JP7402087B2 - buffer - Google Patents

Description

The present invention relates to a shock absorber.

A shock absorber is used, for example, by being interposed between the vehicle body and wheels of a straddle-type vehicle, and suppresses vibrations of the vehicle body and wheels using damping force generated during expansion and contraction.

The shock absorber generates damping force using a valve installed inside the shock absorber, but in addition to this, the shock absorber generates damping force using a valve installed inside the shock absorber. In some cases, a hydraulic lock mechanism is provided to suppress further extension when the extension reaches near the end.

The hydraulic lock mechanism includes, for example, an annular rebound cushion attached to a rod guide attached to the end of the cylinder, and an annular rebound cushion attached to the rod guide via a coil spring that movably slides into contact with the outer circumference of the piston rod. The rod includes a shutter that opens and closes a damping force adjustment passage that communicates the expansion side chamber and the compression side chamber provided in the rod.

Specifically, when the piston rod is displaced relative to the cylinder to the vicinity of the stroke end on the extension side, the shutter contacts an annular stopper attached to the outer circumference of the piston rod, and the shutter opens from the side of the piston rod. Block the force adjustment passage. Since the damping force adjustment passage is closed by the shutter, the pressure increase in the expansion side chamber is promoted and movement of the piston rod toward the expansion side is suppressed. When the shock absorber further extends from this state, the shutter moves together with the stopper while keeping the damping force adjustment passage closed, and the rebound cushion comes into contact with the stopper. In this state, the damping force adjustment passage is closed by the shutter, and the space on the inner peripheral side of the rebound cushion is isolated from the expansion side chamber and the compression side chamber due to the contact between the rebound cushion and the rebound stopper. In such a situation, the hydraulic lock mechanism has a hydraulic lock function that increases the pressure in the space as the piston rod strokes toward the extension side and prevents the piston rod from moving further toward the extension side. This prevents the rebound stopper and the rod guide from colliding forcefully (for example, see Patent Document 1).

JP2019-215040A

In this way, with conventional shock absorbers, the coil spring allows the shutter to be placed in a position separated from the rod guide, and the damping force adjustment passage can be closed at an early timing, so the speed of the piston rod can be sufficiently reduced to achieve the maximum It can reduce the impact during extension.

However, in conventional shock absorbers, when the shutter closes the damping force adjustment passage and the piston rod moves in the opposite direction and contracts, it takes the piston rod to open the damping force adjustment passage before the shutter closes the damping force adjustment passage. The amount of movement toward the contraction side increases. In other words, by shifting the shutter toward the piston using the coil spring, the distance from when the shutter closes the damping force adjustment passage when the shock absorber is extended until the piston rod reaches the stroke end can be lengthened, but the opposite is true. When the piston rod moves from the stroke end on the extension side to the contraction side, the amount of movement of the piston rod increases until the shutter opens the damping force adjustment passage.

Then, when the shock absorber is extended, the damping force adjustment passage is closed by the shutter and the hydraulic lock is activated, and when the shock absorber is retracted, the hydraulic pressure is maintained until the shutter opens the damping force adjustment passage. The lock function remains activated. In such a situation, the damping force at the beginning of the shock absorber's contraction becomes high, making it impossible for the shock absorber to contract smoothly.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a shock absorber that can suppress excessive damping force when switching to a contraction stroke after maximum extension, thereby improving ride comfort in a vehicle.

In order to solve the above-mentioned problems, the shock absorber of the present invention includes a cylinder, an annular rod guide provided at the end of the cylinder, and a shock absorber that is movably inserted into the cylinder by passing through the inner circumference of the rod guide. a piston rod that is inserted into the cylinder and divides the inside of the cylinder into a compression side chamber and a compression side chamber facing the rod guide; and a passage that opens from the side of the piston rod and communicates the expansion side chamber and the compression side chamber. an annular shutter that is attached to the outer periphery of the rod guide so as to be movable in the axial direction to open and close the passage; an elastic member that connects the shutter and the rod guide; and a stopper that is attached to the piston rod and faces the shutter in the axial direction. The shutter has a pressure receiving part that receives the pressure of the pressure side chamber so as to be separated from the stopper while contacting the stopper and closing the passage .

In a shock absorber configured in this way, the shutter quickly opens the passage when switching to the contraction stroke after the maximum extension, so while it exerts the hydraulic lock function at the maximum extension, it also prevents the contraction after the maximum extension. Contraction is performed without generating excessive damping force when switching to stroke.

In addition, the shutter in the shock absorber includes a cylindrical shutter part that slides on the outer periphery of the piston rod, a flange part provided on the outer periphery of the stopper side end of the shutter part and facing the stopper, and a flange part that extends from the inner periphery of the shutter part. The pressure receiving part may be a tapered surface formed by the annular recess. According to the buffer constructed in this way, the liquid can pass smoothly between the shutter and the stopper while ensuring the effective pressure-receiving area of the pressure-receiving part of the shutter, and the shutter can open the passage more smoothly. , the damping force at the time of switching from the extension operation to the contraction operation can be further reduced, and the riding comfort in the vehicle can be further improved.

In addition, the shutter in the shock absorber includes a cylindrical shutter part that slides on the outer periphery of the piston rod, a flange part provided on the outer periphery of the stopper side end of the shutter part and facing the stopper, and a flange part that extends from the inner periphery of the shutter part. and an annular recess provided around the inner periphery of the shutter and facing the passage when the shutter is in contact with the stopper, and the pressure receiving part is an annular recess formed in the shutter part and has a first annular surface parallel to the stopper. and a second annular surface which is an annular recess and is formed on the flange portion and is parallel to the stopper. Even if the pressure receiving portion is formed in this way, the pressure in the pressure side chamber can be applied to the shutter so as to apply a force to separate it from the stopper.

As described above, in the case where the pressure receiving part is formed by providing the annular recess only in the shutter, it is only necessary to process the shutter, so that the processing cost of the shock absorber can be reduced.

Further, the shock absorber may include an annular rebound cushion that is attached to the rod guide and forms a gap on the inner circumferential side when it comes into contact with the stopper. According to the shock absorber configured in this way, when the rebound cushion and the stopper come into contact with each other after the passage is closed by the shutter, the gap is isolated from the expansion side chamber and the compression side chamber, and the hydraulic locking function can be exhibited. Collision between the guide and the stopper can be prevented.

As described above, according to the shock absorber of the present invention, while exhibiting the locking function at the maximum extension, the damping force is suppressed from becoming excessive when switching to the contraction stroke after the maximum extension, thereby improving ride comfort in the vehicle. can be improved.

FIG. 3 is a longitudinal cross-sectional view of a shock absorber in one embodiment. FIG. 2 is a partially enlarged vertical cross-sectional view of the buffer in one embodiment. FIG. 2 is a partially enlarged vertical cross-sectional view of the buffer in one embodiment. It is a partially enlarged longitudinal cross-sectional view of the shock absorber in the 1st modification of one embodiment. FIG. 7 is a partially enlarged vertical cross-sectional view of a shock absorber in a second modified example of an embodiment.

The present invention will be described below based on the embodiments shown in the figures. As shown in FIGS. 1 and 2, the shock absorber D in one embodiment includes a cylinder 1, an annular rod guide 2 provided at the end of the cylinder 1, and an annular rod guide 2 inserted through the inner circumference of the rod guide 2. A piston rod 3 is movably inserted into the cylinder 1, a piston 4 is inserted into the cylinder 1 and divides the inside of the cylinder 1 into a compression side chamber R2 and a expansion side chamber R1 facing the rod guide 2, and the piston rod 3. A passage P that opens from the side and communicates the expansion side chamber R1 and the compression side chamber R2, an annular shutter 6 that is attached to the outer periphery of the rod guide 2 so as to be movable in the axial direction and opens and closes the passage P, and the shutter 6. It is configured to include a coil spring S as an elastic member that connects to the rod guide 2, and a rebound stopper 13 as a stopper mounted on the piston rod 3 and facing the shutter 6 in the axial direction. In the case of this shock absorber D, it is used by being interposed between the vehicle body and wheels of a vehicle (not shown), and suppresses vibrations of the vehicle body and wheels.

Each part of the buffer D will be explained in detail below. As shown in FIG. 1, an annular rod guide 2 is attached to the upper end of the cylinder 1 in FIG. A piston rod 3 is inserted through the inner periphery of the rod guide 2, and the rod guide 2 guides the relative movement of the piston rod 3 in the axial direction with respect to the cylinder 1 in the vertical direction in FIG.

The rod guide 2 includes an annular main body part 2a that fits into the cylinder 1, a cylindrical convex part 2b rising upward in FIG. It includes a cylindrical cushion holding portion 2c that rises downward. Further, a cylindrical bush 7 is attached from the inner circumference of the main body portion 2a of the rod guide 2 to the inner circumference of the convex portion 2b and slides on the outer circumference of the piston rod 3. Further, an annular groove 2d in which a seal ring 8 for sealing between the cylinder 1 and the rod guide 2 is mounted is provided on the outer periphery of the main body portion 2a.

The inner diameter of the cushion holding portion 2c is larger than the inner diameter of the main body portion 2a. Therefore, an annular gap is formed between the cushion holding portion 2c and the piston rod 3.

At the lower part of the main body part 2a of the rod guide 2 in FIG. 2 and on the inner periphery of the cushion holding part 2c, there is an annular U packing 9 that comes into sliding contact with the outer periphery of the piston rod 3, and an upper end of the coil spring S in FIG. A spring receiving member 20 that holds the spring, an annular spacer 21, and a rebound cushion 15 are attached in this order. Specifically, the cushion holding portion 2c has an inner diameter that increases in three stages as it goes downward in FIG. 2, and is provided with a flange portion 2e protruding toward the inner circumference at the lowermost end in FIG. The U packing 9 is fitted into a portion of the cushion holding portion 2c where the inner diameter is the smallest, and provides a seal between the rod guide 2 and the piston rod 3.

The spring bearing member 20 includes an annular plate portion 20a and an annular fitting portion 20b extending downward in FIG. 2 from the inner periphery of the plate portion 20a and slidingly contacting the outer periphery of the piston rod 3. It is laminated together with the spacer 21 at the middle stage in FIG. 2 of 2c. Furthermore, the rebound cushion 15 is laminated on the lowermost step in FIG. 2 of the cushion holding part 2c and the lower end of the spacer 21 in FIG. It is clamped and fixed to the rod guide 2. The inner diameter of the rebound cushion 15 is larger than the outer diameter of the piston rod 3, and an annular gap is formed between the rebound cushion 15 and the piston rod 3. The rebound cushion 15 also has an annular protrusion 15a on its inner periphery that protrudes downward in FIG. 15a protrudes downward in FIG.

Continuing, the upper end of the coil spring S as an elastic member in FIG. 2 is fitted to the outer periphery of the fitting portion 20b of the spring receiving member 20. The coil spring S is attached to the rod guide 2 via a spring receiving member 20 held between the rebound cushion 15 and the rod guide 2. Note that the spacer 21 may be eliminated and the spring receiving member 20 may be fixed to the rod guide 2 using the rebound cushion 15. However, if the spacer 21 is provided, the position of the rebound cushion 15 can be placed downward in FIG. This has the advantage of making it easier to secure.

Note that the shoulder of the main body portion 2a is in contact with a C ring 10 attached to the inner circumference of the cylinder 1, and the rod guide 2 is restricted from moving in the direction of coming out of the cylinder 1, and the pressure inside the cylinder 1 is restricted. It is fixed to the cylinder 1 because it is pressed by the C-ring 10.

Furthermore, a dust seal 5 that slides on the outer periphery of the piston rod 3 is attached to the outer periphery of the upper end of the convex portion 2b of the rod guide 2 in FIG. 2 to prevent water, dust, etc. from entering into the cylinder 1. .

The piston rod 3 is inserted through the inner periphery of the rod guide 2 as described above. The piston rod 3 has a small diameter portion 3a at its tip, on which the piston 4, the expansion damping valve 11, the compression damping valve 12, and the rebound stopper 13 are mounted. A piston nut 14 is screwed onto the tip of the small diameter portion 3a, and the piston 4, the rebound damping valve 11, the compression damping valve 12, and the rebound stopper 13 are fixed to the piston rod 3 by the piston nut 14.

The rebound stopper 13 faces the protrusion 15a of the rebound cushion 15 in the axial direction. Therefore, when the shock absorber D is fully extended, the rebound stopper 13 comes into contact with the protrusion 15a of the rebound cushion 15, cutting off direct communication between the annular gap L on the inner peripheral side of the rebound cushion 15 and the expansion side chamber R1. It has become.

As described above, the piston 4 is attached to the tip of the piston rod 3 and is slidably inserted into the cylinder 1, and is located above the piston 4 in FIG. 1 facing the rod guide 2 inside the cylinder 1. It is divided into a growth side chamber R1 on the side and a compression side chamber R2 on the lower side than the piston 4 in FIG. The expansion side chamber R1 and the compression side chamber R2 are filled with liquid such as hydraulic oil. Note that the liquid may be, for example, water or an aqueous solution other than hydraulic oil.

The piston 4 includes a growth side passage 4a and a compression side passage 4b that communicate the growth side chamber R1 and the compression side chamber R2. The rebound damping valve 11 is stacked below the piston 4 in FIG. 1 and opens and closes the lower end of the rebound passage 4a in FIG. 1, and the compression damping valve 12 is stacked above the piston 4 in FIG. The upper end of the pressure side passage 4b in FIG. 1 is opened and closed. Both the expansion-side damping valve 11 and the compression-side damping valve 12 are laminated leaf valves constructed by laminating a plurality of leaf valves each made of an annular plate. Then, in the extension stroke of the shock absorber D in which the piston rod 3 moves upward in FIG. The valve opens and provides resistance to the flow of hydraulic oil passing through the extension passage 4a. The compression side damping valve 12 moves from the compression side chamber R2 compressed by the piston 4 to the expansion side chamber R1 expanded during the contraction stroke of the shock absorber D in which the piston rod 3 moves downward in FIG. 1 with respect to the cylinder 1. The valve opens and provides resistance to the flow of hydraulic oil passing through the passage 4b. The rebound stopper 13 is annular and stacked above the rebound damping valve 11 in FIG. 1, and faces the rebound cushion 15 attached to the rod guide 2.

Further, in this embodiment, the piston rod 3 has a hollow cylindrical shape, and is provided with a horizontal hole 3b that opens from above the small diameter portion 3a of the piston rod 3 in FIG. 2 and communicates with the inside. The horizontal hole 3b of the piston rod 3 and a hollow portion below the horizontal hole 3b in FIG. 1 form a passage P that communicates the expansion side chamber R1 and the compression side chamber R2. A cylindrical valve seat member 16 is attached to the inner circumference of the piston rod 3 and below the horizontal hole 3b, and a needle 17a is inserted into the piston rod 3 so as to be movable in the axial direction. has been done. The needle 17a is formed at the tip of the control rod 17 inserted into the piston rod 3, and can be moved in the axial direction by operating an adjuster (not shown) attached to the upper end of the piston rod 3 (not shown). When the needle 17a is moved closer to or closer to the valve seat member 16, the gap between the needle 17a and the valve seat member 16 can be widened or narrowed, so the resistance given to the flow of hydraulic oil passing through the passage P can be changed in size. . As described above, the shock absorber D of this embodiment includes the damping force adjustment valve V composed of the valve seat member 16 and the needle 17a.

The lower end of the cylinder 1 in FIG. 1 is closed, and is provided with a bracket for connecting the shock absorber D to the vehicle body or wheels, although not shown in detail. Furthermore, a free piston F is slidably inserted into the cylinder 1 and defines an air chamber G below the pressure side chamber R2.

When the shock absorber D expands, the expansion side damping valve 11 and the damping force adjustment valve V provide resistance to the flow of hydraulic oil from the compression side chamber R1 to the expanding compression side chamber R2, Shock absorber D generates a damping force that prevents extension. Therefore, by widening or narrowing the gap in the damping force adjustment valve V, the extension side damping force of the shock absorber D can be adjusted in height. Furthermore, during the extension stroke of the shock absorber D, since the piston rod 3 withdraws from the cylinder 1, the free piston F moves upward in FIG. 1 by an amount corresponding to the volume of the piston rod 3 withdrawing from the cylinder 1. The air chamber G expands, and the volume of the piston rod 3 withdrawn from the cylinder 1 is compensated for.

On the other hand, when the shock absorber D contracts, the pressure side damping valve 12 and the damping force adjustment valve V provide resistance to the flow of hydraulic oil from the compressed pressure side chamber R2 toward the expanding expansion side chamber R1. Furthermore, when the shock absorber D contracts, the piston rod 3 enters into the cylinder 1, so the free piston F moves downward in FIG. As the piston rod moves, the air chamber G contracts, and the volume of the piston rod 3 entering the cylinder 1 is compensated for. Therefore, when the shock absorber D is in the contraction stroke, the compression side damping valve 12 and the damping force adjustment valve V provide resistance to the flow of the hydraulic oil, so the shock absorber D generates a pressure side damping force that prevents contraction. Further, by widening or narrowing the gap in the damping force adjustment valve V, the compression side damping force of the shock absorber D can be adjusted in height.

In addition, in the above description, compensation for the volume of the piston rod 3 moving in and out of the cylinder 1 is performed by providing a free piston F in the cylinder 1 to form the air chamber G, but there is also a pressure side chamber outside the cylinder 1. A reservoir tank connected to R2 may be provided to compensate for the volume. In that case, a base valve that provides resistance to the flow of hydraulic oil from the pressure side chamber R2 toward the reservoir tank may be provided between the pressure side chamber R2 and the reservoir tank, so that the base valve contributes to the generation of the pressure side damping force. .

Next, a shutter 6 is attached to the rod guide 2 and slidably contacts the outer periphery of the piston rod 3 so as to be movable in the axial direction. As shown in FIGS. 2 and 3, the shutter 6 includes a cylindrical shutter portion 6a that slides on the outer periphery of the piston rod 3 so as to be movable in the axial direction, and a stopper side end that is the lower outer periphery of the shutter portion 6a in FIG. It is configured to include a flange portion 6b provided on the outer periphery and facing the rebound stopper 13, and a tapered surface 6c formed by an annular recess C provided from the inner periphery of the shutter portion 6a to the inner periphery of the flange portion 6b. .

Specifically, as shown in FIG. 2, the annular recess C is formed by cutting the inner periphery of the shutter part 6a into a truncated cone shape from the middle part downward, and by cutting the inner periphery side of the flange part 6b into a truncated cone shape. The shape is said to be possible. When the annular recess C is formed in the shutter 6 in this manner, a tapered surface 6c whose inclination angle changes midway is formed on the inner periphery of the shutter 6, and a horizontal surface 6d is formed at the upper end of the tapered surface 6c. The shutter 6 can close the horizontal hole 3b when in contact with the rebound stopper 13, and the annular recess C may face the horizontal hole 3b of the piston rod 3 when in contact with the rebound stopper 13. .

The lower end of a coil spring S in FIG. 2 is fitted to the outer periphery of the shutter portion 6a of the shutter 6, and the shutter 6 is connected to the rod guide 2 via the spring receiving member 20 and the coil spring S. Further, when the piston rod 3 moves upward in FIG. 2 relative to the cylinder 1 and comes into contact with the rebound stopper 13 as shown in FIG. Then, the horizontal hole 3b is closed. Further, when the shutter 6 comes into contact with the rebound stopper 13, the annular recess C faces the horizontal hole 3b and communicates with the pressure side chamber R2 via the passage P. In the shock absorber D of this embodiment, the elastic member is the coil spring S, but the elastic member may be an elastic body such as a spring or rubber other than the coil spring S.

In other words, even if the shutter 6 closes the horizontal hole 3b, the inside of the annular recess C is communicated with the pressure side chamber R2, and the pressure in the pressure side chamber R2 is transferred between the tapered surface 6c and the horizontal surface using the tapered surface 6c and the horizontal surface 6d of the shutter 6 as pressure receiving surfaces. 6d. Therefore, when the annular recess C faces the horizontal hole 3b, the shutter 6 receives an axial force that causes it to move away from the rebound stopper 13 due to the pressure of the pressure side chamber R2. Therefore, in the present embodiment, in the shutter 6, the pressure receiving part receives the pressure of the pressure side chamber R2 so as to be in contact with the rebound stopper 13 and to be separated from the rebound stopper 13 in a state where the passage P is closed. It is formed by the horizontal surface 6d. Note that the effective pressure receiving area in the pressure receiving part where the pressure of the pressure side chamber R2 acts to apply a force to separate the shutter 6 from the rebound stopper (stopper) 13 is the area of the pressure receiving part projected in the axial direction. What is necessary is just to set an effective pressure receiving area according to the force which it wants to apply to 6.

The shock absorber D configured as described above is in an extension stroke in which the piston rod 3 moves upward in FIG. 2 relative to the cylinder 1, and when the piston rod 3 moves until the shutter 6 contacts the rebound stopper 13, A shutter portion 6a of the shutter 6 completely faces the horizontal hole 3b and closes the passage P. Before the passage P is closed by the shutter 6, the growth side chamber R1 and the compression side chamber R2 are in communication via both the growth side passage 4a and the passage P, and when the passage P is closed by the shutter 6, the growth side chamber R1 and the compression side chamber R2 are in communication via both the growth side passage 4a and the passage P. The growth side chamber R1 and the compression side chamber R2 are in communication with each other only through the passage 4a. As described above, since the passage area is reduced when the passage P is closed by the shutter 6, the damping force generated by the buffer D is greater after the passage P is closed than before it is closed by the shutter 6. It will be more expensive. As described above, when the shutter 6 closes the passage P, the shock absorber D increases the damping force on the extension side, so the moving speed of the piston rod 3 on the extension side is reduced.

Further, in the shock absorber D of this embodiment, when the rebound stopper 13 further extends from the state in which it contacts the shutter 6 and the piston rod 3 moves upward in FIG. 3, the rebound cushion 15 contacts the rebound stopper 13. Direct communication between the annular gap L and the expansion side chamber R1 is cut off. In this manner, when the passage P is closed by the shutter 6 and the communication between the gap L and the growth side chamber R1 is cut off, when the piston rod 3 attempts to move upward in FIG. As the pressure increases, buffer D exhibits a hydraulic locking function that prevents further expansion. In this way, the shock absorber D exhibits a locking function when it is fully extended, so that it can prevent the rebound stopper 13 from crushing the rebound cushion 15 and colliding forcefully against the rod guide 2.

When the shock absorber D switches from the extension stroke to the contraction stroke from the state in which the gap L is closed by the shutter 6 and the rebound cushion 15, as the piston rod 3 moves downward in FIG. The pressure inside increases. The pressure within this pressure side chamber R2 acts through the passage P into the annular recess C of the shutter 6. Therefore, the pressure within the pressure side chamber R2 acts on the pressure receiving portion formed by the tapered surface 6c and the horizontal surface 6d of the shutter 6, and a force is generated that pushes the shutter 6 upward in FIG. Due to the action of this force, the shutter 6 and the rebound stopper 13 are separated, a gap is created between them, and the gap L and the pressure side chamber R2 are communicated via the passage P.

Then, the pressure in the gap L quickly rises, so the hydraulic lock is released, and the shock absorber D contracts smoothly without exerting an excessive damping force when switching from the extension operation to the contraction operation. That is, in switching from the extension operation to the contraction operation, the shock absorber D starts to contract at the beginning of the contraction stroke without increasing the damping force.

As described above, the shock absorber D of this embodiment includes the cylinder 1, the annular rod guide 2 provided at the end of the cylinder 1, and the rod guide 2, which is inserted into the cylinder 1 so as to be movable through the inner periphery of the rod guide 2. a piston rod 3 that is inserted into the cylinder 1 and divides the inside of the cylinder 1 into a compression side chamber R2 and an expansion side chamber R1 facing the rod guide 2; A passage P that communicates the side chamber R1 and the pressure side chamber R2, an annular shutter 6 that is attached to the outer periphery of the rod guide 2 so as to be freely movable in the axial direction to open and close the passage P, and a coil that connects the shutter 6 and the rod guide 2. The shutter 6 includes a spring (elastic member) S and a rebound stopper (stopper) 13 attached to the piston rod 3 and facing the shutter 6 in the axial direction. It has a pressure receiving part that receives the pressure of the pressure side chamber R2 so as to be spaced apart from the rebound stopper (stopper) 13 in the closed state.

In the shock absorber D configured in this way, even if the shutter 6 closes the passage P, the pressure in the pressure side chamber R2 acts on the pressure receiving part provided in the shutter 6 via the passage P, and the shutter 6 is turned into a rebound stopper ( A force is exerted to separate the shock absorber D from the stopper 13, and the shutter 6 immediately opens the passage P when the shock absorber D changes from an extended operation to a retracted operation. Therefore, in the shock absorber D of the present embodiment, the shutter 6 promptly opens the passage P when switching to the contraction stroke after the maximum extension, so that while exhibiting the hydraulic lock function at the maximum extension, At the time of switching to the contraction stroke after extension, the hydraulic lock is quickly released and the contraction operation is performed without generating excessive damping force. As described above, according to the shock absorber D of the present embodiment, the ride comfort in the vehicle can be improved by suppressing the damping force from becoming excessive when switching to the contraction stroke after the maximum extension.

In addition, in the shock absorber D of this embodiment, the shutter 6 is connected to the rod guide 2 by a coil spring (elastic member) S, and since the shutter 6 can be placed downward, the piston rod 3 can be extended to its maximum. By closing the passage P from the previous stage, it is possible to increase the damping force and reduce the impact at the maximum extension.

In the shock absorber D of this embodiment, the shutter 6 includes a cylindrical shutter portion 6a that slides on the outer periphery of the piston rod 3, and a rebound stopper that is provided on the outer periphery of the stopper side end of the shutter portion 6a. (stopper) 13; and an annular shape provided from the inner periphery of the shutter portion 6a to the inner periphery of the flange portion 6b, and facing the passage P with the shutter 6 in contact with the rebound stopper (stopper) 13. The pressure receiving portion is a tapered surface 6c formed by the annular recess C. When the pressure receiving part is formed by the tapered surface 6c in this way, a force equal to the value obtained by multiplying the effective pressure receiving area of the pressure receiving part projected in the axial direction by the pressure of the pressure side chamber R2 acts as a force to move the shutter 6 in the axial direction. . In addition, since a tapered surface 6c is formed on the inner peripheral side of the shutter 6 so that the rebound stopper (stopper) 13 side has a larger diameter, the tapered surface 6c passes through the pressure side chamber R2 and the annular recess C through the passage P and the air gap L. Since the liquid flowing into the gap L flows smoothly along the tapered surface 6c, the liquid can easily move into the gap L. Therefore, according to the buffer D of the present embodiment, the liquid can smoothly pass between the shutter 6 and the rebound stopper (stopper) 13, while ensuring the effective pressure receiving area of the pressure receiving part of the shutter 6. 6 can open the passage P more smoothly, the damping force at the time of switching from the extension operation to the contraction operation can be further reduced, and the riding comfort in the vehicle can be further improved. Note that although the pressure receiving portion in the shutter 6 of this embodiment includes the horizontal surface 6d, it may be formed only of the tapered surface 6c.

Further, as shown in FIG. 4, the annular recess C1 is a rectangular cutout from the middle part to the lower end of the inner circumference of the shutter part 6a of the shutter 6, and a rectangular cutout from the inner circumference to the middle part of the flange part 6b. It may also be a shape. When the annular recess C1 is formed in the shutter 6 in this way, a first annular surface 6e parallel to the rebound stopper (stopper) 13 is formed in the shutter portion 6a of the shutter 6, and a rebound A second annular surface 6f parallel to the stopper (stopper) 13 is formed. The pressure receiving portion is formed by the first annular surface 6e and the second annular surface 6f. Even if the pressure receiving portion is formed in this manner, the pressure in the pressure side chamber R2 can be applied to the shutter 6 to apply a force to separate it from the rebound stopper (stopper) 13.
In addition, as mentioned above, the effective pressure receiving area in the pressure receiving part where the pressure of the pressure side chamber R2 acts to apply a force to separate the shutter 6 from the rebound stopper (stopper) 13 is the area of the pressure receiving part projected in the axial direction. However, the effective pressure-receiving area may be set according to the initial setting applied to the shutter 6.

As shown in FIG. 5, a groove 6g is provided on the inner periphery of the shutter portion 6a of the shutter 6, and an annular groove 13a communicating with the groove 6g is provided from the inner periphery of the shutter side end of the rebound stopper 13 to the middle. The surface facing the annular groove 13a may be used as a pressure receiving portion. In this case, the rebound stopper (stopper) 13 also requires processing. On the other hand, when forming the pressure receiving part by providing the annular recesses C and C1 only in the shutter 6, it is only necessary to process the shutter 6, so that the processing cost of the buffer D can be reduced.

The shock absorber D of this embodiment also includes an annular rebound cushion 15 that is attached to the rod guide 2 and forms a gap L on the inner circumferential side when it comes into contact with the rebound stopper (stopper) 13. . According to the shock absorber D configured in this manner, when the rebound cushion 15 and the rebound stopper (stopper) 13 come into contact with each other after the passage P is closed by the shutter 6, the gap L is isolated from the growth side chamber R1 and the compression side chamber R2. Since the hydraulic locking function can be exerted in this manner, collision between the rod guide 2 and the rebound stopper (stopper) 13 can be prevented. In addition, in the shock absorber D of this embodiment, the shutter 6 is connected to the rod guide 2 by a coil spring (elastic member) S, and the shutter 6 can be placed downward, so that the shock when the shock absorber D is fully extended is Therefore, if the hydraulic locking function is not required, the rebound cushion 15 that forms the gap L that is sealed when the shock absorber D is fully extended can be omitted.

Further, in the embodiment described above, the damping force adjustment valve V was provided in the passage P, but the damping force adjustment valve V may be abolished.

Although the preferred embodiments of the present invention have been described in detail above, modifications, variations, and changes can be made without departing from the scope of the claims.

DESCRIPTION OF SYMBOLS 1... Cylinder, 2... Rod guide, 3... Piston rod, 4... Piston, 6... Shutter, 6a... Shutter part, 6b... Flange part, 6c... Tapered surface (pressure receiving part), 6d... horizontal surface (pressure receiving part), 6e... first annular surface (pressure receiving part), 6f... second annular surface (pressure receiving part), 13... rebound stopper ( Stopper), 15... Rebound cushion, C, C1... Annular recess, L... Gap, P... Passage, D... Buffer, R1... Rebound side chamber, R2... Compression side Chamber, S...Coil spring (elastic member)

Claims (4)

cylinder and
an annular rod guide provided at the end of the cylinder;
a piston rod that is inserted through the inner periphery of the rod guide and movably inserted into the cylinder;
a piston inserted into the cylinder to partition the inside of the cylinder into a compression side chamber and a growth side chamber facing the rod guide;
a passage that opens from the side of the piston rod and communicates the expansion side chamber and the compression side chamber;
an annular shutter that is axially movably attached to the outer circumference of the piston rod and opens and closes the passage;
an elastic member connecting the shutter and the rod guide;
a stopper attached to the piston rod and facing the shutter in the axial direction;
The shock absorber is characterized in that the shutter has a pressure receiving part that receives the pressure of the pressure side chamber so as to be separated from the stopper while contacting the stopper and closing the passage. The shutter includes a cylindrical shutter portion that slides on the outer periphery of the piston rod, a flange portion that is provided on the outer periphery of a stopper side end of the shutter portion and faces the stopper, and a flange portion that extends from the inner periphery of the shutter portion to the flange portion. an annular recess provided around the inner periphery of the section and facing the passage with the shutter in contact with the stopper;
The shock absorber according to claim 1, wherein the pressure receiving portion is a tapered surface formed by the annular recess. The shutter includes a cylindrical shutter part that slides on the outer periphery of the piston rod, a flange part provided on the outer periphery of a stopper side end of the shutter part and facing the stopper, and a flange part that extends from the inner periphery of the shutter part to the flange part. an annular recess provided around the inner periphery of the section and facing the passage with the shutter in contact with the stopper;
The pressure receiving portion is formed of a first annular surface formed in the annular recess and parallel to the stopper, and a second annular surface formed in the annular recess and parallel to the stopper. The shock absorber according to claim 1, characterized in that: The buffer according to any one of claims 1 to 3, further comprising an annular rebound cushion that is attached to the rod guide and forms a gap on the inner circumferential side when it comes into contact with the stopper. vessel.