JP3006690B2 - Hydraulic system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic system that is optimally used for an active suspension system as a vehicle suspension system.

[Conventional technology and its problems]

Various hydraulic systems have been proposed for use in an active suspension system as a vehicle suspension system, but generally have a structure as shown in FIG.

That is, this type of hydraulic system basically includes left and right single-acting hydraulic cylinders C disposed between a suspension arm A, which is an axle of the vehicle, and a vehicle body B with a suspension spring S interposed therebetween. In addition, by supplying the hydraulic pressure from the hydraulic pressure source 1 to the oil chamber C1 of each hydraulic cylinder C via the four-port electromagnetic directional control valve 2, the respective control valves 3 and the oil passages L, the hydraulic cylinders C1 are provided. , And the oil pressure from the oil chamber C1 is discharged to the tank 4 through the respective oil passages L, the control valve 3 and the four-port electromagnetic directional switching valve 2 to increase the pressure in the hydraulic cylinder C. It is formed so that the vehicle height can be adjusted by reducing the cylinder pressure.

A pressure sensor S1 and a gas spring G via a throttle V serving as a damping valve are provided in each oil passage L, and a vehicle sensor S2 is provided in the vehicle body B. Become.

On the other hand, the hydraulic system includes a supply path 5a for communicating the hydraulic pressure source 1 with the four-port electromagnetic directional control valve 2, and a supply path 5b for communicating the four-port electromagnetic directional valve 2 with one of the control valves 3 located above in the figure. And the other control valve 3 which is lower than the supply path 5b in the drawing.
And a supply path side communication path 5c that communicates the
Discharge path that connects the tank 4 and the 4-port electromagnetic directional control valve 2
6a, a discharge path 6b that connects the four-port electromagnetic directional control valve 2 to the other control valve 3, and a discharge path side communication path 6c that connects the discharge path 6b to one control valve 3.

In the hydraulic cylinder, a communication path 7 is provided between a supply path 5a and a discharge path 6a, and an electromagnetic proportional relief valve 7a for setting a hydraulic pressure in the supply path 5a is provided in the communication path 7. Do it.

Incidentally, an operation check valve 5d is provided in the supply path 5b, and an operation check valve 6d is provided in the discharge path 6b.
Is provided, and a hydraulic pressure supply path 5b from each control valve 3 side is provided.
And the flow to the 4-port electromagnetic directional control valve 2 via the discharge passage 6b is prevented.

Then, while the operated check valve 5d is opened with the hydraulic pressure of the discharge passage 6b as the pilot oil pressure, the operated check valve 6d is a check valve provided in the communication passage 8 that connects the supply passage 5b and the discharge passage 6b. It is stated that the hydraulic pressure between the throttle 8a and the throttle 8b is used as the pilot hydraulic pressure to enter the open valve state.

An accumulator 5e is provided in a supply path 5b between the operation check valve 5d and the 4-port electromagnetic directional control valve 2, and a supply path between the accumulator 5e and the 4-port electromagnetic directional control valve 2. 5b is provided with a pressure switch 5f for detecting the hydraulic pressure of the supply path 5b.

Further, in a supply path 5b between the pressure switch 5f and the accumulator 5e, a residual pressure valve 5g and a restrictor 5h connected in series with the residual pressure valve 5g are provided, and the residual pressure valve 5g and the restrictor 5h
And a check valve 5i arranged in parallel with the first valve.

Further, a check valve 6e and a throttle 6f arranged in parallel with the check valve 6e are provided in a discharge path 6a between the operation check valve 6d and the other control valve 3, and a discharge path side communication passage is provided. The check valve 6c is provided with a check valve 6g and a throttle 6h arranged in parallel with the check valve 6g.

Further, check valves L2 are provided in each of the bypass passages L1 that connect the oil passages L to the supply passage side communication passage 5c, bypassing the control valves 3, respectively.

In addition, 4 port electromagnetic directional control valve 2, electromagnetic proportional relief valve
7a and each control valve 3 are operated by a command signal from a controller (not shown).

Then, detection signals from the pressure sensors S1, 5f and the vehicle sensor S2 are also input to the controller.

Therefore, in the above-described conventional hydraulic system, basically, each signal from the pressure sensor S1 and the vehicle sensor S2 is input to the controller, and the four-port electromagnetic direction switching is performed by the electric signal from the controller. The valve 2, each control valve 3, and the electromagnetic proportional relief valve 7a are respectively driven. When each control valve 3 is driven, the hydraulic pressure in the oil chamber C1 of each hydraulic cylinder C, that is, the cylinder pressure is adjusted, and the vehicle height is adjusted. Will be adjusted.

As a result, since the hydraulic cylinders C are provided at each of the four wheels of the vehicle, by adjusting the cylinder pressure in each of the hydraulic cylinders C, the posture of the vehicle body becomes active according to the traveling road surface condition of the vehicle, that is, properly. Will be controlled.

However, in the hydraulic system as a conventional example, the check valve 5i, the pressure reducing valve 5g, and the throttle 5h are provided,
Two sets of operating check valves 5d and 6d are provided, and throttles 6h and 6d
f, two sets of check valves 6g and 6e are provided, and check valves L1 and L2
, The number of so-called constituent parts becomes extremely large, which causes inconveniences such as an increase in overall weight and occupation of a large space, and also leads to an increase in cost. There are inconveniences.

The present invention has been made in view of the above circumstances, and has as its object to simplify the circuit configuration, reduce the number of components, increase the overall weight, and increase the large space. It is an object of the present invention to provide a hydraulic system which is optimal for use in an active suspension system as a vehicle suspension system while preventing the occupation of the vehicle and preventing an increase in cost.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the means of the present invention provides a method in which at least two hydraulic cylinders selectively communicate with a supply path of a hydraulic source and a discharge path on a tank side via a control valve. The supply passage is provided with a main check valve that allows supply of hydraulic pressure only from the hydraulic source to the hydraulic cylinder and an accumulator provided downstream of the main check valve, and a discharge passage from the hydraulic cylinder to the tank is provided in the supply passage. An operating check valve for preventing the flow of hydraulic pressure is provided, and a check valve for restricting the flow of oil between the two hydraulic cylinders and a check valve for preventing the flow of oil from one hydraulic cylinder to the other hydraulic cylinder are provided in the discharge path. Are provided in parallel, the hydraulic pressure from the hydraulic pressure source is supplied to the oil chamber of each hydraulic cylinder via a control valve to increase the cylinder pressure in each hydraulic cylinder, In a hydraulic system in which the hydraulic pressure from the chamber is discharged to the tank via a control valve to reduce the cylinder pressure in each hydraulic cylinder, an electromagnetic directional control valve can be switched on the discharge path downstream of the operating check valve. The supply path is connected to a branch path provided with a throttle upstream of the main check valve, and the supply path is located between the supply path downstream of the main check valve and the discharge path downstream of the electromagnetic directional switching valve. Equipped with a first relief valve that permits the flow of hydraulic pressure from
A second communication passage is provided between the supply path downstream of the main check valve and the discharge path upstream of the operation check valve to allow the flow of hydraulic pressure from the discharge path side to the supply path side.
A second communication passage having a relief valve is provided, a pilot oil passage having a throttle is provided between the branch passage and the first relief valve, and the pilot passage is provided between the branch passage and the operation check valve. A pilot oil passage is provided therebetween, and the electromagnetic directional switching valve selectively connects or disconnects the discharge passage and the branch passage to or from the tank.

(Operation)

Each signal from the pressure sensor and the vehicle sensor is input to the controller, and the control valve and the electromagnetic direction switching valve are respectively driven by the electric signal from the controller.When the control valve is driven, the hydraulic pressure in the oil chamber of the hydraulic cylinder, That is, the cylinder pressure is adjusted in height, and the vehicle height can be adjusted.

Also, when the electromagnetic directional control valve cuts off the communication between the supply path and the discharge path, the operation check valve is in an open valve state, and the hydraulic oil from the hydraulic cylinder can be discharged to the tank via the discharge path. At the same time, the first relief valve generates a high cracking pressure, maintains the hydraulic pressure in the supply path at the control hydraulic pressure, and enables the supply of the hydraulic oil from the hydraulic source to the hydraulic cylinder.

Then, when the energization of the electromagnetic directional control valve is stopped and the pilot hydraulic pressure to the operating check valve and the first relief valve is released, for example, during a fail-safe operation, the operating check valve is closed and the hydraulic cylinder is closed. And the first relief valve generates a low cracking pressure, the hydraulic pressure in the supply path is maintained at the tank pressure, and the hydraulic oil from the hydraulic pressure source is supplied to the hydraulic cylinder. The supply is stopped, whereby the cylinder pressure in the hydraulic cylinder, ie the vehicle height, can be maintained.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

In the hydraulic system of the present invention, as shown in FIG. 1, at least two hydraulic cylinders C, C are selectively provided to a supply path 5 of a hydraulic source 1 and a discharge path 6 on a tank 4 side via control valves 3, 3. The supply passage 5 is provided with a main check valve 5n that allows supply of hydraulic pressure only from the hydraulic source 1 to the hydraulic cylinder C, and an accumulator 5o provided downstream of the main check valve 5n. The discharge passage 6 is provided with an operation check valve 6j for preventing the flow of the hydraulic pressure from the hydraulic cylinder C to the tank 4, and the discharge passage 6 is further provided with two hydraulic cylinders C, C
Throttle 9c and one hydraulic cylinder C allowing oil flow between
The check valves 6m and 9a for preventing the flow of oil from the hydraulic cylinder C to the other hydraulic cylinder C are provided in parallel.

In the present invention, the hydraulic pressure from the hydraulic pressure source 1 is supplied to the oil chambers C1 of the hydraulic cylinders C, C via the control valves 3, 3, so as to increase the cylinder pressure in the hydraulic cylinders C, C, The hydraulic pressure from C1 is discharged to the tank 4 via the control valve 3 to reduce the cylinder pressure in each hydraulic cylinder C.

Further, in the present invention, a three-port electromagnetic directional switching valve 6k is provided in the discharge path 6 so as to be switchable downstream of the operation check valve 6j, and a throttle 51 is provided in the supply path 5 upstream of the main check valve 5n. The branching path 5k is connected. A first relief valve 7b provided between the supply path 5 downstream of the main check valve 5n and the discharge path 6 downstream of the electromagnetic directional switching valve 6k and having a first relief valve 7b for allowing the flow of hydraulic pressure from the supply path side to the discharge path side. One communication passage 7 is provided, and the supply passage 5 also downstream of the main check valve 5n and the discharge passage 6 upstream of the operation check valve 6j.
A second communication passage 8 provided with a second relief valve 8a for allowing the flow of the hydraulic pressure from the discharge path side to the supply path side is provided between the second communication path 8 and the supply path.

A throttle 7d is provided between the branch 5k and the first relief valve 7b.
Is provided, and a pilot oil passage 61 is provided between the branch passage 5k and the operation check valve 6j. The electromagnetic directional control valve 6k is connected to the discharge path 6 and the branch path 5k.
Is selectively communicated with or shut off from the tank 4. The details will be described below.

As shown in FIG. 1, an active suspension system, which is a hydraulic system according to an embodiment of the present invention, has a partly different configuration, but is generally configured substantially the same as the hydraulic system according to the conventional example described above. ing.

That is, in this embodiment, a suspension spring (not shown) is provided between a suspension arm (not shown), which is an axle, and a vehicle body (not shown) in each of the four wheels of the vehicle (not shown).
A plurality of single-acting hydraulic cylinders C disposed under the control valve 3 and a control valve 3 is connected to each oil passage L communicating with each oil chamber C1 of each hydraulic cylinder C. On the other hand, it is assumed that a pressure sensor S1 for detecting the oil pressure in each oil passage L and a gas spring G via a throttle V serving as a damping valve are provided in each oil passage L. In addition, a vehicle sensor (not shown) is provided on the vehicle body.

And each oil chamber in each hydraulic cylinder C
By supplying the hydraulic pressure from the hydraulic pressure source 1 to C1 through the respective control valves 3 and the oil passages L, the cylinder pressure in the respective hydraulic cylinders C is increased, and the hydraulic pressure from the respective oil chambers C1 is increased. Tank 4 via oil passage L and control valve 3
To reduce the cylinder pressure in the hydraulic cylinder C, thereby adjusting the vehicle height.

Incidentally, each of the pressure sensors S1 detects a cylinder pressure in each of the hydraulic cylinders C, and each of the vehicle sensors detects a state of the vehicle. Detection signals from the pressure sensors S1 and the vehicle sensors are output from a controller (not shown). And the control valve 3 is operated by a command signal from the controller, that is, an electric signal.

On the other hand, the active suspension system according to this embodiment includes a supply path 5 that communicates the hydraulic pressure source 1 with the front left control valve 3 at the top in the figure, a tank 4 and a front right right as the second stage in the figure. A discharge passage 6 communicating the control valve 3 of
And a supply passage 5j communicating with the supply passage 5 and communicating with the third control valve 3 on the rear side, which is a third stage in the drawing, and a discharge passage 6 communicating with the discharge passage 6. And a discharge path 6i which is communicated with the rightmost control valve 3 on the rear side at the bottom of the figure.

The discharge path 6 is provided with an operation check valve 6j on its upstream side and a 3-port electromagnetic directional switching valve 6k on its downstream side.

The downstream end of the discharge path 6 is provided with a filter 4a and is located in the tank 4.

The 3-port electromagnetic directional control valve 6k is connected to the supply path 5 by a branch path.
5k, the branch passage 5k is communicated with the discharge passage 6 when the magnet is demagnetized, so-called inactive, so that the hydraulic pressure source 1
It is possible to discharge a high oil pressure to the tank 4.

The three-port electromagnetic directional control valve 6k communicates with the discharge path 6 on the upstream side of the three-port electromagnetic directional switch valve 6k and the discharge path 6 on the downstream side of the three-port electromagnetic directional valve 6k at the time of excitation. Of course.

 It should be noted that a throttle 51 is arranged in the branch path 5k.

Next, the active suspension system according to this embodiment has a communication path 7 for communicating between the supply path 5 and the discharge path 6, and a relief valve 7b is provided in the communication path 7.
Having.

The relief valve 7b is formed such that a predetermined pilot oil pressure is applied via a pilot oil passage 7c communicating with the branch passage 5k.

The pilot oil passage 7c has a throttle 7d, and is communicated between the throttle 51 in the branch passage 5k and the three-port electromagnetic directional switching valve 6k.

The relief valve 7b is formed such that a high cracking pressure is generated in the relief valve 7b when a predetermined pilot oil pressure is applied to the relief valve 7b.

The relief valve 7b is formed such that a low cracking pressure is generated in the relief valve 7b when the predetermined pilot oil pressure is released.

Incidentally, the relief valve 7b is specifically configured as shown in FIG.

That is, the relief valve 7b shown in FIG. 2 has a poppet-shaped valve element 22 slidably provided in an open chamber 21 in the valve body 20 and communicates with the chamber 21. The valve body 22 is inserted into a chamber 23 opened in the valve body 20 as described above.
And a free piston 24 disposed slidably behind the free piston 24.

Then, the poppet-shaped valve element 22 and the free piston 24
A biasing spring 25 is disposed between the valve body 22 and the valve body 22. The biasing force of the biasing spring 25 biases the valve body 22 in a so-called forward direction.

On the other hand, behind the free piston 24, a sealing member fitted to an open end, which is the right end in the figure, of the valve body 20 is provided.
26 is formed by partitioning an oil chamber 27, and the oil chamber 27 is a sealing member.
The orifice 26 communicates with the communication passage 5k via the throttle 7d formed of an orifice and a pilot oil passage 7c.

A closed end, which is the left end of the valve body 20 in the figure, is opened so as to face the tip of the poppet-shaped valve body 22 and communicates with the supply passage 5 through the communication passage 7. And a port 29 for communicating around the distal end portion of the valve element 22 through the communication path 7 but to the discharge path 6 when the valve element 22 retreats to form a gap. Do it.

Therefore, the relief valve 7b according to this embodiment closes the port 28 when the poppet-shaped valve element 22 is in the most advanced state shown in the drawing, and the supply path 5 is communicated with the discharge path 6. When the valve body 22 is retracted, that is, when the urging force of the urging spring 25 is overcome and the free piston 24
When the pilot hydraulic pressure behind is released and the vehicle is retreating, the supply path 5 can be communicated with the discharge path 6, that is, the tank 4.

The operating check valve 6j uses the oil pressure in the branch passage 5k as its pilot oil pressure.

That is, the operation check valve 6j has a pilot oil passage 61 communicating with the branch passage 5k, and the pilot oil passage 61 is similar to the pilot oil passage 7c communicating with the relief valve 7b. It is assumed that the branch passage 5k communicates with a branch passage 5k between the throttle 5l and the three-port electromagnetic directional switching valve 6k.

Therefore, as in the case of the relief valve 7b, the operating check valve 6j generates a hydraulic pressure in the branch passage 5k by excitation of the three-port electromagnetic directional switching valve 6k and generates a predetermined pilot hydraulic pressure in the pilot oil passage 61. When this is done, it becomes a so-called opening valve, which allows the hydraulic pressure on the control valve 3 side to be discharged to the tank 4.

Then, the operation of the operation check valve 6j is released from the excitation to the three-port electromagnetic directional switching valve 6k and the pilot oil passage 6l
When the pilot hydraulic pressure is released, a so-called check valve is provided to prevent the hydraulic pressure on the control valve 3 side from being discharged to the tank 4.

In addition, the active suspension system, which is a hydraulic system according to this embodiment, includes a pressure sensor 5m in a supply path 5 communicating with the branch path 5k, and includes a pressure sensor 5m on the downstream side of the pressure sensor 5m. And a check valve 5n for preventing backflow of the pressure oil from the control valve 3 side.

And the active suspension system,
A relief valve 8a is provided in a communication path 8 that connects the supply path 5 and the discharge path 6 near the control valve 3.

The relief valve 8a is formed to allow the pressure oil from the discharge path 6i communicating with the discharge path 6 to flow into the supply path 5 under a predetermined relief pressure.

The active suspension system has an accumulator 5o in the supply paths 5 and 5j close to the control valve 3, and has a check valve 5p between the accumulator 5o and the control valve 3.

In addition, the active suspension system
A check valve 6m for preventing backflow in the discharge passage 6 is provided in the discharge passage 6, and a discharge side passage 9 communicating the discharge passage 6 with the control valve 3, which is the uppermost stage in the drawing, is provided in the discharge passage 6. A check valve 9a for preventing backflow is provided, and a throttle 9c is provided in a bypass 9b parallel to the discharge side passage 9.

Further, the active suspension system has a throttle 6n in a discharge path 6j connected to the discharge path 6, and is connected to the control valve 3 which is connected to the discharge path 6j and is a third stage in the drawing. And a check valve 10b and 10c arranged in parallel with the throttles 6n and 10a, respectively.

Therefore, in this embodiment, a 3-port electromagnetic directional switching valve 6k is used instead of the 4-port electromagnetic directional switching valve 2 (see FIG. 3), and an electromagnetic proportional relief valve 7a Instead of (see FIG. 3), a relief valve 7b is provided, and further, the arrangement of the operation check valve 5d (see FIG. 3) on the supply path 5b (see FIG. 3) side is omitted. Significant reduction of parts becomes possible.

Then, in the active suspension system according to this embodiment formed as described above, each signal from the pressure sensor S1 and the vehicle sensor S2 is input to a controller (not shown), and an electric signal from the controller is used. Each of the control valves 3 and the three-port electromagnetic directional switching valve 6k are driven, and when each of the control valves 3 is driven,
The cylinder pressure in the hydraulic cylinder C disposed in each part of the four wheels of the vehicle is adjusted, so that the height of the vehicle can be adjusted.

When a large road surface vibration is input to the traveling vehicle and a large oil pressure is supplied to and discharged from the oil chamber C1 of the hydraulic cylinder C, the oil pressure is applied to the gas spring G via the throttle V.
In this case, the shock absorber function can be exhibited by a predetermined damping action, and a predetermined gas spring effect can be obtained.

Further, when each control valve 3 is to be operated, that is, when the active suspension system is operated, the supply path 5,
That is, the relief valve 7b controls the control oil pressure by raising the oil pressure in the branch passage 5k. That is, the oil pressure from the oil pressure source 1 is supplied to each hydraulic cylinder via each control valve 3, and the operation check is performed. The valve 6j becomes in a communicating state, and the discharge of the pressure oil from each control valve 3, that is, the pressure oil from each hydraulic cylinder C to the tank 4 is permitted.

When the operation of each of the control valves 3 and the 3-port electromagnetic directional control valve 6k is stopped at the time of fail-safe, etc., the hydraulic pressure in the supply path 5a is released by the 3-port electromagnetic directional switch valve 6k, and the relief valve 7b While the oil pressure in the supply passage 5 is discharged to the tank 4, the operating check valve 6j is in a check valve state, and the discharge of the pressure oil from each hydraulic cylinder to the tank 4 is prevented, so-called of the active suspension system. It is possible to maintain the cylinder pressure in each hydraulic cylinder C during the suspension of operation, that is, the vehicle height.

〔The invention's effect〕

As described above, according to the hydraulic system of the present invention, the circuit configuration is simplified, and the number of so-called components can be reduced. Therefore, an increase in the overall weight and occupation of a large space can be prevented in advance. This has the advantage of being able to prevent such an increase and to avoid incurring high costs, making it optimal for use in an active suspension system as a vehicle suspension system.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an active suspension system as a hydraulic system according to an embodiment of the present invention, FIG. 2 is a sectional view showing an embodiment of a relief valve, and FIG. 3 is a hydraulic system as a conventional example. FIG. 2 is a circuit configuration diagram showing an active suspension system. [Explanation of Symbols] C: Hydraulic cylinder, C1: Oil chamber L: Oil path 1, Hydraulic source 3: Control valve 4, Tank 5: Supply path, 5k: Branch path 6 …… Discharge path 6j …… Operate check valve 6k …… 3-port electromagnetic directional control valve 6l, 7c …… Pilot oil path 7 …… Communication path, 7b …… Relief valve

Claims (1)

(57) [Claims] At least two hydraulic cylinders are selectively connected or disconnected to a supply path of a hydraulic source and a discharge path on a tank side through a control valve, and supply of hydraulic pressure to the supply path only from the hydraulic source to the hydraulic cylinder. A main check valve that permits the flow of air from the hydraulic cylinder to the tank, and an accumulator provided downstream of the main check valve. A throttle that allows the flow of oil between two hydraulic cylinders and a check valve that prevents the flow of oil from one hydraulic cylinder to the other hydraulic cylinder are provided in parallel, and the hydraulic pressure from the hydraulic power source is Each hydraulic cylinder is supplied to an oil chamber of a hydraulic cylinder to increase the cylinder pressure in each hydraulic cylinder, and the hydraulic pressure from each oil chamber is discharged to a tank via a control valve. In a hydraulic system in which the cylinder pressure is reduced, an electromagnetic direction switching valve is provided in the discharge path so as to be switchable downstream of the operation check valve, and a throttle is provided in the supply path upstream of the main check valve. A first relief valve connected to the branch passage, between the supply passage downstream of the main check valve and the discharge passage downstream of the electromagnetic directional switching valve, allowing a hydraulic flow from the supply passage side to the discharge passage side; A second relief valve is provided between the supply path downstream of the main check valve and the discharge path upstream of the operation check valve to allow a hydraulic flow from the discharge path to the supply path. A second communication passage provided, a pilot oil passage provided with a throttle between the branch passage and the first relief valve, and a pilot oil passage provided between the branch passage and the operating check valve. Hydraulic system the road is provided, the electromagnetic directional control valve is characterized in that so as to communicate or cut off selectively tank discharge passage and branch passage.