JPH0728249U - Hydraulic shock absorber - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the ray noise coefficient in the practical speed range, prevent the generation of swish noise due to cavitation, and apply it during the pressure stroke of a small-diameter piston rod with a small flow rate. [Structure] A base valve case 23 having a pressure side port 25 closed by a leaf valve 24 is provided at a lower end of a cylinder 22 inside an outer shell 21, and a non-return valve 26 for closing an extension side port 27 in the base valve case 23.
Is provided in the lower portion of the base valve case 23, and the reservoir chamber 29 and the volume chamber 3 communicating with the outer shell chamber 39 are provided.
Check valves 28 and 41 that divide 0, 43 into the reservoir chamber 29 through a plurality of port holes 31 and 42 of the hydraulic oil flowing from the pressure side port 25 via the pressure chambers 30 and 43 during the pressure stroke. Is provided so that the reservoir chamber 29 is separated from the valve seat during the extension stroke.
Of the hydraulic oil is sent to the base valve upper chamber 38 via the chambers 30, 43 and the extension side port 27.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hydraulic shock absorber mounted on a vehicle.

[0002]

[Prior art]

 FIG. 7 is a sectional view of an essential part showing a conventional hydraulic shock absorber disclosed in, for example, Japanese Utility Model Publication No. 61-61239. In FIG. 7, reference numeral 1 denotes a piston upper chamber A and a piston inside the cylinder 2. The piston is separated from the lower chamber B and is attached to the end of the piston rod 8.

Reference numerals 3 and 12 denote two leaf valves that close the pressure side port 4 of the piston 1.

Further, 5 is a leaf spring for urging the leaf valve 3 in the closing direction, 6 is a leaf valve for closing the expansion side port 7 of the piston 1, and 9 is a spring attached to the end of the piston rod 8. The leaf valve 6 is pressed against the extension side port 7 side through a ring-shaped spring receiver 12 by a spring 11 installed on the seat 10 of the spring seat member 9 in the seat member.

FIG. 8 is a plan view of the leaf valve 3, and a plurality of port holes 3 a are provided in a portion of the leaf valve 3 corresponding to the extension side port 7.

FIG. 9 is a plan view of the other leaf valve 12, in which a plurality of arc-shaped elongated holes 12a are provided in a portion of the other leaf valve 12 corresponding to the port hole 3a, and further in the outer periphery. A plurality of slits 12b communicating with the pressure side port 4 are formed.

Next, the operation will be described. First, when the piston rod 8 extends, the piston rod 8 moves in the direction of the arrow X, so that the hydraulic oil in the piston upper chamber A is a leaf valve at low speed. It is opened to the piston lower chamber B through the slit 12b of 12 and the pressure side port 4.

When the speed further increases, in addition to the above flow, the hydraulic oil in the piston upper chamber A respectively flows through the port hole 3a of the leaf valve 3 and the long hole 12a of the leaf valve 12 respectively. Through the leaf valve 6 and the seat surface 1a of the piston 1 with which the leaf valve 6 comes into contact with the leaf valve 6, and flows into the piston lower chamber B.

On the other hand, during the pressure stroke of the piston rod 8, the hydraulic oil in the piston lower chamber B flows into the piston upper chamber A via the pressure side port 4 and the slit 12 b of the leaf valve 12.

By the way, in the above-described stroke of the piston rod 8, when the hydraulic oil flows from the piston upper chamber A to the piston lower chamber B, swash noise is generated due to cavitation.

Therefore, it is known that the Reynolds coefficient Re is suppressed to be small in order to prevent the cavitation.

It is expressed by Re = C · di / ν, where C is the average velocity in the pipe, di is the inner diameter of the pipe, and ν is the kinematic viscosity coefficient.

Generally, by dispersing the slits 12b of the leaf valve 12, even if the slit area is the same, the diameter d of the pipe is reduced, and thus the ray noise coefficient Re is also reduced, so that the swish noise can be suppressed. It has been confirmed.

[0014]

[Problems to be Solved by the Invention]

 However, when the speed of the compression stroke of the piston rod 8 increases and reaches the practical speed range, there is a limit to the reduction of the pipe inner diameter di, and eventually the ray noise coefficient Re cannot be lowered, and therefore the cost is reduced. There were problems such as being prepared to improve the vehicle, having to use a gas-filled structure at the expense of riding comfort, and a soundproof structure.

The present invention has been made by paying attention to the above-mentioned conventional problems, and can reduce the ray noise coefficient in the practical speed range to prevent the generation of the scavenging swish noise and to reduce the flow rate. An object of the present invention is to provide a hydraulic shock absorber that can be applied during the pressure stroke of a small-diameter piston rod with a small number of cylinders.

[0016]

[Means for Solving the Problems]

 In the hydraulic shock absorber according to the present invention, a base valve case whose pressure side port is closed by a leaf valve is provided at the lower end of the cylinder inside the outer shell, and a non-return valve for closing the expansion side port is provided in the base valve case. A reservoir chamber and a chamber which communicate with the outer shell chamber are defined in the lower part of the chamber, and the hydraulic oil flowing from the pressure side port through the chamber during the pressure stroke is delivered to the reservoir chamber through its own plurality of port holes. A check valve is provided so that the hydraulic oil in the reservoir chamber is delivered to the upper chamber of the base valve via the capacity chamber and the extension side port while being separated from the valve seat during the extension stroke.

[0017]

[Action]

 The hydraulic shock absorber according to the present invention allows the hydraulic oil in the upper chamber of the base valve to pass through between the pressure side port and the relief valve and the seat surface on the base valve case during the pressure stroke of the piston rod in the practical speed range where the piston speed is high. Guide it to the chamber, and then release it from the chamber to the reservoir chamber that communicates with the outer shell through the port hole of the check valve.

Due to the throttle action of the check valve and the port hole, the pressure of the hydraulic oil drops in two steps from the upper chamber of the base valve → the chamber of the reservoir → the reservoir chamber. It functions to reduce the ray noise coefficient Re by reducing the inner diameter of the tube due to dispersion.

With this, the generation of a swish sound due to cavitation is prevented, and it can be applied to the pressure stroke of a hydraulic shock absorber having a small diameter piston rod with a small flow rate.

[0020]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged view of the vicinity of a base valve according to the present invention. In FIG. 1, 21 denotes an outer shell and 22 denotes an outer shell 21. The cylinder 23 provided inside is a base valve case provided at the lower end of the cylinder 22.

Reference numeral 24 is a leaf valve that closes the lower end of the pressure side port 25 provided in the base valve case 23, and 26 is a non-return valve (that is, a non-return valve that closes the extension side port 27 provided in the base valve case 23). Check valves) and 28 are check valves that close the lower end of the base valve case 23 and separate the reservoir chamber 29 and the chamber 30 that communicate with the inside of the outer shell 21. As shown in FIG. In addition, a large number of small holes 31 are formed.

Further, 32 is a valve holding plate having a ring-shaped cross section, which is attached to the lower end of the mounting shaft 33 of the base valve case 23, and which communicates with the chamber 30 and the reservoir chamber 29. As shown in FIG. 3, a plurality of long port holes 34 are provided, and the projecting end of the outer peripheral edge is the seat surface of the check valve 28.

Reference numeral 35 is a coil spring for urging the outer peripheral portion of the check valve 28 downward.

Further, 36 is a coil spring for urging the non-return valve 26 toward the extension side port 27 side, 37 is a port for communicating the reservoir 29 with the outer shell chamber 39 inside the outer shell 21, and 38 is Upper chamber of base valve.

Next, the operation will be described. Here, a case will be described in which the piston speed, which is a problem in generating a swish sound, is a practical speed.

First, during the pressure stroke of the piston rod (not shown), the hydraulic oil in the base valve upper chamber 38 passes between the pressure side port 25, the leaf valve 24 and the seat surface 23a on the base valve case 23 supporting the leaf valve 24. It is released into the chamber 30.

Further, the hydraulic oil released into the chamber 30 passes through the port hole 31 of the check valve 28 and the port hole 34 of the valve holding plate 32 and is released to the reservoir chamber 29.

Therefore, the pressure of the hydraulic oil during the pressure stroke is increased by the two throttling actions of the port holes 31 of the leaf valve 24 and the check valve 28. It is possible to realize a reduction in the inner diameter of the pipe due to the decrease in the outflow speed of the hydraulic oil and the distributed arrangement of the port holes 31.

As a result, it is possible to reduce the ray noise coefficient, suppress the occurrence of cavitation, and prevent the generation of swish sound.

On the other hand, during the extension stroke of the piston rod (in the practical speed range where the piston speed is high), the working oil in the reservoir chamber 29 pushes the check valve 28 through the port hole 34 of the valve holding plate 32. It opens and moves to the chamber 30, and further pushes the expansion side port 27 and the non-return valve 26 that closes the expansion side port 27 to escape to the base valve upper chamber 38.

The differential pressure between the reservoir chamber 30 and the reservoir chamber 29 is determined by the set load of the coil spring 35 and the spring constant, and the hydraulic oil in the reservoir chamber 29 exceeds the differential pressure. The check valve 28 is pushed open to reach the base valve upper chamber 38 as described above.

The internal pressure of the base valve upper chamber 38 immediately after the conversion from the pressure stroke to the extension stroke is determined by the control of the open pressure of the check valve 28 and the non-return valve 26.

Therefore, the internal pressure of the base valve upper chamber 38 changes abruptly, the vibration of the piston rod is amplified, and as a strange noise of the shock absorber, a problem of causing an occupant to feel uncomfortable occurs. These problems can be eliminated by the above-described two-step control of the open pressure of the return valve 26 as shown in FIG. Example 2. FIG. 5 shows another embodiment of the present invention. The difference between this embodiment and the embodiment shown in FIG. 1 is that a cylindrical check valve in which the overlap of both ends changes at the lower end of the base valve case 23. 41 is attached.

As shown in FIG. 6, the check valve 41 is made by winding a spring sheet having a large number of port holes 42 in a tubular shape so that both ends thereof overlap, and the inside of the check valve 41 is the above-mentioned port. It is a chamber 43 that communicates with the outer shell chamber 39 as a reservoir chamber through the hole 42.

In the shock absorber having such a configuration, during the pressure stroke in the practical speed range, the hydraulic oil in the base valve upper chamber 38 is temporarily stored in the chamber via the pressure side port 25, the leaf valve 24 and the seat surface. 43, and is guided to the outer shell chamber 39 through the port hole 42 of the check valve 41, and operates so as to obtain a two-stage pressure reduction as in the above embodiment, and a swish sound is generated. Prevent.

On the other hand, during the extension stroke, the hydraulic oil in the outer shell chamber 39 causes the check valve 41 to contract due to the pressure difference with the pressure inside the chamber 43, as shown by the dotted line in FIG.

Therefore, the hydraulic oil flows into the chamber 43 through the gap formed at the outer periphery of the check valve 41 and the joint with the base valve case 23, and further the expansion side port 27 and the non-return valve. It will flow to the base valve case upper chamber 38 via 26.

[0038]

【The invention's effect】

 As described above, according to the present invention, the base valve case in which the compression side port is closed by the leaf valve is provided at the lower end of the cylinder inside the outer shell, and the base valve case is provided with the non-return valve for closing the expansion side port. A reservoir chamber and a chamber that communicate with the outer shell chamber are defined in the lower part of the case, and the hydraulic oil flowing from the pressure side port through the chamber during the pressure stroke is delivered to the reservoir chamber through its own plurality of port holes. A check valve is provided to allow the hydraulic oil in the reservoir chamber to be delivered to the upper chamber of the base valve via the chamber and the port on the extension side while separating from the valve seat during the extension stroke. The internal pressure fluctuation that releases the hydraulic oil during the stroke is gradually reduced to moderate the flow speed of the hydraulic oil from the port hole. Can, moreover by small comb Reinoizu coefficient Re by reducing the tube diameter, the effect of practical which would have to be able to effectively prevent the occurrence of swish sound by cavitation can be obtained.

Further, it can be applied to a shock absorber having a small flow rate in the pressure stroke, that is, a piston rod having a small cross-sectional area, and it can be expected that the flow hole of the hydraulic oil can be expected to be rectified by the port hole of the check valve. The effect is obtained.

[Brief description of drawings]

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

FIG. 2 is a plan view showing a check valve in FIG.

3 is a plan view showing a valve holding plate in FIG. 1. FIG.

FIG. 4 is an explanatory diagram showing a change over time in the internal pressure of the upper chamber of the base valve in FIG.

FIG. 5 is a sectional view showing a main part of a hydraulic shock absorber according to another embodiment of the present invention.

FIG. 6 is a plan view of the check valve in FIG.

FIG. 7 is a sectional view showing a main part of a conventional hydraulic shock absorber.

8 is a plan view showing the leaf valve in FIG. 7. FIG.

9 is a plan view showing another leaf valve in FIG. 7. FIG.

[Explanation of symbols]

 21 Outer Shell 22 Cylinder 23 Base Valve Case 24 Leaf Valve 25 Pressure Side Port 26 Non-Retan Valve 27 Extension Side Port 28,41 Check Valve 29 Reservoir Chamber 30,43 Volume Chamber 31,42 Port Hole 38 Base Valve Upper Chamber 39 Outer Shell Chamber (Reservoir chamber)

Claims (1)

[Scope of utility model registration request] 1. A base valve case provided at a lower end of a cylinder inside an outer shell and having a pressure side port closed by a leaf valve, and a non-return valve closing an expansion side port provided at the base valve case,
A reservoir chamber and a chamber communicating with the outer shell chamber are defined below the base valve case, and hydraulic oil flowing from the pressure side port through the chamber during the pressure stroke is delivered to the reservoir chamber through its own plurality of port holes. Then, on the other hand,
A hydraulic shock absorber provided with a check valve that separates from the valve seat during the extension stroke and sends the hydraulic oil in the reservoir chamber to the base valve upper chamber via the volume chamber and the extension side port.