JPH04325378A - Operating fluid feeder for vehicle - Google Patents

Abstract

PURPOSE:To feed an operating fluid with sufficient pressure to a power assist device when the discharge pressure of a pump is reduced to decrease the energy loss of a suspension. CONSTITUTION:A variable-discharge pressure pump 16, the first feed passage 18 connecting the pump 16 and an active suspension 22, the second feed passage connecting the pump 16 and a power assist device 28, a booster device 30 provided in the middle of the second feed passage and boosting the operating fluid flowing in the passage, and a control device controlling the discharge pressure of the pump 16 and the action of the booster device 30 are provided. When the discharge pressure of the pump 16 is set low, the booster device 30 is operated, when the discharge pressure of the pump 16 is set high, the booster device 30 is not operated.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a working fluid supply system for vehicles such as automobiles, and more particularly, the present invention relates to a working fluid supply system for vehicles such as automobiles, and more particularly, it supplies high pressure to both power assist devices such as power steering devices and power assist brake devices, and hydraulic active suspensions. The present invention relates to a working fluid supply device configured to supply working fluid.

0002

2. Description of the Related Art As one of the working fluid supply devices for vehicles such as automobiles, for example, as described in Japanese Utility Model Application No. 60-158966, a working fluid supply device for a vehicle height adjustment device and a hydraulic active suspension is used. A working fluid supply device has already been proposed that is integrated with a working fluid supply device for a power steering device and is configured to be able to supply high-pressure working fluid to both the suspension and the power steering device.

[0003] According to such a working fluid supply device, the number of parts such as pumps can be reduced compared to a case where a working fluid supply device is provided separately for each of the suspension and power steering devices, and fuel efficiency can be reduced. can be improved.

0004

[Problems to be Solved by the Invention] Particularly when the suspension is a hydraulic active suspension, as is well known, the pressure within the actuator that increases or decreases the vehicle height is generally controlled to increase or decrease by a pilot-type pressure control valve or flow rate control valve. During operation of the active suspension, working fluid constantly flows through the pilot pressure formation of these control valves, resulting in energy losses. Since such energy loss is equal to (pump discharge pressure) x (working fluid flow rate), a variable discharge pressure pump is used as the pump of the working fluid supply system, and the active suspension does not need to be operated as much when the vehicle is stopped or when the vehicle is stopped. It is conceivable to reduce the above-mentioned energy loss by lowering the pump discharge pressure when the vehicle is running at very low speeds.

However, when the working fluid is supplied to both the active suspension and the power steering device by one working fluid supply device, the power steering device requires high-pressure working fluid during stationary steering. The discharge pressure of the pump is insufficient, and as a result, it is not possible to perform stationary steering easily.

The present invention has been developed in view of the above-mentioned problems when the working fluid supply device for a hydraulic active suspension is also used as a working fluid supply device for a power assist device. An improved vehicle that can supply working fluid at sufficient pressure to the power assist device to allow the power assist device to function well even when the pump discharge pressure is lowered to reduce energy loss in the active suspension. The object of the present invention is to provide a working fluid supply device for use in the present invention.

[0007]

[Means for Solving the Problems] According to the present invention, the above object is to provide a variable discharge pressure pump, a first working fluid supply passage that communicates and connects the pump and an active suspension, and a a second working fluid supply passage that communicates with the assist device; and a pressure increaser that is provided in the middle of the second working fluid supply passage and selectively increases the pressure of the working fluid flowing in the second working fluid supply passage. and a control device that controls the discharge pressure of the pump and the operation of the pressure booster, and the control device operates the pressure booster when the discharge pressure of the pump is set low, and controls the pressure booster of the pump. This is achieved by a working fluid supply device for a vehicle, characterized in that the pressure increase device is not operated when the discharge pressure is set high.

[0008]

[Operation] According to the above-described configuration, a pressure booster that selectively operates is provided upstream of the power assist device, and when the pump discharge pressure is set low, the pressure booster is operated and the pump discharge pressure increases. When the pressure is set high, the pressure intensifier is not activated. Therefore, for example, when the vehicle is stationary or running at very low speeds when the active suspension does not need to be operated as much, energy loss in the active suspension can be reduced by lowering the pump discharge pressure. Since the working fluid with sufficient pressure increased by the pressure device is supplied, the power assist device can be operated satisfactorily.

The invention will now be described in detail by way of example with reference to the accompanying drawings.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing one embodiment of a working fluid supply device for a vehicle according to the present invention.

In FIG. 1, reference numeral 10 indicates a reservoir for storing oil as a working fluid. One end of a connection passage 12 and one end of a working fluid discharge passage 14 are connected to the reservoir 10 . The other end of the connecting passage 12 is a variable discharge pressure pump 16 driven by an engine (not shown).
connected to the suction side of the In the illustrated embodiment, the pump 16 is capable of changing the discharge pressure in two stages, "high" and "low", as will be described later, and a first working fluid supply passage 18 is provided on the discharge side of the pump 16. is connected at one end. An attenuator (not shown in the figure) is provided in the middle of the working fluid supply passage 18 to absorb pressure pulsations of the working fluid discharged from the pump and reduce pressure changes. is connected to an accumulator 20 which acts to accumulate pressure.

The other ends of the working fluid supply passage 18 and the working fluid discharge passage 14 are connected to a hydraulic active suspension 22, which is indicated by a block in the figure. The hydraulic active suspension 22 itself is well known in the art and does not constitute the gist of the present invention, so a detailed explanation thereof will be omitted, but the explanation will be given to the actuators provided corresponding to each wheel. Any structure may be used as long as the supply and discharge of the working fluid is controlled by a control valve and the fluid pressure within the actuator is controlled to increase or decrease, thereby increasing or decreasing the vehicle height of the corresponding portion.

A second working fluid supply passage 24 is provided in the middle of the working fluid supply passage 18 and the working fluid discharge passage 14, respectively.
and a second working fluid discharge passage 26 are connected to each other, and the other ends of these passages are connected to a power steering device 28 as a power assist device. The power steering device is also well known in the technical field and does not form the gist of the present invention, so a detailed explanation thereof will be omitted, but the supply and discharge of working fluid to and from the power cylinder is controlled by a control valve. Any structure may be used as long as it is configured to generate an assist force for driving a steering member such as a rack bar.

A pressure increase device 30 is provided in the middle of the second working fluid supply passage 24. The pressure booster 30 is connected to the passage 24
a pressure booster circuit 32 such as a plunger pump that increases the pressure of the working fluid flowing therein; a bypass passage 34 that extends around the pressure booster circuit 32 and is connected to the passage 24 at both ends;
It consists of a bypass valve 36 provided in the middle of the bypass passage. In the illustrated embodiment, the bypass valve 36 is a normally closed electromagnetic on-off valve, and opens to communicate with the bypass passage when a control signal is supplied to the solenoid 36A.

As will be described later, the pressure booster 30 includes a pressure boost circuit 32.
is operated and the bypass valve 36 is maintained in the closed state, and the operation state of the pressure increase circuit 32 is stopped and the bypass valve 36 is maintained in the closed state.
The valve is selectively switched between a non-operating state in which the valve is opened and a non-operating state.

FIG. 2 is a schematic diagram showing an example of the variable discharge pressure pump 16. As shown in FIG. In FIG. 2, 38 indicates a housing, which supports the pump body 40 rotatably around an axis 42. The main body 40 is rotated around an axis 42 via a shaft 46 by rotation of a pulley 44 by an engine (not shown).

The main body 40 includes a plurality of plungers 50 that are supported so as to be reciprocated along the axis 42 and have one end in sliding contact with an annular plate-shaped swash plate 48. Although not shown in detail in FIG. 2, when each plunger 50 rotates around the axis 42 together with the main body 40, it is reciprocated by the swash plate 48, thereby sucking working fluid from the suction port 52, and causing high pressure operation. The fluid is discharged to the discharge port 54.

The swash plate 48 is pivotally supported by the housing 38 by a pair of pivot shafts 56 fixed to its periphery at radially opposed positions, and is moved to the maximum tilted position shown by a compression coil spring 58. energized. A cylinder device 60 is provided on the side of the pivot shaft 56 that is radially opposite to the spring 58 . When the pressure in the cylinder chamber 62 is increased, the cylinder device 60 expands and presses the lower end of the swash plate, thereby reducing its angle of inclination. The cylinder device 60 is the housing 38
It consists of a piston 64 fixed to the piston and a cylinder 66 fitted into the piston, and the cylinder 66 is biased to the right in the figure by a compression coil spring not shown in the figure.

The pressure within the cylinder chamber 62 of the cylinder device 60 is controlled by a pilot type on-off valve 68. The on-off valve 68 is provided in the middle of a passage 70 that communicates and connects the cylinder chamber 66 and the discharge port 54, and takes in the pressure Pp in the passage 70 upstream of the on-off valve as a pilot pressure, and the pilot pressure Pp is applied to the spring 7.
When the pilot pressure Pp is higher than the spring force of the spring 72, the valve is maintained at the closed position shown, and when the pilot pressure Pp is lower than the spring force of the spring 72, the valve is opened to communicate with the passage 70.

The spring force of the spring 72 is controlled by a spring force adjusting cylinder device 74. The cylinder device 74 includes a piston 78 fixed to the vehicle body 76 and a cylinder 80 that fits into the piston.
is mounted between the cylinder 80 and a plunger (not shown) of the on-off valve 68.

A cylinder chamber 82 of the cylinder device 74 is connected to a port c of a control valve 84 through a passage 83. The control valve 84 is a three-port, two-position switching type control valve, and its port s is communicatively connected to the passage 70 through a passage 86 , and the port d is communicatively connected to the reservoir 10 through a passage 88 . Further, when the solenoid 84A is not energized, the control valve 84 shuts off the port s and connects ports c and d, and when the solenoid 84A is energized, it shuts off the port d and connects the port s.
and c are interconnected.

Pressure booster 32, bypass valve 36, pump 1
The control valve 84 of No. 6 is controlled by an electronic control device 90 shown in FIG. Electronic control unit 90 includes a microcomputer 92 as shown in FIG. The microcomputer 92 may have a general configuration as shown in FIG. 3, and includes a central processing unit (CPU) 94 and a read-only memory (ROM).
96, a random access memory (RAM) 98, an input port device 100, and an output port device 102, which are connected to each other by a bidirectional common bus 104.

In the illustrated embodiment, the input port device 1
00 receives a signal indicating the vehicle speed V from the vehicle speed sensor 106. The input port device 100 appropriately processes the signals input thereto, and according to instructions from the CPU 94 based on the program stored in the ROM 96, outputs the
The processed signal is output to the PU and RAM98. The ROM 96 stores the control program shown in FIG. The CPU 94 processes signals as described later based on the control program shown in FIG. The output port device 102 is connected to the pressure booster 3 via drive circuits 108 to 112, respectively, according to instructions from the CPU 94.
0, a control signal is output to the solenoid 36A of the bypass valve 36 and the solenoid 84A of the control valve 84 of the pump 16.

The operation of the illustrated embodiment will now be described with reference to the flowchart shown in FIG.

The control according to the flowchart shown in FIG. 4 is started by closing an ignition switch (not shown). Further, in FIG. 4, the flag F indicates whether the pump discharge pressure is set to "low" and the pressure booster 30 is activated, and flag 1 indicates whether the pump discharge pressure is set to "high". This indicates that the operation of the pressure increase device 30 is stopped.

In the first step 10, the flag F is reset to 0, and then the process proceeds to step 20.

In step 20, the vehicle speed sensor 106
The detected vehicle speed V is read, and the process then proceeds to step 30.

In step 30, it is determined whether the flag F is 0 or not, and when it is determined that F=0, the process advances to step 80, where it is determined that F=0. When the determination has been made, the process advances to step 40.

In step 40, the vehicle speed V is set to the reference value V.
1 (for example, 15 km/h), and when it is determined that V>V1 is not true, the process returns to step 20, and when it is determined that V>V1. Proceed to step 50.

In step 50, the operation of the pressure increaser 30 is stopped, that is, the bypass valve 36 is opened and the operation of the pressure increase circuit 32 is stopped, and then step 60
Proceed to.

In this step, if the bypass valve is already open and the pressure increase circuit is not activated, it remains in that state.

[0032] In step 60, the discharge pressure of the pump 16 is set to "high", and the process then proceeds to step 70.

[0033] Also in this step, if the pump discharge pressure has already been set to "high", it is maintained in that state.

At step 70, flag F is set to 1, and then the process returns to step 20.

In step 80, the vehicle speed V is set to the reference value V.
2 (for example, 10 km/h, V2 < V1), and when it is determined that V<V2 is not the case, the process returns to step 20 and V<V
2, the process advances to step 90.

In step 90, the discharge pressure of the pump 16 is set to "low", and then the process proceeds to step 100.

In step 100, the pressure increase device 30 is activated, that is, the bypass valve 36 is closed and the pressure increase circuit 32 is activated, and then the process proceeds to step 110.

At step 110, flag F is reset to 0, and then the process returns to step 20.

Thus, according to this embodiment, step 8
0, it is determined whether or not the vehicle speed V is less than the reference value V2, and the vehicle speed V is less than the reference value V2, such as when the vehicle is stopped or running at a very low speed, and therefore the active suspension 22 is not operated as much. When it is determined that there is no need to increase the pressure, the discharge pressure of the pump 16 is set to "low" in step 90, and the bypass valve 36 is closed and the pressure increase circuit 32 is closed in step 100. The actuation activates the pressure booster 30, thereby reducing the energy loss due to the flow of high pressure working fluid into the pilot pressure forming part of the control valve of the active suspension 22, and also reduces the energy loss caused by the flow of high pressure working fluid into the pilot pressure forming part of the control valve of the active suspension 22. The pressurized working fluid at sufficient pressure is supplied to the control valve of the power steering device 68 .

Also according to the illustrated embodiment, step 40
When it is determined that the vehicle speed V exceeds the reference value V1, the bypass valve 36 is opened in step 50 and the operation of the pressure booster circuit 32 is stopped, thereby reducing the pressure booster 30. The operation of the pump 16 is stopped, and the discharge pressure of the pump 16 is set to "high" in step 60. However, since the reference values V1 and V2 are set to V1 > V2, the vehicle speed is around these vehicle speeds. When the vehicle is traveling in a city, the working fluid supply device can be operated stably by avoiding frequent switching between activation and deactivation of the pump discharge pressure and the pressure increase device.

In the above embodiment, the discharge pressure of the pump 16 is controlled in two stages, high and low.
It may be controlled in a multi-step or stepless manner, and in that case, it is preferable that the pressure booster circuit is also controlled in a multi-step or stepless manner.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to such embodiments, and various other embodiments may be made within the scope of the present invention. It will be obvious to those skilled in the art that this is possible.

[0043]

As is clear from the above description, according to the present invention, a selectively activated pressure increaser is provided upstream of the power assist device, and when the pump discharge pressure is set low, the pressure increaser increases the pressure when the pump discharge pressure is set low. When the pressure device is activated and the discharge pressure of the pump is set high, the pressure increase device is not activated. Therefore, for example, when the vehicle is stationary or running at very low speeds when the active suspension does not need to be operated as much, energy loss in the active suspension can be reduced by lowering the pump discharge pressure. Since the working fluid with sufficient pressure increased by the pressure device is supplied, the power assist device can be operated satisfactorily even if the discharge pressure of the pump is low.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of a working fluid supply device for a vehicle according to the present invention.

FIG. 2 is a schematic configuration diagram showing an example of the variable discharge pressure pump shown in FIG. 1;

FIG. 3 is a block diagram showing an electronic control device that controls the variable discharge pressure pump, pressure booster, and bypass valve shown in FIG. 1;

FIG. 4 is a flowchart showing a control flow achieved by the electronic control device shown in FIG. 3; 10... Reservoir 16... Variable discharge pressure pump 18... First working fluid supply passage 22... Active suspension 24... Second working fluid supply passage 28... Power steering device 30... Pressure booster 32... Pressure booster circuit 36... Bypass valve

Claims (1)

[Claims] a variable discharge pressure pump; a first working fluid supply passage that communicates with the pump and the active suspension; a second working fluid supply passage that communicates with the pump and the power assist device; a pressure increasing device provided in the middle of the fluid supply passage and selectively increasing the pressure of the working fluid flowing in the second working fluid supply passage; and a control device controlling the discharge pressure of the pump and the operation of the pressure increasing device. and the control device is configured to operate the pressure increase device when the discharge pressure of the pump is set low, and not to operate the pressure increase device when the discharge pressure of the pump is set high. Features of a working fluid supply device for vehicles.