JP2000018308A - Hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb the shock caused at the time of collision with a stopper rubber in a stroke edge of a piston rod, in a hydraulic shock absorber. SOLUTION: A piston 17 connected to a piston rod 19 is fitted into a cylinder 14. Orifice oil passages 28, 29 for communicating the inside of a cylinder 14 and a reservoir 15 with each other are provided on the side wall of the cylinder 14. Spiral grooves 30, 31 are provided on the inner circumferential surface of the cylinder 14. When the piston rod 19 is moved to the vicinity of a stroke edge, the orifice oil passage 28 or 29 is closed by the piston 17 to increase damping force. When the stroke of piston rod 19 is further performed, the groove 30 or 31 is bypassed the piston 17 to communicate between cylinder chambers 14a, 14b. Accordingly, at the stroke edge, it is possible to decrease shock degrees (a sum with damping force and the reaction force of the stopper rubber) at the time of collision with a stopper rubber by lowering the damping force. In addition, grooves 30, 31 are spirally formed, so that eccentric abrasion of the piston 17 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber used for a vibration damping device and a suspension device of a vehicle such as a railway vehicle.

[0002]

2. Description of the Related Art In a railway car, for example, a bogie on which wheels are mounted is elastically floated and supported in the left-right direction by a spring means, and a hydraulic shock absorber is mounted between the bogie and the car body. By absorbing the deflection of the truck following the deflection of the track by the spring means and the hydraulic shock absorber,
There is a vehicle equipped with a lateral vibration damping device that suppresses lateral vibration of a vehicle body and improves riding comfort.

An example of a hydraulic shock absorber mounted on this type of lateral vibration damping device will be described with reference to FIG. FIG.
As shown in FIG. 1, in the hydraulic shock absorber 1, a piston 4 to which a piston rod 3 is connected is slidably fitted in a cylinder 2 in which an oil liquid is sealed, and the cylinder inside the cylinder 2a is moved by the piston 4. , 2b. A reservoir 5 in which oil and gas are sealed is provided on the outer periphery of the cylinder 2. The cylinder chambers 2a and 2b are connected to the reservoir 5 via check valves 6 and 7, respectively. The check valves 6 and 7 are respectively connected to the cylinder chambers 2a and 2a from the reservoir 5 side.
Only the flow of the oil liquid to the 2b side is allowed.

The piston 4 has a relief valve 8 for permitting the flow of oil from the cylinder chamber 2a to the cylinder chamber 2b, and a relief valve for permitting only the flow of oil from the cylinder chamber 2b to the cylinder chamber 2a. A valve 9 is provided. An orifice passage 10 is provided in the side wall of the cylinder 2 near the end of the cylinder 2 on the side of the piston rod 3 to communicate the cylinder chamber 2a with the reservoir 5, and a cylinder chamber 2b is provided near the bottom of the cylinder 2 in the reservoir. An orifice passage 11 is provided for communication with the orifice 5.

[0005] With this configuration, during the extension stroke of the piston rod 3, the oil liquid in the cylinder chamber 2 a is pressurized and flows to the reservoir 5 through the orifice oil passage 10 in a low piston speed range. In the high-speed region of the piston speed, damping force is generated by flowing into the cylinder chamber 2b through the relief valve 8. At the same time, the oil liquid in the reservoir 5 opens the check valve 7 and flows into the cylinder chamber 2b. At this time, when the piston rod 3 extends to the vicinity of the stroke end on the extension side, the piston 4 closes the orifice passage 10 to increase the damping force, and a stopper rubber (see FIG. (Not shown).

During the compression stroke of the piston rod 3, the hydraulic fluid in the cylinder chamber 2b is pressurized, and passes through the orifice oil passage 11 through the orifice oil passage 11 in a low piston speed range.
To the relief valve 9 at high piston speeds.
The damping force is generated by flowing through the cylinder chamber 2a through the cylinder chamber 2a. At the same time, the oil liquid in the reservoir 5 opens the check valve 6 and flows into the cylinder chamber 2a. At this time, the piston rod 3
When is shortened to the vicinity of the stroke end on the contraction side, the piston 4 closes the orifice passage 11 to increase the damping force, thereby preventing and cushioning the collision with the stopper rubber (not shown) in the same manner as described above.

[0007] In this manner, by applying a damping force to the bogie's run-out, the vehicle body can be restrained from swaying, and by increasing the damping force near the stroke end of the piston rod 3. Thus, collision with the stopper rubber can be prevented and cushioned, and the riding comfort can be improved.

[0008]

However, the conventional hydraulic shock absorber 1 has the following problems. When the piston rod 3 moves near the stroke end on the extension side or the contraction side, the damping force is increased by closing the orifice passage 10 or 11 by the piston 4, so that the collision with the stopper rubber is suppressed. However, when colliding with the stopper rubber, the collision occurs with the damping force increased, so that the impact force at the time of the collision (the sum of the damping force of the hydraulic shock absorber 1 and the repulsion force of the stopper rubber) And the ride comfort is consequently degraded.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a hydraulic shock absorber which can reduce an impact at the stroke end of a piston rod upon collision with a stopper rubber. I do.

[0010]

In order to solve the above-mentioned problems, a first aspect of the present invention provides a cylinder filled with an oil liquid, a piston defining the inside of the cylinder as two chambers, and one end of the cylinder. A piston rod connected to a piston and having the other end extended to the outside of the cylinder, wherein the hydraulic shock absorber generates a damping force by controlling a flow of an oil liquid generated by sliding of the piston in the cylinder. A groove is provided on the inner peripheral surface of the cylinder, the groove being inclined with respect to the axis of the cylinder.

[0011] With this configuration, the piston slides in the cylinder, and the oil passage formed between the side wall and the groove of the piston bypasses the piston and connects the two chambers in the cylinder. As a result, the damping force is reduced. At this time, since the groove is inclined with respect to the axis of the cylinder, the sliding contact between the piston and the cylinder is not locally worn.

The invention according to a second aspect is characterized in that, in the configuration according to the first aspect, the groove is formed in a spiral shape.

[0013] With this configuration, the groove is spirally formed on the inner peripheral surface of the cylinder, so that the sliding contact portion of the piston with the cylinder is uniformly worn over the entire circumference.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

A first embodiment of the present invention will be described with reference to FIGS. 1 to 5, FIG. 8, and FIG. As shown in FIG. 1, the hydraulic shock absorber 12 has a double cylinder structure in which a cylinder 14 is inserted into a bottomed cylindrical outer cylinder 13.
A reservoir 15 is formed between 14 and the outer cylinder 13. At the bottom of the cylinder 14, a base valve 16 that partitions the inside of the cylinder 14 and the reservoir 15 is provided. An oil liquid is sealed in the cylinder 14, and an oil liquid and a gas are sealed in the reservoir 15.

A piston 17 is slidably fitted in the cylinder 14, and the piston 17 defines the inside of the cylinder 14 as two chambers, cylinder chambers 14a and 14b. piston
One end of a piston rod 19 is connected to 17, and the other end of the piston rod 19 is inserted into a guide seal 18 attached to the ends of the cylinder 14 and the outer cylinder 13 and extends to the outside.

As shown in FIG. 2, the base valve 16 has an oil passage 20 for communicating the cylinder chamber 14b with the reservoir 15.
Further, a check valve 21 is provided which allows only the flow of the oil liquid from the reservoir 15 side of the oil passage 20 to the cylinder chamber 14b side.

As shown in FIG. 3, the piston 17 is provided with oil passages 22, 23 for communicating between the cylinder chambers 14a, 14b. The oil passage 22 always blocks the flow of the oil liquid from the oil chamber 14b side to the oil chamber 14a side, and when the oil liquid in the oil chamber 14a reaches a predetermined pressure, the oil liquid is supplied to the oil chamber 14b side. A relief valve 24 for relief is provided. Oil passage 23
In this case, the flow of the oil liquid from the oil chamber 14a to the oil chamber 14b is always blocked, and when the oil liquid in the oil chamber 14b reaches a predetermined pressure, the oil liquid is relieved to the oil chamber 14a. A relief valve 25 is provided.

The guide seal 18 has an oil passage 26 communicating with the cylinder chamber 14a and the reservoir 15, and a reservoir for the oil passage.
A check valve 27 is provided to allow only the flow of the oil liquid from the 15 side to the cylinder chamber 14a side.

An orifice passage 28 is provided on the side wall of the cylinder 14 from the center to the guide seal 18 from the center to communicate the inside of the cylinder 14 with the reservoir 15. An orifice passage 29 that connects the inside of the cylinder 14 and the reservoir 15 is provided at a position 16 and beyond. These orifice passages 28, 29 communicate with the oil chambers 14a, 14b when the piston 17 is within a predetermined range in the center of the cylinder 14, and when the piston 17 moves beyond the predetermined range, the piston 17 Are arranged so as to be shut off from the oil chambers 14a and 14b which are in communication thereafter.

As shown in FIG. 4, the inner wall of the cylinder 14 extends from both ends of the cylinder toward the center, respectively.
Spiral groove 3 extending at an angle to the axis of cylinder 14
0 and 31 are provided. The grooves 30 and 31 are respectively provided so as to make at least one round around the cylinder 14.

When the piston 17 moves from the central portion of the cylinder 14 to the guide seal 18 during the extension stroke of the piston rod 19, the groove 28 on the guide seal 18 side overlaps the tip 17 with the piston 17. When the piston 17 closes the orifice passage 28 from the cylinder chamber 14a and then moves to the vicinity of the stroke end on the extension side of the piston rod 19, the piston 17 is bypassed between the piston 17 and the side of the cylinder chamber 14a. It is arranged so that an oil passage communicating between 14b is formed.

When the piston 17 moves from the center of the cylinder 14 to the base valve 16 during the contraction stroke of the piston rod 19, the tip of the groove 31 on the side of the base valve 16 overlaps with the piston 17. Further, when the piston 17 has moved to the vicinity of the contraction stroke end of the piston rod 19 after the orifice passage 29 has been shut off from the cylinder chamber 14b, the piston 17 is bypassed between the piston 17 and the side of the cylinder chamber 14a. It is arranged so that an oil passage communicating between 14b is formed.

The operation of the first embodiment configured as described above will now be described.

During the extension stroke of the piston rod 19, the relief valve 24,
25 and the check valve 27 of the guide seal 18 are closed to close the cylinder chamber.
The oil liquid in 14a is pressurized and flows to the reservoir 15 through the orifice oil passage 28. At this time, when the pressure of the oil liquid in the cylinder chamber 14a reaches the opening pressure of the relief valve 24, the relief valve 24 is opened and the oil liquid in the cylinder chamber 14a is relieved to the cylinder chamber 14b. In addition, the oil liquid corresponding to the increase in the volume of the cylinder chamber 14b due to the movement of the piston 17 flows into the cylinder chamber 14b from the reservoir 15 by opening the check valve 21 of the base valve 16.

As a result, the piston speed is low, and before the relief valve 24 is opened, a damping force having an orifice characteristic (damping force is substantially proportional to the square of the piston speed) is generated by the orifice passage 28, and the piston speed is reduced. When the pressure in the cylinder chamber 14a rises and the relief valve 24 is opened, a damping force having valve characteristics (damping force is proportional to the piston speed) is generated according to the opening degree. FIG. 8 shows the damping force characteristic (the relationship between the piston speed and the damping force) in this case.

When the piston rod 19 extends to a predetermined position near the stroke end on the extension side, the piston 17 closes the orifice passage 28 and thereafter the orifice passage 28 is closed.
28 is shut off from the cylinder chamber 14a. Thereby, the damping force is increased near the stroke end on the extension side of the piston rod 19, and the collision with the stopper rubber (not shown) can be suppressed.

Further, the piston 17 is moved and the spiral groove 30 is moved.
And an oil passage is formed between the side surface of the piston 17 and the groove 30. As shown in FIG. 5, when the piston rod 14 further extends to near the stroke end on the extension side, the piston 17 is bypassed by the oil passage formed by the side surface portion of the piston 17 and the groove 30, and the cylinder chambers 14a, The connection between 14b and the damping force decreases.

As described above, in the vicinity of the stroke end on the extension side of the piston rod 19, the orifice passage 28 is cut off from the cylinder chamber 14a to increase the damping force. As a result, the damping force can be appropriately reduced, and the impact force at the time of collision (the sum of the damping force of the hydraulic shock absorber 12 and the repulsive force of the stopper rubber) is reduced, and as a result, the riding comfort can be improved. .

During the contraction stroke of the piston rod 19, the relief valve 24,
25 and the check valve 21 of the base valve 16 are closed to close the cylinder chamber.
The oil liquid in 14b is pressurized and flows to the reservoir 15 through the orifice oil passage 29. At this time, when the pressure of the oil liquid in the cylinder chamber 14b reaches the opening pressure of the relief valve 25, the relief valve 25 is opened and the oil liquid in the cylinder chamber 14b is relieved to the cylinder chamber 14a. Incidentally, the oil liquid corresponding to the increase in the volume of the cylinder chamber 14a due to the movement of the piston 17 flows into the cylinder chamber 14a from the reservoir 15 by opening the check valve 27 of the guide seal 18.

As a result, the piston speed is low, and before the relief valve 25 is opened, a damping force having an orifice characteristic is generated by the orifice passage 29, and the piston speed is increased.
When the pressure in the cylinder chamber 14b rises and the relief valve 25 opens, a damping force having valve characteristics is generated in accordance with the degree of opening.
FIG. 8 shows the damping force characteristic (the relationship between the piston speed and the damping force) in this case.

Then, when the piston rod 19 is shortened to a predetermined position near the contraction stroke end, the piston 17 closes the orifice passage 29 and thereafter the orifice passage 29 is closed.
29 is shut off from the cylinder chamber 14b. Thereby, the damping force is increased near the stroke end on the contraction side of the piston rod 19, and it is possible to suppress the collision with the stopper rubber (not shown).

Further, the piston 17 moves and the spiral groove 31 is moved.
And an oil passage is formed between the side surface of the piston 17 and the groove 31. The piston rod 14
When the piston 17 is further shortened to the vicinity of the stroke end on the contraction side, the piston 17 is bypassed by the oil passage formed by the side surface of the piston 17 and the groove 31, and the cylinder chambers 14a and 14b are communicated with each other, and the damping force is reduced. .

In this way, as in the above-described extension stroke,
In the vicinity of the stroke end on the contraction side of the piston rod 19, the damping force once increased can be reduced when colliding with the stopper rubber, and the impact force at the time of collision can be reduced to improve ride comfort. .

FIG. 9 shows the relationship between the stroke of the piston rod 19 and the damping force when the piston speed is constant in the hydraulic shock absorber 12. In FIG. 9, point S ₁ indicates the stroke at which the extension-side orifice passage 28 starts to be closed by the piston 17, and point S ₂ indicates the stroke at which the extension-side groove 30 starts to bypass the piston 17. Point T ₁ indicates the stroke at which the contraction-side orifice passage 29 starts to be closed by the piston 17, and point T ₂ indicates that the contraction-side groove 31
Shows the stroke starting to bypass 17.

Since the grooves 30 and 31 are spirally formed on the inner peripheral surface of the cylinder 14, the sliding of the piston 17 makes sliding contact with the entire periphery of the piston 17, so that the piston ring (not shown) and the like are provided. The sliding contact portion of the piston 17 with the cylinder 14 is uniformly worn, so that leakage of the oil liquid due to uneven wear can be prevented, and a stable damping force can be generated.

The hydraulic shock absorber 12 does not require devices such as a limit switch, a solenoid control valve, and a controller, and is mechanically constructed, so that its operation is reliable and highly reliable. Further, unlike the conventional hydraulic shock absorber, it is only necessary to form a spiral groove on the inner peripheral surface of the cylinder, and there is no increase in the number of parts, so that the manufacturing cost does not increase.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment has a generally similar structure to the first embodiment except that the shape of the spiral groove formed on the inner peripheral surface of the cylinder is different. The same parts as those of the embodiment are denoted by the same reference numerals, and only different parts will be described in detail.

As shown in FIG. 6, in the hydraulic shock absorber 32 of the second embodiment, the base valve 16
On the side and the guide seal 18 side, grooves 33 and 34 each having the same shape as the spiral groove of the first embodiment are provided so as to cross each other two by two.

With this configuration, the same operation and effect as in the first embodiment can be obtained by bypassing the piston 17 with the two grooves 33 and 34.

Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is generally similar to the first embodiment except that the shape of the spiral groove formed on the inner peripheral surface of the cylinder is different. The same parts as those of the embodiment are denoted by the same reference numerals, and only different parts will be described in detail.

As shown in FIG. 7, in the hydraulic shock absorber 35 of the third embodiment, a helical groove 36 is provided on the inner peripheral surface at the center of the cylinder 14 so that the piston 17 When it is in the vicinity of the portion, the piston 17 is bypassed by the oil passage formed by the side surface portion of the piston 17 and the groove 36, and the communication between the cylinder chambers 14a and 14b is established.

With this configuration, the piston
When 17 is near the center of the cylinder 14, the damping force is small, and near the stroke end, the damping force is large.

In addition to the first to third embodiments, the damping force characteristics can be variously set by changing the arrangement and number of spiral grooves, and by changing the cross-sectional area of the grooves. Alternatively, the damping force can be changed by changing the flow passage area of the oil passage that bypasses the piston. In addition, even if the groove is not helical, if the groove is inclined with respect to the axis of the cylinder, local wear of the sliding contact portion of the piston with the cylinder can be prevented. By providing a plurality of grooves and making sliding contact with the entire circumference of the piston, wear of the piston can be made uniform over the entire circumference.

Further, in the above embodiment, as an example, the case where the present invention is applied to a hydraulic shock absorber mounted on a lateral vibration damping device of a railway vehicle has been described.
The present invention is not limited to this, and can be similarly applied to other hydraulic shock absorbers such as a hydraulic shock absorber (including a damping force-adjustable hydraulic shock absorber) mounted on a suspension device of an automobile.

[0046]

As described above in detail, the hydraulic shock absorber according to the first aspect of the present invention has a groove formed on the inner peripheral surface of the cylinder, the groove being inclined with respect to the axis of the cylinder. When the piston slides, an oil passage formed between the side wall and the groove of the piston bypasses the piston and communicates between the two chambers in the cylinder, thereby reducing the damping force. As a result, the damping force characteristics can be easily changed by the arrangement of the grooves, and the degree of freedom in setting the damping force characteristics can be increased. Thus, for example, by reducing the damping force at the time of collision with the stopper rubber near the stroke end of the piston rod, it is possible to reduce the impact at the time of collision. Also, since the groove is inclined with respect to the axis of the cylinder, the sliding contact between the piston and the cylinder will not be worn locally, preventing leakage of oil and stable damping force. Can be generated.

Further, in the hydraulic shock absorber according to the second aspect of the present invention, since the groove is formed in a spiral shape, the sliding contact portion of the piston with the cylinder can be uniformly worn over the entire circumference, so that uneven wear is achieved. , And a stable damping force can be generated.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a hydraulic shock absorber according to a first embodiment of the present invention.

FIG. 2 is an enlarged view showing a specific structure of a base valve of the hydraulic shock absorber of FIG.

FIG. 3 is an enlarged view showing a specific structure of a piston of the hydraulic shock absorber in FIG. 1;

FIG. 4 is a longitudinal sectional view of a cylinder of the hydraulic shock absorber in FIG. 1;

FIG. 5 is a longitudinal sectional view showing a state in which the piston rod extends to a stroke end on the extension side in the hydraulic shock absorber of FIG. 1;

FIG. 6 is a longitudinal sectional view of a hydraulic shock absorber according to a second embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a hydraulic shock absorber according to a third embodiment of the present invention.

FIG. 8 is a diagram showing a relationship between a piston speed and a damping force of the hydraulic shock absorber of FIG.

9 is a diagram showing damping force characteristics when the piston speed of the hydraulic shock absorber in FIG. 1 is constant.

FIG. 10 is a schematic view showing the structure of a conventional hydraulic shock absorber.

[Explanation of symbols]

 12,32,35 Hydraulic shock absorber 13 Cylinder 14a, 14b Cylinder chamber 17 Piston 19 Piston rod 30,31,33,34,36 Groove

Claims (2)

[Claims] 1. A cylinder filled with an oil liquid, a piston defining the inside of the cylinder as two chambers, and a piston rod having one end connected to the piston and the other end extending outside the cylinder. A hydraulic shock absorber that generates a damping force by controlling a flow of an oil liquid generated by sliding of a piston in the cylinder, wherein a groove that is inclined with respect to an axis of the cylinder is provided on an inner peripheral surface of the cylinder. A hydraulic shock absorber characterized in that: 2. The hydraulic shock absorber according to claim 1, wherein the groove is formed in a spiral shape.