Vehicle control device and brake control device

Abstract

Brake control device with: a first control circuit for controlling a first braking mechanism for generating a braking force for a vehicle; a second control circuit for controlling a second braking mechanism for generating, independently of the first braking mechanism, a braking force for the vehicle; a hydraulic pressure sensor (29) electrically connected to the second control circuit for detecting a hydraulic pressure for calculating a braking force to be generated; and a signal line (27) for electrically connecting the first control circuit and the second control circuit to enable the transmission of a detection signal based on a detection value of the hydraulic pressure sensor (29), wherein: the second control circuit is configured to determine whether there is an abnormality in the hydraulic pressure sensor (29) based on the detection value of the hydraulic pressure sensor (29); the first control circuit is arranged to receive the detection signal of the hydraulic pressure sensor (29) by transmission from the second control circuit via the signal line (27), and is arranged to determine, on the basis of the detection signal received by the transmission, whether an abnormality exists in the hydraulic pressure sensor (29) at a time before the time at which the second control circuit makes the determination, and the first control circuit is arranged not to issue a warning of the occurrence of the abnormality when the first control circuit detects the occurrence of the abnormality in the hydraulic pressure sensor (29), and the second control circuit is arranged to issue the warning of the occurrence of the abnormality when the second control circuit detects the occurrence of the abnormality in the hydraulic pressure sensor (29).

Description

BACKGROUND OF THE INVENTION TECHNICAL FIELD

[0001] The present invention relates to a vehicle control device and a brake control device which are suitably used for a vehicle such as a four-wheeled automobile. STATE OF THE ART

[0002] A brake control device mounted in a vehicle such as a four-wheeled automobile, for example, includes a master cylinder pressure control device (i.e., a first brake mechanism), a first control circuit, a wheel cylinder pressure control device (i.e., a second brake mechanism), and a second control circuit. The master cylinder pressure control device controls a master cylinder pressure generated in a master cylinder by an electric actuator based on a braking operation amount applied by a driver. The first control circuit electronically controls the drive of the electric actuator of the first brake mechanism.The wheel cylinder pressure control device is provided between a wheel cylinder for braking, which is provided on each wheel side of the vehicle, and the master cylinder to variably control the master cylinder pressure generated by the first braking mechanism as a wheel cylinder pressure for each wheel, thereby individually supplying the wheel cylinder pressure to each wheel cylinder of each wheel. The second control circuit electrically controls the drive of the second braking mechanism (see, for example, JP 2011-73535 A).

[0003] A hydraulic pressure sensor for detecting the master cylinder pressure generated in the master cylinder is provided between the first control circuit and the second control circuit. The first control circuit controls the drive of the electric actuator of the first brake mechanism based on a detection value of the hydraulic pressure sensor to thereby control the master cylinder pressure, while the second control circuit controls the wheel cylinder pressure for each wheel side by the second brake mechanism based on the detection value of the hydraulic pressure sensor.

[0004] In the above-described prior art, the following configuration is used to reduce the number of sensors such as the hydraulic pressure sensor. Specifically, the detection signal obtained by the single hydraulic pressure sensor is used for both controlling the master cylinder pressure by the first control circuit and controlling the wheel cylinder pressure by the second control circuit. Due to this configuration, for example, even if an abnormality in the sensor is detected as a result of the determination of whether the detection signal of the hydraulic pressure sensor is abnormal by the first control circuit, the second control circuit continues to execute control using the detection signal of the hydraulic pressure sensor in some cases. As a result, there arises a problem that it is difficult to ensure control reliability.

[0005] DE 10 2008 037 141 A1 relates to a brake control device having two control circuits for controlling two independent braking mechanisms and a pressure sensor electrically connected to the second control circuit. Furthermore, a signal line is provided for electrically connecting the two control circuits and enabling transmission of a detection signal based on a detection value of the pressure sensor. The second control circuit is configured to detect an abnormality in the pressure sensor based on the detection value, and the first control circuit is configured to receive the detection signal of the pressure sensor from the second control circuit via the signal line.

[0006] A similar brake control device is known from DE 10 2008 029 310 A1. DESCRIPTION OF THE INVENTION

[0007] To solve the above-mentioned problem, a brake control device and a vehicle control device having the features of claims 1 and 7, respectively, are provided. Advantageous embodiments are described in the further claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In the attached drawings: Fig. 1 is an overall configuration diagram showing a brake control device as a vehicle control device according to a first embodiment of the present invention; Fig. 2 is a block diagram showing a wire connection relationship between two control circuits and a hydraulic pressure sensor; Fig. 3 is a characteristic diagram showing a determination of whether an abnormality exists in a sensor according to the first embodiment of the present invention; and Fig. 4 is a characteristic diagram showing a determination of whether there is an abnormality in a sensor according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Now, a vehicle control device and a brake control device according to embodiments of the present invention will be described in detail with reference to the accompanying drawings, taking a brake control device to be mounted in a four-wheeled automobile as an example.

[0010] Fig. 1 to 3 show a brake control device according to a first embodiment of the present invention. In Fig. 1, a right front wheel 1R, a left front wheel 1L, a right rear wheel 2R, and a left rear wheel 2L are provided on a lower side of a vehicle body (not shown) that constitutes a body of a vehicle. A front-wheel-side wheel cylinder 3R is provided on the right front wheel 1R, while a front-wheel-side wheel cylinder 3L is provided on the left front wheel 1L. Similarly, a rear-wheel-side wheel cylinder 4L is provided on the right rear wheel 2R, while a rear-wheel-side wheel cylinder 4L is provided on the left rear wheel 2L. The wheel cylinders 3R, 3L, 4R, and 4L are cylinders of a hydraulic disc brake or drum brake. Each of the wheel cylinders 3R, 3L, 4R, and 4L applies braking force to each of the wheels (front wheels 1R and 1L and rear wheels 2R and 2L).

[0011] A brake pedal 5 is provided on a front panel side (not shown) of the vehicle body. The brake pedal 5 is operated by a driver and is depressed in a direction indicated by arrow A in Fig. 1, at the time of a braking operation for the vehicle. The brake pedal 5 is provided with a brake switch 6 and an operation amount detection sensor 7. The brake switch 6 detects whether a braking operation for the vehicle is being performed and, for example, turns on and off a brake lamp (not shown). The operation amount detection sensor 7 detects an entry operation amount of the brake pedal 5 as a stroke amount and outputs a detection signal to the control circuits 26 and 32 and a vehicle data bus 28, which will be described later. The entry amount of the brake pedal 5 is transmitted to a master cylinder 8 through a booster 16, which constitutes a part of an electric booster, which will be described later.Note that, in this embodiment, the operation amount detection sensor 7 detects the stroke amount of the brake pedal 5 as the entry operation amount of the brake pedal 5, but the entry operation amount to be detected by the operation amount detection sensor 7 is not limited to this. For example, an entry force can be detected as an entry operation amount of the brake pedal 5.

[0012] The master cylinder 8 includes a cylinder main body 9 having a cylindrical shape and a closed end. More specifically, the cylinder main body 9 has an open end on one side and a bottom portion on the other side. The open-end side of the cylinder main body 9 is fixedly and removably attached to a booster housing 17 of the booster 16, which will be described later, using a plurality of fastening bolts or the like (not shown). The master cylinder 8 includes the cylinder main body 9, a first piston (including a booster piston 18 and an input piston described later), a second piston 10, a first hydraulic chamber 11A, a second hydraulic chamber 11B, a first return spring 12, and a second return spring 13.

[0013] Here, in the first piston, the master cylinder 8 includes the booster piston 18 and the input piston 19, which will be described below. The first hydraulic chamber 11A formed in the cylinder main body 9 is defined between the second piston 10 and the booster piston 18 (and the input piston 19). The second hydraulic chamber 11B is defined within the cylinder main body 9 between the bottom portion of the cylinder main body 9 and the second piston 10.

[0014] The first return spring 12 is arranged in the first hydraulic chamber 11A and provided between the booster piston 18 and the second piston 10 to bias the booster piston 18 toward the open-end side of the cylinder main body 9. The second return spring 13 is arranged in the second hydraulic chamber 11B and provided between the bottom portion of the cylinder main body 9 and the second piston 10 to bias the second piston 10 toward the first hydraulic chamber 11A.

[0015] When the booster piston 18 (the input piston 19) and the second piston 10 move within the cylinder main body 9 toward the bottom portion of the cylinder main body 9 in association with the pedal operation of the brake pedal, the master cylinder 8 generates a hydraulic pressure as a master cylinder pressure by a brake fluid in the first hydraulic chamber 11A and the second hydraulic chamber 11B.On the other hand, when the brake pedal operation is stopped and the booster piston 18 (and the input piston 19) and the second piston 10 are displaced by the first return spring 12 and the second return spring 13 toward the opening portion of the cylinder main body 9 in a direction indicated by the arrow B, the cylinder main body 9 of the master cylinder 8 releases the hydraulic pressure in the first hydraulic chamber 11A and the second hydraulic chamber 11B while being supplied with the brake fluid from a reservoir 14.

[0016] The reservoir 14, which stores the brake fluid therein, is provided as a working fluid tank of the cylinder main body 9 of the master cylinder 8. The reservoir 14 supplies and discharges the brake fluid to and from the hydraulic chambers 11A and 11B within the cylinder main body 9. The hydraulic pressure as a master cylinder pressure generated in the first hydraulic chamber 11A and the second hydraulic chamber 11B of the master cylinder 8 is transmitted to an ESC 30, which will be described later, which is a hydraulic pressure supply device through, for example, a pair of cylinder-side hydraulic lines 15A and 15B.

[0017] The booster 16 is provided as a part of the electric booster for increasing an operating force on the brake pedal 5 between the brake pedal 5 of the vehicle and the master cylinder 8. The booster 16 and the control circuit 26 configure the electric booster. Together with the master cylinder 8, the booster 16 forms a master cylinder pressure control mechanism (i.e., a first mechanism or a first braking mechanism). Here, the control circuit 26 controls the drive of an electric actuator 20, which will be described later, based on the output of the operating amount detection sensor 7, and the master cylinder pressure control mechanism controls the hydraulic pressure (i.e., the master cylinder pressure) generated in the master cylinder 8.

[0018] The booster 16 as the first braking mechanism includes the booster case 17, the booster piston 18, and the electric actuator 20, which will be described later. The booster case 17 is provided to be mounted on a front wall of a vehicle interior (not shown), which is the front panel of the vehicle body. The booster piston 18 is provided as a drive piston on the booster case 17 so as to be movable (i.e., movable forward and backward in the axial direction of the master cylinder 8). The electric actuator 20 applies a booster thrust to the booster piston 18.

[0019] The booster piston 18 is formed of a cylindrical member which is movably inserted and fitted into the cylinder main body 9 of the master cylinder 8 from the open side in the axial direction. On the inner peripheral side of the booster piston 18, the input piston 19 is slidably inserted and fitted. The input piston 19 is configured as an axial member which is directly pressed in conjunction with the operation of the brake pedal 5 so as to move it forward and backward in the axial direction of the master cylinder 8 (i.e., in directions indicated by arrows A and B in Fig. 1). The input piston 19 forms the first piston of the master cylinder 8 together with the booster piston 18. Within the cylinder main body 9, the first hydraulic chamber 11A is formed between the second piston 10, the booster piston 18, and the input piston 19.

[0020] The booster housing 17 includes a reduction gear housing 17A having a cylindrical shape, a support housing 17B having a cylindrical shape, and a lid body 17C having a cylindrical shape and a step. The reduction gear housing 17A accommodates a speed reduction gear mechanism 23, which will be described later, therein. The support housing 17B is provided between the reduction gear housing 17A and the cylinder main body 9 of the master cylinder 8, and supports the booster piston 18 so that the booster piston 18 is slidably displaceable in the axial direction. The lid body 17C is provided on the side opposite to the support housing 17B in the axial direction through the reduction gear housing 17A therebetween, and closes an opening of the reduction gear housing 17A on one side in the axial direction.On the outer peripheral side of the reduction gear case 17A, a support plate 17D for fixedly supporting an electric motor 21, which will be described later, is provided.

[0021] The input piston 19 is inserted into the booster housing 17 from the cover body 17C side, and extends in the booster piston 18 in the axial direction toward the first hydraulic chamber 11A. An end surface of the input piston 19 on a distal end side (another side in the axial direction) is exposed to the hydraulic pressure generated in the first hydraulic chamber 11A as a braking reaction force at the time of braking operation. The input piston 19 transmits the generated hydraulic pressure to the brake pedal 5. As a result, a suitable pedal feel is provided to the driver of the vehicle through the brake pedal 5. Therefore, a good pedal feel (good braking) can be generated. Accordingly, an operation feel of the brake pedal can be improved to achieve a good braking feel.

[0022] The electric actuator 20 of the booster 16 includes the electric motor 21, the speed reduction gear mechanism 23 such as a belt, and a linear motion mechanism 24 such as a ball screw. The electric motor 21 is mounted on the reduction gear housing 17A of the booster housing 17 through the support plate 17D therebetween. The speed reduction gear mechanism 23 transmits the rotation of the electric motor 21 to a cylindrical rotating body 22 provided in the reduction gear housing 17A after the rotational speed is reduced. The linear motion mechanism 24 converts the rotation of the cylindrical rotating body 22 into axial displacement (forward and backward movement) of the booster piston 18.The booster piston 18 and the input piston 19 each have front ends (ends on the other side in the axial direction) exposed in the first hydraulic chamber 11A of the master cylinder 8, and generate the brake fluid pressure in the master cylinder 8 by the pedal force (thrust) transmitted from the brake pedal 5 to the input piston 19 and the booster thrust transmitted from the electric actuator 20 to the booster piston 18.

[0023] The booster piston 18 of the booster 16 forms a pumping mechanism, which is driven by the electric actuator 20 based on the output from the operating amount detection sensor 7 (i.e., a brake command) to generate the brake fluid pressure (master cylinder pressure) in the master cylinder 8. A return spring 25 for continuously biasing the booster piston 18 in a direction in which the brake is released (direction indicated by arrow B in Fig. 1) is provided within the support housing 17B of the booster housing 17. At the time of releasing the braking operation, the electric motor 21 is driven in a reverse direction, while the booster piston 18 returns to an initial position, which is Fig. 1 is shown in the direction indicated by arrow B, is moved back by a biasing force of the return spring 25.

[0024] The electric motor 21 is configured, for example, as a brushless DC motor. A rotation sensor 21A, called a coordinate converter, is provided in the electric motor 21. The rotation sensor 21A detects a rotation position (rotation angle) of the electric motor 21 (motor shaft) and outputs a detection signal to a control unit, which is a first control circuit (hereafter, the control circuit 26). The first control circuit 26 performs feedback control based on the rotation position signal. The rotation sensor 21A functions as a rotation detection device for detecting an absolute displacement position of the booster piston 18 with respect to the vehicle body based on the detected rotation position of the electric motor 21.

[0025] Furthermore, the rotation sensor 21A, together with the operating amount detection sensor 7, constitutes displacement detection means for detecting a relative displacement amount between the booster piston 18 and the input piston 19. The detection signals of the rotation sensor 21A and the operating amount detection signal 7 are transmitted to the first control circuit 26. The rotation detection means is not limited to the rotation sensor 21A, such as a coordinate converter, but may also be a rotary potentiometer capable of detecting the absolute displacement (rotation angle). The speed reduction mechanism 23 is not limited to a belt or the like, but may also be configured using, for example, a gear reduction gear mechanism or the like. The speed reduction mechanism 23 is not necessarily provided.For example, the following configuration can be used. The motor shaft is provided on the cylindrical rotating body 22 so as to be integral therewith, and a stator of the electric motor is provided around the cylindrical rotating body 22. In this way, the cylindrical rotating body 22 can be directly driven by the electric motor.

[0026] The first control circuit 26 is, for example, a microcomputer, and configures the first control circuit for electrically controlling the driving of the electric actuator 20 of the booster 16, which forms the first braking mechanism. An input side of the first control circuit 26 is connected to the operating amount detection sensor 7 for detecting the operating amount of the pedal force on the brake pedal 5, the rotation sensor 21A of the electric motor 21, a signal line 27 mounted in the vehicle, called, for example, "L-CAN," which is capable of performing data transmission, and the vehicle data bus 28 for supplying power and transmitting and receiving a signal from a control circuit of another vehicle component. The vehicle data bus 28 is a serial transmission unit called "V-CAN," which is mounted in the vehicle and performs vehicle-mounted multiplex transmission. Fig. 1, a line crossed by two diagonal lines represents an electrical system line, such as a signal line or a power line.

[0027] A hydraulic pressure sensor 29 as a detection means detects the hydraulic pressure in, for example, the cylinder-side hydraulic line 15A, and detects the brake fluid pressure supplied from the master cylinder 8 through the cylinder-side hydraulic line 15A to the ESC 30, which will be described later. The hydraulic pressure sensor 29 is electrically connected to a second control circuit 32, which will be described later. Meanwhile, a detection signal of the hydraulic pressure sensor 29 is also transmitted to the first control circuit 26 from the second control circuit 32 via the signal line 27.

[0028] An output side of the first control circuit 26 is connected to the electric motor 21, the signal line 27, and the vehicle data bus 28 mounted in the vehicle. The first control circuit 26 variably controls the brake fluid pressure by the booster 16 in conjunction with the detection signals from the operating amount detection sensor 7 and the hydraulic pressure sensor 29 to be generated in the master cylinder 8, and also determines whether the booster 16, which constitutes part of the first brake mechanism, is functioning normally.

[0029] At this time, when the brake pedal 5 is operated, the input piston 19 moves forward toward the cylinder main body 9 of the master cylinder 8. The movement of the input piston 19 is detected by the operating amount detection sensor 7. In response to the detection signal from the operating amount detection sensor 7, the first control circuit 26 outputs a start command to the electric motor 21 to rotate the electric motor 21. The rotation of the electric motor 21 is transmitted to the cylindrical rotating body 22 through the interposed speed reduction gear mechanism 23. Subsequently, the rotation of the cylindrical rotating body 22 is converted into axial displacement of the booster piston 18 by the linear motion mechanism 24 in the booster 16.

[0030] At this time, the booster piston 18 moves forward integrally with the input piston 19 toward the cylinder main body 9 of the master cylinder 8. As a result, the brake fluid pressure is generated in the first hydraulic chamber 11A and the second hydraulic chamber 11B of the master cylinder 8 depending on the pedal force (thrust) applied from the brake pedal 5 to the input piston 19 and the booster thrust applied from the electric actuator 20 to the booster piston 18. By receiving the detection signal from the hydraulic pressure sensor 29 via the signal line 27, the first control circuit 26 can monitor the hydraulic pressure generated in the master cylinder 8 and therefore determine whether the booster 16 is functioning normally.

[0031] The hydraulic pressure supply device (also called ESC 30) as a second brake mechanism provided between the wheel cylinders 3R, 3L, 4R and 4L provided on the respective wheels of the vehicle (front wheels 1R and 1L and rear wheels 2R and 2L) and the master cylinder 8 will now be described.

[0032] The ESC 30 as a second brake mechanism configures a wheel cylinder pressure control device for variably controlling the hydraulic pressure as the master cylinder pressure generated in the master cylinder 8 (first hydraulic chamber 11A and second hydraulic chamber 11B) by the booster 16 as the wheel cylinder pressure for each wheel, and then individually supplies the wheel cylinder pressure to each wheel cylinder 3R, 3L, 4R, and 4L for the corresponding wheels.

[0033] Specifically, the ESC 30 constitutes a brake assist device. When the brake fluid pressure to be supplied to the wheel cylinders 3R, 3L, 4R, and 4L through the cylinder-side hydraulic lines 15A and 15B from the master cylinder 8 is insufficient, or various types of brake controls (for example, brake force distribution control for distributing braking force to the front wheels 1R and 1L and the rear wheels 2R and 2L, anti-lock brake control, vehicle stability control, and the like) are executed, the ESC 30 supplies a required and sufficient brake fluid pressure, achieved by equalization, to the wheel cylinders 3R, 3L, 4R, and 4L.

[0034] The ESC 30 distributes and supplies the hydraulic pressure output from the master cylinder 8 (first hydraulic chamber 11A and second hydraulic chamber 11B) through the cylinder-side hydraulic lines 15A and 15B between the wheel cylinders 3R, 3L, 4R, and 4L through the brake-side line portions 31A, 31B, 31C, and 31D. In this manner, the independent braking force is applied to each wheel (front wheels 1R and 1L and rear wheels 2R and 2L) as described above. The ESC 30 includes control valves 37, 37', 38, 38', 39, 39', 42, 42', 43, 43', 50, and 50', and an electric motor 45 for driving the hydraulic pumps 44 and 44'.

[0035] The second control circuit 32 is a hydraulic pressure supply control circuit (ESC control circuit) as a second control circuit for electrically controlling the drive of the ESC 30 (second braking mechanism). An input side of the second control circuit 32 is connected to the hydraulic pressure sensor 29, the signal line 27, and the vehicle data bus 28. An output side of the second control circuit 32 is connected to the control valves 37, 37', 38, 38', 39, 39', 42, 42', 43, 43', 50, and 50', the electric motor 45, the signal line 27, and the vehicle data bus 28.

[0036] The second control circuit 32 individually controls the drive of the control valves 37, 37', 38, 38', 39, 39', 42, 42', 43, 43', 50, and 50', and the electric motor 45 of the ESC 30, as described later. In this manner, the second control circuit 32 performs control for reducing, maintaining, boosting, or applying the brake fluid pressure to be supplied from the brake-side conduit portions 31A to 31D to the wheel cylinders 3R, 3L, 4R, and 4L, individually for the wheel cylinders 3R, 3L, 4R, and 4L.

[0037] Specifically, by controlling the drive of the ESC 30, the second control circuit 32 can execute, for example, brake force distribution control, anti-lock brake control, vehicle stability control, hill start assist control, traction control, vehicle follow-up control, lane departure avoidance control, and object avoidance control. The brake force distribution control appropriately distributes the braking force between the corresponding wheels depending on a vertical load when the vehicle is braked. The anti-lock brake control prevents wheel locking by automatically adjusting the braking force for each of the wheels at the time of braking.The vehicle stability control is used to detect wheel skidding during running to suppress understeer and oversteer by appropriately automatically controlling the braking force to be applied to each of the wheels regardless of the operation amount of the brake pedal 5, thereby achieving a stabilizing behavior of the vehicle. The hill start assist control assists starting while maintaining a braking state on a hill (particularly uphill). The traction control prevents wheel spin at the time of starting the vehicle. The vehicle follow-up control allows a constant distance from a preceding vehicle. The lane departure avoidance control allows the vehicle to run within the lane. The object avoidance control avoids collision with an object in front of or behind the vehicle.

[0038] The ESC 30, which constitutes the second braking mechanism (wheel cylinder pressure control device), includes two hydraulic system circuits, that is, a first hydraulic system 33 and a second hydraulic system 33'. The first hydraulic system 33 is connected to one of the output ports (that is, the cylinder-side hydraulic line 15A) of the master cylinder 8 to supply hydraulic pressure to the wheel cylinder 3L for the left front wheel (FL) and the wheel cylinder 4R for the right front wheel (RR). The second hydraulic system 33' is connected to the other output port (that is, the cylinder-side hydraulic line 15B) to supply hydraulic pressure to the wheel cylinder 3R for the right front wheel (FR) and the wheel cylinder 4L for the left front wheel (RL). The first hydraulic system 33 and the second hydraulic system 33' have the same configuration. Accordingly, the first hydraulic system 33 will be described below.For the second hydraulic system 33', the reference numerals of the corresponding components are suffixed with "'", and the description of these is avoided hereafter.

[0039] The first hydraulic system 33 of the ESC 30 includes a brake line 34 connected to a distal end of the cylinder-side hydraulic line 15A. The brake line 34 is divided into a first line portion 35 and a second line portion 36, which are connected to the wheel cylinders 3L and 4R, respectively. The brake line 34 and the brake line portion 35 form a line for supplying the hydraulic pressure to the wheel cylinder 3L with the brake-side line portion 31A, while the brake line 34 and the second line portion 36 form a line for supplying the hydraulic pressure to the wheel cylinder 4R with the brake-side line portion 31D.

[0040] The brake fluid pressure supply control valve 37 (hereinafter referred to simply as "supply control valve 37") is provided on the brake pipe 34. The supply control valve 37 is a normally-opening electromagnetic selector valve for opening and closing the brake pipe 34. A boost control valve 38 is provided on the first pipe section 35. The boost control valve 38 is a normally-opening electromagnetic selector valve for opening and closing the first pipe section 35. A boost control valve 39 is provided on a second pipe section 36. The boost control valve 39 is a normally-opening electromagnetic valve for opening and closing the second pipe section 36.

[0041] On the other hand, the first hydraulic system 33 of the ESC 30 includes a first pressure reduction line 40 for connecting the wheel cylinder 3L side to a reservoir 49 for hydraulic pressure control, and a second pressure reduction line 41 for connecting the wheel cylinder 4L side to reservoir 49. A first pressure reduction control valve 42 is provided on the first pressure reduction line 40, while a second pressure reduction control valve 43 is provided on the second pressure reduction line 41. The first pressure reduction control valve 42 is a normally-closed electromagnetic selection valve for opening and closing the first pressure reduction line 40. Similarly, the second pressure reduction control valve 43 is a normally-closed electromagnetic selection valve for opening and closing the second pressure reduction line 41.

[0042] The ESC 30 includes the hydraulic pump 44 as a hydraulic pressure generating device, which is a hydraulic pressure source. The hydraulic pump 44 is rotationally driven by the electric motor 45. The electric motor 45 is driven by power supplied from the second control circuit 32. When the power supply is stopped, the rotation of the electric motor 45 stops with the stopping of the rotation of the hydraulic pump 44. An output side of the hydraulic pump 44 is connected to a portion of the brake pipe 34 via a check valve 46 disposed on the downstream side of the supply control valve 37 (i.e., at a position where the first pipe portion 35 and the second pipe portion 36 branch). An inlet side of the hydraulic pump 44 is connected to the reservoir 49 for hydraulic pressure control through check valves 47 and 48.

[0043] The hydraulic pressure control reservoir 49 is provided to temporarily retain excess brake fluid. The hydraulic pressure control reservoir 49 temporarily retains excess brake fluid that leaks from the cylinder chambers (not shown) of the wheel cylinders 3L and 3R not only during ABS control of the brake system, but also during other brake controls. The inlet side of the hydraulic pump 44 is connected to the cylinder-side hydraulic line 15A of the master cylinder 8 (that is, a portion of the brake line 34 located on the upstream side of the supply control valve 37) through the check valve 47 and a pressurization control valve 50, which is a normally-closed electromagnetic selector valve.

[0044] For each of the control valves 37, 37', 38, 38', 39, 39', 42, 42', 43, 43', 50 and 50', and the electric motor 45 for driving the hydraulic pumps 44 and 44', which configure the ESC 30, the operation control is carried out in a predetermined procedure in response to a control signal output from the second control circuit 32.

[0045] Specifically, the first hydraulic system 33 of the ESC 30 supplies the hydraulic pressure generated in the master cylinder 8 via the booster 16 through the brake pipe 34 directly to the wheel cylinders 3L and 4R, the first pipe section 35, and the second pipe section 36 at the time of normal operation based on the braking operation performed by the driver. For example, when anti-lock control is to be executed, the boost control valves 38 and 39 are closed to maintain the hydraulic pressure in the wheel cylinders 3L and 4R. When the hydraulic pressure in the wheel cylinders 3L and 4R is to be reduced, the pressure reduction control valves 42 and 43 are opened so that the hydraulic pressure in the wheel cylinders 3L and 4R can be released by draining to the reservoir 49 for hydraulic pressure control.

[0046] When the hydraulic pressure to be supplied to the wheel cylinders 3L and 4R is to be boosted for stabilization control (electronic stabilization control) during vehicle travel, the hydraulic pump 44 is driven by the electric motor 45 in a state where the supply control valve 37 is closed. In this way, brake fluid discharged from the hydraulic pump 44 is supplied to the wheel cylinders 3L and 4R through the first pipe portion 35 and the second pipe portion 36, respectively. At this time, the pressurization control valve 50 is opened. As a result, the brake fluid stored in the reservoir 14 is supplied to the inlet side of the hydraulic pump 44 from the master cylinder 8 side.

[0047] As described above, the second control circuit 32 controls the drive of the supply control valve 37, the boost control valves 38 and 39, the pressure reduction control valves 42 and 43, the pressurization control valve 50, and the electric motor 45 (i.e., the hydraulic pump 44) based on vehicle operation information so as to appropriately maintain, reduce, or boost the hydraulic pressure to be supplied to the wheel cylinders 3L and 4R. As a result, the aforementioned brake control, such as the brake force distribution control, the vehicle stabilization control, the brake assist control, the anti-lock control, the traction control, and the hill start assist control, are executed.

[0048] On the other hand, in a normal braking mode, which is performed in a state where the electric motor 45 (i.e., the hydraulic pump 44) is stopped, the supply control valve 37 and the boost control valves 38 and 39 are opened, while the pressure reduction control valves 42 and 43 and the pressurization control valve 50 are closed. In this state, when the first piston (i.e., the booster piston 18 and the input piston 19) and the second piston 10 of the master cylinder 8 are displaced in the axial direction within the cylinder main body 9 in association with the pedal operation of the brake pedal 5, the brake fluid pressure generated in the first hydraulic chamber 11A is supplied from the cylinder-side hydraulic line 15A through the first hydraulic system 33 and the brake-side line portions 31A and 31D of the ESC 30 to the wheel cylinders 3L and 4R.The brake fluid pressure generated in the second hydraulic chamber 11B is supplied from the cylinder-side hydraulic line side 15B through the second hydraulic system 33' and the brake-side line sections 31B and 31C to the wheel cylinders 3R and 4L.

[0049] In a brake assist mode, which is executed when the brake fluid pressure in the first hydraulic chamber 11A and the second hydraulic chamber 11B (i.e., the hydraulic pressure in the cylinder-side hydraulic line 15A detected by the hydraulic pressure sensor 29) is insufficient, the pressurization control valve 50 and the boost control valves 38 and 39 are opened, while the supply control valve 37 and the pressure reduction control valves 42 and 43 are appropriately opened and closed. In this state, the hydraulic pump 44 is driven by the electric motor 45 so that the brake fluid discharged from the hydraulic pump 44 is supplied to the wheel cylinders 3L and 4R through the first line portion 35 and the second line portion 36, respectively.In this way, together with the brake fluid pressure generated on the master cylinder side 8, the braking force of the wheel cylinders 3L and 4R can be generated by the brake fluid discharged from the hydraulic pump 44.

[0050] A known hydraulic pump, such as a piston pump, a trochoid pump, and a gear pump, can be used as the hydraulic pump 44. Considering adaptability to vehicle installations, low noise, and pumping efficiency, using a gear pump is preferred. A known motor, such as a DC motor, a brushless DC motor, and an AC motor, can be used as the electric motor 45. In this embodiment, the DC motor is used in view of adaptability to vehicle installations.

[0051] Characteristics of the control valves 37, 38, 39, 42, 43, and 50 of the ESC 30 can be appropriately adjusted in conjunction with a usage mode of each of the control valves. Among the above-mentioned control valves, the supply control valve 37 and the boost control valves 38 and 39 are configured as normally-opening valves, while the pressure-reducing control valves 42 and 43 and the pressurizing control valve 50 are configured as normally-closing valves. As a result, the hydraulic pressure from the master cylinder 8 can be supplied to the wheel cylinders 3R, 3L, 4R, and 4L even when no control signal is transmitted from the second control circuit 32. Accordingly, in consideration of reliability and control efficiency of the braking device, it is desirable to adopt the above-mentioned configuration.

[0052] A regenerative cooperative controller 51 for energy charging is connected to the vehicle data bus 28 mounted in the vehicle. The regenerative cooperative controller 51 uses an inertial force generated by the rotation of each of the wheels at the time of deceleration and braking of the vehicle to control the drive of an electric generator (not shown). In this way, the regenerative cooperative controller 51 accumulates kinetic energy as electrical energy. The regenerative cooperative controller 51 is connected to a first control circuit 26 and a second control circuit 32 through the vehicle data bus 28.

[0053] Subsequently, with reference to Fig. 2 describes a wiring connection relationship between the first control circuit 26, the second control circuit 32, and the hydraulic pressure sensor 29. The hydraulic pressure sensor 29 is fixedly provided on the booster 16 side, more specifically, on the master cylinder 8, and is supplied with power from the second control circuit 32 through a power supply line 52. As the detection signal of the hydraulic pressure sensor 29, a measured value of the master cylinder pressure is output as an analog value to the second control circuit 32 via the signal wires 53. Then, the second control circuit 32 digitally converts the detection signal from the hydraulic pressure sensor 29 into constant control sweeps. On the other hand, the first control circuit 26 receives the detection signal, which has been digitally converted by the second control circuit 32, as a communication signal via the signal wires 27, which are a transmission line.In this way, the first control circuit 26 can detect (monitor) the hydraulic pressure as the master cylinder pressure generated in the hydraulic chamber 11A of the master cylinder 8 and the cylinder-side hydraulic line 15A.

[0054] Fig. 3 is a characteristic diagram showing determinations as to whether there is an abnormality in the hydraulic pressure sensor 29. The determinations are made when the brake pedal 5 is not operated and the booster 16 is not driven to generate the hydraulic pressure, that is, in a state in which the cylinder hydraulic pressure is not generated. A characteristic line 54 shown in Fig. 3 represents the detection signal output from the hydraulic pressure sensor 29 as a hydraulic pressure value P. When the hydraulic pressure value P is equal to or less than a predetermined abnormality threshold α, it is determined that the detection value of the hydraulic pressure sensor 29 is normal. When the hydraulic pressure value P exceeds the abnormality threshold α, it is determined that an abnormality has occurred. The characteristic line 54 shows that the hydraulic pressure value P of the hydraulic pressure sensor 29 is normal in the time range from 0 to time t1 and the time range from t3 to t5, and the hydraulic pressure value P of the hydraulic pressure sensor 29 is abnormal in the time range from t1 to t3 and the time range after t5. The abnormality threshold α is set to determine whether the detection signal is output even though the master cylinder pressure is not generated.The abnormality threshold α is set to approximately half of a maximum output value of the hydraulic pressure sensor 29, taking into account individual variabilities or a temperature drift of the hydraulic pressure sensor 29.

[0055] The second control circuit 32 determines whether there is an abnormality in the hydraulic pressure sensor 29 in a predetermined first cycle T1 based on the detection value of the hydraulic pressure sensor 29. Subsequently, when the hydraulic pressure value P exceeds the abnormality threshold value α continuously over the first cycle T1, as shown by the characteristic line 55 in Fig. 3, the occurrence of the sensor abnormality is detected at a time t7 via the second control circuit 32, and a signal indicating the determination of the occurrence of the abnormality is output to the first control circuit 26 via the signal line 27. The first cycle T1 is set as a time period for determining whether the hydraulic pressure sensor P is outputting steadily and is set to, for example, 500 ms. The first cycle T1 is set to a time period that is significantly longer than control cycles of the control circuits 26 and 32 and a transmission cycle between the control circuit 26 and the control circuit 32.

[0056] On the other hand, the control circuit 26 receives the detection value of the hydraulic pressure sensor 29 through the transmission of the signal line 27 from the second control circuit 32, so as to determine, in a second pass T2, which is shorter than the first pass T1, based on the detection signal received through the transmission, whether there is an abnormality in the hydraulic pressure sensor 29. Then, the first control circuit 26 previously determines at a time t2 that there is an abnormality in the hydraulic pressure sensor 29 when the hydraulic pressure value P exceeding the abnormality threshold α is continuously outputted over the second pass T2, as shown by a characteristic line 56 in Fig. 3. At this time, complementary processing, which will be described later, is executed based on the preliminary determination of the abnormality. The result of the preliminary determination may also be transmitted from the first control circuit 26 to the second control circuit 32 via the signal line 27.

[0057] In the complementary processing, the first control circuit 26 controls the drive of the electric actuator 20 based on the detection signal (brake command) from the operating amount detection sensor 7, without using the detection value from the hydraulic pressure sensor 29 determined to be abnormal. Similar to the first cycle T1, each of the second cycles T2 is set to a time period significantly longer than the control cycles of the control circuits 26 and 32 and the transmission cycle between the control circuits 26 and 32. The reason why the second cycle T2 is set shorter than the first cycle T1 is as follows. The first cycle T1 is set as a time period for determining whether the hydraulic pressure value P is output unchanged, as described above.However, if even a slight abnormality exists in the hydraulic pressure value P used to control the first control circuit 26, the drive of the electric actuator 20 cannot be controlled with high accuracy. Accordingly, the second cycle time T2 is set shorter so that the abnormality in the hydraulic pressure sensor 29 can be detected as quickly as possible.

[0058] As described above, in this embodiment, the first pass T1 in the second control circuit 32 is set as a predetermined criterion for determining the occurrence of the abnormality in the hydraulic pressure sensor 29, while the second pass T2, which is shorter than the first pass T1, in the first control circuit 26 is set as another criterion for determining the occurrence of the abnormality in the hydraulic pressure sensor 29. In other words, the first control circuit 26 determines whether an abnormality exists in the hydraulic pressure sensor 29 at a time earlier than the determination time performed by the second control circuit 32.

[0059] Subsequently, the preliminary determination of the occurrence of the abnormality in the hydraulic pressure sensor 29 by the first control circuit 26 is stopped at a time t4 when a period in which the hydraulic pressure P is equal to or less than the abnormality threshold α exceeds the second pass T2 when the hydraulic pressure value P indicated by the characteristic line 54 is reduced to the abnormality threshold α or less at time t3. Subsequently, the control circuit 26 preliminarily determines that the detection value of the hydraulic pressure sensor 29 is normal. Accordingly, at or after time t4 (until time t6, which will be described later), the complementary processing is stopped.The first control circuit 26 controls the drive of the electric actuator 20 based on the detection signal of the operating quantity detection sensor 7 and the detection signal of the hydraulic pressure sensor 29.

[0060] Subsequently, the characteristic line 54 exceeds the abnormality threshold α again at time t5. Then, at time t6, when a period in which the hydraulic pressure value P indicated by the characteristic line 54 is greater than the abnormality threshold α exceeds the second pass T2, the first control circuit 26 performs the preliminary determination of the occurrence of the abnormality. As indicated by the characteristic line 56, the first control circuit 26 starts the complementary processing based on the preliminary determination of the occurrence of the abnormality at time t6, as described above.After a differential interval T3 has elapsed between the first pass T1 and the second pass T2, which corresponds to a period from time t6 to time t7, the second control circuit 32 determines the occurrence of the sensor abnormality at time t7 as described above, and then stores an error code in the control circuit or an external memory and notifies the sensor abnormality using an alarm lamp (not shown). Furthermore, the second control circuit 32 outputs a signal indicating the determination of the occurrence of the abnormality to the first control circuit 26 via the signal line 27. Now, as shown by a characteristic line 57 in FIG. Fig. 3, the first control circuit 26 detects the occurrence of an abnormality in the hydraulic pressure sensor 29 at a time t8 at which a predetermined time period T4 required for transmitting and analyzing the transmission signal after determining the occurrence of an abnormality elapses. The first control circuit 26 also stores an error code of the sensor in the control circuit or an external memory, and at the same time outputs a notification of the sensor abnormality using an alarm lamp or another alarm lamp (not shown).

[0061] The brake control device according to the first embodiment has the configuration described above. The drive of the brake control device will now be described.

[0062] At this time, the input piston 19 is first pushed in the direction indicated by arrow A when the vehicle driver performs pedal operation of the brake pedal 5. At the same time, the drive of the electric actuator 20 for the booster 16 is controlled by the first control circuit 26. More specifically, the first control circuit 26 issues a start command to the electric motor 21 in response to the detection signal output from the operation amount detection sensor 7 to rotatably drive the electric motor 21. The rotation of the electric motor 21 is transmitted to the cylindrical rotating body 22 through a speed reduction gear mechanism 23 interposed therebetween. Subsequently, the rotation of the cylindrical rotating body 22 is converted into the axial displacement of the booster piston 18 by the linear motion mechanism 24.

[0063] As a result, the booster piston 18 for the booster 16 moves forward integrally with the input piston 19 toward the interior of the cylinder main body 9 of the master cylinder 8. Brake fluid pressure is generated in the first hydraulic chamber 11A and the second hydraulic chamber 11B of the master cylinder 8 depending on the pedal force (thrust) applied from the brake pedal 5 to the input piston 19 and the booster thrust applied from the electric actuator 20 to the booster piston 18.

[0064] The first control circuit 26 receives the detection value from the hydraulic pressure sensor 29 as the transmission signal via the signal line 27 to monitor the hydraulic pressure generated in the master cylinder 8. In this way, the first control circuit 26 performs feedback control of the electric actuator 20 of the booster 16 (rotation of the electric motor 21). In this way, the brake fluid pressure generated in the first hydraulic chamber 11A and the second hydraulic chamber 11B of the master cylinder 8 can be variably controlled depending on the braking operation amount of the brake pedal 5. The first control circuit 26 can determine whether the booster 16 (electric booster device) is operating normally in accordance with the detection value of the operation amount detection sensor 7 and the detection value of the hydraulic pressure sensor 29.

[0065] On the other hand, the input piston 19, which is coupled to the brake pedal 5, is subjected to the pressure generated in the first hydraulic chamber 11A and transmits the pressure as a braking reaction force to the brake pedal 5. As a result, a secure pedal feel can be provided to the driver of the vehicle via the input piston 19. Accordingly, the operating feel of the brake pedal 5 can be improved to maintain a good pedal feel.

[0066] Then, the ESC 30, which is provided on the second brake mechanism between the wheel cylinders 3R, 3L, 4R, and 4L for the respective wheels (front wheels 1R and 1L and rear wheels 2R and 2L) and the master cylinder 8, distributes the hydraulic pressure generated by the booster 16 as the master cylinder pressure in the master cylinder 8 (first hydraulic chamber 11A and second hydraulic chamber 11B) from the cylinder-side hydraulic lines 15A and 15B through the hydraulic systems 33 and 33' and the brake-side line portions 31A, 31B, 31C, 31D included in the ESC 30, to the wheel cylinders 3R, 3L, 4R, and 4L as the wheel cylinder pressures for the respective wheels while variably controlling the hydraulic pressure, and supplies the hydraulic pressure thereto. As a result, an appropriate braking force can be applied to each of the wheels (front wheels 1R and 1L and rear wheels 2R and 2L) of the vehicle through each of the wheel cylinders 3R, 3L, 4R, and 4L.

[0067] The second control circuit 32 for controlling the ESC 30 can receive the detection signal from the operation amount detection sensor 7 via the signal line 27. In this case, the pedal operation amount of the brake pedal 5 can be monitored. Subsequently, when the brake is operated, the second control circuit 32 receives the detection signal from the operation amount detection sensor 7 through the transmission. As a result, the control signal from the second control circuit 32 can be output to the electric motor 45 to drive the hydraulic pumps 44 and 44'. At the same time, the hydraulic pressures of the wheel cylinders 3R, 3L, 4R, and 4L can be controlled by selectively opening and closing the control valves 37, 37', 38, 38', 39, 39', 42, 42', 43, 43', 50, and 50'.

[0068] Accordingly, when the vehicle is braked, the brake fluid pressure to be supplied from the master cylinder 8 (and / or the hydraulic pumps 44 and 44') to the wheel cylinders 3R, 3L, 4R, and 4L in accordance with the pedal operation of the brake pedal 5 can be individually boosted, maintained, or reduced. As a result, the brake fluid pressure corresponding to the pedal operation of the brake pedal 5 and the operating state of the vehicle can be supplied to the wheel cylinders 3R, 3L, 4R, and 4L. At the same time, the braking force of the vehicle can be controlled with high accuracy.

[0069] As described above, in this first embodiment, the hydraulic pressure sensor 29 for detecting the hydraulic pressure generated in the hydraulic chamber 11A of the master cylinder 8 (cylinder-side hydraulic lines 15A) is fixedly provided on the side of the booster 16. The hydraulic pressure sensor 29 is configured so that power can be supplied from the second control circuit 32 through the power supply line 52, and the detection signal from the hydraulic pressure sensor 29 is output to the second control circuit 32 via the signal line 53. Subsequently, the second control circuit 32 determines whether an abnormality exists in the hydraulic pressure sensor 29 in the predetermined first cycle T1 based on the detection value of the hydraulic pressure sensor 29. For example, if the occurrence of the sensor abnormality is detected at time t7, as shown by the characteristic line 55 in Fig. 3, the signal indicating the determination of the occurrence of the abnormality is output to the first control circuit 26 via the signal line 27.

[0070] On the other hand, the first control circuit 26 receives the detection value of the hydraulic pressure sensor 29 from the second control circuit 32 via the signal line 27 by transmission, and then determines whether there is an abnormality in the hydraulic pressure sensor 29 in the second cycle T2 based on the detection signal received by transmission. Now, during the time period in which it is determined whether the detection value of the hydraulic pressure sensor 29 is normal, the first control circuit 26 can control the drive of the electric actuator 20 based on the detection signal of the operating amount detection sensor 7 and the detection signal of the hydraulic pressure sensor 29.

[0071] If it is determined that the hydraulic pressure sensor 29 is abnormal as indicated by the times t2 and t6 of the characteristic line 56 in Fig. 3, the first control circuit 26 performs complementary processing based on the prior determination of the occurrence of the abnormality. As a result, the first control circuit 26 can drive the electric actuator 20 based on the detection signal (brake command) from the operating amount detection sensor 7 without using the detection value of the hydraulic pressure sensor 29 determined to be abnormal. Now, for example, when the second control circuit 32 detects the occurrence of the sensor abnormality at time t7, because the duration of the abnormal state of the hydraulic pressure sensor 29 exceeds the first cycle T1, the first control circuit 26 determines the occurrence of the abnormality in the hydraulic pressure sensor 29 at time t8, for example.

[0072] Accordingly, in the first embodiment, the first control circuit 26 and the second control circuit 32 can individually determine whether there is an abnormality in the hydraulic pressure sensor 29. As a result, the reliability of the control performed by each of the control circuits (i.e., the first control circuit 26 and the second control circuit 32) can be ensured.

[0073] In the first embodiment, the first pass T1 is set as the predetermined criterion for determining whether there is an abnormality in the hydraulic pressure sensor 29 used in the second control circuit 32. As the further criterion for determining whether there is an abnormality in the hydraulic pressure sensor 29 used in the first control circuit 26, the second pass T2 is set shorter than the first pass T1.However, as long as the first control circuit 26 is set to determine whether an abnormality exists in the hydraulic pressure sensor 29 at the time earlier than the determination of the occurrence of the abnormality by the second control circuit 32, an abnormality of the hydraulic pressure sensor value P may be determined based on an abnormality threshold α1 smaller than the abnormality threshold α as another criterion for determining whether an abnormality exists in the hydraulic pressure sensor 29 used in the first control circuit 26. In this case, if the first control circuit 26 is configured to determine the occurrence of the abnormality in the hydraulic pressure sensor 29 earlier than the second control circuit 32, the second pass T2 may be set to the same value as or different from the value of the first pass T1.

[0074] Fig. 4 shows a second embodiment of the present invention. The second embodiment has a feature such that it is determined by the second control circuit whether the sensor signal value is abnormal, and the first control circuit executes control based on a signal received from the second control circuit through transmission. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[0075] Fig. Fig. 4 shows an abnormality determination process for the hydraulic pressure sensor 29, which is performed by the first and second control circuits (i.e., the first control circuit 26 and the second control circuit 32) used in the second embodiment. A characteristic line 61 shown in Fig. 4 represents the detection signal output from the hydraulic pressure sensor 29 as the hydraulic pressure value P. When the hydraulic pressure value P is equal to or less than the abnormality threshold α, the detection value of the hydraulic pressure sensor 29 is determined to be normal. When the hydraulic pressure value P exceeds the abnormality threshold α, it is determined to be abnormal. The characteristic line 61 shows that the detection value of the hydraulic pressure sensor 29 is normal in the range from time 0 to time t1 and the range from time t3 to time t5, and the detection value of the hydraulic pressure sensor 29 is abnormal in the range from time t1 to time t3 and at and after time t5.The second control circuit 32 determines whether there is an abnormality in the hydraulic pressure sensor 29 in the predetermined first cycle T1 based on the detection value of the hydraulic pressure sensor 29 as shown by a characteristic line 62 in FIG. Fig. 4. The second control circuit 32 determines in advance whether there is an abnormality in the hydraulic pressure sensor 29 in the second pass T2, which is shorter than the first pass, as shown by a characteristic line 63 in Fig.4. When the hydraulic pressure value P exceeds the abnormality threshold value α at time t1, and the preliminary determination performed by the second control circuit 32 determines the occurrence of the sensor abnormality at time t2 after the second loop T2 has elapsed from the occurrence of the abnormality, the second control circuit 32 transmits the result of the preliminary determination as an abnormality signal to the first control circuit 26 via the signal line 27. With the above-described preliminary determination as to whether there is an abnormality in the hydraulic pressure sensor 29, the second control circuit 32 preliminarily determines in the second loops T2 whether there is an abnormality in the circuits other than the hydraulic pressure sensor 29 (for example, an abnormality in the second control circuit 32).When the preliminary determination made by the second control circuit 32 is determined as the determination of the occurrence of the circuit abnormality, the second control circuit 32 transmits the result of the preliminary determination as an abnormality signal to the first control circuit 26 via the signal line 27.

[0076] The preliminary determination of whether an abnormality exists in the circuits other than the hydraulic pressure sensor 29 is performed for the following reasons. When an abnormality exists in one of the circuits other than the hydraulic pressure sensor 29, the hydraulic pressure value P of the transmission signal transmitted from the first control circuit 26 temporarily differs from an actual hydraulic pressure value even if an abnormality exists in the hydraulic pressure sensor 29. In such a case, the circuit abnormality is transmitted as the abnormality signal to the first control circuit 26, so as not to prevent the electric actuator 20 from being controlled with high accuracy.

[0077] When the result of the previous determination is received by the second control circuit 32, as indicated by the characteristic line 64, the first control circuit 26 performs the same complementary processing as described in the first embodiment. Through the complementary processing, the first control circuit 26 controls the drive of the electric actuator 20 based on the detection signal (brake command) from the operating amount detection sensor 7, without using the detection value of the hydraulic pressure sensor 29 determined to be abnormal.

[0078] Subsequently, the hydraulic pressure value P becomes equal to or lower than the abnormality threshold α at time t3. Now, when the period in which the hydraulic pressure value P is continuously equal to or lower than the abnormality threshold α exceeds the second pass T2 at time t4, the preliminary determination performed by the second control circuit 32 is not performed, as indicated by the characteristic line 63. By receiving the result indicating that the preliminary determination has not been performed, the first control circuit 26 again determines the detection value of the hydraulic pressure sensor 29 as normal, as indicated by the characteristic line 64. Accordingly, at and after time t4 (until time t6 described later), the complementary processing is stopped.The first control circuit 26 controls the drive of the electric actuator 20 based on the detection signal of the operating quantity detection sensor 7 and the detection signal of the hydraulic pressure sensor 29.

[0079] However, if the sensor abnormality occurs again at time t5 and the preliminary determination of the sensor abnormality is then performed at time t6, as in the previously described case, the first control circuit 26 receives the result of the preliminary determination from the second control circuit 32 and performs complementary processing. When a period of time during which an occurrence of an abnormality continues exceeds the first pass T1 at time t7, the second control circuit 32 determines the occurrence of the abnormality because the detection value of the hydraulic pressure sensor 29 is abnormal, as shown by the characteristic line 62. An error code of the sensor is stored in the second control circuit 32. At the same time, notification of the sensor abnormality is performed using an alarm lamp (not shown).

[0080] As described above, when the occurrence of the sensor abnormality is determined at time t7, the second control circuit 32 outputs a signal indicating the occurrence of the abnormality to the first control circuit 26 via the signal line 27. Then, at time t8, at which the predetermined period T4 for determining the occurrence of the abnormality elapses, the first control circuit 26 determines the occurrence of the abnormality in the hydraulic pressure sensor 29, as indicated by the characteristic line 65. An error code of the sensor is stored in the first control circuit 26. At the same time, notification of the sensor abnormality is performed using another alarm lamp (not shown).

[0081] As described above, even in the second embodiment configured as above, whether there is an abnormality in the hydraulic pressure sensor 29 can be determined by the first control circuit 26 and the second control circuit 32. As in the case of the first embodiment, the reliability of control can be ensured for each of the control circuits (i.e., control circuits 26 and 32).

[0082] In the second embodiment described above, the preliminary determination by the second control circuit 32 is configured to be performed based on the determination in the second runs T2 as to whether there is an abnormality in the hydraulic pressure sensor 29, each of which is shorter than the first runs T1, by using common abnormality threshold values α. However, similar to the preliminary determination by the first control circuit 26 described in the first embodiment, the preliminary determination by the second control circuit 32 may also be configured to be performed based on the determination as to whether the hydraulic pressure sensor value P is abnormal, by using the abnormality threshold value α1 that is smaller than the abnormality threshold value α.In this case, when the preliminary determination by the abnormality threshold α1 is configured to determine the occurrence of the abnormality in the hydraulic pressure sensor 29 before the determination by the abnormality threshold α, the second pass T2 may be set to the same value or a value different from the value of the first pass T1.

[0083] In each of the above-described embodiments, the case where the vehicle control device is applied to the brake control device mounted in the four-wheeled automobile described above as an example has been described. However, the present invention is not limited to the above-described case. For example, as in the case where the hydraulic pressure supply device and a motor control device share a detection value of a wheel speed sensor, the present invention can be applied to vehicle control devices other than the brake control device.

[0084] Further, in the above-described embodiments, the first control circuit 26 and the second control circuit 32 may be configured to mutually receive and transmit the result of the determination as to whether there is an abnormality in the hydraulic pressure sensor 29 by the transmission via the signal line 27, so that the processings after the determination as to whether there is an abnormality can be independently executed.

[0085] As previously described in the embodiments, in the vehicle control device of the above-described embodiment, the first control circuit and the second control circuit are configured to independently execute processing after determining whether an abnormality occurs. According to the vehicle control device of the above-described embodiments, there is such a feature that the first control circuit stops control based on the detection signal of the detection means when the occurrence of the abnormality in the detection means is detected by the first or second control circuit. Further, a warning of the occurrence of the abnormality is not issued when the occurrence of the abnormality in the detection means is determined by the first control circuit, while a warning of the occurrence of the abnormality is issued when the occurrence of the abnormality in the detection means is determined by the second control circuit.

[0086] On the other hand, in the brake control device of one embodiment, the first control circuit is configured to control the first brake mechanism based on the braking command to the first brake mechanism and the detection value of the hydraulic pressure sensor when it is detected that an abnormality exists in the hydraulic pressure sensor, and to control the first brake mechanism based on the braking command (without using the detection value of the hydraulic pressure sensor) when the occurrence of the abnormality is detected in the hydraulic pressure sensor. The brake control device of the present invention is also configured to determine, through the second control circuit, whether an abnormality exists in the hydraulic pressure sensor and to determine a failure of the hydraulic pressure sensor when the abnormality is detected.

[0087] Furthermore, the brake control device according to the present invention comprises the first control circuit for controlling the first brake mechanism to generate the braking force for the vehicle, the second control circuit for controlling the second brake mechanism to generate the braking force for the vehicle independently of the first control mechanism, the hydraulic pressure sensor electrically connected to the second control circuit for detecting the hydraulic pressure to calculate the braking force to be generated, and the signal line for electrically connecting the first control circuit and the second control circuit to transmit the detection value of the hydraulic pressure sensor.The second control circuit determines whether an abnormality exists in the hydraulic pressure sensor in the predetermined first pass based on the detection value of the hydraulic pressure sensor, determines whether an abnormality exists in the circuits other than the hydraulic pressure sensor in the second pass shorter than the predetermined first pass, and outputs the abnormality signal to the first control circuit via the signal line when the occurrence of the abnormality is determined. The first control circuit receives the detection value of the hydraulic pressure sensor through transmission from the second control circuit via the signal line, and determines whether an abnormality exists in the hydraulic pressure sensor in the second pass based on the detection signal received through transmission.The first control circuit controls the first brake mechanism based on the brake command to the first brake mechanism (without using the detection value of the hydraulic pressure sensor) when the occurrence of the abnormality in the hydraulic pressure sensor is detected, and determines the occurrence of a failure of the hydraulic pressure sensor or an erroneous behavior of the second control circuit when the abnormality signal is received from the second control circuit via the signal line.

[0088] The above-described embodiments include the following concept. Specifically, the control mechanism for a driven target (brake) includes the first control mechanism (master cylinder pressure control mechanism) and the second control mechanism (wheel cylinder pressure control mechanism) for controlling a drive source for driving the driven target, the physical quantity detector (hydraulic pressure sensor) for detecting a physical quantity of the drive source, the first control device (first control circuit) for inputting the signal from the physical quantity detector to control the first control mechanism, the second control device (second control circuit) for inputting the signal from the physical quantity detector to control the second control mechanism, the first diagnosis function (preliminary determination) provided at the first control device for examining the physical quantity detector,and the second diagnostic function (abnormality determination), provided on the second control device, for examining the physical quantity detector. The first diagnostic function and the second diagnostic function perform an examination based on different examination criteria (first pass T1, second pass T2, abnormality threshold α, and abnormality threshold α1).

[0089] According to one embodiment, the second control circuit may determine whether an abnormality exists in the detection means by comparing the detection value of the detection means with a predetermined threshold value. The first control circuit may determine whether an abnormality exists in the detection means by comparing the detection value of the detection means, which is received by transmission over the signal line, with another threshold value that is different from the predetermined threshold value of the second control circuit.

[0090] According to one embodiment, it is possible to provide the vehicle control device and the brake control device which enable determination of whether there is an abnormality in the detection means individually by two control circuits, thereby ensuring reliable control of each control circuit.

Claims

[1] Brake control device with: a first control circuit for controlling a first braking mechanism for generating a braking force for a vehicle; a second control circuit for controlling a second braking mechanism for generating, independently of the first braking mechanism, a braking force for the vehicle; a hydraulic pressure sensor (29) electrically connected to the second control circuit for detecting a hydraulic pressure for calculating a braking force to be generated; and a signal line (27) for electrically connecting the first control circuit and the second control circuit to enable the transmission of a detection signal based on a detection value of the hydraulic pressure sensor (29), wherein: the second control circuit is configured to determine whether there is an abnormality in the hydraulic pressure sensor (29) based on the detection value of the hydraulic pressure sensor (29); the first control circuit is arranged to receive the detection signal of the hydraulic pressure sensor (29) by transmission from the second control circuit via the signal line (27), and is arranged to determine, on the basis of the detection signal received by the transmission, whether an abnormality exists in the hydraulic pressure sensor (29) at a time before the time at which the second control circuit makes the determination, and the first control circuit is arranged not to issue a warning of the occurrence of the abnormality when the first control circuit detects the occurrence of the abnormality in the hydraulic pressure sensor (29), and the second control circuit is arranged to issue the warning of the occurrence of the abnormality when the second control circuit detects the occurrence of the abnormality in the hydraulic pressure sensor (29). [2] Brake control device according to claim 1, wherein the first control circuit and the second control circuit are arranged to perform independent processing after determining the occurrence of the abnormality; and the second control circuit is arranged to communicate with the first control circuit via the signal line (27) and to transmit a result of the determination as to whether there is an abnormality in the hydraulic pressure sensor (29) to the first control circuit via the signal line (27). [3] A brake control device according to claim 1 or 2, wherein the first control circuit is arranged to interrupt the control based on the detection signal of the hydraulic pressure sensor (29) when the occurrence of the abnormality in the hydraulic pressure sensor (29) is detected by the first control circuit or the second control circuit. [4] A brake control device according to claim 1, 2 or 3, wherein the first control circuit and the second control circuit are arranged to exchange a result of the determination as to whether there is an abnormality in the hydraulic pressure sensor (29) with each other via the signal line (27) to independently perform processing after determining the occurrence of the abnormality. [5] The brake control device according to claim 1, wherein the first control circuit is configured to control the first brake mechanism based on a brake command to the first brake mechanism and the detection value of the hydraulic pressure sensor (29) when no abnormality is detected in the hydraulic pressure sensor (29), and to control the first brake mechanism based on the brake command when the abnormality is detected in the hydraulic pressure sensor (29). [6] A brake control device according to claim 5, wherein the second control circuit itself is arranged to detect whether there is an abnormality in the hydraulic pressure sensor (29) and is arranged to determine a failure of the hydraulic pressure sensor (29) when the abnormality in the hydraulic pressure sensor (29) is detected. [7] Vehicle control device with: a first control circuit for controlling a first mechanism provided on a vehicle; a second control circuit for controlling a second mechanism provided on the vehicle; a detection means in the form of a hydraulic pressure sensor (29) electrically connected to the second control circuit for detecting a condition of the vehicle; and a signal line (27) for electrically connecting the first control circuit and the second control circuit to enable transmission of a detection signal of the detection means, wherein: the second control circuit is configured to determine whether there is an abnormality in the detection means by a predetermined criterion based on a detection value of the detection means; the first control circuit is configured to receive the detection value of the detection means by transmission from the second control circuit via the signal line (27), and to determine, by a further criterion which is different from the predetermined criterion of the second control circuit, on the basis of the detection signal received by the transmission, whether an abnormality exists in the detection means, and the first control circuit is configured not to output a warning of the occurrence of the abnormality if the first control circuit detects the occurrence of the abnormality in the hydraulic pressure sensor (29), and the second control circuit is configured to output the warning of the occurrence of the abnormality if the second control circuit detects the occurrence of the abnormality in the hydraulic pressure sensor (29). [8] Vehicle control device according to claim 7, wherein the first control circuit and the second control circuit are arranged to perform processing independently of each other after determining the occurrence of the abnormality; and the second control circuit is arranged to communicate with the first control circuit via the signal line (27), and to transmit a result of the determination as to whether there is an abnormality in the detection means to the first control circuit via the signal line (27). [9] A vehicle control device according to claim 7 or 8, wherein the first control circuit is arranged to interrupt the control based on the detection signal of the detection means when the occurrence of the abnormality in the detection means is detected by the first control circuit or the second control circuit.

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