JP2016041567A - Brake system of hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure brake force that meets the needs of a driver, regardless of whether regenerative power generation is possible.SOLUTION: A brake system 1 includes: an operation section SW for switching the states of a hybrid vehicle V between a first state and a second state; a determination section 50 for determining whether a motor generator 41 can generate regenerative power; and a controller 50 for controlling a clutch 19 and an exhaust brake device 33 on the basis of the determination result of the determination section 50. When an accelerator is off, the motor generator 41 applies regenerative brake force equivalent to that of an engine brake in the first state, and applies regenerative brake force equivalent to that of an exhaust brake in the second state. When the accelerator is off and it is determined that the regenerative power cannot be generated, the controller 50 does not make the motor generator 41 apply the regenerative brake force. Under these conditions, when in the first state, the controller connects the clutch 19 and makes the engine brake work, and when in the second state, connects the clutch 19, actuates the exhaust brake device 33, and makes the exhaust brake work.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a brake system for a hybrid vehicle.

  Conventionally, a brake system that brakes a hybrid vehicle including an engine and a motor generator is known. For example, in the brake system described in Patent Document 1, a regenerative braking force equivalent to engine braking by a motor generator is applied when the accelerator is off, and the kinetic energy of the vehicle is converted into electric energy, so that the vehicle is decelerated and the motor generator The battery that is the power source is charged.

JP-A-8-79911

  In the brake system of the above-mentioned patent document 1, when regenerative power generation is impossible, such as when an abnormality occurs in the battery or when the battery charge amount (SOC: State Of Charge) is equal to or greater than a predetermined amount, It becomes difficult to apply a regenerative braking force having a magnitude to be applied.

  Some common vehicles include a brake system that can switch the magnitude of the braking force when the accelerator is off according to a driver's request. In this brake system, for example, when the accelerator is off, an engine brake is applied in a normal state, and an exhaust brake (exhaust brake) having a braking force larger than that of the engine brake is applied when the operation switch is turned on. In recent years, even in hybrid vehicles, it has been required that the magnitude of braking force when the accelerator is off can be switched according to the driver's request.

  The present invention has been made in view of the above circumstances, and provides a brake system for a hybrid vehicle that can ensure a braking force that meets the driver's request regardless of whether or not regenerative power generation is possible. Objective.

  A brake system for a hybrid vehicle according to the present invention is a brake system that brakes a hybrid vehicle including an engine having an exhaust brake device connected to a drive system via a clutch, and a motor generator connected to the drive system. The operation unit for switching the state of the hybrid vehicle between at least the first state and the second state, which are different in magnitude of the braking force applied when the accelerator is off, and whether the motor generator is capable of regenerative power generation And a control unit that controls the clutch and the exhaust brake device based on the determination result of the determination unit, and the motor generator has a regeneration corresponding to the engine brake of the engine in the first state when the accelerator is off. The braking force is applied, and in the second state, the exhaust brake is operated by the exhaust brake device. When the determination unit determines that the motor generator is not capable of regenerative power generation, the control unit does not apply the regenerative braking force to the motor generator when the accelerator is off, and the clutch is engaged in the first state. In the second state, the clutch is connected and the exhaust brake device is operated to operate the exhaust brake.

  In this brake system, the braking force when the accelerator is off can be switched between the regenerative braking force by the motor generator and the braking force by the engine depending on whether or not the motor generator can perform regenerative power generation. Moreover, the magnitude of the braking force when the accelerator is off can be switched depending on whether the state of the hybrid vehicle switched by the operation unit is the first state or the second state. Therefore, according to this brake system, it is possible to ensure a braking force that meets the driver's request regardless of whether or not regenerative power generation is possible.

  In the hybrid vehicle brake system according to the present invention, the determination unit calculates the regeneration required torque based on the traveling state of the hybrid vehicle, and based on the charging state and the allowable charging current of the battery that supplies power to the motor generator. Then, the regenerative torque is calculated, and if the regenerative request torque is larger than the regenerative torque, the motor generator may determine that regenerative power generation is not possible. According to this brake system, even when regenerative power generation is not possible because the battery charge is high and the regenerative request torque is larger than the regenerative torque, the braking force that meets the driver's request Can be secured.

  In the hybrid vehicle brake system according to the present invention, the determination unit includes a motor generator, a battery that supplies power to the motor generator, and a motor generator and an inverter that is electrically connected to the battery. When the abnormality of the high voltage system is detected on the basis of the operating state, and the abnormality of the high voltage system is detected, the motor generator may determine that regenerative power generation is not possible. According to this brake system, even when an abnormality occurs in a high voltage system including a motor generator, a battery, and an inverter and regenerative power generation becomes impossible, a braking force that meets the driver's request is ensured. It becomes possible.

  In the braking system for a hybrid vehicle according to the present invention, the hybrid vehicle includes an EV traveling mode in which the engine is stopped and the motor generator is used as a driving force source, and an HV traveling mode in which the engine and the motor generator are used as driving force sources. The control unit may start the stopped engine when the determination unit determines that the motor generator is incapable of regenerative power generation and the hybrid vehicle is in the EV travel mode. According to this brake system, even if regenerative power generation is disabled during EV travel when the engine is stopped, the engine is started and the braking force by the engine is applied to meet the driver's request. It is possible to ensure a matching braking force.

  ADVANTAGE OF THE INVENTION According to this invention, the brake system of the hybrid vehicle which can supply the braking force according to a driver | operator's request | requirement regardless of whether regenerative power generation is possible can be provided.

It is a schematic structure figure showing a brake system concerning one embodiment. It is a flowchart which shows the process by the brake system shown in FIG.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are used for the same or corresponding elements, and duplicate descriptions are omitted.

  FIG. 1 is a schematic configuration diagram illustrating a brake system according to an embodiment. The brake system 1 according to the present embodiment is configured as a brake system that brakes a hybrid vehicle V including an engine 30 and a motor generator 41. Below, the outline | summary of the hybrid vehicle V and the brake system 1 is demonstrated first, and after describing the structure of the brake system 1 with the structure of the hybrid vehicle V, operation | movement of the brake system 1 is demonstrated.

  The hybrid vehicle V is configured as, for example, a plug-in hybrid vehicle (hereinafter, PHV: Plug-in Hybrid Vehicle) that can directly supply power to the battery using an insertion plug. Examples of the hybrid vehicle V to be applied include a medium-sized bus. The hybrid vehicle V here is a PHV bus configured by attaching a motor generator 41 to an existing diesel engine bus in an add-on manner. The hybrid vehicle V is not particularly limited, and may be, for example, a commercial vehicle such as a truck, or may be a large vehicle, a medium vehicle, a normal passenger vehicle, a small vehicle, a light vehicle, or the like. The hybrid vehicle V may be configured as a hybrid vehicle other than PHV.

  The hybrid vehicle V includes, for example, an EV travel mode, an HV travel mode, and an engine travel mode as travel modes, and travels while appropriately switching between them. The EV travel mode is a travel mode in which, for example, the engine 30 is stopped and only the motor generator 41 is used as a driving force source. The HV traveling mode is a traveling mode in which, for example, the engine 30 is operated and the engine 30 and the motor generator 41 are used as driving force sources. The engine travel mode is, for example, a travel mode in which the motor generator 41 is not used as a driving force source and the engine 30 is traveled using only the engine 30 as a driving force source. Switching between these travel modes is automatically performed based on, for example, the travel state of the hybrid vehicle V and the area in which the hybrid vehicle V is traveling.

  In the brake system 1, in any of the EV travel mode, the HV travel mode, and the engine travel mode, basically, when the accelerator is off, a regenerative braking force is applied by the motor generator 41 to perform deceleration and power generation (regenerative braking). . That is, when the accelerator is off, a regenerative braking force of a predetermined magnitude is applied to the motor generator 41 to convert the kinetic energy of the hybrid vehicle V into electric energy, thereby decelerating the hybrid vehicle V and the electric power of the motor generator 41. The battery 45 as a source is charged.

  However, regenerative power generation by the motor generator 41 may not be possible (eg, when the battery 45 is abnormal or when the state of charge (SOC) of the battery 45 is greater than or equal to a predetermined amount). (Expired). In this case, it is difficult to apply a regenerative braking force having a magnitude that should be applied. For example, when the battery 45 is abnormal, the regenerative braking force cannot be generated. In addition, when the charge amount of the battery 45 is equal to or greater than a predetermined amount, a current exceeding the allowable charge current cannot flow through the battery 45, so that only a regenerative braking force smaller than the amount that should originally be generated is generated. I can't. Therefore, in the brake system 1, when regenerative power generation is disabled as described above, the regenerative braking force by the motor generator 41 is not applied when the accelerator is turned off, and instead of the regenerative braking force by the motor generator 41. The required braking force is ensured by applying a mechanical braking force by the engine 30 to the engine. Details of this processing will be described later.

  Further, the hybrid vehicle V includes, for example, a combination switch SW as an operation unit for switching a braking mode related to the braking force when the accelerator is off. The combination switch SW is attached to a steering column (not shown) that supports a steering wheel (not shown), for example. In the present embodiment, the hybrid vehicle V has two states: a first state in which the combination switch SW is off and a second state in which the combination switch SW is on. The braking force when the accelerator is off is the magnitude of the engine brake by the engine 30 when the combination switch SW is off, and the exhaust brake (exhaust brake) having a braking force greater than that of the engine brake when the combination switch SW is on. It is said that the size.

  In the brake system 1, basically, when the accelerator switch is off, the regenerative braking force corresponding to the engine brake is applied by the motor generator 41 when the combination switch SW is off, and the engine brake when the combination switch SW is on. A regenerative braking force corresponding to is applied by the motor generator 41. That is, the electric energy is recovered by the regenerative braking force with strength depending on whether the combination switch SW is turned on or off.

  On the other hand, in the brake system 1, when regenerative power generation is not possible, mechanical braking force by the engine 30 is applied instead of regenerative braking force by the motor generator 41. At this time, the engine brake is applied when the combination switch SW is off, and the exhaust brake is applied when the combination switch SW is on so that a braking force that meets the driver's request is applied. Details of this processing will also be described later.

  Next, the configuration of the brake system 1 will be described together with the configuration of the hybrid vehicle V. The hybrid vehicle V includes a driving system 10 that transmits driving force to wheels W, an engine 30 that is connected to the driving system 10 via a clutch 19 and has an exhaust brake device 33, and a motor generator 41 that is connected to the driving system 10. A high voltage system 40 including a PHVECU (ECU: Electronic Control Unit) 50 (determination unit, control unit), a vehicle control ECU 60, an AMTECU 70, and a CCU (Charge Control Unit) 80 are provided. In this hybrid vehicle V, the brake system 1 includes the combination switch SW (operation unit) and PHVECU 50 (determination unit, control unit).

  The drive system 10 includes an AMT (AMT: Automated Manual Transmission) 11, a transfer 13, and a clutch 19. The AMT 11 is configured as a mechanical automatic transmission, and automatically performs a shift operation such as changing the gear position (shift) and controlling the connection and disconnection of the clutch 19. The AMT 11 is connected to the transfer 13 via the first propeller shaft 14 and transmits the driving force from the engine 30 to the transfer 13.

  A first propeller shaft 14, a second propeller shaft 15, and a motor generator 41 are connected to the transfer 13 so as to be able to transmit a driving force. That is, the transfer 13 is connected to the engine 30 via the AMT 11 and the first propeller shaft 14, and is connected to the wheels W via the second propeller shaft 15, the differential gear 16, and the drive shaft 17.

  The transfer 13 includes, for example, at least one clutch (not shown) therein, and has a function of switching between transmission and non-transmission of driving force among the engine 30, the motor generator 41, and the wheels W. . For example, when the traveling mode of the hybrid vehicle V is the EV traveling mode, the driving force is transmitted between the motor generator 41 and the wheels W. In the transfer 13, for example, when the traveling mode of the hybrid vehicle V is the HV traveling mode, the driving force is transmitted among the engine 30, the motor generator 41, and the wheels W. In the transfer 13, for example, when the hybrid vehicle V is in the engine travel mode, the driving force is transmitted between the engine 30 and the wheels W.

  In addition to driving the wheels W by the driving force, the engine 30 has an engine braking effect in which a mechanical braking force is applied to the wheels W by a resistance force generated inside. Examples of the engine 30 include a diesel engine and a gasoline engine. The engine 30 is appropriately started or stopped based on, for example, the travel mode of the hybrid vehicle V. The AMT 11 is connected to the output shaft of the engine 30 via the clutch 19.

  An exhaust brake device 33 is disposed on the downstream side of the exhaust manifold 31 of the engine 30. The exhaust brake device 33 is an exhaust valve configured by, for example, an electromagnetic valve, and adjusts the amount of resistance in the engine 30 by restricting the flow of exhaust gas flowing through the exhaust manifold 31 by opening and closing the valve. In a state where the exhaust brake device 33 is operated and the valve is closed, the engine brake effect is increased and an exhaust brake having a braking force larger than that of the engine brake is applied.

  The high voltage system 40 includes a motor generator 41, an inverter 43, and a battery 45, and these are electrically connected by a high voltage cable 47. The motor generator 41 functions as a driving force source for the hybrid vehicle V, and also functions as a generator for charging the battery 45 by generating regenerative braking force when the accelerator is off. The inverter 43 is electrically connected to the motor generator 41 and the battery 45, and performs current control while converting the direct current of the battery 45 and the alternating current of the motor generator 41.

  The battery 45 is configured by electrically connecting a plurality of secondary batteries therein, and supplies power to the motor generator 41. Various types of secondary batteries can be used as the battery 45, and a lithium ion battery is employed here. The battery 45 is configured to be able to supply high-voltage (for example, 300 V) power that is equal to or higher than the drive voltage of the motor generator 41.

  The PHVECU 50, the vehicle control ECU 60, the AMTECU 70, and the CCU 80 are each configured by a computer including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), for example. The PHVECU 50 is electrically connected to the inverter 43, the vehicle control ECU 60, the AMTECU 70, and the CCU 80 via, for example, a CAN (Controller Area Network), and performs overall control that causes the hybrid vehicle V to function as a PHV. For example, the PHVECU 50 executes a driving mode switching control of the hybrid vehicle V and a regeneration determination process which will be described later with reference to FIG. As will be described later, in the regeneration determination process, the PHVECU 50 functions as a determination unit that determines whether or not the motor generator 41 can be regenerated, and controls the clutch 19 and the exhaust brake device 33 based on the determination result. It also functions as a part. The PHVECU 50 is configured to be able to receive an output signal from the combination switch SW.

  The vehicle control ECU 60 is electrically connected to the PHVECU 50 and the exhaust brake device 33. For example, the vehicle control ECU 60 controls the operation of the exhaust brake device 33 in accordance with an instruction from the PHVECU 50. Further, the vehicle control ECU 60 acquires vehicle information such as the traveling state of the hybrid vehicle V including the vehicle speed and the engine speed and the opening degree of an accelerator pedal (not shown), and outputs the vehicle information to the PHVECU 50. The AMT ECU 70 is electrically connected to the PHVECU 50 and the AMT 11 and controls, for example, a shift operation of the AMT 11 according to an instruction from the PHVECU 50. The CCU 80 is electrically connected to the PHVECU 50 and the battery 45, acquires the state of charge of the battery 45, and outputs it to the PHVECU 50.

  Next, the operation of the brake system 1 will be described with reference to FIG. The regeneration determination process shown in FIG. 2 is executed by the PHVECU 50. Specifically, the PHVECU 50 starts the regeneration determination process shown in FIG. 2 when determining that the accelerator is turned off.

  First, the PHVECU 50 determines whether or not the combination switch SW is on (step S11). If the combination switch SW is on, the process proceeds to step S12. If the combination switch SW is off, the process proceeds to step S19.

  In step S12, the PHVECU 50 determines whether or not the high voltage system 40 is normal. Specifically, the high voltage system 40 is based on the operating state of the motor generator 41 and the inverter 43 detected based on the output signal from the inverter 43 and the operating state of the battery 45 detected based on the output signal from the CCU 80. It is determined whether or not it is normal. If it is determined that the high voltage system 40 is normal, the process proceeds to step S13. If an abnormality of the high voltage system 40 is detected and it is determined that regenerative power generation is not possible, the process proceeds to step S15. In addition, according to the determination in step S12, not only when abnormality occurs in the motor generator 41, the inverter 43, and the battery 45 itself, abnormality due to disconnection of the high voltage cable 47 or the like is also detected.

  In step S <b> 13, the PHVECU 50 determines whether the regenerative request torque calculated from the traveling state of the hybrid vehicle V is equal to or less than the regenerative torque calculated from the charged state of the battery 45 and the allowable charging current. The regeneration request torque is calculated based on, for example, a map in which the vehicle speed is associated with the braking torque amount. The regenerative torque is calculated based on, for example, the difference between the full charge amount of the battery 45 and the current charge amount, the allowable charging current, and the current rotation speed of the motor generator 41. The PHVECU 50 proceeds to step S14 when the regenerative request torque is equal to or less than the regenerative torque, and proceeds to step S15 when the regenerative request torque is larger than the regenerative torque and it is determined that regenerative power generation is impossible. That is, when it determines with regenerative power generation impossible at step S12 or S13, it progresses to step S15.

  In step S <b> 14, the PHVECU 50 causes the motor generator 41 to generate a regenerative braking force corresponding to the exhaust brake to act on the wheels W. More specifically, PHVECU 50 controls inverter 43 so that the driving force transmitted to motor generator 41 has a magnitude corresponding to the exhaust brake. The equivalent value of the exhaust brake can be acquired using, for example, a map associated with the vehicle speed of the hybrid vehicle V. Thus, when the combination switch SW is on and regenerative power generation is possible, a regenerative braking force corresponding to the exhaust brake is applied to the wheels W. At this time, the PHVECU 50 transmits an operation prohibition request for the exhaust brake device 33 to the vehicle control ECU 60, and transmits a disconnection request for the clutch 19 to the AMTECU 70. Thus, the exhaust brake is not operated, and the braking force by the engine 30 is not transmitted to the wheels W regardless of the operating state of the engine 30.

  In step S15, PHVECU 50 determines whether or not the travel mode is the EV travel mode. As a result of the determination, when it is determined that the travel mode is the EV travel mode, the stopped engine 30 is started (step S16), and then the process proceeds to step S17. On the other hand, as a result of the determination, when it is determined that the travel mode is not the EV travel mode (HV travel mode or engine travel mode), the process proceeds to step S17 as it is. This is because the engine 30 has already been started in the HV traveling mode and the engine traveling mode.

  In step S <b> 17, the PHVECU 50 transmits a connection request for the clutch 19 to the AMTECU 70, and transmits an operation request for the exhaust brake device 33 to the vehicle control ECU 60 (cancels the operation prohibition request). Thereby, the drive system 10 and the engine 30 are connected, the exhaust brake is operated, and the braking force by the exhaust brake is applied to the wheels W (step S18). At this time, PHVECU 50 does not generate a regenerative braking force by motor generator 41. As a method of not generating the regenerative braking force by the motor generator 41, for example, a method of stopping the driving of the motor generator 41 or a method of controlling the inverter 43 so that the regenerative braking force by the motor generator 41 is not transmitted to the wheels W is adopted. it can.

  Also in step S19, the PHVECU 50 acquires the operating state of the high voltage system 40 and determines whether the high voltage system 40 is normal as in step S12. If it is determined that the high voltage system 40 is normal, the process proceeds to step S20. If it is determined that an abnormality has occurred in the high voltage system 40 and regenerative power generation is not possible, the process proceeds to step S21.

  In step S20, the PHVECU 50 determines whether or not the regenerative request torque is equal to or less than the regenerative torque as in step S13. If the regenerative request torque is equal to or less than the regenerative torque, the process proceeds to step S21. If the regenerative request torque is greater than the regenerative torque and it is determined that regenerative power generation is not possible, the process proceeds to step S22.

  In step S <b> 21, the PHVECU 50 causes the motor generator 41 to generate a regenerative braking force corresponding to the engine brake so as to act on the wheels W. More specifically, PHVECU 50 controls inverter 43 so that the driving force transmitted to motor generator 41 has a magnitude corresponding to the engine brake. The equivalent value of the engine brake can be acquired using, for example, a map associated with the vehicle speed of the hybrid vehicle V. Thus, when the combination switch SW is off and regenerative power generation is possible, the regenerative braking force corresponding to the engine brake is applied to the wheels W. At this time, the PHVECU 50 transmits a request for prohibiting the operation of the exhaust brake device 33 to the vehicle control ECU 60 and transmits a request for disengaging the clutch 19 to the AMTECU 70. Thus, the exhaust brake is not operated, and the braking force by the engine 30 is not transmitted to the wheels W regardless of the operating state of the engine 30.

  In step S22, PHVECU 50 determines whether the travel mode is the EV travel mode, as in step S15. As a result of the determination, when it is determined that the travel mode is the EV travel mode, the stopped engine 30 is started (step S23), and then the process proceeds to step S24. On the other hand, as a result of the determination, if it is determined that the travel mode is not the EV travel mode, the process directly proceeds to step S24.

  In step S <b> 24, the PHVECU 50 transmits a clutch 19 connection request to the AMTECU 70 and does not cancel the operation prohibition request for the exhaust brake device 33 to the vehicle control ECU 60. Thereby, the drive system 10 and the engine 30 are connected, the engine brake is activated, and the braking force by the engine brake is applied to the wheels W (step S25). At this time, PHVECU 50 does not generate a regenerative braking force by motor generator 41.

  As described above, in the brake system 1, the braking force when the accelerator is off is switched between the regenerative braking force by the motor generator 41 and the braking force by the engine 30 depending on whether or not the motor generator 41 can perform regenerative power generation. Can be used. Further, the magnitude of the braking force when the accelerator is off can be switched according to whether the combination switch SW is on or off. Therefore, according to the brake system 1, it is possible to ensure a braking force that meets the driver's request regardless of whether or not regenerative power generation is possible.

  Further, according to the brake system 1, even when the rechargeable power generation is not possible because the charge amount of the battery 45 is high and the regenerative request torque is larger than the rotatable torque, it meets the driver's request. It is possible to secure a sufficient braking force. Further, since the determination is made with reference to the current traveling state of the hybrid vehicle V and the charged state of the battery 45, it is possible to accurately determine whether or not regenerative power generation is possible.

  In addition, according to the brake system 1, even if an abnormality occurs in the high voltage system 40 including the motor generator 41, the battery 45, and the inverter 43 and regenerative power generation becomes impossible, it meets the driver's request. It is possible to secure a sufficient braking force.

  Further, according to the brake system 1, even when the regenerative power generation is disabled during EV traveling when the engine 30 is stopped, the engine 30 is started and the mechanical braking force by the engine 30 is applied. Thus, it is possible to secure a braking force that meets the driver's request.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments. The present invention can be modified without departing from the scope described in the claims or applied to other embodiments. May be.

  For example, in the above embodiment, based on both whether or not the high voltage system 40 is normal (steps S12 and S19) and whether or not the regenerative request torque is equal to or lower than the regenerative torque (steps S13 and S20). Although an example of determining whether or not regenerative power generation is possible has been described, only one of them may be used for the determination. Further, in addition to or instead of these, it may be determined whether or not regenerative power generation is possible by another method. For example, when it is identified that CAN communication between the PHVECU 50 and the vehicle control ECU 60, the AMTECU 70, or the CCU 80 has been interrupted, it may be determined that regenerative power generation is not possible. When CAN communication with the vehicle control ECU 60 is interrupted, the PHVECU 50 cannot identify the opening degree of the accelerator pedal, and when CAN communication with the AMTECU 70 is interrupted, the clutch 19 can be disconnected when the regenerative braking force is applied. Disappear. When CAN communication with the CCU 80 is interrupted, the PHVECU 50 cannot identify the state of the battery 45. Also, when it is identified that the CCU 80 has failed, it may be determined that regenerative power generation is not possible. In addition, when an abnormality occurs in the cooling circuit (for example, a fan or a water pump) of the motor generator 41 and the inverter 43, it may be determined that regenerative power generation is impossible. When an abnormality occurs in the cooling circuit, the motor generator 41 and the inverter 43 cannot be driven normally.

  In the above embodiment, the example in which the state (braking mode) of the hybrid vehicle V is switched between the first state and the second state by turning on and off the combination switch SW has been described. However, the braking force when the accelerator is off is large. It is only necessary to be able to switch between at least the first state and the second state that are different from each other. For example, the first and second states may be switched to a third, fourth state,... N-th state in which the magnitude of the regenerative braking force is different. Further, for example, by controlling the magnitude of the braking force by the exhaust brake according to the valve opening / closing amount of the exhaust brake device 33, it is possible to switch to the third state where the regenerative braking force is larger than the first state and smaller than the second state. It is good.

  In the above embodiment, the determination unit that determines whether or not the motor generator 41 can be regenerated and the control unit that controls the clutch 19 and the exhaust brake device 33 based on the determination result are configured as one unit (PHVECU50). However, the determination unit and the control unit may be configured as different units.

DESCRIPTION OF SYMBOLS 1 ... Brake system, 10 ... Drive system, 19 ... Clutch, 30 ... Engine, 31 ... Exhaust manifold, 33 ... Exhaust brake device, 40 ... High voltage system, 41 ... Motor generator, 43 ... Inverter, 45 ... Battery, 47 ... High voltage cable, 50 ... PHVECU (determination unit, control unit), 60 ... vehicle control ECU, 70 ... AMCUCU, 80 ... CCU, SW ... combination switch (operation unit), V ... hybrid vehicle, W ... wheel.

Claims (4)

A brake system for braking a hybrid vehicle comprising an engine having an exhaust brake device connected to a drive system via a clutch, and a motor generator connected to the drive system,
An operation unit for switching the state of the hybrid vehicle between at least a first state and a second state, which are different in magnitude of braking force applied when the accelerator is off;
A determination unit for determining whether the motor generator is capable of regenerative power generation; and
A control unit for controlling the clutch and the exhaust brake device based on a determination result of the determination unit;
The motor generator is
When the accelerator is off, a regenerative braking force corresponding to an engine brake of the engine is applied in the first state, and a regenerative braking force corresponding to an exhaust brake by the exhaust brake device is applied in the second state,
The controller is
When the determination unit determines that the motor generator is not capable of regenerative power generation, the regenerative braking force is not applied to the motor generator when the accelerator is off, and the engine brake is applied by connecting the clutch in the first state. In the second state, the clutch is connected and the exhaust brake device is operated to act on the exhaust brake. The determination unit
Calculate the regenerative request torque based on the running state of the hybrid vehicle, calculate the regenerative torque based on the charge state and allowable charge current of the battery that supplies power to the motor generator,
2. The brake system for a hybrid vehicle according to claim 1, wherein when the regenerative request torque is larger than the regenerative possible torque, the motor generator determines that the regenerative power generation is impossible. 3. The determination unit
An abnormality of the high voltage system based on an operating state of the high voltage system including the motor generator, a battery that supplies power to the motor generator, and an inverter electrically connected to the motor generator and the battery Detect
3. The brake system for a hybrid vehicle according to claim 1, wherein when the abnormality of the high voltage system is detected, the motor generator determines that the regenerative power generation is impossible. The hybrid vehicle includes, as a travel mode, an EV travel mode in which the engine is stopped and the motor generator is used as a drive power source, and an HV travel mode in which the engine and the motor generator are used as drive power sources,
The control unit, when the determination unit determines that the motor generator is not capable of regenerative power generation, starts the stopped engine when the hybrid vehicle is in the EV travel mode. The brake system of the hybrid vehicle of any one of 1-3.

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