Hybrid magnetic semi-active damper

Abstract

The current invention of the hybrid magnetic semi-active damper includes a damper cylinder, a piston, a piston rod, a permanent magnet and an electromagnet arranged in a longitudinal axis. Apart from these aforementioned components, it also consists of secondary components essential to complete the damper as a whole but might or might not effecting the functionality of the damper. The electromagnet is a stationary component whereas the permanent magnet is allowed to move inside the cylinder. The magnitude variation in the current supply to the electromagnet makes the damper semi-active in nature.

Specification

Description:FIELD OF INVENTION
[001] The present invention relates to the vibration dampers and more specifically semi-active magnetic dampers.
BACKGROUND AND PRIOR ART
[002] A damper is a well-known energy dissipating device predominantly used in automobile vehicles as well as structures. Being energy dissipating device, a damper is used to mitigate vibrations in the respective fields. A general damper consists of cylinder, piston and a damping medium/ damping fluid as major components. The damper may be passive, semi-active or active in nature. The semi active dampers have the ability to change the damping characteristics against the influence of external environment or agencies. One of the well-known semi active damper which uses magnetism phenomena is the magneto-rheological fluid damper where the magnetic or ferrous particles dispersed in a carrier fluid are responsible for change in damping characteristics under the influence of magnetic field.
[003] Several studies in the past have described semi-active magnetic dampers for various applications. For example, a patent with patent number 5277281 (with date of patent: January 11, 1994) as well as patents with similar product applications, used magneto-rheological fluid as the damping medium along with electromagnetic or permanent magnet to generate magnetic field. Similarly, a research article published by Gori et al. (published July 18, 2023) and similar articles used permanent magnets for the respective applications for eddy current generation and hence the damping.
[004] The magneto-rheological fluid damper being a well-known and proven semi active damper, uses magneto-rheological fluid as the damping medium. The magnetic flux generated in the magneto-rheological fluid depends on the composition of the magneto-rheological fluid as well as current supplied to the electromagnetic piston core. The variability in the damping characteristics must require the magneto-rheological fluid as the damping medium in such dampers. In the latter mentioned type of dampers, the eddy current generation is the key factor for the damping variation, which depends on the material used for the damper.
[005] The electromagnetism is one of the well-suited phenomena for the semi-activeness of the damper. The usage of magnetic fluid or the material selection becomes a key factor in achieving the semi-active nature of the damper. These factors could increase the complexity in the design of the damper with magnetism or electromagnetism.
[006] Hence, there is a need of a simpler design or arrangement of magnet and electromagnet in the semi active dampers which use magnetism for the semi-active operation.
SUMMARY OF THE INVENTION
[007] The current invention is achieved by including a permanent magnet and an electromagnet in its operation. The components in the current invention contains a cylinder which is developed by using non-magnetic material, a piston rod which is also a non-magnetic component, a permanent magnet preferably a soft ferrous magnet with high magnetic permeability, an electromagnet whose magnetism can be varied with fluctuation in input DC (direct current) current, a piston made up of non-magnetic material, closures for the cylinder from top and bottom direction and screws to attach closures to the cylinder in the respective position.
[008] The cylinder, piston, piston rod, permanent magnet, electromagnet, the closures in the current invention are aligned in a longitudinal axis. The screws are used to attach closures to the cylinder in transverse direction in the relevant positions. The closures in the current invention are made up of delrin (a thermoplastic material) and are attached to the top and bottom position of the cylinder with the help of screw. The closures are positioned inside the cylinder without any clearance between cylinder inner wall and the closure outer surface. These closures are meant for closing the cylinder from top and bottom positions and for the proper alignment of the piston rod in the longitudinal axis. The piston is attached to the piston rod with the help of external and internal thread arrangement respectively. The piston is allowed to move inside the cylinder along the longitudinal direction. The permanent magnet is attached to the one surface of the piston with the help of adhesive. The piston carries the permanent magnet along with itself during its motion inside the cylinder.
[009] The electromagnet is attached to the one surface of closure near the bottom side of the cylinder. This electromagnet is kept stationary and is not allowed to move inside the cylinder. The electromagnet has the wire extension for the supply of DC current. The supply of the DC current to the electromagnet induces magnetic field proportional to the DC current supply. The DC input current variation results in the disparity in the magnitude of electromagnetism and hence the magnetic field intensity changes. The electromagnet and the permanent magnet are positioned in a way to oppose the magnetic field between them. The change in the DC current input provides the variation in opposing nature between the permanent magnet and electromagnet. This phenomenon can be effective in providing semi active nature to the damper with a simple design. Use of damping liquid is avoided in the current invention.
BRIEF DESCRIPTIONS OF DRAWINGS
[010] Fig 1 is the isometric view of the cylinder of the hybrid magnetic damper.
[011] Fig 2 is the isometric view of the piston of the body which moves longitudinally inside the cylinder Fig 1.
[012] Fig 3 is the isometric view of the permanent magnet which is attached to the piston (Fig 2).
[013] Fig 4 is the isometric view of the piston rod which is attached to piston (Fig 2)
[014] Fig 5 is the isometric view of the electromagnet with lead wire to provide DC current input to generate electromagnetism.
[015] Fig 6 is the isometric view of the bottom closure for the cylinder which is attached to the cylinder (Fig 1) form bottom position.
[016] Fig 7 is the view of screw which is used to attach closure (Fig 6 and Fig 8) with the cylinder (Fig 1)
[017] Fig 8 is the isometric view of the upper closure for the cylinder which is attached to the cylinder (Fig 1) form top position.
[018] Fig 9 is the cross-section view of the assembly of the hybrid magnetic damper consisting of permanent magnet and the electromagnet.


DETAILED DESCRIPTION OF THE INVENTION
[019] Referring to Fig 1, the cylinder of the hybrid magnetic damper is shown in isometric view. The cylinder has the outer surface 1a and the inner surface 1b. It has been given the provisions 1c and 1d to attach closures as shown in Fig 6 and Fig 8 with the help of screw as shown in Fig 7. The cylinder is made from aluminium material which non-magnetic or diamagnetic in nature. The Fig 2 shows the piston which moves longitudinally inside the cylinder (Fig 1). The piston has flat surfaces 2a and 2c. The piston also has an inner threaded portion 2b for the attachment of piston rod shown in Fig 4. The Fig 3 shows the permanent magnet having top flat surface 3a and the bottom flat surface 3b. The permanent magnet shown here in Fig 3 is made from neodymium material with N45 grade. The flat surface 3a is attached to the flat surface of the piston 2c with the help of adhesive. Hence, the permanent magnet moves inside the cylinder since attached to piston. Fig 4 shows the piston rod having externally threaded portion 4a and a cylindrical surface 4b. The piston rod is attached to the piston (Fig 2) with the help threaded connection between 4a and 2b. The piston (Fig 2) and the piston rod (Fig 4) are made of non-magnetic or diamagnetic material.
[020] Referring to Fig 5, an electromagnet is shown having an upper surface 5a, a bottom surface 5d and a cylindrical surface 5b. The electromagnet as shown in Fig 5, consists of a wire extension 5c from which external DC power supply can be provided to enable electromagnetism. Fig 6 shows the bottom closure for the cylinder (Fig 1). The bottom closure (Fig 6) has the upper flat surface 6a and the cylindrical surface 6b. The bottom closure (Fig 6) is attached to the cylinder (Fig 1) through a screw (Fig 7) in provision 1d where the cylindrical surfaces 6b and 1b are in contact to each other. The bottom surface 5d of the electromagnet (Fig 5) is attached to the upper flat surface 6a of the bottom closure (Fig 6) with the help of adhesive. Fig 8 refers to the upper closure for the cylinder (Fig 1). The upper closure (Fig 8) has a cylindrical hole 8a, cylindrical surface 8b, a hole 8c and the bottom flat surface 8d. The upper closure (Fig 8) is attached to cylinder (Fig 1) with the help of screw (Fig 7) through the provision 1c. The screw (Fig 7) connects the 8c and 1c to make sure the cylindrical surfaces 8b and 1b are in contact with each other. The cylindrical surface 4b passes through the cylindrical hole 8a. The piston rod (Fig 4) moves in the same longitudinal axis as that of upper closure (Fig 8) through the cylindrical hole 8a.
[021] Referring to Fig 9, is the cross-sectional view of the assembly of the hybrid magnetic damper. The assembly of cylinder (Fig 1), piston (Fig 2), permanent magnet (Fig 3), piston rod (Fig 4), electromagnet (Fig 5), bottom closure (Fig 6) and the upper closure (Fig 8) is done over a same longitudinal axis and can be seen in Fig 9. In the assembly (Fig 9), the surfaces 3b and 5a face to each other. The faces 3b and 5a are maintained with same magnetic polarity in the for the proper functioning of the current invention. The faces 3a and 5b repel each other due to the same magnetic polarity. The DC current supply through the wire extension 5c enables electromagnetism in the electromagnet (Fig 5). The magnitude of DC power supply decides the magnitude of repel between the faces 3a and 5b. The variation in the magnitude of DC power supply enables differences in the electromagnetism in electromagnet (Fig 5) and hence can be used to achieve difference in repelling forces between faces 3a and 5b. This phenomenon can be used to achieve semi activeness in the damping nature of the hybrid magnetic damper. , C , Claims:[022] 1. A hybrid magnetic semi-active damper comprising of non-magnetic cylinder (1), permanent magnet (3), electromagnet (5), non-magnetic piston rod (4), the non-magnetic piston (2), a bottom closure (6), an upper closure (8) where a permanent magnet (3) attached to non-magnetic piston (2) moves longitudinally inside the non-magnetic cylinder (1) wherein the permanent magnet (3) faces the electromagnet (5) whose face is maintained with same polarity as permanent magnet (3) during the movement in the said assembly (9) of the damper.
[023] 2. A hybrid magnetic semi-active damper according to claim 1, a combination of non-magnetic cylinder (1), a non-magnetic piston (2) and a non-magnetic piston rod (4) as the necessary parts in the assembly (9) of the damper for the functionality.
[024] 3. A hybrid magnetic semi-active damper according to claim 1, usage of non-magnetic materials for the bottom closure (6) and the upper closure (8) as the closing elements for the damper (9) from the top and bottom sides.
[025] 4. A hybrid magnetic semi-active damper according to claim 1, usage of polarity between permanent magnet (3) and the electromagnet (5) in the assembly (9) of the damper, wherein the bottom flat surface of the permanent magnet (3b) and the upper surface of the electromagnet (5a) are maintained with same magnetic polarity so that the surfaces 3b and 5a repel each other for the proposed functionality of the hybrid magnetic semi-active damper.
[026] 5. The assembly of the hybrid magnetic semi-active damper wherein the permanent magnet (3) attached to the non-magnetic piston (2) moves longitudinally inside the non-magnetic cylinder (1) and the electromagnet (5) remain stationary which is attached to the bottom closure (6) in the proposed assembly (9). Variation in the electric current input to the electromagnet (5) through the wire extension (5c), helps to vary the magnetic field strength from the electromagnet (5) which results in variation in the repelling force between permanent magnet (3) and the electromagnet (5). This variation in the repelling force is the key to achieve semi active damping behaviour in the hybrid magnetic damper.

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