JPH0492708A - Fluid pressure feeding device - Google Patents

Abstract

PURPOSE:To reduce the size of a switching valve by applying specified limitation on switching control of a switching valve used for variation of a delivery am ount, in a delivery amount variable fluid pressure feeding device. CONSTITUTION:A first return passage 44 is branched on the upper stream side of a first check valve 39A to a first feed passage 38A on the first pump 34A side. A second return passage 46 is branched on the upper stream side of a second check valve 39B to a second feed passage 38B on the second pump 34B side a delivery amount of which is relatively low. A first switching valve 42 to communicate either the return passage 44 or 46 to a third return passage 48 through a tank 30 and a second switching valve 43 to bring the third return passage 48 into a communicating or disconnecting state and are provided. The switching valves 42 and 43 are controlled by means of a delivery passage control circuit passage 50, and control is effected such that the second switching valve 43 is switched from a disconnecting state to a communicating state in a state that the first switching valve 42 communicates the second return passage 46 to the third return passage 48.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to improvements in fluid pressure supply devices, and in particular, in fluid pressure supply devices capable of changing the discharge amount, it is possible to improve the size of the switching valve used to change the discharge amount. The aim is to

[Prior Art] An example of a structure of a switching valve that makes the discharge amount of a fluid pressure supply device variable is disclosed in FIG. 6 of Japanese Unexamined Patent Publication No. 2-123284.

This conventional structure includes two pumps with different discharge volumes, and a fluid passage interposed between the discharge side of the pump (first pump) with a large discharge volume and the fluid pressure equipment, and a pump with a small discharge volume. A branch path is provided on the discharge side of the (second pump) and a fluid path interposed between the fluid pressure equipment, and the other end of these branch paths is connected to a first switching valve. Return the downstream side of the switching valve to the tank via the return path,
Furthermore, a second switching valve is interposed in the return path.

The first switching valve is a switching valve that connects one of the branched paths to the return path, and the second switching valve is a switching valve that connects or blocks the return path. By appropriately switching the second switching valve, only the output of the second pump is supplied to the fluid pressure equipment side (small supply amount: mode 1), and only the output of the first pump is supplied to the fluid pressure equipment side. (Medium supply amount: Mode 2) and a state where the output of both pumps is supplied to the fluid pressure equipment side M
(Large discharge amount: mode 3) can be taken.

Therefore, since it is possible to supply a flow rate according to the required flow rate in the fluid pressure equipment, it is possible to supply a flow rate that is much larger than the required flow rate, that is, to avoid supplying wasteful flow rate, and the device that drives the pump This will improve fuel efficiency, etc.

[Problem to be solved by the invention]

Here, when switching the second switching valve from the cutoff state to the communication state, it is necessary to give the valve spool a force that overcomes the fluid force applied to the valve spool of the second switching valve. The force that moves the spool is usually provided by a spring or solenoid.

In the above-mentioned conventional configuration, there are no restrictions on switching the switching valve, so depending on the state of the first switching valve, the output of the first pump with a large discharge amount may be transferred to the second switching valve. Since the second switching valve may be switched from the cutoff state to the open state while the pump is in the open state, the spring, solenoid, etc. that moves the valve spool of the second switching valve can overcome the output of the first pump. In other words, it is necessary to use a relatively large size, and as a result, the second switching valve becomes large, which causes the fluid pressure supply device to become large and heavy.

This invention has been made by focusing on the unresolved problems of the conventional technology, and it is a fluid pressure control method that enables miniaturization of the switching valve by imposing certain restrictions on the switching control of the switching valve. The purpose is to provide a feeding device.

[Means to solve the problem]

In order to achieve the above object, the fluid pressure supply device according to claim (1) includes a first pump, a first supply path interposed between the discharge side of the first pump and the fluid pressure device, a first check valve that is provided in the first supply path and prevents backflow of fluid toward the first pump; and a first check valve that is branched from the first supply path on the upstream side of the first check valve. a second pump with a smaller discharge amount than the first pump; a second supply path interposed between the discharge side of the second pump and the fluid pressure device; a second check valve that is provided in the second supply path and prevents backflow toward the second pump; and a second check valve that is branched from the second supply path on the upstream side of the second check valve. a second return path; a first switching valve that communicates either one of the first and second return paths with a third return path leading to the tank; and a communication state or cutoff of the third return path. and a switching valve control means for controlling the states of the first and second switching valves, and the switching valve control means is configured to switch the switching valve from the cutoff state to the communication state. The switching of the second switching valve is performed with the first switching valve communicating the second return path with the third return path.

Further, in the fluid pressure supply device according to claim (2), in the invention according to claim (1), the switching valve control means is a third
The switching of the first switching valve and the switching of the second switching valve in the direction of increasing the flow rate in the return path of the switching valve are performed after maintaining the states of the first and second switching valves before switching for a predetermined period of time or more. .

[Effect]

The fluid discharged by the first pump is supplied to the fluid pressure equipment via the first supply path, and the fluid discharged by the second pump is supplied to the fluid pressure equipment via the second supply route. .

Further, the first return path branched from the first supply path and the second return path branched from the second supply path are located upstream of the first check valve or the second check valve, respectively. The first return path is supplied with only the output of the first pump, and the second return path is supplied with only the output of the second pump.

Here, the switching valve control means controls the first switching valve to communicate the first return path with the third return path, and also connects the first return path with the third return path.
When the third return path is brought into communication by controlling the switching valve of
Since the output of the first pump is returned to the tank via the first and third return paths, and the output of the second pump is supplied to the fluid pressure equipment via the second supply path, the fluid pressure supply The discharge amount of the device is in a small state (mode 1).

Further, the switching valve control means controls the first switching valve and the second switching valve.
When the return passage of the first pump is communicated with the third return passage and the second switching valve is controlled to bring the third return passage into communication, the output of the first pump is transferred to the fluid through the first supply passage. Since the output of the second pump is returned to the tank via the second and third return paths, the discharge amount of the fluid pressure supply device is in a medium state (mode 2).

Then, when the switching valve control means controls the second switching valve to cut off the third return path, the first and second return paths and the tank are in a non-communicating state. The output of the first pump is supplied to the fluid pressure equipment via the first supply path,
Since the output of the second pump is supplied to the fluid pressure equipment via the second supply path, the discharge amount of the fluid pressure supply device is in a large state (mode 3).

Furthermore, when switching the second switching valve from the cutoff state to the communication state, the first switching valve connects the second return path to the third return path.
(in other words, direct change from mode 3 to mode 1 is prohibited), the output of the second pump is applied to the valve spool of the second switching valve. , it is only necessary to apply a force to the valve spool of the second switching valve to overcome the output of the second pump.

Further, in the invention described in claim (2), the first switching valve is switched in a direction in which the flow rate of the third return path increases, and the second
When switching to a switching valve, that is, changing from mode 3 to mode 2, or changing from mode 2 to mode 1, the state of the first and second switching valves before switching is maintained for a predetermined period of time or more. This ensures that the switching valve is switched before proceeding to the next operation.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

This embodiment actively reduces rolling displacement, pitching displacement, etc. of the vehicle body by appropriately controlling the operating pressure of a hydraulic cylinder installed between the vehicle body and the wheels according to the lateral acceleration, longitudinal acceleration, etc. occurring in the vehicle body. The present invention is applied to a hydraulic pressure supply device for a vehicle that supplies hydraulic pressure to an active suspension that can suppress the amount of pressure.

In FIG. 1, 2 is a vehicle body, 4 is an arbitrary wheel 6 is an active suspension as a fluid pressure device.

Reference numeral 8 indicates a hydraulic pressure supply device as a fluid pressure supply device. Although not shown in the figure, the same suspension configuration is used for the four wheels.

The active suspension 8 includes a hydraulic cylinder 10, a pressure control valve 12, an attitude control circuit 18, and an acceleration sensor 19.

The hydraulic cylinder 10 has a cylinder tube 10a attached to the vehicle body 2 side, a piston rod 10b attached to the wheel 4 side, and a pressure chamber separated by a piston 10c within the cylinder tube 10a. This pressure chamber is connected to the pressure control valve 12 via a piping 11.
It communicates with o.

Specifically, as shown in FIG. 2, the pressure control valve 12 includes a cylindrical valve housing 13 containing a valve body, and a proportional solenoid 14 integrally provided with the cylindrical valve housing 13.

The main spool 15 and the poppet 16 are slidably inserted into the insertion hole 13A formed in the center of the valve housing 13, and the pilot chambers FL at both ends of the main spool 15 are inserted into the insertion hole 13A.
I. Offset spring 1 is installed in the feedback chamber FL.
7A and 17B are inserted. Note that 13Aa is a fixed aperture. The valve housing 13 is connected to the supply boat 1 at a position opposite to the lands 15a, 15b and the pressure chamber 15c of the main spool 15 and communicated with the insertion hole 13A.
2S, a return port 12r, and an output port 12°. Also poppet 16 and feedback room FL
A partition wall 13 having a valve seat work 3Ba of a predetermined diameter is provided between the partition wall 13 and
A pressure chamber C is formed by B.

The supply boat 12s communicates with a pressure chamber C via a biront passage 13s, and the pressure chamber C has a valve seat 13Ba.

It communicates with the return port 12r via the drain passage 13t. In addition, the output port 12o is connected to the feedback path 1
It communicates with the feedback chamber FL via 5f.

On the other hand, the proportional solenoid 14 includes a plunger 14A that is movable in the axial direction and an excitation coil 14B that drives the plunger 14A. When this excitation coil 14B is excited by the command value ■, the plunger 14A moves and biases the poppet 16, and depending on the bias, the flow rate of the hydraulic oil flowing through the valve seat 13Ba, that is, the pressure chamber C ( That is, the pressure in the pilot chamber F,) can be adjusted.

Therefore, in a state where the pushing force by the proportional solenoid 14 is applied to the poppet 16, both chambers F.

When the pressures of F are balanced, the spool 15 will output
The spool position shown in the figure is taken to cut off the connection between the supply port 12o, the supply port 12s, and the return port 12r. Therefore, Directive 4
The pressure in the pilot chamber Fu is adjusted depending on the magnitude of fz I, and the spool 15 moves slightly until the pressures in both chambers FL and Fl are balanced according to this pyro pressure, and the pressure is adjusted from the output port 12o. The output pressure PC can be controlled in proportion to the command value ■ as shown in FIG. In the same figure, P2
is the maximum line pressure from the hydraulic supply device 8.

The acceleration sensor 19 detects accelerations generated in the vehicle body 2 in the lateral direction 9, longitudinal direction, and vertical direction, and outputs an electric signal C corresponding to these state quantities to the attitude control circuit 18. The attitude control circuit 18 performs calculations such as multiplying the detection signal G by a predetermined gain, and sets the command value I to suppress roll and pitch of the vehicle body and damp vertical vibration.
is calculated and supplied to the pressure control valve 12.

In FIG. 1, 22 is a coil spring that supports the static load of the vehicle body 2, and 24 and 26 are apertures and accumulators that damp vibrations in the resonance region under the springs.

On the other hand, the hydraulic pressure supply device 8 includes a tank 3 that stores hydraulic oil.
0, and a hydraulic pump 34 whose suction side is connected to this tank 30 via piping 32. The hydraulic pump 34 is a variable displacement Bonge system connected to the output shaft 36A of the engine 36, and is specifically a plunge medium-sized pump having a plurality of cylinders. One set of every other cylinder in each cylinder constitutes a first hydraulic pump 34A serving as a first pump with a relatively large discharge amount per revolution, and the other set constitutes a first hydraulic pump 34A with a relatively large discharge amount per revolution. A second hydraulic pump 34 as a second pump with a smaller volume
B is configured.

Here, the first. The discharge flow rate characteristics with respect to the rotational speed of the second hydraulic pumps 34A, 34B are as shown in FIG. In other words, during posture control and running, which consume a large amount of flow, the discharge volume of both the first hydraulic pumps 34A and 34B is used, and when the flow consumption is low, such as when stopped or running, the discharge volume of the second hydraulic pump 34B is used. When a consumption flow rate in between is suitable, the discharge amount of the first hydraulic pump 34A is sufficient.

A first supply side pipe line 38a as a first supply line is connected to the discharge port of the first hydraulic pump 34A.
a reaches the supply boat 12s of the pressure control valve 12 via a check valve 39A as a first check valve and a check valve 39B. Further, a drain side pipe line 40 is connected to the return port 12r of the control valve 12, and this pipe line 40 reaches the tank 30 via an operating check valve 41. The operated check valve 41 is a pilot operated check valve that sets the downstream line pressure of the check valve 39B to a pilot pressure P, and in this embodiment, the pilot pressure PP > pN
(PM is the operating neutral pressure: see Figure 3), the check is released (valve is open) and the pipe 40 is communicated, P, ≦P
, the pipe line 40 is shut off as a checked state (valve closed).

Further, a second supply side pipe line 38b as a second supply line is connected to the discharge port of the second hydraulic pump 34B, and this pipe line 38b is connected to a check valve 39C as a second check valve.
It is connected to the downstream side of the check valve 39A of the first supply side pipe 38a through the check valve 39A.

Furthermore, the hydraulic supply device 8 is connected to a first
A 3-point, 2-position spring offset type electromagnetic directional switching valve 42 serves as a switching valve, and 2 serves as a second switching valve.
It is provided with a spring offset type electromagnetic directional switching valve 43 with a point 2 position.

The first supply pipe line 3 is connected to the input side of the electromagnetic directional control valve 42.
The first branch branched from the upstream side of the check valve 39A of 8a.
The return path 44 is connected to a second return path 46 branched from the upstream side of the check valve 39C of the second supply pipe 38b, and the output side thereof is connected to A third return path 48 is connected, and depending on the position of the valve spool, either the first return path 44 or the second return path 46 is communicated with the third return path 48 .

On the other hand, the electromagnetic directional switching valve 43 is interposed in the middle of the third return path 48, and puts the third return path 48 into a communicating state or a blocked state depending on the position of the valve spool.

Each of these electromagnetic directional control valves 42 and 43 is
Switching signals C3I and C3z supplied to those solenoids from the discharge amount control circuit 50 are turned on.

It can be switched to two stages depending on whether it is off or not.

That is, when the switching signal C81 is "off", the valve spool of the electromagnetic directional control valve 42 assumes the state shown in FIG. 1 due to the urging force of the spring, so that the second return path 46 becomes the third return path 48. When communication is established and the switching signal C81 is "on", the valve spool of the electromagnetic directional control valve 42 takes a state different from that shown in FIG. 1 due to the urging force of the solenoid, so the first return path 44 becomes It communicates with the return path 48.

Furthermore, when the switching signal C32 is "off", the valve spool of the electromagnetic directional switching valve 43 assumes the state shown in FIG. When is "on", the valve spool of the electromagnetic directional control valve 43 assumes a state different from that shown in FIG. 1 due to the biasing force of the solenoid, so the third return path 48 is in a blocked state.

Further, a relatively large capacity pressure accumulator 52 is connected downstream of the check valve 39B of the first supply pipe 38a, and a relief valve 53 for setting the line pressure to a predetermined value is connected to the first supply pipe 38a. It is connected between the line 38a (located between the check valves 39A and 39B) and the drain side pipe line 40.

Furthermore, this hydraulic supply device 8 includes a pump rotation speed sensor 56
and stroke sensors 58FL and 5BPR. The pump rotation speed sensor 56 detects an electric signal N corresponding to the rotation speed of the hydraulic pump 34. Specifically, for example, the pump rotation speed sensor 56 detects the engine rotation speed on the output side of the transmission magnetically,
It also serves as an engine rotation speed sensor consisting of an optically detected pulse detector, and outputs its detection signal N to the discharge amount control circuit 50. Stroke sensor 58FL, 58
FR is the vehicle body 2 and wheels (front, front right wheel) 4,4
The detection signal xL + χR is comprised of a potentiometer interposed in each of the discharge amount control circuits 50.

On the other hand, the discharge amount control circuit 50, as shown in FIG.
Bandpass filters 66 and 68 that filter the input stroke signal X L + X jl and output signals XL and X1 of the bandpass filters 66 and 68.
Each integrator 70 .
72 and the output signals QL and Q of the pilot flow rate setting device 74
, and an adder 76 that mutually adds Qo, and an addition signal of this adder 76 (a signal corresponding to the reference estimated consumption flow rate) Q
A.

A mode setting circuit 78 that receives the pump rotational speed signal N and sets the pump operating mode; a drive circuit 80A that receives the output signal SL of the setting circuit 78 and outputs a switching signal C51 to the electromagnetic directional switching valve 42; Output signal S of circuit 78
The driving circuit 80B receives the signal L2 and outputs a switching signal C52 to the electromagnetic directional switching valve 43.

The low cantoff frequency ft of each bandpass filter 66, 68 is set to a value (for example, 0.5 Hz) that can block the stroke change during vehicle height adjustment, and the high cutoff frequency f
H is set to a value that can block the stroke variation on the unsprung resonance frequency side (for example, 6 cycles). Also, each integrator 7
0,7.2 is Q-Slx 1dt
...Calculated based on the formula (1) (subscript to signal X, R omitted) to obtain the integral value of the stroke change, that is, the total stroke during the integral time T (for example, 2 seconds)! The flow rate in and out of the cylinder corresponding to '1/T - S l large ldt' is determined. K is a gain based on the pressure receiving area of the hydraulic cylinder 10.

Here, if we pay attention to the actual stroke variation between the vehicle body 2 and the wheels 4, in most cases it is on the elongation side.

The vibration appears symmetrically on the contraction side. However, the discharge flow rate from the hydraulic pump 34 is actually required only when the stroke changes to the extension side and hydraulic oil flows into the hydraulic cylinder 10, and when the stroke changes to the contraction side,
When hydraulic oil is drained, there is no need to supply hydraulic oil.

However, the flow rate for the stroke changing to the contraction side may be exactly the amount of hydraulic fluid flowing into the hydraulic cylinder 10 on the rear wheel side, so the calculated value of equation (1) for the two front wheels is After all, it simply represents the consumption flow rate with respect to the total stroke change of the four wheels.

Further, the biloft flow rate setting device 74 outputs a value Q0 corresponding to the internal leakage amount of the pressure control valve 12 for four wheels. Therefore, the addition result QA of the adder 76 becomes the estimated consumption flow rate of the entire system.

Then, the drive circuit 80A outputs the output signal SL with the logical value "
1, the switching signal C8I is turned on;
When the output signal SL has the logical value "O", the switching signal C31 is turned "off", and when the output signal SL has the logical value "1", the driving circuit 80B turns the switching signal C32 "on". J, and the output signal S L z is the logical value "
0, the switching signal C82 is turned off.

Furthermore, as shown in FIG. 5, the discharge amount control circuit 50 receives the stroke signal X L + X l and calculates the average value "L+"l of the signals xL, x, .
A low-pass filter 82.84 serves as an arithmetic unit, and an average value xL based on this filter 82.84.

'Xt XtJ for Xl, 'Xl xll
Adders 86 and 88 each perform the operation of J, and the added value [
It also has an absolute value circuit 90.92 that calculates the absolute value of χL 5ftJ and "X@N*" and outputs the signal to the mode setting circuit 78. The cant-off frequency of the analog low-pass filters 82 and 84 is set to a value (e.g., 0.1) (z) below the stroke frequency range (e.g., around 1 to 107) of vibrations caused by vibration input from the road surface. and the input signal
Smooth L+Xj+.

The mode setting circuit 78 is configured to include, for example, a microcomputer, and stores in advance a mode map corresponding to the discharge flow rate characteristics shown in FIG. 4 described above.
The arithmetic processing in FIGS. 6 to 8, which will be described later, is performed using Δt (<T).
Do it every hour.

Among these, in the process shown in FIG. 6, an estimation mode (value of a flag MP, which will be described later) is set for each time T synchronized with the integration period. The process shown in FIG. 7 is the subroutine process shown in FIG. 6, and is based on the estimation mode set in the process shown in FIG. 6 and outputs a logical value "1" or a logical value "0" according to certain constraints Outputs signals SL and SL.

The process shown in FIG. 8 has the function of monitoring the state in which the stroke amount is large for each time period.

Next, the operation of this embodiment will be explained.

First, the operation of mode setting circuit 78 will be explained.

This mode setting circuit 78 operates for a certain period of time Δt (for example, 2
0m5ec), the timer interrupt processing shown in FIGS. 6 and 8 is performed, respectively.

d is set to zero by the main program at the start of processing. ).

In the process shown in FIG. 6, the counter C is incremented for each interrupt processing in step (2), and it is determined in step (2) whether the integer A corresponding to the predetermined time T (=Δt-A) has been reached.

If the count value of the counter C has not reached the integer A in the judgment of step (2), the process moves to step (2), where it is judged whether the flag a1=1 or not, and if the judgment is rNo, step Moving to (2), it is determined whether flag az=1.

Here, the flags a1 and a2 are flags set in the process shown in FIG. 8, which will be described later, and are
When the stroke amount of is large enough to exceed the predetermined value E2 (large stroke state) and within a predetermined time thereafter, al =
Q, az = 1, and if the stroke amount is smaller than the predetermined value E2 but larger than the predetermined value El (<E2) (medium stroke state) and within the subsequent predetermined time, a1 = iat = O. and if the stroke is less than the predetermined value E (small stroke state), a,
=O, a, =O.

Therefore, the judgments of step ■ and step ■ are both r
If No, it can be determined that the current mode is maintained and the program returns to the main program since it can be determined that the stroke is in a small stroke state.

On the other hand, when the determination in step ■ is rYES, the process moves to step ■, and after clearing the counter C, step ■
to move to.

In step (2), the reference estimated consumption flow rate signal QA, which is the addition result of the adder 76, is input and the value is stored. Next, the process moves to step (2), where the detection signal N of the pump rotational speed sensor 56 is inputted, its value is stored, and the process moves to step (2).

In this step (2), with reference to the map corresponding to FIG. 4, the reference mode of the minimum discharge flow rate to which the coordinates uniquely determined by the reference estimated consumption flow rate QA and the pump rotational speed N belongs is set. That is, for mode 1, the reference mode value M0 is set to 1.
For mode 2, set the reference mode value M0 to 2, and for mode 3
If so, the reference mode value M0 is set to 3.

Next, the process proceeds to step (3), and it is determined whether the flag a, =1, and if the determination is rNOJ, the process proceeds to step [phase], and it is determined whether the flag az=1. In other words, it is determined whether the stroke state is a large stroke state, a medium stroke state, or a small stroke state by the determination of step (2) and step [phase].

If the determinations in step (2) and step [phase] are both rNOJ (small stroke shape B), the process moves to step (2) and the estimation mode is set to the reference mode set in step (2) above. That is, the estimated mode value M1 is set to a value equal to the reference mode value M0.

If the determination in step (2) is rYESJ (medium stroke state), the process moves to step @, and the estimation mode is set to a mode that is one step higher than the reference mode.

In other words, the reference mode value M. If is 1, the estimated mode value M1 is set to 2, and if the reference mode value M0 is 2 or 3, the estimated mode value M is set to 3.

Note that even if the determination in step ① above is rYES,
Since the process in step @ is executed, the estimation mode is set to a mode that is one amp higher than the reference mode.

Furthermore, the determination of step ■ is rNOJ and step [
When the determination of [phase] is rYES (large stroke state), the process moves to step (2), and the estimation mode is set to a mode that is two times higher than the reference mode. In addition, in this embodiment, the mode is divided into three stages, 1, 2 and 3, so
In this step (2), the estimated mode value M is always 3.

Note that even if the determination in step ① above is rYEs,
Since the process of step (2) is executed, the estimation mode becomes 3.

Then, when the estimation mode is set in the processing of step (2), step @, and step (2), the process moves to step 0 and the subroutine processing shown in FIG. 7 is executed.

In the process shown in FIG. 7, first, in step ■, the estimated mode value M
, and the current mode value M2 representing the current mode are determined. If they are equal, there is no need to change the mode, so this subroutine processing is performed without changing the current mode value M2. finish.

However, if it is determined in step ■ that the estimated mode value M, and the current mode value M2 are different, the process moves to step ■, and the estimated mode value M, and the current mode value M2 are different.
It is determined whether M1≧M2.

If this determination is rYESJ, a mode larger than the current mode is desired, so the process moves to step ■, sets the current mode value M2 to a value equal to the estimated mode value M1, and then moves to step ■. to clear and start the timer that measures the time since the current mode was changed.

Then, the process moves to step (3), and the output signals SL and SL2 corresponding to the current mode value M2 are sent to the drive circuits 80A and 80A.
Output to 0B.

That is, if the current mode value M2 is 1, the output signal S L
I is a logic value "1" and the output signal S L 2 is a logic value "1".
0'', and if the current mode value M2 is 2, the output signal SL
, and SL2 are both set to a logic value "0", and if the current mode value M2 is 3, the output signal SL is set to a logic value "0" and the output signal SL2 is set to a logic value "1".

Then, the drive circuits 80A and 80B operate the electromagnetic directional valves 42 and 4 according to the output signals SL and SL2.
Switching signals C81 and CS2 are output to solenoids No.3.

As a result, in the case of mode 1, as shown in FIG. 9(a), the switching signal C81 is "on" and the switching signal C32 is "on".
is turned off, so the electromagnetic directional switching valve 42 connects the first return path 44 to the third return path 48, and the electromagnetic directional switching valve 43 connects the third return path 48, so that On the active suspension 6 side, there is a second
Only the output of the hydraulic pump 34B is supplied.

In addition, in the case of mode 2, as shown in Fig. 9 Φ),
Since the switching signals C3I and C82 are "off", the electromagnetic directional switching valve 42 switches the second return path 46 to the third return path 48.
Since the electromagnetic directional control valve 43 brings the third return path 48 into communication, the active suspension 6 side has a
Only the output of the first hydraulic pump 34A, which has a relatively large discharge amount, is supplied.

Furthermore, in the case of mode 3, as shown in FIG. 9(C), since the switching signal C31 is "off" and the switching signal C32 is "on", the electromagnetic directional switching valve 42 is in the second return state. The passage 46 is communicated with the third return passage 48, but since the electromagnetic directional control valve 43 shuts off the third return passage 48, the first hydraulic pump 34A is connected to the active suspension 6 side.
and the second hydraulic pump 34B are supplied.

Returning to FIG. 7, when the processing of step ■ is completed, this subroutine processing is terminated, while the judgment of step ■ is "
If "NO", it is determined that a smaller mode than the current mode is desired, and the process moves to step (2).

In this step ■, the measurement time of the timer that was cleared and started when the current mode was changed is a predetermined time (
For example, it is determined whether the predetermined time has elapsed (for example, 2 seconds), and if the predetermined time has not yet elapsed, this subroutine processing is ended without changing the current mode value.

If the determination in step (2) is rYES, it can be determined that a predetermined period of time or more has passed since the mode was changed to the current mode, so the process moves to step (2).

That is, when the process of step (2) is executed, when changing the mode from 3 to mode 1.2 or from mode 2 to mode 1, in other words, the flow rate of the third return path 48 is increased. When changing the supply amount to the active suspension 6 side, instead of changing to the draft estimation mode, change the mode before the change (the state of the electromagnetic directional control valves 42 and 43 before the change). After being held for a predetermined time or more, the mode is changed to estimation mode.

Then, in step (2), it is determined whether the current mode value M2-3 and the estimated mode value M,=1, that is, mode 3.
It is determined whether the change is from mode 1 to mode 1 or not.

Here, from mode 3 (see FIG. 9(C)) to mode I
(See Fig. 9(a)), first switch the electromagnetic directional switching valve 42 in the state shown in Fig. 9(C), then switch the electromagnetic directional switching valve 43 to the state shown in Fig. 9(a). how to(
There are two possible methods: the first method) and the second method of switching the electromagnetic directional valve 42 after switching the electromagnetic directional valve 43. When the output of the first hydraulic pump 34A with a large discharge amount is applied to the valve spool 43, the electromagnetic directional control valve 4
3, a relatively large force is required for the switching.

In other words, it is necessary to use a relatively large spring for the electromagnetic directional switching valve 43, and the solenoid that generates force when switching in the opposite direction must be large enough to generate enough force to overcome the large spring. Therefore, the dimensions of the electromagnetic directional control valve 43 become large.

However, if the second method is adopted, when switching the electromagnetic directional control valve 43 from the cutoff state to the communication state, the valve spool of the electromagnetic directional control valve 43 is connected to the output of the second hydraulic pump 34B with a small discharge volume. Since the switching is performed in the state in which the electromagnetic directional control valve 43 is applied, a large force is not required, and there is no need to use a large spring or solenoid for the electromagnetic directional control valve 43, and the electromagnetic directional control valve 43 can be made smaller. .

Therefore, in this embodiment, if it is determined in step ■ that mode 3 is to be changed to mode 1, step
, and sets the current mode value M2 to 2.

That is, when changing from mode 3 to mode 1, the change to mode 2 is performed once, and then the change to mode 1 is performed.

Then, after changing to mode 2 in step ■, the timer is cleared and started in step ■, so after mode 2 has continued for a predetermined period of time, mode 1
Therefore, the electromagnetic directional switching valve 42 is surely switched after the electromagnetic directional switching valve 43 is switched.

Further, if the current mode is 2 and the estimation mode is 1, the process moves from step (2) to step (2), the above-mentioned processing is executed, and the mode is changed to mode 1.

On the other hand, in the process shown in FIG. 8, the output signals tx-x of the absolute value circuits 90 and 92 are
, l l and IX-XLI, and the difference values D8 and DL
be memorized as .

Next, in step ■ and step ■, the difference value D'
It is determined whether either s or DL is equal to or greater than a predetermined value E2 that can determine a large stroke state, and step
If the determinations in step (2) and (2) are both "NO", it is determined that the large stroke state is not present.

Then, the processes of step (2) and step (2) are executed to determine whether either of the difference values DR and DL is equal to or greater than a predetermined value 81 for determining a medium stroke state.

Judgments for both step ■ and step ■ are “NO”
In this case, there is no middle stroke condition, i.e., anterior left
Since it can be determined that both the front right wheels 4 and 4 are in a small stroke state, proceed to step ① and set the variable f, (the stroke state in this process is a large stroke state or a medium stroke state that requires a mode amplifier. or a variable indicating whether the mode is in a small stroke state where mode-up is not necessary) is set to O, and the process moves to step (3).

In step (2), it is determined whether at least one of the flags a and a2 is 1 and the counter d is 1 or more. Here, the counter d is a counter that counts the number of times the large stroke state or the medium stroke state occurs.

In the case of "NO" in this step ■, proceed to step ■, clear the flag a+ + "! + e and counters b and d, and then proceed to step [phase].
Variable fi−, (the stroke state in the previous process is
A variable representing whether the mode is in a large stroke state or medium stroke state that requires mode up, or is in a small stroke state where mode up is not necessary is set to a value equal to the variable f, and the process of FIG. 8 is performed. finish.

However, while repeating the timer interrupt processing, if either step ■ or step ■ is determined to be rYESJ, it is determined that a large stroke is in progress.
After proceeding to step (2) and setting the variable f to 1, proceeding to step @, it is determined whether the variable fi-1 is O.

In other words, in step @, the point in time when the state changes from the small stroke state to the large stroke state is monitored, and this judgment is "NO".
In this case, the processing from step @ to step ■ is not necessary, so this process is ended after moving to step [phase]. On the other hand, if the judgment of step @ is rYEs, the process moves to step ■, and the counter is d is incremented to count the number of times the state has shifted to the large stroke state.

Then, the process moves to step [stock], and after setting the flag a1=0 and flag a2=1 to indicate a large stroke state, the process goes through step [phase] and ends.

Note that both the judgments of step ■ and step ■ are rNO,
, and if either step (2) or step (2) is determined to be rYEsJ, it is determined that the stroke is in the middle stroke state, and steps (2) to (2) are executed.

Note that the processing in steps ① to ② is roughly the same as the processing in steps 0 to 0 above. It is set as a2-0.

In this way, the difference values Da and DL and the predetermined value E.

Since the stroke state is determined by comparing with E2 and flags a and a2 are appropriately set according to the determination result,
In the process shown in FIG. 6, the current stroke state can be known by referring to these flags a1 and a2.

Further, if it is determined in step (2) that rYESJ is determined, the process proceeds to step (2) and it is determined whether or not the counter d is 2 or more.

This judgment is to identify whether or not the vibration is in the convergence direction.If the large stroke state or medium stroke state is still continuing, the count value of the counter d increases in step ■ or step ■, and the stroke If the absolute value of the quantity is less than the predetermined value E1 and there is a tendency to converge, the count value remains 1.

Therefore, if rNo at step [phase], the process moves to step [phase] and the counter c=0. That is, it is determined whether or not time T has elapsed. The judgment of this step [stock] is “
If NO, the process has exited from the large stroke state and the medium stroke state, but the predetermined time T has not yet elapsed, so the process is terminated via step [phase].

However, if 'Y E S-(' occurs in step [phase], proceed to step ■, increment counter b, and determine whether counter b has reached 2 in step 0. The determination is made that after escaping from the large stroke state and medium stroke state, at least 1
This is to maintain the mode-up state for a period (T time).

Therefore, in the case of "NO" in step @, it is assumed that the holding time TF + T (0≦TF<T: TF varies depending on the timing of exit from the large stroke and medium stroke) has not yet elapsed, and the step [phase ], this process ends.

On the other hand, if rYESJ is determined in the above step [phase], it is assumed that a large stroke or a medium stroke occurs again during the previous holding time TF10T, and that the large stroke or medium stroke state has been exited. Move to step [phase], flag e=1 (counter b
= o). If this judgment is rNOJ, it is assumed that counter b has not been cleared yet, and the process moves to step @, where counter b is cleared and the measurement of the holding time is canceled, flag e is set, and this counter is cleared. After showing the above step [phase]
to move to.

Further, if the determination of step [phase] is rYEsJ, it is assumed that the counter has already been cleared, and the process moves to step [phase] without executing step [phase].

Therefore, when a large stroke or medium stroke arrives again during the holding time set by the occurrence of an arbitrary large stroke or medium stroke, it is determined that the large stroke or medium stroke is continuing, and flag a is set.
and maintain the state of a2. Furthermore, when such a large stroke or medium stroke does not arrive, flags a and a2 are lowered after the holding time has elapsed.

Note that the length of the holding time can be freely set depending on the vibration frequency and horsepower consumption.

In this embodiment, the processes shown in FIGS. 6 to 8 correspond to the switching valve control means.

Next, the overall operation will be explained.

Now, you are traveling straight at a constant speed on a smooth road, the operating check valve 41 is open, the supply path and the return path are in communication, and the line determined by the relief valve 53 is being driven by the hydraulic pump 34. It is assumed that pressure is being supplied to the active suspension 6.

In this state, hardly any vibration input from the road surface, stroke fluctuations between the vehicle body 2 and wheels 4, and external forces on the vehicle body 2 occur. For this reason, the stroke sensor 58FL,
The detection signals XL and X* of the 58FR hardly change, the extracted components of the band pass filters 66 and 68 have values close to zero, and the added value of the adder 76 is QA, Q, and the standard estimated consumption flow rate is small. .

At this time, the stroke state is IχLXLI″−,0 and lx+t xR1=o, and l XL XL<E
, and 1χ, -xR (<E, so the flags al =O, az =o are set by the process in FIG. By processing, the coordinate point according to the pump rotation speed N and the standard estimated consumption flow rate QA at that time is set for a certain period of time T.
Read each time and set the reference mode to 1.

At this time, since flags a1 and a2 are both O, the estimation mode is set to 1, which is the same as the reference mode. As a result, the switching signal C8 is turned on and the switching signal C32 is turned off, and the electromagnetic directional control valves 42 and 43 assume the state shown in FIG. 9(a), so that the pump section 51 operates in mode 1.

That is, the first hydraulic pump 34A is in a no-load operation, and the line pressure is covered by the small discharge flow rate of the second hydraulic pump 34B.

In other words, when it is estimated that the flow rate consumed by the cylinder 10 is low, such as when driving straight at a constant speed on a good road, the discharge amount of the pump section 51 is reduced to reduce the horsepower consumption. , aiming to improve fuel efficiency.

Furthermore, if the vehicle enters a undulating road where low-frequency undulations continue from the above-mentioned driving state, the sprung mass resonance region (1
Vertical vibrations of relatively low frequency equivalent to 7) are input,
Assume that there is stroke vibration in at least one of the front wheels 4.4.

Even if such stroke fluctuation occurs, 1xtN L
< E I and X jlX , l < E 1, flags a1 and a2 are maintained at O in the process of FIG. This is covered by the hydraulic oil supply from

However, IXL x, l≧El, 1xll 5
[111≧E.

If at least one of the following is established, either one of the flags a1 and a2 becomes 1 by the process shown in FIG. Therefore, in the process shown in FIG. 6, a mode that is 1 or 2 up from the reference mode is forcibly set as the estimation mode.

As a result, when the estimation mode becomes 2, the electromagnetic directional control valves 42 and 43 are in the state shown in FIG. 9(b), so the second hydraulic pump 34'B is in no-load operation. , a large flow rate of the first hydraulic pump 34A is output to the load side, and when the estimation mode becomes 3, ! Since the magnetic direction switching valves 42 and 43 are in the state shown in FIG. 9(C), the first hydraulic pump 34A and the second hydraulic pump 34B
Both outputs are supplied to the active suspension 6 side.

That is, in this embodiment, the mode up, that is, the amount increase is commanded at an appropriate timing immediately after the vertical vibration input starts. This timing has much better responsiveness than timing based on vertical acceleration, so it eliminates the delay in increasing the amount.

Then, as time passes, l XL XL l <E
+ and return to l XRXRl <E+, the stroke amount touches the contraction side during the mode up holding time,
Assuming that the dark value 'E+J is exceeded again, Step 8 in Figure 8 ■
The retention period is updated by the processing in steps 1 to 2, and measurement of the retention time is started again, and during this measurement, the initially updated estimation mode is maintained as it is. This increase control is repeated in the same way as long as the large stroke state or medium stroke state continues.

On the other hand, in the active suspension 6, posture control in response to vibration input is executed in parallel with the mode-up control described above. That is, at the beginning of entering the undulating road, the pressure in the cylinder chamber of the hydraulic cylinder 10 increases or decreases, and in response to this pressure fluctuation, the spool 15 of the pressure control valve 12 moves slightly in the axial direction as described above. This allows hydraulic oil to flow between the cylinder 10 and the hydraulic pressure supply device 8 via the pressure control valve 12 to absorb vibrations.

However, as the vehicle travels further on an undulating road and vibrations cannot be absorbed by the above-mentioned spool movement, the vehicle body also begins to move up and down. In such a state, the acceleration sensor 19 attached to the vehicle body detects a signal G corresponding to the vertical acceleration and outputs it to the attitude control circuit 18. Therefore, the attitude control circuit 18 calculates a command value I for damping the vertical vibration based on the detection signal G, and outputs it to the pressure control valve 12 of each wheel. Therefore, in the hydraulic cylinder 10, a force proportional to the absolute velocity in the vertical direction is generated, and vertical vibrations are accurately damped and vertical movements are suppressed.

In such a vibration control state, the flow consumption is much larger than in the straight-ahead state, but in this example, the flow rate is increased by switching to mode 2 at the start of a medium stroke and switching to mode 3 at the start of a large stroke. , sufficient flow rate is supplied in advance to meet the consumption flow rate. Therefore, there is no delay in increasing the amount due to the vertical acceleration signal, and there is no possibility that the amount will not be increased in time even if a transition to a large stroke state occurs between the regular mode settings. Therefore, the amount can be increased with good response, without impairing the suspension function, and ensuring good ride comfort on winding roads and the like.

Furthermore, it is assumed that the stroke vibration is brought to a convergence by moving from the above-mentioned undulating road to a good road. In this case as well, mode 2 or mode 3 is maintained until the predetermined holding time elapses, so even if there is a relatively large stroke vibration immediately after exiting the large stroke state or medium stroke state, a large flow rate is supplied. The line pressure is maintained, and the pressure is quickly accumulated in the accumulator 52 as well.

Then, when the holding time has elapsed, flags a1 and a2 both become O in the process of FIG. 8, so in the process of FIG.
Estimation mode is set to reference mode.

That is, when the stroke vibration is small, the mode is returned to mode 1, which is a small discharge flow rate, and fuel efficiency is promoted.

On the other hand, suppose that after traveling on the undulating road, the vehicle body shifts to a state where the vehicle body rolls or pinches due to, for example, cornering on a smooth road without unevenness, sudden deceleration, or sudden acceleration. In this case, the attitude control circuit 18 outputs a command value I based on the detection signal G from the acceleration sensor 19, and
Control the working pressure of 0. As a result, the operating pressure increases roll stiffness and pitch stiffness, and keeps the vehicle body almost flat. Since the front wheel stroke signal Xtx at this time hardly changes, mode 1 is set as described above. In other words, roll on a good road.

In pitch control, the consumption flow rate is relatively small compared to vibration damping in the vertical direction, so it can be handled by the discharge amount in mode 1 and the hydraulic oil supply from the accumulator 52.

On the other hand, when the stroke detection signal χ1. Since .chi.A changes depending on the unevenness, Mode 2 or Mode 3 is set depending on the road surface condition. Although the flow rate consumed for attitude control during such running is large, a flow rate commensurate with this is supplied, resulting in reliable attitude control.

Furthermore, when the vehicle stops after traveling, mode 1 is set because the estimated flow rate is low, and the horsepower consumption is lowered. Also,
When the ignition switch is turned off, the engine 36
Since the rotation of the hydraulic pump 34 stops, the discharge amount of the hydraulic pump 34 immediately becomes zero. At this time, the operating oil leaks to the drain side via the pressure control valve 12, and when the pilot pressure P becomes equal to P, the operating check valve 41 becomes "closed" and the operating pressure is set to a predetermined value. Therefore, the vehicle body posture is flat according to the pressure value P9.

In this way, in this embodiment, instead of the vertical acceleration signal, a stroke signal that more accurately reflects the road surface condition is used to accurately estimate the consumption flow rate at every predetermined time T, and calculate the minimum flow rate that satisfies this estimated value. Since the pump operation mode is set and the pump 34 is driven based on the setting, a necessary and sufficient flow rate can be stably supplied and there is little loss in horsepower consumption. In addition, especially when performing vibration control in the vertical direction, which consumes a large amount of flow, the amount is increased immediately, so there is no response delay when increasing the amount based on acceleration, and even if the predetermined time T is set to a relatively long time, the amount of water is increased immediately. .

There is no need to worry about not being able to increase the amount in time, and there is an advantage that the amount can be increased quickly.

Furthermore, since only two stroke sensors are required for the front wheels, the configuration is relatively simple. Furthermore, by appropriately setting the threshold value E for determining the large stroke state, it is possible to prevent malfunctions due to noise or the like.

Furthermore, in this embodiment, when switching the electromagnetic directional control valve 43 from the cutoff state to the communication state, the output of the second hydraulic pump 34B, which has a small discharge amount, is applied to the electromagnetic directional control valve 43. Therefore, the spring and solenoid can be small, and the electromagnetic directional control valve 43 can be made smaller.

This allows the hydraulic pressure supply device 8 to be made smaller and lighter, so it is suitable for cases where installation space is limited, such as in a vehicle.

In addition, in this embodiment, when changing the mode in the direction of increasing the flow rate of the third return path 48, the change is not made until a predetermined period of time has elapsed after the current mode is entered in step 7 in FIG. Since the previous state is maintained, the electromagnetic directional control valve 4 can be reliably
After 2 and 43 are switched, the next operation begins. For this reason, the switching timing is too fast, and the output of the first hydraulic pump 34A is supplied to the electromagnetic directional switching valve 43 before the switching of the electromagnetic directional switching valve 43 is completed, and the switching of the electromagnetic directional switching valve 43 is This prevents the situation from becoming insufficient.

In the above embodiment, the fluid pressure supply device according to the present invention is applied to a hydraulic pressure supply device 8 that supplies hydraulic fluid to an active suspension 6 for a vehicle, but the present invention is not applicable to this. It is not limited to.

Further, in the above embodiment, a case has been described in which hydraulic pressure is used as the fluid pressure, but other fluid pressures may be used.

〔Effect of the invention〕

As explained above, according to the invention set forth in claim (1), a large force is not required to switch the second switching valve, so the switching valve can be downsized, and the fluid pressure supply device itself can be reduced in size. This has the effect of improving mountability.

Further, according to the invention described in claim (2), since the next operation is started after the switching valve is reliably switched, the switching timing is too fast and the switching of the second switching valve is completed. This prevents the output of the first hydraulic pump from being previously supplied to the second switching valve, resulting in insufficient switching of the second switching valve.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing an embodiment of the present invention, Fig. 2 is a sectional view showing an example of a pressure control valve, Fig. 3 is a graph showing the output characteristics of the pressure control valve, and Fig. 4 is a pump section. FIG. 5 is a block diagram showing the discharge amount control circuit, FIGS. 6 to 8 are flowcharts showing an overview of the processing executed by the mode setting circuit, and FIG. 9(a) is a graph showing the discharge amount characteristics. A diagram showing the state of the electromagnetic directional control valve in mode 1, Fig. 9 (b
) is a diagram showing the state of the electromagnetic directional control valve in mode 2,
FIG. 9(C) is a diagram showing the state of the electromagnetic directional control valve in mode 3. 6... Active suspension (fluid pressure equipment), 8...
・Hydraulic pressure supply device (fluid pressure supply device), 30...tank, 34A...first hydraulic pump (first pump), 3
4B...Second hydraulic pump (second pump), 38a
...first supply side pipe line (first supply line), 38b...
・Second supply side pipe line (second supply line), 39A...check valve (first check valve), 39C...check valve (second check valve), 42...electromagnetic direction Switching valve (
(first switching valve), 43...electromagnetic directional switching valve (second switching valve), 44...first return path, 46...second return path, 48...third return path Return path, 50...Discharge amount control circuit

Claims (2)

[Claims] (1) A first pump, a first supply path interposed between the discharge side of the first pump and the fluid pressure equipment, and a first supply path provided in the first supply path and directed to the first pump side. a first check valve that prevents backflow of fluid; a first return path branched from the first supply path upstream of the first check valve; and a discharge amount higher than that of the first pump. The second one with less
a second supply path interposed between the discharge side of the second pump and the fluid pressure device; and a second supply path provided in the second supply path and configured to prevent backflow to the second pump side. a second check valve, a second return path branched from the second supply path upstream of the second check valve, and one of the first and second return paths connected to the tank. a first switching valve that communicates with a third return path leading to the third return path; a second switching valve that connects or blocks the third return path; and a state of the first and second switching valves. switching valve control means for controlling the switching of the second switching valve from the blocking state to the communication state when the first switching valve is in the second return path. A fluid pressure supply device characterized in that the fluid pressure supply device performs the above operation while communicating with the third return path. (2) The switching valve control means controls switching of the first switching valve and switching of the second switching valve in a direction in which the flow rate of the third return path increases, and the switching of the first switching valve and the second switching valve before switching. The fluid pressure supply device according to claim 1, wherein the fluid pressure supply device is operated after the state of the valve is maintained for a predetermined period of time or more.