JPH02182527A - Fluid pressure type suspension - Google Patents

Abstract

PURPOSE:To make it possible to effectively recover the energy possessed by high pressure working fluid by so constructing to open a relief means and to guide the working fluid to a supply passage when the pressure inside a connecting passage leading to an actuator in a suspension exceeds a specified value. CONSTITUTION:An actuator 58 in a suspension is connected between a suspension arm and a car body, and a working fluid chamber 62 formed by a piston 64 is connected to a pump 14 through a connecting passage 54, a pressure control valve 18, a working fluid supply passage 167, etc. It is also connected to an accumulator 24 through a throttle 74. In this case, the connecting passage 54 and the working fluid supply passage 16 are mutually communicated and connected with a return passage 78, and a relief valve 80 is installed halfway of the return passage 78. The relief valve 80 is set to be opened when the pressure inside the connecting passage 54 exceeds a specified set pressure. With the opening of the valve, part of the working fluid in the connecting passage 54 is introduced into the working fluid supply passage 16.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to suspensions for vehicles such as automobiles, and more particularly to hydraulic suspensions.

BACKGROUND OF THE INVENTION Hydraulic suspensions for vehicles such as automobiles generally include a working fluid supply passage, a working fluid discharge passage, and a hydraulic actuator disposed between a wheel and a vehicle body.
It has a connecting passage that communicates with the actuator, and a pressure control valve that selectively connects the working fluid supply passage means or the working fluid discharge passage to the connecting passage and controls the pressure in the connecting passage.

In such a hydraulic suspension, when severe and rapid turning or acceleration/deceleration is performed, the pressure inside the actuator and the accumulator connected to it becomes extremely high, so it is necessary to protect the actuator and accumulator from high pressure. It is.

In order to achieve this purpose, for example, Utility Model Application No. 63-8170
As described in Publication No. 7, a return passage that communicates and connects the connection passage and the working fluid discharge passage, and a relief valve that is provided in the middle of the return passage and opens when the pressure in the connection passage exceeds a predetermined value. is conventionally provided, and when the pressure in the connection passage exceeds a predetermined value, a relief valve opens and a portion of the working fluid in the connection passage is discharged to the discharge passage.

Problems to be Solved by the Invention In such conventional hydraulic suspensions, when the pressure in the connecting passage exceeds a predetermined value, the relief valve opens and a portion of the working fluid in the connecting passage is discharged into the working fluid discharge passage. As a result, the energy held by the high-pressure working fluid is wasted, resulting in a problem of deterioration of fuel efficiency.

Furthermore, if the pressure in the connection passage exceeds the upper limit of the control pressure range of the pressure control valve even if the pressure in the connection passage does not rise to the opening pressure of the relief valve, the pressure control valve connects the connection passage and the working fluid discharge passage, As a result, a portion of the working fluid in the connecting passage is discharged to the working fluid discharge passage through the pressure control valve. Therefore, when the vehicle turns or accelerates or decelerates relatively rapidly, the roll of the vehicle body increases relatively rapidly when the pressure in the connecting passage exceeds the upper limit of the control pressure range of the pressure control valve. There's a problem.

In view of the above-mentioned problems with conventional hydraulic suspensions, the present invention eliminates wasteful consumption of energy and allows the pressure in the connecting passage to be reduced to a pressure control valve by relatively rapid turning and acceleration/deceleration. An object of the present invention is to provide a hydraulic suspension that is improved so that the roll of the vehicle body does not increase relatively rapidly even when the upper limit of the control pressure range is reached.

Means for Solving the Problems According to the present invention, a working fluid supply passage having an accumulator, a working fluid discharge passage, a fluid pressure actuator disposed between a wheel and a vehicle body, a connection passage that communicates with the actuator; a pressure control valve that selectively communicates and connects the working fluid supply passage or the working fluid discharge passage with the connecting passage and controls the pressure in the connecting passage; and the connecting passage. This is achieved by a hydraulic suspension having relief means that connects the connection passage and the working fluid supply passage to guide the working fluid from the connection passage to the working fluid supply passage when the internal pressure exceeds a predetermined value. .

Effects and Effects of the Invention According to the above configuration, when the pressure in the connection passage exceeds a predetermined value, the relief connects the connection passage and the working fluid supply passage and guides the working fluid from the connection passage to the working fluid supply passage. Means is provided so that when the pressure in the connecting passage exceeds a predetermined value, a portion of the working fluid in the connecting passage is directed to the working fluid supply passage rather than to the working fluid discharge passage, whereby the high pressure working fluid is The retained energy is effectively recovered.

In addition, in the above configuration, the pressure in the connecting passage at which the relief means starts to function, that is, the predetermined value, is set to a value that is substantially the same as the upper limit of the control pressure range of the pressure control valve, or a pressure that is slightly lower than this. By setting this, the connecting passage and the working fluid supply passage are connected to each other when the pressure in the connecting passage exceeds a predetermined value, so the connecting passage and the working fluid discharge passage are connected to each other by the pressure control valve. This prevents a part of the working fluid in the connecting passage from being discharged to the working fluid discharge passage, and as a result, the pressure in the connecting passage is reduced even when the vehicle makes a relatively rapid turn or accelerates or decelerates. When the pressure exceeds the upper limit of the control pressure range of the pressure control valve, it is possible to reliably prevent the roll of the vehicle body from increasing relatively rapidly.

According to one embodiment of the present invention, the relief means is provided in a return passage that communicates with the connection passage and the working fluid supply passage, and is provided in the middle of the return passage and opens when the pressure in the connection passage exceeds a predetermined value. It consists of a relief valve that operates, and a check valve that is provided in the middle of the return passage and allows only the flow of working fluid from the connecting passage to the working fluid supply passage, and the relief valve and the check valve are configured as one valve. It is preferable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures.

Embodiment FIG. 1 is a schematic diagram showing an embodiment of a hydraulic suspension according to the present invention.

In the figure, 10 indicates a reserve tank that stores oil as a working fluid, and this reserve tank is connected to the flow path 1.
2 to the pump 14. One end of a working fluid supply passage 16 is connected to the pump 14, so that the pump 14 pumps up working fluid from the reserve tank 10 through the flow passage 12 and supplies high-pressure working fluid to the working fluid supply passage 16. It has become. The other end of the working fluid supply passage 16 is connected to a pressure control valve 18 .

In the middle of the working fluid supply passage 16, there is an attenuator 20 that absorbs the pressure pulsation of the working fluid discharged from the pump and reduces the pressure change, and a check valve that only allows the working fluid to flow from the pump toward the pressure control valve 18. 22 are provided. Further, an accumulator 24 is connected to the working fluid supply passage 16 at a position downstream from the check valve 22.
The accumulator has high pressure gas sealed therein so as to absorb pressure pulsations of the working fluid and perform a pressure accumulating function.

Attenuator 20 and check valve 2 of working fluid supply passage 16
2 is connected at one end by a passage 26 to a working fluid discharge passage 28 which communicates with the reserve tank 10. A relief valve 30 is provided in the middle of the passage 26, and the relief valve opens when the pressure of the working fluid in the working fluid supply passage 16 is equal to or higher than a predetermined value. The pressure of the working fluid in the working fluid supply passage 16 is thereby prevented from rising above a predetermined value.

Further, a portion of the working fluid supply passage 16 downstream of the check valve 22 is connected to the working fluid discharge passage 28 through passages 32 and 34 . In the middle of the passage 32, a throttle 36 and a normally open electromagnetic on-off valve 38 capable of adjusting the flow rate are provided. The electromagnetic on-off valve 38 can adjust the flow rate of the working fluid passing through the valve by changing the excitation current supplied to the solenoid 40, and can close the valve as necessary. Further, a pilot-operated on-off valve 42 is provided in the middle of the passage 34. The on-off valve 42 is a throttle 36
When there is no differential pressure on both sides of the throttle 36, the valve is maintained at the closed position 42a, and when the pressure on the upstream side of the throttle 36, that is, on the working fluid supply passage side, is high, the valve is moved to the open position 42b. It is designed to switch. Thus, the throttle 36, the electromagnetic on-off valve 38, and the on-off valve 42 cooperate with each other to selectively communicate and connect the working fluid supply passage 16 and the working fluid discharge passage 28 to control the pressure within the working fluid supply passage 16. It constitutes a bypass valve 44.

As shown, the pressure control valve 18 is a switching control valve 46,
It consists of a passage 48 that communicates and connects the working fluid supply passage 16 and the working fluid discharge passage 28, and a fixed throttle 50 and a variable throttle 52 provided in the middle of the passage. The other end of the working fluid supply passage 16 is connected to the P boat of the switching control valve 46, the other end of the working fluid discharge passage 28 is connected to the R boat, and one end of the connecting passage 54 is connected to the A boat. ing.

The switching control valve 46 controls the pressure Pp in the passage 48 between the fixed throttle 50 and the variable throttle 52 and the pressure Pa in the connecting passage 54.
It is a spool valve that takes in as pilot pressure, and when the sum of pressure Pp and spring force F of spring 47 is higher than Pa, switching position 4 connects P boat and A boat for communication.
6a, and when the sum of the pressure Pp and the spring force F and Pa are substantially equal to each other, the switch switches to the switching position 46b where communication with all boats is cut off, and the sum of the pressure LPp and the spring force F is When the pressure is lower than Pa, the switch is switched to a switching position 46c where boat R and boat A are connected in communication. Further, the variable throttle 52 changes the effective passage cross-sectional area of the throttle by controlling the current applied to the solenoid 56, thereby changing the pressure Pp in cooperation with the fixed throttle 50.

The other end of the connection passage 54 is connected to an actuator 58. In the illustrated embodiment, the actuator 58 comprises a cylinder 60 and a piston 64 that fits within the cylinder and cooperates with the cylinder to define a working fluid chamber 62; The piston is connected to a suspension arm (not shown), and the tip of the piston rod is connected to the vehicle body (not shown). Further, a suspension spring 70 is elastically mounted between an upper seat 66 fixed to the rod portion of the piston and a lower seat 68 fixed to the cylinder. As shown, the piston 6
4 is provided with a passage 72 which communicates with the working fluid chamber 62 at one end and with the other end of the connection passage 54 at the other end. Further, an accumulator 76 is connected to the working fluid chamber 62 via a throttle 74 .

Furthermore, the connection passage 54 and the working fluid supply passage 16 are connected to each other by a return passage 78, and a relief valve 80 is provided in the middle of the return passage. In contrast, the relief valve 80 takes in the pressure in the return passage 78 on the side of the connection passage 54, and therefore the pressure Pa in the connection passage 54, as a pilot pressure, and this pressure is set to a predetermined set pressure Pr.
When it exceeds 1, the valve opens to allow the flow of working fluid from the connection passage 54 toward the working fluid supply passage 16.

Thus, the return passage 78 and the relief valve 80 cooperate with each other to constitute a relief device 82 that guides a portion of the working fluid in the connecting passage 54 to the working fluid supply passage 16 when the pressure Pa exceeds the set pressure Pr. .

In this case, the set pressure Pr of the relief valve 80 is the pressure control valve 1
It is preferable that the set pressure P is substantially the same as or lower than the upper limit ph of the control pressure range 8, and in the illustrated embodiment, the set pressure P is set to a value that is substantially the same as the upper limit ph. ing.

Although the internal factors are omitted, the pressure control valve 18, the connection passage 54, the actuator 58, the relief device 82, etc. are provided corresponding to each wheel of the vehicle.

Therefore, according to this embodiment, if the pressure Pa in the working fluid chamber 62 of the actuator 58 exceeds the set pressure P of the relief valve 80 due to severe turning or acceleration/deceleration of a vehicle (not shown), When the relief valve 80 is opened, a portion of the working fluid in the connecting passage 54 is returned to the working fluid supply passage 16 via the return passage 78, thereby effectively recovering the energy held by the high-pressure working fluid.

In addition, when the pressure Pa exceeds the set pressure P'', the connecting passage 54
and the high pressure passage 16 are connected to each other, so that the pressure control valve 1
The connection passage 54 and the working fluid discharge passage 28 are connected to each other by the switching control valve 46 of No. 8, thereby preventing a part of the working fluid in the connection passage from being discharged to the working fluid discharge passage. Even when the vehicle makes a relatively sudden turn or accelerates/decelerates, the roll of the vehicle body increases relatively rapidly when the pressure in the working fluid chamber 62 exceeds the upper limit ph of the control pressure range of the pressure control valve. This will definitely be avoided.

FIG. 2 is a schematic diagram similar to FIG. 1 showing another embodiment of the hydraulic suspension according to the present invention. In FIG. 2, parts that are substantially the same as those shown in FIG. 1 are designated by the same reference numerals as in FIG.

In this embodiment, the relief valve 80 is connected to the pressure Pa in the connection passage 54 and the working fluid supply passage 1 to the relief valve 80.
The valve is configured to open when the pressure in the return passage 78 on the 6 side, and hence the differential pressure (Pa - Ps) with the pressure Ps in the working fluid supply passage 16, exceeds a set pressure P''.

Therefore, according to this embodiment, the pressure P in the working fluid chamber 62
As a increases, the differential pressure Pa - Ps becomes the set pressure Pr
The relief valve 80 is opened at the stage where the temperature exceeds 100, and thereby the same effect as in the embodiment shown in FIG. 1 can be obtained.

Further, according to this embodiment, the relief valve 80 has a differential pressure Pa-
Since the valve opens when Ps exceeds the set pressure Pr, the pressure control valve 18 frequently supplies and discharges working fluid to the actuator 58 in order to control the ride comfort and attitude of the vehicle. The pressure Ps in the working fluid supply passage 16
When the pilot pressure Pp decreases, the pilot pressure Pp also decreases, which makes it easier for the switching control valve 46 to switch to the switching position 46c. However, according to this embodiment, the relief valve 80
- Since the valve opens when PS exceeds the set pressure Pr, the pressure inside the working fluid chamber 62 is reduced when the vehicle suddenly turns or accelerates or decelerates while the pressure inside the working fluid supply passage decreases. Even if the pressure suddenly increases, it is possible to avoid switching the switching control valve 46 to the switching position 46c, and also to prevent the switching control valve 46 from switching to the switching position 46c. The relief valve 80 opens, thereby making it possible to improve the energy recovery rate compared to the embodiment shown in FIG.

In the suspension of the present invention, in order to more reliably guide the working fluid from the connecting passage to the working fluid supply passage when the pressure in the connecting passage exceeds a predetermined value, the present application was filed on the same date as the present application. The means for inhibiting the discharge of working fluid described in Japanese Patent Application No. 1983 filed by the same applicant is located between the part of the connection passage 54 to which the return passage 78 is connected and the pressure control valve 18, or between the part of the connection passage 54 to which the return passage 78 is connected or the discharge of the working fluid. It may be provided in the middle of the passage. Further, an orifice may be provided in the middle of the upper pilot passage of the switching control valve 46 in the drawing.

Although the present invention has been described above in detail with reference to two embodiments, the present invention is not limited to these embodiments, and various other embodiments are possible within the scope of the present invention. This will be obvious to those skilled in the art.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams showing one embodiment of a hydraulic suspension according to the present invention, respectively. 10... Reserve tank, 12... Passage, 14...
- Pump, 16... Working fluid supply passage, 18... Pressure control valve, 20... Attenuator, 22... Check valve, 24... Accumulator, 26... Passage, 28
... Working fluid discharge passage, 30 ... Relief valve, 32
．． 34...Aisle. 36... Throttle, 38... Solenoid on-off valve, 40... Solenoid, 42... On-off valve, 44... Bypass valve,
46...Switching control valve, 48...Passage, 50...
Fixed throttle, 52... Variable throttle, 54... Connection passage,
56... Solenoid. 58... Actuator, 60... Cylinder, 62
... Working fluid chamber, 64... Piston, 66... Upper seat, 68... Lower seat, 70... Suspension spring, 72... Passage, 74... Restriction, 76... Accumulator , 78...Return passage, 80...Relief valve, 82...Relief device patent application Attorney Toyota Motor Corporation

Claims (1)

[Claims] a working fluid supply passage having an accumulator; a working fluid discharge passage; a fluid pressure actuator disposed between a wheel and a vehicle body; a connection passage communicating with the actuator; and the working fluid supply passage or the working fluid discharge. a pressure control valve that selectively communicates and connects the passage and the connection passage and controls the pressure in the connection passage; and when the pressure in the connection passage exceeds a predetermined value, the connection passage and the working fluid supply passage are connected. a relief means for communicating and connecting the connecting passages to guide the working fluid from the connecting passage to the working fluid supply passage.