JPH04154483A - Hydraulic control device for vehicle - Google Patents

Abstract

PURPOSE:To reduce power consumed by a pump by providing a pressure detector in a high pressure line leading to a power steering device, and actuating the hydraulic pressure control valve of an active suspension while constricting the valve in accordance with pressure drop in the high pressure line. CONSTITUTION:A hydraulic pump 1 is driven by an engine 2 and high pressure oil generated is fed to a high pressure line 3 and separated into a power steering device 9 and an active suspension device 10. In this case, the high pressure line 3 is provided with a pressure detector 6 and the output signal of the detector 6 is input to the active suspension controller 10. The signal of the pressure detector 6 is sent via an LPF 13 to a limiter circuit 14 and an output increase judging machine 15 along with the signal of a detector 10g for acceleration and the like and a hydraulic control valve 10c is controlled by final control operation input U2 obtained by limiting of control operation input U1 in accordance with lowering of the output Pm of the LPF 13. When the output Pm of the LPF 13 is lowered to below a reference value a signal requiring an increase in output is obtained for an engine controller 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an engine that directly drives a hydraulic pump,
A power steering device operated by its high pressure source,
Active suspension device.

The present invention relates to a method for reducing the power consumption of a hydraulic pump in a vehicle hydraulic control device equipped with an auxiliary drive device.

[Conventional technology]

Conventionally, as described in ``Numerical Analysis of Hydraulic Supply System for Active Suspension 1990 Hydraulic and Pneumatic Lecture Proceedings'', hydraulic control systems for vehicles have been used for power steering, active suspension systems, and engine cooling fans. There are active devices etc. A hydraulic source for driving these hydraulic devices is obtained by directly driving a hydraulic pump with an engine, and a hydraulic pump is provided on one side for each hydraulic device. For example, the hydraulic pumps used in the power steering system and the active suspension system are of a tandem type, and the pump for the power steering system and the pump for the active suspension system are belt-driven by the engine. The pump capacity for power steering is determined based on the idling rotation speed, and the pump capacity for active suspension hydraulic pumps is determined based on the rotation speed during normal driving. The discharge flow rate of these hydraulic pumps increases approximately in proportion to the engine speed.

Therefore, the power steering hydraulic pump generates an extra discharge flow rate during normal driving.

[Problem to be solved by the invention]

In this way, the conventional inter-vehicle hydraulic control device equipped with a power steering device and an active suspension device,
Because the criteria for setting the pump capacity are different, the pump power consumption is greater than necessary.

An object of the present invention is to provide a hydraulic control device for a vehicle, such as a power steering device and an active suspension device, in which a hydraulic pump is directly driven by an engine, and which consumes less power.

[Means to solve the problem]

A hydraulic pump is directly driven by the engine to secure a hydraulic source (high pressure line), and power steering devices and active suspension devices are used as hydraulic control devices for vehicles that are driven by this hydraulic source.

There are engine cooling fan drive devices, etc. Here, the required flow rate in the power steering device is up to a state near the idling rotational speed, and at a rotational speed higher than that, the flow rate becomes unnecessary. Therefore, if the unnecessary flow rate in the power steering device is used for the active suspension device and the auxiliary drive device, the power consumption of the hydraulic pump can be reduced. Among these hydraulic control devices, the one that affects vehicle safety is the power steering device. Therefore, when distributing the flow rate of the hydraulic power source in the power steering device, it is sufficient to constantly ensure the necessary flow rate from the viewpoint of safety, and to supply the remaining flow rate to other hydraulic control devices.

This can be achieved by directly supplying the pressure of a high pressure line to the power steering device and controlling the flow rate supplied to other devices so that the pressure of the high pressure line does not drop. Control of the flow rate supplied to the accessory drive device is made possible by providing a flow control valve between the high pressure line and the accessory drive device, which throttles the flow rate in accordance with a pressure drop in the high pressure line. Since active suspension systems must support the load acting on the vehicle body, this is possible by directly supplying pressure from a high-pressure line and operating with the pressure control valve installed in the active suspension system in a throttled state. Become. As a control method, a pressure detector may be provided in the high pressure line, and the pressure control valve may be throttled in response to a decrease in pressure in the high pressure line.

In addition, if the vehicle is idling, there will be insufficient flow, but in this case, the pressure in the high pressure line will drop below the standard value, and if it becomes necessary to increase the hydraulic pump discharge amount, the idling rotational speed will be increased. By controlling the engine output, it is possible to secure the minimum flow rate necessary for driving the active suspension system and auxiliary equipment.

[Effect]

The high pressure generated by the hydraulic pump is guided to the power steering device and the active suspension device via a relief valve, and the high pressure is guided to the auxiliary drive device via a flow control valve. The set pressure at which the pressure control valve installed in the active suspension device is close to fully open, and the set pressure at which the flow control valve for auxiliary equipment (the pressure at which the flow control valve is fully open) are greater than the set pressure at the relief valve. Set it a little lower. By configuring like this,
If the discharge flow rate of the hydraulic pump is greater than the flow rate consumed by the power steering system, active suspension system, or auxiliary drive system, the relief valve is activated and the excess flow is returned to the oil tank. In the opposite case, the relief valve is fully opened, and the entire discharge flow rate of the hydraulic pump is supplied to the power steering device, active suspension device, and auxiliary function operating device. At this time, the high pressure supplied to the power steering device becomes lower than the set pressure of the relief valve, so the pressure control valve provided in the active suspension device is throttled, and the flow control valve provided for the auxiliary equipment is throttled. It operates in the direction. Therefore, the pressure in the high-pressure line is restored, and the high pressure supplied to the power steering device is either set at a pressure where the pressure control valve installed in the active suspension device is close to fully open, or set at the flow control valve for the auxiliary equipment. More than pressure will be constantly secured.

Here, it is necessary to use a hydraulic pump with a capacity that can drive the power steering device and has a sufficient margin, but since the engine rotation speed during normal driving is more than three times the idling rotation speed, The margin is small. However, there are times when the car is driven in an idling state, so in that case, find the deviation between the signal of the pressure detector installed in the high pressure line of the hydraulic pump discharge and the set pressure value of the flow control valve, and adjust the pressure according to this deviation signal. Increase engine output by increasing the amount of fuel supplied to the engine.

By doing so, the idling rotational speed can be increased, and the minimum necessary flow rate to be supplied to the active suspension device can be ensured.

〔Example〕

An embodiment of the present invention will be described below.

FIG. 1 shows an example of the system configuration of the present invention. The hydraulic pump 1 is driven by an engine 2, and the generated high pressure oil is sent to a high pressure line 3. Engine 2 is engine controller 4
controlled by. The high pressure line 3 has an accumulator 5. A pressure detector 6 is provided. The oil in the high pressure line is divided into those that are returned to the oil tank 8 via the relief valve 7, those that are supplied to the power steering device 9, and those that are supplied to the active suspension system W10. The main accumulator 5 is used to compensate for instantaneous flow shortages and to absorb fluctuations in the discharge pressure of the hydraulic pump 1. The operating check valve 11 operates when the pressure in the high pressure line 3 drops to the point where it affects the power steering system 9, and cuts off the supply of oil to the active suspension system. The role of this valve is as a safety measure to ensure pressure in the high pressure line and enable steering operation in the event of a failure of the active suspension system, but it is desirable that the valve open and close slowly. The active suspension device 110 includes a sub-accumulator 10a, a three-way valve 10b,
Pressure control valve 10c, suspension hydraulic cylinder 10
d, pilot check valve 10e, controller 10f
, acceleration sensor, etc. 10g. The power steering device 9 consists of a hydraulic control valve 9a and a power steering hydraulic cylinder 9b, and operates smoothly when the set pressure is always acting as the supply pressure, but when the supply pressure decreases, the steering It becomes heavy and interferes with safe driving. The active suspension device operates a pressure control valve 10c by a controller 10f that operates in response to a signal of 10 g from an acceleration detector, etc., and moves a hydraulic cylinder 10 d t [to improve ride comfort and safety of the vehicle. The sub-accumulator 10a is for compensating for instantaneous flow shortage in the active suspension device. Furthermore, the three-way valve 10b and the operating check valve 10e are operated when the vehicle is parked or when the active suspension system malfunctions.During normal operation, the pressure in the high pressure line 3 is controlled by the pressure control valve 10c of the active suspension system. The operating check valve 10e is in an open state. The active suspension controller 10f is connected to the pressure detector 6,
It is also connected to the engine controller 4.

FIG. 2 is a block diagram of the control system of the hydraulic control device shown in FIG. 1. The active suspension system is controlled by calculating the signal from the acceleration detector 10g attached to the vehicle body in the arithmetic processing unit 12 to obtain the control operation amount U1. This part corresponds to a normal active suspension controller. One side of the signal from the pressure detector 6 is sent to a limiter circuit 14 via a low-pass filter 13, and the other side is sent to an output increase determination device 15.

The limiter circuit 14 limits the control operation amount U1 according to the decrease in the output Pm of the low-pass filter 13, determines the final control operation amount U2, and sends it to the drive circuit 16 of the hydraulic control valve 10c. There are two methods of limiting the amount of control operation: changing the gain and changing the maximum output value, and FIG. 2 shows a case where both are changed. Output increase judger 1
5 obtains a signal requesting an increase in engine output from the engine controller 4 when the output Pm of the low-pass filter 13 falls below a reference value. Upon receiving this signal, the engine controller 4 increases the engine output by increasing the amount of fuel supplied. FIG. 3 shows a control flow when the control shown in FIG. 2 is operated by a microcomputer. The main routine repeatedly executes steps 1 to 4, and in step 3 a limiter subroutine is executed. Step 1 in the main routine
and 2 correspond to the arithmetic processing section 12, and steps 3 and 4 correspond to the limiter circuit 14. In the limiter subroutine, in steps 1 and 2, a pressure signal Pm with high frequency components cut is obtained by calculating a low-pass filter from the signal P of the pressure detector 6 provided in the high-pressure line. In step 3, the set pressure P of the relief valve 7 is
The deviation δP between r and Pm is calculated. In step 4, δ
The limit value is calculated for the gain corresponding to P. This is obtained from the relationship shown in FIG. 4, and as the deviation δP increases, K and L are made smaller. In step 5, the gain of the control operation amount is changed, and in step 6, the maximum output value is set to be L or less. Step 7 corresponds to the function of the output increase determiner 15.

If the flow rate consumed by the power steering device 9 and the active suspension device 1o is less than the flow rate discharged by the hydraulic pump 1, the pressure in the high pressure line exceeds the set pressure Pr of the relief valve 7, so the relief valve 7 operates and the excess The flow rate is returned to the oil tank. The active suspension device operates without the hydraulic control valve 10c being throttled. Conversely, if the consumption flow rate is large, the pressure in the high-pressure line will drop, so the control is performed as explained in FIGS. 2 and 3, and the hydraulic control valve 10c operates in a throttled state. Then, the flow rate consumed by the hydraulic control valve 10c is reduced, and the pressure in the high pressure line is restored. In particular, the pressure at which the limit value of the control operation amount is almost close to O (set value of δP = Pr - P
At cl), the flow rate of the active suspension is almost completely throttled, so the pressure in the high pressure line does not fall below Pc1. Here, the set value of δP is set to a value as small as possible within a range in which the control system operates stably. By doing this, the pressure in the high pressure line can be maintained near the set pressure of the relief valve, so the flow rate necessary for the power steering device can always be ensured.

However, when the vehicle is running in an idling state, the active suspension system tends to run out of flow. In this case, the pressure in the high pressure line and the relief valve setting pressure are P c
2 (P r>P c 2>P c 1), the output increase determiner 15 operates, and the engine controller 4 receives this signal and increases the engine output. The engine rotation speed increases, making it possible to compensate for the insufficient flow rate of the hydraulic pump.

FIG. 5 shows the flow rate consumed by the active suspension device and the power steering device when the above configuration and control are performed and a hydraulic pump having the same capacity as the power steering device is used. Fifth
In the figure, the horizontal axis shows the engine rotation speed, and the vertical axis shows the consumption flow rate.

The portions below a and b are the flow amounts consumed in the power steering device, and the portions surrounded by b, a, c, and d are the flow amounts consumed in the conventional active suspension device. Since the discharge amount of the hydraulic pump 1 is less than the apg, it is called ``blate''.

The part surrounded by 19g is an extra flow rate for the power steering device. This extra flow rate is at(
The part surrounded by 3tLg is the flow rate consumed by the active suspension device in the present invention. Therefore, d
, c, e, and Lg are areas where the device according to the present invention suffers from a flow shortage compared to the conventional active suspension device. The flow consumption when driving on a paved general road falls into the area surrounded by b, C, e, f, and g, but when driving on a rough road at low speed, it becomes d +
It may fall into the area surrounded by CT et f+ g. When such a flow shortage occurs, the damping force of the suspension increases, resulting in a decrease in ride comfort.

However, the frequency of deterioration of ride comfort is very low, so
There is no particular problem.

FIG. 6 shows the power consumption of the hydraulic pump 1. The horizontal axis is the engine rotation speed, and the vertical axis is the power consumption.

h is the power consumption of the power steering hydraulic pump, and is equal to the power consumption when using the control method of the present invention.

i is the power consumption when using the conventional method. Conventionally, when the engine speed increases, the hydraulic pump has a flow rate that is considerably larger than that required by the power steering device, and the power consumption increases because the hydraulic pump pumps out the excess flow rate. By using the control method of the present invention, excess flow rate can be used effectively, so power consumption can be considerably reduced.

FIG. 7 shows a vehicle hydraulic control system comprising a power steering system, an active suspension system, and a radiator cooling fan drive system. This is the first
This is an embodiment in which a radiator cooling fan drive device is added to the hydraulic control device shown in the figure, and since the consumption flow rate increases, one hydraulic pump is also added. Since the unload solenoid valve 17 is normally open, the added hydraulic pump 1b is in an unload state. When a flow shortage occurs, the solenoid valve 17
When the check valve 18 is closed, oil is supplied by pushing up the check valve 18, so that the hydraulic pump la as a whole.

A flow rate of 1b is supplied. The opening and closing of the solenoid valve 17 is controlled by the solenoid valve controller 21 based on signals from the radiator cooling water temperature detector 19b and the pressure detector 6 provided in the high pressure line.
This is done by The radiator cooling fan drive device 19 operates by supplying high pressure to the hydraulic motor 19a. A solenoid valve (not shown) is provided immediately before the hydraulic motor inlet, and this solenoid valve opens when the radiator cooling water temperature detector 19b exceeds a set value. Further, high pressure is supplied to the electromagnetic valve described above through a flow control valve 20 provided between the high pressure line 3 and the hydraulic motor.

Here, as the flow rate control valve 20, one shown in FIG. 8 is used. FIG. 8 shows a valve that operates in the same way as a relief valve. This valve controls the flow rate by changing the area of the passage 24 formed between the sleeve 22 and the spool 23 by moving the spool 23 in the axial direction. Spool 23
The pressure of the inlet port 26 is guided to the end face 25 of the drain port 26 through a passage 28 having a throttling effect, and the opposite end face 29 is a drain space, and a coil spring 30 is interposed therebetween.

The spool 23 remains parallel at a position where the inlet pressure and the compressive force of the coil spring 3o are balanced. The area of the passage 24 is O
When the inlet pressure becomes Pcl, when the inlet pressure becomes higher than Pcl, the spool 23 moves in the direction of the coil spring 3o, so the area of the passage 24 increases and oil flows from the inlet port 26 to the outlet boat 27.

In FIG. 7, the set pressure of the relief valve 7 is Pr,
Let Pcl be the set pressure at which the flow control valve 20 is fully opened, and let P be the pressure of the high pressure line.

Pcl is set to be slightly lower than Pr. Further, the discharge amount of the hydraulic pump 1a is set to a capacity sufficient to drive the power steering device, and the hydraulic pump 1b is set to a capacity sufficient to drive the radiator cooling fan drive device. The discharge amount of pumps 1a and 1b is the power steering device.

If the flow rate is larger than that consumed by the active suspension device or radiator cooling fan drive device, P>
Since the oil becomes Pr, the relief valve 7 operates and the excess flow of oil is returned to the oil tank 8, and P is maintained at approximately Pr.

Conversely, when the discharge amount of the pumps 1a and 1b is insufficient, the relief valve 7 closes and the flow rate control valve 20 operates, and at the same time, the flow rate flowing to the active suspension device is throttled as described above, so that P is Maintained within PCI and Pr. In this way, the pressure supplied to the power steering device is always maintained within the range of Pcl and Pr, so steering can be performed smoothly. When the engine speed is higher than the idling speed, the hydraulic pump 1
Since the discharge amount of a is larger than the flow rate required for the power steering device, this extra discharge flow is supplied to the active suspension device and the radiator cooling fan drive device, so that the discharge amount of the hydraulic pump 1a can be used effectively. .

FIG. 9 shows a circuit of the solenoid valve controller 21. The signal from the temperature sensor 19b and its set value are input to the comparator 31, and the signal from the pressure sensor 6 is input to the low-pass filter 32.
The signal is input to the comparator 33 via. The outputs of the two comparators are input to an OR circuit 34 and output to a solenoid valve drive circuit 35. The operation of this solenoid valve controller is to close the solenoid valve 17 in the state shown in Table 1, and the discharge flow rate of the hydraulic pump 1b is sent to the high pressure line.

Therefore, when the temperature of the cooling water in the radiator is low, it is possible to compensate for the insufficient flow rate that occurs in the active suspension.

Furthermore, when the temperature rise of the radiator cooling water is small and the flow rate consumed by the power steering device 9 and active suspension device 10 is small, the entire device can be driven with only the hydraulic pump 1a, resulting in considerable power savings. It becomes possible.

The solenoid valve controller 21 can also be built into an active suspension controller, and the logic shown in FIG. 9 can be processed by a microcomputer.

As the flow control valve 20, instead of the flow control valve shown in FIG. 8, a proportional electromagnetic flow control valve and a pressure detector 6 provided in the high pressure line may be used. In this case, the pressure detector 6
When the signal becomes lower than Pr, the proportional electromagnetic flow control valve may be controlled to close.

In this embodiment, an engine cooling fan drive device is used as the auxiliary device drive device, but by appropriately selecting the capacity of the hydraulic pump lb, a generator or an air conditioner compressor can be driven in the same manner according to the present invention.

〔Effect of the invention〕

According to the present invention, since the excess flow rate generated by the power steering system can be effectively used for the active suspension system and the auxiliary drive system at an engine rotational speed during normal driving, the power consumption of the hydraulic pump can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a vehicle hydraulic control system according to the present invention, Fig. 2 is a block diagram of the control system, Fig. 3 is a flowchart of the control system, Fig. 4 is the relationship between gain and limit value with respect to pressure deviation, and Fig. 5 6 shows the relationship between the hydraulic pump consumption flow rate and the engine rotation speed, and FIG. 6 shows the relationship between the hydraulic pump power consumption and the engine rotation speed. Figure 7 shows a vehicle hydraulic control system with an auxiliary drive system installed;
Figure 8 shows the structure of the flow control valve for driving the auxiliary equipment, Figure 9
The figure is a block diagram of the controller that controls the unloading solenoid valve of the hydraulic pump. DESCRIPTION OF SYMBOLS 1... Hydraulic pump, 2... Engine, 3... High pressure line, 4... Engine controller, 6... Pressure detector, 7... Relief valve, 9... Power steering device, 10...active suspension device,
11... Operate check valve, 17... Solenoid valve,
19...Cooling fan drive device, 20...Flow rate control valve, 21...Electromagnetic force diagram

Claims (1)

[Claims] 1. A vehicle consisting of a hydraulic pump directly driven by an engine, a power steering device driven by the pressure of a high pressure line generated by the hydraulic pump, and an active suspension device incorporating a hydraulic control valve. A hydraulic control device for a vehicle, characterized in that a pressure detector is provided in the high pressure line, and the hydraulic control valve of the active suspension is operated in a throttled state in response to a decrease in pressure in the high pressure line. 2. A hydraulic control system for a vehicle comprising a hydraulic pump directly driven by the engine, a power steering device and an auxiliary equipment drive device driven by the pressure of the high pressure line generated by the hydraulic pump, in which the high pressure line and the A hydraulic control device for a vehicle, characterized in that a flow control valve is provided between an auxiliary drive device to throttle the flow rate according to a pressure drop in a high pressure line. 3. In the hydraulic control device according to claim 1 or 2, the idling speed of the engine is increased when a signal from a pressure detector provided in the high pressure line becomes lower than a setting. Vehicle hydraulic control device.