JP6731537B2 - Shock absorber - Google Patents

Description

The present invention relates to improvements in shock absorbers.

Conventionally, some shock absorbers are provided with a hydraulic cushion, and the shock absorber absorbs and relaxes the impact energy when the shock absorber is extended or contracted most.

For example, the hydraulic cushion described in JP2015-500970A is a rebound cushion that cushions the shock when the shock absorber is extended most, and is a shock absorber that is provided on the outer circumference of the case and the case provided at the upper end of the cylinder. Has an annular ring that fits into the case when it approaches the most extended state, and a stopper that is fixed to the outer periphery of the ring of the piston rod on the side opposite to the case and restricts movement of the ring to the side opposite to the case. Further, a throttle groove is formed in the end portion of the ring on the stopper side, and when the ring is in contact with the stopper, a throttle passage is formed between them by the throttle groove.

In this shock absorber, when the shock absorber approaches the most extended state and the ring is fitted into the case, the space between the ring and the case is closed, and the liquid in the case flows out of the case through the throttle passage. As a result, resistance is given to the flow of the liquid by the throttle passage, so that the pressure in the case rises and a stroke-dependent secondary damping force that suppresses the extension operation of the shock absorber is generated.

As described above, according to the conventional shock absorber, when the stroke amount toward the extension side becomes large and approaches the most extended state, the ring fits in the case and the hydraulic cushion operates, and the main shock absorber is generated. The secondary damping force by the hydraulic cushion can be added to the damping force of. Therefore, the damping force of the shock absorber as a whole can be increased near the maximum extension to absorb and relax the impact energy at the maximum extension.

For example, when a shock absorber is mounted on a vehicle, in order to improve the riding comfort of the vehicle, the axial length of the case is lengthened to increase the stroke amount of the ring moving in the case to reduce the impact energy. It is preferable that the absorption is moderated. In addition, in order to improve the ride comfort of the vehicle, the stroke speed of the shock absorber is low in the normal stroke region where the shock absorber strokes during normal use of the shock absorber, such as when the vehicle travels on a good road. It is preferable to reduce the damping force in the range.

However, it is difficult for the conventional shock absorber to satisfy both of them. This is because when the axial length of the case is made sufficiently long so that the impact energy can be gently absorbed and relaxed, the hydraulic cushion operating region where the hydraulic cushion operates covers a part of the normal stroke region. For this reason, it is necessary to reduce the damping force of the shock absorber when the hydraulic cushion operates, but this is difficult.

More specifically, since the inner circumference of the case and the outer circumference of the ring are in sliding contact with each other during the operation of the hydraulic cushion, a frictional force is generated between the case and the ring. Therefore, when the hydraulic cushion is operated, the frictional force is superposed even in the low speed range, and the damping force of the shock absorber in the low speed range is increased. Further, in order to reduce the secondary damping force in the low speed range during the operation of the hydraulic cushion, it is preferable to increase the flow passage area of the throttle passage. However, the flow passage area of the throttle passage is constant, and if the flow passage area is made sufficiently large, the secondary damping force in the high speed region becomes insufficient. Therefore, the flow passage area of the throttle passage cannot be increased sufficiently, and it is difficult to reduce the secondary damping force in the low speed region.

For these reasons, it is difficult for the conventional shock absorber to reduce the damping force in the low speed range and increase the damping force in the high speed range during the operation of the hydraulic cushion. Further, if the impact energy is gently absorbed and relaxed, the damping force in the low speed range during the operation of the hydraulic cushion becomes excessive and the riding comfort of the vehicle is deteriorated. Further, if the damping force in the low speed range during the operation of the hydraulic cushion is reduced, the damping force in the high speed range is insufficient and the impact energy cannot be sufficiently absorbed, which also leads to deterioration of the riding comfort of the vehicle.

The present invention reduces the damping force when the shock absorber stroke speed is in the low speed range and reduces the damping force in the high speed range even if the shock energy at the time of maximum extension or contraction can be gently absorbed and relaxed. An object of the present invention is to provide a shock absorber that can be made large and that can improve the ride comfort of the vehicle when the shock absorber is mounted on the vehicle.

According to an aspect of the present invention, there is provided a shock absorber, which is a case part, a ring member insertable into the case part, and a throttle passage formed between the ring member and the case part and communicating the inside and outside of the case part. And a back pressure chamber that is formed on the inner circumference of the ring member and communicates with the inside of the case portion, and the ring member is configured to be capable of expanding the diameter by receiving the pressure of the back pressure chamber.

FIG. 1 is a vertical sectional view of a shock absorber according to an embodiment of the present invention. FIG. 2A is an enlarged view of the case part when the ring member of the shock absorber according to the embodiment of the present invention is inserted in the case part and the stroke speed on the extension side of the shock absorber is zero or in the low speed range. FIG. 2B is a sectional view taken along line IIB-IIB of FIG. 2A. FIG. 3A is an enlarged view of the case part when the ring member of the shock absorber according to the embodiment of the present invention is inserted in the case part and the stroke speed on the extension side of the shock absorber is in the high speed range. It is the longitudinal cross-sectional view shown. 3B is a sectional view taken along line IIIB-IIIB of FIG. 3A. FIG. 4A is a vertical cross-sectional view showing an enlarged case portion in a case where the ring member of the shock absorber according to the embodiment of the present invention is inserted into the case portion and the shock absorber strokes toward the contraction side. Is. 4B is a sectional view taken along the line IVB-IVB in FIG. 4A. FIG. 5 is a front view showing a first modified example of the ring member in the shock absorber according to the embodiment of the present invention. FIG. 6A is an enlarged front view of the ring member in the shock absorber according to the embodiment of the present invention. FIG. 6B is a front view showing a second modified example of the ring member in the shock absorber according to the embodiment of the present invention. FIG. 6C is a front view showing a third modified example of the ring member in the shock absorber according to the embodiment of the present invention. FIG. 7: is a longitudinal cross-sectional view which shows the 1st modification of the case part in the shock absorber which concerns on embodiment of this invention, and showed a part of shock absorber provided with the case part which concerns on the said modification. FIG. 8 is a vertical cross-sectional view showing a modified example of the mounting position of the hydraulic cushion in the shock absorber according to the embodiment of the present invention, and showing a part of the shock absorber according to the modified example.

Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals allotted throughout the several figures refer to the same or corresponding parts.

As shown in FIG. 1, the shock absorber D according to the embodiment of the present invention is an upright double-cylinder shock absorber and is mounted on a vehicle such as an automobile. Hereinafter, unless otherwise specified, the upper and lower sides of the shock absorber D according to the present embodiment attached to the vehicle are simply referred to as “upper” and “lower” of the shock absorber D.

The shock absorber D includes a cylinder 1, an outer cylinder 10 provided on the outer periphery of the cylinder 1, a piston 2 slidably inserted into the cylinder 1, a lower end connected to the piston 2, and an upper end outside the cylinder 1. A protruding piston rod (rod) 3, an annular rod guide 11 that slidably supports the piston rod 3 to close the upper end openings of the cylinder 1 and the outer cylinder 10, and a bottom cap 12 that closes the lower end opening of the outer cylinder 10. And a valve case 4 sandwiched and fixed between the bottom cap 12 and the lower end of the cylinder 1, and a hydraulic cushion C1 provided between the piston 2 and the rod guide 11.

Although not shown, brackets for connecting to the vehicle are attached to the upper end of the piston rod 3 protruding to the outside of the cylinder 1 and the lower end of the bottom cap 12, respectively. With these brackets, the piston rod 3 is connected to the vehicle body and the cylinder 1 is connected to the axle. Therefore, when the vehicle runs on a bumpy road surface and the wheels vibrate up and down with respect to the vehicle body, the piston rod 3 moves in and out of the cylinder 1, and the shock absorber D expands and contracts.

The inside of the cylinder 1 is partitioned by the piston 2 into an expansion side chamber R1 and a compression side chamber R2. The expansion side chamber R1 and the compression side chamber R2 are filled with a liquid such as hydraulic oil. The expansion side chamber R1 is one of the two chambers partitioned by the piston 2 in the cylinder 1 and compressed by the piston 2 when the shock absorber D extends. The pressure side chamber R2 is a chamber that is compressed by the piston 2 when the shock absorber D contracts, of the above two chambers. In the present embodiment, the shock absorber D is a single rod type, and the piston rod 3 penetrates only the extension side chamber R1 and projects to the outside of the cylinder 1.

A rod guide 11 is fitted to the upper end of the cylinder 1. An annular bush 13 is fitted on the inner circumference of the rod guide 11. The rod guide 11 slidably supports the piston rod 3 via the bush 13. A seal member 14 is laminated on the rod guide 11. The seal member 14 includes a lip portion 14a that is in sliding contact with the outer periphery of the piston rod 3 to prevent the liquid in the cylinder 1 from leaking to the outside and prevent foreign substances outside the cylinder 1 from entering the cylinder 1. To do.

The expansion side chamber R1 and the compression side chamber R2 in the cylinder 1 communicate with each other through an expansion side passage 2a formed in the piston 2 and a compression side passage 2b. On the pressure side chamber R2 side of the piston 2, an expansion side valve 20 that opens and closes the outlet of the expansion side passage 2a is stacked. The expansion-side valve 20 is an expansion-side damping element, which resists the flow of the liquid flowing from the expansion-side chamber R1 to the compression-side chamber R2 through the expansion-side passage 2a and blocks the reverse flow. A pressure side valve 21 that opens and closes the outlet of the pressure side passage 2b is stacked on the expansion side chamber R1 side of the piston 2. The pressure side valve 21 is a check valve, and allows the flow of the liquid from the pressure side chamber R2 to the expansion side chamber R1 through the pressure side passage 2b and blocks the reverse flow.

A liquid storage chamber R3 is formed between the cylinder 1 and the outer cylinder 10. A liquid is stored in the liquid storage chamber R3, and gas is sealed above the liquid surface. The rod guide 11 closes the upper end opening of the outer cylinder 10 together with the seal member 14, and prevents the liquid and gas in the outer cylinder 10 from leaking to the outside.

The liquid reservoir chamber R3 communicates with the pressure side chamber R2 via a suction passage 4a and a damping passage 4b formed in the valve case 4 fitted to the lower end of the cylinder 1. On the pressure side chamber R2 side of the valve case 4, a suction valve 40 that opens and closes the outlet of the suction passage 4a is stacked. The suction valve 40 is a check valve that allows the flow of the liquid from the liquid storage chamber R3 to the pressure side chamber R2 through the suction passage 4a and blocks the reverse flow. A damping valve 41 that closes the outlet of the damping passage 4b in an openable and closable manner is stacked on the liquid storage chamber R3 side (lower side in FIG. 1) of the valve case 4. The damping valve 41 is a compression-side damping element that provides resistance to the flow of the liquid from the compression-side chamber R2 to the liquid reservoir R3 through the damping passage 4b, and blocks the reverse flow.

According to the above configuration, when the shock absorber D in which the piston rod 3 moves out of the cylinder 1 extends, the piston 2 moves upward in the cylinder 1 to compress the extension side chamber R1. Then, the liquid in the expansion side chamber R1 opens the expansion side valve 20 and moves to the compression side chamber R2 through the expansion side passage 2a. Further, when the shock absorber D extends, the suction valve 40 is opened, and the liquid corresponding to the piston rod volume withdrawn from the cylinder 1 is supplied from the liquid reservoir chamber R3 to the pressure side chamber R2 through the suction passage 4a. The expansion side valve 20 provides resistance to the flow of the liquid passing through the expansion side passage 2a. Therefore, when the shock absorber D extends, the pressure in the expansion side chamber R1 increases, and the shock absorber D exerts a main expansion side damping force that suppresses the expansion operation.

Conversely, when the shock absorber D in which the piston rod 3 enters the cylinder 1 contracts, the piston 2 moves downward in the cylinder 1 and compresses the pressure side chamber R2. Then, the liquid in the pressure side chamber R2 opens the pressure side valve 21 and moves to the expansion side chamber R1 through the pressure side passage 2b. Further, when the shock absorber D contracts, the liquid of the piston rod volume that has entered the cylinder 1 opens the damping valve 41, and the liquid of the pressure side chamber R2 is discharged to the liquid reservoir R3 through the damping passage 4b. The damping valve 41 provides resistance to the flow of the liquid passing through the damping passage 4b. Therefore, when the shock absorber D contracts, the pressure in the cylinder 1 rises, and the shock absorber D exerts a main compression side damping force for suppressing the contraction operation.

As described above, in the present embodiment, the expansion valve 20 is an expansion side damping element for exerting the expansion side damping force, and the damping valve 41 is a compression side damping element for exerting the compression side damping force. Since the extension side and compression side damping elements are configured as one-way passages, the extension side damping force and the compression side damping force can be set individually. However, the structure of the damping element is not limited to this. For example, the compression valve 21 may function as a compression damping element. Alternatively, the piston 2 may be provided with an orifice that allows bidirectional flow, and the orifice may function as a damping element commonly used for expansion.

In addition, in the present embodiment, the shock absorber D is set to a single rod type, and the volume of the piston rod 3 that moves in and out of the cylinder 1 can be compensated by the liquid reservoir R3. Further, in the present embodiment, the shock absorber D is set in an upright/multi-cylinder type, and forms a liquid storage chamber R3 between the cylinder 1 and the outer cylinder 10. That is, the cylinder 1 and the outer cylinder 10 constitute a volume compensation reservoir. However, the form of the shock absorber D is not limited to this, and can be changed appropriately.

For example, the outer cylinder 10 may be eliminated and a reservoir in which the liquid storage chamber R3 is formed may be provided separately from the cylinder 1. Further, an inflatable and expandable air chamber may be formed in the cylinder 1, and the volume of the piston rod 3 may be compensated in the air chamber. In this case, the shock absorber D can be a single cylinder type and an inverted type. In this way, when the shock absorber D is inverted, the shock absorber D shown in FIG. 1 is turned upside down. Further, the shock absorber D may be of a double rod type by projecting the piston rod 3 from both sides of the piston 2 to the outside of the cylinder 1.

In the present embodiment, a hydraulic cushion C1 is provided between the piston 2 and the rod guide 11. The hydraulic cushion C1 includes a case portion 5 provided inside the upper portion of the cylinder 1, a ring member 6 provided on the outer periphery of the piston rod 3 and insertable into the case portion 5, and the ring member 6 attached to the piston rod 3. The holder 7 to be attached and the throttle passage 61, which is formed between the ring member 6 and the case portion 5 in a state where the ring member 6 is inserted into the case portion 5, communicates the inside and the outside of the case portion 5, and the inside of the ring member 6. The back pressure chamber P is formed around the circumference and communicates with the inside of the case portion 5. Hereinafter, the configuration of the hydraulic cushion C1 will be described in detail.

The case portion 5 has a tubular shape and is held by being press-fitted into the rod guide 11. More specifically, the rod guide 11 has a base portion 11a whose outer circumference reaches the outer cylinder 10, and a first reduced diameter portion 11b coaxially connected to the lower side of the base portion 11a and having an outer diameter smaller than the outer diameter of the base portion 11a. A second reduced diameter portion 11c coaxially connected to the lower side of the first reduced diameter portion 11b and having an outer diameter smaller than the outer diameter of the first reduced diameter portion 11b. The upper end of the cylinder 1 is fitted to the outer circumference of the first reduced diameter portion 11b, and the upper end of the case portion 5 is press-fitted to the outer circumference of the second reduced diameter portion 11c. By the press fitting, the case portion 5 is held in a state of being suspended by the rod guide 11.

A portion of the cylinder 1 having an inner diameter into which the piston 2 can be slidably inserted is referred to as a cylinder body 1a. The inner diameter of the portion 1b into which the case portion 5 is inserted is larger than the inner diameter of the cylinder body 1a. The case portion 5 has an inner diameter smaller than the inner diameter of the cylinder body 1a, and has a tapered portion 5a whose diameter gradually increases toward the lower end.

As shown in FIG. 2B, the ring member 6 is an annular member having a split in the circumferential direction, and is formed in a C shape when viewed in the axial direction. As described above, the term “annular” in the present specification means not only a shape that includes an O-ring that is continuous in the circumferential direction but also a shape that includes a C-ring that has a portion in the circumferential direction.

The ring member 6 has an annular (C-annular in this embodiment) ring body 6a and a plurality of protrusions 6b provided on the inner circumference of the ring body 6a. A gap 60 is formed between both ends of the ring body 6a in the circumferential direction. The ring member 6 is formed of an elastic body having elasticity. Therefore, the ring member 6 is configured to be capable of expanding its diameter, and when the diameter of the ring member 6 is expanded, the ring member 6 tends to return to its original shape due to its elasticity. That is, when the diameter of the ring member 6 is expanded, the ring member 6 exerts an elastic force in the direction of reducing the diameter of itself. More specifically, the ring member 6 is formed of a resin material, and is preferably formed of a fiber reinforced resin in which fibers such as glass fibers and carbon fibers are mixed with the resin material. The fiber reinforced resin is suitable as a material for the ring member 6 because it has relatively high strength and excellent dimensional stability. The material of the ring member 6 is not limited to the resin material.

In the present embodiment, the protrusions 6b are provided with a total of three, that is, both ends in the circumferential direction of the ring body 6a (both sides of the gap 60) and the center in the circumferential direction. All of these protrusions 6b project from the inner circumference of the ring body 6a toward the center of the ring body 6a. The number and arrangement of the protrusions 6b can be changed as appropriate. For example, four or more protrusions 6b may be provided on the inner circumference of the ring body 6a, or the protrusions 6b may be provided at equal intervals along the circumferential direction of the ring body 6a. It is desirable that the plurality of protrusions 6b be arranged so as to sandwich the holder 7 (piston rod 3) from the radial direction. Specifically, the plurality of protrusions 6b are arranged such that the vectors of the forces acting on the holder 7 from the protrusions 6b substantially cancel each other without disposing all the protrusions 6b within an angle range smaller than 180°. Is desirable. According to this, in the ring member 6, only the protrusion 6b contacts the holder 7 (a guide portion 7a described later) and the ring body 6a does not contact the holder 7, so that the back pressure chamber P can be easily formed.

As shown in FIGS. 2A and 2B, the holder 7 includes a cylindrical guide portion 7a, an annular seat portion 7b provided at one end of the guide portion 7a in the axial direction, and the other end of the guide portion 7a in the axial direction. The annular retaining portion 7c is provided. The holder 7 is fixed to the outer circumference of the piston rod 3 such that the seat portion 7b is relatively on the piston 2 side (lower side) and the retaining portion 7c is relatively on the case portion 5 side (upper side).

The holder 7 has an annular claw 7d at the lower end. The holder 7 is fixed and positioned on the piston rod 3 by fitting the claw portion 7d into the annular groove 3a formed along the circumferential direction on the outer circumference of the piston rod 3. However, the method of attaching the holder 7 to the piston rod 3 is not limited to this, and can be changed as appropriate. For example, the holder 7 may be fixed to the outer circumference of the piston rod 3 by press fitting, screwing, welding, bonding, or the like, or may be positioned by using a snap ring or the like.

In the holder 7, the axial length of the guide portion 7a is longer than the axial length of the ring member 6. The ring member 6 is mounted on the outer periphery of the guide portion 7a and between the seat portion 7b and the retaining portion 7c.

The outer diameter of the guide portion 7a is formed to be slightly larger than the inner diameter of the ring member 6 in the unloaded state (in a state where it has become a natural length), and the ring member 6 has a margin for the guide portion 7a. Here, in the present embodiment, the inner diameter of the ring member 6 is the diameter of the circle connecting the tips of the protrusions 6b. The ring member 6 is slightly expanded in diameter while being attached to the outer periphery of the guide portion 7a, and the protrusion 6b is pressed against the outer periphery of the guide portion 7a.

The tightening margin of the ring member 6 is set so as not to hinder the axial movement of the ring member 6 with respect to the guide portion 7a. Therefore, the ring member 6 is movable in the axial direction (up and down) along the guide portion 7a, and rattling is suppressed. Therefore, generation of abnormal noise due to rattling of the ring member 6 is suppressed.

A back pressure chamber P is formed between the outer circumference of the guide portion 7 a and the inner circumference of the ring member 6. The pressure in the back pressure chamber P acts in the direction of expanding the ring member 6. The outer diameter of the ring member 6 attached to the piston rod 3 and not receiving an external force such as the pressure of the back pressure chamber P is slightly smaller than the inner diameter of the case portion 5. Therefore, in a state where no external force acts on the ring member 6 in the attached state (for example, a static state in which the shock absorber D is not operating) and the ring member 6 is inserted into the case portion 5, the case is An annular gap that functions as a throttle passage 61 is formed between the inner periphery of the portion 5 and the outer periphery of the ring member 6.

The throttle passage 61 throttles the flow of the liquid moving inside and outside the case portion 5 partitioned by the ring member 6. As described above, the inner diameter of the cylinder body 1a (FIG. 1) is larger than the inner diameter of the case portion 5. Therefore, in the state where the ring member 6 is not inserted into the case portion 5, the liquid can freely move on the outer periphery of the ring member 6.

Here, in the present specification, the above-mentioned external force acting on the ring member 6 is a force applied to the ring member 6 from the outside of the ring member 6 in the mounted state. That is, for example, as a reaction force of the tightening force when the ring member 6 tightens the guide portion 7a, a force applied to the ring member 6 when the ring member 6 is attached, such as a force that acts on the ring member 6 from the guide portion 7a. Not included. In other words, even when the ring member 6 is attached to the piston rod 3 and the load acts on the ring member 6 and other members due to the elastic force of the ring member 6 itself, It is not considered that the ring member 6 receives an external force. The external force acting on the ring member 6 does not include the initial pressure of the back pressure chamber P (the pressure of the back pressure chamber P when the shock absorber D is in a stationary state). Hereinafter, the state in which the ring member 6 is in the attached state and is not receiving the external force is simply referred to as “state not receiving external force”.

The outer diameter of the seat portion 7b provided at the lower end of the guide portion 7a is the same as or slightly smaller than the outer diameter of the ring member 6 when no external force is applied. The outer diameter of the seat portion 7b is smaller than the outer diameter of the case portion 5 and larger than the inner diameter of the ring body 6a. Therefore, the ring member 6 is seated on the seat portion 7b. When the ring member 6 is seated on the seat portion 7b, the ring body 6a abuts the seat portion 7b to prevent liquid from passing between them.

The seat portion 7b is provided so as to face the inside of the case portion 5 with the ring member 6 interposed therebetween. Therefore, when the ring member 6 enters the case portion 5 together with the holder 7, the liquid in the case portion 5 flows out of the case portion 5 and pushes down the ring member 6 to seat it on the seat portion 7b. Therefore, when the ring member 6 enters the case portion 5, the liquid in the case portion 5 passes through the throttle passage 61 formed on the outer periphery of the ring member 6 or the outer periphery of the abutment gap 60 of the ring member 6. It moves to the outside of the case portion 5 through the side.

Since the outer diameter of the seat portion 7b is the same as or slightly smaller than the outer diameter of the ring member 6 in the state where no external force is applied, the gap formed between the seat portion 7b and the case portion 5 passes through the throttle passage 61. There is no further restriction on the flow of liquid. On the other hand, the liquid that does not pass through the throttle passage 61 but passes through the joint gap 60 and moves to the outside of the case portion 5 is throttled by the gap between the sheet portion 7 b and the case portion 5. Thereby, the flow rate of the liquid passing through the abutment gap 60 is limited, and the pressure inside the case portion 5 can be increased by the resistance when the liquid passes through the throttle passage 61.

The pressure in the case portion 5 is propagated to the back pressure chamber P on the inner circumference of the ring member 6, and the pressure in the back pressure chamber P becomes equal to the pressure in the case portion 5. That is, when the liquid flows through the throttle passage 61 and the pressure in the upstream case portion 5 rises, the pressure in the back pressure chamber P also rises. Further, when the liquid is flowing through the throttle passage 61 in this way, the pressure of the throttle passage 61 communicating with the outside of the case portion 5 becomes lower than the pressure of the back pressure chamber P. Therefore, a pressure difference occurs between the pressure of the back pressure chamber P on the inner peripheral side of the ring member 6 and the pressure of the throttle passage 61 on the outer peripheral side.

Assuming that a force obtained by multiplying the area of the inner circumference of the ring member 6 by the pressure of the back pressure chamber P is an inner circumference load, the inner circumference load biases the ring member 6 in the radial direction. On the other hand, when the force obtained by multiplying the area of the outer periphery of the ring member 6 by the pressure of the throttle passage 61 is taken as the outer peripheral load, the ring member 6 contracts due to this outer peripheral load and the spring load due to the elasticity of the ring member 6 itself. It is biased in the radial direction. When the ring member 6 is not receiving an external force, the load on the outer peripheral side and the load on the inner peripheral side become zero, so that the elasticity of the ring member 6 causes the protrusion 6b to come into contact with the outer periphery of the guide portion 7a with a predetermined tightening force.

According to the above configuration, when the ring member 6 enters the case portion 5 and the liquid flows downward from the inside of the case portion 5 to the outside (toward the extension side chamber R1) through the throttle passage 61, the shock absorber D When the stroke speed is low, the flow rate of the liquid flowing through the throttle passage 61 is small. Therefore, the liquid flows through the throttle passage 61 with relatively little resistance. In this case, the pressure difference between the inside and the outside of the case portion 5 with the ring member 6 as a boundary does not increase, and the pressure difference between the inner peripheral side and the outer peripheral side of the ring member 6 does not increase.

Therefore, when the ring member 6 enters the case portion 5 and the stroke speed of the shock absorber D is in the low speed range, the inner peripheral load acting on the ring member 6 causes the elasticity of the ring member 6 itself. Is kept smaller than the combined load of the spring load and the outer peripheral side load. Therefore, as shown in FIGS. 2A and 2B, the throttle passage 61 is maintained in the open state.

On the other hand, when the ring member 6 enters the case portion 5 and the liquid flows through the throttle passage 61 from the inside of the case portion 5 to the outside, when the stroke speed of the shock absorber D increases, the flow rate of the liquid flowing through the throttle passage 61 increases. Will increase. Therefore, the resistance when the liquid flows through the throttle passage 61 increases. Then, the pressure difference between the inside and the outside of the case portion 5 with the ring member 6 as a boundary increases, and the pressure difference between the inner peripheral side and the outer peripheral side of the ring member 6 increases.

Therefore, when the ring member 6 enters the case portion 5 and the stroke speed of the shock absorber D is in the high speed range, the inner peripheral load acting on the ring member 6 causes the elasticity of the ring member 6 itself. It exceeds the combined load of the spring load and the outer peripheral side load. As a result, the diameter of the ring member 6 increases, and the area of the throttle passage 61 decreases as the diameter of the ring member 6 increases. Then, as shown in FIGS. 3A and 3B, when the diameter of the ring member 6 is expanded until the outer circumference of the ring member 6 contacts the inner circumference of the case portion 5, the throttle member 61 is closed by the ring member 6.

In this way, when the throttle passage 61 is closed by the ring member 6, the throttle passage is formed in a portion where the gap formed between the seat portion 7b and the case portion 5 and the abutment gap 60 of the ring member 6 overlap in the axial direction. A throttle hole 62 having a larger degree of throttle (smaller flow passage area) than 61 is formed. That is, the outer diameter of the seat portion 7b does not further restrict the flow of the liquid passing through the throttle passage 61 in the gap between the seat portion 7b and the case portion 5, and the inner diameter of the ring body 6a when the throttle passage 61 is closed. The diameter is larger than that of the narrowing passage 61 and is larger than the narrowing passage 61.

On the other hand, when the ring member 6 in the case unit 5 withdraws from the case unit 5 together with the holder 7, the liquid outside the case unit 5 flows into the case unit 5, and as shown in FIGS. 4A and 4B, the ring member 6 is pushed up to separate from the seat portion 7b. Therefore, the liquid passes through the gap formed between the ring member 6 and the seat portion 7b, the back pressure chamber P, and the gap formed between the ring member 6 and the retaining portion 7c in this order and moves into the case portion 5. it can.

That is, when the ring member 6 exits from the case part 5, the back pressure chamber P becomes a part of the return passage 63 for supplying the liquid from the outside to the inside of the case part 5. Liquid can pass through the return passage 63 with relatively little resistance. Therefore, when the ring member 6 that allows the return passage 63 to be communicated withdraws, the differential pressure between the inside and outside of the case portion 5 with the ring member 6 as a boundary does not increase, and the difference between the inner peripheral side and the outer peripheral side of the ring member 6 does not increase. The pressure does not increase. Therefore, when the ring member 6 withdraws from the case portion 5, the back pressure does not rise, the back pressure chamber P does not perform its function, and the ring member 6 is maintained in the state in which the throttle passage 61 is opened. It

That is, when the ring member 6 withdraws from the case portion 5, the liquid outside the case portion 5 is returned to the return passage 63, the throttle passage 61 formed on the outer periphery of the ring member 6, or the outer peripheral side of the abutment gap 60 of the ring member 6. To move into the case portion 5.

The shape of the retaining portion 7c provided on the upper end of the guide portion 7a is tapered so that the outer diameter gradually decreases toward the lower end. The outer diameter of the lower end, which is the minimum inner diameter in the retaining portion 7c, is larger than the inner diameter of the ring member 6 in the state where no external force is applied and smaller than the inner diameter of the ring body 6a. Therefore, when the ring member 6 moves upward with respect to the holder 7 and the protrusion 6b comes into contact with the lower end of the retaining portion 7c, further upward movement of the ring member 6 is restricted. Further, even when the ring member 6 is in contact with the retaining portion 7c, a gap is formed between the ring body 6a and the retaining portion 7c, and the liquid can pass through the gap. Therefore, the retaining portion 7c does not block the communication of the return passage 63.

Further, when the ring member 6 is outside the case portion 5, since the gap formed between the ring member 6 and the cylinder 1 is wide, the risk of the ring member 6 coming off the holder 7 at that portion increases, but it does not come off. Since the outer diameter of the upper end of the portion 7c is increased, the ring member 6 can be reliably prevented from coming off the holder 7. Specifically, the outer diameter of the upper end portion that has the maximum outer diameter in the retaining portion 7c may be the same as or slightly smaller than the outer diameter of the seat portion 7b.

In the present embodiment, an annular cushion member 8 is provided on the outer circumference of the piston rod 3 and above the retaining portion 7c. The cushion member 8 is formed of an elastic body such as rubber and is compressed between the retaining portion 7c and the rod guide 11 when the shock absorber D is most extended, and exerts an elastic force commensurate with the amount of compression. The cushion member 8 may be formed of a material other than rubber, such as a coil spring, and the cushion member 8 may be omitted.

The operation of the shock absorber D according to this embodiment will be described below.

When the shock absorber D extends, the shock absorber D exerts a main expansion-side damping force (primary damping force) due to the resistance of the expansion-side valve 20 that is the expansion-side damping element. Then, when the stroke amount of the shock absorber D toward the extension side becomes larger than a predetermined value, the ring member 6 enters the case portion 5, and resistance is given to the flow of the liquid from the inside of the case portion 5 to the outside. Therefore, the secondary damping force by the hydraulic cushion C1 due to the resistance is added to the main extension side damping force.

More specifically, when the ring member 6 enters the case portion 5 and the stroke speed toward the extension side of the shock absorber D is in the low speed range, as shown in FIGS. 2A and 2B, the ring The throttle passage 61 formed between the member 6 and the case portion 5 is kept open. Therefore, the liquid in the case portion 5 can move to the outside of the case portion 5 through the throttle passage 61. In the low speed region, the liquid flows through the throttle passage 61 with relatively little resistance, so the differential pressure between the inside and outside of the case portion 5 does not increase, and the secondary damping force of the hydraulic cushion C1 decreases.

Further, when the throttle passage 61 is open, a gap is formed between the ring member 6 and the case portion 5, and the ring member 6 and the case portion 5 do not come into sliding contact with each other. Therefore, a frictional force is generated between the ring member 6 and the case portion 5, and the frictional force is superimposed to increase the damping force of the shock absorber D, whereby smooth expansion and contraction movement of the shock absorber D in the low speed range is obstructed. Can be prevented. Further, as described above, when the stroke speed toward the extension side of the shock absorber D is in the high speed range, the throttle passage 61 is closed. Therefore, even if the degree of throttling of the throttle passage 61 is reduced (the flow passage area is increased), it does not hinder the increase of the secondary damping force in the high speed region. Therefore, the flow passage area of the throttle passage 61 can be sufficiently increased, and the secondary damping force in the low speed region can be reduced.

When the ring member 6 enters the case portion 5 and the stroke speed of the shock absorber D toward the extension side is in the high speed range, the ring member 6 expands as shown in FIGS. 3A and 3B. The diameter of the throttle passage 61 is closed. Then, since the throttle hole 62 is formed by utilizing the gap 60 of the ring member 6, the liquid in the case portion 5 moves to the outside of the case portion 5 through the throttle hole 62. In the high speed range, the throttle hole 62 provides resistance to the flow of liquid, so that the differential pressure between the inside and outside of the case portion 5 increases, and the secondary damping force of the hydraulic cushion C1 increases.

Further, as described above, the throttle hole 62 is a passage having a greater degree of throttle than the throttle passage 61. For this reason, when the throttle passage 61 is closed due to the increase in stroke speed, the damping coefficient of the hydraulic cushion C1 (the ratio of the damping force change amount to the stroke speed change amount) increases at the boundary. Therefore, the secondary damping force by the hydraulic cushion C1 in the high speed range can be increased, and the large secondary damping force can be applied to the main extension side damping force. Therefore, the expansion side damping force of the shock absorber D as a whole becomes large, and the impact energy can be absorbed and relaxed by the large expansion side damping force.

Further, in the present embodiment, the case portion 5 is provided with the taper portion 5a, and the degree of throttling of the throttle passage 61 increases in the taper portion 5a as the stroke amount toward the extension side increases. Therefore, as the stroke amount to the extension side increases, the differential pressure between the inside and outside of the case portion 5 tends to increase, and the throttle passage 61 tends to close. When the throttle passage 61 is closed, the degree of throttling of the throttle hole 62 increases as the stroke amount to the extension side increases. Therefore, the damping coefficient of the hydraulic cushion C1 in the high speed region increases as the stroke amount to the extension side increases.

That is, when the shock absorber D strokes toward the extension side, the hydraulic cushion C1 operates when the ring member 6 enters the case portion 5 as a boundary and exerts a secondary damping force. A strong damping force can be added to the main extension side damping force. The magnitude of the secondary damping force of the hydraulic cushion C1 changes depending on the stroke speed (piston speed) of the shock absorber D, and is large in the high speed range and small in the low speed range. Further, the large secondary damping force in the high speed range changes in size depending on the stroke amount (piston position) of the shock absorber D, and increases as the stroke amount to the extension side increases.

On the contrary, when the shock absorber D contracts, the shock absorber D exerts the main compression side damping force due to the resistance of the damping valve 41 which is the compression side damping element. Then, when the shock absorber D strokes toward the contraction side in a stroke region in which the stroke amount of the shock absorber D toward the expansion side is larger than the predetermined value, the ring member 6 in the case portion 5 retracts from the case portion 5. In this case, the liquid outside the case portion 5 flows into the case portion 5, and the ring member 6 is separated from the seat portion 7b to allow the return passage 63 to communicate with each other, as shown in FIGS. 4A and 4B.

In this way, when the ring member 6 is withdrawn from the case portion 5, the throttle passage 61 formed between the ring member 6 and the case portion 5 is maintained in the open state. Therefore, the liquid flowing from the outer side to the inner side of the case portion 5 can pass through the throttle passage 61 formed on the outer periphery of the ring member 6, the outer peripheral side of the abutment gap 60 of the ring member 6, and the return passage 63. Further, when the ring member 6 is retracted from the case portion 5, even if the ring member 6 moves until it comes into contact with the retaining portion 7c, the retaining portion 7c does not block the communication of the return passage 63 and the return passage 63 does not block. The liquid can be moved through 63 with relatively little resistance.

Therefore, when the shock absorber D strokes toward the contracting side, the differential pressure inside and outside the case portion 5 becomes substantially zero, and the secondary damping force by the hydraulic cushion C1 cannot be obtained. Further, when the amount of stroke of the shock absorber D toward the extension side is less than the predetermined amount and the ring member 6 moves outside the case portion 5, the liquid can freely move on the outer peripheral side of the ring member 6. Therefore, in this case, the secondary damping force by the hydraulic cushion C1 cannot be obtained regardless of the stroke direction of the shock absorber D.

That is, in the present embodiment, the hydraulic cushion C1 operates to exert the secondary damping force when the stroke amount of the shock absorber D toward the extension side is equal to or larger than the predetermined stroke. Only when the stroke is toward the extension side. Even when the hydraulic cushion C1 operates in this way, when the stroke speed of the shock absorber D is in the low speed range, the secondary cushion added to the main damping force by the hydraulic cushion C1 is secondary. The damping force can be reduced.

Therefore, in the case where the axial length of the case portion 5 is increased so that the shock energy of the shock absorber D at the time of the maximum extension can be gently absorbed and relaxed, the hydraulic cushion is provided in a part of the normal stroke region of the shock absorber D. Even when the operating range in which C1 operates is exceeded, the damping force does not become excessive when the stroke speed of the shock absorber D is in the low speed range. As a result, the riding comfort of the vehicle can be improved.

Further, when the stroke speed of the shock absorber D reaches a high speed range such as when the vehicle travels on a rough road, the shock energy at the time of the maximum expansion of the shock absorber D becomes large. On the other hand, when the hydraulic cushion C1 operates in the high speed range, the diameter of the ring member 6 is expanded and the throttle passage 61 is closed, so the secondary cushion added to the main extension side damping force by the hydraulic cushion C1. The damping force can be increased. Therefore, the expansion side damping force of the shock absorber D as a whole becomes large, and a large impact energy can be absorbed and relaxed by the large damping force.

Further, the case portion 5 is provided with the taper portion 5a, and the damping coefficient of the hydraulic cushion C1 increases depending on the stroke amount of the shock absorber D. Therefore, even if the secondary damping force immediately after the operation of the hydraulic cushion C1 is reduced, the secondary damping force near the stroke end can be increased. Therefore, the shock energy at the time of the maximum extension of the shock absorber D can be reliably absorbed and relaxed, and the sudden change of the damping force at the boundary of the operation of the hydraulic cushion C1 can be suppressed to further improve the riding comfort of the vehicle.

Hereinafter, the function and effect of the shock absorber D according to the present embodiment will be described.

The shock absorber D according to the present embodiment is attached to a cylindrical case portion 5 provided at an end portion of the cylinder 1 and a piston rod 3 which is movably inserted in the cylinder 1 in the axial direction. And an insertable ring member 6. When the ring member 6 is not receiving an external force, an annular gap formed between the ring member 6 and the case portion 5 forms a throttle passage 61 that communicates the inside and the outside of the case portion 5. A back pressure chamber P communicating with the inside of the case portion 5 is formed on the inner periphery of the ring member 6. The ring member 6 has elasticity and can be expanded in diameter by the pressure of the back pressure chamber P.

More specifically, in the shock absorber D, the throttle passage 61 has a flow passage area that decreases as the diameter of the ring member 6 increases. The ring member 6 is configured to be capable of expanding its diameter by the pressure of the back pressure chamber P until it comes into contact with the inner circumference of the case portion 5.

According to the above configuration, when the stroke speed of the shock absorber D is in the low speed range, the pressure loss due to the throttle passage 61 does not increase, so the force for expanding the diameter of the ring member 6 due to the pressure in the back pressure chamber P does not increase. Therefore, the ring member 6 and the case portion 5 do not come into contact with each other. Therefore, even when the hydraulic cushion C1 operates, the expansion and contraction operation of the shock absorber D is not hindered by the frictional force generated between the ring member 6 and the case portion 5 in the low speed range. Further, in the throttle passage 61 formed between the ring member 6 and the case portion 5 in the low speed region, the force for expanding the diameter of the ring member 6 by the pressure of the back pressure chamber P is large when the stroke speed is high and at a high speed. Therefore, when the ring member 6 is expanded in diameter under the pressure of the back pressure chamber P, it is closed. Therefore, even if the flow passage area of the throttle passage 61 in which the liquid flows in the low speed region is increased, the secondary damping force in the high speed region does not become insufficient.

Therefore, even if the ring member 6 enters the case portion 5 and the hydraulic cushion C1 operates, when the stroke speed of the shock absorber D is in the low speed range, the secondary cushion by the hydraulic cushion C1 is used. The damping force can be reduced. As a result, even if the axial length of the case portion 5 is increased so that the impact energy can be gently absorbed and relaxed, the damping force is reduced when the stroke speed of the shock absorber D is in the low speed range, and the high speed range is reduced. The damping force in the case of can be increased. Therefore, the ride comfort of the vehicle can be improved.

In addition, in the present embodiment, the ring member 6 is attached to the piston rod 3 in a state with a tight margin. In other words, the ring member 6 is attached to the piston rod 3 in a state where the diameter is expanded from the natural state (no load state). Therefore, rattling of the ring member 6 in the axial direction and the radial direction (for example, the left-right direction in FIG. 1, the front-back direction) can be suppressed, and the generation of abnormal noise can be suppressed. Further, in the present embodiment, the ring member 6 includes an annular ring body 6a and a plurality of protrusions 6b provided on the inner circumference of the ring body 6a. Therefore, it is easy to form the back pressure chamber P on the inner circumference of the ring member 6 and to allow the ring member 6 to have the interference. In addition, in this embodiment, since the three protrusions 6b are provided, it is possible to prevent the ring member 6 from being displaced in the radial direction with respect to the guide portion 7a.

The number and arrangement of the protrusions 6b can be changed as appropriate. Further, the ring member 6 may be attached to the piston rod 3 without any interference. For example, a ring member is loosely fitted on the outer periphery of the guide portion 7a, and a spring such as a wave washer is interposed between the ring member and the retaining portion 7c, and the ring member is attached to the seat portion 7b. You may encourage. In this case, rattling in the axial direction of the ring member can be suppressed. In addition, the same effect can be obtained by using a ring washer 106A formed in a spring washer shape as shown in FIG. 5 and interposing the ring member 106A between the seat portion 7b and the retaining portion 7c. ..

More specifically, the ring member 106A has a part in the circumferential direction and is formed in a C shape when viewed in the axial direction, and one end 6c and the other end 6d in the circumferential direction are axial with respect to each other in an unloaded state. Is off. That is, the ring member 106A is formed in a spiral shape with respect to the central axis. When the ring member 106A is used instead of the ring member 6, for example, one end 6c of the ring member 106A is arranged toward the retaining portion 7c and the other end 6d is arranged toward the seat portion 7b. In this case, when the ring member 106A enters into the case portion 5, one end 6c and the other end 6d of the ring member 106A are seated on the seat portion 7b to cut off the communication of the return passage 63, thereby making the back pressure chamber P function. .. On the other hand, when the ring member 106A retracts from the case portion 5 and when the ring member 106A is not receiving an external force, the elasticity of the ring member 106A causes the one end 6c of the ring member 106A to move away from the seat portion 7b. A gap is formed between them to allow the return passage 63 to communicate with each other.

Further, in the present embodiment, the ring member 6 has a split in a part in the circumferential direction, and is formed in a C-shape when viewed in the axial direction. Therefore, the ring member 6 can be easily attached and the diameter of the ring member 6 can be easily expanded. Therefore, opening and closing of the throttle passage 61 using the ring member 6 can be easily realized. In addition, by utilizing the abutment gap 60 formed by splitting the ring member 6, it is possible to form the throttle hole 62 that communicates the inside and outside of the case portion 5 even when the throttle passage 61 is closed. Of course, the effect can be obtained by using the ring member 106A shown in FIG.

Further, in the present embodiment, the split of the ring member 6 is linearly formed in parallel to the axial direction as shown in FIG. 6A, but the above effect can be obtained regardless of the split shape. .. For example, the split of the ring member 6 may be formed obliquely with respect to the central axis as in the ring member 106B shown in FIG. 6B, and has a stepped shape as in the ring member 106C shown in FIG. 6C. Good.

More specifically, the ring member 106C shown in FIG. 6C includes a first protrusion 6e extending in the circumferential direction from one upper end in the circumferential direction of the ring body 6a and a lower end in the other circumferential direction from the lower end of the ring body 6a in the circumferential direction. The extended 2nd protrusion part 6f is provided. The first protrusion 6e and the second protrusion 6f are in contact with each other vertically in FIG. 6C. Abutment gaps 64 and 65 are formed between the tip of the first protrusion 6e and the ring body 6a, and between the tip of the second protrusion 6f and the ring body 6a, respectively.

When the ring member 106C is used instead of the ring member 6, and the first protrusion 6e is arranged toward the retaining portion 7c and the second protrusion 6f is arranged toward the seat 7b, the diameter of the ring member 106C is increased. Then, when the throttle passage 61 is closed, the throttle hole 62 is formed using the abutment gap 65. The abutment gap 65 is formed so as to give a resistance smaller than the resistance given to the flow of the liquid by the throttle hole 62 (the degree of throttling is smaller than that of the throttle hole 62) when the throttle passage 61 is closed. .. As a result, the liquid flowing out of the case portion 5 is given a resistance corresponding to the throttle hole 62.

Since the ring member 106C is suitable for reducing the throttle hole 62, it is effective when it is desired to increase the secondary damping force in the high speed region by the hydraulic cushion C1. However, when the flow passage area of the throttle hole 62 is insufficient, the notch may be provided in the ring member 106C or the seat portion 7b. This is the same even when the other ring members 6, 106A, 106B are used.

Further, the shape of the ring member 6 is not limited to the C ring shape, and may be formed into a solid O ring shape. When such an O-shaped ring member is used, the inside of the case portion 5 can be oil-locked when the ring member that has entered the case portion 5 expands in diameter and closes the throttle passage 61. The ring member can be changed regardless of the number and position of the protrusions 6b and the presence or absence of the interference.

Further, in this embodiment, the ring member 6 is attached to the piston rod 3 via the annular holder 7. The holder 7 has a guide portion 7a whose axial length is longer than the axial length of the ring member 6 and on which the ring member 6 is mounted, and the back pressure chamber P is located between the ring member 6 and the guide portion 7a. Is formed. According to this structure, the ring member 6 can be easily attached to the piston rod 3. The method of attaching the ring member 6 can be changed as appropriate, and the ring member 6 may be attached directly to the piston rod 3.

In addition, in the present embodiment, the holder 7 has an annular seat portion 7b on which the ring member 6 can be seated and detached, at the lower end (end portion on the side opposite the case portion) of the guide portion 7a. When the ring member 6 is separated from the seat portion 7b, the back pressure chamber P allows the inflow of the liquid from the outside to the inside of the case portion 5 together with the gap formed between the ring member 6 and the seat portion 7b. It constitutes the return passage 63. Therefore, it is possible to suppress the hydraulic cushion C1 from exerting a secondary damping force when the ring member 6 is withdrawn from the case portion 5.

Further, in the present embodiment, the holder 7 has an annular retaining portion 7c at the upper end of the guide portion 7a (end portion on the case portion side). The outer diameter of the retaining portion 7c is gradually reduced toward the guide portion 7a. The outer diameter of the lower end of the retaining portion 7c (the end portion on the guide portion side) is smaller than the inner diameter of the ring body 6a when the ring member 6 is not receiving an external force. Therefore, the retaining member 7c can reliably prevent the ring member 6 from retaining, and the retaining member 7c can prevent the return passage 63 from being blocked. However, a notch is provided in the opposing portion of the retaining portion 7c and the ring member 6, and the gap formed between the retaining portion 7c and the ring member 6 by the notch prevents the retaining portion 7c from blocking the return passage 63. You may.

Further, since the seat portion 7b and the retaining portion 7c are provided on the holder 7, it is easy to attach them to the piston rod 3. However, the seat portion 7b and the retaining portion 7c may be individually attached to the piston rod 3, or may be integrally formed with the piston rod 3. Then, the configuration of the holder 7 and the attachment method of the ring member 6 can be changed regardless of the configuration of the ring member.

Further, in the present embodiment, the case portion 5 is provided with the taper portion 5a whose inner diameter gradually increases toward the insertion side end (lower end in FIG. 1) of the ring member 6. Therefore, the secondary damping force can be increased and the damping force of the shock absorber D can be increased as the amount of the ring member 6 entering the case portion 5 increases. Further, in the present embodiment, the diameter of the end portion of the cylinder 1 is expanded, and the case portion 5 is accommodated in the expanded diameter portion 1b. Therefore, even if the taper portion 5a is formed on the case portion 5, the outer diameter of the taper portion 5a can be increased together with the inner diameter. That is, since the wall thickness of the tapered portion 5a can be secured, it is easy to form the tapered portion 5a on the case portion 5.

However, the wall thickness of the case portion 5 may be reduced toward the lower end to form the tapered portion 5a. In this case, since it is not necessary to expand the diameter of the portion 1b of the cylinder 1 that accommodates the case portion 5, and the inner diameter of the cylinder 1 can be made constant, the cylinder 1 can be easily formed. Further, the tapered portion 5a may be omitted and the inner diameter of the case portion 5 may be made constant in the axial direction, or the entire case portion 5 may be the tapered portion 5a.

Further, in the case where the cylinder 1 and the case portion 5 are separately formed as in this embodiment, and the case 5 is held by the rod guide 11, the end of the cylinder 1 on the rod guide 11 side (see FIG. Since the piston 2 can be assembled from the middle upper end), the ease of assembly of the shock absorber D can be improved. However, the cylinder 1 and the case portion 5 may be integrally formed, and in this case, the number of parts of the shock absorber D can be reduced.

For example, in the hydraulic cushion C10 shown in FIG. 7, the case portion 5A is integrally formed with the cylinder 1A at the end of the cylinder 1A. In other words, the cylinder 1A of the shock absorber shown in FIG. 7 includes a cylinder body 1a into which the piston 2 is slidably inserted, and a case portion which is connected to one end of the cylinder body 1a and whose inner diameter is smaller than the inner diameter of the cylinder body 1a. 5A and.

Further, in the present embodiment, the case portion 5 is provided on the upper end portion of the cylinder 1. Therefore, when the stroke amount of the shock absorber D toward the extension side exceeds a predetermined amount, the ring member 6 is inserted into the case portion 5 and the hydraulic cushion C1 operates. That is, the hydraulic cushion C1 functions as a rebound cushion that absorbs and relaxes the impact energy when the shock absorber D is extended most. However, the position where the case portion 5 is provided is not limited to this, and the stroke region for operating the hydraulic cushion C1 can be appropriately changed.

For example, like the hydraulic cushion C2 shown in FIG. 8, the case portion 5B may be provided at the lower end portion of the cylinder 1B. In this case, when the stroke amount of the shock absorber toward the contraction side becomes a predetermined amount or more, the ring member 6 is inserted into the case portion 5B, and the hydraulic cushion C2 absorbs and relaxes the shock when the shock absorber is contracted most. Functions as a bound cushion.

More specifically, the hydraulic cushion C2 is provided between the piston 2 and the valve case 4. The case portion 5B of the hydraulic cushion C2 is integrally formed with the cylinder 1B at the lower end portion of the cylinder 1B. The ring member 6 is attached below the piston 2 of the piston rod 3 via the holder 107A.

The holder 107A has the guide portion 7a, the seat portion 7b, and the retaining portion 7c described above, and is arranged with the seat portion 7b on the upper side and the retaining portion 7c on the lower side. Further, the holder 107A has a nut portion 7e connected to the upper side of the seat portion 7b. The holder 107A is fixed to the piston rod 3 by screwing the nut portion 7e onto the outer circumference of the piston rod 3. Further, the holder 107A also serves as a piston nut for connecting the piston 2 to the piston rod 3.

According to the above configuration, when the stroke amount of the shock absorber toward the contracted side becomes equal to or greater than the predetermined amount, the ring member 6 enters the case portion 5B and the hydraulic cushion C2 operates. When the hydraulic cushion C2 is in operation, when the stroke speed of the shock absorber toward the contraction side is in the low speed range, the liquid can pass through the throttle passage 61 with relatively little resistance, so that the case portion with the ring member 6 as a boundary is used. The differential pressure between the inside and outside of 5B does not increase. Therefore, the secondary damping force added to the main damping force by the hydraulic cushion C2 can be reduced.

On the other hand, when the hydraulic cushion C2 is operating and the stroke speed of the shock absorber toward the contracting side is in the high speed range, the throttle passage 61 is closed. Then, resistance is given by the throttle hole 62 to the flow of the liquid moving from the inside of the case portion 5B to the outside (the upper side in FIG. 8). Further, when the shock absorber contracts, the liquid in the case portion 5B passes through the damping passage 4b and moves to the liquid storage chamber R3, but the damping valve 41 provides resistance to the flow of the liquid. Therefore, in the high speed region, the pressure inside the case portion 5B rises when the hydraulic cushion C2 operates, and the differential pressure inside and outside the case portion 5B with the ring member 6 as a boundary increases. Therefore, the secondary damping force of the hydraulic cushion C2 is added to the main compression side damping force, and the compression side damping force of the shock absorber increases.

Further, the shock absorber may include both the hydraulic cushion C1 that functions as a rebound cushion and the hydraulic cushion C2 that functions as a bound cushion. In this case, for example, the case portion 5 may be provided at one end portion of the cylinder, the case portion 5B may be provided at the other end portion, and the ring members 6 may be attached above and below the piston 2 in the piston rod 3, respectively.

In this way, the position where the case portion is provided can be changed as appropriate, and whichever case the case portion is provided with, the case portion can be formed integrally with the cylinder or separately. And the said change is possible irrespective of the structure of a holder, the structure of a ring member, and the attachment method.

Further, in the present embodiment, the shock absorber D includes a cylinder 1, a piston 2 slidably inserted into the cylinder 1, a piston rod having one end connected to the piston 2 and the other end protruding outside the cylinder 1. 3, a case portion 5 is provided at one end of the cylinder 1, and a ring member 6 is attached to the piston rod 3. However, the ring member 6 may be attached to a member (rod) other than the piston rod 3. The change can be made regardless of the structure of the holder, the structure and mounting method of the ring member, and the structure and arrangement of the case portion.

Further, in the present embodiment, the stroke speed region of the shock absorber D is divided into a low speed region and a high speed region, but the threshold value of each region can be set arbitrarily.

Although the embodiment of the present invention has been described above, the above embodiment merely shows a part of the application example of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

Modifications of the configurations of the above-described embodiments are also within the scope of the present invention, and the configurations of the above-described embodiments and the configurations of the above-described variations, or the variations may be appropriately combined within a range in which they can be combined.

The present application claims priority based on Japanese Patent Application No. 2017-30707 filed with the Japan Patent Office on February 22, 2017, the entire contents of which are incorporated herein by reference.

Claims (13)

A shock absorber,
A cylindrical case provided at the end of the cylinder,
A ring member that is attached to a rod that is axially movably inserted into the cylinder and that can be inserted into the case portion;
A throttle passage formed between the ring member and the case portion in a state where the ring member is inserted in the case portion, and a throttle passage communicating between the inside and the outside of the case portion,
A back pressure chamber formed on the inner circumference of the ring member and communicating with the inside of the case portion,
The ring member is configured to be capable of expanding its diameter by receiving the pressure of the back pressure chamber,
Shock absorber. The shock absorber according to claim 1, wherein
The shock absorber is a shock absorber whose flow passage area decreases as the diameter of the ring member increases. The shock absorber according to claim 1 or 2 , wherein
The shock absorber configured to expand the diameter of the ring member until it comes into contact with the inner circumference of the case portion by the pressure of the back pressure chamber. The shock absorber according to any one of claims 1 to 3 ,
The said ring member is a shock absorber attached to the said rod in the state with a tightening margin. The shock absorber according to any one of claims 1 to 4 ,
The said ring member is a shock absorber which has a part in the circumferential direction, and is formed in C shape by axial direction view. The shock absorber according to claim 5, wherein
The ring member is a shock absorber in which one end and the other end in the circumferential direction of the ring member are axially displaced from each other in an unloaded state. The shock absorber according to any one of claims 1 to 6 ,
The ring member is attached to the rod via an annular holder,
The holder has a guide portion whose axial length is longer than the axial length of the ring member and on which the ring member is mounted on the outer periphery,
The back pressure chamber is a shock absorber formed between the ring member and the guide portion. The shock absorber according to claim 7, wherein
The holder has an annular seat portion which is provided at an end portion of the guide portion on the side opposite to the case portion and on which the ring member can be seated.
In a state where the ring member is separated from the seat portion, the back pressure chamber allows a liquid to flow from the outside to the inside of the case portion together with a gap formed between the ring member and the seat portion. A shock absorber that constitutes the return passage. The shock absorber according to any one of claims 1 to 8 ,
The ring member is a shock absorber having an annular ring body and a plurality of protrusions provided on an inner circumference of the ring body. The shock absorber according to claim 7 or 8 , wherein
The ring member has an annular ring body and a plurality of protrusions provided on the inner circumference of the ring body,
The holder has an annular retaining portion at the case portion side end portion of the guide portion,
The outer diameter of the retaining portion is gradually reduced as it approaches the guide portion,
The outer diameter of the end portion of the retaining portion on the guide portion side is smaller than the inner diameter of the ring body when the ring member is not receiving an external force. The shock absorber according to any one of claims 1 to 10 ,
A shock absorber in which the ring member is inserted into the case portion when the amount of stroke toward the extension side exceeds a predetermined amount. The shock absorber according to any one of claims 1 to 10 ,
A shock absorber in which the ring member is inserted into the case portion when the amount of stroke toward the contraction side exceeds a predetermined amount. The shock absorber according to any one of claims 1 to 12 ,
The ring member is a shock absorber formed of an elastic body.

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