JPH023064B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic shock absorber used primarily in vehicles such as two-wheeled vehicles.

Conventionally, the present applicant has proposed, for example, a hydraulic shock absorber as shown in Japanese Utility Model Publication No. 48-4468, which alleviates the impact of a hydraulic shock absorber when it is fully compressed to prevent it from bottoming out. This is because a hole for inserting the oil hole is provided in the lower part of the piston rod, which reduces the cross-sectional area of that portion of the piston rod, which is disadvantageous in terms of strength.

Furthermore, the applicant has also proposed a method as shown in, for example, Utility Model Publication No. 53-26550. this is,
The damping force is adjusted by inserting an operating rod into the piston rod and varying the opening area of the orifice, but the structure is complicated and processing is difficult, resulting in high costs.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a hydraulic shock absorber with a simple structure that narrows the pressure side flow communication path at the time of maximum compression to obtain a large damping force and prevent bottoming out. It is an object.

Embodiments of the present invention will be described below based on the drawings.

As shown in FIG.
It is formed into a double structure by an outer tube 2 surrounding it, and an oil reservoir D having an air chamber E in the upper part is defined between them.

The cylinder 1 houses a slidable piston 3 therein, and the piston 3 defines the inside of the cylinder 1 into upper and lower sealed oil chambers A' and A.

At the bottom of this cylinder 1, a spool 4 that slides inside the cylinder 1 is attached to a cover 5 of the cylinder 1.
It is provided around the bolt 6 attached to the spool 4 and is biased upward by a return spring 7 interposed between the spool 4 and the cover 5, and its upper surface is pressed against the lower surface of the head of the bolt 6. There is.

A passage B is defined by the spool 4, the cover 5, and the bolt 6, and the oil chamber A communicates with the passage B through a port 8 provided in the spool 4.
The cylinder 1 is connected to an oil reservoir chamber D through a port 9 provided in the cylinder 1, and a return spring 7 urges the spool 4 to open the port 9.

Further, the lower end of the detection spring 10 is locked at the upper part of the spool 4, and when the piston 3 presses the upper end, the spool 4 is lowered (right row in the figure) in balance with the return spring 7, and the spool 4 Port 9 is configured to be throttled.

Next, the action will be explained.

When the piston 3 descends from the most extended state shown in the figure,
The hydraulic oil corresponding to the volume entered by the piston flows from the oil chamber A into the oil reservoir chamber D through the port 8 of the spool 4, the passage B, and the port 9. At this time, a damping force is generated due to the throttle resistance caused by the port 8.

Next, after the piston 3 contacts and compresses the detection spring 10, a downward force acts on the spool 4 due to the compression. When the piston 3 reaches the lowest position, the acting force becomes maximum, and the spool 4 descends against the biasing force of the return spring 7, narrowing the port 9.
or close. At this time, a large damping force is generated due to the throttle resistance of port 9, and this damping force causes piston 3
This prevents movement of the compressor, absorbs and softens the shock when fully compressed, and prevents bottoming out.

FIG. 2 shows another embodiment.

This has spool 4 and port 1 in the middle of the communication path.
Valve stopper 12 and proportional valve 1 forming 1
3 (base valve) defines passages B, B' and an oil chamber C, and similarly to the above, when the spool 4 moves at maximum compression, the port 11 is throttled to prevent bottoming out. Further, a proportional valve 13 proportionally controls the compression side damping force.

FIG. 3 shows yet another embodiment.

This is achieved by a spring seat 15, a spool 4, a valve stopper 12, and a proportional valve 13, which have a port 14 in the middle of the communication path.
B', defines an oil chamber C, with cutout oil passages 16 and 17 at the engagement part of the spool 4 and the valve stopper 12.
, and the movement of the spool 4 narrows the notched oil passage 16 to prevent bottoming out.

FIG. 4 shows yet another embodiment.

This has a spool 4 with a port 8 in the middle of the communication path, a valve stopper 12, a proportional valve 13, and a relief valve 20 that is biased upward by a relief spring 18 and closes the port 19. B' defines an oil chamber C.

In addition to restricting the port 11 of the valve stopper 12 by moving the spool 4 to prevent bottoming out, the hydraulic oil flows into the oil reservoir D through the proportional valve 13, oil chamber C, and port 21 in the low speed range, resulting in damping. The force is proportional. On the other hand, in the high speed range, passage B' and oil chamber C
The differential pressure increases, causing the relief valve 20 to descend against the relief spring 18 and opening the port 19. As a result, hydraulic fluid flows from passage B' to port 19.
The damping force is of the high-speed cut type.

FIG. 5 shows yet another embodiment.

This is because a check valve 22 is provided in the valve stopper 12 in the embodiment shown in FIG. 4 so that it opens when the expansion side is activated, and when the spool 4 is expanded from the most compressed state, the port 11 is throttled by the detection spring 10. Until the piston 3 separates from the upper end of the detection spring 10, there is no suction passage for the expansion operation, and negative pressure tends to occur below the piston, but at this time the check valve 22 opens to improve suction.

FIG. 6 shows yet another embodiment.

This invention is based on the hydraulic shock absorber previously proposed by the applicant, which uses a proportional type damping force in the low speed range and a cut type damping force in the high speed range, and further increases the cut value according to the internal pressure depending on the stroke position. This is an application of the bottoming prevention valve device configuration.

That is, the valve device V provided in the middle of the communication path
spool 4 with port 8, upper piece 2
3. A spool 25 that responds to the differential pressure between internal pressure and external pressure via a diaphragm 24 biased by a return spring 29, a bearing 26 at the end of the cylinder 1 that houses and locks this spool 25, and one end attached to this bearing 26. A relief valve 28 is provided with a proportional valve 13 that is housed and locked in the bearing 26 and is biased to close the port 19 by the relief spring 27. B″, an oil chamber C is defined.

As the spool 4 moves, the notched oil passage 30 formed in the spool 4 is constricted to prevent bottoming out, as described above, and furthermore, at low speed, the hydraulic oil flows through the proportional valve 13, the passages B', B'', and the ports 31, 32. , the oil chamber C, and the oil reservoir chamber D through the ports 33 and 34, so that the damping force becomes proportional.

On the other hand, when the stroke is small in the high speed range, the internal pressure is low, and the spool 25 is connected to the diaphragm 24.
The passage B'' and the oil chamber C are in communication with each other through the ports 31 and 32. At this time, the pressure in the passage B'' and the oil chamber C is lower than that in the oil reservoir chamber. It is almost the same as the pressure of D. Therefore, the differential pressure ΔP ₁ between the oil chamber A, the passage B'', and the oil chamber C acts on the outer diameter cross-sectional area πd ² ₁ /4 of the valve device V, and the acting force ΔP ₁ πd ² ₁ /4 acts on the relief spring 27 When the biasing force is exceeded, the relief valve 28 descends (rightward).
Then, port 19 opens and high-speed cutting is performed.

In addition, when the stroke is large in the high speed range, the internal pressure is high and the spool 25 is
9, and the flow of oil into the oil chamber C is cut off. Therefore, oil chamber A and passage B'' have almost the same pressure, and the pressure difference ΔP ₃ between oil chamber A and oil chamber C is
When _the acting force ΔP ₃ πd ² ₂ /4 exceeds the biasing force of the relief spring ²⁷ , the relief valve 28 moves downward and the port 19 opens. This results in a high-speed cut.

In this way, as the stroke increases, the effective pressure receiving area of the valve device V decreases from d ² ₁ to d ² ₂ , and the cracking pressure at the port 19 increases by the amount of this change, resulting in a large cut value. It will be done.

FIG. 7 shows yet another embodiment.

This eliminates the return spring 7 in the embodiment shown in FIG. 6 and allows the relief spring 27 to also function as a return spring.
By eliminating the spool 4 and moving the valve stopper 12, the relief valve 28 is lowered to throttle the opened port 19 during high-speed cutting to prevent bottoming out.

As explained above, in the present invention, since the pressure side flow communication passage is narrowed at the time of maximum compression, a large damping force can be obtained, and as a result, bottoming out can be reliably prevented and costs can be reduced. There is.

[Brief explanation of drawings]

1 to 7 are side sectional views of main parts showing embodiments of the present invention, respectively. 1...Cylinder, 2...Outer tube, 4...
...Spool, 7...Return spring, 10...
...Detection spring, 12...Valve stopper, 1
3... Proportional valve, 18... Relief spring, 19... Port, 20... Relief valve, 22
...Check valve, 24...Diaphragm, 25...
...Spool, 26...Bearing, 28...Relief valve, 29...Return spring.

Claims (1)

[Claims] 1. In a hydraulic shock absorber that has a sealed air chamber and an oil reservoir chamber inside, and is equipped with a communication path that allows hydraulic oil to flow from the oil chamber that contracts during pressure side operation to the oil reservoir chamber, there is a A valve device is provided, and this valve device includes a spool housed in a communication passage, a return spring that urges the spool to open the communication passage, and one end of which is locked to the spool and the other end that detects the position of the piston. A hydraulic shock absorber is characterized in that the spool is configured to include a detection spring that compresses the air, and a spool that is pressed by the detection spring near maximum compression narrows a communication path.