JP2007033137A - Working fluid pressure control device and pressure sensor output characteristic correction method - Google Patents

Abstract

PROBLEM TO BE SOLVED To reduce the influence of an error of a pressure sensor when controlling the pressure of a working fluid.
A working fluid pressure control device (10) has a left front wheel WC pressure sensor (44FL) whose output characteristics are set under a first initial correction pressure and that measures the pressure of a working fluid supplied to a first object; A right front wheel WC pressure sensor 44FR for measuring the pressure of the working fluid supplied to the second object, the output characteristic of which is set under a second initial correction pressure different from the first initial correction pressure, and a WC pressure sensor The output characteristic of the left front wheel WC pressure sensor 44FL is corrected based on the output of the left front wheel WC pressure sensor 44FL when the second initial correction pressure acts on both 44FL and 44FR, and both the WC pressure sensors 44FL and 44FR are corrected. An ECU 200 that corrects the output characteristics of the right front wheel WC pressure sensor 44FR based on the output of the right front wheel WC pressure sensor 44FR when the first initial correction pressure is applied. .
[Selection] Figure 1

Description

  The present invention relates to a working fluid pressure control device that controls the pressure of a working fluid supplied to each of a plurality of objects, and a pressure sensor output characteristic correction method suitable for the device.

2. Description of the Related Art Conventionally, a brake control device that applies a desired braking force to each of a plurality of wheels is known. In this brake control device, the wheel cylinder pressure is controlled so that a desired braking force is applied to each wheel based on the measurement values of a plurality of pressure sensors (see, for example, Patent Document 1). These pressure sensors are generally initially corrected under atmospheric pressure. The initial correction means setting an output characteristic, which is a relationship between a pressure acting on the pressure sensor and an output of the pressure sensor at that time, under a predetermined initial correction pressure when the apparatus is manufactured.
Japanese Patent Laid-Open No. 2003-137082

  Although the pressure sensor subjected to the initial correction can measure the pressure near the initial correction pressure with high accuracy, an error is included in the measured value as the pressure to be measured becomes far from the initial correction pressure. Therefore, when controlling a predetermined amount based on the measurement value of such a pressure sensor, it is desirable to consider the influence of errors.

  Accordingly, the present invention provides a working fluid pressure control capable of reducing the influence of the error of the pressure sensor when controlling the pressure of the working fluid supplied to each of the plurality of objects based on the measurement value of the pressure sensor. An object of the present invention is to provide a device and a pressure sensor output characteristic correction method capable of reducing an error of the pressure sensor.

  In order to solve the above-described problem, a working fluid pressure control device according to an aspect of the present invention is a working fluid pressure control device that controls the pressure of a working fluid supplied to each of a plurality of objects. A first pressure sensor for measuring the pressure of the working fluid supplied to the first object, the output characteristic of which is set under the initial correction pressure, and a second initial correction pressure different from the first initial correction pressure And the second initial correction pressure acts on both the first pressure sensor and the second pressure sensor for measuring the pressure of the working fluid supplied to the second object. The second pressure when the first initial correction pressure acts on both the first and second pressure sensors by correcting the output characteristics of the first pressure sensor based on the output of the first pressure sensor at the time Compensate the output characteristics of the second pressure sensor based on the sensor output. It comprises a correcting means for, the.

  According to this aspect, the pressure at the time of initial correction that one pressure sensor can measure with high accuracy is applied to both pressure sensors, and the output of the other pressure sensor is output from the output of the other pressure sensor at this time. Correct the characteristics. By performing such correction mutually between the two pressure sensors, the output characteristics of both pressure sensors are corrected, and the error of the measurement value is reduced. Therefore, the influence of the error of the pressure sensor can be reduced.

  In this case, a first flow path that connects the working fluid source and the first object and has the first pressure sensor in the middle so that equal pressure acts on both the first and second pressure sensors; You may further provide the communication means which can connect the working fluid source and the 2nd target object, and the 2nd flow path which has the 2nd pressure sensor in the middle. If it does in this way, the flow of a working fluid can be connected by a communication means, and the pressure which acts on both sensors can be made equal equally.

  The first object is a first wheel cylinder for applying a braking force to a first wheel provided in the vehicle, and the second object is a second wheel provided in the vehicle. A second wheel cylinder for applying a braking force to the first and second wheel cylinders, wherein the communication means is controlled when the braking force is applied to each of the first and second wheels. In addition, a flow path control unit that communicates the flow path of the working fluid so that equal pressure acts on both the first and second pressure sensors may be further provided.

  In this way, it is possible to correct the output characteristics when a braking force is applied to the wheel, for example, one correction per 10 brakings. Therefore, it becomes possible to improve the accuracy of the pressure sensor at a relatively high frequency during traveling.

  On the other hand, the first object is a first wheel cylinder for applying a braking force to a first wheel provided in the vehicle, and the second object is a second wheel provided in the vehicle. A second wheel cylinder for applying a braking force to the first and second wheels when the braking force is not applied to each of the first and second wheels by the first and second wheel cylinders. You may further provide the flow-path control part which connects the flow path of a working fluid so that the same pressure may act on both of 2 pressure sensors.

  In this way, for example, after the driving source of the vehicle is stopped and the driver leaves the vehicle, the flow path of the working fluid is communicated when the braking force is not applied to the wheel by the wheel cylinder. Can do. Then, when applying a braking force to each wheel, it is possible to apply an equal pressure to a plurality of pressure sensors, which normally have different pressures, regardless of the application of the braking force to the wheels. As a result, since it is possible to perform correction over a longer time than when correction is performed during braking, the correction can be performed more reliably.

  In this case, the output pressure is set under a third initial correction pressure that is different from both the first and second initial correction pressures, and the third pressure that measures the pressure of the working fluid supplied to the third object. The output pressure is set under a sensor and a fourth initial correction pressure different from any of the first to third initial correction pressures, and a fourth pressure for measuring the pressure of the working fluid supplied to the fourth object And a correction means, when the second initial correction pressure acts on both the first and second pressure sensors, and the third initial correction on both the first and third pressure sensors. The output of the first pressure sensor based on the output of the first pressure sensor when the pressure acts and when the fourth initial correction pressure acts on both the first and fourth pressure sensors, respectively. The characteristics may be corrected. In this way, the output characteristic of the first pressure sensor that is the correction target can be corrected based on the output of the first pressure sensor under the initial correction pressure of each of the other three pressure sensors. Pressure can be measured with high accuracy.

  Further, the first initial correction pressure is included in the pressure range of the working fluid that normally acts on the first wheel cylinder during braking, and the second initial correction pressure is normally applied to the second wheel cylinder during braking. It may be included in the pressure range of the working fluid acting on. In this way, since the error of the pressure sensor in the pressure range that normally acts on the wheel cylinder during braking can be reduced, the control performance of the braking force is improved.

  Further, both the first wheel and the second wheel may be front wheels or rear wheels, and one may be a wheel on the right side of the vehicle and the other may be a wheel on the left side of the vehicle. In this way, the difference in error between the pressure sensors corresponding to the left and right wheels of the front wheel or the rear wheel can be reduced, so that the pressure difference between the left and right can be controlled to be small. For this reason, the straight running stability of the vehicle during braking is improved.

  Another aspect of the present invention is a pressure sensor output characteristic correction method. This method sets the output characteristic of the first pressure sensor under a first initial correction pressure, and sets the output characteristic of the second pressure sensor under a second initial correction pressure different from the first initial correction pressure. Set and correct the output characteristics of the first pressure sensor based on the output of the first pressure sensor when the second initial correction pressure acts on both the first and second pressure sensors, The output characteristic of the second pressure sensor is corrected based on the output of the second pressure sensor when the first initial correction pressure acts on both of the second pressure sensors. Also according to this aspect, it is possible to mutually correct the output characteristics between the two pressure sensors, and it is possible to reduce an error in the measurement value of the pressure sensor.

  ADVANTAGE OF THE INVENTION According to this invention, when controlling the pressure of the working fluid supplied to each of a several target object based on the measured value of a pressure sensor, the influence of the error of a pressure sensor can be made small.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system diagram showing a pressure control system of a working fluid pressure control apparatus 10 according to the first embodiment of the present invention. The working fluid pressure control device 10 shown in the figure constitutes an electronically controlled brake system (ECB) for a vehicle, and independently controls the brake pressures of the four wheels of the vehicle according to the operation of the brake pedal 12 by the driver. And it is set optimally. The brake pedal 12 is connected to a master cylinder 14 that sends out brake oil as working fluid (working fluid) in response to a depression operation by a driver. The brake pedal 12 is provided with a stroke sensor 46 for detecting the depression stroke. Further, a reservoir tank 26 is connected to the master cylinder 14. A stroke simulator 24 that creates a reaction force according to the operating force of the brake pedal 12 by the driver is connected to one output port of the master cylinder 14 via a stroke simulator on-off valve 23. The stroke simulator open / close valve 23 is a normally closed solenoid valve that is closed when not energized and is switched to an open state when an operation of the brake pedal 12 by the driver is detected.

  A brake hydraulic control pipe 16 for the right front wheel is connected to one output port of the master cylinder 14, and the brake hydraulic control pipe 16 is a wheel cylinder for the right front wheel that applies a braking force to the right front wheel 19FR. It is connected to 20FR. A brake hydraulic control pipe 18 for the left front wheel is connected to the other output port of the master cylinder 14, and the brake hydraulic control pipe 18 is used for the left front wheel that applies a braking force to the left front wheel 19FL. It is connected to the wheel cylinder 20FL. A right electromagnetic on-off valve 22FR is provided in the middle of the brake hydraulic control pipe 16 for the right front wheel, and a left electromagnetic on-off valve 22FL is provided in the middle of the brake hydraulic control pipe 18 for the left front wheel. The right solenoid on-off valve 22FR and the left solenoid on-off valve 22FL are both normally open solenoid valves that are open when not energized and are switched to the closed state when the operation of the brake pedal 12 by the driver is detected. is there.

  A right master pressure sensor 48FR for detecting the master cylinder pressure on the right front wheel side is provided in the middle of the brake hydraulic control pipe 16 for the right front wheel. A left master pressure sensor 48FL for measuring the master cylinder pressure on the left front wheel side is provided. In the working fluid pressure control device 10, when the brake pedal 12 is depressed by the driver, not only the depression operation amount is detected by the stroke sensor 46 but also the right master pressure sensor 48FR and the left master pressure sensor 48FL. The depressing operation force of the brake pedal 12 can also be obtained from the master cylinder pressure. As described above, it is preferable from the viewpoint of fail-safe that the master cylinder pressure is monitored by the two pressure sensors 48FR and 48FL on the assumption of the failure of the stroke sensor 46.

  On the other hand, one end of a hydraulic supply / discharge pipe 28 is connected to the reservoir tank 26, and a suction port of an oil pump 34 driven by a motor 32 is connected to the other end of the hydraulic supply / discharge pipe 28. . The discharge port of the oil pump 34 is connected to a high pressure pipe 30, and an accumulator 50 and a relief valve 53 are connected to the high pressure pipe 30. In the present embodiment, a reciprocating pump including two or more pistons (not shown) that are reciprocally moved by the motor 32 is employed as the oil pump 34. Further, as the accumulator 50, an accumulator 50 that converts the pressure energy of the brake oil into the pressure energy of an enclosed gas such as nitrogen is stored.

  The accumulator 50 stores brake oil whose pressure has been increased to about 16 to 18 MPa by the oil pump 34, for example. Further, the valve outlet of the relief valve 53 is connected to the hydraulic supply / discharge pipe 28. When the pressure of the brake oil in the accumulator 50 increases abnormally to about 25 MPa, for example, the relief valve 53 is opened and the high-pressure brake is opened. The oil is returned to the hydraulic supply / discharge pipe 28. Further, the high-pressure pipe 30 is provided with an accumulator pressure sensor 51 that detects the outlet pressure of the accumulator 50, that is, the pressure of the brake oil in the accumulator 50.

  The high pressure pipe 30 is connected to the right front wheel wheel cylinder 20FR, the left front wheel wheel cylinder 20FL, the right rear wheel wheel cylinder 20RR, and the left rear wheel wheel cylinder 20RL via the pressure increasing valves 40FR, 40FL, 40RR, 40RL. It is connected to the. Hereinafter, the wheel cylinders 20FR to 20RL will be collectively referred to as “wheel cylinders 20”, and the pressure increase valves 40FR to 40RL will be appropriately collectively referred to as “pressure increase valves 40”. Each of the pressure increasing valves 40 is a normally closed electromagnetic flow control valve (linear valve) that is closed when not energized and is used to increase the pressure of the wheel cylinder 20 as necessary. A disc brake unit (not shown) is provided for each wheel 19FR, 19FL, 19RR, 19RL of the vehicle, and each disc brake unit is controlled by pressing the brake pad against the disc by the action of the wheel cylinder 20. Generate power.

  The right front wheel wheel cylinder 20FR and the left front wheel wheel cylinder 20FL are connected to the hydraulic supply / discharge pipe 28 via pressure reducing valves 42FR or 42FL, respectively. The pressure reducing valves 42FR and 42FL are normally closed electromagnetic flow control valves (linear valves) used for pressure reduction of the wheel cylinders 20FR and 20FL as necessary. On the other hand, the wheel cylinder 20RR for the right rear wheel and the wheel cylinder 20RL for the left rear wheel are connected to the hydraulic supply / discharge pipe 28 via a pressure reducing valve 42RR or 42RL which is a normally open electromagnetic flow control valve. . Hereinafter, the pressure reducing valves 42FR to 42RL are collectively referred to as “pressure reducing valve 42” as appropriate.

  Further, a right front wheel wheel cylinder pressure sensor 44FR for detecting the pressure of brake oil in the corresponding wheel cylinder 20 is provided in the vicinity of the wheel cylinders 20FR to 20RL of the right front wheel 19FR, the left front wheel 19FL, the right rear wheel 19RR, and the left rear wheel 19RL. , A left front wheel wheel cylinder pressure sensor 44FL, a right rear wheel wheel cylinder pressure sensor 44RR, and a left rear wheel wheel cylinder pressure sensor 44RL are provided. Hereinafter, the wheel cylinder pressure sensor will be referred to as “WC pressure sensor” as appropriate, and four of WC pressure sensors 44FR to 44RL, or some of the four, will be collectively referred to as “WC pressure sensor 44”.

  A front wheel side communication pipe 60 for communicating the right front wheel WC pressure sensor 44FR and the left front wheel WC pressure sensor 44FL is provided, and a front wheel side communication valve 64 is provided in the middle of the front wheel side communication pipe 60. In addition, a rear wheel side communication pipe 62 that connects the right rear wheel WC pressure sensor 44RR and the left rear wheel WC pressure sensor 44RL is provided, and a rear wheel side communication valve 66 is provided in the middle of the rear wheel side communication pipe 62. ing. Each of the front wheel side communication valve 64 and the rear wheel side communication valve 66 is a normally closed solenoid valve that is in a closed state when not energized and communicates the front wheel side communication pipe 60 and the rear wheel side communication pipe 62 as necessary.

  The right electromagnetic on-off valve 22FR and the left electromagnetic on-off valve 22FL, the pressure increasing valves 40FR to 40RL, the pressure reducing valves 42FR to 42RL, the oil pump 34, the accumulator 50, the front wheel side communication valve 64, the rear wheel side communication valve 66, etc. A hydraulic actuator 80 of the pressure control device 10 is configured. The hydraulic actuator 80 is controlled by an electronic control unit (hereinafter referred to as “ECU”) 200. The ECU 200 includes a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for data storage and program execution, an input / output interface, a memory, and the like.

  The ECU 200 is electrically connected to the electromagnetic on-off valve 22, the stroke simulator on-off valve 23, the pressure increasing valve 40, the pressure reducing valve 42, the front wheel side communication valve 64, the rear wheel side communication valve 66, and the like. The electromagnetic on / off valve 22, the stroke simulator on / off valve 23, the pressure increasing valve 40, the pressure reducing valve 42, the front wheel side communication valve 64, and the rear wheel side communication valve 66 are configured by a valve control unit 201 (see FIG. 2) built in the ECU 200. ) Respectively.

  Further, the ECU 200 is given a signal indicating the brake oil pressure in the wheel cylinder 20 from the WC pressure sensor 44. Further, the ECU 200 is given a signal indicating the depression stroke of the brake pedal 12 from the stroke sensor 46, and is given a signal indicating the master cylinder pressure from the right master pressure sensor 48FR and the left master pressure sensor 48FL, and from the accumulator pressure sensor 51. A signal indicating the brake oil pressure in the accumulator 50 is provided.

  In the working fluid pressure control device 10 configured as described above, the ECU 200 calculates the target deceleration of the vehicle from the depression stroke of the brake pedal 12 and the master cylinder pressure, and each wheel 19 according to the calculated target deceleration. Target wheel cylinder pressure is required. Then, the pressure increasing valve 40 and the pressure reducing valve 42 are controlled by the valve control unit 201, the wheel cylinder pressure of each wheel 19 is set to the target wheel cylinder pressure, and a braking force is applied to each wheel 19 to achieve the target deceleration. The

  By the way, the pressure sensor used in the present embodiment is initially corrected in advance when the working fluid pressure control device 10 is manufactured. The initially corrected pressure sensor can measure the pressure relatively accurately near the initial corrected pressure, but if the pressure is measured away from the initial corrected pressure, an error is included.

  Therefore, in the present embodiment, the output characteristics of the pressure sensor are corrected at a predetermined frequency by the mutual correction control unit 202 (see FIG. 2). The mutual correction control unit 202 is constructed in the ECU 200 similarly to the valve control unit 201. The mutual correction control unit 202 acquires the pressure measured by the other pressure sensor in a state where the initial correction pressure of the certain pressure sensor acts on the other pressure sensor. This is performed between a plurality of pressure sensors that have been initially corrected under different initial correction pressures, and the output characteristics of each pressure sensor are corrected based on the output acquired from each pressure sensor (hereinafter referred to as appropriate). This is called “mutual correction”.) By this mutual correction, each error of the two pressure sensors can be reduced, and the difference between the measured values of the two pressure sensors can be reduced. As a result, when controlling the pressure of the working fluid, it is possible to suppress the influence of the error of the pressure sensor.

  FIG. 2 is a control block diagram relating to correction of output characteristics of the pressure sensor according to the first embodiment. A mutual correction control unit 202 serving as a correction unit for correcting the output characteristics of the pressure sensor includes a memory 204 for storing the output characteristics of the pressure sensor, and correction of the output characteristics at a predetermined frequency according to the number of times of braking. A braking number counter 206 for performing the operation is connected. The mutual correction control unit 202 is supplied with various signals from the master pressure sensor 48, the WC pressure sensor 44, the accumulator pressure sensor 51, and the stroke sensor 46.

  In the present embodiment, as the master pressure sensor 48, the WC pressure sensor 44, and the accumulator pressure sensor 51, for example, a semiconductor pressure sensor is used. These pressure sensors detect a pressure difference from the atmospheric pressure and output a voltage corresponding to the magnitude of the pressure difference. The output characteristic of the pressure sensor is ideally linear. That is, the output voltage increases in proportion to the increase in the acting pressure.

  FIG. 3 is a diagram illustrating an example of a combination of mutual corrections of the pressure sensor according to the first embodiment. In FIG. 3, between the two pressure sensors connected by the broken-line arrows, that is, between the left front wheel WC pressure sensor 44FL and the right front wheel WC pressure sensor 44FR, and between the left rear wheel WC pressure sensor 44RL and the right rear wheel WC. Mutual correction is performed with the pressure sensor 44RR. The initial correction pressures of the right front wheel WC pressure sensor 44FR and the left front wheel WC pressure sensor 44FL are set to different pressures, and the initial correction pressures of the right rear wheel WC pressure sensor 44RR and the left rear wheel WC pressure sensor 44RL are also set to different pressures. Is done. It is desirable that the initial correction pressure is selected so as to be included in the pressure range of the working fluid that normally acts on the wheel cylinder 20 during braking, that is, the normal range. This is to reduce the error of each pressure sensor in the normal range.

  In the present embodiment, the normal range is, for example, 0 to 3 MPa. Therefore, as shown in FIG. 3, the initial correction pressures of the WC pressure sensors 44FR, 44FL, 44RR, 44RL are, for example, 3 MPa, 0 MPa, 0 MPa, 3 MPa, respectively. It is said. Under these initial correction pressures, the WC pressure sensor 44 is subjected to initial correction and output characteristics are set in advance. These pressure values are all pressure differences from atmospheric pressure. However, a positive value is set when the pressure is greater than atmospheric pressure. The same applies to the following.

  FIG. 4 is a flowchart for explaining the procedure of mutual correction in the first embodiment. In the first embodiment, for example, the mutual correction is performed at a predetermined frequency at the time of braking, for example, once for every 10 to 100 times of braking. The processing shown in FIG. 4 is repeatedly executed at predetermined time intervals while the vehicle is traveling.

  The mutual correction control unit 202 of the ECU 200 first determines whether or not it is during braking (S10). This determination is performed by determining whether or not the brake pedal 12 is depressed from a signal sent from the stroke sensor 46, for example. When the mutual correction control unit 202 determines that it is not during braking (No in S10), the process ends, and after a predetermined time has elapsed, the process returns to the determination as to whether it is during braking (S10). If the mutual correction control unit 202 determines that braking is being performed (Yes in S10), the count number n of the brake count counter 206 is increased by one (S12), and whether the count number n has reached the predetermined brake count N or not. Is determined (S14). In the first embodiment, the predetermined braking number N is, for example, 10 times. When the mutual correction control unit 202 determines that the predetermined number of times of braking N has not been reached (No in S14), the process ends, and after a predetermined time elapses, the process returns to the determination of whether or not braking is being performed (S10).

  When the mutual correction control unit 202 determines that the current braking count n is equal to or greater than the predetermined braking count N (Yes in S14), the valve control unit 201 determines that the front wheel side communication valve 64 and the rear wheel side communication valve 66 are. Both are opened (S16). By opening the front wheel side communication valve 64, the same pressure acts on the left front wheel WC pressure sensor 44FL and the right front wheel WC pressure sensor 44FR, and the rear wheel side communication valve 66 is opened. As a result, equal pressure acts on the left rear wheel WC pressure sensor 44RL and the right rear wheel WC pressure sensor 44RR. It should be noted that these communication valves are not opened at each braking, but are opened when a predetermined number of times of braking N is reached. In a normal braking state where mutual correction is not performed, the four wheels 19 This is to independently control the braking force applied to each of the two.

  When the front wheel side communication valve 64 and the rear wheel side communication valve 66 are opened, the mutual correction control unit 202 performs a mutual correction process (S18). When the mutual correction process ends, the valve control unit 201 closes the front wheel side communication valve 64 and the rear wheel side communication valve 66 (S20). Then, the mutual correction control unit 202 resets the braking number counter (S22), and the process ends.

  With reference to FIGS. 5 to 7, the mutual correction process (S18) will be described in detail. 5 and 6 are graphs for explaining the principle of mutual correction in the present embodiment. In short, in the present embodiment, as for the output characteristics of the first pressure sensor, the output of the first pressure sensor is maintained without changing the measured value of the first pressure sensor at the initial correction pressure of the first pressure sensor. Correct the slope of the characteristic. On the other hand, with respect to the output characteristics of the second pressure sensor, the inclination of the output characteristics of the second pressure sensor is corrected without changing the measured value of the second pressure sensor at the initial correction pressure of the second pressure sensor. . Here, as an example, mutual correction of the left front wheel WC pressure sensor 44FL and the right front wheel WC pressure sensor 44FR will be described.

In FIG. 5, the vertical axis represents the output voltage V _FL of the left front wheel WC pressure sensor 44FL, and the horizontal axis represents the pressure P. The solid line indicates the output characteristic before correction, and the broken line indicates the output characteristic after correction. V _0FL is an output voltage at the initial correction pressure P _FL . In the present embodiment, the initial correction pressure _{P FL} is a 0 _MPa, left front wheel WC pressure sensors 44FL to _{V 0FL} becomes 0V is adjusted during initial correction.

To correct the output characteristics of the left front wheel WC pressure sensor 44FL, first initial correction pressure _{P FR} of the front right wheel WC pressure sensor 44FR to measure the pressure by the left front wheel WC pressure sensor 44FL while acting. In the present embodiment, the initial correction pressure _{P FR} of the front right wheel WC pressure sensors 44FR as described above is a 3 MPa. When performing the mutual correction process, the left front wheel WC pressure sensor 44FL and the right front wheel WC pressure sensor 44FR are communicated by the front wheel side communication valve 64 so that equal pressure is applied to both. Thus, whether pressure P _FR to the left front wheel WC pressure sensor 44FL is acting, is confirmed by measuring the pressure by a right front wheel WC pressure sensor 44FR. Right front wheel WC pressure sensor 44FR, since it is possible to measure the pressure in the vicinity of its initial corrected pressure P _FR with high accuracy, mutual whether the pressure P _FR to the left front wheel WC pressure sensor 44FL acts The correction control unit 202 can make the determination.

As shown in FIG. 5, the output voltage _{V FL} when the pressure _{P FR} to the left front wheel WC pressure sensor 44FL is acting is assumed to be _{V 1.} In this case, the value measured by the left front wheel WC pressure sensor 44FL, the P ₁ derived from the output characteristic before correction. The difference between the P ₁ and P _FR can be considered to be errors. Therefore, the output characteristic of the left front wheel WC pressure sensor 44FL is corrected so that the pressure is measured to be P _FR when the output voltage V _FL is V ₁ .

In this case, from (1) and that the front left wheel WC pressure sensor 44FL can be measured by its initial corrected pressure P _FL at high accuracy, (2) the ideal output characteristic that a straight line, two points, The output characteristic of the left front wheel WC pressure sensor 44FL is corrected to a straight line passing through two points (P _FR , V ₁ ) and (P _FL , V _0FL ). That is, it is common that the output characteristic before correction and the output characteristic after correction are straight lines passing through the point (P _FL , V _0FL ), while the output characteristic after correction is the point (P _FR , V ₁ ). The slope of the straight line is changed to pass.

Further, as shown in FIG. 6, the correction of the output characteristic of the right front wheel WC pressure sensor 44FR is performed in the same manner. The vertical axis represents the output voltage _{V FR} of the right front wheel WC pressure sensor 44FR, the horizontal axis represents the pressure P. The solid line indicates the output characteristic before correction, and the broken line indicates the output characteristic after correction. V _0FR is an output voltage at the initial correction pressure P _FR . In the present embodiment, the initial correction pressure _{P FR} of the front right wheel WC pressure sensor 44FR is different 3MPa the initial correction pressure _{P FL} of the front left wheel WC pressure sensor 44FL.

To correct the output characteristics of the right front wheel WC pressure sensor 44FR measures pressure by the right front wheel WC pressure sensor 44FR in a state where initial correction pressure _{P FL} of the front left wheel WC pressure sensor 44FL acts. In the present embodiment, after confirming by the left front wheel WC pressure sensor 44FL that the state of 0MPa the initial corrected pressure _{P FL} of the front left wheel WC pressure sensor 44FL, measuring the pressure by a right front wheel WC pressure sensor 44FR. Output voltage V _FR of the right front wheel WC pressure sensor 44FR that time is V _2, the pressure derived from the output characteristic before correction is to become P _2. The difference between the P ₂ and P _FL can be considered to be errors. Therefore, the output characteristic of the right front wheel WC pressure sensor _44FR is corrected to a straight line passing through two points (P _FL , V ₂ ) and (P _FR , V _0FR ).

  FIG. 7 is a flowchart for explaining the mutual correction process (S18) of the left front wheel WC pressure sensor 44FL and the right front wheel WC pressure sensor 44FR in the first embodiment. As shown in FIG. 4, after the valve control unit 201 opens both the front wheel side communication valve 64 and the rear wheel side communication valve 66 (S16), the mutual correction process (S18) shown in FIG. 7 is performed. .

Mutual correction control unit 202 determines the pressure acting on the right front wheel WC pressure sensor 44FR is whether the initial correction pressure _{P FL} of the front left wheel WC pressure sensor 44FL (S30). This determination is made based on the measured value of the left front wheel WC pressure sensor 44FL as described above. When the pressure acting on the right front wheel WC pressure sensor 44FR mutual correction control unit 202 when an early corrected pressure _{P FL} of the front left wheel WC pressure sensor 44FL is determined (Yes in S30), as described with reference to FIG. 5 The mutual correction control unit 202 corrects the output characteristics of the right front wheel WC pressure sensor 44FR (S34). The corrected output characteristic is stored in the memory 204.

On the other hand, when the right front wheel WC pressure when the sensor 44FR pressure acting on is not the initial correction pressure _{P FL} of the front left wheel WC pressure sensor 44FL mutual correction control unit 202 to determine (No in S30), the mutual correction control unit 202, S10 In the same manner as described above, it is determined based on the signal from the stroke sensor 46 whether or not braking is being performed (S32). When mutual correction control unit 202 determines that a braking (Yes in S32), the reference pressure acting on the right front wheel WC pressure sensor 44FR is whether the initial correction pressure _{P FL} of the front left wheel WC pressure sensor 44FL Perform again (S30). If the mutual correction control unit 202 determines that it is not during braking (No in S32), the output characteristic is not corrected and the valve control unit 201 closes the front wheel side communication valve 64 and the rear wheel side communication valve 66 ( (S20 in FIG. 4).

When the mutual correction control unit 202 corrects the output characteristics of the right front wheel WC pressure sensor 44FR (S34), the mutual correction control unit 202 continues to apply the pressure acting on the left front wheel WC pressure sensor 44FL to the initial value of the right front wheel WC pressure sensor 44FR. It is determined whether or not the correction pressure is P _FR (S36). This determination is made based on the measured value of the right front wheel WC pressure sensor 44FR as described above. When mutual correction control unit 202 when the pressure acting on the left front wheel WC pressure sensor 44FL is at the initial corrected pressure _{P FR} of the front right wheel WC pressure sensor 44FR is determined (Yes in S36), as described with reference to FIG. 5 The mutual correction control unit 202 corrects the output characteristics of the left front wheel WC pressure sensor 44FL (S40). The corrected output characteristic is stored in the memory 204.

On the other hand, the mutual correction control unit 202 when the pressure acting on the left front wheel WC pressure sensor 44FL is not the initial correction pressure _{P FR} of the front right wheel WC pressure sensor 44FR is determined (No in S36), the mutual correction control unit 202, S10 In the same manner as described above, it is determined based on the signal from the stroke sensor 46 whether or not it is during braking (S38). When mutual correction control unit 202 determines that a braking (Yes in S38), the determination pressure acting on the left front wheel WC pressure sensor 44FL of whether the initial correction pressure _{P FR} of the front right wheel WC pressure sensor 44FR Perform again (S36). If the mutual correction control unit 202 determines that it is not during braking (No in S38), the valve control unit 201 does not correct the output characteristics of the left front wheel WC pressure sensor 44FL and the valve control unit 201 performs the front wheel side communication valve 64 and the rear wheel side communication valve. 66 is closed (S20 in FIG. 4).

In the first embodiment, the mutual correction is performed at the time of braking, so that the pressure of the working fluid gradually increases during the mutual correction process. Therefore, as it is determined whether or not the order that the pressure from the smaller of the initial correction pressure P _FL and the right front wheel WC pressure sensor 44FR initial correction pressure P _FR of the front left wheel WC pressure sensor 44FL acts Yes.

  The mutual correction of the left rear wheel WC pressure sensor 44RL and the right rear wheel WC pressure sensor 44RR communicated by the rear wheel side communication valve 66 is also the mutual correction of the left front wheel WC pressure sensor 44FL and the right front wheel WC pressure sensor 44FR. It is done in the same way in parallel.

  According to the first embodiment, the front wheel side communication valve 64 and the rear wheel side communication valve 66 communicate the two WC pressure sensors 44 on the front wheel side and the rear wheel side with a predetermined frequency during braking so that the output characteristics are mutually corrected. Is done. Therefore, it becomes possible to improve the measurement accuracy of the pressure sensor at a relatively high frequency during traveling. Further, since the front wheel side communication valve 64 and the rear wheel side communication valve 66 are provided exclusively to apply equal pressure to both of the two pressure sensors, it is possible to reliably apply equal pressure to the two pressure sensors. Can do.

  In the first embodiment, the mutual correction targets are the WC pressure sensors 44 on the front wheel side or the WC pressure sensors 44 on the rear wheel side, so that the WC pressures corresponding to the left and right wheels of the front wheel or the rear wheel are respectively. The difference in error of the sensor 44 can be reduced. Therefore, the straight running stability of the vehicle during braking can be improved. Further, since mutual correction is performed for each of the two WC pressure sensors 44, the number of pressure sensors that are mutual correction counterparts is as small as one. Therefore, mutual correction can be performed quickly.

  Furthermore, in the first embodiment, since the mutual correction is performed at a relatively high frequency, for example, once every 10 brakings, the accuracy of the WC pressure sensor 44 can be maintained high. Also, even when the mutual correction is incomplete due to the short braking time, the mutual correction is performed at a relatively high frequency, which is preferable because the opportunity for the next mutual correction can be reached early. . If the mutual correction is incomplete, the mutual correction may be performed again at the next braking.

  Further, according to the first embodiment, the initial correction pressure of the WC pressure sensor 44 is included in the pressure range of the working fluid that normally acts on the wheel cylinder 20 during braking. Therefore, since the error of the WC pressure sensor 44 in the pressure range that normally acts on the wheel cylinder during braking can be reduced, the control performance of the braking force is improved.

  In the first embodiment, the normal range is 0 to 3 MPa, whereas the initial correction pressure of the WC pressure sensor 44 is set to 0 MPa or 3 MPa, which is the most separated value in the normal range. . In the mutual correction in the present embodiment, the slope of the straight line of the output characteristic is changed. Therefore, when the end value of the pressure range of the working fluid during braking is set as the initial correction pressure in this way, the measurement accuracy of the pressure sensor is increased. It can be improved further.

  The initial correction pressure of the WC pressure sensor 44 illustrated in the first embodiment is merely an example and is not limited thereto. By setting the initial correction pressure in accordance with the pressure range to be used, it is possible to improve the accuracy of the pressure sensor in that pressure range.

  For example, in a hybrid vehicle or an electric vehicle that performs cooperative control using a hydraulic brake and a regenerative brake in combination with a motor, the hydraulic pressure of the axle brake to which the regenerative brake motor is attached is small. Therefore, for example, when a motor is mounted on the front wheel side, the range of the brake oil pressure on the front wheel side is set low in, for example, 0 to 1 MPa and the normal range 0 to 3 MPa, and the brake oil pressure on the rear wheel side is set to, for example, 0 to 3 MPa. And can be set higher. Accordingly, as shown in FIG. 8, the initial correction pressures of the WC pressure sensors 44FR, 44FL, 44RR, and 44RL are set to the initial correction values of the right front wheel WC pressure sensor 44FR, for example, 1 MPa, 0 MPa, 0 MPa, and 3 MPa, respectively. The pressure may be set to 1 MPa. This is preferable because the mutual correction of the pressure sensor is performed in accordance with the hydraulic range where the frequency of use is high, and the accuracy of the pressure sensor can be improved in that range.

  Next, a second embodiment of the present invention will be described. In the first embodiment, the mutual correction is performed at the time of braking. However, in the second embodiment, the mutual correction is performed outside the braking time when the braking force is not applied to the wheel 19 by the wheel cylinder 20. In the following description regarding the second embodiment, the description of the same contents as those of the first embodiment will be omitted as appropriate.

  Outside braking, for example, after the ignition key is turned off and the driver leaves the vehicle, before the driver gets on the vehicle and starts the vehicle drive source, or when the vehicle is shipped from the factory . When it is not necessary to generate a braking force by the wheel cylinder 20 as in these cases, a plurality of pressure sensors are opened and closed by opening and closing the valves such as the electromagnetic on-off valve 22, the pressure increasing valve 40, and the pressure reducing valve 42 of the hydraulic actuator 80. Mutual correction is performed by communicating. The pressure acting on the pressure sensor is adjusted by the accumulator 50, for example.

  The pressure control system of the working fluid pressure control apparatus 10 according to the second embodiment is the same as that shown in FIG. However, in the second embodiment, since mutual correction is performed outside the time of braking, it is not necessary to provide the front wheel side communication pipe 60 and the rear wheel side communication pipe 62 which are particularly provided for communicating the pressure sensor. Therefore, it is preferable in that the hydraulic actuator 80 used for brake control can be used as it is for mutual correction during traveling.

  A control block diagram according to the second embodiment is also the same as that shown in FIG. However, since the mutual correction is performed outside the time of braking, the braking frequency counter 206 is not necessary. The combination of pressure sensors that are mutually corrected can be the same as that shown in FIG. 3, for example.

  FIG. 9 is a flowchart for explaining the procedure of mutual correction in the second embodiment. As an example, mutual correction of the left front wheel WC pressure sensor 44FL and the right front wheel WC pressure sensor 44FR will be described. The processing shown in FIG. 9 is executed at a predetermined timing outside the time of braking, for example, after the ignition key is turned off and the driver leaves the vehicle.

First, the valve control unit 201, pressure increasing valve 40FR with the solenoid valve 22 closed, by the 40FL opened, the left front wheel WC pressure sensor 44FL initial corrected pressure _{P FL} of the left front wheel WC pressure sensor 44FL And it is made to act on the right front wheel WC pressure sensor 44FR (S50). At this time, to make sure that the initial corrected pressure _{P FL} of the front left wheel WC pressure sensor 44FL front right wheel WC pressure sensor 44FR by measuring the pressure is acting by the left front wheel WC pressure sensor 44FL. Then, mutual correction control unit 202, in a state where the initial correction pressure _{P FL} of the front left wheel WC pressure sensor 44FL front right wheel WC pressure sensor 44FR is acting, as in the first embodiment the front right wheel WC pressure sensor 44FR Are corrected (S52).

Then, the valve control unit 201 exerts an initial corrected pressure _{P FR} of the front right wheel WC pressure sensor 44FR to the left front wheel WC pressure sensors 44FL and the right front wheel WC pressure sensor 44FR (S54). Mutual correction control unit 202 confirms that the initial correction pressure _{P FR} of the front right wheel WC pressure sensor 44FR to the left front wheel WC pressure sensor 44FL is acting, as in the first embodiment the left front wheel WC pressure sensor 44FL The output characteristic is corrected and the process ends (S56).

  In the second embodiment, since mutual correction is performed outside the time of braking, unlike the first embodiment, mutual correction can be performed regardless of the braking operation by the driver. Therefore, it is preferable in that mutual correction can be performed more surely over time. Further, in the present embodiment, since the working fluid pressure control device 10 can use a valve or the like originally provided in the hydraulic actuator 80 to supply the working fluid, it is not necessary to provide a communication valve for mutual correction. This is also preferable.

  FIGS. 10-13 is a figure which shows the other combination of the pressure sensor at the time of performing the mutual correction in 2nd Embodiment. Similar to FIG. 3, mutual correction is performed between the pressure sensors connected by broken-line arrows.

  As shown in FIG. 10, mutual correction may be performed between the wheels 19 positioned on the diagonal of the vehicle. That is, mutual correction may be performed between the left front wheel WC pressure sensor 44FL and the right rear wheel WC pressure sensor 44RR, and between the left rear wheel WC pressure sensor 44RL and the right front wheel WC pressure sensor 44FR. In this case, initial correction pressures of the WC pressure sensors 44FR, 44FL, 44RR, and 44RL can be set to 3 MPa, 0 MPa, 3 MPa, and 0 MPa, respectively. In this way, even when the diagonal two-wheel braking state occurs when the system is abnormal, the pressure sensor error can be reduced and the braking force control performance can be improved.

  Further, as shown in FIG. 11, mutual correction may be performed between the left front wheel WC pressure sensor 44FL and each of the other three WC pressure sensors 44FR, 44RL, and 44RR. In this case, initial correction pressures of the WC pressure sensors 44FR, 44FL, 44RR, and 44RL can be set to, for example, 0 MPa, 3 MPa, 0 MPa, and 0 MPa, respectively. In this way, the initial correction pressures of the three other WC pressure sensors 44FR, 44RL, and 44RR other than the left front wheel WC pressure sensor 44FL can be set to atmospheric pressure (0 MPa) as in the conventional case. Since pressure sensors that have been initially corrected under atmospheric pressure are readily available on the market, the cost of the pressure sensor is low. As a result, the cost of the working fluid pressure control device 10 can be reduced.

  Furthermore, as shown in FIG. 12, mutual correction can be performed between the WC pressure sensor 44 and the master pressure sensor 48. For example, mutual correction may be performed between the left front wheel WC pressure sensor 44FL and the left master pressure sensor 48FL, and between the right front wheel WC pressure sensor 44FR and the right master pressure sensor 48FR.

  Mutual correction between the left front wheel WC pressure sensor 44FL and the left master pressure sensor 48FL is performed when the driver depresses the brake pedal 12 before starting the vehicle drive source with the left electromagnetic on-off valve 22FL opened, for example. . When the driver depresses the brake pedal 12, the pressure acting on both the left front wheel WC pressure sensor 44FL and the left master pressure sensor 48FL can be changed, so that the initial correction pressure of each sensor is applied to both sensors. Can do. In this case, the initial correction pressures of the left front wheel WC pressure sensor 44FL and the left master pressure sensor 48FL can be set to, for example, 0 MPa and 2 MPa, respectively. This initial correction pressure is preferably set within a range of pressure that can be realized by depressing the brake pedal 12 by the driver. Mutual correction between the right front wheel WC pressure sensor 44FR and the right master pressure sensor 48FR can be performed in the same manner.

  As shown in FIG. 12, in combination with the mutual correction between the WC pressure sensor 44 and the master pressure sensor 48, between the left front wheel WC pressure sensor 44FL and the right front wheel WC pressure sensor 44FR, and the left rear Mutual correction may also be performed between the wheel WC pressure sensor 44RL and the right rear wheel WC pressure sensor 44RR.

  Further, as shown in FIG. 13, the initial correction pressure may be set beyond the normal range. In FIG. 13, the initial correction pressures of the left front wheel WC pressure sensor 44FL, the left master pressure sensor 48FL, the right front wheel WC pressure sensor 44FR, and the right master pressure sensor 48FR are set to, for example, 0 MPa, 12 MPa, 4 MPa, and 0 MPa, respectively. ing. Mutual correction in this case is performed, for example, by applying a pressure from the normal range to the outside of the normal range on each pressure sensor when the vehicle is shipped from the factory. It is preferable to perform the mutual correction at the time of shipment from the factory because the control for the mutual correction can be simplified and the cost can be reduced.

  Next, a third embodiment of the present invention will be described. In the first and second embodiments described above, mutual correction is performed between two pressure sensors. In the third embodiment, mutual correction is performed between a larger number of pressure sensors. In this case, as in the second embodiment, it is preferable to perform mutual correction outside of braking. This is because an equal pressure is simultaneously applied to a large number of pressure sensors in order to perform mutual correction. In the following description regarding the third embodiment, description of the same contents as those of the second embodiment will be omitted as appropriate.

  FIG. 14 is a diagram illustrating a combination of pressure sensors in mutual correction in the third embodiment. In the present embodiment, as shown in FIG. 14, for example, the output characteristic of the left front wheel WC pressure sensor 44FL is corrected by adjusting the left front wheel WC pressure at the initial correction pressure of each of the other three WC pressure sensors 44FR, 44RL, 44RR. This is performed based on the output voltage of the sensor 44FL. Correction of output characteristics of the other three WC pressure sensors 44FR, 44RL, 44RR is performed in the same manner. That is, the correction is performed based on the output voltage of the correction target WC pressure sensor 44 at the initial correction pressure of each of the remaining three WC pressure sensors 44 other than the correction target WC pressure sensor 44. In the present embodiment, the initial correction pressures of the WC pressure sensors 44FR, 44FL, 44RR, and 44RL can be set to, for example, 1 MPa, 0 MPa, 3 MPa, and 2 MPa, respectively.

  FIG. 15 is a flowchart for explaining the procedure of mutual correction in the third embodiment. The process shown in FIG. 15 is executed at a predetermined timing outside braking, for example, after the ignition key is turned off and the driver leaves the vehicle.

First, by the valve controller 201 to the pressure increasing valve 40 in the open state with the solenoid valve 22 closed, the action of the initial correction pressure P _FL of the front left wheel WC pressure sensors 44FL to each WC pressure sensor 44 ( S60). At this time, since an equal pressure is applied to each WC pressure sensor 44, the pressure is measured by the left front wheel WC pressure sensor 44FL, and the initial correction pressure P _{FL of the} left front wheel WC pressure sensor 44FL is measured by the other WC pressure sensors 44 as well. Make sure that is working. Then, the mutual correction control unit 202 causes the three WC pressure sensors 44FR, 44RL, 44RR other than the left front wheel WC pressure sensor 44FL to measure the pressure, and stores the output voltage at that time in the memory 204 (S62).

Then, the valve control unit 201 exerts an initial corrected pressure _{P FR} of the front right wheel WC pressure sensor 44FR to each WC pressure sensor 44 (S64). In this state, the mutual correction control unit 202 causes the three WC pressure sensors 44FL, 44RL, 44RR other than the right front wheel WC pressure sensor 44FR to measure the pressure, and stores the output voltage at that time in the memory 204 (S66). ).

Similarly, the valve control unit 201, by the action of the initial correction pressure _{P RL} of the left rear wheel WC pressure sensors 44RL to each WC pressure sensor 44 (S68), mutual correction control unit 202, the other three WC pressure sensor 44FL , 44FR, 44RR are caused to measure pressure (S70). Furthermore, the valve control unit 201, by the action of the initial correction pressure _{P RR} of the right rear wheel WC pressure sensor 44RR to each WC pressure sensor 44 (S72), mutual correction control unit 202, the other three WC pressure sensor 44FL, The pressure is measured by 44FR and 44RL (S74). The mutual correction control unit 202 stores the output voltage at the time of measurement by each WC pressure sensor 44 so far in the memory 204 each time.

Thereafter, the mutual correction control unit 202 corrects the output characteristics of each WC pressure sensor 44 (S76), and the process ends. Here, as an example, correction of output characteristics of the left front wheel WC pressure sensor 44FL will be described with reference to FIG. FIG. 16 is a graph for explaining the principle of correction of output characteristics in the third embodiment. In FIG. 16, the vertical axis represents the output voltage V _FL of the left front wheel WC pressure sensor 44FL, and the horizontal axis represents the pressure P. The solid line indicates the output characteristic before correction, and the broken line indicates the output characteristic after correction. V _0FL is an output voltage at the initial correction pressure P _FL . In the present embodiment, the initial correction pressure _{P FL} is a _{0MPa, V 0FL} the left front wheel WC pressure sensor 44FL such that 0V is adjusted during initial correction.

In FIG. 16, the output voltages of the left front wheel WC pressure sensor 44FL at the initial correction pressures P _FR , P _RL , P _RR of the other three WC pressure sensors 44FR, 44RL, 44RR are indicated by triangles. Output voltage when the pressure _{P FR} is Va, the output voltage when the pressure _{P RL} is Vb, the output voltage when the pressure _{P RR} is assumed to be Vc.

In this case, the corrected output characteristic is a straight line passing through the point (P _FL , V _0FL ) as in the output characteristic before correction. This is (1) and it is the front left wheel WC pressure sensor 44FL can be measured by its initial corrected pressure P _FL at high accuracy, by (2) the ideal output characteristic that a straight line, two points. The slope of the output characteristic is determined by, for example, a method such as a least square method in consideration of the three points (P _FR , Va), (P _RL , Vb), and (P _RR , Vc) obtained by measurement. I can decide. Correction of the output characteristics of the other WC pressure sensors 44 is performed in the same manner. Thus, in the present embodiment, the slope of the output characteristic of any one of the integrated pressure sensors is changed while not changing the measured value of the any one integrated pressure sensor at the initial correction pressure of any of the integrated pressure sensors. to correct.

  In the third embodiment, the output characteristics are corrected using a larger number of pressure sensors than in the first and second embodiments, so that the accuracy of the sensor can be further improved. In the third embodiment, for example, it is preferable in that the output characteristic can be corrected even when one pressure sensor fails.

  In the present embodiment, as shown in FIG. 14, the initial correction pressures of the WC pressure sensors 44FR, 44FL, 44RR, and 44RL can be set to 1 MPa, 0 MPa, 3 MPa, and 2 MPa, respectively. Setting the initial correction pressure in this manner is effective when the hydraulic pressure distribution on the front side may be smaller than that on the rear side. It should be noted that the initial correction pressure may be set as appropriate from various viewpoints such as whether or not cooperative control is performed using both a hydraulic brake and a regenerative brake by a motor, or weight distribution before and after the vehicle.

  Further, it is preferable that the difference between the initial correction pressure on the front wheel side and the initial correction pressure on the rear wheel side and the difference between the initial correction pressure on the left wheel side and the initial correction pressure on the right wheel side are smaller. This is because the smaller the difference, the more stable the behavior of the vehicle by suppressing the pitching and yawing even when the error of the pressure sensor increases again as time elapses after correction.

  A modification of the third embodiment will be described with reference to FIG. As shown in FIG. 17, an accumulator pressure sensor 51 may be further added to correct the output characteristics of each pressure sensor. In this case, the initial correction pressure of the accumulator pressure sensor 51 can be set to a value included in the operating pressure range of the accumulator 50, and can be set to 16 MPa, for example. Then, since the initial correction pressure of the accumulator pressure sensor 51 becomes a value away from the normal range of each WC pressure sensor 44, the accuracy of the WC pressure sensor 44 can be improved even in a pressure range away from the normal range. As a result, it is possible to appropriately control the behavior of the vehicle even when the wheel is locked, for example, during ABS operation.

  In any of the first to third embodiments, the initial correction pressure of at least one pressure sensor is set to atmospheric pressure (0 MPa), but the present invention is not limited to this. An appropriate value included in the normal range may be set, or a value not included in the normal range may be used. For example, when the initial correction pressure is set to a value in the vicinity of the middle of the normal range, the error at the other end of the normal range can be made smaller than when the value at one end of the normal range is set as the initial correction pressure. For example, when the normal range is 0 to 3 MPa, the case where the initial correction pressure is set to 1.5 MPa in the middle of the normal range and the case where the initial correction pressure is set to 0 MPa which is one end of the normal range are compared. In this case, the error in measuring the pressure near 3 MPa, which is the other end of the normal range, is smaller when the initial correction pressure is 1.5 MPa.

  In particular, for the accumulator pressure sensor 51, the operating region is separated from the atmospheric pressure, for example, 16 to 18 MPa. Therefore, it is preferable from the viewpoint of reducing the error to perform the initial correction at a value closer to the operating region such as 17 MPa, which is an intermediate value of the operating region, than to perform the initial correction at atmospheric pressure as in the past.

1 is a system diagram showing a pressure control system of a working fluid pressure control device according to a first embodiment of the present invention. It is a control block diagram regarding correction | amendment of the output characteristic of the pressure sensor which concerns on 1st Embodiment. It is a figure which shows an example of the combination of the mutual correction of the pressure sensor in 1st Embodiment. It is a flowchart for demonstrating the procedure of the mutual correction | amendment in 1st Embodiment. It is a graph for demonstrating the principle of the mutual correction | amendment in 1st Embodiment. It is a graph for demonstrating the principle of the mutual correction | amendment in 1st Embodiment. It is a flowchart for demonstrating the mutual correction process in 1st Embodiment. It is a figure which shows another example of the combination of the mutual correction of the pressure sensor in 1st Embodiment. It is a flowchart for demonstrating the procedure of the mutual correction | amendment in 2nd Embodiment. It is a figure which shows the other combination of the mutual correction | amendment of the pressure sensor in 2nd Embodiment. It is a figure which shows the other combination of the mutual correction | amendment of the pressure sensor in 2nd Embodiment. It is a figure which shows the other combination of the mutual correction | amendment of the pressure sensor in 2nd Embodiment. It is a figure which shows the other combination of the mutual correction | amendment of the pressure sensor in 2nd Embodiment. It is a figure which shows the combination of the pressure sensor in the mutual correction in 3rd Embodiment. It is a flowchart for demonstrating the procedure of the mutual correction | amendment in 3rd Embodiment. It is a graph for demonstrating the principle of the correction | amendment of the output characteristic in 3rd Embodiment. It is a figure which shows the other combination of the mutual correction | amendment of the pressure sensor in 3rd Embodiment.

Explanation of symbols

  10 working fluid pressure control device, 19 wheel, 20 wheel cylinder, 40 pressure increasing valve, 42 pressure reducing valve, 44 WC pressure sensor, 48 master pressure sensor, 51 accumulator pressure sensor, 60 front wheel side communication pipe, 62 rear wheel side communication pipe, 64 front wheel side communication valve, 66 rear wheel side communication valve, 80 hydraulic actuator, 200 ECU, 201 valve control unit, 202 mutual correction control unit.

Claims (8)

A working fluid pressure control device for controlling the pressure of a working fluid supplied to each of a plurality of objects,
A first pressure sensor whose output characteristic is set under a first initial correction pressure and which measures the pressure of the working fluid supplied to the first object;
A second pressure sensor for measuring the pressure of the working fluid supplied to the second object, the output characteristic of which is set under a second initial correction pressure different from the first initial correction pressure;
Correcting output characteristics of the first pressure sensor based on an output of the first pressure sensor when the second initial correction pressure acts on both the first and second pressure sensors; Correction means for correcting an output characteristic of the second pressure sensor based on an output of the second pressure sensor when the first initial correction pressure acts on both the first and second pressure sensors;
A working fluid pressure control device comprising:   A first flow path connecting the working fluid source and the first object and having the first pressure sensor in the middle so that equal pressure acts on both the first and second pressure sensors; The working fluid according to claim 1, further comprising communication means capable of communicating with a second flow path connecting the fluid source and the second object and having the second pressure sensor in the middle. Pressure control device. The first object is a first wheel cylinder for applying a braking force to a first wheel provided in a vehicle,
The second object is a second wheel cylinder for applying a braking force to a second wheel provided in the vehicle,
When the braking force is applied to each of the first and second wheels by the first and second wheel cylinders, the communication means is controlled to both the first and second pressure sensors. The working fluid pressure control device according to claim 2, further comprising a flow path control unit that communicates the flow path of the working fluid so that equal pressure acts. The first object is a first wheel cylinder for applying a braking force to a first wheel provided in a vehicle,
The second object is a second wheel cylinder for applying a braking force to a second wheel provided in the vehicle,
An equal pressure is applied to both the first and second pressure sensors when no braking force is applied to each of the first and second wheels by the first and second wheel cylinders. The working fluid pressure control device according to claim 1, further comprising a flow path control unit that communicates the flow path of the working fluid. A third pressure sensor for measuring the pressure of the working fluid supplied to the third object, the output characteristic of which is set under a third initial correction pressure different from any of the first and second initial correction pressures; ,
A fourth pressure sensor for measuring the pressure of the working fluid supplied to the fourth object and having an output characteristic set under a fourth initial correction pressure different from any of the first to third initial correction pressures; Further comprising
When the second initial correction pressure acts on both the first and second pressure sensors, the correction means applies the third initial correction pressure to both the first and third pressure sensors. And the first pressure sensor based on the output of the first pressure sensor when the fourth initial correction pressure acts on both the first and fourth pressure sensors. The working fluid pressure control device according to claim 4, wherein an output characteristic of the hydraulic fluid is corrected.   The first initial correction pressure is included in a pressure range of a working fluid that normally acts on the first wheel cylinder during braking, and the second initial correction pressure is the second wheel cylinder during braking. The working fluid pressure control device according to claim 3, wherein the working fluid pressure control device is included in a pressure range of the working fluid that normally acts on the fluid.   The first wheel and the second wheel are both front wheels or rear wheels, one of which is a wheel on the right side of the vehicle and the other is a wheel on the left side of the vehicle. The working fluid pressure control device according to any one of the above. Setting the output characteristics of the first pressure sensor under a first initial correction pressure;
Setting an output characteristic of the second pressure sensor under a second initial correction pressure different from the first initial correction pressure;
Correcting the output characteristics of the first pressure sensor based on the output of the first pressure sensor when the second initial correction pressure acts on both the first and second pressure sensors;
The output characteristic of the second pressure sensor is corrected based on the output of the second pressure sensor when the first initial correction pressure acts on both the first and second pressure sensors. The pressure sensor output characteristic correction method.

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