JPH02195041A - Hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To smooth the changeover of the force of damping, by giving energization by means of a spring so that the opening pressure of a disk valve provided at a piston or a base member may become high at the time of the piston being contracted. CONSTITUTION:An extending side control ring 12 is put on the outer perimeter of the nut 4 of a piston 5 so as to slide up and down freely, and a contracting side control ring 17 is put on a base member 14 so as to slide up and down freely, and a contracting side disk valve 19 is provided at its lower surface. Further, an appropriately free lengthed spring 20 whose one end is capable of butting against the extending side control ring 12 and whose other end is capable of butting against the contracting side control ring 17, is provided between the piston 5 and the base member 14. When the piston 5 is contracted in a loaded state, disk valves 10, 19 are energized by the elasticity of the spring 20, and a valve opening pressure is set highly, and a large damping force is obtained, and also, the changeover of the force of damping is conducted smoothly as it is done by the elasticity of the spring.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a hydraulic shock absorber installed in a vehicle or the like.

(Prior Art) Conventionally, various hydraulic shock absorbers have been proposed that can generate a large damping force when a vehicle is loaded to improve handling stability.

As this type of hydraulic shock absorber, for example,
There is a system disclosed in Japanese Patent No. 4939, in which the inside of an inner cylinder is divided into two chambers by a slidably fitted piston, a passage is formed in the piston that communicates the two chambers, and a passage is formed in the piston to communicate the two chambers. Disc valves that generate damping force are arranged in two places in series, and a side road is communicated between the two disc valves, so that under normal vehicle height conditions, one disc valve generates a small damping force. When the vehicle height is lowered and the piston is shortened, such as when the vehicle is loaded, the sleeve closes off the side passage, and a large damping force is generated by the combination of both disc valves.

Further, in the U, S, P, -4,095,682 publication, a piston rod is formed with a passage extending in its axial direction, and a piston rod is fixed to the lower side of the inner and outer cylinders within this passage. Insert a metering pin that is thin at the center and thick at the tip and base ends, and the metering pin and rebound valve provided in the piston form an annular orifice to maintain normal vehicle height. Then, the orifice should be located in the center of the metering pin or on the rebound valve to increase the opening area of the orifice and generate a small damping force. The thick part of the pin is located in the bound valve to reduce the opening area of the orifice and generate a large damping force.

(Problems to be Solved by the Invention) However, the conventional hydraulic shock absorber described above had the following problems.

First, in the hydraulic shock absorber disclosed in Japanese Patent Publication No. 58-14939, the damping force is opened and closed by a bypass sleeve, and the small damping force generated by one disc valve and the large damping force generated by the combination of two disc valves. Therefore, there is a problem in that a sudden change in damping force occurs at the time of switching, resulting in poor maneuverability and poor riding comfort.

In addition, the hydraulic shock absorber disclosed in U.S.P.-4,095,682 merely changes the opening area of the orifice provided in the passage in the piston rod, and the The switching range of damping force by the valve depends on the range of change in the opening area of this orifice, so in order to set a large switching range of damping force in the high-speed operating range, the opening area of the orifice must be changed significantly. However, if the opening area of the orifice is changed significantly, the damping force in the piston's low-speed operating range will change excessively, resulting in poor maneuverability and ride comfort, and it may be difficult to ensure sufficient damping force in the low-speed operating range. There was a problem that it became difficult to read.

The present invention has been made in view of the above-mentioned problems, and its purpose is to smoothly switch the damping force in the high-speed operation range without significantly affecting the damping force in the low-speed operation range of the piston. An object of the present invention is to provide a hydraulic shock absorber that allows switching of the damping force in the hydraulic shock absorber.

(Means for Solving the Problems) The hydraulic shock absorber of the present invention has an inner cylinder divided into two chambers by a slidable piston, and a base member provided at the lower part of the inner and outer cylinders. A disc valve is provided on the piston to separate the inside and outside of the cylinder, and to generate a damping force by controlling the flow of oil fluid generated between the two chambers by sliding of the piston during an extension stroke, A hydraulic shock absorber comprising a disc valve that generates a damping force by controlling the flow of oil between the inner cylinder and the outer cylinder due to the sliding of the piston during a retraction stroke, wherein the piston and the A splinter is interposed between the piston and the base member, and when the piston is shortened, at least one of the disc valves provided on the piston or the base member is biased by the spring so that the opening pressure thereof is increased. This is a characteristic feature.

(Function) According to the above configuration, a damping force is obtained due to the characteristics of the disc valve in the normal vehicle height state, and when the piston is shortened in the loaded state, the disc valve is urged by the elastic force of the splinter and the valve opening pressure is (Pressure difference required to open the valve) is set high and a large damping force can be obtained. And since this switching of damping force is based on the elastic force of the spring,
The damping force can be changed smoothly without sudden changes, and because the spring independently switches the damping force in the piston's high-speed operating range, it is possible to set the damping force separately in the low-speed operating range of the orifice, etc. There are no problems such as insufficient damping force in the low-speed operating range.

(Example) Next, embodiments of the present invention will be described based on the drawings.

l is the inner cylinder, 2 is the outer cylinder, and the piston rod 3 is inside the inner cylinder l.
A piston 5 fixed by a nut 4 is slidably fitted to the tip of the inner cylinder 1, and the inside of the inner cylinder 1 is divided into two chambers, an upper chamber 6 and a lower chamber 7, by this piston 5. Two types of passages 8 and 9 are formed in the piston 5 at different positions in the radial direction to communicate the upper chamber 6 and the lower chamber 7, and on the end surface of the piston 5 on the lower chamber 7 side, An extension side disc valve 10 is installed so as to close one passage 8 formed inside the piston 5, and an extension side disc valve 10 is attached to the end face of the piston 5 on the upper chamber 6 side. A check valve 11 is provided to close the passage 9. This check valve 11 allows oil to flow from the lower chamber 7 to the upper chamber 6 through the other passage 9, and restricts the flow of oil in the opposite direction.

On the outer periphery of the nut 4, there is provided the expansion side disc valve l.
An extension side control ring 12 having an annular protrusion 12a that contacts the outer circumferential edge of the O is fitted on the outside so as to be able to freely slide up and down, and downward movement is restricted by a stepped portion 4a formed on the nut 4. ing.

An extension-side orifice 5a consisting of a notch that communicates the upper chamber 6 and the lower chamber 7 is formed on the seat surface side of the piston 5 that the extension-side disc valve 10 comes into contact with.

A base member 14 is provided below the inner cylinder 1 and the outer cylinder 2, and the base member 14 partitions the inside of the inner cylinder l and the inside of the outer and outer cylinders 13. Connecting passageway 15
is formed. A check valve 16 is provided on the lower chamber 7 side of the base member 14 so as to close a passage 15, and this check valve 16 allows oil to flow from the inner and outer cylinders 13 into the inner cylinder 1 through the passage 15. It allows oil to flow in the opposite direction and restricts the flow of oil in the opposite direction.

A contraction side control ring 17 is fitted onto the base member I4 so as to be able to freely slide up and down, and the contraction side control ring 17 has a passage 1 that communicates between the inside of the inner cylinder 1 and the inside of the inner and outer cylinders 13.
8 is formed. A compression disc valve 19 is provided on the lower surface of the compression control ring 17 so as to close the passage 18, and a base member 14 is provided on the opposite surface of the compression disc valve 19 from the compression control ring 17. When the retraction-side control ring I7 is lowered, the outer circumferential side of the retraction-side disc valve 19 is bent using the protrusion 14a as a fulcrum, and the inner circumferential side is further pushed against the valve seat 14c. There will be strong contact.

In addition, a contraction side orifice 14b consisting of a notch that communicates the inside of the inner cylinder 1 with the inner and outer cylinders 13 is formed in the protrusion 14a of the base member 14 that comes into contact with the contraction side disc valve 19.

There is an appropriate free length between the piston 5 in the lower chamber 7 and the base member 14, with one end capable of contacting the extension side control ring 12 and the other end capable of contacting the extension side control ring 17. A spring 20 having a diameter is interposed.

The operation of the hydraulic shock absorber having the above configuration will be explained.

First, in the low-speed operating range of the piston 5 during the extension stroke under normal vehicle height conditions, the pressure of the oil in the upper chamber 6 is higher than the pressure of the oil in the lower chamber 7, and the pressure difference causes the oil to flow. The flow is controlled by the extension side orifice 5a and a damping force is generated. In addition, in the high-speed operation range of the piston 5,
Extension side disc valve 10 provided on the piston 5
is bent to control the flow of oil in the passage 8 and generate a damping force. Note that during the extension stroke, the oil in the inner cylinder 1 is insufficient by the volume of the piston rod 3 coming out of the inner cylinder 1, but the check valve 16 provided on the base member 14
is opened and the oil inside the inner and outer cylinders 13 is replenished.

In addition, in the low-speed operation range of the piston 5 during the retraction stroke, the pressure of the oil in the lower chamber 7 becomes higher than the pressure of the oil in the upper chamber 6, and the check valve 11 provided in the piston 5
is opened, and the oil in the lower chamber 7 flows into the upper chamber 6 through the passage 9, but the oil in the inner cylinder 1 flows into the base member 14 by the volume that has entered the piston rod 3 or the inner cylinder 1. Flows from the contraction side orifice 14b provided in the inner and outer cylinders 13,
At this time, the flow of oil is controlled to generate damping force.

In addition, in the high-speed operation range of the piston 5, the compression disc valve 19 provided on the base member 14 bends to control the flow of oil in the passage 18 of the compression control ring 17 to generate damping force.

In this way, during normal running, the orifices 5a, 14
A damping force characteristic is obtained based on the opening area of b and the characteristics of each disc valve 10.19 (set by the material, plate thickness, number of disc valves, etc.).

Next, when the piston 5 is shortened when the vehicle is loaded, it comes into contact with the free-length spring 20 interposed between the piston 5 and the base member 14, elastically deforms it, and expands due to its elastic force. The side control ring 12 is urged upward, and its protrusion 12a presses the outer peripheral edge of the expansion side disc valve 10 to increase the valve opening pressure.
Furthermore, the elastic force of the spring 20 urges the compression side control ring 17 downward, and the protrusion 14a of the base member 14 bends the outer circumferential side of the compression side disc valve 19 to increase the valve opening pressure on the inner circumferential side. make it change

In the low-speed operation range of the piston 5 when the piston 5 is shortened, a damping force is generated in which the damping force generated by each orifice 12a, 14b and the biasing force of the spring 20 are combined, and in the high-speed operation range, the spring 20 A damping force is generated by each disc valve 10.19, which is energized and whose opening pressure is changed to a higher value.

In this way, when loading a vehicle, the orifices 12a, 1
A large damping force is obtained by combining the opening area of 4b or each day, the characteristic of Suffharz 10.19, and the elastic force of the spring 20. Since the elastic force of the spring 20 increases in proportion to its displacement (amount of contraction),
The force applied to each disc valve 10, 19 gradually increases, and the damping force is smoothly switched between large and small values.

In addition, the damping force in the low-speed operating range and the switching width in the high-speed operating range of the piston 5 can be set independently and do not affect each other, so the setting of the damping force characteristics is different between the low-speed operating range and the high-speed operating range. It can be done separately.

In the hydraulic shock absorber of this embodiment, in the normal vehicle height condition,
When the piston 5 moves significantly, such as when passing over a convex portion, a large damping force is generated in the shortening direction, so that the shaking of the vehicle can be damped quickly.

In this embodiment, both the extension side disc valve 10 provided on the piston 5 and the compression side disc valve 19 provided on the base member 14 are connected to the spring 2.
0 to change the valve opening pressure, the present invention is not limited to this, but either the expansion side disc valve 10 or the contraction side disc valve 19 is biased by the spring 20. The valve opening pressure may also be changed.

Further, the length of the free length of the spring 20 can be set as appropriate, and by changing the length, the starting position of the valve opening pressure change can be arbitrarily selected. control ring 12
．． These may be biased by coming into contact with 17.

Furthermore, by changing the spring constant of the spring 20, the damping force by the disc valve 10.19 during contraction can be arbitrarily varied according to the stroke position of the piston rod 3, and the number of springs can also be changed.
It is possible to obtain various damping force characteristics by combining not only a book but also a plurality of pieces with different free lengths and spring constants.

(Effects of the Invention) As explained in detail above, the present invention provides a spring between the piston and the base member of a hydraulic shock absorber, and when the piston is shortened, the disc valve provided on the piston or the base member is activated. Since the valve opening pressure is changed by energizing at least one side with a splinter so that the valve opening pressure becomes higher, the damping force can be smoothly switched between large and small damping forces. As a result, the steering stability and ride comfort of the vehicle can be improved.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view of a hydraulic shock absorber according to an embodiment of the present invention. 1... Inner cylinder 2... Outer cylinder 5... Piston 6... Upper chamber 7... Lower chamber 10... Extension side disc valve 13... Inside and outside cylinder 14... Base member 19
...Compression side disc valve 20...Sprinter patent applicant Tokico Co., Ltd.

Claims (1)

[Claims] (1) The inside of the inner cylinder is divided into two chambers by a slidable piston, and the inside of the inner cylinder and the inside of the outer cylinder are divided by a base member provided at the bottom of the cylinder. A disc valve is provided in the base member to generate a damping force by controlling the flow of oil between the two chambers due to the sliding of the piston during the retraction stroke, and A hydraulic shock absorber is provided with a disc valve that generates a damping force by controlling the flow of oil between the inner and outer cylinders, wherein a spring is interposed between the piston and the base member, and the piston A hydraulic shock absorber, characterized in that the spring biases at least one of the piston or the disc valve provided on the base member so that its opening pressure increases when the piston is shortened.