Vehicle control device

Abstract

To provide a control device which can surely perform discharge control of a capacitor in the vehicle collision in a vehicle having a fluid type transmission device between a motor and drive wheels.SOLUTION: When the collision of a vehicle 10 is detected, as a discharge control unit 132 executes discharge control under such a condition that a motor MG stops rotating and the turbine rotational speed Nt of a turbine rotor 22b of a torque converter 22 is reduced to a level equal to or less than a prescribed rotation speed Nts, the turbine rotational speed Nt of the turbine rotor 22b is reduced and three-phase on control is continued until the motor MG no longer rotates, and thereby the discharge control unit can surely execute discharge control in a state where the motor MG stops rotating.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a vehicle that uses at least an electric motor as a driving force source. [Background technology]

[0002] Vehicles that use at least an electric motor as a driving force source are well known. For example, there is an electric vehicle described in Patent Document 1. Patent Document 1 describes that when a collision of the vehicle is detected, the clutch is released to release the connection between the electric motor and the drive shaft, three-phase ON control of the electric motor is performed to stop the rotation of the electric motor, and then a capacitor discharge control is performed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-123226 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case of a vehicle equipped with a fluid transmission between the electric motor and the drive wheels, if the drive wheels are rotating even when the rotation speed of the electric motor becomes zero due to the three-phase ON control, the fluid transmission may be dragged by the drive wheels to rotate, and the electric motor may be rotated again by being pulled by the fluid transmission. As a result, the electric motor may rotate again after the three-phase ON control is completed, which may make it impossible to control the discharge of the capacitor.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a control device that can reliably control the discharge of a capacitor in the event of a vehicle collision in a vehicle equipped with a fluid transmission device between an electric motor and drive wheels. [Means for solving the problem]

[0006] The gist of the first invention is (a) a vehicle control device that is applied to a vehicle having a driving force source including at least an electric motor and a fluid-type transmission device provided in a power transmission path between the electric motor and a drive wheel, and that includes a control unit that generates a torque in a direction to stop the rotation of the electric motor when a vehicle collision is detected, and executes discharge control to discharge an electric charge of a capacitor provided in parallel to an inverter that controls the electric motor when the rotation of the electric motor stops, and (b) the control unit executes the discharge control on the condition that the rotational speed of a turbine of the fluid-type transmission device has decreased to a predetermined rotational speed.

[0007] The gist of the second invention is that in the first invention, an engine is connected to the electric motor via a clutch so as to be able to transmit power, and the control unit releases the clutch when a vehicle collision is detected.

[0008] The gist of the third invention is that in the first or second invention, the control unit determines whether the motor has stopped rotating based on the current value of the stator coil of the motor during a transition period when the motor stops rotating.

[0009] The gist of the fourth invention is that in the vehicle control device described in any one of the first to third inventions, the vehicle further includes a hydraulic friction clutch provided in a power transmission path between the fluid transmission device and the drive wheels for connecting and disconnecting the power transmission path. Effect of the Invention

[0010] In a vehicle equipped with a fluid transmission in the power transmission path between the electric motor and the drive wheels of the first invention, when the drive wheels rotate after a vehicle collision, the rotation of the drive wheels is transmitted to the fluid transmission, and the electric motor rotates in conjunction with the fluid transmission, which may make it impossible to perform discharge control. In contrast, according to the first invention, discharge control is performed on the condition that the rotation speed of the turbine of the fluid transmission has dropped below a predetermined rotation speed, so that discharge control can be reliably performed with the electric motor stopped rotating.

[0011] According to the second invention, in a vehicle in which an engine is connected to an electric motor via a clutch so that power can be transmitted, the clutch is released when a vehicle collision is detected, thereby preventing the electric motor from rotating together with the engine after a vehicle collision.

[0012] According to the third aspect of the present invention, whether or not the motor has stopped rotating is determined based on the current value of the stator coil of the motor during the transitional period when the motor is stopping its rotation. Therefore, even if the sensor that detects the rotational speed of the motor fails due to a vehicle collision, it is possible to determine whether or not the motor has stopped rotating.

[0013] According to the fourth aspect of the present invention, by further providing a hydraulic friction clutch that disconnects the power transmission path between the fluid transmission and the drive wheels, when the friction clutch is released in the event of a vehicle collision, the rotation of the drive wheels is not transmitted to the turbine side, but if there is a delay in releasing the friction clutch due to residual pressure in the hydraulic actuator of the friction clutch, when the drive wheels rotate after the vehicle collision, the rotation is transmitted to the fluid transmission via the friction clutch to rotate the electric motor. On the other hand, the discharge control is executed on the condition that the rotation speed of the turbine of the fluid transmission falls below a predetermined rotation speed, so that the discharge control can be executed reliably in a state where the rotation of the drive wheels is no longer transmitted to the electric motor side. [Brief description of the drawings]

[0014] [Figure 1]1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and control systems for various controls in the vehicle. [Diagram 2] 4 is a flowchart illustrating a main part of the control operation of the electronic control device, specifically, a flowchart illustrating the control operation related to discharge control when the vehicle collides while traveling. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 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

[0016] FIG. 1 is a diagram for explaining a schematic configuration of a vehicle 10 to which the present invention is applied, and is also a diagram for explaining main parts of control functions and a control system for various controls in the vehicle 10. The vehicle 10 shown in FIG. 1 is a hybrid vehicle equipped with an engine 12 and an electric motor MG, which are driving force sources for traveling. The vehicle 10 also includes a vehicle drive device 16 (hereinafter, drive device 16) that transmits the power of the engine 12 and the electric motor MG to drive wheels 14. The drive device 16 includes, in a case 18, the engine 12 and the electric motor MG, which are driving force sources, a K0 clutch 20, a torque converter 22, an automatic transmission 24, and the like. The torque converter 22 corresponds to the fluid-type transmission of the present invention.

[0017] The engine 12 is a known internal combustion engine such as a gasoline engine, a diesel engine, etc. An engine control device 50 including a throttle actuator, a fuel injection device, an ignition device, etc., provided in the vehicle 10 is controlled by an electronic control device 90 described later, whereby an engine torque Te, which is an output torque of the engine 12, is controlled.

[0018] 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 electric motor generator. The electric motor MG is connected to a high-voltage battery 64, which is a high-voltage battery provided in the vehicle 10, via an inverter 62 provided in the vehicle 10. The electric motor MG controls the inverter 62 by an electronic control device 90 described later, thereby controlling the MG torque Tm, which is the output torque 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 powering torque at the positive torque on the acceleration side, and a regenerative torque at the negative torque on the deceleration side. Specifically, the electric motor MG generates power for traveling by electric power supplied from the high-voltage battery 64 via the inverter 62 instead of or in addition to the engine 12. The electric motor MG also generates power by the power of the engine 12 or the driven force input from the drive wheels 14 side. Electric power generated by the electric motor MG is supplied to a high-voltage battery 64 via an inverter 62. The high-voltage battery 64 is a high-voltage storage device (high-voltage battery) that supplies electric power to the electric motor MG. The electric power also means electrical energy unless otherwise specified. The motive power also means torque or force unless otherwise specified.

[0019] The K0 clutch 20 is a clutch provided between the engine 12 and the electric motor MG in a power transmission path between the engine 12 and the drive wheels 14. That is, the engine 12 is connected to the electric motor MG via the K0 clutch 20 so as to be capable of transmitting power. The torque converter 22 is connected to the engine 12 via the K0 clutch 20, and is also directly connected to the electric motor MG. The K0 clutch 20 corresponds to the clutch of the present invention.

[0020] The automatic transmission 24 is connected to the torque converter 22 and is interposed in a power transmission path between the torque converter 22 and the drive wheels 14. The torque converter 22 and the automatic transmission 24 each constitute a part of the power transmission path between the engine 12 and the drive wheels 14. The drive device 16 also includes a propeller shaft 28 connected to a transmission output shaft 26 which is an output rotating member of the automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, a pair of drive shafts 32 connected to the differential gear 30, and the like. The drive device 16 also includes an engine connecting shaft 34 which connects the engine 12 and the K0 clutch 20, an electric motor connecting shaft 36 which connects the K0 clutch 20 and the torque converter 22, and the like.

[0021] The electric motor MG is connected to the electric motor connecting shaft 36 so as to be capable of transmitting power. The electric motor MG is connected to a power transmission path between the engine 12 and the drive wheels 14, in particular, to a power transmission path between the K0 clutch 20 and the torque converter 22. In other words, the electric motor MG is connected to the torque converter 22 and the automatic transmission 24 so as to be capable of transmitting power without passing through the K0 clutch 20. In other words, the torque converter 22 and the automatic transmission 24 each constitute a part of the power transmission path between the electric motor MG and the drive wheels 14. The torque converter 22 and the automatic transmission 24 transmit the driving force from the engine 12 and the electric motor MG to the drive wheels 14, respectively.

[0022] The torque converter 22 is provided in a power transmission path between the engine 12 and the electric motor MG and the drive wheels 14. The torque converter 22 includes a pump wheel 22a connected to the electric motor connecting shaft 36 and a turbine wheel 22b connected to a transmission input shaft 38 which is an input rotating member of the automatic transmission 24. The pump wheel 22a is connected to the engine 12 via the K0 clutch 20 and is directly connected to the electric motor MG. The pump wheel 22a is an input member of the torque converter 22, and the turbine wheel 22b is an output member of the torque converter 22. The electric motor connecting shaft 36 is also an input rotating member of the torque converter 22. The transmission input shaft 38 is also an output rotating member of the torque converter 22 which is formed integrally with a turbine shaft which is rotationally driven by the turbine wheel 22b. The torque converter 22 is a fluid-type power transmission device which transmits driving force from each of the driving force sources (engine 12, electric motor MG) to the transmission input shaft 38 via a fluid. The torque converter 22 includes a lock-up clutch 40 (hereinafter, referred to as LU clutch 40) that connects the pump wheel 22a and the turbine wheel 22b. The LU clutch 40 is a direct clutch that connects input and output rotating members of the torque converter 22, and is a known lock-up clutch.

[0023] The operating state, i.e., the control state, of the LU clutch 40 is switched by changing the LU clutch torque, which is the torque capacity of the LU clutch 40, by the regulated LU oil pressure supplied from a hydraulic control circuit 42 provided in the vehicle 10. The control states of the LU clutch 40 include a fully released state in which the LU clutch 40 is released, a slip state in which the LU clutch 40 is engaged with slipping, and a fully engaged state in which the LU clutch 40 is engaged.

[0024] The automatic transmission 24 is a known planetary gear type automatic transmission that includes, for example, one or more planetary gear sets (not shown) and a plurality of engagement devices CB. The engagement devices CB are hydraulic friction engagement devices (friction clutches) that are configured, for example, with a multi-plate or single-plate clutch or brake pressed by a hydraulic actuator, or a band brake tightened by a hydraulic actuator. The engagement devices CB are switched between control states such as an engaged state and a released state by changing the CB torque, which is the torque capacity of each of the engagement devices CB, by the CB hydraulic pressure regulated by the hydraulic control circuit 42. In addition, since power is transmitted through the engagement devices CB when they are engaged, the engagement devices CB are provided in a power transmission path between the torque converter 22 and the driving wheels 14, and function as hydraulic friction clutches that connect and disconnect the power transmission path. The engagement device CB includes an engagement device C1 that is engaged when the vehicle starts, and the engagement device C1 is engaged when the vehicle starts, causing the vehicle 10 to start, and the engagement device C1 is released when the vehicle stops, interrupting the power transmission of the automatic transmission 24. The engagement device CB (particularly the engagement device C1) corresponds to a hydraulic friction clutch that connects and disconnects the power transmission path between the torque converter and the drive wheels of the present invention.

[0025] The automatic transmission 24 is a stepped transmission in which one of a plurality of gear stages (also called gear stages) with 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 the automatic transmission 24, the gear stages are switched according to the accelerator operation of the driver (=operator) and the vehicle speed V, etc., by an electronic control device 90 described later, that is, a plurality of gear stages are selectively formed. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 38 and is the input rotation speed of the automatic transmission 24. In addition, the AT input rotation speed Ni is also the rotation speed of the output rotating member of the torque converter 22, and is the same value as the turbine rotation speed Nt, which is the output rotation speed of the torque converter 22. Therefore, the AT input rotation speed Ni can be expressed by the turbine rotation speed Nt. The AT output rotation speed No is the rotation speed of the transmission output shaft 26 and is the output rotation speed of the automatic transmission 24.

[0026] The K0 clutch 20 is a wet or dry friction engagement device composed of a multiple-plate or single-plate clutch pressed by a hydraulic actuator (not shown). The control state of the K0 clutch 20, such as an engaged state or a released state, is switched by controlling the operating state of the hydraulic actuator by an electronic control device 90 (described later). When the K0 hydraulic pressure regulated by the hydraulic control circuit 42 is supplied to the hydraulic actuator in the K0 clutch 20, the K0 torque, which is the torque capacity of the K0 clutch 20, is changed, and the control state of the K0 clutch 20 is switched.

[0027] When the K0 clutch 20 is engaged, the pump impeller 22a and the engine 12 are rotated integrally via the engine connecting shaft 34. That is, when the K0 clutch 20 is engaged, the engine 12 and the driving wheels 14 are connected to each other so that power can be transmitted. On the other hand, when the K0 clutch 20 is released, the power transmission between the engine 12 and the pump impeller 22a is interrupted. That is, when the K0 clutch 20 is released, the connection between the engine 12 and the driving wheels 14 is cut off. Since the electric motor MG is connected to the pump impeller 22a, the K0 clutch 20 is provided in the power transmission path between the engine 12 and the electric motor MG and functions as a clutch that connects and disconnects the power transmission path, that is, a clutch that connects and disconnects the engine 12 and the electric motor MG. That is, the K0 clutch 20 is a disconnecting clutch that connects the engine 12 and the electric motor MG to each other when engaged, and disconnects the connection between the engine 12 and the electric motor MG when released.

[0028] In the drive unit 16, when the K0 clutch 20 is engaged, the power output from the engine 12 is transmitted from the engine connecting shaft 34 to the driving wheels 14 via the K0 clutch 20, the electric motor connecting shaft 36, the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in this order. Moreover, the power output from the electric motor MG is transmitted from the electric motor connecting shaft 36 to the driving wheels 14 via the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in this order, regardless of the control state of the K0 clutch 20.

[0029] The vehicle 10 is equipped with the MOP 58, which is a mechanical oil pump, and the EOP 60, which is an electric oil pump. The MOP 58 is connected to the pump impeller 22a, and is rotated and driven by a driving power source (the engine 12, the electric motor MG) to discharge hydraulic oil OIL used in the drive device 16. The EOP 60 is rotated and driven by a pump motor (not shown) to discharge hydraulic oil OIL. The hydraulic oil OIL discharged by the MOP 58 and the EOP 60 is supplied to the hydraulic control circuit 42.

[0030] The vehicle 10 also includes an inverter 62 that controls the operating state of the electric motor MG, a high-voltage battery 64, a system main relay 66 (hereinafter, SMR 66), a capacitor 68, a DCDC converter 70, and an auxiliary battery 72.

[0031] The inverter 62 includes known switching elements therein, and the switching elements are controlled so that the electric motor MG obtains a driving torque or a regenerative torque based on a command from an MGECU 96 described later. Three lines (Lu, Lv, Lw) connecting the inverter 62 and the electric motor MG shown in Fig. 1 correspond to wiring connected to a three-phase winding constituting the stator coil 78 of the electric motor MG.

[0032] The high-voltage battery 64 is composed of a chargeable and dischargeable secondary battery such as a lithium-ion secondary battery or a nickel-hydrogen secondary battery, and is configured to be able to supply and receive power to and from the inverter 62. The SMR 66 is provided between the high-voltage battery 64 and the inverter 62, and is a relay that connects and disconnects a high-voltage circuit between the high-voltage battery 64 and the inverter 62. The SMR 66 includes an SMRB (system main relay positive side) and an SMRG (system main relay negative side). When the SMR 66 is connected, the SMRB and SMRG are connected (on), so that the power of the high-voltage battery 64 can be supplied to the inverter 62. When the SMR 66 is disconnected, the SMRG and SMRB are disconnected (off), so that the power supply between the high-voltage battery 64 and the inverter 62 is interrupted. The SMR 66 switches between a connected and disconnected state in response to a command signal output from the HVECU 92, which will be described later.

[0033] The capacitor 68 is provided to smooth the current of the high-voltage battery 64. The capacitor 68 is provided in parallel with the inverter 62 that controls the electric motor MG. The DCDC converter 70 is a step-down converter that steps down the output voltage of the high-voltage battery 64 and charges the auxiliary battery 72. The auxiliary battery 72 is an electric storage device that stores the electric power stepped down by the DCDC converter 70. The electric power of the auxiliary battery 72 is configured to be supplied to a starter motor 74 for starting the engine 12, for example.

[0034] The vehicle 10 is equipped with an electronic control device 90, which is a control device that executes various controls such as driving control of the vehicle 10. The electronic control device 90 includes a so-called microcomputer equipped with, for example, a CPU, a RAM, a ROM, an input / output interface, 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. The electronic control device 90 includes various control devices such as a hybrid control ECU 92 (hereinafter, HVECU 92), an engine control ECU 94 (hereinafter, EGECU 94), and an electric motor control ECU 96 (hereinafter, MGECU 96) as necessary. The HVECU 92, the EGECU 94, and the MGECU 96 are capable of communicating with each other via a communication line 46.

[0035] The electronic control device 90 receives various signals based on detection values ​​from various sensors provided in the vehicle 10 (for example, an engine rotation speed sensor 100, a turbine rotation speed sensor 102, an output rotation speed sensor 104, a MG rotation speed sensor 106, an accelerator opening sensor 108, a throttle valve opening sensor 110, a brake switch 112, a battery sensor 114, a MG temperature sensor 116, an acceleration sensor 118, and a voltage sensor 120). The following are respectively supplied: T output rotation speed No, MG rotation speed Nm which is the rotation speed of the electric motor MG, accelerator opening θacc which is the amount of accelerator operation by the driver which indicates the magnitude of the driver's acceleration operation, throttle valve opening θth which is the opening of the electronic throttle valve, brake on signal Bon which is a signal indicating the state in which the brake pedal for activating the wheel brakes is being operated by the driver, battery temperature THbat, battery charge / discharge current Ibat and battery voltage Vbat of the high-voltage battery 64, temperature THm of the electric motor MG, vehicle acceleration α, capacitor voltage VH, etc.

[0036] The HVECU 92 functionally includes a hybrid control unit 122 as a hybrid control means for executing hybrid driving of the vehicle 10. The hybrid control unit 122 calculates a driving demand amount for the vehicle 10 by applying the accelerator opening θacc and the vehicle speed V to a driving demand amount map, for example. The driving demand amount map is a relationship that is experimentally or design-wise obtained and stored in advance, that is, a predetermined relationship. The hybrid control unit 122 also outputs a command to the EGECU 94 to control the engine 12 so as to realize the required driving power in consideration of the transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 24, the chargeable power and dischargeable power of the high-voltage battery 64, and the like, and outputs a command to the MGECU 96 to control the electric motor MG. In response to a command from the HVECU 92, the EGECU 94 outputs an engine control command signal Se to the engine control device 50 to control the engine 12 so as to realize the required driving power. Similarly, upon receiving a command from the HVECU 92, the MGECU 96 outputs to the inverter 62 an MG control command signal Sm for controlling the electric motor MG so as to realize the required driving power.

[0037] In addition, when it is determined that charging control of the high-voltage battery 64 is necessary, for example because the state of charge value SOC of the high-voltage battery 64 falls below a predetermined value, the hybrid control unit 122 can also drive the engine 12 to perform charging control through regeneration of the electric motor MG.

[0038] Next, an operation of the vehicle 10 configured as described above when a collision occurs while the vehicle 10 is traveling will be described. When a collision (vehicle collision) of the vehicle 10 is detected, the electronic control device 90 generates a drag torque in a direction to stop the rotation of the electric motor MG, and has a function of executing discharge control to discharge the charge of the capacitor 68 when the rotation of the electric motor MG stops.

[0039] The electronic control device 90 functionally includes a hybrid control unit 122 that operates in the event of a vehicle collision, a collision determination unit 124 as a collision determination means, a relay cutoff unit 126 as a relay cutoff means, a rotation stop control unit 128 as a rotation stop control means, a rotation stop determination unit 130 as a rotation stop determination means, and a discharge control unit 132 as a discharge control means. In this embodiment, the HVECU 92 functionally includes the hybrid control unit 122, the collision determination unit 124, and the relay cutoff unit 126, and the MGECU 96 functionally includes the rotation stop control unit 128, the rotation stop determination unit 130, and the discharge control unit 132. The collision determination unit 124, the rotation stop control unit 128, the rotation stop determination unit 130, and the discharge control unit 132 correspond to the control units of the present invention.

[0040] The collision determination unit 124 determines whether or not a collision has been detected while the vehicle 10 is traveling, i.e., whether or not a vehicle collision has occurred. The collision determination unit 124 determines whether or not a vehicle collision has been detected based on, for example, whether or not an activation signal for an airbag system that activates in the event of a vehicle collision has been output.

[0041] When a vehicle collision is detected, the hybrid control unit 122 cuts off the power supply to the vehicle 10 ("Ready-OFF"), and in parallel therewith outputs a command to the EGECU 94 to stop the engine 12 and outputs a command to the hydraulic control circuit 42 to release the K0 clutch 20. This executes a fuel cut that stops the fuel supply to the engine 12, and stops the engine 12. In addition, the solenoid that controls the K0 clutch 20 operates to the release side of the K0 clutch 20, thereby releasing the K0 clutch 20. For example, in the case where the K0 clutch 20 is configured to be engaged when a drive current is supplied to the solenoid, the K0 clutch 20 is released by stopping the drive current to the solenoid.

[0042] Next, the relay cutoff unit 126 cuts off the SMR 66 to cut off the power supply from the high-voltage battery 64. At this time, since there is a concern that a malfunction may occur if the SMR 66 is cut off while power can be supplied to the electric motor MG, the relay cutoff unit 126 temporarily cuts off the power supply to the inverter 62 (cuts off the inverter gate) and then cuts off the SMR 66.

[0043] When the SMR 66 is cut off, the rotation stop control unit 128 executes rotation stop control to stop the rotation of the electric motor MG. The rotation stop control unit 128 executes three-phase ON control as rotation stop control to generate a drag torque (rotation braking torque) acting in a direction to stop the rotation of the electric motor MG. Note that the three-phase ON control is a known technique, and therefore a detailed description thereof will be omitted.

[0044] The rotation stop determination unit 130 determines whether the motor MG has stopped rotating when performing discharge control. The rotation stop determination unit 130 determines whether the motor MG has stopped rotating based on whether the sum of squares IS of the current values ​​of each phase (U phase, V phase, W phase) of the three-phase winding constituting the stator coil 78 of the motor MG is equal to or smaller than a predetermined value IX during a rotation stop transition period of the motor MG. The sum of squares IS of the current values ​​is calculated from the following formula (1) when the current value of the U phase is current value Iu, the current value of the V phase is current value Iv, and the current value of the W phase is current value Iw. The predetermined value IX is determined in advance experimentally or by design, and is set to a very small value at which it can be determined that the motor MG has stopped rotating. In this way, by determining whether the motor MG has stopped rotating based on the sum of squares IS of the current values ​​(Iu, Iv, Iw) of the three-phase windings constituting the stator coil 78 of the motor MG during the transitional period of the motor MG to stop rotating, rather than based on the MG rotation speed Nm detected by the MG rotation speed sensor 106, it is possible to determine whether the motor MG has stopped rotating even if the MG rotation speed sensor 106 has failed due to a vehicle collision. Note that the current values ​​(Iu, Iv, Iw) are detected by a current sensor built into the inverter 62. IS=(Iu 2 +Iv 2 +Iw 2 ) 1 / 2 (1)

[0045] Here, when the electric motor MG is stopped to execute the discharge control, even if it is determined that the MG rotation speed Nm of the electric motor MG has stopped rotating, if the drive wheels 14 are still rotating after the vehicle collision, the rotation of the drive wheels 14 may be transmitted to the turbine impeller 22b via the automatic transmission 24, and may further be transmitted to the pump impeller 22a and the electric motor connecting shaft 36 due to the drag of the fluid in the torque converter 22. At this time, if the three-phase ON control is stopped, the electric motor MG may rotate again, and the discharge control may not be executed. Note that when the vehicle 10 collides, the LU clutch 40 and the engagement device CB (engagement device C1) of the automatic transmission 24 are released as the vehicle speed V decreases, but if there is a delay in releasing the engagement device CB (C1) due to, for example, residual pressure in the hydraulic actuator of the engagement device CB (C1), when the drive wheels 14 rotate after the vehicle collision, the rotation is transmitted to the torque converter 22 via the engagement device CB (C1) of the automatic transmission 24 to rotate the electric motor MG.

[0046] In response to this, when the rotation stop determination unit 130 determines that the motor MG has stopped rotating, it further determines whether the turbine rotation speed Nt, which is the rotation speed of the turbine wheel 22b, has become equal to or lower than a preset predetermined rotation speed Nts. The predetermined rotation speed Nts is determined in advance experimentally or by design, and is set to, for example, an upper limit value of the turbine rotation speed Nt at which the motor connecting shaft 36, which is the rotating shaft of the motor MG, does not rotate with the rotation of the turbine wheel 22b. After it is determined that the motor MG has stopped rotating, it is further determined whether the turbine rotation speed Nt has decreased to a rotation speed at which the motor connecting shaft 36 does not rotate with the rotation of the turbine wheel 22b, so that the motor MG will not rotate again after it has stopped rotating. The turbine wheel 22b corresponds to the turbine of the present invention.

[0047] The rotation stop control unit 128 stops the three-phase ON control when the electric motor MG stops rotating and the turbine rotation speed Nt becomes equal to or lower than the predetermined rotation speed Nts. On the other hand, if the turbine rotation speed Nt is higher than the predetermined rotation speed Nts even when the electric motor MG stops rotating, the rotation stop control unit 128 continues the three-phase ON control because there is a possibility that the electric motor MG will rotate again. In this way, by continuing the three-phase ON control until the electric motor MG stops rotating and the turbine rotation speed Nt becomes equal to or lower than the predetermined rotation speed Nts, there is no risk of the electric motor MG rotating again after the three-phase ON control is stopped.

[0048] When it is determined that the motor MG has stopped rotating and that the turbine rotation speed Nt has become equal to or lower than a predetermined rotation speed Nts, the discharge control unit 132 starts discharge control by the motor MG. The rotation stop control unit 128 executes discharge control to control the inverter 62 so that a d-axis current flows through the motor MG, thereby discharging the charge of the capacitor 68 without outputting torque from the motor MG. As described above, the discharge control is executed on the condition that the motor MG has stopped rotating and that the turbine rotation speed Nt has decreased to or lower than the predetermined rotation speed Nts, so that the discharge control is executed reliably under a condition where there is no risk of the motor MG rotating again.

[0049] The discharge control unit 132 detects the capacitor voltage VH of the capacitor 68 as needed while the discharge control is being performed, and determines whether or not to stop the discharge control based on whether or not the capacitor voltage VH has become equal to or lower than a predetermined voltage VX. The predetermined voltage VX is determined in advance experimentally or by design, and is set, for example, to a voltage threshold value at which it can be determined that the charge in the capacitor 68 has been discharged and there is no longer a risk of electric shock. The discharge control unit 132 continues the discharge control when the capacitor voltage VH is higher than the predetermined pressure VX. On the other hand, the discharge control unit 132 stops the discharge control when the capacitor voltage VH has become equal to or lower than the predetermined pressure VX.

[0050] 2 is a flowchart for explaining the main control operations of the electronic control device 90, and is a flowchart for explaining the control operations related to the discharge control when the vehicle 10 collides while traveling. This flowchart is repeatedly executed while the vehicle is traveling.

[0051] First, in step S10 (hereinafter, step is omitted) corresponding to the collision determination unit 124, it is determined whether or not a vehicle collision has been detected during traveling. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, in S20 corresponding to the control function of the hybrid control unit 122, the power supply to the vehicle 10 is cut off ("Ready-OFF"), and further, the engine 12 is stopped and the K0 clutch 20 is released. Next, in S30 corresponding to the control function of the relay cutoff unit 126, the power supply to the inverter 62 is temporarily cut off (inverter gate cutoff), and then the SMR 66 is cut off (SMR cutoff). In S40 corresponding to the control function of the rotation stop control unit 128, three-phase ON control is executed, and a drag torque (rotation braking torque) in a direction to stop the rotation of the electric motor MG is generated. This drag torque reduces the MG rotation speed Nm of the electric motor MG. In S50, which corresponds to the control function of the rotation stop determination unit 130, it is determined whether the motor MG has stopped rotating based on whether the sum of squares IS of the current values ​​(Iu, Iv, Iw) flowing through the three-phase windings of the motor MG is equal to or less than a predetermined value IX. If the determination in S50 is negative, the process returns to S40 and the three-phase ON control is continued. If the determination in S50 is positive, it is determined in S60, which corresponds to the control function of the rotation stop determination unit 130, whether the turbine rotation speed Nt of the turbine impeller 22b of the torque converter 22 is equal to or less than a predetermined rotation speed Nts. If the determination in S60 is negative, the process returns to S40 and the three-phase ON control is continued until both the determinations in S50 and S60 are positive. If the determination in S60 is positive, it is determined that the motor MG will not rotate again, and the three-phase ON control is stopped in S70, which corresponds to the control function of the rotation stop control unit 128. In S80, which corresponds to the control function of the discharge control unit 132, discharge control is executed to control the inverter 62 so that a d-axis current flows through the electric motor MG. In S90, which corresponds to the control function of the discharge control unit 132, it is determined whether the capacitor voltage VH has become equal to or lower than a predetermined voltage VX as a result of the discharge control. If the determination in S90 is negative, the process returns to S80, and the discharge control continues to be executed. If the determination in S90 is positive, this routine is ended.

[0052] As described above, according to this embodiment, discharge control is executed under the condition that the electric motor MG stops rotating and the turbine rotation speed Nt of the turbine impeller 22b of the torque converter 22 drops to a predetermined rotation speed Nts or less. Therefore, by continuing the three-phase on control until the turbine rotation speed Nt drops and the electric motor MG stops rotating again, discharge control can be reliably executed even when the electric motor MG stops rotating.

[0053] Furthermore, according to this embodiment, in the vehicle 10 in which the engine 12 is connected to the motor MG via the K0 clutch 20 so as to be capable of transmitting power, when a vehicle collision is detected, the K0 clutch 20 is released, thereby preventing the motor MG from rotating together with the engine 12 after the vehicle collision. Furthermore, whether or not the motor MG has stopped rotating is determined based on the current values ​​(Iu, Iv, Iw) of the three-phase windings constituting the stator coil 78 of the motor MG during the transitional period in which the motor MG stops rotating, so that even if the MG rotation speed sensor 106 that detects the MG rotation speed Nm of the motor MG breaks down due to a vehicle collision, it is possible to determine whether or not the motor MG has stopped rotating.

[0054] 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.

[0055] For example, in the above embodiment, the occurrence of a vehicle collision is determined by detecting an activation signal of an airbag system provided in the vehicle 10, but the present invention is not limited to this embodiment. For example, the occurrence of a collision may be determined based on whether or not the vehicle acceleration α exceeds a predetermined value. Alternatively, a strain sensor may be provided at a specific portion of the vehicle 10, and the occurrence of a collision may be determined based on the amount of strain detected by the strain sensor.

[0056] In the above embodiment, the stop of rotation of the motor MG is determined based on the current values ​​(Iu, Iv, Iw) of the three-phase windings constituting the stator coil 78 of the motor MG, but it may be determined based on the MG rotation speed Nm detected by the MG rotation speed sensor 106. Also, it is not necessary to determine based on the current values ​​(Iu, Iv, Iw) of the three-phase windings, and it may be determined based on the sum of squares of the current values ​​(Iu, Iv) of two phases (e.g., U phase, V phase) of the three-phase windings.

[0057] In the above embodiment, the HVECU 92 is functionally equipped with the hybrid control unit 122, the collision determination unit 124, and the relay cutoff unit 126, and the MGECU 96 is functionally equipped with the rotation stop control unit 128, the rotation stop determination unit 130, and the discharge control unit 132, but the present invention is not necessarily limited to this. For example, if the HVECU 92 and the MGECU 96 are configured with a common ECU, the ECU will be functionally equipped with these control units. Also, the functions of each of the above control units may be functionally equipped in different ECUs. In this way, the configuration of the ECU may be appropriately changed within the scope in which the functions of each control unit are executed.

[0058] In the above embodiment, the vehicle 10 is a hybrid vehicle using the engine 12 and the electric motor MG as a driving force source, but the present invention is not necessarily limited to a hybrid vehicle. For example, the present invention can be applied to an electric vehicle using only the electric motor MG as a driving force source.

[0059] In the above embodiment, the automatic transmission 24 is exemplified as a planetary gear type automatic transmission, but is not limited to this embodiment. For example, the automatic transmission 24 may be a known DCT (Dual Clutch Transmission), a known belt type continuously variable transmission, or the like. When the automatic transmission 24 is a DCT, one of the engagement devices connected to the input shafts of the two systems corresponds to the friction clutch of the present invention. When the automatic transmission 24 is a belt type continuously variable transmission, one of the engagement devices of the forward clutch and the reverse brake of a known forward / reverse switching device provided together with the belt type continuously variable transmission corresponds to the friction clutch of the present invention.

[0060] In the above embodiment, the torque converter 22 is used as the fluid-type power transmission device, but the present invention is not limited to this. For example, instead of the torque converter 22, other fluid-type power transmission devices such as a fluid coupling that does not amplify torque may be used as the fluid-type power transmission device.

[0061] In the above embodiment, the inverter 62 and the capacitor 68 are provided separately, but the capacitor 68 may be built into the inverter 62 .

[0062] 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]

[0063] 10: Vehicle 12: Engine (power source) 14: Drive wheel 20:K0 clutch (clutch) 22: Torque converter (fluid transmission device) 22b: Turbine wheel (turbine) 62: Inverter 68: Capacitor 78: Stator coil 90: Electronic control device (control device) 124: Collision determination unit (control unit) 128: Rotation stop control unit (control unit) 130: Rotation stop determination unit (control unit) 132: Discharge control unit (control unit) CB: Engagement device (friction clutch) MG: Electric motor (driving force source)

Claims

1. A vehicle control device is applied to a vehicle including a driving force source including at least an electric motor and a fluid type power transmission device provided in a power transmission path between the electric motor and a driving wheel, and includes a control unit that generates a torque in a direction to stop rotation of the electric motor when a vehicle collision is detected, and executes discharge control to discharge an electric charge of a capacitor provided in parallel to an inverter that controls the electric motor when the rotation of the electric motor stops, The control unit executes the discharge control under the condition that the rotation speed of the turbine of the hydrodynamic transmission falls to a predetermined rotation speed or less. A vehicle control device comprising:

2. An engine is connected to the electric motor via a clutch so as to be capable of transmitting power thereto. The control unit releases the clutch when a vehicle collision is detected.

2. The vehicle control device according to claim 1.

3. The control unit determines whether or not the motor has stopped rotating based on a current value of a stator coil of the motor during a transitional period in which the motor stops rotating.

3. The vehicle control device according to claim 1 or 2.

4. The vehicle further includes a hydraulic friction clutch provided in a power transmission path between the fluid transmission device and the drive wheels for connecting and disconnecting the power transmission path.

4. The vehicle control device according to claim 1, wherein the vehicle control device further comprises a control unit for controlling the vehicle.

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