JP2021127826A - Cylinder device - Google Patents

Abstract

To reduce occurrence of abnormal noise of a cylinder device.SOLUTION: A cylinder device includes: a cylinder 20; a piston 30 which is housed in the cylinder 20 and defines a rod side chamber and an opposite rod side chamber in the cylinder 20; and bearings 50 which are provided at an outer periphery of the piston 30 and slidably contact with an inner peripheral surface of the cylinder 20. The bearing 50 has: outer periphery chamfered parts 50b formed at end parts of an outer peripheral surface; and inner periphery chamfered parts 50d, each of which is formed facing the outer periphery chamfered part 50b and formed at an end part of an inner peripheral surface. An axial length of the inner periphery chamfered part 50d is larger than an axial length of the outer periphery chamfered part 50b.SELECTED DRAWING: Figure 3

Description

The present invention relates to a cylinder device.

Patent Document 1 discloses a fluid pressure cylinder including a cylindrical cylinder tube, a piston that separates a rod chamber and an end chamber in the cylinder tube, and a piston rod connected to the piston. The rod chamber and the end chamber communicate with the working fluid pressure source, respectively, and the piston rod expands and contracts by the working fluid pressure.

Japanese Unexamined Patent Publication No. 2013-53718

In the fluid pressure cylinder described in Patent Document 1, a bearing is interposed on the outer periphery of the piston, and the bearing is in sliding contact with the inner peripheral surface of the cylinder tube. In such a fluid pressure cylinder, when a load is applied to the piston in a direction inclined with respect to the axial direction of the cylinder tube, the end of the outer peripheral surface of the bearing comes into contact with the inner peripheral surface of the cylinder tube, and the outer peripheral surface of the bearing The surface pressure at the edges may increase. In this case, the oil film on the inner peripheral surface of the cylinder tube is scraped off by the bearing, the lubricity between the bearing and the inner peripheral surface of the cylinder tube deteriorates, and abnormal noise may occur.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the generation of abnormal noise in the cylinder device.

The present invention includes a cylinder, a piston housed in the cylinder and partitioning a fluid pressure chamber in the cylinder, and a bearing provided on the outer peripheral surface of the piston and in sliding contact with the inner peripheral surface of the cylinder. The bearing has an outer peripheral chamfering portion formed at the end portion of the outer peripheral surface and an inner peripheral chamfering portion formed opposite to the outer peripheral chamfering portion and formed at the end portion of the inner peripheral surface. The axial length of the inner peripheral chamfered portion is larger than the axial length of the outer peripheral chamfered portion.

In the present invention, even if a load is applied to the piston in a direction inclined with respect to the axial direction of the cylinder and the outer peripheral chamfered portion of the bearing comes into contact with the inner peripheral surface of the cylinder, the inner peripheral chamfered portion makes the outer peripheral chamfered portion. It is possible to suppress an increase in the acting surface pressure. This prevents deterioration of lubricity between the bearing and the inner peripheral surface of the cylinder.

The present invention is characterized in that the outer peripheral chamfered portion and the inner peripheral chamfered portion are formed over the entire circumference of the bearing.

In the present invention, it is possible to suppress an increase in the surface pressure acting on the outer peripheral chamfered portion regardless of the contact position between the outer peripheral chamfered portion of the bearing and the inner peripheral surface of the cylinder in the circumferential direction.

The present invention is characterized in that a plurality of bearings are provided on the outer peripheral surface of the piston, and an inner peripheral chamfered portion is formed at an end portion of the plurality of bearings facing the fluid pressure chamber.

In the present invention, it is possible to suppress an increase in the surface pressure at a location where the surface pressure acting on the bearing tends to increase when the piston and the bearing are tilted with respect to the cylinder.

The present invention is characterized in that the outer peripheral chamfered portion and the inner peripheral chamfered portion are formed at both ends of the outer peripheral surface and the inner peripheral surface of the bearing.

In the present invention, it is possible to suppress an increase in the surface pressure acting on both ends of the bearing.

The present invention is characterized in that the bearing is formed by injection molding a resin material.

In the present invention, even when the bearing is formed by injection molding a resin material and the sliding surface with the cylinder is curved in a concave shape, the inner peripheral chamfering portion deteriorates the lubricity between the bearing and the inner peripheral surface of the cylinder. Be prevented.

According to the present invention, it is possible to reduce the generation of abnormal noise in the cylinder device.

It is sectional drawing of the cylinder apparatus which concerns on embodiment of this invention. It is sectional drawing of a bearing. It is a partially enlarged view of FIG. It is sectional drawing of the cylinder apparatus which concerns on the comparative example of embodiment of this invention. It is sectional drawing of the bearing which concerns on the modification of embodiment of this invention.

Hereinafter, the cylinder device according to the embodiment of the present invention will be described with reference to the drawings. Hereinafter, a case where the cylinder device is a hydraulic cylinder 100 driven by using hydraulic oil as a working fluid will be described.

As shown in FIG. 1, the hydraulic cylinder 100 includes a cylindrical cylinder 20, a piston 30 housed in the cylinder 20 and partitioning a rod side chamber 1 as a fluid pressure chamber and an anti-rod side chamber 2 in the cylinder 20, and a piston 30. An annular bearing 50 provided on the outer peripheral surface 31 of the cylinder 20 and slidably contacting the inner peripheral surface of the cylinder 20 is provided.

The hydraulic cylinder 100 expands and contracts with hydraulic oil guided from the hydraulic source to the rod side chamber 1 or the anti-rod side chamber 2. The piston 30 is screwed and fastened to the piston rod 10. The outer peripheral surface 31 of the piston 30 is provided with a seal member 40 and an O-ring 41 that seal between the inner peripheral surface of the cylinder 20 and the outer peripheral surface 31 of the piston 30. The O-ring 41 presses the seal member 40 against the inner peripheral surface of the cylinder 20. As a result, the communication between the rod side chamber 1 and the anti-rod side chamber 2 through between the inner peripheral surface of the cylinder 20 and the outer peripheral surface 31 of the piston 30 is cut off.

On the outer peripheral surface 31 of the piston 30, two annular grooves 32 in which a part of the bearing 50 is housed are formed with the seal member 40 interposed therebetween. The bearing 50 is housed in each of the grooves 32 in a partially exposed state. The piston 30 slides in the cylinder 20 via the bearing 50.

The bearing 50 will be described with reference to FIGS. 1 to 3. FIG. 2 is a cross-sectional view of the bearing 50. FIG. 3 is a cross-sectional view of the bearing 50, the piston 30, and the cylinder 20, and the broken line shows the shape of the bearing 50 before deformation. In FIG. 3, the inclination of the bearing 50 and the piston 30 and the amount of deformation of the bearing 50 are exaggerated and greatly described.

As shown in FIG. 2, the bearing 50 has an outer peripheral chamfered portion 50b formed at both ends of the outer peripheral surface 50a and an inner peripheral chamfered portion 50d formed at both ends of the inner peripheral surface 50c. The outer peripheral chamfered portion 50b is formed in a curved surface shape, and the inner peripheral chamfered portion 50d is formed in a tapered shape. The outer peripheral chamfered portion 50b and the inner peripheral chamfered portion 50d are formed over the entire circumference of the bearing 50. The axial length of the inner peripheral chamfered portion 50d shown by B in FIG. 2 is formed to be larger than the axial length of the outer peripheral chamfered portion 50b shown by A in FIG. That is, the first boundary portion 50e, which is the boundary between the inner peripheral surface 50c and the inner peripheral chamfered portion 50d, is inside the second boundary portion 50f, which is the boundary between the outer peripheral surface 50a and the outer peripheral chamfered portion 50b. The radial length of the inner peripheral chamfered portion 50d shown by C in FIG. 2 is formed to be smaller than the radial depth of the groove 32 of the piston 30. Therefore, when the bearing 50 is housed in the groove 32, the axial end 50 g of the bearing 50 comes into contact with the inner surface of the groove 32, so that the bearing 50 is stably held in the groove 32. Further, as shown in FIG. 1, when the bearing 50 is accommodated in the groove 32, a space 60 is formed between the groove 32 and the inner peripheral chamfered portion 50d.

As shown in FIG. 3, in the hydraulic cylinder 100, when a load is applied to the piston 30 in a direction tilted with respect to the axial direction of the cylinder 20, the piston 30 and the bearing 50 are tilted with respect to the cylinder 20, and the outer peripheral surface of the bearing 50 is tilted. The bearing 50b comes into contact with the inner peripheral surface of the cylinder 20. At this time, when the surface pressure of the outer peripheral chamfering portion 50b increases, the oil film on the inner peripheral surface of the cylinder 20 is scraped off by the bearing 50, and the lubricity between the bearing 50 and the inner peripheral surface of the cylinder 20 deteriorates, resulting in abnormal noise. May occur.

However, in the hydraulic cylinder 100, the axial length of the inner peripheral chamfered portion 50d is formed to be larger than the axial length of the outer peripheral chamfered portion 50b. Therefore, when a load is applied to the piston 30 in a direction inclined with respect to the axial direction of the cylinder 20 and the outer peripheral chamfered portion 50b is in contact with the inner peripheral surface of the cylinder 20, the load received by the outer peripheral chamfered portion 50b from the cylinder 20 is , As shown by the arrow in FIG. 3, it acts toward the outside of the first boundary portion 50e of the inner peripheral chamfered portion 50d, that is, toward the space 60. Therefore, the bearing 50 is deformed so as to bend toward the space 60 with the vicinity of the first boundary portion 50e as a fulcrum. As a result, the load received by the outer peripheral chamfered portion 50b from the cylinder 20 can be dispersed. That is, even if the outer peripheral chamfered portion 50b of the bearing 50 comes into contact with the inner peripheral surface of the cylinder 20, a part of the bearing 50 bends toward the space 60 side, thereby suppressing an increase in the surface pressure of the outer peripheral chamfered portion 50b. be able to. Therefore, deterioration of lubricity between the bearing 50 and the inner peripheral surface of the cylinder 20 is prevented. Therefore, it is possible to reduce the generation of abnormal noise in the hydraulic cylinder 100.

Here, in order to facilitate understanding of the operation of the bearing 50, the bearing 150 according to the comparative example will be described with reference to FIG. FIG. 4 is a cross-sectional view of the bearing 150, the piston 30, and the cylinder 20, and the inclinations of the bearing 150 and the piston 30 are exaggerated and greatly described. In the bearing 150, outer peripheral chamfered portions 150b are formed at both ends of the outer peripheral surface 150a, and inner peripheral chamfered portions 150d having the same axial length as the outer peripheral chamfered portions 150b are formed at both ends of the inner peripheral surface 150c. NS.

As shown in FIG. 4, when a load is applied to the piston 30 in a direction tilted with respect to the axial direction of the cylinder 20, the piston 30 and the bearing 150 are tilted with respect to the cylinder 20, and the outer peripheral chamfering portion 150b of the bearing 150 is a cylinder. It contacts the inner peripheral surface of 20. In this state, the load received from the cylinder 20 by the outer peripheral chamfered portion 150b acts inside the boundary portion 150e of the inner peripheral chamfered portion 150d, that is, outside the space 60, as shown by the arrow in FIG. .. Therefore, the bearing 150 cannot be deformed so as to bend with the vicinity of the boundary portion 150e as a fulcrum, and the load received by the outer peripheral chamfering portion 150b from the cylinder 20 cannot be dispersed. Therefore, in the bearing 150 in which the outer peripheral chamfered portion 150b and the inner peripheral chamfered portion 150d having the same axial length are formed, even if the outer peripheral chamfered portion 150b comes into contact with the inner peripheral surface of the cylinder 20, the outer peripheral chamfering portion is taken. The increase in the surface pressure of the portion 150b cannot be suppressed.

On the other hand, in the bearing 50, the axial length of the inner peripheral chamfered portion 50d is formed to be larger than the axial length of the outer peripheral chamfered portion 50b. Therefore, even if the piston 30 and the bearing 50 are tilted with respect to the cylinder 20 and the outer peripheral chamfered portion 50b of the bearing 50 comes into contact with the inner peripheral surface of the cylinder 20, the space 60 is sufficiently large to allow the bearing 50 to bend. Therefore, an increase in the surface pressure of the outer peripheral chamfered portion 50b can be suppressed by bending a part of the bearing 50 toward the space 60 side. Therefore, deterioration of lubricity between the bearing 50 and the inner peripheral surface of the cylinder 20 is prevented. Therefore, it is possible to reduce the generation of abnormal noise in the hydraulic cylinder 100.

Further, since the inner peripheral chamfered portion 50d is formed in a tapered shape, the vicinity of the axial end portion of the bearing 50 becomes thinner in the radial direction. Therefore, when the outer peripheral chamfered portion 50b comes into contact with the inner peripheral surface of the cylinder 20, the vicinity of the axial end portion of the bearing 50 tends to bend toward the space 60 side, and the surface pressure of the outer peripheral chamfered portion 50b can be efficiently increased. Can be suppressed.

Further, the bearing 50 has the same area of the outer peripheral surface 50a, that is, the area of the sliding surface with the cylinder 20 as that of the conventional bearing. Therefore, the bearing 50 suppresses an increase in the surface pressure of the outer peripheral chamfered portion 50b when the outer peripheral chamfered portion 50b comes into contact with the inner peripheral surface of the cylinder 20 without reducing the area of the sliding surface with the cylinder 20. can do.

Further, in the present embodiment, the bearing 50 is formed by injection molding a resin. In the bearing 50 formed in this way, there is a high possibility that a sink mark will occur during manufacturing as compared with the bearing formed by cutting, and the sliding surface with the cylinder 20 will be curved in a concave shape due to the sink mark. Therefore, the outer circumference of the bearing 50 in which the sliding surface with the cylinder 20 is concavely curved as compared with the case where the outer peripheral chamfered portion of the bearing having a flat sliding surface with the cylinder 20 comes into contact with the inner peripheral surface of the cylinder 20. The increase in the surface pressure of the chamfered portion 50b becomes large. However, even when the sliding surface with the cylinder 20 is curved in a concave shape, the bearing 50 can suppress an increase in the surface pressure of the outer peripheral chamfered portion 50b by bending toward the space 60 side. The bearing 50 is not limited to the one made of resin, and may be made of metal.

Further, in the present embodiment, the inner peripheral chamfered portions 50d are formed at both ends of the bearing 50 so as to suppress an increase in the surface pressure acting on both ends of the bearing 50, but the present invention is not limited to this. When the piston 30 and the bearing 50 are tilted with respect to the cylinder 20, the end portion (region P or region Q shown in FIG. 1) of the outer peripheral surface 50a of the bearing 50 facing the rod side chamber 1 or the anti-rod side chamber 2 is the cylinder 20. There is a high possibility that the bearing 50 will come into contact with the inner peripheral surface, and the ends of the outer peripheral surface 50a of the bearing 50 (regions R and S shown in FIG. 1) are unlikely to come into contact with the inner peripheral surface of the cylinder 20. Therefore, when a plurality of bearings 50 are provided on the outer peripheral surface 31 of the piston 30 as in the present embodiment, the inner peripheral surface is at least at the end of the plurality of bearings 50 facing the rod side chamber 1 and the anti-rod side chamber 2. The bearing 50d may be formed. That is, the inner peripheral chamfered portion 50d may be formed at least at the end where the bearing 50 is likely to come into contact with the inner peripheral surface of the cylinder 20 when the piston 30 and the bearing 50 are tilted with respect to the cylinder 20. .. As a result, when the piston 30 and the bearing 50 are tilted with respect to the cylinder 20, the surface of the bearing 50 is likely to come into contact with the inner peripheral surface of the cylinder 20, that is, the surface where the surface pressure acting on the bearing 50 is likely to increase. The increase in pressure can be suppressed. Further, it is not necessary to form the inner peripheral chamfered portions 50d at all the end portions of the bearing 50, which facilitates the manufacture of the hydraulic cylinder 100.

Further, only one bearing 50 may be provided on the outer peripheral surface 31 of the piston 30, or a plurality of bearings 50 may be provided. In this case, as described above, the inner peripheral chamfered portion 50d may be formed at least at the end of the bearing 50 facing the rod side chamber 1 and the anti-rod side chamber 2.

Further, in the above embodiment, the outer peripheral chamfered portion 50b is formed in a curved surface shape, and the inner peripheral chamfered portion 50d is formed in a tapered shape. However, the present invention is not limited to this, and if the axial length of the inner peripheral chamfered portion 50d is formed to be larger than the axial length of the outer peripheral chamfered portion 50b, the shapes of the outer peripheral chamfered portion 50b and the inner peripheral chamfered portion 50d are formed. Can have any shape. For example, the inner peripheral chamfered portion 50d has a concavely curved curved surface as shown in FIG. 5 (a), a convexly curved curved surface as shown in FIG. 5 (b), and a curved surface as shown in FIG. 5 (c). Such a step may be used, and the outer peripheral chamfered portion 50b may also have the same shape as described above.

Further, the outer peripheral chamfered portion 50b and the inner peripheral chamfered portion 50d are formed by, for example, cutting, but the present invention is not limited to this, and the outer peripheral chamfered portion 50b and the inner peripheral chamfered portion 50d are directly formed by injection molding or the like. You may.

According to the above embodiment, the following effects are obtained.

Since the axial length of the inner peripheral chamfered portion 50d of the bearing 50 is formed to be larger than the axial length of the outer peripheral chamfered portion 50b, even if the outer peripheral chamfered portion 50b comes into contact with the inner peripheral surface of the cylinder 20. It is possible to suppress an increase in the surface pressure of the outer peripheral chamfered portion 50b. As a result, deterioration of lubricity between the bearing 50 and the inner peripheral surface of the cylinder 20 is prevented.

Further, since the area of the outer peripheral surface 50a of the bearing 50 is the same as that of the conventional bearing, the outer peripheral chamfered portion 50b comes into contact with the inner peripheral surface of the cylinder 20 without reducing the area of the sliding surface with the cylinder 20. It is possible to suppress an increase in the surface pressure of the outer peripheral chamfered portion 50b at the time of the operation.

Further, the bearing 50 has an outer circumference when the outer peripheral chamfered portion 50b comes into contact with the inner peripheral surface of the cylinder 20 even when a sink mark occurs during manufacturing such as resin injection molding and the sliding surface with the cylinder 20 is curved in a concave shape. It is possible to suppress an increase in the surface pressure of the chamfered portion 50b.

Further, since the outer peripheral chamfered portion 50b and the inner peripheral chamfered portion 50d are formed over the entire circumference of the bearing 50, the contact position between the outer peripheral chamfered portion 50b of the bearing 50 and the inner peripheral surface of the cylinder 20 in the circumferential direction. Regardless of this, an increase in the surface pressure of the outer peripheral chamfered portion 50b can be suppressed.

The configuration, operation, and effect of the embodiment of the present invention configured as described above will be collectively described.

The hydraulic cylinder 100 is provided on the cylinder 20, the piston 30 housed in the cylinder 20 and partitioning the rod side chamber 1 and the anti-rod side chamber 2 in the cylinder 20, and the outer peripheral surface 31 of the piston 30, and slides on the inner peripheral surface of the cylinder 20. The bearing 50 includes a contacting bearing 50, and the bearing 50 is formed so as to face the outer peripheral chamfering portion 50b formed at the end portion of the outer peripheral surface 50a and the outer peripheral chamfering portion 50b, and is formed at the end portion of the inner peripheral surface 50c. The inner peripheral chamfering portion 50d is provided, and the axial length of the inner peripheral chamfering portion 50d is larger than the axial length of the outer peripheral chamfering portion 50b.

In this configuration, even if a load is applied to the piston 30 in a direction inclined with respect to the axial direction of the cylinder 20 and the outer peripheral chamfered portion 50b of the bearing 50 comes into contact with the inner peripheral surface of the cylinder 20, the inner peripheral chamfered portion 50d , It is possible to suppress an increase in the surface pressure acting on the outer peripheral chamfered portion 50b. As a result, deterioration of lubricity between the bearing 50 and the inner peripheral surface of the cylinder 20 is prevented. Therefore, it is possible to reduce the generation of abnormal noise in the cylinder device.

The hydraulic cylinder 100 is characterized in that the outer peripheral chamfered portion 50b and the inner peripheral chamfered portion 50d are formed over the entire circumference of the bearing 50.

In this configuration, it is possible to suppress an increase in the surface pressure acting on the outer peripheral chamfered portion 50b regardless of the contact position between the outer peripheral chamfered portion 50b of the bearing 50 and the cylinder 20 in the circumferential direction.

A plurality of bearings 50 of the hydraulic cylinder 100 are provided on the outer peripheral surface 31 of the piston 30, and the inner peripheral chamfering portion 50d is formed at an end portion of the plurality of bearings 50 facing the rod side chamber 1 and the anti-rod side chamber 2. It is characterized by that.

In this configuration, it is possible to suppress an increase in the surface pressure at a position where the surface pressure acting on the bearing 50 tends to increase when the piston 30 and the bearing 50 are tilted with respect to the cylinder 20.

The outer peripheral chamfered portion 50b and the inner peripheral chamfered portion 50d of the hydraulic cylinder 100 are formed at both ends of the outer peripheral surface 50a and the inner peripheral surface 50c of the bearing 50.

With this configuration, it is possible to suppress an increase in the surface pressure acting on both ends of the bearing 50.

The bearing 50 of the hydraulic cylinder 100 is characterized in that it is formed by injection molding a resin material.

In this configuration, even when the bearing 50 is formed by injection molding a resin material and the sliding surface with the cylinder 20 is curved in a concave shape, the inner peripheral chamfered portion 50d allows the bearing 50 and the inner peripheral surface of the cylinder 20 to be connected to each other. Deterioration of lubricity is prevented.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configurations of the above embodiments. No.

Although the case where two bearings are provided in the above embodiment has been described, three or more bearings may be provided. Even in this case, an inner chamfered portion may be formed at least at the end of the bearing facing the rod side chamber and the anti-rod side chamber.

Although the case where the bearing is provided on the piston of the hydraulic cylinder has been described in the above embodiment, the bearing may be provided on the piston of the shock absorber.

1 ... Rod side chamber (fluid pressure chamber), 2 ... Anti-rod side chamber (fluid pressure chamber), 20 ... Cylinder, 30 ... Piston, 50 ... Bearing, 50a ... Outer peripheral surface, 50b ... outer peripheral chamfered portion, 50c ... inner peripheral surface, 50d ... inner peripheral chamfered portion, A ... outer peripheral chamfered portion 50b in axial length, B ... inner peripheral surface Axial length of chamfer 50d

Claims (5)

It ’s a cylinder device,
Cylinder and
A piston housed in the cylinder and partitioning the fluid pressure chamber in the cylinder,
A bearing provided on the outer peripheral surface of the piston and in sliding contact with the inner peripheral surface of the cylinder is provided.
The bearing is
An outer peripheral chamfer formed at the end of the outer peripheral surface,
It has an inner peripheral chamfered portion formed so as to face the outer peripheral chamfered portion and formed at an end portion of the inner peripheral surface.
A cylinder device characterized in that the axial length of the inner peripheral chamfered portion is larger than the axial length of the outer peripheral chamfered portion. The cylinder device according to claim 1.
The cylinder device, wherein the outer peripheral chamfered portion and the inner peripheral chamfered portion are formed over the entire circumference of the bearing. The cylinder device according to claim 1 or 2.
A plurality of the bearings are provided on the outer peripheral surface of the piston.
A cylinder device characterized in that the inner peripheral chamfered portion is formed at an end portion of a plurality of bearings facing the fluid pressure chamber. The cylinder device according to any one of claims 1 to 3.
A cylinder device characterized in that the outer peripheral chamfered portion and the inner peripheral chamfered portion are formed on both ends of the outer peripheral surface and the inner peripheral surface of the bearing. The cylinder device according to any one of claims 1 to 4.
The bearing is a cylinder device characterized in that it is formed by injection molding a resin material.

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