JPH061879U - Hydraulic shock absorber - Google Patents

Abstract

(57) [Abstract] [Purpose] Even if the oil temperature changes and the oil viscosity changes, the damping force does not change and no abnormal noise is generated. A piston rod 11 is movably inserted into a cylinder 3 via a piston 12, the piston defines two upper and lower oil chambers 5 and 10 in the cylinder, and a lower oil chamber is a reservoir 14 via a base valve. In the hydraulic shock absorber communicating with the piston body 7, the piston body 7 is hollow, the collars 2 and 8 are provided inside the piston body, and upper and lower oil chambers are provided between the outer circumference of the collar and the inner circumference of the piston body. It is assumed that the damping force generating gaps 19 and 21 that communicate with each other are formed, and that the collar is made of a material having a large coefficient of thermal expansion.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hydraulic shock absorber that is interposed between a vehicle body and an axle of a vehicle to damp vibrations from the road surface.

[0002]

[Prior art]

 In this type of hydraulic shock absorber, a piston rod is movably inserted into a cylinder via a piston, the piston defines two upper and lower oil chambers in the cylinder, and a base valve is provided at the bottom of the cylinder. Things are known.

Generally, a cylinder is provided with a communication port that connects two upper and lower oil chambers, and a damping valve is openably and closably provided at the outlet end of this port. Is occurring.

Similarly, the base valve is provided with a port that connects the lower oil chamber and the reservoir, and a damping valve is openably and closably provided at the outlet end of this port so that the oil in the lower oil chamber is compressed from the port when compressed. Open to generate damping force on the compression side.

[0005]

[Problems to be solved by the device]

 In the above conventional hydraulic shock absorber, for example, when the oil temperature rises at high temperature, the viscosity of the oil decreases and the damping force decreases, so that the viscosity of the oil changes due to the change in the oil temperature, and thus the damping force changes. .

Further, since the damping force is generated when the damping valve is opened from the port, there is a problem that abnormal noise is generated due to the damping valve.

Therefore, an object of the present invention is to provide a hydraulic shock absorber in which the damping force does not change even when the oil temperature changes and the oil viscosity changes, and abnormal noise does not occur.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the structure of the present invention is such that a piston rod is movably inserted into a cylinder through a piston, the piston defines two upper and lower oil chambers in the cylinder, and a lower oil chamber is a base valve. In the hydraulic shock absorber communicating with the reservoir via the piston, the piston body is made hollow, and a collar is provided inside the piston body, and upper and lower oil is provided between the outer circumference of the collar and the inner circumference of the piston body. It is characterized in that a gap for communicating a chamber is formed to generate a damping force, and the collar is made of a material having a large coefficient of thermal expansion.

[0009]

[Action]

 During the expansion and contraction operation, the oil passes through the gap between the collar and the piston body, and the flow resistance, that is, the choke throttle, produces a damping force.

When the oil temperature rises, the collar expands and narrows the gap, so even if the viscosity of the oil decreases, the reduction of the damping force is prevented. Conversely, even if the oil temperature decreases and the viscosity of the oil increases, the color decreases. Prevents the damping force from increasing because it contracts and enlarges the gap.

Since the oil flows through the gap as a choke and the damping valve is not used, no abnormal noise is generated.

[0012]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

In FIG. 1, the right half shows the expanded state and the left half shows the compressed state.

A piston rod 11 is movably inserted into a cylinder 3 via a piston 12, and a hollow piston main body 7 as a partition wall member constituting the main body of the piston 12 has two upper and lower oil chambers 10 inside the cylinder 3. , 5 are divided.

The piston body 7 includes a hollow portion 24 and a port 25, and the hollow portion 24 and the port 25 communicate the upper and lower oil chambers 10 and 5, respectively.

An outer tube 13 is concentrically provided outside the cylinder 3, and a reservoir 14 is defined inside the outer tube 13.

A base valve 15 is provided inside the lower part of the cylinder 3, and a hollow valve case 1 which is a partition member forming the main body of the base valve 15 partitions a lower oil chamber 5 and a reservoir 14.

The valve case 1 includes a hollow portion 26 and a port 27, and the hollow portion 26 and the port 27 connect the lower oil chamber 5 and the reservoir 14 to each other.

Inside the piston body 7, a collar 8 formed of a material having a coefficient of thermal expansion higher than that of the piston body 7, for example, synthetic resin, aluminum or the like is arranged so as to be movable up and down. And a gap 19 for generating a damping force along the axial direction is formed between the inner circumference of the piston main body 7 and the gap 19 is open to the upper oil chamber 10 and communicates with the lower oil chamber 5 via the port 25. ing.

The collar 8 is vertically guided by a guide 29, and is normally pushed by the lower seat 34 by a spring 32 arranged in the hollow portion 29.

The collar 8 is provided with a hollow portion 29, a port 30 and a notch 31 on the upper side, and thereby has a function of a check valve.

The valve case 1 of the base valve 15 has a port 27 connecting the lower oil chamber 5 and the reservoir 14 and a notch 22.

Inside the hollow portion 26, which is the inner side of the valve case 1, a color 2 that moves up and down along a guide 33 is movably arranged, and between the outer circumference of the collar 2 and the inner circumference of the valve case 1. A gap 21 for generating a damping force is provided along the axial direction.

The gap 21 opens to the lower oil chamber 5 and communicates with the reservoir side via the port 27.

The collar 2 has a port 35 and is normally pressed by a spring 17 against a lower seat 36.

The collar 2 has a function of a check valve.

Further, the collar 2 is formed of a material having a coefficient of thermal expansion higher than that of the valve case.

During the extension operation, the collar 8 is pushed by the seat 34 and closes the port 30, so that the oil in the upper oil chamber 10 flows out to the lower oil chamber 5 through the gap 19 and the choke effect of the gap 19 is generated. An extension side damping force is generated by the oil, and the oil corresponding to the discharge volume of the piston rod 11 is sucked into the lower oil chamber 5 by pushing up the collar 2 from the port 27 from the reservoir 14.

At the time of compression, the oil in the lower oil chamber 5 pushes up the collar 8 from the port 25 and flows out to the upper oil chamber 10, and the amount of oil that has penetrated the piston rod 11 is equal to the space 21 of the base valve 15 and the port. It flows out to the reservoir 14 through the notch 27 and the notch 22, and the compression resistance is generated by the flow resistance of the gap 21.

Even if the oil temperature changes, for example, the oil temperature rises and the viscosity of the oil decreases, the collars 2 and 8 expand as the oil temperature rises, and the gaps 21 and 19 are narrowed. Therefore, the decrease in damping force is prevented, and when the oil temperature drops as well, the collars 2 and 8 contract and the gaps 21 and 19 become large, so the damping force does not increase and a constant damping force is always generated. .

FIG. 2 shows another embodiment of the present invention.

A check valve is provided on the upper part of the collar so as to be openable and closable, and the other structures, functions and effects are the same as those of the embodiment shown in FIG. The same structure is denoted by the same reference numeral, and the details are omitted.

A collar 8 is provided inside the piston body 7, and a gap 19 is formed between the outer circumference of the collar 8 and the inner circumference of the piston body 7.

The collar 8 is formed with an upper oil chamber 10 and an axial port 30a opening to the port 25, and a check valve 38 urged by a spring 37 is provided at the upper opening end of the port 30a so as to be openable and closable. ing.

The collar 8 is made of a material having a larger thermal expansion force than the piston body 7.

During the extension operation, the oil in the upper oil chamber 10 flows out into the lower oil chamber 5 through the gap 19 (see the second left cross section), and during the compression operation, the lower oil chamber 5 as shown in the right cross section of FIG. Oil flows out of the ports 25 and 30a into the upper oil chamber 10 by opening the check valve 38.

The configurations of the collar 8 a and the check valve 38 may be applied to the base valve 15.

FIG. 3 shows another embodiment of the present invention in which the collar itself has a check valve function.

The collar 8 has the same structure as that of the embodiment shown in FIG. 1, and is vertically movably inserted while being guided by the guide 28 in the hollow portion 24 of the piston body 7, and is normally pushed by the lower seat 34 by the spring 32. ing.

A port 25 opening to the upper oil chamber 10 is formed in the upper part of the piston body 7.

During expansion, the collar 8 is pushed downwards to close the port 30, the oil in the upper oil chamber 10 flows out to the lower oil chamber 5 through the gap 21, and during compression operation, the oil in the lower oil chamber 5 is compressed. Is pushed up, the port 30 is opened, and it flows out from the hollow portion 29 to the upper oil chamber 10 via the port 25a.

Other functions and effects are the same as those of the embodiment shown in FIG.

The structure shown in FIG. 3 can be applied to the base valve 15.

[0045]

[Effect of device]

 According to the present invention, the following effects can be obtained.

Since a collar having a large coefficient of thermal expansion is provided inside the piston body and a gap for generating a damping force is provided between the collar and the piston body, the damping force is generated by the flow resistance of the oil flowing through the gap during extension. Occurs.

Since the collar expands or contracts according to the change in the oil temperature and the size of the gap changes, the damping force does not change even if the viscosity of the oil changes due to the change in the oil temperature.

Damping force of the choke effect is generated by utilizing the gap, and since no damping valve is used, generation of abnormal noise can be prevented.

Since the collar is provided inside the piston body, the size of the cylinder itself does not change, and since design management of only the internal structure of the piston is sufficient, workability is good and it is advantageous in terms of cost.

Since the collar is provided inside the piston body, the piston body itself does not need to be formed long in the axial direction, and the effective stroke is increased.

Since the temperature characteristic of the damping force is compensated by the difference in thermal expansion between the piston body and the collar, the degree of freedom in material setting is high.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a hydraulic shock absorber according to an embodiment of the present invention.

FIG. 2 is a sectional view of a piston portion according to another embodiment of the present invention.

FIG. 3 is a sectional view of a piston portion according to another embodiment of the present invention.

[Explanation of symbols]

 2,8 Color 3 Cylinder 5,10 Oil chamber 7 Piston body 11 Piston rod 12 Piston 14 Reservoir 19,21 Gap

Claims (2)

[Scope of utility model registration request] 1. A piston rod is movably inserted into a cylinder via a piston, the piston defines two upper and lower oil chambers in the cylinder, and the lower oil chamber communicates with a reservoir via a base valve. In the hydraulic shock absorber, the piston body is configured to be hollow, a collar is provided inside the piston body, and a gap for generating damping force that connects the upper and lower oil chambers is provided between the outer circumference of the collar and the inner circumference of the piston body. A hydraulic shock absorber, wherein the hydraulic shock absorber is formed and the collar is formed of a material having a large thermal expansion coefficient. 2. The hydraulic shock absorber according to claim 1, wherein the collar has a check valve function.