JP2514195B2 - Shock absorber with vehicle height adjuster - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a shock absorber with a vehicle height adjusting device, which is used in, for example, a motorcycle, and particularly to a period in which an extra load is applied to a piston rod due to a pumping action. The present invention relates to a pressure accumulation control structure capable of suppressing the deterioration of the buffer function by shortening the pressure. The present invention can be applied to both hydraulic and pneumatic shock absorbers, but the hydraulic shock absorber will be described below as an example.

[Conventional technology]

A hydraulic shock absorber with a vehicle height adjusting device used in motorcycles or the like secures a predetermined vehicle height during normal traveling, and adjusts the vehicle height to a low value so that these operations can be easily performed when getting on and off the vehicle. A device that allows the vehicle height to be changed according to the purpose. As such a shock absorber with a vehicle height adjusting device, conventionally, for example, a pump chamber is formed in a piston rod, and a pumping mechanism formed by inserting a plunger attached to a cylinder into the pump chamber is built in a shock absorbing device, There was a system in which the high-pressure hydraulic oil generated by this pumping mechanism was accumulated in the pressure accumulating chamber, and when the accumulated pressure exceeded a predetermined pressure, the relief valve allowed the hydraulic oil to escape to the low-pressure chamber (for example, Japanese Patent Publication No. 50-28588). See the bulletin).

[Problems to be solved by the invention]

In the above conventional device, the pumping mechanism always performs a pumping operation as the shock absorber expands and contracts. In this case, the load acting on the piston rod corresponds to the product of the hydraulic pressure generated and the cross-sectional area of the plunger in the compression stroke of this pumping operation, and this load disappears in the extension stroke. Further, since it resists this hydraulic pressure, the seal resistance also increases. Therefore, a large fluctuating load acts on the piston rod as compared with a shock absorber without a pumping mechanism, and the original shock absorbing function is impaired. Even in the case where the relief valve described above is provided, the pumping operation is always performed, and therefore it does not contribute to the elimination of such a problem.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, and shortens the period during which load fluctuations on the piston rod due to pumping operation occur, and thus the period during which the cushioning function is impaired, as much as possible, and as a whole ride An object of the present invention is to provide a shock absorber with a vehicle height adjusting device that can improve the feeling.

[Means for solving problems]

The present invention incorporates a pumping mechanism including a pump chamber formed in a piston rod and a plunger attached to a cylinder, accumulates a high-pressure working fluid in the pressure accumulator chamber, and adjusts the vehicle height by the accumulated pressure. In the shock absorber with vehicle height adjusting device, a first hydraulic passage communicating the pump chamber and the lift chamber, a second hydraulic passage communicating the lift chamber and the working chamber, and the working chamber and the pump chamber. A third hydraulic passage communicating with the first hydraulic passage, and a pressure accumulating chamber is connected to the first hydraulic passage via a one-way valve that blocks flow from the accumulating chamber to the pump chamber. It is characterized in that a pressure accumulation control valve is provided so as to allow only the flow from the working chamber to the pump chamber when the value is below a predetermined value, and to allow the flow in both directions when the value is above the predetermined value.

[Action]

According to the shock absorber with the vehicle height adjusting device of the present invention, when the pressure in the pressure accumulating chamber is equal to or lower than the predetermined value, that is, mainly at the traveling start time, the shock absorber operates in the extension stroke of the shock absorber as in the conventional shock absorber. The fluid is sucked from the working chamber through the pressure accumulation control valve into the pump chamber, pressurized in the contraction stroke, and accumulated in the pressure accumulation chamber. On the other hand, when the pressure in the accumulator reaches or exceeds the predetermined value,
The pressure accumulation control valve circulates in both directions between the working chamber and the pump chamber, whereby the working fluid sucked into the pump chamber in the expansion stroke is returned to the working chamber as it is in the contraction stroke, that is, the pumping operation is canceled. Therefore, in the present invention, after the accumulated pressure becomes equal to or higher than the predetermined value, the load on the piston rod does not fluctuate at all, the period during which the cushioning function is impaired is greatly shortened, and the riding feeling as a whole is greatly improved.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 are views for explaining one embodiment of the present invention. First, in FIG. 5 showing the schematic configuration of the device of the present embodiment, 2 is a shock absorber, and the lift chamber 13, the pump chamber 11, and the working chamber 3 of the shock absorber are respectively provided in the main passage 25 and the first passage branched from the main passage 25. The second hydraulic passages 14 and 15 communicate with each other, and a pressure accumulating chamber 17 is connected to the first hydraulic passage 14. Further, the working chamber 3 and the pump chamber 11 are communicated with each other through a third hydraulic passage 16. A hydraulic control device 18 is arranged at a branch portion between the main passage 25 and the first and second hydraulic passages 14 and 15.

An unload valve 23 for canceling the pumping action when the accumulated pressure exceeds a specified value is provided in the third hydraulic passage 16, and the structure of the unload valve 23 is described in the present embodiment as described later. Is characterized by.

In addition, 10 is a sub tank for supplying hydraulic oil, 21a,
21b are check valves for accumulating pressure and vehicle height, 22a and 22b, respectively.
Is a throttle valve for adjusting the vehicle height ascending / descending speed, and 24 is a safety relief valve when the unload valve 23 fails.

2 to 4 showing the structure embodying the shock absorber 2, the cylinder 1 of the shock absorber has a body member 1a fixed to the upper end of a cylindrical member and a lower end closed by an end plate 1b. It becomes. A lift case 6 constituting the lift chamber 13 is slidably mounted on the cylinder 1, and the lift case 6 is formed with a first spring receiver 6a for preventing a buffer spring described later. A piston rod 5 having a piston 9 at its upper end is slidably inserted into the cylinder 1, and a vehicle body support 4 is provided at the lower end of the piston rod 5.
A second spring receiver 7 is fixedly formed above this. A buffer spring 8 is provided between the second spring receiver 7 and the first spring receiver 6a. This buffer spring 8 is the main spring 8a
And two auxiliary springs 8b.
A movable spring bearing 19 is provided between 8a and 8b, and the movable spring bearing 19 is slidably mounted on the cylinder 1.

The unload valve 23 is formed on the vehicle body supporting portion 1a. As shown in the conceptual diagram of FIG. 1, the unload valve 23 is composed of a tilt type control valve 26 and a valve body drive unit 27 for tilting the valve. The tilt type control valve 26 forms a valve chamber 16b having an opening / closing hole 16a in the middle of the third hydraulic passage 16 that connects the working chamber 3 and the pump chamber 11, and the tilt type valve body 28 is formed in the valve chamber 16b. Are arranged.
The valve shaft 28a of the valve body 28 projects from the opening / closing hole 16a toward the working chamber 3, and the valve plate 28b is pressed against the opening / closing hole edge portion 16c by a biasing spring 28c. Note that 29a and 29b are stopper members.

Further, the valve body drive unit 27 is a drive chamber 30 communicating with the pressure accumulating chamber 17.
The drive pin 31 is arranged so as to be movable in the axial direction. The drive pin 31 penetrates the bottom of the drive chamber 30 and can press the valve shaft 28a of the valve body 28, and the drive pin 31 is biased by a spring 32 toward the pressure accumulating chamber, that is, the valve shaft. It is urged away from 28a. This biasing spring 32 is a pressure accumulating chamber.
When the pressure inside 17 exceeds the specified pressure Drive pin 31
It is set to the biasing force that tilts 28a.

 Next, the function and effect of this embodiment will be described.

In the device of the present embodiment, when the pressure in the pressure accumulating chamber 17 is low as at the start of traveling, the drive pin 31 of the unload valve 23 is pushed by the urging spring 32 and is positioned at its retracted end, and the valve element 28 is Standing up. Therefore, the third hydraulic passage 16 is in a state in which only the check valve function of the valve body 28 allows the flow from the working chamber 3 to the pump chamber 11 direction. Therefore, when the pump chamber 11 reaches the bottom pressure from the working chamber 3 in the extension stroke as the shock absorber 2 expands and contracts, hydraulic oil pushes the valve body 28 of the unload valve 23 open and is sucked into the pump chamber 11. . Then, this hydraulic oil is pressurized in the contraction stroke and is sent under pressure through the pressure accumulation check valve 21a into the pressure accumulation chamber 17.

Then, when the pressure in the pressure accumulating chamber 17 rises above a specified value by the hydraulic oil sent under pressure, the drive pin 31 moves forward by this pressure, and the tip of the drive pin 31 pushes and tilts the valve body 28 of the unload valve 23. Then, as a result, the third hydraulic passage 16 becomes
From the working chamber 3 to the pump chamber 11 as well as in the opposite direction. Therefore, after that, the working oil sucked from the working chamber 3 into the pump chamber 11 in the extension stroke is pressurized in the contraction stroke. Without returning to the working chamber 3, the pumping operation is canceled.

Next, when the driver switches the vehicle height changeover switch to the rising side, the pressure control device 18 causes the pressure accumulation chamber 17 and the lift chamber 13 to be released.
And are communicated. As a result, the auxiliary spring 8b is compressed and the lift case 6 and the movable spring receiver 19 come into contact with each other, and the buffer spring 8
The set load and the spring constant increase, the amount of sinking decreases, and the vehicle height rises. Then, when the pressure in the pressure accumulating chamber 17 is reduced, the drive pin 31 is retracted, the valve body 28 is in an upright state, the pumping operation is restored, and hydraulic oil is pumped to the pressure accumulating chamber 17,
When the pressure reaches the specified pressure, the pumping operation is canceled again.

As described above, in the apparatus of this embodiment, after the pressure inside the pressure accumulating chamber 17 reaches the specified pressure, the unload valve 23 keeps the working chamber 3 and the pump chamber 11 in a conductive state in both directions. Pump operation can be canceled when sufficient hydraulic oil is accumulated in 17. In other words, during normal running after the hydraulic oil is stored, it operates in the same way as a shock absorber without a vehicle height adjustment device. It takes only a short time, and the overall riding feeling can be improved.

Further, in the unload valve 23, since the tilt type structure is adopted as the structure for conducting in both directions, the driving force of the tilt type structure is small, and the operation can be surely performed.

Although the tilt valve structure is adopted as the unload valve 23 in the above embodiment, various modifications of the structure of the unload valve 23 are conceivable, and the unload valve structure is not limited to the tilt valve structure. . In the present invention, the point is that the working chamber and the pump chamber may be connected in both directions when the accumulated pressure is equal to or higher than a specified value.

〔The invention's effect〕

As described above, according to the shock absorber with the vehicle height adjusting device of the present invention, the working chamber and the pump chamber, when the pressure of the pressure accumulating chamber is equal to or less than the specified value, only the direction from the working chamber to the pump chamber, the specified value or more. In this case, the pumping operation can be canceled after the necessary working fluid is stored in the pressure accumulating chamber, and a high cushioning function can be secured by eliminating unnecessary pumping operation to improve the riding comfort. There is an effect that can be done.

[Brief description of drawings]

1 to 5 are views for explaining a shock absorber with a vehicle height adjusting device according to an embodiment of the present invention. FIG. 1 is a conceptual diagram of an unload valve, and FIG. 2 is a diagram of an unload valve portion. FIG. 3 is a cross-sectional plan view, FIG. 3 is a cross-sectional side view thereof, FIG. 4 is a cross-sectional side view of a shock absorber in which the unload valve is adopted, and FIG. 5 is a system diagram showing the overall structure of the shock absorber. In the figure, 1 is a cylinder, 2 is a shock absorber, 3 is a working chamber,
5 is a piston rod, 11 is a pump chamber, 12 is a plunger,
16 is a third hydraulic passage (passage), 16a is an opening / closing hole, 16b is a valve chamber,
16c is an opening / closing hole edge portion, 17 is a pressure accumulating chamber, 23 is an unload valve (accumulation control valve), 26 is a tilt type control valve, 27 is a valve body drive part, 28
Is a valve body, 28a is a valve shaft, 28b is a valve plate, 30 is a drive chamber, and 31 is a drive pin (drive member).

Claims (2)

(57) [Claims] 1. A pumping mechanism formed by inserting a plunger provided in a working chamber of a cylinder into a pump chamber formed in a piston rod, and the working fluid pressurized by the pumping mechanism is stored in a pressure accumulating chamber. In the shock absorber with the vehicle height adjusting device, the vehicle height is adjusted by introducing the pressure of the working fluid in the pressure accumulating chamber to the lift chamber or by releasing the pressure in the lift chamber. A first hydraulic passage that communicates with the lift chamber, a second hydraulic passage that communicates between the lift chamber and the working chamber, and a third hydraulic passage that communicates between the working chamber and the pump chamber are provided. Is connected to the pump chamber via a one-way valve that blocks flow from the pressure chamber to the pump chamber, and only flows from the working chamber to the pump chamber when the pressure chamber is below a predetermined pressure in the third hydraulic passage. To Volume and, when the predetermined pressure or more working chambers, the level control system equipped with a buffer device being characterized in that interposed the accumulator control valve that allows flow in both directions between the pump chamber. 2. A tilt-type control valve, wherein the pressure accumulation control valve opens and closes a passage by tilting a valve shaft in a direction perpendicular to the axis,
The tilt type control valve forms a valve chamber having an opening / closing hole in the third passage, and the valve body has a valve shaft in the valve chamber. The valve plate is configured to protrude through the opening / closing hole to the working chamber side, and the valve plate is urged so as to come into contact with the edge of the opening / closing hole, and the valve body drive unit is communicated with the pressure accumulating chamber. A drive chamber is formed, and a drive member is disposed in the drive chamber such that the tip of the drive member passes through the bottom of the drive chamber and faces the valve shaft in the valve chamber and is movable in the axial direction. The shock absorber with a vehicle height adjusting device according to claim 1, characterized in that the member is urged in a direction against pressure accumulation.