JP2003294075A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To mutually cancel force in which fluid acts on a rotary valve and prevent the rotary valve from generating unnecessary rotary torque. <P>SOLUTION: Ports 28 and 30 provided on a piston rod 9 and connecting holes 29 and 31 provided on the rotary valve 12 are separately arranged to a flowing direction of fluid which flows in the rotary valve 12, and a flowing direction of fluid which flows out of the rotary valve 12. <P>COPYRIGHT: (C)2004,JPO

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 mounted on an automobile or the like so that the generated damping force can be adjusted according to changes in the load.

[0002]

2. Description of the Related Art A hydraulic shock absorber as a suspension is provided between a vehicle body and an axle of a vehicle such as an automobile.
Vibrations from the road surface and shocks such as lift-up input are damped while the vehicle is running to improve the riding comfort of the vehicle.

This hydraulic shock absorber, for example, as shown in FIG. 4, uses a piston 5 having an expansion side port 1 and a compression side port 2 and an expansion side damping valve 3 and a compression side damping valve 4 to move the inside of a cylinder 6 inside. It is divided into a rod side chamber 7 and a piston side chamber 8 in which hydraulic oil as a fluid is stored.

The piston rod 9 to which the piston 5 is attached has a bypass 1 bypassing the damping valves 3 and 4.
0 is provided, and a rotary valve 12 whose rotation is controlled by an actuator such as a motor via a control rod 11 is provided in the bypass 10.

Then, the communication hole 14 formed in the rotary valve 12 is made to face the port 13 formed in the piston rod 9 and used for expansion, and the opening area where these are overlapped with each other is adjusted so that the oil on the rod side is adjusted. By making the chamber 7 and the piston side oil chamber 8 communicate with each other, the damping force can be selectively controlled from hard to soft, or from soft to hard.

In order to improve the performance of the hydraulic shock absorber, it is essential to increase the pressure receiving area. However, if the pressure receiving area is increased, the damping force adjusting hydraulic shock absorber has a large damping force. The flow rate of the fluid (hydraulic oil) passing through the adjusting rotary valve 12 increases, which increases the fluid force, and this fluid force affects the rotational torque and the stationary torque of the rotary valve 12.

That is, the fluid force is given by a change in the momentum of the fluid. Therefore, the fluid force acting on the rotary valve 12 is a force that pushes the rotary valve 12 in the axial direction, as shown by the arrow in FIG. Fa and AA of FIG.
The force Ft acts in the tangential direction of the rotary valve 12 as indicated by the arrow in FIG. 5, which is a sectional view taken along the line.

Among these, the force Ft is that the fluid flowing into the rotary valve 12 in the direction of the arrow in FIG.
And the force Fq that resists the force Fp in the direction of flowing out from the port 13, and this component Ft is the force component Ft.
As shown in FIG. 5, a rotational force in the direction of arrow R is generated for 2.

[0009]

In the conventional hydraulic shock absorber, when the fluid force is large, the above forces Fa and Ft are applied.
Acts as a moment that resists when the rotary valve 12 is rotated by a motor or the like, and resists, for example, a force that rotates the rotary valve 12 in the clockwise direction, so that the rotation amount of the rotary valve 12 becomes insufficient. Therefore, there is a problem that the adjustment of the damping force may be insufficient.

Further, in order to reduce the force resisting the rotational force of the motor as described above, the port 13 and the communication hole 14 are used.
It is possible to adopt a method such as suppressing the diameter of the valve to a small value or reducing the frictional resistance of the rotary valve 12 with respect to the piston rod 9, but this alone has a limit, and the performance of the hydraulic shock absorber is improved by increasing the pressure receiving area. Can not contribute.

Therefore, it is an object of the present invention to pay attention to the fact that a change in the momentum of a fluid becomes a fluid force, so that the flow of the fluid from the rotary valve through the communication hole of the rotary valve and the port of the piston rod and the fluid to the rotary valve By providing two sets so as to separately share the flow that flows in, a hydraulic shock absorber that can cancel the fluid forces acting on the rotary valve mutually and prevent unnecessary rotary torque from acting on the rotary valve is provided. To get.

[0012]

[Means for Solving the Problems] To achieve the above object,
Means of the present invention, a piston rod attached to a piston that divides the inside of the cylinder into a rod side chamber and a piston side chamber, an expansion side port and a pressure side port that are provided in the piston and communicate the rod side chamber and the piston side chamber, and A rotary valve having an expansion side damping valve and a compression side damping valve that open and close the outlet end, and a communication hole that is rotatably provided in a bypass in a piston rod that bypasses each damping valve and that is opened and closed in a port formed in the piston rod. In a hydraulic shock absorber that includes and adjusts the soft or hard damping force by adjusting the opening area of the communication hole,
It is characterized in that two sets of the above-mentioned ports and communication holes are provided as one set separately for the flow direction of the fluid flowing into the rotary valve and the flow direction of the fluid flowing out of the rotary valve.

In this case, the opening form of the communication hole for each set of ports may be such that the reaction force received by the rotary valve by the fluid flow is the same and the direction of this reaction force is opposite.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a main part of a hydraulic shock absorber of the present invention. 1 and a compression side port 2, and an expansion side damping valve 3 and a compression side damping valve 4, which are slidably provided in a cylinder 6.

Further, the piston 5 divides the inside of the cylinder 6 into a rod side chamber 7 and a piston side chamber 8 which contain hydraulic oil as a fluid.

The piston rod 9 to which the piston 5 is attached is provided with a bypass 10 that bypasses the damping valves 3 and 4 and is connected to a control rod 11 driven by an actuator such as a motor. A cylindrical rotary valve 12 whose rotation is controlled is provided.

An annular fluid passage 5a, which communicates with the piston side chamber 8 via an oil passage 5b, is arranged on the inner peripheral side of the piston 5. The structure up to this point is substantially the same as that shown in FIG. 4 except for the annular passage 5a.

On the other hand, on the piston rod 9 and on the rod side chamber 7 side of the piston 5, as shown in the drawing, a valve body 15 which opens toward the rod side chamber 7 direction.
And a disk 17 that closes the opening of the valve body 15 to form a fluid chamber 16 between the valve body 15 and the bottom of the valve body 15, and a compression side port 18 and an expansion side port that are provided so as to penetrate the disk 17. 19, an expansion side sub-valve 20 and a compression side sub-valve 21 which are provided to open and close each of these ports 18, 19 are arranged.

Further, on the piston rod 9 between the valve body 15 and the expansion side sub-valve 20, a small cup member 23 forming an annular passage 22 between the bottom of the valve body 15 and the piston rod 9 is interposed. Has been done.

The small cup member 23 is provided with a notch groove 24 that penetrates inward and outward in the radial direction of the small cup member 23. In the wall thickness of the bottom portion of the valve body 15, the small cup member 23 passes through the inner and outer circumferences thereof. The hole 15a is bored.

At the end of the piston rod 9, the opening end of the bypass 10 is closed, and the expansion side damping valve 3, the compression side damping valve 4, the piston 5, the valve body 15, the disk 17, the expansion side sub-valve 20 and the compression side sub-valve. Two
Piston nuts 27 are pressed into the stopper plate 26 via the spacers 25 so as to press and hold them.

On the other hand, at the positions of the piston rod 9 and the rotary valve 12 which correspond to each other, a port and a communication hole are formed so as to penetrate through the wall thickness thereof, specifically, the first port 28 and the first port 28 each having two holes. A communication hole 29 is provided.

The first port 28 and the first communication hole 29
Communicates with the annular passage 5a provided in the piston 2, and therefore the first port 28 and the first communication hole 29 have a relatively overlapping opening amount and the annular passage 5a and the rotary passage 5a. It communicates with the inside of the tubular portion 12 a of the valve 12 and the bypass 10 of the piston rod 9.

Further, at the other corresponding positions of the piston rod 9 and the rotary valve 12, two second ports 30 and two second communicating holes 31 are formed so as to penetrate through the wall thickness of the piston rod 9 and the rotary valve 12. The second port 30 and the second communication hole 31 are provided in the valve body 1
It communicates with the bottom of 5 and an annular passage 22 made between the piston rod 9 and the small cup member 23.

The second port 30 and the second communication hole 31 have an opening amount that overlaps each other, and the annular passage 22 and the cylindrical portion 12a of the rotary valve 12 and the bypass 10 of the piston rod 9 are provided. It communicates with the inside.

Therefore, the cylindrical portion 12 of the rotary valve 12
a and the bypass 10 of the piston rod 9 communicate with the fluid chamber 16 in the valve body 15 through the second port 30, the second communication hole 31, the annular passage 22, and the notch groove 24 of the small cup member 23. is doing.

It is important to note that the first communication hole 29 and the second communication hole 31 provided in the rotary valve 12 have the same shape, the same size, and the same direction at the same position in the circumferential direction ( For example, it is formed in the radial direction.

The first rod provided on the piston rod 9
That is, the port 28 and the second port 30 are formed at the same position in the circumferential direction and have the same shape, the same size, and the same direction.

Further, a rod-side orifice 32 and a rotary valve-side orifice 33 are provided at further different positions of the piston rod 9 and the rotary valve 12 corresponding to each other.

The rod-side orifice 32 and the valve-side orifice 33 are inserted into the rod-side chamber 7 and the cylindrical portion 12a of the rotary valve 12 and the piston 9 through a through hole 15a formed in the base of the valve body 15. It communicates with the inside of the bypass 10.

These through holes 15a, 32, 33 adjust the flow rate of the fluid passing therethrough, and the vehicle travels together with the expansion side damping valve 3, the compression side damping valve 4, the expansion side sub-valve 20, and the compression side sub-valve 21. A damping force suitable for each medium speed range is generated in the hydraulic shock absorber.

Next, the operation of the hydraulic shock absorber having the above structure will be described with reference to the sectional view taken along line BB shown in FIG. 1 (FIG. 2). First, the damping of the piston rod 9 in the pressure stroke. The force adjustment operation will be described.

In the pressure stroke of the piston rod 9, the piston 5 moves in the cylinder 6 toward the direction of the piston side chamber 8 (right in the figure), so that the fluid (operating oil) in the piston side chamber 8 is compressed. The compression side damping valve 4 is opened through the port 2 to generate a compression side damping force, and further flows into the rod side chamber 7.

Further, in parallel with this, the fluid in the piston side chamber 8 passes through the annular passage 5a on the inner circumference of the piston 5 in the direction of the solid line arrow to reach the first port 2 of the piston rod 9.
8 and the first communication hole 2 in the rotary valve 12
9, through the tubular portion 12a of the rotary valve 12, the second communication hole 31 of the rotary valve 12 and the port 30 of the piston rod 9, the annular passage 22 surrounded by the small cup member 23, and the cutout groove 24 It flows into the chamber 16.

Further, the fluid flowing into the fluid chamber 16 passes through the pressure side port 18 and opens the pressure side sub-valve 21 to flow into the rod side chamber 7.

Further, the fluid in the cylindrical portion 12a of the rotary valve 12 is the same as the rotary valve side orifice 3 described above.
3, it flows into the rod side 7 through the rod side orifice 32 and the through hole 15a.

Therefore, by rotating the rotary valve 12 by a predetermined amount through the control rod 11 using a motor or the like, the opening amount of the first communication hole 29 with respect to the first port 28 and the second port 30 are controlled. Second
The opening amount of the communication hole 31 can be rotated by the same amount.

Therefore, a part of the fluid on the piston side 8 is bypassed by the pressure side damping valve 4 by an amount corresponding to the opening amount of the fluid, and the annular passage 22, the notch groove 24, the fluid chamber 16,
The pressure side port 18 and the pressure side sub-valve 21 are sequentially passed to flow into the rod side chamber 7, whereby the pressure side damping force generated by the pressure side damping valve 4 can be adjusted.

At this time, a part of the fluid in the cylindrical portion 12a of the rotary valve 12 bypasses the expansion side sub-valve 21 as described above, and the rotary valve side orifice 33, the rod side orifice 32 and the valve body 1 are provided.
The pressure side damping force is adjusted according to the opening amount of the orifices 33, 32, 15a which flow into the rod side chamber 7 through the through hole 15a in the valve 5.

The damping force of the entire hydraulic shock absorber on the pressure side is
The damping force generated by the compression side damping valve 4, the compression side sub-valve 21 and the orifices 33 and 32 are combined, and the damping force is adjusted to the optimum value according to the vehicle speed by the rotation of the rotary valve 12, for example. It will be.

By the way, in the hydraulic shock absorber having a large pressure receiving area, the ports 28 and 30 and the communication holes 29 and 31 are provided.
Since the flow rate of the fluid flowing through the
This affects the rotary control force of the rotary valve.

That is, when considering the above-mentioned pressure stroke of the piston rod 9, the fluid in the piston side chamber 8 passes through the annular passage 5a, and the rotary valve 12 from the first port 28 and the first communication hole 29. When flowing into the cylindrical portion 12a, the fluid motion as shown in the sectional view of FIG. 2 taken along the line CC in FIG.

That is, when the fluid flows into the tubular portion 12a in the rotary valve 12 at the pressure Fr in the region where the first port 28 and the first communication hole 29 overlap with each other, the fluid flows in this inflow direction. The resisting reaction force Fs acts on the rotary valve 12.

Then, the component force Fu of the reaction force Fs is applied in the tangential direction of the rotary valve 12, and this component force Fu causes the rotary valve 12 to generate a rotational force, so that the rotary valve 12 is in the direction of arrow S. Be urged by.

On the other hand, the fluid that once flows into the cylindrical portion 12a in the rotary valve 12 has the second communicating hole 31 and the second communicating hole 31.
Through the port 30, through the annular passage 22 and the notch groove 24, and flows into the fluid chamber 16 as described above, and further opens the pressure side sub-valve 21 and flows out to the rod side chamber 7.

At this time, the fluid force acting on the rotary valve 12 is the same as that described with reference to FIG.
There are two forces, a force Fa that pushes the rotary valve 12 in the axial direction, and a force Ft that acts in the tangential direction of the rotary valve 12, as shown in the cross-sectional view of FIG. 3 taken along the line BB of FIG.

Of these, the force Ft is a component force of the force Fq that resists the force Fp in the direction in which the fluid flowing into the rotary valve 12 in the direction of the arrow in FIG. 3 flows out from the port 30 and the communication hole 31. This component force Ft causes the rotary valve 12 to generate a rotational force in the direction of arrow R of a half-clock as shown in FIG.

Therefore, in the first communication hole 29, the reaction force Fu acting on the rotary valve 12 and the second communication hole 3
1, the reaction force Ft acting on the rotary valve 12 has a substantially small magnitude, and the directions thereof are opposite directions (circumferential direction). Therefore, these reaction forces Fu and Ft cancel each other, and as a result, The rotary valve 12 does not generate unnecessary rotational force due to fluid force.

As a result, the high performance of the hydraulic shock absorber can be easily realized by increasing the pressure receiving area, and even if a small motor is used as an actuator for driving the rotary valve 12 for adjusting the damping force, the piston is particularly effective. This makes it possible to set or adjust the damping force in the high speed range with high accuracy.

In the above description, the cancellation of the fluid force in the pressure stroke of the piston rod 9 has been described, but by performing the cancellation of the fluid force in the extension stroke in the same manner, the rotary valve in the extension stroke is used. The damping force can be adjusted easily and accurately.

[0051]

As described above, according to the present invention, the flow direction of the fluid flowing into the rotary valve and the flow of the fluid flowing out from the rotary valve are controlled through the port on the piston rod side and the communication hole on the rotary valve side. It is possible to cancel these fluid forces through the rotary valve by providing two equal fluid forces in opposite directions at the same time on the rotary valve by providing them separately in two directions (two sets). Even if the fluid force acting on the rotary valve becomes large due to the increase in the pressure receiving area, it is possible to avoid giving unnecessary rotary force to the rotary valve.

Therefore, the rotation control of the rotary valve becomes light, and it becomes unnecessary to increase the rotation torque of the rotary valve by the motor or the like more than necessary.

Further, the opening form of each communication hole for each port of each set is such that the reaction force received by the rotary valve due to the fluid flow is the same and the direction of this reaction force is opposite. Even if the flow rate of the fluid passing through the valve increases and the fluid force increases, the damping force adjustment by the rotary control of the rotary valve can be achieved with good direction balance, reliably, and highly accurately even with a small actuator.

[Brief description of drawings]

FIG. 1 is a sectional view of essential parts showing a hydraulic shock absorber according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a change in momentum of fluid in a port of 9 and a communication hole of a rotary valve in one set of piston rods in FIG.

3 is an explanatory diagram showing a change in momentum of fluid in a port of a piston rod and a communication hole of a rotary valve of the other set in FIG. 1. FIG.

FIG. 4 is a sectional view of an essential part showing a conventional hydraulic shock absorber.

5 is an explanatory view showing a change in momentum of fluid in a communication hole of a port of a piston rod and a rotary valve in FIG.

[Explanation of symbols]

1 Extension side port 2 Pressure side port 3 Extension side damping valve 4 Pressure side damping valve 5 pistons 6 cylinders 7 Rod side chamber 8 Piston side chamber 9 Piston rod 10 Bypass 12 Rotary valve 28 First Port 29 First communication hole (communication hole) 30 Second port (port) 31 Second communication hole (communication hole)

Claims (2)

[Claims] 1. A piston rod attached to a piston that divides the inside of a cylinder into a rod-side chamber and a piston-side chamber, an expansion-side port and a pressure-side port that are provided in the piston and communicate with the rod-side chamber and the piston-side chamber, and outlets of each port. An expansion side damping valve and a compression side damping valve that open and close ends, and a rotary valve that has a communication hole that is rotatably provided in a bypass in a piston rod that bypasses each damping valve and that is opened and closed in a port formed in the piston rod. In a hydraulic shock absorber that is equipped with a hydraulic shock absorber that adjusts the opening area of the communication hole to perform soft or hard damping force adjustment, the above-mentioned port and communication hole, as a set, flow direction of the fluid flowing into the rotary valve and flow out from the rotary valve. Hydraulic shock absorber characterized in that two sets are provided separately for each direction of fluid flow . 2. The opening form of the communication hole for each set of ports is such that the reaction force received by the rotary valve due to the flow of fluid is the same and the directions thereof are opposite. The described hydraulic shock absorber.