A DIFFERENTIAL UNIT FOR EFFICIENT TRANSFER OF TORQUE TO VEHICLE WHEELS AND ASSOCIATED DRIVETRAIN

Abstract

A differential unit (104) that provides superior traction abilities to vehicle wheels on different types of terrains is provided. The differential unit (104) includes a clutch pack (522), one or more push rods (544), a dog clutch (524), a ball ramp unit (526), and a motor (124). The motor (124) is adapted to rotate a rotating ball ramp (528) of the ball ramp unit (526) in a first direction (1502) or in a second direction (1504) for operating the differential unit (104) in an electronic limited slip differential (ELSD) mode or in a differential lock mode, respectively. Rotation of the rotating ball ramp (528) in the first direction (1502) compresses the clutch pack (522) in the ELSD mode. Rotation of the rotating ball ramp (528) in the second direction (1504) causes the dog clutch (524) to engage with a side gear (520) in the differential lock mode. FIG. 6

Specification

Description:RELATED ART


[0001] Embodiments of the present specification relate generally to a drivetrain of a vehicle, and more particularly to a drivetrain that includes a differential unit that selectively operates the vehicle in one of an open differential mode, an electronic limited slip differential mode, and a differential lock mode.
[0002] Generally, vehicle wheels tend to slip when vehicles navigate on low traction surfaces such as on snowy or icy roads, and wet or muddy terrains. Slippage of the vehicle wheels may also occur due to various other reasons such as due to poor road conditions, rash driving, overinflated tires that decrease the tire's grip on the road, and improper mounting of the tires. Such slippage may cause the vehicle to skid or rollover, which may be fatal to the driver and passengers of the vehicle.
[0003] In order to address the aforementioned issues, conventional vehicles use either one or two differentials selected from a group of an open differential, an electronic limited slip differential, and a differential lock. Each of these differentials have associated advantages and limitations. For example, the open differential includes a mechanism that performs a differential action during vehicle cornering events and allows inner and outer wheels to spin at different speeds to provide more traction to the wheels during such events. However, the open differential transmits power to the wheels with least resistance, which causes one of the wheels to spin ineffectively when the vehicle navigates on a low traction surface.
[0004] Further, the electronic limited slip differential provides efficient torque distribution to the wheels and offers improved traction and enhanced vehicle stability, thus being more suitable for driving the vehicle on highways, and wet, and icy terrains. However, the electronic limited slip differential generally fails to optimally transfer the torque to the wheels especially in extremely rough terrains such as on off-road terrains. In contrast, the differential lock distributes an equal amount of power to the wheels, and provides superior traction abilities in off-road and towing conditions. However, the differential lock provides increased traction that introduces stresses on the vehicle's geartrain components, which leads to early wear and tear of the geartrain components.
[0005] Many of the present-day vehicles employ either a combination of open and electronic limited slip differentials or a combination of open and lock differentials, both of which cause the wheels of the vehicles to not obtain adequate traction on all kind of terrains. For example, the vehicles that employ the combination of open and electronic limited slip differentials may not be able to offer superior traction abilities in off-road and towing conditions. Similarly, the vehicles that employ the combination of open and lock differentials may not be able to offer superior traction abilities on highways, and wet, and icy terrains.
[0006] Accordingly, there remains a need for a differential unit that is capable of selectively operating a vehicle in all three modes including an open differential mode, an electronic limited slip differential mode, and a differential lock mode on need basis to offer superior traction abilities to wheels of the vehicle on all kinds of terrains.


BRIEF DESCRIPTION


[0007] It is an objective of the present disclosure to provide a differential unit of a vehicle. The differential unit includes a clutch pack, one or more push rods operatively coupled to the clutch pack, a dog clutch operatively coupled to the one or more push rods, a ball ramp unit, and a motor. The ball ramp unit includes a rotating ball ramp, a sliding ball ramp operatively coupled to the one or more push rods, and one or more ramp balls arranged between the rotating ball ramp and the sliding ball ramp. The motor is operatively coupled to the ball ramp unit and a control unit in the vehicle. The motor is adapted to rotate the rotating ball ramp in a first direction based on a first instruction from the control unit to switch an operational mode of the differential unit from an open differential mode to an electronic limited slip differential mode. The motor is adapted to rotate the rotating ball ramp in a second direction opposite to the first direction based on a second instruction from the control unit to switch the operational mode of the differential unit from the open differential mode to a differential lock mode. The rotation of the rotating ball ramp in the first direction moves the one or more push rods linearly towards the clutch pack and compresses the clutch pack to a compressed state, thereby disposing the differential unit in the electronic limited slip differential mode. The rotation of the rotating ball ramp in the second direction moves the one or more push rods linearly away from the clutch pack and further causes the dog clutch to engage with a side gear, thereby disposing the differential unit in the differential lock mode.
[0008] The rotating ball ramp and the sliding ball ramp include one or more extended grooves and one or more matching grooves, respectively of a variable depth. Each of the one or more extended grooves of the rotating ball ramp includes a first intermediate depth region of a first depth, a first minimum depth region of a second depth, and a first maximum depth region of a third depth. Each of the one or more matching grooves of the sliding ball ramp includes a second intermediate depth region of the first depth, a second minimum depth region of the second depth, and a second maximum depth region of the third depth. The second depth is lesser than the first depth and the third depth is greater than the first depth and the second depth. Values of the first depth, the second depth, and the third depth are selected based on one or more of a type and a model of the vehicle.
[0009] The dog clutch includes a plurality of holes disposed on an exterior surface of the dog clutch. The differential unit includes one or more coil springs disposed between a spring mount sleeve and the holes of the dog clutch in a semi-compressed state when the differential unit is disposed in the open differential mode. The one or more ramp balls are arranged between the first intermediate depth region and the second intermediate depth region of the one or more extended grooves and the one or more matching grooves, respectively. The dog clutch is disposed in a non-pushed position and is engaged with the one or more push rods when the differential unit is disposed in the open differential mode. The control unit is communicatively coupled to an onboard sensor unit. The control unit corresponds to one or more electronic control units in the vehicle. The onboard sensor unit includes one or more of a vehicle speed sensor that measures a speed of the vehicle, one or more wheel speed sensors that measure a speed of a right wheel and a speed of a left wheel of the vehicle, a steering angle sensor that measures a steering angle of the vehicle, a yaw sensor that measures a yaw angle of the vehicle, and a throttle position sensor that measures a position of a throttle of the vehicle. The control unit disposes the differential unit in the open differential mode when the measured speed of the vehicle is greater than a designated vehicle speed threshold and a difference between the speed of the right wheel and the speed of the left wheel of the vehicle is within a first threshold range.
[0010] The motor is adapted to rotate the rotating ball ramp in the first direction when the measured speed of the vehicle is greater than the designated vehicle speed threshold and the difference between the speed of the right wheel and the speed of the left wheel of the vehicle corresponds to a value that falls within a second threshold range that is different from the first threshold range. The one or more ramp balls are adapted to move from the first and second intermediate depth regions to the first and second minimum depth regions upon rotation of the rotating ball ramp in the first direction, which linearly moves the sliding ball ramp and the one or more push rods towards the clutch pack, and thereby linearly moving the one or more push rods to push a pressure disc, which compresses the clutch pack to the compressed state, thereby switching the operational mode of the differential unit from the open differential mode to the electronic limited slip differential mode. The linear movement of the one or more push rods is adapted to push the dog clutch from the non-pushed position to a pushed position, thereby compressing the one or more coil springs to a fully compressed state when the differential unit is disposed in the electronic limited slip differential mode.
[0011] The control unit instructs the motor to rotate the rotating ball ramp in the second direction when the measured speed of the vehicle is greater than the designated vehicle speed threshold and the difference between the speed of the right wheel and the speed of the left wheel of the vehicle corresponds to a value that falls within the first threshold range. The one or more ramp balls are adapted to move back to the first and second intermediate depth regions upon rotation of the rotating ball ramp in the second direction, which disposes the sliding ball ramp in an associated original center position, which in turn moves the one or more push rods linearly away from the clutch pack and disposes the clutch pack in an original uncompressed state, thereby switching the operational mode of the differential unit to the open differential mode from the electronic limited slip differential mode. The linear movement of the one or more push rods away from the clutch pack is adapted to expand the one or more coil springs to the semi-compressed state, which pushes the dog clutch to the non-pushed position when the differential unit is switched to the open differential mode from the electronic limited slip differential mode.
[0012] The motor is adapted to rotate the rotating ball ramp in the second direction when the measured speed of the vehicle is lesser than the designated vehicle speed threshold and the difference between the speed of the right wheel and the speed of the left wheel of the vehicle is greater than a second threshold range that is different from the first threshold range. The one or more ramp balls are adapted to move from the first and second intermediate depth regions to the first and second maximum depth regions upon rotation of the rotating ball ramp in the second direction, which moves the sliding ball ramp and the one or more push rods to move linearly away from the clutch pack. The linear movement of the one or more push rods is adapted to expand the one or more coil springs from the semi-compressed state to a fully extended state, thereby engaging the dog clutch to the side gear, which switches the operational mode of the differential unit from the open differential mode to the differential lock mode. The motor is adapted to rotate back the rotating ball ramp in the first direction when the measured speed of the vehicle corresponds to a value greater than the designated vehicle speed threshold and the difference between the speed of the right wheel and the speed of the left wheel of the vehicle corresponds to a value that falls within the first threshold range. The one or more ramp balls are adapted to move to the first and second intermediate depth regions upon rotation of the rotating ball ramp in the first direction, which disposes the sliding ball ramp in the associated original center position, pushes the one or more push rods and the dog clutch, and compresses the one or more coil springs to the semi-compressed state, thereby switching the operational mode of the differential unit to the open differential mode from the differential lock mode.
[0013] The vehicle includes a differential mode selection unit that allows a user to manually select the operational mode of the differential unit. The differential mode selection unit corresponds to one or more of a switch, a button, a knob, a touch input device, a gesture recognition device, a display device, and a human-machine interface residing in the vehicle. The motor corresponds to a brushless direct current motor. The differential unit is integrated into a drivetrain of the vehicle. The vehicle corresponds to one of an internal combustion engine powered vehicle, a hybrid vehicle, and an electric vehicle. The differential unit is retrofittable to a drivetrain of the vehicle. The vehicle corresponds to one of an internal combustion engine powered vehicle, a hybrid vehicle, and an electric vehicle.


BRIEF DESCRIPTION OF DRAWINGS


[0014] These and other features, aspects, and advantages of the claimed subject matter will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
[0015] FIG. 1 illustrates a block diagram depicting an exemplary architecture of an internal combustion engine (ICE) powered 4x2 axle configuration vehicle including a differential unit, in accordance with aspects of the present disclosure;
[0016] FIG. 2 illustrates a block diagram depicting an exemplary architecture of an ICE powered 4x4 axle configuration vehicle including the differential unit of FIG. 1, in accordance with aspects of the present disclosure;
[0017] FIG. 3 illustrates a block diagram depicting an exemplary architecture of a two-motor electric all-wheel drive vehicle including the differential unit of FIG. 1, in accordance with aspects of the present disclosure;
[0018] FIG. 4 illustrates a block diagram depicting an exemplary architecture of an all-wheel drive hybrid vehicle including the differential unit of FIG. 1, in accordance with aspects of the present disclosure;
[0019] FIG. 5 illustrates a cross-sectional view of the differential unit of FIG. 1, in accordance with aspects of the present disclosure;
[0020] FIG. 6 illustrates an exploded view depicting various exemplary components of the differential unit of FIG. 1, in accordance with aspects of the present disclosure;
[0021] FIG. 7 illustrates a side perspective view of a clutch pack in the differential unit of FIG. 1, in accordance with aspects of the present disclosure;
[0022] FIG. 8 illustrates a cross-sectional view of a differential cover of the differential unit of FIG. 1, in accordance with aspects of the present disclosure;
[0023] FIG. 9 illustrates a cross-sectional view of the differential unit of FIG. 1 depicting coil springs placed between a spring mount sleeve and holes of a dog clutch in the differential unit, in accordance with aspects of the present disclosure;
[0024] FIG. 10 illustrate side views of a rotating ball ramp and a sliding ball ramp in the differential unit of FIG. 1, in accordance with aspects of the present disclosure;
[0025] FIG. 11 illustrates an exemplary view depicting ramp balls positioned between the rotating ball ramp and the sliding ball ramp of FIG. 10 during an operation of the differential unit of FIG. 1 in an open differential mode, in accordance with aspects of the present disclosure;
[0026] FIG. 12 illustrates a cross-sectional view of a portion of the differential unit of FIG. 1 operating in the open differential mode, in accordance with aspects of the present disclosure;
[0027] FIG. 13 illustrates a cross-sectional view of a portion of the differential unit of FIG. 1 operating in the open differential mode with associated coil springs disposed in an original state, in accordance with aspects of the present disclosure;
[0028] FIG. 14 illustrates a cross-sectional view of a portion of the differential unit of FIG. 1 operating in the open differential mode and adapted to transfer torque to one or more wheels of the vehicle, in accordance with aspects of the present disclosure;
[0029] FIG. 15 illustrates an exemplary view depicting ramp balls positioned between the rotating ball ramp and the sliding ball ramp during an operation of the differential unit of FIG. 1 in an electronic limited slip differential (ELSD) mode, in accordance with aspects of the present disclosure;
[0030] FIG. 16 illustrates a cross-sectional view of a portion of the differential unit of FIG. 1 operating in the ELSD mode, in accordance with aspects of the present disclosure;
[0031] FIG. 21 illustrates a cross-sectional view of a portion of the differential unit of FIG. 1 operating in the ELSD mode with associated coil springs disposed in a fully compressed state, in accordance with aspects of the present disclosure;
[0032] FIG. 18 illustrates a cross-sectional view of a portion of the differential unit of FIG. 1 operating in the ELSD mode and adapted to transfer torque to one or more wheels of the vehicle, in accordance with aspects of the present disclosure;
[0033] FIG. 19 illustrates an exemplary view depicting ramp balls positioned between the rotating ball ramp and the sliding ball ramp during an operation of the differential unit of FIG. 1 in a differential lock mode, in accordance with aspects of the present disclosure;
[0034] FIG. 20 illustrates a cross-sectional view of a portion of the differential unit of FIG. 1 operating in the differential lock mode, in accordance with aspects of the present disclosure;
[0035] FIG. 21 illustrates a cross-sectional view of a portion of the differential unit of FIG. 1 operating in the differential lock mode with associated coil springs disposed in a fully extended state, in accordance with aspects of the present disclosure; and
[0036] FIG. 22 illustrates a cross-sectional view of a portion of the differential unit of FIG. 1 operating in the differential lock mode and adapted to transfer torque to one or more wheels of the vehicle, in accordance with aspects of the present disclosure.


DETAILED DESCRIPTION


[0037] The following description presents an exemplary drivetrain of a vehicle. Particularly, embodiments described herein disclose a drivetrain that includes a differential unit that selectively operates in one of an open differential mode, an electronic limited slip differential (ELSD) mode, and a differential lock mode. Specifically, the differential unit includes a set of custom components including a ball ramp unit and a differential lock dog clutch that enable the differential unit to seamlessly switch between one of the open differential, ELSD, and differential lock modes to prevent wheel slippage and further to offer superior traction abilities to the wheels on all kinds of terrains.
[0038] As noted previously, conventional vehicles either include only the open differential, or a combination of the open and ELSD differentials or the open and lock differentials, which often fail to provide adequate traction to wheels of a vehicle on all kinds of terrains. In contrast, the differential unit described in the present disclosure ensures that adequate traction is provided to the wheels of the vehicle on all kinds of terrains, which ensures the safety of the vehicle, driver, and the passengers.
[0039] In certain embodiments, the differential unit described in the present disclosure may be deployed in different types of vehicles such as in internal combustion engine (ICE) powered vehicles, electric vehicles, and hybrid vehicles to ensure optimized torque transfer to wheels of those vehicles during various driving conditions. Specific examples of such vehicles include pickup trucks, sport utility vehicles, passenger cars, and commercial fleets. Though the present differential unit can be deployed in different types of the vehicles, certain embodiments of the differential unit are described herein in greater detail with reference to associated deployment in ICE powered and hybrid vehicles.
[0040] Particularly, FIGS. 1-4 illustrate block diagrams depicting architectures of various types of vehicles. For example, FIG. 1 illustrates a block diagram depicting an architecture of an ICE powered 4x2 axle configuration vehicle (100), which includes a drivetrain (102) that, in turn, includes an enhanced differential unit (104). In certain embodiments, the differential unit (104) is deployed in a rear axle (106) of the vehicle (100) for better handling, stability, increasing vehicle performance, and achieving enhanced traction on different types of terrains. However, it is be understood that the differential unit (104) may alternatively be deployed in a front axle (108) of the vehicle (100). As further depicted in FIG. 1, the vehicle (100) includes an engine (110) that is operatively coupled to a transmission (112). The transmission (112), in turn, is operatively coupled to the drivetrain (102) including the differential unit (104).
[0041] In certain embodiments, the differential unit (104) operates in an open differential mode by default. A control unit (114) residing in the vehicle (100) switches an operation of the differential unit (104) from the open differential mode to either an ELSD mode or a differential lock mode on need basis based on one or more inputs received from an onboard sensor unit (116). An example of the control unit (114) includes one or more electronic control units of the vehicle (100). The onboard sensor unit (116) includes one or more sensors (118A-E) such as a vehicle speed sensor (118A), one or more wheel speed sensors (118B), a steering angle sensor (118C), a yaw sensor (118D), and a throttle position sensor (118E).
[0042] Specifically, the control unit (114) receives sensor values from the onboard sensor unit (116) such as a speed of the vehicle (100) from the vehicle speed sensor (118A), a speed of a right wheel (122A) and a speed of a left wheel (122B) from the one or more wheel speed sensors (118B), and a steering angle of the vehicle (100) from the steering angle sensor (118C). The control unit (114) additionally receives a yaw angle of the vehicle (100) from the yaw sensor (118D) and a position of a throttle of the vehicle (100) from the throttle position sensor (118E). Based on these sensor values received from the onboard sensor unit (116), the control unit (114) selects and activates an operational mode of the differential unit (104).
[0043] For instance, the control unit (114) operates the differential unit (104) in the open differential mode when the speed of the vehicle (100) is greater than a designated vehicle speed threshold, and a difference between the speed of the right wheel (122A) and the speed of the left wheel (122B) of the vehicle (100) is within a first threshold range. When the difference in wheel speeds falls within the first threshold range, the control unit (114) identifies that a sufficient amount of traction is available to the wheels (122A-B) of the vehicle (100). Hence, the control unit (114) operates the differential unit (104) in the open differential mode, and does not switch the operational mode to the ELSD mode or differential lock mode. Additionally, the control unit (114) uses the other sensor values such as the steering angle of the vehicle (100), the yaw angle of the vehicle (100), and the position of the throttle of the vehicle (100) to identify if the differential unit (104) needs to be operated in the open differential mode.
[0044] In certain embodiments, the control unit (114) switches the operational mode of the differential unit (104) from the open differential mode to the ELSD mode when the speed of the vehicle (100) is greater than the designated vehicle speed threshold, and further when a difference between the speeds of the right and left wheels (122A-B) of the vehicle (100) increases to a value that falls within a second threshold range different from the first threshold range. In one embodiment, the second threshold range is greater than the first threshold range. A difference in wheel speeds that falls within the second threshold range indicates to the control unit (114) that the vehicle (100) is currently navigating on a slippery terrain such as on a wet, icy, or snowy terrain and at least one of the wheels (122A-B) of the vehicle (100) is losing traction. Consequently, the control unit (114) controls an operation of a custom motor (124) coupled to the drivetrain (102) to automatically switch the operational mode of the differential unit (104) from the open differential mode to the ELSD mode, as described in detail with reference to FIGS. 15-18. An example of the custom motor (124) that is added to the drivetrain (102) includes a brushless direct current motor.
[0045] In addition to using the sensor values such as the speed of the vehicle (100) and the difference in the speeds of the right and left wheels (122A-B), the control unit (114) also uses the other sensor values such as the steering and yaw angles of the vehicle (100), and the position of the throttle of the vehicle (100) to identify if the differential unit (104) needs to be switched to the ELSD mode. In one embodiment, the control unit (114) switches back the operational mode of the differential unit (104) from the ELSD mode to the open differential mode when the speed of the vehicle (100) is greater than the designated vehicle speed threshold, and further when the difference between the speeds of the right and left wheels (122A-B) of the vehicle (100) reduces to a value that falls within the first threshold range.
[0046] In certain embodiments, the control unit (114) controls the operation of the motor (124) to switch the operational mode of the differential unit (104) from the open differential mode to the differential lock mode, as described in detail with reference to FIGS. 19-22. Specifically, the control unit (114) switches the operational mode to the differential lock mode when the speed of the vehicle (100) decreases to a value lesser than the designated vehicle speed threshold, and further when the difference between the speeds of the right and left wheels (122A-B) of the vehicle (100) increases to a value greater than an upper limit of the second threshold range. Further, the control unit (114) switches the operational mode to the differential lock mode only when an off-road driving mode is manually enabled by a user, for example, using a differential mode selection unit (126). Examples of the differential mode selection unit (126) include a switch, a button, a knob, a touch input device, a gesture recognition device, a display device, or a human-machine interface residing in the vehicle (100). In certain embodiments, the control unit (114) switches back the operational mode of the differential unit (104) to the open differential mode when the user disables the off-road driving mode, the speed of the vehicle (100) increases back to a value greater than the designated vehicle speed threshold, and the difference between the speeds of the right and left wheels (122A-B) of the vehicle (100) reduces back to a value that falls within the first threshold range.
[0047] In certain embodiments, the values associated with the first threshold range and the second threshold range vary based on the speed of the vehicle (100) at a particular instant of time and a condition of the road on which the vehicle (100) is navigating. For example, the value of the first threshold range may correspond to 0-20 revolutions per minute (RPM) and the value of the second threshold range may correspond to 21-100 RPM when the vehicle (100) is cornering at the speed of 80 kilometers per hour. However, the value of the first threshold range may correspond to 0-25 RPM and the value of the second threshold range may correspond to 26-110 RPM when the vehicle (100) is navigating on a straight road at the speed of 90 kilometers per hour.
[0048] FIG. 2 illustrates a block diagram depicting an exemplary implementation of the differential unit (104) in a different vehicle corresponding to an ICE powered 4x4 axle configuration vehicle (200). It may be noted that the architecture of the ICE powered 4x4 axle configuration vehicle (200) is similar to the architecture of the ICE powered 4x2 axle configuration vehicle (100) except that the vehicle (200) additionally includes a front axle drivetrain (202) and a transfer case (204). In this implementation, the engine (110) is operatively coupled to the transmission (112), which in turn, is coupled to the transfer case (204). The transfer case (204) splits the power from the engine (110) and transmits the power to both the front axle drivetrain (202) and the rear axle drivetrain (102) through a connecting shaft (206) and a propeller shaft (208), respectively.
[0049] Further, FIG. 3 illustrates a block diagram depicting an exemplary implementation of the differential unit (104) in another vehicle corresponding to a two-motor electric all-wheel drive vehicle (300). It may be noted that the architecture of the vehicle (300) includes certain differences with respect to the architecture of the vehicle (100). For example, the vehicle (300) includes front and rear axles electric drive units (302A-B), which are absent in the architecture of the vehicle (100). Further, the vehicle (300) lacks certain components such as the internal combustion engine (110) and the ICE transmission (112) that are present in the architecture of the ICE vehicle (100). Though there are certain differences that exist between the architectures of the vehicles (100 and 300), it is to be understood that components and functions of the differential unit (104) used in the ICE vehicle (100) will be same as components and functions of the differential unit (104) in the electric vehicle (300).
[0050] FIG. 4 illustrates a block diagram depicting an exemplary implementation of the differential unit (104) in yet another vehicle corresponding to an all-wheel drive hybrid vehicle (400). It may be noted that the architecture of the hybrid vehicle (400) includes certain differences with respect to the architecture of the electric vehicle (300). For example, the vehicle (400) includes components such as an internal combustion engine (402) and an ICE transmission (404) instead of the front axle electric drive unit (302A) in the electric vehicle (300). Though the differences exist in the architectures of the vehicles (300 and 400), it is to be understood that components and functions of the differential unit (104) in the hybrid vehicle (400) will be same as components and functions of the differential unit (104) in the electric vehicle (300).
[0051] In certain embodiments, the differential unit (104) includes a plurality of associated components that enable the differential unit (104) to seamlessly switch between a plurality of differential modes including the open differential, ELSD, and differential lock modes. For example, FIGS. 5-9 depict such exemplary components of the differential unit (104) that are connected to each other for enabling the differential unit (104) to selectively switch between the plurality of modes. Specifically, FIG. 5 illustrates a cross-sectional view of the differential unit (104). As depicted in FIG. 5, the differential unit (104) includes a differential case (502) that receives power from a prime mover (not shown in FIGS) of the vehicle (100) through an input ring gear (504). In certain embodiments, the input ring gear (504) is fixed to a differential housing (506), for example, by welding or using splines or fasteners.
[0052] In one embodiment, the differential case (502) corresponds to a casing that combines the differential housing (506) and a differential cover (508) together, for example, by welding. Further, the differential case (502) supports a first tapper roller bearing (510) at an associated one end. Moreover, the differential case (502) supports a second tapper roller bearing (512) at an associated another end. In certain embodiments, the differential case (502) transmits the power received from the prime mover to a spider gear (514) that is concentric and includes a spider pin (516) and split spider pins (602) (depicted in FIG. 6). In one embodiment, the spider pin (516) is fixed on the differential case (502) and is operatively coupled to a first side gear (518) of the spider gear (514). The split spider pins (602) are fixed on the differential case (502) and are operatively coupled to a second side gear (520) of the spider gear (514).
[0053] In certain embodiments, the spider gear (514) transfers the power received from the prime mover to the wheel (122A) via a rear axle right-side shaft (128) (shown in FIG. 1) and further to the wheel (122B) via a rear axle left-side shaft (130) (shown in FIG. 1). Further, the differential unit (104) includes a clutch pack (522), a dog clutch (524), and a ball ramp unit (526) for actuating the ELSD and differential lock modes of the differential unit (104). In one embodiment, the clutch pack (522) includes one or more plates including a metal plate (702) and a friction plate (704) (depicted in FIG. 7). The metal plate (702) includes outer splines (706) that engage with internal splines (604) of the differential case (502) when various components of the differential unit (104) are assembled together. Similarly, the friction plate (704) includes internal splines (708) that engage with the outer spline (606A) selected from the outer splines (606A-B) of the second side gear (520) when various components of the differential unit (104) are assembled together. Additionally, the outer splines (606B) of the second side gear (520) also engage with internal splines (608) in the dog clutch (524) when various components of the differential unit (104) are assembled together to enable the dog clutch (524) to switch the differential unit (104) to the differential lock mode.
[0054] In one embodiment, the dog clutch (524) also includes outer teeth (610) that are always in an engaged state with respect to dog clutch teeth (802) (shown in FIG. 8) of the differential cover (508), which enables the dog clutch (524) to switch the differential unit (104) to the differential lock mode based on the sensor values measured by the vehicle and wheel speed sensors (118A-B), as described previously with reference to FIG. 1. Further, the differential unit (104) additionally includes a ball ramp unit (526) that, in turn, includes a rotating ball ramp (528) and a sliding ball ramp (530) to switch the operational mode of the differential unit (104) to the differential lock mode and to the ELSD mode from the open differential mode. In one embodiment, the rotating ball ramp (528) is fixedly coupled to the differential case (502) through an angular contact ball bearing (536) in all three operational modes of the differential unit (1040, including the open differential mode, the ELSD mode, and the differential lock mode. In particular, the rotating ball ramp (528) is rotationally coupled to the motor (124) (shown in FIG. 1) and exhibits rotational motion when the operational mode of the differential unit (104) is switched from the open differential mode to the ELSD mode and/or the differential lock mode. In contrast to the rotating ball ramp (528), the sliding ball ramp (530) exhibits linear motion and moves linearly either along a first direction (532) towards the clutch pack (522) or along a second direction (534) away from the clutch pack (522) by the actuation of ramp balls (612) for enabling the differential unit (104) to operate in the ELSD mode and the differential lock, respectively.
[0055] In one embodiment, the ball ramp unit (526) is supported by the angular contact ball bearing (536), which is mounted on the differential cover (508) in all three operational modes of the differential unit (104). Further, the sliding ball ramp (530) of the ball ramp unit (526) includes a needle bearing setup (538) placed between the sliding ball ramp (530) and the differential cover (508) in all three operational modes of the differential unit (104). The needle bearing setup (538) includes a needle bearing (540) and a bearing mount (542), which push one or more push rods (544) arranged inside holes (614) of the differential cover (508) for activating the ELSD mode. Furthermore, a spring mount sleeve (546) is rigidly fixed between the differential housing (506) and the differential cover (508). The spring mount sleeve (546) supports one end of a plurality of coil springs (616), which are used for switching back the differential unit (104) from the ELSD mode to the open differential mode and further from the open differential mode to the differential lock mode. The other end of the plurality of coil springs (616) are supported by holes (902) in the dog clutch (524), as depicted in FIG. 9. Thus, in certain embodiments, the coil springs (616) are arranged between the spring mount sleeve (546) and the holes (902) in the dog clutch (524) when various components of the differential unit (104) are assembled together and are placed in a semi-compressed state by default in the open differential mode.
[0056] In one embodiment, the dog clutch (524) is a custom component that is different from clutches that are usually present in conventional differential units. Specifically, the dog clutch (524) includes a special provision of holes (902) for accommodating the coil springs (616), as depicted in FIG. 9. The holes (902) prevent the coil springs (616) from exhibiting rotational motion during various operational modes of the differential unit (104). Further, the holes (902) act as guiding surfaces that guide linear compression and expansion of the coil springs (616) during switching of the differential unit (104) to the ELSD mode and to the differential lock mode, respectively. Moreover, the holes (902) also help in making an overall dimension of the differential unit (104) compact. For example, in an alternatively contemplated design, the coil springs (616) will need to be positioned between the spring mount sleeve (546) and an exterior surface (904) of the dog clutch (524) if the special provision of holes (902) is not provided in the dog clutch (524). Such positioning of the coil springs (616) between the spring mount sleeve (546) and the exterior surface (904) of the dog clutch (524) will increase the overall dimension of the differential unit (104). In order to address the aforementioned issue, the holes (902) are made in the dog clutch (524), and the coil springs (616) are placed between those holes (902) and the spring mount sleeve (546), which reduces the overall dimension of the differential unit (104).
[0057] In certain embodiments, the differential unit (104) operates in the open differential mode by default, as noted previously. The differential unit (104) either switches from the open differential mode to the ELSD mode or to the differential lock mode on need basis using the ball ramp unit (526). Specific subcomponents of the ball ramp unit (526) that allow the differential unit (104) to switch between the plurality of modes are depicted and described subsequently with reference to FIG. 10.
[0058] FIG. 10 illustrates a perspective view depicting the exemplary rotating and sliding ball ramps (528 and 530) in the ball ramp unit (526). Specifically, the rotating ball ramp (528) includes one or more extended grooves (1002A) of variable depths. Each of the extended grooves (1002A) includes a first intermediate depth region (1004A) having a first depth. Further, each of the extended grooves (1002A) includes a first minimum depth region (1006A) having a second depth that is lesser than the first depth. It may be noted from FIG. 10 that the depths of the extended grooves (1002A) gradually decrease from the first intermediate depth region (1004A) towards the first minimum depth region (1006A) such that the depths of the extended grooves (1002A) are minimum at the first minimum depth region (1006A). Moreover, each of the extended grooves (1002A) also includes a first maximum depth region (1008A) having a third depth that is greater than both the first depth and the second depth. It may be noted from FIG. 10 that the depths of the extended grooves (1002A) gradually increase from the first intermediate depth region (1004A) towards the first maximum depth region (1008A) such that the depths of the extended grooves (1002A) are maximum at the first maximum depth region (1008A).
[0059] It may also be noted from FIG. 10 that the sliding ball ramp (530) also includes grooves whose profiles are exactly same as profiles of the extended grooves (1002) of the rotating ball ramp (528). Specifically, the sliding ball ramp (530) includes matching grooves (1002B) that match with the extended grooves (1002A) when various components of the differential unit (104) are assembled together. Similar to the rotating ball ramp (528), each of the matching grooves (1002B) of the sliding ball ramp (530) includes a second intermediate depth region (1004B) of the first depth, a second minimum depth region (1006B) of the second depth that is lesser than the first depth, and a second maximum depth region (1008B) of the third depth that is greater than both the first depth and the second depth. In one embodiment, the first, second, and third depths of the intermediate depth regions (1004A-B), the minimum depth regions (1006A-B), and the maximum depth regions (1008A-B), respectively, are selected based on a distance by which the sliding ball ramp (530) needs to be linearly moved during activation of the ELSD and differential lock modes. The first, second, and third depths are also selected based on a vehicle type in which the different unit (104) is ultimately to be deployed. The first, second, and third depths may vary from one vehicle to another vehicle to handle different axle torque outputs.
[0060] When the differential unit (104) initially operates in the open differential mode, the one or more ramp balls (612) are positioned between the first and second intermediate depth regions (1004A-B) of the extended and matching grooves (1002A-B), respectively, as depicted in FIG. 11. Further, the push rods (544) are engaged with the dog clutch (524), which is placed in a non-pushed position (1202) when the differential unit (104) operates in the open differential mode, as depicted in FIG. 12. Additionally, one end (1204) of each of the push rods (544) is secured against a pressure disc (1206), as depicted in FIGS. 12 and 13. Moreover, the coil springs (616) are arranged in an original state (1302) corresponding to a semi-compressed state between the spring mount sleeve (546) and the holes (902) in the dog clutch (524) when all components of the differential unit (104) are assembled together, as depicted in FIG. 13.
[0061] When the differential unit (104) operates in the open differential mode, the input ring gear (504) transfers the power from the prime mover of the vehicle (100) to the differential housing (506) and further to the spider gear (514), as depicted in FIG. 14. The spider gear (514) then transfers the power to the first and second side gears (518 and 520). Further, the spider gear (514) transfers the power to the rear axle's right-side and left-side shafts (128 and 130), which allow smooth transfer of torque to the wheels (122A-B) of the vehicle (100). However, if the differential unit (104) is allowed to operate in only the open differential mode, one or more of the wheels (122A-B) may slip when the wheels (122A-B) include less or no traction to transfer differential torque. In such scenarios, the differential unit (104) automatically switches from the open differential mode to the ELSD mode to prevent slippage of one or more of the wheels (122A-B). Specifically, the differential unit (104) automatically switches to the ELSD mode when the speed of the vehicle (100) is greater than the designated vehicle speed threshold, and further when the difference between the speeds of the right and left wheels (122A-B) of the vehicle (100) corresponds to a value that falls within the second threshold range, as noted previously with reference to FIG. 1.
[0062] In one embodiment, the differential unit (104) automatically switches from the open differential mode to the ELSD mode using the motor (124) that is rotationally coupled to the rotating ball ramp (528). To switch the operational mode to the ELSD mode, the control unit (114) provides a first instruction to the motor (124) to rotate the rotating ball ramp (528) in a first direction (1502), for example, corresponding to a clockwise direction (1502) (depicted in FIG. 15). The rotation of the rotating ball ramp (528) in the clockwise direction (1502) causes the ramp balls (612) to roll from the first and second intermediate depth regions (1004A-B) to the first and second minimum depth regions (1006A-B) of the extended and matching grooves (1002A-B), respectively. The movements of the ramp balls (612) from the first and second intermediate depth regions (1004A-B) to the first and second minimum depth regions (1006A-B) cause the sliding ball ramp (530) to move in a first direction (1602) (shown in FIG. 16), for example, towards the clutch pack (522). The movement of the sliding ball ramp (530) in the first direction (1602) causes the push rods (544) coupled to the sliding ball ramp (530) to move in the same first direction (1602) and further causes the push rods (544) to push the pressure disc (1206). The pushing of the pressure disc (1206), in turn, pushes and compresses the clutch pack (522) to a compressed state (1604), which activates the ELSD mode of the differential unit (104).
[0063] Further, the movements of the ramp balls (612) from the first and second intermediate depth regions (1004A-B) to the first and second minimum depth regions (1006A-B) also cause the push rods (544) to push the dog clutch (524) from the non-pushed position (1202) to a pushed position (1606) (clearly visible in FIG. 17). The pushing of the dog clutch (524) to the pushed position (1606) compresses the coil springs (616) from the original state (1302) to a fully compressed state (1702), and thereby allows the coil springs (616) to store energy during the ELSD mode.
[0064] Thus, the differential unit (104) switches to the ELSD mode by the compression of the clutch pack (522) to the compressed state (1604), which arrests the side gear (520) with the differential housing (506). The compression of the clutch pack (1604) also transfers the power to one of the rear wheels (122A-B) from the differential case (502). Further, the compression of the clutch pack (522) distributes torque (indicated using arrow marks (1802) in FIG. 18) to the rear wheels (122A-B) and thereby prevents slippage of the rear wheels (122A-B).
[0065] In certain embodiments, the differential unit (104) switches back to the open differential mode when the speed of the vehicle (100) is greater than the designated vehicle speed threshold, and further when the difference between the speeds of the right and left wheels (122A-B) of the vehicle (100) corresponds to a value that falls within the first threshold range, as noted previously with reference to FIG. 1. To that end, the control unit (114) instructs the motor (124) to rotate the rotating ball ramp (528) in a second direction (1504), for example, corresponding to an anti-clockwise direction (1504) (depicted in FIG. 15). The rotation of the rotating ball ramp (528) in the anti-clockwise direction (1504) causes the ramp balls (612) to roll back from the first and second minimum depth regions (1006A-B) to the first and second intermediate depth regions (1004A-B). Consequently, the sliding ball ramp (530) moves back in a second direction opposite to the first direction (1602) to subsequently be disposed in an associated original center position (1208) (shown in FIG. 12). The movement of the sliding ball ramp (530) to the associated original center position (1208) causes the push rods (544) to move in the same second direction and further to release the clutch pack (522) from the compressed state (1604) to an original uncompressed state. The release of the clutch pack (522) to the original uncompressed state switches the operational mode of the differential unit (104) back to the open differential mode.
[0066] Further, when the differential mode switches back to the open differential mode from the ELSD mode, the coil springs (616) release the stored energy and partially expand back to the original state (1302) from the fully compressed state (1702). The expansion of the coil springs (616) to the original state (1302) causes the coil springs (616) to push back the dog clutch (524) to the non-pushed position (1202) from the pushed position (1606), which completes switching back the operational modes of the differential unit (104) from the ELSD mode to the open differential mode.
[0067] In certain embodiments, the differential unit (104) automatically switches from the open differential mode to the differential lock mode when the off-road driving mode is enabled, the speed of the vehicle (100) corresponds to a value lesser than the designated vehicle speed threshold, and the difference between the speeds of the right and left wheels (122A-B) of the vehicle (100) corresponds to a value greater than the upper limit of the second threshold range, as noted previously with reference to FIG. 1. To switch the operation mode of the differential unit (104) to the differential lock mode, the control unit (114) provides a second instruction to the motor (124) to rotate the rotating ball ramp (528), for example, further in the anti-clockwise direction (1504). The rotation of the rotating ball ramp (528) in the anti-clockwise direction (1504) causes the ramp balls (612) to roll from the first and second intermediate depth regions (1004A-B) to the first and second maximum depth regions (1008A-B) of the extended and matching grooves (1002A-B), respectively, as depicted in FIG. 19.
[0068] The movements of the ramp balls (612) from the first and second intermediate depth regions (1004A-B) to the first and second maximum depth regions (1008A-B) cause the sliding ball ramp (530) to move in a second direction (2002) (shown in FIG. 20) away from the clutch pack (522). The movement of the sliding ball ramp (530) in the second direction (2002), in turn, causes the push rods (544) to move in the same second direction (2002). The movement of the push rods (544) in the second direction (2002) causes the coil springs (616) to further expand from the original state (1302) to a fully extended state (2102) (clearly visible in FIG. 21). The expansion of the coil springs (616) to the fully extended state (2102) causes the coil springs (616) to move the dog clutch (524) in the second direction (2002) from the non-pushed position (1202). The movement of the dog clutch (524) in the second direction (2002) causes the dog clutch (524) to be engaged and positioned in a locked position (2004) with the second side gear (520) and further to engage with the differential case (502) (shown in FIG. 5), which activates the differential lock mode of the differential unit (104).
[0069] The engagement of the dog clutch (524) with the differential case (502) and the second side gear (520) causes the differential unit (104) to transfer all hundred percentage of torque (indicated using arrow marks (2202) in FIG. 22) to one of the rear wheels (122A-B) that includes less or no traction for preventing slippage of that particular rear wheel (122A-B). In certain embodiments, the differential unit (104) switches back to the open differential mode when the user disables the off-road driving mode, the speed of the vehicle (100) corresponds to a value greater than the designated vehicle speed threshold, and the difference between the speeds of the right and left wheels (122A-B) of the vehicle (100) corresponds to a value that falls within the first threshold range, as noted previously with reference to FIG. 1.. To that end, the motor (124) rotates back the rotating ball ramp (528), for example, in the clockwise direction (1502). The rotation of the rotating ball ramp (528) in the clockwise direction (1502) causes the ramp balls (612) to roll back to the first and second intermediate depth regions (1004A-B) from the first and second maximum depth regions (1008A-B).
[0070] The movements of the ramp balls (612) to the first and second intermediate depth regions (1004A-B) cause the sliding ball ramp (530) to move back in the first direction (1602) towards the associated original center position (1208). The movement of the sliding ball ramp (530) towards the first direction (1602) also causes the push rods (544) to move back in the first direction (1602). The movement of the push rods (544) in the first direction (1602) pushes or moves the dog clutch (524) back to the non-pushed position (1202), which in turn, causes the coil springs (616) to compress to the original state and to switch back the operational mode of the differential unit (104) to the open differential mode.
[0071] In certain embodiments, the differential unit (104) of the present disclosure can be easily retrofitted to existing vehicles with minimal modifications. For example, the differential unit (104) may be retrofitted by replacing existing differential units in the vehicles with an embodiment of the present differential unit (104) and further by making certain modifications to housings, drivetrain, and/or actuation components of the existing differential units. Further, only minimal changes may need to be made in drivetrain assembly and manufacturing lines in order to integrate the differential unit (104) in any upcoming vehicle variants.
[0072] Examples of such modifications to be made in the existing differential units and/or the drivetrain assembly and manufacturing lines include increasing a dimension of the differential housing (506) in castings. This is because, most of the conventional differential units operate either in a single differential mode or maximum in two different differential modes. However, the differential unit (104) described in the present disclosure is capable of operating in three different differential modes with the help of additional custom components such as the ball ramp unit (526) and the dog clutch (524), which require additional space in the differential housing (506) to accommodate these custom components. Additionally, the control unit (114) needs to be communicatively coupled to the onboard sensor unit (116) for enabling the control unit (114) to receive sensor inputs. Examples of such sensor inputs received by the control unit (114) include the speed of the vehicle (100), the speeds of the right and left wheels (122A-B) of the vehicle (100), the steering and yaw angles of the vehicle (100), and the position of the throttle of the vehicle (100). The control unit (114) then selectively switches the operational mode of the differential unit (104) to a particular differential mode based on the received sensor inputs.
[0073] As noted previously, the differential unit (104) of the present disclosure is capable of operating and seamlessly switching between all three differential modes including the open differential mode, the ELSD mode, and the differential lock mode. Hence, the differential unit (104) provides superior traction to the wheels (122A-B) of the vehicle (100) on different types of terrains such as normal smooth terrains, icy terrains, snowy terrains, highways, wet terrains, and off-road-type terrains. The differential unit (104) efficiently prevents slippage of the wheels (122A-B) on all kinds of terrains, which provide improved safety to the vehicle (100), the driver, and the passengers of the vehicles (100, 200, 300, 400). Further, the differential unit (104) may also be easily retrofitted to the existing vehicles and/or may be easily integrated to new vehicle variants by making only minimal modifications to the assembly and manufacturing lines, which leads to significant cost savings to automotive original equipment manufacturers.
[0074] Although specific features of various embodiments of the present systems and methods may be shown in and/or described with respect to some drawings and not in others, this is for convenience only. It is to be understood that the described features, structures, and/or characteristics may be combined and/or used interchangeably in any suitable manner in the various embodiments shown in the different figures.
[0075] While only certain features of the present systems and methods have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes.



LIST OF NUMERAL REFERENCES:



100 4x2 axle configuration ICE vehicle
200 4x4 axle configuration ICE vehicle
300 Two-motor electric AWD vehicle
400 AWD hybrid vehicle
102, 202 Drivetrain
104 Differential unit
106, 108 Rear and Front axles
110 Engine
112, 404 Transmission
114 Control unit
116 Onboard sensor unit
118A Vehicle speed sensor
118B Wheel speed sensors
118C Steering angle sensor
118D Yaw sensor
118E Throttle position sensor
122A-B Vehicle wheels
124 Motor
126 Differential mode selection unit
128, 130 Rear axle shafts
204 Transfer case
206 Connecting shaft
208 Propeller shaft
302A-B Electric driver units
402 Internal combustion engine
502 Differential case
616 Coil springs
504 Input ring gear
506 Differential housing
508 Differential cover
510, 512 Tapper roller bearings
514 Spider gear
516 Spider pin
518, 520 Side gears
522 Clutch pack
524 Dog clutch
526 Ball ramp unit
528 Rotating ball ramp
530 Sliding ball ramp
532, 534 Sliding ball ramp directions
536 Angular contact ball bearing
538 Needle bearing setup
540 Needle bearing
542 Bearing mount
544 Push rods
546 Spring mount sleeve
602 Split spider pins
604 Differential case internal splines
606A-B Side gear outer splines
608 Dog clutch internal splines
610 Dog clutch outer teeth
612 Ramp balls
614 Differential cover holes
1202 Non-pushed dog clutch position
702 Metal plate
704 Friction plate
706 Metal plate outer splines
708 Friction plate internal splines
802 Differential cover dog clutch teeth
902 Dog clutch holes
904 Dog clutch exterior surface
1002A Extended grooves
1002B Matching grooves
1004A-B Intermediate depth regions
1006A-B Minimum depth regions
1008A-B Maximum depth regions
1204 End of push rods
1206 Pressure disc
1208 Original position of sliding ball ramp
1302 Coil spring in original state
1502, 1504 Rotating ball ramp directions
1602, 2002 Sliding ball ramp directions
1604 Clutch pack in compressed state
1606 Dog clutch in pushed position
1702 Coil spring in fully compressed state
2004 Dog clutch in locked position
1802, 2202 Torque transfer directions

, Claims:We claim:

1. A differential unit (104) of a vehicle (100), comprising:
a clutch pack (522) and one or more push rods (544) operatively coupled to the clutch pack (522);
a dog clutch (524) operatively coupled to the one or more push rods (544);
a ball ramp unit (526) comprising a rotating ball ramp (528), a sliding ball ramp (530) operatively coupled to the one or more push rods (544), and one or more ramp balls (612) arranged between the rotating ball ramp (528) and the sliding ball ramp (530); and
a motor (124) operatively coupled to the ball ramp unit (526) and a control unit (114) in the vehicle (100), wherein the motor (124) is adapted to rotate the rotating ball ramp (528) in a first direction (1502) based on a first instruction from the control unit (114) to switch an operational mode of the differential unit (104) from an open differential mode to an electronic limited slip differential mode, wherein the motor (124) is adapted to rotate the rotating ball ramp (528) in a second direction (1504) opposite to the first direction (1502) based on a second instruction from the control unit (114) to switch the operational mode of the differential unit (104)from the open differential mode to a differential lock mode,
wherein the rotation of the rotating ball ramp (528) in the first direction (1502) moves the one or more push rods (544) linearly towards the clutch pack (522) and compresses the clutch pack (522) to a compressed state (1604), thereby disposing the differential unit (104) in the electronic limited slip differential mode, and wherein the rotation of the rotating ball ramp (528) in the second direction (1504) moves the one or more push rods (544) linearly away from the clutch pack (522) and further causes the dog clutch (524) to engage with a side gear (520), thereby disposing the differential unit (104) in the differential lock mode.

2. The differential unit (104) as claimed in claim 1, wherein the rotating ball ramp (528) and the sliding ball ramp (530) comprise one or more extended grooves (1002A) and one or more matching grooves (1002B), respectively of a variable depth, wherein each of the one or more extended grooves (1002A) of the rotating ball ramp (528) comprises a first intermediate depth region (1004A) of a first depth, a first minimum depth region (1006A) of a second depth, and a first maximum depth region (1008A) of a third depth, wherein each of the one or more matching grooves (1002B) of the sliding ball ramp (530) comprises a second intermediate depth region (1004B) of the first depth, a second minimum depth region (1006A) of the second depth, and a second maximum depth region (1008B) of the third depth, wherein the second depth is lesser than the first depth, and wherein the third depth is greater than the first depth and the second depth, wherein values of the first depth, the second depth, and the third depth are selected based on one or more of a type and a model of the vehicle (100).

3. The differential unit (104) as claimed in claim 2, wherein the dog clutch (524) comprises a plurality of holes (902) disposed on an exterior surface (904) of the dog clutch (524), and wherein the differential unit (104) comprises one or more coil springs (616) disposed between a spring mount sleeve (546) and the holes (902) of the dog clutch (524) in a semi-compressed state (1302) when the differential unit (104) is disposed in the open differential mode.

4. The differential unit (104) as claimed in claim 3, wherein the one or more ramp balls (612) are arranged between the first intermediate depth region (1004A) and the second intermediate depth region (1004B) of the one or more extended grooves (1002A) and the one or more matching grooves (1002B), respectively, and wherein the dog clutch (524) is disposed in a non-pushed position (1202) and is engaged with the one or more push rods (544) when the differential unit (104) is disposed in the open differential mode.

5. The differential unit (104) as claimed in claim 4, wherein the control unit (114) is communicatively coupled to an onboard sensor unit (116), wherein the control unit (114) corresponds to one or more electronic control units in the vehicle (100), wherein the onboard sensor unit (116) comprises one or more of a vehicle speed sensor (118A) that measures a speed of the vehicle (100), one or more wheel speed sensors (118B) that measure a speed of a right wheel (122A) and a speed of a left wheel (122B) of the vehicle (100), a steering angle sensor (118C) that measures a steering angle of the vehicle (100), a yaw sensor (118D) that measures a yaw angle of the vehicle (100), and a throttle position sensor (118E) that measures a position of a throttle of the vehicle (100), wherein the control unit (114) disposes the differential unit (104) in the open differential mode when the measured speed of the vehicle (100) is greater than a designated vehicle speed threshold and a difference between the speed of the right wheel (122A) and the speed of the left wheel (122B) of the vehicle (100) is within a first threshold range.

6. The differential unit (104) as claimed in claim 5, wherein the motor (124) is adapted to rotate the rotating ball ramp (528) in the first direction (1502) when the measured speed of the vehicle (100) is greater than the designated vehicle speed threshold and the difference between the speed of the right wheel (122A) and the speed of the left wheel (122B) of the vehicle (100) corresponds to a value that falls within a second threshold range that is different from the first threshold range, wherein the one or more ramp balls (612) are adapted to move from the first and second intermediate depth regions (1004A-B) to the first and second minimum depth regions (1006A-B) upon rotation of the rotating ball ramp (528) in the first direction (1502), which linearly moves the sliding ball ramp (530) and the one or more push rods (544) towards the clutch pack (522), and thereby linearly moving the one or more push rods (544) to push a pressure disc (1206), which compresses the clutch pack (522) to the compressed state (1604), thereby switching the operational mode of the differential unit (104) from the open differential mode to the electronic limited slip differential mode.

7. The differential unit (104) as claimed in claim 6, wherein the linear movement of the one or more push rods (544) is adapted to push the dog clutch (524) from the non-pushed position (1202) to a pushed position (1606), thereby compressing the one or more coil springs (616) to a fully compressed state when the differential unit (104) is disposed in the electronic limited slip differential mode.

8. The differential unit (104) as claimed in claim 7, wherein the control unit (114) instructs the motor (124) to rotate the rotating ball ramp (528) in the second direction (1504) when the measured speed of the vehicle (100) is greater than the designated vehicle speed threshold and the difference between the speed of the right wheel (122A) and the speed of the left wheel (122B) of the vehicle (100) corresponds to a value that falls within the first threshold range, wherein the one or more ramp balls (612) are adapted to move back to the first and second intermediate depth regions (1004A-B) upon rotation of the rotating ball ramp (528) in the second direction (1504), which disposes the sliding ball ramp (530) in an associated original center position (1208), which in turn moves the one or more push rods (544) linearly away from the clutch pack (522) and disposes the clutch pack (522) in an original uncompressed state, thereby switching the operational mode of the differential unit (104) to the open differential mode from the electronic limited slip differential mode.

9. The differential unit (104) as claimed in claim 8, wherein the linear movement of the one or more push rods (544) away from the clutch pack (522) is adapted to expand the one or more coil springs (616) to the semi-compressed state (1302), which pushes the dog clutch (524) to the non-pushed position (1202) when the differential unit (106) is switched to the open differential mode from the electronic limited slip differential mode.

10. The differential unit (104) as claimed in claim 5, wherein the motor (124) is adapted to rotate the rotating ball ramp (528) in the second direction (1504) when the measured speed of the vehicle (100) is lesser than the designated vehicle speed threshold and the difference between the speed of the right wheel (122A) and the speed of the left wheel (122B) of the vehicle (100) is greater than a second threshold range that is different from the first threshold range, wherein the one or more ramp balls (612) are adapted to move from the first and second intermediate depth regions (1004A-B) to the first and second maximum depth regions (1008A-B) upon rotation of the rotating ball ramp (528) in the second direction (1504), which moves the sliding ball ramp (530) and the one or more push rods (544) to move linearly away from the clutch pack (522), wherein the linear movement of the one or more push rods (544) is adapted to expand the one or more coil springs (616) from the semi-compressed state to a fully extended state (2102), thereby engaging the dog clutch (524) to the side gear (520), which switches the operational mode of the differential unit (104) from the open differential mode to the differential lock mode.

11. The differential unit (104) as claimed in claim 10, wherein the motor (124) is adapted to rotate back the rotating ball ramp (528) in the first direction (1502) when the measured speed of the vehicle (100) corresponds to a value greater than the designated vehicle speed threshold and the difference between the speed of the right wheel (122A) and the speed of the left wheel (122B) of the vehicle (100) corresponds to a value that falls within the first threshold range, wherein the one or more ramp balls (612) are adapted to move to the first and second intermediate depth regions (1004A-B) upon rotation of the rotating ball ramp (528) in the first direction (1502), which disposes the sliding ball ramp (530) in the associated original center position (1208), pushes the one or more push rods (544) and the dog clutch (524), and compresses the one or more coil springs (616) to the semi-compressed state (1302), thereby switching the operational mode of the differential unit (104) to the open differential mode from the differential lock mode.

12. The differential unit (104) as claimed in claim 11, wherein the vehicle (100) comprises a differential mode selection unit (126) that allows a user to manually select the operational mode of the differential unit (104), wherein the differential mode selection unit (126) corresponds to one or more of a switch, a button, a knob, a touch input device, a gesture recognition device, a display device, and a human-machine interface residing in the vehicle (100).

13. The differential unit (104) as claimed in claim 1, wherein the motor (124) corresponds to a brushless direct current motor.

14. The differential unit (104) as claimed in claim 1, wherein the differential unit (104) is integrated into a drivetrain (102) of the vehicle (100), wherein the vehicle (100) corresponds to one of an internal combustion engine powered vehicle, a hybrid vehicle, and an electric vehicle.

15. The differential unit (104) as claimed in claim 1, wherein the differential unit (104) is retrofittable to a drivetrain (102) of the vehicle (100), wherein the vehicle (100) corresponds to one of an internal combustion engine powered vehicle, a hybrid vehicle, and an electric vehicle.

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