Control device for hybrid vehicle

Abstract

The present invention addresses the problem of providing a control device for a hybrid vehicle capable of selecting engine start control capable of discharging water in an exhaust pipe when a request for starting an engine is issued during wading travel. When the transfer case is in a low speed range and IG-ON after IG-OFF, the engine start control selection unit requests engine start and selects an engine start control having a large start torque from among a plurality of engine start controls. Thus, when IG-ON after IG-OFF when the low speed range of the transfer is selected (during wading travel) during wading travel, the engine start is requested, and the engine start control having a large start torque among the plurality of engine start controls is selected, so that water in the exhaust pipe can be discharged, and the engine start control can be prevented from being turned off. Therefore, the engine can be started easily.

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle, the hybrid vehicle having a transfer case that distributes driving force transmitted from an engine to the front and rear wheels and has a transmission mechanism capable of switching between high and low speeds, the control device having multiple engine start controls with different starting torques. Background Technology

[0002] Patent Document 1 discloses a vehicle control device that, when the water level around the vehicle is above a predetermined value, prevents the engine from stopping while it is running, and starts the engine when it stops by means of idling or other means.

[0003] According to the control device of this vehicle, when the water level around the vehicle is high, it is possible to prevent water from entering the exhaust pipe while the engine is stopped.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2017-218911 Summary of the Invention

[0005] In hybrid vehicles that intermittently drive the engine based on required driving force or the remaining charge of the battery, a minimum necessary starting torque is set to improve fuel efficiency. Therefore, during wading in a hybrid vehicle, the engine intermittently stops and water enters the exhaust pipe. In the case of intermittent starting under this condition, sometimes the aforementioned starting torque is insufficient to expel the water from the exhaust pipe.

[0006] The present invention was made against the background described above, and its object is to provide a control device for a hybrid vehicle that, when an engine start request is issued during wading, can select an engine start control that can expel water from the exhaust pipe.

[0007] The inventors focused on the fact that in hybrid vehicles equipped with a transfer case having a transmission mechanism capable of switching between high and low speeds, the transfer case is switched to a low gear when driving through water. They discovered that when the transfer case is switched to a low gear and an engine start request is issued via IG-ON, if engine start control is performed with a starting torque sufficiently large than the minimum necessary starting torque, water in the exhaust pipe can be expelled, thereby facilitating engine start. The present invention was made based on this insight.

[0008] That is, the essence of the first invention is to provide a control device for a hybrid vehicle, wherein (a) the hybrid vehicle includes an engine and an electric motor, and a transfer case, the transfer case distributing the driving force transmitted from the engine and the electric motor to the front wheels and the rear wheels and having a transmission mechanism capable of switching between high and low speeds, and (b) the control device has multiple engine start controls that start the engine with relatively different starting torques, and includes an engine start control selection unit, which requests engine start when the transfer case is in a low gear and after IG-OFF and IG-ON, and selects the engine start control with the higher starting torque among the multiple engine start controls.

[0009] The essence of the second invention is that, in the first invention, (c) the hybrid vehicle has an engine disconnect clutch between the engine and the electric motor, and (d) the engine start control selection unit, in the plurality of engine start controls, for engine start controls with low starting torque, uses the electric motor to transmit starting torque to the engine while the engine disconnect clutch is slip-engaged, and for engine start controls with high starting torque, uses the electric motor to transmit starting torque to the engine while the engine disconnect clutch is fully engaged.

[0010] The essence of the third invention is that, in the second invention, the engine start control selection unit selects the engine start control with the smaller starting torque among the plurality of engine start controls when the transfer case is in high gear.

[0011] Invention Effects

[0012] In the control device of the hybrid vehicle of the first invention, when the transfer case is in a low gear, the engine start control selection unit requests engine start after IG-OFF and then IG-ON, and selects the engine start control with the highest starting torque from among multiple engine start controls. Thus, when driving through water, when the transfer case is in a low gear and IG-OFF is followed by IG-ON, the engine is requested to start, and the engine start control with the highest starting torque from among multiple engine start controls is selected. This allows water to be expelled from the exhaust pipe, making engine start easier.

[0013] In the second invention, the hybrid vehicle includes an engine disconnect clutch between the engine and the electric motor. The engine start control selection unit, among multiple engine start controls, uses the electric motor to transmit starting torque to the engine when the engine disconnect clutch is slip-engaged for engines with low starting torque, and uses the electric motor to transmit starting torque to the engine when the engine disconnect clutch is fully engaged for engines with high starting torque. Therefore, by using the electric motor to transmit starting torque to the engine when the engine disconnect clutch is fully engaged, water in the exhaust pipe can be quickly expelled, thus facilitating easy engine starting.

[0014] In the third invention, when the transfer case is in high gear, the engine start control selection unit selects the engine start control with the lowest starting torque among multiple engine start controls, so that the engine can be started with the minimum necessary starting torque in order to improve fuel efficiency. Attached Figure Description

[0015] Figure 1 This is a diagram illustrating the general structure of the drive system of a hybrid vehicle with front and rear wheel drive to which the present invention is applied, and also a diagram showing the main parts of the control function.

[0016] Figure 2 This is an explanation Figure 1 A schematic diagram of a specific example of a transmission device for HV.

[0017] Figure 3 This is an explanation Figure 1 A schematic diagram of a specific example of a transfer case.

[0018] Figure 4 This is an explanation Figure 1 A diagram showing the multiple driving modes of a hybrid vehicle.

[0019] Figure 5 This is an explanation of the reason. Figure 1 The flowchart shows the control content executed by the engine start control selection unit. Detailed Implementation

[0020] The present invention pertains to a four-wheel drive hybrid vehicle that uses both an electric motor and an engine (internal combustion engine) as power sources. The electric motor is suitably an electric generator that also functions as a generator, but an electric motor that cannot function as a generator may also be used. The hybrid vehicle is preferably a so-called single-motor hybrid vehicle, in which the engine, engine disconnect clutch, electric motor, transmission, and transfer case are arranged in sequence. However, it can also be a so-called dual-motor hybrid vehicle, in which the engine is connected to a first rotating element of a planetary gear system that functions as a power distribution device, the first electric motor is connected to a second rotating element, the second electric motor is connected to a third rotating element, and the transmission or transfer case is connected to the third rotating element. Furthermore, it can also be a so-called series hybrid vehicle, in which the first electric motor is connected to the engine, and the second electric motor drives all four wheels via a transfer case, the second electric motor being driven by electricity generated by the first electric motor.

[0021] A transfer case can be used for always-on four-wheel drive, distributing the driving force from the engine and electric motor to both the front and rear wheels. Alternatively, it can be used for partial four-wheel drive, selectively distributing a portion of the driving force transmitted from the engine and electric motor to the primary drive wheels to the secondary drive wheels. Furthermore, the high-speed / low-speed switching device of the transfer case can be, for example, a planetary gear system, but a parallel shaft type high-speed / low-speed switching device can also be used. The high-speed / low-speed switching device includes a clutch, preferably with a synchronizing mechanism, but it may not have one.

[0022] The driving mode switching control unit is configured to enable, for example, four driving modes: H4F mode, H4L mode, L4F mode, and L4L mode, based on the selection of the high / low speed selection device and the selection of the differential state selection device. However, it can also switch to only three driving modes: H4F mode, L4F mode, and L4L mode, or only three driving modes: H4F mode, H4L mode, and L4L mode.

[0023] Example

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0025] Figure 1This is a schematic diagram illustrating the drive system of the hybrid vehicle 10 to which the present invention is applied, and also shows the main parts of the control functions used for various controls in the hybrid vehicle 10. The hybrid vehicle 10 is a front-wheel drive (four-wheel drive) vehicle with a front-engine rear-wheel drive (FR) hybrid system as its basic hybrid system. The hybrid vehicle 10 includes an engine 12, a pair of left and right front wheels 14, a pair of left and right rear wheels 16, and a power transmission device 18. As is well known, in the hybrid vehicle 10, engine driving and electric motor driving are repeatedly performed to reduce fuel consumption, thereby intermittently operating the engine 12.

[0026] The power transmission device 18 includes an HV transmission 20 connected to the engine 12 and a transfer case 22 connected to the HV transmission 20. The driving force transmitted from the engine 12 and the HV transmission 20 to the transfer case 22 is transmitted to the left and right rear wheels 16 via the rear propeller shaft 26 and the differential 30. Conversely, a portion of this driving force is transmitted to the left and right front wheels 14 via the front propeller shaft 24 and the differential 28. The engine 12 is an internal combustion engine such as a gasoline engine, used as a power source for driving. The engine torque Te, which is the torque of the engine 12, is controlled by an engine control signal Se output from the electronic control unit 150.

[0027] An exhaust pipe 12c is connected to the engine 12. The exhaust pipe 12c has a catalytic converter 12a and a muffler 12b for discharging exhaust gases from the engine 12. The outlet 12d of the exhaust pipe 12c is about 30 cm above the ground. When the hybrid vehicle 10 sometimes crosses a river 70 cm deep, for example, the outlet 12d of the exhaust pipe 12c can be considered to be submerged in water during the wading operation.

[0028] Figure 2 This is a schematic diagram illustrating a specific example of the HV transmission 20. The HV transmission 20 includes a motor MG, a motor connecting shaft 42, a torque converter 44, and an automatic transmission 46, all disposed within a housing 40 (which is a non-rotating component) on a common first axis CL1. The motor MG and the torque converter 44 are configured approximately symmetrically with respect to the first axis CL1. Figure 2 The lower half of the first axis CL1 is omitted.

[0029] An engine disconnect clutch K0 is provided between the engine 12 and the motor connection shaft 42. The electric motor MG is connected to the motor connection shaft 42 via a motor disconnect clutch K2, and the electric motor MG, together with the engine 12, serves as a power source for driving. The engine disconnect clutch K0 and the motor disconnect clutch K2 are hydraulic friction engagement devices, controlled by switching signals Sk0 and Sk2 from the electronic control unit 150 via the hydraulic control circuit 52 (reference). Figure 1The hydraulic control circuit 52, in addition to having a solenoid switching valve or a solenoid pressure regulating valve, also has an electric oil pump, which can output the prescribed oil pressure even when the hybrid vehicle 10 is parked. The electric motor MG is an electric generator that also functions as a generator. It is connected to the energy storage device via an inverter (not shown). The torque of the electric motor MG, i.e., the MG torque Tmg, is controlled by the MG control signal Smg output from the electronic control unit 150.

[0030] The torque converter 44 includes a pump impeller 44a connected to the motor connection shaft 42 and a turbine impeller 44b connected to the transmission input shaft 48. The torque converter 44 is a fluid transmission device that transmits power from the engine 12 and / or the electric motor MG (which serves as a power source) to the transmission input shaft 48 via fluid. The torque converter 44 includes a lock-up clutch LU connecting the pump impeller 44a and the turbine impeller 44b. The lock-up clutch LU is a hydraulic friction engagement device that switches between engagement and disengagement states by controlling the engagement oil pressure supplied from the hydraulic control circuit 52 via the LU control signal Slu output from the electronic control unit 150.

[0031] The automatic transmission 46 is, for example, a known planetary gear type automatic transmission having one or more sets of planetary gear units and multiple engagement devices CB. The engagement devices CB are hydraulic friction engagement devices, and the engagement open / closed state is switched by controlling the engagement oil pressure supplied from the hydraulic control circuit 52 via the CB control signal Scb output from the electronic control unit 150. The automatic transmission 46 is a stepped transmission capable of forming multiple gear positions with different gear ratios γ (=AT input speed Ni / AT output speed No) depending on the engagement open / closed state of the multiple engagement devices CB. The AT input speed Ni is the rotational speed of the transmission input shaft 48, which is equal to the turbine speed Nt, which is the output speed of the torque converter 44. The AT output speed No is the rotational speed of the transmission output shaft 50.

[0032] Figure 3This is a schematic diagram illustrating a specific example of the transfer case 22. The transfer case 22, on a first axis CL1 shared with the HV transmission 20, includes a TF input shaft 62 connected to the transmission output shaft 50, a high / low speed switching device 64, a center differential 66, a rear wheel-side output shaft 68, and a sprocket-shaped drive gear 70 that outputs driving force to the wheels 14. Driving force is transmitted from the rear wheel-side output shaft 68 to the rear propeller shaft 26. The transfer case 22, on a second axis CL2 parallel to the first axis CL1, includes a front wheel-side output shaft 72 and a sprocket-shaped driven gear 74 integrally formed with the front wheel-side output shaft 72. An endless loop chain 76 is wound between the drive gear 70 and the driven gear 74. Driving force is transmitted from the center differential 66 to the front wheel-side output shaft 72 via the drive gear 70, the chain 76, and the driven gear 74. Driving force is transmitted from the front wheel-side output shaft 72 to the front propeller shaft 24.

[0033] The high-low speed switching device 64 consists of a planetary gear device with a single pinion gear type having a sun gear S1, a carrier C1, and a ring gear R1, and a high-low speed switching clutch D1, which is capable of switching between high and low speeds. The sun gear S1 is connected to the TF input shaft 62, and the ring gear R1 is fixed to the housing 40. The high-low speed switching clutch D1 is a meshing clutch with a synchronization mechanism, which includes: a high-gear side meshing tooth 80 provided on the TF input shaft 62; a low-gear side meshing tooth 82 provided on the carrier C1; and an HL switching sleeve 86, which is configured in a manner that prevents relative rotation with respect to the HL output component 84 and allows axial movement, and is provided with meshing teeth that selectively mesh with either the high-gear side meshing tooth 80 or the low-gear side meshing tooth 82. The HL switching sleeve 86, through axial reciprocating movement by a hydraulic actuator, engages with the high-gear side meshing gear 80 to switch between a high-gear Hi (directly connecting the TF input shaft 62 to the HL output component 84) and a low-gear Lo (connecting the carrier C1 to the HL output component 84 by engaging with the low-gear side meshing gear 82, thus making the HL output component 84 operate at a lower speed than the TF input shaft 62). Controlled by the D1 switching signal Sd1 output from the electronic control unit 150, the hydraulic pressure supplied from the hydraulic control circuit 52 causes the HL switching sleeve 86 to move axially, switching the high / low speed switching device 64 between the high-gear Hi and the low-gear Lo. Between the high-gear Hi and the low-gear Lo, the HL switching sleeve 86 does not engage with either the high-gear side meshing gear 80 or the low-gear side meshing gear 82, remaining in a neutral state where power transmission is cut off.

[0034] The central differential 66 is configured as a planetary gear unit with a single pinion, including a sun gear S2, a carrier C2, and a ring gear R2. The carrier C2 is connected to the HL output component 84 and is driven to rotate. Furthermore, the ring gear R2 is connected to the rear wheel-side output shaft 68, and the sun gear S2 is connected to the drive gear 70, differentially transmitting the rotation of the HL output component 84 to the front wheel 14 and the rear wheel 16.

[0035] Between the sun gear S2 and the carrier C2 of the central differential 66, a differential locking clutch D2 is provided as a differential locking device to restrict differential rotation. The differential locking clutch D2 is a non-synchronizing engagement clutch, comprising: engagement teeth 90 on the sun gear S2; engagement teeth 92 on the carrier C2; and a differential locking sleeve 94, configured to move axially, and having engagement teeth that mesh with the engagement teeth 90 and 92. The differential locking sleeve 94 is always engaged with one engagement tooth 90 and, through axial reciprocating movement by a hydraulic actuator, engages with the other engagement tooth 92, connecting the sun gear S2 and the carrier C2 in a differential lock that prevents relative rotation. When the engagement with the other engagement tooth 92 is released, relative rotation of the sun gear S2 and the carrier C2, i.e., differential rotation of the central differential 66, is allowed, switching to free rotation. By controlling the oil pressure supplied from the hydraulic control circuit 52 by the D2 switching signal Sd2 output from the electronic control unit 150, the differential locking sleeve 94 moves axially, and the central differential 66 switches to free and differential locking.

[0036] return Figure 1 The hybrid vehicle 10 includes an electronic control unit 150 as a control device for controlling the operation of various components such as the engine 12, the HV transmission 20, and the transfer case 22. The electronic control unit 150 is configured as a so-called microcomputer including a CPU, RAM, ROM, input / output interfaces, etc., and performs various controls by processing signals according to a program pre-stored in the ROM.

[0037] Various sensors installed in the hybrid vehicle 10 supply various information required for control to the electronic control unit 150. For example, the engine speed Ne, representing the speed of the engine 12, the MG speed Nmg, the AT input speed Ni, and the AT output speed Nmg, representing the speed of the electric motor MG, are respectively supplied from the engine speed sensor 112, MG speed sensor 114, AT input speed sensor 116, AT output speed sensor 118, throttle opening sensor 120, throttle opening sensor 122, brake force sensor 124, wheel speed sensor 126, high and low speed status detection sensor 128, and differential status detection sensor 130. The system outputs signals including engine speed No, throttle opening θacc corresponding to the amount of throttle pedal operation, throttle valve opening θth (which corresponds to the opening of the electronic throttle valve of engine 12), braking force Fbr corresponding to the force of brake pedal operation, wheel speeds Nwfl, Nwfr, Nwrl, and Nwrr of the front and rear wheels 16, high / low speed state Phl (indicating whether the high / low speed switching device 64 is in high gear Hi or low gear Lo), and differential state Pdiff (indicating whether the central differential 66 is free or locked). The vehicle speed V can be calculated from the wheel speeds Nwfl, Nwfr, Nwrl, and Nwrr.

[0038] The gear selection device 140, the high / low speed selection device 142 (which selects whether the high / low speed switching device 64 is set to high gear Hi or low gear Lo), and the differential status selection device 144 (which selects whether the central differential 66 is set to free or locked) respectively supply the gear selection signal Srang, the high / low speed selection signal Shl, and the differential status selection signal Sdiff to the electronic control unit 150. These gear selection devices 140, 142, and 144 are, for example, operating devices located near the driver's seat and operated by the driver. The gear selection device 140, for example, allows selection via a gear lever or the like, of a forward-driving gear (D), a reverse-driving gear (R), or a parking gear (P). The high / low speed selection device 142 is, for example, a low-gear selection switch operated when low gear Lo is selected, and selects high gear Hi when not operated. The differential state selection device 144 is, for example, a differential lock selection switch that operates when the differential is locked, and is free to select when not in operation. These high / low speed selection devices 142 and differential state selection devices 144 are operated, for example, to set the high / low speed switching device 64 to the low gear Lo or to lock the center differential 66 when improving passability on muddy roads, icy roads, riverbanks, and other places with poor road conditions.

[0039] The electronic control unit 150 calculates the required drive torque based on the throttle opening θacc and vehicle speed V, and determines the engine driving mode or electric motor driving mode from a pre-stored driving mode mapping based on the required drive torque. It then controls the engine torque Te and MG torque Tmg for engine driving or the MG torque Tmg for electric motor driving to minimize fuel consumption. Through this control, the engine 12 of the hybrid vehicle 10 operates intermittently. Furthermore, in addition to executing automatic transmission 46 shift control based on a pre-set shift mapping, the electronic control unit 150 also includes: a four-wheel driving mode switching control unit 152 that switches between various four-wheel driving modes with different operating states of the transfer case 22; and an engine start control selection unit 154 that has multiple engine start control (modes) with relatively different starting torque values. When the transfer case 22 is in a low gear, it selects the engine start control with the highest starting torque when starting the engine after the engine stop period (electric motor driving period) to improve the startability of the engine 12 during wading.

[0040] The four-wheel driving mode switching control unit 152 changes the operating state of the high-low speed switching device 64 and the differential lock-up clutch D2 based on the selection of the high-low speed selection device 142 and the differential state selection device 144, thereby switching the transfer case 22 to... Figure 4 Any one of the four four-wheel driving modes shown. Specifically, switching to H4F mode (high / low speed switch 64 in high gear Hi and center differential 66 free), H4L mode (high / low speed switch 64 in high gear Hi and center differential 66 locked), L4F mode (high / low speed switch 64 in low gear Lo and center differential 66 free), and L4L mode (high / low speed switch 64 in low gear Lo and center differential 66 locked). Figure 5 As shown, these H4F, H4L, L4F, and L4L modes switch the high / low speed switching device 64 and the differential locking clutch D2 respectively according to the selection operation of the high / low speed selection device 142 and the differential state selection device 144, but the high / low speed switching device 64 and the differential locking clutch D2 will not switch simultaneously.

[0041] The engine start control selection unit 154 has multiple engine start controls (modes) that start the engine 12 with relatively different starting torques. When the transfer case 22 is in low gear according to the signal from the four-wheel driving mode switching control unit 152, the engine is requested to start when IG-ON (ignition on state) after IG-OFF (engine 12 stops based on ignition off). The engine start control with the largest starting torque is selected from the multiple engine start controls, preferably the engine start control with the largest starting torque, to start the engine 12.

[0042] The engine start control selection unit 154, among multiple engine start controls, selects the engine start control with a high starting torque by transmitting the starting torque to the engine 12 using the electric motor MG while the engine disconnect clutch K0 is fully engaged. Conversely, for the engine start control with a low starting torque, the engine start control selection unit 154 transmits the starting torque to the engine 12 using the electric motor MG while the engine disconnect clutch K0 is slip-engaged. For example, when the transfer case 22 is in high gear, the engine start control selection unit 154 selects the engine start control with the low starting torque among the multiple engine start controls.

[0043] Figure 5 This is a flowchart illustrating the main parts of the control operation of the electronic control device 150. Figure 5 S3, S5-S7 correspond to the engine start control selection unit 154. In step S1 (hereafter omitted), after setting IG-OFF to stop the intermittently running engine 12 and switch to electric motor driving mode, in S2, it is set to IG-ON to switch to engine driving mode. Next, assuming that the transfer case 22 has been switched to low gear by the operation of the high / low speed selection device 142 at least during wading, in S3, it is determined whether the transfer case 22 has been switched to low gear. If the determination in S3 is negative, the transfer case 22 is in high gear, so the electric motor driving mode continues, and it is set to ReadyON in S4. However, if the judgment in S3 is affirmed, an engine start request is issued in S5, and in S6, among multiple engine start controls (modes) that use the electric motor MG and the engine disconnect clutch K0 to start the engine 12 with relatively different starting torques, the engine start control with the larger starting torque that transmits starting torque to the engine 12 while the engine disconnect clutch K0 is fully engaged is selected. Then, in S7, the engine 12 is started using the engine start control with the larger starting torque selected in S6. Finally, in S4, the engine is set to engine driving mode and set to ReadyON state.

[0044] As described above, in the electronic control unit 150 of the hybrid vehicle 10 of this embodiment, when the transfer case 22 is in a low gear, the engine start control selection unit 154 requests engine start after IG-OFF and IG-ON, and selects the engine start control with the highest starting torque among multiple engine start controls. Thus, when the low gear of the transfer case 22 is selected, at least during wading, the engine is requested to start after IG-OFF and IG-ON, and the engine start control with the highest starting torque among multiple engine start controls is selected. Therefore, water in the exhaust pipe 12c can be expelled, making engine start easy.

[0045] Furthermore, in the electronic control unit 150 of the hybrid vehicle 10 in this embodiment, the hybrid vehicle 10 has an engine disconnect clutch K0 between the engine 12 and the electric motor MG. In multiple engine start controls, the engine start control selection unit 154, for engine start controls with low starting torque, uses the electric motor MG to transmit starting torque to the engine 12 while the engine disconnect clutch K0 is slip-engaged. For engine start controls with high starting torque, the electric motor MG is used to transmit starting torque to the engine 12 while the engine disconnect clutch K0 is fully engaged. Therefore, for engine start controls with high starting torque, using the electric motor MG to transmit starting torque to the engine 12 while the engine disconnect clutch K0 is fully engaged allows for rapid drainage of water from the exhaust pipe 12c, thus facilitating easy engine start.

[0046] Furthermore, in the electronic control unit 150 of the hybrid vehicle 10 in this embodiment, when the transfer case 22 is in high gear, the engine start control selection unit 154 selects the engine start control with the smaller start torque among a plurality of engine start controls with different start torques, so that the engine 12 can be started with the minimum necessary start torque to improve fuel efficiency.

[0047] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but these are only one implementation method and can be implemented in a manner with various changes and improvements.

[0048] Symbol Explanation

[0049] 10-Hybrid vehicle, 12-Engine, 12c-Exhaust pipe, 14-Front wheel, 16-Rear wheel, 22-Transfer transfer case, 150-Electronic control unit (control unit), 154-Engine start control selector, MG-Electric motor, K0-Engine disconnect clutch.

Claims

1. A control device of a hybrid vehicle characterized by comprising: The hybrid vehicle is provided with an engine and an electric motor, and a transfer that distributes driving force transmitted from the engine and the electric motor to front wheels and rear wheels and has a speed change mechanism that can be switched between high speed and low speed, The control device has a plurality of engine start controls that start the engine with relatively different magnitudes of start torque, and includes an engine start control selection section that, when the transfer is in the low speed range, requests engine start at IG-ON after IG-OFF, and selects an engine start control of the plurality of engine start controls that has a large start torque.

2. The control device of the hybrid vehicle according to claim 1, characterized in that The hybrid vehicle is provided with an engine disconnect clutch between the engine and the electric motor, The engine start control selection section uses the electric motor to transmit start torque to the engine in a state in which the engine disconnect clutch is slip-engaged for an engine start control of the plurality of engine start controls that has a small start torque, and uses the electric motor to transmit start torque to the engine in a state in which the engine disconnect clutch is fully engaged for an engine start control of the plurality of engine start controls that has a large start torque.

3. The control device of the hybrid vehicle according to claim 2, characterized in that The engine start control selection section selects an engine start control of the plurality of engine start controls that has a small start torque when the transfer is in the high speed range.

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