JPH04266635A - Damping force regulating type hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To ensure the switching of a damping force by increasing the operating force of the damping force regulating valve of a damping force regulating type hydraulic shock absorber. CONSTITUTION:A piston 4 having oil passages 5, 6 is fitted to a cylinder 3 in such a manner as to be capable of sliding. The cylinder upper chamber 3a and cylinder lower chamber 3b partitioned by the piston 4 are allowed to communicate each other by a bypass passage 13, and a pilot selector 14 for opening and closing the bypass passage 13 is provided. A hydraulic unit 28 for generating a pilot pressure through a control valve 29 is connected to a pilot selector 12. According to this constitution, the pilot pressure is supplied and released from the hydraulic unit 28 to the pilot selector 14 by switching the control valve 29, whereby the bypass passage 13 can be opened and closed to regulate a damping force. Since a large pilot pressure can be easily generated by the hydraulic pressure generated by the hydraulic unit 28, the damping force can be certainly switched.

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 used in a suspension system for a vehicle such as an automobile.

0002

[Prior Art] Hydraulic shock absorbers used in suspension systems for vehicles such as automobiles have damping force characteristics that can be adjusted as appropriate to improve ride comfort and handling stability depending on road surface conditions, driving conditions, etc. There is a damping force adjustable hydraulic shock absorber.

[0003] Conventionally, this type of hydraulic shock absorber includes a piston that divides the inside of the cylinder into two chambers in a cylinder filled with oil, such as the one described in Japanese Patent Laid-Open No. 61-163011. are slidably fitted together, an oil passage communicating the two chambers is formed in the piston, a damping force generating mechanism is provided in this oil passage, and the two chambers are fitted in the piston rod connected to the piston. Some are equipped with a bypass passage that communicates the chambers and a solenoid valve that opens and closes this bypass passage. With this configuration, the damping force is adjusted by energizing the solenoid, moving the plunger, opening and closing the valve, and switching the flow path of the oil fluid as the piston slides.

0004

[Problems to be Solved by the Invention] However, the above conventional example has the following problems. In other words, since the pressure of the oil in the cylinder exerts resistance to opening and closing the valve, a large solenoid is required to increase the operating force of the valve, and it is difficult to incorporate the solenoid valve into the piston rod. There is.

[0005]Also, if oil is introduced to the back side of the valve so that the pressure of the oil in the cylinder does not affect the opening and closing of the valve, the solenoid can be made smaller, but the shape of the valve is complicated. Therefore, there is a problem in that it is costly.

Furthermore, there is a problem in that when the temperature of the solenoid increases due to the temperature increase due to the operation of the hydraulic shock absorber, the electrical resistance increases and the operating force of the solenoid decreases.

The present invention has been made in view of the above points, and an object of the present invention is to increase the operating force of a damping force regulating valve that opens and closes a bypass passage.

[0008]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the damping force adjustable hydraulic shock absorber of the present invention provides a hydraulic shock absorber in which two chambers are connected to each other by sliding a piston in a cylinder. A damping force adjustment type that generates a damping force by controlling the flow of oil generated in the chamber, and also makes it possible to adjust the damping force by opening and closing a bypass passage that communicates between the two chambers using a damping force adjustment valve. A hydraulic shock absorber is provided, a pilot type damping force regulating valve is used as the damping force regulating valve, and a hydraulic supply/discharge means for supplying and discharging pilot pressure is connected to the damping force regulating valve.

[0009]

[Operation] With this structure, the damping force can be adjusted by opening and closing the bypass passage by supplying and discharging the pilot pressure generated by the hydraulic supply/discharge means to the damping force adjusting valve. Further, since a large pilot pressure can be easily obtained by the hydraulic pressure of the hydraulic supply/discharge means, the operation of the damping force adjustment valve can be ensured.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, a hydraulic shock absorber 1 is interposed between the vehicle body side and the wheel side of a suspension system of a vehicle such as an automobile, and the hydraulic shock absorber 1 includes a hydraulic circuit 2 (hydraulic supply and discharge means). is connected.

The hydraulic shock absorber 1 will be explained. A piston 4 that partitions the inside of the cylinder 3 into two chambers, an upper cylinder chamber 3a and a lower cylinder chamber 3b, is slidably fitted into the cylinder 3 filled with oil and gas. The piston 4 is provided with oil passages 5 and 6 that communicate the upper cylinder chamber 3a and the lower cylinder chamber 3b. In the oil passage 5,
A check valve mechanism 7 that allows oil fluid to flow from the cylinder upper chamber 3a to the cylinder lower chamber 3b during an extension stroke, and a damping force generation mechanism 8 that controls the flow of this oil fluid and generates a damping force are provided. There is. The oil passage 6 includes a check valve mechanism 9 that allows oil to flow from the lower cylinder chamber 3b to the upper cylinder chamber 3a during the contraction stroke, and a damping force generator that controls the flow of this oil to generate a damping force. A mechanism 10 is provided. One end of the piston rod 11 is connected to the piston 4, and the other end of the piston rod 11 is connected to the vehicle body, and the cylinder 3 is connected to the wheel side. In addition, in the figure, 12 is a suspension spring.

A bypass passage 13 is provided that communicates the upper cylinder chamber 3a and the lower cylinder chamber 3b, and the bypass passage 13 is provided with a pilot switching valve 14 as a damping force adjustment valve that opens and closes the bypass passage 13. .

As shown in FIG. 2, the pilot switching valve 14 includes, within the case 15, a cylinder upper chamber side passage 16 connected to the cylinder upper chamber 3a and a cylinder lower chamber side passage 17 connected to the cylinder lower chamber 3b. The cylinder upper chamber side passage 16 and the cylinder lower chamber side passage 17 are communicated with each other via an annular valve seat 18. Inside the cylinder lower chamber side passage 17, there is a pointed end 19a facing the valve seat 18.
A valve body 19 (poppet) is provided, which is seated on and off the valve seat 18, and the valve body 19 is urged toward the valve seat 18 by a spring 20. A valve seat 1 is provided in the cylinder upper chamber side passage 16.
A pilot piston 21 is slidably fitted opposite to the valve seat 8, and the pilot piston 21 is urged toward the valve seat 18 by a spring 22 whose elastic force is smaller than that of the spring 20, and the pilot piston 21 is urged toward the valve seat 18 side by a spring 22 having a smaller elastic force than the spring 20. The formed convex portion 21a is the valve body 19
It is in contact with the pointed end 19a of. The case 15 is provided with a pilot pressure supply passage 23 communicating with the back side of the pilot piston 21, and the hydraulic circuit 2 is connected to the pilot pressure supply passage 23.

With this configuration, the pilot pressure supply passage 2
When the pilot pressure No. 3 is released, the tip 28a of the valve body 19 is seated on the valve seat 18 due to the elastic force of the spring 20, and the cylinder upper chamber side passage 16 and the cylinder lower chamber side passage 1 are connected to each other.
7, and the bypass passage 13 is closed. Further, when pilot pressure is supplied from the pilot pressure supply passage 23 to the back side of the pilot piston 21, the pilot piston 21 moves toward the valve seat 18 side due to the pressure, and the convex portion 21a touches the tip portion 19a of the valve body 19. It is pressed and separated from the valve seat 18, and the cylinder upper chamber side passage 16 and the cylinder lower chamber side passage 17 are communicated with each other, and a bypass passage 13 having a throttle 13a and generating a predetermined damping force is connected.

The hydraulic circuit 2 will be explained. pump 24
, a reservoir tank 25, a suction filter 26, and a relief valve 27 for keeping the discharge pressure of the pump constant, forming a hydraulic unit 28 that generates hydraulic pressure. The discharge side of the hydraulic unit 28 is branched into four parts, each of which has a control valve 29 (3 port 2 position switching valve).
is connected. Here, the control valve 29 is
There are four provided corresponding to each ring, and since they are similar, only one will be described below. One of the other two ports of the control valve 29 is connected to the pilot passage 30
The other end is connected to the pilot switching valve 14 through a return passage 31, and the other end is connected to a reservoir tank 25 through a return passage 31. By switching the control valve 29, the pilot passage 30 and the discharge side of the hydraulic unit 28 or the pilot passage 30 and the return passage 31 are selectively brought into communication. The pilot passage 30 is provided with an orifice 32 for slowing the switching of the pilot switching valve 14.

The operation of this embodiment constructed as above will be explained next. When the control valve 18 is operated to communicate the pilot passage 30 and the return passage 31, the hydraulic pressure generated by the hydraulic unit 28 is shut off by the control valve 29, the hydraulic pressure in the pilot passage 30 is reduced, and the pilot is switched. The pilot pressure of the valve 14 is released, and the bypass passage 13 is closed. Therefore, piston rod 1
As the piston 4 slides when the piston 3 expands and contracts, the oil in the cylinder upper chamber 3a flows through the oil passage 5 and flows into the cylinder lower chamber 3b during the extension stroke, thereby creating a damping force generating mechanism. 8 generates a damping force, and during the contraction stroke, the oil in the cylinder lower chamber 3b flows through the oil passage 6 and flows into the cylinder upper chamber 3a, so that the damping force is generated by the damping force generating mechanism 10. .

In this manner, when the bypass passage 13 is closed, the oil in the cylinder 3 flows only through the damping force generating mechanisms 8 and 10 provided on the piston 4, as shown by the solid line in FIG. This is a damping force characteristic (hard characteristic) that generates a relatively large damping force.

The pilot passage 30 is opened by operating the control valve 18.
When communicating with the discharge side of the hydraulic unit 28, the hydraulic pressure generated by the hydraulic unit 28 flows through the pilot passage 30.
The pilot pressure is transmitted to the pilot switching valve 14 through the pilot switching valve 14, and the pilot pressure is supplied to the pilot switching valve 14, and the bypass passage 13 is made conductive. Therefore, as the piston 4 slides when the piston rod 11 expands and contracts,
During the extension stroke, the oil in the cylinder upper chamber 3a flows through both the bypass passage 13 and the oil passage 5 and flows into the cylinder lower chamber 3.
By flowing into the cylinder b, a damping force that is smaller than the above-mentioned hard characteristics is generated, and during the contraction stroke, the oil in the cylinder lower chamber 3b flows through both the oil passage 6 and the bypass passage 13 and is applied to the top of the cylinder. By flowing into the chamber 3a, a damping force that is smaller than the above-mentioned hard characteristics is generated.

In this way, when the bypass passage 13 is in the conductive state, the oil in the cylinder 3 flows through both the damping force generating mechanisms 8 and 10 provided in the piston 4 and the bypass passage 13. This is a damping force characteristic (soft characteristic) that generates a relatively small damping force as shown by the broken line in 3.

Next, a second embodiment of the present invention in which a bypass passage and a damping force adjustment valve are built into the piston rod will be described. As shown in FIG.
A piston 34 that divides the inside of the cylinder 33 into two chambers, an upper cylinder chamber 33a and a lower cylinder chamber 33b, is slidably fitted within the cylinder 33, and a free piston 35 is slidably fitted inside the cylinder 33 on the bottom side. The upper cylinder chamber 33a and the lower cylinder chamber 33b are filled with oil, and the gas chamber 33c formed between the free piston 35 and the bottom of the cylinder 33 is filled with gas. Similar to the hydraulic shock absorber 1 in FIG. A contraction side oil passage 41 is provided.

A proximal end of a piston rod 42 is connected to the piston 34 through the piston 34.
A through hole 43 is bored in the axial direction. Through hole 43
An oil passage 4 that opens into the upper cylinder chamber 33a is formed on the side wall of the cylinder.
4 is bored, and the base end of the through hole 43 and the oil passage 4
4 constitutes a bypass passage 45 that communicates the cylinder upper chamber 33a and the cylinder lower chamber 33b. The bypass passage 45 (through hole 43) has an annular valve seat 46 formed in the middle thereof, and a valve seat that is slidably fitted on the proximal end side of the piston rod 42 with respect to the valve seat 46. A poppet valve mechanism that opens and closes the bypass passage 45 is provided, which is composed of a valve body 47 (poppet) that is seated on and off from the 46 section. The valve body 47 has a throttle passage 47b, is urged toward the valve seat 47 by a spring 48, and is seated on the valve seat portion 46. A rod 49 is inserted into the through hole 43 , one end of which abuts the pointed end 47 a of the valve body 47 , and the other end of which extends to near the tip of the piston rod 42 . A cylinder member 49 is attached to the tip of the piston rod 42, and a pilot piston 51 is slidably fitted into the cylinder member 50. The pilot piston 51 has a protrusion 51a formed on its front side that is inserted into the through hole 43 and abuts the end of the rod 49, and has a smaller elastic force than the spring 48 provided on its back side. It is urged toward the piston rod 42 by a spring 52. Cylinder member 50
A pilot pressure supply passage 53 is provided which communicates with the back side of the pilot piston 51 and is connected to the hydraulic circuit 2 .

With this configuration, the pilot pressure supply passage 5
When the pilot pressure No. 3 is released, the tip 47a of the valve body 47 is seated on the valve seat 46 due to the elastic force of the spring 48, and the bypass passage 45 is closed.

Furthermore, when pilot pressure is supplied from the pilot pressure supply passage 53 to the back side of the pilot piston 51, the pilot piston 51 moves toward the piston rod 42 side due to the pressure, and the convex portion 51a moves toward the rod 49.
, the rod 49 presses the pointed end 47a of the valve body 47 against the elastic force of the spring 48 to separate it from the valve seat 46, and the bypass passage 45 is opened.

By opening and closing the bypass passage 45, the damping force characteristics can be changed similarly to the hydraulic shock absorber 1 shown in FIG.

Further, as a third embodiment of the present invention, as shown in FIG. 5, the control valve 29 (switching valve) is replaced with a proportional pressure control valve 54 in the apparatus shown in FIG. 1, so that the pilot pressure can be adjusted. By using the pilot switching valve 14 (switching valve) as a flow control valve 55 that adjusts the flow rate according to the value of the pilot pressure, the damping force characteristics can be continuously adjusted.

The hydraulic unit 28 can be used in conjunction with an existing hydraulic unit provided as a hydraulic source for power steering, hydraulic suspension, and the like. In this case, the hydraulic pressure supplied to the hydraulic shock absorber is used only to obtain pilot pressure, so the consumption flow rate of pressure fluid is small and the output consumption is small.

In addition, although the control valves 29 and 54 are individually provided for each system of each hydraulic shock absorber 1 so that the damping force of each hydraulic shock absorber 1 can be adjusted independently, the present invention is not limited to this. The systems may be connected to one control valve 29, 54 so that all the damping forces can be switched at the same time, or two systems for the front and rear wheels may be configured so that the front and rear wheels can be switched independently. You can also.

[0028]

[Effect of the invention] The damping force adjustable hydraulic shock absorber of the present invention has the following features:
With the configuration described in detail above, the damping force can be adjusted by opening and closing the bypass passage by supplying and discharging the pilot pressure generated by the hydraulic supply/discharge means to the damping force adjustment valve. As a result, a large pilot pressure can be easily obtained by the hydraulic pressure of the hydraulic supply/discharge means, so that the damping force regulating valve can be operated reliably. Furthermore, since a large pilot pressure can be obtained, an inexpensive poppet valve can be used as the damping force adjustment valve, which has the excellent effect of reducing costs. Further, the hydraulic supply/discharge means can be used in combination with existing hydraulic supply/discharge means provided as a hydraulic source for power steering, hydraulic suspension, etc., so it does not take up much space and is inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the damping force adjustment valve of the device in FIG. 1;

FIG. 3 is a diagram showing damping force characteristics of the device in FIG. 1;

FIG. 4 is a longitudinal sectional view of a hydraulic shock absorber according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a third embodiment of the present invention.

[Explanation of sign]

1...Hydraulic shock absorber 2...Hydraulic circuit (hydraulic supply/discharge means) 3...Cylinder 4...Piston 5, 6...Oil liquid passage 13...Bypass passage

Claims (1)

[Claims] Claim 1: A damping force is generated by controlling the flow of oil generated in an oil passage communicating between two chambers by sliding a piston in a cylinder, and the two chambers are communicated. A damping force adjustable hydraulic shock absorber is provided in which the damping force can be adjusted by opening and closing a bypass passage using a damping force adjusting valve, and a pilot type damping force adjusting valve is used as the damping force adjusting valve to adjust the damping force. A damping force adjustable hydraulic shock absorber characterized in that a hydraulic supply/discharge means for supplying and discharging pilot pressure is connected to a regulating valve.