JPH0780413B2 - Air spring suspension device with sub tank - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air spring type suspension device with a sub tank.

2. Description of the Related Art A conventional suspension device of this type is described in, for example, Japanese Utility Model Publication No. 60-51110.

According to this suspension device, in addition to the chamber of the suspension device, a sub-tank is provided, and the two are in a communication state, the spring constant of the suspension is lowered, a so-called soft state is obtained, and the communication between the two is cut off. The spring constant of the suspension is increased to obtain a so-called hard state.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described conventional suspension device, the switching from the soft state to the hard state and from the hard state to the soft state are performed by simply opening and closing the solenoid valve. There is a difference between the chamber internal pressure and the sub-tank internal pressure, and when switching from the hard state to the soft state, an occupant may experience an unpleasant thrusting or dropping shock.

This occurs when the compressed air in the sub-tank suddenly and in large quantities flows into the suspension chamber or flows out of the suspension chamber into the sub-tank. For example, at the time of starting or during sudden braking, the soft state is switched to the hard state in order to prevent the cut and nose dive, but at that time, it becomes the hard state with relatively high air pressure generated in the sub tank or the chamber, and this is the vehicle. Occurs when the hard control is released when the vehicle has moved to a stable running state after finishing the sudden acceleration and braking.

Means for Solving the Problems In order to solve the above problems, the present invention provides a suspension tank, which receives a high-pressure fluid supplied from a pressure source, with a sub-tank via a communication passage and a cut valve in the communication passage. The cut valve is opened to connect the chamber and the sub-tank to reduce the spring constant of the suspension, and the cut valve is closed to disconnect the chamber and the sub-tank from each other to increase the spring constant of the suspension. In an air spring suspension device with a sub tank, the controller for instructing the opening and closing of the cut valve is configured to be on / off control in which the cut valve drive current is continuously turned on / off for a required time, and the duty of this on / off control is changed with time. It is configured to change and control.

Action When the cut valve opens, its opening ratio changes with the passage of time, and the compressed air in the sub-tank gradually flows into the suspension chamber while changing the flow rate.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, a sub-tank 4 is connected to a chamber 2 of a suspension 1 which receives high-pressure gas from a compressor 6 as a pressure source via a supply / discharge passage 3a via a communication passage 3.
And a cut valve 5 is provided in the communication passage 3, and the cut valve 5 is opened to make the chamber 2 and the sub-tank 4 communicate with each other to lower the spring constant of the suspension 1 so that the cut valve 5 is softened. By closing the chamber 2 and the sub-tank 4 in a non-communication state, the spring constant of the suspension 1 is increased to make it hard. As shown in FIG. 2, the cut valve 5 includes a fixed core 5a and a coil 5b wound around the coil 5b, and is provided with a collenoid 5c. When the solenoid 5c is excited by energizing the coil 5b, the movable core 5d is fixed. The valve body 5e, which is sucked by the 5a and moves, is integrally provided with the movable iron core 5d via the rod, contacts the valve seat 5g, closes the valve, and closes the sub-tank side passage 3a and the chamber side passage 3b to connect them. When the passage 3 is closed and the coil 5b is de-energized, the valve body 5e and the movable iron core 5d are pushed up by the set spring 5f so that the valve body 5e is separated from the valve seat 5g and the communication passage 3 is opened. Referring back to FIG. 1, 8 is a suspension valve provided for each supply / discharge passage 3a of each suspension 1, 10 is an exhaust valve, and 12 is a dryer. By driving the compressor 6, compressed air is dried. The compressed air in the suspension chamber 2 is supplied to each suspension valve 18 through 12 and is exhausted by the exhaust valve 10 via the suspension valve 8 and the dryer 12.

Reference numeral 15 denotes a controller for instructing opening and closing of the cut valve 5, which receives detection signals from a steering angle sensor, a brake sensor, a vehicle speed sensor, an accelerator sensor, etc., which are not shown, and the controller 6 of the compressor 6 is based on these detection signals. While driving the drive motor, each suspension valve 8
Also, each solenoid of the exhaust non-valve 10 is driven and a drive current is supplied to the solenoid 5c of the cut valve 5. As shown in the waveform diagram of FIG. 3, the controller 15 operates when the cut valve 5 is opened.
The drive current is continuously turned on and off for a required time, and the duty of the on / off control is controlled. Specifically, the width of the control pulse for the on / off control is changed with time to change the ratio of the average time t of the on state to one cycle T of the on / off (t / T × 100 (%)), that is, the duty. I'm running. This change in duty may be controlled to be 50%, 40%, 30%, 20% continuously over time, or 50%, 40%, 30%, 20% may be continued for a certain period of time. However, it is set to change sequentially.

In addition, a signal from a vehicle height sensor is also input to the controller 15, and instead of the vehicle height that fluctuates due to vibration, a steady change in vehicle height from the reference vehicle height is detected, and the vehicle height is below a set value. Sometimes the controller 15 causes the suspension valve 8
Open, the exhaust valve 10 is closed, the compressor 6 is operated, and the compressed air from the compressor 6 is suspended 1
The vehicle height is increased by supplying the compressed air from the suspension chamber 8 of the suspension 1 to the atmosphere by opening the suspension valve 8 and the exhaust valve 10 when the vehicle height is higher than the set value. It is designed to lower the vehicle height.

According to the structure of the above embodiment, when switching from hard to soft, the drive current from the controller 15 to the solenoid 5c of the cut valve 5 is repeatedly turned on and off while changing the duty with time as shown in FIG. Supplied. As a result, the closing time during which the valve body 5e of the cut valve 5 is seated on the valve seat 5g,
The ratio of the opening time of 5e away from the valve seat 5g, that is, the valve opening time changes with the passage of time, and the cut valve 5
The opening time will gradually increase. Therefore, the air having a high pressure in the sub tank 4 gradually flows into the chamber 2 through the cut valve 5 little by little. This will be apparent from the comparison between the waveform diagram of the drive current of the solenoid shown in FIG. 3 and the operation waveform of the valve opening ratio of the cut valve 5.
Further, since the duty of the on / off control is changed with time (the duty is controlled), the responsiveness of the opening operation of the cut valve 5 becomes faster than in the case where the duty of the on / off control is set unchanged at a certain required value. .

FIG. 4 shows a different example of the present invention. As shown in the waveform diagram of the drive current of the solenoid 5c in the cut valve 5, the duty of the on / off control is zero or broken as shown in one cycle of the initial opening of the cut valve. It is set to a small value as described above, and after 2 cycles, it is set to a constant value which is larger than that in the initial 1 cycle and remains unchanged. Therefore, after the cut valve 5 reduces the pressure under the sub tank 4 and the air chamber 2 in one initial cycle,
The opening / closing operation allows high pressure air to gradually flow into the chamber 2 little by little to reduce the initial pressure difference, thereby shortening the duty control time. In the above, the first
The duty is changed only for the cycle, but the second, third, etc. may be changed if necessary.

In each of the above-described embodiments, the case where the compressor 6 is driven by the motor M has been described as an example. However, although not shown, the compressor 6 can be driven by an automobile engine. The compressor 6 in this case is connected to the engine through a clutch.

As described above, according to the present invention, the sub-tank 4 is attached to the chamber 2 of the suspension 1 through the communication passage 3, the cut valve 5 is provided in the communication passage 3, and the cut valve 5 is opened to open the chamber. 2 and the sub-tank 4 are in communication with each other to reduce the spring constant of the suspension 1, and the cut valve 5 is closed to disconnect the chamber 2 and the sub-tank 4 from each other to increase the spring constant of the suspension 1. In an attached air spring type suspension device, a controller 15 for instructing opening and closing of the cut valve 5 and an on / off control in which a cut valve drive current is continuously turned on and off for a required time are configured, and a duty of the on / off control is changed with time. It is configured so that it can be controlled, so it is recommended when switching from hardware to software. Compressed air, even in the sub-tank 4 when there is a pressure difference between the Chiyanba pressure and the sub-tank internal pressure Chiyanba 2
It gradually flows into the inside little by little, and it is possible to prevent an unpleasant shocking feeling. Moreover, because I controlled the duty,
There is a new effect such that the responsiveness of the opening of the cut valve 5 can be improved.

[Brief description of drawings]

FIG. 1 is a schematic constitutional view showing an embodiment of the present invention, FIG. 2 is a constitutional view showing the periphery of a cut valve of the same embodiment, FIG. 3 is a waveform diagram for explaining the operation of the same embodiment, and FIG. The figure is a waveform diagram showing a different example of the present invention. 1 ... Suspension, 2 ... Chamber, 3 ... Communication passage, 4 ... Sub tank, 5 ... Cut valve, 15 ... Controller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Okamura, Atsugi City, Kanagawa Prefecture, 1370, Atsugi Motor Parts Co., Ltd. 72) Inventor Yukio Ikeda 1370 Onna, Atsugi City, Kanagawa Prefecture Atsugi Auto Parts Co., Ltd. (72) Inventor Hideo Ito 2 Takaracho, Kanagawa-ku, Yokohama City, Kanagawa Prefecture Nissan Motor Co., Ltd. 2 Takaramachi, Kanagawa-ku, Yokohama-shi Nissan Motor Co., Ltd. (72) Inventor Kenji Kawagoe 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (56) Reference JP 62-103212 (JP, A) Special Open Sho-6050011 (JP, A) Actual Open Sho-60-51110 (JP, U)

Claims (1)

[Claims] 1. A sub-tank is attached to a chamber of a suspension receiving a high-pressure fluid from a pressure source through a communication passage, and a cut valve is provided in the communication passage, and the cut valve is opened to bring the chamber and the sub-tank into communication with each other. The suspension spring constant is reduced, and the air valve type suspension device with a sub-tank is adapted to increase the spring constant of the suspension by closing the cut valve to bring the chamber and the sub-tank out of communication with each other. The controller for instructing opening / closing is configured as an on / off control in which the cut valve drive current is continuously turned on / off for the required time, and the duty of this on / off control is changed and controlled with the passage of time. Air spring suspension device.