JP2538330B2 - Hydraulic suspension - Google Patents

Description

TECHNICAL FIELD The present invention relates to a suspension of a vehicle such as an automobile,
More particularly, it relates to a hydraulic suspension.

2. Description of the Related Art As one of fluid pressure type suspensions for vehicles such as automobiles, as disclosed in, for example, Japanese Patent Laid-Open No. 63-219408, between a working fluid supply passage, a working fluid discharge passage, wheels and a vehicle body. A suspension having a fluid pressure actuator disposed in the actuator and a pressure control valve that selectively connects the working fluid supply passage means or the working fluid discharge passage to the actuator and controls the pressure in the connection passage is known in the prior art. Has been.

The pressure control valve incorporated in such a conventional hydraulic suspension is a differential pressure between the pilot pressure due to the pressure in the working fluid supply passage (hereinafter referred to as system pressure) Ps and the pressure Pa in the actuator. Driven based on Ps-Pa, differential pressure Ps-Pa
Is less than the first predetermined value, the working fluid discharge passage and the actuator are communicatively connected, and when the differential pressure Ps-Pa exceeds the second predetermined value, the working fluid supply passage and the actuator are communicatively connected, and the differential pressure Ps When -Pa is in the range between the first predetermined value and the second predetermined value, the communication between the working fluid supply passage and the working fluid discharge passage and the actuator is cut off.

Therefore, in the conventional fluid pressure type suspension that incorporates such a pressure control valve, when the vehicle makes a sudden turn like a danger avoidance slalom, the pressure Pa inside the actuator on the outer ring side of the turn becomes extremely high. , Therefore the differential pressure Ps
-Pa becomes less than the first predetermined value, the working fluid discharge passage and the actuator are connected in communication, and a part of the working fluid in the actuator is discharged to the working fluid discharge passage through the pressure control valve. The vehicle height on the turning outer wheel side drops sharply. Also, the pressure Pa in the actuator on the turning inner wheel side becomes a very low value, so the differential pressure Ps-Pa exceeds the second predetermined value and the working fluid supply passage and the actuator are connected in communication, and The working fluid is supplied to the actuator via the pressure control valve, and as a result, the vehicle height on the turning inner wheel side suddenly increases.

This phenomenon also occurs when the vehicle is subjected to acceleration / deceleration that receives a very high inertial force in the front-rear direction. Therefore, in the conventional hydraulic suspension, the pressure inside the actuator exceeds the control pressure range of the pressure control valve. There is a problem that the posture of the vehicle body changes rapidly at each stage.

In view of the above-mentioned problems in the conventional hydraulic suspension, the present invention prevents the working fluid from being supplied to and discharged from the actuator when the pressure inside the actuator exceeds the control pressure range of the pressure control valve. It is an object of the present invention to provide an improved fluid pressure type suspension that does not change rapidly.

According to the present invention, a working fluid supply passage, a working fluid discharge passage, a fluid pressure actuator arranged between a wheel and a vehicle body, and the working fluid are provided. A pressure control valve for controlling the pressure in the actuator to a pressure within a control pressure range by selectively connecting the supply passage or the working fluid discharge passage to the actuator, and the pressure control valve in response to the pressure in the actuator, And a working fluid discharge inhibiting means for preventing the working fluid from being discharged from the actuator to the working fluid discharge passage via the pressure control valve when the pressure in the actuator is substantially equal to or higher than the upper limit value of the control pressure range. A fluid pressure type suspension having, a working fluid supply passage and a working fluid discharge passage,
By selectively connecting the fluid pressure actuator disposed between the wheel and the vehicle body with the working fluid supply passage or the working fluid discharge passage and the actuator, the pressure in the actuator is within the control pressure range. And a pressure control valve for controlling the pressure in the actuator, and when the pressure in the actuator is substantially equal to or lower than the lower limit value of the control pressure range in response to the pressure in the actuator, the pressure is supplied from the working fluid supply passage through the pressure control valve. And a hydraulic fluid suspension means for preventing the working fluid from being supplied to the actuator.

Action and Effect of the Invention According to the former configuration described above, when the pressure in the actuator is substantially equal to or higher than the upper limit value of the control pressure range of the pressure control valve in response to the pressure in the actuator, the actuator operates via the pressure control valve. Since there is a working fluid discharge prohibiting means that prevents the working fluid from being discharged to the fluid discharge passage, the pressure inside the actuator is equal to or higher than the upper limit value of the control pressure range due to a sudden turning or acceleration / deceleration of the vehicle. Even if it becomes, the working fluid is prevented from being discharged from the actuator to the working fluid discharge passage through the pressure control valve, which causes the vehicle height of the corresponding portion to drastically decrease and the posture of the vehicle body It is possible to prevent a sudden change.

Further, according to the latter configuration described above, when the pressure in the actuator is substantially equal to or lower than the lower limit value of the control pressure range of the pressure control valve in response to the pressure in the actuator, the pressure is supplied from the working fluid supply passage to the actuator via the pressure control valve. Since the working fluid supply prohibiting means for preventing the working fluid from being supplied is provided, even if the pressure inside the actuator becomes equal to or lower than the lower limit value of the control pressure range due to a sudden turning or acceleration / deceleration of the vehicle. , Is prevented from being supplied to the actuator from the working fluid supply passage via the pressure control valve,
Accordingly, it is possible to prevent the posture of the vehicle body from changing abruptly due to the vehicle height of the corresponding portion rapidly increasing.

Thus, according to the present invention, it is possible to prevent a sudden change in the posture of the vehicle body when the vehicle is suddenly turned or accelerated or decelerated,
As a result, it is possible to improve the steering stability when the vehicle suddenly turns or is accelerated or decelerated. If the pressure in the actuator exceeds the upper limit value of the control pressure range or falls below the lower limit value of the control pressure range, unnecessary supply and discharge of working fluid to the actuator is prevented. The flow rate consumed is reduced, which can improve fuel efficiency.

According to one embodiment of the present invention, the working fluid discharge inhibiting means is configured to connect the working fluid discharge passage means and the actuator in communication by the pressure control valve when the pressure in the actuator is equal to or higher than the upper limit value of the control pressure range. The blocking is configured to prevent the working fluid from being discharged from the actuator to the working fluid discharge passage via the pressure control valve.

According to another embodiment of the present invention, the working fluid discharge prohibiting means and the working fluid supply prohibiting means respectively operate when the pressure in the actuator is equal to or higher than the upper limit value of the control pressure range and equal to or lower than the lower limit value of the control pressure range. Occasionally, the communication between the actuator and the pressure control valve is shut off, or the working fluid discharge passage is shut off to prevent the supply and discharge of the working fluid to and from the actuator.

According to still another embodiment of the present invention, the working fluid discharge inhibiting means includes a working fluid discharge passage via the pressure control valve from the actuator even when the pressure in the working fluid supply passage means falls below a predetermined value. Is configured to prevent the working fluid from being discharged.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First Embodiment FIG. 1 is a schematic configuration diagram showing a first embodiment of a fluid pressure type suspension according to the present invention.

In FIG. 1, reference numeral 10 denotes a reserve tank that stores oil as a working fluid, and the reserve tank is connected to a pump 14 by a passage 12. One end of a working fluid supply passage 16 is connected to the pump 14, whereby the pump 14 pumps up the working fluid from the reserve tank 10 via the passage 12, and supplies the high-pressure working fluid to the working fluid supply passage 16. Has become. The other end of the working fluid supply passage 16 is connected to the pressure control valve 18.

In the middle of the working fluid supply passage 16, 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 allows only the working fluid flow from the pump to 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 of the check valve 22. The accumulator is filled with high pressure gas to absorb the pressure pulsation of the working fluid and to accumulate pressure. It's designed to be eggplant.

A portion of the working fluid supply passage 16 between the attenuator 20 and the check valve 22 is communicatively connected by a passage 26 to a working fluid discharge passage 28 that communicates with the reserve tank 10 at one end. A relief valve 30 is provided in the middle of the passage 26, and the relief valve is opened when the pressure Ps of the working fluid in the working fluid supply passage 16 is equal to or higher than a predetermined value and the working fluid in the working fluid supply passage 16 is opened. Part of the fluid is guided to the working fluid discharge passage 28, thereby preventing the pressure of the working fluid in the working fluid supply passage 16 from rising above a predetermined value Psh.

A portion of the working fluid supply passage 16 on the downstream side of the check valve 22 is connected to a working fluid discharge passage 28 through passages 32 and 34. In the middle of the passage 32, a throttle 36 and a normally open type solenoid valve 38 with adjustable flow rate are provided. Solenoid open / close valve 38
Is capable of adjusting the flow rate of the working fluid passing through the valve by changing the exciting current supplied to the solenoid 40 and closing the valve as required. A pilot operated on-off valve 42 is provided in the middle of the passage 34. The on-off valve 42 takes in the pressure on both sides of the throttle 36 as pilot pressure and maintains the valve closed position 42a when there is no differential pressure on both sides of the throttle 36, and the pressure on the upstream side of the throttle 36, that is, the working fluid supply passage side is high. Sometimes, it is switched to the valve opening position 42b. Thus throttle 36, solenoid on-off valve 3
8 and the on-off valve 42 cooperate with each other to provide the working fluid supply passage 16
And the working fluid discharge passage 28 are selectively connected to each other to connect the check valve.
The pressure in the working fluid supply passage 16 downstream of 22 is set to a predetermined value Ps.
The bypass valve 44 is controlled to o.

As shown in the figure, the pressure control valve 18 includes a switching control valve 46, a passage 48 for connecting the working fluid supply passage 16 and the working fluid discharge passage 28 to each other, a fixed throttle 50 and a variable throttle 52 provided in the middle of the passage. It has become. The other end of the working fluid supply passage 16 is connected to the P port of the switching control valve 46, the other end of the working fluid discharge passage 28 is connected to the R port, and one end of the connection passage 54 is connected to the A port. ing.

The switching control valve 46 takes in the pressure Pp in the passage 48 between the fixed throttle 50 and the variable throttle 52 as a pilot pressure via the pilot passage 48a, and the connecting passage 54 via the pilot passage 54a having the fixed throttle 45 in the middle. It is a spool valve that takes in the internal pressure Pa as pilot pressure.
When the sum of the spring force F of 47 and Pa is higher than Pa, it is switched to the switching position 46a for connecting and connecting the P port and the A port,
When the sum of the pressure Pp and the spring force F and Pa are substantially equal to each other, the switching position 46 that shuts off the communication of all ports.
When the sum of the pressure Pp and the spring force F is lower than the pressure Pa, the pressure is switched to the switching position 46c where the port R and the port A are communicatively connected. Variable aperture 5
The solenoid 2 changes the effective passage cross-sectional area of the throttle by controlling the electric current supplied to the solenoid 56, thereby changing the pressure Pp in cooperation with the fixed throttle 50.

Thus, if the pressure in the working fluid discharge passage, which is substantially atmospheric pressure, is Pd, the pressure control valve 18 determines the pressure in the connection passage.
Pa is controlled within a range of Pal (> Pd) or more and Pah (<Psh) or less.

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

The connection passage 54 and the working fluid discharge passage 28 are the return passage 78.
And a relief valve 80 is provided in the return passage. The relief valve 80 takes in the pressure in the return passage 78 on the side of the connection passage 54, that is, the pressure Pa in the connection passage 54 as a pilot pressure, and opens when the pressure exceeds a predetermined set pressure Pr to open the connection passage. The flow of the working fluid from 54 toward the working fluid discharge passage 28 is allowed, thereby protecting the actuator and the like from a very high pressure.

Further, a portion of the pilot passage 54a between the switching control valve 46 and the throttle 45 is connected to a working fluid discharge passage by a passage 82, and a relief valve 84 is provided in the middle of the passage. The relief valve 84 takes in the pressure Pa ′ in the passage 82 on the pilot passage 54a side as a pilot pressure, opens when the pressure exceeds a predetermined set pressure Ph, and opens from the pilot passage 54a through the passage 82 to generate the working fluid. The flow of the working fluid toward the discharge passage 28 is allowed. Thus, the passage 82 and the relief valve 84 cooperate with each other to guide a part of the working fluid in the pilot 54a to the working fluid discharge passage 28 when the pressure Pa 'becomes equal to or higher than the set pressure Ph, whereby the pilot pressure is increased.
By reducing Pa ′, the switching control valve 46 is prevented from switching to the switching position 46c even when the pressure Pa in the working fluid chamber 62 of the actuator exceeds a predetermined value as described later, and the pressure from the actuator is reduced. A working fluid discharge inhibiting device 86 that prevents the working fluid from being discharged to the working fluid discharge passage 28 via the control valve is configured.

The set pressure Pr of the relief valve 80 is the set pressure Ph of the relief valve 84.
It is set to a value much higher than that, and the set pressure Ph of the relief valve 84 is set to the same as or slightly lower than the upper limit value Pah of the control pressure range of the pressure control valve 18.
Although not shown in the drawing, the pressure control valve 18, the connection passage 54, the actuator 58, the working fluid discharge inhibiting device 86, etc. are provided corresponding to each wheel of the vehicle.

In this embodiment, when the set pressure Ph of the relief valve 84 is set to a pressure slightly lower than the upper limit value Pah of the control pressure range of the pressure control valve, the vehicle makes a sharp turn or acceleration / deceleration. By doing so, the pressure in the working fluid chamber 62 rises, and when the pilot pressure Pa ′ reaches the set pressure Ph of the relief valve 84, the relief valve 84 opens and the pilot pressure Pa ′ becomes the pressure.
It does not rise above Ph, and this causes the switching control valve 46
Are switched to the switching position 46a. Therefore, the working fluid chamber 62
Even if the internal pressure further rises, it is possible to prevent the working fluid in the actuator 58 from flowing out to the working fluid discharge passage 28 via the pressure control valve 18 and suddenly lowering the vehicle height.

When the set pressure Ph of the relief valve 84 is set to the same value as the upper limit value Pah of the control pressure range of the pressure control valve, the pressure Pa in the working fluid chamber 62 increases and the pilot pressure
When Pa ′ reaches the set pressure Ph of the relief valve 84, the relief valve 84 opens, and even if the pressure Pa further rises, the pilot pressure Pa ′ is maintained at the set pressure Ph. 46 is maintained in the switching position 46b, and the working fluid in the actuator 58 is prevented from flowing out to the working fluid discharge passage 28 via the pressure control valve 18, thereby avoiding a rapid decrease in vehicle height.

Therefore, the roll rigidity during turning of this embodiment changes as shown by the solid line in FIG. 10, and when the pressure in the connection passage exceeds the upper limit value of the control pressure range of the pressure control valve, the pressure control valve Compared to the case of the conventional fluid pressure type suspension (indicated by the phantom line in FIG. 10) in which the connection passage and the working fluid discharge passage are communicated by the Roll rigidity can be improved. Further, even when abrupt acceleration / deceleration is performed, the rigidity in the vehicle front-rear direction is improved as compared with the conventional case. Therefore, according to this embodiment, the posture change of the vehicle body during abrupt turning or acceleration / deceleration is performed. It can be reduced as compared with the conventional case.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the fluid pressure suspension according to the present invention. Note that, in FIG. 2, the same reference numerals as those in FIG. 1 are attached to the substantially same portions as those shown in FIG. In this embodiment, a shutoff valve 90 is provided in the middle of the connection passage 54. The shutoff valve 90 takes in the pressure Pa in the connection passage 54 and the pressure Ps in the working fluid supply passage 16 on the actuator side from that as pilot pressure, and closes when the differential pressure Ps-Pa becomes a predetermined value or less, and the The flow of the working fluid toward the pressure control valve 18 is blocked. Further, the connection passage 54 is connected to a passage 92 that bypasses the cutoff valve 90 and connects the connection passages on both sides of the cutoff valve 90, and only the flow of the working fluid from the pressure control valve 18 to the actuator 58 is provided in the middle of the passage. A check valve 94 that allows the

Thus, the shutoff valve 90, the passage 92, and the check valve 94 cooperate with each other, and when the differential pressure Ps-Pa falls below a predetermined value, the actuator 5
A working fluid discharge inhibiting device 96 that blocks the flow of the working fluid from 8 toward the pressure control valve 18 via the connection passage 54 is configured. Note that the shutoff valve 90 has a pressure Pa in the connection passage 54
The valve is closed when the pressure becomes equal to or slightly lower than the upper limit value Pah of the control pressure range.

Further, in this embodiment, a shutoff valve 98 is provided in the middle of the working fluid discharge passage 28. This shut-off valve 98 takes in the pressure Pd in the working fluid discharge passage and the pressure Ps in the working fluid supply passage 16 on the downstream side as pilot pressure, and opens when the differential pressure Ps-Pd exceeds a predetermined value. It is like this. The working fluid discharge passage 28 is connected to a passage 100 that bypasses the shutoff valve 98 and connects the working fluid discharge passages on both sides thereof. A residual pressure valve 102 is provided in the middle of the passage 100, and the residual pressure valve 102 is provided on the upstream side and the downstream side of the residual pressure valve 102.
The pressure in 0 is taken in as a pilot pressure, and when the pressure difference between them is equal to or greater than a predetermined value, the valve is opened, which causes a certain difference between the upstream side and the downstream side of the shutoff valve 98 in the working fluid discharge passage 28. It is designed to secure pressure. The differential pressure for opening the shutoff valve 98 is set to be larger than the differential pressure for opening the residual pressure valve 102.

Further, the return passage 78 having the relief valve 80 in the middle is provided with the working fluid discharge inhibiting device 96 and the actuator 58 in the connection passage 54.
And a portion of the passage 100 on the upstream side of the residual pressure valve 102. Further, one end of the passage 48 of the pressure control valve 18 is not connected to the working fluid discharge passage 28 but directly connected to the reserve tank 10, and an electromagnetic opening / closing valve 104 is provided in the middle thereof. The electromagnetic opening / closing valve 104 is of a normally closed type, and is opened by supplying a control current to its solenoid 106 from a control device (not shown) at the start of the operation of this embodiment. There is.

The pressure control valve 18, the working fluid discharge inhibiting device 96, the actuator 58, the relief valve 80, etc. are provided for each wheel, and the shutoff valve 98 and the residual pressure valve 102 are the left and right front wheel suspensions and the left and right rear wheel suspensions. Are provided corresponding to each.

According to this embodiment, the pressure in the working fluid chamber 62 of the actuator 58 is increased by the sudden turning or acceleration / deceleration of the vehicle.
When Pa rises and the differential pressure Ps-Pa falls below a specified value, the shutoff valve 9
When 0 is closed and the communication of the connection passage 54 is cut off, the actuator functions as a hydropneumatic suspension, whereby the actuator transmits the working fluid to the working fluid discharge passage 28 via the connection passage 54 and the pressure control valve 18. Is prevented from flowing out, which prevents the vehicle height of the corresponding portion from being suddenly lowered.

Therefore, in this embodiment, the roll rigidity during turning is
As shown by the broken line in FIG. 10, therefore, according to this embodiment, the posture change of the vehicle body when a sudden turn or acceleration / deceleration is performed is compared with that in the first embodiment. It can be reduced more effectively.

FIG. 3 is a schematic configuration diagram showing a third embodiment of the fluid pressure suspension according to the present invention. Incidentally, in FIG. 3, the substantially same parts as those shown in FIG. 2 are designated by the same reference numerals as those shown in FIG.

In this embodiment, the shutoff valve 90 of the working fluid discharge inhibiting device 96 is provided in the middle of the working fluid discharge passage 28, and the passage 92 and the check valve 94 in the second embodiment are eliminated. ing. The shutoff valve 90 in this embodiment is also configured similarly to the shutoff valve 90 in the second embodiment, and closes when the differential pressure Ps-Pa becomes equal to or less than a predetermined value, and the working fluid discharge passage 28 is closed. It is designed to cut off communication.

Therefore, according to this embodiment, the pressure Pa in the working fluid chamber 62 rises due to the sudden turning or acceleration / deceleration of the vehicle,
When the differential pressure Ps-Pa becomes equal to or lower than a predetermined value, the communication of the working fluid discharge passage 28 is cut off, so that the working fluid flows out from the actuator to the reserve tank through the connection passage, the pressure control valve, and the working fluid discharge passage. This is prevented, which prevents the vehicle height of the corresponding portion from rapidly decreasing.

Further, in this embodiment and the above-mentioned second embodiment, the shutoff valve 90 is provided when the differential pressure Ps-Pa between the pressure Ps in the working fluid supply passage 16 and the pressure Pa in the connection passage is less than or equal to a predetermined value. Since the valve is closed, even if the pressure Ps fluctuates, and thus the upper limit value of the control pressure range of the pressure control valve fluctuates, when the pressure Pa becomes high, the pressure control valve and the working fluid discharge passage are discharged from the actuator. It is possible to reliably prevent the working fluid from flowing out to the reserve tank via the.

FIG. 4 is a schematic configuration diagram showing a fourth embodiment of the fluid pressure suspension according to the present invention. Incidentally, in FIG. 4, the same reference numerals as those shown in FIG. 1 are attached to the portions substantially the same as the portions shown in FIG.

In this embodiment, two shutoff valves 110 and 112 are provided in the connecting passage 54. The shut-off valve 110 takes in the pressure Pd in the reserve tank as a pilot pressure from a pilot passage 114 communicating with the reserve tank 10, and the pilot passage 12 having a throttle 118 midway from the auxiliary valve 116.
The pilot pressure Pc is taken in through 0, the valve is opened when the differential pressure Pc-Pd is equal to or higher than a predetermined value, and the valve closed state is maintained when the differential pressure Pc-Pd is less than the predetermined value. Auxiliary valve 116
A pilot passage 120, a pilot passage 122 communicating with the working fluid supply passage 16, and a pilot passage 123 communicating with the reserve tank 10 are connected. This auxiliary valve 116
Is the part 5 of the connection passage 54 between the pressure control valve 18 and the shutoff valve 110.
Via the pressure Pa ₁ pilot passage 124 within 4b uptake, also the pressure in the pilot passage 122 through the pilot passage 126 communicating with the pilot passage 122 having an aperture 125 in the middle, thus the pressure Ps of the working fluid supply passage 16 The pressure Ps in the working fluid supply passage 16 is introduced into the pilot passage 120 by switching to the switching position 116a when the differential pressure Ps-Pa ₁ is greater than or equal to a predetermined value.
When s-Pa ₁ is less than the predetermined value, the pressure Pd in the reserve tank 10 is introduced into the pilot passage 120 by switching to the switching position 116b.

The auxiliary valve 116 and the shutoff valve 110 constitute a working fluid discharge inhibiting device 128 for preventing the working fluid from flowing out from the actuator 58 to the working fluid discharge passage 28 via the connection passage 58 and the pressure control valve 18, as described later. The shutoff valve 110 is closed when the control pressure of the pressure control valve 18 reaches its upper limit value Pah.

Further, the shutoff valve 112 takes in the pressure Pd in the reserve tank as the pilot pressure via the pilot passage 130 communicating with the pilot passage 114, and the shutoff valves 110 and 1 of the connection passage 54.
The pressure Pa ₂ in the portion 54c between the 12 and 12 is taken in through the pilot passage 134 having the throttle 132 in the middle, and when the differential pressure Pa ₂ -Pd is a predetermined value or more, the valve is opened and the differential pressure Pa ₂ -Pd is set to the predetermined value. When it is less than the value, it is designed to open. The shutoff valve 112 constitutes a working fluid supply prohibiting device 136 for preventing the working fluid from being supplied to the actuator from the pressure control valve 18 via the connection passage 54 as described later, and the control pressure of the pressure control valve is The valve closes when the lower limit Pal is reached.

In this embodiment, when the pressure in the working fluid supply passage 16 is within the predetermined range, that is, the lower limit value Ps1 or more and the upper limit value Psh or less, the auxiliary valve 116 is switched to the switching position 116a. As a result, the pressure Ps is supplied to the pilot passage 120, whereby the shutoff valve 110 is opened and the shutoff valve 136 is opened.
By also opening the valve, the connection passage 54 is maintained in a communicating state.

On the other hand, when the pressure Ps in the working fluid supply passage 16 drops below Ps1, the auxiliary valve 116 is switched to the switching position 116b, whereby the pressure Pd is supplied to the pilot passage 120, and the shutoff valve 110 is closed. To be done. Thus pressure P
When s becomes less than Ps1, the working fluid discharge inhibiting device 128 prevents the working fluid from flowing from the actuator 58 to the working fluid discharge passage 28 via the connection passage 54 and the pressure control valve 18.

Further, when the pressure Ps in the working fluid supply passage 16 is in the normal pressure range, the pressure Pa in the working fluid chamber 62 of the actuator 58 is changed by the pressure control valve 18 when the vehicle suddenly turns and accelerates / decelerates. When the control pressure range becomes higher than the upper limit value Pah, the pilot pressure in the pilot passage 124 also becomes higher than the upper limit value, which causes the auxiliary valve 116 to move to the switching position 116b.
Is switched to. Therefore, the pilot pressure in the pilot passage 120 becomes substantially the pressure Pd, and the shutoff valve 110 is closed, whereby the communication of the connection passage 54 is shut off. Thus, even when the pressure in the actuator exceeds a predetermined value, the working fluid discharge prohibiting device 128 prevents the working fluid from flowing out of the actuator to the working fluid discharge passage through the connection passage and the pressure control valve, and thus the countermeasure is taken. It is possible to prevent the vehicle height of the part to be reduced from dropping sharply.

On the contrary, when the pressure in the working fluid chamber 62 falls below the lower limit value Pa1 of the control pressure range of the pressure control valve 18 due to the vehicle suddenly turning or accelerating and decelerating, the shutoff valve 112 is shut off. The communication of 54 is cut off, which prevents the working fluid from being supplied from the working fluid supply passage 16 to the actuator through the pressure control valve and the working fluid supply passage, thereby rapidly increasing the vehicle height of the corresponding portion. Is avoided. In this case, since the shut-off valve 110 maintains the open state, when the pressure Pa in the working fluid chamber 62 becomes equal to or higher than the lower limit value Pa1 of the control pressure range of the pressure control valve 18, a control device (not shown) is used. The control pressure of the pressure control valve is pressure Pa
Is controlled to be equal to
The shut-off valve is opened by being taken into the shut-off valve 112 via 134.

Thus, according to this embodiment, when the control pressure of the pressure control valve reaches the upper limit value and the lower limit value of the control pressure range,
The working fluid discharge inhibiting device 128 and the working fluid supply inhibiting device 136 respectively reliably prevent the supply and discharge of the working fluid to and from the actuator 58. Therefore, the roll rigidity in this embodiment changes as shown by the solid line in FIG. 11, and the posture change of the vehicle body is effectively prevented in both the bounding and rebounding directions of the wheels.

Further, since the pilot passage 134 guides the pressure in the connection passage 54 (part 54c) on the pressure control valve side from the shutoff valve 112, the pressure Pa in the actuator is set to the control pressure range of the pressure control valve as described above. If the lower limit value is not more than the lower limit value and the lower limit value is not less than the lower limit value, the shutoff valve 112 can be opened promptly and the normal riding comfort control and the posture control can be swiftly changed.

FIG. 5 is a schematic configuration diagram showing a fifth embodiment of the fluid pressure suspension according to the present invention. Note that, in FIG. 5, parts substantially the same as the parts shown in FIG. 4 are denoted by the same reference numerals as those shown in FIG.

In this embodiment, the pilot passage 120 of the shutoff valve 110 is
Is directly connected to the working fluid supply passage 16. Further, a cutoff valve 140 is provided in a portion of the connection passage 54 between the cutoff valve 110 and the actuator 58. This shut-off valve 140 takes in the pressure Pa ₃ in the portion 54d between the shut-off valves 110 and 140 of the connection passage 54 via the pilot passage 142, and has a throttle 144 on the way to communicate with the pilot passage 120. The pressure Ps in the working fluid supply passage is taken in as a pilot pressure via.

The shutoff valve 110 operates similarly to the shutoff valve 110 in the fourth embodiment, and opens when the differential pressure Ps-Pd exceeds a predetermined value,
When the differential pressure Ps-Pd is less than or equal to a predetermined value, the valve closed state is maintained. The shut-off valve 140 is opened when the differential pressure Ps-Pa ₃ exceeds a predetermined value, when the differential pressure Ps-Pa ₃ below the predetermined value is adapted to maintain the closed state, as described later working fluid A working fluid discharge inhibiting device 148 is configured to close when the pressure in the chamber 62 exceeds a predetermined value and prevent the working fluid from flowing out from the actuator to the working fluid discharge passage 28 via the connection passage 54 and the pressure control valve 18. are doing.

In this embodiment, as in the case of the fifth embodiment, when the pressure Ps in the working fluid supply passage 16 drops below a predetermined value, the shutoff valve 110 is closed, which causes the actuator 58 to operate.
As a result, the working fluid is prevented from flowing out to the working fluid discharge passage 28 through the connection passage 54 and the pressure control valve 18. The pressure in the working fluid chamber 62 rises as the vehicle makes sharp turns and accelerates / decelerates, and the upper limit of the control pressure range of the pressure control valve 18 is reached.
When a pressure substantially equal to Pah is reached, the shut-off valve 140 closes, again preventing the working fluid from flowing from the actuator through the connection passage and the pressure control valve to the working fluid discharge passage, As a result, it is possible to prevent the vehicle height of the corresponding portion from being suddenly lowered.

FIG. 6 is a schematic configuration diagram showing a sixth embodiment of the fluid pressure suspension according to the present invention. Incidentally, in FIG. 5, parts substantially the same as the parts shown in FIG. 4 or FIG. 5 are given the same reference numerals as those shown in FIG. 4 or FIG. .

In this embodiment, the shutoff valve 14 in the fifth embodiment is used.
A shutoff valve 112 identical to the shutoff valve 112 in the fourth embodiment is provided in the portion of the connection passage between 0 and the actuator 58, and the shutoff valve 112 is the shutoff valve 112 in the fourth embodiment. The working fluid supply prohibiting device 136 is configured in the same manner as in.

Note that the shutoff valve 112 may be provided in the portion of the connection passage between the pressure control valve 18 and the shutoff valve 110 as shown in FIG. 7 showing the seventh embodiment of the present invention. According to the sixth and seventh embodiments, both the effects of the fifth embodiment and the effects of the working fluid supply inhibiting device 136 of the fourth embodiment can be obtained.

FIG. 8 is a schematic configuration diagram showing an eighth embodiment of the fluid pressure suspension according to the present invention. Note that, in FIG. 8, the same reference numerals as those in FIG. 4 are attached to the substantially same portions as the portions shown in FIG.

In this embodiment, the pilot passage 124 of the first auxiliary valve 116 is provided with the second auxiliary valve 150 so that the working fluid supply passage 16
The internal pressure Ps or the internal pressure Pa ₁ in the portion 54b of the connection passage 54 is supplied. The second auxiliary valve 150 takes in the pressure Pa ₁ in the portion 54b as a pilot pressure via a pilot passage 154 having a throttle 152 in the middle, and takes in the pressure Pd in the reserve tank 10 as a pilot pressure via a pilot passage 156. When the differential pressure Pa ₁ -Pd is greater than or equal to a predetermined value, the pressure is switched to the switching position 150a, which connects the pilot passages 154 and 124 to each other and connects them to the pilot passage 124.
When a ₁ is supplied and the differential pressure Pa ₁ -Pd is less than a predetermined value, the switching position is switched to the switching position 150b.
The pressure Ps in the working fluid supply passage 16 is guided to the pilot passage 124 by connecting and.

Thus, shutoff valve 110, first auxiliary valve 116, second auxiliary valve
As described below, the pressure Pa in the connection passage 54 is 150.
A working fluid discharge and working fluid supply prohibiting device 160 that blocks the supply and discharge of the working fluid to and from the actuator 58 when the control pressure range is equal to or higher than the upper limit value Pah or equal to or lower than the lower limit value Pal.

In this embodiment, the pressure Ps in the working fluid supply passage 16 is
Is lower than the lower limit value Psl, the first and second auxiliary valves maintain the illustrated state, the pressure in the pilot passage 120 becomes the pressure Ps in the working fluid supply passage supplied through the pilot passage 122, As a result, the shutoff valve 110 is closed and the communication of the connection passage 54 is shut off, whereby the working fluid is prevented from flowing out from the actuator to the working fluid discharge passage 28 via the connection passage and the pressure control valve 18.

Further, when the pressure Ps in the working fluid supply passage 16 is in the normal pressure range, the pressure Pa in the working fluid chamber 62 of the actuator 58 is changed by the pressure control valve 18 when the vehicle suddenly turns and accelerates / decelerates. When the upper limit value Pah of the control pressure range is reached, the second auxiliary valve 150 maintains the illustrated state, while the first auxiliary valve 116 is switched to the switching position 116b.
As a result, the pressure in the pilot passage 120 is switched to the pressure Pd in the reserve tank 10. Therefore, the shut-off valve 110 is closed to cut off the communication of the connection passage 54, thereby preventing the working fluid from flowing out from the actuator to the working fluid discharge passage via the connection passage and the pressure control valve, and thereby the corresponding portion. It is possible to avoid a sudden drop in vehicle height.

On the contrary, when the pressure Pa in the working fluid chamber 62 falls below the lower limit value Pal of the control pressure range of the pressure control valve 18 due to the sudden turning or acceleration / deceleration of the vehicle, the pressure Pa ₁ in the portion 54b also drops. As a result, the second auxiliary valve 150 is switched to the switching position 150b. As a result, the pressure Ps in the working fluid supply passage 16 passes through the pilot passages 124 and 158 through the pilot passages 122 and 158.
Is supplied, which causes the first auxiliary valve 116 to switch to the switching position 1
Switched to 16b. Therefore, in this case as well, the pressure in the pilot passage 120 becomes the pressure Pd in the reserve tank, which closes the shutoff valve 110 and shuts off the communication of the connection passage 54, thereby controlling the pressure from the working fluid supply passage 16. The working fluid is prevented from being supplied to the actuator via the valve and the connection passage, thereby avoiding a sudden increase in vehicle height at the corresponding portion.

FIG. 9 is a schematic configuration diagram showing a ninth embodiment of the fluid pressure suspension according to the present invention. Note that, in FIG. 9, the portions substantially the same as the portions shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG.

In this embodiment, an electromagnetic on-off valve 170 is provided in a portion between the pressure control valve 18 and a portion of the connection passage 54 to which the return passage 78 is connected. In the illustrated embodiment, the solenoid on-off valve 170 is a normally-open type on-off valve, and is switched to a closed position by outputting a control signal to a solenoid 172 from a controller (not shown). It is like this. Further, in this embodiment, a pressure sensor 174 for detecting the pressure in the connection passage 54 is provided between the actuator and the on-off valve 170.

Although not shown in the figure, the electromagnetic on-off valve 170 is a case where the pressure Pa detected by the pressure sensor 174 is equal to or higher than the upper limit value or lower than the lower limit value of the control pressure range of the pressure control valve 18, and Only when the vehicle speed sensor, steering angle sensor, brake switch, throttle opening sensor, etc., not shown in the figure, detect that the vehicle is making a sharp turn or accelerating / decelerating, the valve is closed. There is.

Therefore, in this embodiment as well, the connection is made when the pressure in the working fluid chamber 62 becomes equal to or higher than the upper limit value or equal to or lower than the lower limit value of the control pressure range of the pressure control valve due to a sudden turning or acceleration / deceleration of the vehicle. The communication of the passage 54 is cut off, whereby the working fluid flows from the actuator to the working fluid discharge passage via the connection passage and the pressure control valve, and conversely operates from the working fluid supply passage to the actuator via the pressure control valve and the connection passage. The fluid is prevented from being supplied, which prevents a sudden change in posture of the vehicle body when the vehicle rapidly turns or accelerates / decelerates.

In addition, according to this embodiment, the supply and discharge of the working fluid to and from the actuator are not blocked except when the vehicle is suddenly turned or accelerated or decelerated, so that the riding comfort of the vehicle when traveling on a bad road is deteriorated. It can be avoided.

In this embodiment, the pressure in the working fluid supply passage 16 is
Even if Ps fluctuates, the working fluid as shown in FIG. 9 is provided so as to surely avoid the supply and discharge of the working fluid to and from the actuator through the pressure control valve in the case of sudden turning or acceleration / deceleration of the vehicle. The supply passage 16 is also provided with a pressure sensor 176 for detecting the pressure Ps therein, and when the differential pressure Ps-Pa is equal to or higher than a predetermined value or lower than a predetermined value, the vehicle speed sensor or the like causes the vehicle to make a sharp turn or acceleration / deceleration. The electromagnetic on-off valve 170 may be configured to be closed only when it is detected that the operation is being performed.

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

[Brief description of drawings]

1 to 9 are schematic structural views showing one embodiment of a fluid pressure suspension according to the present invention, and FIG. 10 is a view of the embodiment shown in FIGS. 1 and 2 and a conventional fluid pressure suspension. FIG. 11 is a schematic graph showing changes in roll rigidity, and FIG. 11 is a schematic graph showing changes in roll rigidity in the embodiment shown in FIG. 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
...... Passage, 36 ...... Throttle, 38 ...... Solenoid on-off valve, 40 ...... Solenoid, 42 ...... Open / close valve, 44 ...... Bypass valve, 46 ...... Switching control valve, 48 ...... Passage, 50 ...... Fixed throttle , 52 ... Variable diaphragm, 54 ...
… Connection path, 56 …… Solenoid, 58 …… Actuator, 6
0 …… Cylinder, 62 …… Working fluid chamber, 64 …… Piston, 66…
… Upper seat, 68 …… Lower seat, 70 …… Suspension spring, 72 …… Passage, 74 …… Throttle, 76 …… Accumulator, 78 …… Return passage, 80 …… Relief valve, 82 ……
Passage, 84 …… Relief valve, 86 …… Working fluid discharge prohibition device, 9
0 …… Shut-off valve, 92 …… Passage, 94 …… Check valve, 96 …… Working fluid discharge inhibiting device, 98 …… Shut-off valve, 100 …… Passage, 102 …… Residual pressure valve, 104 …… Solenoid on-off valve , 106 ... Solenoid, 110,112 ...
… Shut-off valve, 114 …… Pilot passage, 116 …… Auxiliary valve, 118…
… Aperture, 120-124 …… Pilot passage, 125 …… Aperture, 126
...... Pilot passage, 128 ...... Work fluid discharge prohibition device, 130
...... Pilot passage, 132 ...... Throttle, 134 ...... Pilot passage, 136 ...... Work fluid supply prohibition device, 140 ...... Shut-off valve, 142 ......
… Pilot passage, 144 …… Throttle, 146 …… Pilot passage, 148 …… Working fluid discharge inhibiting device, 150 …… Second auxiliary valve, 152 …… Throttle, 154-158 …… Pilot passage, 160 ……
Supply and discharge prohibition device for working fluid, 170 ... Electromagnetic on-off valve, 172
...... Solenoid, 174,176 ...... Pressure sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Yonekawa 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Toshio Onuma 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. ( 72) Inventor, Katsuhiko Hattori, 1) 41 Yokomichi, Nagakute-cho, Aichi-gun, Aichi-gun, Toyota Central Research Institute, Inc. (72) Inventor, Osamu Komazawa, 2-chome, Asahi-cho, Kariya, Aichi (Aisin Seiki Co., Ltd.) 72) Inventor Narutaka Isoya 2-1-1 Asahi-cho, Kariya city, Aichi Aisin Seiki Co., Ltd.

Claims (2)

(57) [Claims] 1. A working fluid supply passage, a working fluid discharge passage, a fluid pressure actuator disposed between a wheel and a vehicle body, and the working fluid supply passage or the working fluid discharge passage and the actuator are selected. Pressure control valve for controlling the pressure in the actuator to a pressure within the control pressure range by being connected in a continuous manner, and the pressure in the actuator in response to the pressure in the actuator is substantially the upper limit of the control pressure range. A hydraulic suspension having a working fluid discharge inhibiting means for preventing the working fluid from being discharged from the actuator through the pressure control valve to the working fluid discharge passage when the value is equal to or more than a value. 2. A working fluid supply passage, a working fluid discharge passage, a fluid pressure actuator arranged between a wheel and a vehicle body, and the working fluid supply passage or the working fluid discharge passage and the actuator are selected. Pressure control valve for controlling the pressure in the actuator to a pressure within the control pressure range by being connected in a continuous manner, and the pressure in the actuator in response to the pressure in the actuator is substantially the lower limit of the control pressure range. A hydraulic suspension having a working fluid supply prohibiting means for preventing the working fluid from being supplied to the actuator from the working fluid supply passage via the pressure control valve when the value is not more than a value.