JP6191142B2 - Electric parking brake control device - Google Patents

Description

  The present invention relates to an EPB control device applied to a vehicle brake system having an electric parking brake (hereinafter referred to as an EPB (Electric parking brake)).

  Conventionally, Patent Document 1 proposes an electric disk brake that can perform failure diagnosis of an EPB without an EPB operation. In this electric disc brake, the EPB driving motor is driven to rotate forward and backward in a region where no braking force is generated, and the failure of the EPB is detected from the motor current value and the motor displacement value at that time. An abnormal measure such as warning the driver is performed.

JP 2007-203821 A

  In the electric disc brake described in Patent Document 1 described above, failure diagnosis is performed by driving the motor when the braking force by EPB is not generated, that is, when the wheel is in the released state instead of the locked state. However, if the motor is driven in order to perform a failure diagnosis every time the release state is established, the motor or the like may be deteriorated, resulting in a problem that the durability performance is deteriorated.

  Failure diagnosis is usually performed at the time of initial check when the ignition switch (hereinafter referred to as IG) is turned on. In the case of EPB, the braking force is generated by EPB during parking and the wheels are locked. Therefore, it is not preferable to rotate the motor in this state. For this reason, if the failure diagnosis of the EPB is performed when the IG is turned on, it is assumed that the release state is set as a condition, but in that case, the failure occurs every time it is in the release state. Diagnosis will be performed and the above problem will occur.

  In view of the above, the present invention suppresses excessive failure diagnosis by suppressing the frequency of EPB failure diagnosis, and suppresses deterioration of durability performance due to deterioration of a motor or the like. An object of the present invention is to provide an EPB control device capable of performing

  In order to achieve the above object, in the invention according to any one of claims 1 to 7, in the EPB control device, a release state determination means (110) for determining whether or not the release state is established, and a release that is a duration of the release state Release time integrating means (120) for integrating time, continuous time determining means (130) for determining whether or not the release time has reached the continuation determination time, and motor ( It is characterized by comprising failure diagnosis means (140 to 160) for performing failure diagnosis of EPB (2) by driving 10) forwardly.

  In this way, the release time, which is the duration of the release state, is measured, and when the release time reaches the continuation determination time, the motor is driven for failure diagnosis at a predetermined timing. Thereby, it becomes possible to perform failure diagnosis of EPB (2) at an appropriate frequency, and it is possible to suppress excessive failure diagnosis. Therefore, it is possible to prevent the motor (10) and the like from being deteriorated due to frequent use, and it is possible to suppress the deterioration of the durability performance of the motor (10) and the like.

  The invention according to claim 2 is characterized in that the duration determination means (130) sets the duration determination time to a shorter time as the number of times the EPB (2) is used increases.

  In this way, considering the aging of EPB (2), the continuation determination time can be made variable according to the number of times EPB (2) is used. As a result, failure diagnosis can be performed with a higher frequency after aging deterioration when failure is likely to occur, and it is possible to detect failure at an earlier timing when a failure occurs.

  In the invention according to claim 3, the failure diagnosis means (140 to 160) includes a start intention determination means (150) for determining whether or not the driver intends to start the vehicle. When there is a start intention, the parking brake force The failure diagnosis is performed in such a manner that the motor (10) stops the forward rotation before generating the release, and then the release operation is performed. If there is no intention to start, the motor (10) is driven forward until the parking brake force is generated. It is characterized by performing failure diagnosis in the form of a release operation afterwards.

  In this way, it is possible to prevent parking brake force from being generated for failure diagnosis when there is a driver's intention to start, and to prevent the driver from feeling uncomfortable due to the effect of failure diagnosis. It becomes possible.

  For example, as described in claim 4, the release time accumulation means (120) can perform the accumulation of the release time only while the EPB control device is activated. In this case, as described in claim 5, the release time correction means (125) for correcting the release time by adding the time corresponding to the time not in operation to the release time is provided, and the duration determination means ( 130), it is preferable to determine whether or not the corrected release time has reached the continuation determination time or more.

  This makes it possible to bring the release time closer to the more accurate release time while taking into account the release time during IG off. Then, it is possible to determine whether or not failure diagnosis should be performed based on a more accurate release time.

  Furthermore, as the operation timing for driving the motor (10) to rotate forward, for example, as described in claim 6, the timing at which the IG in the vehicle is switched from on to off or the timing from when off to on is switched on. Can do. Further, as described in claim 7, the operation timing can be set when the shift position is the parking position or the neutral position in the stop state.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows an example of a corresponding relationship with the specific means as described in embodiment mentioned later.

1 is a schematic diagram showing an overall outline of a vehicle brake system to which an EPB control device according to a first embodiment of the present invention is applied. It is the flowchart which showed the detail of the failure diagnosis control process of EPB2 in parking brake control. It is the time chart which showed an example of the normal waveform and abnormal waveform of the motor current at the time of lock operation. It is a time chart when performing a failure diagnosis control process. It is a time chart when performing a failure diagnosis control process. It is a time chart when performing a failure diagnosis control process. It is the graph which showed an example of the relationship between the motor operation frequency corresponding to the frequency | count of use of EPB2, and continuation determination time. It is a time chart when failure diagnosis control processing is executed after aging. It is the flowchart which showed the detail of the failure diagnosis control process of EPB2 concerning 3rd Embodiment of this invention. It is a time chart at the time of performing a release time correction process.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A first embodiment of the present invention will be described. In the present embodiment, a vehicle brake system in which a disc brake type EPB is applied to the rear wheel system will be described as an example. FIG. 1 is a schematic diagram showing an overall outline of a vehicle brake system to which an EPB control device according to the present embodiment is applied. Hereinafter, a description will be given with reference to this figure.

  As shown in FIG. 1, the brake system includes a service brake 1 that generates a braking force based on a pedaling force of a driver, and an EPB 2 that locks a wheel during parking and restricts the movement of the vehicle.

  The service brake 1 boosts the pedal force according to the depression of the brake pedal 3 by the driver with the booster 4, and then applies the brake fluid pressure according to the boosted pedal force to the master cylinder (hereinafter referred to as M / C). The braking force is generated by transmitting the brake fluid pressure to each W / C 6 provided in the brake mechanism of each wheel. In addition, an actuator 7 for adjusting the brake fluid pressure is provided between the M / C 5 and the W / C 6 to adjust the brake force generated by the service brake 1 and improve the safety of the vehicle. Therefore, it is structured such that various types of control (for example, ABS control) can be performed.

  Various controls using the actuator 7 are executed by an ESC (Electronic Stability Control) -ECU 8. For example, the brake fluid pressure circuit provided in the actuator 7 is controlled by outputting a control current for controlling various control valves and pump driving motors provided in the actuator 7 from the ESC-ECU 8, and the W / C Control the pressure. For example, during normal braking, the actuator 7 transmits the M / C pressure generated in the M / C 5 to the W / C 6 as it is. However, during ABS control, the actuator 7 controls on / off of various control valves and drives the pump. By controlling this motor, the W / C pressure is increased or decreased so that wheel lock can be avoided. In addition, the actuator 7 can automatically increase the W / C pressure by driving various control valves and a pump driving motor. When the M / C pressure is not generated or when the M / C pressure is higher than the M / C pressure, When it is desired to generate the C pressure, a high braking force can be generated based on the automatic pressurizing function. The structure of the actuator 7 has been well known in the art and will not be described in detail. However, the actuator 7 has a configuration including various control valves, a pump, a pump driving motor, and the like.

  On the other hand, the EPB 2 is controlled by an EPB control device (hereinafter referred to as “EPB-ECU”) 9 and drives the motor 10 by the EPB-ECU 9 to control the brake mechanism to generate a braking force.

  The EPB-ECU 9 is constituted by a well-known microcomputer having a CPU, ROM, RAM, I / O, and the like. The EPB-ECU 9 controls the rotation of the motor 10 according to a program stored in the ROM and the like. Parking brake control such as failure diagnosis control of EPB2 is performed. The EPB-ECU 9 and the ESC-ECU 8 exchange information with each other through CAN communication that is an in-vehicle LAN, and the EPB-ECU 9 performs vehicle parking brake control, such as vehicle speed information handled by the ESC-ECU 8. Can be obtained.

  In addition, the EPB-ECU 9 inputs, for example, a signal corresponding to an operation state of an operation switch (SW) 20 provided in an instrument panel (not shown) in the passenger compartment, or a detection signal of the shift position sensor 21, The motor 10 is driven based on the operation state of the SW 20 and the shift position of the vehicle. Further, the EPB-ECU 9 outputs a signal indicating whether it is locked or released according to the driving state of the motor 10 to the lock / release display lamp 22 provided in the instrument panel, When a failure of the EPB 2 is detected, a signal indicating that is output to the display device 23.

  Specifically, the EPB-ECU 9 detects the current (motor current) flowing through the motor 10 on the upstream side or the downstream side of the motor 10, and the target motor current (target current value when the lock control is ended) ) To calculate the target motor current, to determine whether or not the motor current has reached the target motor current, and to control the EPB2 based on the operation state of the operation SW 20, etc. ing. The EPB-ECU 9 controls the EPB 2 by rotating the motor 10 forward or backward based on the state of the operation SW 20 or the motor current or stopping the rotation of the motor 10.

  The brake mechanism provided in each wheel has a mechanical structure that generates a braking force in the brake system of the present embodiment, and the brake mechanism of the front wheel system has a structure that generates a braking force by operating the service brake 1. However, the brake mechanism of the rear wheel system has a common structure that generates a braking force for both the operation of the service brake 1 and the operation of the EPB 2. The front-wheel brake mechanism is a brake mechanism that is generally used from the past, in which a mechanism that generates a braking force based on the operation of the EPB 2 is eliminated from the rear-wheel brake mechanism. That is, the front-wheel brake mechanism generates a braking force for each wheel by pressing the brake pad 11 against the brake disk 12 as the driver operates the service brake 1. The rear wheel brake mechanism generates a braking force for each wheel by pressing the brake pad 11 against the brake disc 12 in accordance with the operation of the EPB 2 in addition to the operation of the service brake 1 by the driver.

  The brake mechanism that generates braking force by operating the front wheel service brake 1 is conventionally used, and generates braking force in response to the operation of the rear wheel service brake 1 and EPB 2. The brake mechanism to be used is also known in, for example, Japanese Patent Application Laid-Open No. 2010-58536. For this reason, description of a detailed structure is abbreviate | omitted here.

  Next, parking brake control executed by the EPB-ECU 9 using a program stored in the various functional units and a built-in ROM (not shown) using the brake system configured as described above will be described. However, since normal lock control and release control in the parking brake control are the same as those in the past, here, the failure diagnosis control of the EPB 2 which is a feature of the present invention will be described.

  FIG. 2 is a flowchart showing details of the failure diagnosis control process of EPB 2 in the parking brake control. This process is executed at predetermined control cycles when, for example, the IG is turned on and the EPB-ECU 9 is activated.

  First, in step 100, a vehicle state acquisition process is performed. As the vehicle state, the EPB2 state of whether the wheel is locked or released by the EPB2, the IG state of whether the IG is on or off, and the shift position are acquired. Specifically, when the EPB-ECU 9 executes lock control or release control, the state of the EPB 2 based on the lock control or release control is stored. Therefore, the state of the EPB 2 can be read by reading the stored contents from the EEPROM or the like provided in the EPB-ECU 9. Is getting. As for the state of the IG, the on / off state of the IG can be directly acquired. However, when the EPB-ECU 9 is activated when the IG is turned on, the failure diagnosis control process may be executed. Since it means that the IG is on, the time when the EPB-ECU 9 is activated may be the time when the IG is switched from IG off to IG on. The shift position is acquired based on the detection signal of the shift position sensor 21.

  And it progresses to step 110 and it is determined whether the state of the wheel by EPB2 is a release state. If it is not in the released state, that is, if the wheel is in the locked state, it is not the timing for performing the failure diagnosis, and therefore the process proceeds to step 120 only when an affirmative determination is made in this step.

  In step 120, release time integration processing is performed. The release time is the time corresponding to the duration when the vehicle is in the release state regardless of whether the vehicle is running or stopped, and the elapsed time since the last release state is measured As a result, the release time is accumulated. Here, the release time is integrated by obtaining the total amount of time that was in the release state while the IG was on. Since the EPB-ECU 9 is not activated during the IG off period, it is not possible to determine whether or not it is in the released state. Not included in release time. Of course, if the release time can be continuously measured even when the IG is off, the release time should be measured including that time. In that case, more accurate release time is measured. It becomes possible.

  Then, it progresses to step 130 and it is determined whether release time exceeds the continuation determination time. The continuation determination time is a time corresponding to the interval of failure diagnosis, and is a threshold value indicating that the release time, which is the continuation time of the release state, has reached the time for failure diagnosis. For example, the continuation determination time can be set in advance to a predetermined time (for example, 24 hours), and failure diagnosis can be performed every time the release time reaches the continuation determination time.

  If an affirmative determination is made here, for example, by setting a long-time continuation determination flag, it is indicated that a situation for failure diagnosis has been reached, and then the routine proceeds to step 140 where an operation timing determination process is executed. Examples of the operation timing include a timing when the IG is switched from IG off to IG on (after the IG is turned on), a timing when the IG is switched from IG on to the IG off (after the IG is turned off), and the IG is turned on. Examples of the case where the IG is on include a case where the shift position is a P (parking) position or an N (neutral) position in a stopped state. Whether the vehicle is stopped can be determined by confirming whether the vehicle speed is 0 km / h from the vehicle speed information acquired from the ESC-ECU 8. After any one of these timings is determined as the operation timing, it is determined whether or not the determined operation timing has been reached in a state in which the long-term continuation determination flag is set. .

  In step 150, the motor 10 is driven as a motor drive process, and a lock operation and a release operation are performed.

  For example, the EPB 2 includes a gear mechanism, a nut (propulsion shaft), a piston, and the like in addition to the motor 10. In such a configuration, when the motor 10 is rotated in the forward direction, the rotation is attenuated by the gear mechanism, and converted into a linear motion of the nut screwed into the male screw groove of the rotation shaft of the gear mechanism. Then, by moving the piston along with the straight movement of the nut, the brake pad 11 serving as the friction material attached to the tip of the piston is pressed against the brake disk 12 serving as the friction material, thereby generating a parking brake force. The lock operation is performed. Even after the motor 10 is stopped, the parking brake force is maintained based on the frictional force generated by the engagement between the nut and the male screw groove. Further, when the motor 10 is rotated in the reverse direction, the nut is moved in the opposite direction to the piston, and accordingly, the piston and the brake pad 11 are moved in the same direction. Then, a release operation is performed in which the brake pad 11 attached to the tip of the piston is separated from the brake disk 12 and the generated parking brake force is released.

  In order to perform the locking operation and the releasing operation in this way, as the motor driving process, first, the motor 10 is rotated forward to perform the locking operation, and then the motor 10 is rotated reversely to perform the releasing operation so that the piston and the like are released. A process of returning to the standby position is performed.

  At this time, the motor current flowing through the motor 10 is monitored. After the inrush current is generated immediately after the start of the motor driving and increases instantaneously, the motor current becomes a no-load current value, that is, a small current value within a predetermined range until the brake pad 11 is pressed against the brake disk 12. When the pad 11 is pressed against the brake disk 12, a load corresponding to the pressing force is applied and the current value increases. For this reason, since the motor current changes according to the motor drive state, the motor current is monitored by detecting the motor current, and at the time of the lock operation, the target motor current that is assumed to have generated the desired parking brake force is reached. When this occurs, the energization of the motor 10 is stopped, and then the release operation is performed to reversely rotate the motor 10 for a predetermined time.

  Then, it progresses to step 160 and an abnormality determination process is performed. The abnormality determination process is performed based on whether or not the change in the motor current monitored during the motor drive process is a desired change.

  For example, the normal waveform and abnormal waveform of the motor current have shapes as shown in FIGS. That is, as shown in FIG. 3A, the normal waveform of the motor current reaches the no-load current value included in the predetermined range after the inrush current is generated immediately after the start of the motor driving, and then at a predetermined gradient. The waveform rises. On the other hand, for example, when EPB2 is not used for a long time and the gear is bitten and fixed, or an operational amplifier provided in the motor current detection circuit fails and cannot output a change in motor current. As shown in FIG. 3B, the motor current does not decrease to a predetermined range after the inrush current. Further, when the gain of the operational amplifier provided in the motor current detection circuit is increased due to a failure, the increase gradient of the motor current after the no-load current is larger than that in the normal state as shown in FIG.

  Therefore, by determining whether or not the motor current becomes a current value within a predetermined range after the inrush current, or by determining whether or not the subsequent increase gradient is a desired gradient, the change in the motor current is desired. It is determined whether or not it is a change, and if it is a desired change, it is determined as normal, and if it is not a desired change, it is determined as abnormal.

  Then, it progresses to step 170 and a display treatment process is performed. For example, if it is determined in the abnormality determination process in step 160 that an abnormality has occurred, a signal indicating that a failure of EPB 2 has been detected is output to the display device 23, and the failure of EPB 2 is displayed on the display device 23. As a result, the driver can recognize the failure of EPB2.

  If a negative determination is made in step 110 described above or a negative determination is made in step 130, the failure diagnosis is not performed, so the process proceeds to step 170 and processing is performed without indicating that a failure has been detected as a display procedure. Exit.

  4 to 6 are time charts when the failure diagnosis control process is executed as described above. In FIG. 4, in the operation timing determination process, a case where the timing for driving the motor is the timing when the IG is switched from IG off to IG on is exemplified. FIG. 5 shows an example in which the timing for driving the motor is the timing at which the IG is switched from IG on to IG off in the operation timing determination process. In FIG. 6, in the operation timing determination process, an example is given in which the timing for driving the motor is determined to be a stopped state while the IG is on and the shift position is the P position.

  As shown in FIG. 4 to FIG. 6, when the driver is IG-on at time T1 and the previous release operation is performed by operating the operation SW 20, the release that is the duration of the release state with that timing as the start timing Time accumulation starts. Then, the release time is integrated after the time T1 to T2 when the IG is on and the time T3 when the IG is switched from the IG off to the IG on again, and if the release time exceeds the continuation determination time as a threshold at the time T4, The continuation determination flag is set to indicate that a situation for failure diagnosis has been reached.

  Therefore, as shown in FIG. 4, when the timing for driving the motor is the timing when the IG is turned off to the IG on, the timing when the IG is turned off at the time T5 and then turned on again at the time T6. Then, the motor drive is turned on, and the failure diagnosis of EPB2 is performed. Further, as shown in FIG. 5, when the timing for performing the motor driving is the timing when the IG is switched from IG on to IG off, the motor driving is turned on at the timing when the IG is switched from IG on to IG off at the time T5. Failure diagnosis of EPB2 is performed. Similarly, as shown in FIG. 6, when it is determined that the timing for performing the motor drive is a stopped state while the IG is on and the shift position is the P position, at time T5, At the timing when the shift position is the P position, the motor drive is turned on, and the failure diagnosis of EPB2 is performed.

  As described above, in this embodiment, the release time that is the duration of the release state is measured, and when the release time reaches the continuation determination time, the motor is driven for failure diagnosis at a predetermined timing. Yes. In this way, if the motor is driven when the release time reaches the continuation determination time, it is possible to carry out failure diagnosis of EPB 2 at an appropriate frequency, and that failure diagnosis is performed excessively. Can be suppressed. Therefore, it is possible to prevent the motor 10 and the like from being deteriorated due to frequent use, and it is possible to suppress the deterioration of the durability performance of the motor 10 and the like.

(Second Embodiment)
A second embodiment of the present invention will be described. In this embodiment, the continuation determination time is made variable with respect to the first embodiment, and the others are the same as those in the first embodiment. Therefore, only the parts different from the first embodiment will be described.

  As described above, in the failure diagnosis control process shown in FIG. 2, the continuation determination time is set as a threshold for determining that the release time has continued for a predetermined time, and on condition that the release time has reached the continuation determination time, Thereafter, when a desired operation timing is reached, motor driving for failure diagnosis is performed. The continuation determination time at this time can be set as a predetermined time in advance as described in the first embodiment. However, taking into consideration that the EPB 2 deteriorates over time, the continuous determination time depends on the deterioration over time. It is also possible to variably set so that failure diagnosis is performed at appropriate time intervals.

  Therefore, in this embodiment, the continuation determination time is corrected according to the number of times EPB2 is used. FIG. 7 is a graph showing an example of the relationship between the motor operation count corresponding to the EPB2 use count and the continuation determination time.

  It is considered that the aging deterioration of EPB2 progresses as the motor operation frequency increases. Therefore, as shown in FIG. 7, the continuation determination time becomes the first predetermined time (for example, 24 hours) until the motor operation number reaches the first predetermined number (for example, 50,000 times), and then the motor operation number is set to the second predetermined number of times. The continuation determination time can be gradually reduced so that the continuation determination time becomes a second predetermined time (for example, 12 hours) shorter than the first predetermined time at the number of times (for example, 100,000 times). That is, the continuation determination time is set to be shorter as the number of times EPB2 is used increases. Thereby, the continuation determination time in consideration of the aging deterioration of EPB2 can be set.

  FIG. 8 is a time chart when the failure diagnosis control process is executed after aging deterioration. As shown in this figure, since the continuation determination time is reduced as compared with that before the aging deterioration, the long-time continuation determination flag is set earlier and the failure diagnosis can be performed earlier. FIG. 8 shows an example in which the timing for performing the motor drive is determined to be a stop state while the IG is on and the shift position is the P position. However, the IG is switched from IG off to IG on. The same can be said for the timing or the timing when the IG is switched from IG on to IG off.

  In this way, the continuation determination time can be made variable in accordance with the number of times EPB2 is used in consideration of aging degradation of EPB2. As a result, failure diagnosis can be performed with a higher frequency after aging deterioration when failure is likely to occur, and it is possible to detect failure at an earlier timing when a failure occurs.

(Third embodiment)
A third embodiment of the present invention will be described. In this embodiment, the release time can be corrected when the release time cannot be measured while the IG is off with respect to the first embodiment, and the rest is the same as the first embodiment. Only parts different from the first embodiment will be described.

  In the failure diagnosis control process, if the release time can be measured only while the IG is on and cannot be measured while the IG is off, the release state is actually continued even while the IG is off, so the release time is an accurate value. It is not. For this reason, in this embodiment, correction is performed so that the release time is closer to an accurate time.

  FIG. 9 is a flowchart showing details of the failure diagnosis control process of the EPB 2 according to the present embodiment. As shown in this figure, it is basically the same as the failure diagnosis control process described in FIG. 2 in the first embodiment, but in this embodiment, as shown in FIG. Following the process, a release time correction process is performed as step 125.

  In the release time correction process, the release time acquired by the release time integration process is corrected based on the IG off time. For example, when the elapsed time from IG off to IG on can be accurately grasped based on time information such as navigation ECU, the release time is corrected by adding the off time to the release time. If the elapsed time from IG OFF to IG ON cannot be accurately grasped, a certain time is added to the release time. For example, if it can be determined that the engine has cooled from the coolant temperature of the engine measured by a thermometer based on information such as a meter ECU, the IG is off for about 1 hour. It can be estimated that it continued. In this case, the release time is corrected by adding, for example, 1 hour as a fixed time to the release time. This makes it possible to bring the release time closer to the more accurate release time while taking into account the release time during IG off.

  In this way, when the release time is corrected, it is determined in step 130 whether or not the corrected release time has reached the continuation determination time, and the failure diagnosis should be performed based on the corrected release time. Whether or not is determined. Thereby, it is possible to determine whether or not failure diagnosis should be performed based on a more accurate release time.

  FIG. 10 is a time chart when the release time correction process is performed. As shown in this figure, the release time is corrected in consideration of the time during which the IG is off, and it is determined whether or not the duration has been determined based on the corrected release time. This makes it possible to set the timing for performing failure diagnosis based on a more accurate release time.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. This embodiment is a modification of the motor driving method when performing failure diagnosis with respect to the first to third embodiments, and the other aspects are the same as those of the first to third embodiments. Only parts different from the third embodiment will be described.

  In the failure diagnosis control process, when the timing at which the parking brake force is generated by the EPB 2 when the motor is driven overlaps with the operation of starting the vehicle by the driver, the brake is applied to start the vehicle. . For this reason, there is a possibility of giving the driver a feeling of dragging the brakes due to the influence of the failure diagnosis. In such a case, it is preferable that failure diagnosis can be performed without generating parking brake force.

  For this reason, in the present embodiment, when the motor driving process described in the first embodiment or the like is performed, the driver determines whether or not there is a start intention to start the vehicle. Thus, the time for forward rotation of the motor 10 is changed.

  Specifically, as described above, in the first to third embodiments, in the abnormality determination process performed after the motor is driven, it is determined whether or not the motor current becomes a current value within a predetermined range after the inrush current. Then, it is determined whether or not there is an abnormality by determining whether or not the subsequent increasing gradient is a desired gradient.

  On the other hand, in the present embodiment, when the driver intends to start, the motor driving is stopped before the parking brake force is generated, and whether or not the motor current becomes a current value within a predetermined range after the inrush current. The presence / absence of abnormality is determined based only on the above. If the driver does not intend to start, the motor is driven until the parking brake force is generated as in the first to third embodiments. In the abnormality determination process performed after the motor is driven, the motor current is It is determined whether or not there is an abnormality by determining whether or not the current value is within a predetermined range, or by determining whether or not the subsequent increase gradient is a desired gradient.

  In this way, it is possible to prevent parking brake force from being generated for failure diagnosis when there is a driver's intention to start, and to prevent the driver from feeling uncomfortable due to the effect of failure diagnosis. It becomes possible.

  The presence or absence of the driver's intention to start can be determined from the shift position, for example. That is, it is considered that the driver does not intend to start when the shift position is the P position or the N position in the case of an automatic vehicle, and the shift position is the N position in the case of a manual vehicle. In some cases, the driver's intention to start is considered. Therefore, it is possible to determine whether or not the driver intends to start based on the shift position.

(Other embodiments)
In the first to third embodiments, the motor driving time is until the parking brake force by the EPB 2 is generated, but the motor driving time cannot be generated by the parking brake force regardless of the driver's intention to start. It may be set to time. When the motor drive time is set until the parking brake force is generated, failure diagnosis based on the gradient when the motor current increases from the no-load current value can also be performed, so that more accurate failure diagnosis can be performed. Is obtained. Conversely, when the motor drive time is set to a time during which parking brake force cannot be generated, the motor drive time can be shortened so that failure diagnosis can be performed in a short time and the driver tries to start the vehicle. In addition, it is possible to prevent the driver from feeling uncomfortable due to the failure diagnosis.

  In addition, the brake mechanism described in each of the above embodiments has a common structure for generating a braking force for both the operation of the service brake 1 and the operation of the EPB 2, but these have different structures. It doesn't matter.

  In the above embodiment, the disc brake type EPB 2 is described as an example, but the friction surface of the brake shoe corresponding to the friction material corresponds to the friction target material by adjusting the pressure of the wheel cylinder by driving the motor. The present invention can also be applied to a drum-type EPB 2 that presses against the inner wall surface of the brake drum and generates a braking force.

  The steps shown in each figure correspond to means for executing various processes. That is, the part that executes the process of step 110 is the release state determining means, the part that executes the process of step 120 is the release time integrating means, the part that executes the process of step 125 is the release time correcting means, and the process of step 130 is executed The portion that corresponds to the duration determination means. Further, the part that executes the processing of steps 140 to 160 corresponds to the failure diagnosis means, of which the part that executes the process of step 140 is the operation timing determination means, and the part that executes the process of step 150 is the start intention determination means. Equivalent to.

  DESCRIPTION OF SYMBOLS 1 ... Service brake, 2 ... EPB, 3 ... Brake pedal, 5 ... M / C, 6 ... W / C, 7 ... Actuator, 8 ... ESC-ECU, 9 ... EPB-ECU, 10 ... Motor, 11 ... Brake pad 12 Brake disc

Claims (7)

By driving the motor (10) in the forward direction, the friction material (11) is moved in the direction toward the friction material (12) attached to the wheel to generate a parking brake force by the electric parking brake (2). The electric parking brake (2) by moving the friction material (11) in a direction away from the friction target material (12) by driving the lock to bring the wheel into a locked state and driving the motor (10) in a reverse rotation. In the electric parking brake control device that performs the release operation to release the parking brake force by
Release state determining means (110) for determining whether or not the release state;
Release time integration means (120) for integrating release time, which is the duration of the release state,
Continuation time determining means (130) for determining whether or not the release time has reached or exceeded the continuation determination time;
Failure diagnosis means (140 to 160) for performing failure diagnosis of the electric parking brake (2) by driving the motor (10) to rotate forward when the release time reaches the continuation determination time or longer. An electric parking brake control device.   The electric parking brake control device according to claim 1, wherein the duration determination means (130) sets the duration determination time to a shorter time as the number of uses of the electric parking brake (2) increases.   The failure diagnosis means (140 to 160) has a start intention determination means (150) for determining whether or not the driver intends to start the vehicle. When there is the start intention, the motor (10) is driven to rotate forward. The failure diagnosis is performed in such a manner that the release operation is performed after the parking brake force is generated, and when there is no intention to start, the motor (10) is driven to rotate forward until the parking brake force is generated. 3. The electric parking brake control device according to claim 1, wherein the failure diagnosis is performed in a form in which the release operation is performed.   The electric parking brake control device according to any one of claims 1 to 3, wherein the release time integration means (120) integrates the release time only while the electric parking brake device is activated. . Release time correction means (125) for correcting the release time by adding a time corresponding to a time when the electric parking brake device is not activated to the release time,
The electric parking brake control device according to claim 4 , wherein the duration determination means (130) determines whether or not the corrected release time has reached the duration determination time or more.
The failure diagnosis means (140 to 160) has an operation timing determination means (140) for determining an operation timing for driving the motor (10) to rotate forward for the failure diagnosis,
The operation timing determining means (140) determines, as the operation timing, a timing at which an ignition switch in a vehicle is switched from on to off or a timing at which the ignition switch is switched from off to on. The electric parking brake control device according to any one of the above. The failure diagnosis means (140 to 160) has an operation timing determination means (140) for determining an operation timing for driving the motor (10) to rotate forward for the failure diagnosis,
The electric parking according to any one of claims 1 to 5, wherein the operation timing determining means (140) determines the operation timing when the shift position is a parking position or a neutral position in a stopped state. Brake control device.

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