JPH0220514Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hydraulic shock absorber used in a vehicle suspension.

[Prior Art] The structure of a double-tube hydraulic shock absorber has been well known (for example, Japanese Utility Model Application Publication No. 87644/1987). In a conventional double-tube hydraulic shock absorber, the cylinder body is composed of an inner cylinder and an outer cylinder. The inner cylinder has a liquid chamber that accommodates hydraulic fluid, and the liquid chamber is partitioned by the piston into two chambers: a piston upper chamber and a piston lower chamber. A reservoir chamber is formed between the inner cylinder and the outer cylinder to accommodate the working fluid from the piston lower chamber. The lower piston chamber and the reservoir chamber are communicated with each other by two communication passages of a base valve provided at the lowest part of the lower piston chamber, and each communication passage is provided on the outer periphery of the base valve.

In addition, a two-stage adjustment fluid buffer is provided with an electromagnet inside the buffer filled with fluid, and the inlet of the fluid return duct is opened and closed by electromagnetic force.
It is disclosed in Japanese Patent Application Laid-Open No. 110176/1983. In this shock absorber, the optimum damping rate can be selected by operating an electromagnet, and the electromagnet is operated by the driver according to the vehicle speed, the load, and the unevenness of the road surface.

[Problems to be solved by the invention] The working fluid in the hydraulic shock absorber may contain iron-based foreign matter such as metal abrasion powder and chips, albeit in small amounts. If the hydraulic shock absorber is used for a long time with iron-based foreign matter mixed in the hydraulic fluid, the sliding surface between the piston and the inner cylinder may be scraped by the iron-based foreign matter, or the iron-based foreign matter may scrape the sliding surface between the piston and the inner cylinder. A problem arises in that it gets caught in the valve body that generates the damping force. Therefore, problems arise in that the sealing function of the piston is deteriorated and the oil passage cannot be completely blocked by the valve body, which adversely affects the damping performance of the hydraulic shock absorber.

The present invention has focused on the above-mentioned problem, and aims to provide a hydraulic shock absorber that can reliably collect iron-based foreign matter even when the iron-based foreign matter is mixed in the hydraulic fluid.

[Means for Solving the Problems] The hydraulic shock absorber of the present invention that meets this objective has a cylinder body composed of an inner cylinder and an outer cylinder, a liquid chamber for storing a working fluid is provided in the inner cylinder, and an inner cylinder. Between the cylinder and the outer cylinder,
A reservoir chamber is provided to store the working fluid from the inner cylinder, and the liquid chamber of the inner cylinder is partitioned into two chambers, a piston upper chamber and a piston lower chamber, by a piston that is slidably fitted into the inner cylinder and connected to a piston rod. Also, the piston upper chamber and the piston lower chamber are communicated via a damping force generation mechanism provided on the piston, and the piston lower chamber and the reservoir chamber are provided at the lowest part of the piston lower chamber on the opposite side from the piston rod. In the hydraulic shock absorber, the hydraulic shock absorber is configured to communicate via a base valve having a damping force generating means with a communication passage on its outer periphery, and a central portion of the base valve in the lower piston chamber is provided through a non-magnetic material. It consists of a permanent magnet that is supported and that attracts iron-based foreign matter in the hydraulic fluid.

[Function] In the hydraulic shock absorber configured in this way,
When the piston moves up and down due to the impact transmitted to the piston rod, iron-based foreign matter mixed in the working fluid flowing near the permanent magnet is attracted by the magnetic force of the permanent magnet.

Since the flow rate of the hydraulic fluid is slower in the central part of the base valve where the permanent magnet is provided than in the outer peripheral part where the communication passage of the damping force generating means is located, iron-based foreign matter mixed in the hydraulic fluid is It will not be washed away by the flow of hydraulic fluid and will be reliably attracted to the permanent magnet. Moreover, once the foreign matter is attracted to the permanent magnet, it is almost impossible to separate due to the flow of the working fluid. Further, since the lowermost part of the piston lower chamber where the base valve is located tends to accumulate settled foreign matter, by arranging a permanent magnet in this part, the effect of trapping iron-based foreign matter is significantly enhanced.

Furthermore, since the permanent magnet is held via a non-magnetic material, the inner cylinder is not magnetized by the permanent magnet, and adhesion of iron-based foreign matter to the sliding surface of the inner cylinder is also prevented. Therefore, the occurrence of cutting action due to foreign matter during sliding contact between the piston and the inner cylinder is reliably prevented.

[Embodiments] Hereinafter, preferred embodiments of the hydraulic shock absorber according to the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 shows a hydraulic shock absorber according to a first embodiment of the present invention. In the figure, 21 indicates a cylinder body, and the cylinder body 21 is composed of an inner cylinder 22 and an outer cylinder 23. The inside of the inner cylinder 22 is a liquid chamber in which hydraulic fluid is accommodated. This liquid chamber is
A piston 24 slidably fitted into the inner cylinder 22 partitions the piston into an upper chamber 25 and a lower piston chamber 26 . A reservoir chamber 27 is formed between the inner cylinder 22 and the outer cylinder 23 in which the working fluid in the inner cylinder 22 is stored.

A damping force generation mechanism is formed in the piston 24, and a piston upper chamber 25 and a piston lower chamber 26 are formed.
are communicated via this damping force generating mechanism.
The damping force generation mechanism is configured as follows.
That is, a hole 24a is provided in the center of the piston 24, and the piston rod 2 is inserted into the hole 24a.
The end of 8 is inserted. A threaded portion 28a is formed at the end of the piston rod 28, and the piston 24 is connected to the piston rod 28 by a piston holding member 29 screwed onto the threaded portion 28a. The outer periphery of the piston 24 includes a first communication passage 30 that allows the hydraulic fluid to pass in only one direction from the piston lower chamber 26 to the piston upper chamber 25 when the piston rod 28 moves downward, and a first communication passage 30 that allows the hydraulic fluid to pass in only one direction from the piston lower chamber 26 to the piston upper chamber 25 when the piston rod 28 moves upward. A second communication path 31 is provided that allows the hydraulic fluid to pass in only one direction from the piston upper chamber 25 to the piston lower chamber 26 when the piston is turned. The first communication path 30 and the second communication path 31 are
It is formed to extend in the axial direction of the cylinder body 1. The first communication passage 30 can be opened and closed by a vertically movable valve body 32 provided on the upper surface side of the piston 24. The second communication passage 31 can be opened and closed by a valve body 33 provided on the lower surface side of the piston 24, and the valve body 33 is always urged against the lower surface of the piston 24 by a compression spring 34. .

Note that a relief hole 28b is provided at the lower end of the piston rod 28 to prevent interference with a permanent magnet 44, which will be described later.

A bottom lid 35 shaped like a container with a bottom is fitted inside the lower end of the outer cylinder 23 , and the lower end of the inner cylinder 22 is disposed inside the bottom lid 35 . A base valve 36 having damping force generating means for communicating the piston lower chamber 26 and the reservoir chamber 27 is provided at the lowest part of the piston lower chamber 26, that is, between the lower end of the inner cylinder 22 and the bottom cover 35. There is. The damping force generating means includes a first communication path 39, a second communication path 40, valve bodies 41, 42, a valve body support member 43, and the like.

The upper part of the base valve 36 is fitted into the inner cylinder 22, and the outer diameter of the base valve 36 is the same as the outer diameter of the inner cylinder 22. As a result, the inner cylinder 22,
A hydraulic fluid passage 37 communicating with the reservoir chamber 27 is formed between the outer peripheral surface of the base valve 36 and the inner wall of the bottom cover 35 . Also, base valve 3
The bottom surface 36a of the bottom cover 35 is in contact with the slope of the bottom cover 32, and a hydraulic fluid passage 38 is formed between the bottom surface 36a and the bottom surface 35a of the bottom cover 35. This passage 38 is in communication with the passage 37 described above.

At the outer periphery radially outward from the center of the base valve 36 is a first connection that allows the hydraulic fluid to pass in only one direction from the piston lower chamber 26 to the reservoir chamber 27 when the piston rod 28 moves downward. When the passage 39 and the piston rod 28 move upward, the hydraulic fluid is transferred from the reservoir chamber 27 to the lower piston chamber 2.
A second communication path 40 is provided that allows passage of the liquid in only one direction to 6. The first communication passage 39 and the second communication passage 40 are formed to extend in the axial direction of the cylinder body 1. At the center of the base valve 36 is a valve body support member 43 that supports the valve bodies 41 and 42.
is provided to penetrate the base valve 36 in the axial direction. The valve body 41 is provided on the upper surface side of the base valve 36, and the second communication passage 40 can be opened and closed by vertical movement of the valve body 41. Further, excessive upward movement of the valve body 41 is restricted by the upper bulging portion 43a of the valve body support member 43. The valve body 42 is provided on the lower surface side of the base valve 6, and the first communication path 39 is connected to the valve body 42.
It can be opened and closed by moving up and down. and,
The valve body 42 has a bulging portion 4 below the valve body support member 43.
Excessive downward movement is restricted by a plate-shaped member 46 supported by 3b.

Base valve 36 in the piston lower chamber 26
A permanent magnet 44 that attracts iron-based foreign matter in the hydraulic fluid is located directly above the center of the valve body support member 43, that is, at a position where the flow velocity of the hydraulic fluid is relatively slow.
is provided. The permanent magnet 44 is formed in a cylindrical shape extending in the axial direction of the cylinder body 1,
The lower end portion of the permanent magnet 44 is supported by a non-magnetic material 45 provided on the valve body support member 43.

Next, the operation in the first embodiment will be explained.

When the piston rod 28 is moved downward by an external impact, the piston 24 connected to the piston rod 28 also moves downward. In this case, the working fluid in the piston lower chamber 26 passes through the first communication passage 30 of the piston 24 from the piston lower chamber 26 and flows into the piston upper chamber 25 . At the same time, the hydraulic fluid passes through the first communication path 39 and flows into the reservoir chamber 27 . The first communication path 39 is
Since it is provided on the outer periphery of the base valve 36, the flow velocity of the hydraulic fluid near the permanent magnet 44 provided in the center of the base valve 36 is controlled by the first communication path 3.
It becomes slower than the flow velocity near 9. Therefore, iron-based foreign substances mixed in the working fluid flowing near the permanent magnet 44 are not washed away together with the working fluid, but are reliably attracted to the permanent magnet 44.

Furthermore, when the piston 24 moves upward, the hydraulic fluid in the piston upper chamber 25 flows from the piston upper chamber 25 into the piston lower chamber 26 through the second communication passage 31 of the piston 24 . Similarly, the hydraulic fluid flows from the reservoir chamber 27 into the lower piston chamber 26 through the second communication passage 40 of the base valve 36 . Since the second communication passage 40 is provided on the outer periphery of the base valve 36, the flow rate of the hydraulic fluid flowing into the piston lower chamber 26 near the permanent magnet 44 is higher than that near the second communication passage 40. Become slow. Therefore, in the same way as described above, iron-based foreign matter mixed in the hydraulic fluid flowing near the permanent magnet 44 is not washed away with the hydraulic fluid as in the above-mentioned effect.
It is reliably attracted to the permanent magnet 44.

In this way, the hydraulic fluid flows out from the piston lower chamber 26 to another chamber or flows into the piston lower chamber 26 from another chamber due to the movement of the piston 24, so the permanent magnet 44 is moved to the piston where the flow of hydraulic fluid is concentrated. By providing it in the lower chamber 26, it becomes easy to collect iron-based foreign substances. Furthermore, since the lowermost part of the piston lower chamber 26 where the base valve 36 is located tends to accumulate settled foreign matter, by arranging the permanent magnet 44 in this part, the effect of trapping iron-based foreign matter is significantly enhanced.

Also, the orientation of the permanent magnet 44 and the first communication path 3
9. The direction of the second communication path 40 is
Since the axial direction is the same as that of the permanent magnet 44, the working fluid flows along the permanent magnet 44, and the adsorption efficiency of iron-based foreign matter is greatly increased.

Note that since the permanent magnet 44 is supported by the valve body support member 43 of the base valve 36 via the non-magnetic material 45, the inner cylinder 22 is no longer magnetized by the permanent magnet 44, and the inner cylinder 22 is not magnetized by the permanent magnet 44. The adsorption of iron-based foreign matter to the sliding surfaces of is prevented. Therefore, the problem of the sliding surface of the inner cylinder 22 being cut by iron-based foreign matter when the piston 24 and the inner cylinder 22 are in sliding contact is solved.

Second Embodiment FIGS. 2 and 3 show a second embodiment of the present invention. The second embodiment differs from the first embodiment in the mounting structure of the permanent magnet, and other parts are similar to the first embodiment.
By assigning the same reference numerals as in the embodiment, description of the corresponding parts will be omitted, and only different parts will be described.

In FIGS. 2 and 3, 71 is
A valve body support member is shown, and in this embodiment, the valve body support member 71 is fastened to the base valve 36 by a nut 72. In the first embodiment, the top of the valve body support member was provided with a permanent magnet extending in the axial direction, but in this embodiment, a permanent magnet 72 is embedded in the upper end surface side of the valve body support member 71 of the base valve 36. ing. The permanent magnet 72 is press-fitted into the valve body support member 71 via a non-magnetic material 73, and the upper end surface 72a of the permanent magnet 72 is slightly recessed than the upper end surface 71a of the valve body support member 71.

In the second embodiment configured in this way,
The position of the permanent magnet 72 is substantially the same as in the first embodiment, and the flow rate of the hydraulic fluid flowing near the permanent magnet 72 is relatively slow. Therefore, the iron-based foreign matter adsorbed to the permanent magnet 72 will not be separated from the permanent magnet 72 due to the flow of the working fluid, and the iron-based foreign matter will be reliably collected. Moreover, since the permanent magnet 72 is located at the lowest part of the piston lower chamber 26, most of the precipitated foreign matter can be collected, and collection efficiency is improved.

Furthermore, since the permanent magnet 72 is embedded in the valve body support member 71, there is no need for the permanent magnet to protrude as in the first embodiment, and the hydraulic shock absorber of the conventional structure can be used as is, and the design of other parts can be improved. No changes are required.

[Effects of the invention] As explained above, when using the hydraulic shock absorber of the invention, the hydraulic shock absorber is supported via a non-magnetic material in the center of the base valve in the lower piston chamber, where the flow velocity of the hydraulic fluid is relatively slow. Since we installed a permanent magnet,
Iron-based foreign substances in the working fluid can be efficiently and reliably collected. As a result, it is possible to significantly suppress the wear of the sliding parts due to iron-based foreign objects, and the iron-based foreign objects are no longer caught on the valve body, thereby preventing a decrease in the damping performance of the hydraulic shock absorber. I can do it.

Further, since the permanent magnet is supported via a non-magnetic material, the inner cylinder is not magnetized by the permanent magnet, and adsorption of iron-based foreign matter to the inner cylinder is reliably prevented. Therefore, it is possible to reliably prevent a vicious cycle in which the wall surface of the inner cylinder is further scraped off by the metal pieces scraped off by the sliding contact between the piston and the inner cylinder.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a main part of a hydraulic shock absorber according to a first embodiment of the present invention, FIG. 2 is a partially enlarged cross-sectional view of a hydraulic shock absorber according to a second embodiment of the present invention, and FIG. is the second
It is a partial sectional view of the valve body support member in a figure. 21... Cylinder body, 22... Inner cylinder, 23...
...Outer cylinder, 24...Piston, 25...Piston upper chamber, 26...Piston lower chamber, 27...Reservoir chamber, 28...Piston rod, 39...First communication path, 40...Second communication path Passage, 36... Base valve, 44, 72... Permanent magnet, 45, 73...
Non-magnetic material.

Claims (1)

[Scope of utility model registration request] The cylinder body is composed of an inner cylinder and an outer cylinder, the inner cylinder is provided with a liquid chamber for storing the working fluid, and a reservoir chamber is provided between the inner cylinder and the outer cylinder for storing the working fluid from the inner cylinder, The liquid chamber of the inner cylinder is partitioned into two chambers, a piston upper chamber and a piston lower chamber, by a piston that is slidably fitted into the inner cylinder and connected to a piston rod, and the piston upper chamber and the piston lower chamber are separated from each other by the piston rod. A damping force generating means that communicates with the lower piston chamber and the reservoir chamber via a damping force generating mechanism provided on the piston, and is provided at the lowest part of the lower piston chamber on the opposite side of the piston rod and has a communication passage on the outer periphery. In a hydraulic shock absorber that communicates via a base valve, the hydraulic shock absorber is supported at the center of the base valve in the lower piston chamber via a non-magnetic material and adsorbs iron-based foreign matter in the hydraulic fluid. A hydraulic shock absorber characterized by being equipped with a permanent magnet.