JP2022143217A - Cylinder device - Google Patents

Abstract

To provide a cylinder device which can prevent a rebound cushion from becoming the flow passage resistance of a working fluid.SOLUTION: A cylinder device comprises: a cylinder into which a working fluid is sealed; a piston slidably fit into the cylinder, and partitioning the inside of the cylinder into two chambers; a rod guide arranged at an opening side of the cylinder; a piston rod connected to the piston at one end side, inserted into the rod guide, and extended to the outside of the cylinder at the other end side; and a rebound cushion 66 arranged at the piston rod, and abutting on the rod guide according to the extension of the piston rod from the cylinder. The rebound cushion 66 is formed into a satin shape having minute irregularities 101 on its surface.SELECTED DRAWING: Figure 2

Description

The present invention relates to a cylinder device.

Some cylinder devices have a piston rod provided with a rebound cushion that abuts against a rod guide as the piston rod extends from the cylinder (see, for example, Patent Documents 1 and 2).

JP-A-2002-39252 JP 2014-92169 A

When the rebound cushion contacts the rod guide and deforms, it narrows the flow path of the working fluid flowing on its surface, resulting in flow path resistance.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cylinder device capable of suppressing the rebound cushion from becoming flow path resistance.

In order to achieve the above object, according to one aspect of the present invention, the rebound cushion has a satin-like surface with minute unevenness.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to suppress that a rebound cushion becomes flow-path resistance.

BRIEF DESCRIPTION OF THE DRAWINGS It is a front sectional view which shows the cylinder apparatus of one Embodiment which concerns on this invention. It is a front sectional view showing a rebound cushion of a cylinder device of one embodiment concerning the present invention. It is a top view showing a rebound cushion of a cylinder device of one embodiment concerning the present invention. It is a front sectional view showing the surface of the rebound cushion of the cylinder device of one embodiment concerning the present invention. 1 is a front cross-sectional view showing essential parts of a cylinder device according to one embodiment of the present invention when fully extended; FIG.

A cylinder device of one embodiment according to the present invention will be described below with reference to the drawings.

A cylinder device 10 of the present embodiment shown in FIG. 1 is a hydraulic shock absorber that uses oil as a working fluid, and is used in a suspension device for a vehicle such as an automobile. The cylinder device 10 includes a cylindrical inner cylinder 11 and a bottomed cylinder having a larger diameter than the inner cylinder 11 and coaxially provided on the outer peripheral side of the inner cylinder 11 so as to form a reservoir chamber 12 between the inner cylinder 11 and the inner cylinder 11 . It has a cylinder 14 consisting of a shaped outer cylinder 13 . That is, the cylinder device 10 is of a double cylinder type in which the cylinder 14 has the inner cylinder 11 and the outer cylinder 13 . It should be noted that the present invention is applicable not only to a double-tube type cylinder device, but also to a single-tube type cylinder device.

The cylinder device 10 is arranged on the central axis of the inner cylinder 11 and has one axial end side inserted into the inner cylinder 11 and the other axial end side extending from the opening sides of the inner cylinder 11 and the outer cylinder 13 to the outside. and a piston 18 connected to one end of the piston rod 15 and slidably fitted in the inner cylinder 11 of the cylinder 14 to divide the inner cylinder 11 into two chambers 16 and 17. have. The cylinder 14 has an inner cylinder 11 filled with hydraulic fluid as a working fluid, and a reservoir chamber 12 between the inner cylinder 11 and the outer cylinder 13 filled with hydraulic fluid and high-pressure gas as a working fluid. there is

The cylinder device 10 includes a cylindrical rod guide 21 provided on the opening side in the axial direction of the inner cylinder 11 and the outer cylinder 13 that constitute the cylinder 14, and the rod guide 21 arranged further outside the rod guide 21 in the axial direction of the outer cylinder 13. and a base valve 23 arranged on the opposite side of the rod guide 21 and the oil seal 22 in the axial direction of the inner cylinder 11 and the outer cylinder 13 . The piston rod 15 is slidably inserted inside the rod guide 21 and the oil seal 22 . The rod guide 21 supports the piston rod 15 axially movably while restricting its radial movement, and guides the movement of the piston rod 15 . The inner circumference of the oil seal 22 is in sliding contact with the axially moving piston rod 15 to prevent the oil in the inner cylinder 11 and the high-pressure gas and oil in the reservoir chamber 12 from leaking out. do. In this embodiment, the reservoir chamber 12 is filled with oil and high-pressure gas as working fluids, but the reservoir chamber 12 may be filled with air instead of high-pressure gas.

The outer cylinder 13 is made of metal, and has a cylindrical body portion 25, a bottom portion 26 that closes one end side of the body portion 25 opposite to the projecting side of the piston rod 15, and the piston rod 15 in the body portion 25. It has a substantially cylindrical shape with a bottom and a locking portion 28 that protrudes radially inward from the position of the opening 27 on the protruding side.

The inner cylinder 11 is made of metal and has a cylindrical shape. One axial end side of the inner cylinder 11 is fitted and supported by a base body 30 of a base valve 23 disposed inside the bottom portion 26 of the outer cylinder 13 . The other end side is supported by the rod guide 21 fitted inside the opening 27 of the outer cylinder 13 .

A base body 30 of the base valve 23 is made of metal. The base body 30 has an oil passage 31 that allows communication between the chamber 17 in the inner cylinder 11 and the reservoir chamber 12 between the outer cylinder 13 and the inner cylinder 11. , 32 are formed. A disc valve 33 as a compression damping valve capable of opening and closing the inner oil passage 31 is arranged on the base body 30 on the bottom portion 26 side, and a disc valve as a check valve capable of opening and closing the outer oil passage 32 is arranged. 34 is located opposite the bottom 26 . These disc valves 33 , 34 are attached to the base body 30 with rivets 35 .

The disk valve 33 allows oil to flow from the chamber 17 to the reservoir chamber 12 side through the passage hole (not shown) of the disk valve 34 and the oil passage 31 to generate a damping force, while the oil in the opposite direction is allowed to flow. Regulate the flow of liquid. On the contrary, the disk valve 34 permits the flow of oil from the reservoir chamber 12 to the chamber 17 through the oil passage 32 without resistance, but restricts the flow of the oil in the opposite direction. In other words, the disk valve 33 opens the oil passage 31 when the piston rod 15 moves toward the contraction side and the piston 18 moves toward the chamber 17 side to increase the pressure in the chamber 17, generating a damping force at that time. damping valve. Further, the disk valve 34 opens the oil passage 32 when the piston rod 15 moves to the extension side and the piston 18 moves to the chamber 16 side and the pressure in the chamber 17 drops. It is a suction valve that allows oil to flow into the chamber 17 without substantially generating a damping force.

The piston rod 15 is made of metal and has a main shaft portion 37 with a substantially constant diameter and a mounting shaft portion 38 at the end of the side inserted into the inner cylinder 11 and having a smaller diameter than the main shaft portion 37 . . A nut 40 is screwed onto the mounting shaft portion 38 , and the piston 18 and disk valves 41 and 42 on both sides of the piston 18 are mounted on the piston rod 15 by the nut 40 . The piston rod 15 moves together with the piston 18 .

The piston 18 is provided with an oil passage 44 and an oil passage 44 that allows communication between the chamber 17 in the inner cylinder 11 on the bottom 26 side of the piston 18 and the chamber 16 in the inner cylinder 11 on the opposite side of the piston 18 to the bottom 26 . A passage 45 is formed. The disk valve 41, which is a compression-side damping valve capable of opening and closing the oil passage 44, is disposed on the piston 18 on the side opposite to the bottom portion 26, and serves as an extension-side damping valve capable of opening and closing the oil passage 45. The disc valve 42 described above is arranged on the bottom portion 26 side.

The disk valve 41 permits oil to flow from the chamber 17 to the chamber 16 through the oil passage 44, but restricts the oil to flow in the opposite direction. On the contrary, the disc valve 42 allows oil to flow from the chamber 16 side to the chamber 17 through the passage hole (not shown) of the disc valve 41 and the oil passage 45, while the oil is allowed to flow in the opposite direction. regulate the flow. In other words, the disk valve 41 opens the oil passage 44 when the piston rod 15 moves toward the contraction side and the piston 18 moves toward the chamber 17, increasing the pressure in the chamber 17, generating a damping force. damping valve. Further, the disk valve 42 opens the oil passage 45 when the piston rod 15 moves to the extension side and the piston 18 moves to the chamber 16 side to increase the pressure in the chamber 16, generating a damping force at that time. damping valve.

When the piston rod 15 moves toward the extension side and the amount of protrusion from the inner cylinder 11 increases, the corresponding amount of oil flows from the reservoir chamber 12 through the oil passage 32 while opening the disc valve 34 of the base valve 23 . 17, and when the piston rod 15 moves to the contraction side and the insertion amount into the inner cylinder 11 increases, the corresponding amount of oil flows from the chamber 17 through the oil passage 31 while opening the disk valve 33. , and flows into the reservoir chamber 12.

The rod guide 21 includes a substantially stepped cylindrical metal rod guide body 50 and a cylindrical collar 51 fitted and fixed to the inner peripheral portion of the rod guide body 50 . The collar 51 is formed by coating the inner peripheral surface of a cylindrical body made of metal such as SPCC material or SPCE material with fluororesin-impregnated bronze.

The rod guide body 50 has an insertion portion 53 on one side in the axial direction and a collar portion 54 on the other side in the axial direction and having a larger diameter than the insertion portion 53 . It is inserted on the peripheral side, and is fitted and inserted into the inner peripheral portion of the body portion 25 of the outer cylinder 13 at the collar portion 54 . In the center of the rod guide body 50 in the radial direction, a large-diameter hole portion 56 is provided on the axial flange portion 54 side, and a small-diameter hole portion 57 having a smaller diameter than the large-diameter hole portion 56 is provided on the axial insertion portion 53 side. formed respectively.

The rod guide main body 50 is formed with an annular projection 59 projecting in the axial direction at the axial end on the collar portion 54 side. A communicating hole 60 is formed to penetrate through. The communication hole 60 communicates with the reservoir chamber 12 between the outer cylinder 13 and the inner cylinder 11 . The collar 51 is fitted in the small-diameter hole 57 of the rod guide body 50 , and the piston rod 15 is inserted through the collar 51 so that the main shaft portion 37 is in sliding contact with the rod guide 21 .

The oil seal 22 is formed by bonding rubber to a metal core material, and is arranged at one end in the axial direction of the outer cylinder 13 . As a result, leakage of oil or the like from the gap between the rod guide 21 and the main shaft portion 37 of the piston rod 15 to the outside is restricted. One axial side of the outer peripheral portion of the oil seal 22 abuts against the annular convex portion 59 of the rod guide 21 , and the other axial side abuts against the locking portion 28 of the outer cylinder 13 .

A metal rebound stopper 61 is fixed to a portion of the main shaft portion 37 of the piston rod 15 located within the inner cylinder 11 , in other words, a portion between the piston 18 and the rod guide 21 . The rebound stopper 61 has a perforated disc-shaped stopper portion 62 and an engaging portion 63 extending from the inner peripheral side of the stopper portion 62 to one side in the axial direction. It is fixed to the piston rod 15 by crimping it inwardly. That is, the rebound stopper 61 is fitted to the outer peripheral portion of the main shaft portion 37 of the piston rod 15 at its inner peripheral portion in such a posture that the engaging portion 63 before crimping faces the mounting shaft portion 38 side in the axial direction. In this state, the engaging portion 63 is crimped and engaged with the fixing groove 64 formed in the outer peripheral portion of the main shaft portion 37 , thereby fixing the main shaft portion 37 at a predetermined position in the axial direction. The outer diameter of the stopper portion 62 , which is the maximum outer diameter of the rebound stopper 61 , is smaller than the inner diameter of the inner cylinder 11 .

A cylindrical rebound cushion 66 is provided on the main shaft portion 37 of the piston rod 15 between the rebound stopper 61 and the rod guide 21 . The main shaft portion 37 of the piston rod 15 is inserted through the rebound cushion 66 radially inward. The rebound cushion 66 is arranged on the opposite side of the stopper portion 62 of the rebound stopper 61 from the engaging portion 63 in the axial direction.

The rebound cushion 66 is made of synthetic resin, for example, integrally molded from a thermoplastic polyester elastomer (TPEE) material. As shown in FIG. 2, the rebound cushion 66 includes an inner peripheral surface 71 that is a radially inner surface, an outer peripheral surface 72 that is a radially outer surface, and a pair of axial end surfaces that are surfaces on both ends in the axial direction. 73 and . The inner peripheral surface 71 , the outer peripheral surface 72 , and the pair of axial end surfaces 73 have the same center axis, and these center axes become the center axis of the rebound cushion 66 .

The inner peripheral surface 71 of the rebound cushion 66 has, at its axial center, a cylindrical inner peripheral end surface 81 which is positioned radially innermost on the inner peripheral surface 71 and also positioned radially innermost on the rebound cushion 66 . A pair of tapered surfaces 82 are formed at both ends in the axial direction, the diameter of which increases with distance from the inner peripheral end surface 81 in the axial direction.

The edge portion on the inner peripheral end surface 81 side in the axial direction of one tapered surface 82 is the edge portion on the tapered surface 82 side in the axial direction of the inner peripheral end surface 81 . The edge portion of the one tapered surface 82 opposite to the inner peripheral end surface 81 in the axial direction is the inner peripheral edge portion of the one axial end surface 73 . Further, the edge portion of the other tapered surface 82 on the side of the inner peripheral end surface 81 in the axial direction is the edge portion on the side of the tapered surface 82 in the axial direction of the inner peripheral end surface 81 . The edge portion of the other tapered surface 82 opposite to the inner peripheral end surface 81 in the axial direction is the inner peripheral edge portion of the other axial end surface 73 .

A pair of axial end surfaces 73 at both ends of the rebound cushion 66 in the axial direction are planar and extend perpendicularly to the central axis of the rebound cushion 66 .

The outer peripheral surface 72 of the rebound cushion 66 has the largest diameter at the central position of the rebound cushion 66 in the axial direction, and the diameter decreases with increasing distance from this central position in the axial direction of the rebound cushion 66 . In other words, the outer peripheral surface 72 of the rebound cushion 66 has a shape that bulges outward in the radial direction of the rebound cushion 66 . The outer peripheral surface 72 of the rebound cushion 66 has an edge portion on one axial side that is the outer peripheral edge portion of one axial end surface 73 , and an edge portion on the other axial side that is the other axial end surface 73 . It is the outer peripheral edge of the The outer peripheral surface 72 of the rebound cushion 66 has a constant arcuate cross-section on a plane including the central axis of the rebound cushion 66 regardless of the position of the rebound cushion 66 in the circumferential direction. The outer peripheral surface 72 of the rebound cushion 66 has mirror symmetry with respect to the center position in the axial direction.

The maximum outer diameter of the rebound cushion 66 in its natural state, that is, the maximum outer diameter of the outer peripheral surface 72 is smaller than the inner diameter of the inner cylinder 11 . When the rebound cushion 66 is provided on the piston rod 15 and arranged in the inner cylinder 11, the outer diameter of the rebound cushion 66 becomes the maximum outer diameter that provides a radial clearance between the rebound cushion 66 and the inner cylinder 11 if it does not come into contact with the rod guide 21. ing. In other words, if the rebound cushion 66 does not come into contact with the rod guide 21 , it forms an oil flow path over the entire length with the inner cylinder 11 . The rebound cushion 66 has an inner peripheral surface 71 facing the cylindrical outer peripheral surface 91 of the main shaft portion 37 of the piston rod 15 and an outer peripheral surface 72 facing the cylindrical inner peripheral surface 92 of the inner cylinder 11 .

The rebound cushion 66 has a satin-finished surface having a large number of minute unevennesses 101 distributed almost evenly. The entire surface of the rebound cushion 66 has a satin-like surface with a large number of minute unevennesses 101 distributed almost evenly. That is, the entire surface of the inner peripheral end surface 81 , the entire surface of each of the pair of tapered surfaces 82 , the entire surface of each of the pair of axial end surfaces 73 , and the entire surface of the outer peripheral surface 72 have a large number of fine irregularities 101 . It has a satin-like texture with a uniform distribution.

Here, taking the unevenness 101 formed on the inner peripheral end surface 81 in FIG. It has a concave portion 103 that is recessed and a convex portion 104 that protrudes outward from the main surface 102 in the radial direction of the main surface 102 . The recess 103 has a depth D from the main surface 102 of, for example, 0.1 mm to 0.5 mm, and an opening inner diameter φ1 at the main surface 102 of, for example, 0.1 mm to 0.5 mm. there is Moreover, the density of the distribution of the concave portions 103 is 10 to 27 per square centimeter. The convex portion 104 has a height H from the main surface 102 of, for example, 0.1 mm to 0.5 mm, and an outer diameter φ2 at the main surface 102 of, for example, 0.1 mm to 1 mm. . Further, the density of the distribution of the projections 104 is 10 to 31 per square centimeter. The unevenness 101 of the pair of tapered surfaces 82, the unevenness 101 of the pair of axial end surfaces 73, and the unevenness 101 of the outer peripheral surface 72 are similar.

As the piston rod 15 extends from the cylinder 14 , the rebound cushion 66 contacts the rod guide 21 and limits the extension of the piston rod 15 from the cylinder 14 together with the rebound stopper 61 , as shown in FIG. 5 . That is, when the piston rod 15 increases the amount of extension from the cylinder 14, the rebound cushion 66 is held by the rebound stopper 61 and moves together with the piston rod 15 to the rod guide 21 side. It is sandwiched between the guide 21 and the rebound stopper 61 and is elastically deformed, and when elastically deformed to the limit, the rebound stopper 61 and the piston rod 15 fixed thereto are stopped against the rod guide 21 . This position is the fully extended position of the piston rod 15 . The rebound cushion 66 is elastically deformed when the piston rod 15 approaches the fully extended position.

When the piston rod 15 is fully extended, one axial end surface 73 of the rebound cushion 66 abuts against the stopper portion 62 of the rebound stopper 61 and the other axial end surface 73 abuts against the rod guide 21 . will be elastically deformed such that the length of is shortened, thereby expanding in the radial direction. As a result, the outer peripheral surface 72 of the rebound cushion 66 contacts the inner peripheral surface 92 of the inner cylinder 11 , and the inner peripheral surface 71 contacts the outer peripheral surface 91 of the main shaft portion 37 of the piston rod 15 . At this time, since the surfaces of the rebound cushion 66, that is, the axial end surfaces 73 on both sides in the axial direction, the outer peripheral surface 72, and the inner peripheral surface 71, are all satin-like with fine irregularities 101, the surfaces The unevenness 101 secures the flow path of the oil flowing through. In other words, even when the piston rod 15 is fully extended, the rebound cushion 66 maintains the axial end surface 73 and the stopper without the unevenness 101 of the one axial end surface 73 contacting the stopper portion 62 of the rebound stopper 61 being completely crushed. 62, and the unevenness 101 of the other axial end surface 73 abutting against the rod guide 21 is not completely crushed, and the gap between this axial end surface 73 and the rod guide 21 is A radial flow path is ensured, and the axial flow path between the outer peripheral surface 72 and the inner cylinder 11 is secured without the irregularities 101 of the outer peripheral surface 72 abutting against the inner cylinder 11 being crushed completely, and the piston rod 15 The axial flow path between the inner peripheral surface 71 and the piston rod 15 is ensured without the unevenness 101 of the inner peripheral surface 71 abutting on the piston rod 15 being crushed completely.

Here, the rebound cushion 66 is molded with a mold having fine unevenness on the inner surface of the cavity, and the unevenness on the inner surface of the cavity is transferred to make the surface satin-like. Alternatively, the rebound cushion 66 is made into a satin finish by being molded with a normal mold and then spraying fine particulate resin on the surface. Alternatively, the rebound cushion 66 is molded with a normal mold and then buffed to have a satin finish.

The above-described Patent Documents 1 and 2 disclose a cylinder device in which the piston rod is provided with a rebound cushion that abuts against the rod guide according to the extension of the piston rod from the cylinder. When the rebound cushion comes into contact with the rod guide and deforms, it narrows the flow path of the oil flowing on the surface of the rebound cushion, which may result in flow path resistance.

On the other hand, in the cylinder device 10 of the embodiment, since the surface of the rebound cushion 66 has a satin-like surface with minute unevenness 101, even if the rod guide 21 is brought into contact with the rod guide 21 and deformed, the unevenness 101 does not affect the rebound cushion 66. To secure a flow path for an oil flowing on a surface and suppress narrowing of the flow path for the oil. Therefore, it is possible to prevent the rebound cushion 66 from acting as flow path resistance for the oil. Therefore, it is possible to suppress the occurrence of hydraulic lock at the time of so-called full extension.

In addition, since the entire surface of the rebound cushion 66 has a satin-like surface with minute unevenness 101, it is possible to secure a flow path for the oil flowing on the surface over the entire surface and to suppress narrowing of the flow path for the oil. Therefore, it is possible to further suppress the rebound cushion 66 from acting as flow path resistance for the oil.

The surface of the rebound cushion 66 is made satin-like by molding with a mold having minute unevenness 101, or is made satin-like by spraying, or satin-like by buffing. . Therefore, the surface of the rebound cushion 66 can be easily satin-finished.

The cylinder device of the first aspect of the above-described embodiment includes a cylinder in which a working fluid is sealed, a piston slidably fitted in the cylinder and partitioning the inside of the cylinder into two chambers, and the cylinder a rod guide provided on the opening side of the piston rod, one end of which is connected to the piston and inserted through the rod guide and the other end of which extends outside the cylinder; and the piston rod provided on the piston rod a rebound cushion that abuts against the rod guide in response to extension of the cylinder from the cylinder, the rebound cushion having a satin-like surface with minute unevenness. As a result, it is possible to prevent the rebound cushion from becoming a flow path resistance of the working fluid.

A cylinder device according to a second aspect of the embodiment is the cylinder device according to the first aspect, and the rebound cushion has a satin-like surface with minute unevenness on the entire surface.

A cylinder device according to a third aspect of the embodiment is the cylinder device according to the first or second aspect, wherein the rebound cushion is formed in a satin-like shape by being molded with a mold having minute unevenness, or , the satin-like surface is obtained by spraying, or the satin-like surface is obtained by buffing.

REFERENCE SIGNS LIST 10 cylinder device 14 cylinder 15 piston rod 16, 17 chamber 18 piston 66 rebound cushion 71 inner peripheral surface (surface)
72 outer peripheral surface (surface)
73 axial end surface (surface)
101 Unevenness

Claims (3)

a cylinder in which the working fluid is sealed;
a piston slidably fitted in the cylinder and partitioning the inside of the cylinder into two chambers;
a rod guide provided on the opening side of the cylinder;
a piston rod having one end connected to the piston and inserted through the rod guide and having the other end extending outside the cylinder;
a rebound cushion provided on the piston rod and abutting against the rod guide in accordance with extension of the piston rod from the cylinder;
The cylinder device, wherein the rebound cushion has a satin-like surface having fine irregularities. 2. The cylinder device according to claim 1, wherein the rebound cushion has a pear-skinned surface with minute irregularities on the entire surface. The rebound cushion is formed into the satin-like shape by being molded with a mold having fine irregularities, or is made into the satin-like shape by spraying, or is made into the satin-like shape by buffing. 3. The cylinder device according to claim 1 or 2.

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