JP2699643B2 - Fluid pressure supply device for vehicles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fluid pressure supply device for a vehicle, and in particular, to a fluid pressure cylinder interposed between a vehicle body and wheels in which an operation flow rate and an operation pressure constantly change. The present invention relates to a fluid pressure supply device suitable for supplying pressure energy.

[Conventional technology]

As a conventional vehicle fluid pressure supply device, for example, a device described in Japanese Utility Model Application Laid-Open No. 62-201134 proposed by the present applicant (the name of the device is "hydraulic suspension hydraulic pressure supply device") is known. I have.

This conventional hydraulic supply device uses a hydraulic suspension provided with a hydraulic cylinder interposed between each wheel and a vehicle body and a control valve for controlling the operating hydraulic pressure of the hydraulic cylinder as a load, and applies hydraulic energy to the load. It is a device for supplying.
Specifically, a hydraulic pump connected to a rotary drive source such as an engine, an actuator and a relief valve connected to a discharge side thereof, and a discharge amount per one rotation of the hydraulic pump,
And a discharge amount control device that performs control in accordance with the consumption flow rate of the hydraulic suspension.

[Problems to be solved by the invention]

The conventional hydraulic supply device described above is effective in that the discharge amount is controlled in accordance with the consumed flow rate of the load to reduce the horsepower consumed by the pump. However, in the conventional device, the relief pressure of the relief valve installed on the discharge side of the hydraulic pump is
In order to secure the operating pressure at the time of suppressing the posture change, the configuration is fixed and set to a higher predetermined value. For this reason, for example, even when the vehicle is traveling straight on a flat good road at a constant speed and the flow rate of the hydraulic suspension is small (that is, when the load pressure fluctuation of the suspension is usually small), a high line is generated by the relief pressure. Since the pressure is set, the consumed horsepower represented by the product of the discharge flow rate and the discharge pressure includes wasteful consumption, and the energy efficiency is reduced by that amount. Was.

The present invention has been made in view of such a conventional unsolved problem, and adjusts the discharge flow rate and the discharge pressure in accordance with the consumed horsepower required by the fluid pressure cylinder to further reduce the wasteful horsepower. It is an object to solve the problem to reduce the energy consumption and increase the energy efficiency.

[Means for solving the problem]

In order to solve the above-mentioned problems, a fluid pressure supply device for a vehicle according to the present invention includes a fluid pressure discharge mechanism capable of changing a discharge flow rate, as shown in FIG. And a fluid pressure supply device for a vehicle that supplies a fluid pressure to a fluid pressure cylinder interposed between wheels, wherein a relief pressure can be changed to a flow path from the fluid pressure discharge mechanism to a pressure control valve that controls the fluid pressure cylinder. And a consumption flow estimating means for estimating the consumption flow rate of the fluid pressure cylinder based on the running state of the vehicle,
A discharge amount determining unit that compares the estimated value of the consumed flow rate estimating unit with a discharge capacity of the fluid pressure discharging mechanism and determines a necessary minimum discharge amount capable of covering the estimated consumed flow amount, and a determination of the discharged amount determining unit. A discharge amount control means for changing a discharge amount of the fluid pressure discharge mechanism in accordance with a value; and a relief pressure control means for changing a relief pressure of the relief valve in accordance with a value determined by the discharge amount determination means. .

[Action]

In the present invention, the consumption flow rate of the hydraulic cylinder is estimated based on the running state of the vehicle, and the estimated value is compared with the discharge capacity of the hydraulic pressure discharge mechanism, and the necessary minimum discharge amount that can cover the estimated consumption flow rate is calculated. It is determined. Then, the discharge amount of the fluid pressure discharge mechanism is changed and the relief pressure of the relief valve is changed according to the discharge amount determination value. Specifically, for example, when the discharge pressure of the fluid pressure discharge mechanism is increased while the relief pressure is always set to a lower value, the relief pressure is increased, and the relief pressure is always set to a higher value. In this case, when the discharge amount of the fluid pressure discharge mechanism is reduced, the relief pressure is reduced. As a result, when the consumption flow rate of the hydraulic cylinder is small, the pressure fluctuation of the hydraulic cylinder due to the pressure control valve is small, and the maximum pressure required for the hydraulic cylinder control can be reduced. It becomes the operation state corresponding to the state. Accordingly, since the discharge amount is reduced and the supply line pressure is further reduced, the horsepower consumption of the discharge mechanism is further reduced.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the attached FIGS.

In FIG. 2, 2 indicates a vehicle body, 4 indicates wheels, and 6 indicates an active suspension as a load. Reference numeral 8 denotes a hydraulic pressure supply device as a vehicle fluid pressure supply device.

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

The hydraulic cylinder 10 has a cylinder tube 10a mounted on the vehicle body 2 side and a piston rod 10b mounted on the wheel 4 side, and a pressure chamber L is separated from the cylinder tube 10a by a piston 10c. The pressure chamber L communicates with an output port of the pressure control valve 12 via a pipe 20.

The pressure control valve 12 is capable of adjusting a valve housing, a spool slidable in an insertion hole of the valve housing, and a pilot pressure applied to the other end of the spool in response to a feedback pressure applied to one end of the spool. It comprises a conventionally known three-port proportional electromagnetic pressure reducing valve having a proportional solenoid (for example, see Japanese Patent Application Laid-Open No. 1-122717). Therefore, the output pressure can be controlled in proportion to the command value I supplied to the proportional solenoid.

Lateral acceleration sensor 19 detects the acceleration in a lateral direction generated in the vehicle body 2, is also supplied with electrical signals G ₁ corresponding to the amount their state in the discharge amount relief pressure control circuit for posture control circuit 18 described later, and You. Attitude control circuit 18, the detection signal G ₁ performs operations such as multiplying a predetermined gain, and supplies the pressure control valve 12 by calculating the inhibit command value I of the vehicle body roll.

In FIG. 2, reference numeral 22 denotes a coil spring for supporting a static load of the vehicle body 2, and reference numerals 24 and 26 denote an aperture and an accumulator for attenuating vibration in an unsprung resonance region.

On the other hand, the hydraulic pressure supply device 8 includes a tank 30 for storing hydraulic oil.
And a hydraulic pump 34 having a suction side connected to the tank 30 via a pipe 32. The hydraulic pump 34 is a variable discharge type pump system connected to the output shaft 36A of the engine 36, and is specifically a plunger type pump having a plurality of cylinders. Then, a first hydraulic pump 34A having a relatively large discharge amount per one rotation is constituted by one set of every other cylinder in each cylinder, and one set is constituted by the other set.
A second hydraulic pump 34B having a small discharge amount per rotation is configured.

Here, the discharge flow rate characteristics with respect to the rotation speeds of the first and second hydraulic pumps 34A and 34B are as shown in FIG. That is, at the time of attitude control where the consumption flow rate is large, the discharge amount of the first and second hydraulic pumps 34A and 34B is used. In the middle state, the first hydraulic pump 34A
Has become as a cover, the flow rate to meet these required amount _{Q a, Q b (Q a} > Q b) is set.

The first supply-side conduit 3 is provided at the discharge port of the first hydraulic pump 34A.
8a is connected, and this line 38a reaches the supply port of the pressure control valve 12 via the check valves 39A and 39B. A drain port 40 is connected to the return port of the pressure control valve 12, and the pipe 40 reaches the tank 30 via the operation check valve 41. The operation check valve 41 is for containing the cylinder operating oil after the engine stops, and the check valve 39B
Of which the downstream line pressure is composed of a pilot-operated check valve to the pilot pressure P _P. In this embodiment, when the pilot pressure P _P > P _N (where P _N is the operating neutral pressure), the check is released (the valve is open) and the line 40 is communicated, and when P _P ≤P _N , the check is performed. (The valve is closed) and the line 40 is shut off.

A second supply-side pipeline 38b is connected to the discharge port of the second hydraulic pump 34B, and this pipeline 38b is connected to a downstream side of the check valve 39A of the first supply-side pipeline 38a via a check valve 39C. It is connected to the.

Further, as shown in FIG.
An electromagnetic directional control valve 42 at port 3 is provided. The switching valve 42 is switched by turning on and off switching signals CS ₁ and CS _2. When both CS ₁ and CS ₂ are off, the first input port 42 a is closed and the second input port 42 b and the output When port 42c is in communication (medium flow switching position), CS ₁ is on and CS ₂ is off, all ports are closed (high flow switching position), and CS ₁ is off and C
The when S ₂ is on first input port 42a and an output port 4
2c communicates and the second input port 42b is in the closed state (switching position at small flow rate).

The first input port 42a of the switching valve 42 communicates with the discharge side of the first supply side pipeline 38a via a pipe 44, and the second input port 42b communicates with the second supply side pipeline via a pipe 46. It communicates with the discharge side of 38b. Further, the output port 42c of the switching valve 42
Leads to the tank 30 via the line 48.

In this embodiment, the hydraulic pump 34, the check valves 39A, 39C,
The electromagnetic direction switching valve 42 constitutes a hydraulic discharge mechanism 50 as a fluid pressure discharge mechanism.

A relief valve 52 for determining a line pressure is connected between the supply-side pipe line 38a (a position between the check valves 39A and 39B) and the drain-side pipe line 40. The relief valve 52 has a proportional solenoid for setting a relief pressure, and a control signal RF is supplied to the proportional solenoid. Therefore, the level of the relief pressure of the relief valve 52 can be changed in proportion to the value of the control signal RF.

Further, the hydraulic pressure supply device 8 includes a discharge amount / relief pressure control circuit 54, a pump speed sensor 56, and a stroke sensor.
It has 58FL and 58FR. The pump speed sensor 56 is configured to also serve as, for example, an engine speed sensor, detects an electric signal N corresponding to the speed of the hydraulic pump 34,
Output to the relief pressure control circuit 54. Stroke sensor 58
FL and 58FR are the body 2 and wheels (front left and front right wheels) 4,4
To be configured in each interposed a potentiometer, and outputs the detection signal x _L, the x _R to the control circuit 54.

The discharge amount / relief pressure control circuit 54, as shown in FIG.
Enter stroke position signal x _L, a band-pass filter 66, 68 for filtering the x _R, the output signal x _L of the band-pass filter 66, an integrator 70, 72 for performing integration operation which will be described later in x _R, and a pilot flow rate setting unit 74, furthermore, the output signal Q _L of the integrators 70, 72 and a pilot flow rate setting unit 74, an adder 76 for adding the Q _R and Q _O to each other in the adder 76 _A setting circuit 78 that receives the addition signal Q _A , the pump speed signal N, and the lateral acceleration signal G ₁ , selects an operation mode and sets a relief pressure, and an output signal of the setting circuit 78.
Receiving SL ₁ , SL ₂ and DP, switching signal C to electromagnetic directional switching valve 42
And a drive circuit 80A~80C for outputting S _1, CS ₂ and a control signal RF.

The lower cut-off frequency f _L of each of the band-pass filters 66 and 68 is set to a value (for example, 0.5 Hz) that can cut off a stroke change at the time of adjusting the vehicle height, and the higher cut-off frequency f _H is set to the unsprung resonance frequency side. Is set to a value (for example, 6 Hz) at which the change in stroke can be cut off. Also, each integrator 70, 72 (The suffixes L and R for x are omitted) and the integral of the stroke change, that is, the integral time T (for example, 2
The flow rate Q to / from the cylinder corresponding to the total stroke amount “1 / T · ∫ || dt” within the second) is obtained. K is a gain based on the pressure receiving area of the hydraulic cylinder 10.

Here, when attention is paid to the actual stroke variation between the vehicle body 2 and the wheels 4, in most cases, vibrations appear symmetrically on the extension side and the contraction side. However, the flow is actually consumed only when the stroke changes to the extension side and the hydraulic oil flows into the hydraulic cylinder 10, and when the stroke changes to the contraction side and the hydraulic oil is discharged, the operation is performed. There is no need to supply oil. However, the flow rate corresponding to the amount by which the stroke changes to the contraction side may be exactly the amount of hydraulic oil flowing into the hydraulic cylinder 10 on the rear wheel side.
The calculated value of the above equation (1) for the two front wheels eventually approximates the consumed flow rate for the total stroke change of the four wheels.

Further, the pilot flow rate setting device 74 outputs a value Q _O corresponding to the amount of internal leak of the pressure control valves 12 for the four wheels. Therefore, the addition result Q _A of the adder 76 becomes the estimated consumption rate of the entire system.

Further, the setting circuit 78 includes, for example, a microcomputer, and stores in advance a mode map corresponding to the discharge flow rate characteristic of FIG. 3 described above, and executes the processing of FIG. (For example, 20 msec <T) is performed every time. Among them, in the processing of FIG. 5, the operation modes I to III are set for each time T synchronized with the integration cycle, and the signals SL ₁ and SL ₂ of logical values corresponding to the modes I to III are output. Here, mode I is an operation state in which the second hydraulic pump 34B, mode II is a first hydraulic pump 34A, and mode III is an operation state in which the first and second hydraulic pumps 34A and 34B are connected to the supply lines, respectively. is there. Process Figure 6 is one in which the lateral acceleration becomes a state of a predetermined value or more, sets the boost value β for increasing the estimated consumption rate Q _A.

The setting circuit 78 sets the integrators 70 and 72 every time the integration time ends.
Reset. Further, the drive circuits 80A and 80B
L ₁ or SL ₂ of logic value "0", corresponding to "1", the switching valve 4
Off the output signal CS ₁ or CS ₂ for 2, to turn on. The drive circuit 80C outputs a control signal FR proportional to the value of the input signal DP to the relief valve 52.

Next, the processing operation of the setting circuit 78 will be described. The fifth,
The flags F1, F2, F3, the counters c, d, and the increment value β relating to the timer interrupt processing in FIG. 6 are initialized to zero by the main program at the time of startup.

First, in FIG. 5, the counter c is incremented every Δt time in that step, and the predetermined time T
It is determined whether or not an integer A corresponding to (= Δt · A) has been reached. If the count value of the counter c has not reached A in this determination, it is determined whether or not the flag F1 of the step is 1 or not. The flag F1 = 1 means that the lateral acceleration is equal to or higher than a predetermined value or within a mode holding period thereafter. Therefore, if "NO" in the step, the process returns to the main program, and the operation mode currently instructed is maintained as it is.

On the other hand, if “YES” in the step, the counter is set to c = 0 in the step, and then the process proceeds to the step. In the step, it is determined whether or not the flag F3 = 1. Flag F3
= 1 indicates that the lateral acceleration has become equal to or more than the predetermined value, and that the increase command has already been issued. Therefore, when the determination in the step is YES, the process returns as it is, but when the determination is NO, the process of the step is performed.

Among them, enter the estimated consumption flow rate signal Q _A is the addition result of the adder 76 keep step and stores that value as the flow value. In the step, the detection signal N of the pump rotation speed sensor 56 is input, and the value is stored as the rotation speed.

First, in the step, read is determined by the processing of FIG. 6 to be described later, the value of the bulking variable β for estimating consumption rate Q _A from the predetermined storage area. In the step, Q _AA = Q _A
+ An estimated consumption rate Q _A by the operation of the beta and increased by beta, determine an estimated consumption rate Q _AA was modified. Further, in the step, the mode of the minimum discharge flow rate to which the coordinate point uniquely determined by the corrected estimated consumption flow rate Q _AA and the pump rotation speed N belongs is set with reference to the map corresponding to FIG. That is, the setting signal SL ₁ = logic “0”, SL ₂ = logic “1” for mode I, SL ₁ = logic “0”, SL ₂ = logic “0” for mode II, and SL _{1 for} mode III = Logic “1”, SL ₂ = logic “0”.

Next, in a step, signals SL ₁ and SL ₂ corresponding to the setting mode are output to the drive circuits 80A and 80B.

The process further proceeds to step and determines whether or not the mode set in step is down, that is, whether or not the mode is mode I.
This determination is to change the relief pressure of the relief valve 53 according to the magnitude of the load flow rate. If the determination in this step is NO, it is determined that the mode I corresponding to the small load flow rate has not been set and the step Move to In step, so that it can respond to large pressure fluctuations during vehicle body attitude control, set to a predetermined value P _H of the higher you set the relief pressure command value prior. However, if the determination in the step is YES, the process proceeds to the step assuming that the mode I has been set, and the relief pressure command value is reduced to the lower predetermined value P _L.
(<P _H : see Fig. 8).

Then proceeds to step, and outputs a logic signal DP to the relief valve 52 corresponding to the step or relief pressure command value set by P _H or P _L, the process returns. Accordingly, relief pressure of the relief valve 52 is set to the target value P _H or P _L.

If "YES" in the above step, it is determined that the lateral acceleration has exceeded the reference value during the setting of the regular mode related to the integration (= A) of the counter c, and the determination of the step is made. In the step, it is determined again whether or not the above-mentioned flag F3 = 1, and in the case of YES, the process returns to the main program and N
In the case of O, the processing after the step is performed through the setting of the step flag F3 = 1.

Meanwhile, in the processing of FIG. 6, reads the detection signals G ₁ of the lateral acceleration sensor 19 at that step, Step | G ₁ |
It is determined whether or not ≧ α (α is a predetermined value capable of discriminating a state where the lateral acceleration is large). If “NO” in this step, the lateral acceleration has not occurred or is small. Then, the process proceeds to the step, and it is determined whether or not the above-described flag F1 = 1, and in the case of NO, the increase value β = 0 in the step,
Return to the main program.

If the result of the above step is "YES", the process proceeds to step and a counter d described later is cleared, and the process of step is performed. In the step, set F1 = 1,
In the step, the increase value β = β ₀ (β ₀ is a predetermined flow rate value suitable for compensating the consumption flow rate when the lateral acceleration becomes large) is set, and then the process returns.

When the answer is YES in the above step, it is determined whether or not the counter value c = 0 in the step. The counter value c is counted in the step of FIG. When the answer is NO in this step, the process returns as it is, and when the answer is YES, the counter d = d + 1 is counted up in the step, and the process proceeds to the determination in the step. In the step, it is determined whether or not the counter d = 2. In the case of NO, the process returns to the main program, and in the case of YES, the process of the step is performed and the process returns. In the step, the increase value β = 0 is set, and in the step, the flags F1, F3 =
0 and the counter d = 0.

Among the above configuration and processing, detection signals G ₁ and a stroke sensor 58FL of the lateral acceleration sensor 19, 58 FR of the detection signal x _L, x
_R corresponds to the running state of the vehicle in the present invention, and the stroke sensors 58FL, 58FR, the lateral acceleration sensor 19, the filters 66, 6
8, integrators 70 and 72, pilot flow rate setting device 74, adder 76,
5 and the processing of FIG. 6 constitute the consumed flow rate estimating means. The processing of the pump speed sensor 56 and the steps in FIG. 5 constitute the discharge amount determining means, and the processing and the drive circuits 80A and 80B in the steps of FIG. 5 constitute the discharge amount control means.
The processing and the drive circuit 80C of FIG. 5 to constitute the relief pressure control means.

 Next, the overall operation will be described.

Now, it is assumed that the vehicle is traveling straight at a constant speed on a good road without unevenness, the operation check valve 41 is “open”, and both the supply path and the return path are in communication.

In this state, almost no vibration input from the road surface, a change in the stroke between the vehicle body 2 and the wheels 4, and no external force on the vehicle body 2 are generated. For this reason, stroke sensors 58FL, 58FR
And the position signals x _L and x _R of the band pass filter 6
The extracted component of 6,68 becomes a value close to zero, and the added value of the adder 76
Q _A ≒ Q _O and the estimated consumption flow rate is small.

On the other hand, since the lateral acceleration G ₁ ≒ 0, the setting circuit 78 executes the processing of steps 1 to 3 in FIG.
F1 = 0 and the increase value β = 0 are maintained. Therefore, in the processing of FIG. 5, only the regular mode setting through steps,.

Since the estimated consumption flow rate Q _{AA in} the current running state is small, for example, a point m ₁ (N ₁ , Q ₁ ) on the map in FIG. 3 is designated, and the mode I is set thereby. Therefore, the output signals SL ₁ = “0” and SL ₂ = “1” of the setting circuit 78, and the switching signal CS
₁ = OFF, CS ₂ = ON, and the electromagnetic directional control valve 42 assumes the “switching position at small flow rate” as described above. Therefore, the first hydraulic pump 34A becomes no-load operation, a small discharge flow rate Q _b of the second hydraulic pump 34B is supplied.

On the other hand, by the mode I as described above are set, as set circuit 78 shown in Figure 8, sets the relief pressure command value to a lower value P _L, corresponding to the command value P _L signal
Output DP. As a result, the control signal RF is
Sent to, the relief pressure is set to P _L. Therefore, the line pressure supplied to the active suspension 6 comprises a low value determined by the relief pressure P _L.

Thus, when the consumption rate of the active suspension 6 is estimated to be small, the hydraulic ejection mechanism 50, i.e., with reducing the discharge amount of the hydraulic pump 34, also decreases to a predetermined value P _L to the line pressure. This is a state where the vehicle is traveling straight on a good road when the low discharge amount equivalent mode (in this case, mode I) is selected in actual traveling,
Based on the fact that the cylinder pressure fluctuations are small, the required maximum pressure is low and the relief pressure is low. Therefore, the horsepower consumed by the pump, which is determined by the product of the discharge flow rate and the discharge pressure, becomes closer to the value corresponding to the truly required hydraulic energy, and the energy efficiency is further improved as compared with the conventional art, and the fuel efficiency is improved.

Further, the lateral acceleration G ₁ from the running state, for example, performing a lane change or turning is changed as shown in Figure 7.
In contrast, although until the time t ₁₁ the setting of the mode I mentioned above, at time t ₁₁ | G ₁ | second from a ≧ alpha 6
A process passing through the steps shown in FIG. 5 is executed, and a process passing through the steps shown in FIG. 5 is executed. As a result, increase value β = β ₀ next, try adding the increase value β ₀ in the estimated consumption flow rate Q _AA at that time, see if its value belongs to which mode. For example, if Q _AA = Q ₁ , mode II is set when Q ₁ + β ₀ falls within the range of Q _a (see FIG. 3), and mode III is set when Q ₁ + β ₀ falls within the range of Q _a + Q _b . However, when the addition result of Q ₁ + β ₀ does not reach any of them, the mode I is maintained because it is determined that the ejection amount still has enough power. Thus, when the flow rate lateral acceleration G ₁ is increased is considered to have increased, the emergency mode setting has interrupted the scheduled mode setting is performed, when the flow rate increase is required due to the mode II or III A middle or large flow rate is supplied to the load side to satisfy the required flow rate of the suspension 6.

At the same time, as a result of the mode setting described above,
Or the III is set, the relief pressure is set to a value P _H of the higher, as shown in Figure 8. Therefore, the line pressure is high value P _H next supplied to the active suspension 6 can supply sufficient hydraulic pressure to large variations in load pressures, nor the load is controlled insufficient.

Returning to FIG. 7, the operation mode at the time t ₁₁ to the raised to the II or III from I. The status of this new mode is 5th and 6th
At time t ₂₂ based on the flag F1 = 1 and the counters c and d in the figure.
It is the rest of the time T _F of belonging integration period, and continues until time t ₄ when adding one more alternative integration period T. Thus, until the lateral acceleration G ₁ is sufficiently converged to zero, and the flow consumption is relatively large, and supplies a sufficient amount of hydraulic oil. The seventh
In the figure, the swing back of the lateral acceleration G ₁ is small, and G ₁ is −α
Mode II or holding period III if not exceed the t ₁₂ ~t ₃
Up to.

When in the example of FIG. 7 time t ₄ has passed, the flag
Becomes F1, F3 = 0 and the counter d = 0 (FIG. 6 step), returns to the state of the mode I mentioned above, and, is set to the relief pressure is also low value P _L, the line pressure decreases.

As described above, in the present embodiment, the relief pressure is changed in accordance with the estimated value of the consumed flow rate, in addition to eliminating waste of horsepower consumed, and the current control of the hydraulic discharge mechanism 50 for roll control involving large flow rate consumption. Check in advance whether the discharge flow rate of the tank has enough capacity to compensate for the flow rate newly used for roll control,
The mode is increased only when there is no spare capacity to increase the amount. Therefore, the waste that the amount is increased despite the surplus is eliminated. Further, in the case of a sudden lane change at a high speed, the generated lateral acceleration has a waveform close to a pulse, but there is no chattering due to the mode change by securing the holding time, and a stable line pressure is secured. .

In the embodiment described above, | G ₁ | While boost value beta ₀ to be added during ≧ alpha was a constant value regardless of the magnitude of the lateral acceleration G _1, for example, the magnitude of the lateral acceleration G ₁ The increase value β may be changed in proportion.

Further, the hydraulic discharge mechanism of the present invention has a configuration in which the discharge amount can be switched to three stages using a plurality of hydraulic pumps, but may be two stages as required. Further, as the hydraulic discharge mechanism, a single variable displacement pump capable of continuously changing the discharge amount in accordance with a command signal may be used, and the above-described variable relief pressure relief valve may be provided on the discharge side. .

Further, the active suspension is not limited to the case where only the roll control is performed as described above, and may be provided with a configuration for performing the pitch control and the bounce control.

Furthermore, the fluid pressure supply device of the present invention is not limited to a device using hydraulic oil, but may be a device using gas.

〔The invention's effect〕

As described above, in the present invention, a relief valve capable of changing a relief pressure is provided in a flow path from a fluid pressure discharge mechanism to a pressure control valve for controlling a fluid pressure cylinder, and a fluid pressure estimated based on a running state of a vehicle is provided. The discharge amount of the fluid pressure discharge mechanism is controlled so that the consumption flow rate of the cylinder can be minimized, and the relief pressure of the relief valve is changed according to the discharge amount (for example, when the discharge amount is increased, the relief pressure is increased). , Or, when the discharge amount is reduced, the relief pressure is lowered).
When the estimated consumption flow rate is small, it is usually easy to achieve a state in which the required maximum line pressure is small, and by reducing the relief pressure, the consumed horsepower is surely reduced compared to the conventional device, and the energy efficiency is reduced. It can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims. 2 to 8 are views showing an embodiment of the present invention. FIG. 2 is an overall block diagram, FIG. 3 is a discharge flow rate (estimated consumption flow rate) characteristic diagram, and FIG. Block diagram of relief pressure control circuit, FIG.
FIG. 6 and FIG. 6 are flow charts each showing an example of the processing procedure of the setting circuit, FIG. 7 is a graph showing an example of a change in lateral acceleration, and FIG. 8 is a graph showing an example of the relationship between the mode (discharge amount) and the relief pressure. . In the drawing, 6: active suspension, 8: hydraulic supply device for vehicle, 34: hydraulic pump, 50: hydraulic discharge mechanism, 52
…… Relief valve, 54 …… Discharge amount / relief pressure control circuit,
56: Pump rotation speed sensor, 58FL, 58FR: Stroke sensor.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Itaru Fujimura It is Nissan Motor Co., Ltd. (2) Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (72) Inventor Kensuke Fukuyama 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (56) References JP-A-60-64013 (JP, A) JP-A-62-1201134 (JP, U)

Claims (1)

(57) [Claims] A fluid pressure for a vehicle, comprising a fluid pressure discharge mechanism capable of changing a discharge flow rate, and supplying a working fluid discharged from the discharge mechanism to a fluid pressure cylinder interposed between a vehicle body and wheels. In the supply device, a relief valve capable of changing a relief pressure is provided in a flow path from the fluid pressure discharge mechanism to a pressure control valve that controls the fluid pressure cylinder, and consumption of the fluid pressure cylinder is determined based on a running state of a vehicle. Consumption flow estimating means for estimating the flow rate, and a discharge amount determination for comparing the estimated value of the consumption flow estimating means with the discharge capacity of the fluid pressure discharge mechanism and determining a necessary minimum discharge amount capable of covering the estimated consumption flow rate Means, discharge amount control means for changing the discharge amount of the fluid pressure discharge mechanism according to the determined value of the discharge amount determining means, and relief of the relief valve according to the determined value of the discharge amount determining means. A fluid pressure supply device for a vehicle, comprising relief pressure control means for changing a leaf pressure.