Hybrid Vehicles

Abstract

To provide a hybrid vehicle that includes a clutch between an internal combustion engine and a motor and is capable of starting the internal combustion engine even when communication is interrupted between a control apparatus controlling the internal combustion engine and a control apparatus controlling the clutch.SOLUTION: When communication abnormality occurs between an engine ECU 80 and a clutch ECU 86, the engine ECU 80 controlling an engine 12 executes engagement control of a K0 clutch 28; and therefore, it is possible to appropriately start the engine 12 even when the communication with the clutch ECU 86 becomes difficult.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a hybrid vehicle that is provided with a clutch between an internal combustion engine and an electric motor. [Background technology]

[0002] A hybrid vehicle equipped with a clutch between an internal combustion engine and an electric motor has been proposed. Such a hybrid vehicle is described in Patent Document 1. Patent Document 1 describes that the hybrid vehicle is equipped with a control device that controls the internal combustion engine and a control device that controls the clutch, and that data is exchanged between the control devices via communication. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-168564 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in a hybrid vehicle having a clutch between an internal combustion engine and an electric motor as in Patent Document 1, when starting the internal combustion engine, the clutch is engaged and the internal combustion engine is cranked by the electric motor. However, if communication is interrupted between a control device that controls the internal combustion engine and a control device that controls the clutch, there is a risk that the internal combustion engine will not be able to be started properly.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a hybrid vehicle having a clutch between an internal combustion engine and an electric motor, in which the internal combustion engine can be started even if communication is interrupted between a control device that controls the internal combustion engine and a control device that controls the clutch. [Means for solving the problem]

[0006] The gist of the present invention is a hybrid vehicle comprising (a) an internal combustion engine, an electric motor, a clutch interposed between the internal combustion engine and the electric motor, a first control unit that controls the internal combustion engine, and a second control unit that controls the clutch, wherein when the internal combustion engine is started, the first control unit and the second control unit communicate with each other and cooperate to engage the clutch, and (b) when a communication abnormality occurs between the first control unit and the second control unit, the clutch engagement control that was previously performed by the first control unit and the second control unit in cooperation is performed by only the first control unit. Effect of the Invention

[0007] According to the present invention, if a communication abnormality occurs between the first control unit and the second control unit, the clutch engagement control is executed by the first control unit that controls the internal combustion engine, so that the internal combustion engine can be started properly even if communication with the second control unit becomes difficult.

[0008] Preferably, in the present invention, a starter for driving the internal combustion engine is provided, whereby the internal combustion engine can be started by the starter. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing an overall structure of a vehicle to which the present invention is applied; [Diagram 2] 2 is a functional block diagram illustrating the control functions of an engine ECU, a motor ECU, a hybrid ECU, and a clutch ECU that mainly control the drive system in a vehicle. [Diagram 3] FIG. 4 is a diagram showing an example of a time chart when engine start control is executed; [Figure 4] 5 is a flowchart illustrating a main part of the control operation of the electronic control device, that is, a control operation that can start the engine even if a communication abnormality occurs between the engine ECU and the clutch ECU. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. EXAMPLES

[0011] 1 is a diagram showing the overall structure of a vehicle 10 to which the present invention is applied. The vehicle 10 is a hybrid vehicle using an engine 12 and an electric motor MG as driving power sources. The vehicle 10 is configured to include the engine 12, the electric motor MG, a torque converter 14 with a lock-up clutch, an automatic transmission 16, a transfer 18, a front differential device 20, a pair of left and right front wheels 22, a rear differential device 24, and a pair of left and right rear wheels 26.

[0012] The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. An engine ECU 80 controls the output of the engine 12, and controls a throttle actuator, a fuel injection device, an ignition device, and the like provided in the vehicle 10, thereby controlling the engine torque Te of the engine 12. The engine 12 is also provided with a starter 38, which can start the engine 12.

[0013] The electric motor MG is a rotating electric machine having a function as a motor that generates mechanical power from electric power and a function as a generator that generates electric power from mechanical power, and is a so-called motor generator. The electric motor MG is connected to a battery unit 62 provided in the vehicle 10 via a power control unit 60 (hereinafter, PCU 60) provided in the vehicle 10. The electric motor MG controls the MG torque Tm, which is the torque of the electric motor MG, by controlling the PCU 60 by an electric motor ECU 82 that controls the output of the electric motor MG. For example, when the rotation direction of the electric motor MG is a positive rotation that is the same as the rotation direction when the engine 12 is operating, the MG torque Tm is a power running torque at the positive torque on the acceleration side, and a regenerative torque at the negative torque on the deceleration side. The electric motor MG generates power for traveling using electric power supplied from the battery unit 62 via the PCU 60 instead of or in addition to the engine 12. The electric motor MG also generates power using the power of the engine 12 and the driven force input from the wheel side. The electric power generated by the electric motor MG is stored in the battery unit 62 via the PCU 60. The battery unit 62 is an electric power storage device that supplies and receives electric power to and from the electric motor MG.

[0014] A K0 clutch 28 is interposed between the engine 12 and the electric motor MG. The K0 clutch 28 is a wet or dry friction engagement device constituted by a multi-plate or single-plate clutch pressed by a hydraulic actuator (not shown). The engine ECU 80 controls a K0 clutch solenoid 30 to drive a hydraulic actuator constituting the K0 clutch 28, thereby switching the control state of the K0 clutch 28 between an engaged state, a released state, and the like. The K0 clutch 28 corresponds to the clutch of the present invention.

[0015] When the K0 clutch 28 is in an engaged state, the engine 12 and the electric motor MG are connected to each other so that power can be transmitted. At this time, the power of the engine 12 can be transmitted to the front wheels 22 and the rear wheels 26. On the other hand, when the K0 clutch 28 is in a disengaged state, the power transmission between the engine 12 and the electric motor MG is interrupted. At this time, the power of the engine 12 is not transmitted to the front wheels 22 and the rear wheels 26. The K0 clutch 28 is a connecting / disconnecting clutch that connects the engine 12 and the electric motor MG when engaged and disconnects the connection between the engine 12 and the electric motor MG when disengaged. The torque converter 14 is a fluid-type power transmission device that transmits driving force from each of the driving force sources (engine 12, electric motor MG) to the automatic transmission 16 via a fluid.

[0016] The automatic transmission 16 is a known planetary gear type automatic transmission that includes, for example, one or more planetary gear devices and a plurality of engagement devices CB. Each engagement device CB is a hydraulic friction engagement device that is configured, for example, by a multi-plate or single-plate clutch or brake that is pressed by a hydraulic actuator. The engagement devices CB are switched between control states such as an engaged state and a released state by controlling a linear solenoid valve provided in a hydraulic control circuit 58 to adjust the hydraulic pressure of the hydraulic oil supplied to the hydraulic actuator that constitutes each engagement device CB.

[0017] The automatic transmission 16 is a stepped automatic transmission in which one of a plurality of gear stages (also called gear ratios) having different speed ratios (also called gear ratios) γat (=AT input rotation speed Ni / AT output rotation speed No) is formed by engaging one of the engagement devices CB. In other words, the automatic transmission 16 is shifted to a plurality of gear stages according to a combination of engagement and disengagement of the plurality of engagement devices CB.

[0018] The transfer 18 is a power distribution device that distributes the power transmitted from the output shaft 32 of the automatic transmission 16 to the front wheels 22 and the rear wheels 26. The transfer 18 is a known technology, so a detailed description thereof will be omitted.

[0019] The front differential 20 is connected to the transfer 18 via a front propeller shaft 34 so as to be capable of transmitting power. The front differential 20 is a differential device that transmits power from the transfer 18 to the pair of left and right front wheels 22 while allowing a difference in rotational speed between the pair of left and right front wheels 22. The front differential 20 is a known technology and therefore a detailed description thereof will be omitted.

[0020] The rear differential 24 is connected to the transfer 18 via a rear propeller shaft 36 so as to be capable of transmitting power. The rear differential 24 is a differential device that transmits power from the transfer 18 to the pair of left and right rear wheels 26 while allowing a rotational speed difference between the pair of left and right rear wheels 26. The rear differential 24 is a known technology and therefore a detailed description thereof will be omitted.

[0021] In the vehicle 10, when the K0 clutch 28 is engaged, the power output from the engine 12 is transmitted to the transfer 18 via the K0 clutch 28, the torque converter 14, and the automatic transmission 16. The power transmitted to the transfer 18 is distributed by the transfer 18 to the front wheels 22 and the rear wheels 26 at a predetermined distribution ratio and transmitted to the front wheels 22 and the rear wheels 26. The power output from the electric motor MG is transmitted to the transfer 18 via the torque converter 14 and the automatic transmission 16 regardless of the engagement state of the K0 clutch 28. The power transmitted to the transfer 18 is distributed by the transfer 18 to the front wheels 22 and the rear wheels 26 at a predetermined distribution ratio and transmitted to the front wheels 22 and the rear wheels 26.

[0022] The hydraulic pressure of the hydraulic oil supplied to the hydraulic actuator constituting the K0 clutch 28 and the hydraulic actuators constituting each engagement device CB of the automatic transmission 16 is generated by a mechanical oil pump MOP and an electric oil pump EOP. The mechanical oil pump MOP is connected to a pump impeller of the torque converter 14 via a belt or the like so as to be capable of transmitting power. Therefore, when at least one of the engine 12 and the electric motor MG is driven, the power of at least one of the engine 12 and the electric motor MG is transmitted to the mechanical oil pump MOP, thereby driving the mechanical oil pump MOP.

[0023] The electric oil pump EOP is driven by a pump motor (not shown). The electric oil pump EOP is driven when the hydraulic pressure is insufficient only with the hydraulic oil discharged from the mechanical oil pump MOP or when the mechanical oil pump MOP does not operate, such as when the vehicle is stopped. Here, a drive circuit for driving the electric oil pump EOP is provided in the clutch ECU 86 that controls the K0 clutch 28 and the like. Therefore, the electric oil pump EOP is driven based on a drive command signal Seop output from the clutch ECU 86.

[0024] The vehicle 10 is equipped with an electric power steering mechanism 42 that assists the driver in operating the steering wheel 40. The electric power steering mechanism 42 is equipped with an electric motor 42a. The electric motor 42a is controlled based on information such as the torque and rotation speed of the steering wheel 40 and the vehicle speed V. The electric motor 42a is controlled by a steering ECU 88.

[0025] The vehicle 10 is equipped with an accelerator pedal 46, a brake pedal 48, a shift operation device 50, and the like, which are operated by the driver.

[0026] The brake pedal 48 is mechanically connected to a hydraulic control unit 54 that controls the hydraulic pressure of the hydraulic oil supplied to the hydraulic brakes 52a to 52d provided on each wheel (the front wheels 22 and the rear wheels 26). The hydraulic control unit 54 is provided with a plurality of linear solenoid valves (not shown), and is configured to adjust the hydraulic pressure of the hydraulic oil supplied to each of the hydraulic brakes 52a to 52d by controlling the operating states of the plurality of linear solenoid valves. The hydraulic control unit 54 controls the operating states of the plurality of linear solenoid valves in coordination with the regenerative braking force of the electric motor MG so that a braking force desired by the driver based on the operation amount of the brake pedal 48 is obtained. The operating states of the linear solenoid valves provided in the hydraulic control unit 54 are controlled by a brake ECU 90.

[0027] The vehicle 10 includes a PCU 60 that controls the operation of the electric motor MG, and a battery unit 62 that supplies power to the PCU 60.

[0028] The PCU 60 includes an inverter unit 64 including a plurality of switching elements, and a DC-DC converter 66. The inverter unit 64 is configured to control each switching element based on a command from the motor ECU 82, thereby generating a driving torque or a regenerative torque in the motor MG. Three lines (Lu, Lv, Lw) connecting the inverter unit 64 and the motor MG correspond to wiring connected to a three-phase winding that constitutes the stator coil of the motor MG.

[0029] The DC-DC converter 66 steps down the high battery voltage output from the battery unit 62 and charges the auxiliary battery 68. The power charged in the auxiliary battery 68 is supplied to auxiliary devices such as the starter 38 for starting the engine, lamps, and audio equipment.

[0030] The battery unit 62 includes an HEV battery 70 and a system main relay (hereinafter, SMR 72) 72. The HEV battery 70 is composed of a chargeable and dischargeable secondary battery such as a lithium ion secondary battery or a nickel-metal hydride secondary battery, and is configured to be able to provide and receive power from the PCU 60. The SMR 72 connects and disconnects the HEV battery 72 and the PCU 60 in conjunction with the operation of a power switch that starts the vehicle 10. When the SMR 72 is connected, power can be provided and received between the HEV battery 72 and the PCU 60. When the SMR 72 is disconnected, power cannot be provided and received between the HEV battery 70 and the PCU 60.

[0031] In addition, HEV battery 70 is connected to electric air conditioner 74 via SMR 72. Electric air conditioner 74 is driven by power supplied from HEV battery 70. Electric air conditioner 74 is driven based on a drive command output from air conditioner ECU 92.

[0032] The vehicle 10 includes, as control devices for performing various controls of the vehicle 10, an engine ECU 80 for controlling the engine 12, an electric motor ECU 82 for controlling the electric motor MG, a hybrid ECU 84 for executing various controls of the hybrid system related to driving, a clutch ECU 86 for controlling the K0 clutch 28 and the automatic transmission 16, a steering ECU 88 for controlling the electric power steering mechanism 42, a brake ECU 90 for controlling the hydraulic control unit 54, an air conditioner ECU 92 for controlling the electric air conditioner 74, a battery ECU 94 for controlling the battery unit 62, and a meter ECU 96 for controlling the display of an in-vehicle display (not shown). The engine ECU 80 corresponds to a first control unit of the present invention, and the clutch ECU 86 corresponds to a second control unit of the present invention.

[0033] Each ECU is configured to include a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and the CPU executes various controls of the vehicle 10 by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. In addition, each ECU is capable of communicating with each other via a CAN (controller area network) communication line, etc.

[0034] In FIG. 1, each of the dashed lines extending from each ECU indicates an operation signal output from each ECU.

[0035] To the engine ECU 80, for example, a signal indicating an accelerator opening θacc which is the amount of operation of the accelerator pedal 46, a signal indicating a shift operation position Psh which is switched by the shift operation device 50, and the like are input. In addition, the engine ECU 80 outputs, for example, an engine control command signal Se to a throttle actuator, a fuel injection device, an ignition device, and the like provided in the engine 12, an electric fan drive command signal Sfan1 which drives an electric fan 100 disposed behind the radiator 76, an electric fan drive command signal Sfan2 which drives an electric fan 102 provided separately from the electric fan 100, and a starter drive command signal Sst which starts the engine 12 using the starter 38 under a predetermined condition.

[0036] From the electric motor ECU 82, for example, an MG control command signal Sm is output to the inverter unit 64 of the PCU 60 which controls the driving state of the electric motor MG.

[0037] The hybrid ECU 84 outputs, for example, a request signal to the motor ECU 82, which generates an output request value of the motor MG calculated based on signals from various sensors, a drive command signal Scon to the DCDC converter 66, a drive command signal Spump to the water pump 56 that cools the PCU 60, and a display command signal Smet to the meter ECU 96.

[0038] The clutch ECU 86 outputs, for example, a CB hydraulic control command signal Scb to a plurality of linear solenoid valves provided in the hydraulic control circuit 58 of the automatic transmission 16, a drive command signal Seop to the electric oil pump EOP, and the like.

[0039] The steering ECU 88 outputs, for example, a torque assist command signal Sast to the electric motor 42a of the electric power steering mechanism 42. The brake ECU 90 outputs, for example, a braking force control command signal Sbrk to the hydraulic control unit 54 for controlling the braking forces of the hydraulic brakes 52a to 52d. The battery ECU 94 outputs, for example, an electric fan drive command signal Sfan3 for driving the electric fan 104 attached to the battery unit 62.

[0040] 2 is a functional block diagram illustrating the control functions of the engine ECU 80, the electric motor ECU 82, the hybrid ECU 84, and the clutch ECU 86, which mainly control the drive system in the vehicle 10. The engine ECU 80, the electric motor ECU 82, the hybrid ECU 84, and the clutch ECU 86 are capable of communicating with each other, for example, via a CAN communication line. The engine ECU 80, the electric motor ECU 82, the hybrid ECU 84, and the clutch ECU 86 constitute an electronic control device 110 that executes various controls of the vehicle 10.

[0041] The electronic control device 110 receives various signals based on detection values ​​from various sensors provided in the vehicle 10 (for example, an engine rotation speed sensor 112, a turbine rotation speed sensor 114, an output rotation speed sensor 116, a MG rotation speed sensor 118, an accelerator opening sensor 120, a throttle opening sensor 124, a brake switch 128, a battery sensor 130, an oil temperature sensor 132, and a shift position sensor 136), and outputs various signals (for example, a crank angle θcr of the engine 12, an engine rotation speed Ne which is the rotation speed of the engine 12, a turbine rotation speed Nt which is the same value as an input rotation speed Ni of the automatic transmission 16, an output rotation speed No of the automatic transmission 16 corresponding to the vehicle speed V, an MG rotation speed N which is the rotation speed of the electric motor MG, and a vehicle speed V which is the rotation speed of the electric motor MG). m, accelerator opening θacc which is the amount of operation of accelerator pedal 46 by the driver which indicates the magnitude of the driver's acceleration operation, throttle opening θth which is the opening of the electronic throttle valve, brake on signal Bon which is a signal indicating the state in which brake pedal 48 for operating hydraulic brakes 52a to 52d (wheel brakes) is being operated by the driver, battery temperature THbat, battery charge / discharge current Ibat and battery voltage Vbat of HEV battery 70, hydraulic oil temperature THoil which is the temperature of hydraulic oil supplied to K0 clutch 28 and the hydraulic actuator of automatic transmission 16, and shift operation position Psh which is the operating position of shift operation device 50 by the driver.

[0042] The electronic control device 110 outputs various command signals (e.g., an engine control command signal Se for controlling the engine 12, an MG control command signal Sm for controlling the electric motor MG, a CB hydraulic control command signal Sbc for controlling the engagement device CB, a K0 hydraulic control command signal Sk0 for controlling the K0 clutch 28, a drive command signal Seop for controlling the EOP 60, etc.) to each device provided in the vehicle 10 (e.g., the engine 12 (electronic throttle valve, fuel injection device, ignition device, etc.), the PCU 60, the hydraulic control circuit 58, and the pump motor of the electric oil pump EOP).

[0043] Each hydraulic control command signal S will be described by taking the K0 hydraulic control command signal Sk0 as an example. The electronic control device 110 calculates a K0 hydraulic command value Spk0, which is a hydraulic command value for supplying the regulated K0 hydraulic pressure PRk0 from the hydraulic control circuit 58. The electronic control device 110 converts the K0 hydraulic command value Spk0 into a K0 command current value Sik0 for driving the K0 clutch solenoid 30 provided in the hydraulic control circuit 58. The K0 clutch solenoid 30 is a solenoid valve for the K0 clutch 28 that outputs the K0 hydraulic pressure PRk0. The K0 hydraulic control command signal Sk0 is a K0 drive current value Sik0d based on the K0 command current value Sik0 for the K0 clutch solenoid 30 by the K0 linear driver 138 provided in the engine ECU 80. The K0 linear driver 138 is a drive circuit for driving the K0 clutch solenoid 30.

[0044] The hybrid ECU 84 functionally includes a hybrid control unit 140 serving as hybrid control means for controlling the hybrid system based on signals from various sensors.

[0045] The hybrid control unit 140 calculates a total output demand value according to the driving state based on the driver's required driving force calculated based on signals from various sensors and the state of charge value SOC calculated from the battery temperature THbat, battery charge / discharge current Ibat, and battery voltage Vbat of the HEV battery 70. The hybrid control unit 140 also calculates output demand values ​​of the engine driving force and the MG driving force that realize the calculated total output demand value, and outputs demand signals of the respective output demand values ​​to the engine ECU 80 and the electric motor ECU 82.

[0046] Furthermore, when the total required output value can be realized only by the electric motor MG, the hybrid control unit 140 sets the driving mode to the motor driving (=BEV driving) mode. In the BEV driving mode, the hybrid control unit 140 performs BEV driving in which the vehicle runs using only the electric motor MG as a driving force source with the K0 clutch 28 in a released state. On the other hand, when the total required output value cannot be realized without using at least the output of the engine 12, the hybrid control unit 140 sets the driving mode to the engine driving mode, i.e., the hybrid driving (hereinafter, HEV driving) mode.

[0047] In the HEV driving mode, the hybrid control unit 140 performs engine driving, i.e., HEV driving, in which the vehicle runs using the engine 12 and the electric motor MG as driving power sources with the K0 clutch 28 engaged. On the other hand, even if the total output requirement value can be realized only by the output of the electric motor MG, the hybrid control unit 140 establishes the HEV driving mode when the state of charge value SOC of the HEV battery 70 is less than a predetermined engine start threshold value or when warming up of the engine 12 or the like is required. The engine start threshold value is a predetermined threshold value for determining that the state of charge value SOC is such that the engine 12 needs to be forcibly started to charge the HEV battery 70. In this way, the hybrid control unit 140 automatically stops the engine 12 during HEV driving, restarts the engine 12 after the engine stop, or starts the engine 12 during BEV driving, depending on the driving state of the vehicle 10, thereby appropriately switching between the BEV driving mode and the HEV driving mode.

[0048] The engine ECU 80 functionally includes an engine control unit 142 as an engine output control means for controlling the output of the engine 12. The engine control unit 142 executes engine control such as throttle opening control, fuel injection control, and ignition timing control in accordance with an output requirement value of the engine 12 transmitted from the hybrid control unit 140 so that the output requirement value is realized.

[0049] The motor ECU 82 functionally includes a motor control unit 144 as a motor control means for controlling the motor MG. The motor control unit 144 controls the PCU 60 to control the output of the motor MG according to a required output value of the MG driving force of the motor MG transmitted from the hybrid control unit 140, so that the required output value is realized.

[0050] The hybrid control unit 140 determines whether there is an engine start request to switch the control state of the engine 12 from a stopped state to an operating state. For example, the hybrid control unit 140 determines whether there is an engine start request based on whether, during the BEV driving mode, the output requirement value has increased beyond a range that can be achieved only by the output of the electric motor MG, whether warming up of the engine 12, etc. is necessary, or whether the state of charge value SOC of the HEV battery 70 has fallen below a predetermined engine start threshold value.

[0051] The clutch ECU 86 functionally includes a clutch control unit 146 as a clutch control means for controlling the K0 clutch 28. When the hybrid control unit 140 determines that there is an engine start request, the clutch control unit 146 controls the K0 clutch 28 to execute start control of the engine 12. For example, the clutch control unit 146 calculates a K0 command current value Sik0 for controlling the K0 clutch 28 in the released state toward the engaged state so as to obtain a K0 torque Tk0 for transmitting the cranking torque Tcr to the engine 12 side. That is, when starting the engine 12, the clutch control unit 146 calculates a starting K0 command current value Sik0 as a starting command value for adjusting the K0 hydraulic pressure PRk0 so as to switch the control state of the K0 clutch 28 from the released state to the engaged state. The cranking torque Tcr is a torque required for cranking the engine 12 to increase the engine rotation speed Ne.

[0052] When the hybrid control unit 140 determines that there is an engine start request, it controls the engine 12 and the electric motor MG to execute start control of the engine 12. For example, when starting the engine 12, the engine control unit 142 outputs a K0 drive current value Sik0d as a start-time drive command value for driving the hydraulic control circuit 58, i.e., the K0 clutch solenoid 30, based on the engine start K0 command current value Sik0 transmitted from the clutch control unit 146. The electric motor control unit 144 outputs an MG control command signal Sm to the PCU 60 for the electric motor MG to output the cranking torque Tcr in accordance with the switching of the K0 clutch 28 to the engaged state. That is, when starting the engine 12, the electric motor control unit 144 outputs an MG control command signal Sm to the PCU 60 for controlling the electric motor MG to output the cranking torque Tcr, i.e., to increase the MG torque Tm by the cranking torque Tcr.

[0053] Furthermore, the engine control unit 142 outputs an engine control command signal Se to a fuel injection device or the like (fuel injection device, ignition device, etc.) for starting fuel supply, engine ignition, etc., in conjunction with cranking of the engine 12. That is, when starting the engine 12, the engine control unit 142 outputs an engine control command signal Se to the fuel injection device or the like for controlling the engine 12 so that the engine 12 starts operating in conjunction with switching the K0 clutch 28 to an engaged state, that is, cranking of the engine 12. The engine control unit 142 outputs an engine control command signal Se to the fuel injection device or the like for outputting an engine torque Te so that the engine 12 reaches a stable state of independent rotation due to the explosion of the engine 12 after the initial explosion when ignition of the engine 12 is started, that is, a state in which the engine 12 reaches a complete explosion state.

[0054] When cranking the engine 12, a reaction torque occurs due to the engagement of the K0 clutch 28. During BEV driving, this reaction torque causes a drop in the drive torque Tr due to the inertia of the engine 12 during engine start. Therefore, the MG torque Tm that is increased toward the cranking torque Tcr when starting the engine 12 is an MG torque Tm for canceling this reaction torque, and is an MG torque Tm for compensating for this reaction torque, that is, an MG torque Tm for reaction compensation. The cranking torque Tcr is the K0 torque Tk0 required for cranking the engine 12, and is the MG torque Tm required for cranking the engine 12 that flows from the electric motor MG side to the engine 12 side via the K0 clutch 28. The cranking torque Tcr is, for example, a constant torque that is determined in advance based on, for example, the specifications of the engine 12, the starting method of the engine 12, and the like.

[0055] After the initial explosion of the engine 12, the electric motor control unit 144 outputs an MG control command signal Sm to the PCU 60 to stop the output of the cranking torque Tcr by the electric motor MG, and ends the cranking of the engine 12. After the cranking of the engine 12 is ended, the clutch control unit 146 outputs a K0 command current value Sik0 for waiting for the switching of the K0 clutch 28 to the engaged state so that the K0 torque Tk0 is lowered below the cranking torque Tcr and maintained at a predetermined torque Tk0f. The predetermined torque Tk0f is a predetermined K0 torque Tk0 smaller than the cranking torque Tcr so as not to become a disturbance to the complete explosion of the engine 12 after the end of cranking. Not becoming a disturbance to the complete explosion of the engine 12 means not hindering the independent rotation of the engine 12 after the initial explosion of the engine 12. From another perspective, when the engine rotation speed Ne is increased by the self-rotating engine 12 after ignition, if the K0 clutch 28 has a K0 torque Tk0 equivalent to the cranking torque Tcr, for example, starting shock may increase due to the influence of the inertia of the electric motor MG and the like downstream of the K0 clutch 28. The specified torque Tk0f is a predetermined K0 torque Tk0 smaller than the cranking torque Tcr in order to reduce the starting shock when the engine rotation speed Ne is increased by the self-rotating engine 12 after cranking of the engine 12 is completed.

[0056] The clutch control unit 146 outputs a K0 command current value Sik0 for controlling the K0 clutch 28 toward an engaged state so as to obtain a synchronizing K0 torque Tk0syc for synchronizing the input rotation speed and output rotation speed of the K0 clutch 28 after the engine 12 has completely exploded. The input rotation speed of the K0 clutch 28 is equal to the engine rotation speed Ne. The output rotation speed of the K0 clutch 28 is equal to the MG rotation speed Nm. In other words, synchronizing the input rotation speed and output rotation speed of the K0 clutch 28 is equivalent to synchronizing the engine rotation speed Ne and the MG rotation speed Nm.

[0057] FIG. 3 is a diagram showing an example of a time chart when the start control of the engine 12 is executed. In FIG. 3, time t1 indicates a time when the start control of the engine 12 is started by determining that there is an engine start request accompanying the driver's further depression of the accelerator pedal 46 during, for example, BEV driving. After the start control of the engine 12 is started, packing control of the K0 clutch 28, i.e., K0 packing control, is executed (see time t1-time t2). The K0 packing control is a control for packing the K0 clutch 28 so that the pack clearance in the friction plates of the K0 clutch 28 is reduced. In the K0 packing control, first, a quick apply (=QA) is executed (see part a) that outputs a temporarily high K0 drive current value Sik0d in order to improve the initial responsiveness of the K0 hydraulic pressure PRk0, and then a constant pressure standby for packing is executed (see part b) in order to complete the packing of the K0 clutch 28. In the dashed line during constant pressure standby for packing, a K0 drive current value Sik0d is output to set the constant pack pressure PRk0pk, which is the K0 oil pressure PRk0 for maintaining the K0 clutch 28 in a packing completion state. In the solid line during constant pressure standby for packing, a K0 drive current value Sik0d is output to set the total K0 oil pressure PRk0, which is the pack pressure PRk0pk plus the K0 oil pressure PRk0 equivalent to the cranking torque Tcr. The K0 drive current value Sik0d shown in the dashed line and the K0 drive current value Sik0d shown in the solid line actually have different periods of K0 packing control, but for convenience in FIG. 2 they are shown to be the same length.

[0058] After the K0 packing control is completed, in order to crank the engine 12, cranking is performed by the K0 clutch 28 that transmits the cranking torque Tcr to the engine 12, that is, K0 cranking is performed (see time t2-t3). The K0 drive current value Sik0d during K0 cranking is the K0 drive current value Sik0d for realizing the total K0 oil pressure PRk0 obtained by adding the K0 oil pressure PRk0 equivalent to the cranking torque Tcr to the pack pressure PRk0pk, and is the K0 drive current value Sik0d for adjusting the K0 oil pressure PRk0 so that the K0 clutch 28 transmits the cranking torque Tcr. During K0 cranking, the MG torque Tm of a magnitude equivalent to the cranking torque Tcr, that is, the MG torque Tm for reaction force compensation, is output from the electric motor MG. During K0 cranking, when the engine speed Ne is increased, engine ignition and the like are started and the engine 12 is first fired.

[0059] After the end of K0 cranking, in order to wait for the K0 clutch 28 to be switched to the engaged state, a constant pressure standby after cranking is executed (see time t3-t4) in which the K0 torque Tk0 is lowered below the cranking torque Tcr and maintained at a predetermined torque Tk0f. The K0 drive current value Sik0d during the constant pressure standby after cranking is, for example, the same as or greater than the value for maintaining the K0 clutch 28 in the packing completion state, and is the K0 drive current value Sik0d for realizing the K0 torque Tk0 that does not disturb the complete explosion of the engine 12, and is the K0 drive current value Sik0d for adjusting the K0 hydraulic pressure PRk0 so that the K0 torque Tk0 is lowered below the cranking torque Tcr and temporarily maintained at the predetermined torque Tk0f. During the execution of the constant pressure standby after cranking, the engine rotation speed Ne is increased not by the K0 torque Tk0 but solely by the combustion torque of the engine 12. In this embodiment, prior to execution of constant pressure standby after cranking, a quick drain (=QD) is executed to temporarily output a low K0 drive current value Sik0d in order to improve the initial responsiveness of the K0 oil pressure PRk0 (see part c).

[0060] During execution of the constant pressure standby after cranking, when the self-sustaining rotation due to the explosion of the engine 12 becomes stable, that is, when the engine 12 becomes in a state of complete explosion, the rotation synchronization control between the engine 12 and the electric motor MG, that is, the synchronization control by the K0 clutch 28 that synchronizes the engine rotation speed Ne and the MG rotation speed Nm, that is, the K0 synchronization control, is executed (see time t4 and after). The complete explosion of the engine 12 is determined, for example, when a complete explosion notification is output from the engine control unit 142. The complete explosion notification of the engine 12 is output by the engine control unit 142, for example, when the elapsed time from the time when the engine rotation speed Ne reaches a predetermined complete explosion rotation speed of the engine 12 exceeds a predetermined complete explosion notification waiting time. This complete explosion notification waiting time is predetermined, for example, taking into consideration the exhaust gas requirements of the engine 12. After the input rotation speed and the output rotation speed of the K0 clutch 28 are synchronized, i.e., K0 synchronization is completed, in other words, after the K0 clutch 28 is switched to the engaged state, i.e., K0 engagement is completed, K0 full engagement control is executed to transition the K0 clutch 28 to a fully engaged state. After the K0 clutch 28 is brought into the fully engaged state by the K0 full engagement control, the start control of the engine 12 is completed (see time t5), and the fully engaged state of the K0 clutch 28 is maintained (see time t5 and after).

[0061] The clutch control unit 146 calculates the K0 hydraulic pressure command value Spk0 according to the K0 control phase of the K0 clutch 28 during the above-mentioned starting transition period of the engine 12. The K0 control phase is a plurality of progress stages divided according to the control state of the K0 clutch 28 that is switched during the starting transition period of the engine 12. Referring to Fig. 3, the K0 control phase is defined as, for example, a QA phase, a constant pressure standby phase for packing, a K0 cranking phase, a QD phase, a constant pressure standby phase after cranking, a K0 full engagement phase, etc.

[0062] Various signals are transmitted between the engine control unit 142 and the clutch control unit 146 via, for example, a CAN communication system. The K0 command pressure current value Sik0 transmitted from the clutch control unit 146 to the engine control unit 142 is output from the K0 linear driver 138 to the K0 clutch solenoid 30 of the hydraulic control circuit 58 as a K0 drive current value Sik0d.

[0063] When starting the engine 12, first, an engine start request output from the engine control unit 142 (engine ECU 80) is received by the clutch control unit 146 via the CAN communication line. After receiving the engine start request, the clutch control unit 146 starts outputting the K0 command current value Sik0 in the QA phase. The K0 command current value Sik0 is transmitted to the engine control unit 142, and the engine control unit 142 outputs a K0 drive current value Sik0d based on the K0 command current value Sik0.

[0064] In addition, when the control of the K0 clutch 28 progresses and engine ignition etc. is started in conjunction with K0 cranking, the QD phase and the constant pressure waiting phase after cranking are executed to temporarily reduce the K0 torque Tk0 so as not to disturb the independent operation of the engine 12. Therefore, after the start of engine ignition etc., the engine control unit 142 makes a K0 release permission determination to end the K0 cranking phase and determine a transition to the QD phase, and the K0 release permission flag is turned on. The on information of the K0 release permission flag transmitted from the engine control unit 142 is received by the clutch control unit 146. After receiving the on information of the K0 release permission flag, the clutch control unit 146 starts outputting the K0 command current value Sik0 in the QD phase. The K0 command current value Sik0 in the QD phase is transmitted to the engine control unit 142, and the engine control unit 142 outputs the K0 drive current value Sik0d in the QD phase based on the K0 command current value Sik0 in the QD phase. In this way, when the engine control unit 142 permits a transition to a predetermined next K0 control phase in a predetermined K0 control phase, it outputs the K0 drive current value Sik0d at engine start based on the K0 command current value Sik0 for engine start in the predetermined next K0 control phase that is subsequently transmitted from the clutch control unit 146.

[0065] As described above, the drive circuit (K0 linear driver 138) for the K0 clutch 28 that controls the K0 clutch 28 is present within the engine ECU 80, and when the engine is started, communication is performed between the engine ECU 80 (engine control unit 142) and the clutch ECU 86 (clutch control unit 146), and these are configured to cooperate to engage the K0 clutch 28.

[0066] Incidentally, if it is determined that there is a request to start the engine 12 when the electric motor MG fails, the engine is started by the starter 38 provided in the engine 12. On the other hand, if a communication abnormality occurs between the engine ECU 80 and the clutch ECU 86, making communication with the clutch ECU 86 difficult, the function of cooperatively controlling the K0 oil pressure PRk0 of the K0 clutch 28 at engine start is lost. In addition, since a drive circuit for driving the electric oil pump EOP is provided in the clutch ECU 86, if a communication abnormality occurs, the electric oil pump EOP cannot generate oil pressure. As a result, it becomes difficult to start the engine 12.

[0067] In response to this, the engine ECU 80 is functionally provided with an abnormality engine starting unit 150 as an abnormality engine starting means that starts the engine 12 in a method different from that used in normal operation when it determines that communication with the clutch ECU 86 has been interrupted in starting the engine 12. The engine ECU 80 is also functionally provided with a communication abnormality determination unit 148 that determines whether a communication abnormality with the clutch ECU 86 has occurred.

[0068] The communication abnormality determination unit 148 determines that a communication abnormality has occurred in the clutch ECU 86, for example, if there is no response signal from the clutch ECU 86 to the engine ECU 80 in response to a signal output from the engine ECU 80, or if the time required to receive a response signal from the clutch ECU 86 based on the time when the engine ECU 80 output a signal to the clutch ECU 86 exceeds a predetermined time.

[0069] When a communication abnormality of the clutch ECU 86 is determined, the engine starting unit 150 under abnormality executes starting of the engine 12 in a method different from that under normal circumstances. When a communication abnormality is determined, the engine starting unit 150 under abnormality determines whether the vehicle 10 is currently before start-up and the driver has pressed a power switch to start the vehicle 10, or whether the vehicle 10 is currently running in BEV mode using the electric motor MG. In other words, when starting the engine 12, the engine starting unit 150 under abnormality determines whether the vehicle 10 is currently before start-up or after start-up of the vehicle 10 (BEV running).

[0070] When the power switch of the vehicle 10 is pressed by the driver before the vehicle 10 is started, the abnormality engine starting unit 150 switches to engine starting by the starter 38. When the power switch of the vehicle 10 is pressed, the abnormality engine starting unit 150 drives the starter 38 to crank the engine 12. Furthermore, while the engine ECU 80 and the clutch ECU 86 cooperate to control the K0 clutch 28 under normal conditions, when a communication abnormality in the clutch ECU 86 is determined, engagement control of the K0 clutch 28 is executed only by the engine ECU 80.

[0071] The abnormality engine starting unit 150 stores a map (relationship) of the K0 hydraulic command value Spk0 of the K0 clutch 28 against elapsed time, which is applied when a communication abnormality is determined, and outputs the K0 drive current value Sik0d corresponding to the K0 hydraulic command value Spk0 based on this map from the K0 linear driver 138. Here, in the normal state, the engine ECU 80 and the clutch ECU 86 control in cooperation with each other, so that the K0 hydraulic command value Spk0 becomes a precise value according to the K0 control phase, but the K0 hydraulic command value Spk0 when a communication abnormality is determined is specified by a relatively simple logic such as sweeping up with the passage of time, so that shocks are more likely to occur than in the normal state, and drivability is inferior to that in the normal state. However, since the engagement control of the K0 clutch 28 is possible only by the engine ECU 80, the engagement of the K0 clutch 28 is possible even if a communication abnormality occurs.

[0072] As in the normal state, when starting the engine 12, the abnormality engine starting unit 150 outputs an engine control command signal Se to the fuel injection device and the like for controlling the engine 12 so that the engine 12 starts operating in conjunction with switching the K0 clutch 28 to the engaged state, i.e., cranking of the engine 12. The abnormality engine starting unit 150 also outputs an engine control command signal Se to the fuel injection device and the like for outputting an engine torque Te so that the engine 12 reaches a stable state of independent rotation due to the explosion after the initial explosion when ignition of the engine 12 is started, i.e., a state in which the engine 12 reaches a complete explosion state.

[0073] In addition, when the vehicle 10 is started, the mechanical oil pump MOP is not driven, so that it is necessary to drive the electric oil pump EOP and generate hydraulic pressure for executing the engagement control of the K0 clutch 28. However, when a communication abnormality occurs in the clutch ECU 86, it becomes difficult for the engine ECU 80 to output a command to drive the electric oil pump EOP to the clutch ECU 86. In response to this, the abnormality-time engine starting unit 150 drives the electric motor MG when a communication abnormality in the clutch ECU 86 is determined. The abnormality-time engine starting unit 150 outputs a command to drive the electric motor MG to the electric motor control unit 144. The electric motor control unit 144 drives the electric motor MG upon receiving a command from the abnormality-time engine starting unit 150. When the electric motor MG is driven, the pump impeller of the torque converter 14 is rotated, and the mechanical oil pump MOP, which is connected to the pump impeller so as to be capable of transmitting power, is driven. As a result, hydraulic oil is discharged from the mechanical oil pump MOP, and the hydraulic pressure required for the engagement control of the K0 clutch 28 is secured. In addition, when ensuring the oil pressure, the abnormality-time engine starting unit 150 outputs a drive command to the electric oil pump EOP in addition to driving the electric motor MG. In this way, when the electric motor MG fails, the oil pressure is ensured by driving the electric oil pump EOP, and when a communication abnormality occurs in the clutch ECU 86, the oil pressure is ensured by the electric motor MG, making it possible to start the engine 12 by the starter 38.

[0074] Next, engine starting during EV driving will be described. When starting the engine 12, if the vehicle 10 is in BEV driving when the communication abnormality of the clutch ECU 86 is determined, the abnormality engine starting unit 150 switches to control of the K0 clutch 28 by the engine ECU 80 alone, as in the case of starting the vehicle 10. The abnormality engine starting unit 150 stores a map (relationship) of the K0 hydraulic pressure command value Spk0 of the K0 clutch 28 for BEV driving, which is applied when the communication abnormality is determined, and outputs the K0 drive current value Sik0d corresponding to the K0 hydraulic pressure command value Spk0 based on this map from the K0 linear driver 138. Since the electric motor MG rotates during BEV driving, the rotation of the engine 12 is increased by forcibly engaging the K0 clutch 28 without using the starter 38 (push start). Since the electric motor MG is driven during BEV driving, the hydraulic pressure is ensured by the mechanical oil pump MOP.

[0075] Similarly to normal operation, the abnormal-time engine starting unit 150 outputs an engine control command signal Se to the fuel injection device and the like for controlling the engine 12 so that the engine 12 starts operating in conjunction with switching the K0 clutch 28 to the engaged state, i.e., cranking of the engine 12, when starting the engine 12. The abnormal-time engine starting unit 150 also outputs an engine control command signal Se to the fuel injection device and the like for outputting an engine torque Te so that the engine 12 reaches a stable state of independent rotation due to the explosion after the initial explosion when ignition of the engine 12 is started, i.e., a state in which the engine 12 reaches a complete explosion state.

[0076] 4 is a flowchart illustrating the main part of the control operation of the electronic control device 110, that is, the control operation that can start the engine 12 even if a communication abnormality occurs between the engine ECU 80 and the clutch ECU 86. This flowchart is executed every time a request to start the engine 12 is output.

[0077] First, in step S10 (hereinafter, step will be omitted) corresponding to the control function of the communication abnormality determination unit 148, it is determined whether or not a communication abnormality has occurred in the clutch ECU 86. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, it is determined in S20 corresponding to the control function of the abnormality-time engine starting unit 150 whether or not the power switch of the vehicle 10 has been pressed by the driver before the vehicle 10 is started.

[0078] If the determination in S20 is positive, in S30 corresponding to the control function of the engine starting unit 150 in an abnormality, the engagement control of the K0 clutch 28 is switched to control by the engine ECU 80 alone. In addition, the cranking of the engine 12 is switched to cranking using the starter 38. Furthermore, the hydraulic pressure of the hydraulic oil required for engaging the K0 clutch 28 is ensured by driving the electric motor MG and driving the mechanical oil pump MOP. Next, in S40 corresponding to the control function of the engine starting unit 150 in an abnormality, the fuel injection device and the like are operated so that the engine 12 starts operating in conjunction with the cranking of the engine 12, and the fuel injection device and the like are operated so that the independent rotation of the engine 12 becomes stable (complete combustion state) after the initial explosion of the engine 12. As a result, the engine 12 is switched to the complete explosion state, and the engagement of the K0 clutch 28 is completed (ReadyON).

[0079] If the determination in S20 is negative, then in S50, which corresponds to the control function of the engine starting unit 150 in an abnormality, it is determined whether or not the vehicle is in BEV driving mode. If the determination in S50 is negative, this routine is terminated. If the determination in S50 is positive, then in S60, which corresponds to the control function of the engine starting unit 150 in an abnormality, the engagement control of the K0 clutch 28 is switched to control by the engine ECU 80 alone. During BEV driving, the rotation of the engine 12 is increased by forcibly engaging the K0 clutch 28 without using the starter 38. In addition, since the mechanical oil pump MOP is driven in conjunction with the driving of the electric motor MG, it is not necessary to ensure the hydraulic pressure required for the engagement control to engage the K0 clutch 28. Next, in S70 corresponding to the control function of the abnormality-time engine starting unit 150, the fuel injection device and the like are operated in conjunction with the increase in the engine speed Ne accompanying the engagement of the K0 clutch 28 so that the engine 12 starts operating, and the fuel injection device and the like are operated so that the engine 12 reaches a stable state of independent rotation (complete combustion state) after the initial explosion of the engine 12. As a result, the engine 12 is switched to the complete explosion state, and the engagement of the K0 clutch 28 is completed (HEV transition completion). As described above, when a communication abnormality occurs in the clutch ECU 86, regardless of whether it is before or after the start of the vehicle 10, the engine 12 can be started, and running as a fail-safe is possible.

[0080] As described above, according to this embodiment, if a communication abnormality occurs between the engine ECU 80 and the clutch ECU 86, instead of the engagement control of the K0 clutch 28 being performed in coordination between the engine ECU 80 and the clutch ECU 86, the engagement control of the K0 clutch 28 is performed solely by the engine ECU 80 which controls the engine 12. Therefore, even if communication with the clutch ECU 86 becomes difficult, the engine 12 can be started properly.

[0081] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

[0082] For example, in the above-described embodiment, the engine ECU 80 and the clutch ECU 86 exist as separate ECUs and are configured to be able to communicate with each other via a CAN communication line, but the engine ECU 80 and the clutch ECU 86 may be provided in the same ECU and be configured to be able to communicate with each other within the same ECU.

[0083] In addition, in the above-described embodiment, the clutch ECU 86 is provided with a drive circuit for driving the electric oil pump EOP, but the drive circuit for the electric oil pump EOP may be provided in the engine ECU 80 or another ECU.

[0084] In the above embodiment, a planetary gear type automatic transmission is exemplified as the automatic transmission 16, but the present invention is not limited to this. The automatic transmission 16 may be a synchronous mesh type parallel two-shaft automatic transmission including a known DCT (Dual Clutch Transmission). In short, the present invention can be applied to any vehicle that includes an engine and a clutch provided between the engine and the drive wheels.

[0085] In the above embodiment, the torque converter 14 is used as the fluid transmission device, but the present invention is not limited to this. For example, instead of the torque converter 14, other fluid transmission devices that do not have a torque amplifying effect, such as a fluid coupling, may be used as the fluid transmission device. Alternatively, the fluid transmission device does not necessarily have to be provided, and may be replaced with, for example, a starting clutch.

[0086] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0087] 10: Vehicles (hybrid vehicles) 12: Engine (internal combustion engine) 28:K0 Clutch (Clutch) 80: Engine ECU (first control unit) 86: Clutch ECU (second control unit) MG: Electric motor

Claims

[Claim 1] A hybrid vehicle comprising an internal combustion engine, an electric motor, a clutch interposed between the internal combustion engine and the electric motor, a first control unit that controls the internal combustion engine, and a second control unit that controls the clutch, wherein, when the internal combustion engine is started, the first control unit and the second control unit communicate with each other and cooperate to engage the clutch, When a communication error occurs between the first control unit and the second control unit, the clutch engagement control that has been executed by the first control unit and the second control unit in cooperation with each other is executed only by the first control unit. A hybrid vehicle characterized by

Images