JP2002013582A - Damping force control type hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix both damping forces on extension and compression sides at a medium in the event of failure, in a damping force control type hydraulic shock absorber having opposite characteristics on the extension side and on the contraction side in terms of damping force. SOLUTION: Fluid flow of oil liquid entailed between an upper chamber port 14 and a lower chamber port 15 and between the lower chamber port 15 and a reservoir port 16 by means of telescopic motion of a piston rod 6 is controlled by damping valves 19, 20 on the extension and the compression sides and the damping force is produced. Usually, a spool 26 is driven by a proportional solenoid action 41, and the damping force with reversal characteristic is obtained by controlling the flow path areas of ports 27, 33 by lands 34, 35. In the event of failure, the spool 26 moves rightwards by a spring 44 and is communicated with a bypass port 17 by making the flow path area of the port 27 as medium by a land 37, and then a flow path area of a port 32 is made as medium. Thereby, the damping forces on the extension and compression sides can be fixed at medium range, and stability and ride comfort of a car body can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping force-adjustable hydraulic shock absorber mounted on a vibration damping device and a suspension device of a railway vehicle or the like.

[0002]

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

In such a roll damping device, various sensors detect a lateral acceleration of a vehicle body, a relative speed between a bogie and a vehicle body, and the like, and a controller controls a damping force of a hydraulic shock absorber in real time based on these. By doing so, a so-called semi-active damper control is known which effectively suppresses the roll of the vehicle body.

When such semi-active damper control is performed, one of the damping forces on the extension side and the contraction side of the piston rod of the hydraulic shock absorber is large (hard) and the other is small (soft).
It is known that a damping force-adjustable hydraulic shock absorber having a so-called inversion characteristic in which one is small (soft) and the other is large (hard) is suitable.

[0005]

However, the conventional damping force adjusting type hydraulic shock absorber having the above-described reversal characteristics has the following problems. In general, in a roll damping device, when the damping force of the hydraulic shock absorber cannot be adjusted due to a failure of a controller or the like (at the time of a failure), the damping force of the hydraulic shock absorber is stabilized as much as possible. Is desirably fixed to the hard side (fail safe).
However, in the damping force adjusting type hydraulic shock absorber having the reversal characteristic, when the power supply to the actuator is cut off due to a failure of the controller or the like, the valve body of the damping force adjusting valve is displaced to one side by the urging force of the return spring or the like. Therefore, one of the extension side and the contraction side is fixed in a hard state and the other is fixed in a soft state. In this state, since the vehicle body tends to be displaced toward the soft side due to vibration, there is a problem from the viewpoint of stabilizing the vehicle body.

Therefore, a fail-safe valve is provided to close the oil passages on the extension side and the contraction side of the hydraulic shock absorber at the time of a failure,
There has been proposed a damping force-adjustable hydraulic shock absorber in which both the expansion-side and contraction-side damping force characteristics are fixed to the hard side when a failure occurs (see Japanese Patent Application Laid-Open No. 7-269627). However, in the above-mentioned publication, it is necessary to separately provide a fail-safe valve, which complicates the structure,
Since the damping forces on the extension side and the contraction side are fixed to the hard side, there arises a problem that the ride quality is extremely deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and in a reversing characteristic damping force adjustable hydraulic shock absorber using a spool, the damping force on the extension side and the contraction side at the time of a failure is set to a desired value. An object of the present invention is to provide a damping force-adjustable hydraulic shock absorber that can be fixed.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the invention according to claim 1 comprises a cylinder filled with an oil liquid, a piston slidably fitted in the cylinder,
One end is connected to the piston, and the other end is a piston rod extended to the outside of the cylinder, and an expansion-side oil passage that communicates with the cylinder to circulate an oil liquid during the expansion stroke of the piston rod and a contraction stroke. A contraction-side oil passage through which the oil liquid flows, a spool valve for adjusting the flow passage area of the extension-side oil passage and the contraction-side oil passage, and an actuator for driving a spool of the spool valve; When one of the flow path areas of the expansion side and the contraction side oil path is large, the other is small, and when one is small, the other is large, and in the damping force adjusting hydraulic shock absorber, the spool valve has a thrust of the actuator. A spring means for moving the spool to one side when lost, and one of the extension-side and contraction-side oil paths having a smaller flow passage area when the spool moves to one side. By Scan, and wherein the spool is provided with a bypass passage that opens when moving to one side.
With this configuration, when the thrust of the actuator is lost, the spool is moved to one side by the spring means, and one of the expansion-side and contraction-side oil passages has a smaller flow passage area. By a bypass passage, a desired damping force is obtained.

According to a second aspect of the present invention, in the damping force adjusting type hydraulic shock absorber according to the first aspect of the present invention, when the spool moves to one side, a flow passage area of the bypass passage is increased. Out of the extension side and the contraction side passage, the passage area between the large and small passage areas obtained in one of the oil passages on the bypass side, and of the extension side and the contraction side oil passage The flow path area of the other oil path is set to a predetermined flow path area between large and small. With this configuration, the desired damping force characteristics on the extension side and the contraction side can be obtained in a state where the thrust of the actuator is lost.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. As shown in FIGS. 1 and 2,
The damping force-adjustable hydraulic shock absorber 1 of the present embodiment includes a hydraulic shock absorber main body 2 and a damping force generating mechanism 3. A piston 5 is slidably fitted in the cylinder 4 in which the hydraulic fluid of the hydraulic shock absorber main body 2 is sealed, and the piston 5 divides the inside of the cylinder 4 into two chambers, an upper cylinder chamber 4a and a lower cylinder chamber 4b. Is defined. One end of a piston rod 6 is connected to the piston 5, and the piston rod 6 is
The other end extends outside the cylinder 4 through a. A reservoir 8 filled with oil and gas is connected to the cylinder lower chamber 4b via a base valve 7 provided at the bottom of the cylinder 4.

The piston 5 has an oil passage 9 communicating between the cylinder upper and lower chambers 4a and 4b, and a non-return valve which allows only the flow of the oil liquid from the cylinder lower chamber 4b side of the oil passage 9 to the cylinder upper chamber 4a side. A valve 10 is provided. In addition, the base valve 7
An oil passage 11 that connects the cylinder lower chamber 4b and the reservoir 8 is provided, and a check valve 12 that allows only the flow of the oil liquid from the reservoir 8 side of the oil passage 11 to the cylinder lower chamber 4b is provided.

The case 13 of the damping force adjusting mechanism 3 has four ports, an upper chamber port 14 (extension side oil passage), a lower chamber port 15 (compression side oil passage), a reservoir port 16 and a bypass port 17 (bypass passage).
There are two ports. Upper room port 14, lower room port
15 and reservoir port 16
The bypass port 17 is connected to the cylinder lower chamber 4b via a check valve 18 and connected to the cylinder lower chamber 4b and the reservoir 8. The check valve 18 allows only the flow of the oil liquid from the bypass port 17 side to the cylinder lower chamber 4b side. Case 13
Inside, the expansion-side damping valve 19 for controlling the flow of the oil liquid from the upper chamber port 14 to the lower chamber port 15 to generate a damping force and the flow of the oil liquid from the lower chamber port 15 to the reservoir port 16 are controlled. A contraction-side damping valve 20 that generates a damping force is provided.

The extension-side damping valve 19 is a pilot-type pressure control valve, and includes a main valve 21 (disk valve) and a pilot chamber 22 for applying an internal pressure to the main valve 21 in a valve closing direction.
And a fixed orifice 23 for constantly communicating the upstream side of the main valve 21 with the pilot chamber 22, and a spool valve 24 for adjusting the flow rate of the oil liquid from the pilot chamber 22 to the lower chamber port 15. Then, the sleeve 25 of the spool valve 24
By the movement of the spool 26 slidably fitted inside,
By changing the flow path area between the ports 27 and 28 provided in the sleeve 25, the orifice characteristics (the damping force is almost proportional to the square of the piston speed) are directly adjusted, and the internal pressure of the pilot chamber 22 is changed. Let the main valve 21
To adjust the valve characteristics (the damping force is almost proportional to the piston speed).

The contraction-side damping valve 20 is a pilot-type pressure control valve, and includes a main valve 29 (disk valve) and a pilot chamber 30 for applying an internal pressure to the main valve 29 in a valve closing direction.
A fixed orifice 31 that constantly communicates the upstream side of the main valve 29 with the pilot chamber 30; and a spool valve 24 that is shared with the extension side that adjusts the flow rate of the oil liquid from the pilot chamber 30 to the reservoir port 16. Have been. By moving the spool 26 of the spool valve 24 to change the flow passage area between the ports 32 and 33 provided in the sleeve 27, the orifice characteristics are directly adjusted and the internal pressure of the pilot chamber 30 is changed. The valve characteristics of the main valve 29 can be adjusted.

When the spool 26 is moved to the right in the drawing, the land 34 closes the port 27 and the port 27, 28 is commonly used for the spool valve 24 shared by the extension side and the contraction side damping valves 19, 20. While reducing the flow passage area, the land 35 opens the port 33 to increase the flow passage area between the ports 32 and 33, that is, the damping force of the expansion damping valve 19 is hardened, and the damping force of the compression damping valve 20 is reduced. Adjust to the soft side. Conversely, when the spool 26 is moved to the left in the figure, the land 35 closes the port 33 to reduce the flow passage area between the ports 32 and 33, and the land 34 opens the port 27 and moves between the ports 27 and 28. That is, the damping force of the expansion-side damping valve 19 is adjusted to the soft side, and the damping force of the contraction-side damping valve 20 is adjusted to the hard side. Also, spool 26
Lands 34 and 35 are ports
The ports and the lands are arranged so as to open both between the ports 27 and 28 and between the ports 32 and 33, that is, to adjust the damping forces of the extension side and the contraction side damping valves 19 and 20 to the soft side.

As shown in FIG. 2, when the spool 26 is displaced to the far right and one end thereof is in contact with the stopper 36, the land 34 closes the port 27 and the other end of the spool 26 is closed. The land 37 formed in the opening 25 opens the port 27 and communicates with the oil chamber 39 in the distal end of the sleeve 25 via the groove 38. The distal end of the sleeve 25 is fitted to the bypass port 17, and the oil chamber 39 is connected to the bypass port 17. Further, the land 35 has the port 33 completely open, but the land 40 facing the land 35 closes the port 32 by a predetermined amount to reduce the flow passage area between the ports 32 and 33. At this time, the flow passage area of the port 27 and the port 32 is intermediate between the hard side and the soft side, that is, the damping forces of the extension side and the contraction side damping valves 19 and 20 are both medium.

One end of the spool 26 abuts the operating rod 42 of the proportional solenoid actuator 41 (actuator), and the other end is interposed between the spool 26 and a spring receiver 43 attached to the distal end of the sleeve 25. A compression spring 44 (spring means) is in contact. Then, the spool 26 is usually
Is biased to the right in the drawing, and the thrust of the operating rod 42 of the proportional solenoid actuator 41 causes a spring 44
By moving the lands 34 and 35 to the left against the urging force of the lands 34 and 35 to adjust the flow path areas between the ports 27 and 28 and between the ports 32 and 33, the expansion-side and compression-side damping valves 19 and 20 are adjusted. When the thrust of the proportional solenoid actuator 41 is lost, the urging force of the spring 44 moves rightward and abuts the stopper 36. The spool 26 is provided with a communication passage 45 for communicating the chambers at both ends in the sleeve 25 with each other, so that the spool 26 can move smoothly in the sleeve 25.

Next, the operation of the embodiment constructed as described above will be described. The normal operation of the damping force adjusting hydraulic shock absorber 1 will be described. During the extension stroke of the piston rod 6, as the piston 5 moves, the check valve 10 of the piston 5 closes and the oil liquid in the cylinder upper chamber 4a side is pressurized, and the upper chamber port 14, the extension side damping valve 19 and the lower It flows through the chamber port 15 to the cylinder lower chamber 4b. Thereby, the extension side damping valve 19
Before opening the main valve 21 (low-speed range of the piston speed), the fixed orifice 23 and the port 27 of the spool valve 24,
The damping force of the orifice characteristic occurs due to the flow path area between the 28 and after the main valve 21 is opened (high-speed range of piston speed)
, A damping force of valve characteristics is generated according to the opening degree. It should be noted that the amount of oil that the piston rod 6 has withdrawn from the cylinder 4 is supplied from the reservoir 8 to the check valve 12 of the base valve 7.
Is opened to flow into the cylinder lower chamber 4b.

During the compression stroke of the piston rod, the check valve 10 of the piston 5 is opened in accordance with the movement of the piston 5, and the oil liquid in the cylinder lower chamber 4b passes through the oil passage 9 and the cylinder upper chamber 4a.
Directly flows into the upper and lower chamber ports 14a and 4b of the cylinder upper and lower chambers 14a and 4b.
There is no flow of the oil liquid between the pump and the lower chamber port 15. On the other hand, when the piston rod 6 enters the cylinder 4, the check valve 12 of the base valve 7 closes, and the oil liquid in the cylinder 4 is pressurized to the extent that the piston rod 6 enters, so that the cylinder lower chamber 4b From the lower chamber port 15, the contraction side damping valve 20 and the reservoir port 16 to the reservoir 8. As a result, before the main valve 29 of the compression-side damping valve 20 is opened (low-speed range of the piston speed), the damping force of the orifice characteristic is increased by the flow passage area between the fixed orifice 33 and the ports 32 and 33 of the spool valve 24. After the main valve 29 is opened (a high-speed region of the piston speed), a damping force having valve characteristics is generated according to the opening degree.

Then, the proportional solenoid actuator 41
By moving the spool 26 of the spool valve 24 against the urging force of the spring 44 in accordance with the energizing current,
By adjusting the flow path areas between ports 7 and 28 and between ports 32 and 33 on the contraction side, the orifice characteristics on the extension and contraction sides are directly adjusted, and the internal pressure of pilot chambers 22 and 30 is changed to change the main valve. The valve opening characteristics (valve characteristics) of 21, 29 can be adjusted. At this time, when the spool 26 is moved to the left in the figure, the extension side is adjusted to the soft side, the contraction side is adjusted to the hard side, and when it is moved to the right, the extension side is adjusted to the hard side, and the contraction side is adjusted to the soft side. With these intermediate positions, both the extension side and the contraction side are adjusted to the soft side.

Next, the operation of the damping force-adjustable hydraulic shock absorber 1 when the thrust of the proportional solenoid actuator 41 is lost (at the time of failure) due to a controller failure or the like will be described. When the thrust of the proportional solenoid actuator 41 is lost, as shown in FIG. 2, the spool 26 moves rightward in the figure by the urging force of the spring 44 and contacts the stopper 36. In this state, during the extension stroke of the piston rod 6, the oil liquid flowing through the extension-side damping valve 19 passes through the port 27 moderately restricted by the land 37, flows through the groove 38, the oil chamber 39, and the bypass port 17. Then, the check valve 18 is opened to flow into the cylinder lower chamber 4b. Also, during the contraction stroke, the extension side damping valve
The oil flowing through 20 passes through port 32, which is moderately restricted by land 40, flows through port 33 and reservoir port 16, and flows into reservoir 8.

As a result, the extension-side and compression-side damping valves 19,
The damping force by 20 depends on the flow path area of ports 27 and 32,
Both will be adjusted to medium characteristics. In this way, at the time of a failure, the damping force characteristics on the extension side and the contraction side can be fixed to arbitrary characteristics such as medium.
The stability of the vehicle body and good riding comfort can be ensured. In this case, the single spool valve 24 can obtain the damping force characteristics at the time of normal operation and at the time of failure.
Since it is not necessary to provide a fail-safe valve or the like, the structure is simple, and downsizing and reduction in manufacturing cost can be achieved. The position of the spool 26 of the damping force-adjustable hydraulic shock absorber 1 (i.e., the current supplied to the proportional solenoid actuator 41)
FIG. 3 shows the relationship between and the damping force.

In the above embodiment, as an example, a pilot type pressure control valve is used as the expansion-side and compression-side damping valves. However, the present invention is not limited to this. The present invention can be similarly applied to a damping force-adjustable hydraulic shock absorber using another type of damping valve as long as the damping force is adjusted on the side and the contraction side. Further, in the present embodiment, as an example, the one in which the damping force generating mechanism is provided outside the cylinder is described. However, the present invention is not limited to this, and the damping force generating mechanism is provided in the piston portion. The same can be applied to objects.

In the above embodiment, an example in which a push type solenoid is used has been described, but a pull type solenoid may be used. In this case, when the solenoid is not energized, the spool moves to the side away from the solenoid, and the configuration of the passage is upside down from that of FIG. Further, the damping force-adjustable hydraulic shock absorber of the present invention can be used for a suspension of an automobile.

[0025]

As described above in detail, according to the damping force adjusting type hydraulic shock absorber according to the first aspect, when the thrust of the actuator is lost, the spool moves to one side by the spring means, and the elongation occurs. A desired damping force can be obtained by bypassing, by the bypass passage, one of the side and contraction side oil passages having a smaller flow passage area. as a result,
At the time of a failure in which the thrust of the actuator is lost due to a failure of the controller or the like, the damping force can be fixed to a desired value, and the stability of the vehicle body and good riding comfort can be secured. Further, according to the damping force-adjusting hydraulic shock absorber according to the second aspect, it is possible to set the expansion-side and contraction-side damping force characteristics to desired characteristics in a state where the thrust of the actuator is lost.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a damping force adjusting hydraulic shock absorber according to one embodiment of the present invention.

FIG. 2 is an enlarged longitudinal sectional view showing a damping force generating mechanism of the device of FIG. 1;

FIG. 3 is a diagram showing a damping force characteristic of the damping force adjustable hydraulic shock absorber of FIG. 1;

[Explanation of symbols]

 1 Damping force adjustable hydraulic shock absorber 4 Cylinder 5 Piston 6 Piston rod 14 Upper chamber port (extension side oil path) 15 Lower chamber port (retraction side oil path) 17 Bypass port (Bypass path) 24 Spool valve 41 Proportional solenoid actuator ( Actuator) 44 Spring (spring means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16F 15/02 F16F 15/02 FF Term (Reference) 3J048 AB09 AB11 AC04 BE03 CB27 EA15 3J069 AA50 DD50 EE01 EE36 EE44

Claims (2)

[Claims] 1. A cylinder filled with an oil liquid, a piston slidably fitted in the cylinder, and a piston having one end connected to the piston and the other end extending outside the cylinder. A rod, an extension-side oil passage communicating with the cylinder and allowing the oil liquid to flow during the extension stroke of the piston rod, and a contraction-side oil passage allowing the oil liquid to flow during the contraction stroke;
A spool valve that adjusts the flow area of the expansion-side oil path and the compression-side oil path; and an actuator that drives a spool of the spool valve, wherein the spool valve has a flow-path area of the expansion-side and compression-side oil paths. When one is large, the other is small, and when one is small, the other is large, and in the damping force adjustable hydraulic shock absorber, the spool valve moves the spool to one side when the thrust of the actuator is lost. Spring means for moving;
A bypass passage that, when the spool moves to one side, bypasses one of the oil passages having a smaller flow path area and opens when the spool moves to one side; And a damping force adjusting hydraulic shock absorber. 2. The spool valve according to claim 1, wherein, when the spool moves to one side, the flow path area of the bypass passage is increased by one of the expansion-side and contraction-side passages, which is obtained by one of the bypass-side oil passages. With the flow area between the flow area of the small and the small, the flow area of the other oil path in the expansion side and the contraction side oil path, the flow area of the other oil path with a predetermined flow area between the large and small 2. The damping force-adjustable hydraulic shock absorber according to claim 1, wherein: