JPS6124576B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a hydraulic shock absorber with a piston structure in which the compression damping force is generated by a base valve provided at the lower end of the cylinder, in which a part of the compression damping force is borne by the piston side. This invention relates to a damping force generating device in a hydraulic shock absorber.

The first known hydraulic shock absorber
There is something like the picture. A piston rod 3 is telescopically inserted into a cylinder 1 via a piston 2, and inside the cylinder 1 there are two upper and lower liquid chambers 4,
5 is partitioned by the piston 2. A base valve 6 is disposed at the lower end of the cylinder 1, and an outer tube 7 coaxial with the outer tube 7 is attached to the outside of the cylinder 1, and a tank chamber 8 is formed between the outer tube 7 and the cylinder 1. Moreover, the lower liquid chamber 4 and the tank chamber 8 communicate with each other via the base valve 6.

A passage 9 for both the expansion side and the compression side is bored in the piston 2 in the axial direction, and this passage 9 allows the upper and lower liquid chambers 4 and 5 to communicate with each other.

Further, a plate valve 10 is disposed at the upper end of the passage 9 to generate a damping force during the expansion operation and to allow free flow during the compression operation, so that the damping force during the expansion operation can be generated.

In the hydraulic shock absorber as described above, when it is extended, a flow rate corresponding to the difference between the cross-sectional area of the inner diameter of the cylinder 1 and the cross-sectional area of the outer diameter of the piston rod 3 multiplied by the extension speed is transferred from the upper liquid chamber 5 to the lower liquid chamber 4. The plate valve 10 is deflected, and the water flows out through the passage 9 to obtain a damping force. Also, during compression, part of the oil in the reduced volume of the liquid chamber 4 pushes up the plate valve 10 through the passage 9 and flows out into the upper liquid chamber 5 with little resistance, and the oil corresponding to the volume entered by the piston rod 3 flows from the base valve 6 into the tank chamber. At this time, the damping force during compression is obtained by the action of the base valve 6. However, in this case, the compression side damping force is determined by the flow rate passing through the base valve 6 corresponding to the intrusion volume of the piston rod 3, but since the flow rate is small, a sufficient damping force cannot be obtained. In order to solve this problem, by narrowing down the passage in the piston section that causes the oil in the lower liquid chamber 4 to flow out to the upper liquid chamber, a pressure difference will be generated between the two liquid chambers, and a part of the pressure-side damping force will be transferred to the piston section. It is possible to make up for the shortfall in the base valve. This method is called back aperture and is a generally known technique.

However, in the case where the plate valve 10 is provided at the upper end of the opening of the single passage 9 as shown in FIG. If the area of the passage 9 is reduced in order to burden the second side as well, it will conversely act as an orifice also on the rebound side, and the high speed range of the rebound side damping force will rise rapidly, resulting in an over-damped state. In this way, in a piston structure that has a single passage 9 for both expansion and compression, reducing the passage area solely for the purpose of rear throttling would actually affect the damping force on the expansion side, making it practically unusable. It is.

Therefore, the present applicant has installed a single leaf valve with an orifice hole and a ring seat at the lower mouth end of a single passage shared by extension without drastically changing the structure of the piston. By simply placing a plate valve at the top opening of the passageway that generates damping force and allows free flow during compression, it can perform the same action as a rear throttle without affecting the rebound damping force. We have developed a damping force generator for hydraulic shock absorbers. A longitudinal cross-sectional side view of the piston of this newly developed hydraulic shock absorber is shown in FIG.

This piston is slidably inserted into the cylinder 1 of the hydraulic shock absorber as shown in FIG. According to this, one or more through holes 15 are bored in the body of the piston 11 in the axial direction to allow the upper and lower liquid chambers 4 and 5 to communicate with each other.

Next, a leaf valve 22 is installed at the lower mouth end of the through hole 15.
are arranged in series so as to be freely openable and closable, and this leaf valve 22 has an orifice or notch 23 formed at a position opposite to the through hole 15, so that even when the leaf valve 22 is closed, this orifice or notch 23 2
Through hole 15 through hole 14 or lower liquid chamber 4
I'm starting to understand this.

The center part of the leaf valve 22 may be directly sandwiched between the upper end surface of the nut 13 and the lower end surface of the piston 11, but as shown in the figure, there is an orifice or notch on the lower side of the leaf valve 22, which has a smaller diameter than the leaf valve 22. A ring seat 24 which does not interfere with the ring 23 may be interposed to hold the ring 23 in place.

In the above hydraulic shock absorber, the piston 11 rises during extension, and at this time, the oil in the upper liquid chamber 5 flows out into the through hole 15 while deflecting the plate valve 16. At this time, the plate valve 16 acts to exert a damping force on the extension side. occurs. and,
Oil from the through hole 15 pushes open the leaf valve 22 and flows out into the lower liquid chamber 4.

Conversely, when the piston 11 is on the pressure side, the piston 11 descends, and a portion of the oil in the liquid chamber 4 flows through the orifice or notch 23 of the leaf valve 22 to the plate valve 1 through the through hole 15.
6 is pushed open to flow out into the upper liquid chamber 5, and some oil flows out into the tank chamber 8 via the base valve 6. At this time, the damping force on the compression side is obtained by the action of the base valve 6 and the orifice or notch 23 of the leaf valve 22. That is, the orifice or notch 23 compensates for the lack of damping force of the base valve 6, and the desired damping force can be obtained.

However, it has been noticed that even this newly developed hydraulic shock absorber has the following drawbacks. That is, if an orifice or notch 23 is attached to the leaf valve 22, the strength of the leaf valve 22 will be adversely affected, and since the leaf valve 22 is made of a spring steel plate such as a Swedish steel plate, the orifice or notch 23 will be Processing had to be carried out using a press die, making it difficult to process freely, and the orifice area had to be selected from a limited number of types, making it impossible to set the back drawing as desired. That is, this is because having a large number of press molds is difficult in terms of production management and product cost.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks by providing one or more pressure-side rear throttle ports corresponding to orifices or notches in the piston part, and improving the strength of the leaf valve and setting the orifice area. It is an object of the present invention to provide a damping force generating device for a hydraulic shock absorber that eliminates anxiety.

One embodiment of the present invention will be described below with reference to FIG.

FIG. 3 shows a longitudinal side view of the piston of the invention, which piston is slidably inserted into the cylinder 1 of the same hydraulic shock absorber as in FIG.

A piston rod 12 is located in the center of the piston 11a.
A small diameter portion 12a of the base end passes through the piston 12a and is fixed to the piston 11a side with a nut 13. Piston 11a
A space 14 that is open to the lower liquid chamber 4 is bored at the lower end, and a nut 13 is accommodated in this space 14, but this space 14 is not necessarily necessary, and the piston rod 12 is installed at the lower end of the piston 11a. It may protrude and be fixed with a nut 13.

The body of the piston 11a is provided with one or more through holes 15, which are expansion-side exclusive passages, bored in the axial direction so that the upper and lower liquid chambers 4 and 5 communicate with each other only during the expansion operation.

Further, the piston 11a has a through hole 1 in the vertical direction.
5, one or more rear aperture ports 25 for common expansion and compression are bored to communicate the space 14 and the through hole 18. Originally, there may only be one rear throttle port 25, but if there is only one, the diameter needs to be increased, and in this case, there is a restriction due to the space for the piston 11a, and the swiss noise generated when passing through the port. Since it is smaller when divided into a plurality of ports having the same area than one port, it is preferable to divide the rear aperture port 25 into a plurality of ports.

There is an opening at the upper end of the piston 11a that communicates the upper end of the through hole 15 with the upper end of the back throttle port, and a plate valve 16 made of one or more stacked valves is disposed above this opening. The upper opening ends of the through hole 15 and the rear throttle port 25 can be opened and closed with respect to the upper liquid chamber 5. Piston 11a
A plurality of support legs 17 are fixed to the outer periphery of the upper part of the upper liquid chamber 5.
communicates with the through hole 15 and the rear throttle port 25, and the outer periphery of the plate valve 16 is supported inside the support leg 17, so that the piston 11
It is held so that it does not shift laterally from the top of a.

A support member 19 having one or more through holes 18 in the axial direction is disposed on the plate valve 16 so as to be movable up and down, and a spring 20 or other elastic member is interposed between the support member 19 and the support legs 17. The restoring force of the spring 20 constantly presses the plate valve 16 through the support member 19 in a direction to close the opening end of the through hole 15 and the rear throttle port 25.

A support plate 21 that is horizontal or slightly inclined upward is interposed on the support leg 17, and supports the support leg 17, the spring 20, the support member 19, and the support plate 21 above the piston 11a.
The plate valve 16 is designed not to pop out upwards.

At the lower end of the through hole 15, the through hole 15 is opened during the compression stroke.
Leaf valves 22 without notches are arranged in series.

The center portion of the leaf valve 22 may be directly sandwiched between the upper end surface of the nut 13 and the lower end surface of the piston 11, but as shown in the figure, an annular seat 24 having a smaller diameter than the leaf valve 22 is interposed below the leaf valve 22. You can also hold it in place.

In the above hydraulic shock absorber, the piston 11a is
rises, and at this time, the oil in the upper liquid chamber 5 flows out from the through hole 18 into the through hole 15 and the rear throttle port 25 through the opening while bending the plate valve 16. side damping force is generated. Further, the oil from the through hole 15 pushes open the leaf valve 22, and the oil from the rear throttle port 25 directly flows into the lower liquid chamber 4.

On the other hand, when on the pressure side, the piston 11a descends, and some of the oil in the liquid chamber 4 flows out to the opening at the bottom of the plate valve 15 through the rear throttle port 25, and the effect due to the large pressure receiving area in this opening The plate valve 16 is pushed open under the pressure to allow free flow to flow into the upper liquid chamber 5.

Also, a part of the oil flows out into the tank chamber 8 through the base valve 6, and at this time, a damping force on the pressure side is obtained from both the base valve 6 and the rear throttle port 25. In other words, the rear throttle port 25 compensates for the lack of damping force of the base valve 6, but the rear throttle port 25, which is independent of the through hole 15, allows the damping force to be adjusted as desired without being affected by the setting conditions of the damping force on the rebound side. In addition, during this compression stroke, the leaf valve 22 closes the through hole 15 and the plate valve 16 operates under a large pressure receiving area to ensure free flow. Because you can
Only the rear throttle port 25 serves as an oil passage without being affected by the spring 20, and stable rear throttle is realized. Moreover, since the leaf valve 22 does not have an orifice or notch, concerns about the strength of the leaf valve 22 are eliminated, and the rear throttle port 25 can also be formed by drilling or reaming, so it can be adjusted to the desired diameter and number. It is easily possible to do so.

As described above, the present invention provides a piston with a passage dedicated to the growth side and a rear throttle port parallel to the passage dedicated to the growth side, which is also used for expansion and compression, and a leaf at the lower end of the passage dedicated to the growth side that closes during the compression stroke of the piston. A valve is installed, and the expansion-side dedicated passage and the rear throttle port communicate through an opening at the upper end of the piston, and this opening is equipped with a plate valve that generates damping force during expansion operation and allows free flow during compression operation. The piston is characterized in that a portion of the compression damping force is borne by the piston by throttling the amount of oil during the compression stroke using the rear throttle port.

With this configuration, the present invention has the following effects.

During expansion side operation, oil passes through both the expansion side dedicated passage 15 and the rear throttle port 25, so the passage area is large and the passage area is increased from the upper liquid chamber 5 to the lower liquid chamber 4.
The oil can flow with almost no passage resistance other than the bending resistance of the plate valve 6 and the leaf valve 22.

Since the leaf valve 22 has no notch or orifice, it is advantageous to process the leaf valve 22 itself, which can be done at low cost, and the strength of the leaf valve 22 can be maintained.

Conversely, for the flow from the lower liquid chamber 4 to the upper liquid chamber during pressure side operation, the plate valve 16 is connected to the spring 2.
It is possible to easily open and allow free flow under the large pressure receiving area at the opening at the upper end of the piston without being affected by the Become. The ring seat 24 is added for the purpose of reducing variations in the rebound damping force, and the object of the present invention can be achieved even without it.

Furthermore, in the case of the present invention, it is better to make the area of the through hole 15 as large as possible so as not to affect the rebound damping force.

[Brief explanation of the drawing]

1 and 2 are a partially cutaway vertical side view of a conventional hydraulic shock absorber and an enlarged vertical side view of a piston portion in the hydraulic shock absorber, and FIG. 3 is a hydraulic shock absorber according to an embodiment of the present invention. FIG. 3 is an enlarged longitudinal sectional side view of the piston part. 11a...Piston, 13...Nut, 15...Through hole, 16...Plate valve, 22...Leaf valve, 24
...ring seat, 25...rear aperture port.

Claims (1)

[Scope of Claims] 1. The piston is provided with a passage exclusively for the expansion side and a rear throttle port for common expansion and compression parallel to the passage exclusively for the expansion side, and a leaf valve that is closed during the compression stroke of the piston is provided at the lower end of the passage exclusively for the expansion side. The expansion-side dedicated passage and the rear throttle port communicate through an opening at the top end of the piston, and this opening is equipped with a plate valve that generates damping force during expansion operation and allows free flow during compression operation. A damping force generating device for a hydraulic shock absorber, in which a portion of the compression side damping force is borne by the piston side by throttling the amount of oil during the compression stroke using the rear throttle port. 2. A damping force generating device in a hydraulic shock absorber according to claim 1, which has one rear throttle port. 3. A damping force generating device in a hydraulic shock absorber according to claim 1, which includes a plurality of rear throttle ports having the same diameter. 4. A damping force generation device in a hydraulic shock absorber according to claim 1, 2, or 3, wherein a rear throttle port is bored outside the growth-side exclusive passage.