JPS6121438A - Shock absorber - Google Patents

Abstract

PURPOSE:To take foreign matter in concave portions and to prevent a sliding surface from being damaged by foreign matter by disposing concave portions in the sliding surface of a rod guide for a piston rod in such a manner not to be connected with at least one of both upper and lower edges of the sliding surface. CONSTITUTION:A shock absorber 1 comprises a cylinder 3 fixed in an outer shell 2, a piston rod 7 inserted in the cylinder 3 through a guide 6, and a piston 9 fixed to the lower end of the rod 7. In this arrangement, there are provided concave portions 10 in the sliding surfaces between the inner peripheral surface of the cylinder 3 and a piston ring 9 and between the outer peripheral surface of the piston rod 7 and a guide bush 6a. The concave portions 10 are formed with a depth and a width sufficient to accomodate cutting powder produced from the sliding surface or foreign matter in the operation oil. The concave portions 10 are disposed in such a manner not to be connected with an least one of both upper and lower edges of the sliding surface 10, for example, a plurality of circular cavities are uniformly disposed on the sliding surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a shock absorber, particularly to a shock absorber for a vehicle such as an automobile.

Conventional technology and its problems Generally, a cylindrical shock absorber used for the suspension of passenger cars, trucks, trucks, etc. has a cylinder with a much smaller diameter inserted and fixed inside the outer shell of the largest diameter, and a cylinder with a smaller diameter is inserted and fixed at the upper end of the cylinder. An oil seal and pace pulp are provided at the lower end of the cylinder, and a piston rod is inserted into the rod guide provided below the oil seal of the cylinder via a guide bushing, and the piston rod is inserted into the cylinder near the inner end. A piston is fixedly installed in sliding contact with the circumferential surface and divides the inside of the cylinder into upper and lower compartments. Hydraulic oil is stored inside the cylinder and between the cylinder and the outer shell, and the amplitude of the relative movement between the cylinder and piston rod caused by vehicle vibration is controlled by the flow resistance of the hydraulic oil passing through the orifice provided in the piston and the base valve. It has the function of damping the leaf valve by the resistance when pushing it open. That is, in a shock absorber, a sliding relationship exists between the inner peripheral surface of the cylinder and the piston, and between the piston rod and the guide bushing that supports the piston.

In conventional shock absorbers, the frictional resistance at the sliding parts tends to increase with long-term use, which changes the original design conditions, worsening the ride comfort of the car and reducing steering stability. A problem has arisen with reduced performance.

According to research conducted by the present inventors, these causes are thought to be as follows. In order to prevent damage to the inner circumferential surface of the cylinder, the piston is in sliding contact with the cylinder by a piston ring fitted into a groove provided on the outer circumference of the piston. The surface is made relatively soft by forming a layer or by using a material made of reinforced resin. However, cylinders are often made of drawn steel tubes due to cost advantages, and their hardness is around Hv 160, and when observed microscopically, there are minute irregularities of several microns on the surface, making it difficult to compare. It has a rough surface. Due to long-term sliding, the protrusions on this rough surface are shaved off and fall off as metal powder, but if these particles enter between the sliding surface of the piston ring and the piston ring, the cutting action will further damage the inner peripheral surface of the cylinder and cause sliding resistance. Particularly in the case where the piston ring is made of resin, the fallen metal powder gets stuck in the piston ring and constantly rubs against the inner circumferential surface of the cylinder, promoting the generation of metal powder, resulting in a repeating vicious cycle. In addition, foreign matter often exists in the system from the beginning due to chips during manufacturing or carelessness when injecting hydraulic oil. The situation of tilting is the same in the case of the guide bush and piston rod, both of which damage the sliding surfaces and increase frictional resistance.

Object and Structure of the Invention The present invention is directed to the above-mentioned metal powder generated at the sliding contact portion of a shock absorber that enters between the sliding surfaces and causes grinding damage to the inner peripheral surface of the cylinder or the surface of the piston rod. The purpose is to prevent the vicious cycle that encourages the occurrence of such outbreaks.

The purpose of this is to guide a piston rod slidably installed in a cylinder by a rod guide, and also to A shock absorber is provided with a concave portion in the sliding surface of the id with the piston rod and/or the sliding surface of the piston with the cylinder, and the concave portion is arranged so that at least one of the upper and lower edges of the sliding surface does not communicate with the other. This can be achieved by

Furthermore, if a guide bush is fitted to the sliding surface of the rod and the piston rod and/or a piston ring is fitted to the sliding surface of the piston and the cylinder, a low-cost and highly accurate shock absorber can be obtained.

More specifically, a cylinder with a much smaller diameter is fixed within a larger diameter outer shell, and the two are communicated at the upper and lower ends through oil seals and base valves each having an orifice. Further, a piston rod is inserted into the guide fixed in the cylinder so as to be slidable in the axial direction via a guide, and a piston having an orifice is fitted on the outer periphery of the piston rod. The piston ring is slidably fixed to the inner circumferential surface of the cylinder in the axial direction through a piston ring, and hydraulic oil is stored in the cylinder and in the space between the cylinder and the outer shell. A shock absorber that damps relative vibrations between a piston rod and the inside of a cylinder by the flow resistance of hydraulic oil passing through the shock absorber, wherein a recess is provided on the sliding surface of the piston ring and/or guide bushing, and the recess is provided with a sliding surface. This is achieved by a shock absorber characterized in that it is arranged so that at least one of the upper and lower edges of the surface does not communicate with each other.

Specific Means for Solving the Problems The present invention will be explained in more detail below based on embodiments shown in the drawings.

FIG. 2 is a schematic side sectional view of the shock absorber 1 of the present invention, in which a small-diameter cylinder 3 is fixed coaxially within a large-diameter outer shell 2.

An oil seal 4 is tightly fitted to the upper end of the cylinder 3, and a Nihahesbulg 5 is tightly fitted to the lower end to separate the outer shell 2 and the cylinder 3. A rod guide 6 is fixed in the cylinder 3 directly below the oil seal 4, and a piston rod 7 is inserted into the cylinder 3 from above in the axial direction through this center hole. A guide pusher 68 that comes into sliding contact with the piston rod 7 is fitted and fixed into the inner circumferential surface of the center hole of the guide 6 . Further, a piston 9 having an orifice 8 is fixedly installed near the inner end of the piston rod 7, and a piston ring 9a that is in sliding contact with the inner circumferential surface of the cylinder 3 is fitted onto the outer circumferential surface of the piston 9. The piston 9 divides the inside of the cylinder 3 into upper and lower compartments.・Furthermore, hydraulic oil is stored inside the cylinder 3 and in the space between the cylinder 3 and the outer shell 2, so that vibration displacement in the axial direction to the cylinder that is transmitted to the piston rod 7 due to vibrations of the vehicle is absorbed within the cylinder 3. , resulting in a change in the volume of the upper and lower compartments of the hydraulic fluid and the resulting flow resistance as it moves through the orifice 8 or the base valve 5, damping the amplitude of the vibrations.

The front guide 6 has a function of correctly regulating vertical displacement of the piston rod 7 in the axial direction.

It will be understood that in the above configuration, a sliding relationship occurs between the inner circumferential surface of the cylinder 3, the piston ring 9a, and the outer circumferential surface of the piston rod (7) and the guide bush 6a. In the present invention, as shown in FIGS. 1a to 1d, a piston ring 9a, a guide valve, a
A feature is that a recess 10 is provided on the sliding surface of L6a.

This recess 10 is formed by metal powder generated from the sliding surface, especially the inner peripheral surface of the cylinder, due to friction during sliding, cutting powder generated during manufacturing and assembly of the shock absorber and remaining inside it, or when hydraulic oil is injected. It is necessary to have a depth and width that can accommodate mixed foreign matter etc. with sufficient margin. In addition, the shape and arrangement can be selected as necessary, but
To avoid deteriorating the oil sealing properties of these sliding surfaces, grooves that are open at both ends should be avoided so that the upper and lower edge surfaces communicate with each other. A preferred shape and arrangement is one in which a plurality of planar substantially circular depressions are arranged substantially evenly over the entire surface of the sliding surface (first
a), a method with multiple rows of parallel grooves arranged in the circumferential direction (Fig. 1b), a method with multiple rows of parallel grooves arranged in the circumferential direction (Fig. 1c), and a method from near the upper to near the lower edge. For example, there is a groove provided diagonally in the circumferential direction and open in one direction.

In the shock absorber of the present invention having such a structure, metal powder that falls off from the sliding surface inside the cylinder, particularly from the inner circumferential surface of the cylinder that makes sliding contact with the piston ring due to long-term use, is removed from the recess provided in the sliding surface. Since it is taken into the inner circumferential surface of the cylinder 10, it is pressed against the sliding surface between the piston ring 9 and the inner circumferential surface of the cylinder 3, like a conventional shock absorber, and may further damage the inner circumferential surface of the cylinder or damage the piston. This phenomenon can be avoided by inserting it into the ring 9a and constantly performing the -1yllJ+ action. Further, when foreign matter that has been mixed into the cylinder since the beginning of use or newly mixed into the hydraulic oil as described above reaches the sliding surface due to the circulation of the hydraulic oil, it is also taken into the recess 10. Therefore, secondary damage to the sliding contact surface due to these foreign substances is prevented. Furthermore, since the four parts 10 also function as a type of oil reservoir and are always filled with hydraulic oil, seizure of the sliding surfaces can be prevented.

Effects of the Invention As detailed above, according to the present invention, since four parts are provided on the sliding contact surface between the piston and the cylinder and/or the sliding contact surface between the front guide and the piston rod, foreign matter such as metal powder can be trapped therein. It is possible to prevent contact with the sliding surface, and therefore, it is possible to prevent scratches on the inner peripheral surface of the cylinder and the outer peripheral surface of the piston rod caused by the cutting effect of the metal powder.

Further, since the recess is formed as a discontinuous closed groove or recess so as not to communicate between the upper and lower edges of the sliding surface, the oil sealing effect of the stone ring and guide bushing is not impaired. This avoids an increase in sliding resistance due to long-term use of the shock absorber, thereby increasing its lifespan.

[Brief explanation of the drawing]

1a to 1d are developed views of the sliding surfaces of the piston ring or guide bush of the present invention, and FIG. 2 is a schematic side sectional view of a shock absorber to which the present invention is applied. 1-... Shock absorber, 2... Outer shell,
3... Cylinder, 4... Oil seal, 5... Base valve, 6... Rod guide, 6a... Guide bush, 7... Piston rod, 8... Orifice, 9... ...Piston, 9a...Piston ring, 1
0... Concavity. Figure 1Q Figure 1b Figure 1C Figure 1d

Claims (1)

[Scope of Claims] 1. A shock absorber in which a piston rod slidably housed in a cylinder is guided by a rod guide, and includes a piston in sliding contact with the inner circumferential surface of the cylinder near the inner end of the piston rod, A recess is provided in the sliding surface of the rod guide with the piston rod and/or the sliding surface of the piston with the cylinder, and the recess is arranged so that at least one of the upper and lower edges of the sliding surface does not communicate with each other. A shock absorber characterized by: 2. The shock absorber according to claim 1, wherein a guide bush is disposed on the sliding surface of the rod guide with respect to the piston rod. 3. The shock absorber according to claim 1 or 2, wherein a piston ring is fitted on a sliding surface of the piston with respect to the cylinder. 4. The shock absorber according to claim 1, wherein the recessed portion of the sliding surface is a plurality of planar substantially circular depressions. 5. The shock absorber according to claim 1, wherein the recessed portion of the sliding surface is a groove provided along the circumferential direction of the sliding surface. 6. The shock absorber according to claim 2, wherein a plurality of said grooves are provided.