JP7485624B2 - Shock absorber - Google Patents

Description

The present invention relates to a shock absorber.

The shock absorber may, for example, comprise a cylinder, a piston rod movably inserted into the cylinder, a piston slidably inserted into the cylinder and connected to the piston rod, an extension side chamber and a compression side chamber partitioned in the cylinder by the piston and filled with hydraulic oil, an extension side port and a compression side port provided in the piston to communicate with the extension side chamber and the compression side chamber, an annular extension side leaf valve stacked on the compression side chamber end of the piston and fixed at its inner periphery to the piston rod to allow bending of its outer periphery to open and close the extension side port, an annular compression side leaf valve stacked on the extension side chamber end of the piston and fixed at its inner periphery to the piston rod to allow bending of its outer periphery to open and close the compression side port, and a choke passage provided in the piston to communicate with the extension side chamber and the compression side chamber.

When a shock absorber configured in this way expands or contracts at low speed, the expansion side leaf valve or the compression side leaf valve does not open, so the hydraulic oil passes through the choke passage between the expansion side chamber and the compression side chamber. Therefore, when a conventional shock absorber expands or contracts at low speed, it exerts a damping force that depends on the pressure loss when the hydraulic oil passes only through the choke passage (see Patent Document 1). The characteristic of the damping force generated by the shock absorber when the hydraulic oil passes only through the choke passage with respect to the expansion/contraction speed (damping force characteristic) is a characteristic that the damping force increases approximately in proportion to the expansion/contraction speed, which is called the choke characteristic. Therefore, when a choke passage is provided in the piston in this way, it is relatively easy to set the damping force compared to an orifice in which the damping force of the shock absorber is proportional to the square of the expansion speed.

JP 2007-132389 A

The longer the length of the choke passage, the greater the resistance it provides to the flow of hydraulic oil, and the greater the damping force of the shock absorber can be. For this reason, when providing a choke passage in the piston instead of an orifice in a conventional shock absorber, the length of the choke passage can be set according to the required damping force characteristics.

However, in conventional shock absorbers, when a choke passage is provided in the piston, it is provided so as to penetrate the piston in the axial direction from the extension side chamber end to the compression side chamber end, and the length of the choke passage cannot be set to be longer than the axial length of the piston. Also, increasing the axial length of the piston sacrifices the stroke length of the shock absorber, so there is a limit to how long the axial length of the piston can be increased.

As a result of the above, using an orifice makes it difficult to set the damping force characteristics, so it is desirable to use a choke passage. However, with conventional shock absorbers, the choke passage cannot be made long, meaning that it is not possible to set a high damping force when expanding and contracting at low speeds.

Therefore, the present invention aims to provide a shock absorber that can increase the damping force when expanding and contracting at low speeds and also makes it easy to set the damping force characteristics.

In order to solve the above-mentioned problems, the shock absorber of the present invention comprises a cylinder, a rod movably inserted into the cylinder, and a disk-shaped partition member inserted into the cylinder to partition two working chambers within the cylinder, the partition member comprising a port communicating the two working chambers and having a bent portion bent on one side of the inner or outer circumference of the partition member , and a choke passage communicating the two working chambers and having a portion passing along the circumferential direction on the inner or outer side of the bent portion of the port of the partition member , opposite to the bent side of the bent portion . In the shock absorber configured in this manner, the choke passage comprises a portion provided along the circumferential direction in a dead space on the inner or outer side of the port of the disk-shaped partition member, so that the passage length of the choke passage can be increased without increasing the axial length of the partition member. Since the passage length of the choke passage can be increased, the degree of freedom in designing the passage length of the choke passage is improved, and a choke passage of sufficient length can be formed in the partition member. Furthermore, with a shock absorber configured in this manner, a space is formed on the inner or outer side of the bent portion of the partition member, providing a portion that passes along the circumferential direction of the choke passage on the inner or outer side of the port of the partition member, and a choke passage can be formed without strain on the piston.

A shock absorber according to another invention includes a cylinder, a rod movably inserted into the cylinder, and a disk-shaped partition member inserted into the cylinder to partition two working chambers within the cylinder, the partition member having a port communicating the two working chambers, a choke passage communicating the two working chambers and having a portion passing along the circumferential direction on the inner or outer circumferential side of the port of the partition member, and a small diameter portion on the outer periphery of one end forming an annular gap between the cylinder and the partition member facing one of the working chambers, the choke passage opening from the small diameter portion and communicating with the other end of the partition member. In the shock absorber thus configured, the choke passage includes a portion provided along the circumferential direction in a dead space on the inner or outer circumferential side of the port of the disk-shaped partition member, so that the passage length of the choke passage can be increased without increasing the axial length of the partition member. Since the passage length of the choke passage can be increased, the degree of freedom in designing the passage length of the choke passage is improved, and a choke passage of sufficient length can be formed in the partition member. Furthermore, with a shock absorber configured in this manner, a large diameter can be ensured for the annular valve seat surrounding the port formed in the partition member, the opening response of the leaf valve can be improved, and the variation in damping force characteristics between products can be reduced. Also, in a shock absorber of another invention, the portion of the choke passage may be spirally shaped and disposed on the inner or outer circumferential side of the port of the partition member. With a shock absorber configured in this manner, the length of the choke passage can be set by setting the number of times the choke passage is turned circumferentially within the partition member by effectively utilizing the dead space of the partition member, and the degree of freedom in designing the passage length of the choke passage can be greatly improved.

Furthermore, the partitioning member in the shock absorber of the present invention may be provided with a small diameter portion on the outer periphery of one end thereof which forms an annular gap between the partitioning member and the cylinder and faces one of the working chambers, and the choke passage may be formed to open from the small diameter portion and communicate with the other end of the partitioning member. With this shock absorber configured in this manner, it is possible to ensure a large diameter for the annular valve seat surrounding the port formed in the partitioning member, thereby improving the valve opening responsiveness of the leaf valve and reducing the variation in damping force characteristics between products.

In addition, the partition member in the shock absorber of the present invention may include a plurality of ports that allow a fluid to flow from one side of the working chamber to the other side, and a plurality of second ports that are provided on the inner circumferential side of the ports of the partition member and not aligned in the radial direction with the ports, and that allow a fluid to flow from the other side of the working chamber to the one side, and one end of the choke passage may be connected to one of the ports, and the other end of the choke passage may be connected to one of the second ports. According to the shock absorber configured in this manner, it is possible to ensure a large diameter of the annular valve seat surrounding the ports and the second ports formed in the partition member, it is possible to improve the valve opening responsiveness of the leaf valve, and it is possible to reduce variation in damping force characteristics between products.

As a result, the shock absorber of the present invention can increase the damping force when expanding and contracting at low speeds, and it is easy to set the damping force characteristics.

FIG. 2 is a vertical cross-sectional view of the shock absorber according to the embodiment. FIG. 2 is a plan view of a piston of the shock absorber according to one embodiment. FIG. 2 is a cross-sectional view of a piston of a shock absorber according to an embodiment of the present invention; FIG. 4 is a bottom view of a piston of the shock absorber according to one embodiment. FIG. 11 is a cross-sectional view of a first modified example of a piston of the shock absorber according to the embodiment. FIG. 11 is a cross-sectional view of a second modified example of the piston of the shock absorber in one embodiment. FIG. 13 is a vertical cross-sectional view of a shock absorber according to an embodiment, which is provided with a piston according to a third modified example. FIG. 13 is a plan view of a third modified example of the piston of the shock absorber in one embodiment. FIG. 11 is a cross-sectional view of a third modified example of the piston of the shock absorber according to the embodiment; FIG. 13 is a bottom view of a third modified example of the piston of the shock absorber in the embodiment. FIG. 13 is a plan view of a fourth modified example of the piston of the shock absorber in one embodiment. FIG. 13 is a cross-sectional view of a fifth modified example of the piston of the shock absorber in one embodiment.

The present invention will be described below based on the embodiment shown in the drawings. As shown in FIG. 1, a shock absorber D in one embodiment includes a cylinder 1, a rod 2 movably inserted into the cylinder 1, and a piston 3 inserted into the cylinder 1 as a partition member that partitions the cylinder 1 into two working chambers, an expansion side chamber R1 and a compression side chamber R2. This shock absorber D is used, for example, by being interposed between the body and the axle of a vehicle (not shown) to suppress vibration of the body and wheels.

The following is a detailed explanation of each part of the shock absorber D. As shown in FIG. 1, an annular rod guide 10 is attached to the upper end of the cylinder 1, and the lower end of the cylinder 1 is closed with a cap 11. A rod 2 with a piston 3 attached to its tip is inserted into the cylinder 1 so as to be freely movable.

The rod 2 is inserted into the cylinder 1 by being slidably inserted through a rod guide 10 , and the movement in the axial direction is guided by the rod guide 10. The inside of the cylinder 1 is divided by the piston 3 into an extension side chamber R1 and a compression side chamber R2 filled with a fluid such as hydraulic oil. Note that the fluid may be a liquid other than hydraulic oil, such as water or an aqueous solution. Also, the fluid may be a gas instead of a liquid.

In the cylinder 1, below the compression side chamber R2, an air chamber G is defined by a free piston 6 that is slidably inserted into the cylinder 1. When the rod 2 is displaced axially relative to the cylinder 1, the air chamber G is expanded or contracted by the free piston 6 being displaced axially relative to the cylinder 1 in accordance with the volume of the rod 2 moving in and out of the cylinder 1, and the change in volume of the air chamber G compensates for the volume of the rod 2 moving in and out of the cylinder 1. In this way, the shock absorber D is a so-called single-cylinder shock absorber, but it may also be configured as a double-cylinder shock absorber with a reservoir outside the cylinder 1.

Returning to the previous section, the rod 2 has a threaded portion 2b provided on the outer periphery of the tip portion 2a, which is the lower end in FIG. 1, and a C-ring 2c attached to the outer periphery above the tip portion 2a. A ring-shaped extension-side leaf valve 7 and a compression-side leaf valve 8 are attached to the outer periphery of the tip portion 2a of the rod 2, together with an annular piston 3. These leaf valves 7, 8 and piston 3 are clamped by a piston nut 9 screwed onto the threaded portion 2b and the C-ring 2c, and are fixed to the outer periphery of the tip portion 2a of the rod 2.

As shown in Figures 2 to 4, the piston 3 is disk-shaped and has a central insertion hole 3a through which the tip 2a of the rod 2 is inserted, and an extension side port 3b and a compression side port 3c that are arc-shaped when viewed in the axial direction and are provided on the same circumference. The extension side ports 3b and the compression side ports 3c are arranged alternately on the same circumference in groups of three on the piston 3, and are considered as ports in the piston 3 as a partition member.

As shown in FIG. 4, the piston 3 has a petal-shaped valve seat 3d surrounding each of the expansion side ports 3b at the end facing the expansion side chamber R2, and as shown in FIG. 2, the piston 3 has a petal-shaped valve seat 3e surrounding each of the compression side ports 3c at the end facing the expansion side chamber R1. In this way, the expansion side ports 3b provided on the piston 3 of the shock absorber D of this embodiment are independent opening ports that are not connected to each other, and the compression side ports 3c are also independent opening ports that are not connected to each other.

As shown in Figures 2 to 4, the piston 3 is provided with a spiral choke passage T1 that is disposed on the outer periphery side of the expansion side port 3b and the compression side port 3c of the piston 3 and surrounds the expansion side port 3b and the compression side port 3c. In other words, the choke passage T1 is formed in a spiral shape and is formed to include a spiral portion that passes along the outer periphery side of the expansion side port 3b and the compression side port 3c as ports of the piston 3 in the circumferential direction. More specifically, the choke passage T1 is spiral and opens from the outer periphery side of the valve seat 3e at the expansion side chamber R1 end of the piston 3 and leads to the outer periphery side of the valve seat 3d at the compression side chamber R2 end of the piston 3, thereby communicating the expansion side chamber R1 and the compression side chamber R2.

Although not shown, the choke passage T1 may be formed of a spiral portion disposed on the outer periphery side of the extension side port 3b and the compression side port 3c of the piston 3, a portion that opens in the axial direction from the outer periphery side of the valve seat 3e at the end of the extension side chamber R1 of the piston 3 and is connected to the spiral portion, and a portion that opens in the axial direction from the outer periphery side of the valve seat 3d at the end of the compression side chamber R2 of the piston 3 and is connected to the spiral portion. The spiral choke passage T1 may also be disposed on the inner periphery side of the extension side port 3b and the compression side port 3c of the piston 3, as in the piston 3 in the first modified example shown in FIG. 5 and the second modified example shown in FIG. 6. When the choke passage T1 is disposed on the inner periphery side of the extension side port 3b and the compression side port 3c of the piston 3, as shown in FIG. 5, the spiral portion T1a of the choke passage T1 may be provided between the extension side port 3b and the compression side port 3c of the piston 3 as portions T1b and T1c that respectively connect the extension side chamber R1 end and the compression side chamber R2 end of the piston 3. Also, when the choke passage T1 is disposed on the inner periphery side of the extension side port 3b and the compression side port 3c of the piston 3, as shown in FIG. 6, one end and the other end of the choke passage T1 may be opened to the insertion hole 3a, and the rod 2 may be provided with a passage 2d that connects one of the openings to the extension side chamber R1 and a passage 2e that connects the other of the openings to the compression side chamber R2.

The piston 3 configured as described above can be manufactured using a 3D printer. Using a 3D printer, the choke passage T1, which has a complex structure, can be easily formed in the piston 3 together with the expansion side port 3b and the compression side port 3c.

The extension leaf valve 7 is a laminated leaf valve made of multiple stacked annular plates, and is laminated on the underside of the piston 3 facing the pressure side chamber R2 in FIG. 1. The inner periphery of the extension leaf valve 7 is sandwiched and fixed between the piston nut 9 and the C-ring 2c, and the bending of the outer periphery, which is the free end, is permitted, and it opens and closes the outlet end of the extension side port 3b by seating on the valve seat 3d. In this way, when the extension side leaf valve 7 is sandwiched between the piston nut 9 and the C-ring 2c of the rod 2 and fixed to the rod 2 while overlapping the piston 3, it abuts against the valve seat 3d and is laminated on the piston 3. When the outer periphery of the extension side leaf valve 7 is seated on the valve seat 3d, it closes the extension side port 3b and cuts off the communication between the extension side chamber R1 and the compression side chamber R2 via the extension side port 3b. In addition, when the expansion-side leaf valve 7 receives pressure from the expansion-side chamber R1 through the expansion-side port 3b and bends, it leaves the valve seat 3d, opening the expansion-side port 3b, connecting the expansion-side chamber R1 to the compression-side chamber R2, and providing resistance to the flow of hydraulic oil from the expansion-side chamber R1 to the compression-side chamber R2.

The contraction-side leaf valve 8 is a laminated leaf valve made of multiple stacked annular plates, and is laminated on the upper surface of the piston 3 facing the expansion-side chamber R1 in FIG. 1. The contraction-side leaf valve 8 is fixed by being clamped at its inner periphery between the piston nut 9 and the C-ring 2c, and is allowed to bend at its outer periphery, which is its free end, and opens and closes the outlet end of the contraction-side port 3c by being seated on the valve seat 3e. In this way, when the contraction-side leaf valve 8 is stacked on the piston 3 and clamped between the piston nut 9 and the C-ring 2c of the rod 2 and fixed to the rod 2, it abuts against the valve seat 3e and is laminated on the piston 3. When the contraction-side leaf valve 8 is seated at its outer periphery on the valve seat 3e, it closes the contraction-side port 3c and cuts off communication between the contraction-side chamber R2 and the expansion-side chamber R1 through the contraction-side port 3c. In addition, when the compression side leaf valve 8 receives pressure from the compression side chamber R2 through the compression side port 3c and bends, it leaves the valve seat 3e, opening the compression side port 3c, connecting the compression side chamber R2 to the expansion side chamber R1, and providing resistance to the flow of hydraulic oil from the compression side chamber R2 to the expansion side chamber R1.

The shock absorber D is configured as described above, and its operation will be described below. First, the operation will be described when the rod 2 moves upward in FIG. 1 relative to the cylinder 1 and the shock absorber D extends. When the shock absorber D extends, the piston 3 moves upward in FIG. 1 relative to the cylinder 1, compressing the expansion side chamber R1 and expanding the compression side chamber R2.

Then, the pressure in the expansion side chamber R1 rises. This pressure acts on the expansion side leaf valve 7 through the expansion side port 3b that is not blocked by the leaf valve 8 stacked at the upper end of the piston 3 in FIG. 1. When the expansion speed of the shock absorber D is low and the pressure in the expansion side chamber R1 does not reach the opening pressure of the leaf valve 7, the hydraulic oil moves from the expansion side chamber R1 to the compression side chamber R2 only through the choke passage T1. Therefore, when the expansion speed of the shock absorber D is low, the choke passage T1 provides resistance to the hydraulic oil passing through it to generate a damping force. Also, when the expansion speed of the shock absorber D exceeds the low speed and reaches the high speed range, the leaf valve 7 bends and leaves the valve seat 3d, opening the expansion side port 3b, so that the hydraulic oil in the expansion side chamber R1 moves to the compression side chamber R2 through the expansion side port 3b and the choke passage T1. When the flow rate of the choke passage T1 increases, it provides a greater resistance to the flow of hydraulic oil than the leaf valve 7. Therefore, when the extension speed of the shock absorber D becomes high, the hydraulic oil has difficulty passing through the choke passage T1, and so it preferentially passes through the extension port 3b. Therefore, when the extension speed of the shock absorber D exceeds low speed and reaches a high speed range, the damping force is generated almost entirely by the resistance that the leaf valve 7 provides to the flow of hydraulic oil. When the shock absorber D extends, the rod 2 retreats from the cylinder 1, so the free piston 6 moves upward in FIG. 1 relative to the cylinder 1, and the volume of the air chamber G expands by the volume of the rod 2 retreating from the cylinder 1, compensating for the volume of the rod 2 retreating from the cylinder 1.

Next, we will explain the operation when the rod 2 moves downward in FIG. 1 relative to the cylinder 1 and the shock absorber D contracts. When the shock absorber D contracts, the piston 3 moves downward in FIG. 1 relative to the cylinder 1, compressing the compression side chamber R2 and expanding the expansion side chamber R1.

Then, the pressure in the compression side chamber R2 rises. This pressure acts on the compression side leaf valve 8 through the compression side port 3c that is not blocked by the leaf valve 7 stacked at the lower end of the piston 3 in FIG. 1. When the contraction speed of the shock absorber D is low and the pressure in the compression side chamber R2 does not reach the opening pressure of the leaf valve 8, the hydraulic oil moves from the compression side chamber R2 to the extension side chamber R1 only through the choke passage T1. Therefore, when the contraction speed of the shock absorber D is low, the choke passage T1 provides resistance to the hydraulic oil passing through it to generate a damping force. Also, when the contraction speed of the shock absorber D exceeds the low speed and reaches the high speed range, the leaf valve 8 bends and leaves the valve seat 3e, opening the compression side port 3c, so that the hydraulic oil in the compression side chamber R2 moves to the extension side chamber R1 through the compression side port 3c and the choke passage T1. When the flow rate of the choke passage T1 increases, it provides a greater resistance to the flow of hydraulic oil than the leaf valve 8. Therefore, when the contraction speed of the shock absorber D becomes high, the hydraulic oil has difficulty passing through the choke passage T1, and so it preferentially passes through the compression side port 3c. Therefore, when the contraction speed of the shock absorber D exceeds low speed and reaches a high speed range, the damping force is generated almost entirely by the resistance that the leaf valve 8 provides to the flow of hydraulic oil. When the shock absorber D contracts, the rod 2 enters the cylinder 1, so the free piston 6 moves downward in FIG. 1 relative to the cylinder 1, and the volume of the air chamber G is reduced by the volume of the rod 2 entering the cylinder 1, and the volume of the rod 2 entering the cylinder 1 is compensated for.

In this way, when the expansion/contraction speed of the shock absorber D is low, the shock absorber D generates a damping force through the choke passage T1, and when the expansion/contraction speed of the shock absorber D is high, the shock absorber D generates a damping force through the leaf valves 7 and 8. Therefore, the damping force characteristics of the shock absorber D in this embodiment are choke characteristics that are approximately proportional to the expansion/contraction speed when the expansion/contraction speed of the shock absorber D is low, and when the expansion/contraction speed of the shock absorber D becomes high, the characteristics change to the valve characteristics of the leaf valves 7 and 8.

As described above, the shock absorber D of this embodiment includes a cylinder 1, a rod 2 movably inserted into the cylinder 1, and a disk-shaped piston (compartment member) 3 that is inserted into the cylinder 1 and divides the inside of the cylinder 1 into two working chambers, an expansion side chamber R1 and a compression side chamber R2. The piston (compartment member) 3 includes an expansion side port (port) 3b and a compression side port (port) 3c that connect the expansion side chamber R1 and the compression side chamber R2, and a choke passage T1 that connects the expansion side chamber R1 and the compression side chamber R2 and has a portion that passes circumferentially on the outer periphery side of the expansion side port (port) 3b and the compression side port (port) 3c of the piston (compartment member) 3.

In the shock absorber D configured in this manner, the choke passage T1 has a portion provided along the circumferential direction in the dead space on the outer periphery of the expansion side port (port) 3b and the compression side port (port) 3c of the disk-shaped piston (compartment member) 3, so the passage length of the choke passage T1 can be increased without increasing the axial length of the piston (compartment member) 3. Since the passage length of the choke passage T1 can be increased, the design freedom of the passage length of the choke passage T1 is improved, and a choke passage T1 of sufficient length can be formed in the piston (compartment member) 3. In this way, according to the shock absorber D of this embodiment, the passage length of the choke passage T1 can be increased, and it is not necessary to use an orifice whose damping force characteristics are difficult to set as a countermeasure against insufficient damping force, so the damping force when expanding and contracting at low speeds can be increased and the damping force characteristics can be easily set.

As described above, the choke passage T1 may have a portion that is provided circumferentially in a dead space on the inner periphery of the expansion side port (port) 3b and the compression side port (port) 3c of the disk-shaped piston (compartment member) 3. Even in a shock absorber D configured in this way, the passage length of the choke passage T1 can be increased, and it is not necessary to use an orifice, whose damping force characteristics are difficult to set, as a countermeasure against insufficient damping force. This makes it possible to increase the damping force when expanding and contracting at low speeds and also makes it easier to set the damping force characteristics.

In addition, in the shock absorber D of this embodiment, the portion of the choke passage T1 that is provided on the inner or outer circumference of the expansion side port (port) 3b and the compression side port (port) 3c of the piston (compartment member) 3 is spiral-shaped, so the length of the choke passage T1 can be set by setting the number of times the piston (compartment member) 3 is rotated circumferentially by effectively utilizing the dead space of the piston (compartment member) 3, greatly improving the design freedom of the passage length of the choke passage T1.

In the shock absorber D of this embodiment, the partitioning member is the piston 3, but a partition wall or the like used in a manner fixed to the cylinder 1 may also be used as the partitioning member. For example, in a twin-cylinder shock absorber with a reservoir outside the cylinder, the valve case fixed to the end of the cylinder may be used as the partitioning member, and the reservoir and compression side chamber partitioned by the valve case may be used as the working chamber, forming a choke passage in the valve case.

As shown in FIG. 7, the piston 20 may be configured as follows as a third modified example of the partition member. As shown in FIG. 7 to FIG. 10, the piston 20 includes a disk-shaped piston body 21 having an insertion hole 21a in the center that allows the rod 2 to be inserted, a cylindrical extension 22 that hangs down from the outer periphery of the lower end of the piston body 21 in FIG. 9, a ring mounting part 23 having a plurality of annular grooves provided on the outer periphery of the extension part from the middle of the outer periphery of the piston body 21, and a piston ring 24 that is mounted on the outer periphery of the ring mounting part 23. In the piston 20 configured in this manner, the outer diameter of the part of the piston body 21 where the piston ring 24 is not mounted is smaller than the outer diameter of the piston ring 24, and an annular gap C is formed between this part and the cylinder 1. In other words, a small diameter part 25 is formed in the piston 20 in the part of the piston body 21 where the piston ring 24 is not mounted.

In addition, the piston body 21 of the piston 20 is provided with three compression side ports 21c that are arc-shaped in the axial direction and communicate between the expansion side chamber R1 and the compression side chamber R2, and three expansion side ports 21b that are circular in the axial direction and communicate between the expansion side chamber R1 and the compression side chamber R2. The expansion side ports 21b are provided at equal intervals on the same circumference in the piston body 21 of the piston 20, and the compression side ports 21c are provided at equal intervals on the same circumference on the outer periphery side of the expansion side ports 21b of the piston body 21 of the piston 20. At the end of the compression side chamber R2 of the piston body 21, an extension side annular valve seat 21d is provided, which surrounds the outer periphery of each extension side port 21b. At the end of the compression side chamber R1 of the piston body 21, an inner annular valve seat 21e is provided between the extension side port 21b and the compression side port 21c, which surrounds the outer periphery of each extension side port 21b, and a compression side annular valve seat 21f is provided, which surrounds the outer periphery of each compression side port 21c.

The extension side port 21b and the compression side port 21c are provided at positions offset from each other in the circumferential direction with respect to the piston body 21, that is, positions that are not aligned radially with respect to the piston body 21. Furthermore, the compression side port 21c, which is provided on the outer periphery side of the extension side port 21b with respect to the piston body 21, has a bent portion 21c1 in the center that is bent toward the inner periphery side of the piston body 21, as shown in FIG. 9.

The piston 20 is provided with a choke passage T2. The choke passage T2 is configured to include a portion T2a that opens from the small diameter portion 25, which is the outer periphery of the piston body 21, and extends diagonally downward in FIG. 9 toward the center of the piston 20, leading to the axial center of the piston body 21; a portion T2b that opens from a position that is on the outer periphery of the opening of the extension side port 21c and radially faces the extension side port 21b at the lower end of the piston body 21 in FIG. 9, extends in the axial direction, and leads to the axial center of the piston body 21; and a portion T2c that is arranged on the outer periphery of the compression side port 21c as a port and the extension side port 21b as a second port in the piston 20, passes along the circumferential direction, and communicates with the portion T2a and the portion T2b, as shown in FIG. 8. The circumferential length of the portion T2c is set to be longer than the axial length of the piston body 21 in the piston 20, but can be set to any length by setting the damping force. Additionally, portion T2c may extend along the circumferential direction while meandering radially around the piston body 21.

The portion T2c of the choke passage T2 that passes circumferentially on the outer periphery side of the compression side port 21c and the extension side port 21b of the piston 20 passes outside the bent portion 21c1 of the compression side port 21c, and is arranged at a position overlapping the open end of the compression side port 21c when the piston 20 is viewed from the axial direction, as shown in FIG. 8. In other words, the portion T2c of the choke passage T2 is arranged on the outer periphery of the bent portion 21c1 of the compression side port 21c, on the opposite side to the bent side of the bent portion 21c1, and is arranged between the opening of the compression side port 21c on the extension side chamber R1 side and the opening of the compression side chamber R2 side in the axial direction of the piston 20. When viewed from the compression side port 21c, the compression side port 21c has a bent portion 21c1 in the center that avoids the portion T2c of the choke passage T2.

Since the compression side port 21c has the bent portion 21c1 in the middle in this way, a space is formed on the outer periphery side of the bent portion 21c1 of the piston 20 to provide a portion T2c that passes along the circumferential direction of the choke passage T2 from the compression side port 21c, and the choke passage T2 can be formed smoothly in the piston 20. Since each expansion side port 21b as the second port is provided on the inner periphery side of each compression side port 21c, it is not necessary to provide a bent portion to ensure a space to provide the portion T2c of the choke passage T2. If the compression side port 21c and the expansion side port 21b are provided on the same circumference and do not have a bent portion, a bent portion may be provided in the compression side port 21c and the expansion side port 21b when the space to provide the portion T2c of the choke passage T2 cannot be ensured in the piston 20 .

Also, the choke passage T2 may be formed as in the piston 20 in the fourth modified example shown in Fig. 11 and the fifth modified example shown in Fig. 12. Specifically, the choke passage T2 has only the portion T2c, and as shown in Fig. 11, the compression side port 21c and the expansion side port 21b are communicated in the piston 20 , and the expansion side chamber R1 and the compression side chamber R2 are communicated through the compression side port 21c and the expansion side port 21b. Furthermore, the portion T2c in the choke passage T2 may be disposed on the inner circumferential side of the expansion side port 21b and the compression side port 21c of the piston 20, as shown in Fig. 12. In this case, in order to prevent the inner circumferential side expansion side port 21b from compressing the space for providing the portion T2c of the choke passage T2, a bent portion 21b1 is provided that bends to the outer circumferential side of the piston 20 as the expansion side port 21b, thereby securing a space for providing the portion T2c, and the bent portion may not be provided for the compression side port 21c. In addition, when the choke passage T2 is disposed on the inner side of the expansion-side port 21 b and the compression-side port 21 c of the piston 20, as in the example shown in FIG. 6, one end and the other end of the choke passage T2 may be opened to the insertion hole 21 a, and the rod 2 may be provided with a passage 2d communicating one of the openings with the expansion-side chamber R1 and a passage 2e communicating the other opening with the compression-side chamber R2.

Even if the choke passage T2 is formed in the piston 20 as described above, the choke passage T2 has a portion provided along the circumferential direction in the dead space on the outer circumferential side of the compression side port (port) 21c of the disk-shaped piston (partition member) 20, so the passage length of the choke passage T2 can be lengthened along the circumferential direction, which is easier to obtain a length than the axial length of the piston (partition member) 20, without lengthening the axial length of the piston (partition member) 20. Since the passage length of the choke passage T2 can be lengthened, the design freedom of the passage length of the choke passage T2 is improved, and a choke passage T2 of sufficient length can be formed in the piston (partition member) 20. Therefore, according to the shock absorber D of this embodiment in which the choke passage T2 is formed in the piston 20 as described above, the passage length of the choke passage T2 can be lengthened, and it is not necessary to use an orifice whose damping force characteristics are difficult to set as a countermeasure for insufficient damping force, so the damping force when expanding and contracting at low speeds can be increased and the damping force characteristics can be easily set.

As described above, the choke passage T2 may have a portion that is provided circumferentially in the dead space on the inner periphery side of the compression side port (port) 21c of the disc-shaped piston (compartment member) 20. Even in the shock absorber D configured in this way, the passage length of the choke passage T2 can be increased, and it is not necessary to use an orifice, whose damping force characteristics are difficult to set, as a countermeasure against insufficient damping force. This makes it possible to increase the damping force when expanding and contracting at low speeds and also makes it easier to set the damping force characteristics.

In addition, in the piston (compartment member) 20 of the third modified example described above, the compression side port (port) 21c has a bent portion 21c1 that bends to the inner circumference of the piston (compartment member) 20, and the portion T2c that is arranged on the outer periphery of the compression side port (port) 21c of the piston (compartment member) 20 in the choke passage T2 and passes along the circumferential direction is arranged on the outer periphery side of the bent portion 21c1 of the compression side port (port) 21c and on the opposite side to the bent side of the bent portion 21c1. According to the shock absorber D configured in this manner, a space is formed on the outer periphery side of the bent portion 21c1 of the piston (compartment member) 20 to provide the portion T2c that passes along the circumferential direction of the choke passage T2 from the compression side port (port) 21c, and the choke passage T2 can be formed smoothly in the piston (compartment member) 20. In addition, as shown in FIG. 12, when the portion T2c of the choke passage T2 is arranged on the inner side of the extension side port 21b of the piston 20, a bent portion 21b1 that bends toward the outer periphery of the piston (compartment member) 20 may be provided in the extension side port 21c, and the portion T2c arranged on the inner side of the extension side port 21b in the choke passage T2 and passing along the circumferential direction may be arranged on the inner side of the bent portion 21b1 of the extension side port 21b of the piston (compartment member) 20 and on the opposite side to the bent side of the bent portion 21b1. Even with the shock absorber D configured in this way, a space is formed on the inner side of the bent portion 21b1 of the piston 20 to provide the portion T2c that passes along the circumferential direction of the choke passage T2 from the extension side port 21b of the piston 20, and the choke passage T2 can be formed smoothly in the piston 20.

Furthermore, the piston (compartment member) 20 of the third modified example described above has a small diameter portion 25 that forms an annular gap C facing the expansion side chamber (one of the working chambers) R1 between the cylinder 1 and the outer periphery of the expansion side chamber side end, which is one end, and the choke passage T2 opens from the small diameter portion 25 and leads to the compression side chamber side end, which is the other end of the piston (compartment member) 20. In the piston (compartment member) 20 configured in this manner, the outlet end of the expansion side chamber R1 side of the choke passage T2 is formed in the small diameter portion 25, which is the outer periphery side of the piston (compartment member) 20, and it is not necessary to provide the outlet end of the expansion side chamber R1 side of the choke passage T2 at the end of the piston (compartment member) 20 facing the expansion side chamber (one of the working chambers) R1. Therefore, the outlet end of the compression side port (port) 21c can be arranged on the outer periphery side of the end of the piston (compartment member) 20 facing the expansion side chamber (one of the working chambers) R1 without being obstructed by the choke passage T2. Therefore, with the shock absorber D configured in this manner, the diameter of the compression side annular valve seat 21f surrounding the compression side port (port) 21c formed in the piston (compartment member) 20 can be made large, so that the pressure-receiving area that receives the pressure of the compression side chamber R2 of the compression side leaf valve 8 is increased, improving the opening response of the leaf valve 8. Therefore, with the shock absorber D configured in this manner, the opening response of the leaf valve 8 can be improved, so that the variation in the damping force characteristics between products can be reduced.

The small diameter portion may be provided on the outer periphery of the compression side chamber of the piston 20. In this case, the expansion side port 21b may be arranged on the outer periphery side of the compression side port 21c, and the expansion side chamber side end of the choke passage T2 may be opened to the small diameter portion. In this way, the choke passage T2 does not get in the way when the outlet end of the expansion side port 21b is formed on the outer periphery side of the piston 20, and the diameter of the expansion side annular valve seat 21d surrounding the expansion side port 21b is increased to improve the opening response of the leaf valve 7, thereby reducing the variation in the damping force characteristics of the shock absorber D from product to product.

Furthermore, the piston (compartment member) 20 of the fourth modified example described above has a plurality of compression side ports (ports) 21c that allow fluid to flow from the compression side chamber R2 to the expansion side chamber R1, and a plurality of expansion side ports (second ports) 21b that are located on the inner side of the compression side ports (ports) 21c of the piston (compartment member) 20 and do not radially oppose the compression side ports (ports) 21c and allow fluid to flow from the expansion side chamber R1 to the compression side chamber R2, and one end of the choke passage T2 is connected to one of the compression side ports (ports) 21c, and the other end of the choke passage T2 is connected to one of the expansion side ports (second ports) 21b. In the piston (compartment member) 20 configured in this manner, the outlet ends of both ends of the choke passage T2 are not formed at the expansion side chamber side end and the compression side chamber side end of the piston (compartment member) 20, so the diameter of the compression side annular valve seat 21f surrounding the compression side port (port) 21c and the diameter of the expansion side annular valve seat 21d surrounding the expansion side port 21b can be increased. Therefore, according to the shock absorber D configured in this manner, the opening response of the leaf valves 7 and 8 can be improved, and the variation in the damping force characteristics of the shock absorber D for each product can be reduced. In this embodiment, the compression side port 21c is a port and the expansion side port 21b is a second port, but the compression side port 21c may be a second port and the expansion side port 21b may be a port.

Although the preferred embodiment of the present invention has been described in detail above, modifications, variations, and changes are possible without departing from the scope of the claims.

Reference Signs List 1: Cylinder, 2: Rod, 3, 20: Piston (compartment member), 3b: Expansion side port (port), 3c, 21c: Compression side port (port), 21b: Expansion side port (second port), 21b1, 21c1: Bent portion, 25: Small diameter portion, C: Annular gap, D: Shock absorber, R1: Expansion side chamber (operating chamber), R2: Compression side chamber (operating chamber), T1, T2: Choke passage, T2c: Part in choke passage

Claims (5)

A cylinder;
A rod that is movably inserted into the cylinder;
a partition member that is disk-shaped and is inserted into the cylinder to partition two working chambers within the cylinder;
a partition member having a port communicating with the two working chambers and having a bent portion bent to one of the inner circumference or the outer circumference of the partition member , and a choke passage communicating with the two working chambers and having a portion passing along a circumferential direction on the inner circumference side or the outer circumference side of the bent portion of the port of the partition member, opposite to the bent side of the bent portion . A cylinder;
A rod that is movably inserted into the cylinder;
a partition member that is disk-shaped and is inserted into the cylinder to partition two working chambers within the cylinder;
the partition member has a port communicating the two working chambers, a choke passage communicating the two working chambers and having a portion passing along a circumferential direction on an inner circumferential side or an outer circumferential side of the port of the partition member, and a small diameter portion on an outer periphery of one end thereof forming an annular gap between the cylinder and the small diameter portion facing one side of the working chamber,
The choke passage opens from the small diameter portion and leads to the other end of the partition member.
A shock absorber characterized by: The shock absorber according to claim 2 , wherein the portion of the choke passage is spiral and is disposed on the inner or outer circumferential side of the port of the partition member. the partition member has a small diameter portion on an outer periphery of one end thereof which forms an annular gap between the partition member and the cylinder and faces one side of the working chamber;
The shock absorber according to claim 1 , wherein the choke passage opens from the small diameter portion and communicates with the other end of the partition member. the partition member has a plurality of the ports that allow a fluid to flow from one side of the working chamber to the other side, and a plurality of second ports that are provided on the inner circumferential side of the ports of the partition member and not aligned with the ports in the radial direction, and that allow a fluid to flow from the other side of the working chamber to one side,
2. The shock absorber according to claim 1 , wherein one end of the choke passage is connected to one of the ports, and the other end of the choke passage is connected to one of the second ports.

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