JPH023058B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a shock absorber for a vehicle.

Conventionally, the spring characteristics of suspension springs and sealed air to absorb the impact force received from the running ground have been improved.
A vehicle shock absorber that can be changed according to driving conditions and driver's preferences has already been proposed by the present applicant in, for example, Japanese Utility Model Application Publication No. 120488/1983.

As shown in Fig. 1, cylinder 1 (inner cylinder 2, outer cylinder 3) on which a piston (not shown) slides has oil chambers B and C and a gas chamber (not shown) inside cylinder 1, and cylinders 2 and 3 have oil chambers B and C and a gas chamber (not shown). In a shock absorber with a shock absorbing spring 4 disposed between them, an adjusting piston 5 that responds to externally controlled hydraulic pressure is
One spring seat of the spring 4 is installed between the cylinders 2 and 3, and the initial load of the spring 4 is changed according to the stroke of the adjusting piston 5, and the gas chamber volume is changed at the same time. be. In other words, by sending pressure oil into the lower chamber 6 of the adjustment piston 5 and pushing it up, the initial load of the spring 4 is increased, and at the same time, the volume of the gas chamber is compressed by an amount equivalent to the amount of pressure oil sent into the lower chamber 6. This improves the air spring characteristics.

By the way, changes in the spring constant based on changes in gas chamber volume affect ride comfort and handling, and the initial load of the spring 4 is heavy to ensure absorbed energy and maintain the vehicle body posture (vehicle height adjustment). Be involved.

However, with this device, the gas chamber volume and the initial load of the spring change simultaneously with the stroke of the adjustment piston 5, so it is not possible to set each of them optimally, and when one is satisfied,
There was a problem that the other value deviated from the optimum value.

The present invention was made to solve these problems, and the initial load of the springs can be adjusted independently, allowing the vehicle height to be freely adjusted without impairing ride comfort or handling. The purpose is to provide a buffer.

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

In Fig. 2, 10 is the shock absorber body, 30 is an adjustment cylinder, 38A, 38B, 39A, 39B.
is a pipe connecting these, and 34A and 34B are solenoid cutoff valves.

The shock absorber main body 10 will be explained with reference to FIG. 3. Reference numeral 11 is an outer cylinder, 12 is an inner cylinder, and 13 is an outer cylinder.
14 is the base valve, 14 is the piston fixed to the piston rod 15, and the piston 14 is the inner cylinder 1.
The interior of 2 is defined into upper and lower oil chambers A and B.

Reference numeral 16 denotes an outer tube that slides into contact with the outer circumference of the outer cylinder 11. Both of them form a gas chamber E and an oil chamber C between the inner cylinder 12 and the piston rod 15, and the oil chambers C and B are connected to the base valve 13 and the piston rod 15. Communication occurs via port 17.

A guide tube 18 is fixed to the lower outer periphery of the inner cylinder 12, and an annular adjustment piston 19 is slidably housed between this guide tube and the outer cylinder 11.

A suspension spring 20 is interposed between the upper end of the outer tube 16 and the adjustment piston 19, between the outer periphery of the inner cylinder 12 and the inner periphery of the outer cylinder 11, and biases the outer tube 18 in the direction of expansion. .

21 connects the inner cylinder 12 to the under bracket 22
A passage 25 is formed in which an oil chamber 23 defined between the end bolt and the under bracket 22 communicates with an oil chamber 24 defined at the lower part of the base valve 13. Moreover, 26 is a reaction oil chamber defined below the adjustment piston 19, and the adjustment piston 19 is raised by feeding pressure oil.

27A and 27B are connectors that connect passages 28A and 27B provided in the under bracket 22, respectively.
It communicates with the oil chambers 26 and 23 via 28B. Note that 29 is a relief port provided in the guide tube 18 to limit the upward movement of the adjustment piston 19, and even if more pressure oil is fed,
By letting oil escape from the relief port 29,
Regulate the stroke.

As the details of the adjustment cylinder 30 are shown in FIG. 4, a piston 32, in which a large diameter piston 32A with a large diameter D and a small diameter piston 32B with a small diameter d are integrally formed, slides on a stepped cylinder housing 31. It can be stored freely, and furthermore, the filter 33, pump P,
Motor M solenoid cutoff valves 34A and 34B are integrally assembled. In addition, 35 is a small diameter piston 32
This is a contact piece provided at the end of the rod 36 projecting outward from B, and comes into contact with a plurality of gas chamber volume adjustment position detection switches 37 fixed to the cylinder housing 31.

As shown in FIG. 2, the oil chambers 26 and 23 of the shock absorber main body 10 are connected to an outgoing side and a return side conduit 38A, which have a pump (trochoid pump) P interposed therebetween for sending oil to the oil chamber 26 side. 38B, a solenoid cutoff valve 34A is installed in the outgoing pipe line 38A, and an oil filter 33 is installed in the return pipe line 38B.

In addition, the large diameter piston 32A of the adjustment cylinder 30
The cylinder chamber 31A of the cylinder chamber 31A is connected to a conduit 39A branching from the middle of the return conduit 38B, while the cylinder chamber 31B of the small diameter piston 32B is connected to the solenoid cutoff valve of the outbound conduit 38A via a solenoid cutoff valve 34B. A conduit 39B connects between 34A and the discharge port of pump P.

The solenoid cutoff valve 34A and the pump P (motor M) are energized by a leveling sensor on the vehicle body (not shown), and the solenoid cutoff valve 34B is energized by a gas volume adjustment position detection switch 37, respectively.

Next, the effect will be explained.

The solenoid cutoff valves 34A and 34B are normally closed, but when the vehicle height becomes low, such as when the payload increases, a leveling sensor (not shown) opens the solenoid cutoff valves 34A, and the motor M rotates to drive the pump P. Then, the oil in the lower end oil chamber C flows through the port 17, the oil chamber 24, the passage 25, and the oil chamber 23.
The oil is sucked into the pump P via the return pipe line 38B, and the discharged oil flows from the outgoing pipe line 38A to the reaction oil chamber 2.
6, the adjusting piston 19 is raised to increase the initial load of the suspension spring 20, and as a result, the vehicle body is lifted via the suspension spring 20, increasing the vehicle height.

In this case, the oil is the upper hydraulic pressure C of the adjusting piston 19.
The total amount of oil remains unchanged, and therefore the liquid level remains unchanged, and the volume of the gas chamber E does not change.

As shown in Fig. 5, this means that while the gas chamber shared load F _A is constant, the initial deflection l of the suspension spring 20 is changed, and only the spring shared load F _S is changed, and the total spring The load is
However, the spring constant does not change. When the vehicle height returns to the standard level, the leveling sensor closes the solenoid cutoff valve 34A and also stops the rotation of the motor M, thereby preventing backflow of hydraulic oil and maintaining this state.

Conversely, when the vehicle height becomes higher than the standard, the output of the leveling sensor opens the solenoid cutoff valve 34A without rotating the motor M. Then, the reaction oil chamber 26
The oil is pressed by the adjustment piston 19, which descends via the suspension spring 20 due to the weight of the vehicle, flows backward from the outgoing pipe 38a, motoring the pump P, and passes through the oil chamber 23 from the return pipe 38b. Since the oil flows into the lower oil chamber C, the vehicle height is lowered in accordance with the downward movement of the adjustment piston 19. When the vehicle height reaches the standard level, the solenoid cutoff valve 34A is closed by the leveling sensor to cut off the flow of hydraulic oil and maintain this state.

The solenoid cutoff valve 34A is controlled based on the output of the leveling sensor to automatically adjust the vehicle height to the standard height. However, the solenoid cutoff valve 34A and the pump P
It is also possible to control the operation of the vehicle and freely change the vehicle height.

By the way, in this embodiment, the spring constant can be increased independently by changing the volume of the gas chamber E. To explain this, the solenoid cutoff valve 3 is activated by a signal from a control means (not shown).
Only 4B is opened and the motor M is rotated. Then, since the shutoff valve 34B is closed, a part of the oil in the cylinder chamber 31A on the large diameter piston 32A side of the adjustment cylinder 30 is sucked into the pump P, and is pushed into the cylinder chamber 31b of the small diameter piston 32B via the solenoid shutoff valve 34B. and moves the piston 32 to the left in the figure. Now, if the amount of movement of the piston 32 is δ, the amount of oil pushed out from the cylinder chamber 31a of the adjustment cylinder 30 by the left movement of the piston 32 is δπD ² /4, and the amount of oil sent into the cylinder chamber 31b is δπd ² /4. be. Therefore, the oil with the difference δπ(D ² - ^{d 2} )/4 enters the lower oil chamber C from the passage 39A and the return passage 38B via the oil chamber 23, thereby raising the liquid level and causing the gas to The volume of chamber E is reduced by δπ(D ² −d ² )/4. As a result, the spring constant of the gas chamber E gradually increases as shown in FIG.

Note that at this time, the initial load of the suspension spring 20 remains almost unchanged since the adjustment piston 19 is not displaced (the load on the spring 20 decreases slightly due to the increase in the spring constant due to the gas chamber E).

The above-mentioned degree of reduction of the gas chamber volume (increase of the spring constant) is performed according to the movement of the piston 32, and therefore the gas chamber volume adjustment is operated (ON, OFF) via the rod 36 integrated with the piston 32. Since it can be detected by the position detection switch 37, it can be set arbitrarily.

Further, in order to expand the gas chamber volume in order to reduce the spring constant, only the solenoid cutoff valve 34B is opened. Then, the oil in the oil chamber C is pushed by the gas pressure and presses the large diameter piston 32A of the adjustment cylinder 30 through the oil chamber 23, the passage 38B, and the passage 39A. At this time, almost the same pressure is applied to the small diameter piston 32B, but due to the difference in the pressure receiving area, the piston 32B
is moved to the right, and the oil on the small diameter piston 32B side of the adjustment cylinder 30 is removed while motoring the pump P. In this case as well, the movement of the piston 32 causes the cylinder chamber 31a to
Oil corresponding to the difference in volume between 31b and 31b flows out from the lower oil chamber C and flows into the cylinder chamber 31a, and as a result,
The volume of the gas chamber E increases and the spring constant decreases.
Since the degree of expansion of the gas chamber volume corresponds to the amount of displacement of the piston 32 as described above, it can be confirmed by the gas chamber volume adjustment position detection switch 37.

As explained above, according to the present invention, the hydraulic oil in the lower oil chamber can be moved to the oil chamber below the adjusting piston to raise the adjusting piston without changing the liquid level. The initial load of the suspension springs can be adjusted independently without changing the interior volume, and as a result, the vehicle height can be freely adjusted without impairing ride comfort or handling.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing the main parts of a conventional device. FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention,
Figure 3 is a longitudinal cross-sectional view of the shock absorber body, Figure 4A is the second
A sectional view of the adjustment cylinder in the figure, Figure 4B is Figure 4A
The A arrow view, FIG. 5, and FIG. 6 are characteristic diagrams when adjusting the initial load of the spring and when adjusting the gas chamber volume, respectively. 10...Buffer body, 11...Outer cylinder, 1
2...Inner cylinder, 17...Port, 19...Adjustment piston, 20...Suspension spring, 23,2
4...Oil chamber, 26...Reaction oil chamber, 34A, 34B
... Solenoid shutoff valve, 38A, 38B ... Pipe line, P ... Pump, M ... Motor, A, B, C ...
...Oil room, E...Gas room.

Claims (1)

[Claims] 1 Forming an oil chamber and a gas chamber inside the relatively expandable outer tube and cylinder,
In a hydraulic shock absorber in which a buffer spring is interposed between an outer tube and a cylinder, a regulating piston that supports one end of the spring is housed in the cylinder, and a reaction oil chamber is defined below the spring. The piping that communicates with the reaction oil chamber below the adjustment piston is equipped with a pump that pressurizes the oil sucked from the oil chamber into the reaction oil chamber when the adjustment piston is driven, and a shutoff valve that opens and closes the piping. Hydraulic shock absorber.