JPH06213266A - Supply flow control device for fluid type suspension - Google Patents

Abstract

PURPOSE:To constitute a flow adjusting mechanism by which a discharge quan tity of a variable delivery pump is limited while preventing variation of vehicle height at starting a fluid pressure supply device, without using an electromag netic valve and at low cost. CONSTITUTION:A flow adjusting mechanism 4 is provided on the suction side of a radial piston pump 1 supplying oil pressure to a fluid type suspension, and the mechanism 4 is constituted of a spool valve 41 to be positioned on a low pressure minimum flow position, a high pressure maximum flow position, and a high pressure minimum flow position according to the discharge pressure of the piston pump 1. At starting the piston pump 1, the valve 41 is positioned on the low pressure minimum flow position due to low discharge pressure so as to limit the discharge flow and gradually increase the discharge pressure, and when it reaches over the holding pressure of a pressure holding part 61, the valve is positioned on the high pressure maximum flow position so as to quickly increase the discharge pressure up to setting pressure, and after reaching the setting pressure, constant pressure control is performed between the high pressure minimum flow position and the high pressure maximum flow position according to the discharge pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supply flow rate control device for a hydraulic suspension having a hydraulic control system including a fluid pressure cylinder such as an active suspension.

[0002]

2. Description of the Related Art As a conventional supply flow rate control device for a fluid type suspension, there is, for example, one disclosed in Japanese Patent Application Laid-Open No. 3-42321 proposed by the present applicant.
In this conventional example, a fluid pressure cylinder inserted between each wheel and a vehicle body, and a control valve for controlling a working fluid pressure from a fluid pressure supply device supplied to the fluid pressure cylinder according to a command value. An active suspension including a pressure holding mechanism having a closed circuit on the control valve side when the supply pressure of the control valve interposed between the control valve and the fluid pressure supply device becomes a predetermined pressure or less, An on-off valve that is opened by a predetermined time delay when the fluid pressure supply device is started is inserted in the supply-side pipe between the fluid pressure supply device and the pressure control valve, and a throttle is provided in parallel with the on-off valve. With this configuration, when the fluid pressure supply device is in the starting state, the fluid pressure is gradually supplied to the pressure control valve to prevent a sudden increase in vehicle height and to give an occupant a feeling of discomfort. I try to prevent it.

By the way, in the above-mentioned conventional example, the hydraulic pump constituting the fluid pressure supply device is constituted by a fixed displacement pump, and therefore at the maximum load regardless of the amount of hydraulic oil consumed by the pressure control valve. Since the corresponding constant flow rate is discharged, excess hydraulic oil is returned to the tank via the relief valve, which causes the hydraulic oil to generate heat and the energy consumption of the hydraulic system must be increased. There is.

In order to solve this, the flow rate control device for a variable displacement positive displacement pump disclosed in Japanese Patent Laid-Open No. 3-213683 previously proposed by the present applicant is applied to change the fluid pressure supply device. It is composed of a capacity pump, and throttle means is inserted in the suction passage of this variable capacity pump, and this throttle means responds to the discharge pressure of the variable capacity pump as the capacity control pressure and in the direction opposite to this capacity control pressure. By the valve means that receives the discharge pressure control force and responds to this, and the opening degree is set, the flow rate is controlled so that the discharge pressure is kept constant by the pressure compensating action of the pump. The excess flow rate relieved from the relief valve is reduced, the heat generation of the hydraulic oil is reduced, and the energy consumption can be reduced.

[0005]

However, in the above-mentioned conventional flow rate control device for the fluid type suspension, the fluid pressure supply device is made to be a variable displacement pump, so that the surplus relief from the relief valve at the normal time is achieved. Although it is possible to reduce the energy consumption by reducing the flow rate, in order to prevent a change in vehicle height when the fluid pressure supply device is started,
In order to limit the sudden increase of the working fluid supplied to the pressure control valve, it is necessary to suppress the discharge amount of the variable displacement pump. For this purpose, the pressure control is disclosed in Japanese Patent Laid-Open No. 3-90417. It is conceivable to provide a flow rate adjusting mechanism consisting of an on-off valve inserted in the supply passage of the valve and a throttle inserted in parallel with this, but in this case, the on-off valve is provided only when the fluid pressure supply device is started. An electromagnetically operated on-off valve is applied to control the time-closed state, and a control circuit that controls this electromagnetically operated on-off valve and a harness that electrically connects this control circuit and the electromagnetically operated on-off valve are required. Therefore, there is an unsolved problem that the cost increases.

Therefore, the present invention has been made by paying attention to the unsolved problem of the above-mentioned conventional example, and limits the discharge amount of the variable displacement pump while preventing the vehicle height change at the time of starting the fluid pressure supply device. It is an object of the present invention to provide a supply flow rate control device for a fluid suspension, which can configure a flow rate adjusting mechanism that operates at low cost without using an electromagnetically operated valve.

[0007]

In order to achieve the above object, a supply flow rate control device for a fluid suspension according to a first aspect of the present invention is a fluid pressure cylinder interposed between a vehicle body and a wheel, and the fluid. A fluid supply device having a variable displacement pump for supplying a working fluid to the pressure cylinder; a pressure control valve for controlling the working fluid supplied from the variable displacement pump according to a command value to supply the fluid pressure cylinder; A fluid type including a pressure holding mechanism that is interposed between the pressure control valve and the fluid supply device and has a closed circuit on the pressure control valve side when the supply pressure to the pressure control valve becomes equal to or lower than a set pressure. In the suspension supply flow rate control device, the fluid supply device has a variable throttle in an intake passage of the variable displacement pump that opens and closes according to a change in discharge pressure, and the variable throttle has a discharge pressure of the pressure holding device. When the pressure becomes equal to or higher than the first set pressure higher than the set pressure, the opening degree increases from the minimum opening degree in accordance with the increase in the discharge pressure, and the second opening pressure higher than the first set pressure reaches the maximum opening degree. It is characterized by being configured.

Further, in the fluid suspension supply flow rate control device according to a second aspect, in the variable throttle, the variable throttle restricts a sleeve in which the pump side port and the tank side port are axially adjacent to each other, and slides in the sleeve. Has a spool rod portion which is disposed so as to be able to communicate with at least the pump side port and the tank side port formed between the first and second spool land portions, and the first spool land portion has the pump side port. Between the low pressure minimum flow rate position that closes the tank, the high pressure maximum flow rate position that communicates the pump side port and the tank side port with the spool rod portion, and the high pressure low flow rate position that closes the tank side port with the second spool land portion. A spool that slides, a pressing unit that presses the spool toward the high-pressure low-flow rate position side according to the pump discharge pressure, and a low-pressure maximum in all the sliding regions of the spool. First biasing means for biasing to the flow rate position side, second biasing means for biasing the spool toward the low pressure minimum flow rate position between the high pressure low flow rate position and the high pressure maximum flow rate position, and the tank side port And a check valve that is interposed between the fluid chamber formed between the second spool land portion and the sleeve and that blocks a fluid flow from the fluid chamber to the tank side port. I am trying.

Further, a supply flow rate control device for a fluid type suspension according to a third aspect includes a fluid pressure cylinder inserted between a vehicle body and a wheel, and a variable displacement pump for supplying a working fluid to the fluid pressure cylinder. A fluid supply device provided, and a pressure control valve that controls the working fluid supplied from the variable displacement pump according to a command value and supplies the fluid pressure cylinder with the pressure control valve.
A fluid type including a pressure holding mechanism that is interposed between the pressure control valve and the fluid supply device and has a closed circuit on the pressure control valve side when the supply pressure to the pressure control valve becomes equal to or lower than a set pressure. In the suspension supply flow controller,
The fluid supply device applies a radial piston pump as the variable displacement pump, and limits the number of pistons for discharge when the discharge pressure of the radial piston pump is less than the set pressure of the pressure holding mechanism, and It is characterized in that the discharge flow rate of the piston is returned to the tank to limit the discharge quantity.

Further, a supply flow rate control device for a fluid type suspension according to a fourth aspect of the present invention is a fluid pressure cylinder interposed between a vehicle body and a wheel, and a variable displacement pump for supplying a working fluid to the fluid pressure cylinder. A fluid supply device including
A pressure control valve for controlling the working fluid supplied from the variable displacement pump according to a command value to supply the fluid pressure cylinder, and a pressure control valve interposed between the pressure control valve and the fluid supply device. In a supply flow rate control device for a fluid type suspension, which comprises a pressure holding mechanism having a closed circuit on the pressure control valve side when the supply pressure becomes equal to or lower than a set pressure,
A flow rate adjusting mechanism capable of limiting the discharge amount of the variable capacity pump is provided between the pressure control valve and the variable capacity pump, and the flow rate adjusting mechanism has a pressure on the downstream side equal to or higher than a set pressure of the pressure holding mechanism. It is characterized by having a pilot operated switching valve that is opened when it becomes open.

[0011]

In the supply flow rate control device for the fluid type suspension according to the first aspect, the variable throttle is disposed in the suction passage of the variable displacement pump, and the opening of the variable throttle is the discharge pressure of the variable displacement pump. When the pressure is equal to or higher than the first set pressure, the minimum opening is increased in accordance with the increase in the discharge pressure, and the second opening is higher than the first setting to the maximum opening. Since the discharge pressure of the variable displacement pump is lower than the first set pressure when the variable displacement pump is started, the discharge pressure is gradually increased by setting the variable throttle to the minimum opening, and then the pressure is increased. When the pressure exceeds the set pressure of the holding mechanism, the closed state of the pressure control valve side by the pressure holding mechanism is released, and the pressure of the fluid pressure cylinder can be controlled by the pressure control valve. Discharge pressure from opening Increases with increasing increases the discharge amount of the variable displacement pump, the maximum opening angle when it reaches the second set pressure, a state capable of ensuring maximum discharge flow rate. For this reason, it is not necessary to provide a flow rate adjusting mechanism between the variable displacement pump and the pressure control valve, and the variable throttle can be of a pilot operated type.

In the fluid suspension supply flow rate control device according to the second aspect, between the tank side port of the variable throttle and the fluid chamber formed between the second spool land portion of the spool and the sleeve. Since the check valve is inserted in the, the movement of the spool from the low-pressure minimum flow rate position to the high-pressure maximum flow rate position is easily permitted, but movement on the opposite side, that is, from the high-pressure maximum flow rate position to the low-pressure minimum flow rate position is fluid. The check valve prevents the fluid discharge in the room, and maintains the maximum flow rate even when the pump discharge pressure drops because a large flow rate is required on the pressure control valve side and prevents the supply pressure from dropping. .

Further, in the supply flow rate control device for the fluid suspension according to the third aspect, a radial piston pump is applied as the variable displacement pump and is connected to the discharge side when the discharge pressure is less than the set pressure of the pressure holding mechanism. By limiting the number of pistons to be discharged and causing the discharge amount of the piston not connected to the discharge side to recirculate to the tank, the supply flow rate control device for the fluid suspension according to claim 1,
It is possible to limit the discharge amount at the time of starting the variable displacement pump without providing a flow rate adjusting mechanism including an electromagnetically operated valve.

Further, in the supply flow rate control device for the fluid suspension according to the fourth aspect, a flow rate adjusting mechanism capable of limiting the discharge rate of the variable displacement pump is provided between the variable displacement pump and the pressure control valve. Since this flow rate adjusting mechanism has a pilot operation switching valve that opens when the pressure on the downstream side of the pressure adjusting mechanism is equal to or higher than the set pressure of the pressure holding mechanism, like an electromagnetically operated switching valve, Costs can be reduced without the need for control circuits or harnesses.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention. In the figure, FS is a fluid pressure supply device, and is a fixed cylinder type radial piston pump 1 that is rotationally driven by being connected to an output shaft 2a of an engine 2 as a rotational drive source,
A flow rate control mechanism 4 constituting a control means interposed between the suction of the pump 1 and the reservoir 3, a line pressure pipe 6S connected to the discharge side of the pump 1 via a check valve 5, and a reservoir. 3 is provided with a return pipe 6R connected through an oil cooler 7, a line pressure pipe 6S is connected to a pulsation absorbing accumulator 8, and a filter 9 is inserted on the downstream side of the accumulator 8. There is. A bypass flow passage is formed in the filter 9 in parallel with the filter 9 when the filter 9 is clogged, and a check valve 10 is inserted in the bypass flow passage.

Here, the pump 1 is, as shown in FIG.
It has a pump housing 13, and this pump housing 1
3, the pump drive shaft 14 has a bearing 1 so as to penetrate therethrough.
It is rotatably supported by 5 and 16. An eccentric cam 14a is integrally formed on the pump drive shaft 14 between its bearings 15 and 16, and the eccentric cam 14a is housed in a suction chamber 17 formed in the pump housing 13. A ring 18 is rotatably fitted on the outer circumference of the eccentric cam 14a, and, for example, ten radial pistons 19 (only one is shown in the drawing) are provided oppositely on the outer circumference of the ring 18 at equal intervals in the circumferential direction. Each of these radial pistons 19
Are slidably fitted in corresponding fixed cylinders 20 formed in the pump housing 13 by extending in the radial direction of the eccentric cam ring 18. The external opening end of the fixed cylinder 20 is closed by a plug 21, and a discharge chamber 22 is defined between the plug 21 and the radial piston 19.

Each radial piston 19 has a bottomed sleeve shape in which the end near the eccentric cam ring 18 is closed.
The spring 23 presses the eccentric cam ring 18.
Then, a side port 24 is formed on the peripheral wall of each radial piston 19 at a position where the radial piston 19 projects into and out of the suction chamber 17 during the stroke of the radial piston. Pump drive shaft 1
The rotating shaft 2 of the engine 2 with the right end in FIG.
A portion of the pump drive shaft 14 that is connected to a and is close to this is sealed with respect to the pump housing 13 by a seal 25.
The other end of the pump drive shaft 14 is sealed by a seal 27 with respect to a passage member 26 attached to the pump housing 13. The passage member 26 has a suction passage 28 and a discharge passage 29, and the discharge passages 29 are formed in the same number as the fixed cylinders 20. The suction passage 28 communicates with the suction chamber 17 through a communication port 30 formed in the pump housing 13.
Each discharge passage 29 is connected to the corresponding discharge chamber 22 by a communication port 31 formed in the pump housing 13.

A delivery valve 32 is provided between the communication port 31 and the discharge passage 29. This valve opens when a pressure equal to or higher than the valve opening pressure is supplied from the communication port 31 to the discharge passage 29 through the working fluid. Is used, and no type of working fluid in the opposite direction is allowed. An end cover 33 is additionally provided on the side of the passage member 26 far from the pump housing 13, and a single groove 34 communicating with all the discharge passages 29 is formed in the end lid 33, and the discharge port 3 reaching this groove is formed.
5 is formed, and the line pressure pipe 6S is connected to the discharge port 35.
Are connected.

The flow rate control mechanism 4 adjusts the amount of working fluid that has reached the suction circuit 40 from the reservoir 3 and flows into the suction passage 28 of the piston pump 1, and is provided with a spool valve 41 as valve means. There is. This spool valve 41
Is configured by slidably fitting a spool 43 in a sleeve 42, and should communicate with the tank side port 44 to which the suction circuit 40 connected to the reservoir 3 is connected to the sleeve 42 and the suction passage 28 of the piston pump 1. Pump side port 4
5 are formed adjacent to each other in the axial direction. The spool 43 has a first spool land portion 43 and a second spool land portion 43 at both axial ends.
a and 43b are formed, and these spool land portions 43 are formed.
A small-diameter spool rod portion 43c is formed between a and 43b, and the axial length of the spool rod portion 43c is equal to the length from the right end of the tank side port 44 to the left end of the pump side port 45 as shown in FIG. The variable throttles 46 and 47 which are selected and whose opening changes according to the stroke are formed by the pump side port 45, the tank side port 44, and the spool rod portion 43c. Spool 43
A feedback plunger 48 to which the discharge pressure of the piston pump 1 is supplied as a displacement control pressure is arranged at the left end of the sleeve opposed to the left end in the drawing, and is screwed to the right end in the drawing of the spool 43 and the right end of the sleeve 42. A coil spring 50 as a first biasing means for biasing the end plate 49 to the low pressure minimum flow rate position side that closes the tank side port 44 with the second spool land portion 43b is interposed between the end plate 49 and the end plate 49. In addition, the spool 4 is provided on the inner peripheral surface on the right end side of the sleeve 42.
A spring seat 51 having a flange 51a that engages with the right end of the spring seat 3 is provided. Between the flange 51a of the spring seat 51 and the end plate 49, a coil spring 50 is concentrically provided as a second urging means. The coil spring 52 is inserted.

Here, the set load of the coil spring 50 is
Pilot operated check valve 66 of pressure holding portion 61 described later
Discharge pressure higher than the set pressure of feedback plunger 4
8, the thrust generated by the plunger 48 sets the spool 43 to the first set load in which the spool 43 moves to the right, and the set load of the coil spring 52 is greater than the maximum supply pressure higher than the set load of the coil spring 50. When the discharge pressure of (1) acts on the feedback plunger 48, the spool 43 is set to the second set load that operates from the high pressure maximum flow rate position to the high pressure minimum flow rate position by the thrust generated by the plunger 48.

Further, the pump side port 4 of the sleeve 42
5 and the spool rod portion 43c of the spool 43, the variable throttle 46 has a minimum flow rate at a low pressure minimum flow rate position where the left end of the spool 43 is in contact with the left inner wall of the sleeve 42, as shown in FIG. The tank side port 44 of the sleeve 42 is set to have the smallest opening area.
The variable throttle 47 formed by the spool rod portion 43c of the spool 43 has a minimum flow rate at the high pressure minimum flow position where the spool 43 moves to the right against both coil springs 50 and 52 as shown in FIG. It is set to have the opening area.

Therefore, the flow rate input to the piston pump 1 from the flow rate adjusting mechanism 4, that is, the discharge flow rate of the piston pump 1 is, as shown in FIG. Since it is held at the flow rate position, the minimum flow rate _QLMIN on the low pressure side is maintained, and from this state, the pilot operated check valve 6 of the pressure holding unit 61 is
Feedback plunger 48 _exceeding the set pressure P _{P0 of} 6
When the thrust of the first discharge pressure P _O1 exceeds the set load of the coil spring 49, the spool 43 moves to the left, so that the discharge flow rate of the piston pump 1 rapidly increases and the spool 4
When the left end of No. 3 comes into contact with the spring seat 51, the maximum discharge flow rate Q _MAX is reached, and thereafter the discharge pressure becomes the second discharge pressure P.
_When it becomes _O2 or more, the spool 43 becomes the spring seat 51.
As the discharge pressure increases, the discharge flow rate gradually decreases, and when the pump-side port 45 is blocked by the spool land portion 43a of the spool 43, the discharge flow rate becomes zero.

The line pressure pipe 6S and the return pipe 6
The other end of R is connected to the input port and the return port of the pressure control valves 63FL to 63RR corresponding to each wheel via the pressure holding portion 61 and the fail-safe valve 62. The pressure holding portion 61 includes a check valve 64 inserted in the line pressure pipe 6S.
And a normal line pressure setting relief valve 65 for setting a normal line pressure P _L (kg / cm ² ) interposed between the line pressure pipe 6S and the return pipe 6R, and a downstream side of the fail-safe valve 62. And a pilot operated check valve 66 to which the line pressure is supplied as the pilot pressure P _P. Here, the pilot operated check valve 66 has a pilot pressure P
_{When P} is equal to or higher than a predetermined neutral pressure P _N set in advance, the check valve function is released and the upstream side and the downstream side are in an open state, and the pilot pressure P _P is the neutral pressure P _N. When it is less than the above, the check valve function is actuated to close the upstream side and the downstream side.

The fail-safe valve 62 is a spring-offset 4-port 2-position electromagnetic switching valve. The P-port is connected to the pressure holding portion 61 downstream of the check valve 64 and the pilot operated check valve. R port connected to input port 66i of 66 and pressure control valves 63FL to 63RR
Of the solenoid 6 having an A port connected to the input port 71i and a B port connected to the return port 71o.
The abnormality detection signal AS supplied to 2a is in the off state,
At the normal switching position switched by the return spring 62b, the P port and the R port are shut off and the A port and the B port are communicated with each other, and the abnormality detection signal AS supplied to the solenoid 62a is turned on and the offset occurs. A communication passage that directly communicates the P port and the A port at the switching position and a communication passage that directly communicates between the R port and the B port are formed. Further, an external fixed throttle 6 is provided between the R port and the B port of the fail-safe valve 62.
It is communicated via 2c. Then, the solenoid 62a of the fail-safe valve 62 is controlled by a control signal CS ₁ from the control device 100 described later.

Each of the pressure control valves 63FL to 63RR is
It has an input port 71i, a return port 71o, and a control pressure port 71c, and makes the control pressure port 71c, the input port 71i, and the return port 71o in a closed state, or the control pressure port 71c, the input port 71i, and the return port 71.
There is a spool that switches to a communication state in which it communicates with either one of o, the supply pressure and the control pressure are supplied as pilot pressure to both ends of this spool, and a poppet valve controlled by the proportional solenoid 72 is further provided on the supply pressure side. With the configuration provided, the pressure of the control pressure port 71c is controlled so as to always be the pressure corresponding to the exciting current supplied from the control device 100 described later to the proportional solenoid 72.

The input port 71i is connected to the A port of the failsafe valve 62, the return port 71o is connected to the B port of the failsafe valve 62, and the control port 71c is connected to the hydraulic cylinder 69 via the hydraulic pipe 68.
It is connected to the pressure chamber 70 of FL to 69RR. Here, the relationship between the exciting currents I _{FL to} I _RR and the control oil pressure P _C output from the control port 21c is as shown in FIG. 6, when the command values I _{FL to} I _RR are near zero, P _MIN When the command values I _{FL to} I _RR increase in the positive direction from this state, the control oil pressure P _C increases with a predetermined proportional gain K ₁ and the saturation occurs at the set line pressure P _L of the pressure holding unit 11. To do.

The pressure control valves 63FL and 63FR
A back pressure absorbing accumulator 81F is connected to a return pipe 80F that communicates between the return port 71o and the B port of the fail-safe valve 62, and the pressure control valves 63RL and 6RL are provided.
A back pressure absorbing accumulator 81R is connected to the return pipe 80R that communicates between the return port 71o of the 3RR and the B port of the fail-safe valve 62, and the back pressure absorbing accumulator 81R is connected to the return pipe 80R by the pipe resistance of pressure oil flowing through the return pipes 80F and 80R. It absorbs the generated back pressure.

Reference numeral 82F is A of the fail-safe valve 62.
The accumulator for pressure accumulation connected to the hydraulic pipe between the port and the input port 71i of the pressure control valves 63FL and 63FR, and 82R to the hydraulic pipe between the A port of the fail-safe valve 62 and the input port 71i of the pressure control valves 63RL and 63RR. Accumulators for pressure accumulation connected, 83 and 8
Reference numeral 4 denotes a damping valve and an accumulator for absorbing a pressure fluctuation in a high frequency range of vehicle unsprung vibration from the road surface input to the hydraulic cylinders 69FL to 69RR, and 85F and 85R.
Is a check valve for releasing the abnormal high pressure to the line pressure pipe 6S when the high pressure is generated in the return pipes 80F, 80R, 86F,
86R is always the back pressure of the return pipe 6R, 80F, 80R
This is a throttle for preventing oil column separation of the return pipe 6R by keeping it at kgf / cm ² .

Further, hydraulic cylinders 69FL to 69RR
Each has a cylinder tube 69a, in which a pressure chamber 70 defined by a piston 69b is formed, and the cylinder tube 6a
The lower end of 9a is attached to the wheel side member, and the tip of the piston rod 26c is attached to the vehicle body side member. The control device 100 receives a detection signal from a posture change detector 101 for detecting a posture change of a vehicle body such as a vehicle height sensor for detecting a displacement between a vehicle body and wheels, a lateral acceleration sensor, and the like, and a power supply circuit, Fluid pressure supply device FS, pressure control valve 63F
Abnormal state detector 1 for detecting an abnormal state such as L to 63RR
The attitude change detector 1 receives the abnormality detection signal from
Based on the detection signal from 01, a predetermined attitude change suppressing process is executed to calculate a command value for suppressing the attitude change, and the exciting currents I _{FL to} I _RR corresponding thereto are set to the pressure control valves 63FL to 6FL.
The control signal CS ₁ that is output to the 3RR proportional solenoid 72 and that is supplied to the fail-safe valve 62 based on the abnormality detection signal from the abnormality state detector 102 is forcibly turned off. Further, the control device 100 is turned on when the ignition switch is turned on to start execution of the posture change suppressing process, and turns on the control signal CS ₁ for the failsafe valve 62,
When the ignition switch is turned off, the self-holding timer keeps the power on for a predetermined time to continue the posture change suppressing process, and at the same time, the control signal CS ₁
Keeps on.

Next, the operation of the above embodiment will be described with reference to the time chart of FIG. Now, assuming that the ignition switch is off and the engine 2 is stopped, the pilot operated check valve 66 of the pressure holding portion 61 is
Is fully closed and the pilot operated check valve 66
And the main check valve 64, the fail-safe valve 62,
Pressure control valves 63FL to 63RR and hydraulic cylinder 69F
It is assumed that the hydraulic control system including L to 69RR is in the pressure holding state.

In this state, when the ignition switch is turned on at time t ₁ and the engine 2 is started, the drive shaft 14 of the piston pump 1 is rotationally driven accordingly. Since the pressure is close to zero, the spool 43 of the flow rate adjusting mechanism 4 is shown in FIG.
At the low pressure minimum flow rate position shown in Fig. 4, the variable throttle 46 formed between the spool rod portion 43c and the pump side port 45 has the minimum opening area, and the discharge flow rate of the piston pump 1 becomes the minimum flow rate. ing. However,
When the engine is started, the pressure holding portion 61 is in a pressure holding state, so that the working oil is not supplied to the fail-safe valve 62 side through the main check valve 64, and the pulsation absorption connected to the line pressure pipe 6S is absorbed. Since the accumulator 8 for use has a small capacity, the discharge pressure of the piston pump 1 rapidly increases as shown in FIG. 7 (c). On the other hand, the fail-safe valve 62 is also controlled to the open state when the control signal CS ₁ from the control device CD is turned on.

After that, at time t ₂ , when the discharge pressure of the piston pump 1 becomes equal to or higher than the holding pressure sealed by the main check valve 64 of the pressure holding portion 61, the main check valve 64 is opened and the main check valve 64 is opened. The holding pressure on the downstream side of the stop valve 64 increases, and accordingly the vehicle height gradually increases as shown in FIG. 7 (d), and the discharge flow rate of the piston pump 1 maintains the minimum flow rate state. To do.

When the holding pressure on the downstream side of the main check valve 64 reaches the set pressure of the pilot operated check valve 66 at time t ₃ , the pilot operated check valve 66 is opened, which causes The pressure holding state by the pressure holding portion 61 is released. In response to this, the pressure control valves 63FL-6FL
3RR will start normal function, and the vehicle height will be as shown in Fig. 7.
As shown in (d), the vehicle height is maintained at an appropriate level, and the discharge flow rate of the piston pump 1 is maintained at the minimum flow rate state.

Therefore, the discharge pressure of the piston pump 1 continues to gradually increase, and at the time t ₄ , the piston pump 1 is discharged.
The discharge pressure of the feedback plunger 48
When the thrust force exceeds the first discharge pressure P _O1 which is equal to or more than the set load of the coil spring 50, the spool 43 moves to the right to reach the high pressure maximum flow rate position side shown in FIG. Rapidly increases and reaches the maximum discharge flow rate Q _MAX when the right end of the spool 43 reaches the second discharge pressure P _{O2 at} which it abuts on the spring seat 51. Therefore, the fluid pressure on the downstream side of the main check valve 64 suddenly rises as shown in FIG. 7 (b).

After that, when the thrust of the feedback plunger 48 becomes the second discharge pressure P _O2 or more that exceeds the set load of the coil springs 50 and 52 as the discharge pressure of the piston pump 1 suddenly increases, the spool 43 causes the spring seat 5 to move.
When it moves to the right with 1 to the high pressure minimum flow rate position shown in FIG. 4, the discharge flow rate gradually decreases as the discharge pressure increases, and the pump side port 45 is blocked by the spool land portion 43a of the spool 43. The discharge flow rate becomes zero, and the discharge pressure of the piston pump 1 is controlled to the maximum discharge pressure P _MAX as shown in FIG. 7 (c).

Therefore, in this state, for example, when the vehicle is started and a so-called scut phenomenon occurs in which the front wheel side floats up and the rear wheel side sinks, a so-called scut phenomenon is suppressed from the control device 100 to the rear wheel side. Pressure control valve 63RL,
When the pressure command current for increasing the pressure is output to the 63RR, and the pressure on the downstream side of the main check valve 64 is reduced by this, the feedback plunger 48
When the thrust of the piston pump 1 is reduced, the spool 43 is pushed back by the coil springs 50 and 52.
The discharge flow rate is increased to compensate for the pressure drop in the supply side pipe 6S. Similarly, when the vehicle is running on a bad road,
When the working fluid consumption amount in the pressure control valves 63FL to 63RR is significantly increased, the pressure of the supply side pipe 6S is correspondingly reduced, and the thrust of the feedback plunger 48 is also reduced, and accordingly, the piston pump is reduced. The discharge flow rate of 1 increases to compensate for the pressure drop of the supply side pipe 6S.

As described above, according to the first embodiment, in the spool 43 of the flow rate adjusting mechanism 4 which constitutes the variable throttle inserted on the suction side of the piston pump 1, the discharge pressure of the piston pump 1 is the pressure holding portion. Until it reaches the first set pressure P _O1 which is slightly higher than the set pressure of the pilot operated check valve 66 of 61, it is maintained at the opening position where the minimum flow rate on the low pressure side is reached and exceeds the first set pressure P _O1 . The opening degree increases in accordance with the increase in the discharge pressure of the piston pump 1, and the maximum opening degree is set at the second setting pressure P _O2 higher than the first setting pressure P _O1. Immediately after being turned on, in a state where the pressure holding portion 61 holds the pressure on the pressure control valves 63FL to 63RR side, a rapid increase in the discharge pressure of the piston pump 1 is suppressed and the pressure rises gently. To loosen Can, it is not necessary to provide a separate flow rate adjustment mechanism, can also be omitted control system therefor,
The entire structure can be simplified.

In the first embodiment, the case where one spool valve is provided as the flow rate adjusting mechanism 4 has been described, but the present invention is not limited to this, and as shown in FIG. A spool valve 41A provided with a coil spring 50A set to a set load equivalent to 50;
Spool valve 41B having coil spring 52B set to a combined set load of coil spring 50 and coil spring 52
And may be connected in series to configure a flow rate adjusting mechanism equivalent to the spool valve 41.

Next, a second embodiment of the present invention will be described with reference to FIGS.
Will be described. In the second embodiment, when the discharge pressure of the piston pump 1 maintains the rated pressure in the first embodiment and a large flow rate is suddenly required on the pressure control valves 63FL to 63RR side, The maximum flow rate is ensured and the hydraulic control system is maintained in a good state.

Therefore, the spool valve 41 in the first embodiment is modified as shown in FIG. That is,
The thrust of the feedback plunger 48 is the coil spring 50.
When the spool 43 is at the low pressure minimum flow position and is less than the set load of
Of the tank side port 44 and the pump side port 45 to ensure the minimum flow rate at this time.
A fixed throttle 52L for compensating the minimum flow rate at low pressure is provided for communicating with each other, and the thrust of the feedback plunger 48 is equal to or larger than the combined set load of the coil springs 49 and 51, so that the spool 43 is at the high pressure minimum flow rate position. ,
The pump side port 45 is closed by the land of the spool 43, and in order to secure the minimum flow rate at this time, a fixed throttle 52H for communicating the tank side port 44 and the pump side port 45 for high pressure minimum flow rate compensation is provided. A damping orifice 53 is provided between the suction circuit 40 and the spring storage chamber on the right end side of the spool 43, and the spool 43 is located on the left end side of the sleeve 42 in the low pressure minimum flow position and the high pressure maximum flow position. 43 is blocked by the land 43a, the spool 43
Is provided with an adjustment port 54 whose opening area increases with the movement of the high pressure maximum flow rate position to the high pressure minimum flow rate side. The adjustment port 54 and the pump side port 45 are connected to each other. In addition, the passage of hydraulic oil from the opening 55 to the pump side port 45 and the adjustment port 54 is blocked between the adjustment port 54 and the opening 55 on the left side of the adjustment port 54 of the sleeve 42, and 2 has the same configuration as that of the above-described first embodiment except that a check valve 56 that allows the passage of hydraulic oil to and from is provided. The detailed description thereof will be omitted.

According to the second embodiment, when the piston pump 1 is driven by starting the engine, the discharge pressure of the piston pump 1 is low and the thrust of the feedback plunger 48 is smaller than the set load of the coil spring 50. As shown in FIG. 9, at the low pressure minimum flow position,
The minimum flow rate is maintained as shown in FIG. In this state, the adjustment port 54, the opening 55, and the pump-side port 45 are closed by the lands 43a and 43b of the spool 43, but the tank-side port 44 and the pump-side port 45 are fixed throttles. It is communicated via 52L, and it is possible to ensure the same operation for gently increasing the discharge pressure as in the first embodiment described above.

When the discharge pressure of the piston pump 1 exceeds the first discharge pressure P _{O1 at} which the thrust of the feedback plunger 48 is equal to or greater than the set load of the coil spring 50 while the spool 43 is at the low pressure minimum flow rate position. The spool 43 has the spring seat 51 as in the first embodiment.
The by rightward movement in high maximum flow position illustrated in Figure 10 abuts the discharge flow rate of the piston pump 1 is maximized discharge flow rate Q _MAX soared as shown in FIG. 12. At this time,
When the spool 43 moves from the low pressure minimum flow rate position to the high pressure maximum flow rate position, negative pressure is generated in the opening 55 on the left end side of the spool 43 as the spool 43 moves to the right. The portion 55 is communicated with the tank side port 44 via the check valve 56, and since the check valve 56 allows passage of hydraulic oil from the tank side port 44, the tank side port 44 is provided with the check valve 56. By supplying the hydraulic oil from 44, the smooth right movement of the spool 43 can be ensured, and moreover, the opening portion on the right side of the spool 43 is communicated with the reservoir tank 3 via the damping orifice 53. The vibration of the spool 43 can be suppressed by exerting an appropriate damping effect when the spool 43 moves.

As described above, when the spool 43 reaches the high-pressure maximum flow rate position, the discharge pressure of the piston pump 1 rapidly increases, which causes the feedback plunger 48.
When the thrust force exceeds the second discharge pressure P _O2 which exceeds the set load of the coil springs 50 and 52, the spool 43 moves rightward together with the spring seat 51 to the high pressure minimum flow position, and the discharge pressure of the piston pump 1 reaches the maximum discharge. The constant pressure is controlled to the pressure P _MAX . When the spool 43 moves from the high pressure maximum flow rate position to the high pressure minimum flow rate side, the adjustment port 54 is opened, and the adjustment port 54 is always in communication with the tank side port 44. Not only the movement but also the discharge pressure of the piston pump 1 is reduced and the thrust of the feedback plunger 48 is reduced, so that the left hydraulic oil in the opening 55 passes through the adjustment port 54 even when the spool 43 moves to the left. Tank side port 44
As a result, the spool 43 can be smoothly moved to the left.

However, when the spool 43 is positioned between the high pressure maximum flow rate position and the high pressure minimum flow rate position, for example, the posture changes such as roll, pitch and bounce occur simultaneously on the vehicle body, so that the pressure control valves 63FL to 63FL. 63RR
When a very large flow rate is suddenly required due to a rapid increase in the consumption pressure at the piston pump 1, the discharge pressure of the piston pump 1 sharply decreases, the thrust of the feedback plunger 48 sharply decreases, and the spool 43 becomes The coil springs 50 and 52 return the pressure to the low pressure minimum flow position side. At this time, the adjustment port 54 maintains the open state until the high pressure minimum flow position reaches the high pressure maximum flow position. Since the hydraulic oil of the portion 55 is returned to the tank side port 44, the left movement of the spool 43 is smoothly performed.
However, when the spool 43 is near the high-pressure maximum flow rate position, the check valve 56 prevents the hydraulic oil from flowing out to the tank-side port 44 in the opening 55 itself, and the opening area of the adjustment port 54 gradually decreases. By becoming
When the amount of hydraulic oil flowing out from the opening 55 on the left end side of the spool 43 is gradually reduced, the left moving speed of the spool 43 is reduced accordingly, and when the spool 43 reaches the high pressure maximum flow rate position, the spool 43 moves. Since the adjusting port 54 is closed by the land 43a, the hydraulic oil in the opening 55 on the left side of the left end of the spool 43 is blocked and confined, so that the left movement of the spool 43 is suppressed and the spool 43 is prevented. 43 is held near the high pressure maximum flow rate position. As a result, as shown by the characteristic curve L in FIG. 12, the problem that the discharge flow rate of the piston pump 1 is sharply reduced by the spool 43 immediately returning to the low pressure minimum flow rate position is solved, and the discharge flow rate is increased to the maximum flow rate Q _MAX. Since it can be maintained, it is possible to compensate for the decrease in the supply pressure.

After that, each pressure control valve 63FL to 63RR
When the consumption amount in the piston pump 1 decreases, the discharge pressure of the piston pump 1 recovers to the maximum discharge pressure P _MAX , and accordingly, the spool 43
Moves to the right, but at this time, as described above, the check valve 5
Since the hydraulic oil is supplied from 6 to the opening 55, the spool 43 can be smoothly moved to the right, and the time required to widen the rated flow rate can be shortened.

When the vehicle stops running and the engine 2
When the piston pump 1 is stopped, the piston pump 1 is also stopped, so that the discharge pressure thereof sharply decreases, and as described above, the leftward movement of the spool 43 from the high pressure maximum flow position to the low pressure minimum flow position side is suppressed. Spool 4
Since there is a gap between the land 43a of No. 3 and the inner diameter of the sleeve 42, the left hydraulic oil trapped in the opening 55 on the left end side of the spool 43 flows out through this gap, so that the spool 43 finally has a low pressure. When the engine is restarted after that, the control is started from the state where the discharge flow rate is throttled, and the vehicle height does not suddenly change. Also, engine 2
When the engine 2 is restarted when the spool 43 is on the high pressure maximum flow rate position side before returning to the low pressure maximum flow rate position, the state where the discharge flow rate of the piston pump 1 is high continues, In this case, there is almost no change in vehicle height when the engine 2 is stopped, so there is no possibility of a sudden change in vehicle height.

As described above, according to the second embodiment, in the normal control state in which the spool 43 is between the high pressure maximum flow rate position and the high pressure minimum flow rate position, a rapid decrease in the discharge pressure of the piston pump 1 due to a rapid increase in the consumed flow rate occurs. When the spool 43
Since it is possible to maintain the maximum flow rate state by suppressing the movement to the low pressure minimum flow rate side, it is possible to promptly return to the maximum discharge pressure P _MAX when the consumption flow rate decreases, so that the spool 43 By reducing the discharge flow rate of the piston pump 1 on the low pressure minimum flow rate side, it is possible to reliably avoid a further decrease in the discharge pressure of the piston pump 1 and a long recovery time to the maximum discharge pressure.

Next, a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, the discharge flow rate of the piston pump 1 is controlled by whether or not the discharge quantity of the required number of radial pistons 19 among the six radial pistons 19 constituting the piston pump 1 is returned to the reservoir tank 3. It is something that is done.

That is, as shown in FIGS. 13 and 14, one of the six radial pistons 19a to 19f in which the fixed cylinder radial piston pump 1 is arranged around the pump drive shaft 14 at equal angular intervals. For example, the discharge passage 19a of the radial piston 19a is connected to the discharge port 35A via the passage member 34A, and the discharge passages 19b to 19f of the remaining five radial pistons 19b to 19f form an arc-shaped passage member 34B. It has the structure connected to the discharge port 35B through.

Further, the spool valve 41 of the flow rate adjusting mechanism 4
However, as shown in FIG. 13, as in the conventional example, the spool 43
Is urged to the left by only the coil spring 50, and the discharge pressure of the hydraulic oil discharged from the piston pump 1 is supplied to the position of the sleeve 42 facing the left end of the spool 43 via the orifice 39, and Spool 43
The axial length of the spool rod portion 43c is selected to be substantially equal to the center-to-center length of the tank side port 44 and the pump side port 45, and when the discharge pressure of the piston pump 1 is low, the spool 43 is located on the left side of the tank side port 44. When the thrust for moving the spool 43 to the right due to the increase in the discharge pressure exceeds the set load of the coil spring 50, the spool 43 moves to the right according to the increase in the discharge pressure. However, the variable throttle 46 formed by the pump side port 45 and the spool rod portion 43c is configured to move to the high-pressure minimum flow rate position where the minimum opening is obtained.

The discharge port 35A of the radial piston pump 1 is directly connected to the working pressure circuit 38, the discharge port 35B is connected to the working pressure circuit 38 via the check valve 57, and the discharge port 35B and the check valve. A pilot operation switching valve 58 at 2 ports and 2 positions is interposed between a connection point between 57 and the reservoir tank 3. The pilot operation switching valve 58 has a pilot port whose operating pressure circuit 38.
And a normal switching position for communicating between the input and output ports when the operating pressure of the operating pressure circuit 38 is less than the pilot setting pressure slightly higher than the preset setting pressure of the pilot operated check valve 66. When the pressure is equal to or higher than the pilot set pressure, it is configured to take an offset switching position that shuts off between the input and output ports.

According to the third embodiment, since the pump drive shaft 14 is stopped when the engine 2 is stopped, the discharge pressure and discharge flow rate of each radial piston 19a to 19f are shown in FIG. 15 (a). And as shown in (b), it is zero, and the pilot operation switching valve 58 can be switched to the normal position. When the engine 2 is started from this stop state at time t ₁ in FIG. 15, the pump drive shaft 14
Is driven to rotate, so that each radial piston 19
The hydraulic oil is discharged from a to 19f, but at this time, the pilot operation switching valve 58 is in the normal position, so the hydraulic oil discharged from the radial pistons 19b to 19f is stored in the reservoir tank 3 via the pilot operation switching valve 58. Only the hydraulic oil discharged to the working pressure circuit 38 is discharged to the working pressure circuit 38. Therefore, at the time point t ₁ , the pump discharge flow rate and the pump discharge pressure are 1
It rises by only one radial piston 19a.

At time t ₁ , the pilot operated check valve 66 of the pressure holding portion 61 is maintained in the closed state, and the check valve 64 and the check valve 64 allow the pressure control valves 63FL to 63FL to 63FL.
Since the RR side is maintained at the set pressure, the discharge flow rate of the piston pump 1 is only supplied before the check valve 64 of the line pressure pipe 6S, and hence the discharge flow rate from one radial piston 19a is constant thereafter. However, since the capacity of the line pressure pipe 6S is small, the pump discharge pressure gradually increases, and when the filled pressure in the pressure holding portion 64 is reached at time t ₂ ,
The pilot operated check valve 66 of the pressure holding portion 64 is opened, but at this time, each pressure control valve 63FL to 63RR
Assuming that the hydraulic oil is not consumed at, the pump discharge pressure rises further, and at time t ₃ , the pilot operation switching valve 58
When the pilot set pressure of is reached, the pilot operation switching valve 58 can be switched to the offset position.
By this, each radial piston 1 of the piston pump 1
Since the drain passages 9b to 19f to the reservoir tank 3 are blocked, the discharge flow rate of each radial piston 19b to 19f is supplied to the working pressure circuit 38 in addition to the discharge flow rate of the radial piston 19a. Therefore, the pump discharge flow rate rapidly increases at the time point t ₃ , and the pump discharge pressure rapidly increases accordingly. Next, when the pump discharge pressure reaches the set pressure at time t ₄ , the spool 4 of the flow rate adjusting mechanism 4
3 moves to the right against the coil spring 50, which reduces the opening of the variable throttle 46 to reduce the discharge flow rate of the piston pump 1 and when there is no pressure fluctuation in the line pressure pipe 6S, the spool 43 Reaches the high pressure minimum flow rate position, and the pump discharge flow rate is set to the minimum value.

As described above, also in the third embodiment, since the discharge flow rate of the piston pump 1 is limited when the engine 2 is started, the discharge pressure of the piston pump 1, that is, the pressure increase of the line pressure pipe 6S, is increased. Since it is performed gently, it is possible to prevent a sudden change in vehicle height with a simple configuration. Next, a fourth embodiment of the present invention will be described with reference to FIGS.

In the fourth embodiment, instead of controlling the discharge flow rate in the piston pump 1, a flow rate control valve provided in the line pressure pipe 6S is used to prevent a sudden increase in pressure at engine startup. . That is, as shown in FIG. 16, the piston pump 1 and an ordinary constant-volume pump are applied, and the pilot operation switching valve of the 2-port 2-position is provided downstream of the check valve 64 of the line pressure pipe 6S in the pressure holding portion 61. And a bypass pipe 6 disposed in parallel with the pilot operation switching valve 67.
8, a fixed throttle 69 is interposed, a pilot port of the flow control valve 67 is connected to a confluence point with the bypass pipe 68 on the downstream side of the flow control valve 67, and the flow control valve 67 has a pilot set pressure P _PS. is set to a value slightly higher than the pilot set pressure of the pilot-operated check valve 66, it takes the normal position to block the line pressure line 6S when the pilot pressure is lower than the pilot set pressure P _PS, pilot set pressure P _PS or In this case, the line pressure pipe 6S has the same configuration as that of the above-described first embodiment except that the line pressure pipe 6S is set to the offset position so that the line pressure pipe 6S is in the communicating state.

According to the fourth embodiment, as shown in FIG. 17, the discharge pressure of the piston pump 1 is changed by starting the engine 2 at time t ₀ and setting the fail-safe valve 62 to the offset position as shown in FIG. As shown in (c),
The check valve 64 rises abruptly and exceeds the holding pressure held by the pressure holding portion 61 at time t ₁ to open the check valve 64. At this time, the flow control valve 67, which is the pilot pressure of the flow control valve 67, opens. Since the downstream pressure is lower than the pilot pressure set value P _PS as shown in FIG. 17B, the flow rate control valve 67 is in the normal position and shuts off the line pressure pipe 6S. The hydraulic oil to be supplied is supplied to each of the pressure control valves 63FL to 63RR via the fixed throttle 69 provided in the bypass pipe 68, and the pressure on the downstream side of the flow control valve 67 is shown in FIG. 17 (b). As shown in FIG. 17, the vehicle height increases accordingly.
It gradually increases as shown in (d).

After that, at time t ₂ , the discharge pressure of the piston pump 1 reaches the set pressure of the relief valve 65, so that the relief valve 65 operates to maintain the supply pressure at a constant pressure. On the other hand, the pressure increase on the downstream side of the flow control valve 67 is still gradually increasing, and when the pilot set pressure of the pilot operated check valve 66 is reached at time t ₃ , the check valve 66 is opened. As a result, the pressure in the return pipe 6R on the upstream side is rapidly reduced from the enclosed pressure to zero, as shown in FIG. 17A, and the attitude change suppression control such as vehicle height adjustment by the pressure control valves 63FL to 63RR is performed. Then, when the pressure on the downstream side of the flow rate control valve 67 reaches the pilot set pressure P _PS at time t ₄ , the flow rate control valve 67 is switched to the offset position and the line pressure piping 6S is shut off. When the flow control valve 6 is released, the communication state is established.
7 downstream pressure rapidly increases the time point t ₅ at a flow rate control valve 6
When the pressure on the downstream side of 7 reaches the supply pressure, the pressure is maintained at a constant value.

As described above, according to the fourth embodiment as well, the flow control valve is controlled so that the hydraulic pressure supplied to the pressure control valves 63FL to 63RR gradually rises when the engine is started. Can be suppressed, and riding comfort can be improved. In addition, in each of the above-described embodiments, the case where the common pressure holding portion 61 and the fail-safe valve 62 are provided for each pressure control valve has been described, but the pressure holding portion 61 and the fail-safe valve 62 are not limited to this. You may make it provide separately.

Furthermore, in the above embodiment, the case where the rotational driving force of the hydraulic pump 1 is obtained from the engine 2 has been described, but the present invention is not limited to this, and a rotational driving source such as an electric motor is provided. Needless to say, can be applied. Furthermore, the control valve of the hydraulic suspension is not limited to the pressure control valves 63FL to 63RR, but other flow rate control type servo valves or the like can be applied.

In the above embodiment, the case where the working oil is used as the working fluid has been described, but the working fluid is not limited to this, and any working fluid may be applied as long as the fluid has a low compression rate. .

[0061]

As described above, according to the supply flow rate control device for the fluid type suspension of the first aspect, the variable throttle which opens and closes according to the change of the discharge pressure is provided in the suction passage of the variable displacement pump of the fluid supply device. The variable throttle increases in opening degree from the minimum opening degree in accordance with an increase in discharge pressure when the discharge pressure becomes equal to or higher than a first set pressure higher than the set pressure of the pressure holding mechanism, and the first set pressure is increased. Since the maximum opening is achieved at the higher second set pressure, when the variable displacement pump is started, the pressure of the fluid pressure cylinder can be controlled by the pressure control valve before the variable throttle is opened. The discharge amount of the variable displacement pump is increased by increasing the degree from the minimum opening degree according to the rise of the discharge pressure, and reaches the maximum opening degree when the second set pressure is reached, so that the maximum discharge flow rate can be secured. State, engine start A pilot that can suppress a sudden change in vehicle height at the time, does not require a flow rate adjusting mechanism between the variable displacement pump and the pressure control valve, and does not require external control of the variable throttle. It is possible to obtain the effect that the operation-type configuration can be completed.

According to the supply flow rate control device of the fluid type suspension of claim 2, the variable throttle is provided with a spool having a low pressure minimum flow rate position, a high pressure maximum flow rate position and a high pressure minimum flow rate position according to the discharge pressure of the pump. And a structure in which a check valve is provided, which supplies hydraulic oil to the fluid chamber in the moving direction of the spool but prevents discharge when the spool moves from the high pressure maximum flow position to the low pressure minimum flow position side. Therefore, it is possible to prevent a sudden change in the vehicle height at the time of starting the engine, and of course, in the normal control state, when the consumption flow rate temporarily increases on the pressure control valve side and the discharge pressure of the pump decreases, the spool It is possible to suppress the movement to the side of the minimum bottom flow rate position, and to shorten the discharge pressure recovery time when the discharge flow rate of the pump decreases and the consumed flow rate returns to its original value. That effect can be obtained.

Further, according to the supply flow rate control device of the fluid suspension of the third aspect, the radial piston pump is applied as the variable displacement pump, and the discharge pressure of the radial piston pump is less than the set pressure of the pressure holding mechanism. Since it is configured to limit the number of pistons for discharge at one time and to recirculate the discharge flow rate of the remaining pistons to the tank to limit the discharge amount, a simple selection means such as a switching valve for selecting the number of pistons. With a simple configuration that only requires
Similar to the first aspect, it is possible to obtain the effect that it is possible to suppress a rapid change in vehicle height when the engine is started.

Further, according to the supply flow rate control device of the fluid suspension of the fourth aspect, a flow rate adjusting mechanism capable of limiting the discharge rate of the variable displacement pump is provided between the pressure control valve and the variable displacement pump. Since the flow rate adjusting mechanism has a pilot operation switching valve that is opened when the pressure on the downstream side becomes equal to or higher than the set pressure of the pressure holding mechanism, a sudden change in vehicle height at the time of engine start is externally applied. The effect that it can be suppressed with a simple configuration without performing control is obtained.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a piston pump applicable to the first embodiment.

3 is a cross-sectional view showing a high-pressure maximum flow rate state of the flow rate adjusting mechanism of FIG.

FIG. 4 is a cross-sectional view showing a high pressure minimum flow rate state of the flow rate adjusting mechanism of FIG.

FIG. 5 is a characteristic diagram showing the relationship between the discharge pressure of the piston pump and the discharge flow rate.

FIG. 6 is a characteristic diagram showing a relationship of control pressure with respect to a command current of the pressure control valve.

FIG. 7 is a time chart for explaining the operation of the first embodiment.

FIG. 8 is a sectional view showing a modified example of the flow rate adjusting mechanism in the first embodiment.

FIG. 9 is a sectional view showing a low pressure minimum flow rate state of a flow rate adjusting mechanism showing a second embodiment of the present invention.

FIG. 10 is a cross-sectional view showing a high-pressure maximum flow rate state of the flow rate adjusting mechanism.

FIG. 11 is a sectional view showing a high pressure minimum flow rate state of the flow rate adjusting mechanism.

FIG. 12 is a characteristic diagram showing the relationship between the discharge pressure and the discharge flow rate of the piston pump in the second embodiment.

FIG. 13 is a schematic configuration diagram showing a third embodiment of the present invention.

FIG. 14 is an end view showing a state where an end cover of the piston pump is removed.

FIG. 15 is a time chart used for explaining the operation of the third embodiment.

FIG. 16 is a hydraulic circuit diagram showing a fourth embodiment of the present invention.

FIG. 17 is a time chart for explaining the operation of the fourth embodiment.

[Explanation of symbols]

 FS Fluid supply device 1 Fixed cylinder type radial piston pump 2 Engine 3 Reservoir tank 4 Flow rate adjusting mechanism 6S Line pressure pipe 6R Return pipe 19 Radial piston 25 Output port 41 Spool valve 43 Spool 44 Tank side port 45 Pump side port 46, 47 Variable Throttle 48 Piston plunger 50,52 Coil spring CD control device 61 Pressure holding part 63FL to 63RR Pressure control valve 64 Check valve 66 Pilot operated check valve 69FL to 69RR Hydraulic cylinder

Claims (4)

[Claims] 1. A fluid pressure cylinder including a fluid pressure cylinder interposed between a vehicle body and a wheel, a variable displacement pump for supplying a working fluid to the fluid pressure cylinder, and a variable displacement pump for supplying the fluid. A pressure control valve that controls a working fluid according to a command value to supply the fluid pressure cylinder to the fluid pressure cylinder, and a supply pressure to the pressure control valve that is interposed between the pressure control valve and the fluid supply device is less than or equal to a set pressure. In the supply flow rate control device for the fluid suspension, which includes a pressure holding mechanism having a closed circuit on the pressure control valve side, the fluid supply device changes the discharge pressure to the suction passage of the variable displacement pump. It has a variable throttle that opens and closes, and the variable throttle increases in opening degree from the minimum opening degree in response to an increase in discharge pressure when the discharge pressure becomes equal to or higher than a first set pressure higher than the set pressure of the pressure holding mechanism. , The first A supply flow rate control device for a fluid suspension, which is configured to have a maximum opening degree at a second set pressure higher than the set pressure. 2. The variable throttle has a sleeve in which a pump side port and a tank side port are formed adjacent to each other in an axial direction,
Slidably disposed within the sleeve and at least a first
And a low pressure minimum flow rate position that has a spool rod portion formed between the second spool land portion and is capable of communicating the pump side port and the tank side port, and closes the pump side port with the first spool land portion, A spool that slides between a high-pressure maximum flow rate position that communicates the pump-side port and the tank-side port with the spool rod portion and a high-pressure low-flow rate position that closes the tank-side port with the second spool land portion,
A pressing means for pressing the spool toward the high pressure / low flow rate position side in accordance with the pump discharge pressure, a first biasing means for biasing the spool toward the low pressure minimum flow rate position in all sliding regions, and the spool. A second urging means for urging the high pressure low flow rate position and the high pressure maximum flow rate position toward the low pressure minimum flow rate position, and the fluid chamber formed between the tank side port and the second spool land portion and the sleeve. 2. A supply flow rate control device for a fluid type suspension according to claim 1, further comprising a check valve interposed between the fluid chamber and the check chamber for blocking fluid flow from the fluid chamber to the port on the tank side. 3. A fluid pressure cylinder provided between a vehicle body and a wheel, a fluid supply device having a variable displacement pump for supplying a working fluid to the fluid pressure cylinder, and a variable displacement pump. A pressure control valve that controls a working fluid according to a command value to supply the fluid pressure cylinder to the fluid pressure cylinder, and a supply pressure to the pressure control valve that is interposed between the pressure control valve and the fluid supply device is less than or equal to a set pressure. In the supply flow rate control device of the fluid type suspension having a pressure holding mechanism having a closed circuit on the pressure control valve side when, the fluid supply device applies a radial piston pump as the variable displacement pump, When the discharge pressure of the radial piston pump is less than the set pressure of the pressure holding mechanism, the number of pistons for discharge is limited so that the discharge flow rate of the remaining pistons is returned to the tank. A supply flow rate control device for a fluid type suspension, characterized in that the discharge amount is limited. 4. A fluid pressure cylinder provided between a vehicle body and a wheel, a fluid supply device including a variable displacement pump for supplying a working fluid to the fluid pressure cylinder, and a variable displacement pump. A pressure control valve that controls the working fluid according to a command value and supplies it to the fluid pressure cylinder, and the supply pressure to the pressure control valve that is inserted between the pressure control valve and the fluid supply device is less than or equal to a set pressure. In a supply flow rate control device for a fluid suspension, which includes a pressure holding mechanism having a closed circuit on the pressure control valve side when the pressure is controlled, the discharge amount of the variable displacement pump is limited between the pressure control valve and the variable displacement pump. A fluid that is provided with a possible flow rate adjusting mechanism, and the flow rate adjusting mechanism has a pilot operation switching valve that is opened when the pressure on the downstream side of the flow rate adjusting mechanism becomes equal to or higher than the set pressure of the pressure holding mechanism. Flow control system for suspension system.