JPH0672311A - Anti-skid controller - Google Patents

Abstract

PURPOSE:To make the change of liquid pressure slow by braking electrically each motor by impressing opposite-directioned voltage at the finish time of the forward/backward rotation of each motor to increase/decrease brake cylinder liquid pressure, then conducting the maintenance of a state in which voltage of either forward or backward direction is not impressed. CONSTITUTION:In the case of a master cylinder 10 connected to a brake pedal 14 through a vacuum booster 12, both pressurization chambers 22, 24 are connected respectively to respective right and left and front and rear vehicle wheels 36, 38, 52, 54 through respective liquid pressure controllers 88, 90 or the like. The respective motors of the respective liquid pressure controllers 88, 90 are respectively controlled by means of an anti-skid control unit 170 through a motor control circuit 180 on the basis of respective detection signals from respective vehicle wheel rotary speed sensors 172, 174, 176, 177 and a brake switch 179 or the like. In this instance, at the finish time of the forward/backward rotation of each motor, each motor is braked electrically by impressing opposite- directioned voltage. Afterwards, the maintenance of a non-impression state in which voltage of neither forward nor backward direction is impressed, is conducted.

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 anti-skid control device having an electric motor has been known. For example, Japanese Patent Laid-Open No. 4-1
Japanese Patent No. 66463 discloses (a) an electric motor that is rotatable in both forward and reverse directions, (b) a movable member that is moved forward and backward by rotation of the electric motor in forward and reverse directions, respectively, and (c). The volume is increased and decreased by moving the movable member forward and backward, respectively, and the fluid chamber communicates with a brake cylinder that suppresses wheel rotation; and (d) the electric motor is rotated in the forward direction to brake the cylinder. And a motor control device for increasing the hydraulic pressure of the brake cylinder by rotating in the opposite direction to increase the hydraulic pressure of the brake cylinder, and an anti-skid control device for controlling the slip ratio of the wheel within a set range is described. There is.

[0003]

However, in the anti-skid control device described in the above publication, when the hydraulic pressure of the brake cylinder is changed from the decrease to the increase, the rotation direction of the electric motor is changed from the normal direction to the reverse direction. It was switched to the direction. Therefore, as shown in FIG. 10, there is a problem that the brake cylinder hydraulic pressure changes rapidly. Also,
Therefore, there is a problem that the brake cylinder pressure is in a hunting state.

Against the background of the above circumstances, the present invention has been made in order to avoid a sudden change in the hydraulic pressure of the brake cylinder.

[0005]

The gist of the invention according to claim 1 of the present application is: (a) an electric motor, (b) a movable member, (c) a liquid chamber, and (d) a motor control device. In the anti-skid control device equipped with, a voltage for driving the electric motor is applied to the motor control device in the opposite direction to that at the end of at least one of the forward rotation and the reverse rotation of the electric motor. Anti-phase braking means for electrically braking the electric motor with the electric motor, and neither the voltage for driving the electric motor in the forward direction nor the voltage for driving in the reverse direction is applied after the operation of the anti-phase braking means is terminated. The state maintaining means is provided.

Further, the gist of the invention according to claim 2 is the anti-skid control provided with the (a) electric motor, (b) movable member, (c) liquid chamber, and (d) motor control device. In the device, the motor control device is provided with a dynamic braking circuit that forms a closed circuit including the electric motor and the load device to brake the electric motor.

[0007]

In the anti-skid control device according to claim 1, the negative-phase braking means causes the electric motor to rotate in the opposite direction to that at the end of at least one of the forward rotation and the reverse rotation of the electric motor. When the driving voltage is applied, the rotation of the electric motor is suppressed. After the operation of the anti-phase braking means is completed, the non-application state maintaining means maintains the non-application state in which neither the voltage for driving the electric motor in the forward direction nor the voltage for driving in the reverse direction is applied, so that the rotation of the electric motor is suppressed. And kept in a held state. That is, if the electric motor is stopped by the anti-phase braking means, the non-application state maintaining means keeps the electric motor in the holding state. Further, even if the electric motor is rotating after the operation by the anti-phase braking means is finished, the electric motor is stopped by the non-application state maintaining means,
After that, the holding state is maintained.

In the anti-skid control device according to the present invention, when the dynamic braking circuit including the electric motor and the load device is closed, the electric motor acts as a generator and the energy generated by the electric power is consumed by the load device. Therefore, the rotation of the electric motor is suppressed. If the electric motor is stopped, then it is kept in the holding state.

[0009]

As described above, according to the antiskid control device of the first aspect, when the rotation direction of the electric motor is switched, the rotation is suppressed and the holding state is maintained, so that the change of the brake cylinder pressure is moderate. Therefore, hunting can be avoided.

Further, if the electric motor is kept in a state of being restrained and held at the end of either the forward rotation or the backward rotation of the electric motor, then the pressure reducing mode, the pressure increasing mode, and the holding mode are set. Whichever is selected, the electric motor can be quickly made to respond to the next control command. Therefore, a hydraulic pressure waveform that faithfully follows the control command can be obtained, which has the effect of improving the brake hydraulic pressure control accuracy, that is, the antiskid control accuracy.

According to the second aspect of the present invention, the rotation of the electric motor can be suppressed well by closing the dynamic braking circuit. In addition, therefore, the change in the brake cylinder pressure can be moderated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case in which an antiskid control device, which is an embodiment common to the inventions described in claims 1 and 2, is mounted on a vehicle will be described in detail below with reference to the drawings. In FIG. 4, 10 is a master cylinder, and this master cylinder 10
Vacuum booster (hereinafter referred to simply as booster) 1
The brake pedal 14 is connected via 2. 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. Reference numeral 26 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, 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. 5, 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 pressure control piston 96 is located at the retracted end, the projection 1 provided on the end face 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. The shaft 150 of the pinion 148 is connected to the DC servomotor 160 via a clutch 152. The clutch 152 is a clutch that allows transmission of rotation of the DC servomotor 160 in both forward and reverse directions to the shaft portion 150, but blocks transmission of rotation of the shaft portion 150 in both forward and reverse directions to the DC servomotor 160. is there.

The ball screw 136 is rotated by the DC servomotor 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. afterwards,
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. When the nut 132 is retracted, the hydraulic pressure 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 of the liquid chamber 140 increases. When the hydraulic pressure control piston 96 reaches the backward end, the open / close valve 110 is opened.

The stopper 164 formed of a disc spring provided in the opening of the cylinder bore 94 and the bearing 14
2 and the step portion 166, a retracting end and an advancing end of the nut 132 are defined by a stopper 168 composed of a disc spring and a washer. The nut 132 contacts the stopper 164 or 168. If they come into contact, the rotation of the DC servo motor 160 is forcibly blocked.

The DC servomotor 160 is controlled by an anti-skid control unit (hereinafter simply referred to as a unit) 170, as shown in FIG. 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. In the input section of the unit 170,
Output signals from rotation speed sensors 172 and 174 for detecting the rotation speeds of the left and right front wheels 52 and 36, the left and right rear wheels 38,
Rotation speed sensors 176 and 17 for detecting the rotation speed of 54
7 and the detection result of the brake switch 179 for detecting whether or not the brake pedal 14 is depressed. 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 3, the tables shown in FIGS.

A DC servo motor 160 is connected to an output section of the unit 170 via a motor control circuit 180, and a DC servo motor (not shown) is connected to the output section of the unit 170 via a motor control circuit 181. Based on the calculation result of the above program, the solenoid opening / closing valve 80 and the DC servo 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.

As shown in FIG. 6, the motor control circuit 180 comprises 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 circuit for forward rotation 192 having a MOS type FET 188 for switching the current supply direction and a MOS type FET 190 for controlling the amount of current in series.
And a reversing 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 forward rotation circuit 192 and the reverse rotation circuit 198 are closed circuits that include the DC power supply 200, the DC servo motor 160, and the resistor 202 in common.

In the FET 188 of the normal rotation circuit 192, the signal obtained by amplifying the normal rotation command signal RIN output from the unit 170 by the amplifier is at a high level (hereinafter referred to as unit 1).
When 70 is abbreviated to output the forward rotation command signal H-RIN), it conducts and allows a current to flow in the direction P for rotating the DC servomotor 160 in the forward direction. Similarly, in the FET 194 of the reverse rotation circuit 198, the signal obtained by amplifying the reverse rotation instruction signal LIN is at a high level (hereinafter, referred to as unit 1).
When 70 outputs the reverse rotation command signal H-LIN (abbreviated as "when output"), it conducts and allows a current to flow in the direction Q for rotating the DC servomotor 160 in the reverse 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 DC servo motor 160 via 0 or 196, and its rotation speed is controlled.

Further, the feedback circuit 186 includes a detection circuit for detecting a voltage difference between both terminals of the resistor 202, a differential amplifier 208, etc., and a 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, LPWM output from the unit 170, that is, the duty control ratio Dpwm
Is calculated based on the table shown in FIG.
As is clear from FIG. 7, 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 The control ratio Dpwm is positive or negative, and its absolute value is large. Here, positive duty control ratio Dpwm indicates pressure increase control, and negative duty control ratio indicates pressure reduction control. When the duty control ratio Dpwm is negative, the sign is inverted and a positive signal is output.

The slip state quantity Ws is calculated according to Japanese Patent Laid-Open No. 3-500.
As described in detail in Japanese Patent Publication No. 59, 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. As shown in FIG. 9, the estimated vehicle body speed Vso generally decreases linearly during braking, and therefore the estimated vehicle body acceleration Gs has a substantially constant negative value. In brackets of the second term, a substantially constant value is added to the wheel acceleration Gw. It will be a large size.
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 in the first term, and changes in the slip state amount Ws with respect to time are almost the same as those in the first term. Same, but occurs earlier than the change in the first term.

The fact that the slip state quantity Ws is positive means that the wheel speed is higher than the target wheel speed and the brake cylinder pressure is insufficient, and the fact that it is negative means that slip has occurred. , Indicates that the brake cylinder pressure is excessive. Further, in both positive and negative cases, if the absolute value of the slip state amount Ws is large, it is necessary to control the brake cylinder pressure immediately, and it is necessary to increase the changing speed thereof. That is, the slip state amount Ws is the brake cylinder pressure change required amount.

The motor control circuit 1 configured as described above
The control of the unit 170 in 80 will be described based on Table 1.

[0030]

[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 reverse rotation command signal H-LIN, and the current value command signal based on the table of FIG. Outputs LPWM. As a result, current is caused to flow in the direction of arrow Q by the reverse rotation circuit 198, and the DC servomotor 160 is rotated in the reverse 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 near 0,
Hold mode is set. Since the holding mode is the same as the case where the duty control ratio Dpwm in the pressure increasing mode is 0%, the unit 170 outputs only the reverse rotation command signal H-LIN. As a result, the closed circuit 210 shown by the broken line is formed, the DC motor 160 is disconnected from the power source 200, and the voltage for rotating in the forward direction and the voltage for rotating in the reverse direction are not applied.

When the slip state amount Ws is negative and the absolute value is large, the pressure reducing mode is set, the unit 170 outputs the forward rotation command signal H-RIN, and the current value command signal based on the table of FIG. Outputs RPWM. As a result, a current in the direction of arrow P is caused to flow in the forward rotation circuit 192, and the DC servomotor 160 moves in the forward direction to the FET 19.
It is rotated at a speed controlled to zero. As a result, the hydraulic pressure control piston 96 is advanced and the hydraulic pressure in the wheel cylinders 56, 58 is reduced.

When it becomes necessary to stop the forward rotation of the DC servo motor 160, the braking mode is set,
A voltage for rotating the DC servo motor 160 in the reverse direction is applied to perform anti-phase braking. At this time, it is not necessary to control the rotation speed, and it suffices to stop the rotation of the motor 160 promptly.
LIN is output and the duty control ratio Dpwm 10
Outputs 0% current value command signal LPWM. As a result, in the reverse rotation circuit 198, a voltage is applied in the direction of flowing the current in the direction of arrow Q, and the rotation of the DC servomotor 160 is strongly suppressed.

After the set time has elapsed since the braking mode was set, the braking holding mode is switched to. The braking holding mode in this case is executed by the output of the reverse rotation command signal H-LIN signal and the current value command signal LPWM with the duty control ratio Dpwm of 0%. If the motor 160 is stopped within the set time, the holding state is maintained by switching to the brake holding mode, but it is switched to the brake holding mode even if the motor 160 is not stopped within the set time. By this, dynamic braking is performed and the motor 16
The rotation of 0 is suppressed. The motor 160 has a closed circuit 210
When it is formed, the closed circuit 21
At 0, a counter electromotive force is generated in a direction in which a current flows in the direction of arrow R. This direction R is the same as the direction Q of the current that flows when the DC servo motor 160 is rotated in the opposite direction, and the energy generated is consumed in the closed circuit 210, and the rotation of the DC servo motor 160 is promptly stopped. To be However, the suppression in this case is slower than in the case of the above-described anti-phase braking. The closed circuit 210 is the dynamic braking circuit according to claim 2.

As shown in FIG. 8, the execution time of the anti-phase braking is set according to the time during which the DC servo motor 160 has continuously rotated in the forward direction. As is clear from the figure, when the decompression time is long and the DC servo motor 160 has reached the steady state, the anti-phase braking time is set long, and when the decompression time is short and the steady state has not been reached, it is set short. It In the present embodiment, instead of switching the braking mode to the braking holding mode after confirming that the DC servo motor 160 has stopped, the DC servo motor 16 is set after the set time has elapsed after the braking mode was set.
Even if 0 is not stopped, the braking holding mode is switched to. If the set time is too long, the DC servo motor 16
Since 0 may rotate in the opposite direction, the antiphase braking time is set to be slightly shorter than the time required to stop the rotation of the DC servomotor 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 and the pressurizing chamber 2 is moved forward.
A hydraulic pressure is generated in 2 and 24, and the hydraulic pressure is transmitted to the wheel cylinders 40, 42, 56 and 58 as it is, 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 appropriate range, antiskid control is performed. The unit 170 operates the hydraulic pressure control pistons 96 of the hydraulic pressure control devices 88 and 90 by controlling the DC servomotor 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, 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 172-1
The output value Vw ** (**: FL, FR, RL, RR) of 77 is read and the estimated vehicle 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.

In S5, the values Vso, Vs, Gw, and Gs stored in advance in the ROM are read, and in S6, these values Vso, Vs, and G obtained in S2 to S4 are read.
w, Gs and the value read in S5 are compared,
It is determined whether these values are valid. If it is determined to be abnormal, the abnormality flag is set in S7 and the driver is warned. In S8,
By moving the hydraulic pressure control piston 96 to the backward end, the pressurizing chamber 24 of the master cylinder 12 and the wheel cylinders 56, 58 are made to communicate 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 it is determined in S21 that the anti-skid control is being performed, it is determined in S22 and 23 whether or not the anti-skid control should be ended. The output signal of the brake switch 179 is read in S22, and the brake switch 1 is read in S23.
It is determined whether the output signal of 79 is OFF, or whether the estimated vehicle body speed Vso calculated in S2 is 5 km / h or less. If at least one of the above two conditions is satisfied, it is determined that the unkiskid control should be ended, and S24 and subsequent steps are executed. If neither condition is satisfied, it is determined that the anti-skid control should be continued, the end counter Tend is cleared in S30, and S34 and the subsequent steps are executed.

When it is determined in S21 that the anti-skid control is not being performed, it is determined in S31 and 32 whether or not the anti-skid control should be started. S3
In 1, the output signal of the brake switch 179 is read, in S32, the output signal of the brake switch 179 is ON, 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, it is determined that the anti-skid control should be started, the anti-skid control flag Fsta is set to 1 in S33, and S34 and subsequent steps are executed. If it is not satisfied, it is not necessary to start anti-skid control.
It is returned to the main routine as it is.

The control of this routine is divided into the non-anti-skid control, the anti-skid control end, and the anti-skid control. The control at the end of the anti-skid control will be described first. In S24, the control end mode is set, and the hydraulic pressure control piston 96 is moved toward the backward end position. DC servo motor 1
When the nut 60 is rotated in the reverse 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 end counter Tend is counted up in S25, and the count value Tend of the end counter is set in S26.
It is determined whether d0 or more.

When S26 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 S27 and S28, and all counters such as the end counter and the pressure increase counter are cleared.
In S29, the non-control mode is set, and the process returns to the main routine. By returning the hydraulic pressure control piston 96 to the retracted end, the hydraulic passage 46 and the hydraulic passage 47 are made to communicate with each other, and a normal hydraulic brake is realized.

The set count value Tend0 is a count number required for the hydraulic pressure 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 96 is normally located between 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. ,
The nut 132 comes into contact with the stopper 164 to forcibly stop the rotation of the DC servomotor 160.

Next, the control during the anti-skid control or at the start of the anti-skid control will be described.
In S34, the duty control ratio Dpwm is obtained based on the table of FIG. 7, and in S35, it is determined whether the duty control ratio Dpwm is negative. When the duty control ratio Dpwm is negative and it is determined to be YES, the pressure reducing process is performed in S36 and is 0 or more,
If NO is determined, the pressure increasing / holding process is performed after S37.

At the start of normal anti-skid control, the pressure reducing process is first performed. Here, the pressure increasing / holding process will be described first. In S37, the unit 170 outputs the reverse rotation command signal H-LIN and also outputs the current value command signal LPWM based on the duty control ratio Dpwm obtained from FIG. Duty control ratio D
When pwm is 0%, the holding mode is set, and when it is positive, the pressure increasing mode is set. When the pressure boosting mode is set, the DC servo motor 160 is rotated in reverse at the speed controlled by the FET 196, and the nut 132 is moved backward.
The hydraulic pressure control piston 96 is retracted against the hydraulic pressure in the liquid chamber 98. The volume of the liquid chamber 98 is reduced and the hydraulic pressure in the wheel cylinders 56, 58 is increased. Next, the pressure increase counter Tup is incremented in S38, and S39
At, the decompression counter and the braking holding counter are cleared and the process returns to the main routine.

Next, the depressurization control subroutine is shown in FIG.
It will be described based on. 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. The set value Vup is a positive value of 0.5 km / h or less. Since the slip state amount Ws changes due to vibration or the like, if the slip state amount Ws (n) is simply determined to be 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. If the current slip state amount Ws (n) is smaller than the previous slip state amount Ws (n-1) and is decreasing, or is approximately equal, it is determined to be NO and the pressure reduction control is executed after S51. . This slip state quantity W
When s (n) is larger than the previous slip state amount Ws (n-1) by the set value Vup or more and is increasing, YES is determined,
After S55, braking control is performed.

When the anti-skid control is started, the slip state amount Ws is decreasing, but initially the previous slip state amount Ws (n-1) is 0, and this slip state amount Ws (n ) Is negative. Therefore, the determination of S50 is NO, the depressurization mode is set in S51, and the DC servomotor 160 is rotated in the forward direction at the rotation speed controlled by the FET 190. The nut 132 is advanced, and the fluid pressure control piston 96 is advanced by the fluid pressure in the fluid chamber 98. The on-off valve 110 is closed and the liquid chamber 98
The hydraulic pressure in the wheel cylinders 56, 58 is reduced as the volume of the cylinders increases. Decompression counter T in S52
dwn is counted up, and in S53, the braking time T is calculated from the count value of the pressure reduction counter Tdwn based on FIG.
stp is required. In step S54, the pressure increase counter and the brake holding counter are cleared and the process returns to the main routine.

Whether the slip state amount 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 judged if the count value Thld of the braking holding 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 holding counter is 0, so it is determined to be NO, the braking mode is set in S56, and the DC servomotor 160 rotating in the forward direction is reversed. Directional rotation voltage is applied. In S57 and S58, the braking holding counter is counted up, the decompression counter is cleared, and the process is returned to the main routine.

If the count value Thld of the braking holding counter reaches the value corresponding to the braking time Tstp, YES is determined in S55 and the braking holding mode is set in S59. As a result, the circuit 210 shown by the broken line is formed. The DC servo motor 16 is executed by executing S56 to S58.
When 0 is stopped, the DC servomotor 160 is held in the holding state by setting the braking holding mode. If the DC servomotor 160 is not stopped,
It is stopped by the counter electromotive force, and then kept in the holding state. In S60, the braking holding counter is incremented and returned to the main routine.

As described above, when the rotation of the DC servo motor 160 is completed and the rotation of the motor 160 is suppressed and kept in the holding state, any one of the pressure reducing mode, the pressure increasing mode and the holding mode is selected thereafter. However, the DC servo motor 160 can be promptly responded 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.

Further, in the conventional anti-skid control device, since the rotation of the DC servomotor is switched from the forward direction to the reverse direction at the time of switching from the pressure reducing control to the pressure increasing control, the hydraulic pressure changes rapidly and hunting occurs. However, in the present embodiment, since the DC servomotor 160 is braked and held when the pressure is reduced and then increased, the change in the hydraulic pressure becomes gentle.
It is possible to favorably avoid the occurrence of hunting.

Further, in the conventional anti-skid control device, there is a problem that the brake cylinder pressure is excessively decreased and the braking distance becomes long because the DC servo motor is excessively rotated by the inertia. Indicates that the rotation of the DC servo motor 160 is suppressed when the slip state amount Ws that changes earlier than the slip amount changes from a decreasing tendency to an increasing tendency. Therefore, excessive decompression due to excessive rotation due to inertia of the DC servo motor 160 is caused. It can be avoided satisfactorily, and the effect of improving the accuracy of anti-skid control can also be obtained.

As is clear from the above description, in the present embodiment, the motor control device is constituted by the anti-skid control unit 170 and the motor control circuit 180, and S56 in the depressurization processing subroutine of the anti-skid control unit 170 is executed. The portion constitutes the anti-phase braking means, and the portion executing S59 constitutes the non-application state maintaining means.

In the above embodiment, the braking is performed when the direction of rotation of the DC servo motor 160, which has been rotating in the forward direction for pressure reduction, is reversed, but it is rotated in the reverse direction. It is also possible to perform braking when the rotation direction of the DC servo motor 160 which has been performed is reversed, or to perform braking both in the forward direction to the reverse direction and in the reverse direction to the forward direction.

Further, in the above embodiment, the time point at which the pressure reducing mode is switched to the braking mode is determined based on the slip state amount Ws, but the slip state amount Ws is set.
It is also possible to decide based on the slip amount or the like.

Further, in the above embodiment, the duty control ratio Dpwm of FIG. 7 may be corrected based on the count value Tup of the pressure increasing counter. The fact that the count value of the pressure increase counter Tup is large means that the slip state amount does not easily decrease even if the brake cylinder pressure is increased. For example, the case where the low μ road is changed to the high μ road is considered. To be In that case, the recovery of the slip ratio is promoted by further increasing the duty control ratio Dpwm. Further, similarly, the duty control ratio Dpwm in FIG. 7 may be corrected based on the count value of the decompression counter.

In the above embodiment, the voltage in the opposite direction is applied to the electric motor for the set time, but the voltage may be applied until the electric motor stops. It is not essential to switch to braking hold mode after braking mode.

Further, in the anti-skid control device in the above embodiment, the pressure reducing mode is switched to the braking mode and then to the braking holding mode, but it is also possible to switch from the pressure reducing mode to the braking holding mode. Aspect is an embodiment of the invention described in claim 2.

In this case, for example, in S50,
When it is determined that the slip state amount Ws has a decreasing tendency or does not substantially change, the pressure reducing mode is set, and when it is determined that the slip state amount Ws has changed to an increasing tendency, the braking holding mode is set. When the braking holding mode is set, a closed circuit (power generation braking circuit) 210 is formed, the DC servomotor 160 acts as a generator, and the energy generated by the power generation is consumed in the closed circuit 210. Since a current in the opposite direction R flows through the closed circuit 210 due to the back electromotive force, the DC servo motor 16
0 is stopped immediately. As described above, the rotation of the motor 160 can be suppressed by setting the braking holding mode without applying the voltage for rotating the DC servo motor 160 in the opposite direction. Also, the motor 1
Even after the rotation of 60 is stopped, the holding state can be maintained without switching the mode.

Although not specifically exemplified, the present invention can be carried out in variously 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 depressurization processing subroutine stored in a unit of an anti-skid control device according to an embodiment of claims 1 and 2 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 an overall view of the anti-skid control device of the above embodiment.

FIG. 5 is a cross-sectional view of the hydraulic control device of the above embodiment.

FIG. 6 is a circuit diagram of a motor drive circuit of the above embodiment.

FIG. 7 is a table showing a relationship between a slip state amount and a duty control ratio stored in the unit of the above embodiment.

FIG. 8 is a table showing the relationship between the count value of the decompression counter and the control time stored in the unit.

FIG. 9 is a graph showing changes in wheel speed, target wheel speed, and estimated vehicle body speed in a conventional anti-skid control device.

FIG. 10 is a graph showing a change in brake cylinder pressure when a conventional anti-skid control device is applied to the anti-skid control device of the above embodiment.

[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 98 liquid chamber 160 direct current servo motor 170 anti Skid control unit 180 Motor control circuit 188, 190, 194, 196 FET 200 Power supply 204 PWM generation circuit 210 Closed circuit

Claims (2)

[Claims] 1. An electric motor that is rotatable in both forward and reverse directions, a movable member that is moved forward and backward by rotation of the electric motor in forward and backward directions, and a volume that is moved forward and backward by the movable member. A fluid chamber that is increased and decreased and is connected to a brake cylinder that suppresses wheel rotation, and the motor is rotated in the forward direction to reduce the hydraulic pressure in the brake cylinder, or is rotated in the opposite direction. A motor controller for increasing the hydraulic pressure of a brake cylinder, the anti-skid controller for controlling the slip ratio of the wheel within a set range, wherein the motor controller is configured to reverse the forward rotation of the electric motor. At the end of at least one of the rotation in the direction, the motor is driven by applying a voltage to drive the electric motor in the opposite direction. Reverse-phase braking means for electrically braking over data,
Anti-skid control, characterized in that non-applied state maintaining means for maintaining a non-applied state in which neither a voltage for driving the electric motor in the forward direction nor a voltage for driving in the reverse direction is applied after the operation of the anti-phase braking means is completed apparatus. 2. An electric motor that is rotatable in both forward and reverse directions, a movable member that is moved forward and backward by rotation of the electric motor in forward and reverse directions, and a volume that is moved forward and backward by the movable member. A fluid chamber that is increased and decreased and is connected to a brake cylinder that suppresses wheel rotation, and the motor is rotated in the forward direction to reduce the hydraulic pressure in the brake cylinder, or is rotated in the opposite direction. A motor control device for increasing the hydraulic pressure of a brake cylinder, and an anti-skid control device for controlling the slip ratio of the wheel within a set range, wherein the motor control device includes a closed circuit including the electric motor and a load device. An anti-skid control device is provided with a dynamic braking circuit that forms a brake and brakes an electric motor.