JPH08142630A - Self-pumping type shock absorber - Google Patents

Abstract

PURPOSE: To prevent the excess/shortage of the damping force as the whole shock absorber when the load on a vehicle is large. CONSTITUTION: A shock absorber is provided with a damping force generating valve, a low pressure chamber 22, a high pressure chamber 32 to be communicated with an upper chamber 52 as a working fluid chamber, and a pump 104 to feed the oil from the low pressure chamber to the high pressure chamber by the relative movement in the contraction direction between a piston 34 and a cylinder 10, while a pump is provided with a pump cylinder member 46 which is slidably arranged in a rod part 36 of the piston, and a pump rod 48 to demarcate a pump chamber in cooperation with the pump cylinder member. The pump cylinder member is supported so as to be moved in the advancing direction of the pump rod when the pressure in the pump chamber 50 is above the prescribed value, and a communication control valve 106 to communicably connect the upper chamber 52 to a lower chamber 54 when the pump cylinder member is moved is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber, and more particularly to a self-pumping type shock absorber.

[0002]

2. Description of the Related Art As one of shock absorbers for vehicles such as automobiles, as disclosed in, for example, Japanese Patent Laid-Open No. 59-159441, they are relatively reciprocally fitted to each other and cooperate with each other. A piston and a cylinder that demarcate the chamber and the lower chamber, a damping force generating valve provided on the piston, a low pressure chamber, a high pressure chamber that communicates with the upper chamber, and a pump whose volume is increased or decreased by relative movement of the piston and the cylinder. A pump having a chamber, and a communication control mechanism that communicates with the low pressure chamber and the upper chamber when the shock absorber extends by a predetermined amount or more,
The pump is a pump cylinder member arranged in the rod portion of the piston, and a pump rod that is fitted to the pump cylinder member so as to reciprocate, is fixed to the cylinder at one end, and cooperates with the pump cylinder member to define the pump chamber. And a suction valve that allows the flow of oil from the low pressure chamber to the pump chamber, and a discharge valve that allows the flow of oil from the pump chamber to the upper chamber, the low pressure due to the suction stroke corresponding to the extension stroke of the shock absorber. 2. Description of the Related Art A self-pumping type shock absorber configured to suck oil from a chamber to the pump chamber and discharge the oil from the pump chamber to the upper chamber by a discharge stroke corresponding to the contraction stroke of the shock absorber has been conventionally known.

According to such a self-pumping type shock absorber, when the shock absorber repeatedly expands and contracts, the suction stroke and the discharge stroke of the pump are also repeated, whereby oil is supplied from the low pressure chamber to the upper chamber and the lower chamber via the pump. The shock absorber gradually expands, and when the expansion amount of the shock absorber reaches a predetermined amount, the communication control mechanism prevents the shock absorber from expanding further. Even if the vehicle repeatedly bounces and rebounds as the vehicle travels, the vehicle height can be automatically returned to the standard vehicle height. Therefore, the vehicle height can be adjusted to the shock absorber without using an electric pump. Can have

[0004]

In the above-mentioned conventional self-pumping type shock absorber, the discharge stroke of the pump is performed during the compression stroke of the shock absorber, and the pressure inside the pump chamber is changed during the discharge stroke of the pump. The pump rod is driven against this, and the pressure inside the pump chamber rises as the load on the vehicle increases, so the shock absorber as a whole, which is the sum of the damping force generated by the damping force generation valve and the reaction force of the pump, There is a problem that the damping force during the contraction stroke becomes too high as the load of the vehicle increases, and the riding comfort of the vehicle deteriorates.

In order to solve such a problem, even if the amount of increase in the damping force during the compression stroke of the shock absorber as a whole accompanying the increase in the vehicle load is set to an optimum value, the higher the pressure in the pump chamber, Since the pump reaction force during the suction stroke of the pump is small, the damping force of the shock absorber as a whole during the extension stroke is insufficient when the vehicle has a high load, and the steering stability of the vehicle is likely to deteriorate.

The present invention has been made in view of the above-mentioned problems in the conventional self-pumping type shock absorber, and the main object of the present invention is to provide a shock absorber when the vehicle has a high load. By reducing the damping force generated by the damping force generation valve during the compression stroke of the shock absorber, or by increasing the damping force generated by the damping force generation valve during the expansion stroke of the shock absorber, the damping force of the shock absorber as a whole is increased. The purpose is to prevent shortage, thereby improving the ride comfort of the vehicle while ensuring good steering stability of the vehicle.

[0007]

SUMMARY OF THE INVENTION According to the present invention, the above-mentioned main problem is that the first and second working fluid chambers are defined so as to be relatively reciprocally fitted to each other and cooperate with each other. A piston and a cylinder, a damping force generating valve provided on the piston or the cylinder, a low pressure chamber, a high pressure chamber communicating with the first and second working fluid chambers, and a contraction direction of the piston and the cylinder. A pump cylinder that supplies a working fluid from the low pressure chamber to the high pressure chamber by relative movement to the pump cylinder member, the pump cylinder member slidably arranged in the rod portion of the piston, and the cylinder at one end. And a pump rod fixed to the pump cylinder member so as to reciprocate and cooperating with the pump cylinder member to define a pump chamber. The pump cylinder member is supported in the rod portion so as to move in a direction in which the pump rod enters the pump cylinder member when the pressure in the pump chamber is equal to or higher than a predetermined value. A self-pumping shock absorber (composition of claim 1), characterized in that a communication control valve is provided which connects the first and second working fluid chambers to each other. A piston and a cylinder that cooperate with each other to demarcate the first and second working fluid chambers, a damping force generation valve for extension stroke and compression stroke, which is provided in the piston, a low pressure chamber, and the first and second A high-pressure chamber communicating with the second working-fluid chamber and a working fluid from the low-pressure chamber to the high-pressure chamber by relative movement of the piston and the cylinder in the contraction direction. And a pump cylinder member slidably arranged in the rod portion of the piston, and a pump cylinder member fixed at one end to the cylinder and reciprocally fitted to the pump cylinder member. In a self-pumping shock absorber having a pump rod that cooperates with a pump cylinder member to define a pump chamber, the extension stroke damping force generating valve attaches a valve element and the valve element to a closed position. Urging spring means, and the spring means is supported by the pump cylinder member, and the pump cylinder member is directed in a direction in which the pump rod enters the pump cylinder member when the pressure in the pump chamber is a predetermined value or more. It is supported in the rod part by an elastic member so as to move,
A self-pumping shock absorber (composition of claim 2), or a relative reciprocating motion, characterized in that the urging force of the spring means on the valve element is reduced when the pump cylinder member moves. A piston and a cylinder that fit together and cooperate with each other to define the first and second working fluid chambers, a damping force generation valve provided in the piston or the cylinder, a low pressure chamber, and A self-pumping shock absorber having a high pressure chamber that communicates with the first and second working fluid chambers, and a pump that supplies working fluid from the low pressure chamber to the high pressure chamber by relative movement of the piston and the cylinder in the direction of contraction. In the above, a communication passage that connects the working fluid chamber whose volume decreases during the extension stroke of the shock absorber and the high pressure chamber, and the communication passage An on-off valve provided inside thereof to open and close in response to a pressure in the high-pressure chamber, and the on-off valve is configured to close when the pressure in the high-pressure chamber is equal to or higher than a predetermined value. This is achieved by a self-pumping shock absorber (construction of claim 3).

[0008]

According to the above-mentioned structure of the first aspect, the pump cylinder member is supported in the rod portion so as to move in the approaching direction of the pump rod with respect to the pump cylinder member when the pressure in the pump chamber exceeds a predetermined value. Since the communication control valve that connects the first and second working fluid chambers to each other when the cylinder member moves is provided, when the vehicle load becomes high and the pressure in the pump chamber exceeds a predetermined value, the communication control valve The first and second working fluid chambers are communicatively connected, and a part of the working fluid flowing from one working fluid chamber to the other working fluid chamber during the compression stroke of the shock absorber passes through the communication control valve, and the damping force generating valve The flow rate of the working fluid flowing through the shock absorber is reduced, and the damping force generated by the damping force generation valve is reduced. Force is reduced.

According to a second aspect of the present invention, the damping force generating valve for extension stroke includes a valve element and spring means for urging the valve element to a closed position, and the spring means is supported by the pump cylinder member. The pump cylinder member is supported in the rod portion by the elastic member so that the pump cylinder member moves in the approaching direction of the pump rod with respect to the pump cylinder member when the pressure in the pump chamber is equal to or higher than a predetermined value. Since the urging force of the means against the valve element is reduced, when the pressure in the pump chamber exceeds a predetermined value due to an increase in the vehicle load, the urging force of the spring means against the valve element of the damping force generating valve is increased. By reducing the damping force generated by the damping force generation valve, the damping force during the compression stroke of the shock absorber as a whole is reduced.

According to the third aspect of the present invention, the communication passage for connecting the working fluid chamber and the high pressure chamber, the volume of which is reduced during the extension stroke of the shock absorber, and the pressure inside the high pressure chamber, which is provided in the middle of the communication passage. Has an on-off valve that opens and closes in response,
The on-off valve is configured to close when the pressure in the high pressure chamber is equal to or higher than a predetermined value, so that when the pressure in the high pressure chamber becomes equal to or higher than the predetermined value due to an increase in the vehicle load, the on-off valve closes. The communication between the high pressure chamber and the working fluid chamber, whose volume decreases during the extension stroke of the shock absorber, is cut off,
All the working fluid in the working fluid chamber, the volume of which decreases during the extension stroke of the shock absorber, passes through the damping force generation valve, whereby the damping force generated by the damping force generation valve during the extension stroke is increased.

[0011]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing a first embodiment of a self-pumping shock absorber according to the present invention, FIG.
Is an enlarged partial vertical sectional view showing the intake valve of the first embodiment and its vicinity, FIG. 3 is an enlarged partial vertical sectional view showing the discharge valve of the first embodiment and its vicinity, and FIG. 4 is a first embodiment. FIG. 3 is an enlarged partial vertical sectional view showing the communication control valve of FIG. The right half of FIG. 4 shows the case where the pressure inside the pump chamber is low, and the left half of FIG. 4 shows the case where the pressure inside the pump chamber is high.

In these drawings, reference numeral 10 denotes a cylinder, which includes an inner cylinder 14 and an outer cylinder 16 extending concentrically with each other along an axis 12. The upper end of the outer cylinder 16 is closed by an end cap 16A which is integral with the outer cylinder 16, and the end cap 18 is fixed to the lower end of the outer cylinder 16. The inner cylinder 14 has a support member 20 at an upper portion.
Is fixed to the outer cylinder 16 by means of, and is fixed to the outer cylinder by the end cap 18 and seal caps 19A, 19B at the lower end.

The support member 20 cooperates with the partition member 21 fixed to the lower end of the support member 20 and the outer cylinder 16 to define an annular low-pressure chamber 22, and the low-pressure chamber 24 has a low-pressure gas 24.
Also, an oil 26 as a working fluid is enclosed. Below the partition wall member 21, a substantially cylindrical diaphragm 28 is arranged in an annular space between the inner cylinder 14 and the outer cylinder 16. The diaphragm 28 is fixed to the partition member 21 at the upper end and the end cap 1 at the lower end.
It is fixed to No. 8 and thereby defines a gas chamber 30 in which a high pressure gas is filled on the outside in the radial direction and a high pressure chamber 32 in which a high pressure oil 26 is filled inside in the radial direction.

A piston 34 is disposed in the inner cylinder 14 so as to be capable of reciprocating along the axis 12. The piston 34 is a piston rod 36 extending along the axis 12.
And a piston body 3 fixed to the upper end of the piston rod
It consists of eight. The piston body 38 is provided with a damping force generation valve 40 for extension stroke and a damping force generation valve 42 for compression stroke which are known per se. Piston rod 36
Has a hollow hole 44 extending along the axis 12, and a pump cylinder member 46 extending along the axis 12 is disposed in the hollow hole 44 so as to be slidable along the axis.

A pump rod 48 extending along the axis 12 is fitted in the pump cylinder member 46 so as to be capable of reciprocating relative to the pump cylinder member, and the pump rod 48 has a support member 20 and the like at its upper end. Outer cylinder 1
It is fixed to 6 and cooperates with the pump cylinder member to define the pump chamber 50. The piston 34 is the inner cylinder 1
4 and the support member 20, the spacer washer 49, the inner cylinder 14, and the pump rod 48 cooperate with each other to define the upper chamber 52 as a working fluid chamber, and the inner cylinder 14 and the seal cap 19B. Together, they define the lower chamber 54 as a working fluid chamber. The upper end of the upper chamber 52 is connected to the upper end of a high-pressure passage 55 defined between the inner cylinder 14, the support member 20, and the partition member 21.

The pump rod 48 is provided with a low-pressure passage 56 extending along the axis 12, and the upper end of the low-pressure passage 56 is an intermediate section defined between the upper end of the support member 20 and the end cap 16A. A conduit 60 fixed to the chamber 58 and the support member 20 communicates with the lower portion of the low pressure chamber 22. A communication hole 62 that communicates with the low-pressure passage 56 at the inner end and opens at the outer surface of the pump rod at the outer end and extends in the radial direction is provided at the center of the pump rod 48 in the longitudinal direction. Particularly in the illustrated embodiment, the lower portion of the pump rod 48 is tapered so that the clearance between the pump rod and the pump cylinder member 46 is set to gradually decrease as the vehicle height increases. Has been done.

As shown in detail in FIG. 2, a suction valve 64 is provided at the lower end of the pump rod 48. The intake valve 64 includes a substantially plate-shaped valve element 66, a substantially cup-shaped support member 68 fixed to the lower end of the pump rod 48 at the upper end, and a resilient member mounted between the valve element 66 and the support member 68. And a compression coil spring 70 for biasing the valve element to the illustrated closed position where it abuts the lower end of the pump rod 48. The support member 68 is provided with a communication hole 72 such as a slit or a hole that connects the inside of the support member 68 to the pump chamber 50. The suction valve 64 allows the flow of oil from the low pressure passage 56 toward the pump chamber 50, but functions as a check valve that blocks the flow of oil from the pump chamber toward the low pressure passage.

Further, as shown in detail in FIG. 3, a cup-shaped support member 76 is fixed to the lower end portion of the pump cylinder member 46 by a ring 74, and the support member 76 slides along the axis 12. It fits in the hollow hole 44 as much as possible. A discharge valve 78 is provided inside the support member 76 and below the pump cylinder member 46. The discharge valve 78 includes a substantially plate-shaped valve element 80, a valve element 80 and a support member 76.
And a compression coil spring 82 which is resiliently mounted between the valve element and the bottom wall thereof to urge the valve element to the illustrated closed position where it abuts the lower end of the pump cylinder member 46.

A compression coil spring 84 and a shim 86 as elastic members are arranged between the support member 76 and the bottom wall of the hollow hole 44, whereby the pump cylinder member 46 is shown in the figure via the support member. And is biased upward, and is positioned by being pressed against a lock nut 87 fixed to the upper end of the piston rod 36 as shown in the right half of FIG. Thus, when the pressure in the pump chamber 50 of the pump cylinder member 46 becomes a predetermined value or more and a downward force equal to or greater than the spring force of the compression coil spring 84 acts, the pump rod 48 enters the lower part of the drawing, that is, the pump cylinder member. It is supported in the piston rod 36 so as to move in the direction.

A plurality of grooves 88 extending in the longitudinal direction are provided on the inner surface of the cylindrical portion of the support member 76. A plurality of grooves extending in the longitudinal direction are provided on the outer peripheral surface of the pump cylinder member 46 or the inner peripheral surface of the pump rod 48, and the plurality of grooves that connect the groove 88 and the upper chamber 52 to each other are provided by these grooves. The communication passage 90 is bounded. The discharge valve 78 allows the flow of oil from the pump chamber 50 toward the communication passage 90, but functions as a check valve that blocks the flow of oil from the communication passage toward the pump chamber.

Further, as shown in detail in FIG. 4, the lock nut 87 has a communication hole for connecting the upper end of the communication passage 90 to the upper chamber 52 through an intermediate chamber 92 between the lock nut 87 and the upper end of the piston rod 36. It has 94. Further, the piston rod 36 is provided with a communication hole 96 below the piston body 38 for connecting the communication passage 90 and the lower chamber 54. The pump cylinder member 46 is integrally formed with a land portion 98 that is substantially closely fitted to the hollow hole 44. The land portion 98 has a communication passage 90 above it and a communication passage below it. A communication hole 99 for communication connection is provided.

As shown in the right half of FIG. 4, the land portion 98 has the lock nut 8 at the upper end of the pump cylinder member 46.
7, the communication hole 96 and the communication passage 90 are cut off from each other, and when the pump cylinder member 46 moves downward, the communication hole 96 and the communication passage 90 are allowed to communicate with each other. Therefore, the land portion 98 and the communication hole 96 cooperate with each other to define a communication control valve 106 that controls the communication between the upper chamber 52 and the lower chamber 54 according to the pressure in the pump chamber 50.

Further, as shown in FIG. 1, a connecting member 100 is integrally provided at the lower end of the piston rod 36. Although not shown in the drawing, a connecting member 100 is provided between the connecting member 100 and the seal cap 19A. Has dust boots. Also, the end cap 1 on the upper end of the outer cylinder 16
A connecting member 102 is integrally fixed to 6A, and the shock absorber is connected to the vehicle body by a connecting member 102 via a rubber bush not shown in the drawing, and is not shown in the drawing by a connecting member 100. It is adapted to be connected to a suspension member such as a suspension arm via a rubber bush.

As can be understood from the above description, the high pressure passage 55 defines high pressure passage means for connecting the upper chamber 52 and the high pressure chamber 32 to each other, and the conduit 60, the intermediate chamber 58 and the low pressure passage 56 include the low pressure chamber 22. And the pump chamber 50 are connected to each other to define a low pressure passage means, and the communication hole 62 cooperates with the upper end of the pump rod 48 to relatively displace the piston 34 and the cylinder 10 in the extending direction by a predetermined amount or more, that is, When the vehicle height becomes higher than the standard vehicle height, a communication control means for connecting the upper chamber 52 and the low pressure passage 56 to each other is defined.

The extension stroke damping force generating valve 40 and the contraction stroke damping force generating valve 42 define damping force generating means for generating a damping force in response to a wheel bound and rebound. Pump cylinder member 46, pump rod 4
8, the suction valve 64, the discharge valve 78, and other members move above and below the low-pressure chamber 22 via the low-pressure passage means as the shock absorber expands and contracts due to wheel bounding and rebound to increase and decrease the volume of the pump chamber 50. A pump 104 for pumping oil to the chamber 52 is defined.

In the first embodiment constructed as described above, when the piston 34 and the cylinder 10 move relative to each other in the extension stroke due to the rebound of the wheel (not shown), the volume of the upper chamber 52 increases. As the volume of the lower chamber 54 decreases, the oil in the lower chamber moves to the upper chamber through the piston body 38, and the damping force generating valve 40 generates the damping force in the extension stroke. Further, in the extension stroke of the shock absorber, the volume of the pump chamber 50 increases and the pressure in the pump chamber decreases, so that the discharge valve 78 is closed and the suction valve 64 is opened, and the low pressure chamber is opened. 22 from conduit 60,
Oil is sucked into the pump chamber 50 through the intermediate chamber 58, the low pressure passage 56, and the suction valve 64, whereby the suction stroke of the pump 104 is performed, and the damping force of the entire shock absorber is generated by the damping force generation valve 40. It is the sum of the damping force and the reaction force of the pump 104.

On the other hand, in the compression stroke of the shock absorber, the volume of the upper chamber 52 decreases and the volume of the lower chamber 54 increases, but when the pressure in the pump chamber 50 is less than a predetermined value, the communication control valve 106 closes. The valve state is maintained, the communication passage 90 and the lower chamber 5
Since the communication with 4 is cut off, the oil in the upper chamber moves to the lower chamber only through the damping force generating valve 42,
The damping force generation valve 42 generates a damping force in the compression stroke. Further, since the volume of the pump chamber 50 decreases and the pressure inside the pump chamber rises, the suction valve 64 is closed and the discharge valve 78 is opened, so that the discharge valve 7 is discharged from the pump chamber 50.
8, the groove 88, the communication passage 90, the communication hole 99, the intermediate chamber 92, and the communication hole 94, the oil is discharged and supplied to the upper chamber 52, whereby the discharge stroke of the pump 104 is performed, and the damping force of the shock absorber as a whole. Is the sum of the damping force generated by the damping force generation valve 42 and the reaction force of the pump 104.

On the other hand, for example, the pressure in the pump chamber 50 becomes a predetermined value or more due to an increase in the load, and the communication control valve 10
When the valve 6 is opened, the communication passage 90 and the lower chamber 54 communicate with each other through the communication hole 96.
The oil in the upper chamber moves not only to the damping force generation valve 42 but also to the lower chamber through the communication hole 94, the intermediate chamber 92, the communication passage 90, and the communication hole 96, so that the damping force generation valve 4
The flow rate of the oil passing through 2 is reduced, so that the damping force in the contraction stroke is reduced as compared with the case where the oil does not flow to the lower chamber via the communication control valve 106, thereby avoiding excessive damping force. As a result, the riding comfort of the vehicle is improved.

Further, in this case, since the valve opening amount of the communication control valve 106 increases as the pressure in the pump chamber 50 increases, the degree of reduction of the damping force when the oil does not flow to the lower chamber via the communication control valve 106 is the same. The higher the pressure in the chamber 50, that is, the higher the load, the higher the load. Therefore, the increase rate of the damping force during the compression stroke of the shock absorber as a whole with the increase of the load increases the oil communication control valve 106.
It becomes smaller than the case where it does not flow to the lower chamber via.

When the suction stroke and the discharge stroke of the pump 104 are repeated in this way, the amount and pressure of oil in the upper chamber 52, the lower chamber 54 and the high pressure chamber 32 increase, which causes the piston 34 and the cylinder 10 to expand. However, when the communication hole 62 is located above the upper end of the pump cylinder member 46, the upper chamber 52 is communicatively connected to the low pressure passage 56 by the communication hole 62, and a part of the oil in the upper chamber 52 is displaced. Is discharged to the low pressure chamber 22, and thereby the piston 34 and the cylinder 10 are positioned relative to each other so that the communication hole 62 is located at the position of the upper end of the pump cylinder member 46. Therefore, even if the vehicle load changes and the vehicle height fluctuates, the vehicle height is determined by the position of the communication hole 62 by the pumping action of the pump 104 and the positioning action of the communication hole 62 which are performed by the expansion and contraction of the shock absorber. The standard vehicle height will be automatically restored.

FIG. 5 shows an enlarged partial longitudinal section showing the pistunt body of the second embodiment of the self-pumping type shock absorber according to the present invention and the vicinity thereof when the pressure in the pump chamber is low (right half) and high (left half). It is a side view. 5, parts corresponding to the parts shown in FIG. 4 are designated by the same reference numerals as those shown in FIG.

In this second embodiment, the land portion 98
Is provided near the upper end of the pump cylinder member 46 and at a position higher than in the case of the first embodiment.
9 does not have a communication hole corresponding to 9, and thus the communication passage 90 is blocked from the intermediate chamber 92 by the land portion 98. Further, the lower end of the compression coil spring 42 </ b> B that urges the valve element 42 </ b> A of the compression-side damping force generating valve 42 to the valve closing position where it abuts the piston body 38 is supported by the spring seat member 110.

In the illustrated embodiment, the spring seat member 110.
Is a half-split type, and is composed of an arcuate portion 110A that supports the lower end of the compression coil spring 42B and a plurality of spoke portions 110B that are integral with the arcuate portion and extend in the radial direction. It is integrally held in an annular shape by 112. Each spoke 110B has a piston rod 3
6 extends through a hole 114 formed in 6 and tightly fits in a groove 116 formed in the pump cylinder member 46 at the inner end, whereby the spring seat member 110 is integrally supported by the pump cylinder member. Has been done. The holes 114 receive the spokes 110B so as to be capable of reciprocating along the axis 12, and always connect the communication passage 90 and the lower chamber 54 to each other.

The second embodiment is configured in the same manner as the first embodiment except for the other points. Therefore, in this embodiment, the communication passage 90 is provided in the compression stroke of the shock absorber.
As in the case of the first embodiment, except that oil is discharged and supplied to the lower chamber 54 through the hole 114, the pump (10
Even when the suction stroke and the discharge stroke of 4) are performed and the vehicle loading load fluctuates and the vehicle height fluctuates, the pumping action of the pump (104) performed by the expansion and contraction of the shock absorber and the communication hole (62). Due to the positioning action, the vehicle height is automatically returned to the standard vehicle height determined by the position of the communication hole.

In the extension stroke of the shock absorber, the oil in the lower chamber 54 moves to the upper chamber 52 via the damping force generation valve 40, and the damping force generation valve 40 generates the damping force in the extension stroke. However, in the compression stroke of the shock absorber, when the pressure in the pump chamber 50 is less than the predetermined value, the spring seat member 110 is maintained in the position shown in the right half of FIG. The damping force generating valve 42 generates a damping force in the contraction stroke while the biasing force of the compression coil spring 42B that biases the valve element 42A of 42 to the closed position is maintained at a high value.

On the other hand, the pressure in the pump chamber 50 exceeds a predetermined value due to an increase in the load, and the pump cylinder member 46 is moved downward, whereby the spring seat member 110 is shown in the left half of FIG. If the urging force of the compression coil spring 42B with respect to the valve element 42A is reduced when the urging force of the compression coil spring is constant, the damping force generation valve 42 generates The damping force applied to the vehicle is reduced, which prevents the damping force from becoming excessive, thereby improving the riding comfort of the vehicle.

Further, in this case, the amount of downward movement of the spring seat member 110 increases as the pressure inside the pump chamber 50 increases, so the degree of reduction of the damping force relative to the case where the biasing force of the compression coil spring is constant is the pump chamber. The higher the pressure in 50,
That is, the higher the load becomes, the larger the load becomes. Therefore, the rate of increase of the damping force in the compression stroke of the shock absorber as a whole due to the increase in the load becomes smaller than that when the biasing force of the compression coil spring 42B is constant.

FIG. 6 is an enlarged partial vertical sectional view showing the opening / closing valve of the third embodiment of the self-pumping type shock absorber according to the present invention and the vicinity thereof. 6, parts corresponding to the parts shown in FIG. 1 are denoted by the same reference numerals as those given in FIG.

In the third embodiment, although not shown in the drawing, the pump cylinder member 46 is fixed by the piston rod 36 so as not to move even if the pressure in the pump chamber 50 increases. Supported by the public. Although not shown in the drawing, the communication hole 96 and the land portion 98 in the first embodiment are not provided, and the land portion 98 and the hole 114 in the second embodiment are provided. The spring seat member 110 is fixedly supported by the piston rod 36. Further, regarding the degree of restriction of the damping force generating valve 40 for the compression stroke, the inner diameter of the pump cylinder member 46, the outer diameter of the pump rod 48, etc., the damping force of the shock absorber as a whole with the increase of the load is optimized during the compression stroke. It is set to increase and change.

As shown in FIG. 6, the seal cap 19B is provided with a passage 120 communicating with the lower chamber 54 at one end, and the end cap 18 is provided with the passage 1 at one end.
A passage 124 communicating with 20 and blocked at the other end by a stopper member 122, and a passage 126 communicating with the passage 124 at one end and communicating with the high pressure chamber 32 at the other end are provided. The communication between the passages 124 and 126 is controlled by the opening / closing valve 128. The on-off valve 128 has a passage 124 at one end.
, 126 and a valve hole 134 which is closed at the other end by the plug member 130 and extends along the axis 132, and a needle valve 136 which is arranged in the valve hole so as to be reciprocable along the axis 132. Have

The needle valve 136 cooperates with the valve seat 138 at one end to control the communication between the passage 124 and the passage 126, and integrally has a piston 136A at the other end. Piston 1
36A cooperates with the plug member 130 and the valve hole 134 to form the valve chamber 1
The valve chamber 140 is connected to the passage 126 by a communication hole 142 formed in the needle valve 136 along the axis 132. A compression coil spring accommodating chamber 144 is formed between the piston 136A and the shoulder portion of the valve hole 134, and the compression coil spring 146 is accommodated in the chamber, whereby one end of the needle valve 136 has a valve seat 138. Is urged to the valve opening position where it abuts against. The compression coil spring accommodating chamber 144 is open to the atmosphere through a vent 148.

The third embodiment is otherwise constructed in the same manner as the first embodiment, so that in this embodiment, the pump (104) is the same as in the first embodiment. Even though the intake stroke and the discharge stroke of the vehicle are performed and the vehicle load changes and the vehicle height also changes, the pumping action of the pump (104) and the positioning action of the communication hole (62) performed by the expansion and contraction of the shock absorber. As a result, the vehicle height is automatically returned to the standard vehicle height determined by the position of the communication hole.

In the compression stroke of the shock absorber, the oil in the upper chamber (52) moves to the lower chamber 54 via the damping force generation valve (42) and is compressed by the damping force generation valve (42). Although the damping force is generated, during the expansion stroke of the shock absorber, the opening / closing valve 128 is maintained in the open state when the pressure in the high pressure chamber 32 is less than the predetermined value, and the lower chamber 54
The oil inside passes through the damping force generation valve (40) and goes to the upper chamber (52).
In addition to moving to the high pressure chamber 32 through the passage 124, the opening / closing valve 128, and the passage 126, the damping force generating valve (40) generates an appropriate damping force in the extension stroke.

On the other hand, for example, the pressure in the high pressure chamber 32 becomes a predetermined value or more due to an increase in the load, and the on-off valve 128 is closed to cut off the communication between the lower chamber 54 and the high pressure chamber 32. Then, the oil in the lower chamber 54 moves to the upper chamber (52) through only the damping force generating valve (40), so that the damping is reduced as compared with the case where the opening / closing valve 128 is maintained in the open state. The damping force generated by the force generation valve (40) is increased, which avoids a shortage of the damping force in the extension stroke, thereby improving the steering stability of the vehicle.

Further, in this case, the opening amount of the opening / closing valve 128 becomes smaller as the pressure in the high pressure chamber 32 becomes higher.
The degree of increase in the damping force in the extension stroke with respect to the case where the valve 8 is maintained in the open state increases as the pressure in the high-pressure chamber 32 increases, that is, as the load increases, so that the shock absorber as a whole increases with the load increasing. The rate of increase of the damping force during the extension stroke is larger than that when the on-off valve 128 is maintained in the open state.

Although the present invention has been described above in detail with reference to specific embodiments, the present invention is not limited to these embodiments, and various other embodiments within the scope of the present invention. It will be apparent to those skilled in the art that

For example, the structure of the above-mentioned first or second embodiment so that the damping force of the shock absorber as a whole during the compression stroke and the damping force during the extension stroke of the shock absorber change more preferably with an increase in the vehicle load. And the structure of the third embodiment may be combined.

[0049]

As is apparent from the above description, according to the above-mentioned constitution of claim 1, when the load of the vehicle becomes high and the pressure in the pump chamber becomes a predetermined value or more, the first and second communication control valves are used. The second working fluid chamber is connected in communication, and a part of the working fluid flowing from one working fluid chamber to the other working fluid chamber during the compression stroke of the shock absorber passes through the communication control valve, and thus flows through the damping force generating valve. Since the flow rate of the working fluid is reduced, the damping force generated by the damping force generation valve is reduced to reduce the damping force during the compression stroke of the shock absorber as a whole, which ensures good steering stability of the vehicle. In addition, it is possible to reliably prevent deterioration of riding comfort of the vehicle when the vehicle has a high load.

According to the second aspect of the invention, when the pressure in the pump chamber exceeds a predetermined value due to an increase in the vehicle load, the urging force of the spring means against the valve element of the damping force generating valve is reduced. The damping force generated by the damping force generation valve is reduced to reduce the damping force during the compression stroke of the shock absorber as a whole, which ensures good steering stability of the vehicle and a high load capacity of the vehicle. It is possible to reliably prevent the deterioration of the riding comfort of the vehicle.

Further, according to the third aspect of the invention, when the pressure in the high pressure chamber exceeds a predetermined value due to an increase in the vehicle load, the on-off valve closes, and the volume of the shock absorber decreases during the extension stroke. The communication between the working fluid chamber and the high pressure chamber is cut off, and the working fluid in the working fluid chamber, whose volume decreases during the extension stroke of the shock absorber, passes through the damping force generation valve. As the damping force is increased and the shortage of the damping force during the extension stroke is avoided, it is possible to ensure good riding comfort of the vehicle while ensuring the deterioration of the steering stability of the vehicle when the vehicle has a high loading load. Can be prevented.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a self-pumping type shock absorber according to the present invention.

FIG. 2 is an enlarged partial vertical sectional view showing the intake valve of the first embodiment and its vicinity.

FIG. 3 is an enlarged partial vertical sectional view showing the discharge valve of the first embodiment and the vicinity thereof.

FIG. 4 is an enlarged partial vertical cross-sectional view showing the communication control valve of the first embodiment and its vicinity when the pressure inside the pump chamber is low (right half) and high (left half).

FIG. 5 is an enlarged partial vertical cross-sectional view showing a piston body and its vicinity of a second embodiment of a self-pumping shock absorber according to the present invention when the pressure inside the pump chamber is low (right half) and high (left half). Is.

FIG. 6 is an enlarged partial vertical sectional view showing an opening / closing valve of a third embodiment of a self-pumping type shock absorber according to the present invention and the vicinity thereof.

[Explanation of symbols]

 10 ... Cylinder 22 ... Low pressure chamber 32 ... High pressure chamber 34 ... Piston 40, 42 ... Damping force generating valve 46 ... Pump cylinder member 48 ... Pump rod 52 ... Upper chamber 54 ... Lower chamber 55 ... High pressure passage 56 ... Low pressure passage 62 ... Communication Hole 64 ... Suction valve 78 ... Discharge valve 104 ... Pump 106 ... Communication control valve 110 ... Spring seat member 124, 126 ... Passage 128 ... Open / close valve

Claims (3)

[Claims] 1. A piston and a cylinder that are fitted to each other so as to be relatively reciprocable and cooperate with each other to define a first and a second working fluid chamber, and a damping force provided to the piston or the cylinder. Supplying working fluid from the low pressure chamber to the high pressure chamber by relative movement of the generation valve, the low pressure chamber, the high pressure chamber communicating with the first and second working fluid chambers, and the piston and the cylinder in the contraction direction. And a pump to
The pump has a pump cylinder member slidably arranged in the rod portion of the piston, and is reciprocably fitted to the pump cylinder member and fixed to the cylinder at one end thereof to cooperate with the pump cylinder member. In a self-pumping shock absorber having a pump rod defining a pump chamber, the pump cylinder member moves in a direction in which the pump rod enters the pump cylinder member when the pressure in the pump chamber is a predetermined value or more. Thus, a self-pumping shock absorber is provided, which is supported in the rod portion and is provided with a communication control valve that connects and connects the first and second working fluid chambers when the pump cylinder member moves. 2. A piston and a cylinder which are relatively reciprocally fitted to each other and cooperate with each other to define the first and second working fluid chambers, and an extension stroke and a contraction provided on the piston. A damping force generation valve for stroke, a low pressure chamber, a high pressure chamber that communicates with the first and second working fluid chambers, and the high pressure chamber from the low pressure chamber due to relative movement of the piston and the cylinder in the contraction direction. A pump for supplying a working fluid to the pump, the pump being slidably arranged in the rod portion of the piston, and the pump cylinder member fixed at one end to the pump cylinder member so that the pump cylinder member can reciprocate. In a self-pumping shock absorber having a pump rod that is fitted and cooperates with the pump cylinder member to define a pump chamber, the damping force generating valve for the extension stroke includes a valve element and the valve element. Spring means for urging the element to the valve closing position, the spring means being supported by the pump cylinder member, the pump cylinder member being against the pump cylinder member when the pressure in the pump chamber is above a predetermined value. It is supported in the rod portion by an elastic member so as to move in the approaching direction of the pump rod, and when the pump cylinder member moves, the biasing force of the spring means on the valve element is reduced. A self-pumping shock absorber featuring. 3. A piston and a cylinder which are fitted to each other so as to be relatively reciprocable and cooperate with each other to define the first and second working fluid chambers, and a damping force provided to the piston or the cylinder. The working fluid is supplied from the low pressure chamber to the high pressure chamber by relative movement of the generation valve, the low pressure chamber, the high pressure chamber communicating with the first and second working fluid chambers, and the piston and the cylinder in the contraction direction. In a self-pumping shock absorber having a pump, a communication passage that connects the working fluid chamber whose volume decreases during the expansion stroke of the shock absorber and the high pressure chamber, and the high pressure provided in the middle of the communication passage. An on-off valve that opens and closes in response to the pressure in the room, and the on-off valve is configured to close when the pressure in the high-pressure room is equal to or higher than a predetermined value. Npingu shock absorber.