JPH04321417A - Working fluid supply device for fluid pressure type suspension - Google Patents

Abstract

PURPOSE:To satisfactorily operate a power assist device by supplying working fluid at a sufficiently high pressure into the power assist device even upon start of operation of a fluid pressure type suspension. CONSTITUTION:A working fluid supply device 40 for a suspension comprises a control valve 42 for controlling the supply and discharge of working fluid to and from an actuator 56, and a shut-off valve 66 disposed in a supply passage and in a discharge passage 52 and adapted to be opened when the pressure in the supply passage 36 upstream of the control valve becomes higher than a predetermined value. There are provided a working fluid source 18 and a supply pressure control valve 26 which is disposed in a supply passage 20 between the control valve or the shut-off valve and the source. The power assist device 68 is connected to the supply passage, upstream from the control valve 26.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention relates to a hydraulic suspension for vehicles such as automobiles, and more particularly to a hydraulic suspension configured to supply high-pressure working fluid to a power assist device such as a power steering device. It relates to a suspension working fluid supply device.

0002

BACKGROUND ART As one type of hydraulic suspension for vehicles such as automobiles, for example, as described in Japanese Patent Application Laid-Open No. 2-274607 filed by the same applicant as the present applicant, there is a system that supports each wheel. an actuator that increases or decreases the vehicle height of a corresponding portion by supplying and discharging a working fluid to and from a working fluid chamber; a working fluid supply passage that communicates and connects a working fluid supply source and the working fluid chamber; a working fluid discharge passage that communicates and connects the fluid chamber and the working fluid recovery means; a control valve that is provided in the middle of the working fluid supply passage and the working fluid discharge passage and controls the supply and discharge of the working fluid to and from the working fluid chamber; The valve is provided in the middle of the working fluid supply passage and the working fluid discharge passage, and is configured to open when the pressure in the working fluid supply passage is equal to or higher than the valve opening pressure, and close when the pressure within the working fluid supply passage is equal to or lower than the valve closing pressure. Hydraulic suspensions with pilot-operated isolation valves are already known.

[0003] When the operation of such a hydraulic suspension is started, the shut-off valve is suddenly opened with a substantial difference in pressure in the passages on both sides of the shut-off valve when the shut-off valve is opened. When the valve is closed, a relatively large amount of working fluid flows past the shut-off valve at the same time as the shut-off valve opens, causing a temporary change in vehicle height. Therefore, in a conventional suspension incorporating a pilot-operated shutoff valve as described above, a bypass valve is provided between the working fluid supply passage and the working fluid discharge passage, and the bypass valve is activated when the hydraulic suspension starts operating. By gradually closing the valve, the pressure within the working fluid supply passage is slowly increased to gradually open the shutoff valve.

0004

[Problems to be Solved by the Invention] However, when the working fluid supply source of a hydraulic suspension is shared as a working fluid supply source of a power assist device such as a power steering device or a power assist brake device, At the start of operation, the pressure in the working fluid supply passage is suppressed to a low value by operating the bypass valve, so working fluid of sufficient pressure cannot be supplied to the power assist device, so that the power assist device functions well. The problem is that I can't.

[0005] The present invention solves the above-mentioned problems when the working fluid supply source of a conventional hydraulic suspension incorporating a pilot-operated shutoff valve is shared as a working fluid supply source of a power assist device. In view of the above problems, a working fluid supply device for a hydraulic suspension is improved so that the power assist device can function satisfactorily by supplying working fluid of sufficient pressure to the power assist device even when the hydraulic suspension starts operating. is intended to provide.

[0006]

[Means for Solving the Problems] According to the present invention, the above-mentioned object is achieved by supplying and discharging a working fluid to a working fluid chamber provided corresponding to each wheel, thereby increasing the vehicle height of the corresponding portion. An actuator that increases or decreases, a working fluid supply passage that communicates with the working fluid chamber at one end, a working fluid discharge passage that communicates with the working fluid chamber at one end, and an intermediate portion of the working fluid supply passage and the working fluid discharge passage. a control valve provided in the working fluid chamber for controlling the supply and discharge of the working fluid to the working fluid chamber; and a control valve provided in the working fluid supply passageway upstream of the control valve and provided in the middle of the working fluid supply passageway and the working fluid discharge passageway. A working fluid supply device for a hydraulic suspension having a shutoff valve configured to respond to pressure and open when the pressure is equal to or higher than a predetermined value, the working fluid supply being connected to the other end of the working fluid supply passage. a supply pressure control means provided in the middle of the working fluid supply passage between the control valve, the shutoff valve, and the working fluid supply source to control downstream pressure; The supply passage is achieved by a hydraulic suspension working fluid supply device connected to the power assist device between the working fluid supply source and the supply pressure control means.

[0007]

[Operation] According to the above structure, the supply pressure control means is provided in the middle of the working fluid supply passage between the control valve, the shutoff valve, and the working fluid supply source, and is configured to control the pressure on the downstream side thereof. The power assist device is connected to the working fluid supply passage between the working fluid supply source and the supply pressure control means.

Therefore, by relatively rapidly increasing the pressure in the working fluid supply passage upstream of the supply pressure control means by the working fluid supply source at the start of suspension operation, power assist can be achieved substantially from the beginning of suspension operation. It is now possible to supply sufficient pressure working fluid to the device to ensure the power assist device operates well.
Moreover, even if the pressure in the working fluid supply passage upstream of the supply pressure control means increases relatively rapidly, the pressure in the working fluid supply passage downstream of the control means is gradually increased by the supply pressure control means. By gradually opening the shutoff valve, a relatively large amount of working fluid flows through the shutoff valve when the shutoff valve is opened, and a temporary change in vehicle height caused by this is reliably prevented. becomes possible.

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 an embodiment of a working fluid supply device according to the present invention together with a hydraulic suspension.

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 connected to the suction side of a pump 18 driven by an engine 16. Pump 18 is a variable displacement pump in the illustrated embodiment, and one end of working fluid supply passage 20 is connected to its discharge side. An attenuator 22 is provided in the middle of the working fluid supply passage 20 to absorb pressure pulsations of the working fluid discharged from the pump and reduce pressure changes, and an accumulator 22 is provided in the working fluid supply passage 20 to accumulate pressure. 24 are connected.

The other end of the working fluid supply passage 20 is connected to a pilot-operated pressure control valve 26 as supply pressure control means.
It is communicatively connected to the P port of a three-position switching control valve 28. The pressure control valve 26 includes a switching control valve 28;
It consists of a connecting passage 30 that communicates and connects the working fluid supply passage 20 and the working fluid discharge passage 14, and a fixed throttle 32 and a variable throttle 34 provided in the middle of the passage.

One end of a working fluid supply passage 36 is connected to the A port of the switching control valve 28. Also, the switching control valve 2
One end of a working fluid discharge passage 15 is connected to the R port 8, and the other end of the passage is connected to the working fluid discharge passage 14. The switching control valve 28 is a spool valve that takes in the pressure Pp in the passage 30 between the fixed throttle 32 and the variable throttle 34 and Pa in the working fluid supply passage 36 as pilot pressure, and when the pressure Pp is higher than the pressure Pa, Switching position 28a that communicates and connects port P and port A
When the pressures Pp and Pa are equal to each other, the switching position 28b switches to the switching position 28b where all ports are cut off, and when Pp is lower than the pressure Pa, the port R is switched to the switching position 28b.
and port A are switched to a switching position 28c for communicating and connecting them. Further, the variable throttle 34 changes the effective passage cross-sectional area of the throttle by controlling the current applied to its solenoid, thereby changing the pressure Pp in cooperation with the fixed throttle 32.

Thus, the reservoir 10, the pump 18, the accumulator 24, and the pressure control valve 26 are connected to the working fluid supply passage 3.
A working fluid supply device 40 is configured to supply high-pressure working fluid to 6 and control the pressure thereof.

The other end of the working fluid supply passage 36 and the other end of the working fluid discharge passage 14 communicate with the P port and the R port of a pilot-operated 3-port 3-position switching control valve 44 of the pressure control valve 42, respectively. It is connected. The pressure control valve 42 includes a switching control valve 44, a connection passage 46 that communicates with the working fluid supply passage 36 and the reservoir 10, and a fixed throttle 48 and a variable throttle 50 provided in the middle of the passage.

A connection passage 5 is connected to the A port of the switching control valve 44.
2 are connected. The switching control valve 44 is a spool valve that takes in the pressure Pr in the passage 46 between the fixed throttle 48 and the variable throttle 50 and Pb in the connecting passage 52 as pilot pressure, and when the pressure Pr is higher than the pressure Pb, the port P and port A are connected to each other at switching position 44a.
and a switching position 44b in which communication between all ports is cut off when the pressures Pr and Pb are equal to each other.
When the pressure Pr is lower than the pressure Pb, the pressure is switched to a switching position 44c in which port R and port A are connected in communication. Further, the variable throttle 50 changes the effective passage cross-sectional area of the throttle by controlling the current applied to its solenoid, thereby changing the pressure Pr in cooperation with the fixed throttle 48.

The other end of the connecting passage 52 is connected to a working fluid chamber 58 of an actuator 56 provided corresponding to the wheel. As shown in the figure, the actuator 56 is a type of cylinder-piston device, and although not shown in the figure, it is disposed between a suspension member that supports the wheels and the vehicle body, and supplies and discharges working fluid to and from the working fluid chamber 58. By doing so, the vehicle height of the corresponding area can be increased or decreased. A gas-liquid spring device 62 is connected to the working fluid chamber 58 via a passage 60.
are connected to each other, and a throttle 64 is provided in the middle of the passage 60. The gas-liquid spring device 62 thus acts as a suspension spring or an auxiliary suspension spring, and the throttle 64 is adapted to generate a damping force.

A shutoff valve 66 is provided in the middle of the connection passage 52. The shutoff valve 66 takes in the pressure Pc (=Pa) in the working fluid supply passage 36, and controls the pilot pressure Pc.
The valve is configured to open when the pilot pressure exceeds a predetermined valve-opening value, and to close when the pilot pressure falls below a predetermined valve-closing value.

Furthermore, the pressure control valve 42, the connection passage 52, and the throttle 5
4, shutoff valve 66, actuator 56, gas-liquid spring device 6
The second class is provided corresponding to each wheel. Also, the variable throttle 34 of the pressure control valve 26 and the variable throttle 5 of the pressure control valve 42
0 is controlled by an electronic control device not shown in the figure.

A power steering device 68 as a power assist device is provided between the working fluid supply passage 20 and the working fluid discharge passage 14, so that the high pressure working fluid in the working fluid supply passage 20 is transferred to the power steering device 68. It is designed to be supplied to the control valve.

When the illustrated embodiment starts operating, the electronic control device (not shown) starts driving the pump 18 with the effective passage cross-sectional area of the variable throttle 34 of the pressure control valve 26 set to a large value. Ru. In this case, the pressure drop due to the fixed throttle 32 is large and the pilot pressure Pp of the switching control valve 28 is maintained at a low value, so the switching control valve 28 is maintained at the switching position 28c, and the pressure Pc in the working fluid supply passage 36 is maintained at a low value. It is maintained at a low value to maintain the shutoff valve 66 in a closed state.

When the pump 18 continues to be driven in this state, the pressure Ps in the working fluid supply passage 20 rises relatively rapidly to a predetermined pressure P0 as shown in FIG. 2, and thereafter the pressure Pb is substantially this predetermined pressure P0
is maintained at a constant value.

Further, the effective passage cross-sectional area of the variable restrictor 34 of the pressure control valve 26 is gradually reduced by an electronic control device (not shown) at the same time as the start of operation, thereby reducing the pressure controlled by the pressure control valve 26. That is, the pressure Pc within the working fluid supply passage 36 also increases gradually. In this case, the shutoff valve 6
Let the pressure Pc in the working fluid supply passage 36 when the valve 6 starts to open be the pressure P1, and the pressure Pc when the shutoff valve becomes fully open be the pressure P2. The valve gradually opens in the process of gradually rising between

Therefore, according to the illustrated embodiment, by relatively rapidly increasing the pressure Ps in the working fluid supply passage 20, a sufficient pressure of working fluid is supplied to the power assist device 68 substantially from the beginning of suspension operation. Moreover, by gradually increasing the pressure in the working fluid supply passage 36 by the pressure control valve 26, the isolation valve 66 is gradually opened, thereby causing a relatively large amount of actuation when the isolation valve is opened. Temporary changes in vehicle height caused by fluid flowing through the cutoff valve can be reliably prevented.

The pressure Pc in the working fluid supply passage 36 is controlled by the pressure control valve 26, as shown by the broken line in FIG. The pressure may be increased gradually between the pressure P2 and the pressure may be increased relatively rapidly again when the pressure exceeds the pressure P2. When the pressure Pc is controlled in such a manner,
Compared to the case where the pressure Pc is controlled as shown by the solid line in FIG. 2, the shutoff valve 66 can be opened relatively early and the suspension can be brought into a functional state earlier. .

In the above embodiment, the supply pressure control means of the working fluid supply device and the control valve of the suspension are pressure control valves, but these means may also be flow rate control valves.

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.

[0028]

As is clear from the above description, according to the present invention, the pressure in the working fluid supply passage upstream of the supply pressure control means is relatively rapidly increased by the working fluid supply source when the suspension starts operating. By raising the
Substantially from the beginning of the operation of the suspension, sufficient pressure working fluid can be supplied to the power assist device to ensure good operation of the power assist device. Even if the pressure increases relatively rapidly, the supply pressure control means gradually increases the pressure in the working fluid supply passage downstream of the control means, thereby gradually opening the cutoff valve. It is possible to reliably prevent a relatively large amount of working fluid from flowing through the shutoff valve when the valve is opened, and a temporary change in vehicle height caused by this.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a working fluid supply device according to the present invention together with a hydraulic suspension.

FIG. 2 is a graph showing changes in pressure within the working fluid supply passage at the start of operation of the embodiment. 10... Reservoir 16... Engine 18... Pump 20... Working fluid supply passage 26... Pressure control valve 36... Working fluid supply passage 40... Working fluid supply device 42... Pressure control valve 56... Actuator 58... Working fluid chamber 52... Gas-liquid spring Device 54... Throttle 66... Shutoff valve 68... Power steering device

Claims (1)

[Claims] an actuator that is provided corresponding to each wheel and increases or decreases the vehicle height of the corresponding portion by supplying and discharging a working fluid to and from a working fluid chamber; and a working fluid supply passage that communicates with the working fluid chamber at one end; a working fluid discharge passage communicating with the working fluid chamber at one end; a control valve provided in the middle of the working fluid supply passage and the working fluid discharge passage to control supply and discharge of working fluid to the working fluid chamber; A shutoff valve is provided in the middle of the working fluid supply passage and the working fluid discharge passage, and is configured to respond to the pressure in the working fluid supply passage upstream of the control valve and open when the pressure is equal to or higher than a predetermined value. A working fluid supply device for a hydraulic suspension, comprising: a working fluid supply source connected to the other end of the working fluid supply passage; and between the control valve, the shutoff valve, and the working fluid supply source. supply pressure control means provided in the middle of the working fluid supply passage to control pressure on the downstream side; A hydraulic suspension working fluid supply device connected to the device.