JP3306204B2 - Electro-rheological fluid-filled shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber using an electrorheological fluid whose viscosity changes according to an applied voltage.

[0002]

2. Description of the Related Art Japanese Utility Model Publication No. 3-5698 is known as a shock absorber in which the generated damping force can be adjusted by using an electrorheological fluid whose viscosity changes according to an applied voltage.

This electrorheological fluid mixes insulating base oil with polarizable fine particles, and these particles are arranged in a chain between electrodes in response to application of a voltage, thereby increasing the flow resistance of the base oil. As a result, the viscosity of the fluid is changed.

[0004] In this shock absorber, an electrorheological fluid is used as a working fluid flowing through the interior as the piston slides.
By providing an electrode in the flow path, the generated damping force can be adjusted according to the applied voltage.

[0005]

In this case, the piston rod is supported by the piston rod protruding from the cylinder so that the working fluid inside the cylinder does not leak out of the cylinder and outside dust and the like do not enter the inside of the cylinder. A seal is provided near the opening of the bearing.

This seal has a dust lip for scraping off dust adhering to the surface of the piston rod, and an oil lip for scraping off working fluid adhering to the surface of the piston rod.

However, since the working fluid contains fine particles, the fine particles tend to bite between the oil lip and the piston rod due to repeated contact between the working fluid and the oil lip, and easily damage the surface of the oil lip and the piston rod. There was a tendency. Therefore, if the sealing function is reduced, not only does the working fluid in the shock absorber leak, but if water enters from outside beyond the oil lip, the damping force adjustment function by the electrorheological fluid does not function sufficiently. Occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to enhance the sealing ability of a shock absorber using an electrorheological fluid and the durability of a sealing member.

[0009]

SUMMARY OF THE INVENTION The present invention provides a piston which is slidably housed in a cylinder, and a piston rod connected to the piston is supported by a bearing which slidably supports the piston rod; And projecting from the cylinder via a seal member slidingly contacting the piston rod on the opposite side, and changing the viscosity of the working fluid flowing while generating a damping force with respect to the sliding of the piston according to the applied voltage, In an electrorheological fluid-filled buffer comprising an electrorheological fluid in which polarizable microparticles are mixed with an insulating base oil and having a reservoir for storing the electrorheological fluid, the electrorheological fluid is filled between a seal member and a bearing. A mechanism for separating the fine particles from the base oil and a return path for returning the separated fine particles to the reservoir are provided. To have.

In the present invention, the separating mechanism is constituted by another seal member which slides on the piston rod.

The present invention further comprises a filter provided with a mesh finer than fine particles, which is in sliding contact with the piston rod between the seal member and the piston.

[0012]

With the mechanism for separating the fine particles of the electrorheological fluid and the base oil between the seal member and the bearing, and the return passage for returning the separated fine particles to the reservoir, the fine particles are extended when the piston rod is extended. Is removed before the seal member and returns to the reservoir through the passage. For this reason, the microparticles are not caught between the seal member and the piston rod, and the environment is such that the seal member and the piston rod are not easily damaged.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a shock absorber in which an electrorheological fluid in which polarizable fine particles are mixed in a base oil is enclosed as a working oil. 1 is a cylinder, 2 is an outer tube, 3 is an inner tube, 4 is a piston, and 13 is a piston rod.

The interior of the cylinder 1 is defined by a piston 4 as oil chambers 5 and 6, and an oil reservoir 7 as a reservoir for storing an electrorheological fluid is formed between the outer tube 2 and the inner tube 3. A passage 11 is formed between the tube 3 and the cylinder 1.

In this shock absorber, check valves 8 and 9 provided at the piston 4 and the bottom of the cylinder 1 respectively allow the piston 11 to slide from the port 10 to the passage 11 Then, the electrorheological fluid flows out and flows into the oil reservoir 7 from the port 12 of the inner tube 3.

The inner tube 3 and the cylinder 1 on both sides of the passage 11 are each made of an insulated conductive material, and a voltage is applied between the inner tube 3 and the cylinder 1 as necessary. Thereby, the fine particles of the electrorheological fluid passing through the passage 11 at the time of energization are aligned between the inner tube 3 and the cylinder 1, and the generated damping force in both the expansion and contraction directions is increased by the increase of the flow resistance.

The piston rod 13 is slidably supported by a bearing 14 provided across the outer tube 2. A main seal 15 serving as a seal member and a sub-seal 16 serving as a separating mechanism are in sliding contact with the outer periphery of the piston rod 13. The sub seal 16 is provided at a position closer to the bearing 14 than the main seal 15.

The main seal 15 comprises an oil lip 15A and a dust lip 15B which are in sliding contact with the piston rod 13, and a cap 1 provided at the opening of the outer tube 3.
7 is housed inside. The oil lip 15A is located closer to the bearing 14 than the dust lip 15B.

The sub-seal 16 is composed of an oil lip 16A and a dust lip 16B which are in sliding contact with the piston rod 13, and is housed inside a recess 18 provided in the bearing 14. The oil lip 16A is located closer to the main seal 15 than the dust lip 16B.

A return passage 19 is formed in the bearing 14 for returning the fine particles accumulated in the concave portion 18 to the oil reservoir via a check seal 20 provided at the upper end of the oil reservoir 7. The check seal 20 allows the flow of fine particles and the like from the return passage 19 toward the oil reservoir 7.

The bearing 14 further includes a cap 17.
A passage 22b is formed to recirculate the oil stored in the oil holding chamber 22a formed between the sub seal 16 and the main seal 15 to the oil storage chamber 7 via the check seal 20.

Next, the operation will be described.

As the piston 4 slides in the cylinder 1, the piston rod 13 expands and contracts while sliding with respect to the bearing 14, the main seal 15, and the sub-seal 16.

Accordingly, the electrorheological fluid in the cylinder 1 attached to the outer periphery of the piston rod 13 is taken out of the bearing 14 through the sliding gap with the bearing 14 as the piston rod 13 extends.

On the other hand, first, the dust lip 16B of the sub-seal 16 in the concave portion 18 slides on the piston rod 13 to scrape off fine particles contained in the electrorheological fluid.
The scraped-off fine particles accumulate in the concave portion 18 between the bearing 14 and the dust lip 16B, and return to the oil reservoir 7 from the passage 19 via the check seal 20.

Further, the base oil remaining on the surface of the piston rod 13 in the form of an oil film is scraped off to the oil lip 15A of the main seal 15. As a result, every time the piston rod 13 extends, a small amount of base oil accumulates in the oil holding chamber 22a between the main seal 15 and the sub-seal 16. This base oil is supplied to the passage 22b and the check seal 2
The oil is returned to the oil reservoir 7 through 0.

Since the return passage 19 for returning the fine particles and the passage 22b for returning the base oil are provided in this manner, the electrorheological fluid leaking from the sliding gap between the bearing 14 and the piston rod 13 is formed in the sub-seal 16. The oil is efficiently separated before and after and collected in the oil reservoir 7. Since the fine particles are separated by the dust lip 16B closest to the bearing 14, the fine particles are removed before the main seal 15 and the fine particles are removed.
There is no danger of 5 being hurt. Further, since fine particles are not caught between the main seal 15 and the piston rod 13, the piston rod 13 is also hardly damaged.

On the other hand, when the piston rod 13 contracts, the dust lip 15B of the main seal 15 scrapes dust adhering to the surface of the protrusion of the piston rod 13. Therefore, there is no possibility that the sub-seal 16 may be damaged by dust that has entered from the outside.

In summary, the electrorheological fluid flows through the passage 11 when the piston 4 expands and contracts, but a part of the electrorheological fluid adheres to the outer periphery of the piston rod 13 and leaks from the sliding gap with the bearing 14. try to. The fine particles contained in the electrorheological fluid are removed by dust lip 16B, and the remaining base oil is removed by oil lip 15B.
A large pressure is applied to the dust lip 16B and the oil lip 15B due to the accumulation of the removed components, and a sufficient sealing function cannot be obtained. In order to prevent such a pressure load, the recess 18 and the oil reservoir 7 and the oil holding chamber 22a and the oil reservoir 7 are communicated with each other by the return passage 19 and the passage 22b.

The oil lip 16 of the sub-seal 16
A is an oil holding chamber 2 between the main seal 15 and the sub-seal 16.
This function prevents the base oil in 2a from flowing back to the dust lip 16B side, but can be omitted if there is no fear of this.

Since the main function of the sub-seal 16 is to separate fine particles in the electrorheological fluid, it is desirable to use a material capable of facilitating the passage of the base oil and reducing the sliding resistance. Urethane foam is an example of a material corresponding to this.

FIG. 2 shows a second embodiment of the present invention.

Here, the sub-seal 16 is used as a separating mechanism.
Is replaced by a filter 30. The filter 30 has a mesh smaller than the fine particles of the electrorheological fluid.
The filter 30 is held inside a holder 33 fixed to the recess 18. A lip 30 </ b> A is formed at the lower end of the filter 30 so as to slide on the outer periphery of the piston rod 13. A low friction sliding member 31 for sliding the piston rod 13 without resistance is provided inside the filter 30 above the lip 30A.

In this case, when the piston rod 13 extends, the bearing 1
For the electrorheological fluid passing through 4, the filter 30 separates the fine particles from the base oil and keeps them in the concave portion 18. As a result, the piston rod 13 passes through the low friction sliding member 31 using the base oil from which the fine particles have been removed as lubricating oil. When the piston rod 13 reaches the outside of the bearing 14, the oil lip 15A of the main seal 15 is
Scrub the base oil into 2a.

The fine particles in the concave portion 18 pass through the return passage 19 and the check seal 20, and the base oil in the oil holding chamber 22 a between the bearing 14 and the cap 17 passes through the passage 22 b and the check seal 20 to form the oil reservoir 7. Reflux.

[0037]

As described above, the present invention comprises a mechanism for separating fine particles of electrorheological fluid from base oil between a seal member and a bearing, and a return passage for returning the separated fine particles to the reservoir. Therefore, the fine particles are removed in front of the seal member, and the seal member does not come into contact with the fine particles.Therefore, the seal member may be damaged, or the piston rod may be damaged by the fine particles caught between the seal member and the piston rod. In addition, the sealing ability and durability of the sealing member can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a shock absorber according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of a shock absorber according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 4 Piston 7 Oil reservoir 13 Piston rod 14 Bearing 15 Main seal 16 Sub seal 19 Return passage 30 Filter

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mikiya Shinohara 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (56) References JP-A-5-44766 (JP, A) Japanese Utility Model 4 -8845 (JP, U) Japanese Utility Model 2-9305 (JP, U) JP-B-53-115476 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16F 9/53 F16F 9/36

Claims (3)

(57) [Claims] A piston is slidably received in a cylinder, and a piston rod connected to the piston is slidably supported on the piston rod on a side opposite to the piston with the bearing interposed therebetween. The working fluid flowing out while projecting from the cylinder through the contacting seal member and generating a damping force against the sliding of the piston changes the viscosity according to the applied voltage. A mechanism for separating microparticles of electrorheological fluid from base oil between a seal member and a bearing in an electrorheological fluid-filled shock absorber including an electrorheological fluid in which particles are mixed and having a reservoir for storing the electrorheological fluid. And a return passage for returning the separated fine particles to the reservoir. Fluid-filled shock absorber. 2. The electrorheological fluid-filled shock absorber according to claim 1, wherein the separation mechanism is another seal member that slides on the piston rod. 3. The electrorheological fluid-filled shock absorber according to claim 1, wherein the separation mechanism is a filter having a mesh finer than fine particles, the filter being in sliding contact with the piston rod between the seal member and the piston.