JP2021148137A - Shock absorber - Google Patents

Abstract

To provide a shock absorber capable of improving ride quality on a vehicle while exerting a lock function when extended in maximum.SOLUTION: A shock absorber D includes: a cylinder 1; an annular rod guide 2 disposed on an end portion of the cylinder 1; a piston rod 3 inserted to an inner periphery of the rod guide 2 and slidably inserted into the cylinder 1; a piston 4 inserted into the cylinder 1 for dividing the inside of the cylinder 1 into a pressure-side chamber R2 and an extension-side chamber R1 facing the rod guide 2; a passage P opened from a side part of the piston rod 3 to communicate the extension-side chamber R1 and the pressure-side chamber R2; an annular shutter 6 axially movable mounted on an outer periphery of the rod guide 2 for opening and closing the passage P; an elastic member S connecting the shutter 6 and the rod guide 2; and a stopper mounted on the piston rod 3 and opposed to the shutter 6 in the axial direction. The shutter 6 has a pressure receiving portion receiving a pressure of the pressure-side chamber R2 to be separated from the stopper in a state of closing the passage P by contact with the stopper.SELECTED DRAWING: Figure 2

Description

The present invention relates to a shock absorber.

The shock absorber is used, for example, as being interposed between the vehicle body and wheels in a saddle-mounted vehicle, and suppresses vibration between the vehicle body and wheels by a damping force generated during expansion and contraction.

The shock absorber generates damping force by the valve mounted inside, but in addition to this, in order to prevent a violent collision between the rod guide and the rebound stopper provided at the tip of the piston rod at the time of maximum extension, a stroke It may be equipped with a hydraulic lock mechanism that suppresses further extension when it extends to the vicinity of the end.

The hydraulic lock mechanism is, for example, an annular rebound cushion attached to a rod guide attached to the end of a cylinder, and a piston attached to the rod guide via a coil spring and slidably sliding on the outer periphery of the piston rod. It is provided with a shutter that opens and closes a damping force adjusting passage that communicates the extension side chamber and the compression side chamber provided on the rod.

Specifically, when the piston rod is displaced to the vicinity of the stroke end on the extension side with respect to the cylinder, the shutter abuts on the annular stopper mounted on the outer circumference of the piston rod and is damped to open from the side of the piston rod. Block the force adjustment passage. Since the damping force adjusting passage is blocked by the shutter, the pressure rise in the extension side chamber R1 is promoted and the movement of the piston rod to the extension side is suppressed. Further, when the shock absorber is further extended from this state, the shutter moves together with the stopper while the damping force adjusting passage is closed, and the rebound cushion comes into contact with the stopper. In this state, the damping force adjusting passage is blocked by the shutter, and the space on the inner peripheral side of the rebound cushion is isolated from the extension side chamber and the compression side chamber by the contact between the rebound cushion and the rebound stopper. In such a situation, the hydraulic lock mechanism provides a hydraulic lock function in which the piston rod raises the pressure in the space with respect to the stroke to the extension side to prevent the piston rod from moving further to the extension side. It exerts its effect to prevent the rebound stopper and the rod guide from colliding vigorously (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2019-215040

In this way, in the conventional shock absorber, the shutter can be arranged at a position separated from the rod guide by the coil spring, and the passage for adjusting the damping force can be closed at an early timing. Therefore, the speed of the piston rod can be sufficiently reduced to the maximum. The impact during extension can be mitigated.

However, in the conventional shock absorber, when the shutter closes the damping force adjusting passage and then the piston rod moves in the opposite direction and contracts, the piston rod required for the shutter to open the damping force adjusting passage. The amount of movement to the contraction side increases. In other words, the distance from the shutter blocking the damping force adjustment passage to the piston rod reaching the stroke end can be increased by the amount that the shutter is shifted to the piston side by the coil spring, 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 until the shutter opens the damping force adjusting passage increases.

Then, when the shock absorber is extended, the damping force adjusting passage is blocked by the shutter and the hydraulic lock functions until the shutter opens the damping force adjusting passage when the shock absorber contracts. The lock function remains exerted. In such a situation, the damping force at the initial stage of contraction of the shock absorber becomes high, and the shock absorber cannot be smoothly contracted.

Therefore, an object of the present invention is to provide a shock absorber capable of improving the riding comfort in a vehicle by suppressing an excessive damping force at the time of switching to the contraction stroke after the maximum extension.

In order to solve the above-mentioned problems, the shock absorber of the present invention is inserted into the cylinder, an annular rod guide provided at the end of the cylinder, and the inner circumference of the rod guide so as to be movable in the cylinder. Piston rod, a piston that is inserted into the cylinder and divides the inside of the cylinder into a compression side chamber and an extension side chamber facing the rod guide, and a passage that opens from the side of the piston rod to communicate the extension side chamber and the compression side chamber. An annular shutter that is mounted on the outer circumference 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 mounted on the piston rod and faces the shutter in the axial direction. The shutter has a pressure receiving portion that receives the pressure of the compression side chamber R2 so as to be separated from the stopper in a state where the shutter is in contact with the stopper and the passage P is closed.

In the shock absorber configured in this way, the shutter quickly opens the passage when switching to the contraction stroke after the maximum extension, so that the hydraulic pressure lock function at the maximum extension is exhibited, and the contraction after the maximum extension is performed. It contracts without generating excessive damping force when switching to the stroke.

Further, the shutter in the shock absorber has a cylindrical shutter portion that is in sliding contact with the outer circumference of the piston rod, a flange portion that is provided on the outer circumference of the stopper side end of the shutter portion and faces the stopper, and a flange portion from the inner circumference of the shutter portion. It may have an annular recess facing the passage in a state where the shutter is in contact with the stopper, and the pressure receiving portion may be a tapered surface formed by the annular recess. According to the shock absorber configured in this way, the liquid can smoothly pass between the shutter and the stopper while ensuring the effective pressure receiving area of the pressure receiving portion 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.

Further, the shutter in the shock absorber includes a cylindrical shutter portion that is in sliding contact with the outer periphery of the piston rod, a flange portion provided on the outer periphery of the stopper side end of the shutter portion and facing the stopper, and a flange portion from the inner circumference of the shutter portion. The pressure receiving portion is formed on the shutter portion by the annular recess and has a first annular surface parallel to the stopper. And a second annular surface formed on the flange portion at the annular recess and parallel to the stopper. Even if the pressure receiving portion is formed in this way, the pressure in the compression side chamber can be applied so as to apply a force to the shutter to separate it from the stopper.

As described above, when the annular recess is provided only in the shutter to form the pressure receiving portion, only the shutter needs to be processed, so that the processing cost of the shock absorber can be reduced.

Further, the shock absorber may be provided with an annular rebound cushion which is attached to the rod guide and forms a gap on the inner peripheral 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 blocked by the shutter, the gap can be isolated from the extension side chamber and the compression side chamber and the hydraulic pressure locking function can be exerted. It can prevent the collision between the guide and the stopper.

From the above, according to the shock absorber of the present invention, while exhibiting the locking function at the time of maximum extension, it is possible to suppress the excessive damping force at the time of switching to the contraction stroke after maximum extension, and the riding comfort in the vehicle. Can be improved.

It is a vertical sectional view of the shock absorber in one embodiment. It is a partially enlarged vertical sectional view of the shock absorber in one embodiment. It is a partially enlarged vertical sectional view of the shock absorber in one embodiment. It is a partially enlarged vertical sectional view of the shock absorber in the 1st modification of one Embodiment. It is a partially enlarged vertical sectional view of the shock absorber in the 2nd modification of one Embodiment.

Hereinafter, the present invention will be described based on the embodiments shown in the figure. As shown in FIGS. 1 and 2, the shock absorber D in one embodiment is inserted through the cylinder 1, the annular rod guide 2 provided at the end of the cylinder 1, and the inner circumference of the rod guide 2. A piston rod 3 that is movably inserted into the cylinder 1, a piston 4 that is inserted into the cylinder 1 and divides the inside of the cylinder 1 into a compression side chamber R2 and an extension side chamber R1 facing the rod guide 2, and a piston rod 3. A passage P that opens from the side of the rod guide 2 and communicates the extension 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 a shutter 6. It is configured to include a coil spring S as an elastic member connecting the rod guide 2 and a rebound stopper 13 as a stopper mounted on the piston rod 3 and opposed to the shutter 6 in the axial direction. Then, in the case of this shock absorber D, it is used by being interposed between the vehicle body and the wheels in a vehicle (not shown), and the vibration of the vehicle body and the wheels is suppressed.

Hereinafter, each part of the shock absorber D will be described in detail. 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 circumference of the rod guide 2, and the rod guide 2 guides the relative movement of the piston rod 3 in the vertical direction in FIG. 1, which is the axial direction with respect to the cylinder 1.

The rod guide 2 has an annular main body portion 2a that fits in the cylinder 1, a cylindrical convex portion 2b that rises upward in FIG. 2 from the inner circumference of the main body portion 2a, and a lower end outer circumference of the main body portion 2a in FIG. It is provided with a cylindrical cushion holding portion 2c that rises downward. Further, a tubular bush 7 that is in sliding contact with the outer circumference of the piston rod 3 is mounted from the inner circumference of the main body portion 2a of the rod guide 2 to the inner circumference of the convex portion 2b. Further, an annular groove 2d on 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 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.

An annular U-packing 9 that is in sliding contact with the outer periphery of the piston rod 3 and an upper end of the coil spring S in FIG. The spring receiving member 20, the annular spacer 21, and the rebound cushion 15 are attached in this order. Specifically, the cushion holding portion 2c has an inner diameter of three steps larger toward the lower side in FIG. 2, and a flange portion 2e protruding toward the inner peripheral side is provided at the lowermost end in FIG. The U packing 9 is fitted in a portion where the inner diameter of the cushion holding portion 2c is minimized, and seals between the rod guide 2 and the piston rod 3.

The spring receiving member 20 includes an annular plate portion 20a and an annular fitting portion 20b that extends downward in FIG. 2 from the inner circumference of the plate portion 20a and is in sliding contact with the outer periphery of the piston rod 3, and is a cushion holding portion. It is laminated together with the spacer 21 in the middle stage of FIG. 2 of 2c. Further, the rebound cushion 15 is laminated on the lowermost step portion of the cushion holding portion 2c in FIG. 2 and the lower center of FIG. 2 of the spacer 21, and the outer periphery thereof is formed by the lower step portion and the flange portion 2e. It is sandwiched 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. Further, the rebound cushion 15 is provided with an annular protruding portion 15a protruding downward in FIG. 2 on the inner circumference, and is a protruding portion from the lowermost end of the rod guide 2 in a state of being attached to the cushion holding portion 2c of the rod guide 2. 15a projects downward in FIG.

Subsequently, 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 sandwiched between the rebound cushion 15 and the rod guide 2. The spacer 21 may be abolished and the spring receiving member 20 may be fixed to the rod guide 2 with the rebound cushion 15. However, if the spacer 21 is provided, the position of the rebound cushion 15 can be arranged downward in FIG. 2, the close contact length of the coil spring S can be lengthened, the degree of freedom in designing the coil spring S is improved, and the accommodation space for the coil spring S is further improved. There is an advantage that it becomes easy to secure.

The shoulder of the main body 2a is in contact with the C ring 10 mounted on 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. Is pressed against the C ring 10 and is fixed to the cylinder 1.

Further, a dust seal 5 that is in sliding contact with the outer periphery of the piston rod 3 is mounted on 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 the cylinder 1. ..

The piston rod 3 is inserted through the inner circumference of the rod guide 2 as described above. The piston rod 3 is provided with a small diameter portion 3a at the tip to which the piston 4, the extension side damping valve 11, the compression side damping valve 12, and the rebound stopper 13 are mounted. A piston nut 14 is screwed to the tip of the small diameter portion 3a, and the piston 4, the extension side damping valve 11, the compression side 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 protruding portion 15a of the rebound cushion 15 in the axial direction. Therefore, when the shock absorber D is fully extended, the rebound stopper 13 abuts on the protruding portion 15a of the rebound cushion 15 so as to cut off the direct communication between the annular gap L on the inner peripheral side of the rebound cushion 15 and the extension side chamber R1. It has become.

As described above, the piston 4 is mounted on the tip of the piston rod 3 and is slidably inserted into the cylinder 1, and is above the piston 4 in FIG. 1 facing the rod guide 2 in the cylinder 1. It is divided into an extension side chamber R1 on the side and a compression side chamber R2 on the lower side of the piston 4 in FIG. The extension side chamber R1 and the compression side chamber R2 are filled with a liquid such as hydraulic oil. In addition to the hydraulic oil, the liquid may be a liquid such as water or an aqueous solution.

The piston 4 includes an extension side passage 4a and a compression side passage 4b that communicate the extension side chamber R1 and the compression side chamber R2. Then, the extension side damping valve 11 is laminated in the lower part of FIG. 1 of the piston 4 to open and close the lower end of FIG. 1 of the extension side passage 4a, and the compression side damping valve 12 is laminated in the upper part of FIG. 1 of the piston 4. The upper end of the compression side passage 4b in FIG. 1 is opened and closed. The extension side damping valve 11 and the compression side damping valve 12 are both laminated leaf valves formed by laminating a plurality of leaf valves made of an annular plate. Then, the extension side damping valve 11 moves from the extension side chamber R1 compressed by the piston 4 to the compression side chamber R2 expanded in the extension stroke of the shock absorber D in which the piston rod 3 moves upward in FIG. 1 with respect to the cylinder 1. A valve is opened and resistance is given to the flow of hydraulic oil passing through the extension side passage 4a. The compression side damping valve 12 is compressed from the compression side chamber R2 compressed by the piston 4 toward the extension side chamber R1 in 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. It opens a valve and provides resistance to the flow of hydraulic oil passing through the passage 4b. Further, the rebound stopper 13 is annular and is laminated on the upper side of FIG. 1 of the extension side damping valve 11 and faces the rebound cushion 15 attached to the rod guide 2.

Further, the piston rod 3 has a cylindrical shape having a hollow inside in the present embodiment, and has a lateral hole 3b that opens from above in FIG. 2 and leads to the inside of the small diameter portion 3a of the piston rod 3. A passage P for communicating the extension side chamber R1 and the compression side chamber R2 is formed between the lateral hole 3b of the piston rod 3 and the hollow portion in the lower part of FIG. 1 than the lateral hole 3b. A cylindrical valve seat member 16 is mounted on the inner circumference of the piston rod 3 below the lateral 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 a 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). Then, when the needle 17a is brought 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 that the resistance given to the flow of hydraulic oil passing through the passage P can be changed. .. As described above, the shock absorber D of the present embodiment includes the damping force adjusting 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 although not shown in detail, a bracket for connecting the shock absorber D to the vehicle body or the wheel side is provided. Further, a free piston F for partitioning the air chamber G is slidably inserted into the cylinder 1 below the compression side chamber R2.

Then, when the shock absorber D is extended, the extension side damping valve 11 and the damping force adjusting valve V provide resistance to the flow of hydraulic oil from the compressed extension side chamber R1 to the expanding compression side chamber R2. The shock absorber D generates a damping force that hinders elongation. Therefore, the extension side damping force of the shock absorber D can be adjusted to be high or low by widening or narrowing the gap in the damping force adjusting valve V. Further, during the extension stroke of the shock absorber D, the piston rod 3 retreats from the inside of the cylinder 1, so that the free piston F moves upward in FIG. 1 by the amount corresponding to the volume of the piston rod 3 retreating from the inside of the cylinder 1. The air chamber G is expanded, and the volume of the piston rod 3 retracting from the cylinder 1 is compensated.

On the contrary, when the shock absorber D contracts, the compression side damping valve 12 and the damping force adjusting valve V provide resistance to the flow of hydraulic oil from the compressed compression side chamber R2 toward the expanding extension side chamber R1. Further, when the shock absorber D is contracted, the piston rod 3 invades the cylinder 1, so that the free piston F moves downward in FIG. 1 by the amount corresponding to the volume of the piston rod 3 invading the cylinder 1. As it moves, the air chamber G shrinks, and the volume of the piston rod 3 entering the cylinder 1 is compensated. Therefore, when the shock absorber D is in the contraction stroke, the compression side damping valve 12 and the damping force adjusting valve V provide resistance to the flow of the hydraulic oil described above, so that the shock absorber D generates a compression side damping force that hinders contraction. Further, the compression side damping force of the shock absorber D can be adjusted to be high or low by widening or narrowing the gap in the damping force adjusting valve V.

In the above-mentioned place, the volume of the piston rod 3 entering and exiting the cylinder 1 is compensated by providing the free piston F in the cylinder 1 to form the air chamber G, but the compression side chamber outside the cylinder 1. A reservoir tank communicating with R2 may be provided to compensate for the volume. In that case, a base valve that gives resistance to the flow of hydraulic oil from the compression side chamber R2 to the reservoir tank may be provided between the compression side chamber R2 and the reservoir tank so that the base valve contributes to the generation of the compression side damping force. ..

Subsequently, the rod guide 2 is equipped with a shutter 6 that is slidably contacted with 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 has a cylindrical shutter portion 6a that is slidably in contact with 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 outer periphery of the lower end in FIG. 2 of the shutter portion 6a. 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 circumference of the shutter portion 6a to the inner circumference of the flange portion 6b. ..

Specifically, as shown in FIG. 2, the annular recess C is cut into a truncated cone shape from the middle portion of the inner circumference of the shutter portion 6a to the lower side, and the inner peripheral side of the flange portion 6b is cut into a truncated cone shape. It is said that it can be shaped. When the annular recess C is formed in the shutter 6 in this way, a tapered surface 6c whose inclination angle changes in the middle is formed on the inner circumference of the shutter 6, and a horizontal plane 6d is formed at the upper end of the tapered surface 6c. The shutter 6 may close the lateral hole 3b in the state of being in contact with the rebound stopper 13, and the annular recess C may be opposed to the lateral hole 3b of the piston rod 3 in the state of being in contact with the rebound stopper 13. ..

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

That is, even if the shutter 6 closes the lateral hole 3b, the inside of the annular recess C is communicated with the compression side chamber R2, and the pressure in the compression side chamber R2 is the tapered surface 6c and the horizontal plane with the tapered surface 6c and the horizontal plane 6d of the shutter 6 as the pressure receiving surface. It acts on 6d. Therefore, when the annular recess C faces the lateral hole 3b, the shutter 6 receives an axial force away from the rebound stopper 13 due to the action of the pressure of the compression side chamber R2. Therefore, in the present embodiment, in the shutter 6, the pressure receiving portion that receives the pressure of the compression side chamber R2 so as to be separated from the rebound stopper 13 in a state of being in contact with the rebound stopper 13 and closing the passage P is the tapered surface 6c and the tapered surface 6c. It is formed by the horizontal plane 6d. The effective pressure receiving area in the pressure receiving portion on which the pressure of the pressure side chamber R2 acts so as to apply a force to separate the shutter 6 from the rebound stopper (stopper) 13 is the area projected in the axial direction of the pressure receiving portion. The effective pressure receiving area may be set according to the force to be applied to 6.

When the shock absorber D configured in this way is in the extension stroke in which the piston rod 3 moves upward in FIG. 2 with respect to the cylinder 1, the piston rod 3 moves until the shutter 6 abuts on the rebound stopper 13. The shutter portion 6a of the shutter 6 completely faces the lateral hole 3b and closes the passage P. Before the passage P is closed by the shutter 6, the extension side chamber R1 and the compression side chamber R2 are in a communicating state via both the extension side passage 4a and the passage P, and when the passage P is blocked by the shutter 6, the extension side The extension side chamber R1 and the compression side chamber R2 are communicated with each other only in the passage 4a. In this way, since the passage area is reduced by closing the passage P by the shutter 6, the damping force generated by the shock absorber D is after the passage P is closed by the shutter 6 than before. Is higher. As described above, when the shutter 6 closes the passage P, the shock absorber D increases the damping force on the extension side, so that the moving speed of the piston rod 3 toward the extension side is reduced.

Further, in the shock absorber D of the present embodiment, when the rebound stopper 13 further extends from the state of being in contact with the shutter 6 and the piston rod 3 moves upward in FIG. 3, the rebound cushion 15 hits the rebound stopper 13. In contact with each other, the direct communication between the annular gap L and the extension side chamber R1 is cut off. In this way, in a state where the passage P is blocked by the shutter 6 and the communication between the gap L and the extension side chamber R1 is cut off, when the piston rod 3 tries to move upward in FIG. 2, it is in the gap L. As the pressure rises, the shock absorber D exerts a hydraulic locking function that suppresses further elongation. In this way, since the shock absorber D exerts a locking function at the time of maximum extension, it is possible to prevent the rebound stopper 13 from crushing the rebound cushion 15 and vigorously colliding with the rod guide 2.

When the shock absorber D is switched 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, the compression side chamber R2 is moved downward in FIG. 2 of the piston rod 3. The pressure inside rises. The pressure in the compression side chamber R2 acts on the annular recess C of the shutter 6 via the passage P. Therefore, the pressure in the compression side chamber R2 acts on the pressure receiving portion formed by the tapered surface 6c and the horizontal plane 6d of the shutter 6, and a force is generated on the shutter 6 to push it upward in FIG. Due to the action of this force, the shutter 6 and the rebound stopper 13 are separated from each other, a gap is formed between them, and the gap L and the compression side chamber R2 are communicated with each other through the passage P.

Then, since the pressure in the gap L rises rapidly, the hydraulic pressure lock is released, and the shock absorber D contracts smoothly without exerting an excessive damping force in the switch from the extension operation to the contraction operation. That is, the shock absorber D begins to contract at the initial stage of the contraction stroke without increasing the damping force at the switching from the extension operation to the contraction operation.

As described above, the shock absorber D of the present embodiment is inserted into the cylinder 1, the annular rod guide 2 provided at the end of the cylinder 1, and the inner circumference of the rod guide 2 so as to be movable in the cylinder 1. The piston rod 3 is inserted into the cylinder 1, and the inside of the cylinder 1 is divided into the compression side chamber R2 and the extension side chamber R1 facing the rod guide 2. The piston 4 is opened from the side of the piston rod 3 and extended. A passage P that connects the 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 a cylinder that connects the shutter 6 and the rod guide 2. A spring (elastic member) S and a rebound stopper (stopper) 13 mounted on the piston rod 3 and facing the shutter 6 in the axial direction are provided, and the shutter 6 abuts on the rebound stopper (stopper) 13 to pass through the passage P. It has a pressure receiving portion that receives the pressure of the compression side chamber R2 so as to be separated 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 compression side chamber R2 acts on the pressure receiving portion provided in the shutter 6 through the passage P, and the shutter 6 is rebounded. A force for separating from the stopper) 13 is exerted, and when the shock absorber D changes from the extension operation to the contraction operation, the shutter 6 promptly opens the passage P. Therefore, in the shock absorber D of the present embodiment, when the shutter 6 is switched to the contraction stroke after the maximum extension, the shutter 6 promptly opens the passage P, so that the buffer D exhibits the hydraulic pressure lock function at the maximum extension, but at the maximum. At the time of switching to the contraction stroke after extension, the hydraulic pressure lock is quickly released and the contraction operation is performed without generating an excessive damping force. From the above, according to the shock absorber D of the present embodiment, it is possible to suppress the excessive damping force in the switching to the contraction stroke after the maximum extension and improve the riding comfort in the vehicle.

Further, in the shock absorber D of the present embodiment, the shutter 6 is connected to the rod guide 2 by the coil spring (elastic member) S, and the shutter 6 can be arranged downward, so that the piston rod 3 is extended to the maximum. However, the passage P can be blocked from the previous stage to increase the damping force and alleviate the impact at the time of maximum extension.

Further, in the shock absorber D of the present embodiment, the shutter 6 is provided on the outer periphery of the cylindrical shutter portion 6a that is in sliding contact with the outer periphery of the piston rod 3 and the stopper side end of the shutter portion 6a to provide a rebound stopper. A flange portion 6b facing the (stopper) 13 and an annular shape provided from the inner circumference of the shutter portion 6a to the inner circumference of the flange portion 6b and facing the passage P with the shutter 6 in contact with the rebound stopper (stopper) 13. It has a recess C, and the pressure receiving portion is a tapered surface 6c formed by the annular recess C. When the pressure receiving portion is formed by the tapered surface 6c in this way, the force of the value obtained by multiplying the effective pressure receiving area projected in the axial direction by the pressure of the pressure side chamber R2 acts as a force to move the pressure receiving portion to the shutter 6 in the axial direction. .. Further, since the tapered surface 6c is formed on the inner peripheral side of the shutter 6 so that the rebound stopper (stopper) 13 side has a large diameter, the gap L passes through the compression side chamber R2 and the annular recess C via the passage P. Since the liquid flowing into the liquid flows smoothly along the tapered surface 6c, it becomes easy for the liquid to move into the gap L. Therefore, according to the shock absorber 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 portion of the shutter 6. Since the passage P can be opened more smoothly by No. 6, 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. Although the pressure receiving portion in the shutter 6 of the present embodiment includes the horizontal plane 6d, it may be formed only by the tapered surface 6c.

Further, as shown in FIG. 4, the annular recess C1 is cut out in a rectangular shape from the middle portion to the lower end of the inner circumference of the shutter portion 6a of the shutter portion 6 and is cut out in a rectangular shape from the inner circumference to the middle portion of the flange portion 6b. It may be in shape. When the annular recess C1 is formed in the shutter 6 in this way, the shutter portion 6a of the shutter 6 is formed with a first annular surface 6e parallel to the rebound stopper (stopper) 13, and the flange portion 6b of the shutter 6 is rebounded. A second annular surface 6f parallel to the stopper (stopper) 13 is formed. The pressure receiving portion is formed of the first annular surface 6e and the second annular surface 6f. Even if the pressure receiving portion is formed in this way, the pressure of the compression side chamber R2 can be applied so as to apply a force to the shutter 6 to separate from the rebound stopper (stopper) 13.
As described above, the effective pressure receiving area in the pressure receiving portion on which the pressure of the pressure side chamber R2 acts so as to apply a force to separate the shutter 6 from the rebound stopper (stopper) 13 is the area projected in the axial direction of the pressure receiving portion. However, the effective pressure receiving area may be set according to the setting from scratch acting on the shutter 6.

As shown in FIG. 5, a groove 6 g is provided on the inner circumference of the shutter portion 6a of the shutter 6, and an annular groove 13a leading to the groove 6 g is provided from the inner circumference of the shutter side end of the rebound stopper 13 to the middle, and the shutter 6 is provided. The surface facing the annular groove 13a of the above may be used as the pressure receiving portion. In this way, the rebound stopper (stopper) 13 also needs to be processed. On the other hand, when the annular recesses C and C1 are provided only in the shutter 6 to form the pressure receiving portion, only the shutter 6 needs to be processed, so that the processing cost of the shock absorber D can be reduced.

Further, the shock absorber D of the present embodiment includes an annular rebound cushion 15 that is attached to the rod guide 2 and forms a gap L on the inner peripheral side when it comes into contact with the rebound stopper (stopper) 13. .. According to the shock absorber D configured in this way, 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 extension side chamber R1 and the compression side chamber R2. Since the hydraulic pressure locking function can be exerted, the collision between the rod guide 2 and the rebound stopper (stopper) 13 can be prevented. In the shock absorber D of the present embodiment, the shutter 6 is connected to the rod guide 2 by a coil spring (elastic member) S, the shutter 6 can be arranged downward, and the impact at the time of maximum extension of the shock absorber D is achieved. Therefore, if it is not necessary to exert the hydraulic pressure locking function, the rebound cushion 15 that forms the void L that is sealed when the shock absorber D is fully extended can be omitted.

Further, in the above-described embodiment, the damping force adjusting valve V is provided in the passage P, but the damping force adjusting valve V may be abolished.

Although the preferred embodiments of the present invention have been described in detail above, they can be modified, modified, and modified as long as they do not deviate from the claims.

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 plane (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 ... void, P ... passage, D ... shock absorber, R1 ... extension chamber, R2 ... compression side Chamber, S ... Cylinder spring (elastic member)

Claims (4)

Cylinder and
An annular rod guide provided at the end of the cylinder and
A piston rod that is inserted through the inner circumference of the rod guide and movably inserted into the cylinder.
A piston that is inserted into the cylinder and divides the inside of the cylinder into a compression side chamber and an extension side chamber facing the rod guide.
A passage that opens from the side of the piston rod and communicates the extension side chamber and the compression side chamber,
An annular shutter that is mounted on the outer circumference of the piston rod so as to be movable in the axial direction and opens and closes the passage.
An elastic member that connects the shutter and the rod guide,
A stopper mounted on the piston rod and facing the shutter in the axial direction is provided.
The shutter is a shock absorber having a pressure receiving portion that receives the pressure of the compression side chamber so as to be separated from the stopper in a state where the shutter is in contact with the stopper and the passage is closed. The shutter includes a cylindrical shutter portion that is in sliding contact with the outer circumference of the piston rod, a flange portion that is provided on the outer periphery of the stopper side end of the shutter portion and faces the stopper, and the flange from the inner circumference of the shutter portion. It is provided over the inner circumference of the portion and has an annular recess facing the passage in a state where the shutter is 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 portion that is in sliding contact with the outer circumference of the piston rod, a flange portion that is provided on the outer periphery of the stopper side end of the shutter portion and faces the stopper, and the flange from the inner circumference of the shutter portion. It is provided over the inner circumference of the portion and has an annular recess facing the passage in a state where the shutter is in contact with the stopper.
The pressure receiving portion is formed by a first annular surface formed on the shutter portion by the annular recess and parallel to the stopper, and a second annular surface formed on the flange portion by the annular recess and parallel to the stopper. The shock absorber according to claim 1, wherein the shock absorber is provided. The buffer according to any one of claims 1 to 3, wherein an annular rebound cushion that is attached to the rod guide and forms a gap on the inner peripheral side when it comes into contact with the stopper is provided. vessel.

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