JPH06127365A - Antiskid control device - Google Patents

Abstract

PURPOSE:To heighten the hydaulic pressure control accuracy of an antiskid control device for increasing/reducing brake cylinder pressure by both normal/ reverse rotation of an electric motor. CONSTITUTION:In the case of being set to a pressure boosting mode and the slip state quantity being on the increase, the preset slip state quantity Ws is successively made the maximum slip state quantity Wsp (S74), and 40% of the maximum slip state quantity Wsp is successively made the threshold Wsd (S75). In the case of the slip state quantity Ws being decreased to become the threshold Wsd or less (S76), the changeover to a pressure boosting braking hold mode is made to perform dynamic braking (S78). The normal rotation of a motor is thereby suppressed desirably, and a pressure boosting gradient can be eased to avoid excessive boosting and to improve hydraulic pressure control accuracy. Also, since the threshold Wsd is determined according to the maximum slip state quantity Wsp (the maximum rotating speed of a motor), the rotation of the motor can be suppressed according to inertia.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antiskid control device having an electric motor.

[0002]

2. Description of the Related Art Conventionally, an antiskid control device having an electric motor has been known. For example, Japanese Patent Laid-Open No. 4-16
Japanese Patent No. 6463 discloses (1) an electric motor that can rotate in both forward and reverse directions, and (2) a movable member that can be moved backward and forward by rotation of the electric motor in forward and reverse directions.
(3) A liquid chamber communicated with a brake cylinder that reduces and increases the volume by retreating and advancing the movable member, and that suppresses wheel rotation; and (4) rotating the electric motor in the forward direction to brake. Increase the hydraulic pressure in the cylinder,
Alternatively, there is described an anti-skid control device that includes a motor control device that rotates in the opposite direction to reduce the hydraulic pressure of the brake cylinder, and that controls the brake cylinder pressure so that the slip amount, slip ratio, etc. of the wheels fall within an appropriate range. ing.

Further, Japanese Patent Laid-Open No. 3-50059 discloses that
An anti-skid control device is described that includes a solenoid valve control device that controls a three-position solenoid valve that can switch between a pressure increasing position, a holding position, and a pressure reducing position. In the anti-skid control device described in this publication, the solenoid valve control device supplies a three-position solenoid valve with a current of a magnitude (duty ratio) corresponding to the slip state amount based on the graph shown in FIG. Control it. The slip state quantity is a brake cylinder pressure change request quantity as will be described later. When the slip state quantity is positive, it indicates that the pressure increase control is requested, and when the slip state quantity is negative, the pressure reduction control is requested. Further, when the slip state amount is positive and is increasing, the degree of insufficient braking force is increasing, and there is a demand to increase the pressure increasing gradient of the brake cylinder pressure. When it is decreasing, the pressure increasing gradient is increased. It indicates that there is a demand to loosen it.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention are
An attempt was made to apply the same control as the solenoid valve control described in JP-A-3-50059 to the electric motor described in JP-A-4-166464. As a result, it was clarified that when the electric motor is controlled in the same way as the solenoid valve, the pressure is excessively increased. In the solenoid valve control device, when the slip state amount is decreasing from the maximum value and there is a request to loosen the pressure increase gradient of the brake cylinder, the supply current gradually decreases as shown in the table of FIG. However, the rotation speed of the electric motor does not decrease in response to the decrease in the supplied current. That is, the rotation speed of the electric motor is due to the inertia of the electric motor,
As the magnitude of the current gradually decreases, it does not decrease immediately, but decreases with a delay. Further, the larger the slip state amount is, the more current is supplied, so that the rotational speed of the electric motor increases and the inertia increases, which makes it more difficult to decelerate.

In view of the above circumstances, the present invention has been made in order to avoid excessive pressure increase and improve hydraulic control accuracy in an anti-skid control device in which the brake cylinder pressure is controlled by an electric motor. It is a thing.

[0006]

The gist of the present invention is shown in FIG.
As shown in FIG. 4, in the anti-skid control device including the electric motor 1, the movable member 2, the movable chamber 2, the liquid chamber 3, and the motor control device 4, Four
In addition, when the electric motor 1 is rotating in the forward direction and the slip state amount decreases from its maximum value by the product of the maximum value and a predetermined coefficient, the rotation of the electric motor 1 That is, the rotation suppressing means 5 for electrically suppressing is provided.

[0007]

In the antiskid control device of the present invention,
When the electric motor is rotating in the forward direction and the slip state amount decreases from the maximum value by the product of the maximum value and a predetermined coefficient, the rotation of the electric motor is electrically reduced by the rotation suppressing means. Suppressed to. As the rotation suppressing means, so-called anti-phase braking means for applying a voltage for rotating the electric motor in a reverse direction opposite to that used so far, so-called dynamic braking means for causing the electric motor to act as a generator, and the like can be adopted. That is, the rotation of the electric motor does not decelerate immediately in response to the gradual decrease of the supply current as in the solenoid valve, but decelerates with a delay. If it is suppressed, the delay can be reduced or eliminated.

"When the slip state amount decreases from the maximum value by the product of the maximum value and a predetermined coefficient", for example, the slip state amount is from the maximum value to 60% of the maximum value.
This is the case when the size is reduced by. In other words, the slip state amount changes from an increasing tendency to a decreasing tendency and decreases to a magnitude of 40% of the maximum value (hereinafter referred to as a threshold value). Therefore, the threshold value is large when the maximum value of the slip state amount is large, and is small when the maximum value is small. For example, if the slip state amount is the above-described brake cylinder pressure change request amount and the relationship between the slip state amount and the magnitude of the supply current is as shown in FIG. 8, the slip state amount is positive. The larger the absolute value is, the larger the current supplied to the electric motor is, so that the rotation speed of the electric motor in the forward direction is increased and the inertia is increased. Therefore, the threshold value is large when the inertia is large and is small when the inertia is small.

[0009]

According to the anti-skid control device of the present invention, since the forward rotation of the electric motor is properly decelerated, the pressure increase gradient can be appropriately moderated and excessive pressure increase can be avoided. be able to. Further, since the threshold value is determined according to the inertia, deceleration can be performed according to the inertia, and the hydraulic pressure control accuracy can be improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where an antiskid control device according to an embodiment of the present invention is mounted on a vehicle will be described in detail below with reference to the drawings. In FIG. 5, reference numeral 10 denotes a master cylinder, and a brake pedal 14 is connected to the master cylinder 10 via a vacuum booster (hereinafter, simply referred to as a booster) 12. The master cylinder 10 is a tandem type in which two pressurizing pistons 18 and 20 are provided in series, and hydraulic pressures of substantially the same height are provided in two independent pressurizing chambers 22 and 24 according to the depression of the brake pedal 14. Generate. Code 2
Reference numeral 6 is a reservoir that stores the brake fluid at atmospheric pressure. The booster 12 boosts the pedaling force applied to the brake pedal 14, and transmits the boosted pedaling force to the pressurizing piston 20 via the push rod 28.

The hydraulic pressure generated in one pressurizing chamber 22 of the master cylinder 10 is transmitted to the brake cylinders 40 and 42 of the respective brakes of the right front wheel 36 and the left rear wheel 38 by the main fluid passages 30, 31, 32 and 34. The hydraulic pressure generated in the other pressurizing chamber 24 is transmitted to the brake cylinders 56 and 58 of each brake of the left front wheel 52 and the right rear wheel 54 by the main liquid passages 46, 47, 48 and 50. Proportioning valves 60 and 62 are provided between the main liquid passages 32 and 34 and between the main liquid passages 48 and 50, respectively. This brake system is of X piping type.

A liquid pressure control device 88 is provided between the liquid passage 30 and the liquid passage 31, and a liquid pressure control device 90 is provided between the liquid passage 46 and the liquid passage 47. Since the hydraulic pressure control device 88 and the hydraulic pressure control device 90 are the same, the hydraulic pressure control device 90 will be described here. As shown in FIG. 6, a bottomed cylinder bore 94 is formed in the housing 92 of the hydraulic control device 90. A fluid pressure control piston 96 is fitted in the cylinder bore 94 so as to be fluid tight and slidable in the axial direction, and a fluid chamber 98 is formed behind the fluid pressure control piston 96. Liquid chamber 98 is port 1
00 to the liquid passage 46 and port 1
It is connected to the liquid passage 47 by 06. An on-off valve 110 is provided between the port 100 and the liquid chamber 98. The on-off valve 110 is equipped with a valve 112, a valve seat 114, a spring 116, etc.
16 urges the valve seat 114 in the direction in which it is seated.

When the hydraulic control piston 96 is located at the retracted end, the projection 1 provided on the end surface of the control piston 96
20 separates the valve element 112 from the valve seat 114 against the elastic force of the spring 116, thereby connecting the liquid passage 46 and the liquid passage 47. When the hydraulic pressure control piston 96 moves slightly forward, the projection 120 separates from the valve element 112, the on-off valve 110 closes, and the liquid passage 46 and the liquid passage 47 are shut off.

On the other hand, a spline hole 130 is concentrically formed in the housing 92, and a nut 132 is fitted in a spline 134 formed on the outer peripheral surface thereof so as to be axially movable and non-rotatable. A ball screw 136 is screwed into the nut 132.

Hydraulic control piston 96 for ball screw 136
The end portion 140 on the side opposite to the side is supported by the housing 92 via bearings 142, 144 so as to be rotatable and immovable in the axial direction. Bearings 142 and 14 at this end 140
A gear 146 is attached to a portion between the gears 4 and 4 so as not to rotate relative to the gear 146, and is meshed with the pinion 148. A shaft portion 150 of the pinion 148 is connected via a clutch 152 to a DC servo motor (hereinafter, simply referred to as a motor) 1
It is connected to 60. The clutch 152 is the motor 16
This clutch allows the rotation of 0 in both forward and reverse directions to the pinion 148, but blocks the transmission of both forward and reverse rotations of the pinion 148 to the motor 160.

The ball screw 136 is rotated by the motor 160 via the gear 146 and the pinion 148, whereby the nut 132 is moved forward and backward. Further, when the nut 132 is advanced, the hydraulic pressure control piston 96 is also advanced by the action of the hydraulic pressure of the liquid chamber 98, and the on-off valve 110 is closed. After that, the volume of the liquid chamber 98 increases, the hydraulic pressure of the liquid chamber 98 is reduced, and the hydraulic pressure of the wheel cylinders 56, 58 is reduced.
In this case, the ball screw 136 is housed in the bottomed hole 162 formed in the hydraulic pressure control piston 96. Nut 1
When 32 is retracted, the hydraulic control piston 96 is also pushed by the end surface of the nut 132 and retracted. The volume of the liquid chamber 98 decreases and the liquid pressure in the liquid chamber 98 increases. When the hydraulic pressure control piston 96 reaches the backward end, the open / close valve 110 is opened.

Further, the stopper 164 formed of a disc spring provided at the opening of the cylinder bore 94 and the bearing 14
2 and the step portion 166, the retracting end and the advancing end of the nut 132 are defined by a disc spring and a stopper 168 composed of a washer, respectively.
When 32 contacts these stoppers 164 or 168, the rotation of the motor 160 is forcibly blocked.

The motor 160, as shown in FIG. 6, is an anti-skid control unit (hereinafter simply referred to as a unit).
Controlled by 170. The unit 170 is mainly composed of a computer having a CPU, a ROM, a RAM, an input unit, an output unit, and a bus connecting them, which are not shown. The left and right front wheels 5 are connected to the input section of the unit 170.
The output signals of the rotation speed sensors 172 and 174 detecting the rotation speeds of 2 and 36, the output signals of the rotation speed sensors 176 and 177 detecting the rotation speeds of the left and right rear wheels 38 and 54, and whether the brake pedal 14 is depressed. The detection result of the brake switch 179 for detecting whether or not it is supplied. Further, the ROM stores a program for calculating the estimated vehicle speed, slip ratio, etc., the programs shown in the flowcharts of FIGS. 1 to 4, the tables shown in FIGS.

At the output of the unit 170, the motor 160 is connected to the motor control circuit 1 via the motor control circuit 180.
Motors (not shown) are connected via 81. Based on the calculation result of the above program, the motor 160
Are controlled, and the slip ratios of the wheels 36, 38, 52, 54 are controlled to values as close to appropriate values as possible.

The motor control circuit 180, as shown in FIG. 7, includes a main circuit 182, a duty control circuit 184, a feedback circuit 186 and the like. Motor control circuit 1
Since 81 has the same structure as the motor control circuit 180,
Illustration and description are omitted. The main circuit 182 is a reverse circuit 192 having a MOS FET 188 for switching the current supply direction and a MOS FET 190 for controlling the amount of current in series.
And a normal rotation circuit 198 having a MOS FET 194 for switching the current supply direction and a MOS FET 196 for controlling the current amount in series. The reverse rotation circuit 192 and the forward rotation circuit 198 are closed circuits that include the DC power supply 200, the DC servo motor 160, and the resistor 202 in common.

The FET 188 of the reverse rotation circuit 192 has a high level (hereinafter referred to as unit 1) which is a signal obtained by amplifying the reverse rotation instruction signal LIN output from the unit 170 by an amplifier.
Direction 70 for outputting the reverse rotation command signal H-LIN), and a direction P for rotating the motor 160 in the reverse direction.
Allow current to flow through. Similarly, the FET 194 of the normal rotation circuit 198 conducts when the signal obtained by amplifying the normal rotation command signal RIN is at a high level (hereinafter, abbreviated as when the unit 170 outputs the normal rotation command signal H-RIN). However, the current is allowed to flow in the direction Q that rotates the motor 160 in the positive direction.

The duty control circuit 184 includes a differential amplifier 204, a PWM generation circuit 206, an AND circuit, an amplifier, etc., and the current value command signals RPWM, LPWM output from the unit 170 are generated by the differential amplifier 204, PWM. It is supplied to the MOS type FETs 190 and 196 for controlling the amount of current through the circuit 206, the AND circuit, the amplifier and the like. The current of the DC power supply 200 is the MOS type FET 19 for controlling the amount of current.
It is supplied to the motor 160 via 0 or 196, and its rotation speed is controlled.

Further, the feedback circuit 186 is provided with a detection circuit for detecting the voltage difference between both terminals of the resistor 202, a differential amplifier 208, etc., and the signal detected by the detection circuit is amplified by the differential amplifier 208. And is supplied as a feedback signal to the differential amplifier 204. The differential amplifier 204 outputs a signal according to the difference between the current value command signal RPWM or LPWM output from the unit 170 and the feedback signal to the PWM generation circuit 206.
Supply to. Therefore, the FETs 190 and 196 are supplied with the signals obtained by correcting the output signals RPWM and LPWM by the feedback signal.

The current value command signals RPWM and LPWM output from the unit 170, that is, the duty control ratio Dpw
m is calculated based on the table shown in FIG. As is apparent from the figure, when the slip state amount Ws is a value near 0, the duty control ratio Dpwm is 0, but if the slip state amount Ws is positive or negative and its absolute value becomes large, the duty control is performed. It can be seen that the ratio Dpwm is positive or negative and its absolute value is large. Here, the positive duty control ratio Dpwm indicates pressure increase control, and the negative duty control ratio Dpwm indicates pressure reduction control. In the case of negative, the sign is inverted and the signal is output as a positive signal. ing.

The slip state amount Ws in this embodiment is
As in the invention described in Japanese Patent Laid-Open No. 3-50059, it is obtained from the following equation and is determined by the slip amount of the wheel and the difference between the wheel acceleration and the estimated vehicle body acceleration. Ws = Ka * (Vw-Vs) + Kb * (Gw-Gs) where Vw is the wheel speed, Vs is the target wheel speed, Gw is the wheel acceleration, Gs is the estimated vehicle body acceleration, and Ka and Kb are constants and acceleration 1G. Is determined to correspond to a speed difference of 2 km / h. During braking, the estimated vehicle speed V is usually
Since so generally decreases linearly, estimated vehicle body acceleration Gs
Is a substantially constant negative value, and the value in the brackets of the second term is the wheel acceleration Gw plus a substantially constant value. Therefore, it can be considered that the slip state amount Ws is a value obtained by adding the wheel acceleration to the slip amount in the parentheses of the first term, and the change in the slip state amount with respect to time is substantially the same as that of the first term. However, it occurs earlier than the first term.

The fact that the slip state amount Ws is positive means that the slip amount or slip ratio (target wheel speed Vs
The sum of itself and the sign of its increase is small, which means that the brake cylinder pressure is insufficient.A negative value indicates that the sum is large and the brake cylinder pressure is large. Is too large. Further, in both positive and negative cases, if the absolute value of the slip state amount Ws is large, it is necessary to rapidly control the brake cylinder pressure to increase the changing speed. Further, the fact that the slip state amount Ws is positive and tends to increase indicates that the insufficient tendency of the brake cylinder pressure is increasing. Therefore, it is necessary to increase the pressure increase gradient and the tendency is to decrease. It is necessary to reduce the pressure increase gradient because it indicates that the tendency of insufficient brake cylinder pressure is decreasing. On the other hand, the fact that the slip state amount Ws is negative and the absolute value thereof tends to increase indicates that the excessive tendency of the brake cylinder pressure is increasing. Therefore, it is necessary to increase the pressure reduction gradient and the decreasing tendency. Since it means that the excessive tendency of the brake cylinder pressure is decreasing, it is necessary to reduce the pressure reduction gradient. That is, the slip state amount Ws is a brake cylinder pressure change required amount, and if the brake cylinder pressure can be controlled as required by the slip state amount Ws,
The braking performance can be improved.

Unit 1 in motor control circuit 180
The control of 70 is performed based on Table 1.

[0028]

[Table 1]

When the slip state amount Ws is positive and the absolute value is large, the pressure increasing mode is set. The unit 170 outputs the normal rotation command signal H-RIN, and at the same time, obtains the absolute value of the duty control ratio Dpwm obtained from the table of FIG. 8 (in this case, the value that has been obtained since it is originally a positive value). Output as current value command signal RPWM. As a result, a current is caused to flow in the direction of arrow Q by the forward rotation circuit 198, and the motor 160 is rotated in the forward direction at the rotation speed controlled by the FET 196. The hydraulic pressure control piston 96 is retracted to reduce the volume of the liquid chamber 98 and increase the hydraulic pressure of the wheel cylinders 56 and 58.

When the slip state amount Ws is positive, is decreasing, and reaches a threshold value Wsd, which will be described later, the pressure increase braking holding mode is set. The unit 170 outputs the reverse rotation command signal H-LIN and the current value command signal LPWM with a duty control ratio of 0% to perform dynamic braking and suppress the forward rotation of the motor 160. By setting the pressure-increasing braking holding mode, the motor 16
0 is disconnected from the power supply 200 to form a closed circuit 210. As a result, since the motor 160 acts as a generator, the back electromotive force of the closed circuit 210 causes a current to flow in the direction of arrow R. This direction R
Is the same as the direction P of the current that flows when the motor 160 is rotated in the reverse direction, and the energy generated is consumed in the closed circuit 210, and the rotation of the motor 160 is suppressed. In this way, by suppressing the rotation of the motor 160 in the forward direction, the pressure increase gradient of the wheel cylinders 56, 58 is made gentle. In other words, in order to make the pressure increase gradient gentle, even if the value of the current value command signal RPWM is made small, it is not possible immediately to make the once increased rotation speed due to the inertia of the motor 160, By suppressing the rotation, the rotation speed is reduced and the pressure increase gradient is made gentle.

When the slip state amount Ws is negative and the absolute value is large, the unit 170 outputs the reverse rotation command signal H-LIN and the absolute value (negative value) of the duty control ratio Dpwm based on the table of FIG. The value excluding the sign) is output as the current value command signal LPWM. As a result, a current in the direction of arrow P is caused to flow in the reverse rotation circuit 192, and the motor 160 is rotated in the reverse direction at the speed controlled by the FET 190. As a result, the hydraulic pressure control piston 96 is advanced and the hydraulic pressure in the wheel cylinders 56, 58 is reduced.

When the slip state amount Ws is negative and the slip state amount has changed from the decreasing tendency to the increasing tendency, the depressurization braking mode is set, and the voltage in the direction reverse to that before, that is, the direction of rotating in the positive direction, is the motor. Given to 160. The unit 170 has a forward rotation command signal H-RIN and a duty control ratio of 10
Outputs 0% current value command signal RPWM. As a result, the voltage is applied to the forward rotation circuit 198 in the direction of causing the current to flow in the direction of arrow Q, and the rotation of the motor 160 is suppressed.
That is, the depressurization gradient is relaxed.

After the set time has elapsed since the pressure reducing braking mode was set, the pressure reducing braking holding mode is set. The unit 170 outputs a normal rotation command signal H-RIN and a current value command signal RPWM with a duty control ratio of 0%. The closed circuit 210 is set by setting the pressure-reduction braking holding mode.
Is formed, and the rotation of the motor 160 is suppressed as described above.

The execution time of the pressure-reduction braking mode is set according to the time during which the motor 160 has been continuously rotating in the reverse direction until then, as shown in FIG. As is clear from the figure, when the decompression time is long and the motor 160 has reached the steady state, the decompression braking mode execution time is set to be long, and when the decompression time is short and the steady state has not been reached, it is short. Is set.

In the present embodiment, the pressure reduction braking mode is not switched to the pressure reduction braking holding mode after confirming that the motor 160 has stopped, but the rotation of the motor 160 is not stopped after the set time has elapsed. Also switches to the depressurization braking hold mode. If the set time is too long, the motor 160 may rotate in the forward direction, so the set time is set to be slightly shorter than the time required to stop the rotation of the motor 160.

When the anti-skid control is completed,
The control end mode is set. That is, this is a process of moving the hydraulic pressure control piston 96 to the backward end position. At this time, it is not necessary to control the speed, but the hydraulic pressure control piston 9
In order to reduce the collision of No. 6 with the stopper 164, the pressure increasing mode is set when the duty control ratio is 40%. After the completion of the anti-skid control termination processing, that is, after the control is terminated and the hydraulic pressure control piston 96 is returned to the backward end position, the non-control mode is set and the unit 1 is set.
No signal is output from 70.

In the hydraulic brake device constructed as described above, normally, when the brake pedal 14 is depressed, the pressurizing pistons 18 and 20 are advanced to generate hydraulic pressure in the pressurizing chambers 22 and 24. Then, the hydraulic pressure is transmitted as it is to the wheel cylinders 40, 42, 56, 58, and the rotation of the wheels is suppressed.

When the depression force of the brake pedal 14 becomes excessive due to the relationship with the friction coefficient of the road surface and the slip ratio of the wheels exceeds the proper range, antiskid control is performed. The unit 170 operates the hydraulic pressure control pistons of the hydraulic pressure control devices 88 and 90 by controlling the motor 160, and controls the brake cylinder pressure so that an appropriate slip ratio is obtained. The anti-skid control is performed independently for each of the hydraulic pressure control devices 88 and 90. The control in the hydraulic pressure control device 90 will be described below with reference to the flowcharts of FIGS. The description of the control performed by the hydraulic pressure control device 88 is the same as the control performed by the hydraulic pressure control device 90, and will therefore be omitted.

The main routine shown in the flowchart of FIG. 2 is repeatedly executed at all times. This main routine is a routine common to the hydraulic pressure control devices 88 and 90. First,
In step 1 (hereinafter abbreviated as S1; the same applies to other steps), initialization such as clearing each flag and counter provided in the RAM of the unit 170 is performed. In S2, the rotation speed sensors 172-
The output value Vw ** (**: FL, FR, RL, RR) of 177 is read and the estimated vehicle body speed Vso is calculated. Usually, it is assumed that the maximum wheel speed represents the vehicle body speed, and when the deceleration of the maximum wheel speed exceeds 1.2G, the vehicle speed is calculated by fixing the deceleration to 1.2G.

In S3, the equation Vs = Vso-Kso.ΔV
The target wheel speed Vs is determined from the estimated vehicle body acceleration Gs in S4 by the equation Gs = Kso (Vso (n) -Vso (n-1).
) / ΔT, and the wheel acceleration Gw is calculated by the equation Gw = Kw
It is calculated from (Vw (n) -Vw (n-1)) / ΔT. Here, Kso, ΔV, Kw, and Kso are constants, and subscripts n and n−1 are present calculated value and previous calculated value, respectively.

At S5, the appropriate ranges of the values Vso, Vs, Gw, and Gs stored in the ROM in advance are read,
In S6, these values Vs obtained in S2 to S4
The values o, Vs, Gw, and Gs are compared with the range read in S5 to determine whether or not the obtained value is valid. If it is determined to be abnormal, the abnormality flag is set in S7 and the driver is warned. In S8, the hydraulic pressure control piston 96 is moved to the retreat end, so that the pressurizing chamber 2 of the master cylinder 12 is moved.
4 and the wheel cylinders 56 and 58 are communicated with each other, the non-control mode is set, and the process returns to S2. If it is determined to be abnormal, the interrupt routine is not executed even if the interrupt signal is issued. If it is determined that there is no abnormality, the process directly returns to S2.

If an interrupt signal is issued during execution of the main routine, the interrupt routine shown in the flowchart of FIG. 3 is executed. The interrupt signal is issued, for example, every 5 ms, and is returned to the main routine every time one execution is completed. The hydraulic control device 90 includes a left front wheel 52 and a right rear wheel 5.
The slip ratio of No. 4 is controlled so as to be within an appropriate range. Here, the case where the left front wheel 52 is controlled will be described.

At S20, the slip state amount Ws is
From the wheel speed VwFL of the left front wheel 52, the target wheel speed Vs, the wheel acceleration GwFL, and the vehicle body acceleration Gs, the above expression Ws = Ka.
Calculated based on (VwFL-Vs) + Kb. (GwFL-Gs). In S21, it is determined whether the anti-skid control flag Fsta is 1 or not.

When this routine is executed first,
Since the anti-skid control flag Fsta is 0, NO
Therefore, it is determined in S22 and S23 whether the anti-skid control start condition is satisfied. The output signal of the brake switch 179 is read in S22, the output signal of the brake switch 179 is ON in S23, and the slip state amount Ws calculated in S20 is a negative value and its absolute value is the set value. It is determined whether or not it is larger. If the above conditions are satisfied, the anti-skid control is started, the anti-skid control flag Fsta is set to 1 in S24, and S
25 and thereafter are executed. If the above conditions are not satisfied, the anti-skid control is not started and the process is returned to the main routine as it is.

If anti-skid control is being performed and YES is determined in S21, it is determined in S26 and S27 whether the anti-skid control end condition is satisfied. In S26, the output signal of the brake switch 179 is read, and in S27, whether the output signal of the brake switch 179 is OFF or whether the estimated vehicle body speed Vso calculated in S2 is 5 km / h or less. It is judged. When at least one of the above two conditions is satisfied, S29 and the subsequent steps are executed, and the unkiskid control is ended. If neither condition is satisfied, the anti-skid control is continued, the end counter Tend is cleared in S28, and S25 and thereafter are executed.

As described above, the control of this routine is divided into the non-anti-skid control, the end of the anti-skid control, and the anti-skid control. First, the control at the end of the anti-skid control will be described. S29
At, the control end mode is set, and the hydraulic pressure control piston 96 is moved toward the backward end position. When the motor 160 is normally rotated, the nut 132
Is retracted, and the fluid pressure control piston 96 is retracted against the fluid pressure in the fluid chamber 98. In S30, the count value Tend of the end counter is incremented,
In S31, it is determined whether or not the count value Tend of the end counter is greater than or equal to the set count value Tend0.

When S31 is executed for the first time, the count value Tend of the end counter is 1, so NO is determined and the process is returned to the main routine. YES when the count value Tend of the end counter exceeds the set count value Tend0
If it is determined, the antiskid control flag Fsta is set to 0 in S32 and S33, and the count values of all counters such as the end counter, the pressure increase counter, and the pressure decrease counter are set to 0. In S34, the non-control mode is set, and the process returns to the main routine.

The set count value Tend0 is a count number required for the control piston 96 to move from the forward end position to the backward end position, and is a count number corresponding to 50 to 100 msec. When the count value Tend of the end counter reaches the set count value Tend0, the return to the backward end is guaranteed regardless of the position of the hydraulic pressure control piston 96 at the end of the control. At the end of control, since the hydraulic pressure control piston is normally in the middle of the forward end and the backward end, the hydraulic pressure control piston 96 reaches the backward end before the count value Tend of the end counter reaches the set count value Tend0, and the nut The contact of 132 with the stopper 164 forcibly stops the rotation of the motor 160. By returning the hydraulic pressure control piston 96 to the retracted end, the liquid passage 46
And the fluid passage 47 are communicated with each other to form a normal hydraulic brake.

Next, the control during the anti-skid control or at the start of the anti-skid control will be described.
In S25, the duty control ratio Dpwm is calculated from the table of FIG. 8 based on the slip state amount Ws, and S3
At 5, it is determined whether the duty control ratio Dpwm is negative. The duty control ratio Dpwm is negative and Y
If it is determined to be ES, the pressure reducing process is performed in S36, and it is 0 or more. If it is determined to be NO, S3 is performed.
In step 7, pressure increase processing is performed.

At the start of the anti-skid control, the slip state amount Ws is negative and the absolute value thereof is large, so the duty control ratio Dpwm becomes a negative value, so that a positive determination is made in S35, and a pressure reducing process is performed in S36. This depressurization process will be described based on the flowchart of FIG. In S50, it is determined whether the current slip state amount Ws (n) is larger than the previous slip state amount Ws (n-1) plus the set value Vup. Set value Vup is 0.5
It is a positive value of not more than km / h. Since the slip state quantity Ws changes due to vibration, etc., simply the slip state quantity Ws
If it is determined whether (n) is larger than the previous slip state amount Ws (n-1), the determination may be erroneous. In order to avoid this, the set value Vup is added. This slip state amount Ws (n) is the previous slip state amount Ws (n-
When it is smaller than 1) and tends to decrease, or is almost equal, it is determined to be NO, and the pressure reduction control is executed after S51. If the current slip state amount Ws (n) is larger than the previous slip state amount Ws (n-1) by the set value Vup or more and is in the increasing tendency, YES is determined, and the braking control is performed after S55.

At the start of the anti-skid control, the slip state quantity Ws is decreasing, the slip state quantity Ws (n-1) of the last time is 0, and the slip state quantity Ws (n) of this time is negative. . Therefore, the determination in S50 is NO, and S51
At the pressure reduction mode, the motor 160 is set to FE.
It is rotated in the opposite direction at the rotation speed controlled by T190. The nut 132 is advanced and the hydraulic pressure control piston 9
6 is advanced by the hydraulic pressure in the liquid chamber 98. On-off valve 1
10 is closed, and as the volume of the liquid chamber 98 increases,
The hydraulic pressure in the wheel cylinders 56, 58 is reduced.
The count value Tdwn of the pressure reduction counter is increased in S52, and the braking time Tstp is obtained from the count value of the pressure reduction counter Tdwn in S53 based on FIG.
In step S54, the pressure increase counter and the braking counter are cleared, and the process returns to the main routine.

Whether the slip state quantity Ws tends to decrease,
Alternatively, the determination in S50 is NO while the pressure reducing process is performed while there is no change, but the slip state amount Ws turns to an increasing tendency, and if YES is determined in S50, S50 is determined.
At 55, it is determined whether the count value Thld of the braking counter is larger than the value corresponding to the braking time Tstp.
When this step is first executed, the count value Thld of the braking counter is 0, so NO is determined,
In step S56, the pressure reducing braking mode is set, and a forward rotation voltage is applied to the motor 160 that was rotating in the reverse direction. In S57 and S58, the braking counter is incremented, the decompression counter is cleared, and the process returns to the main routine.

If the count value Thld of the braking counter reaches the value corresponding to the braking time Tstp, YE in S55.
It is determined to be S, and the depressurization braking holding mode is set in S59. As a result, the circuit 21 shown by the broken line in FIG.
0 is formed. By executing S56 to S58, the motor 1
When the motor 60 is stopped, the pressure reduction braking holding mode is set, so that the motor 160 is held in the holding state.
If the motor 160 is not stopped, it is stopped by the counter electromotive force, and thereafter, the motor 160 is kept in the holding state. S60
At, the braking counter is incremented and returned to the main routine.

Next, the duty control ratio Dpwm according to FIG.
When 0 is 0 or more and the pressure increasing process is performed in S37, it will be described based on the flowchart of FIG. In the normal anti-skid control, the depressurization process causes the slip state amount Ws to increase.
When the negative set value A is reached, the duty control ratio Dpwm becomes 0 or more and the pressure increasing process is started.

At S70, the current slip state amount W
It is determined whether s (n) is larger than the previous slip state amount Ws (n-1) plus the set value Vdwn. Set value V
dwn is a positive value of 0.5 km / h or less, and is a value added to avoid an erroneous determination due to a change in the slip state amount Ws due to vibration or the like, like the set value Vup in S50. When the current slip state amount Ws (n) is larger than the previous slip state amount Ws (n-1) by the set value Vdwn or more and is increasing, YES is determined, and S71 and the subsequent steps are executed. If the current slip state amount Ws (n) has become smaller than the previous slip state amount Ws (n-1) and has a decreasing tendency, or is approximately equal, it is determined as NO, and S76 and the subsequent steps are executed.

YES if S70 is executed for the first time
Then, the pressure increasing mode is set in S71.
The motor 160 is rotated in the forward direction, the nut 132 is retracted, and the hydraulic pressure control piston 96 is retracted against the hydraulic pressure in the hydraulic chamber 98. The volume of the liquid chamber 98 is reduced, and the hydraulic pressure in the wheel cylinders 56, 58 is increased. As described above, the pressure increasing process is performed after the pressure reducing process. However, since the rotation of the motor 160 is suppressed at the end of the pressure reducing process in S36,
When the pressure-reduction braking holding mode is switched to the pressure-increasing mode in S71, the motor 160 quickly and always starts rotating in the forward direction with the same tendency. Next, S72 and S73
At, the count value Tup of the pressure increase counter is increased and the count value Tdwn of the pressure decrease counter is cleared.
Thereafter, in S74, the current slip state amount Ws is set as the maximum slip state amount Wsp, and in S75, the threshold value Wsd is obtained by multiplying the maximum slip state amount Wsp by the coefficient Kd, and the process is returned to the main routine. In this embodiment, the coefficient Kd is 0.4.

While the slip state quantity Ws is increasing,
The current slip state quantity is the maximum slip state quantity Wsp
And the threshold value Wsd is sequentially obtained. Therefore,
The threshold value Wsd increases as the slip state amount Ws increases. On the other hand, if the maximum slip state amount Wsp is large, the rotation speed of the motor 160 in the forward direction is also increased, so the threshold value Wsd is set to a larger value as the maximum rotation speed of the motor 160, that is, the inertia is larger. .

If the slip state quantity Ws changes from an increasing tendency to a decreasing tendency, it is determined as NO in S70 and S76.
At, it is determined whether the current slip state amount Ws is larger than the threshold value Wsd obtained in S75 last time. Here, the threshold value Wsd is set to 40% of the maximum value Wsp of the slip state amount Ws. If S76 is executed first, it is determined as YES and S77, S
At 78, the pressure increasing mode is continuously set, and the count value Tup of the pressure increasing counter is increased.

If the slip state amount Ws becomes equal to or less than the threshold value Wsd and NO is determined in S76, the pressure increase braking holding mode is set in S79. Unit 170
Outputs only the signal H-LIN, and neither the voltage for rotating in the forward direction nor the voltage for rotating in the reverse direction is applied to the motor 160, and the closed circuit 210 is formed. Since the motor 160 acts as a generator, rotation of the motor 160 is suppressed by dynamic braking. Then, in S80, the count value Tup of the pressure increase counter is increased.

The fact that the slip state amount Ws has become equal to or less than the threshold value Wsd means that it is necessary to stop the forward rotation of the motor 160 or to start the reverse rotation of the motor 160 in the near future. In the present embodiment, when the slip state amount Ws becomes equal to or less than the threshold value Wsd, the rotation of the motor 160 is suppressed and the pressure increase gradient is positively relaxed.

On the other hand, when the duty control ratio Dpwm is 0%, NO is determined in S35 and the pressure increasing mode is set. In that case, the current value command signal RPWM with the duty control ratio 0% is set. Since it is output, the motor 160
Will be held. In this embodiment, the case where the duty control ratio is 0% is also included in the pressure increasing mode.

An example of actual control will be described below with reference to FIG. At time t ₀ , the anti-skid control is started and the pressure reducing mode is set. Slip state amount W
When s changes from a decreasing tendency to an increasing tendency (time t ₁ ), the pressure reducing mode is switched to the pressure reducing braking mode, and after the set time Tstp elapses, the pressure reducing braking holding mode is switched. Next, when the slip state amount becomes equal to or greater than the negative set value A (time t ₂ ), the pressure increasing mode is set. Since the slip state amount Ws tends to increase, the slip state amount Ws is sequentially set as the maximum slip state amount Wsp, the threshold value Wsd is sequentially obtained, and 40% of the maximum value Wsp1 is set as the threshold value Wsd1. Turned to the slip state quantity Ws is decreasing, when the slip state quantity Ws is reduced to the threshold Wsd1 (time t _3), it is switched to increase pressure braking holding mode. Furthermore, reduced slip state quantity Ws is equal to or less than a negative set value A (time t _4), is switched to vacuum mode.

That is, the forward rotation of the motor 160 is suppressed at time t ₃ , and then the motor 160 is controlled so as to rotate in the reverse direction at time t ₄ . The pressure increase gradient is made gentle from time t ₃ , and the motor 160 is rotated in the opposite direction at time t ₄ . Since the rotation of the motor 160 is sufficiently suppressed from the time t ₃ to the time t ₄ , the motor 160 can be quickly rotated in the reverse direction.

Hereinafter, similar control is performed, but
Although 10 is switched to the pressure-increase dynamic hold mode from the pressure increasing mode at the time t _6, as in the vicinity of the time t _7, when the slip state quantity Ws does not become less negative set value A is switched to vacuum mode Instead, the mode is switched to the pressure increasing mode again. Even in that case, since the rotation of the motor 160 is suppressed, the motor 160 can be quickly rotated in the forward direction. Further, even when the slip state amount Ws is decreasing, as in the vicinity of time t ₉ , if the threshold value Wsd is not exceeded, the pressure increasing braking holding mode cannot be switched to.

As described above, when the slip state amount Ws is decreasing and the threshold value Wsd is reached, the pressure increasing mode is switched to the pressure increasing braking holding mode, so that the motor 160 is rotated in the forward direction. The deceleration delay can be reduced. Therefore, the pressure increase gradient can be made gentle and excessive pressure increase can be favorably avoided. Further, since the magnitude of the threshold value Wsd is determined based on the magnitude of the maximum value Wsp, the maximum value Wsp is large,
It increases as the maximum rotation speed of the motor 160 increases.
Therefore, the rotation of the motor 160 can be favorably suppressed according to the inertia. Furthermore, after that, the decompression mode,
Whichever pressure boost mode is selected, the motor 160 can be made to respond quickly to the next control command. Since the hydraulic pressure waveform faithfully following the control command is obtained, the effect of improving the control accuracy of the brake hydraulic pressure, that is, the antiskid control accuracy is obtained.

In the above embodiment, when the pressure-increasing braking holding mode is set, the motor 160 is rotated by maintaining the non-applied state in which neither the voltage for rotating the motor 160 in the forward direction nor the voltage for rotating in the reverse direction is applied. However, the rotation may be suppressed by applying a voltage for rotating the motor 160 in the opposite direction.

In the above embodiment, the threshold value W
Although the value of the coefficient Kd for obtaining sd is always 0.4, it is not limited to this value and may be another value. Further, it is not always constant, but the maximum value of the slip state amount Ws and the count value Tup of the pressure increasing counter are increased.
Of the slip state amount Ws, the gradient of change of the slip state amount Ws, and the like may be taken into consideration.

Although not specifically exemplified, the present invention can be carried out in various modified and improved modes based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief description of drawings]

FIG. 1 is a flowchart showing a pressure increase processing subroutine stored in a unit of an anti-skid control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a main program stored in the unit.

FIG. 3 is a flowchart showing an interrupt routine of a main program stored in the unit.

FIG. 4 is a flowchart showing a pressure reduction processing subroutine stored in the unit.

FIG. 5 is an overall view of the anti-skid control device of the above embodiment.

FIG. 6 is a cross-sectional view of the hydraulic control device of the above embodiment.

FIG. 7 is a circuit diagram of a motor drive circuit of the above embodiment.

FIG. 8 is a graph showing a relationship between a slip state amount and a duty control ratio stored in the unit.

FIG. 9 is a graph showing the relationship between the count value of the decompression counter stored in the unit and the braking time.

FIG. 10 is a graph showing a control example of the anti-skid control device of the above embodiment.

FIG. 11 is a block diagram conceptually showing the structure of the present invention.

[Explanation of symbols]

 10 master cylinder 30, 31, 46, 47 liquid passage 36, 38, 52, 54 wheel 40, 42, 56, 58 wheel cylinder 88, 90 hydraulic control device 96 hydraulic control piston 160 motor (DC servomotor) 170 anti Skid control unit 180 Motor control circuit 188, 190, 194, 196 FET 200 Power supply 204 PWM generation circuit

Claims (1)

[Claims] 1. An electric motor that can rotate in both forward and reverse directions, a movable member that is moved backward and forward by rotation of the electric motor in forward and reverse directions, and a volume that is reduced by moving the movable member backward and forward. A hydraulic chamber that is increased and communicates with a brake cylinder that suppresses wheel rotation, and the electric motor is rotated in the forward direction to increase the hydraulic pressure in the brake cylinder, or is rotated in the reverse direction to brake. In an anti-skid control device including a motor control device that reduces the hydraulic pressure of a cylinder, in the motor control device, the electric motor is rotating in the forward direction, and the slip state amount is from its maximum value. Rotation suppressing means for electrically suppressing the rotation of the electric motor when the product of the maximum value and a predetermined coefficient is reduced is provided. Anti-skid control apparatus according to claim and.