JP2008265669A - Electric parking brake system - Google Patents

Abstract

An electric parking brake system capable of appropriately dealing with a voltage drop of a power supply is obtained.
A voltage drop countermeasure process is provided in a program for controlling an electric parking brake. The control content is stored in the storage variable X, and the control content is executed in the subsequent processing by inputting the control content to the execution variable Y (S43). On the other hand, if it is determined in S41, 42 that the voltage is in a lowered state, the process of stopping the electric motor (Y = 0) is performed in S46 regardless of the value of the storage variable X, and the control is stopped. . Furthermore, in S47 to S50, the time during which the control is stopped is measured, and the restart of the control is prevented after the set time has elapsed (S51). According to the above processing, when the voltage drop state ends in a short time, the control is resumed, but when the voltage drop state is continued for a long time, the restart of the control is prevented to appropriately cope with the voltage drop.
[Selection] Figure 10

Description

  The present invention relates to an electric parking brake system, and more particularly to an electric parking brake that can appropriately cope with a voltage drop of a power source.

The electric parking brake presses the friction material against the brake rotator by the driving force of the electric motor to maintain the vehicle in a parked state, or moves the friction material away from the brake rotator so that the vehicle can run. is there. An example of the electric parking brake system is described in Patent Document 1 below. Patent Document 1 describes a technique for operating an electric parking brake to assist a hydraulic brake for traveling when a decrease in power supply voltage is detected. Further, in Patent Document 2 below, when a decrease in power supply voltage is detected in a traveling electric brake system that includes a speed reduction mechanism that decelerates the driving force of an electric motor and presses a friction material against a brake rotating body. A technique for reducing the drive voltage of the electric motor to the extent that the braking force at that time can be maintained using the mechanical loss of the speed reduction mechanism is described.
JP 2005-297777 A JP 2003-194116 A

However, the techniques described in Patent Documents 1 and 2 are for increasing the braking force of the vehicle as much as possible when the power supply voltage drops during traveling, and the vehicle can be driven in a parked state. There is no description on how to deal with a drop in the power supply voltage when the original function of the parking brake such as switching between different states is exhibited.
As in the above example, the conventional electric parking brake system still has room for improvement from the viewpoint of improving practicality, such as appropriately dealing with a decrease in power supply voltage. The present invention has been made in view of such circumstances, and an object of the present invention is to obtain a more practical electric parking brake system.

  In order to solve the above problems, an electric parking brake system according to the present invention includes: a control device that controls a parking brake device; a motor control unit that controls the electric motor according to an operation command; and (a) a voltage of the power source is In the voltage drop state, which is a state where the voltage drops below the set voltage, the control according to the operation command of the motor control unit is stopped, the electric motor is deactivated, and (b) when the voltage drop state is not reached. A voltage drop countermeasure unit that resumes control according to the operation command of the motor control unit, and the operation command of the motor control unit even when the voltage drop state is not satisfied when a predetermined restart prevention condition is satisfied. And a control restart prevention unit that does not restart the control according to the above.

  In the electric parking brake system according to the present invention, when a voltage drop state occurs during the control of the electric motor, the voltage drop countermeasure unit temporarily stops the motor and can resume the control when the voltage returns. In addition, when the restart prevention condition is satisfied, the control restart prevention unit can prevent the restart of the control. That is, according to the present invention, a more practical electric parking brake system can be obtained that can cope with a state where the power supply voltage is appropriately reduced.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the combinations of the constituent elements constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, the prior art, and the like. In addition, an aspect in which is added, and an aspect in which some constituent elements are deleted from the aspect of each item can also be an aspect of the claimable invention.

  In each of the following paragraphs, (1) is in claim 1, (2) is in claim 2, (3) is in claim 3, (4) is in claim 4, (5) ) Corresponds to claim 5, (8) corresponds to claim 6, and (11) corresponds to claim 7.

(1) A parking brake device that includes an electric motor, presses the friction material against the brake rotating body by the driving force of the electric motor to generate a braking force, and maintains the braking force when the electric motor is in an inoperative state;
Power supply,
An electric parking brake system including a control device for controlling the parking brake device,
The control device is
A motor control unit for controlling the electric motor in accordance with an operation command;
(a) In a voltage drop state in which the voltage of the power source is lowered below a set voltage, the control according to the operation command of the motor control unit is stopped, and the electric motor is inactivated, and (b) the A voltage drop coping unit that resumes control according to the operation command of the motor control unit when the voltage drop state is no longer present;
And a control restart prevention unit for preventing restart of control according to the operation command of the motor control unit even when the voltage drop state is not achieved when a predetermined restart prevention condition is satisfied. Parking brake system.
The electric parking brake system of this section (hereinafter abbreviated as “electric PKB system” unless otherwise required) controls an electric motor (hereinafter abbreviated as “motor” unless otherwise required), A braking force is generated. Therefore, in a state where the voltage of the power source is lowered (voltage lowered state), there is a possibility that the driving force of the electric motor is insufficient and a target braking force cannot be obtained, or that the electric PKB system malfunctions as described later. It may occur. A decrease in the power supply voltage is likely to occur when an electric motor provided in a device or system other than the electric PKB system is operated, for example, when the engine of the vehicle is started or when the electric power steering is operated.
The electric PKB system of this section is equipped with a voltage drop countermeasure unit against such a power supply voltage drop, and the motor control unit is in a voltage drop state when starting control of the motor according to the operation command. Alternatively, the control can be stopped and the control can be resumed when the voltage is restored, for example, when the voltage drops during the motor control.
In this way, if the control is stopped and the power supply to the motor is stopped in the voltage drop state, power can be preferentially supplied to a device or system having a higher priority in the vehicle, and the power supply voltage can be reduced. If the control is automatically resumed when returning, an increase in the operation burden on the driver can be avoided. However, although the power supply voltage normally recovers in a relatively short time, this is not always the case. Factors that take a long time to recover the power supply voltage include, for example, insufficient charging or deterioration of a battery as a power source, an abnormality in a power generation device (including an alternator, a regulator, and the like).
When the control is resumed after a relatively long time has elapsed since the voltage recovery is delayed, for example, the driver may have already started the vehicle or may have stopped driving the vehicle. If the control is resumed in such a state, it may be misunderstood that the electric PKB system has malfunctioned. Even if the driver does not take any action, there is a possibility that the electric PKB system may be misunderstood if the control is resumed with a great delay from the original operation timing. That is, it may be desirable to prevent resumption of control.
On the other hand, the electric PKB system of this section includes a control restart prevention unit, and can prevent restart of delayed control, for example, and more appropriately cope with a voltage drop state. In other words, the electric PKB system of this section includes a voltage drop countermeasure unit and a control restart prevention unit, and can cope with a state where the power supply voltage has dropped more appropriately, and is a more practical electric PKB system. is there. Whether or not the restart prevention condition is satisfied is determined based on whether or not a set time has elapsed since the control was stopped, as in an aspect described later, or for starting the vehicle performed by the driver. It is possible to make a determination based on the operation or the operation for stopping the operation.
The operation command can include, for example, an action command for generating a braking force, or a release command for releasing the braking force. The operation command may include information such as the magnitude of the braking force to be generated.
The operation command can be acquired based on an input operation of a switch or the like for operating the PKB device, for example. Alternatively, for example, an operation necessity determination device that automatically determines whether a braking force should be applied or released based on a driving operation of the vehicle (change of shift position, etc.) or the like is provided in the system (or It is also possible to provide an operation command based on the determination result of the operation necessity determination device.
The mode in which the control restart prevention unit prevents the restart of the control is, for example, a mode in which execution of at least a part of processing performed by the motor control unit or an operation command is changed, an electromagnetic switch (relay, MOS- For example, the conduction between the control device and the drive circuit or between the drive circuit and the motor may be cut off by a FET or the like. The parking brake device according to this aspect preferably includes a holding mechanism that holds a pressing force of the friction material against the brake rotating body in a state where electric power is not supplied to the electric motor.
(2) The time-based restart prevention condition that the control restart prevention unit determines that the restart prevention condition is satisfied when a state in which the control according to the operation command of the motor control unit is stopped continues for a set time or longer. The electric parking brake system according to item (1), including a determination unit.
The mode of this section prevents the restart of the control when the time when the control is stopped continues for a set time or more. Therefore, it is possible to simply prevent the delayed control from being restarted, and to reduce the possibility that the parking brake device may be mistaken for a malfunction. If the set time is shortened, the degree of delay in resuming the control can be reduced. However, if the set time is too short, there is a possibility that the resumption of control may be unnecessarily prevented. The set time can be, for example, 1 second or more, 2 seconds or more, and can be 6 seconds or less, 5 seconds or less, 4 seconds or less. In addition, when the aspect of the following term depends on this term, the upper limit of the set time can be increased, for example, 10 seconds or less, 8 seconds or less, and the like.
In addition, since the mode of this section can determine whether the restart prevention condition is satisfied without relying on the input of a switch or sensor, the mode of the following paragraph (8) is subordinate to the mode of this section Particularly suitable.
(3) When the control restart prevention unit performs an operation for starting the vehicle after the control according to the operation command of the motor control unit is stopped, and when the driver operates the vehicle. In the case of at least one of the case where the operation for stopping is performed and the operation state-based restart prevention condition determination unit that determines that the restart prevention condition is satisfied, the electric motor according to the item (1) or (2) Parking brake system.
Usually, the parking brake device is operated in a state where the vehicle is stopped. The actions that the driver can subsequently take are starting the vehicle, stopping (stopping) driving (including the case of resting in the vehicle, etc.), and the like. Therefore, the mode of this section determines that the resumption prevention condition is satisfied when the driver performs the above operation in the state where the control is stopped due to the voltage drop. Therefore, the control can be flexibly prevented according to the driver's action, and the possibility of misunderstanding that the parking brake device is malfunctioning can be reduced.
In order to detect that the above operation has been performed, for example, at least one of a start operation detecting unit and a driving stop operation detecting unit can be provided in the driving state dependence restart preventing condition determining unit. The start operation detecting unit can detect, for example, whether the shift position is a traveling position, whether a brake operation is performed, whether an accelerator operation is performed, whether a seat belt is attached, or the like. For example, the operation stop operation detection unit detects that the power source has been stopped, the ignition key is turned off, the seat belt is removed, the driver's door is opened, It can be detected that the backrest is reclined more than a set angle.
In addition, when it becomes possible to restart the stopped control (for example, when the voltage returns to a normal level), the operation state dependence restart prevention condition determination unit of this section can prevent the restart of the control. It can be determined whether it is necessary, that is, whether the restart prevention condition is satisfied.

(4) The electric parking brake system includes a notification device that notifies an occupant of an abnormality of the system,
Any one of the items (1) to (3), wherein the control device includes a notification command unit that notifies the notification device of an abnormality when the control restart prevention unit is prevented from restarting the control according to the operation command. The electric parking brake system described in 1.
According to the notification device of this section, it is possible to notify the occupant that the system is abnormal when resumption of control is prevented. The notification can call the driver's attention, and can cope with the voltage drop state more appropriately.
(5) When the control resumption prevention unit acquires a new operation command after preventing the resumption of control, the control according to the new operation command of the motor control unit is allowed to be performed ( The electric parking brake system according to any one of items 1) to (4).
According to the aspect of this section, when the power supply voltage is restored after preventing the restart of the control, the parking brake device can be operated according to a new operation command suitable for the situation. In the aspect of this section, even when the control is permitted by the control restart prevention unit, the control is not executed when the control is stopped by the voltage drop countermeasure unit.
(6) The electric parking brake system includes an operation member for inputting the operation command to the control device,
When an input operation is performed on the operation member after the control resumption preventing unit prevents resumption of control, control according to the operation command of the motor control unit acquired based on the input operation is performed. The electric parking brake system according to any one of (1) to (4), wherein
According to the aspect of this section, when the power supply voltage is restored after preventing the restart of the control, the parking brake device can be operated based on the driver's intention. In the aspect of this section, even when the control is permitted by the control restart prevention unit, the control is not executed if the control is stopped by the voltage drop countermeasure unit.
(7) The control resumption preventing unit prevents resumption of control according to the operation command stopped by changing the operation command to a command to make the electric motor inoperative. Or the electric parking brake system according to any one of (6).
Even when the control according to the operation command is stopped by the voltage drop countermeasure unit, the control according to the operation command is resumed by the motor control unit if the power supply voltage is restored thereafter. However, after the operation command is changed to a command to turn off the electric motor (for example, a command to stop power supply), the operation command to be resumed has already disappeared, even if the power supply voltage is restored. Even so, control cannot be resumed.

(8) The control device may be configured such that the voltage of the power source is a voltage at which the control device can operate, and the set voltage is set to a magnitude that can prevent malfunction of the electric parking brake system. The electric parking brake system according to any one of (1) to (7), further including an operation guarantee non-voltage detecting unit that determines that the voltage is in a lowered state when the voltage is less than a first set voltage.
If the power supply voltage is lower than the above set voltage (voltage that cannot guarantee operation), even if the control device operates normally, for example, the input from the sensor or switch may be inaccurate, or between the control device and other devices. Communication may be disabled. For this reason, when the power supply voltage becomes a voltage that cannot guarantee operation, it is desirable to stop the control once and restart the control after the voltage is restored.
In the case where the mode of this section is subordinate to the above (3), the operation state restart prevention condition determination unit determines that the restart prevention condition is satisfied when the power supply voltage is lower than the set voltage or higher than the set voltage. It can be determined whether it is satisfied.
(9) When the operation guarantee non-voltage detecting unit is less than the first set voltage when the operation command is a brake release command for releasing the braking force generated by the parking brake device, The electric parking brake system according to item (8), which is determined to be in a voltage drop state.
Since the braking force can be released even at a relatively low voltage in many cases, the mode of this section is in a voltage-decreasing state if the power supply voltage is equal to or higher than the first set voltage when a braking release command is issued. It is determined not to be present and control can be performed. The brake release command is an example of a release command.
(10) When the control device is a parking brake command for supplying power to the electric motor until the parking brake device generates a parking braking force that can maintain the vehicle in a parked state, the power supply When the voltage is greater than the first set voltage and becomes less than a second set voltage set to a magnitude that allows the electric motor to operate until the parking brake device generates the parking braking force. The electric parking brake system according to item (9), including a driving force insufficient voltage detection unit that determines that the voltage is in a low voltage state.
Since a relatively large voltage is often required in order to generate the parking braking force, the mode of this section is based on the voltage when the power supply voltage becomes less than the second set voltage when a parking braking command is issued. It is determined that the state is in a lowered state, and the control is stopped. The parking brake command is an example of an action command.
In addition, in the aspect of the above (8), when a parking braking command is made, if the power supply voltage is equal to or higher than the first set voltage, it is not determined that the voltage is in a lowered state and can be controlled. included. In this case, a light voltage drop in which the power supply voltage drop does not reach the operation unguaranteed voltage is not emphasized, and a severe voltage drop in which the power supply voltage drop reaches the operation unguaranteed voltage is emphasized. On the other hand, according to the aspect of this section, it is possible to appropriately cope with a slight voltage drop.
(11) The control device sets the power supply voltage to a minimum necessary level for operating the electric motor until the parking brake device generates a parking braking force that can maintain the vehicle in a parked state. The electric parking brake system according to any one of (1) to (7), further including a driving force shortage voltage detection unit that determines that the voltage is in a lowered state when the voltage becomes lower than the set voltage.
When the power supply voltage decreases, the driving force of the motor decreases, so that it may not be possible to generate a parking braking force. In such a case, it is desirable to stop the control once and restart the control after the voltage is restored. In addition, the aspect of this term shall respond | correspond appropriately to the said slight voltage drop.
(12) The driving force shortage voltage detection unit causes the parking brake device to generate a parking braking force with which the power supply voltage is less than the set voltage and the operation command can maintain the vehicle in a parking state. The electric parking brake system according to item (11), wherein it is determined that the voltage is in a lowered state when the parking braking control is to supply electric power to the electric motor.
In the aspect of this section, when the parking braking command is issued, if the power supply voltage becomes less than the set voltage, it is determined that the voltage is in a lowered state, and the control is stopped. When the brake release command is issued, for example, it can be determined that the voltage is in a lowered state when the power supply voltage becomes the voltage that cannot guarantee operation.
(13) The motor control unit
An operation command storage unit for storing the latest operation commands;
An operation command execution unit that controls the electric motor according to the operation command stored in the operation command storage unit and sets the electric motor in a non-operating state after the control is completed. The electric parking brake system according to any one of items 12).
By storing the operation command, the suspended control can be resumed after the control is stopped. In addition, the operation command execution unit can change the operation command to a command to put the motor in a non-operation state after the control is completed, or the next new operation command after the control is completed. The motor may be deactivated until is acquired.
(14) The motor control unit obtains the operation command based on an action signal indicating that a braking force, which is a signal input to the control device, is to be applied, and a release signal indicating that the braking force is to be released. The electric parking brake system according to any one of items (1) to (13), including an operation command acquisition unit that performs the operation.
The action signal and the release signal are, for example, input to the control device when an operation member operating the PKB device is operated, or transmitted from the operation necessity determination device to the control device It can be.

  Several embodiments of the claimable invention will now be described in detail with reference to the drawings. In addition to the following examples, the claimable invention can be practiced in various modifications based on the knowledge of those skilled in the art, including the aspects described in the above [Aspect of the Invention] section. .

  FIG. 1 schematically shows an electric parking brake system according to an embodiment of the claimable invention. In FIG. 1, the code | symbol 10 shows the electric motor which is a drive source, and the code | symbol 12 shows the motion conversion mechanism with a clutch. The electric motor 10 (hereinafter abbreviated as “motor” unless otherwise required) is constituted by an electric motor capable of duty control, for example, a brushless DC motor. The motion conversion mechanism 12 with the clutch converts the rotation of the output shaft of the motor 10 into a linear motion of the output member, and prevents the motor 10 from being rotated by a force applied to the output member. Reference numerals 14 and 16 indicate left and right rear wheels, and reference numerals 18 and 20 indicate parking brakes provided on the wheels 14 and 16, respectively. The vehicle provided with the electric parking brake system is a rear-wheel drive vehicle, and parking brakes are provided on the left and right rear wheels 14 and 16 as drive wheels, respectively. The parking brakes 18 and 20 and the motion conversion mechanism 12 with the clutch are connected by cables 22 and 24, respectively. When the cables 22 and 24 are pulled by the operation of the motor 10, the parking brakes 18 and 20 are activated. In the present embodiment, an electric parking brake 30 (a kind of parking brake device) is constituted by the motor 10, the motion conversion mechanism 12 with clutch, the cables 22, 24, the parking brakes 18, 20, and the like. The motor 10 may be constituted by a brushed DC motor.

As shown in FIG. 2, the motion conversion mechanism 12 with a clutch includes a gear train 40, a clutch 42, a screw mechanism 44, and the like.
The gear train 40 includes a plurality of gears 46, 48 and 50. The gear 46 is engaged with the gear portion of the output shaft 52 of the motor 10 and rotated by the rotation of the output shaft 52, and the rotation of the gear 46 is transmitted to the gear 50 through the gear 48. On the end surface of the gear 50 opposite to the motor 10, a drive transmission portion 54 that protrudes in parallel with the axial direction is provided.

  The clutch 42 is a one-way clutch, and can rotate integrally with a housing 60, a coil spring 62 provided on the inner peripheral side of the housing 60, and an output shaft 64 of the clutch 42, as shown in FIG. Rotor 66. FIG. 3 shows a state in which the clutch 42 is cut along the line AA shown in FIG. The coil spring 62 is fitted to the housing 60 in a state where the winding diameter is elastically slightly contracted, and the outer peripheral surface thereof is in close contact with the inner peripheral surface of the housing 60, and the end portions 68, 70 are provided so as to protrude toward the inner peripheral side. The drive transmission portion 54 of the gear 50 is located in one of the two spaces sandwiched between the two end portions 68 and 70, and the rotor 66 is located in the other.

  When the gear 50 rotates with the rotation of the motor 10, the drive transmission portion 54 comes into contact with either one of the end portions 68 and 70, and the coil spring 62 is tightened to tighten the inner peripheral surface of the housing 60 and the outer periphery of the spring 62. The frictional force between the surfaces is reduced. Thereby, the coil spring 62 and the rotor 66 can be rotated, and the output shaft 64 is rotated. The output shaft 64 is rotated integrally with the gear 50, and the rotation of the motor 10 is transmitted to the output shaft 64 by the clutch 42.

When torque is applied to the output shaft 64 in a state where no current is supplied to the motor 10, the rotor 66 comes into contact with one of the end portions 68 and 70, thereby expanding the coil spring 62. The frictional force between the outer peripheral surface of the coil spring 62 and the inner peripheral surface of the housing 60 is increased, and the rotation of the coil spring 62 is prevented. The clutch 42 prevents the torque of the output shaft 64 from being transmitted to the gear 50, and the motor 10 is not rotated by the torque applied to the output shaft 64 when no current is supplied to the motor 10.
In this embodiment, the clutch 42 constitutes the “holding mechanism that holds the pressing force of the friction material against the brake rotating body in a state where no electric power is supplied to the electric motor”. The state in which no current is supplied to the motor 10 is one aspect of the “non-operating state of the electric motor”.

  As shown in FIG. 2, the screw mechanism 44 includes a housing 80, a male screw member 82 extending in a direction parallel to the axis L, a nut (not shown) screwed to the male screw member 82, and the nut axis line. And an equalizer 84 mounted so as to be rotatable around an axis perpendicular to the axis. The male screw member 82 is supported by the housing 80 through a pair of radial bearings 85 (the other is not shown) and a needle thrust bearing 86 so as to be relatively rotatable. The inner cables 87 of the cables 22 and 24 are connected to both arms of the equalizer 84, respectively. The main body of the equalizer 84 is provided with an engagement protrusion 88, which is not shown, but is engaged with a guide provided in the housing 80 in a direction parallel to the axis L. As a result, the equalizer 84 is not relatively rotatable with respect to the housing 80 around the axis L, is relatively movable in a direction parallel to the axis L, and is relatively rotated around the engaging projection 88 (around the axis M). It is possible to move.

  The equalizer 84 is movable relative to the housing 80 between a position indicated by a solid line and a position indicated by a two-dot chain line in FIG. 2, and the inner cable 22, 24 is moved along with the relative movement of the equalizer 84. The cable 87 is pulled or loosened. Further, the equalizer 84 is arranged around the engaging protrusion 88 (on the axis M) so that the tension applied to the inner cable 87 of the two cables 22 and 24 (hereinafter simply referred to as the tension of the cables 22 and 24) is the same. Around). A tension sensor 90 that detects the tension of the cable 24 is provided inside the housing 80. Since the tension applied to the cables 22 and 24 by the equalizer 84 is set to the same magnitude, the tension applied to the cable 24 detected by the tension sensor 90 is also the tension applied to the cable 22.

  Reference numeral 92 denotes an abnormality canceling device. The abnormality release device 92 is a device for releasing the parking brakes 18 and 20 when the motor 10 is abnormal. The abnormality canceling device 92 includes an outer cable 93 and an inner cable 94 that is a drive member provided in the outer cable 93 so as to be movable in the longitudinal direction, and an operator operates a grip (not shown) as an operation member. The cable 94 is engaged with the gear 96 so as not to be relatively rotatable, and the gear 96 is rotated. The rotation of the gear 96 is transmitted to the gear 50 through the gears 46 and 48, and the output shaft 64 is rotated by the rotation of the gear 50, and the equalizer 84 is moved in the direction of loosening the cables 22 and 24. Thereby, the parking brakes 18 and 20 are released.

  As shown in FIGS. 4 and 5, the parking brakes 18 and 20 are duo-servo type drum brakes in this embodiment. Therefore, hereinafter, the parking brakes 18 and 20 may be referred to as drum brakes as necessary. The electric parking brake 30 is an electric drum brake. In FIG. 4, reference numeral 97 denotes a brake disk, reference numeral 98 denotes a caliper, and the brake disk 97 and the caliper 98 together constitute a disk brake 99 as a service brake. The drum brakes as the parking brakes 18 and 20 are provided on the inner peripheral side of the brake disc 97, and are drum-in disc brakes in this embodiment. Since the drum brakes 18 and 20 have the same structure, the drum brake 18 will be described and the description of the drum brake 20 will be omitted.

  The drum brake 18 includes a backing plate 100 as a non-rotating member attached to a vehicle body (not shown) and a brake drum 104 (hereinafter referred to as a drum 104) as a brake rotating body having a friction surface 102 on its inner peripheral surface and rotating together with the wheels 14. Abbreviated). An anchor member 106 and an adjuster 108 as a relay link are provided at two positions separated in the diameter direction of the backing plate 100, respectively. The anchor member 106 is fixed to the backing plate 100, and the adjuster 108 is a floating type. Between the anchor member 106 and the adjuster 108, a pair of brake shoes 110a and 110b as friction materials each having an arc shape are attached so as to face the inner peripheral surface of the drum 104. The pair of brake shoes 110a and 110b are attached to the backing plate 100 so as to be movable along the surfaces thereof by shoe hold-down devices 112a and 112b. The through hole provided in the center of the backing plate 100 is for allowing the axle shaft (not shown) to pass therethrough.

  The pair of brake shoes 110a and 110b are operatively connected at one end to each other by an adjuster 108, and each other end abuts against the anchor member 106 and is rotatably supported. One end portions of the pair of brake shoes 110a and 110b are urged toward the adjuster 108 by the adjuster spring 114, and the other end portions are urged toward the anchor member 106 by the return spring 115. . Brake linings 116a and 116b as friction materials are held on the outer peripheral surfaces of the brake shoes 110a and 110b, and the pair of brake linings 116a and 116b are brought into contact with the friction surface 102 of the drum 104, whereby the brake linings 116a and 116b are arranged. A frictional force is generated between 116 b and the drum 104. The adjuster 108 is operated to adjust the gap between the pair of brake linings 116a and 116b and the drum 104 in accordance with the wear of the pair of brake shoes 110a and 110b.

FIG. 5 shows the pressing mechanism 120. The pressing mechanism 120 includes a brake lever 122 and a strut 124, and is supported by heads of bolts 138 and 140 that fix the anchor member 106 to the backing plate 100 so as to be relatively movable. Each of the brake lever 122 and the strut 124 is a plate-like member. When the brake lever 122 is sandwiched between two plate members constituting the strut 124, the brake lever 122 and the strut 124 have one end portion thereof. In FIG. 2, the shaft is connected so as to be relatively rotatable around the connecting shaft 126. In the brake lever 122, the brake shoe 110 a is engaged with an engaging portion 128 provided at a portion separated from the connecting shaft 126 toward the backing plate 100, and an end separated from the connecting shaft 126 in a direction parallel to the backing plate 100. The inner cable 87 of the cable 22 is connected to the engaging part 130 provided in the part. The inner cable 87 is guided by an outer tube 134 having one end fixed to a through-hole 132 provided in the backing plate 100, and extends to a side opposite to the side where the brake shoe 110 and the like of the backing plate 100 are disposed. It has been made.
Further, in the strut 124, the brake shoe 110 b is engaged with an engaging portion 135 provided at the end opposite to the connecting shaft 126.
In the state shown in the drawing, the engaging portion 130 is located on the backward rotation direction side of the center line N (of the fixed end of the outer tube 134 to the backing plate 100) of the through hole 132. Further, as will be described later, when the pressing mechanism 120 is relatively moved in the circumferential direction, the engaging portion 130 is also relatively moved, but by design, the pressing mechanism 120 is relatively moved from the center line N to the forward rotation direction side. It is made not to be moved.

  The pressing mechanism 120 is supported by the heads of the bolts 138 and 140 at the supported portions 136 and 137. The motor 10 is rotated in the direction in which the parking brakes 18 and 20 are applied, the male screw member 82 is rotated, and the equalizer 84 is moved from the position indicated by the solid line to the position indicated by the two-dot chain line in FIG. When 87 is pulled, the brake lever 122 is rotated around the contact point between the supported portion 136 and the head of the bolt 138. As a result, the connecting shaft 126 and the strut 124 are moved to the right in FIG. The strut 124 pushes the brake shoe 110b to the right. At that time, the reaction force from the brake shoe 110b is transmitted to the brake shoe 110a via the strut 124, the connecting shaft 126 and the brake lever 122, and the brake shoe 110a is pushed to the left in FIG. The brake shoes 110a and 110b are spread by being applied with the same spreading force. As a result, the brake linings 116a and 116b have the same magnitude on the friction surface 102 of the drum 104. Pressed with force. The tensile force applied to the cable 22 is boosted in accordance with the lever ratio of the brake lever 122, and the friction force between the supported portion 136 and the head of the bolt 138 is calculated from the boosted force. It is applied to the brake shoe 110a as the expanding force of the subtracted size.

  When the drum brake 18 is operated in a state where torque is applied to the drum 104, a circumferential force is applied from the drum 104 to the brake shoes 110a, 110b, and one of the brake shoes 110a, 110b is applied to the anchor member 106. A so-called duo-servo effect occurs. When torque in the forward rotation direction (the rotation direction of the wheel when the vehicle moves forward) P is applied, the brake shoe 110a is pressed against the drum 104 with a greater force than when only the expansion force is applied due to the self-servo effect (contact surface pressure). Is increased). The circumferential force due to the self-servo effect is transmitted to the brake shoe 110b by the adjuster 108 together with the spreading force, and the brake shoe 110b is pressed against the drum 104 more strongly than the brake shoe 110a. The brake shoe 110b is brought into contact with the anchor member 106, and braking torque is generated. When a torque in the reverse rotation direction (the rotation direction of the wheel when the vehicle moves backward) Q is applied, conversely, the brake shoe 110a is pressed against the drum 104 more strongly than the brake shoe 110b. One output of the pair of brake shoes 110a and 110b becomes the other input. In this case, the pressing force of the brake shoes 110a, 110b against the drum 104 has a magnitude corresponding to the tension of the cable 22, and the curve shown in FIG. There is a relationship represented by When the vehicle is in a stopped state and the friction coefficient between the brake linings 116a and 116b and the drum inner peripheral surface 102 is constant, the braking force, the frictional force, the pressing force, and the spreading force If a certain relationship is established and the expansion force increases, the pressing force, the frictional force, and the brakeable torque also increase. Therefore, for example, based on the relationship between tension and spreading force, it is possible to acquire the relationship between tension and pressing force, the relationship between tension and frictional force, and the relationship between tension and brakeable torque.

The electric parking brake 30 is controlled by a parking brake electronic control unit (hereinafter abbreviated as “ECU” unless otherwise required) 200 as a control device shown in FIG. The ECU 200 includes an input / output unit 202, an execution unit 204, and a storage unit 206. The input / output unit 202 includes a parking brake switch 210 (hereinafter abbreviated as PKB switch 210), an ignition switch 212 (hereinafter abbreviated as IG switch), a door switch 214, a seat belt switch 216 ("SB switch" in the figure). And a tension sensor 90 are connected.
The PKB switch 210 is a manual operation switch. For example, the PKB switch 210 is rotatably provided on the instrument panel, and is selectively positioned at an OFF position (neutral position), a lock position, and a release position. When not added, the switch automatically returns to the OFF position. The PKB switch 210 is rotated to the lock position and outputs a lock signal (a kind of action signal), and is turned to the release position and outputs a release signal (a kind of release signal).

As shown in FIG. 1, the motor 10 is connected to the input / output unit 202 via the drive circuit 220 and driven. Further, a CAN (Car Area Network) 224 is connected to the input / output unit 202, whereby communication is performed among the ECU 200, the meter computer 230, the skid control computer 234, the engine control computer 236, and the like.
To the meter computer 230, a combination meter 240 and a notification sound generator 242 which are a kind of display device are connected. The combination meter 240 includes an instrument for displaying the vehicle speed and the like, an indicator lamp for simply notifying various kinds of information with graphics, a multi-display (liquid crystal display, organic electric luminescence display, etc.) as a character graphic display device, and the like. The notification sound generator 242 is a buzzer that generates a warning sound or the like.
The skid control computer 234 receives detection signals of various sensors such as a wheel speed sensor 250, a front / rear G sensor 252, a brake pedal switch 254, and the like, and acquires vehicle speed, acceleration, brake operation, and the like. Further, the brake actuator and the like are controlled based on the vehicle speed, the acceleration, and the like, and braking control, antilock control, vehicle stability control, and the like are performed. From the skid control computer 234 to the ECU 200, for example, the traveling speed of the vehicle (hereinafter abbreviated as vehicle speed) and the front and rear G are supplied.
As shown in FIG. 1, the engine control computer 236 receives detection signals from various sensors such as an accelerator pedal sensor 260 and a shift position sensor 262, and acquires accelerator operation information, shift position information, and the like. Further, the vehicle drive device (engine, transmission) is controlled based on the accelerator operation information, the shift position information, etc., and the left and right rear wheels 14, 16 are rotationally driven.
Further, the vehicle is provided with a battery 270 as a power source, and power is supplied to various computers and devices including the ECU 200 and the drive circuit 220. In FIG. 1, a power supply path 272 that connects battery 270 to ECU 200 and drive circuit 220 is representatively shown. The ECU 200 includes a voltmeter and can acquire the voltage of the power supply path 272.

The operation will be described.
FIG. 7 shows a flowchart of an electric parking brake control program (hereinafter abbreviated as “electric PKB program”). This program is stored in the storage unit of the ECU 200 and is repeatedly executed after the ECU 200 is activated.
In step 11 (hereinafter abbreviated as “S11”), it is confirmed whether or not the braking force of the electric PKB 30 is appropriate. For example, when the electric PKB 30 does not change the braking force, the braking force is applied even when the vehicle is in a traveling state, or the appropriate braking force is applied when the vehicle is stopped. If not, it is determined that the braking force is inappropriate. Thereafter, in S12, when the PKB switch 210 is operated, how to control the motor 10, that is, the control content as an operation command is determined. In S13, processing corresponding to the voltage drop of the battery 270 is performed, and the control content is changed when necessary. Thereafter, in S14, control is performed according to the control content.
Below, S11-S14 is demonstrated in detail.

FIG. 8 shows a flowchart of the braking force appropriateness confirmation in S11. With this process, in a state where the control for changing the braking force of the electric PKB 30 is not performed, if the detected value of the tension sensor 90 is an inappropriate value, it is notified that the braking force is inappropriate and the driving is performed. The user's operation is prompted. This will be described in detail below.
In S21, longitudinal acceleration, vehicle speed, and the like are acquired from the skid control computer 234 via the CAN 224, and are used for processing to be described later.
In S22, it is determined whether or not the value of the storage variable X is 0. The storage variable X is a variable for storing a control correspondence number that is a numerical value corresponding to each control content, and the value is determined in a control content determination process described later. When the storage variable X is 0, no power is supplied to the motor 10 and the motor 10 stops. That is, when the memory variable X is 0, basically, the control for changing the braking force has been completed, and the parking braking force that is the braking force that can maintain the vehicle in the parking state is applied (hereinafter referred to as the braking force). , Referred to as “locked state”) or in a state where the vehicle can travel without being applied with a braking force (hereinafter referred to as “release state”).
If the value of the storage variable X is 0 in S22, it is determined in S24 to S30 whether the braking force is appropriate. On the other hand, when the value of the storage variable X is other than 0, since it is in the middle of changing the braking force, it is not determined whether or not the braking force is appropriate. This is released, and the execution of the braking force appropriateness confirmation process ends.
Note that when the execution of the braking force appropriateness confirmation process is completed, S13 of FIG. 7 is executed.

In S24, when the vehicle speed is equal to or higher than a set speed V0 (eg, 3 km / h, 5 km / h, etc.) set near 0, it is determined that the vehicle is traveling. When the vehicle is running, it is appropriate that the vehicle is in the released state. In S25, the tension S acquired based on the output of the tension sensor 90 (see FIG. 6) is the set value Sa set near 0. If it is less than that, it is determined that the vehicle is in the released state and the braking force is appropriate.
On the other hand, when the tension S is equal to or greater than the set value Sa, it is determined that the braking force is not appropriate, not the released state, and a command to notify that the braking force is inappropriate is issued in S26. It is made to the meter computer 230.
The meter computer 230 that has received the notification command turns on or blinks a specific indicator lamp of the combination meter 240 and displays a warning, and indicates that the braking force of the electric PKB 30 is inappropriate on the multi-display. A sentence is displayed. In addition, a warning sound is generated from the notification sound generator 242 to prompt the driver to check the multi-display and the indicator lamp of the combination meter 240.
With such a warning, for example, the driver recognizes that the braking force of the electric PKB 30 is in an inappropriate state, and if the vehicle is running, temporarily stops the vehicle and operates the PKB switch 210 (in this case) If so, the release position) can be performed.
Note that the notification sound generation device 242 can be a sound generation device that transmits the notification contents in a speech language. The sound generation device includes, for example, a computer, an amplifier, a speaker, and the like, and reproduces various sounds stored in the storage unit of the computer in accordance with the notification contents, and generates sound such as a car navigation system. Functions can be used.

If it is determined in S24 that the vehicle is stopped, the locked state or the released state is set to an appropriate state. The reason why the release state is appropriate while the vehicle is stopped is that the locked state and the release state can be selected by the driver's operation while the vehicle is stopped.
In S27, the target tension Sb for determining whether or not the vehicle is in the locked state is determined according to the road surface gradient (longitudinal acceleration) so that the target tension Sb increases as the gradient increases. In the storage unit 206 of the ECU 200, the correspondence relationship between the value of the longitudinal acceleration and the value of the target tension Sb is stored in the map, and the value of the target tension Sb corresponding to the acquired longitudinal acceleration is read from the map. The target tension Sb is determined.
In S28, when neither the locked state (S ≧ Sb) nor the released state (S ≦ Sa) is satisfied (Sa <S <Sb), it is determined that the braking force is in an inappropriate state. The determination as to whether or not the lock state is established can also be made based on whether or not the tension S is greater than a value obtained by subtracting the set value α from the target tension Sb (Sb−α). This is because the target tension Sb is set to a value that can maintain the parking state with a margin, so that the parking state can be maintained even if the tension S is smaller than the target tension Sb.
If it is determined in S28 that the braking force is in an inappropriate state, a notification that the braking force is in an inappropriate state is made in S29, as in S26. If it is determined that the braking force is not inappropriate, the notification command is canceled (S30).

FIG. 9 shows a flowchart of the control content determination process in S12. In this process, when an operation input of the PKB switch 210 is made, the control content is determined based on the operation input, the vehicle speed, and the state of the IG switch 220.
In this embodiment, there are four types of control contents, and the number of control correspondences is set for each. When the control correspondence number is “0”, the power supply to the motor 10 is stopped (non-operating state). When “1”, the electric PKB 30 is locked, and when “−1”, the electric PKB 30 is released. In the case of “2”, the braking control during traveling described later is performed. In this embodiment, the power supply stop to the motor 10 is included in the control content, but the power supply stop also means that the control is not performed, and setting the control correspondence number to 0 stops the control. It can be considered that the control content is deleted.
(a) When a lock signal input is detected in S31 and it is determined that the vehicle is stopped in S32, “1” is input to the storage variable X in S33, and the lock control to lock the electric PKB 30 is selected. Is done. Further, in S34, the target tension Sb is determined as in S27. That is, a lock control command that is a kind of parking braking command is acquired. The lock control command includes a target tension value.
Whether or not the vehicle is stopped is determined by whether or not the vehicle speed V is less than a set speed V1 set near zero. The set speed V1 can be set to the same value as the set speed V0 described above.
(b) If a lock signal is input and it is determined that the vehicle is traveling, “2” is input to the storage variable X in S35 and braking control during traveling is selected.
The running braking control increases the braking force only while the driver continues to operate the PKB switch 210 to the locked position, and the driver releases the operation of the PKB switch 210 (the lock signal and the release signal are not input). Is a control in which the braking force is automatically reduced to the released state. This running braking control is a kind of action command.
(c) When the input of the release signal is detected in S36 and it is determined in S37 that the IG switch 220 is ON, "-1" is input to the storage variable X in S38, and the electric PKB 30 is set in the release state. Release control is selected. That is, a release control command that is a kind of braking release command is acquired.
Whether the IG switch 220 is ON / OFF is determined based on whether or not the voltage of the electric power supplied to the ECU 200 via the IG switch 220 is equal to or higher than a set voltage.
(d) When the release signal is input and it is determined that the IG switch 220 is OFF, “0” is input to the storage variable X in S39, and the power supply stop to the electric PKB 30 is selected.
The ECU 200 has two power supply paths A and B, and the conduction of the path A via the IG switch 220 is cut off when the IG switch 220 is turned off. The other path B is provided with an electromagnetic switch (not shown) such as a MOS-FET, and the IG switch 220 is turned off while the electromagnetic switch is turned on by the output of the ECU 200. However, electric power is supplied from the path B to the ECU 200. In such a state, even if the PKB switch 210 is operated to the release position, release control is not performed. The ECU 200 shuts off the conduction of the path B by stopping the output to the electromagnetic switch when the state in which the processing such as the lock control is not performed continues for a set time in the state where the IG switch 220 is turned off. The power is turned off.

Here, for easy understanding, a part of the voltage drop handling process of S13 will be briefly described, and then the control content execution process of S14 will be described.
FIG. 10 shows a flowchart of the voltage drop handling process in S13. If it is determined in the processing of S41 and S42 that the voltage is not lowered, the value of the control correspondence number input to the storage variable X in S43 becomes the execution variable Y referred to in the control content execution processing of S14. Entered. That is, a process is performed in which the control content corresponding to the control correspondence number determined in the control content determination process in S12 is directly executed in the control content execution process in S14.

FIG. 11 shows a flowchart of the control content execution process of S14. In S61 to S63, the control content is determined based on the value of the control correspondence number stored in the execution variable Y, and the following processing is performed. Regarding the rotation direction of the motor 10, rotation in the direction in which the tension S is increased is referred to as “forward rotation”, and rotation in the direction in which the tension S is decreased is referred to as “reverse rotation”.
(a) When the execution variable Y is “1”, lock control is performed in S64 to S67.
Specifically, when the tension S is equal to or less than the target tension Sb, the motor 10 is rotated forward (S65), and the braking force is increased. On the other hand, when the tension S exceeds the target tension Sb, since the locking is completed, the power supply to the motor 10 is stopped and the motor 10 is stopped (S66). Further, the storage variable X is set to “0” (S67), and the control content is stopped.
If the PKB switch 210 is not operated until the next execution of this control content execution process by the process of setting the storage variable X in S67 to 0, the execution variable Y becomes 0, so the processes of S64 to S75. Is skipped and the motor 10 is stopped in S76.
(b) When the execution variable Y is “−1”, release control is performed in S68 to S71.
Specifically, when the tension S is equal to or greater than the set tension Sa (see FIG. 6) set near 0, the motor 10 is reversely rotated (S69), and the braking force is reduced. On the other hand, when the tension S is less than the set tension Sa, since the release is completed, the power supply to the motor 10 is stopped and the motor 10 is stopped (S70). Further, the storage variable X is set to “0” (S71), and the control content is stopped. Note that the description of S70 is the same as that of S67.
(c) When the execution variable Y is “2”, the running braking control is performed in S72 to S75. Specifically, when the tension S is equal to or less than the set tension Sh, the motor 10 is rotated forward (S73), and the braking force is increased. The set tension Sh is set to the same value as the maximum value of the target tension Sb. On the other hand, when the tension S exceeds the set tension Sh, the power supply to the motor 10 is stopped and the motor 10 is stopped in order to maintain the braking force (S74). Further, the storage variable X is set to “−1” (S75), and the control content is changed to release control.
The release control is automatically performed after the driver releases the input operation of the PKB switch 210, that is, after the PKB switch 210 is returned to the OFF position by the process of setting the storage variable X in S75 to “−1”. To be done. That is, at the next execution of this control content execution process, if the PKB switch 210 has not been operated until then, the execution variable Y becomes “−1”, so release control is started in the processes of S68 to S71. It is.
(d) When the execution variable Y is “0”, the power supply to the motor 10 is stopped and the motor 10 is stopped in S76.

The process of S67 and S71 is an example of a process of “turning the electric motor in a non-operating state based on the operation command stored in the storage unit”. The process is performed by changing the value of the storage variable X, which is an operation command, to 0, which is a control-corresponding number that puts the motor in an inoperative state, that is, by changing the operation command.
This is the end of the description of the control content execution process in S14, and the voltage drop handling process in S13 will be described in detail below.

FIG. 10 shows a flowchart of the voltage drop handling process in S13. When the voltage supplied from the battery 270 is normal, this process allows the execution of the control according to the control content determined in the control content determination process, while temporarily executing the control according to the control content in the voltage drop state. In addition, the control is stopped, and when the set condition is satisfied, the restart of the stopped control is prevented.
In S41 and S42, based on the voltage of the battery 270 (specifically, the voltage of the power supply path 272), it is determined whether or not it is in a voltage drop state. In the present embodiment, at least one of the two types of states is determined to be a voltage drop state.
In S41, it is determined that the voltage of the battery 270 is in a voltage drop state when the voltage of the battery 270 is a control prohibition voltage that is an operation guarantee impossible voltage. The control prohibition voltage is a voltage that may cause an inaccurate input from various switches or sensors due to a lack of voltage, or disable information communication via the CAN 224 or the like.
Further, when the determination in S41 is NO, it is determined in S42 that the lock control (X = 1) is being performed and the voltage of the battery 270 is a driving force insufficient voltage, and that the voltage is in a low state. The The driving force insufficient voltage is a voltage at which the motor 10 cannot generate a driving force that increases the tension S to the set tension Sc. The set tension Sc can be set to the same value as the target tension Sb, for example. In this case, the correspondence relationship between the target tension Sb and the voltage required to increase the tension S to the target tension Sb can be stored in the storage unit 206 in advance. Then, when the voltage of the battery 270 is less than the voltage corresponding to the determined target tension Sb, it can be determined that the driving force is insufficient. Further, for example, the set tension Sc can be set to a value larger than the target tension Sb when the motor 10 stops the tension S on a horizontal road surface and equal to or less than the set tension Sh.
The control inhibition voltage is set to a voltage lower than the set voltage E1 (a kind of first set voltage) smaller than the normal voltage, and the drivability deficiency voltage is set to be larger than the set voltage E1 and smaller than the normal voltage. The voltage is less than the voltage E2 (a kind of second set voltage).

If it is determined that the voltage drop state is not present, as described above, the control content determined in the control content determination processing in S12 is executed as it is in S14. Specifically, in S43, the control correspondence number stored in the storage variable X in S12 is input to the execution variable Y referred to in S14 later.
Thereafter, after processing such as S44 and S45 described later is performed, the execution of the voltage drop handling processing is terminated, and the control content execution processing of S14 described above is performed.

If it is determined in S41 or S42 that the voltage is in a lowered state, the motor 10 is stopped, and further, the restart of the control is prevented after the set time elapses after the control according to the control content is stopped. This will be described in detail below.
In S46, the value of the execution variable Y is set to 0 regardless of the value of the storage variable X. That is, by this process, the control of the motor 10 according to the control content is stopped, and the power supply is stopped and the motor 10 is stopped in S14 (S76 in FIG. 11).
In S47 to S50, the time when the control of the motor 10 according to the control content is stopped is measured. Specifically, if the value of the storage variable X is other than 0 and the flag Ft is OFF by the determination of S47, the timer is started after being reset to 0 (S48), and the flag Ft is ON. (S49). By these processes, when the value of the storage variable X is 0, that is, when the lock control, the release control or the like is not performed, the timer is not started even in the voltage drop state. . Further, since the flag Ft is turned on after the timer is started, the processing of S48 and S49 is performed until the voltage is restored and it is not determined that the voltage is lowered and the flag Ft is turned off in S45. It is supposed to be skipped. If the voltage is not lowered, the timer is stopped after being reset to 0 in S44.

In S50, when the measured time T of the timer is equal to or shorter than the set time T1 (for example, 3 seconds), one execution of the voltage drop handling process ends. Thereafter, as described above, the motor 10 is stopped in S14. Thereafter, when this process is executed and the voltage drop state is not reached, S43 is executed, and control according to the control content stored in the storage variable X in S14 is performed. That is, the control according to the stopped control content is resumed.
On the other hand, in S50, when the measurement time T exceeds the set time T1, the processing of S51 and S52 is performed.
In S51, a restart prevention process is performed by setting the value of the storage variable X to 0. That is, since the number of control correspondences before the resumption of control is prevented by setting the value of the storage variable X to 0 is deleted, the electric PKB control of FIG. In this case, the control according to the control content before blocking is not performed. That is, the restart of the control according to the control content before the voltage drop state is prevented.

Thereafter, in S52, a command to notify the driver that the electric PKB 30 is in an inoperable state is transmitted to the meter computer 230. When the meter computer 230 receives the notification command, a specific indicator lamp or the like of the combination meter 240 is turned on or blinked to display a warning, and a text indicating that the electric PKB 30 is not operable is displayed on the multi-display. Is done. In addition, a warning sound is generated from the notification sound generator 242 to prompt the driver to check the multi-display and the indicator lamp of the combination meter 240. With the above warning, for example, the driver can recognize that the electric PKB 30 is inoperable, and can respond appropriately. The notification sound generation device 242 can be a sound generation device that transmits the notification contents in a spoken language as described above.
When communication by CAN 224 is disabled due to a voltage drop of battery 270, meter computer 230 notifies that electric PKB 30 is abnormal regardless of whether there is a notification command from ECU 200. Specifically, as described above, a warning is given by the indicator lamp, the multi-display, and the notification sound generator 242 so that the driver can recognize that the electric PKB 30 is abnormal.

Even if the PKB switch 210 is operated in a state where the resumption of control is prevented, the storage variable X is set to 0 in the processing of S51, and the operation is cancelled.
On the other hand, when the resumption of control is prevented and the inoperable state is notified, and the voltage of the battery 270 is restored and the voltage is not lowered, when an input operation is performed on the PKB switch 210, a new operation is performed in S12. The control content is determined, and the notification command is canceled by the processing of S53 and S54. In S14, the motor 10 is controlled according to the control content. That is, control according to a new operation command is permitted.

In the present embodiment, the part of the ECU 200 that performs the control content determination process in S12 (S31 to S39 in FIG. 9) constitutes the “operation command acquisition unit”. Further, the portion of the ECU 200 that executes the processing of S14 (S61 to S76 in FIG. 11) constitutes the “operation command execution portion”. Further, a combination of the operation command acquisition unit, the operation command execution unit, and the portion of the ECU 200 that executes the process of S43 constitutes the “motor control unit”. Further, the part of the ECU 200 that stores the storage variable X and the target tension Sb constitutes the “operation command storage unit”. Furthermore, the portion of ECU 200 that performs the braking force appropriateness confirmation processing in S11 (S21 to S30 in FIG. 8) constitutes a “braking force abnormality detection unit that detects an abnormality in the braking force of the parking brake device”. The braking force abnormality detection unit can be included in, for example, the control device or the motor control unit.
In the present embodiment, the part of the ECU 200 that executes the processes of S41, S42, and S46 constitutes the “voltage drop countermeasure unit”. Further, the part of the ECU 200 that executes S41 constitutes the “operation guaranteed non-voltage detecting unit”. Furthermore, the portion of the ECU 200 that executes S42 constitutes the “driving force insufficient voltage detector”. Furthermore, the portion of the ECU 200 that executes the processing of S44 to S50 constitutes the “time-based restart prevention condition determination unit”. Furthermore, the portion of the ECU 200 that executes the processes of S44 to S54 constitutes the “control restart prevention unit”. In this embodiment, the control restart prevention unit is configured to issue a command to notify that when the control restart is stopped. A combination of the meter computer 230, the combination meter 240, and the notification sound generator 242 constitutes the “notification device”. Furthermore, the portion of the ECU 200 that executes the process of S52 constitutes the “notification command unit”.

In the process of S41 of this embodiment, when the voltage of the battery 270 becomes less than the set voltage E1, the determination is YES and the control is stopped regardless of whether the control content is lock control or release control. (S46). As a result, when the voltage of the battery 270 is equal to or higher than the set voltage E1, the process of S42 is performed, the control content is lock control, and the voltage of the battery 270 is less than the set voltage E2. Control is stopped (S46). That is, in this embodiment, when the voltage of the battery 270 is the control prohibition voltage, it can be considered that the control is stopped regardless of whether the control content is the lock control or the release control. Further, when the voltage of the battery 270 is a driving force insufficient voltage but not a control prohibiting voltage, it can be considered that the lock control is stopped and the release control is allowed.
In addition, the process of S41 may be configured so that the determination is YES when the control content is release control other than lock control, braking control during travel, and the voltage of the battery 270 is a control inhibition voltage. Yes (or the order of S41 and S42 can be interchanged). Even in such a case, the result of the voltage drop handling process does not change, but as a method of grasping the determination process, (a) when the control content is release control or the like and the voltage of the battery 270 is the control prohibition voltage It can be considered as a mode in which it is determined that the voltage is in the low voltage state, and (b) the control content is the lock control and the voltage of the battery 270 is the driving force insufficient voltage. .

An embodiment different from the above will be described.
In the above embodiment, the restart of the control is prevented depending on the time during which the control is stopped. However, the restart of the control can also be prevented depending on the operation state. In the present embodiment, an electric parking brake system similar to that shown in FIG. 1 is used, and a program executed by the ECU 200 is partially different. Therefore, the description of the same configuration as that of the above embodiment is omitted, and different portions will be mainly described.
In the present embodiment, the above-described electric PKB control program (FIG. 7) is executed. The processes of S11, S12, and S14 are the same as in the above embodiment, and the voltage drop handling process of S13 is different.

FIG. 12 and FIG. 13 show flowcharts of the voltage drop handling process B (indicated by symbol B to distinguish it from FIG. 10) performed in S13. The processes of S41 to S43, S53 and S54 are the same as in the above embodiment. Further, the same processing as S46 described above is performed in S46a and S46b.
In S101, when the voltage is restored after the voltage of the battery 270 is reduced to the control inhibition voltage (voltage ≦ E1) (voltage> E1), it is determined whether or not to restart the control described later (No. 1) "Restart prevention necessity determination process" that is a process between No. 1 and No. 2 (FIG. 13)) is performed. In other words, when the voltage drops to the control prohibition voltage, there is a possibility that the input of various sensors and switches may be inaccurate. The necessity of resumption is judged after becoming larger. Specifically, if the voltage has dropped to the control inhibition voltage, the determination in S41 is YES and the flag Fv is turned on (S103). Thereafter, when the voltage is restored, the control is not resumed unless it is determined whether or not the resumption is permitted.
In S102, driving operation information in a state that is not determined to be a voltage drop state is acquired. In the present embodiment, the driving operation information includes operation information for starting the vehicle and operation information for stopping driving. The driving operation information is used in the restart prevention determination process.
The process of FIG. 13 will be described later in detail.

14 and 15 show flowcharts of the driving operation information acquisition process of S102. The driving operation information is executed when the voltage is not lowered, and obtains what operation was performed before the voltage lowered state.
In S111 to S113, it is determined whether or not the shift position is a travel position. If the shift position is a travel position, the flag Fs is turned on, and if different, the flag Fs is turned off. For example, in the case of an automatic transmission, the shift position for traveling is a position such as a drive, a back, a low, a second, or the like. The shift position operation information is acquired by the engine control computer 236 based on the output of the shift position sensor 262 and transmitted to the ECU 200 via the CAN 224.
In S114 to S116, it is determined whether or not the brake for driving is being operated. If the operation is being performed, the flag Fb is turned ON. The operation information of the running brake is acquired by the skid control computer 234 based on the output of the brake pedal switch 254 and transmitted to the ECU 200 via the CAN 224.
In S117 to S119, it is determined whether or not the accelerator operation is performed. If the operation is performed, the flag Fa is turned ON. The accelerator operation information is acquired by the engine control computer 236 based on the output of the accelerator pedal sensor 260 and transmitted to the ECU 200 via the CAN 224.
In S121 to S123, it is determined whether or not the seat belt is worn. If the seat belt is worn, the flag Fr is turned ON. Whether or not the seat belt is attached is acquired based on the output of the seat belt switch 216 provided in the buckle portion that fixes the seat belt to the side surface of the driver's seat.
In S124 to S126, it is determined whether or not the IG switch 212 is ON. If it is ON, the flag Fi is turned ON. Whether or not the IG switch 212 is ON is determined by the ECU 200 based on whether or not the voltage of the power supplied via the IG switch 212 is equal to or higher than the set voltage.
In S127 to S129, it is determined whether or not the door of the driver's seat is open. If it is open, the flag Fd is turned ON. Whether or not the door is open is acquired based on the output of the door switch 214 that is turned ON / OFF by opening and closing the door. In the present embodiment, the so-called half-door state is determined to be an open state, but the half-door state may be determined to be a closed state.

Returning to FIG. 13, the restart prevention necessity determination process (S141 to S147, S51, S52), which is the process between No. 1 and No. 2, will be described. As described above, this process is executed when at least one of the determination in S42 and the determination in S101 is YES in FIG. That is, when the lock control is selected (X = 1) and the voltage of the battery 270 is larger than the control prohibition voltage and the driving force is insufficient (S42), the voltage of the battery 270 is set when the storage variable X is other than 0. Is executed after at least one of the case where the control returns to the control inhibition voltage, that is, the case where the interrupted control can be resumed (S101).
Control is performed when the above-described various flags Fs to Fd indicating operation information before the voltage drop state (hereinafter referred to as “normal voltage”) and the current operation state satisfy the set conditions. It is determined that it is necessary to prevent the restarting.

In S141, when the voltage is normal, the shift position is not the travel position (Fs = OFF), but when the current position is the travel position, the restart is prevented. That is, the shift position is changed from the stop position to the travel position, so that it is determined that the driver is about to start the vehicle or after the vehicle is started, and control is performed at that time. Is prevented from being resumed.
Similarly, in S142, the running brake is operated when the voltage is normal (Fb = ON), but the restart is prevented when the running brake is released at the present time. . Furthermore, similarly, in S143, the accelerator operation is not performed when the voltage is normal (Fa = OFF), whereas the restart is prevented when the accelerator operation is performed at the present time. Further, in S144, similarly, when the voltage is normal, the seat belt is not worn (Fr = OFF), but when the seat belt is worn at the present time, restart is prevented.
It is determined whether or not an operation for starting the vehicle has been performed through the processes of S141 to S144. On the other hand, whether or not an operation for stopping the driving of the vehicle by the driver has been performed is determined by the following processes of S145 to S147.
In S145, when the voltage is normal, the seat belt is worn (Fr = ON), but when the seat belt is not worn at this time, the restart is prevented. That is, when the seat belt is removed, it is determined that the driver is about to stop driving or after the driving is stopped, and the resumption of control is prevented at that point.
Similarly, in S146, when the voltage is normal, the IG switch 212 is turned on (Fi = ON), whereas when the IG switch 212 is turned off at the present time, restart is prevented. The As described above, the ECU 200 operates for a set time even after the IG switch 212 is turned OFF, and thus such processing is provided. Further, similarly, in S147, when the voltage is normal, the door is closed (Fd = OFF), but when the door is opened at the present time, the restart is prevented.

  If it is determined that it is necessary to prevent the control from being restarted, the same processing of S51 and S52 as described above is executed, the restart is blocked, and it is notified that the electric PKB 30 is inoperable, and this voltage drop One execution of the response process B ends. On the other hand, when it is determined that it is not necessary to prevent the restart of the control, one execution of the voltage drop handling process B ends. Thereafter, the process of S14 is performed.

  In the present embodiment, the part of the ECU 200 that executes the processes of S141 to S144 constitutes the “start operation detection unit”. Note that the start operation can be detected by at least one of S141 to S144. Further, the part of the ECU 200 that executes the processes of S145 to S147 constitutes the “operation stop operation detection unit”. Note that the operation to stop the operation can be detected by at least one of S145 to S147. The “driving state dependent resumption prevention unit” of the present embodiment is configured to prevent resumption when either an operation for starting the vehicle or an operation for stopping the driving is performed. It is also possible to adopt a mode in which resumption is prevented only when one operation is performed.

In this embodiment, whether or not it is necessary to prevent resumption of control is determined without depending on the time when control is stopped, but whether or not resumption prevention is necessary depends on both the control stop time and the operation state. It can also be determined. For example, as shown in a simplified manner in FIG. 16, in the flowchart of FIG. 12, the processes of S44 and S45 of FIG. 10 are inserted between S43 and S53 (for example, after S102), and after the process of S103. The processing of S47 to S52 in FIG. 10 is inserted, and as shown in a simplified manner in FIG. 17, the processing of S47 to S50 in FIG. 10 is inserted before S141 in the flowchart in FIG. It is possible to make the determination based on the control stop time. The set time T1 in this case can be made longer than in the case of FIG.
In addition, when determining whether to prevent resumption based on both the control stop time and the driving operation state, the determination based on the operating state is not performed before the set time elapses after the control is stopped. You can also.

It is a figure showing roughly the electric parking brake system which is an example of the claimable invention. It is a front view (partial cross section) which shows the motion conversion mechanism with a clutch of the said electric parking brake system. It is side surface sectional drawing which shows the clutch of the said motion conversion mechanism with a clutch, and is AA sectional drawing in FIG. It is a front view which shows the drum brake which is a parking brake of the said electric parking brake system. It is a front view (partial cross section) which shows the pressing mechanism of the said electric parking brake system. It is a graph showing the relationship between the tension | tensile_strength of a cable at the time of the action | operation of the said electric parking brake system, and a brakeable torque. It is a figure which shows the flowchart of the program which controls the said electric parking brake. It is a figure which shows the flowchart of the braking force confirmation process of the said program. It is a figure which shows the flowchart of the control content determination process of the said program. It is a figure which shows the flowchart of the voltage drop response process of the said program. It is a figure which shows the flowchart of the control content execution process of the said program. In another Example different from the above, it is a figure which shows the flowchart of the voltage drop response process B of the program which controls an electric parking brake. It is a figure which shows a part of flowchart of the said voltage drop response process B. FIG. It is a figure which shows the first half part of the flowchart of the driving operation information acquisition process of the said voltage drop response process. It is a figure which shows the latter half part of the flowchart of the driving operation information acquisition process of the said voltage drop response process. It is a figure which shows the flowchart of the voltage drop response process C which deform | transformed the said voltage drop response process. It is a figure which shows a part of flowchart of the said voltage drop response process.

Explanation of symbols

    10: Electric motor 12: Motion conversion mechanism with clutch 18, 20: Parking brake 30: Electric parking brake (parking brake device) 42: Clutch (holding mechanism) 80: Housing 90: Tension sensor 100: Backing plate 102: Friction surface 104 : Drum (brake rotating body) 110a, b: brake shoe (friction material) 120: pressing mechanism 200: electronic control unit [ECU] (control device) 210: PKB switch (operation member) 220: drive circuit 222: CAN 230: Meter computer 240: Combination meter 242: Notification sound generator 270: Battery (power source) 272: Power supply path

Claims (7)

A parking brake device that includes an electric motor, presses the friction material against the brake rotating body by the driving force of the electric motor to generate a braking force, and maintains the braking force in a non-operating state of the electric motor;
Power supply,
An electric parking brake system including a control device for controlling the parking brake device,
The control device is
A motor control unit for controlling the electric motor in accordance with an operation command;
(a) In a voltage drop state in which the voltage of the power source is lowered below a set voltage, the control according to the operation command of the motor control unit is stopped, and the electric motor is inactivated, and (b) the A voltage drop coping unit that resumes control according to the operation command of the motor control unit when the voltage drop state is no longer present;
And a control restart prevention unit for preventing restart of control according to the operation command of the motor control unit even when the voltage drop state is not achieved when a predetermined restart prevention condition is satisfied. Parking brake system.   A time-based restart prevention condition determination unit that determines that the restart prevention condition is satisfied when a state in which the control according to the operation command of the motor control unit is stopped continues for a set time or longer. The electric parking brake system according to claim 1.   When the control restart prevention unit performs an operation for starting the vehicle after the control according to the operation command of the motor control unit is stopped, and for the driver to stop driving the vehicle. 3. The electric parking brake system according to claim 1, further comprising an operation state-based restart prevention condition determination unit that determines that the restart prevention condition is satisfied in at least one of cases where the operation is performed. The electric parking brake system includes a notification device that notifies an occupant of an abnormality of the system,
4. The electric parking brake system according to claim 2, wherein the control device includes a notification command unit that causes the notification device to report an abnormality when the control restart according to the operation command is blocked by the control restart blocking unit. .   5. The control restart prevention unit allows control according to the new operation command of the motor control unit when the control restart prevention unit acquires a new operation command after preventing the restart of control. The electric parking brake system described in 1.   When the voltage of the power supply is less than the set voltage that is set to a size that can prevent the malfunction of the electric parking brake system when the voltage of the power supply is a voltage that allows the control device to operate. The electric parking brake system according to any one of claims 2 to 5, further comprising an operation guarantee impossible voltage detection unit that determines that the voltage drop state is present.   The control device is configured such that the voltage of the power source is set to a minimum necessary magnitude for operating the electric motor until the parking brake device generates a parking braking force that can maintain the vehicle in a parked state. The electric parking brake system according to any one of claims 2 to 5, further comprising a driving force shortage voltage detection unit that determines that the voltage drop state occurs when the voltage is lower than a set voltage.

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