JPH0995229A - Brake fluid pressure control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate the shift of the operation amount of a solenoid valve and carry out a precise ABS control by that PWM control means in an actuator control means sets the duty ratio of PWM control in response to the ratio between a coil current detection value when an on duty ratio is a specific % and a standard current value. SOLUTION: An actuator control means 20 is provided with PWM control means 22aFL-22aR, 22bFL-2bR, 22cFL-22cR for PWM controlling the control signals of actuators 6FR, 6FL, 6R for controlling the current value to solenoid valves 8, 9 at the time of brake fluid pressure control and the coil current detection means DIC of the solenoid valves 8, 9. PWM control means sets the duty ratio of PWM control in response to the ratio between the coil current detection value when an on duty ratio is 100% and a standard current value set in advance. Consequently, the change of a magnetized current by the temperature change of coil of solenoid valve and the change of an electric source voltage is compensated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-brake lock system (hereinafter, referred to as "A") for controlling a hydraulic pressure acting on a braking cylinder of each wheel to an optimum state to prevent wheel locking.
(Referred to as BS) or a traction control device, etc., and particularly to a control result due to a change in coil current caused by a change in coil temperature of a solenoid valve (heat generation by coil current or environmental temperature). The present invention relates to a brake fluid pressure control device that can suppress the fluctuation of

[0002]

2. Description of the Related Art Among such brake fluid pressure control devices, an AB for preventing wheel lock during braking of a vehicle
In general, S is a target that detects a negative acceleration of the number of rotations of a wheel to be controlled, and the absolute value of the negative acceleration satisfies a reference slip ratio that is effective for securing a steering effect and a braking distance. If it is greater than the absolute value of the negative acceleration,
If the absolute value of the negative acceleration of the wheel rotational speed becomes smaller than the target absolute value of the negative acceleration due to this pressure reduction, the hydraulic pressure to the braking cylinder is reduced again. By increasing the pressure and automatically performing a so-called pumping brake operation, the braking force is adjusted and controlled so that the slip ratio of the wheel to be controlled is maintained below the reference slip ratio.

The pressure increasing control of the working fluid during the ABS control repeats the pressure increasing limited every predetermined time,
Macroscopically, the hydraulic pressure of the braking cylinder of each wheel is relatively moderately increased (hereinafter also referred to as “slowly increased pressure”). In addition, recently, even in the hydraulic pressure depressurization adjustment control during the ABS control, the limited depressurization is repeated every predetermined time,
There is also a system in which the hydraulic pressure of the braking cylinder of the wheel is reduced relatively gently (hereinafter, also referred to as a gentle pressure reduction).

When the working fluid pressure (hereinafter also referred to as wheel cylinder pressure) of the braking cylinder is gradually increased or decreased, the
In order to repeat the limited pressure increase / decrease every predetermined time, a solenoid valve 8 (in this case, an inflow solenoid valve) as shown in FIG. 18, for example, is used. Discharge hole 5 of this solenoid valve 8
1 is connected to the wheel cylinder side (not shown), and the inflow hole 53 is connected to the master cylinder side (not shown).

A front end (lower end in FIG. 18) of a needle 55 is opposed to a valve seat surface 54 formed between the inflow hole 53 and the discharge hole 51, and a rear end of this needle 55 (FIG. 18). An armature 56 is formed on the upper end of the armature 56, and a coil 57 is arranged on the outer circumference of the armature 56.

Further, a return spring 58 is interposed between the needle 55 and the valve seat surface 54, and the needle 55 is
Is urged in a direction away from the valve seat surface 54. Also,
A throttle 52 is formed between the valve seat surface 54 and the inflow hole 53. Therefore, when the coil 57 is not energized, the needle 55 moves the valve seat surface 5 by the urging force of the return spring 58.
4, the inflow hole 53 and the discharge hole 51 are in communication with each other, and the master cylinder pressure increases the wheel cylinder pressure while being influenced by the throttle 52.

When the coil 57 is energized, the armature 56 is displaced toward the inflow hole 53 side against the urging force of the return spring 58, and the front end of the needle 55 contacts the valve seat surface 54, The wheel cylinder pressure is maintained by blocking the inflow hole 53 and the discharge hole 51.

Therefore, when the wheel cylinder pressure is gradually increased by using the solenoid valve 8 as described above, the wheel cylinder is kept energized to close the space between the inflow hole 53 and the discharge hole 51. From the pressure holding state, the coil 57 is deenergized at predetermined time intervals, for example, in the shape of a short rectangular wave (pulse) whose duty ratio is controlled, and the inflow hole 53 and the discharge hole 51 are opened. The wheel cylinder pressure is increased and is repeated every predetermined time so that the wheel cylinder pressure is increased stepwise.

In the wheel cylinder pressure gentle pressure increase control, the de-energization signal to the coil having the short pulse shape is a signal for controlling the overall pressure increase speed of the slow pressure increase control. be able to.

[0010]

By the way, when a current is passed through the coil of such a solenoid valve, the coil generates heat due to the electric resistance of the coil, and in the case of PWM driving, an AC induction resistance is also added. The amount of heat generated is larger than that in the case of driving, so that the temperature of the coil rises. When the temperature of the coil rises, the resistance value of the coil fluctuates and P
A shift occurs in the correspondence between the duty ratio of the WM control signal and the opening / closing operation amount of the solenoid valve.

Further, due to fluctuations in the battery voltage, etc., A
When the power supply voltage to the BS controller fluctuates, the duty ratio of the PWM control signal and the opening / closing operation amount of the solenoid valve deviate from each other. Due to the deviation of these correspondences, as shown in FIG. The relationship between the duty ratio and the wheel cylinder pressure (referred to as W / C pressure in FIG. 19) is not constant,
Therefore, the ABS control performance is adversely affected, and the precise A
There is a problem that BS control is hindered.

Further, in the case of controlling the working fluid pressure or its flow rate in small increments as in the PWM control, the fluid path system vibrates due to the pulsation of the fluid pressure. As is known, the vibration of the vehicle body that occurs when the pressure is gradually increased or decreased during the ABS control is originally caused by the pulsation of the fluid pressure, which causes the pulsation of the braking force to be transmitted to the vehicle body through the suspension system. However, there is also vibration that is directly transmitted to the vehicle body from a piping system that constitutes a fluid path system between the solenoid valve and the wheel cylinders via a mounting member of the piping system.

That is, the fluid pressure system is closed from the solenoid valve to the wheel cylinder, and the pressure fluctuation of the working fluid develops at the same period as the resonance frequency of the fluid path system, mainly the piping system, which constitutes the fluid pressure system. This state is shown in FIG. 20 as a pressure fluctuation when a single pulse pressure increase / decrease signal (valve opening signal) is applied.

It should be noted that the fact that the wheel cylinder pressure once decreases despite the fact that the valve opening signal continues and the solenoid valve is open is due to the pulsation of the working fluid. And
The reason why the amplitude of the pulsation gradually decreases is mainly due to the viscous resistance of the diaphragm 52. Also, when the valve is opened and closed, pressure fluctuations due to resonance of the piping system occur. Incidentally, the vibration of the piping system is larger when the valve is closed and when the valve is closed.

In order to suppress such pulsation of the wheel cylinder pressure, generally, a fluid pressure device such as an orifice or a damper is added in the actuator including the solenoid valve. The addition may reduce the responsiveness of braking force generation during normal braking (non-ABS braking).

There is also a problem that the cost is increased by the addition of such a fluid pressure device. Further, the suppression of the pulse pressure by these fluid pressure devices is to accelerate the convergence by viscous resistance and does not suppress the pulse that triggers the generation of the fundamental pulse pressure.

The present invention has been developed in view of these problems, and the deviation of the correspondence between the duty ratio of the PWM control signal and the opening / closing operation amount of the solenoid valve due to the temperature change of the coil and the fluctuation of the power supply voltage. An object of the present invention is to provide a brake fluid pressure control device such as a control device capable of performing compensation and performing accurate ABS control.

Further, by giving rise and fall of the control signal for controlling the opening and closing of the solenoid valve so that the solenoid valve can be opened and closed gently, the pulsation of the braking cylinder pressure itself can be prevented. It is an object of the present invention to provide a brake fluid pressure control device such as an anti-skid control device that can reduce the vibration generated in the fluid path system and the noise caused by the vibration and can reduce the cost.

[0019]

In order to solve the above-mentioned problems, the brake fluid pressure control device according to claim 1 of the present invention, as shown in the basic configuration diagram of FIG. An actuator for adjusting the fluid pressure of the braking cylinder of each wheel according to a control signal and controlling the opening / closing operation of the solenoid valve of the actuator based on the slip state of the wheel. In a brake fluid pressure control device including actuator control means for outputting a control signal, the actuator control means performs PWM control of a control signal for controlling a current value to the solenoid valve during brake fluid pressure control, and PWM control means. A coil current detecting means for detecting a current value of the coil of the solenoid valve, wherein the PWM control means has an on-duty ratio of 10
The duty ratio of the PWM control is set according to the ratio of the coil current detection value at 0% and a preset reference current value.

According to a second aspect of the present invention, in the brake fluid pressure control device, the coil current detection value at the on-duty ratio of 100% is used as the coil current value during the depressurizing operation during the ABS operation or the hydraulic pressure holding operation. Based on this, the duty ratio of the PWM control signal for the next pressure increase is set for each pressure reduction or hydraulic pressure holding operation.

In the brake fluid pressure control device according to claim 3 of the present invention, the brake fluid pressure control device according to the third aspect of the invention gradually increases the next time in accordance with the coil current detection value during the pressure reduction operation during ABS operation or during the fluid pressure holding operation immediately after pressure reduction. The duty ratio of the PWM control signal at the time of pressure is set.

Further, in the brake fluid pressure control device according to a fourth aspect of the present invention, the actuator control means causes the solenoid valve to gradually move in at least one of the opening direction and the closing direction to gradually increase and decrease the pressure. , A duty ratio setting means for gradually increasing / decreasing the duty ratio of the PWM control signal is provided, and the next time in accordance with the coil current detection value at the on-duty ratio of 100% set during the hydraulic pressure holding operation during the slow pressure increasing operation. The duty ratio of the PWM control signal at the time of outputting the pressure increase / decrease signal is set.

Therefore, in the brake fluid pressure control device according to claim 1 having the above-mentioned configuration, when the brake fluid pressure is controlled,
The PWM control means included in the actuator control means PWM-controls the current value to the solenoid valve, and the working fluid pressure to be supplied to the braking cylinder is adjusted to a pressure that is suitable for braking and steerability maintaining the slip ratio of the wheel. Can be maintained at.
In particular, the coil current detection means of the solenoid valve detects the current value actually sent to the solenoid valve when the on-duty ratio is 100%, and the PWM is determined according to the ratio between this and the preset reference current value. By setting the duty ratio of the PWM control by the control means, the change of the exciting current due to the temperature change of the coil of the solenoid valve or the change of the power supply voltage is compensated, and the deviation between the solenoid valve operation amount and the duty ratio is eliminated. So
The deviation between the control signal and the actual working fluid pressure is eliminated.

Further, in the brake fluid pressure control device according to the second aspect, the coil current detection value at the on-duty ratio of 100% is used as the coil current value during the pressure reducing operation or the fluid pressure maintaining operation during the ABS operation. By setting the duty ratio of the PWM control signal for the next pressure increase for each pressure reduction or hydraulic pressure holding operation based on this, the duty ratio is always set based on the latest coil current value. Compensation for temperature and power supply voltage variations can be made to further reduce the deviation between the control signal and the actual working fluid pressure.

In the ABS control, in the depressurized state and the hydraulic pressure maintained state, in order to completely close the solenoid valve for inflow, a current having an on-duty ratio of 100% is sent to the solenoid valve. There is.

Further, in the brake fluid pressure control device according to the third aspect, the PWM for the next slow pressure increase is performed according to the coil current detection value during the pressure reduction operation during the ABS operation or during the fluid pressure holding operation immediately after the pressure reduction. By setting the duty ratio of the control signal, it is possible to further reduce the deviation between the control signal and the actual working fluid pressure when the pressure is slowly increased, which requires particularly high precision.

Further, in the brake fluid pressure control device according to the present invention, the duty ratio setting means provided in the actuator control means determines the time change rate of the fluid pressure to the braking cylinder during ABS control by the electromagnetic ratio. By gradually increasing or decreasing the pressure within the allowable range of the valve and gradually moving the solenoid valve in the opening direction or the closing direction, sudden opening and closing of the valve is not performed, and therefore the pulsation of hydraulic pressure to the braking cylinder is prevented. The vibration of the vehicle body, the piping system, etc., which is suppressed and is generated during the ABS control described above, is prevented.

Further, the duty ratio of the PWM control signal for the next output of the boosting signal is set in accordance with the coil current detection value at the on-duty ratio of 100% set during the fluid pressure holding operation during the slow boosting operation. As a result, even if the state where the duty ratio is 100% does not appear for a relatively long time such that the solenoid valve gradually moves in the opening direction or the closing direction and gradually increases the pressure, the latest coil current value is obtained as much as possible. It is possible to compensate for changes in coil temperature and power supply voltage based on precision AB
S control becomes possible.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a brake fluid pressure control device according to the present invention will be described below with reference to the accompanying drawings. The contents of the above description are roughly divided into a configuration for the purpose of PWM control, compensation of fluctuation of coil resistance of solenoid valve and fluctuation of power supply voltage, and suppression of pulsation of hydraulic pressure to a braking cylinder. A detailed description of the action, claim 1.
~ It corresponds to claim 4.

FIG. 2 shows an embodiment in which the brake fluid pressure control device of the present invention is applied to an anti-skid control device for a rear-wheel drive vehicle based on the FR (front engine / rear drive) system. In the figure, 1FL and 1FR are front left and right wheels, 1RL and 1RR are rear left and right wheels, and the rear left and right wheels 1RL and 1RR are provided with a rotational driving force from an engine EG to a transmission T, a propeller shaft PS, and a differential gear. It is transmitted via DG. Wheel cylinders 2FL to 2RR as braking cylinders are attached to the wheels 1FL to 1RR, respectively.

Further, the front left and right wheels 1FL and 1FR have pulse signals PS _FL and PS _FR corresponding to the rotational speeds of these wheels.
Wheel speed sensors 3FL and 3FR as a wheel speed (hereinafter, also simply referred to as wheel speed) detecting means for outputting are output to the propeller shaft PS.
A wheel speed sensor 3R as a wheel speed detecting means for outputting a pulse signal PS _R according to the average rotational speed of L, 1RR is attached. Further, the vehicle is provided with a longitudinal acceleration sensor 16 which detects and outputs longitudinal acceleration Xg generated in the longitudinal direction of the vehicle body.

Front wheel side wheel cylinders 2FL, 2F
In R, one master cylinder pressure P _MCF from the master cylinder 5 that generates two systems of master cylinder pressures on the front wheel side and the rear wheel side according to the depression of the brake pedal 4,
It is supplied individually via the front wheel side actuators 6FL, 6FR and is also supplied to the rear wheel side wheel cylinders 2RL,
In 2RR, the other master cylinder pressure P _MCR from the master cylinder 5 is common to the rear wheel side actuator 6R.
And is configured as a three-sensor three-channel system as a whole.

The master cylinder 5 is provided with pressure sensors 13F and 13R for detecting and outputting the two-system master cylinder pressures P _MCF and P _MCR . In addition, working fluid pressures (hereinafter, also referred to as wheel cylinder pressures) P _FL and P _R of the wheel cylinders 2FL to 2RR are provided in the fluid paths between the wheel cylinders 2FL to 2RR corresponding to the actuators 6FL to 6R. Pressure sensor 1 to detect
8FL to 18R are provided.

As shown in FIG. 3, each of the actuators 6FL to 6R includes an electromagnetic inflow valve 8 interposed between a hydraulic pipe 7 connected to a master cylinder 5 and a wheel cylinder 2FL to 2RR, and an electromagnetic inflow valve 8 of the same. A series circuit of an electromagnetic outflow valve 9, a hydraulic pump 10 and a check valve (not shown) connected in parallel with the inflow valve 8, an electromagnetic outflow valve 9 and an electromagnetic pump 10.
And a reservoir 12 which also serves as an accumulator and is connected to a hydraulic pipe between the two. In addition, 10a is a pump motor.

The electromagnetic valves constituting the electromagnetic inflow valve 8 and the electromagnetic outflow valve 9 are the same as or substantially the same as those of the conventional one shown in FIG. 20, and the connection structure and operation thereof are also the same as those described above. Or, since they are almost the same, detailed description thereof will be omitted.

Due to the operation compensation at the time of abnormality, that is, the so-called fail-safe relationship, the electromagnetic inflow valve 8 is normally open (pressure increasing state) at a normal position without energization and closed (pressure holding state) at a switching position by energization. ), The electromagnetic outflow valve 9 is normally closed (pressure holding state) in the normal position where there is no energization, and open (depressurized state) in the switching position by energization.
Move to Then, the transition of these solenoid valves 8 and 9 to the open state is referred to as an opening operation, and the transition to the closed state is referred to as a closing operation.

Further, the current value control for adjusting the opening / closing operation of the respective solenoid valves 8 and 9 is substantially performed by the duty ratio control in the PWM control which will be described later. In the pressure-increasing mode, the pressure-increasing state of the electromagnetic inflow valve 8 and the pressure-retaining state are repeatedly selected and set at predetermined intervals to control the pressure-increasing gradient of the wheel cylinder pressure.
By repeatedly selecting and setting the pressure reduction state and the pressure holding state by the electromagnetic outflow valve 9 every predetermined time, the pressure reduction gradient of the wheel cylinder pressure is controlled.

The electromagnetic inflow valve 8, the electromagnetic outflow valve 9 and the hydraulic pump 10 of each of the actuators 6FL to 6R have the wheel speed pulse signals PS _FL from the wheel speed sensors 3FL to 3R.
-PS _R and longitudinal acceleration X from longitudinal acceleration sensor 16
g and a pressure sensor 13F, the master cylinder pressure P _MCF from 13R, the brake pedal depression from a brake switch 14 that detects the depression of the wheel cylinder pressure P _FL to P _R and the brake pedal 4 from P _MCR and pressure sensor 18FL~18R Brake switch signal B that sometimes turns on
It is controlled by the hydraulic pressure control signals EV, AV and MR from the control unit CR, which S inputs.

The control unit CR has the wheel speed pulse signals PS _{FL to} P _FL from the wheel speed sensors 3FL to 3R.
The wheel speed Vw _FL , which is the peripheral speed of each wheel, is input from S _R and from these and the tire rolling radius of each wheel 1FL to 1RR.
Wheel speed calculating circuit 15FL~15R for calculating the ～Vw _R
And an estimated vehicle speed (hereinafter also referred to as pseudo vehicle speed) Vi based on the wheel speeds Vw _{FL to} Vw _R of the wheel speed calculation circuits 15FL to 15R, and the target wheel cylinder pressures P _FL * to P _R *. And the target wheel cylinder pressures P _FL * to P _R * and the pressure sensors 18FL to 18R.
The microcomputer 20 as a control means for outputting the control signals EV, AV and MR to the actuators 6FL to 6R so that the wheel cylinder pressures P _{FL to} P _R detected in step S1. Output control signals EV _{FL to} EV _R , AV _FL
~ AV _R and MR _FL ~ MR _R are PWM drive circuits 22a _FL ~
It is supplied to the actuators 6FL to 6R via 22a _R , 22b _{FL to} 22b _R and 22c _{FL to} 22c _R.

Then, the microcomputer 20
Are the wheel speeds Vw _{FL to} Vw _R , which are the output values from the wheel speed calculation circuits 15FL to 15R, and the longitudinal acceleration sensor 1.
6, an input interface circuit 20a having an A / D conversion function for reading the longitudinal acceleration Xg and the like, an arithmetic processing unit 20b such as a microprocessor, ROM, RA
A storage device 20c such as M, and control signals EV _{FL to} EV _R , AV _{FL to} AV _R and MR obtained by the arithmetic processing device 20b.
D / A for outputting the _{FL ~MR R} as an analog signal
An output interface circuit 20d having a conversion function is provided.

The microcomputer 20 calculates the pseudo vehicle speed Vi as the vehicle body speed detection value from the maximum wheel speed Vw _H using the wheel speeds Vw _{FL to} Vw _R , and the target wheel speed Vi based on the pseudo vehicle speed Vi. Vw * is calculated and the wheel speeds Vw _{FL to} Vw _R are differentiated to differentiate the wheel acceleration / deceleration V ′.
w _{FL to} V′w _R are calculated, and the wheel speeds Vw _{FL to} Vw _{R, the} wheel acceleration / deceleration V′w _{FL to} V′w _R, and the target wheel speed Vw * are calculated.
Calculates a target wheel cylinder pressure P _FL * ~P _R * on the basis of equal, such that the wheel cylinder pressure P _FL to P _R and the target wheel cylinder pressure P _FL * ~P _R * matches, each actuator 6FL ~ Control signal EV _FL for 6R ~
EV _R, AV _FL ~AV _R, and outputs the MR _FL ~MR _R.

Next, the operation of the brake fluid pressure control device according to the above embodiment will be described with reference to FIGS. 4 to 9 showing the arithmetic processing of the microcomputer 20. The arithmetic process shown in FIG. 4 is executed as an interrupt process to the main program every predetermined time (for example, 10 msec). It should be noted that although no particular information input / output step is provided in this flowchart, the information calculated and set by the arithmetic processing device 20b is stored in the storage device 20c at any time, and is also stored in the storage device 20c. The stored information is transmitted to and stored in the buffer or the like of the arithmetic processing unit 20b at any time.

In this calculation process, first, step S1
Then, the master cylinder pressures (M / C pressures) P _MCF and P _MCR of the pressure sensors 13F and 13R and the longitudinal acceleration Xg of the longitudinal acceleration sensor 16 are read. Next, step S
2, the wheel speeds Vw _{FL to} Vw _R (Vwi in the figure) of the wheel speed calculation circuits 15FL to 15R are read.

Next, in step S3, the wheel speeds Vw _{FL to} Vw _R read in step S2 are differentiated with respect to time, and the wheel acceleration / deceleration V'w _{FL to} V'w _R (V in the figure:
′ Wi) is calculated, and these are stored in a predetermined storage area of the storage device 20c. Next, the process proceeds to step S4, and the vehicle body speed calculation process for calculating the pseudo vehicle speed Vi based on the wheel speeds Vw _{FL to} Vw _R read in step S2 is executed.

Next, in step S5, the wheel cylinder pressures P _FL to P _FL of the pressure sensors 18FL to 18R are set.
Read P _R (Pi in the figure). Next, in step S6, the target wheel speed V is calculated by calculating the following equation (1).
w * is calculated and stored in the target wheel speed storage area set in the storage device 20c. Vw * = 0.8Vi ………… (1)

Next, in step S7, it is determined whether or not the wheel speed Vwi is smaller than the target wheel speed Vw *. If Vw *> Vwi, the process advances to step S8, and if not, the step The process moves to S9. In step S8, the target wheel acceleration / deceleration V'w * is set to "0" and stored in the target wheel deceleration storage area set in the storage device 20c, and the process proceeds to step S10.

On the other hand, in step S9, the following equation (2) is calculated to calculate the target wheel acceleration / deceleration V'w *, and then the process proceeds to step S10. V'w * = V'wo ... (2) Here, V'wo is a preset negative set value.

In step S10, the target wheel cylinder pressure P _FL for each wheel cylinder 2FL to 2R is set.
A target wheel cylinder pressure calculation process for calculating * to P _R * is executed. Next, in step S11, the wheel cylinder pressures P _{FL to} P _R and the target wheel cylinder pressure P are set.
_FL * ~P _R * actuator depending on the difference between the 6FL~
The control signals EV, AV, MR for 6R are determined, the actuator control process for outputting them is executed, the timer interrupt process is terminated, and then the predetermined main program is restored.

Incidentally, step S4 of the arithmetic processing of FIG.
The pseudo vehicle speed calculation processing as a subroutine executed in the above is specifically disclosed in Japanese Patent Application Laid-Open No. 4-27 filed by the applicant earlier.
It can be considered that the hardware configuration described in Japanese Patent No. 650 is a software configuration, and the description of the specific calculation process is omitted. Then, in step S10 of the calculation process of FIG. 4, the target wheel cylinder pressure calculation process is executed as a subroutine according to the flowchart of FIG.

Next, step S1 of the arithmetic processing shown in FIG.
In 1, the actuator control calculation process is executed as a subroutine according to the flowchart of FIG. Next, the actuator control signal output calculation process for the electromagnetic inflow valve 8 executed by the microcomputer 20 will be described with reference to the flowchart shown in FIG.

This calculation processing is a time (for example, 1 msec) sufficiently shorter than the execution time ΔT of the calculation processing of FIG.
It is executed as a free-run timer interrupt process for each ΔT _EVi . In the flowchart of FIG. 7A, the flag code, the timer code, the duty ratio code, etc. described above are the same as those in the description of the arithmetic processing of FIG.

Here, the duty ratio D of the electromagnetic inflow valve 8
Briefly described closing side predetermined duty ratio D _Hevi and later to open side by a predetermined duty ratio D _LEVI of _EVi. As described above, the electromagnetic outflow valve 9 is normally open and closed by energization, and the current value thereof is the duty ratio D.
_Controlled by _LEVi . The variable range of the duty ratio D _LEVi is, of course, 0 to 100%. However, as shown in FIG. 8A, the duty that can increase the wheel cylinder pressure (W / C pressure in the figure) to the master cylinder pressure is controlled. Ratio D
_EVi is in a fully closed state with a relatively large closed-side predetermined duty ratio D _H , and has a relatively small open-side predetermined duty ratio D _L
Then, it will be almost fully opened.

FIG. 8 shows a case where this is replaced by a valve displacement.
(B). Here, the variable effective range (effective duty range in the figure) of the duty ratio capable of adjusting and controlling the valve displacement is only 10 to 15% of the total variable range. Thus, the closed side duty ratio D _EVi of the duty ratio variable scope and closing side predetermined duty ratio D _Hevi solenoid inlet valve 8, the open-side duty ratio D _EVi and open-side predetermined duty ratio D _LEVI.

In the actuator control signal output calculation process for the electromagnetic inflow valve 8 of FIG. 7A, first, in step S101, the inflow valve PWM control permission flag F _PWMEVi by the calculation process of FIG. 6 is set to "1". If it is in the set state, the process proceeds to step S102, and if not, the process proceeds to step S103.

In step S103, the electromagnetic inflow valve 8 is
Inlet valve duty ratio D to keep the valve fully open
_EVi is set to "0", which is stored in the storage device 20c and is output to the electromagnetic inflow valve 8 before returning to the main program. On the other hand, in step S102,
Inflow valve holding pressure control flag F by the calculation process of FIG.
It is determined whether _HOLDEVi is "0", and if the inflow valve holding pressure control flag F _HOLDEVi is in the reset state of "0", the process proceeds to step S104, and if not, the process proceeds to step S105. To do.

In step S105, the inflow valve duty ratio D _{EVi is set} so as to maintain the electromagnetic inflow valve 8 in the completely closed state.
Is set to "100"%, stored in the storage device 20c, output to the electromagnetic inflow valve 8 and then returned to the main program. Step S10
In 4, the pressure _increase cycle timer T _PEVi is incremented.

Next, in step S106, it is determined whether or not the inflow valve duty ratio reduction permission flag F _DEVi is set to "1", and the duty ratio reduction permission flag F _DEVi is set to "1". If it is in the set state of "", the process proceeds to step S107, and if not, the process proceeds to step S108.

In step S107, the storage device 20
It is determined whether or not the inflow valve duty ratio D _EVi stored in c is less than or equal to the open side predetermined duty ratio D _LEVi ,
If the inflow valve duty ratio D _EVi is less than or equal to the open side predetermined duty ratio D _LEVi , the _{process proceeds} to step S109,
If not, the process proceeds to step S110.

[0059] At step S110, from the previous inflow valve duty ratio D _EVi, calculates setting the current inflow valve duty ratio D _EVi by subtracting the duty ratio predetermined decrease amount [Delta] D _EV1i of relatively large positive value, stores the It is stored in the device 20c and is output to the electromagnetic inflow valve 8 before returning to the main program.

On the other hand, in step S109, the inflow valve duty ratio D _EVi is set to the open side predetermined duty ratio D _LEVi , which is updated and stored in the storage device 20c.
After outputting to the inflow valve 8, it transfers to step S111.

In step S111, the pressure increase timer T _EVi
Is the pressure increase time T described in the calculation process of FIG.
_It is determined whether or not _LEVi is not equal. If they are not equal, the _{process proceeds} to step S112, and if they are equal, the _{process proceeds} to step S113.

In step S112, the pressure increase timer T
After incrementing _EVi , return to the main program. Further, in step S113, the inflow valve duty ratio reduction permission flag F _DEVi is reset to "0", and then the process returns to the main program.

On the other hand, at step S108, the inflow valve duty ratio D _EVi is set to the closing side predetermined duty ratio D _HEVi.
It is determined whether or not the above, and the inflow valve duty ratio D
_{If EVi} is _greater than or equal to the closing-side predetermined duty ratio D _HEVi , the process proceeds to step S114, and if not, the process proceeds to step S115.

In step S115, the predetermined duty ratio decrease amount Δ is added to the previous inflow valve duty ratio D _EVi.
A positive duty ratio predetermined increase amount ΔD _EV2i smaller than D _EV1i is added to calculate and set the inflow valve duty ratio D _EVi this time, and this is stored in the storage device 20c.
After outputting to the electromagnetic inflow valve 8, it returns to the main program.

On the other hand, in step S114, the inflow valve duty ratio D _EVi is set to the _{close side} predetermined duty ratio D _HEVi.
And store this in the storage device 20c,
After outputting to the electromagnetic inflow valve 8, it transfers to step S116.

In step S116, the pressure increase cycle timer T _PEVi is set to the predetermined pressure increase count-up value T.
It is determined whether it is _{equal to} or greater than _dEVi , and if the pressure increase cycle timer T _PEVi is _{equal to} or greater than the predetermined pressure increase count-up value T _dEVi , the process proceeds to step S117, and if not, the process proceeds to step S118.

In step S117, the inflow valve duty ratio reduction permission flag F _DEVi is set to "1", and then the process proceeds to step S119. In step S119,
After the pressure _increase cycle timer T _PEVi is cleared to "0", the _{process proceeds} to step S118. In step S118, after the pressure increase timer T _EVi is cleared to “0”,
Return to the main program.

Next, the actuator control signal arithmetic processing for the electromagnetic outflow valve 8 executed by the microcomputer 20 will be described with reference to the flowchart of FIG. 9 (a). As apparent from a glance, this calculation process is similar to the calculation process of FIG. 7A, and therefore, the description of each step will be omitted, and only different points will be described in detail.

First, the description of the inflow valve described in the explanation of the calculation process of FIG. 7A is basically replaced with the outflow valve in the calculation process of FIG. 9A. In addition, the subscript EV added in the meaning of inflow in the arithmetic processing of FIG.
Has been changed to the subscript AV that can be followed in the meaning of outflow in the arithmetic processing of FIG.

The execution time of the calculation process of FIG. 9A may be substantially the same as the predetermined execution time ΔT _EVi , but here, the calculation process of FIG. 4 is set individually. Is executed as a free-run timer interrupt process for each predetermined execution time (for example, 1 msec) ΔT _AVi sufficiently shorter than the execution time ΔT.

The flag code, the timer code, the duty ratio code, etc. in the flowchart of FIG. 9A are the same as those in the calculation process of FIG. 7A. Also, F
Outflow valve duty ratio D _{AVi when DAVi} is set to “1”
Allow increase of. That is, it is an outflow valve duty ratio increase permission flag that permits the electromagnetic outflow valve 9 to open to allow the wheel cylinder pressure to be reduced, and its reset state is set to "0". Further, T _AVi is a decompression timer, and the outflow valve duty ratio D _AVi is maintained at the open side predetermined duty ratio D _HAVi to measure the substantial decompression time of the wheel cylinder pressure.

By this arithmetic processing, as shown in FIGS. 7 (b) and 9 (b), the PWM control output output from the actuator control means when the valve opening / closing state changes is within the duty ratio variable effective range. , It can be changed step by step in small increments to have a macroscopically smooth linear slope.

Further, in the electromagnetic outflow valve 9 which is normally closed and is opened only when energized, the state in which the outflow valve duty ratio D _AVi as the control signal is large is the open state, and the small state is the closed state. 8 (a) and FIG. 8 (b), the electromagnetic outflow valve 9 can be reversed although it is the reverse of the description of the electromagnetic inflow valve 8.
Since the variable effective range of the duty ratio in which the reduction of the wheel cylinder pressure Pi can be controlled or the valve displacement can be adjusted and controlled is basically the same, here, the electromagnetic outflow valve 9 is set in the duty ratio variable effective range. A relatively large open-side duty ratio D _AVi that causes a substantially fully closed state is _defined as an open-side predetermined duty ratio D _HAVi .

On the arithmetic processing step, the step corresponding to step S105 of FIG. 7A is deleted, and the arithmetic processing step S202 of FIG. 9A is deleted.
If the outflow valve holding pressure control flag F _HOLDAVi is not in the reset state of "0" in step S1 of FIG.
It is set to shift to step S203 corresponding to 03.

Further, from the setting change of the predetermined duty ratio D _{LAVi on the} close _side and the predetermined duty ratio D _{HAVi on} the open side, as shown in FIG.
Step S107 of (a) is step S207 in the arithmetic processing of FIG. 9 (a), step S108 is step S208, and step S110 is step S210.
In addition, the step S115 is changed to the step S215, and the other steps are the same except that the above conditions and the 100s of the step code are changed to the 200s.

Of these, in step S207, the outflow valve duty ratio D stored in the storage device 20c is determined.
_{If AVi} is equal to or higher than the open side predetermined duty ratio D _HAVi , the process proceeds to step S209, and if not, the process proceeds to step S210.

[0077] In step S210, calculates setting the current outflow valve duty ratio D _AVi added a relatively large duty ratio of the positive values predetermined increment △ D _AV1i the previous outflow valve duty ratio D _AVi, which Is updated in the storage device 20c and is output to the electromagnetic outflow valve 9, and then the main program is restored.

On the other hand, in step S208, the outflow valve duty ratio D _AVi is set to the closing side predetermined duty ratio D _LAVi.
It is determined whether or not it is the following, and the outflow valve duty ratio D
_{If AVi} is less than or equal to the closing-side predetermined duty ratio D _LAVi , the _{process proceeds to} step S214. If not, the _{process proceeds} to step S215.

[0079] Then, the in step S215, the from the previous outflow valve duty ratio D _AVi, wherein compared to the duty ratio predetermined increment △ D _AV1i, this by subtracting the duty ratio predetermined decrease amount △ D _AV2i small positive value The outflow valve duty ratio D _AVi is calculated and set, stored in the storage device 20c, and output to the electromagnetic outflow valve 9 before returning to the main program.

Next, the operation of the ABS control device of this embodiment will be described with reference to the timing charts of FIGS. In this timing chart, the vehicle is running at a constant speed at a high speed in a non-braking state on a sufficiently high friction coefficient road surface such as a dry paved road before time t0, and the brake is depressed at time t1 to start the braking. It is a simulation of the state when you do.

According to the respective calculation processes, when the brake pedal is depressed at the time t1 to enter the braking state, the pseudo vehicle speed Vi is reduced to 0 in step S6 based on the pseudo vehicle speed Vi calculated in step S4 of FIG. The target wheel speed Vw * calculated by multiplying by 0.8 is set as shown by the broken line in FIG. Further, to a time t from the time t1, since the yet ABS braking is normally braked state not performed, the wheel cylinder pressure Pi are matched to the master cylinder pressure P _MC.

Therefore, when the target wheel cylinder pressure calculation process of FIG. 7A is executed, the wheel acceleration / deceleration V '
Although wi decreases in the negative region, step S5 of FIG.
The target wheel cylinder increase / decrease amount ΔPi * calculated according to the following equation (3) in 1 is 7 as shown in FIG.
Continues to be a positive value and the wheel cylinder pressure Pi has increased, so that the calculated target wheel cylinder pressure Pi * becomes a value larger than the master cylinder pressure P _MC. According to (4), the master cylinder pressure P _MC is the target wheel cylinder pressure Pi *.
Is determined as

ΔPi * = KP × (Vwi−Vw *) + KD × (V′wi−V′w *) (3) Pi * = min (P _MC , Pi *) (4) The above formula ( In 3), the first term on the right side is a proportional control term, the second term on the right side is a differential control term, KP is a proportional gain, and KD is a differential gain.

Therefore, when the calculation process of the actuator control of FIG. 6 is executed, the target wheel cylinder pressure Pi
Since * and the master cylinder pressure P _MC match, the process proceeds from step S14 to step S16, and the PWM control permission flags F _PWMAVi and F _PWMEVi both become "0", and also at step S34, the outflow valve duty ratio D _AVi and Both the inflow valve duty ratios D _EVi become “0”, and the pressure increasing state for the actuator 6i is continued so that the master cylinder pressure P _MC is supplied as the wheel cylinder pressure Pi. Therefore, the wheel speed Vwi of each wheel 1i starts to decrease from time t1 as shown in FIG. 10 (a).

At this time, FIG. 7 (a) and FIG.
In the actuator control signal output calculation process of (a), since the inflow valve duty ratio D _EVi is set to “0”% and output, the electromagnetic inflow valve 8 is fully opened, and the outflow valve holding control flag F is also included. _{Since HOLDAVi} is set to "1", the outflow valve duty ratio D _AVi is "0".
Since the output is set to%, the electromagnetic outflow valve 9 is completely closed, and the wheel cylinder pressure Pi is equal to the master cylinder pressure P _MC, which is a so-called normal braking state.

Eventually, the pseudo wheel speed Vi becomes as shown in FIG.
If it continues to decrease as shown by the broken line in (a), the target wheel speed Vw * also decreases accordingly, and further the wheel speed acceleration / deceleration V ′.
Wi also decreases in the negative region as shown in FIG.

Therefore, when the target wheel cylinder pressure calculation process of FIG. 6 is executed, the target wheel cylinder pressure increase / decrease amount ΔPi * calculated in step S51 is as shown in FIG.
As shown in 0 (c), it starts to decrease, becomes zero at time t3, and then decreases in the negative region.

Therefore, in the subsequent step S56 of the calculation process of FIG. 5, the target wheel cylinder pressure increase / decrease amount ΔPi * is "0" with respect to the continuously increasing master cylinder pressure P _MC .
Therefore, the target wheel cylinder pressure Pi * is maintained at the previous wheel cylinder pressure Pi.

In this way, the target wheel cylinder pressure Pi
Although the increase of * is stopped, the master cylinder pressure P _MC continues to increase as shown by the broken line in FIG. 10 (d). Therefore, when the calculation process of the actuator control of FIG. Since the cylinder pressure Pi * and the master cylinder pressure P _MC do not match, the process proceeds from step S14 to step S15, and the target wheel cylinder pressure Pi *
When the wheel cylinder pressure error Perri between the wheel cylinder pressure Pi and the wheel cylinder pressure Pi is calculated, the target wheel cylinder pressure Pi * is equal to the wheel cylinder pressure Pi at time t3 or immediately thereafter, so the wheel cylinder pressure error Perri is equal to “0. Therefore, the pressure increasing time T _LEVi is calculated and set to “0” by shifting from step S17 to step S18 and performing the calculation of the following equation (5).
In addition, the depressurization time _{THAVi is} also set to "0", and then, in step S20, both the outflow valve and inflow valve PWM control permission flags F _PWMAVi and F _PWMEVi are set to "1", and steps 21 to S22 are _executed. In S24,
Since the wheel cylinder pressure holding mode is set, both the outflow valve and inflow valve holding pressure control flags F _HOLDAVi and F _HOLDEVi are set to "1", and then both the pressure increase / decrease cycle timers T _PAVi and T _PEVi are set to "0" in step S29. Is cleared, and the holding pressure mode is established in which the wheel cylinder 2i and the master cylinder 5 are shut off from each other. T _LEVi = INT (Perri / P _EV0i ) ... (5) In the above formula (5), INT represents rounding off after the decimal point.

Further, the wheel cylinder pressure increase amount reference value P
_EV0i is the execution time Δ of the arithmetic processing of FIG. 4 when the inflow valve duty ratio D _EVi calculated as the opening control amount to the electromagnetic inflow valve 8 is “0”% indicating the fully open state. During T, the amount of increase of the wheel cylinder pressure Pi when the PWM control of the electromagnetic inflow valve 8 is continued.

At this time, FIG. 7 (a) and FIG.
In the actuator control signal output calculation process of (a), since the inflow valve holding pressure control flag F _HOLDEVi is set to "1", the inflow valve duty ratio D _EVi is set to "100"% and output. , The electromagnetic inflow valve 8 is completely closed, and the outflow valve holding pressure flag F
_{Since HOLDAVi} is set to "1", the outflow valve duty ratio D _AVi is set to "0"% and output, so that the electromagnetic outflow valve 9 is completely closed and the wheel cylinder pressure Pi is immediately before that. Held in a state.

In this way, in the holding pressure mode in which the cylinder pressure of the wheel cylinder 2i is held at a constant value, the target calculated in step S51 when the target wheel cylinder pressure calculation process of FIG. 5 is executed. The wheel cylinder pressure increase / decrease amount ΔPi * decreases in the negative region, but since the target wheel speed Vw * continues to be equal to or lower than the wheel speed Vwi, the process proceeds from step S52 to step S54. The target wheel cylinder pressure increase / decrease amount ΔPi * is limited to “0”, and in step S55, the current wheel cylinder pressure Pi that holds the previous wheel cylinder pressure Pi according to the following equation (6) is used as it is as the target wheel cylinder pressure Pi *. set as, and target wheel master cylinder pressure P _MC at step S56 is set because it has continued to increase state Rushirinda pressure Pi * is directly stored. Pi * = max (0, Pi + ΔPi *) (6) Therefore, when the calculation process of the actuator control of FIG. 6 is executed, the holding pressure mode of the actuator 6i is changed as in the previous process. Continued.

After that, the wheel speed Vwi decreases, and the time t
4 becomes a value smaller than the target wheel speed Vw *, when the process of FIG. 4 is executed, the process proceeds from step S7 to step S9, and the target wheel speed Vw * is set to "0". When the target wheel cylinder pressure calculation process of FIG. 5 is executed in this state, the target wheel cylinder pressure increase / decrease amount ΔPi * calculated in step S51 continues to decrease in the negative region, and Wheel speed Vw * is wheel speed V
Since it is larger than wi, steps S52, S53,
After S55, the process proceeds to step S56, where the target wheel cylinder pressure Pi * is set to a value obtained by adding the target wheel cylinder pressure increase / decrease amount ΔPi * to the wheel cylinder pressure Pi (target wheel cylinder pressure increase / decrease amount ΔPi * itself. Is a negative value, the actual target wheel cylinder pressure Pi
* Becomes smaller).

Therefore, when the calculation process of the actuator control of FIG. 6 is executed, the wheel cylinder pressure error Perri calculated in step S15 becomes a negative value.
From step 17 to step S19, the following formula (7) is calculated to set a certain depressurization time T _HAVi ,
In addition, the pressure increase time T _LEVi is set to “0”, and then, in step S20, both the outflow valve and inflow valve PWM control permission flags F _PWMAVi and F _PWMEVi continue to be set to “1”, and then from step S21 to step S23. Since the shift is made to the wheel cylinder pressure reducing mode, the inflow valve holding pressure control flag F _HOLDEVi continues to be set to "1", but the outflow valve holding pressure control flag F _HOLDAVi is reset to "0", and then in step S27. _Boosting cycle timer T _PEVi
Continues to be cleared to "0", but the decompression cycle timer T
_PAVi is set to the predetermined depressurization count-up value T _dAVi , and then in step S28, the inflow valve duty ratio D _EVi continues to be set to "0"%, but the outflow valve duty ratio D
_{Since AVi} is set to the predetermined duty ratio D _LAVi on the _closing side,
In response to this, the control signals EVi, AVi, MRi are output to the actuator 6i as pressure reduction signals. T _HAVi = INT (Perri / P _AV0i ) …… (7)

The wheel cylinder pressure reduction amount reference value P _AV0i is set to 100% when the outflow valve duty ratio D _AVi calculated as the opening control amount to the electromagnetic outflow valve 9 indicates a fully open state. At a certain time, it is the pressure reduction amount of the wheel cylinder pressure Pwi when the PWM control of the electromagnetic outflow valve 9 is continued during the execution time ΔT of the arithmetic processing of FIG.

At this time, according to the arithmetic processing of FIG. 9 (a), the duty ratio control signal is from the closed side predetermined duty ratio D _LAVi to the open side predetermined duty ratio D _HAVi from the predetermined execution time ΔT _AVi. Is the predetermined increase of the duty ratio
It increases by D _AV1i and gradually shifts from the closed state to the opening direction within the variable duty ratio effective range. In addition,
The inclination at this time, that is, the valve opening speed is relatively large, and the electromagnetic outflow valve 9 is not steep at the opening operation, but is opened relatively quickly.

On the other hand, the increased outflow valve duty ratio D
_{When AVi} increases up to the open side predetermined duty ratio D _HAVi ,
9A, the process proceeds from step S207 to step S209 to set and output the outflow valve duty ratio D _AVi to the open side predetermined duty ratio D _HAVi , and then to step S21.
The flow of incrementing the pressure reduction T _AVi in step S212 is repeated until the pressure reduction timer T _AVi counts up in the pressure reduction time T _HAVi at 1.

Therefore, as shown in FIG. 9B, the outflow valve duty ratio D is _maintained until the depressurization time _THAVi elapses.
_{Since AVi} is maintained at the open side predetermined duty ratio D _HAVi ,
The electromagnetic outflow valve 9 is maintained in the open or substantially open state, and the wheel cylinder pressure Pi is reduced by an amount commensurate with the pressure reducing time T _HAVi .

When the depressurization timer T _AVi counts up in the depressurization time T _HAVi , the duty ratio control signal output during this period is closed from the open side predetermined duty ratio D _HAVi as shown in FIG. 9B. Side predetermined duty ratio D
Until _LAVi , the duty ratio predetermined decrease amount _{ΔD AV2i is} reduced by the predetermined execution time ΔT _AVi , and the open state is gradually changed to the closed state within the duty ratio variable effective range. The inclination at this time, that is, the valve opening speed is relatively small, and the electromagnetic outflow valve 9 is closed more slowly than the opening operation when the electromagnetic outflow valve 9 is closed.

The outflow valve duty ratio D which is gradually increased
_{When AVi decreases} to the closing-side predetermined duty ratio D _LAVi , as shown in FIG. _9B , from the start of the increase of the outflow valve duty ratio D _{AVi to} the passage of the predetermined decompression count-up value T _dAVi. , Outflow valve duty ratio D _AVi
Is maintained at the _closed side predetermined duty ratio D _LAVi , so the electromagnetic outflow valve 9 is maintained in the closed or substantially closed state and the wheel cylinder pressure Pi is maintained.

Then, every time the pressure reduction cycle timer T _PAVi counts up with the predetermined pressure reduction count-up value T _dAVi , the increase / decrease or the hold setting of the outflow valve duty ratio D _AVi is repeated, and the wheel cylinder pressure P
i is gradually reduced toward the target wheel cylinder pressure Pi *.

For this reason, the electromagnetic inflow valve 8 of the actuator 6i is maintained in the closed state, but the electromagnetic outflow valve 9 is the same as in FIG.
The actuator control signal output calculation process of (a) normally maintains the closed state, and the open state is maintained for the depressurization time T _{HAVi at} every predetermined time, and the hydraulic pump 10 is operated by the control signal MRi by the calculation process (not shown). By being driven, the working fluid in the wheel cylinder 2i is discharged to the master cylinder 5 side, whereby the cylinder pressure of the wheel cylinder 2i starts to be reduced as shown in FIG. 7B, and thereafter, the predetermined count is reached. The holding pressure and the pressure reduction are repeated every time corresponding to the up value T _dAVi , and the pressure is reduced stepwise.

By continuing this depressurized state, FIG.
As shown in 0 (a), the wheel speed Vwi recovers by increasing toward the actual vehicle speed, and at the time t5, when the target wheel cylinder pressure calculation process of FIG. The cylinder pressure increase / decrease amount ΔPi * becomes “0” again, and the target wheel cylinder pressure Pi * and the wheel cylinder pressure Pi coincide with each other accordingly. Therefore, when the actuator control process of FIG. 6 is executed. Then, the wheel cylinder pressure error Per calculated in step S15
Since ri becomes “0”, the pressure increase time T _LEVi is set to “0” by moving from step S17 to step S18 and performing the calculation of the above equation 11, and the decompression time T _HAVi is also set. Set to "0", then step S2
At 0, the outflow valve and inflow valve PWM control permission flag F _PWMAVi ,
After setting both F _PWMEVi to "1", step S21
From step S22 to step S24, the wheel cylinder holding pressure mode is set, so that the cylinder pressure of the wheel cylinder 2i is held at a constant value, as in the time t3 and thereafter.

In this wheel cylinder holding pressure mode, as described above, in the target wheel cylinder pressure calculation process of FIG. 5, the target wheel cylinder pressure increase / decrease amount ΔPi *
However, since the target wheel speed Vw * is higher than the wheel speed Vwi, the process proceeds from step S52 to step S54, and the target wheel cylinder pressure increase / decrease amount Δ
Pi * is limited to "0", whereby the target wheel cylinder pressure Pi * is held at the previous value.

After that, when the target wheel speed Vw * and the wheel speed Vwi match at time t6, when the target wheel cylinder pressure calculation process of FIG. 5 is executed, steps S52, S53, S55 and step S56 are executed. Since the target wheel cylinder increase / decrease amount ΔPi * at this time has a large value in the positive direction, the target wheel cylinder pressure Pi * is set to a value larger than the wheel cylinder pressure Pi and is stored. .

Therefore, when the calculation process of the actuator control of FIG. 6 is executed, the wheel cylinder pressure error Perri calculated in step S15 becomes a positive value, so that the process proceeds from step S17 to step S18. The formula (5) is calculated and a certain pressure increase time T _LEVi is set, and the pressure _decrease time T _HAVi is also set to “0”. Then, in step S20, the outflow valve and inflow valve PWM control permission flags F _PWMAVi , F Both _PWMEVi are continuously set to "1", and the _{process proceeds} from step S21 to step S22 to step S25 to _enter the wheel cylinder pressure increasing mode, so that the outflow valve holding pressure control flag F _HOLDAVi continues to be set to "1". , The inflow valve holding pressure control flag F _HOLDEVi is reset to “0”, and then the pressure reducing cycle timer T _PAVi is set to “0” in step S31. However, the pressure increase cycle timer T _PEVi is set to the predetermined pressure increase count-up value T.
_{Since the} outflow valve duty ratio D _EVi is set to the closing-side predetermined duty ratio D _HEVi in step S32, the control signals EVi, AVi, MRi are set accordingly.
Is output to the actuator 6i as a pressure reduction signal.

As described above, when the pressure increasing mode is selected,
Immediately after the pressure increasing mode is selected in the calculation process of FIG. 7A, the duty ratio control signal _changes from the _close side predetermined duty ratio D _HEVi to the open side predetermined duty as shown in FIG. 7B. _{Microscopically} up to the ratio D _LEVi , the duty ratio predetermined decrease amount Δ for each predetermined execution time ΔT _EV1.
It becomes smaller by D _EV1i , and macroscopically, gradually changes from the closed state to the open state within the duty ratio variable effective range. It should be noted that the inclination at this time, that is, the valve opening speed is relatively large, and the electromagnetic inflow valve 8 is relatively steeply opened during the opening operation, although not steeply.

On the other hand, when the reduced duty ratio D _{EVi of the} inflow valve decreases to the predetermined open side duty ratio D _LEVi , as shown in FIG. 7B, the inflow valve duty ratio T _LEVi elapses until the pressure increase time T _LEVi elapses. Since the duty ratio D _EVi is maintained at the open side predetermined duty ratio D _LEVi , the electromagnetic inflow valve 8 is maintained in the open or substantially open state, and the wheel cylinder pressure Pi is increased by an amount corresponding to the pressure increase time T _LEVi. To be done.

When the pressure increase timer T _EVi counts up in the pressure increase time T _LEVi , the duty ratio control signal output during this period is the open side predetermined duty ratio D _LEVi as shown in FIG. _7B. To the closed side predetermined duty ratio D
_Up to _HEVi , the duty ratio predetermined increase amount 6D _EV1i increases by the predetermined execution time ΔT _EV1 , and gradually shifts from the open state to the closing direction within the duty ratio variable effective range. The inclination at this time, that is, the valve closing operation speed is relatively small, and the electromagnetic inflow valve 8 is closed more slowly during the closing operation than during the opening operation.

Eventually, the inflow valve duty ratio D is increased.
_{When EVi} increases to the _{close side} predetermined duty ratio D _{HEVi, the} predetermined pressure increase count-up value T _dEVi elapses after the inflow valve duty ratio D _EVi starts decreasing as shown in FIG. 7B. Up to inflow valve duty ratio D _EVi
Is maintained at the predetermined duty ratio D _HEVi on the closing side, the electromagnetic inflow valve 8 is maintained in the closed or substantially closed state, the wheel cylinder pressure Pi is held, and the pressure increase cycle timer T _PEVi is maintained.
Is repeatedly increased / decreased or held at the inflow valve duty ratio D _EVi every time the predetermined pressure increase count-up value T _dEVi is counted up, and the wheel cylinder pressure Pi becomes the target wheel cylinder pressure Pi *. The pressure is gradually set to increase.

Therefore, the electromagnetic outflow valve 9 of the actuator 6i is maintained in the closed state, but the electromagnetic inflow valve 8 is kept in the state shown in FIG.
By the actuator control signal output calculation process of (a), normally, the closed state is maintained, and the pressure increasing time T _{LEVi is} opened at every predetermined time, and the working fluid on the master cylinder 5 side enters the wheel cylinder 2i. The cylinder pressure of the wheel cylinder 2i is supplied as shown in FIG. 7 (b).
As shown in (4), the pressure increase is started, and thereafter, the holding pressure and the pressure increase are repeated at each time corresponding to the predetermined pressure increase count-up value T _dEVi , and the pressure is increased stepwise.

After the wheel speed Vwi is recovered, the wheel speed Vw output from the wheel speed calculation circuit 15i at time T7.
When i select-high wheel speed Vw _H of substantially coincides with the pseudo vehicle speed Vi, the select-high wheel speed Vw _H that abruptly decelerated
There between times t8 away from the pseudo vehicle speed Vi, the pseudo vehicle speed Vi is set to match to the select high wheel speed Vw _H, The target wheel speed Vw * is accordingly, Figure 1
It is assumed that 0 (a) is set as indicated by the broken line.

On the other hand, the wheel speed Vwi starts to decrease again as shown in FIG. 10 (a) due to the increased pressure of the wheel cylinder 2i, and after the time t8, the wheel speed Vwi is reduced at each execution time ΔT.
The pseudo vehicle speed Vi is calculated and set as indicated by the broken line at 0 (a), and the target wheel speed Vw * is also set in accordance with the calculated setting.

When the target wheel cylinder pressure calculation processing of FIG. 5 is executed at time t9, step S5 is started.
Target wheel cylinder pressure increase / decrease amount ΔPi * calculated by 1
Becomes “0”, the holding pressure state is established as at the time t3 described above, and when the process of FIG. 5 is executed next, the process proceeds from step S52 to step S54 and the target pressure increase / decrease amount ΔPi * Is held in the state of "0".

Thereafter, at time t10, the target wheel speed Vw *
When becomes smaller, when the target wheel cylinder pressure calculation process of FIG.
After 55, the process proceeds to step S56, and the above-mentioned time t4
Similarly to the above, the pressure is reduced, and thereafter, the holding pressure state at time t11, the pressure increasing state at time t12, the holding pressure state at time t13,
At time t14, the reduced pressure state is repeated and the pseudo vehicle speed Vi decreases.

The above is the description regarding the suppression of the pulsation of the hydraulic pressure to the braking cylinder of the PWM control means and the actuator control means in the configuration of the brake hydraulic pressure control device according to claim 1 of the present invention. ), Steps S104, S114, S116 and / or FIG.
Steps S204 and S21 in the flowchart of (a)
4, S216 corresponds to the hydraulic pressure holding means, and the same applies to step S11 of the flowchart of FIG.
Step S18 or S19 of the flowchart of FIG. 7 corresponds to the valve opening time setting means, and step S110 or S115 of the flowchart of FIG. 7A and / or step S210 or S215 of the flowchart of FIG. 9A serves as the duty ratio setting means. The entire flowchart of FIG. 6 and the entire flowchart of FIG. 7A and / or FIG. 9A executed in step S11 of the flowchart of FIG. 4 correspond to the PWM control means, and the flowchart of FIG. Alternatively, the entire flowchart of FIG. 9A corresponds to actuator control means.

In this embodiment, the pressure increase / decrease count is increased under the pressure increase / decrease count up values T _dEVi , T _dAVi corresponding to the pressure increase / decrease cycle time set based on the _fineness of the pressure increase / decrease control. Only the up values T _dEVi and T _dAVi are used as variables, and the other predetermined open duty ratios D _HAVi and D _LEVi and _close predetermined duty ratios D _LAVi and D _{HEVi are used.}
And duty ratio predetermined increase / decrease amount _{ΔD AV1i} , _{ΔD AV2i} , _ΔD
EV1i , _{ΔD EV2i,} etc. can be appropriately set or selected as constants. By doing so, the algorithm of the arithmetic processing is simplified and the execution speed of the arithmetic processing can be increased.

Further, the duty ratio predetermined increase / decrease amount Δ
_{D AV1i, △ D AV2i, △} D EV1i, △ D EV2i is enough to set a small absolute amount, a high pulsation suppression effect of the wheel cylinder pressure. However, if it is made too small, the transition time from the open state to the closed state of the solenoid valve or from the closed state to the open state becomes long, and a sufficient pressure increasing / decreasing time cannot be obtained.

Therefore, in terms of design, the duty ratio is determined in consideration of the responsiveness of the control of the wheel cylinder pressure and the condition required for the vehicle such as the pulsation suppression effect of the wheel cylinder pressure (for example, vibration noise suppression effect). It is necessary to set the above-mentioned predetermined duty ratio predetermined increase / decrease amount at an optimum compromise between the contradictory numerical values of increasing / decreasing the increase / decrease amount.

[0120] Also, the duty ratio predetermined pressure increase amount corresponding to the valve closing speed △ D _AV2i, △ D effects on the pulsation of _EV2i is, the duty ratio corresponding to the valve-opening speed predetermined pressure increase amount △ D _{AV1i, ΔD EV1i} is larger than the influence on pulsation, so it is of course possible to set the former smaller than the latter and take a longer transition time from the open state to the closed state of the solenoid valve. Side duty ratios D _HAVi , D _LEVi , _close side duty ratios D _LAVi , D _HEVi and duty ratio predetermined pressure increase / decrease amounts _{ΔD AV1i} , _{ΔD AV2i} , _{ΔD EV1i} , _{ΔD EV2i} The pressure times T _HAVi and T _LEVi should be set.

In an actual vehicle, the vehicle speed, the friction coefficient of the road surface, etc. should be taken into consideration when setting the amount of increase / decrease of the wheel cylinder pressure Pi. Further, it is necessary to sufficiently consider the timing of the free-run timer interrupt, which is related to the increase / decrease rate of change of the duty ratio, the time required to execute the arithmetic processing of each program, and the like.

Further, as described above, generally, there is an individual variation in the duty ratio variable effective range of the solenoid valve and the correspondence between the duty ratio and the valve operation amount due to the operating environment such as temperature. Side predetermined duty ratio D _HAVi ,
It is necessary to set D _LEVi and predetermined _closed-side duty ratios D _LAVi and D _HEVi according to each vehicle.

In such a brake fluid pressure control device, in the present invention, the coil current detecting means DIC is provided as shown in FIGS. 1 and 2 to detect the current flowing through the coil CEM at a duty ratio of 100%. Input is made to the arithmetic processing unit 20b and the storage unit 20c via the input interface circuit 20a.

That is, the coil current detecting means DIC is as shown in FIG.
As shown in FIG. 1, a battery BATT as a power source is connected to one end of a coil (solenoid valve) CEM of the electromagnetic inflow valve 8, and the other end of the coil CEM is connected to a shunt resistor RS.
And a field effect transistor FET that switches at high speed by a PWM signal, and is connected to the ground GND to generate a potential difference proportional to the current across the shunt resistor RS, and to connect both ends of the shunt resistor RS to the input resistor Ri. _Is connected to the inverting input terminal and the non-inverting input terminal of the operational amplifier O _AMP via, and the inverting input terminal and the output terminal of the operational amplifier O _AMP are connected via the feedback resistor Rf,
The non-inverting input terminal and the ground GND are connected via the ground resistance Rb. A flywheel diode FLD is connected in parallel to the coil CEM.

By configuring the coil current detection means DIC in this way, the voltage that is accurately proportional to the above potential difference is used as the current detection value and the wheel cylinder pressure is reduced via the input interface circuit 20a having the A / D conversion function. It is possible to input to the microcomputer 20 at the same timing during the operation or the hydraulic pressure holding operation.

Next, with reference to FIGS. 12 to 15, a description will be given of a calculation process using the coil current detection value when the duty ratio is 100%. The coil current detection value fetched by the microcomputer 20 is processed according to the flowchart shown in FIG. That is, in step S301, ABS
If the ABS control is not performed, it is determined whether or not the control is performed. In step S302, the PWM control output is prohibited, and in step S303, the normal mode (pressure increase mode) is set and then the main program is restored. To do.

If it is determined in step S301 that the ABS control is being performed, it is determined in step S304 whether the current state is the reduced pressure state, the hydraulic pressure holding state, or the increased pressure state. If so, P in step S305
After the WM control output is prohibited, the process proceeds to step S306. In step S306, the depressurization time is set in the free-run timer A, the depressurization mode is set in step S307, and then the process returns to the main program.

If it is determined in step S304 that the hydraulic pressure is maintained, the process proceeds to step S308. In step S308, the PWM control output is prohibited and then the process proceeds to step S309. In step S309, the hydraulic pressure holding mode is set and then step S310.
Move to In step S310, the value obtained by A / D converting the coil current value detected by the coil current detecting means DIC is set as R0 and the memory is updated, and then the process proceeds to step S311.

In step S311, the value obtained by multiplying the preset set current value (open side of the outflow valve) IH by 100 and dividing by the value RO is updated as the open side duty ratio DH of the outflow valve. Then, the process proceeds to step S312.
In step S312, a value obtained by multiplying a preset current value IL (close side of the outflow valve) IL by 100 and dividing the value by the value RO is updated as a close duty ratio DL of the outflow valve, and then the memory is updated. The process moves to S313. Step S3
In 13, the average value of the open side duty ratio DH and the close side duty ratio DL is set as the intermediate duty ratio DM, the memory is updated, and then the process returns to the main program.

If it is determined in step S304 that the pressure is increased, the process proceeds to step S314. In step S314, the pressure increase / decrease time is set to the free run timer A.
, And then the process proceeds to step S315. In step S315, the open side duty ratio DH of the outflow valve is stored in the duty ratio register set in the arithmetic processing unit 20b, and then the process proceeds to step S316. In step S316, the PWM output is permitted and then the process returns to the main program.

The free-run timer A determines the timing of interruption to the main program.
As shown in step 3, when this interrupt occurs, step S
At 320, it is determined whether the ABS control is in the pressure reducing state or the pressure increasing state. If the ABS control is in the pressure reducing state, the process proceeds to step S321. In step S321, the hydraulic pressure holding mode is set, and then the process returns to the main program.

If it is determined in step S320 that the pressure is increased, the process proceeds to step S322. In step S322, the intermediate duty ratio DM is stored in the duty ratio register, and then the process proceeds to step S323. In step S323, free-run timer B
The decompression count-up value Td is stored in and the main program is returned to.

The free-run timer B determines the timing of interruption to the main program.
As shown in step 4, when this interrupt occurs, step S
At 330, it is determined whether or not the current closed-side duty ratio DL is smaller than the current closed-side duty ratio DL stored in the duty ratio register. If is not small, step S33
In step 1, the current close side duty ratio DL is stored in the register and then the main program is restored.

If the current closing side duty ratio DL is smaller in step S330, the process proceeds to step S332. In step S332, the predetermined closing-side duty ratio DL, which is a reference for control stored in another register, is stored in the above register, and then the process returns to the main program.

As a result of performing such arithmetic processing, as shown in FIG. 15, the duty ratio PWM-controlled and the effective value of the exciting current (in FIG. 15, in FIG. 15) are changed due to the change of the coil resistance value due to the temperature change and the change of the power supply voltage. Corresponding to the coil current), as shown in the upper graph H or the lower graph L from the graph M at the center of the figure in which the duty ratio of the PWM control and the effective value of the exciting current correspond exactly. Even if there is a deviation, by correcting the duty ratio by the above-mentioned calculation processing, it is possible to output an exciting current having an effective value equivalent to that of the central graph M in which the duty ratio accurately corresponds to the effective value of the exciting current.

That is, as an example, the resistance of the coil increases and / or the power supply voltage decreases to decrease the effective value of the exciting current, and the correspondence between the duty ratio and the effective value of the exciting current is shown in the central graph M. The case of displacement to the lower side will be described. When the above calculation processing is not performed and the output is performed at the duty ratio indicated by D1, the effective of I ₁ ′ indicated by the intersection of the lower graph L and the vertical extension line from D1 is shown. Only the exciting current of the specified value will be output.

On the other hand, in this embodiment, D1 '= D
1 × 100 × I ₀ / I ₀ ′ is calculated, and D1 ′%
By outputting the PWM control signal of, the effective value of I ₁ indicated by the intersection of the lower graph L and the vertical extension line from the same duty ratio D1 ′ (the duty ratio and the effective value of the exciting current correspond accurately). It is possible to output an exciting current having the same effective value as that of the central graph M).

D1 is the duty ratio when the correction by the above calculation processing is not performed, I ₀ is the reference current value, and the duty ratio of the central graph M in which the duty ratio and the effective value of the exciting current correspond exactly. The effective value of the exciting current at a ratio of 100%, I ₀ ′ is the coil current detection value, and the effective value of the exciting current at a duty ratio of 100% at that time, D 1 ′ is the PWM control signal output to the solenoid valve. It is a duty ratio.

By correcting the PWM control output by the arithmetic processing as described above, FIG. 16 (a) and FIG. 16 (b) are obtained.
As shown in the timing chart of Fig. 3, it is possible to accurately draw the pattern of the intended coil current regardless of the change in the coil resistance of the solenoid valve, which in turn makes it possible to draw the intended pattern of the wheel cylinder pressure. .
Although FIG. 16A is drawn with an off-duty pattern, the vertical axis is inverted upside down and 0% is set to 100%,
By considering 100% as 0%, this can be understood as an on-duty pattern.

As a result, regardless of the change in the coil temperature of the solenoid valve, as shown in (2) and (4) of FIG. 17C, the duty ratio is controlled so as to faithfully correspond to the control purpose. As a result, as shown in (1) (3) and (1) (3) minute current change in FIG. 17D, the effective value faithfully corresponding to the control purpose in detail. Since it is possible to act on the coil of the solenoid valve with a coil current having the following, it is possible to realize a wheel cylinder pressure that faithfully corresponds to the control purpose as shown in FIG. 17 (b). As described above, during brake operation during ABS control, the pressure reducing operation is started accurately when the wheel speed crosses the line indicating the speed at which the preset slip amount is reached, and the wheel caused by excessive braking force is caused. Braking distance due to slip It is possible to prevent the extension and the steerability worse. In addition, in FIG. 17A, the vertical distance between the vehicle body speed and the wheel speed indicates the slip amount.

Further, in step S313 of FIG. 12, an arithmetic operation is performed in which an average value of the open side duty ratio DH and the close side duty ratio DL is set as an intermediate duty ratio DM, and when the pressure is increased, the intermediate duty ratio DM is used as a starting point. After that, by slowly increasing the pressure by slowing down the pressure increasing speed,
It is arranged to prevent the slip ratio from increasing due to the sudden rise of the braking force due to the rapid pressure increase and the vibration of the vehicle body from occurring (see FIG. 17C).

Further, as described above, in the present invention, the duty ratio is compensated for the coil temperature fluctuation and the power supply voltage fluctuation. Therefore, the setting slip amount is set small in consideration of such fluctuation as in the conventional case. You don't have to.

Therefore, according to the present invention, the set slip amount is set to be larger than the conventional value, or the amount of excessively decreasing the wheel speed beyond the set slip amount is set to be smaller than the conventional value, while ensuring safety. By exerting stronger braking force, the braking distance can be shortened.

[0144]

As described above, according to the brake fluid pressure control device of the first aspect of the present invention, the current value to the solenoid valve is controlled by the PWM control means provided in the actuator control means during the brake fluid pressure control. By performing PWM control, the working fluid pressure to be supplied to the braking cylinder can be maintained at a pressure that is suitable for braking and maintaining steerability and that is commensurate with the slip ratio of the wheel. In particular, the coil current detection means of the solenoid valve detects the current value actually sent to the solenoid valve when the on-duty ratio is 100%, and the PWM is determined according to the ratio between this and the preset reference current value. By setting the duty ratio of the PWM control by the control means, the change of the exciting current due to the temperature change of the coil of the solenoid valve or the change of the power supply voltage is compensated, and the deviation between the solenoid valve operation amount and the duty ratio is eliminated. Therefore, the deviation between the control signal and the actual working fluid pressure is eliminated.

Further, since the duty ratio is compensated for the coil temperature fluctuation and the power source voltage fluctuation, the wheel speed is exceeded by exceeding the set slip amount by setting the set slip amount to a value close to the limit determined by the friction coefficient. Make the braking time longer by reducing the amount of excessive reduction as much as possible,
In addition to exerting stronger braking force, excessive reduction in wheel speed beyond the set slip amount that impairs safety is minimized to shorten the braking distance and ensure steerability for safety. It is possible to improve the property. Incidentally, in the prior art, since the set slip amount is set to be small in anticipation of the above variation, there is a problem that the braking time is shortened and the braking performance is deteriorated.

According to the brake fluid pressure control device of the second aspect of the present invention, the coil current detection value at the on-duty ratio of 100% is used as the coil current value during the pressure reducing operation or the fluid pressure maintaining operation during the ABS operation. By setting the duty ratio of the PWM control signal for the next pressure increase for each pressure reduction or hydraulic pressure holding operation based on this, the duty ratio is always set based on the latest coil current value. As a result, more precise temperature and power supply voltage fluctuations are compensated for, and the deviation between the control signal and the actual working fluid pressure can be made smaller.

Further, according to the brake fluid pressure control device of the third aspect of the present invention, according to the coil current detection value of the coil current value during the pressure reducing operation during the ABS operation or the fluid pressure holding operation immediately after the pressure reduction, By setting the duty ratio of the PWM control signal at the time of the next slow increase in pressure, it is possible to further reduce the deviation between the control signal at the time of slow increase in pressure, which requires particularly high precision, and the actual working fluid pressure.

Further, according to the brake fluid pressure control device of the present invention, the duty ratio setting means provided in the actuator control means causes the time change rate of the hydraulic pressure to the braking cylinder during ABS control. By gradually increasing or decreasing the pressure within a range that the solenoid valve can tolerate, and gradually moving the solenoid valve in the opening direction or the closing direction, rapid opening and closing of the valve is not performed, and therefore the liquid to the braking cylinder is The pulsation of pressure is suppressed, and it is possible to prevent the vibration of the vehicle body, the piping system, etc. that occurs during the ABS control described above.

Further, the duty ratio of the PWM control signal at the time of the next pressure increase signal output is set according to the coil current detection value at the time of the on-duty ratio 100% set during the hydraulic pressure holding operation during the slow pressure increase operation. As a result, even if the state where the duty ratio is 100% does not appear for a relatively long time such that the solenoid valve gradually moves in the opening direction or the closing direction and gradually increases the pressure, the latest coil current value is obtained as much as possible. It is possible to compensate for changes in coil temperature and power supply voltage based on precision AB
Since the S control can be performed and devices such as an orifice and a damper that reduce the responsiveness of the wheel cylinder pressure control are not required, the responsiveness can be kept high.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a brake fluid pressure control device of the present invention.

FIG. 2 is a schematic configuration diagram of a vehicle including the brake fluid pressure control device of the present invention.

FIG. 3 is a configuration diagram of an actuator according to an embodiment of the present invention.

FIG. 4 is a flowchart of a wheel cylinder pressure control process.

FIG. 5 is a flowchart of a target wheel cylinder pressure calculation processing subroutine.

FIG. 6 is a flowchart of an actuator control calculation processing subroutine.

FIG. 7A is a flow chart of an inflow valve control signal output calculation process, and FIG. 7B is a graph showing an inflow valve control signal output pattern.

FIG. 8 (a) is a graph showing a relationship between a change in wheel cylinder pressure with respect to time and a duty ratio of a solenoid valve,
FIG. 8B is an explanatory diagram of the duty ratio variable effective range and the input pattern of the solenoid valve.

9A is a flow chart of an outflow valve control signal output calculation process, and FIG. 9B is a graph showing an outflow valve control signal output pattern.

FIG. 10 is a time chart showing the braking operation of the present invention.

FIG. 11 is a circuit diagram showing a configuration of a coil current detection means DIC.

FIG. 12 is a flowchart of a temperature / power supply voltage fluctuation compensation calculation processing subroutine.

FIG. 13 is a flowchart of a hydraulic pressure holding mode and interrupt timing setting subroutine relating to temperature / power supply voltage fluctuation compensation.

FIG. 14 is a flowchart of a register storage update subroutine relating to temperature / power supply voltage fluctuation compensation.

FIG. 15 is a graph for explaining the compensation calculation process.

FIG. 16 is a time chart showing a relationship between a PWM output pattern (a) and a coil current (b).

FIG. 17 is a time chart showing the relationship among vehicle speed and wheel speed (a), wheel cylinder pressure (b), PWM output pattern (c), and coil current (d).

18 (a) is a structural explanatory view of a solenoid valve, FIG.
(B) is an enlarged view around the valve seat surface 54.

FIG. 19 is a time chart showing the relationship between changes in wheel cylinder pressure and coil resistance and power supply voltage.

FIG. 20 is an explanatory diagram of fluctuations in working fluid pressure due to valve opening.

[Explanation of symbols]

1FL to 1RR Wheels 2FL to 2RR Wheel Cylinder (Brake Cylinder) 3FL to 3R Wheel Speed Sensor 4 Brake Pedal 5 Master Cylinder 6FL to 6R Actuator 8 Electromagnetic Inflow Valve 9 Electromagnetic Outflow Valve 10 Hydraulic Pump 10a Pump Motor 12 Reservoir 13F, 13R Pressure Sensor 15FL to 15R Wheel speed calculation circuit 16 Longitudinal acceleration sensor 18FL to 18R Pressure sensor 20 Microcomputer 20a Input interface circuit 20b Calculation processing device 20c Storage device 20d Output interface circuit 22aFL to 22aR, 22bFL to 22bR, 22c
FL ~ 22cR PWM drive circuit CR control unit DIC Coil current detection means PS Propeller shaft EG Engine T Transmission DG Differential gear

Claims (4)

[Claims] 1. An actuator, which comprises an electromagnetic valve that opens and closes according to a control signal, adjusts the fluid pressure of a braking cylinder of each wheel according to the control signal, and the actuator based on the slip state of the wheel. In a brake fluid pressure control device including an actuator control unit that outputs a control signal for controlling the opening / closing operation of an electromagnetic valve of an actuator, the actuator control unit controls a current value to the electromagnetic valve during brake fluid pressure control. A PWM control means for performing PWM control of the control signal and a coil current detection means for detecting a current value of the coil of the solenoid valve are provided, and the PWM control means preliminarily stores a coil current detection value at an on-duty ratio of 100%. The brake fluid pressure control is characterized in that the duty ratio of the PWM control is set according to the ratio with the set reference current value. Apparatus. 2. The coil current detection value with an on-duty ratio of 100% is the coil current value during depressurization operation or hydraulic pressure holding operation when the anti-brake lock system is activated, and based on this, for each depressurization or hydraulic pressure holding operation. PWM at the next pressure increase
The brake fluid pressure control device according to claim 1, wherein a duty ratio of the control signal is set. 3. The duty ratio of the PWM control signal for the next slow pressure increase is set according to the coil current detection value during the pressure reducing operation during the operation of the anti-brake lock system or during the hydraulic pressure holding operation immediately after the pressure reducing. The brake fluid pressure control device according to claim 2. 4. The duty ratio setting means for gradually increasing or decreasing the duty ratio of the PWM control signal so that the actuator control means gradually shifts the solenoid valve in at least one of the opening direction and the closing direction to gradually increase and decrease the pressure. According to the coil current detection value at the on-duty ratio of 100% set during the fluid pressure holding operation during the slow pressure increasing operation,
The brake fluid pressure control device according to claim 2, wherein the duty ratio of the PWM control signal at the time of outputting the next boosting signal is set.