JPH08177931A - Hydraulic shock absorber - Google Patents

Abstract

PURPOSE: To positively prevent a leaf valve from deforming even if the circumstance may allow high back pressure to act on the leaf valve. CONSTITUTION: The upper and lower end surfaces of a piston 36 is respectively arranged with valve mechanisms 46 composed of a leaf valve 56 and a check valve 58. The check valve 58 opens a communication hole 62 resisting to the energy force of a compression coil spring when back pressure of more than the specified value acts upon the leaf valve 56. Thus high back pressure acting upon the leaf valve 58 can be nipped in the bud. As a result, the leaf valve 56 is never deformed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber which is used for a suspension of an automobile or the like and which includes a cylinder, a partition member, a communication passage, and a valve mechanism.

[0002]

2. Description of the Related Art Conventionally, hydraulic shock absorbers have been used in various devices, but as one example, they are used as shock absorbers, which are constituent elements of automobile suspensions. Below is the actual fair 2-
A conventional technique will be described by taking the shock absorber disclosed in Japanese Patent No. 5135 as an example.

FIG. 11 shows an essential part of a conventional structure for the invention disclosed in this publication. As shown in this figure, a small diameter portion 102A is formed at the tip of a piston rod 102 that axially moves in the inner cylinder 100, and the small diameter portion 102A has a washer 104 and a retainer 1.
06, double-layered leaf valve 108, piston 11
0, four-layer leaf valve 112, retainer 114,
Members such as washers 116 are inserted and arranged in this order and fixed by nuts 118.

Further, annular grooves 120 and 122 are formed on the upper end surface and the lower end surface of the piston 110 in the vicinity of their respective peripheral edges. Further, the piston 110 is provided with an orifice 126 that communicates the annular groove 120 on the upper end surface side of the piston and the lower piston chamber 124, and an orifice 130 that communicates the annular groove 122 on the lower end surface side of the piston and the upper chamber 128 of the piston. It is provided.

According to the above construction, the piston 110 slides in the direction of arrow A during the expansion process, and the leaf valve 112 having a four-layer structure is bent toward the washer 116 accordingly. As a result, the oil in the piston upper chamber 128 flows into the piston lower chamber 124 through the orifice 130 and the annular groove 122, and a damping force is generated during the stretching process. On the other hand, during the contracting step, the piston 110 slides in the direction of the arrow B, and the leaf valve 108 having the two-layer structure bends toward the washer 104 accordingly. As a result, the piston lower chamber 12
The oil in No. 4 flows into the piston upper chamber 128 through the orifice 126 and the annular groove 120, and a damping force is generated during the compression process.

However, in the case of the above configuration, the leaf valve 108 has two layers and is less rigid than the leaf valve 112 in order to set the damping force during the expansion step to be higher than the damping force during the contraction step. Therefore, as shown in FIG. 12, when the back pressure is applied to the leaf valve 108 during the expansion process, a part of the leaf valve 108 is partially covered with the annular groove 1.
It may be deformed inward of 20.

Therefore, in the structure disclosed in the above publication,
As shown in FIG. 13, the leaf valve 108 having a two-layer structure.
Reinforcement plate 140 having a relatively high strength between the washer 104 and the washer 104.
Is arranged. The reinforcing plate 140 has a ring shape, and a guide ring 142 corresponding to the retainer 106 is arranged on the shaft core portion. Further, a leaf spring 144 having a predetermined shape is arranged between the reinforcing plate 140 and the washer 104, which normally causes the leaf valve 108 to close the annular groove 120 via the reinforcing plate 140. The reinforcing plate 140 is loosely fitted to the guide ring 142, and slides along the guide ring 142 when the leaf valve 108 bends toward the washer 104 against the biasing force of the plate spring 144. Is ready to go.

According to this structure, although the back pressure is applied to the reinforcing plate 140 during the stretching process, the reinforcing plate 140 is a high-rigidity member, so that a part of the leaf valve 108 is in the annular groove 120.
It is possible to prevent inward deformation.

However, even if the reinforcing plate 140 is provided as described above, the strength may be insufficient. That is, when running on a rough road, a very high back pressure may be applied to the reinforcing plate 140 because a stretching process occurs instantaneously. In such cases,
The reinforcing plate 140 itself may be deformed, and the effect of preventing the leaf valve 108 from being deformed cannot be obtained. In order to eliminate this, the reinforcing plate 140 may be thickened, but if the reinforcing plate 140 is simply thickened, the damping force characteristic changes, which is not preferable.

In view of the above facts, the present invention provides a hydraulic shock absorber capable of reliably preventing the leaf valve from being deformed even under a situation where a high back pressure may act on the leaf valve. Is the purpose.

[0011]

According to the present invention, there is provided a cylindrical body having a fluid filled therein, a partition member for partitioning a chamber in the cylindrical body, and each chamber partitioned by the partition member. A communication passage communicating with each other, and provided at the open end of this communication passage,
A hydraulic shock absorber having a valve mechanism for opening and closing the communication passage, wherein the valve mechanism is elastically deformable at the open end of the communication passage, and in the non-deformed state, the communication passage is closed and elastically deformed. The leaf valve that opens the communication passage and the communication hole formed at a position corresponding to the communication passage in the leaf valve are provided so as to be openable and closable, and a back pressure in the closing direction and a predetermined value or more acts on the leaf valve. And a check valve that opens the communication path in some cases.

[0012]

In the following, as an example, the case where the separating member is arranged inside the inner cylinder of the double cylinder type cylinder and the valve mechanism is provided at both ends on the open side of the communication passage will be described. The operation of the invention will be described.

In this case, since the leaf valve is in the non-deformed state in the initial state, the communication passage is closed. Further, in this state, the check valve also closes the communication hole, because the back valve does not act on the leaf valve in the closing direction and the back pressure exceeds a predetermined value.

From this state, in the expansion step, a back pressure in the closing direction acts on the leaf valve on the upper end surface side of the partition member. Therefore, the leaf valve maintains the closed state. At this time, if the back pressure acting on the leaf valve is less than the predetermined value, the check valve also maintains the closed state, but if the back pressure acting on the leaf valve exceeds the predetermined value, the check valve opens. As a result, the communication hole provided in the leaf valve is opened, so that the fluid flows through the communication hole to the communication passage.

In this case, since pressure in the opening direction acts on the leaf valve on the lower end surface side of the partition member, the leaf valve is elastically deformed to open the communication passage. At this time, since the pressure acting on the leaf valve is in the opening direction, the check valve maintains the closed state. For this reason,
The fluid that has flowed through the communication passage through the communication hole of the leaf valve on the upper end surface side of the partition member is transferred to the leaf valve (in the elastically deformed state) on the lower end surface side of the partition member and the lower end surface of the partition member. It flows into the lower chamber of the inner cylinder through the gap.

During the contracting step, the operation is the reverse of the operation described above. As described above, according to the present invention, since the communication valve provided in the leaf valve is provided with the check valve which is opened when the back pressure in the closing direction and when the back pressure is equal to or more than the predetermined value acts on the leaf valve, a high back pressure acts on the leaf valve. There is nothing to do. That is, it is possible to prevent the high back pressure from acting on the leaf valve. Therefore, a part of the leaf valve does not deform toward the communication passage.

[0017]

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

FIG. 3 shows the overall structure of the shock absorber 10. As shown in this figure, the shock absorber 10 is a so-called multi-cylinder type shock absorber including a cylinder 12 that functions as an inner cylinder and an outer shell 14 that functions as an outer cylinder.

A dish-shaped lower cap 16 is fitted to the lower end of the outer shell 14, and is welded in this state. As a result, the lower end of the outer shell 14 is closed.

On the other hand, a base case 18 having a dish shape and a flange formed on the peripheral edge is fitted to the lower end of the cylinder 12. A piston rod 20 is arranged inside the cylinder 12 in a state of partially protruding upward. A rebound stopper plate 22 having a hat-shaped cross section is welded to an axially intermediate portion of the piston rod 20, and a rebound stopper 24, which is an elastic body, is arranged at the upper end portion thereof. A rod guide 26 having a predetermined shape is arranged at the upper end of the cylinder 12.
The rod guide 26 includes a disc-shaped base portion 26A and the base portion 26A.
The inner boss 26B is fitted into the upper end of the cylinder 12. When the boss 26B is fitted to the upper end portion of the cylinder 12, the outer peripheral surface of the base portion 26A is the outer shell 1
It is in close contact with the inner peripheral surface of No. 4. A cylindrical bush 28 is press-fitted on the inner peripheral surface of the shaft center of the boss 26B so as to be relatively movable and closely attached to the outer peripheral surface of the piston rod 20. Further, an annular groove is formed on the outer peripheral edge of the base portion 26A, and the rectangular seal ring 30 is fitted in the groove. In the state where the rectangular seal ring 30 is fitted, the inner end surface and the lower end surface of the rectangular seal ring 30 contact the rod guide 26, the outer end surface contacts the inner peripheral surface of the outer shell 14, and the upper end surface of the ring nut 32. By contacting the lower end surface, the sealability between the three is secured.

A female screw is formed on the inner peripheral surface of the upper end portion of the outer shell 14, and a ring nut 32 is screwed into the female screw. An oil seal 34 is provided at the axial center of the ring nut 32 to seal between the ring nut 32 and the piston rod 20. By screwing the ring nut 32 into the upper end of the cylinder 12, the rod guide 26, the rectangular seal ring 30, the cylinder 12, and the base case 18 are fixed in the outer shell 14. At this time, a part of the flange of the base case 18 comes into contact with the inclined surface of the lower cap 16 so that the outer shell 14
The cylinder 12 is aligned with respect to the axis of.

In the above-mentioned structure, since the piston 36, which will be described later, is reciprocally disposed inside the cylinder 12, the chamber inside the cylinder 12 is divided into the upper chamber 38 and the lower chamber 40. Also, the inside is filled with oil. Further, in the reservoir chamber 42 formed between the cylinder 12 and the outer shell 14, oil and gas such as nitrogen gas are sealed in a separated state.

Next, the details of the piston portion provided at the tip of the piston rod 20 will be described.

As shown enlarged in FIG. 1, a small diameter portion 20A is provided at the tip of the piston rod 20. A stopper 44, a valve mechanism 46, a piston 36, a valve mechanism 46 having the same configuration, and a stopper 44 are attached to the small diameter portion 20A in this order. After mounting these components, the nut 4 is attached to the tip of the small diameter portion 20A.
8 is tightened so that the above parts are fixed. Hereinafter, each component will be specifically described. Since the stopper 44 and the valve mechanism 46 have the same upper and lower configurations, the stopper 44 and the valve mechanism 46 on the upper side of the stopper 44 and the valve mechanism 46 are identical.
Will be described only.

The piston 36 has a through hole in its shaft center, and the small diameter portion 20A of the piston rod 20 penetrates through this through hole. In addition, a plurality of ports 50 are formed on the outer peripheral portion of the piston 36 so as to penetrate in parallel to the axis. Further, annular recessed grooves 52 are formed on the upper end surface and the lower end surface of the piston 36, respectively. These upper and lower recessed grooves 52 communicate with the above-mentioned port 50. A piston band 54 is fitted on the outer peripheral surface of the piston 36 to ensure sealing performance with the inner peripheral surface of the cylinder 12.

The valve mechanism 46 is composed of a thin disk-shaped leaf valve 56 and a plurality of check valves 58 provided near the periphery of the leaf valve 56. The leaf valve 56 is arranged in contact with the upper end surface of the piston 36. Therefore, normally, the groove 52
As a result, the port 50 is closed, but a predetermined pressure acts from the concave groove 52 side to elastically deform and open them.

As shown in an enlarged view in FIG. 4, a plurality of check valves 58 are provided in the vicinity of the peripheral edge of the leaf valve 56 at equal intervals in the circumferential direction. Leaf valve 56
In the vicinity of the peripheral edge of the center hole 60, a plurality of communication holes 62 arranged around the center hole 60 are formed at equal intervals in the circumferential direction (see FIG. 6). In the central hole 60, a head having a spherical end surface, a shaft portion protruding from the shaft core portion of the head portion and having a smaller diameter than the head portion, and a diameter smaller than the shaft portion provided at the tip end portion of the shaft portion The shaft portion of the pin (stepped pin) 64 formed of the small diameter portion is penetrated. In addition, a thin disk-shaped valve body 66 having a diameter dimension capable of closing all the communication holes 62 is inserted into the small diameter portion of the pin 64, and after the insertion, the tip of the small diameter portion is caulked, whereby the valve body 66 is inserted. Is fixed to the pin 64. A compression coil spring 68 is wound around the shaft portion of the pin 64, that is, between the head portion and the peripheral surface of the center hole 60 of the leaf valve 56. Therefore, the compression coil spring 68 constantly presses and urges the valve element 66 in the direction in which the communication hole 62 is closed. The check valve 58 described above is provided with a compression coil spring 68 when the leaf valve 56 is applied with a back pressure in the closing direction and a predetermined value or more.
Is separated from the leaf valve 56 against the urging force of the communication hole 6
It is designed to open 2.

As shown in FIG. 5, the stopper 44 has a disk shape having a predetermined thickness, has a hole 70 for penetrating the piston rod 20 in the shaft core portion, and has a periphery thereof. Have discontinuous long holes 72 and 74 formed concentrically. In the state where the stopper 44 is inserted and arranged in the small diameter portion 20A of the piston rod 20, the elongated hole 7 on the outer peripheral side is provided.
The partition wall 44A between 2 and the inner circumferential long hole 74 is located directly above the head of the pin 64 described above.

Next, the details of the base portion provided at the lower end of the cylinder 12 will be described. As shown in an enlarged manner in FIG. 2, a base case 18 having a flange formed on the peripheral edge and a bulged central portion is fitted to the lower end of the cylinder 12. As described above, one flange of the base case 18 abuts the inclined surface of the lower cap 16 to align the cylinder 12, but the other flange is separated from the inclined surface of the lower cap 16. As a result, a flow path 76 that connects the cylinder 12 side and the inside of the outer shell 14 is formed. A boss 18A is formed on the shaft center of the base case 18, and a stopper 44 and a valve mechanism 46 used in the piston portion are arranged in the same arrangement on the upper end surface and the lower end surface of the boss 18A, respectively. ing. Since the configurations of the stopper 44 and the valve mechanism 46 are as described above,
The description is omitted. Base case 18 as described above
With the stopper 44 and the valve mechanism 46 arranged in the base case 1, the base case 1
These parts are fixed to 8 to form a base valve.

The operation of this embodiment will be described below. In the initial state, the valve mechanism 46 of the piston portion and the valve mechanism 46 of the base portion are in the states shown in FIGS. 1 and 2. In this state, there is no pressure difference between the front and back surfaces of each leaf valve 56, so each leaf valve 56 is in a non-deformed state. Therefore, the piston 36 and each annular groove 52 and the port 50 of the base case 18 are closed. Further, in this state, since no back pressure is applied to the leaf valve 56 in the closing direction and above a predetermined value, the valve body 66 of the check valve 58 receives the biasing force of the compression coil spring 68 and closes the communication hole 62. ing.

From this state, when the piston rod 20 is moved downward to perform the contracting process, the lower chamber 4 of the cylinder 12 is
The pressure of 0 is higher than the pressure of the upper chamber 38. Therefore, the leaf valve 56 on the lower end surface side of the piston 36 maintains the closed state, but when the back pressure acting on the leaf valve 56 exceeds a predetermined value, the valve body 6 of the check valve 58 is closed.
6 opens the communication hole 62 against the biasing force of the compression coil spring 68. Therefore, as shown by the arrow in FIG.
After passing through the communication hole 62, the oil in the lower chamber 40 flows in the port 50 through the concave groove 52 on the lower end surface side of the piston 36.

In this case, since pressure is applied to the leaf valve 56 on the upper end surface side of the piston 36 in the opening direction, the leaf valve 56 on the upper end surface side of the piston 36 is elastically deformed and the outer periphery of the upper end surface of the piston 36. Protrusion 36A (see FIG. 8)
A predetermined gap 82 is formed between the outer peripheral protrusion 36A and the outer peripheral protrusion 36A. The state shown in FIG. 8 is during the contraction process and the moving speed of the piston 36 is in the low speed range.
In this case, the elastic deformation of the leaf valve 56 is stopped by the head portion of the pin 64 of the check valve 58 not contacting the partition wall portion 44A of the stopper 44 or merely contacting the partition wall portion 44A of the stopper 44.
Therefore, the valve body 66 of the check valve 58 closes the communication hole 62 of the leaf valve 56 by the urging force of the compression coil spring 68. As a result, as shown by the arrow in FIG. 8, the oil flows into the upper chamber 38 of the cylinder 12 through the gap 82 between the leaf valve 56 and the outer peripheral protrusion 36A on the upper end surface of the piston 36.

On the other hand, on the side of the base valve shown in FIG. 2, the pressure in the lower chamber 40 of the cylinder 12 is equal to that of the reservoir chamber 4.
Higher than the pressure of 2. Therefore, the base case 18
Since the leaf valve 56 on the upper end surface side of the device receives back pressure in the closing direction, it maintains the closed state. When this back pressure exceeds a predetermined value, the valve element 66 of the check valve 58 moves in the direction away from the leaf valve 56 against the urging force of the compression coil spring 68 to open the communication hole 62. Therefore, the oil in the lower chamber 40 of the cylinder 12 flows into the port 50 through the communication hole 62 of the leaf valve 56 on the upper end surface side of the base case 18, and then through the annular groove 52 on the upper end surface side. Go. In this case, since pressure is applied to the leaf valve 56 on the lower end surface side of the base case 18 in the opening direction, the leaf valve 56 is elastically deformed and separated from the outer peripheral projection 18B on the lower end surface of the base case 18, and the outer peripheral projection is formed. A predetermined gap is formed with 18B. If the moving speed of the piston 36 is in the low speed range, the head of the pin 64 of the check valve 58 on the lower end surface side of the base case 18 does not contact the partition wall 44A of the stopper 44, or does not contact the partition wall 44A of the stopper 44. Only then, the elastic deformation of the leaf valve 56 is stopped. Therefore, the valve body 66 of the check valve 58 is urged by the compression coil spring 68 to force the communication hole 6 of the leaf valve 56.
2 is closed. As a result, the oil is in the base case 1
8 port 50 to leaf valve 56 and base case 1
The fluid flows into the reservoir chamber 42 through the gap between the outer peripheral protrusion 18B on the lower end surface of the nozzle 8.

In the above operation, the piston 36
The main flow resistance when the leaf valve 56 on the upper end surface side of the base elastically deforms and the oil passes through the gap 82, and when the leaf valve 56 on the lower end surface side of the base case 18 elastically deforms and the oil passes through the gap. Occurs and a damping force is obtained during the compression process.

By the way, when the piston 36 is in the contracting process and the moving speed of the piston 36 is in the middle / high speed range, such as when traveling on a rough road, the state shown in FIG. 8 shifts to the state shown in FIG. . That is, in this case, the piston 3
6, the tip of the leaf valve 56 on the upper end surface side of 6 is the stopper 4
The leaf valve 56 is elastically deformed until it comes into contact with the lower end surface of the outer peripheral portion of No. 4. In this case, the pin 64 of the check valve 58
Since the head portion of the leaf valve is already in contact with the partition wall portion 44A of the stopper 44, the leaf valve 56 is elastically deformed, so that the valve element 66 is relatively forcibly separated from the leaf valve 56 and is opened. . Therefore, the piston 36
The oil flowing through the port 50 of the leaf valve 56
And the outer peripheral projection 36A of the piston 36, and also the communication hole 62 of the leaf valve 56. That is,
The oil flow path increases to two systems. As a result, the damping force in the middle / high speed range during the shrinking process is reduced.

On the other hand, in the elongation step, the operation reverse to the above-mentioned operation is performed. Briefly, when the moving speed of the piston 36 during the extension process is in the low speed range, the pressure of the upper chamber 38 of the cylinder 12 becomes higher than the pressure of the lower chamber 40, so the leaf valve on the upper end surface side of the piston 36. 56 maintains a closed state, and the check valve 58 becomes an open state. In addition, the check valve 5 on the lower end surface side of the piston 36
8 remains closed, but the leaf valve 56 is open. As a result, the oil in the upper chamber 38 becomes
6, from the check valve 58 on the upper end face side of the piston 6 through the communication hole 62 and the port 50, the outer peripheral projection 3 on the lower end face side of the piston 36.
The lower chamber 40 is passed through the gap 82 between the 6A and the leaf valve 56.
It flows inward.

On the base valve side, the cylinder 12
Since the pressure of the lower chamber 40 becomes lower than the pressure of the reservoir chamber 42, the leaf valve 56 on the lower end surface side of the base case 18 maintains the closed state, and the check valve 58 becomes the open state. Further, the check valve 58 on the upper end surface side of the base case 18 remains closed, but the leaf valve 56 is opened. As a result, the oil in the reservoir chamber 42 passes from the check valve 58 on the lower end surface side of the base case 18 through the communication hole 62 and the port 50 to the gap 84 between the outer peripheral protrusion 18B and the leaf valve 56 on the upper end surface side of the base case 18. It flows through it into the lower chamber 40.

As a result, a damping force is obtained during the stretching process. The description of the operation when the piston speed is medium or high is omitted because the operation is the same as in the case of the contracting step.

From the above, the damping force characteristics when the shock absorber 10 according to the present embodiment is used are shown in FIG.
As shown in. That is, with respect to the extension side damping force, when the piston speed is in the low speed range, the damping force does not decrease as in the conventional case, and in the middle / high speed range, the slope of the damping force becomes gentle and is reduced. On the other hand, the same applies to the damping force characteristics during the shrinking process. It should be noted that the damping force during the contracting process is set to be lower than the damping force during the expanding process as a whole, but this tuning is performed by adjusting the diameter of the port 50, the spring constant of the compression coil spring 68, and the leaf valve. It is made by the rigidity of 56 and the like.

As described above, in this embodiment, the valve mechanism 46 provided in the piston portion and the base portion is provided in the leaf valve 5.
6 and the check valve 58, the check valve 58 opens the communication hole 62 formed in the leaf valve 56 when a back pressure in the closing direction and a predetermined value or more acts on the leaf valve 56. Because I did
It is possible to prevent high back pressure from acting on the leaf valve 56. Therefore, it is possible to prevent a part of the leaf valve 56 from being deformed toward the concave groove 52 side of the piston 36 or the base case 18 and being damaged. In addition,
As a result, the conventionally used reinforcing plate is also unnecessary.

Further, in this embodiment, when the piston speed changes rapidly from the low speed range to the medium / high speed range, such as when running on a rough road, the check valve 58 is opened again. The damping force in such a case can be reduced. That is, it is possible to reduce only the damping force in the middle / high speed range without reducing the damping force in the low speed range of the piston speed. As a result, both steering stability and good riding comfort can be achieved.

In this embodiment, the valve mechanism 46 to which the present invention is applied is set in both the piston portion and the base portion, but the present invention is not limited to this, and the valve in which the present invention is applied to only one of them. The mechanism 46 may be set. Further, the valve mechanism 46 to which the present invention is applied is set on both the upper end surface side and the lower end surface side of the piston portion, but the valve mechanism 46 to which the present invention is applied may be set to only one of them. . In addition, this point is similarly applied to the base portion.

Further, although the present invention is applied to the shock absorber 10 of the double cylinder type in the present embodiment, the present invention is not limited to this, and the present invention can be applied to the shock absorber of the single cylinder type. is there.

Further, in the present embodiment, the present invention is applied to the shock absorber 10 which constitutes a part of the suspension of the automobile, but the application of the hydraulic shock absorber according to the present invention is not limited to this, and various types are applicable. It is applicable to devices.

According to the valve mechanism of the present invention as defined in claim 1, "the communication passage is provided at the open end of the communication passage so as to be elastically deformable, and in the non-deformed state, the communication passage is closed and elastically deformed. The leaf valve that opens the valve and the communication hole formed at a position corresponding to the communication path in the leaf valve are openable and closable, and when the leaf valve is closed and a back pressure of a predetermined value or more acts on the leaf valve, And a check valve that opens the communication hole when elastically deformed by a predetermined amount or more. ", The following actions and effects are obtained.

That is, the piston speed is from low speed to medium
When the leaf valve is elastically deformed by a predetermined amount or more in the high speed range, the check valve is opened again. As a result, the communication hole provided in the leaf valve is opened again,
The fluid flows into the communication passage through the communication hole. Therefore, when applied to a shock absorber of an automobile, for example, the damping force in the medium / high speed range can be reduced. As a result, steering stability and riding comfort can be improved.

Further, in the valve mechanism according to the present invention as set forth in claim 1, "the communication passage is provided at the open end of the communication passage so as to be elastically deformable, and in the non-deformed state, the communication passage is closed and elastically deformed. And a limiting means (stopper 4) for limiting the amount of elastic deformation of the leaf valve.
4 corresponds to this), and a communication hole formed at a position corresponding to the communication passage in the leaf valve is provided so as to be opened and closed.
And a check valve that opens the communication hole when a back pressure in the closing direction and a predetermined value or more acts on the leaf valve and when the elastic deformation amount of the leaf valve is limited by the limiting means. '' Also in the case, the same action and effect can be obtained.

[0048]

As described above, in the hydraulic shock absorber according to the present invention, the leaf valve forming a part of the valve mechanism is formed with the communication hole, and the leaf valve is provided with a back pressure in the closing direction and at a predetermined value or more. Since the check valve that opens the communication hole only when the leaf valve is actuated is provided, it is possible to reliably prevent the leaf valve from being deformed even in a situation where a high back pressure may act on the leaf valve. Has excellent effect.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a piston portion of a shock absorber according to this embodiment.

FIG. 2 is an enlarged cross-sectional view of a base portion of the shock absorber according to this embodiment.

FIG. 3 is an overall configuration diagram of a shock absorber according to the present embodiment.

FIG. 4 is an enlarged cross-sectional view of the check valve shown in FIGS. 1 and 2.

5 is an enlarged plan view of the stopper shown in FIGS. 1 and 2. FIG.

FIG. 6 is an enlarged plan view of the leaf valve shown in FIGS. 1 and 2.

FIG. 7 is an explanatory diagram for explaining the state of the valve mechanism on the lower end surface side of the piston in the low speed region during the contracting step.

FIG. 8 is an explanatory diagram for explaining the state of the valve mechanism on the upper end face side of the piston in the low speed region during the contracting step.

FIG. 9 is an explanatory diagram for explaining the state of the valve mechanism on the upper end face side of the piston in the medium / high speed range during the contracting step.

FIG. 10 is a damping force characteristic diagram showing the relationship between piston speed and damping force.

FIG. 11 is a vertical sectional view showing a main part of a hydraulic shock absorber according to a conventional example.

FIG. 12 is an explanatory diagram for explaining a problem when the structure shown in FIG. 11 is used.

FIG. 13 is a vertical cross-sectional view showing a main part of a hydraulic shock absorber according to another conventional example.

[Explanation of symbols]

 10 Shock absorber (hydraulic shock absorber) 12 Cylinder (cylindrical body) 14 Outer shell (cylindrical body) 18 Base case (separating member) 36 Piston (separating member) 38 Upper chamber 40 Lower chamber 46 Valve mechanism 50 port (communication passage) 52 recessed groove (communication passage) 56 leaf valve 58 check valve 62 communication hole

Claims (1)

[Claims] 1. A tubular body having a fluid filled therein, a partitioning member for partitioning a chamber in the tubular body, and a communication passage for communicating the chambers partitioned by the partitioning member with each other. A hydraulic shock absorber having a valve mechanism provided at an open end of the communication passage for opening and closing the communication passage, wherein the valve mechanism is elastically deformable provided at an open end of the communication passage. In the non-deformed state, a leaf valve that closes the communication passage and elastically deforms to open the communication passage, and a communication hole formed at a position corresponding to the communication passage in the leaf valve are openable and closable. A hydraulic shock absorber, comprising: a check valve that opens the communication passage when a back pressure of a predetermined value or more acts in the closing direction.