JP3040110B2 - Vehicle suspension equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is configured so that suspension characteristics can be changed by supplying and discharging a working fluid to and from a cylinder provided between a vehicle body and wheels. The present invention relates to a suspension device.

(Prior Art) A vehicle suspension device generally comprises a combination of a mechanical spring and a shock absorber. For example, as disclosed in Japanese Patent Publication No. 59-14365, a vehicle suspension device is provided between a vehicle body and wheels. A suspension device has also been proposed in which a cylinder is provided and the supply and discharge of a working fluid to and from the cylinder are controlled so that suspension characteristics such as vehicle height and hardness can be freely changed.

(Problems to be Solved by the Invention) The above-mentioned supply / discharge control in such a suspension device is performed by providing a predetermined control valve in a piping path of a working fluid and controlling the operation of the control valve by predetermined control means. However, since the working fluid supplied to the cylinder is in a high pressure state, when the cylinder is connected to the return pipe by the operation of the control valve, the working fluid in the cylinder rapidly flows into the return pipe. Then, a pressure rise occurs in the reflux pipe. When such a pressure rise occurs, a water hammer phenomenon such as abnormal noise and vibration occurs in the return pipe, which is not preferable.

Further, a main accumulator provided on a high-pressure pipe connecting the supply source of the working fluid and the control valve, a relief pipe connecting the main accumulator and the reflux pipe, and an ignition switch provided on the relief pipe are provided. When the ignition switch is closed and the ignition switch is opened and the ignition switch is opened, the working fluid in the main accumulator is in a high-pressure state. When the working fluid in the main accumulator is communicated with the return pipe through the return pipe, the working fluid in the main accumulator rapidly flows into the return pipe, and a pressure rise occurs in the return pipe. When such a pressure increase occurs, a water hammer phenomenon such as abnormal noise and vibration occurs in the return pipe, which is not preferable.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle suspension device that can prevent a water hammer phenomenon from occurring in a return pipe.

(Means for Solving the Problems) A suspension device for a vehicle according to the present invention, by providing a predetermined pressure attenuating means in a return pipe path, reduces a pressure increase in the return pipe, thereby achieving the above object. It was made. That is, in a vehicle suspension device configured to be able to change a suspension characteristic by supplying and discharging a working fluid to and from a cylinder provided between a vehicle body and wheels, a cylinder is provided with a hydraulic fluid according to a predetermined condition. A control valve for controlling the supply and discharge of the working fluid, and a return pipe connecting the control valve and the reservoir tank; and a pressure damping means for attenuating the pressure of the working fluid in the return pipe in the return pipe path. It is characterized by being provided.

The "pressure attenuation means" is not limited to a specific configuration as long as it can attenuate the pressure of the working fluid in the return pipe. For example, an accumulator, a throttle, or the like can be employed. The position of the "pressure damping means" in the return pipe route is not particularly limited, but is preferably as close to the control valve as possible in order to effectively prevent the water hammer phenomenon.

Further, the vehicle suspension device according to the present invention is a vehicle suspension device provided with a pressure attenuating means in the return pipe path, and further includes a high-pressure pipe connecting the supply source of the working fluid and the control valve. A main accumulator, a relief pipe connecting the main accumulator and the return pipe, and an ignition switch interlocking valve provided on the relief pipe, which is closed when an ignition switch is turned on and opened when the ignition switch is turned off. It is characterized by comprising.

(Operation) As shown in the above configuration, since the pressure attenuating means is provided in the return line, the operation of the control valve or the ignition switch interlocking valve causes the working fluid to rapidly flow into the return line. However, the pressure increase in the reflux pipe due to this is reduced by the pressure damping means.

(Effect of the Invention) Therefore, according to the present invention, it is possible to prevent the occurrence of the water hammer phenomenon in the return pipe.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a hydraulic circuit diagram showing an embodiment of a vehicle suspension device according to the present invention, and FIG. 2 is an overall configuration diagram of the suspension device.

In the figure, the main elements corresponding to the right front wheel, the left front wheel, the right rear wheel and the left rear wheel are numbered “FR”, “F”, respectively.
The symbols L, "RR" and "RL" are additionally shown, but in the following description, these symbols will be added only when particularly necessary.

As shown in FIG. 2, a hydraulic cylinder 4 is fixed to the vehicle body 2 for each wheel, and a hydraulic chamber 8 is defined by a piston 6 slidably fitted in the hydraulic cylinder 4. ing. A wheel 12 is held on a piston rod 10 integrated with the piston 6. A gas spring 14 communicates with the hydraulic chamber 8 via a hydraulic passage. This gas spring 14
Has a gas chamber 18 and a liquid chamber 20 defined by a diaphragm 16 as a movable partition, and the liquid chamber 20 is
Is communicated to.

As shown in FIG. 1, three gas springs 14 are provided for the front wheels and two gas springs are provided for the rear wheels, and they are connected to the hydraulic cylinders 4 in a parallel relationship with each other. An orifice 24 is provided in each of the hydraulic passages 22 communicating with each of the gas springs 14. A unit composed of such a combination of the hydraulic cylinder 4, the gas spring 14 and the orifice 24
With this damping action, the suspension device has a basic function as a suspension device.

A high-pressure pipe 26F or 26R is connected to each of the hydraulic cylinders 4, and supply and discharge of hydraulic fluid to and from the hydraulic cylinder 4 are performed through these pipes. The pump 28 for supplying the hydraulic fluid is composed of a vane pump driven by an engine, pumps the hydraulic fluid 32 from the reservoir tank 30, and uses the hydraulic fluid 32 for the front wheels and the rear wheels through the common high-pressure pipe 26. Pressure feed to high pressure pipes 26F and 26R. In this common high-pressure pipe 26, a filter 36, a check valve 38,
A main accumulator 40 for accumulating pressure and a system oil pressure gauge 42 are provided. In the pump 28,
An in-pump relief valve 44 is provided to recirculate the discharged hydraulic fluid 32 to the suction side when the pressure on the discharge side rises abnormally.

The high-pressure pipe 26F for the front wheels is branched into a high-pressure pipe 26FR for the right front wheel and a high-pressure pipe 26FL for the left front wheel.
FL is communicated with each hydraulic chamber 8 of the right front wheel hydraulic cylinder 4FR and the left front wheel hydraulic cylinder 4FL. The same is true for the rear wheels. In addition, each of the above high pressure pipes 26F, 26R
Pilot passages 46F, 46R are branched from the pilot passage, and these pilot passages 46F, 46R are connected to an electromagnetic on-off valve 48, respectively. In each of the high-pressure pipes 26FR, 26FL, 26RR, 26RL, a flow control valve 52 having a built-in pressure assurance valve 50, sequentially from the upstream side,
A pressure-operated on-off valve 54, a relief valve 56, and a hydraulic gauge 58 are interposed. And the relief port of each relief valve 56 is
It is connected to the reflux pipe 60F or 60R. The hydraulic fluid return ports of the pressure assurance valve 50 and the solenoid on-off valve 48 are also connected to the return pipe 60F or 60R. In the vicinity of the flow control valves 52 of the reflux pipes 60F and 60R, return accumulators 62 that perform a pressure accumulating action are respectively mounted.

The front-wheel-side reflux pipe 60F and the rear-wheel-side reflux pipe 60R are connected to a common reflux pipe 60 that extends through the cooling circuit 64 to the reservoir tank 32.
It is connected to the. The common reflux pipe 60 and the common high-pressure pipe 26 are communicated with each other by relief pipes 66 and 68. An unload relief valve 70 and an ignition switch interlocking valve 72 are interposed between the relief pipes 66 and 68, respectively. The connection between the relief pipes 66 and 68 and the common high-pressure pipe 26 is made on the upstream and downstream sides of the check valve 38, respectively.

Next, the operation of the suspension device having the above configuration will be described.

The operations of the unload relief valve 70, the ignition switch interlocking valve 72, the solenoid on-off valve 48, and the flow control valve 52 are controlled by a control unit 74 (see FIG. 2) composed of, for example, a microcomputer. The control unit 74 includes the system oil pressure gauge 42, an oil pressure gauge 58 provided for each hydraulic cylinder 4, each wheel 12FR, 12FL,
Acceleration sensor 7 that detects sprung acceleration every 12RR, 12RL
6, and a vehicle height sensor that detects the vehicle height (ie, cylinder stroke) for each wheel 12FR, 12FL, 12RR, 12RL
In FIG. 2, an oil pressure gauge 58, an acceleration sensor 76, and a vehicle height sensor corresponding to the left rear wheel 12RL are input.
Only 78 is shown). And the control unit
74 controls the supply and discharge of the hydraulic fluid 32 based on the cylinder internal pressure, sprung acceleration and vehicle height indicated by the oil pressure gauge 58, the acceleration sensor 76 and the vehicle height sensor 78, respectively.

That is, first, when the electromagnetic opening / closing valve 48 is closed by the control unit 74, even if the pump 28 and the like are operating normally, the hydraulic fluid 32 in the pilot passage 46 is operated by the operating type opening / closing valve Supply to 54 is cut off. Pressurized actuated on-off valve 54 connected to pilot passage 46
Is a device that is kept closed at all times and opens only when a predetermined operating pressure is received at the operating pressure receiving port 54a. Therefore, when the supply of the hydraulic oil 32 to the operating pressure receiving port 54a is interrupted as described above, the closed state is established. When the pressure-operated on-off valve 54 is closed in this way, the suspension device
The characteristics based on the elastic modulus of the gas spring 14 and the throttle resistance of the orifice 24 are shown. That is, at this time, the suspension device is a so-called passive suspension.

On the other hand, when the electromagnetic opening and closing valve 48 is opened by the control unit 74 while the pump 28 and the like are operating normally, the pressure of the operating oil liquid 32 is applied to the operating pressure receiving port 54a of the pressurized operation type opening and closing valve 54. Thereby, the on-off valve 54 opens. When the pressure-operated on-off valve 54 is opened and the flow control valve 52 is opened to the opening specified by the control unit 74, for example, the piston 10 is displaced upward (to the left in FIG. 1). When the hydraulic fluid 32 is supplied to the hydraulic chamber 8 of the hydraulic cylinder 4 during the operation, the displacement of the piston 6 is suppressed by the supplied hydraulic fluid 32, and as a result, the dynamic spring The constant changes in a direction to increase. By supplying and discharging the hydraulic fluid into and from the hydraulic cylinder 4 in this manner, the same effect as changing the throttle resistance of the orifice 24 and the elastic modulus of the gas spring 14 is obtained, and the suspension device functions as a so-called active suspension device. I do. Further, it is also possible to control the amount of hydraulic fluid in the hydraulic chamber 8 of the hydraulic cylinder 4 to control the vehicle height for each wheel.

In the above control, since the hydraulic oil supplied to the hydraulic chamber 8 of the hydraulic cylinder 4 is in a high pressure state, the flow control valve
By the operation of 52, the hydraulic chamber 8 of the hydraulic cylinder 4
When the working fluid is communicated with F, 60R, the working fluid in the hydraulic chamber 8 rapidly flows into the return pipes 60F, 60R, and a pressure rise occurs in the return pipes 60F, 60R. When such a pressure rise occurs, a water hammer phenomenon such as abnormal noise and vibration occurs in the return pipes 60F and 60R, which is not preferable.

However, in the present embodiment, the reflux pipes 60F, 60F
Since return accumulators 62 are provided in the paths of R, respectively,
Even if the working fluid flows into the 60F, 60R rapidly, the pressure increase in the return pipes 60F, 60R due to this is reduced by the pressure accumulating action of the return accumulator 62.
In other words, the return accumulator 62 functions as a pressure damping unit, whereby the return piping 60F, 60
The occurrence of the water hammer phenomenon in R can be prevented.

When the pressure in the high-pressure pipe 26 indicated by the system oil pressure gauge 42 exceeds a set value, the unload relief valve 70 is opened by the control unit 74, whereby the hydraulic fluid 32 is returned to the reservoir tank 30, and the high-pressure pipe is Abnormal pressure rise in 26 is prevented. Further, the control unit 74 performs control to close the ignition switch interlocking valve 72 only when the ignition switch is turned on, thereby opening the ignition switch interlocking valve 72 after the engine stops and releasing the high pressure state in the high pressure pipe 26. You. In this case, when the ignition switch interlocking valve 72 is opened, the high-pressure working fluid in the main accumulator 40 flows into the return pipes 60, 60R, and 60F rapidly through the relief pipe 68. The pressure increase in 60, 60R, 60F is alleviated by the pressure accumulating action of return accumulator 62. Therefore, even when the ignition switch interlocking valve 72 is opened, it is possible to prevent the occurrence of the water hammer phenomenon in the return pipes 60, 60R, and 60F.

As described above, if the hydraulic pressure (supply pressure) on the upstream side of the flow control valve 52 drops abnormally due to, for example, breakage of the high-pressure pipe 26, even if the electromagnetic on-off valve 48 is open, No predetermined operating pressure is applied to the pressure-operated on-off valve 54. Thereby, the on-off valve 54 is automatically closed,
At this time, the suspension device is in the passive state described above. Of course, even in this state, the basic function of the suspension device is maintained, so that there is no problem in running the vehicle. When the engine is stopped when the vehicle is parked, the pump 28 stops, and the ignition switch interlocking valve
Since 72 is open, the operating pressure receiving port 54a of the pressure-operated on-off valve 54
Does not receive a predetermined operating pressure. So in this case,
Even if the solenoid on-off valve 48 fails and is left open, the pressurized actuation-type on-off valve 54 is closed, so that the hydraulic oil 32 flows out of the hydraulic cylinder 4 little by little and the vehicle height becomes low. Such a situation is surely prevented.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of a vehicle suspension device according to the present invention, and FIG. 2 is an overall configuration diagram of the suspension device. 2 ... body, 4 ... hydraulic cylinder 6 ... piston, 8 ... hydraulic chamber 10 ... piston rod, 12 ... wheels 14 ... gas spring, 16 ... movable partition 18 ... gas chamber, 20 …… Liquid chamber 26 …… High pressure pipe, 28 …… Pump 30 …… Reservoir tank 32 …… Hydraulic fluid (working fluid) 52 …… Flow control valve (Control valve) 60 …… Reflux pipe 62 …… Return accumulator ( Pressure damping means) 74 Control unit

────────────────────────────────────────────────── (5) References JP-A-60-85008 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60G 17/04

Claims (2)

(57) [Claims] 1. A suspension device for a vehicle configured to change a suspension characteristic by supplying and discharging a working fluid to and from a cylinder provided between a vehicle body and a wheel, according to predetermined conditions. A control valve for controlling the supply and discharge of the working fluid to and from the cylinder, a recirculation pipe connecting the control valve to the reservoir tank, and a main valve provided in a high-pressure pipe connecting the supply source of the working fluid and the control valve. An accumulator, a relief pipe connecting the main accumulator and the return pipe, and an ignition switch interlocking valve provided on the relief pipe, which is closed when an ignition switch is turned on and opened when the ignition switch is turned off. A pressure damping means for damping the pressure of the working fluid in the return pipe is provided in the path. Suspension device for a vehicle. 2. The vehicle suspension device according to claim 1, wherein said pressure damping means is an accumulator.