JP5138638B2 - Brake control device - Google Patents

Description

  The present invention relates to a brake control device including a normally open type proportional control valve.

  Conventionally, as a brake control device including a normally open type proportional control valve, a technique described in Patent Document 1 is known.

JP 2000-71973 A

  In order to control a normally open type proportional control valve with high accuracy, it is desirable that the relationship between the electromagnetic force and the valve stroke be constant (hereinafter referred to as flat characteristics). However, in order to achieve this, the configuration of the proportional control valve needs to be complicated and highly accurate, resulting in a cost increase. Further, in order to use a control region where flat characteristics can be obtained, use in a region of relatively high electromagnetic force is desired, and a spring set load or the like is set high. In this case, there is a problem that power consumption is large.

  The present invention has been made paying attention to the above problem, and is to provide a brake control device capable of suppressing power consumption at a low cost.

In order to achieve the above object, in the present invention, a first energizing means for energizing a solenoid of a proportional control valve with a predetermined current for closing the valve body, and a predetermined current continuously after energization by the first energizing means. The proportional control valve is controlled by the second energizing means for energizing a lower current . At this time, while the drive command is output to the motor that drives the pump, the current is supplied by the first energizing means for the time until the motor starts to rotate by applying a voltage .

  Therefore, high control accuracy can be obtained even if the offset load is reduced while simplifying the configuration of the proportional control valve.

It is the schematic showing the structure of the hydraulic control unit in the brake control apparatus of Example 1. It is a characteristic view showing the relationship between the valve stroke and electromagnetic force of a high-performance proportional control valve. It is a characteristic view showing the relationship between an electric current and a balance hydraulic pressure. It is a characteristic view showing the relationship between the valve stroke and electromagnetic force of a low performance proportional control valve. 3 is a flowchart illustrating a hydraulic pressure control process according to the first embodiment. 3 is a flowchart illustrating a gate-out valve current control process according to the first embodiment. 3 is a time chart at the time of balance control during pressure increase in the first embodiment. It is a figure showing to which position the relationship between an electric current and a balance liquid pressure changes when balance control is performed by the characteristic of an electric current and the balance liquid pressure.

FIG. 1 is a schematic diagram illustrating a configuration of a hydraulic pressure control unit in the brake control device according to the first embodiment. 1 is a brake pedal, 2 is a booster, 3 is a tandem master cylinder, 4 is a reservoir tank, and 5 is a wheel cylinder. A plurality of configurations corresponding to the respective wheel cylinders 5 (the left front wheel 5a, the right front wheel 5b, the left rear wheel 5c, and the right rear wheel 5d) are distinguished by adding suffixes a to d. a corresponds to the left front wheel, b corresponds to the right front wheel, c corresponds to the left rear wheel, and d corresponds to the right rear wheel. 1 is divided into a primary system (P system) and a secondary system (S system) with the master cylinder 3 in FIG. 1 as the center. . 6 is a pressure increase control valve provided corresponding to each wheel, and 7 is a pressure reduction control valve provided corresponding to each wheel. 8 is a normally open type proportionally controlled gate-out valve provided for each system, 9 is a pump provided for each system, 10 is a motor for driving the pumps of both systems, 11 Is an internal reservoir with a pressure adjusting function provided corresponding to each system, 12 is a master cylinder pressure sensor provided in the P system, and 13 is a check valve provided in each system.
Here, the configuration of the gate-out valve 8 will be described. As shown in the enlarged portion of FIG. 1, the gate-out valve 8 includes a valve body 81, a valve seat 82 that opens and closes the flow path when the valve body 81 abuts, and a valve body 81. A spring 83 (biasing means) that urges the valve body 81 in a direction to separate the valve body 81, a solenoid 84 that generates an electromagnetic force for moving the valve body 81 in the direction of the valve seat portion 82 against the urging force of the spring 83, Have When a current is passed through the solenoid 84, the valve body 81 is pushed down against the elastic force of the spring 83 by the electromagnetic force, and the flow passage area between the valve seat portion 82 is changed according to the stroke amount of the valve body 81. Thus, the flow rate or hydraulic pressure is proportionally controlled.
The oil passage 20 connected to the master cylinder 3 branches into an oil passage 21 connected to the internal reservoir 11 and an oil passage 22 provided with the gate-out valve 8 and connected to the wheel cylinder 5. Hereinafter, the S system will be described. The oil path 22S branches into an oil path 22Sb connected to the right front wheel wheel cylinder 5b and an oil path 22Sc connected to the left rear wheel wheel cylinder 5c. The oil passages 22Sb and 22Sc are branched into oil passages 23Sb and 23Sc connected to the internal reservoir 11S. The internal reservoir 11 and the suction side of the pump 9 are connected by an oil passage 25, and the discharge side of the pump 9 and the oil passage 22 are connected by an oil passage 26. In addition, a control unit 20 is provided, and opening / closing control and motor drive control of each control valve and the electromagnetic valve of the motor 10 are executed by a command signal or drive current output from the control unit 20. The control unit 20 includes a first energization unit 201 (first energization means) that energizes the solenoid 84 with a predetermined current for closing the valve body 81, and is continuously lower than the predetermined current after energization by the first energization unit 201. It has the 2nd electricity supply part 202 (2nd electricity supply means) which supplies an electric current, and controls the electric current supplied to the solenoid 84. FIG.

Next, the operation will be described. When the driver depresses the brake pedal 1, the stepping force is amplified by the booster 2, and this amplified force is transmitted to the master cylinder 3. The master cylinder 3 generates a master cylinder pressure that is a hydraulic pressure proportional to the transmitted force.
The pressure increase control valve 6 performs an opening / closing operation by a command current from the control unit 20, and performs an operation of supplying or shutting off the master cylinder pressure or pump pressure supplied to the pressure increase control valve 6 to the wheel cylinder 5. The check valve provided in parallel with the pressure increase control valve 6 acts to release the wheel cylinder pressure to the master cylinder side when the wheel cylinder pressure> (pressure on the discharge side of the pump 9).
The decompression control valve 7 performs an opening / closing operation by a command current from the control unit 20, and performs an operation of supplying or shutting off the wheel cylinder pressure to the internal reservoir 11.
The gate-out valve 8 operates proportionally between fully opened and fully closed by a command current from the control unit 20, and performs an operation of intermittently connecting between the discharge side of the master cylinder 3 and the pump 9 and the pressure increase control valve 6. . The check valve provided in parallel with the gate-out valve 8 controls the master cylinder pressure to the discharge side of the pump 9 and the pressure increase control valve when the master cylinder pressure> (pressure on the discharge side of the pump 9). It works to tell the 6th side.
The pump 9 is driven by the motor 10 and scrapes the brake fluid in the internal reservoir 11 to the master cylinder 3 side via the gate-out valve 8. Further, the brake fluid is sucked from the master cylinder 3 through the internal reservoir 11 and discharged to the wheel cylinder 5 side.
The rotation speed of the motor 10 is controlled by a command current from the control unit 20 and drives the pump 9.
The internal reservoir 11 with a pressure adjusting function prevents the pump 9 from flowing into the suction side when a pressure is generated from the master cylinder 3 side even when the pump 9 is stopped, and from the master cylinder 3 side when the pump 9 is driven. Inflow is preferentially enabled. Moreover, the brake fluid sent via the pressure reduction control valve 7 is stored.
The master cylinder pressure sensor 12 detects the master cylinder pressure and inputs the detected value to the control unit 20.
The check valve 13 prevents a back flow from between the gate-out valve 8 and the pressure increase control valve 6 to the discharge side of the pump 9.
The control unit 20 receives the detection value sent from the master cylinder pressure sensor 12 and the information about the running state sent from the vehicle, and based on the built-in program, the pressure increase control valve 6, the pressure reduction control valve 7, the gate-out valve. 8. The motor 10 is controlled.
Here, the gate-out valve 8 is a so-called proportional control valve in which the valve opening degree changes proportionally depending on the current value. Note that the pressure increase control valve and the pressure reduction control valve may be an on / off valve or a proportional control valve in which the valve opening degree takes only two positions of fully open and fully closed.

[Problems when using a normally open proportional control valve]
Next, problems when using a normally open type proportional control valve such as the gate-out valve 8 will be described. When the normally open proportional control valve is kept closed, an electromagnetic force larger than the sum of the spring force and the fluid force is applied as much as necessary to keep the normally closed state, thereby reducing electric energy consumption. In addition, a current is supplied to the proportional control valve before the pressure is increased.
In this system, the relationship between the valve stroke and the electromagnetic force is important when performing balance control that controls the actual wheel cylinder hydraulic pressure and the target wheel cylinder hydraulic pressure by using the balance of the differential pressure between the pressure-reducing proportional control valves during pressure increase. It is. FIG. 2 is a characteristic diagram showing the relationship between the valve stroke and the electromagnetic force of the high-performance proportional control valve, and FIG. 3 is a characteristic diagram showing the relationship between the current and the balance hydraulic pressure. The dotted line in FIG. 2 shows the relationship of spring force. As shown in FIG. 2, if the valve stroke and the electromagnetic force are flat, that is, a proportional control valve having high control performance in which the electromagnetic force is stable even if the position of the plunger is changed by the valve stroke, the current and the balance liquid As for the relationship of pressure, proportional control can be performed in which the valve stroke is proportionally changed from fully open to fully closed with the minimum necessary electromagnetic force as shown in the diagram (1) of FIG. However, in order to flatten the characteristics of electromagnetic force, it is necessary to complicate the configuration, and it is very expensive because it is affected by manufacturing accuracy and the like. In addition, a region having an attractive force characteristic with a high current value is used, the consumption of electric energy increases, heat is generated, and there is a concern that durability may deteriorate.
Here, a case where a proportional control valve having a low control performance is designed by simplifying the configuration at low cost and using a suction force characteristic with a reduced current value to be used will be considered. FIG. 4 is a characteristic diagram showing the relationship between the valve stroke and the electromagnetic force of the low performance proportional control valve. As shown in FIG. 4, the relationship between the valve stroke and the electromagnetic force has a characteristic of a downward slope, and the relationship between the current and the balance hydraulic pressure has a characteristic as shown by a dotted line (2) in FIG. That is, there is a problem that the valve does not stroke at the minimum necessary current at the start of the movement from fully open to fully closed, and cannot be fully closed or cannot be proportionally controlled. If it is not fully closed or proportional control is not possible, it is necessary to determine the state of the fluid pressure by a pressure sensor or the like, and to correct the fluid pressure control so that the fluid pressure follows the target value. In addition, when the valve is stroked with the current value at which the electromagnetic force exceeds the spring force from fully open to fully closed, and the valve is fully closed, more electromagnetic force than necessary is applied compared to the spring force, which is unnecessary. There is also a problem of incurring excessive power consumption.
Therefore, in the first embodiment, even with an inexpensive low-performance proportional control valve, a large current is given for a predetermined time at the initial stage of the valve stroke so that stable control can be achieved, and then the current is lowered to perform proportional control. The pressure control process was performed.

[Hydraulic pressure control processing]
Next, the hydraulic pressure control performed in the control unit 20 in the first embodiment will be described. FIG. 5 is a flowchart illustrating the hydraulic pressure control process according to the first embodiment.
In step S601, it is determined whether or not the wheel cylinder pressure is to be controlled. If so, the process proceeds to step S602. If not, the process proceeds to step S606 to end the present process.
In step S602, it is determined whether or not the wheel cylinder pressure is increased. If the pressure is increased, the process proceeds to step S603, and if not, the process proceeds to step S607.
In step S603, the gate-out valve 8 is balanced, the pressure increase control valve 6 is opened, the pressure reduction control valve 7 is closed, the motor 10 is turned on, and the pump 9 is driven. As a result, the pump pressure is supplied to the wheel cylinder 5 via the internal reservoir 11, and the wheel cylinder pressure is increased.
In step S604, it is determined whether or not the wheel cylinder pressure has reached a target value. This determination is made by comparing the wheel cylinder pressure with the estimated value. If the target value has been reached, the process proceeds to step S605. If not, the process returns to step S603, and the wheel cylinder 5 is continuously pressurized.
In step S605, it is determined whether or not to continue to control the wheel cylinder pressure. When the control is continued, the process returns to step S602 to continue the control. When the control is finished, the process proceeds to step S606.
In step S606, in order to terminate the control, the gate-out valve 8 is opened, the pressure increase control valve 6 is opened, the pressure reduction control valve 7 is closed, and the motor 10 is turned off. Thereby, the oil path between the master cylinder 3 and the wheel cylinder 5 is connected, the master cylinder pressure is supplied to the wheel cylinder 5, and the wheel cylinder pressure is increased by the driver's operation.
In step S607, it is determined whether or not the wheel cylinder pressure is to be reduced. If the pressure is to be reduced, the process proceeds to step S608. If not, the process proceeds to step S610.
In step S608, the gate-out valve 8 is proportionally controlled, the pressure-increasing control valve 6 is opened, the pressure-reducing control valve 7 is closed, the motor 10 is turned off, and the wheel cylinder pressure is smoothly supplied to the reservoir tank 4 via the gate-out valve 8. The pressure is reduced by returning to.
In step S609, it is determined whether or not the wheel cylinder pressure has reached a target value. This determination is made by comparing the wheel cylinder pressure with the estimated value. If the target value is reached, the process proceeds to step S605 described above. If not, the process returns to step S608, and the wheel cylinder is continuously depressurized.
In step S610, the pressure is neither increased nor reduced, that is, maintained, the gate-out valve 8 is closed, the pressure-increasing control valve 6 is opened, the pressure-reducing control valve 7 is closed, and the motor 10 is turned off. Hold.
In step S611, it is determined whether or not the wheel cylinder pressure has reached a target value. This determination is made by comparing the wheel cylinder pressure with the estimated value. If the target value has been reached, the process proceeds to step S605 described above. If not, the process returns to step S610 to continue holding the wheel cylinder.

Next, current control of the gate-out valve 8 will be described. FIG. 6 is a flowchart illustrating a gate-out valve current control process according to the first embodiment.
In step S701, it is determined whether or not the balance control is started. If the control is started, the process proceeds to step S702. If the balance control is performed in advance, the process proceeds to step S705.
In step S702, a current necessary for moving to the gate stroke which can be proportionally controlled is supplied to the gate-out valve 8, and the proportional control valve is once stroked.
In step S703, a current is continuously supplied for a predetermined time so as to reliably move the gate-out valve 8 to a valve stroke that can be proportionally controlled (first energization unit 201). If the predetermined time has elapsed, the process proceeds to step S704, and if not, the process proceeds to step S702. The predetermined time here indicates a short time until the pump 9 starts rotating by applying a voltage to the motor 10, and the motor 10 and the gate-out are utilized by utilizing the fact that the response of the motor 10 is delayed with respect to the control valve. By applying a voltage to the valve 8 at the same timing and changing the current value to the gate-out valve 8 before the motor 10 starts to rotate so that proportional control is possible, balance control can be performed while preventing delay in boosting. Let me.
In step S704, the current that has flowed to move to the valve stroke that can be proportionally controlled by the gate-out valve 8 is lowered to a current that can be balanced, and the balance control is enabled.
In step S705, the current flowing through the gate-out valve 8 is set so as to match the balance hydraulic pressure, and thereafter balance control is performed (second energization unit 202).

Next, the operation based on the above control will be described. FIG. 7 is a time chart at the time of balance control at the time of pressure increase in the first embodiment.
When the hydraulic pressure command value increases and the pressure is increased, the motor 10 starts to be given a duty, and at the same time, the current value flowing through the gate-out valve 8 is greatly given to move to a valve stroke that can be proportionally controlled (first energizing means). Thereafter, the current value is lowered to a current value that can be balanced and controlled until the number of rotations of the motor 10 is generated, and then the current at the balanced hydraulic pressure is supplied to smoothly increase the pressure (second energizing means). The pressure increase control valve 6 is open, and the pressure decrease control valve 7 is closed.
FIG. 8 is a diagram showing where the relationship between the current and the balance fluid pressure changes when balance control is performed using the characteristics of the current and the balance fluid pressure. The position when a high current is passed in the initial stage of current control is (1) in the figure, and here, the valve stroke moves and the proportional control is possible. Balance control is possible at this point when the fluid pressure is high, but the initial fluid pressure is close to zero, so by lowering the current value after that, it moves on the characteristic diagram of the closed to open current and the balance fluid pressure. (2) It moves to the position which enables balance control even with a low fluid pressure. Thereafter, the current value increases as the hydraulic pressure increases, and moves to the position (3) until it is held and reduced.
In this way, when performing balance control for controlling the actual wheel cylinder pressure to the target wheel cylinder pressure by utilizing the balance of the differential pressure of the gate-out valve 8 which is a proportional control valve that is normally open during pressure increase, the gate-out valve 8 A large amount of current is flowed once. By moving to a valve stroke that can be proportionally controlled by this, and then reducing to a current necessary for balance control, current control of the characteristic portion that cannot be proportionally controlled at the initial stage between fully open and fully closed is not performed. Using the characteristic that the controllability of closing to opening is proportional, it is possible to perform proportional control again from opening to closing. Therefore, proportional control can be performed satisfactorily even from a low current value at the initial stage of pressure increase, and highly accurate proportional control can be realized even with a proportional control valve having low control performance.
In addition, the configuration of the gate-out valve 8 that is a proportional control valve is simplified and made inexpensive, the current value is reduced to suppress heat generation, and the proportional control valve with low control performance with improved durability is in good proportion. Control can be performed. Conventionally, in a proportional control valve with low control performance, it has been necessary to configure a feedback loop that corrects hydraulic pressure control using a wheel cylinder pressure sensor to follow a target value. However, in the configuration of the first embodiment, the control can be performed with good characteristics, so that the hydraulic pressure control can be executed without using the wheel cylinder pressure sensor.

As described above, the effects listed below can be obtained in the first embodiment.
(1) A valve body 81, a valve seat part 82 that opens and closes the flow path by contacting the valve body 81, and a spring 83 that urges the valve body 81 in a separating direction; A gate-out valve 8 which is a normally open type proportional control valve having a solenoid 84 for generating an electromagnetic force for moving the valve body 81 in the direction of the valve seat 82 against the biasing force of the spring 83; A first energization unit 201 for energizing a solenoid 84 with a predetermined current for closing the valve body 81; and a second energization unit 202 for energizing a current lower than the predetermined current continuously after energization by the first energization unit 201; And a control unit 20 for controlling the current supplied to the solenoid 84. In other words, prior to the proportional control of the gate-out valve 8 (second energization unit 202), the solenoid 84 is energized with a current for opening the valve element 81 for a predetermined time (first energization unit 201). Therefore, high control accuracy can be obtained even when the offset load of the spring 83 is reduced while simplifying the configuration of the gate-out valve 8.
(2) It has the pump 9 driven by the motor 10, and the predetermined time indicates a short time until the pump 9 starts to rotate by applying a voltage to the motor 10, and the control unit 20 is driven by the motor 10. The first energization unit 201 energizes the current while outputting the command.
That is, using the fact that the response of the motor 10 is delayed with respect to the gate-out valve 8 (time lag until the pump 9 generates the discharge pressure), the voltage is applied to the motor 10 and the gate-out valve 8 at the same timing. By changing the value of the current to the gate-out valve 8 before starting to rotate so that the proportional control is possible, the balance control can be executed while preventing the pressure increase delay.
Although the first embodiment has been described above, the control of the present invention may be applied to a proportional control valve provided in the configuration of another hydraulic pressure control device. For example, in the first embodiment, an example in which an internal reservoir having a pressure regulating mechanism is provided has been described. However, the control of the present invention may be applied to a gate-out valve having a normal internal reservoir and a gate-in valve. .
Further, technical ideas other than the claims that can be grasped from the above embodiment will be described.
(3) a valve body, a valve seat part that opens and closes the flow path when the valve body comes into contact with the valve body, biasing means that biases the valve body in the direction of separating, and the valve The valve body closes with respect to a normally open type proportional control valve having a solenoid that generates an electromagnetic force for moving the body in the direction of the valve seat against the urging force of the urging means. A brake control method characterized by energizing a predetermined current and continuously energizing a current lower than the predetermined current after the energization. The effect of Example 1 can be obtained by this method.

1 Brake pedal 2 Booster 3 Master cylinder 4 Reservoir tank 5 Wheel cylinder 6 Pressure increase control valve 7 Pressure reduction control valve 8 Gate-out valve (proportional control valve)
9 Pump 10 Motor 11 Internal reservoir 12 Master cylinder pressure sensor 13 Check valve 20 Control unit 81 Valve body 82 Valve seat part 83 Spring 84 Solenoid
201 1st energization part (1st energization means)
202 2nd energization part (2nd energization means)

Claims (3)

A valve body, a valve seat that opens and opens the flow path by closing and separating the flow path when the valve body abuts, an urging means that urges the valve body in the direction of separating, and the valve body are attached. A normally open type proportional control valve having a solenoid that generates an electromagnetic force for moving in the direction of the valve seat against the biasing force of the biasing means;
First energization means for energizing the solenoid with a predetermined current for closing the valve body for a predetermined time; and second energization means for energizing a current lower than the predetermined current continuously after energization by the first energization means; A control unit for controlling a current flowing through the solenoid;
A pump driven by a motor;
With
The predetermined time indicates a time until the motor starts rotating by applying a voltage,
The brake control device , wherein the control unit energizes the current by the first energizing means while outputting a drive command to the motor. The brake control device according to claim 1, wherein
The control unit controls the position of the valve body by proportionally controlling energization to the solenoid, and executes the first energization means prior to the proportional control . The brake control device according to claim 1 or 2,
Having a pump driven by a motor;
The predetermined time indicates a short time until the pump starts discharging by applying a voltage to the motor,
The brake control device according to claim 1, wherein the control unit energizes the first energizing unit while outputting a drive command to the motor.

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