JPH05213173A - Anti-skid control device - Google Patents

Abstract

PURPOSE:To improve accuracy for hydraulic control, in an anti-skid control device in such a form as increasing and decreasing hydraulic pressure in a brake cylinder, by normal and reverse rotation of a direct current motor. CONSTITUTION:Increasing and decreasing of hydraulic pressure in a brake cylinder and velocity thereof are controlled, by controlling rotational direction of a direct current motor 92 through selective conductivity of FET 152, 162 in a main circuit 142 and by controlling rotational speed through duty control of FET 154, 164. At that time, actual' current is detected by a current detector 146 consisting of a shunt resistor 172 and an amplifier 186, and it is fed back to a PWM generating circuit 18 through a feed back circuit 148. A PWM signal from the PWM generating circuit 180 is selected by AND circuits 182, 202 and supplied to FET 154 or 164. The main circuit 142 becomes a linear circuit substantially though it is a non-linear circuit originally, and accuracy for the velocity control of the direct current motor 92 and moreover accuracy for the hydraulic control of the brake cylinder are improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid control device provided in a vehicle hydraulic brake device, and more particularly to an anti-skid device of the type in which the brake cylinder hydraulic pressure is increased / decreased by the forward and reverse rotation of a DC motor. The present invention relates to improvement of hydraulic pressure control accuracy in a control device.

[0002]

2. Description of the Related Art The applicant of the present invention is Japanese Patent Application No. 2-183598.
Japanese Patent Application No. 2-291292 and Japanese Patent Application No. 2-41156
No. 0 etc. proposed an anti-skid control device of the above type. These anti-skid control devices include (1) a movable member that is moved forward and backward by a DC motor that is normally or reversely rotated by a DC motor control circuit, and a liquid chamber whose volume is increased or decreased by the movement of the movable member. A hydraulic pressure control device for controlling the hydraulic pressure of the brake cylinder, the hydraulic chamber being communicated with the hydraulic chamber of the brake cylinder of the brake that suppresses the rotation of the wheel, and (2) according to the slip state of the wheel. And a main control device for controlling the hydraulic pressure control device to keep the slip ratio of the wheel in an appropriate range.

If the wheels slip excessively during braking of the vehicle, the main controller causes the direct current motor to rotate in the normal direction to increase the volume of the fluid chamber of the fluid pressure controller. As a result, the brake fluid flows out of the fluid chamber of the brake cylinder into the fluid chamber of the fluid pressure control device, the fluid pressure of the brake cylinder is reduced, and the braking force is reduced. As a result, when the wheel slip is reduced, the main control device reverses the direct-current motor, and the brake cylinder fluid pressure is increased by the supply of the brake fluid from the fluid chamber of the fluid pressure control device to increase the braking force. By repeating this operation, the brake cylinder hydraulic pressure is maintained at a substantially proper value, and the wheel slip ratio is maintained within a proper range.

[0004]

The control circuit for the DC motor includes (a) a forward rotation circuit and a reverse rotation circuit for connecting the DC motor and the DC power source, respectively, and both of these circuits are selectively operated. A current amount that has direction changeover switch means for switching the direction of current supply to the DC motor when it is made conductive, and at least one of these circuits controls the magnitude of the current supplied to the DC motor by duty control. It is desirable to include a main circuit having a control switch means, and (b) a duty control circuit for duty-controlling the current amount control switch means on the basis of a command current value from the main control device. It is possible to control not only the forward rotation and the reverse rotation of the DC motor but also the rotation speed in at least one of the forward direction and the reverse direction to control at least one of the pressure increasing speed and the pressure reducing speed of the brake cylinder hydraulic pressure. This is because the skid control accuracy can be improved.

However, in this circuit, the relationship between the command current value from the main control unit and the actual current value actually flowing in the DC motor depends on the inductive reactance of the coil of the DC motor and ON / OFF of the switch means such as MOSFET. It becomes non-linear due to the non-linearity of the characteristics. As a result, it becomes difficult to control the rotation speed of the DC motor, and the control accuracy of the brake cylinder hydraulic pressure deteriorates. An object of the present invention is to improve the control accuracy of the brake cylinder hydraulic pressure by improving the accuracy of the rotation speed control of the DC motor.

[0006]

The gist of the present invention resides in the above (a) main circuit and (b) of an antiskid controller including (1) a hydraulic controller and (2) a main controller. In the motor control circuit including the duty control circuit,
(C) A current value detector for detecting the current value actually flowing through the DC motor, and (d) a feedback circuit for feeding back the current value detected by the current value detector to the duty control circuit. The feedback circuit may be provided in only one of the forward rotation circuit and the reverse rotation circuit of the main circuit, or in both of them. When the feedback circuit is provided in both, the current detector can be provided in each of the forward rotation circuit and the reverse rotation circuit of the main circuit, but it is also possible to provide the current detector in the common portion of both circuits and share it. Is.

[0007]

In the anti-skid control device equipped with the motor control circuit having the above structure, the actual current detected by the current detector is fed back to the duty control circuit, so that the inductive reactance of the motor coil and the non-linearity of the switching means are increased. Despite the non-linearity of the main circuit due to the characteristics, the control circuit as a whole becomes almost linear, and the control accuracy of the rotation speed of the DC motor is improved. If the feedback circuit is provided in the forward rotation circuit, the forward rotation speed control accuracy of the DC motor is improved and the pressure reduction control accuracy is improved.If it is provided in the reverse rotation circuit, the reverse rotation speed control accuracy is improved and increased. If the accuracy of pressure control is improved and provided in both the forward rotation circuit and the reverse rotation circuit, both the pressure increase and pressure reduction control accuracy are improved.

[0008]

As described above, according to the present invention, the control accuracy of the brake cylinder hydraulic pressure is improved, the slip ratio of the wheel is kept in a range closer to an appropriate value than before, and the antiskid control accuracy is improved. As a result, the braking distance of the vehicle is shortened and the running stability is improved. Moreover, since the current detector and the feedback circuit may be added for that purpose, the object can be achieved at low cost.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings by taking the case where the present invention is applied to an anti-skid control device for a hydraulic brake device for a four-wheel vehicle as an example. 2 in FIG.
Is a master cylinder, and a brake pedal 14 as a brake operating member 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 approximately the same height are provided in the 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 pedal effort applied to the brake pedal 14, and transmits the boosted pedal effort 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 each brake of the right front wheel 36 and the left rear wheel 38 by the main fluid passages 30, 32 and 34, and the other. The hydraulic pressure generated in the pressurizing chamber 24 of the left front wheel 52,
Brake cylinders 56, 58 for each brake of the right rear wheel 54
Be transmitted to. Between the main liquid passages 32 and 34, 48 and 50
And proportioning valves 60 and 6 between
Two are provided. This brake system is of X piping type.

A forward movement blocking device 70 is provided between the booster 12 and the master cylinder 10. The advance prevention device 70 includes a bottomed cylindrical housing 72, to which a control piston 74 is fitted in a liquid-tight and slidable manner. The push rod 28 of the booster 12 is engaged with the rear end (the right end in the figure) of the control piston 74, and the pressurizing piston 20 of the master cylinder 10 is engaged with the front end (the left end in the figure). ing. By fitting the control piston 74 into the housing 72, a control liquid chamber 78 is formed in front of the control piston 74 (left side in the drawing).

The volume of the control liquid chamber 78 decreases as the control piston 74 moves forward (moves to the left in the figure), and increases as it moves backward.
The control liquid chamber 78 is connected to the reservoir 26 via a normally open electromagnetic opening / closing valve 80. A check valve 82 that bypasses the solenoid valve 80 is connected to the solenoid valve 80. The check valve 82 allows the flow of the brake fluid from the reservoir 26 side toward the control fluid chamber 78 side and blocks the reverse.

2 of housing 72 and control piston 74
Cup seals 84 and 86 are attached to the one fitting portion, respectively. Each of the cup seals 84 and 86 has a first lip extending from the body toward the control fluid chamber 78 side and a second lip extending toward the outside, and the brake fluid from the control fluid chamber 78 side toward the outside. Both the flow of and the opposite flow are blocked.

Therefore, when the electromagnetic opening / closing valve 80 is closed, the brake fluid is contained in the control fluid chamber 78, the forward movement of the control piston 74 is blocked, and the brake pedal 1
The increase in the hydraulic pressure in the master cylinder 10 due to the depression of 4 is prevented. When the depression of the brake pedal 14 is released with the electromagnetic opening / closing valve 80 closed, the brake fluid flows from the reservoir 26 into the control fluid chamber 78 through the check valve 82, and the control piston 74 retreats. Is acceptable.

A liquid pressure control device 90 is connected to the pressurizing chamber 24 by a liquid passage 88. The hydraulic pressure control device 90
By moving the ball screw 94 based on the rotation of the DC motor 92, the hydraulic pressure control piston 96 is moved back and forth to increase or decrease the volume of the liquid chamber 98. The rotational movement of the DC motor 92 is based on the pinion 100 and the gear 102.
The hydraulic piston 96 is moved forward and backward by being converted into the linear movement of the ball screw 94 by the nut 104.

The DC motor 92 and the pinion 100 are connected to each other via a clutch 108. Clutch 1
08 is a one-way type in which the rotation on the DC motor 92 side is transmitted to the pinion 100 side, but the rotation on the pinion 100 side is not transmitted to the DC motor 92 side. Reference numeral 110 is a spline shaft integrally formed with the ball screw 94, and 112 is a spline hole into which the spline shaft 110 is fitted. The spline shaft 110 and the spline hole 11
2, the ball screw 94 is allowed to move in the axial direction but is prevented from rotating about the axis. Further, the nut 104 is rotatable about the axis and is immovable in the axial direction.

The electromagnetic opening / closing valve 80 and the DC motor 92
Are controlled by an anti-skid control unit (hereinafter, simply referred to as a unit) 120. The unit 120 is
The main component is a computer having a CPU, a ROM, a RAM and a bus connecting them. The unit 120 includes wheel speed sensors 124 and 126 that detect the wheel speeds of the left and right front wheels 52 and 36, respectively, and a wheel speed sensor 12 that detects wheel speeds of the left and right rear wheels 38 and 54.
The detection results of Nos. 8 and 130 are supplied, and the unit 120 calculates the wheel speed, the wheel acceleration, the vehicle body speed, the slip ratio, and the like based on the supplied results.

The unit 120 also includes a motor control circuit 1
The DC motor 92 is controlled via 40. The electromagnetic on-off valve 80 and the DC motor 92 are controlled based on the result of the above calculation to control the slip ratios of the wheels 36, 38, 52, 54, etc. to values as close to appropriate values as possible, and in the present embodiment. The unit 120 has wheel speed sensors 124, 1
26, 128, 130 and the like constitute the main controller.

As shown in FIG. 1, the motor control circuit 140 includes a main circuit 142, a duty control circuit 144, a current detector 146 and a hood back circuit 148. The main circuit 142 is a MOS type F for switching the current supply direction.
ET152 and MOS type FET 154 for controlling current amount
Is provided in series, and a reverse circuit 166 having in series a current supply direction switching FET 162 and a current amount control FET 164. The forward rotation circuit 156 and the reverse rotation circuit 166 form a closed circuit that connects the DC power supply 170 and the DC motor 92 in series, but have a common portion, and the shunt resistor 172 is provided at the common portion. Is provided.

In the FET 152 of the normal rotation circuit 156, the normal rotation command signal R _IN from the unit 120 is supplied to the amplifiers 174, 1.
Conducts when the signal amplified by 76 is at high level,
The current is allowed to rotate the DC motor 92 in the positive direction. The current value command signal R _PWM is also output from the unit 120.
Is supplied to the PWM (pulse width control signal) generation circuit 180 via the differential amplifier 178. And
The PWM signal from the PWM generation circuit 180 is the AND circuit 1
Is supplied to the FET 154 via the amplifier 82 and the amplifier 184, and the DC motor 9 is controlled by the duty control of the FET 154.
The current supplied to 2 is changed to change the rotation speed in the forward direction.

The voltage between both terminals of the shunt resistor 172 is amplified by the amplifier 186, is supplied to the differential amplifier 178 via the filter 188, and is supplied to the differential amplifier 178.
Is adapted to supply an output voltage to the PWM generating circuit 180 according to the difference between the current value command signal R _PWM from the unit 120 and the actual current value signal I _A detected by the shunt resistor 172. As a result, the PWM generation circuit 180
Generates a PWM signal that eliminates the difference between the current value command signal R _PWM and the actual current value signal I _A. The shunt resistor 172 and the amplifier 186 form the current detector 146, and the filter 188 and the differential amplifier 178 form the feedback circuit 148.

Although the forward rotation circuit 156 side has been described above, the reverse rotation circuit 166 side is similarly configured, and the amplifier 1 is provided.
94, 196, a differential amplifier 198, an AND circuit 202, an amplifier 204 and the like are provided. The reverse rotation command signal is represented by L _IN , and the current value command signal in the reverse rotation direction is L _PWM.
It is represented by.

In the AND circuit 182, in addition to the PWM signal,
The output signal of the amplifier 174 is input to the unit 1
Only when the forward rotation command signal R _IN is issued from 20, the passage of the forward rotation PWM signal is allowed. A
A signal obtained by inverting the output signal of the amplifier 194 by the inverter 210 is input to the ND circuit 182. This is because, if the FET 152 and the FET 164 are rendered conductive at the same time due to a malfunction of the unit 120, a short circuit that bypasses the DC motor 92 may be formed and the FETs 152 and 164 may be damaged. Is. An inverter 212 is also provided on the side of the AND circuit 202 and has the same configuration. The inverters 210 and 212 are omitted,
It is also possible to make the AND circuits 182 and 202 two inputs.

In the hydraulic brake device constructed as described above, the electromagnetic opening / closing valve 80 is normally opened and the control liquid chamber 78 is communicated with the reservoir 26. Therefore, when the brake pedal 14 is depressed, the control piston 7
4 is advanced, the pressurizing pistons 18, 20 are advanced, hydraulic pressure is generated in the pressurizing chambers 22, 24, and rotation of the wheels is suppressed. At this time, the hydraulic pressure having the same height as the hydraulic pressures of the pressurizing chambers 22 and 24 is transmitted to the liquid chamber 98, but since the forward movement of the hydraulic pressure control piston 96 is blocked by the clutch 108, the liquid chamber 98. Does not increase in volume.

When the stepping force of the brake pedal 14 becomes excessive and the slip ratio of the wheels exceeds the proper range, the unit 120 switches the electromagnetic opening / closing valve 80 to the closed state to prevent the control piston 74 from advancing. The hydraulic pressure control piston 96 is operated. First, the electric motor 92 is rotated through the motor control circuit 140 in a direction to increase the volume of the fluid chamber 98, whereby the fluid pressure in the fluid chamber 98, and thus the fluid pressure in the pressure chambers 22 and 24 and the brake cylinder fluid. The pressure is reduced. As a result, the reaction force applied from the pressure piston 20 to the control piston 74 decreases. Therefore, as long as the stepping force of the brake pedal 14 is kept constant, the force balance of the control piston 74 is broken and the control piston 7
4 tries to move forward, but since the outflow of the brake fluid from the control fluid chamber 78 is blocked by the electromagnetic on-off valve 80 which is in the closed state, the control piston 74 cannot move forward and the pressurizing piston 20 moves forward. The hydraulic pressure in the control liquid chamber 78 only increases by an amount commensurate with the amount of decrease in the reaction force of. That is,
By closing the electromagnetic opening / closing valve 80, the forward movement of the control piston 74 is blocked, and the pressurizing chamber 22,
Even if the hydraulic pressure in 24 decreases, the control piston 74 does not move forward to increase the hydraulic pressure in the pressurizing chambers 22, 24.

If the slip ratio starts to recover due to the above pressure reduction, is the forward movement of the hydraulic pressure control piston 96 stopped?
Alternatively, the liquid chamber 98 is moved back, and the volume of the liquid chamber 98 is held or reduced so that the hydraulic pressure, and thus the brake cylinder hydraulic pressure, is held or increased. By this pressure increase, the reaction force from the pressure piston 20 to the control piston 74 increases,
The hydraulic pressure in the control liquid chamber 78 is reduced by an amount commensurate with the increase, the balance of the force on the control piston 74 is maintained, and the control piston 74 continues to stand still.

As described above, the unit 120 includes the DC motor 9
2 is controlled to increase / decrease the volume of the liquid chamber 98 irrespective of the depression of the brake pedal 14 to reduce / maintain / increase the brake cylinder hydraulic pressure to keep the wheel slip ratio within an appropriate range. If the depression of the brake pedal 14 is released during the anti-skid control, the control piston 74 retracts, and the pressurizing pistons 18 and 20 retract accordingly, so that the hydraulic pressures in the pressurizing chambers 22 and 24 reach the height desired by the driver. Decompressed to.

The control of the brake cylinder hydraulic pressure is performed by pressure reduction, holding and pressure increase as described above. In this embodiment, both the pressure reduction and pressure increase speeds can be controlled arbitrarily. For example, the depressurization speed is based on the current value command signal R _PWM from the unit 120
The duty control of 54 is performed, the rotation speed is controlled by the control of the current supplied to the DC motor 92, and the brake fluid from the fluid chamber of the brake cylinders 40, 42, 56 and 58 to the fluid chamber 98 of the fluid pressure control device 90 is controlled. Is controlled by controlling the outflow rate of.

Moreover, the actual current value of the DC motor 92 is detected by the current detector 146 and fed back to the PWM generating circuit 180, so that the PWM generating circuit 180 outputs the current value command signal R _PWM from the unit 120 and the actual current value signal. I
_Since the PWM signal is generated according to the difference from _A , current control is easy. Since the coil of the DC motor 92 has an inductive reactance and the ON / OFF characteristic of the FET 154 has non-linearity, the forward current circuit 156 as a whole has the actual current value of the DC motor 92 as the command current value from the unit 120. Although it is a non-linear circuit that is not proportional to, it becomes a substantially linear circuit by feedback of the actual current value, and the current control by the unit 120 becomes easy.

Therefore, the accuracy of the rotation speed control of the DC motor 92 is improved, and the accuracy of reducing the brake cylinder hydraulic pressure is improved. The same applies to the pressure increase control of the brake cylinder hydraulic pressure. The speeds of pressure reduction and pressure increase can be controlled arbitrarily and accurately, and the brake cylinder hydraulic pressure can be controlled with high accuracy.

Another embodiment of the motor control circuit is shown in FIG. In the motor control circuit 140, the unit 1
AND of the selection of the current value command signals R _PWM and L _PWM based on the forward command signal R _IN and the reverse command signal L _IN from 20
This is performed by the circuits 182 and 202, and a commercially available 7408 is used as the AND circuits 182 and 202.
Since TTL or the like can be used and the selection does not have to be performed by the program of the unit 120, there is an advantage that the configuration can be inexpensive, but as shown in FIG. I can fulfill my purpose. The analog switch 220 selects the output signal of the amplifier 186 according to the switching signal from the unit 120 and supplies it to the filter 222.

In this embodiment, for example, the DC motor 92
When it is necessary to rotate the forward direction, the unit 120 supplies the forward direction current value command signal R _PWM to the filter 222.
, The actual current value signal I _A is supplied to the adder 224 and the difference between the two is calculated. On the other hand, regarding the reverse rotation direction, signals of equal magnitude are supplied from the unit 120 and the filter 222, and the difference between the two is calculated. Since it becomes zero, only the normal rotation signal is supplied to the PWM generation circuit 180. Since other parts are the same as those in the above-described embodiment, the corresponding components are designated by the same reference numerals and detailed description thereof will be omitted.

In the above embodiment, the hydraulic pressure control device 90 is separate from the master cylinder 10, the advance prevention device 70 and the booster 12, but the hydraulic control device 90, the master cylinder 10 and the advance prevention device are separate. The device 70 and the booster 12 may be integrally connected to each other to form a hydraulic pressure source unit. In this case, for example, as shown in FIG. 4, the hydraulic pressure control device 90 may be configured integrally with the advancement prevention device 70 so that it can be attached and detached as a unit between the master cylinder 10 and the booster 12. Is.

Further, in each of the above-mentioned embodiments, the forward movement preventing device 70 always allows the pressurizing pistons 18 and 20 to move forward and backward, but only the forward movement is prevented during the anti-skid control. However, during anti-skid control, not only forward movement but also backward movement can be prevented. Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention can be carried out in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an example of a motor control circuit of an anti-skid control device that is an embodiment of the present invention.

FIG. 2 is a system diagram of a hydraulic brake device including the anti-skid control device.

FIG. 3 is a circuit diagram of a motor control circuit according to another embodiment of the present invention.

FIG. 4 is a system diagram of a hydraulic brake device including an anti-skid control device according to another embodiment of the present invention.

[Explanation of symbols]

 10 Master Cylinder 14 Brake Pedal 40, 42, 56, 58 Brake Cylinder 70 Forward Stop Device 90 Hydraulic Pressure Control Device 120 Anti-Skid Control Unit 140 Motor Control Circuit 142 Main Circuit 144 Duty Control Circuit 146 Current Detector 148 Feedback Circuit 152, 154 , 162, 164 FET 156 circuit for forward rotation 166 circuit for reverse rotation

Claims (1)

[Claims] 1. A liquid chamber provided with a movable member that is moved forward and backward by a DC motor that is normally or reversely rotated by a DC motor control circuit, and a liquid chamber whose volume is increased or decreased by the movement of the movable member. Is connected to a hydraulic chamber of a brake cylinder of a brake that suppresses wheel rotation, and controls a hydraulic pressure control device that controls the hydraulic pressure of the brake cylinder; and controls the hydraulic pressure control device according to the slip state of the wheel. In the anti-skid control device including a main control device that keeps the slip ratio of the wheels in an appropriate range, the DC motor control circuit includes a forward rotation circuit and a reverse rotation circuit that respectively connect a DC motor and a DC power supply. , And has direction changeover switch means for changing over the direction of current supply to the DC motor by selectively turning on both of these circuits, and
At least one of the two circuits has a main circuit having a current amount control switch means for controlling the magnitude of the current supplied to the DC motor by duty control, and the current amount control based on a command current value from the main control device. A duty control circuit for duty-controlling the switching means, a current value detector for detecting a current value actually flowing through the DC motor, and a feedback circuit for feeding back a current value detected by the current value detector to the duty control circuit. An anti-skid control device characterized by including.