JP3208456B2 - Suspension control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control device for controlling the attitude of a vehicle body by supplying oil to a hydraulic cylinder interposed between the vehicle body side and the wheel side of an automobile.

[0002]

2. Description of the Related Art In recent years, various suspension control devices have been proposed to stabilize the posture of a vehicle body by automatically suppressing rolling and pitching that occurs in the vehicle body during traveling in an automobile or the like.

FIG. 13 shows an example of this suspension control device. FIG. 13 shows a front-wheel-side suspension control device. The rear-wheel-side suspension control device includes a hydraulic pump 1, a reservoir tank 2, and a main accumulator 6 to be described later.
Except for common use, etc., it has the same configuration as the front wheel side,
The description is omitted. In the figure, a hydraulic pump 1 is driven by an engine, a motor, and the like.
Is designed to store an oil liquid, and the hydraulic pump 1 and the reservoir tank 2 are connected via a suction pipe 3.

[0004] Reference numeral 4 denotes a supply pipe provided on the discharge side of the hydraulic pump 1. The supply pipe 4 has a check valve 5 for preventing backflow of the pressure oil to the hydraulic pump 1 side, and a supply pipe 4.
And a main accumulator 6 for temporarily storing the pressure oil from the hydraulic pump and supplying the pressure oil to the hydraulic cylinders 11a and 11b in accordance with the operation of the flow control valves 7a and 7b. . The downstream portion of the supply pipe 4 is branched and extended as branch supply pipe portions 4a and 4b.

[0005] Reference numerals 7a and 7b denote flow control valves connected to the branch supply pipe sections 4a and 4b, respectively. Each flow control valve 7a, 7b
Displaces the spool in accordance with the current supplied to the solenoids 7A and 7B, always to the neutral position (a), and to extend the hydraulic cylinder to the refueling position (b).
When the hydraulic cylinder is further contracted, the oil drain position (c)
In each case. Note that, even when the flow control valves 7a and 7b are in the neutral position (a) due to the structure as the spool valve, the oil liquid easily leaks from the outer peripheral portion thereof.

[0008] 8a and 8b are supply / discharge pipes for connecting the respective flow control valves 7a and 7b and suspension units 10a and 10b described later, respectively, and 9a and 9b are for connecting the respective flow control valves 7a and 7b and the reservoir tank 2. This is a return pipe line. In addition, return pipe
9a and 9b are respectively extended from the respective flow control valves 7a and 7b,
They are merged to form a merged pipe section 9A and extend into the reservoir tank 2.

[0007] 10a and 10b are suspension units for suspending the vehicle body (the same configuration is also provided on the rear wheel side), and 11a and 11b are hydraulic cylinders constituting the suspension unit. , 11b are connected to the hydraulic pump 1 via supply / discharge pipes 8a, 8b, and are expanded or contracted by pressure oil supplied / discharged from the hydraulic pump 1,
The vehicle height is adjusted or the posture of the vehicle body is controlled. The hydraulic cylinders 11a and 11b have accumulators.
12a and 12b are connected, and damping force valves 13a and 13b as damping force generating mechanisms are provided, and hydraulic cylinders 11a and 11b are provided.
When the pressure oil in b moves between the hydraulic cylinders 11a, 11b and the accumulators 12a, 12b, the damping force valves 13a,
13b generates a damping force.

[0008] 14a, 14b is a pilot check valve as a leakage prevention valve provided in the middle of each supply and discharge piping 8a, 8b, 15
Reference numerals a and 15b denote pilot pipes each having one end connected to each of the pilot check valves 14a and 14b, and reference numeral 15A denotes a merging pipe portion provided to merge with the pilot pipes 15a and 15b.
A pilot pressure control valve 16 is provided so as to be connected to the joining pipe section 15A. Pilot pressure control valve 16 is 3 port 2
Position pilot valves, each pilot pipe 15a, 15
b is connected to one of the branch supply pipes 4a, 4b and the return pipes 9a, 9b.
The junction pipe 15A is selectively connected to the branch supply pipes 4a and 4b and the return pipes 9a and 9b.

Further, an unloading pipe 19 is interposed between the supply pipe 4 between the hydraulic pump 1 and the check valve 5 and the merging pipe section 9A.
Unload valve 20 consisting of a 2-port 2-position electromagnetic switching valve
Is provided. The unload valve 20 is of the N / O type (unload when not energized, on-load when energized) and is always in the communication position (d) when not energized. When the pressure of the pressure oil supplied to the tank is equal to or higher than a predetermined value, the pressure oil from the hydraulic pump 1 is returned to the reservoir tank 2. When the pressure of the main accumulator 6 is equal to or less than a predetermined value, the main accumulator 6 is energized to be positioned at the neutral position (e) to prevent the oil liquid from flowing out to the reservoir tank 2 and supply the oil liquid to the main accumulator 6. Can be planned.

Further, between the supply pipe 4 on the upstream side of the unload valve 20 (closer to the hydraulic pump 1) and the merging line 9A downstream of the unload valve 20 (closer to the reservoir tank 2).
Relief valve to prevent abnormal circuit pressure value
21 are provided.

A control device (not shown) is provided connected to the flow control valves 7a and 7b, the pilot pressure control valve 16, the unload valve 20, and the like. , Vehicle speed, etc.).

In the suspension control device configured as described above, the hydraulic pump 1 is driven by driving the hydraulic pump 1.
Is discharged from the main accumulator 6 through a check valve, and when the pressure reaches a predetermined value, a pressure sensor (not shown) detects the pressure and the control device unloads. Position the valve 20 at the communication position (d) ,
The oil liquid from the hydraulic pump 1 is returned to the reservoir tank 2 so that the pressure in the supply pipe 4 becomes a predetermined value.

When the vehicle height is lowered due to an increase in the number of occupants or luggage, a vehicle height sensor (not shown) is provided.
Is detected, the flow rate control valves 7a, 7b are switched from the neutral position (a) to the refueling position (b) by the control device, and the oil liquid stored in the main accumulator 6 is supplied through the pilot check valves 14a, 14b. Supply to the hydraulic cylinders 11a and 11b of each suspension unit,
To maintain a constant vehicle height by increasing the vehicle height.

When the height of the vehicle increases due to a decrease in the number of occupants or load, the flow control valves 7a and 7b are switched from the neutral position (a) to the oil discharge position (c), and the hydraulic cylinder
The pressure oil in 11a, 11b is returned to the reservoir tank 2 through the return pipes 9a, 9b, and the hydraulic cylinders 11a, 11b contract, lowering the vehicle height and maintaining a constant vehicle height state.

[0015]

By the way, in the above, when the flow control valves 7a and 7b malfunction (lock) in the state of the oil supply position (b) or the oil discharge position (c), the failure flow rate Hydraulic cylinders 11a, 11b corresponding to control valves 7a, 7b
Or the vehicle height in this part remains high, or the hydraulic cylinders 11a and 11b corresponding to the failed flow control valves 7a and 7b contract and the vehicle height in this part remains low. As a result, there is a risk that proper adjustment of the vehicle height may be hindered.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a suspension control device capable of appropriately adjusting the vehicle height even if a malfunction occurs in a flow control valve.

[0017]

According to a first aspect of the present invention, in order to achieve the above object, a hydraulic cylinder is interposed between a vehicle body side and a wheel side, and a main pipeline connecting the hydraulic cylinder and a hydraulic source is provided. A suspension control device in which a control valve is disposed, and a control valve is moved to an oil supply side position or an oil discharge side position to supply and discharge oil to and from a hydraulic cylinder to control a posture of a vehicle body. , The oil supply side of the hydraulic pressure source and the control valve
A communication function for communicating the main pipeline with the main pipeline between the ports
And a check that allows only the flow of the oil liquid to the oil supply port
A supply-side switching means capable of selectively setting a return function and a return pipe connecting the oil-discharge port of the control valve to a reservoir tank attached to a hydraulic pressure source and the supply-side disconnection of the main pipe.
Connecting or blocking the pipe to the pipe between the
A first switching valve for disconnecting the first return valve;
Closes or communicates with the return line downstream of the switching valve
A second switching valve is provided, and the second return valve is connected to the second switching valve.
On the downstream side of the switching valve and on the supply side switching means of the main line
It is characterized in that a relief valve is provided in a pipe between the outlet side and the outlet side .

According to a second aspect, in order to achieve the above object,
A hydraulic cylinder is interposed between the vehicle body side and the wheel side, and a control valve is disposed in a main pipeline connecting the hydraulic cylinder and a hydraulic power source, and an oil supply side position or an oil discharge side position of a valve body of the control valve. A suspension control device that controls the attitude of the vehicle body by supplying and discharging oil to and from a hydraulic cylinder by controlling movement to a hydraulic cylinder, wherein the main pipe is provided in a main pipeline between the hydraulic pressure source and an oil supply port of the control valve. Communication function that connects the
A check function that allows only the flow of oil liquid to the
The-option configurable supply side switching means is provided, upstream of the supply side switching means of the control valve of the oil discharge side port hydraulic source return conduit connecting to the reservoir tank which is attached to said main conduit
A first cut-off that connects or disconnects the pipe between
A valve is provided upstream of the return pipe upstream of the pipe.
A third switching valve for closing or communicating the return line is provided.
Characterized in that was.

[0019]

According to the first aspect of the present invention, when the control valve is locked at the refueling position, the second switching valve is shut off to bring the supply-side switching means and the first switching valve into communication with each other. The hydraulic cylinder, the oil supply port of the control valve, the supply side switching means, and the relief valve constitute a circuit for discharging the oil liquid to the reservoir tank, and the excess oil liquid from the hydraulic cylinder over the relief pressure passes through the discharge circuit. Will be discharged.

When the control valve is locked at the oil discharge position, the second switching valve is shut off and the supply-side switching means is set in the communicating state, so that the oil pressure of the hydraulic source, the first switching valve, and the control valve is drained. The port constitutes a supply circuit for the oil liquid to the hydraulic cylinder, and the oil liquid is supplied from the oil pressure source to the hydraulic cylinder through the supply circuit.

The second invention is configured as described above.
When the control valve is locked at the refueling position, the third switching valve is closed and the supply-side switching means and the first switching valve are set in the communicating state, so that the hydraulic cylinder, the refueling port of the control valve, the supply-side switching means, The first switching valve constitutes a circuit for discharging the oil liquid to the reservoir tank, and the oil liquid is discharged from the hydraulic cylinder through the discharge circuit.

When the control valve is locked at the oil discharge position, the main line and the return line are shut off by setting the first and third switching valves to the shut-off state, and the oil liquid flows out of the hydraulic cylinder. Is prevented.

[0023]

Next, an embodiment of the present invention will be described with reference to FIGS. The overall configuration of the suspension control device according to the present embodiment is substantially the same as that of the prior art described with reference to FIG. 13, and the same members are denoted by the same reference numerals and description thereof will be omitted.

First, a first embodiment of the present invention will be described with reference to FIG. In this apparatus, a supply-side switching valve 30 as a supply-side switching means having a communication function and a check valve function selectively set by a control device is provided in place of the check valve 5 in comparison with the above-described conventional one. A pilot connecting a return passage switching valve (second switching valve) 31 to the merging pipe section 9A downstream of the valve (first switching valve) 20 and connecting to the merging pipe section 9A instead of the relief valve 21 The difference is that a pilot type relief valve 32 having a pipe 32A is provided. The pilot relief valve 32 is operated by setting the internal pressure of the pilot pipe 32A to P _P and the hydraulic pump 1 discharge side (supply pipe 4).
If the relief pressure and _{P 1, P 1 = -KP P} + P S (1) K: the pressure receiving area ratio _{S PP} / S _P1 P S: a relief pressure at the P _P = 0. That it is, in order to relief pressure can be changed by the internal pressure P _P in the pilot pipe 32A. In addition,
P _P = 0 when the system is normal, and P _P =
Although the P _1, the relief pressure P ₁ when the respective following equations (2) and (3). Relief pressure at P _P = 0: P ₁ = P _S … When the system is normal (2) Relief pressure at P _P = P ₁ : P ₁ = P _S / (1 + K)… At system failure (3)

In this embodiment, the unload valve described above is used.
20 constitutes a first switching valve.

The operation of the suspension control device thus configured will be described. First, when the system is normal, the supply-side switching valve 30 is turned on, so that the supply-side switching valve 30 performs a check valve function. Even when the discharge pressure of the hydraulic pump 1 becomes substantially zero due to the unload operation, , The pressure of the main accumulator 6 is maintained at a constant value. Further, the return passage switching valve 31 is energized, and the return pipe lines 9a and 9b communicate with the reservoir tank 2 so that the pressure becomes substantially zero.

As a result, the pressure in the pilot pipe 32A of the pilot type relief valve 32 also becomes substantially zero, and the relief pressure is set to the maximum pressure that guarantees system safety (equivalent to the equipment withstand pressure). In the case where the electric control system fails or the unload valve 20 locks in the on-load state, the pilot-type relief valve 32 can cope with a trouble.

When the flow control valves 7a and 7b become uncontrollable due to the lock of the spool (the spool can be locked at any of the oil supply position, the neutral position and the oil discharge position), or the electric control system fails. When a normal control command cannot be issued (for example, when each sensor fails or the computer itself runs away), power supply to all actuators (in this case, solenoids) is stopped. The operation in each of the above cases will now be described. In this case, the return pipes 9a and 9b upstream of the return path switching valve 31 are disconnected from the reservoir tank 2 by the return path switching valve 31, and the supply pipe 4 is returned by the unload valve 20 to the return pipes 9a and 9b. Will be communicated with 9b. Further, when the supply side switching valve 30 is opened, the flow control valves 7a and 7b are opened.
Supply port, main accumulator 6 and supply pipe 4
Communicates with the hydraulic pump 1. That is, the internal pressures of the supply ports, the tank ports, the cylinder ports, and the main accumulator 6 of the flow control valves 7a and 7b become the same. This pressure is maintained so as to be the pressure represented by the above-mentioned equation (3), that is, the value in the vehicle height neutral state.

When the flow control valves 7a and 7b are locked at the refueling position, the hydraulic cylinder which has been fully extended before the failure is detected
The pressure oil in 11a, 11b and accumulators 12a, 12b is supplied to pilot check valves 14a, 14b by the pressure in return pipes 9a, 9b.
Since b is in an open state, it flows backward through the supply-side ports of the flow control valves 7a and 7b, passes through the supply pipe 4, and from the pilot-type relief valve 32 whose relief pressure is reduced to the reservoir tank 2
Will be leaked. As a result, even if the flow control valves 7a, 7b malfunction at the refueling position, the hydraulic oil can flow out from the hydraulic cylinders 11a, 11b corresponding to the failed flow control valves 7a, 7b, and the appropriate vehicle height adjustment can be performed. Can be achieved.

When the flow control valves 7a and 7b are locked at the oil discharge position, the hydraulic pump 1 passes through the unload valve 20, the return pipes 9a and 9b, and the oil discharge ports of the flow control valves 7a and 7b. Pressure oil is supplied to hydraulic cylinders 11a, 11b and accumulators 12a, 12
b. This allows the flow control valves 7a, 7b
Even if the valve malfunctions at the oil discharge position, pressure oil can be supplied to the hydraulic cylinders 11a and 11b corresponding to the failed flow control valves 7a and 7b as necessary, and proper vehicle height adjustment can be achieved. Will be able to

When the control is interrupted due to a malfunction of the control system (the spools of the flow control valves 7a and 7b are locked) in the vehicle height abnormal state, the control is performed from the outer periphery of the spools of the flow control valves 7a and 7b. (The amount of leakage from the clearance is generally several tens of cc / min.).
The pressure of 11b and the accumulators 12a and 12b becomes a value in a neutral state, whereby a proper vehicle height adjustment can be achieved after a lapse of a predetermined time.

In each state described above, the pilot check valves 14a and 14b are open. That is, in this state, the pilot pressure control valve 16 is de-energized, but the internal pressure of the return pipes 9a, 9b increases, so that the pressure of the pilot pipes 15a, 15b increases through the pipe 18. In this case, the valve opening pressure (valve closing pressure) of the pilot check valves 14a and 14b is reduced by the relief pressure P _S at the time of failure of the relief valve 32.
By making it slightly smaller, after a failure occurs,
Even if the pump (engine) stops and the circuit pressure drops due to leakage, the pilot check valves 14a and 14b close before the vehicle height does not drop significantly, thereby maintaining the vehicle height in an appropriate state. it can. As a result, even when a failure occurs during running and the rotation of the hydraulic pump 1 stops (engine stall, wheel lock, etc.), the posture does not become extremely unstable, and safe running is achieved. It can be achieved reliably.

Next, a second embodiment of the present invention will be described with reference to FIG. The suspension control device shown in FIG. 2 is different from that shown in FIG. 1 in that an electromagnetic proportional relief valve 40 is provided instead of the pilot type relief valve 32.
The electromagnetic proportional relief valve 40 can obtain a relief pressure proportional to the magnitude of the current supplied from the control device, and the relief pressure is set to be low at the time of failure as in the first embodiment.

In this suspension control device, the operation is the same as that shown in FIG.
Even if a, 7b malfunctions at the oil supply position or the oil discharge position, the hydraulic oil can flow out or inflow to the hydraulic cylinders 11a, 11b corresponding to the failed flow control valves 7a, 7b, and the appropriate vehicle height Adjustment can be achieved.

Next, a third embodiment of the present invention will be described with reference to FIG. The suspension control device shown in FIG. 3 is different from that shown in FIG. 1 in that a pilot-type check valve 50 is provided as supply-side switching means instead of the supply-side switching valve 30, and the pilot pipe 50A of the pilot-type check valve 50 is The difference is that it is provided in the middle of the pilot pipe 32A.

This suspension control device also operates in the same manner as that shown in FIG. 1, so that the flow control valves 7a, 7
Even if b malfunctions at the oil supply position or the oil discharge position, the hydraulic oil can flow out or in to the hydraulic cylinders 11a and 11b corresponding to the failed flow control valves 7a and 7b to adjust the vehicle height appropriately. Can be achieved. Further, in this embodiment, the pilot type check valve 50 is provided in place of the supply side switching valve 30, so that the number of solenoids can be reduced as compared with that shown in FIG.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.

The fourth embodiment differs from the first embodiment (shown in FIG. 1) in that an externally connected pilot pipe 32 is provided.
A relief valve 60 having no externally connected pilot pipe is provided in place of the pilot type relief valve 32 having A, and an electromagnetic proportional relief valve is used in place of the return passage switching valve 31.
The main difference is that 61 (relief pressure is about 100 kg / cm ² ) is provided. The relief valve 60 is for preventing pressure destruction of the device, and its relief pressure is set to about 200 kg / cm ² which is higher than the relief pressure of the electromagnetic proportional relief valve 61.

The electromagnetic proportional relief valve 61 is provided with an electromagnetic proportional relief valve drive circuit 62 shown in FIG.
The electromagnetic proportional relief valve drive circuit 62 includes hydraulic cylinders 11a, 11
b, a cylinder pressure is input from a pressure sensor provided corresponding to b through a switch 63, and the hydraulic cylinders 11a,
(If the hydraulic cylinders 11a, the direction of 11b pressure large, a positive.) 11b of the pressure at the neutral position (neutral state pressure) P _CO and pulling difference signal and a comparator 64 for outputting, connected to the output of the comparator 64 And an adder 66 for adding the output signal of the differentiator 65 and the neutral pressure.
And an amplifier 67 that amplifies the output data of the adder 66 and outputs the amplified data with a dither signal (harmonic signal). The output data of the amplifier 67 is supplied to an electromagnetic proportional relief valve 61, , The relief pressure is set as described later. In this case, the differentiator 65 is formed of a high-pass filter capable of changing a time constant, and outputs a peak-shaped signal corresponding to the time constant. As a result, the electromagnetic proportional relief valve drive circuit 62 applies the pressure P to the hydraulic cylinders 11a and 11b.
If but greater than the pressure in the neutral state P _CO (refueling side lock),
The output of the amplifier 67 is reduced after rising to a peak (see FIG. 7). Conversely, the hydraulic cylinders 11a, a pressure P of 11b is less than the pressure in the neutral state P _CO (oil discharge side locking), the output of the amplifier 67, and finally is gradually increased from 0 to converge to the neutral pressure command values Shape (see FIG. 9).
By outputting a signal from the amplifier 67 in this manner, the electromagnetic proportional relief valve 61 sets a relief pressure that is substantially proportional to the solenoid current (corresponding to the output of the amplifier 67) as shown in FIG.

In this case, the case where the pressure of the hydraulic cylinders 11a and 11b is detected by the pressure sensor is described as an example. However, when the pressure sensor is not provided, the lock position of the flow control valves 7a and 7b is set to the vehicle height sensor. The same processing as described above can be performed by detecting with the method using. When the vehicle height sensor is used, if the vehicle height is abnormally high, it is determined that the fuel supply lock or the sensor is abnormal, and if the vehicle height is abnormally low, the oil discharge side lock or the sensor is abnormal.

The operation of the suspension control device having the above configuration will be described in comparison with the first embodiment.

FIG. 8 shows a flow control valve according to the first embodiment.
The relationship between the current supplied to the solenoid and the pressure in the pipe when 7a and 7b are locked at the refueling position is shown. In Figure, P _M is the pressure of the main accumulator 6, P _C is a hydraulic cylinder 11a, 11
b and _PT are in return pipes 9a and 9b (return passage switching valve 31
The upstream pressure _PCo indicates the pressure in the neutral state of the hydraulic cylinders 11a and 11b. Pressure P _M of the main accumulator 6 in this thing, to rise at the time of on-load (unload valve 20 on), and the pressure is gradually reduced at the time of unloading.

[0043] If the time T ₁ at a flow rate control valve 7a, 7b of the spool is locked by the fueling position (fail-generation), the hydraulic cylinders 11a, pressure of 11b rises, the main accumulator 6
(The hydraulic cylinders 11a and 11b are extended and the vehicle height is in an extended state.)

[0044] is detected failure at time T _2, 3 valves (supply side switching valve 30, the unload valve 20, the return path switching valve 3
1) is turned off (the supply-side switching valve 30 is in the communicating state, the unload valve 20 is in the communicating state, and the return passage switching valve 31 is in the shut-off state). At the same time, the internal pressure of the return pipes 9a and 9b rises sharply, and this pressure is led to the pilot type relief valve 32 through the pilot pipe 32A. The pilot-type relief valve 32 reduces the relief pressure by increasing the internal pressure of the pilot pipe 32A and discharges the pressurized oil in the supply pipe 4 to the reservoir tank 2 at a stretch. For this reason, the pressure in the pipeline in which the pilot type relief valve 32 is provided and the hydraulic cylinders 11a and 11b vibrate as shown in FIG. 8, and there is a possibility that vehicle height fluctuations and impulsive sounds may be generated.

On the other hand, in the fourth embodiment, as shown in FIG. 7, at the time of failure detection (time T ₂ ), the supply-side switching valve 30 and the unload valve 20 are turned off. At this time, a neutral position command value is input to the amplifier 67, and a current I shown in the figure is supplied from the amplifier 67 to the electromagnetic proportional relief valve 61. Current I reaches the peak value immediately after energization (set at approximately the supply pressure of normal), converges to the neutral pressure command value current then time T _3. Thus, circuit pressure and a hydraulic cylinder 11a, the pressure of 11b gradually converged to the neutral pressure P _CO,
The vehicle of the first embodiment does not generate a vehicle height abnormality or an impact sound which may occur.

FIG. 10 shows a flow control valve according to the first embodiment.
The relationship between the current supplied to the solenoid and the pressure in the pipe when 7a and 7b are locked at the oil discharge position is shown. In this case, similarly to the case described above, the pressure of the pipeline provided with the pilot type relief valve 32 and the hydraulic cylinders 11a and 11b vibrates as shown in FIG. .

On the other hand, in the fourth embodiment, as shown in FIG. 9, the energizing current of the electromagnetic proportional relief valve 61 gradually rises from 0, and the main accumulator 6 immediately after the supply-side switching valve 30 is turned off. Backflow of pressurized oil from the reservoir tank 2
To escape. Therefore, the pressure rise of the supply pipe 4, the return pipe lines 9a, 9b, and the hydraulic cylinders 11a, 11b becomes gentle, and the pressure fluctuation becomes small, so that the vehicle height fluctuation and the impact noise are not generated.

Next, a fifth embodiment of the present invention will be described with reference to FIG. The suspension control device shown in FIG.
The return passage switching valve 31 and the pilot-type relief valve 32 are omitted, and an electromagnetic switching valve (third switching valve) 70 is provided in the merging line section 9A on the upstream side of the unload valve 20 as compared with that shown in FIG. That is different.

This suspension control device also operates in the same manner as that shown in FIG. 1, so that the flow control valves 7a, 7
Hydraulic cylinder corresponding to the failed flow control valve 7a, 7b, even if b has malfunctioned at the refueling or draining position
Appropriate vehicle height adjustment can be achieved by flowing out or inflow of pressure oil to and from 11a and 11b.

If one of the flow control valves 7a, 7b malfunctions while being in the refueling position, the hydraulic cylinder
The hydraulic pressure in the hydraulic cylinders 11a and 11b expands. However, when an abnormality is detected by a vehicle height sensor (not shown) or a pressure sensor (not shown), the unload valve is opened.
Turn off the power to 20 and set the unload valve 20 to the communication position,
The pressure oil from the hydraulic pump 1 is returned to the reservoir tank 2 to prevent the supply of the oil liquid to the flow control valves 7a and 7b. Further, the flow control valves 7a and 7b which normally operate are once returned to the neutral position, and the power supply to the supply side switching valve 30 and the electromagnetic switching valve 70 is stopped. As a result, the junction pipe section 9A is brought into a non-communication state with the reservoir tank 2. Since the supply side switching valve 30 is in a communicating state, the oil liquid in the hydraulic cylinders 11a and 11b flows backward through the supply ports of the flow control valves 7a and 7b in which the malfunction has occurred, and the oil in the main accumulator 6 flows. The liquid is returned to the reservoir tank 2 via the unload valve 20.

When the pressure of the supply pipe 4 falls below a predetermined value,
The supply-side switching valve 30 is energized again to prevent the backflow of the oil liquid from the hydraulic cylinders 11a and 11b, and to switch the normally operating flow control valves 7a and 7b to the supply position, so that the pressure of the two or four wheels becomes equal. The supply and discharge pipes 8a and 8b are communicated so that the pressure is increased.

If one of the flow control valves 7a, 7b malfunctions while being in the oil discharge position, the hydraulic cylinder
The hydraulic fluid in 11a, 11b is returned to the reservoir tank 2 via the electromagnetic switching valve 70, so that the hydraulic cylinders 11a, 11b are lowered.
The power supply to the hydraulic cylinders 11a and 11b is stopped so that the junction pipe section 9A is not communicated with the reservoir tank 2 to prevent the hydraulic fluid from being discharged from the hydraulic cylinders 11a and 11b.

In the same manner as described above, in order to stop the power supply to the supply side switching valve 30 and the electromagnetic switching valve 70, the pressure oil from the hydraulic pump 1 and the oil liquid in the main accumulator 6 pass through the unload valve 20. To the reservoir tank 2.

When the pressure in the supply pipe 4 becomes equal to or less than a predetermined value, the supply side switching valve 30 is energized again. (This operation is not necessary for an operation failure at the oil discharge position. The control is simplified by using the same operation as in the case of malfunction of the valve.) In addition, the normally operating flow control valves 7a and 7b are switched to the oil discharge position, and the The supply and discharge pipes 8a and 8b are communicated so that the pressure of the two or four wheels is the same.

As described above, according to the present embodiment, the control is performed so that the cylinder pressure of the four wheels is set to the same pressure at any of the oil supply position and the oil discharge position of the flow control valves 7a and 7b in response to the malfunction. Therefore, an appropriate vehicle height can be maintained at the time of a failure, and safety is ensured. In the case of the first embodiment, the unload valve 20 is used when the malfunction is taken.
The return passage switching valve 31 provided between the tank port and the reservoir tank 2 is closed and the pilot relief valve 32 is closed.
In order to control the relief pressure to be the pressure value at the time of cylinder neutral, the circuit pressure at the time of the countermeasure increases,
As the power loss increases and the temperature of the oil liquid increases, there is a possibility that the hydraulic pump 1 itself may malfunction, but in this case, the hydraulic oil from the hydraulic pump 1 is supplied through the unload valve 20. Since the pressure is returned to the reservoir tank 2, the pressure of the hydraulic pump 1 does not increase, the power loss is reduced, the abnormal temperature rise does not occur, and the malfunction of the hydraulic pump 1 occurs. There is no.

Instead of the electromagnetic switching valve 70 shown in FIG. 11, a pilot type switching valve 71 operated by the pressure of the supply pipe 4 may be provided as shown in FIG. Normally, since the pressure in the supply pipe 4 is maintained at a high value, the pilot-type switching valve 71 is in a communicating state. However, if a malfunction occurs in the flow control valves 7a and 7b, the pressure in the supply pipe 4 becomes low. Accordingly, the pilot type switching valve 71 is switched to the non-communication state by the spring force.

In each of the above embodiments, the case where the control valve is a flow control valve is described as an example. However, the present invention is not limited to this, and may be, for example, a pressure control valve.

[0058]

According to the first aspect of the present invention, since the suspension control device is configured as described above, when the control valve is locked at the oil supply position or the oil discharge position, the oil is transferred from the hydraulic cylinder corresponding to the failed control valve. Properly adjusts the vehicle height by preventing the hydraulic cylinder from being extended or contracted due to liquid spillage or oil supply. it can.

Since the second invention is a suspension control device configured as described above, when the control valve is locked at the oil supply position or the oil discharge position, the hydraulic fluid is supplied from the hydraulic cylinder corresponding to the failed control valve. Properly adjusts the vehicle height by preventing the hydraulic cylinder from expanding or contracting due to spillage or oil drainage. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a suspension control device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a suspension control device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a suspension control device according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a suspension control device according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing an electromagnetic proportional relief valve drive circuit 62 of the suspension control device.

FIG. 6 is a diagram showing current and relief pressure characteristics of an electromagnetic proportional relief valve of the suspension control device.

FIG. 7 is a diagram showing a current supplied to a solenoid and a pressure characteristic in a pipe when the flow control valve is locked at a refueling position in the suspension control device.

FIG. 8 is a diagram showing a current flowing through a solenoid and a pressure characteristic in a pipe when the flow control valve is locked at a refueling position in the first embodiment.

FIG. 9 is a view showing a current flowing to a solenoid and a pressure characteristic in a pipe when a flow control valve is locked at an oil discharge position in a fourth embodiment.

FIG. 10 is a view showing a current flowing to a solenoid and a pressure characteristic in a pipe when the flow control valve is locked at an oil discharge position in the first embodiment.

FIG. 11 is a diagram showing a suspension control device according to a sixth embodiment of the present invention.

FIG. 12 is a diagram showing a suspension control device in which a pilot-type switching valve is provided instead of the electromagnetic switching valve of the suspension control device.

FIG. 13 is a diagram showing an example of a conventional suspension control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic pump 2 Reservoir tank 4 Supply pipe 7a Flow control valve 7b Flow control valve 9a Return pipe 9b Return pipe 11a Hydraulic cylinder 11b Hydraulic cylinder 20 Unload valve (first switching valve) 30 Supply side switching valve (supply side) Switching means) 31 Return passage switching valve (second switching means) 32 Pilot type relief valve 70 Solenoid switching valve (third switching valve)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60G 17/04

Claims (2)

(57) [Claims] 1. A hydraulic cylinder is interposed between a vehicle body side and a wheel side, and a control valve is disposed in a main pipeline connecting the hydraulic cylinder and a hydraulic pressure source. Alternatively, in a suspension control device that controls the posture of a vehicle body by supplying and discharging oil to and from a hydraulic cylinder by controlling movement to an oil discharge side position, a main pipe between the oil pressure source and an oil supply port of the control valve is provided. To the refueling side port
And a check function that allows only the flow of oil liquid
The supply side switching means for providing, the supply side of the control valve of the oil discharge side port hydraulic source return conduit connecting to the reservoir tank which is attached to said main conduit
The pipe is connected to the pipe between the upstream side of the switching means or
A first switching valve for shutting off is provided, and the return pipe is provided downstream of the first switching valve in the return pipe line.
A second switching valve for closing or communicating with the main pipe, and a downstream side of the second switching valve of the return pipe and the main pipe.
In the pipe between the supply path switching means and the upstream side of the passage.
A suspension control device comprising a valve . 2. A hydraulic cylinder is interposed between a vehicle body side and a wheel side, and a control valve is disposed in a main pipeline connecting the hydraulic cylinder and a hydraulic power source. Alternatively, in a suspension control device that controls the posture of a vehicle body by supplying and discharging oil to and from a hydraulic cylinder by controlling movement to an oil discharge side position, a main pipe between the oil pressure source and an oil supply port of the control valve is provided. To the refueling side port
And a check function that allows only the flow of oil liquid
The supply side switching means for providing, the supply side of the control valve of the oil discharge side port hydraulic source return conduit connecting to the reservoir tank which is attached to said main conduit
The pipe is connected to the pipe between the upstream side of the switching means or
A first switching valve for shutting off, wherein the return pipe is provided upstream of the pipe of the return pipe;
A third switching valve that closes or communicates with the suspension control device.