Braking control device for hybrid vehicle

Abstract

To provide a brake control device of a vehicle, that can perform appropriate braking even when composite abnormality has occurred during braking control.SOLUTION: In braking control using an engine brake, a regeneration brake, and a friction brake in cooperation with each other, a BCU 14 sets deceleration at the time of abnormality detection of the regeneration brake, as target deceleration, when abnormality of the regeneration brake is detected, and performs brake force compensation using the friction brake according to feedback control with respect to the target deceleration.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a braking control device for a hybrid vehicle capable of generating braking force by regenerative braking using a motor generator. [Background technology]

[0002] Conventionally, in vehicles such as hybrid vehicles, braking control devices are known that obtain the desired braking force by combining a friction brake, which generates a braking force on the wheels by operating a friction engagement element using hydraulic pressure or the like, and a regenerative brake, which generates a braking force on the wheels by operating a motor generator as a generator.

[0003] Furthermore, in a braking control device (vehicle control device) for such a hybrid vehicle, a technology for stabilizing vehicle behavior even when an abnormality occurs in the regenerative brake is disclosed in, for example, Patent Document 1. Patent Document 1 discloses a technology that, when an abnormality in the regenerative brake is detected in a case where the difference between a target behavior of the vehicle calculated based on the amount of brake pedal operation or the amount of accelerator pedal operation and the deceleration detected by a G sensor exceeds a predetermined range, distributes torque generated by the entire vehicle to normal friction brakes other than the regenerative brake, the engine, and the transmission so as to compensate for the torque reduced due to the abnormal regenerative brake and achieve the target behavior until the motor generator is electrically disconnected from the vehicle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6064762 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology disclosed in the above-mentioned Patent Document 1 may not be able to perform appropriate braking if multiple abnormalities occur, such as when the regenerative brake is cut off and abnormalities occur in various sensors.

[0006] The present invention has been made in consideration of the above circumstances, and has an object to provide a braking control device for a hybrid vehicle that can perform appropriate braking even when multiple abnormalities occur during braking control. [Means for solving the problem]

[0007] A vehicle braking control device according to one aspect of the present invention is a braking control device for a hybrid vehicle equipped with an engine and a motor generator as a drive source for a power unit, and includes braking force control means for controlling braking force by coordinating an engine brake using the engine, a regenerative brake using the motor generator, and a friction brake using friction engagement elements, regenerative brake abnormality detection means for detecting an abnormality in the regenerative brake, power unit abnormality detection means for detecting an abnormality in a control system of the power unit, regenerative stop means for isolating the regenerative brake from the braking force control and stopping operation of the regenerative brake when an abnormality in the regenerative brake is detected, and braking force compensation means for performing braking force compensation using the friction brake from the time when an abnormality in the regenerative brake is detected until the regenerative brake is isolated from the braking force control. a brake system sensor abnormality detection means for detecting an abnormality in a brake system sensor; The braking force compensation means performs the braking force compensation by feedback control of the deceleration when an abnormality in the regenerative brake is detected. and the braking force compensation means performs the braking force compensation by a preset constant brake hydraulic pressure for the friction brake, instead of the braking force compensation by the feedback control, at least when an abnormality in the regenerative brake and an abnormality in a sensor of the braking system are detected. This is what happens. Effect of the Invention

[0008] According to the braking control device for a hybrid vehicle of the present invention, appropriate braking can be performed even when multiple abnormalities occur during braking control. [Brief description of the drawings]

[0009] [Figure 1]Schematic diagram of a hybrid vehicle [Diagram 2] Brake actuator configuration diagram [Diagram 3] Flowchart showing braking torque distribution control routine [Figure 4] Flowchart showing a regenerative brake disconnection control routine [Diagram 5] A flowchart showing a braking force compensation control routine when a regenerative brake malfunctions. [Figure 6] 11 is a flowchart showing a first braking force compensation control subroutine. [Figure 7] 2 is a flowchart showing a second braking force compensation control subroutine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A vehicle 1 shown in Fig. 1 is, for example, a hybrid vehicle, and a power unit PU of this vehicle 1 has an engine 2 and a motor generator 4 connected to the output shaft of the engine 2 via an automatic transmission 3.

[0011] In this embodiment, the vehicle 1 shown in Fig. 1 is a four-wheel drive vehicle, and the output shaft of the automatic transmission 3 is connected to the left and right front wheels 5fl, 5fr and the left and right rear wheels 5rl, 5rr. Each wheel 5fl, 5fr, 5rl, 5rr (hereinafter collectively referred to as "each wheel 5") is provided with a wheel cylinder 8fl, 8fr, 8rl, 8rr (hereinafter collectively referred to as "each wheel cylinder 8") equipped with a friction engagement element such as a disc brake. In Fig. 1, Dc denotes a center differential device, Df denotes a front differential device, and Dr denotes a rear differential device.

[0012] The control system that controls the running of the vehicle 1 includes a hybrid control unit (HEV_CU) 10, an engine control unit (ECU) 11, a transmission control unit (TCU) 12, a power control unit (PCU) 13 incorporating an inverter 13a, and a brake control unit (BCU) 14. These control units 10 to 14 are connected to each other so as to be able to communicate with each other via a CAN (Controller Area Network) or the like.

[0013] Various sensors are connected to the input side of the HEV_CU 10, such as an accelerator sensor 15 serving as an accelerator operation detection means for detecting the state of operation of the accelerator pedal 15a by the driver, and a brake sensor 16 serving as a brake operation detection means for detecting the state of braking operation of the brake pedal 16a by the driver.

[0014] The accelerator sensor 15 is capable of detecting, for example, the operation speed of the accelerator pedal 15a, and whether the accelerator pedal 15a is fully open or fully closed, etc. The brake sensor 16 is capable of detecting, for example, the operation speed of the brake pedal 16a, and whether the brake pedal 16a is fully open or fully closed, etc.

[0015] The HEV_CU 10 calculates the required torque for the engine 2 and the motor generator 4 based on signals from various sensors, for example, and performs overall drive control of the engine 2 and the motor generator 4.

[0016] Furthermore, the HEV_CU 10 performs switching control of the driving mode through control of various clutches (not shown) provided in the automatic transmission 3. In this embodiment, the HEV_CU 10 can switch the driving mode to any one of an EG mode in which the vehicle runs solely on the engine 2, an HEV mode in which the vehicle runs solely on the engine 2 and the motor generator 4, and an EV mode in which the vehicle runs solely on the motor generator 4.

[0017] Furthermore, the HEV_CU 10 is capable of performing braking force control, etc., by engine braking using the engine 2, regenerative braking by the motor generator 4, friction braking by operation of each wheel cylinder 8, or by a combination of these.

[0018] In this braking force control, the HEV_CU 10 acquires a target deceleration. That is, for example, during coasting, the HEV_CU 10 calculates a target deceleration based on a signal (accelerator opening degree, etc.) from the accelerator sensor 15. Also, for example, when the HEV_CU 10 detects the driver's depression of the brake pedal based on a signal from the brake sensor 16, the HEV_CU 10 calculates a target deceleration based on signals from first and second brake fluid pressure sensors 59a, 59b, etc., which will be described later. Furthermore, in the vehicle 1 equipped with a driving support device (not shown), the HEV_CU 10 acquires a target deceleration for automatic brake control, etc., calculated by the driving support device.

[0019] Then, the HEV_CU10 calculates the necessary braking torque from the acquired target deceleration, for example. Furthermore, the HEV_CU10 calculates each distribution value (engine braking torque, regenerative braking torque, and friction braking torque) for distributing the calculated necessary braking torque to the engine brake, the regenerative brake, and the friction brake according to the running state of the host vehicle 1, and outputs a control signal based on each calculated distribution value to each control unit 11 to 14.

[0020] The ECU 11 receives control information such as required torque from the HEV_CU 10, as well as detection information from various sensors (not shown) such as a crank angle sensor provided in the engine 2. Based on this input information, the ECU 11 drives the engine 2 by controlling the fuel injection amount, ignition timing, and various devices such as an electronically controlled throttle valve.

[0021] The TCU 12 receives control information from the HEV_CU 10, as well as detection information from various sensors (not shown), such as a shift position sensor provided on a shift lever and a vehicle speed sensor. Based on this input information, the TCU 12 performs hydraulic control applied to each element of the automatic transmission 3, such as a clutch, to control the gear ratio of the automatic transmission 3.

[0022] During braking, the TCU 12 cooperates with the ECU 11 to perform a predetermined gear shift control, thereby generating a braking force (engine braking torque) by engine braking.

[0023] The PCU 13 receives control information such as required torque from the HEV_CU 10, and also acquires from the inverter 13a the current value, voltage value, and various sensor signals flowing through the motor generator 4. The PCU 13 then drives the motor generator 4 by converting DC power from the battery 7 into AC power through control over the inverter 13a.

[0024] Furthermore, during deceleration, the PCU 13 controls the inverter 13a to cause the motor generator 4 to function as a generator, converting AC power regenerated by the motor generator 4 into DC power and charging the battery 7. When the motor generator 4 functions as a generator, a regenerative braking force is applied to each wheel 5 by the regenerative brake. Note that this regenerative braking force is applied to the driving wheels, but since the vehicle 1 of this embodiment is a four-wheel drive vehicle, a regenerative braking force (regenerative braking torque) is applied to all of the wheels 5.

[0025] The BCU 14 receives control information from the HEV_CU 10, as well as detection information from various sensors such as wheel speed sensors 17fl, 17fr, 17rl, and 17rr (hereinafter collectively referred to as "wheel speed sensors 17") that detect the wheel speeds of the wheels 5, and a longitudinal acceleration sensor 18. Based on this input information, the BCU 14 controls the drive of each wheel cylinder 8 through brake fluid pressure control for the brake actuator 6, thereby generating a frictional braking force (frictional braking torque) on each wheel 5.

[0026] Here, the brake actuator 6 is mainly constituted by a brake fluid pressure circuit 42 connected to a brake fluid pressure generating section 41, for example, as shown in FIG.

[0027] The brake fluid pressure generating unit 41 has a master cylinder 44, a reservoir tank 45 attached to the master cylinder 44, and a brake booster 46 interposed between the brake pedal 16a and the master cylinder 44. A pressure medium (oil) is stored in the reservoir tank 45. In addition, the brake pedal 16a is connected to the brake booster 46 via an operating rod 48.

[0028] A master cylinder 44 of the brake fluid pressure generating unit 41 is connected via a brake fluid pressure circuit 42 to wheel cylinders 8fl, 8fr, 8rl, and 8rr provided on the wheels 5fl, 5fr, 5rl, and 5rr of the vehicle.

[0029] The brake hydraulic circuit 42 is composed of two hydraulic lines, a first hydraulic circuit 52 and a second hydraulic circuit 53. The brake hydraulic circuit 42 according to this embodiment is of a cross piping (X piping) type in which the first hydraulic circuit 52 and the second hydraulic circuit 53 are arranged diagonally across the vehicle 1. That is, in the brake hydraulic circuit 42 according to this embodiment, the first hydraulic circuit 52 is connected to the wheel cylinders 8fl, 8rr of the left front wheel and the right rear wheel arranged in one diagonal direction of the vehicle 1, and the second hydraulic circuit 53 is connected to the wheel cylinders 8fr, 8rl of the right front wheel and the left rear wheel arranged in the other diagonal direction of the vehicle 1.

[0030] In addition, since the first hydraulic circuit 52 and the second hydraulic circuit 53 have the same configuration, the same reference numerals are appropriately used to simplify the explanation below. In addition, in explaining the configuration of the brake hydraulic circuits 52, 53 below, for convenience, the master cylinder 44 side will be described as the upstream side and the wheel cylinders 8fl, 8fr, 8rl, 8rr side will be described as the downstream side based on the flow from the master cylinder 44 to the wheel cylinders 8fl, 8fr, 8rl, 8rr side of the brake caliper.

[0031] The master cylinder 44 is provided with first and second supply / discharge ports 44a, 44b, and the upstream of a first fluid passage L1 constituting each of the hydraulic circuits 52, 53 is connected to each of the supply / discharge ports 44a, 44b. The downstream of the first fluid passage L1 is connected to the middle of a second fluid passage L2. The upstream side of the second fluid passage L2 is connected to a low-pressure accumulator 54 serving as a pressure accumulation means.

[0032] The downstream side of the second fluid path L2 is branched and connected to a third fluid path L3 and a fourth fluid path L4. Furthermore, the downstream side of each of the fluid paths L3 and L4 is connected to wheel cylinders 8fl and 8rr (8fr and 8rl) that operate brake calipers provided on the wheels 5fl and 5rr (5fr and 5rl) to generate braking force (friction braking force) on the wheels 5fl and 5rr (5fr and 5rl).

[0033] Meanwhile, the upstream of the fifth and sixth fluid paths L5 and L6 are connected to the middle of the third and fourth fluid paths L3 and L4. The downstream of these fifth and sixth fluid paths L5 and L6 is connected to a seventh fluid path, and the downstream of this seventh fluid path L7 is connected to the low-pressure accumulator 54.

[0034] A gate-in valve 55 is provided in the first hydraulic line L1, and a hydraulic pump 56 is provided in the second hydraulic line L2 downstream of the first hydraulic line L1. The hydraulic pumps 56 of the first and second hydraulic circuits 52, 53 are connected to a common electric motor 57.

[0035] The drive shaft of each hydraulic pump 56, 56 is connected to a motor 57 so that the hydraulic pressure pulsations generated by each hydraulic pump 56, 56 are in opposite phase to each other. The motor 57 is driven and controlled based on a control signal (brake hydraulic pressure command value) input from the BCU 14. In this case, the motor 57 is basically driven at high speed when braking from high speed driving requiring a large braking force (brake hydraulic pressure), and is driven at low speed when braking from low speed driving requiring not so large braking force (brake hydraulic pressure).

[0036] In addition, the first fluid line L1 on the upstream side of the gate-in valve 55 and the second fluid line L2 on the downstream side of the hydraulic pump 56 are bypass-connected via an eighth fluid line L8, and a bypass valve 58 is provided in the eighth fluid line L8. Furthermore, a first brake fluid detection sensor 59a (a second brake fluid detection sensor 59b) is provided downstream of the eighth fluid line L8 in the second fluid line L2. The brake fluid detection sensor 59a (59b) is, for example, a fluid pressure sensor that detects the hydraulic pressure of the brake fluid acting on the second fluid line L2. Furthermore, pressure-increasing valves 60 and 61 are provided in the third and fourth fluid lines L3 and L4, and pressure-reducing valves 62 and 63 are provided in the fifth and sixth fluid lines L5 and L6.

[0037] Each of these valves 55, 58, 60 to 63 is, for example, an electromagnetic solenoid valve, and is switched in response to a drive signal from the BCU 14. In this embodiment, for example, the bypass valve 58 and the pressurizing valves 60 and 61 are configured as normally open electromagnetic solenoid valves, and the gate-in valve 55 and the decompression valves 62 and 63 are configured as normally closed electromagnetic solenoid valves.

[0038] For the brake actuator 6, the BCU 14 performs various braking controls through control of the electric motor 57 and the valves 55, 58, 60 to 63, and the like.

[0039] That is, the BCU 14 basically stops the electric motor 57, closes the gate-in valve 55, and opens the bypass valve 58. As a result, the brake fluid pressure generated in the master cylinder 44 in accordance with the amount of depression of the brake pedal 16a by the driver is supplied directly to each wheel cylinder 8.

[0040] Also, for example, in the vehicle 1 equipped with a driving assistance device (not shown), when a target deceleration for automatic brake control or the like is set by the driving assistance device, the BCU 14 drives the electric motor 57. Furthermore, the BCU 14 opens the gate-in valve 55 and closes the bypass valve 58. As a result, the pressure medium pressurized in the master cylinder 44 or the pressure medium supplied directly from the reservoir tank 45 is pressurized to a predetermined brake hydraulic pressure via the hydraulic pump 56, and then supplied from the second hydraulic path L2 to the third and fourth hydraulic paths L3 and L4.

[0041] Furthermore, the BCU 14 drives and controls the pressurizing valves 60, 61 and the depressurizing valves 62, 63 as necessary, and performs distribution control and depressurization control of the brake fluid pressure supplied to each wheel cylinder 8. This realizes ABS (Anti-lock Brake System) control, anti-skid control, etc.

[0042] Furthermore, during braking force control in which the friction brake is coordinated with the regenerative brake, the engine brake, etc., the BCU 14 reduces the brake fluid pressure through drive control of the pressure reducing valves 62, 63 and the electric motor 57, etc. As a result, the friction brake force is controlled to a brake force according to the torque distribution value of the required braking torque calculated in the HEV_CU 10.

[0043] Incidentally, during braking force control in which each brake is coordinated as described above, if an abnormality occurs in the regenerative brake, the BCU 14 performs braking force compensation using the friction brake until the regenerative brake is separated from the braking force control by the PCU 13.

[0044] For example, when an abnormality is detected only in the regenerative brake, or when an abnormality is detected in the regenerative brake and an abnormality is detected in the control system of the power unit PU, the BCU 14 performs a first braking force compensation control. In this first braking force compensation control, the BCU 14 sets the deceleration at the time when the abnormality of the regenerative brake is detected (more specifically, immediately before the abnormality of the regenerative brake is detected) as a target deceleration, and performs feedback control using a friction brake for the set target deceleration, thereby performing braking force compensation.

[0045] An abnormality in the regenerative brake refers to, for example, a case where the regenerative brake is cut off (a case where braking force is no longer generated by the regenerative brake), etc. This abnormality in the regenerative brake is determined, for example, by the PCU 13. That is, the PCU 13 determines an abnormality in the regenerative brake when, for example, a predetermined regenerative power generation is not being performed in the motor generator 4 despite the execution of regenerative brake control.

[0046] An abnormality in the control system of the power unit PU refers to, for example, a case where a well-known abnormality diagnosis in the ECU 11, TCU 12, etc. detects an abnormality in the sensor system of the power unit PU or an abnormality in the actuator system.

[0047] Furthermore, when at least an abnormality is detected in the regenerative brake and an abnormality is detected in a sensor of the braking system, the BCU 14 performs a second braking force compensation control. In this second braking force compensation control, the BCU 14 performs braking force compensation by a braking force due to a preset brake fluid pressure. Here, the case where at least an abnormality is detected in the regenerative brake and an abnormality is detected in a sensor of the braking system also includes, for example, a case where an abnormality is detected in the regenerative brake, an abnormality is detected in the control system of the power unit PU, and an abnormality is detected in a sensor of the braking system.

[0048] In addition, a sensor abnormality in the braking system refers to, for example, a case where each wheel speed sensor 17, acceleration sensor 18, etc., is not outputting a sensor value or is outputting an abnormal sensor value due to a well-known abnormality diagnosis in the BCU 14.

[0049] Thus, in this embodiment, the HEV_CU10, together with the ECU11, TCU12, PCU13, and BCU14, functions as a braking force control means. The ECU11, TCU12, etc., function as a power unit abnormality detection means. The PCU13 functions as a regenerative brake abnormality detection means and a regenerative stop means. The BCU14 functions as a braking force compensation means and a braking system sensor abnormality detection means.

[0050] Next, the braking torque distribution control for each brake (regenerative brake, engine brake, and friction brake) will be described with reference to the flowchart of the braking torque distribution control routine shown in Fig. 3. This routine is repeatedly executed at set time intervals in the HEV_CU 10.

[0051] When the routine starts, the HEV_CU10 checks in step S101 whether or not a deceleration request has been made. That is, the HEV_CU10 determines that a deceleration request due to coasting has been made when, for example, the HEV_CU10 detects that the accelerator pedal 15a is released based on a signal from the accelerator sensor 15. Alternatively, the HEV_CU10 determines that a deceleration request has been made when, for example, the HEV_CU10 detects that the brake pedal 16a is depressed based on a signal from the brake sensor 16. Alternatively, the HEV_CU10 determines that a deceleration request has been made when, for example, a target deceleration is input from a driving support device (not shown).

[0052] Then, in step S101, if it is determined that there is no deceleration request, the HEV_CU 10 exits the routine.

[0053] On the other hand, when the process proceeds from step S101 to step S102, the HEV_CU10 acquires a target deceleration. That is, for example, during coasting, the HEV_CU10 calculates a target deceleration based on a signal (accelerator opening degree, etc.) from the accelerator sensor 15, the vehicle speed, etc. Also, for example, when the HEV_CU10 detects depression of the brake pedal by the driver based on a signal from the brake sensor 16, the HEV_CU10 calculates a target deceleration based on signals from the first and second brake fluid pressure sensors 59a, 59b, etc. Furthermore, in the vehicle 1 equipped with a driving support device (not shown), the target deceleration for automatic brake control, etc., calculated by the driving support device is acquired.

[0054] In the next step S103, the HEV_CU 10 calculates a necessary braking torque based on the current target deceleration. Then, the HEV_CU 10 calculates each braking torque distribution value for distributing the calculated necessary braking torque to the regenerative brake, the engine brake, and the friction brake according to the running state of the host vehicle 1, etc.

[0055] Then, when the process proceeds from step S103 to step S104, the calculated braking torque distribution value is outputted as control information to the corresponding control unit, and then the routine ends.

[0056] That is, for example, when a braking torque distribution value for the regenerative brake is calculated, the HEV_CU 10 outputs the braking torque distribution value to the PCU 13 as control information. As a result, magnetic field control for regenerative power generation in the motor generator 4 is performed, and a regenerative braking force according to the braking torque distribution value is generated. Note that when a regenerative inhibition flag F, which will be described later, is set to "1", the regenerative brake is prohibited. Therefore, when the regenerative inhibition flag F is set to "1", the regenerative brake is excluded from the calculation of the braking torque distribution value in the above-mentioned step S103.

[0057] Furthermore, for example, when a braking torque distribution value for engine braking is calculated, the HEV_CU 10 outputs the braking torque distribution value as control information to the ECU 11 and the TCU 12. As a result, the output torque of the engine 2 and the gear ratio of the automatic transmission 3 are controlled, and an engine braking force according to the braking torque distribution value is generated.

[0058] Furthermore, for example, when a braking torque distribution value for a friction brake is calculated, the HEV_CU 10 outputs the braking torque distribution value as control information to the BCU 14. This causes brake fluid pressure control in the brake actuator 6 to be performed, and a friction brake force according to the braking torque distribution value is generated.

[0059] Next, the regenerative brake disconnection control when an abnormality occurs in the regenerative brake will be described with reference to the flowchart of the disconnection control routine shown in Fig. 4. This disconnection control is for disconnecting the regenerative brake from the braking control when an abnormality in the regenerative brake is detected during the above-mentioned braking control (braking torque distribution control). This routine is repeatedly executed by the PCU 13 at set time intervals.

[0060] When the routine starts, the PCU 13 checks in step S201 whether or not the regeneration inhibition flag F is set to "1."

[0061] Then, if it is determined in step S201 that the regeneration inhibition flag F is set to "1", the PCU 13 exits the routine.

[0062] On the other hand, if it is determined in step S201 that the regeneration inhibition flag F is cleared to "0", the PCU 13 proceeds to step S202 and checks whether or not a regenerative brake abnormality has been detected.

[0063] Then, if it is determined in step S202 that no abnormality in the regenerative brake has been detected, the PCU 13 exits the routine.

[0064] On the other hand, if it is determined in step S202 that a regenerative brake abnormality has been detected, the PCU 13 proceeds to step S203 and checks whether or not regenerative brake control is currently being performed.

[0065] Then, if it is determined in step S203 that regenerative braking control is not being performed, the PCU 13 proceeds to step S206.

[0066] On the other hand, if it is determined in step S203 that regenerative braking control is being performed, the PCU 13 proceeds to step S204 and executes separation of the regenerative braking from the braking force control. That is, the PCU 13, for example, releases the magnetic field control for regenerative power generation for the motor generator 4, and disconnects the motor generator 4 from the output shaft of the automatic transmission 3 through clutch control (not shown) or the like.

[0067] When the process proceeds from step S204 to step S205, the PCU 13 checks whether or not the regenerative brake has been disconnected.

[0068] Then, in step S205, if it is determined that the regenerative brake has not been completely disconnected, the PCU 13 returns to step S204.

[0069] On the other hand, if it is determined in step S205 that the regenerative braking has been disconnected, the PCU 13 proceeds to step S206.

[0070] When the process proceeds from step S203 or step S205 to step S206, the PCU 13 sets a regeneration inhibition flag F, which inhibits regenerative braking, to "1", and then exits the routine.

[0071] Next, braking force compensation control when an abnormality occurs in the regenerative brake will be described with reference to a flowchart of a braking force compensation control routine shown in Fig. 5. This routine is repeatedly executed by the BCU 14 at set time intervals.

[0072] When the routine starts, the BCU 14 checks in step S301 whether the regeneration prohibition flag F is set to "1".

[0073] Then, if it is determined in step S301 that the prohibition flag F is set to "1", the BCU 14 exits the routine as is.

[0074] On the other hand, if it is determined in step S301 that the prohibition flag F is cleared to "0", the BCU 14 proceeds to step S302 and checks whether the PCU 13 has detected an abnormality in the regenerative brake.

[0075] Then, if it is determined in step S302 that no abnormality in the regenerative brakes has been detected, the BCU 14 exits the routine.

[0076] On the other hand, if it is determined in step S302 that a regenerative brake abnormality has been detected, the BCU 14 checks whether or not a sensor abnormality in the control system has been detected.

[0077] Then, if it is determined in step S303 that an abnormality in the power unit control system has been detected, the BCU 14 proceeds to step S305.

[0078] On the other hand, if it is determined that no abnormality has been detected in the power unit control system, the BCU 14 proceeds to step S304 and executes the first braking force compensation control.

[0079] This first braking force compensation control is executed, for example, in accordance with a subroutine of a first braking force modification control shown in FIG.

[0080] When the subroutine starts, the BCU 14 checks in step S401 whether or not the regenerative brake has just been cut off due to an abnormality.

[0081] Then, in step S401, if it is determined that the regenerative brake has not been disconnected immediately, the BCU 14 proceeds to step S404.

[0082] On the other hand, if it is determined in step S401 that the regenerative brakes have just been disconnected, the BCU 14 proceeds to step S402 and stores the deceleration at the time when the abnormality in the regenerative brakes has occurred (immediately before the regenerative brakes are disconnected) as the target deceleration.

[0083] In the following step S403, the BCU 14 calculates the brake fluid pressure required to generate the target deceleration by friction braking based on the target deceleration and the current deceleration of the vehicle 1 (for example, the deceleration detected by the longitudinal acceleration sensor 18), and then proceeds to step S406.

[0084] Furthermore, when proceeding from step S401 to step S404, the BCU 14 calculates a feedback correction amount for the target brake fluid pressure based on the target deceleration set in step S402 and the current deceleration of the vehicle 1 (for example, the deceleration detected by the longitudinal acceleration sensor 18).

[0085] Then, in step S404, the BCU 14 corrects the target brake fluid pressure based on the feedback correction amount, and then proceeds to step S406.

[0086] When the process proceeds from step S403 or step S405 to step S406, the BCU 14 performs brake fluid pressure control on the brake actuator 6 using the target brake fluid pressure, and then exits the subroutine.

[0087] Also, in the main routine of FIG. 5, when the process proceeds from step S303 to step S305, the BCU 14 performs the second braking force compensation control, and then the process proceeds to step S306.

[0088] This second braking force compensation control is executed, for example, in accordance with a subroutine of the second braking force compensation control shown in FIG.

[0089] When the subroutine starts, in step S501, the BCU 14 checks whether or not the brake fluid pressure when an abnormality occurs in the regenerative brake (immediately before the regenerative brake is cut off) is equal to or higher than a preset threshold value.

[0090] Then, in step S501, if it is determined that the brake fluid pressure when the abnormality occurs in the regenerative brake is less than the threshold value, the BCU 14 directly exits the subroutine.

[0091] On the other hand, if it is determined in step S501 that the brake fluid pressure when a regenerative braking abnormality occurs is equal to or greater than the threshold value, the BCU 14 proceeds to step S502, performs brake fluid pressure control on the brake actuator 6 using a preset constant brake fluid pressure, and then exits the subroutine.

[0092] In the main routine of FIG. 5, when the process proceeds from step S304 or step S305 to step S306, the BCU 14 checks whether or not separation of the braking force control of the regenerative brake has been completed.

[0093] Then, in step S306, if it is determined that the regenerative brake has not been completely disconnected, the BCU 14 returns to step S302.

[0094] On the other hand, if it is determined in step S306 that the regenerative brake has been released, the BCU 14 exits the routine.

[0095] According to this embodiment, during braking control using engine braking, regenerative braking, and friction braking in a coordinated manner, when an abnormality in the regenerative braking is detected, BCU14 sets the deceleration at the time the abnormality in the regenerative braking is detected as the target deceleration, and performs feedback control on the target deceleration to compensate for the braking force using the friction brake, thereby enabling appropriate braking to be performed even when multiple abnormalities occur.

[0096] That is, even if an abnormality occurs in the regenerative brake, or even if an abnormality occurs in the regenerative brake and the control information of the control system of the power unit PU cannot be used for the braking control, the braking force compensation is performed by feedback control using only the sensor information that can be acquired by the BCU 14, so that a temporary decrease in the braking force of the entire vehicle 1 can be prevented even until the regenerative brake is separated from the braking force control. Therefore, an increase in the braking distance, etc. can be appropriately prevented and safety can be ensured. In addition, feedback control is performed on the deceleration when an abnormality in the regenerative brake is detected until the regenerative brake is separated from the braking force control, so that it is possible to prevent the occupants from feeling uncomfortable due to a sudden increase in deceleration.

[0097] Furthermore, at least when a regenerative brake abnormality and a braking system sensor abnormality are detected, BCU14 performs braking force compensation using a preset constant brake fluid pressure instead of braking force compensation by feedback control, thereby enabling braking force compensation to be performed even for more complex abnormalities.

[0098] In this case, when the brake fluid pressure when a regenerative brake abnormality is detected is below a predetermined threshold value, braking force compensation using a constant brake fluid pressure is not performed, thereby preventing the generation of excessive braking force.

[0099] In the above-described embodiment, the HEV_CU10, ECU11, TCU12, PCU13, and BCU14 are configured with a well-known microcomputer equipped with a CPU, RAM, ROM, non-volatile storage unit, and peripheral devices thereof, and the ROM stores programs to be executed by the CPU and fixed data such as data tables in advance. Note that all or part of the functions of the processor may be configured with a logic circuit or an analog circuit, and the processing of various programs may be realized by an electronic circuit such as an FPGA.

[0100] The invention described in the above embodiment is not limited to those embodiments, and various modifications can be made in the implementation stage without departing from the gist of the invention.

[0101] For example, if some of the constituent elements shown in each form are deleted, and the stated problem can be solved and the stated effect can be obtained, the configuration from which these constituent elements are deleted can be extracted as an invention. [Explanation of symbols]

[0102] 1 … Vehicle (own vehicle) 2 … Engine 3. Automatic transmission 4 … Motor generator 5(5fl,5fr,5rl,5rr) … Wheels 6 … Brake actuator 7 … Battery 8 (8fl, 8fr, 8rl, 8rr) ... Wheel cylinder 10 … Hybrid control unit (HEV_CU) 11 … Engine control unit (ECU) 12 … Transmission control unit (TCU) 13 ... Power Control Oil Niche (PCU) 13a … Inverter 14 … Brake control unit (BCU) 15 ... Accelerator sensor 15a ... accelerator pedal 16 ... Brake sensor 16a ... Brake pedal 17 (17fl, 17fr, 17rl, 17rr) ... Wheel speed sensor 18 ... Front and rear acceleration sensor 41 ... Brake fluid pressure generating section 42 ... Brake hydraulic circuit 44 ... Master cylinder 44a, 44b … Supply and exhaust ports 45 ... Reservoir tank 46 ... Brake booster 48 ... Operating rod 52,53 … Brake hydraulic circuit 54 ... Low pressure accumulator 55 … Gate-in valve 56 ... Hydraulic pump 57 … Electric motor 58 … Bypass valve 59a, 59b ... Brake fluid pressure sensor 60,61 … Pressure valve 62,63 … Pressure reducing valve

Claims

1. A braking control device for a hybrid vehicle having an engine and a motor generator as a drive source of a power unit, a braking force control unit that controls a braking force by coordinating an engine brake using the engine, a regenerative brake using the motor generator, and a friction brake using a friction engagement element; A regenerative brake abnormality detection means for detecting an abnormality in the regenerative brake; a power unit abnormality detection means for detecting an abnormality in a control system of the power unit; a regenerative braking stop means for isolating the regenerative brake from the braking force control and stopping the operation of the regenerative brake when an abnormality in the regenerative brake is detected; a braking force compensation means for performing braking force compensation using the friction brake during a period from when an abnormality in the regenerative brake is detected until when the regenerative brake is separated from the braking force control; a brake system sensor abnormality detection means for detecting an abnormality in a brake system sensor; Equipped with the braking force compensation means performs the braking force compensation by feedback control of the deceleration when an abnormality in the regenerative brake is detected, The braking force compensation means performs the braking force compensation by a preset constant brake fluid pressure for the friction brake, instead of the braking force compensation by the feedback control, at least when an abnormality in the regenerative brake and an abnormality in a sensor of the braking system are detected.

2. The braking force compensation means of the braking control device for a hybrid vehicle as described in claim 1, characterized in that even if an abnormality in the regenerative brake is detected, an abnormality in the control system of the power unit, and a sensor abnormality in the braking system is detected, when the brake fluid pressure when the abnormality in the regenerative brake is detected is less than a predetermined threshold value, does not perform the braking force compensation using the constant brake fluid pressure.

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