JP4222348B2 - Electric brake abnormality judgment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine abnormality in electric friction brakes 22, 32 when a vehicle is started in the vehicle including the electric friction brakes 22, 32 to be operated by motors 20, 30 based on the operation of a brake pedal 34, and a parking brake 36 to be operated by a parking brake pedal 35. <P>SOLUTION: In a state in which a vehicle is stopped by both operations of a brake pedal 34 and a parking brake pedal 35 though the creep torque is applied to wheels (S405, 407-413), and the drive signal to generate the braking torque larger than the creep torque is fed to motors 20, 30 irrespective of the operational strength of the brake pedal 34 (S406). When the operation of the parking brake pedal 35 is released without releasing the operation of the brake pedal 34 (S414, 415), the electric friction brakes 22, 32 are determined to be abnormal when the vehicle does not maintain a stopped condition (S417, 420). <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a technique for determining whether or not an electric brake is abnormal in a vehicle.

Patent Document 1 describes the following electric brake abnormality determination method. This detects an amount related to the output of the motor at the time of a brake operation, and determines that the electric brake is abnormal when the detected amount does not properly correspond to the drive signal supplied to the motor. This is an electric brake abnormality determination method.
International publication specification WO97 / 3869

However, this conventional method has a problem that an abnormality cannot be determined when the brake operation is not substantial. When starting the vehicle from the parking state, it is normal that the parking brake operation is first released and then the normal brake operation is released while both the normal brake operation and the parking brake operation are performed. However, the service brake operation during a period in which the service brake operation is performed but the parking brake operation is not performed is not a substantial brake operation, that is, a brake operation for braking the traveling vehicle. It is desirable to be able to determine an abnormality during such an insubstantial brake operation, but this has not been possible with the conventional method.
In addition, it is not possible to determine whether or not the electric brake is abnormal unless it is during the brake operation, and thus there is a problem that it is not possible to determine whether or not the electric brake is abnormal at a time preceding the substantial brake operation.
The present invention has been made against the background of the above circumstances, and an object thereof is to provide a method capable of determining whether or not there is an abnormality prior to substantial brake operation.

In the electric brake abnormality determination method according to the present invention, a creep torque for creeping the vehicle when the acceleration operation member is not operated is applied to the wheels by the power source, and the output of the power source is increased based on the operation of the acceleration operation member. The electric brake that brakes the wheel by friction force using the motor as a drive source based on the operation of the service brake operation member and the wheel based on the operation of the parking brake operation member In a vehicle including a parking brake, a method for determining whether or not the electric brake is abnormal,
In the state where the vehicle is stopped by both the operation of the service brake operation member and the operation of the parking brake operation member despite the creep torque being applied to the wheel, Regardless of the strength of the operation of the brake operation member, a predetermined drive signal is supplied to cause the motor to generate a braking torque that is greater than the creep torque, and then the operation of the service brake operation member is released. When the operation of the parking brake operation member is released without being performed, it is determined that the electric brake is abnormal when the vehicle does not maintain the stop state.

  In this method, when the parking brake operation is released and the vehicle is about to start, it is determined whether or not there is an abnormality. Here, when the vehicle is about to start, it usually means before a substantial brake operation is started. Therefore, according to this method, it is possible to determine whether or not there is an abnormality prior to a substantial brake operation.

Aspects of the Invention

Hereinafter, each aspect of the present invention will be described in the same format as the claims, with each item numbered. This is to clearly show the possibility of adopting a combination of the features described in each section.
(1) A vehicle driven by a creep torque applied to the wheels by a power source when the acceleration operation member is not operated, and the output of the power source is increased based on the operation of the acceleration operation member In a vehicle including an electric brake that brakes a wheel with frictional force using a motor as a drive source based on an operation of a service brake operation member, and a parking brake that brakes a wheel based on an operation of a parking brake operation member A method for determining whether or not the electric brake is abnormal,
In the state where the vehicle is stopped by both the operation of the service brake operation member and the operation of the parking brake operation member despite the creep torque being applied to the wheel, Regardless of the strength of the operation of the brake operation member, a predetermined drive signal is supplied to cause the motor to generate a braking torque that is greater than the creep torque, and then the operation of the service brake operation member is released. When the operation of the parking brake operation member is released without being performed, it is determined that the electric brake is abnormal when the vehicle does not maintain the stop state. Item 1].
In this method, the “power source” includes an engine (internal combustion engine) and a motor.
(2) The electric brake abnormality determination method according to (1), wherein the determination as to whether or not the electric brake is abnormal is prohibited when the acceleration operating member is operated.
According to this method, since it is determined whether or not there is an abnormality when operating the acceleration operation member, it is possible to avoid a situation in which the determination is erroneously performed.
(3) Further, when the service brake operating member is not operated, the drive signal is supplied to the motor, and in this state, an amount related to the output of the motor is detected, and the detected amount is normalized to the supplied drive signal. The electric brake abnormality determining method according to (1) or (2), wherein it is determined that the electric brake is abnormal when the electric brake is not supported.
In this method, the “amount related to the motor output” is the driving force and driving torque of the motor, the operating amount (including force, torque, stroke, etc.) of the movable member operated by the motor, or the operation by the motor. The braking force and braking torque generated on the wheels by the brake to be applied, or the vehicle deceleration.
According to this method, it is possible to determine whether or not there is an abnormality both when the parking brake operation is canceled during the service brake operation and when the service brake operation is not performed.
(4) An electric brake abnormality determination method for performing the determination described in the item (3) when the determination as to whether the abnormality is described in the item (1) cannot be performed.
According to this method, even when the brake abnormality determination cannot be performed at the start of the vehicle, it is possible to determine whether or not there is an abnormality at the time of non-braking operation. It is possible to determine whether there is an abnormality prior to the brake operation.
(5) The electric brake abnormality determination method according to (3) or (4), wherein the driving signal does not cause the wheel to generate braking torque by the electric brake.
According to this method, it is possible to determine whether or not there is an abnormality without causing the driver to feel uncomfortable.
(6) The electric brake abnormality determination method according to (3) or (4), wherein the driving signal is caused to generate braking torque on the wheel by the electric brake.
(7) The electric brake abnormality determination method according to (3) or (4), wherein the driving signal is supplied so that a substantial change does not occur in a traveling state of the vehicle during the traveling of the vehicle. Claim 5].
When the method described in the previous section is performed, a deceleration that the driver does not expect may occur in the vehicle when determining whether or not there is an abnormality, and the driver may feel uncomfortable. On the other hand, according to the method described in this section, the driving signal is supplied during the non-braking operation so that no substantial change occurs in the running state of the vehicle. It is possible to determine whether or not there is an abnormality without letting it go.
(8) The wheels are provided on the vehicle as front wheels and rear wheels, the electric brakes are provided on the front wheels and the rear wheels, respectively, and the driving signals are supplied to the electric brakes and rear wheels of the front wheels. The electric brake abnormality determination method according to any one of (3) to (7), which is performed at different times with respect to the electric brake.
According to this method, the drive signal is supplied at different times with respect to the electric brake for the front wheels and the electric brake for the rear wheels, so that the drive signal generates braking torque on the wheels by the electric brake. Even if it is a thing, the deceleration which generate | occur | produces at each time in a vehicle for determination of whether it is abnormal does not need to become so big, and it makes it suppress a driver | operator feeling uncomfortable.
(9) The vehicle is accelerated by increasing the output of the power source based on the operation of the acceleration operation member, and when the operation of the acceleration operation member is released, braking torque is applied to the wheels by the power source. Deceleration is performed by being applied as power source dependent braking torque,
When the brake operation member is not operated and when the operation of the acceleration operation member is released, the power source is controlled so that the actual value of the power source-dependent braking torque is lower than an expected value. A predetermined drive signal is supplied to the motor to be supplied to the motor in order to compensate for the reduction in the dependent braking torque by the electric brake, and the vehicle deceleration is detected in that state. The electric brake abnormality determination method according to any one of (3) to (8), wherein when the detected vehicle deceleration is smaller than a reference value, the electric brake is determined to be abnormal.
According to this method, when the electric brake is normal, the braking torque of the entire vehicle does not change depending on whether or not it is determined whether or not it is abnormal, so that the driver feels uncomfortable when determining whether or not it is abnormal. It is avoided.
In this method, the “power source” includes an engine (internal combustion engine) and a motor.
(10) The vehicle is accelerated by increasing the engine output based on the operation of the acceleration operation member, and when the operation of the acceleration operation member is released, braking torque is applied to the wheels by the engine negative pressure. It is decelerated by being applied as engine brake torque,
When the brake operation member is not operated and when the operation of the acceleration operation member is released, the engine is controlled so that the actual value of the engine brake torque is lower than an expected value, and the engine brake torque is reduced. A predetermined drive signal is supplied to the motor to be supplied to the motor in order to compensate for the electric brake, and in this state, the vehicle deceleration is detected, and the detected vehicle The electric brake abnormality determination method according to any one of (3) to (8), wherein when the deceleration is smaller than a reference value, the electric brake is determined to be abnormal.
In this method, the engine control for reducing the actual value of the engine brake torque from the expected value can be realized by increasing the engine output, and the engine output can be increased by increasing the engine speed. It is.
Further, “power source” and “engine brake torque” in this method are examples of “power source” and “power source-dependent braking torque” in the method described in the previous section, respectively.
(11) In the vehicle, the brake operation member is used as a service brake operation member, the electric brake is used as a service brake, and the machine is operated by an operation force of an emergency brake operation member different from the service brake operation member. The mechanical brake for braking the wheel is an emergency brake, and the determination as to whether the electric brake is abnormal is prohibited when the mechanical brake is activated (3) to (10) The electric brake abnormality determination method according to any one of the items.
When the brake operation member is provided in common for the service brake and the emergency brake, not only the service brake but also the emergency brake cannot be operated when the brake operation member is not operated. On the other hand, when the brake operation members are provided independently for the service brake and the emergency brake, the emergency brake operation may be performed when the service brake operation is not performed. The relationship between the motor input and output differs depending on whether or not the emergency brake operation is performed. For this reason, when the normal brake operation is not performed, whether or not the electric brake is abnormal is determined regardless of whether or not the emergency brake operation is performed. May end up. Therefore, in the method described in this section, in the vehicle in which the brake operation members are provided independently for the service brake and the emergency brake, it is determined whether the electric brake is abnormal or not. Prohibited when the brake is activated. Therefore, according to the method described in this section, erroneous determination is avoided.
(12) A vehicle driven by increasing the output of the power source based on the operation of the acceleration operation member, and a creep torque that creeps the vehicle when the acceleration operation member is not operated is applied to the wheels by the power source In addition, in a brake system including an electric brake that brakes a wheel with frictional force using a motor as a drive source based on an operation of a service brake operation member, and a parking brake that brakes a wheel based on an operation of a parking brake operation member
In the state where the vehicle is stopped by both the operation of the service brake operation member and the operation of the parking brake operation member despite the creep torque being applied to the wheel, Regardless of the strength of the operation of the brake operation member, a drive signal that is predetermined to generate a braking torque larger than the creep torque on the wheels by the motor is supplied, and then the operation of the service brake operation member is performed. An abnormality determining device is provided that determines that the electric brake driving device is abnormal when the operation of the parking brake operation member is released without being released and the vehicle is not maintained in a stopped state. Brake system to do.
In this brake system, when the parking brake operation is released and the vehicle is about to start, it is determined whether or not there is an abnormality. Here, when the vehicle is about to start, it usually means before a substantial brake operation is started. Therefore, according to this brake system, it is possible to determine whether or not there is an abnormality prior to substantial brake operation.
The “power source” in this brake system can be interpreted in the same manner as in the method described in the above item (1).

Hereinafter, more specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an overall configuration of a brake system according to an embodiment of the present invention. This brake system is provided in a four-wheel vehicle provided with left and right front wheels FL and FR and left and right rear wheels RL and RR. This vehicle includes an engine 10 (internal combustion engine) as a power source and an automatic transmission (hereinafter abbreviated as “AT”) 12 as a driving force transmission device. Drive wheels, which are at least one of the front wheels and the left and right rear wheels, are driven, thereby driving the vehicle.

  The left and right front wheels FL, FR are provided with an electric disc brake 22 (electric brake) that uses the ultrasonic motor 20 as a drive source and does not use fluid pressure. On the other hand, for the left and right rear wheels RL, RR, as an ordinary brake, an electric drum brake 32 which uses a DC motor 30 as a drive source and does not use fluid pressure (also referred to as an electric brake or a rear wheel drum brake as necessary). ), Which is actuated based on the operation of the brake pedal 34, and a mechanical drum brake 36 (mechanical brake) that uses the parking brake pedal 35 as a drive source and does not use fluid pressure as a parking brake. Is provided. The brake pedal 34 is provided as a service brake operation member, while the parking brake pedal 35 is provided as a parking brake operation member. Both the electric drum brake 32 and the mechanical drum brake 36 are provided on each rear wheel. The brake lining as the friction material and the drum as the rotating body are provided in common to the electric drum brake 32 and the mechanical drum brake 36, respectively.

  This vehicle is provided with several members operated by the driver. Some of the operation members include the brake pedal 34 and the parking brake pedal 35, an accelerator pedal 44 as an acceleration operation member, a steering wheel 46, and a shift lever 440.

When the accelerator pedal 44 is operated, the driving force of the engine 10 is increased, thereby driving the vehicle. When the steering wheel 46 is rotated, the steering wheel is steered by a steering device (not shown) accordingly. Further, when the shift lever 440 is operated, the reduction ratio of the AT 12 is changed.
The brake pedal 34 is provided with an operation stroke applying mechanism 50 that applies a stroke corresponding to the operation force to the brake pedal 34.

FIG. 2 shows details of the electric disc brake 22 for the left and right front wheels. However, in the drawing, only the electric disc brake 22 for the right front wheel is typically shown in a plan sectional view.
The electric disc brake 22 includes a mounting bracket 100 as a fixing member attached to a vehicle body (not shown), and a disc 104 having friction surfaces 102 on both sides and rotating together with wheels. The mounting bracket 100 supports the pair of brake pads 106a and 106b so as to be movable along the rotation axis of the disk 104 at a position where the disk 104 is sandwiched from both sides. In addition, the mounting bracket 100 includes a portion (receiving member) that receives a frictional force generated in each brake pad 106 a and 106 b when contacting the disc 104. In the figure, an arrow X indicates a direction in which the disk 104 rotates when the vehicle body moves forward.

  Of the pair of brake pads 106a and 106b, the outer pad 106a on the outside of the vehicle body (right side in the figure) is supported by the mounting bracket 100 in a state where rotation with the disk 104 is substantially prevented when contacting the disk 104. . On the other hand, the inner pad 106b on the inner side of the vehicle body (the left side in the figure) is supported by the mounting bracket 100 in a state where the rotation with the disc 104 is positively allowed when contacting the disc 104, unlike the outer pad 106a. Has been. In the figure, the arrow Y indicates the direction of rotation of the inner pad 106b.

  However, the accompanying rotation of the inner pad 106b is not always permitted, and is prevented when the frictional force generated between the inner pad 106b and the disk 104 is smaller than the first set value, and in a state where the friction force is greater than or equal to the first set value. It is allowed. In order to realize such follow-up control, in this embodiment, the front end portion 110 of the inner pad 106b is engaged with the mounting bracket 100 via a spring 112 as an elastic member. When the frictional force of the inner pad 106b is smaller than the first set value, the spring 112 is not elastically deformed and the inner pad 106b is prevented from being rotated, and when the friction force of the inner pad 106b is equal to or higher than the first set value, the spring 112 is elastically deformed. Thus, accompanying rotation of the inner pad 106b is allowed. Further, in the present embodiment, a stopper 114 that contacts the mounting bracket 100 when the amount of rotation of the inner pad 106b reaches the second set value is provided. As a result, the limit of the accompanying rotation of the inner pad 106b is restricted, and as a result, an excessive self-servo effect described later is prevented.

  The electric disc brake 22 includes a braking force sensor 116 that detects an amount related to the wheel braking force. In the present embodiment, the braking force sensor 116 is attached to a pressing member 134 (described later) in a state of receiving the axial force thereof, and eventually the pressing force actual value that pressurizes the inner pad 106b to the disk 104. Is detected as a wheel braking force-related quantity.

  The electric disc brake 22 further includes a caliper body 120 that is movable in the rotation axis direction of the disc 104 but cannot move in the rotation direction of the disc 104. The caliper body 120 is slidably fitted to a plurality of pins (not shown) attached to the vehicle body so as to extend parallel to the rotational axis of the disk 104. The caliper body 120 is attached to the vehicle body so as to straddle the disc 104 and sandwich the pair of brake pads 106a and 106b from behind. The caliper body 120 includes (a) a reaction portion 126 that engages with the outer pad 106a from the back, (b) a pressing portion 128 that is close to the inner pad 106b in the back, and (c) the reaction portion 126 and the pressing portion 128. It is comprised so that the connection part 130 connected mutually may be included.

  In the pressing part 128, the ultrasonic motor 20 is coaxially connected to the pressing member 134 via a ball screw mechanism 132 as a motion conversion mechanism. The pressing member 134 is supported by the pressing portion 128 so as not to rotate around the axis of the pressing member 134 and to be movable in the axial direction. Therefore, if the rotating shaft 136 of the ultrasonic motor 20 rotates, the rotational motion is converted into the linear motion of the pressing member 134 by the ball screw mechanism 132. As a result, the pressing member 134 is moved back and forth along the axis of the pressing member 134, and a pressing force is applied to the inner pad 106 b, and consequently the outer pad 106 a, and thereby the pair of brake pads 106 a and 106 b are applied to the disc 104. Pressed.

  With respect to the outer pad 106a, the thickness of the back plate 140 is uniform in the disc rotation direction X, but with respect to the inner pad 106b, the rear side (rear side in the vehicle body) from the rear side (rear side in the vehicle body) to the front side (in the vehicle body). The plate thickness is gradually reduced as the process proceeds to the front side. The back surface of the back plate 140 of the inner pad 106 b is a slope 142 with respect to the friction surface 102 of the disk 104, and the front end surface of the pressing member 134 is in contact with the inner pad 106 b on the slope 142. Further, the inclined surface 142 and the front end surface of the pressing member 134 are relatively movable along these surfaces. Therefore, in a state where the inner pad 106b is rotated, the inner pad 106b functions as a wedge between the disc 104 and the pressing member 134, and the self-servo effect of the electric disc brake 22 is realized. In the present embodiment, the axis of the pressing member 134 is perpendicular to the inclined surface 142.

Next, the operation of the electric disc brake 22 will be described.
When the brake pedal 34 is operated by the driver and the ultrasonic motor 20 is rotated accordingly and the pressing member 134 is advanced from the non-operating position, the pair of brake pads 106a and 106b are pressed against the disc 104, Thus, a frictional force is generated between each brake pad 106a, 106b and the disk 104, and the wheel is braked.

  When the frictional force of the inner pad 106b is lower than the first set value and the set load of the spring 112 cannot be overcome, the spring 112 prevents the inner pad 106b from rotating, thereby preventing the occurrence of the self-servo effect. Is done. Therefore, since the electric disc brake 22 is effective at the time of weak braking operation or the like, the wheel is braked without the self-servo effect when the frictional force of the inner pad 106b is small.

  On the other hand, if the frictional force of the inner pad 106b becomes equal to or higher than the first set value and can overcome the set load of the spring 112, the spring 112 allows the inner pad 106b to rotate. When the inner pad 106b is rotated, the inclined surface 142 slides and moves integrally with the inner pad 106b, and as a result, the distance between the friction surface 102 of the disk 104 and the inclined surface 142 increases. As a result, the inner pad 106b is strongly compressed in the thickness direction by the disk 104 and the pressing member 134, and as a result, the inner pad 106b is pressed against the disk 104 with a large force. Therefore, in a state where the frictional force of the inner pad 106b is increased because the brake pedal 34 is operated strongly (for example, a deceleration of about 0.3 to 0.6G is generated in the vehicle body), the inner pad 106b It functions as a wedge between the disk 104 and the pressing member 134, and as a result, the wheel is braked with a self-servo effect.

  If the frictional force of the inner pad 106b further increases and the stopper 114 comes into contact with the mounting bracket 100, further follow-up of the inner pad 106b is prevented, thereby preventing excessive self-servo effect.

  In this embodiment, the front wheel disc brake 22 is configured to brake the wheel using the self-servo effect, but can be configured to brake the wheel without using the self-servo effect. is there.

FIG. 3 shows details of the electric drum brake 32 for the left and right rear wheels. However, in the figure, only the electric drum brake 32 for the right rear wheel is representatively shown in a side view.
This electric drum brake 32 includes a substantially disc-shaped backing plate 200 as a non-rotating member attached to a vehicle body (not shown), and a drum 204 that has a friction surface 202 on its inner peripheral surface and rotates with a wheel. I have. An anchor pin 206 as an anchor member and an adjuster 208 as a relay link are provided at two locations separated from each other in the diameter direction of the backing plate 200. The anchor pin 206 is fixedly attached to the backing plate 200. On the other hand, the adjuster 208 is a floating type. A pair of brake shoes 210 a and 210 b each having an arc shape are attached between the anchor pins 206 and the adjuster 208 so as to face the inner peripheral surface of the drum 204. The pair of brake shoes 210a and 210b are attached to the backing plate 200 so as to be movable along the surface thereof by shoe hold-down devices 212a and 212b. In addition, an axle shaft (not shown) is rotatably provided in a through hole provided in the center of the backing plate 200.

  The pair of brake shoes 210a, 210b are connected to each other by an adjuster 208 so that they cannot be approached to each other and can be separated from each other, while the other ends are brought into contact with the anchor pins 206. It is supported so as to be rotatable around the end. One end portions of the pair of brake shoes 210a and 210b are urged by the adjuster spring 214 so as to approach each other via the adjuster 208. On the other hand, the other end portions of the pair of brake shoes 210a and 210b are urged toward the anchor pin 206 by the shoe return springs 215a and 215b. The brake linings 216a and 216b are held on the outer peripheral surfaces of the brake shoes 210a and 210b, and the pair of brake linings 216a and 216b are brought into contact with the inner peripheral surface of the drum 204, whereby the brake linings 216a and 216b and the drum 204 are contacted. A frictional force is generated between Note that the adjuster 208 wears the gap between the pair of brake linings 216a and 216b and the drum 204 by human force before assembling the vehicle body and when the vehicle is stopped, and wear of the pair of brake linings 216a and 216b while the vehicle is running. Automatically adjust according to the.

  Each of the brake shoes 210a and 210b includes a rim 220 and a web 222, and the lever 230 is rotatable in one web 222 of the pair of brake shoes 210a and 210b in a direction intersecting the rotation axis of the drum 204. Is attached. A pin 232 as a lever support member is fixedly attached to the web 222, and one end of the lever 230 is rotatably connected to the pin 232. Both ends of a strut 236 as a force transmission member are engaged with a notch in a portion where the lever 230 and the other brake shoe 210b face each other. The strut 236 has an adjusting function for adjusting the length thereof by a screw mechanism, so that a gap between the pair of brake shoes 210a and 210b and the drum 204 is made by a human force before assembling the vehicle and during stopping the vehicle. It is adjustable.

  One end of a service brake cable 240 is connected to the other end (free end) of the lever 230. The service brake cable 240 is composed of a plurality of wires and is flexible. The service brake cable 240 is driven by a shoe expansion actuator 250 attached to the backing plate 200. As shown in an enlarged view in FIG. 4, the shoe expansion actuator 250 has an input shaft of the speed reducer 252 coupled to the rotating shaft of the DC motor 30, and a ball screw mechanism 254 as a motion conversion mechanism connected to the output shaft of the speed reducer 252. The other end of the service brake cable 240 is connected to the output member of the ball screw mechanism 254. The ball screw mechanism 254 is a mechanism that converts the rotational motion of the DC motor 30 into linear motion. In the figure, reference numerals 256 and 258 both indicate brackets, and reference numerals 260 and 262 both indicate bolts for attaching the brackets 256 and 258 to the backing plate 200.

  The ball screw mechanism 254 is configured such that a nut 266 as an output member is screwed to a male screw 264 as an input member via a plurality of balls (not shown). The nut 266 is fitted to a housing 267 as a fixing member so as not to rotate but to move in the axial direction. Thereby, the rotational motion of the external screw 264 is converted into the linear motion of the nut 266. An output shaft 268 is coaxially attached to the end of the nut 266 opposite to the male screw 264 side. Intrusion of dust into the sliding portions of the male screw 264, nut 266 and output shaft 268 is prevented by the housing 267 and the extendable dust boot 270.

  The coupling between the output shaft 268 and the other end of the service brake cable 240 is performed as follows. That is, a cable mounting male screw 272 is formed at the end of the output shaft 268 opposite to the ball screw mechanism 254 side, while a cable mounting nut is mounted at the other end of the service brake cable 240. 274 is attached. The cable mounting nut 274 is screwed onto the cable mounting male screw 272, and the locking nut 276 is screwed onto the cable mounting male screw 272, and the locking nut 276 is connected to the cable mounting nut 274. The cable mounting nut 274 is prevented from loosening.

  The shoe expansion actuator 250 configured as described above applies a tensile force to the service brake cable 240 when the brake pedal 34 is operated, whereby the lever 230 is separated from the brake shoe 210b at the other end thereof. As a result, the pair of brake shoes 210 a and 210 b are expanded by the strut 236.

  The electric drum brake 32 includes a shoe contraction mechanism effective for overcoming the self-servo effect generated by the pair of brake shoes 210a and 210b and contracting them. In the present embodiment, the shoe contraction mechanism is a service brake return spring 280 stretched between the lever 230 and the backing plate 200, as shown in FIG. The service brake return spring 280 is stretched coaxially with the service brake cable 240, and has one end at the other end of the lever 230 and the other end at a fixed portion of the shoe expansion actuator 250 (for example, a housing). , Brackets, etc.). Accordingly, if the shoe expansion actuator 250 is returned toward the initial position when the operation of the brake pedal 34 is released, the lever 230 is rotated toward the initial position by the compression force of the service brake return spring 280.

  The electric drum brake 32 is provided with a brake position sensor 285 that detects its operating position. In the present embodiment, the brake position sensor 285 is configured to contact the lever 230 and detect its rotational position.

  The electric drum brake 32 has been described above. Next, the mechanical drum brake 36 will be described.

  In the mechanical drum brake 36, the components other than the service brake cable 240, the shoe extension actuator 250, and the service brake return spring 280 among the plurality of components of the motorized drum brake 32 are shared with the motorized drum brake 32. Is done. In the mechanical drum brake 36, a parking brake cable 282 and a parking brake return spring 284 coaxial therewith are used instead of the service brake cable 240, the shoe extension actuator 250, and the service brake return spring 280. used. One end of the service brake cable 240 and one end of the parking brake cable 282 are connected to the other end of the lever 230. As a result, the lever 230 can be rotated even when the mechanical drum brake 36 is operated. Thus, the pair of brake linings 216a and 216b are pressed against the drum 204, so that the rotation of the wheels is suppressed. The parking brake cable 282 is also composed of a plurality of wires and is flexible.

  The parking brake cable 282 is provided for each of the left rear wheel mechanical drum brake 36 and the right rear wheel mechanical drum brake 36. The other ends of the two parking brake cables 282 are shown in FIG. As shown in FIG. 1, it is mechanically linked to the parking brake pedal 35 via a parking brake control 300. The parking brake control 300 transmits the operating force of the parking brake pedal 35 to the two parking brake cables 282 as a tensile force.

  In the brake system configured as described above, when the brake pedal 34 is operated, a tensile force is applied to the service brake cable 240 by the shoe extension actuator 250 as shown in FIG. Is rotated in a direction in which the pair of brake shoes 210a and 210b expand (hereinafter simply referred to as “shoe expansion direction”). At this time, the parking brake cable 282 is bent because it has flexibility as described above. Therefore, in the present embodiment, the operation of the brake shoes 210 a and 210 b by the electric drum brake 32 is prevented from being hindered by the mechanical drum brake 36.

  On the other hand, when the parking brake pedal 35 is operated, a tensile force is applied to the parking brake cable 282 by the parking brake pedal 35, thereby rotating the lever 230 in the shoe extending direction. At this time, the service brake cable 240 is flexed because it has flexibility similar to the parking brake cable 282 as described above. Therefore, in the present embodiment, the operation of the brake shoes 210 a and 210 b by the mechanical drum brake 36 is prevented from being inhibited by the electric drum brake 32.

  In short, in the present embodiment, since the two cables 240 and 282 that are connected to the same lever 230 and act at different times can be deformed together, the action of one cable is hindered by the other cable. There is nothing.

  The hardware configuration of this brake system has been described above. Next, the software configuration will be described.

  As shown in FIG. 1, the brake system includes an electronic control unit (hereinafter abbreviated as “brake ECU”) 330. The brake ECU 330 is mainly configured by a computer 346 including a CPU 340, a ROM 342, and a RAM 344. Several sensors and switches are connected to the input side of the brake ECU 330. Some of the sensors and switches include the braking force sensor 116 and the brake position sensor 285, the operation force sensor 348, the parking brake pedal switch 349, the brake pedal switch 350, the accelerator pedal switch 352, the accelerator pedal operation amount sensor 353, and the like. Rudder angle sensor 354, yaw rate sensor 355, longitudinal acceleration sensor 356, lateral acceleration sensor 358, wheel speed sensor 360 for four wheels, motor rotation position sensor 362 for four wheels, motor current sensor 364 for four wheels, and shift position sensor 452.

The operating force sensor 348 detects the operating force F of the brake pedal 34 and outputs a signal indicating the magnitude thereof. The parking brake pedal switch 349 is an example of a parking brake sensor, and outputs an OFF signal (first signal) when the parking brake pedal 35 is not operated and an ON signal (second signal) when the parking brake pedal 35 is operated. The brake pedal switch 350 is an example of a service brake operation sensor, and outputs an OFF signal (first signal) when the brake pedal 34 is not operated and an ON signal (second signal) when the brake pedal 34 is operated. The accelerator pedal switch 352 is an example of an acceleration operation sensor, and outputs an OFF signal (first signal) when the accelerator pedal 44 is not operated and an ON signal (second signal) when the accelerator pedal 44 is operated. The accelerator pedal operation amount sensor 353 is an example of an acceleration operation amount sensor, detects the operation amount of the accelerator pedal 44, and outputs a signal that defines the operation amount. The steering angle sensor 354 is an example of a vehicle turning amount sensor, detects a rotation operation angle of the steering wheel 46, and outputs a signal that defines the magnitude thereof. The yaw rate sensor 355 detects the yaw rate of the vehicle and outputs a signal that defines the yaw rate. The longitudinal acceleration sensor 356 detects the deceleration _GFR in the longitudinal direction of the vehicle body and outputs a signal that defines the height thereof. The lateral acceleration sensor 358 detects the deceleration _GLR in the lateral direction of the vehicle body and outputs a signal that defines the height thereof. Each wheel speed sensor 360 detects the wheel speed of each wheel and outputs a signal that defines the magnitude of the wheel speed. Each motor rotational position sensor 362 detects the rotational position of each wheel motor 20, 30 and outputs a signal that defines the rotational position. Each motor current sensor 364 detects the current actually supplied to the coils of the motors 20 and 30 of each wheel, and outputs a signal that defines the actual supply current value. Shift position sensor 452 outputs a signal representing the position of shift lever 440.

  On the other hand, first and second drivers 366 and 368 are connected to the output side of the brake ECU 330. The first driver 366 is provided between the first battery 370 as a power source and the ultrasonic motor 20 of the electric disc brake 22 for the left and right front wheels. On the other hand, the second driver 368 is provided between the second battery 372 as a power source and the DC motor 30 of the left and right rear wheel electric drum brakes 32. When the brake pedal 34 is operated, a command is supplied from the brake ECU 330 to each driver 366, 368, and each driver 366, 368 supplies current to each motor 20, 30 from each battery 370, 372 in response to the command.

  In the present embodiment, a main battery 374 is also provided as a power source. The main battery 374 is independent of the first and second batteries 370 and 372. The main battery 374 activates the electric parts of the vehicle excluding the motors 20 and 30. Therefore, the brake ECU 330 is operated not by the first and second batteries 370 and 372 but by the main battery 374.

  Further, on the output side of the brake ECU 330, an engine ECU 454 for controlling an engine output control device (throttle control device, fuel supply control device, ignition timing control device, etc.) (not shown) of the engine 10 and a shift control device (not shown) of the AT 12 (not shown). ATECU 456 for controlling a shift solenoid and the like). The brake ECU 330 outputs a signal for suppressing the driving force to the engine output control device and the shift control device in order to suppress the spin of the driving wheel when the vehicle is driven. That is, the brake ECU 330 is also configured to execute traction control.

  Furthermore, a brake warning lamp 376 as a brake warning device and a wear warning lamp 378 as a wear warning device are provided on the output side of the brake ECU 330. The brake warning lamp 376 is lit when an electrical failure occurs in the electric disc brake 22 or the electric drum brake 32, and warns the driver of the fact that the failure has occurred. On the other hand, the wear warning lamp 378 is provided for each wheel and is turned on when it is estimated that the wear amount of the friction material of each wheel exceeds the specified value, and informs the driver of the fact that the wear amount is excessive. Warning. Note that the brake warning device may be a brake warning buzzer that gives an audible warning instead of the brake warning lamp 376 that gives a visual warning to the driver, or a combination of both.

  The ROM 342 of the computer 346 includes a normal brake control routine, a start brake abnormality check routine, a front wheel disc brake abnormality check routine, a rear wheel drum brake abnormality check routine, a front wheel disc brake wear check routine, and a rear wheel drum brake wear check routine. Various routines are stored.

  The service brake control routine is represented by a flowchart in FIG. The contents of this routine will be described below.

First, a brief description will be given.
This routine executes various types of brake control. Various types of brake control include basic control, antilock control, traction control, and vehicle stability control (hereinafter referred to as “VSC”). The “basic control” is based on output signals from the operation force sensor 348, the brake pedal switch 350, the motor rotation position sensor 362, and the motor current sensor 364, and considers the distribution of the braking force of the vehicle and the motor rotation position and motor current. The motors 20 and 30 are controlled so that the vehicle body deceleration corresponding to the operating force F is realized while monitoring the respective actual values. “Anti-lock control” is based on output signals from the brake pedal switch 350, the wheel speed sensor 360, the motor rotation position sensor 362, and the motor current sensor 364 so that the lock tendency of each wheel does not become excessive during vehicle braking. 20 and 30 control the braking torque of each wheel. “Traction control” is based on output signals from the accelerator pedal switch 352, the accelerator pedal operation amount sensor 353, the wheel speed sensor 360, the motor rotation position sensor 362, and the motor current sensor 364, and the spin tendency of the driving wheels is excessive when the vehicle is driven. In other words, the drive torque of each drive wheel is controlled by the motors 20 and 30 so as not to become inconsistent. “VSC” is based on the output signals from the steering angle sensor 354, the yaw rate sensor 355, the lateral acceleration sensor 358, the wheel speed sensor 360, the motor rotational position sensor 362, and the motor current sensor 364. The yaw moment of the vehicle is controlled by the difference in braking force between the left and right wheels so as not to become excessive.

Next, it demonstrates concretely based on FIG.
This routine is repeatedly executed while the ignition switch of the vehicle is turned on. At each execution of this routine, first, in step S1 (hereinafter, simply represented by “S1”, the same applies to other steps), a brake pedal switch 350 (represented by “brake pedal SW” in the figure). It is determined whether or not the same applies to the switch), that is, whether or not the service brake is being operated. If it is ON, the determination is YES, and basic control is performed in S2. Thereafter, in S3, it is determined whether or not anti-lock control is necessary, that is, whether or not an excessive lock tendency has occurred on the wheels. If it is assumed that anti-lock control is not required this time, the determination is NO, and one execution of this routine is immediately terminated. If it is assumed that this is necessary, the determination is YES, and in S4, anti-lock control is performed. Is executed. Subsequently, in S5, it is determined whether or not the continuous execution of the antilock control is unnecessary. Unless it becomes unnecessary, the determination is no and the process returns to S4. If it becomes unnecessary, the determination is YES, and one execution of this routine is completed.

  On the other hand, when the brake pedal switch 350 is OFF, that is, when the regular brake operation is not performed, the determination of S1 is NO, and whether or not traction control is necessary in S6, that is, It is then determined whether or not an excessive spin tendency has occurred on the drive wheels. If it is assumed that traction control is necessary this time, the determination is YES, and traction control is executed in S7. Subsequently, in S8, it is determined whether or not the continuous execution of the traction control becomes unnecessary. Unless it becomes unnecessary, the determination is no and the process returns to S7. If it becomes unnecessary, the determination is YES, and one execution of this routine is completed.

  Further, when the brake pedal switch 350 is OFF and traction control is not required, the determination of S1 is NO and the determination of S6 is also NO. In S9, whether or not VSC is required, that is, the vehicle It is determined whether or not an excessive drift-out tendency or spin tendency has occurred. If it is assumed that VSC is necessary this time, the determination is YES, and VSC is executed in S10. Subsequently, in S11, it is determined whether or not the continuous execution of the VSC is unnecessary. Unless it becomes unnecessary, the determination is no and the process returns to S10. If it becomes unnecessary, the determination is YES, and one execution of this routine is completed.

Next, a brake abnormality check will be described. The brake abnormality check is broadly divided into a check at the time of starting performed at the time of starting and a check during driving performed during the traveling. At the time of starting, when the parked vehicle is started to run, it is checked whether there is any abnormality in the brake. The running check is a check performed after the vehicle starts running.
The start brake abnormality check routine is executed with priority over the service brake control routine, and the execution of the service brake control routine is prohibited when the start brake abnormality check routine is executed. In addition, the brake abnormality check routine during traveling is as early as possible after the start of traveling only when the execution of the brake abnormality check routine at start cannot be completed because the conditions are not met when the parked vehicle starts traveling. Regardless of whether or not the start brake abnormality check routine is completed, for example, if the vehicle is started once before the vehicle actually needs to be decelerated or stopped, or the vehicle starts running, It can be executed once. As will be apparent from the following description, the latter is used in this embodiment.
Hereinafter, the start check and the running check will be sequentially described.

First, the starting check will be described.
This vehicle includes a shift lock mechanism 442 for preventing an erroneous operation of the shift lever 440. The shift lock mechanism 442 shifts the shift lever 440 from the parking position or neutral position to the drive position, L position, 2 position, or reverse position while the brake pedal 34 is not operated even when the ignition switch is turned ON. This is prohibited. Therefore, when the vehicle is started from the parking state, the driving wheel (the left and right front wheels FL, FR and the left and right rear) passes through the period in which the brake pedal 34 is operated and the AT 12 in which the output of the engine 10 in the idling state is in the force transmitting state. As a general rule, a period during which the vehicle creeps by being transmitted to at least one of the wheels RL and RR partially overlaps. Since the period during which the braking torque by the motors 20 and 30 based on the operation of the brake pedal 34 is applied to the drive wheels and the period during which the creep torque is applied to the drive wheels by the engine 10 partially overlap. is there.
On the other hand, if the motors 20 and 30 are driven so that the braking torque of the driving wheels by the motors 20 and 30 does not fall below the creep torque when the brakes are checked, the vehicle is maintained in a stopped state. By determining whether or not, it is possible to perform a brake abnormality check. Therefore, in this embodiment, a brake abnormality check is performed using creep torque.

  In this embodiment, the abnormality check is performed by using the creep torque of the same drive wheel for the wheel to which the creep torque is applied, that is, the brake of the drive wheel. It is possible to use the torque of the driving wheel or the brake of the wheel to which the creep torque is not applied, that is, the brake of the driven wheel.

  Further, in the present embodiment, the parking position and neutral position of the shift lever 440 are positions where the vehicle cannot be creeped because the output of the engine 10 is not transmitted to the driving wheels. On the other hand, the drive position, the L position, the 2 position, and the reverse position are positions that can cause the vehicle to creep in order to transmit the output of the engine 10 to the drive wheels, and are therefore referred to as creep generation positions.

The starting check is performed as shown in the time chart of FIG.
The signal of the brake pedal switch 350 is OFF at time t ₀ , then changes to ON at time t ₁ , and returns to OFF at time t ₂ . The signal of the parking pedal switch 349 is ON at time t ₀ , and returns to OFF at time t ₃ after time t _{1 and} before time t ₂ . The position of the shift lever 440 is in the creep non-occurrence position at time t ₀ , and then changes to the creep generation position at time t ₄ after time t ₁ and before time t ₃ .

In response to such an operation, the driver 366, 368 receives an abnormality check drive signal for realizing a target braking torque T _B ^* larger than a reference torque T _REF set in advance as a value equal to or greater than the actual creep torque T _C. Supplied. Therefore, if the motor 20, 30 is normal, the actual braking torque T _B is increased at timing t ₁ to the target braking torque T _B ^*. The actual creep torque T _C is 0 at time t ₁ and increases from 0 at time t ₄ . Actual braking torque T _P by the parking brake 430 is not zero at time t _0, it decreased in the period t ₃ to 0.

In time t ₃ after, for actual braking torque T _P by the parking brake 430 is 0, the torque direction for driving the vehicle actual creep torque T _C only, the torque direction to brake the actual braking by the motor 20, 30 It becomes only torque T _B, the running state of the vehicle will be determined depending on the difference between their actual creep torque T _C and the actual braking torque T _B. Therefore, the driver 366, 368, the if the target braking torque T _B ^* abnormality checking drive signal for realizing the supply, if the motor 20, 30 is normal, the actual braking torque T _B is the target braking torque Since it is equal to T _B ^* , the vehicle will not start. However, when the first abnormality (indicated by (1) in the figure) that the actual braking torque T _B does not increase to the actual creep torque T _C occurs in the motors 20 and 30, the above-mentioned abnormality checking drive is given to the drivers 366 and 368. even signal is supplied, since the actual braking torque T _B is not increased to the target braking torque T _B ^*, the parking brake 430 is released, the vehicle will be starting. Therefore, in this embodiment, it is determined whether or not the vehicle has started after time t _{3. If} the vehicle has started, it is determined that the motors 20 and 30 are abnormal.

Further, a second abnormality (indicated by (2) in the figure) occurs in the motors 20 and 30 that the actual braking torque T _B increases to the actual creep torque T _C but does not increase to the target braking torque T _B ^* . Then, when the abnormality check drive signal is supplied to the drivers 366, 368, the vehicle is initially stopped, but the driver 366, 368 is caused to gradually reduce the target braking torque T _B ^* . When the drive signal is supplied, the actual braking torque T _B falls below the actual creep torque T _C at time t ₅ , and the vehicle is started. Therefore, the present embodiment, the motor 20, 30, timing t _3, i.e., the time after which no longer affected by the parking brake 430, the abnormality checking drive signal for the actual braking torque T _B gradually decreases Is supplied. Then, because the second abnormality in the motor 20, 30 has occurred, but in the vehicle timing t ₃ are stopped, when starting the subsequent time t _5, the motor 20, 30 is abnormal Determined.

  Next, the abnormality check will be described in detail with reference to FIG. In the figure, a start-up brake abnormality check routine that is stored in the ROM of the computer of the brake ECU 330 and executed by the CPU is shown in a flowchart.

  This routine is executed sequentially and repeatedly for a plurality of drive wheels. When executing each time, first, in S401, it is determined whether or not an ignition switch (indicated by “IGSW” in the figure) is ON. If it is OFF, the determination is NO and the same step is executed again. If it is ON, the determination is YES and the next step, that is, S402 is executed. In S402, a predetermined initial check is performed on the front wheel disc brake 22. It is checked whether an abnormality such as inoperability in the mechanical system has occurred, or whether an abnormality has occurred in the electrical system, such as disconnection or short circuit. Subsequently, in S403, it is determined whether or not an abnormality has been found in at least one of the mechanical system and the electrical system of the front wheel disc brake 22. If it is assumed that an abnormality has been found this time, the determination is YES, and in S404, the brake warning lamp 376 is lit, thereby warning the driver of the abnormality.

  On the other hand, if no abnormality is found in the brakes 22 and 32 by the initial check, the determination in S403 is NO, and in S405, whether or not the brake pedal 34 is being operated, that is, the normal brake is being operated. It is determined whether or not. This determination is made, for example, as long as the condition that the brake petal switch 350 is ON is satisfied, and it is determined that the service brake is being operated, or in addition to the condition that the brake pedal switch 350 is ON, the operation force sensor 348 Unless the condition that the detected value is not 0 (or the detected value of the operation stroke sensor is not 0) is also satisfied, it is not determined that the service brake is being operated. If it is assumed that the service brake is not being operated this time, the determination is NO and the same step is executed again. However, if it is assumed that the service brake is being operated this time, the determination is YES, and the process proceeds to S406.

In S406, the pressure command value F ^* to be realized by the motors 20 and 30 is made equal to the pressure check F ^* _CHK for abnormality check, and the abnormality check drive signal is sent to the motors 20 and 30 (corresponding to drive wheels). To be supplied. Here, "abnormality checking pressure F ^* _CHK" is larger than "the reference pressure F ^* _REF", the "reference pressure F ^* _REF" is greater than "equivalent pressure F _EQU". Here, the “equivalent applied pressure F _EQU ” is set so that the braking torque T _B applied to each wheel by the motors 20 and 30 is substantially equal to the creep torque T _C applied by the engine 10.

  Thereafter, in S407, the shift position sensor 452 detects the current position of the shift lever 440. Subsequently, in S408, based on the result, it is determined whether or not the shift lever 440 is in the creep non-occurrence position (P position or N position). If it is not in the position where no creep occurs, the determination is NO, and the same step is executed again. On the other hand, if it is in the position where no creep occurs, the determination is YES, and the process proceeds to S409.

  In S409, a signal that allows the driver to start the engine 10 is output to the engine ECU 454. Thereafter, usually, the engine 10 is actually started. Subsequently, in S410, it is determined whether or not the parking pedal 35 is being operated, that is, whether or not the parking brake is being operated. For example, if the parking pedal switch (indicated by “SW” in the figure) 349 is ON, it is determined that the parking brake is being operated. If it is assumed that the parking brake is not being operated this time, the determination is NO, and the same step is executed again. On the other hand, if it is assumed that the parking brake is being operated, the determination is YES, and the flow proceeds to S411.

  In S411, a signal for permitting the driver to operate the shift lever 440 is output to the ATECU 456. Thereafter, in S412, the position of the shift lever 440 is detected again by the shift position sensor 452. Subsequently, in S413, the position of the shift lever 440 is the creep generation position (D position, L position, 2 position or R position). It is determined whether or not. It is determined whether or not the shift lever 440 has been operated from the creep non-occurrence position to the creep generation position. If it is assumed that the current position is not the creep generation position, the determination is NO, and the same step is executed again. On the other hand, if the current position is the creep generation position, the determination is YES, and the process proceeds to S414.

  In S414, it is determined whether or not the operation of the parking pedal 35 has been released, that is, whether or not the parking brake operation has been released. For example, if the parking pedal switch 349 changes from ON to OFF, it is determined that the parking brake operation has been released. If it is assumed that it has not been released this time, the determination is NO, and the same step is executed again. On the other hand, if it is assumed that it has been released, the determination is YES, and the process proceeds to S415.

  In S415, it is determined whether or not the service brake is still being operated. If the service brake operation has been released, the determination is no, the execution of this routine ends, and the abnormality check is prohibited, but if not released, the determination is yes, and the process proceeds to S416.

  In S416, it is determined whether or not an accelerator pedal switch (represented by "accelerator pedal SW" in the figure) 352 is OFF, that is, whether or not the accelerator is being operated. If the accelerator operation is being performed, the determination is NO and the execution of this routine is terminated, and abnormality check is prohibited. However, if the accelerator operation is not being performed, the determination is YES, and the process proceeds to S417.

In S417, it is determined whether or not the vehicle is stopped. For example, when the wheel speed detected by the wheel speed sensor 362 for each wheel is substantially 0, it is determined that the vehicle is stopped. If it is assumed that the vehicle is stopped this time, the determination is YES. In S418, a value obtained by subtracting the constant value ΔF from the latest pressure command value F ^* is set as a new pressure command value F ^* . Drive signal for reducing a predetermined amount a braking torque T _B of output or the wheel of the motor 20, 30 is being outputted to the driver 366, 368. Thereafter, in S419, it is determined whether or not the new applied pressure command value F ^* is greater than the reference applied pressure F ^* _REF . If it is assumed that it is large this time, the determination is YES, and the process returns to S415. While the execution of S415 to S419 is repeated, the new pressure command value F ^* becomes equal to or less than the reference pressure F ^* _REF . As a result, if the determination in S419 is NO, the execution of this routine ends. In this case, even if the pressure command value F ^* is reduced to the reference pressure F ^* _{REF, the} vehicle does not start, so it is determined that there is no abnormality in the brakes 22 and 32. As a result, the brake warning lamp 378 is displayed. It will not be lit.

On the other hand, when the vehicle starts, the determination in S417 is NO, and the brake warning lamp 378 is turned on in S420, thereby warning the driver that the brakes 22 and 32 are abnormal. The Thereafter, in S421, the pressurizing force command value F ^* is increased by a constant value ΔF, and then in S421, it is determined whether or not the vehicle has stopped. If it does not stop, determination will be NO and will return to S421. When the brakes 22 and 32 are abnormal, an attempt is made to stop the vehicle by increasing the pressure command value F ^* by a certain value ΔF. If the vehicle has stopped, the determination in S422 is YES, and the execution of this routine ends.

  In addition, when the left and right front wheels and the left and right rear wheels are driving wheels, the brake abnormality check routine at the time of starting is executed with respect to the left and right front wheels and the left and right rear wheels, respectively. When only one of the rear wheels is a drive wheel, the process is executed for only one of them. On the other hand, when at least the left and right front wheels of the left and right front wheels and the left and right rear wheels are drive wheels, the brake abnormality check routine is executed for the left and right front wheels, and the rear drum brake of FIG. It is also possible to execute an abnormality check routine.

  Next, a traveling check for checking whether there is any brake abnormality during traveling will be described. This running check is performed by executing a front wheel disc brake abnormality check routine and a rear wheel drum brake abnormality check routine.

The front wheel disc brake abnormality check routine is represented by the flowchart of FIG. 8 and is executed while the vehicle is running.
First, a brief description will be given.
This routine is executed alternately for the left front wheel and the right front wheel. If this routine is executed for each front wheel, a drive signal for driving each ultrasonic motor 20 is output to the first driver 366 as an abnormality check drive signal during non-braking operation. The abnormality check drive signal is such that power is supplied from the first battery 370 to each ultrasonic motor 20, and if each ultrasonic motor 20 is normal, the position L of the pressing member 134 as a brake position becomes equal to the specified value S _0. It is set to be supplied in an amount for. Then, the position L of the pressing member 134 is detected in a state where the abnormality check drive signal is output to the first driver 366. In the present embodiment, the position L is not directly detected, but indirectly detected by the motor rotation position sensor 362. Thereafter, it is determined whether or not the detected position L is within an allowable range where S ₁ is the lower limit value and S ₂ is the upper limit value. If so, the electric system of the disc brake 22 of the front wheels is normal. Otherwise, it is determined to be abnormal.

In the present embodiment, the specified value S ₀ is set to a value at which the pair of brake pads 106 a and 106 b do not contact the disk 104. Therefore, the abnormality check of the front wheel disc brake 22 is performed in a state in which the driver does not feel uncomfortable by not changing the vehicle body deceleration.

The contents of this routine will be specifically described with reference to FIG.
This routine is executed after the vehicle starts traveling. First, in S106, initial setting is performed. The lower limit value S ₁ and the upper limit value S ₂ are input from the ROM 342, and “0” indicates that an abnormality check to be described later is not performed on the front wheel disc brake 22, and “1” is completed. The abnormality checked flag F ₁ indicating this is set to “0”.

  Thereafter, in S107, it is determined whether or not the brake pedal switch 350 is OFF. It is determined whether or not it is during non-brake operation. If it is assumed that it is not OFF this time, the determination is NO, and in S108, it is determined whether or not the ignition switch is OFF. If it is not OFF, the determination is NO, and the process returns to S107. If it is OFF, the determination is YES, and one execution of this routine ends.

  Assuming that the brake pedal switch 350 is OFF, the determination in S107 is YES, and in S110, the antilock control (represented by “ABS” in the figure), the traction control (represented by “TRC” in the figure), and the VSC It is determined whether neither is running. This is to avoid the occurrence of an abnormality in these controls due to the abnormality check. If it is assumed that at least one of these controls is being executed this time, the determination is NO and the process proceeds to S108. However, if it is assumed that none of them is being executed, the determination is YES and the process proceeds to S111.

In S111, the abnormality check flag F ₁ is whether or not "0" is determined. It is determined whether or not an abnormality check has never been performed in the current vehicle travel. If it is assumed that it is “1” this time, the determination is NO and the process proceeds to S108, but if it is assumed that it is “0”, the determination is YES and the process proceeds to S112 and below.

  In S112 to S116, an abnormality check is performed on the disc brake 22 for the left and right front wheels which is the current execution target of this routine (hereinafter referred to as “execution target disc brake 22”).

First, in S112, the abnormality check drive signal is output to the first driver 366. Next, in S113, in the output state, the execution target disk brake 22 is controlled based on a signal from a motor rotation position sensor 362 corresponding to the execution target disk brake 22 (hereinafter referred to as “execution target motor rotation position sensor 362”). The actual rotational position of the corresponding ultrasonic motor 20 (hereinafter referred to as “execution target ultrasonic motor 20”) is detected and used as the position L of the pressing member 134. Thereafter, in S114, the retraction position of the execution target ultrasonic motor 20 is input from the RAM 344. The retracted position is set in advance by the front wheel disc brake wear check routine described later and stored in the RAM 344. Subsequently, in S115, the execution target ultrasonic motor 20 is returned to the retracted position by being reversely rotated. Thereafter, in S116, the detected position L is equal to or less than the lower limit values S ₁ or more and the upper limit value S ₂ is determined. It is determined whether or not the detected position L is within an allowable range. This time the process proceeds to S117 without going through S118 for lighting lower values S ₁ or more and the upper limit value assuming them if the determination is YES and it is S ₂ or less, a brake warning lamp 376, where, abnormal check flag F ₁ It is set to “1”. Thereafter, the process proceeds to S108.

  On the other hand, if it is assumed that the detected position L is not within the allowable range this time, the determination in S116 is NO, and the brake warning lamp 376 is turned on in S118. The driver is warned that is abnormal. Thereafter, in S119, it is determined whether or not the execution target motor rotational position sensor 362 is normal and abnormality such as disconnection or short circuit has not occurred. The cause of the detected position L deviating from the allowable range is that there is an abnormality in the execution target ultrasonic motor 20, and there is no abnormality in the execution target ultrasonic motor 20, but there is an abnormality in the execution target motor rotational position sensor 362. And investigate which of these two causes is the real cause. If it is assumed that the execution target motor rotation position sensor 362 is normal this time, the determination is YES. In S120, the execution target motor rotation position sensor 362 monitors the actual rotation position of the execution target ultrasonic motor 20 while monitoring the actual rotation position. The sonic motor 20 is returned to the retracted position or the original position. The wheel braking force by the execution target disc brake 22 is reduced to zero. Thereafter, in S121, the service brake control routine is commanded to brake the vehicle by backup control using the remaining three-wheel brakes that are expected to be normal. In the backup control, the braking force to be generated by the disc brake 22 determined to be abnormal is supplemented by the remaining three brakes, and the wheel braking force of one of the four wheels becomes zero. This is done so that yawing does not occur in the vehicle. Thereafter, the process proceeds to S108.

  On the other hand, if it is assumed that there is an abnormality in the execution target motor rotational position sensor 362, the determination in S119 is NO, and in S122, the execution is performed without using the execution target motor rotational position sensor 362 for the regular brake control routine. It is instructed to perform alternative control for controlling the target ultrasonic motor 20. For example, the execution target ultrasonic motor 20 is controlled using at least one of the braking force sensor 116 and the motor current sensor 364, or is controlled in an open loop manner without using any sensor. The process proceeds to S108.

  That is, when the cause that the detected position L deviates from the allowable range is that an abnormality has occurred in the execution target ultrasonic motor 20, the action of the disc brake 22 corresponding to the execution target ultrasonic motor 20 is activated. When the vehicle is braked with the remaining three-wheel brakes set to 0 and the cause is that an abnormality has occurred in the execution target motor rotation position sensor 362, it is expected to be normal. By using the execution target ultrasonic motor 20 without being adversely affected by the abnormal execution target motor rotational position sensor 362, the vehicle is braked with a four-wheel brake.

  The rear wheel drum brake abnormality check routine is shown in a flowchart in FIG. Hereinafter, the contents of this routine will be described. However, since there are portions in common with the front wheel disc brake abnormality check routine, those portions will be briefly described, and only characteristic portions will be described in detail.

First, a brief description will be given.
This routine is also executed alternately for the left rear wheel and the right rear wheel while the vehicle is running. If this routine is executed for each rear wheel, a drive signal for driving each DC motor 30 is output to the second driver 368 as an abnormality check drive signal during non-braking operation. This abnormality check drive signal is obtained when the electric power is supplied from the second battery 372 to each DC motor 30, and if each DC motor 30 is normal, the first position M ₁ of the lever 230 as the first brake position is a specified value T ₁₀ . A first drive signal to be supplied in an amount to equalize. Further, the second drive signal is supplied after the first drive signal, and if each DC motor 30 is normal, the second position M ₂ of the lever 230 as the second brake position is the specified value T. ₁₀ is included to be equal to a specified value T ₂₀ different from ₁₀ . In the present embodiment, the prescribed value T ₂₀ is set to prescribed value T ₁₀ value less than. Then, in each of the output state of the first drive signal and the output state of the second drive signal, the first and second positions M ₁ and M ₂ of the lever 230 as the brake position are detected. In the present embodiment, the first and second positions M ₁ and M ₂ are directly detected by the brake position sensor 285. Thereafter, the value representing the detected first position M ₁ (represented with the position where the brake lining 216 is farthest from the drum 204) is equal to or greater than the reference value T ₁ and the detected second position M _2. Is determined to be equal to or less than a reference value T ₂ smaller than the reference value T _1. If so, it is determined that the electric system of the electric drum brake 32 for the rear wheels is normal, and so on. If not, it is determined to be abnormal.

In the present embodiment, both the prescribed values T ₁₀ and T ₂₀ are set to values at which the pair of brake linings 216 a and 216 b do not contact the drum 204. Therefore, the abnormality check of the rear wheel drum brake 32 is also performed in a state in which the driver does not feel uncomfortable by not changing the vehicle body deceleration. Further, the prescribed value T ₁₀ includes a pair of brake linings 216a, position close to as long as the drum 204 capable 216b (e.g., immediately before contact position) is set to a value corresponding to, also, the prescribed value T ₂₀ is a pair The brake linings 216 a and 216 b are set to values corresponding to the positions farthest from the drum 204. Therefore, in the present embodiment, in order to detect the second position M ₂ , the second driver 368 receives a signal for preventing power from being supplied from the second battery 372 to each DC motor 30 at the second drive. It will be supplied as a signal.

Next, the contents of this routine will be specifically described with reference to FIG. However, steps common to the front wheel disc brake abnormality check routine of FIG. 8 will be briefly described.
First, in S156, initial setting is performed. The reference values T ₁ and T ₂ are input from the ROM 342, and “0” indicates that the abnormality check described later is not performed on the electric drum brake 32, and “1” indicates that it has been completed. the abnormality check flag F ₂ is shown is set to "0".

  Thereafter, in S157, it is determined whether or not a brake pedal switch (represented by “brake pedal SW” in the figure) 350 is OFF. It is determined whether or not it is during non-brake operation. If it is assumed that it is not OFF this time, the determination is NO, and it is determined in S158 whether or not the ignition switch is OFF. If it is ON, the determination is NO and the process returns to S157, but if it is OFF, the determination is YES, and one execution of this routine ends.

On the other hand, if the brake pedal switch 350 is OFF, the determination in S157 is YES, and in S159, it is determined whether or not the parking brake pedal switch (represented by “parking brake pedal SW” in the figure) 349 is OFF. Determined. The lever 230 is shared by the electric drum brake 32 and the mechanical drum brake 36. If the mechanical drum brake 36 is in operation, it is not guaranteed that the abnormality check for the electric drum brake 32 is correctly performed. is there. If it is assumed that the parking brake pedal switch 349 is ON this time, the determination is NO and the process proceeds to S158. If it is assumed that the parking brake pedal switch 349 is OFF, the determination is YES and the process proceeds to S160. In S160, it is determined whether or not any of anti-lock control (represented by “ABS” in the figure), traction control (represented by “TRC” in the figure), and VSC is being executed. If it is assumed that at least one of these controls is being executed this time, the determination is NO and the process proceeds to S158. If it is assumed that none of them is being executed, the determination is YES and the process proceeds to S161. In S161, the abnormality check flag F ₂ is whether a "0" is determined. If it is assumed that the value is “1”, the determination is NO and the process proceeds to S158. However, if it is assumed that the value is “0”, the determination is YES and the process proceeds to S162 and below.

  In S162 to S166, an abnormality check is performed on the electric drum brake 32 for the left and right rear wheels that is the current execution target of this routine (hereinafter referred to as “execution target drum brake 32”).

First, in S <b> 162, the first drive signal is output to the second driver 368. Next, in S163, in the output state, based on a signal from a brake position sensor 285 corresponding to the execution target drum brake 32 (hereinafter referred to as “execution target brake position sensor 285”), the first position M ₁ of the lever 230 is set. Is detected. Thereafter, in step S164, the second drive signal is output to the second driver 368. Subsequently, in S165, at its output state, based on a signal from the execution target brake position sensor 285, the second position M ₂ of the lever 230 is detected.

Thereafter, in S166, whether or not the detected value representing the first position M ₁ is equal to or greater than the reference value T ₁ and the detected value representing the second position M ₂ is equal to or less than the reference value T ₂ is determined. Determined. This time assumes them if the determination is YES and it is, the process proceeds to S167 without going through S168 for turning on the brake warning lamp 376, where the abnormality check flag F ₂ is set to "1". Thereafter, the process proceeds to S158.

On the other hand, this time, it is assumed that the detected value representing the first position M ₁ is not equal to or greater than the reference value T ₁ or the detected value representing the second position M ₂ is not equal to or less than the reference value T _2. Then, the determination in S166 is NO, and in S168, the brake warning lamp 376 is turned on, thereby warning the driver that the execution target drum brake 32 is abnormal. Thereafter, in S169, it is determined whether or not the execution target brake position sensor 285 is normal and abnormality such as disconnection or short circuit has occurred. The reason why the values representing the detected positions M ₁ and M ₂ are not appropriate is that the execution target DC motor 30 has an abnormality, or the execution target DC motor 30 has no abnormality, but the execution target brake position sensor 285 has no abnormality. This is to determine whether there is an abnormality. If it is assumed that the execution target brake position sensor 285 is normal this time, the determination is YES. In S170, the execution target DC motor 30 is detected by the execution target brake position sensor 285 or the motor rotation position sensor 362 corresponding to the execution target drum brake 32. The execution target DC motor 30 is returned to the retracted position or the original position while the actual rotation position is monitored. The wheel braking force by the execution target drum brake 32 is reduced to zero. Thereafter, in S171, the service brake control routine is commanded to brake the vehicle by backup control using the remaining three-wheel brakes that are expected to be normal. In the backup control, the braking force to be generated by the drum brake 32 determined to be abnormal is supplemented by the remaining three wheel brakes, and the wheel braking force of one of the four wheels becomes zero. This is done so that yawing does not occur in the vehicle. Thereafter, the process proceeds to S158.

  On the other hand, if it is assumed that there is an abnormality in the execution target brake position sensor 285, the determination in S169 is NO, and unlike the case of the front wheel disc brake abnormality check routine, the process immediately proceeds to S158. This is because basic control of the rear drum brake 32 is performed without using the brake position sensor 285 in the first place. However, it is possible to change the basic control of the rear wheel drum brake 32 to be performed using the brake position sensor 285, and in this case, as in the case of the front wheel disc brake abnormality check routine, the normal brake control is performed. The routine is instructed to perform alternative control for controlling the execution target DC motor 30 without using the execution target brake position sensor 285.

  In addition, in the present embodiment, the vehicle body deceleration is not caused by the operation of the motors 20 and 30 both when checking the abnormality of the front wheel disc brake 22 and when checking the abnormality of the rear wheel drum brake 32. However, it is possible to design so that the vehicle body deceleration is generated by the operation of the motors 20 and 30. In this case, the front wheel disc brake abnormality check routine of FIG. 8 and the rear wheel drum brake abnormality check of FIG. The routine is executed at different times, whereby the action of the front wheel disc brake 22 by the ultrasonic motor 20 and the action of the rear wheel drum brake 32 by the DC motor 30 are performed at different times, thereby causing abnormalities. Preventing the vehicle body deceleration from occurring for the check makes the driver feel uncomfortable. Desirable in terms of performing the abnormality check in no. In this embodiment, since the vehicle body deceleration does not occur due to the operation of the motors 20 and 30 both when checking the abnormality of the disc brake 22 of the front wheel and when checking the abnormality of the drum brake 32 of the rear wheel, execution of these two routines is performed. It is not essential to make timing special.

  In addition, according to the hardware configuration of the present embodiment, the parking pedal 35 can be used as an emergency brake pedal, in which case the rear wheel parking brake 430 is used as an emergency brake. It will be.

  Finally, the brake wear check will be described. This wear check is performed by executing a front wheel disc brake wear check routine shown in FIG. 10 and a rear wheel drum brake wear check routine shown in FIG.

First, a front wheel disc brake wear check routine will be schematically described.
This routine is executed alternately for each of the left and right front wheels. When this routine is executed, each ultrasonic motor 20 is driven during non-braking operation. Each ultrasonic motor 20 is stopped when the pair of brake pads 106 a and 106 b starts to contact the disk 104. As the contact rotation angle Θ, which is the rotation angle of the ultrasonic motor 20 at that time, increases, the wear amount of the pair of brake pads 106a and 106b increases. Therefore, in this embodiment, when the contact rotation angle Θ is larger than the reference value Θ ₀ , it is determined that the amount of wear of the front wheel disc brake 22 has increased abnormally.

The time when the pair of brake pads 106 a and 106 b starts to contact the disk 104 is detected by the braking force sensor 116. Here, as with the other sensors, the braking force sensor 116 has a limit in accurately detecting a small force. Therefore, in the present embodiment, the time when the braking force sensor 116 detects the detection limit value P ₀ is regarded as the time when the pair of brake pads 106 a and 106 b starts to contact the disk 104.

In addition, after detecting the contact rotation angle Θ, the ultrasonic motor 20 is reversely rotated by a certain angle ΔΘ in order to move the pressing member 134 backward by a certain distance from the position of the back surface of the inner pad 106b. The member 134 is retracted and stopped at a position retracted by a predetermined distance from the actual position of the inner pad 106b. Further, the rotational speed θ ₀ corresponding to the retracted position of the pressing member 134 of the ultrasonic motor 20 is calculated by subtracting a certain angle ΔΘ from the contact rotation angle Θ, and the value is stored in the RAM 344.

Next, the contents of this routine will be specifically described with reference to FIG.
First, in S201, it is determined whether or not a brake pedal switch (represented by “brake pedal SW” in the figure) 350 is OFF. It is determined whether or not it is during non-brake operation. If it is ON, the determination is NO, and one execution of this routine is immediately terminated. If it is OFF, the determination is YES, and the process proceeds to S202. In this S202, a braking force sensor 116, the pressing member 134 is a inner pad 106b pressurizing actual pressing force P _A on the disk 104 is detected. Subsequently, in S203, the detected actual pressing force P _A is whether the difference is less than the detection limit value P ₀ is determined. If it is smaller, the determination is YES, and in S204, a wear check drive signal for rotating the ultrasonic motor 20 forward is output to the first driver 366. Thereafter, the process returns to S202. On the contrary, when the detected actual pressing force P _A is not less than the detection limit value P _0, the determination is NO next S203, in S205, the detected actual pressing force P _A is the detection limit It is determined whether the value P ₀ is substantially equal. It is determined whether or not it is the time when the pressing member 134 starts to press the inner pad 106b against the disc 104. If it is assumed that the actual pressing force value F _S is larger than the detection limit value P ₀ , the determination is NO, and it is determined in S206 whether or not a normal rotation command signal is being output to the ultrasonic motor 20. If the forward rotation command signal is being output, the determination is YES, and after the ultrasonic motor 20 is once turned off in S207, the reverse rotation command signal is output to the ultrasonic motor 20. Thereafter, the process returns to S202. On the other hand, if the forward rotation command signal is not being output, the determination in S206 is NO, and the reverse rotation command signal is output to the ultrasonic motor 20 in S208. In either case, the pressing member 134 is retracted to correct its overshoot. Thereafter, the process returns to S202.

On the other hand, if the actual pressing force value F _S is substantially equal to the detection limit value P ₀ , the determination in S205 is YES, and the ultrasonic motor 20 is turned off in S209. Thereafter, in S210, a motor rotation position signal θ is input from the motor rotation position sensor 362, and the contact rotation angle Θ of the ultrasonic motor 20 is detected based on the signal. Subsequently, in S211, a reverse rotation command signal is output to the ultrasonic motor 20 so that the ultrasonic motor 20 reversely rotates by a certain angle ΔΘ with reference to the contact rotation angle Θ. Here, the constant angle ΔΘ is set to correspond to a distance necessary to be secured between the brake pad 106 and the disk 104 in order to prevent the brake pad 106 from being dragged by the disk 104. Further, it is desirable to set in consideration of uneven wear of the brake pad 106. By executing S211, the pressing member 134 is stopped at a position spaced apart from the actual position of the inner pad 106b. Thereafter, in S212, it detected contact rotation angle theta whether greater than the specified value theta ₀ is determined. It is determined whether or not the amount of wear of the brake pad 106 is excessive. If the detected contact rotation angle Θ is greater than the prescribed value Θ ₀ , the determination in S212 is YES, and in S213, the wear warning lamp 378 is turned on, so that the right and left front wheels are subject to execution of this routine. The driver is warned that the wear amount of the brake pad 106 of the disc brake 22 is excessive. This completes one execution of this routine. On the other hand, if the detected contact rotation angle Θ is not greater than the specified value Θ ₀ , the determination in S212 is NO, S213 is skipped, and one execution of this routine is completed.

Next, the rear-wheel drum brake wear check routine will be schematically described.
This routine is executed alternately for each of the left and right rear wheels. When this routine is executed, each DC motor 30 is driven during a brake operation. For each drum brake 30, a relationship is established between the amount of displacement ΔQ of the lever 230 by the DC motor 30 and the amount of wear of the brake linings 216a and 216b that increases as the amount of wear increases. The brake linings 216a, in a state in which 216b is not worn, when the brake linings 216a, 216b is in contact with the drum 204, represented by a non-working position Q ₀ of the displacement Delta] Q (lever 230 of the lever 230 to the reference ) And the current value I of the DC motor 30, as shown in the graph of FIG. 12, a relationship is established in which the motor current value I increases as the displacement amount ΔQ increases. Therefore, the relationship is memorized, and if the motor current value I is actually detected during the brake operation, the displacement of the lever 230 corresponding to the actual current value I of the DC motor 30 is calculated from the detected value I and the above relationship. The normal value of the amount ΔQ, that is, the normal lever displacement amount ΔQ _N is known. Further, the actual displacement amount ΔQ _A of the lever 230 is determined from the lever operating position Q ₁ that is the actual rotation position of the lever 230 at the time of the brake operation, and the lever non-operation that is the actual rotation position of the lever 230 at the time of non-braking operation it can be obtained by subtracting the position Q _0.

Therefore, in the present embodiment, based on the above knowledge, the relationship between the normal lever displacement amount ΔQ _N and the current value I of the DC motor 30 is stored in the ROM 342, and the motor current value is actually set during the brake operation. I is detected, and a normal lever displacement amount ΔQ _N corresponding to the actual current value _I is obtained from the detected value I and the stored relationship. Thereafter, the actual lever displacement amount ΔQ _A is obtained by subtracting the lever non-operation position Q ₀ from the lever operation position Q _1, and the difference between the actual lever displacement amount ΔQ _A and the normal lever displacement amount ΔQ _N is obtained. Is determined to be greater than or equal to an allowable value N. If the allowable value is equal to or greater than N, it is determined that the wear amount of the brake linings 216a and 216b is excessive.

Next, the contents of this routine will be specifically described with reference to FIG.
First, in S251, it is determined whether or not an ignition switch (represented by “IGSW” in the figure) is ON. If it is OFF, the determination is NO, and one execution of this routine is immediately terminated. If it is ON, the determination is YES and the process proceeds to S252.

In S252, initial setting is performed. Specifically, the provisional position A and the allowable value N of the lever non-operating position Q ₀ are read from the ROM 342, and “0” indicates that the wear check of the rear drum brake 32 has not been performed. The wear check completed flag F ₃ indicating that it has been completed is set to “0”. Thereafter, in S253, it is determined whether or not a brake pedal switch (represented by “brake pedal SW” in the figure) 350 is ON. It is determined whether or not the brake is being operated. If it is OFF, the determination is NO, and it is determined in S254 whether the parking brake pedal switch 349 is OFF. If it is OFF, the determination is YES, and the current lever position Q is detected by the brake position sensor 285 in S255. Subsequently, in S256, the lever position Q is set as the lever non-operation position Q _0. Stored in the RAM 344. Than it is lever inactive position Q ₀ is updated to the actual lever position Q from the temporary position A in RAM 344. On the other hand, when the parking brake pedal switch 349 is ON, the determination in S254 is NO, and S255 and S256 are skipped. This is because when the mechanical drum brake 36 is operated, the position of the DC motor 30 and the position of the lever 230 are not in a normal relationship, and nevertheless, if a wear check is performed, an erroneous result may be caused. In any case, after that, in S257, it is determined whether or not the ignition switch is OFF. If it is OFF, the determination is YES, and one execution of this routine is immediately terminated. If it is ON, the determination is NO and the process returns to S253.

On the other hand, when the brake pedal switch 350 is ON, the determination in S253 is YES, and in S258, it is determined whether the parking brake pedal switch 349 is OFF. If it is OFF, the determination is YES and the process proceeds to step S260 and the subsequent steps. If it is ON, the determination is NO and the process immediately proceeds to S257, and as a result, the wear check is prohibited. In S260, the wear check flag F ₃ whether "0" is determined. If “0”, the determination is YES and the process proceeds to step S261 and subsequent steps. However, if “1”, the determination is NO and the process immediately proceeds to S257, with the result that the wear check is prohibited. Is done.

In S261, the motor current value I is detected by the motor current sensor 264. Subsequently, in S262, the current lever position Q is detected by the brake position sensor 285. Thereafter, in S263, the detected lever position Q is stored in the RAM344 as a lever operating position Q _1. Subsequently, in S264, a normal lever displacement amount ΔQ _N corresponding to the detected motor current value I is determined in accordance with the relationship stored in the ROM 342. Thereafter, in S265, the actual lever displacement amount ΔQ _A is calculated by subtracting the latest lever non-operation position Q ₀ from the lever operation position Q ₁ . Subsequently, in S266, it is determined whether or not the difference between the normal lever displacement amount ΔQ _N and the actual lever displacement amount ΔQ _A is equal to or larger than the allowable value N. If the difference is equal to or larger than the allowable value N, the determination is YES. In S267, the wear warning lamp 378 is turned on, so that the driver is warned that the wear amount of the brake linings 216a and 216b is excessive with respect to the drum brake 32. Thereafter, in S268, the wear check flag F ₃ is set to “1”, and the process proceeds to S257.

In this routine, the actual position of the lever 230 is detected with respect to the operating position and the non-operating position, the actual lever displacement amount ΔQ _A is calculated, and this is compared with the normal lever displacement amount ΔQ _N. Although the wear check is performed, it is possible to perform the wear check by detecting the actual position of the lever 230 only with respect to the operating position and comparing it with the normal operating position.

Since the ultrasonic motor 20 can generate a large stationary holding torque, it can be used as a parking brake, and the mechanical drum brake 36 can be used as an emergency brake. The ultrasonic motor 20 is actuated in response to an operation of a parking brake pedal as a parking brake operating member, and the supply of current is stopped in the actuated state. When the parking brake is released, the ultrasonic motor 20 may be operated in the reverse direction. On the other hand, the mechanical drum brake 36 is operated by an emergency brake operation member different from the parking brake operation member.
Further, the drive source of the front wheel disc brake 32 can be changed from the ultrasonic motor 20 to the DC motor. In that case, the rear-wheel drum brake 36 (mechanical type) can be used not only as a parking brake but also as an emergency brake. The parking brake pedal 35 is a dual-use brake operation member that is used not only as a parking brake operation member but also as an emergency brake operation member.

  Another embodiment of the present invention will be described. However, only elements different from the above-described embodiment will be described in detail, and the same elements will be denoted by the same reference numerals and detailed description thereof will be omitted.

In the above-described embodiment, the motors 20 and 30 do not substantially actuate the brakes 22 and 32 when the abnormality is checked while the front wheel disc brake 22 and the rear wheel drum brake (electric drum brake) 32 are running. The material is driven so as not to contact the rotating body. On the other hand, in this embodiment, at the time of abnormality check, an abnormality check drive signal for driving the motors 20 and 30 so that the friction material is weakly in contact with the rotating body is output to the drivers 366 and 368. The braking force f _A is detected in the output state, and it is determined whether or not the braking force f _A is within the allowable range. If the braking force f _A is not within the allowable range, it is determined that the brakes 22 and 32 are abnormal. As described above, in the present embodiment, the motors 20 and 30 are driven so that the friction material weakly contacts the rotating body at the time of abnormality check. Deceleration occurs in the front and rear wheels.

  Therefore, in this embodiment, the abnormality check is performed at different times with respect to the front wheel disc brake 22 and the rear wheel drum brake 32, thereby preventing a large deceleration from occurring in the vehicle body during the abnormality check. As a result, it is possible to prevent the driver from feeling uncomfortable.

  In the present embodiment, the abnormality check is performed only when the vehicle is traveling at a low speed, and is prohibited when the vehicle is traveling at a high speed. This is because the driver feels vehicle body deceleration accompanying the abnormality check more easily during high-speed driving than during low-speed driving.

  FIG. 13 is a flowchart showing a brake abnormality check routine common to the front wheel disc brake 22 and the rear wheel drum brake 32. This routine is performed so that the front wheel disc brake 22 and the rear wheel drum brake 32 are different from each other, that is, the abnormality check for the other brake is not started before the abnormality check for one brake is completed. However, the left and right wheels may be performed at substantially the same time or at different times. This is common for the front and rear wheels.

  First, in S381, it is determined whether or not the brake pedal switch 350 (indicated by “brake pedal SW” in the figure) is OFF. It is determined whether or not it is during non-brake operation. If it is ON, the determination is NO, and one execution of this routine is immediately terminated. If it is OFF, the determination is YES, and the process proceeds to S382.

In S382, along with the current value of the vehicle speed V is detected by a vehicle speed sensor (not shown), whether or not the vehicle speed V is less than the reference value V ₀ is determined. It is determined whether the vehicle is currently traveling at a low speed. The vehicle speed sensor detects the rotational speed of the output shaft of the AT 12 and detects the vehicle speed based on the result, or estimates the vehicle speed based on the plurality of wheel speeds detected by the wheel speed sensor 362. The format can be If the vehicle speed V is greater than the reference value V ₀ , the determination is NO and one execution of this routine is immediately terminated. If the vehicle speed V is less than or equal to the reference value V ₀ , the determination is YES, and in S383 The abnormality check drive signal is output to the driver 366 or 368. Thereafter, the braking force f _A is detected in S384. The front wheel disc brake 22 is detected by the braking force sensor 116, while the rear wheel drum brake 32 is detected by the brake position sensor 285. The rear wheel drum brake 32 is not provided with a braking force sensor. On the other hand, there is a certain relationship between the braking force and the brake position, that is, the rotation position of the lever 230. This is because the braking force can be estimated from the position.

Subsequently, in S385, it is determined whether or not the detected braking force f _A is within an allowable range. Since it is determined whether or not the detected braking force f _A is between the lower limit value (= reference value f _A0 −allowable value Δ) and the upper limit value (= reference value f _A0 + allowable value Δ). is there. This time, if it is assumed that it is not within the allowable range, the determination is NO, and in S386, the brake warning lamp 376 is turned on to warn the driver that the brakes 22 and 32 are abnormal. On the other hand, this time, if it is assumed that the detected braking force f _A is within the allowable range, the determination in S385 is YES, and S386 is skipped. In any case, one execution of this routine is completed.

  Still another embodiment of the present invention will be described. However, since this embodiment has the same hardware configuration as that of the above embodiment, and the only difference is the software configuration of the brake abnormality check during traveling, the hardware configuration will be described in detail by using the same reference numerals. And only the software configuration will be described in detail.

  If the operation of the accelerator pedal 44 is canceled while the vehicle is running, the engine brake is applied to the engine 10 and, as a result, the engine brake torque is applied to the drive wheels. At this time, deceleration occurs in the wheels and the vehicle. The deceleration occurs directly on the driving wheel, but indirectly on the driven wheel via the vehicle body, and thus more significantly occurs on the driving wheel than on the driven wheel. In this way, there is a time when the driver feels deceleration of the vehicle body even when the service brake is not being operated. On the other hand, the engine brake torque can be reduced by increasing the idle speed of the engine 10. Therefore, even when the motors 20 and 30 are driven to generate braking torque when the service brake operation is not performed, the engine braking torque (power source dependent braking torque) is reduced as well as the reduction. If the braking torque is generated by that amount, the motors 20 and 30 can be driven without increasing the deceleration of the wheels and the vehicle. If there is an abnormality in the motors 20 and 30 at the time of driving, the actual braking torque becomes smaller than the reduction amount of the engine braking torque, and as a result, the deceleration of the wheels and the vehicle is normal when the motors 20 and 30 are normal, that is, Smaller than before the engine brake torque is reduced.

  Therefore, in the present embodiment, when neither the arcel operation nor the regular brake operation is performed, the engine brake torque is reduced by increasing the idle rotation speed of the engine 10, and the motor 20 in the brake of the drive wheel, 30, an abnormality check drive signal for increasing the actual braking torque by the reduced amount is output, and in that output state, the actual wheel deceleration of the drive wheel (actual vehicle deceleration is acceptable) is detected. Then, it is determined whether or not the detected actual wheel deceleration is smaller than the determination value. If it is smaller, it is determined that the motors 20 and 30 are abnormal.

  The reduction amount of the engine brake torque can be an amount necessary for making the engine brake torque zero or an amount necessary for making the amount non-zero. In the former case, it is normal. The motors 20 and 30 generate a braking torque having a magnitude equal to the normal engine brake torque. In the latter case, a braking torque smaller than the normal engine brake torque is generated.

  In order to perform such an abnormality check, a brake abnormality check routine represented by a flowchart in FIG. 14 is stored in the ROM of the brake ECU 330.

  This routine is executed sequentially and repeatedly for a plurality of drive wheels. When executing each time, first, in S501, it is determined whether or not a non-accelerator operation is being performed. The determination can be performed using the accelerator pedal switch 352. If it is assumed that the accelerator operation is being performed this time, the determination is NO, and the same step is executed again. On the other hand, if it is assumed that the non-accelerator operation is being performed, the determination is YES, and the process proceeds to S502.

  In S502, it is determined whether or not a non-brake operation is being performed. This determination can be performed using at least one of the brake pedal switch 350 and the operation force sensor 348. If it is assumed that the service brake is being operated this time, the determination is NO, and the same step is executed again. On the other hand, if it is assumed that the non-brake operation is being performed, the determination is YES, and the process proceeds to S503.

In step S <b> 503, an idle up command for increasing the idle speed of the engine 10 is output to the engine ECU 330. In the present embodiment, the idle up command is output as a command for reducing the engine brake torque to substantially zero. After that, in S504, for each driver 366, 368, an abnormality check is performed so that the braking torque is generated on each drive wheel by each motor 20, 30 with the same magnitude as the engine brake torque that decreases in accordance with the idle increase. Drive signal is output. Subsequently, in S505, the actual wheel speed V _W of each driving wheel is detected by the wheel speed sensor 362, and then in S506, the wheel deceleration GV _W of each driving wheel is calculated. The calculation is performed by subtracting the previous value from the current value of the actual wheel speed V _W. Subsequently, in S507, it is determined whether or not the calculated wheel deceleration GV _W is smaller than a determination value G ₀ . If it is assumed that it is not small this time, the determination is NO, and in S508, an idle down command for returning the idle speed of the engine 10 to a normal value is output to the engine ECU 454. Thereafter, in S509, a signal for returning the motors 20 and 30 to the non-operating position is output to the drivers 366 and 368. This is the end of the execution of this routine. In this case, it is determined that the motors 20 and 30 are normal, and the brake warning lamp 376 is not turned on.

On the other hand, when the calculated wheel deceleration GV _W is smaller than the determination value G ₀ , the determination in S507 is YES, and the brake warning lamp 376 is lit in S510, whereby the brakes 20, 30 are determined. The driver is warned that there is an abnormality. Thereafter, the execution of this routine is terminated through S508 and S509.

  By the way, the magnitude of the engine brake torque is not always constant and changes depending on the vehicle speed. Therefore, in this embodiment, the relationship between the vehicle speed and the engine brake torque, the relationship between the engine brake torque and the idle up command, and the relationship between the braking torque and the abnormality check drive signal are stored in the ROM. Each of the idle up command and the abnormality check drive signal is determined according to the vehicle speed.

  Although several embodiments of the present invention have been described in detail with reference to the drawings, various modifications and improvements can be made based on the knowledge of those skilled in the art without departing from the scope of the claims. The present invention can be implemented in such a form.

It is a systematic diagram showing a brake system which is one embodiment of the present invention. FIG. 2 is a plan sectional view showing the front wheel disc brake in FIG. 1. It is side surface sectional drawing which shows the rear-wheel drum brake in FIG. It is a side view which expands and shows the shoe expansion actuator in a rear-wheel drum brake. 2 is a flowchart showing a service brake control routine stored in a ROM of a computer of the ECU in FIG. 3 is a graph for explaining the principle of a start brake abnormality check in the brake system of FIG. 1. It is a flowchart which shows the brake abnormality check routine at the time of start memorize | stored in the said ROM. It is a flowchart which shows the front-wheel disc brake abnormality check routine memorize | stored in said ROM. It is a flowchart which shows the rear-wheel drum brake abnormality check routine memorize | stored in the said ROM. 4 is a flowchart showing a front wheel disc brake wear check routine stored in the ROM. It is a flowchart which shows the rear-wheel drum brake wear check routine memorize | stored in the said ROM. It is a graph for demonstrating the operation | movement principle of a rear-wheel drum brake abrasion check routine. It is a flowchart which shows the brake abnormality check routine memorize | stored in ROM of the computer of ECU of the brake system which is another embodiment of this invention. It is a flowchart which shows the brake abnormality check routine memorize | stored in ROM of the computer of ECU of the brake system which is further another embodiment of this invention.

Explanation of symbols

20 Ultrasonic Motor 22 Electric Disc Brake 30 DC Motor 32 Electric Drum Brake 34 Brake Pedal 35 Parking Brake Pedal 36 Mechanical Drum Brake 44 Accelerator Pedal 330 Brake ECU
440 Shift lever

Claims (5)

A creep torque that creeps the vehicle when the acceleration operation member is not operated is applied to the wheels by a power source, and the vehicle is driven by increasing the output of the power source based on the operation of the acceleration operation member. A vehicle including an electric brake that brakes a wheel with frictional force using a motor as a drive source based on an operation of a service brake operation member; and a parking brake that brakes a wheel based on an operation of a parking brake operation member. A method for determining whether or not the type brake is abnormal,
In the state where the vehicle is stopped by both the operation of the service brake operation member and the operation of the parking brake operation member despite the creep torque being applied to the wheel, Regardless of the strength of the operation of the brake operation member, a predetermined drive signal is supplied to cause the motor to generate a braking torque that is greater than the creep torque, and then the operation of the service brake operation member is released. When the operation of the parking brake operation member is released without being performed, it is determined that the electric brake is abnormal when the vehicle does not maintain the stopped state. The electric brake abnormality determination method according to claim 1, wherein determination of whether or not the electric brake is abnormal is prohibited when the acceleration operation member is operated. Further, the drive signal is supplied to the motor when the service brake operating member is not operated, and in this state, an amount related to the output of the motor is detected, and the detected amount does not properly correspond to the supplied drive signal. 3. The electric brake abnormality determination method according to claim 1, wherein the electric brake is determined to be abnormal. An electric brake abnormality determination method for performing the determination of claim 3 when the determination of claim 1 cannot be performed. The electric brake abnormality determination method according to claim 3 or 4, wherein the drive signal is supplied so that a substantial change does not occur in a running state of the vehicle during the running of the vehicle.

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