JPS6383424A - Damping force variable type hydraulic damper - Google Patents

Abstract

PURPOSE:To enable the compression-stroke damping force of extending in variable range by increasing both the liquid pressures in a lower and upper liquid chambers at the compression stroke of a piston and having the liquid reduce in flow rate via a check valve to cause substitutional flow of the liquid inside the lower liquid chamber into a reservoir chamber by a compression stroke damping force generating means to generate the damping force. CONSTITUTION:The liquid pressure inside a lower liquid chamber B is increased at the compression stroke of a piston 2. At the same time, the liquid opens the piston check valve 9 of the piston 2 to flow into an upper liquid chamber A, whereby increasing the pressure therein to approximately the same level as the liquid pressure inside the liquid chamber B. When the liquid pressure in the lower liquid chamber B reaches the specified value, the liquid in said chamber B is reduced in flow rate by the compression-stroke damping force generating means 24 of a base check valve 17 and at the same time, substitutionally flows into a reservoir chamber D, whereby generating the compression-stroke damping force. Said damping force is adjusted according to the speed of the piston 2 by a damping force varying mechanism 31 which is mounted in a communication passage 28 which communicates the upper liquid chamber A with the reservoir chamber D. Without any creation of the cavitation in the upper liquid chamber, the damping force having a wide selection range can be generated.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a variable damping force hydraulic shock absorber.

Conventional technologyAs a hydraulic shock absorber used in the suspension system of automobiles, etc., the damping force variable type is used to adjust the damping force of the hydraulic shock absorber according to the driving conditions of the automobile. Hydraulic shock absorbers are known (for example, JP-A-60-196444).

This variable damping force hydraulic shock absorber is a double cylinder type in which an outer cylinder is placed outside the cylinder and a reservoir chamber is formed between the cylinder and the outer cylinder, and the cylinder filled with liquid is connected to the piston. The piston is divided into two upper and lower chambers, an upper liquid chamber and a lower liquid chamber, and the piston has a damping valve that operates during the extension sowing and compression strokes to generate a damping force, and a damping valve that is operated from the outside. The pace pulp installed at the lower end of the cylinder has a compression side reduction chamber which generates a damping force during the compression stroke, and the valve opens during extension sowing, allowing the pace pulp to flow from the reservoir chamber to the lower part. It is equipped with a check box that allows liquid to flow into the liquid chamber, and is intended to obtain a damping force that corresponds to the driving conditions of the vehicle.

Problems to be Solved by the Invention According to this conventional structure, the extension-side damping force generated when the liquid in the upper liquid chamber passes through the damping valve and flows into the lower liquid chamber when the piston is extended is applied to the piston. It can be set arbitrarily by the installed variable orifice. However, during the compression stroke of the piston, the damping valve installed on the piston and the compression-side damping valve installed on the pace pulp work together to generate a compression-side damping force. Therefore, when it is desired to increase the compression damping force, the damping force must be set taking into consideration the damping force of the pace pulp, and the compression damping force must be set arbitrarily by the variable orimeter installed on the piston. I can't.

In other words, the damping force on the compression side is controlled by the variable orimeter installed on the piston! Even if you want to increase the damping force, if you do not set the damping force variably within a range where the pressure in the upper liquid chamber does not become negative, cavitation will occur in the upper liquid chamber, causing abnormal noise and deterioration of riding comfort. There is a limit to how big a valve can be. It is also possible to change the compression damping valve of the pace pulp to a damping type that generates a large fA setting force so that the pressure in the upper liquid chamber becomes negative or positive, but damping is caused by a variable orifice installed in the piston. Even if the force is selected to be small, the pace pulp generates a high rt f force, resulting in the phenomenon that the damping force in the compression stroke cannot be reduced. Therefore, such a conventional Q lamp has a problem in that the width of the compression side damping valve cannot be increased. Therefore, an object of the present invention is to provide a variable damping force type hydraulic shock absorber that solves these problems.

Means to Solve the Problem The piston, which defines the cylinder into an upper liquid chamber and a lower liquid chamber, generates a damping force by replacing the liquid in the upper liquid chamber with the lower liquid chamber during the extension of the piston. A piston check valve is installed at the bottom of the cylinder to allow fluid to flow from the lower liquid chamber to the upper liquid chamber during the compression stroke of the piston. The pace check is equipped with a compression-side damping force generating means that generates a damping force by displacing the liquid in the lower liquid chamber to the reservoir chamber when the piston is extended, and allowing the liquid to flow from the reservoir chamber to the lower liquid chamber when the piston is extended. Pulp is attached,
In the communication passage that communicates the upper liquid chamber and the reservoir chamber, a cross section fJt′fI: f of the passage inserted in the middle of the communication passage in response to the hydraulic pressure in the cylinder is generated according to the floating speed of the piston. A damping force variable mechanism is attached to change the damping force.

In order to sow the extension of the working piston, the liquid pressure in the upper liquid chamber increases and the liquid pressure in the lower liquid chamber decreases, so that the liquid in the upper liquid chamber is throttled by the force generating means. I go to the lower liquid chamber while being pushed! The displacement flow generates a rebound damping force. Also, at this time, the base check valve opens to allow fluid to flow from the reservoir chamber to the lower liquid chamber, so that the lower liquid chamber is replenished with the amount of liquid that has withdrawn from the piston rod.

During the compression stroke of the piston, the liquid pressure in the lower and upper liquid chambers increases, and the liquid in the lower liquid chamber is squeezed by the compression-side damping force generating means of the base check valve and is replaced and circulated to the reservoir chamber, causing compression-side damping. generate force. Also, at this time, the liquid in the lower liquid chamber opens the piston valve of the piston and flows into the upper liquid chamber, so the lower liquid chamber and the lower liquid chamber have approximately the same pressure, and cavitation may occur in the upper liquid chamber. Prevented.

When the moving speed of the piston increases, the damping force uT attached to the communication passage that communicates the upper liquid chamber and the reservoir chamber increases.
The variable mechanism strengthens the damping force on the expansion and compression sides,
When the moving speed of the piston becomes slow, the damping force variable mechanism weakens the damping force on the expansion side and the compression side.

Example Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 to 4 show an embodiment of the present invention, in which 1 is a cylinder defined by a piston 2 into an upper liquid chamber A and a lower liquid chamber B, the inside of which is filled with liquid such as oil. It is a shaped cylinder. Reference numeral 3 designates an outer cylinder disposed outside the cylinder 1 and forming a reservoir chamber between the cylinder 1 and the cylinder 1. The upper part of the reservoir chamber is filled with gas, and the other part is filled with liquid such as oil. A piston rod 4 extends outside through one end of the cylinder 1. A piston mounting step 5 is formed at the tip of the piston rod 4, and the piston 2 is attached to the piston mounting step 5 together with a spacer 6.
is fitted and tightened with nut 7. A passage 8 is formed in the piston 2 to communicate the upper liquid chamber A and the lower liquid chamber B, and a piston check valve 9 is attached to the open end of the passage 8 on the upper liquid chamber A side. This piston check valve 9 has an outer cylindrical portion 1 fitted onto the piston 2.
a retainer 10 consisting of a flange portion 10b bent from the outer cylinder portion 10a and fitted into the spacer 6; a check spring 11 with a weak spring force supported by the retainer 10;
1, the check body 12 is urged downward (towards the end surface of the upper liquid chamber A side of the piston 2), a through hole 13 formed in the check body 12, and a passage 8 formed in the piston 2. Rebound damping force generating means 1 made of an elastic plate that blocks the
It consists of 4. The check body 12 and the extension side reduction force generating means 14 are connected to the outer cylindrical portion 10 of the retainer 10.
It is fitted into the book so that it can reciprocate between a and the spacer 6. Among these, the expansion 1ull damping force generating means 14 is
Since the notch 15 is formed in the surface of the piston 2 on the upper liquid gA side, the inner peripheral end can be deformed toward the lower liquid chamber B side. 16 is a passage formed in the beam taker 1o. Piston check valve 9 configured in this way
is the expansion side damping force generating means 1 during the compression stroke of the piston 2.
4 receives the hydraulic pressure of the lower liquid NB, compresses the check spring 11 via the check body 12, opens the passage 8, and allows liquid to flow from the lower liquid chamber B to the upper liquid chamber A. In addition, the piston check valve 9 is configured so that when the piston 2 starts to extend, the inner circumferential end of the extension damping force generating means 14 is bent downward under the hydraulic pressure of the upper liquid chamber A to open the through hole 13.
A damping force is generated to restrict the flow of liquid flowing from the upper liquid chamber A to the lower liquid chamber B via the through hole 13 and the passage 8.

17 is a pace check valve attached to the lower part of the cylinder 1. In detail, the base check valve 17 includes a valve body 18 fixed to the lower end of the cylinder 1 as shown in FIG. 2, and a substantially hat-shaped retainer 19 fixed to the upper part of the valve body 18. A check spring 20 supported by this retainer 19 and a lower valve body 18 supported by this check spring 20
The check body 21 is biased toward the side, and the check body 21 is interposed between the check body 21 and the valve body 18, and
A through hole 22 and a valve body 1 are fitted into the retainer 19 so as to be able to reciprocate and are bored in the check body 21.
The damping force generating means 24 on the compression side is made of an elastic plate and extends over a passage 23 (see FIG. 4) bored in the shaft 8. Reference numeral 25 denotes a notch formed on the surface of the valve body 18 facing the compression side damping force generating means 24. Moreover, since this notch 25 is formed, the inner peripheral end of the compression side damping force generating means 24 is formed. The part can be bent and deformed downward. 26 is a passage bored in the retainer 19, and 27 is a passage provided at the lower end of the valve body 18 for communicating the lower liquid chamber B and the reservoir chamber. The base check valve 17 configured in this manner is configured such that during the compression stroke of the piston 2, the inner peripheral end of the damping force generating means 24 is in the lower fluid chamber B.
When the liquid pressure reaches a predetermined value, the inner circumferential end bends downward to open the through hole 22, and the fluid flows from the lower liquid chamber B through the through hole 22 and passages 23 and 27 to the reservoir. A reducing force is generated to restrict the flow of liquid flowing into the chamber. In addition, the base check valve 17 receives the reduced hydraulic pressure of the lower liquid chamber B on one side and the hydraulic pressure of the reservoir chamber on the other side, so that when the piston 2 is extended, The check spring 20 is compressed via the check body 21 to open the passage 23 and allow liquid to flow from the reservoir chamber to the lower liquid chamber B.

28 is a communication path that communicates the upper liquid chamber A and the reservoir chamber. In this embodiment, this communication path 28 is connected to the cylinder 1.
A cylinder-side communication passage 28a, which is formed as a double structure and extends from the upper end of the cylinder 1 toward the lower end, and whose upper end opens to the upper liquid chamber A through the communication hole 29, and the base check valve 17. A side passage 30 formed in the valve body 18 and opening at the lower end of the cylinder side communication passage 28a
and a passage 27a that cooperates and communicates the side passage 30 and the reservoir chamber.

27 and a pace check side communication path 28b.

Reference numeral 31 denotes a side path 30 of the pace check side path 28b (an attached fA setting force variable mechanism). This damping force variable mechanism 31 is on the side 'N! Fixed at 30, this side road 309 Shimomishi.

A plurality of orifices 32 opening into the valve body 1
A fixed orifice housing 34 having a substantially U-shaped folded surface and having a communication hole 33 that communicates with the passage 27a of No. 8, and a shaft portion 35a and a side passage 30 fitted into the m fixed orifices 34 in a reciprocating state. A spool 35 having a substantially T-shaped cross section and a flange portion 35b that fits into the spool 35 is interposed between the flange portion 35b of this spool 35 and one end of the fixed orifice cylinder 34, and the spool 35 is held with a predetermined elastic force. Side road 30
A spring 36 that biases toward one end (in a direction away from the fixed orifice cylinder 34) and a flange portion 3 of the spool 350.
It is composed of an oil reservoir 37 recessed in one end of the side passage 30 located outside of the oil reservoir 5b, and a pressure control orifice 38 that communicates the oil reservoir 37 with the lower liquid chamber B.

39 is a communication hole 1t drilled in the pulp body 18 in order to communicate the side passage 30 in which the spring 3B is accommodated with the reservoir chamber via the passage 27. The damping force variable mechanism 31 configured in this manner is effective when driving on rough roads, etc.
When the moving speed of the piston 2 becomes faster and the hydraulic pressure in the lower liquid chamber B rises above a predetermined pressure, the spool 35 receives the hydraulic pressure in the 'F section liquid chamber B via the pressure control orifice 38,
The spring 36 is compressed and enters the fixed orifice cylinder 34 to close some of the plurality of orifices 32, thereby increasing the damping force during the extension and compression strokes of the piston 2. Furthermore, when the piston speed increases and the hydraulic pressure in the lower liquid chamber B increases, the damping force variable mechanism 31 closes all of the plurality of orifices 32 with the spool 35, so that the piston 2 does not extend. To further strengthen the damping force during seeding and compression strokes.

On the other hand, when the moving speed of the piston 2 slows down when driving on a good road, the hydraulic pressure in the lower liquid chamber B decreases, so the damping force variable mechanism 31 causes the spool 35 to be pushed back by the spring 36 and open the orifice 32. In order to do this, the damping force during the extension and compression strokes of the piston 2 is weakened. As described above, the damping force variable mechanism 31 causes the spool 35 to respond to the moving speed of the piston 2 (that is, the change in the fluid pressure in the lower fluid chamber B), so that the extension side damping force generating means 14 and the compression 1iIII damping force generating means 24 This is to adjust the strength of the damping force generated by A damping effect is produced by the oil sump 37 and the pressure control orifice 38,
Rapid movement of the spool 35 is prevented. Spool 35
It is determined by the set load and spring constant of the IL8 dynamic speed variable spring 36, the pressure jfjlJ, the diameter of the orifice 38, etc.

40 is a front guide disposed at the upper end of the cylinder 1 to slidably support the piston rod 4. 41 is disposed outside the rod guide 40, and is in close contact with the outer periphery of the piston rod 4 and the inner periphery of the outer periphery 3.
and a sealing device for sealing the upper end of the outer cylinder 3. 42 is a lid member fixed to the lower end of the outer cylinder 3 and sealing the lower end of the cylinder 1 and the outer periphery 3.

According to the structure of the above example, when the piston 2 is extended to sow, the liquid pressure in the upper liquid chamber A increases and the liquid pressure in the lower liquid chamber B decreases, so that the liquid in the upper liquid chamber A is used to check the piston. The liquid is throttled by the expansion side damping force generating means 14 of the valve 9, and is exchanged and circulated to the lower liquid chamber B to generate expansion side forces $ and f. This extension-side damping force is adjusted according to the speed of the piston 2 by a force variable mechanism 31 attached to the communication passage 28 that fully communicates with the upper liquid chamber A and the reservoir chamber. Also, at this time, the base check valve 17 is opened to allow the flow of liquid from the reservoir chamber to the lower liquid chamber B, so that the lower liquid chamber B is replenished with the amount of liquid withdrawn by the piston rod 4. . On the other hand, during the compression stroke of the piston 2, the hydraulic pressure in the lower liquid chamber B increases, but this hydraulic pressure also flows into the upper liquid chamber A by opening the piston check valve 9 of the piston 2, and flows into the upper liquid chamber A. Increase the fluid pressure in A to approximately the same level as in lower fluid chamber B, and lower fluid pressure in lower fluid chamber B.
When the liquid pressure reaches a predetermined value, the liquid in the lower liquid chamber B is throttled by the compression-side damping force generating means 24 of the base check valve 17 and flows to the reservoir chamber to generate a compression-side damping force. This compression side damping force is adjusted according to the speed of the piston 2 by a damping force variable mechanism 31 attached to the communication passage 28 that communicates the upper liquid chamber A and the reservoir chamber.

FIG. 5 shows an example of application of the above embodiment, in which the same parts as in the above embodiment are denoted by the same reference numerals, and redundant explanations will be omitted. That is, in this application example, a damper liquid chamber C is formed at one end of the side passage 30 of the base check valve 17, and the damper liquid chamber C and the lower liquid chamber B are connected to a pressure introduction hole bored in the pulp body 18. A check valve 45 is provided between the communication path 44 and the damper liquid chamber C to allow liquid to flow from the lower liquid chamber B to the damper liquid chamber C. It is. The check valve 45 includes a valve body 47 seated on a seat portion 46 protruding from the open end of the communication passage 44, and a spring 48 that biases the valve body 47 toward the seat portion 46 with a weak spring force. A pressure control orifice 49 is provided approximately in the center of the valve body 47.
At the same time, a communication groove 50 is formed at the outer peripheral end of the valve body 47.
A notch is formed. By configuring like this,
When the liquid pressure in the lower liquid chamber B rises above a predetermined pressure, the liquid in the lower liquid chamber B passes through the pressure introduction hole 43 and the communication passage 44, opens the check valve 45, and enters the damper liquid chamber C. The spool 35 of the variable damping force mechanism 31 is pushed into the fixed orifice segment 34, and the opening area of the orifice 32 is engaged to adjust the damping force. On the other hand, when the liquid pressure in the lower liquid chamber B drops, the check valve 45 closes the communication passage 44, and the liquid in the damper liquid chamber C is throttled by the pressure control orifice 49 and flows to the lower liquid chamber B. gradually returns to a position where the biasing force of the spring 36 and the hydraulic pressure in the lower liquid chamber B are balanced. In this way, a sudden return operation of the spool 35 is prevented and the opening area of the orifice 32 is stably maintained.

FIGS. 6 and 7 show another embodiment of the present invention, in which the same parts as in the previous embodiment are denoted by the same reference numerals, and redundant explanations will be omitted. That is, in this embodiment, the piston check valve 9 is attached to the piston 2, and the base check valve 17 is attached to the lower end of the cylinder 1, which is the same as in the above embodiment. The configuration is different.

Here, 51 is a cylinder side communication passage that extends from the upper part to the lower part of the cylinder 1 and has a lower end communicating with the reservoir chamber through a communication hole 52. 53 is a front guide side communication passage formed in the rod guide 40 and communicating the upper liquid chamber A and the cylinder side communication passage 51.

This front guide side communication passage 53 has an I oil direction passage 53a formed on the inner periphery of the rod guide 40, one end opens to this axial direction passage 53a, and the other end opens to the cylinder 1 UN passage 51. It consists of a radial passage 53b. Then, the cylinder side communication passage 51 and the front guide side communication passage 53
A communication path 54 that communicates the upper liquid chamber A and the reservoir chamber is configured by these. 55 is rod guide +t
l! This is a damping force variable mechanism interposed in the middle of the passage 53b of the l communication passage 53. This damping force variable mechanism 55 has a passage 5
A spool 56 that changes the passage cross-sectional area of 3b, and a spool 56 that slidably accommodates this spool 56.It is disposed at one end of the P chamber E and allows liquid to flow from the upper liquid chamber A to the spool valve chamber E. It consists of a check valve 57 and a spring 58 which is disposed at the other end of the spool valve chamber E and urges the spool 56 in the valve opening direction (towards one end of the spool valve chamber E). Of these, the check valve 57 is seated at the spool 1tlQ end 60 of a pressure introduction hole 59 formed in the rod guide 40 and communicating the upper liquid chamber A and the spool valve chamber E, as shown in FIG. 7 in detail. The check valve body 61 is made up of a check valve body 61, a check spring 62 that urges the check valve body 61 toward the pressure introduction hole 59 side with a weak spring force, and a support body 63 that supports the check spring 62.

The check valve body 61 has a pressure control orifice 64 formed approximately in the center, and a communication γ 485 at the outer peripheral end.
is formed with a notch. With this configuration, when the moving speed of the piston 2 increases when driving on a rough road, etc., and the hydraulic pressure in the upper liquid chamber A rises to a predetermined pressure or more, the liquid in the upper liquid chamber A opens the check valve 57. It flows into one end side of the spool valve chamber E from the valve valve and the pressure introduction hole 59, and the spool 5
6 to the other end of the spool valve chamber E. Therefore,
The cross-sectional area of the passage 53b is narrowed by the spool 5B, thereby increasing the damping force. On the other hand, when traveling on a good road, etc., when the moving speed of the piston 2 slows down and the hydraulic pressure in the upper liquid chamber A decreases, the check valve 57 closes and the liquid in the spool valve chamber E is throttled by the pressure control orifice 64. Since the liquid flows out to the upper liquid chamber A side, the spool 56 is urged by the spring 58 and returns gently. In this way, as in the application example described above, it is possible to prevent the spool 56 from returning suddenly.

FIG. 8 shows an example of a damping force characteristic diagram obtained by the variable damping force type hydraulic shock absorber of the present invention, and (I) shows the damping force obtained by the extension side reduction force generating means 14. ,
(■) indicates the damping force obtained by the compression side damping force generating means 24, and (1) indicates the damping force obtained by the operation of the damping force variable mechanism 31. In this figure, point a indicates the set load of the springs 36 and 58 that bias the variable damping force mechanisms 31 and 55.

Effects of the Invention As described above, the present invention generates a damping force by displacing and circulating the liquid in the upper liquid chamber into the lower tfIi chamber during the extension of the piston, which divides the cylinder into upper and lower parts. It is equipped with a damping force generating means on the expansion side, and a piston check valve is attached to the piston's pressure seeding device to allow fluid to flow from the lower liquid chamber to the lower liquid chamber. The base is equipped with a compression-side damping force generating means that generates a damping force by displacing and circulating the liquid in the lower liquid chamber to the reservoir chamber during first seeding, and allows liquid to flow from the reservoir chamber to the lower liquid chamber during piston extension seeding. A check valve is attached to the communication passage that communicates the upper liquid chamber and the reservoir chamber, and the cross-sectional area of the passage inserted in the middle of the communication passage is changed in response to the pressure inside the cylinder, and the piston is Since it is equipped with a damping force OT variable mechanism that changes the generated damping force according to the moving speed, the entire damping force can be set independently and arbitrarily in each of the piston extension stroke and compression stroke, which prevents cavitation in the upper liquid chamber. This has a great practical effect in that it is possible to freely obtain a wide range of damping forces depending on the characteristics of the vehicle without causing any damage, and there is no need for an external actuator to operate the variable damping force mechanism, thereby reducing the cost of products.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
An enlarged view of the lower end of the figure, FIG. 3 is a diagram of the operating state of the variable damping force mechanism, FIG. 4 is an IV-IV analysis view of FIG. 2, and FIG. 5 is a cross-section of the main part showing an application example of the present invention 6 is a sectional view showing another embodiment of the present invention, FIG. 7 is a partial enlarged view of the same damping force variable mechanism, and FIG. 8 is a damping force characteristic diagram. DESCRIPTION OF SYMBOLS 1... Cylinder, 2... Piston, 9... Piston check valve, 14... Rebound damping force generation means, 1
7...Base check valve, 24...Compression side damping force generating means, 28.54...Communication path, 31.55...
・Variable damping force mechanism, 32° design, B...lower liquid chamber, D
...Reservoir room. 2 people outside Figure 8

Claims (1)

[Claims] (1) A cylinder defined by a piston into an upper liquid chamber and a lower liquid chamber, and a cylinder disposed outside the cylinder,
The piston is provided with an outer cylinder that forms a reservoir chamber between the cylinder and a communication passage that communicates the upper liquid chamber of the cylinder with the reservoir chamber. The piston is provided with a rebound damping force generating means for displacing and circulating liquid into the lower liquid chamber to generate a damping force, and is provided with a piston check valve that allows liquid to flow from the lower liquid chamber to the upper liquid chamber during the compression stroke of the piston. Further, the lower part of the cylinder is provided with compression side damping force generating means for displacing and circulating the liquid in the lower liquid chamber to the reservoir chamber during the compression stroke of the piston to generate a damping force, and the means for generating damping force is provided in the lower part of the cylinder to generate damping force during the compression stroke of the piston. A base check valve is provided that allows liquid to flow from the chamber to the lower liquid chamber, and the communication passage is further provided with a cross-sectional area of a passage interposed in the middle of the communication passage in response to the hydraulic pressure in the cylinder. 1. A variable damping force type hydraulic shock absorber, characterized in that a variable damping force mechanism is provided for changing the generated damping force in accordance with the moving speed of the piston.