JP7327154B2 - Braking control device - Google Patents

Description

The present invention relates to a braking control device.

In recent years, EPBs (Electric Parking Brakes) have been widely used in vehicles such as passenger cars. EPB control includes lock control and release control. In the lock control, for example, the motor is rotated forward to move the direct-acting member, thereby moving the braking member in a direction closer to the member to be braked that rotates together with the wheels of the vehicle. In the release control, for example, the motor is reversely rotated to move the linear motion member in the reverse direction, thereby moving the braking member away from the member to be braked.

Further, for example, when a wheel targeted for EPB slips while the vehicle is running and antilock control is executed using EPB, lock control and release control are alternately repeated. In that case, assuming that there is no mechanism for directly detecting the position of the linear motion member, the position of the linear motion member is the initial position of the linear motion member and the time during which the current is supplied to the motor in lock control. It is estimated using the power supply time and the release power supply time, which is the time during which current is supplied to the motor in release control.

Also, in the release control when the operation of the EPB is terminated, the estimated position of the linear motion member is used to move the linear motion member to the initial position.

JP 2015-203458 A

However, in the above-described prior art, due to an error in the detected value of the drive current of the motor, etc., excessive movement of the linear motion member during release control when ending the operation of the EPB, that is, so-called over-release. I had it happen. If excessive release occurs, the direct-acting member may come into contact with other members, which is not preferable. In addition, depending on the structure of the EPB, for example, there is a concern that the linear motion member may be insufficiently moved during the release control. inadequate condition) can occur.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a braking control device capable of suppressing over-release or under-release in an electric parking brake.

A braking control device according to the present invention, in an electric parking brake, rotates a motor in the forward direction to move a linear motion member in the forward direction so that the braking member that moves in conjunction with the linear motion member is integrated with the wheel of the vehicle. lock control to move the braking member in a direction approaching the rotating member to be braked; and a braking control device that executes a release control that causes the The braking control device adds a lock power supply time, which is a time during which current is supplied to the motor in the lock control, to a counter related to a current supply time to the motor, and supplies current to the motor in the release control. The estimated position of the linear motion member is calculated by subtracting the release power supply time, which is the time when the linear motion member is set to the initial position when the release control is executed when the operation of the electric parking brake is terminated. a control unit for setting a target release power supply time, which is a target power supply time to the motor for moving the motor according to the estimated position; and a determination unit that determines. When the determination unit determines that the braking member has come into contact with the braked member, the control unit changes the value of the counter to a predetermined value to correct the estimated position.

FIG. 1 is a schematic side view of the brake device of the embodiment as seen from the outside in the vehicle width direction. FIG. 2 is a schematic side view of the operation of the braking member by the moving mechanism of the braking device of the embodiment, in a non-braking state. FIG. 3 is a schematic cross-sectional view of the electric actuator of the embodiment in a braking state. FIG. 4 is a block diagram showing the functional configuration of the braking control device and the like in the embodiment. FIG. 5 is a time chart showing how each element changes over time when the brake device is operated in the embodiment. FIG. 6 is a flow chart schematically showing processing executed by the braking control device in the embodiment.

Illustrative embodiments of the invention are disclosed below. The configurations of the embodiments and modifications shown below, and the actions and results (effects) brought about by the configurations are examples. The present invention can be realized by configurations other than those disclosed in the following embodiments and modifications. Moreover, according to the present invention, it is possible to obtain at least one of various effects (including derivative effects) obtained by the configuration.

First, with reference to FIGS. 1 to 3, the outline of the structure of the brake device 2 (an example of an electric parking brake) will be described. FIG. 1 is a side view of the braking device 2 from the outside in the vehicle width direction. FIG. 2 is a side view showing the movement of the brake shoe 3 (an example of the braking member) by the moving mechanism 8 of the brake device 2, in a non-braking state. FIG. 3 is a cross-sectional view of the electric actuator 100 of this embodiment in a braking state.

The braking device 2 is a so-called drum brake. The brake device 2 has two brake shoes 3 which are spaced apart in the front-rear direction. The two brake shoes 3 extend arcuately along an inner peripheral surface 4a of a cylindrical drum rotor 4 (an example of a member to be braked). The drum rotor 4 rotates integrally with a wheel (not shown) around a rotation center C extending in the vehicle width direction (Y direction). The two brake shoes 3 move so as to come into contact with the inner peripheral surface 4a of the cylindrical drum rotor 4. As shown in FIG. As a result, the friction between the brake shoes 3 and the drum rotor 4 brakes the drum rotor 4 and the wheels.

The brake device 2 includes, as actuators for moving the brake shoes 3, a wheel cylinder 51 operated by hydraulic pressure and a motor 120 operated by energization. The wheel cylinder 51 and motor 120 can each move two brake shoes 3 . The wheel cylinder 51 is used, for example, for braking during running, and the motor 120 is used, for example, for braking during parking. Note that the motor 120 may be used for braking during running.

Further, although detailed description is omitted, as shown in FIG. 3 , in the electric actuator 100 , the rotational force of the motor 120 is transmitted via each component to move the linear motion member 142 . The actuating member 200 receives force from the linear motion member 142 to actuate the brake shoe 3 . That is, the operating member 200 is configured such that one end (the transmission member 210) receives force from the linear motion member 142 to operate the brake shoes 3, and the other end (the end portion 150b of the cable 150) operates the brake shoes 3. ing.

Since there is no mechanism for directly detecting the position of the linear motion member 142, the position of the linear motion member 142 is estimated using the lock power supply time and the release power supply time to the motor 120 (details will be described later). ).

Further, in the release control when the operation of the electric actuator 100 (EPB) is terminated, information on the estimated position (estimated position) of the linear motion member 142 is used to move the linear motion member 142 to the initial position (also referred to as the standby position). move to However, in the prior art, as described above, for example, excessive release may occur due to an error in the detected value of the drive current of the motor. If excessive release occurs, the direct-acting member may come into contact with other members, which is not preferable.

So, below, the technique which suppresses excessive release in such a brake device 2 is demonstrated.

A functional configuration of the braking control device 400 and the like in the embodiment will be described with reference to FIG. 4 . FIG. 4 is a block diagram showing the functional configuration of the braking control device 400 and the like in the embodiment.

Various sensors 500 are connected to the braking control device 400 . The various sensors 500 are, for example, an acceleration sensor, a gyro sensor, a current sensor, a temperature sensor, etc. provided in the vehicle.

The braking control device 400 constitutes a part of a brake ECU (Electronic Control Unit) having hardware such as a processor, memory, and the like similar to those of a normal computer, for example. Note that the brake control device 400 may be integrated with other parts of the brake ECU, or may be configured separately from the other parts.

The braking control device 400 includes an acquisition unit 401, a determination unit 402, and a control unit 403 as functional configurations. The acquisition unit 401 acquires various sensor values from the various sensors 500 .

The determination unit 402 determines whether or not the brake shoe 3 (braking member) contacts the drum rotor 4 (braked member) during lock control. For example, the determination unit 402 determines whether or not the brake shoe 3 has come into contact with the drum rotor 4 enough to generate a braking force during lock control. That is, for example, when the wheel targeted by the brake device 2 slips during operation of the brake device 2, and when the detected value of the drive current of the motor 120 becomes equal to or greater than a predetermined current value, the determination unit 402 It is determined that the brake shoe 3 comes into contact with the drum rotor 4 in at least one of the following cases.

The control unit 403 executes various controls. For example, the control unit 403 executes lock control and release control by controlling the electric actuator 100 . In the lock control, the control unit 403 rotates the motor 120 in the forward direction to move the linear motion member 142 in the forward direction so that the brake shoe 3, which moves in conjunction with the linear motion member 142, is integrated with the wheel of the vehicle. It is moved in a direction approaching the rotating drum rotor 4 .

In the release control, the control unit 403 rotates the motor 120 in the reverse direction to move the linear motion member 142 in the reverse direction, thereby moving the brake shoe 3 away from the drum rotor 4 .

In addition, the control unit 403 adds a lock power supply time, which is a time during which current is supplied to the motor 120 in lock control, to a counter related to the time during which current is supplied to the motor 120 (current supply time), and in release control, The estimated position of the direct-acting member 142 is calculated by subtracting the release power supply time, which is the time during which the current is supplied to the motor 120 . Further, when the control unit 403 executes release control when terminating the operation of the brake device 2, the control unit 403 supplies target power to the motor 120 for moving the linear motion member 142 to the initial position according to the estimated position. Set the time as the target release feed time.

Further, when the determination unit 402 determines that the brake shoe 3 has come into contact with the drum rotor 4, the control unit 403 changes the value of the counter to a predetermined value to correct the estimated position to a predetermined position on the initial position side. do. The above-mentioned predetermined value is, for example, when the contact between the brake shoe 3 and the drum rotor 4 is reached when the direct-acting member 142 is moved from the state in which the brake shoe 3 and the drum rotor 4 are in contact with each other to the initial position side. This is a preset value corresponding to the position of the linear motion member 142 when the brake shoe 3 and the drum rotor 4 do not even drag after the brake shoe 3 is released.

Note that the above-described predetermined value is obtained, for example, from the value of the current supplied to the motor 120 (no-load current) when the brake shoe 3 and the drum rotor 4 are in a non-contact state where no drag occurs. A value may be set that corresponds to the position at which an increase starts with the start of dragging between the two.

Each of the units 401 to 403, which are these functional configurations, are realized, for example, as a result of execution of various programs stored in the memory by the processor of the braking control device 400. FIG. Part or all of these functional configurations may be realized by a dedicated circuit or the like.

Next, with reference to FIG. 5, how each element changes over time when the brake device 2 is operated in the embodiment will be described. FIG. 5 is a time chart showing how each element changes over time when the brake device 2 is operated in the embodiment. In addition, here, one wheel which is the object of the brake device 2 among a plurality of wheels (for example, four wheels) of the vehicle will be described.

As shown in (a), the vehicle body speed is substantially constant. Further, as shown in (b), the wheel speed changes, and the wheel slips midway. At time t5, the determination unit 402 determines that the slip occurs in the wheel and the braking force is generated during the lock control. It is determined that the brake shoe 3 has come into contact with the drum rotor 4 .

Further, as shown in (c), the EPB switch provided near the driver's seat is switched from ON to OFF at time t12.

Also, here, antilock control is executed while the vehicle is running. For example, as shown in (e), there are lock requests (lock control requests) at times t1 to t2, times t3 to t4, and times t10 to t11. Release requests (requests for release control) are issued at times t6 to t7, t8 to t9, and t12 to t13. Accordingly, as shown in (d), the current value of the motor 120 (detected drive current value) changes. Further, as shown in (f), the counter value related to the estimated position of the direct-acting member 142 and the time during which the current is supplied to the motor 120 changes. Specifically, the control unit 403 calculates the estimated position of the linear motion member 142 by adding the lock power supply time and subtracting the release power supply time from the counter.

At time t5, the determination unit 402 determines that the brake shoe 3 has come into contact with the drum rotor 4, so the control unit 403 corrects the estimated position of the direct-acting member 142 to the predetermined position value on the initial position side. Therefore, the value of the counter is changed to a predetermined value.

After that, at time t12, the EPB switch is switched from ON to OFF, and the control unit 403 performs target release control according to the corrected estimated position in order to execute release control when terminating the operation of the brake device 2. Set the power supply time.

Next, with reference to FIG. 6, processing executed by the braking control device 400 in the embodiment will be described. FIG. 6 is a flow chart schematically showing the processing executed by the braking control device 400 in the embodiment.

First, in step S1, the control section 403 determines whether or not the EPB switch is ON. If Yes, the process proceeds to step S2, and if No, the process returns to step S1.

In step S2, the control unit 403 determines whether or not there is a lock request. If Yes, the process proceeds to step S3, and if No, the process proceeds to step S5.

In step S3, the control unit 403 executes lock control. Next, in step S4, the control unit 403 adds the lock power supply time to the value of the counter. After step S4, the process proceeds to step S5.

In step S5, the control unit 403 determines whether or not there is a release request. If Yes, the process proceeds to step S6, and if No, the process proceeds to step S8.

In step S6, the control unit 403 executes release control. Next, in step S7, the control unit 403 subtracts the release power supply time from the value of the counter. After step S7, the process proceeds to step S8.

In step S8, the determination unit 402 determines whether or not the brake shoe 3 (braking member) has come into contact with the drum rotor 4 (braked member). Proceed to S10.

In step S9, the control unit 403 changes the value of the counter so as to correct the estimated position to a predetermined position closer to the initial position. After step S9, the process proceeds to step S10.

In step S10, the control unit 403 determines whether or not the EPB switch is OFF. If Yes, the process proceeds to step S11, and if No, the process returns to step S2.

In step S<b>11 , the control unit 403 sets a target release power supply time according to the estimated position in order to execute release control when the operation of the brake device 2 is terminated. Next, in step S12, the control unit 403 executes release control.

In this manner, according to the braking control device 400 of the present embodiment, while the control unit 403 adds the lock power supply time and subtracts the release power supply time, the determination unit 402 determines whether the braking force is increased during the lock control. When it is determined that the brake shoe 3 has contacted the drum rotor 4 to such an extent that it occurs, the value of the counter is changed to a predetermined value in order to correct the estimated position of the linear motion member 142 to a predetermined position on the initial position side. Then, when executing release control when terminating the operation of the brake device 2, the control unit 403 sets the target release power supply time according to the corrected estimated position, and executes the release control. Thereby, excessive release can be suppressed. The reason is as follows.

As described above, one cause of excessive release is an error in the current value of the motor 120 (detected drive current value). However, due to the characteristics of the motor 120, the error in the current value of the motor 120 when the brake shoe 3 is not in contact with the drum rotor 4 is the current value of the motor 120 when the brake shoe 3 is in contact with the drum rotor 4. larger than the error of That is, the detection accuracy of detecting that the brake shoe 3 has contacted the drum rotor 4 from a state of separation is higher than the detection accuracy of detecting that the brake shoe 3 has separated from the drum rotor 4 from a state of contact. is higher.

Therefore, for example, in the prior art, there is a technique of detecting (estimating) that the brake shoe has separated from the drum rotor in release control, and moving the linear motion member for a predetermined set time after that detection. Since the error in the current value of the motor is large and the detection accuracy of the separation (accuracy of detection timing) is low, the degree of suppression of over-release is small.

On the other hand, in the present embodiment, it is determined (estimated) that the brake shoe 3 has come into contact with the drum rotor 4 during lock control, and at that time the estimated position of the linear motion member 142 is corrected to a predetermined position on the initial position side. Since the value of the counter is changed to a predetermined value for this purpose, the error in the current value of the motor 120 is small, and the contact detection accuracy is high. That is, when the motor 120 is switched from a no-load state to a load state, even if the current value of the motor 120 fluctuates due to disturbance or the like, it tends to converge, so detection accuracy is high. Furthermore, as in the present embodiment, by making it a condition that it is determined that the brake shoe 3 has come into contact with the drum rotor 4 enough to generate a braking force during lock control, the effect of improving the detection accuracy is further improved. becomes suitable.

Further, by using the occurrence of wheel slip and the current value of the motor 120 exceeding a predetermined current value as a condition for determining that the brake shoe 3 has come into contact with the drum rotor 4, high reliability can be achieved. can be processed.

Further, the predetermined value may be, for example, a preset value of the brake shoe 3 and the drum rotor 4 when the direct-acting member 142 is moved to the initial position side from the state in which the brake shoe 3 and the drum rotor 4 are in contact with each other. It is possible to use a value corresponding to the position of the linear motion member 142 at the time when the abutment between the brake shoe 3 and the drum rotor 4 is released, for example, so-called drag between the brake shoe 3 and the drum rotor 4 does not occur. As a result, the estimated position of the direct-acting member 142 when it is determined by the determining unit 402 that the brake shoe 3 has come into contact with the drum rotor 4 enough to generate a braking force during lock control is can be set to a position where no drag occurs, and the release control can be accurately performed from this position as a starting point.

In addition, excessive release is suppressed by changing the value of the counter to the predetermined value to correct the estimated position of the linear motion member 142 to the predetermined position on the initial position side, and variations in the release completion position of the linear motion member 142 are reduced. Since the size can be reduced, the movable range of the linear motion member 142 can be reduced, and the size and cost of the electric actuator 100 can be reduced.

In addition, in order to directly detect the position of the linear motion member 142, a rotational load imparting mechanism such as a spring is provided at the release completion position. Compared to the method of detecting the position of 142, such a mechanism is unnecessary, and the size and cost of the electric actuator 100 can be reduced.

Although the embodiment of the present invention has been described above, the above-described embodiment is merely an example and is not intended to limit the scope of the invention. The novel embodiments described above can be implemented in various forms, and various omissions, replacements, or modifications can be made without departing from the scope of the invention. Moreover, the above-described embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

For example, when the left rear wheel and the right front wheel of the vehicle are provided with respective brake devices 2, by executing the control as described above for each brake device 2, both the two rear wheels are over-released. can be suppressed. That is, for example, even if the timings of lock control and release control in each brake device 2 are different in antilock control, excessive release can be suppressed.

In the above example, the "predetermined value" for changing the counter value when it is determined that the braking member has come into contact with the member to be braked during lock control is set so that the braking member and the receiving member do not even drag. Although the value corresponds to the position of the direct-acting member when contact with the braking member is released, the value is not limited to this. The "predetermined value" is, for example, a value corresponding to a state in which the braking force is smaller than the contact state between the braking member and the member to be braked, which is the condition for the above determination (state in which the linear motion member is closer to the initial position). If it is

In the above example, when the determining unit determines that the braking member has come into contact with the member to be braked during lock control, the estimated position of the linear motion member is corrected to a predetermined position on the initial position side to prevent over-release. A suppressing aspect has been described. Alternatively, for example, when the determining unit determines that the braking member has come into contact with the member to be braked during lock control, the estimated position of the linear motion member is corrected to a predetermined position on the opposite side of the initial position and released. You may adopt the aspect which suppresses insufficiency. The latter is particularly useful, for example, when the structure of the brake device tends to cause drag between the braking member and the member to be braked due to insufficient release.

Further, the predetermined value described above may also be set in consideration of the mechanical (structural) determination time required for the brake device 2 with respect to the determination.

Further, the scope of application of the present invention is not limited to drum brakes, and may be applied to disk brakes.

2 Brake device 3 Brake shoe (braking member) 4 Drum rotor (braked member) 100 Electric actuator 120 Motor 142 Linear motion member 150 Cable 150b End (other end) ), 200... Operating member, 210... Transmission member (one end).

Claims (4)

In the electric parking brake,
By rotating the motor forward to move the linear motion member in the forward direction, the brake member that moves in conjunction with the linear motion member moves in a direction approaching the member to be braked that rotates integrally with the wheels of the vehicle. control and
release control for moving the braking member away from the member to be braked by rotating the motor in reverse to move the linear motion member in the opposite direction;
A braking control device that performs
A lock power supply time, which is the time during which the current is supplied to the motor in the lock control, is added to a counter related to the current supply time to the motor, and a release power supply, which is the time during which the current is supplied to the motor during the release control. When the estimated position of the linear motion member is calculated by subtracting the time, and the release control is executed when the operation of the electric parking brake is terminated, the linear motion member is moved to the initial position. a control unit that sets a target release power supply time, which is a target power supply time to the motor, according to the estimated position;
a determination unit that determines that the braking member has come into contact with the braked member during the lock control;
The braking control device according to claim 1, wherein, when the determination section determines that the braking member has come into contact with the braked member, the control section changes the value of the counter to a predetermined value to correct the estimated position. The determination unit is configured to determine at least when a slip occurs in the wheel targeted by the electric parking brake during operation of the electric parking brake and when the detected value of the driving current of the motor becomes equal to or greater than a predetermined current value. 2. The braking control device according to claim 1, wherein it is determined that said braking member comes into contact with said member to be braked in either case. 3. The braking according to claim 1, wherein, in correcting the estimated position, the control unit changes the value of the counter to the predetermined value so as to correct the estimated position to a predetermined position closer to the initial position. Control device. The predetermined value is a predetermined value, which is a difference between the braking member and the member to be braked when the direct-acting member is moved from the state in which the braking member and the member to be braked are in contact with each other to the initial position side. 4. The braking control device according to claim 3, wherein the value corresponds to the position of the direct-acting member when the abutment is released.

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