JP6269472B2 - Vehicle drive device - Google Patents

Description

  The present invention relates to a drive device for a vehicle that travels using the output of at least one of an engine, a first motor generator, and a second motor generator.

  International Publication No. 2014/002219 (Patent Document 1) includes a transmission and a differential device provided between an engine and two three-phase AC motor generators (a first motor generator and a second motor generator). A hybrid vehicle is disclosed. In this hybrid vehicle, a planetary gear mechanism having a carrier, a sun gear, and a ring gear is used as a differential device. The carrier is connected to the engine via the transmission, the sun gear is connected to the first motor generator, and the ring gear is connected to the second motor generator and the drive wheels. The transmission has hydraulic friction engagement elements (clutch and brake).

  The hybrid vehicle disclosed in Patent Document 1 is capable of both-motor traveling that travels using the outputs of both the first motor generator and the second motor generator. While the two motors are running, the output of the first motor generator is transmitted from the sun gear to the ring gear using the carrier as a fulcrum by engaging the friction engagement element of the transmission and fixing the carrier of the actuator.

International Publication No. 2014/002219

  The actuator mounted on the hybrid vehicle disclosed in Patent Document 1 is configured such that when one of the three rotational elements of the carrier, the sun gear, and the ring gear is determined, the remaining one rotational speed is determined. Has been. For this reason, when the vehicle stops while the two motors running with the carrier fixed, the rotation of the ring gear in addition to the carrier is also restricted, so the rotation of the remaining sun gear is also restricted. Therefore, during the period in which torque is output from the first motor generator and the second motor generator when the vehicle is stopped, such as at the start of the start on an uphill road, each motor generator is supplied with a three-phase alternating current even though it is supplied to each motor generator. There is a possibility that the motor does not rotate and a phase change of current does not occur in each motor generator, and a current flows in only one phase (hereinafter referred to as “single phase lock”). If the single-phase lock is continued, there is a possibility that the heat load of each motor generator and an electric device (such as an inverter) that drives each motor generator increases.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to avoid a single-phase lock of a motor generator while suppressing fluctuations in vehicle driving force in a hybrid vehicle capable of running both motors. It is to be.

  A vehicle drive device according to the present invention is a vehicle drive device that travels using the output of at least one of an engine, a first motor generator, and a second motor generator, and includes a first rotating element connected to the engine, and And a second rotating element connected to the first motor generator and a third rotating element connected to the second motor generator and the drive wheel, and any two of the first to third rotating elements rotate. A differential device configured to determine the remaining one rotational speed when the speed is determined, a friction engagement device for fixing the first rotating element of the differential device, and the engine is stopped and first and second Running in the two-motor running mode in which the vehicle is driven using both outputs of the motor generator is executed with the first rotating element fixed by engaging the friction engagement device. And a control device. The control device determines whether or not the first and second motor generators are in a locked state in which the first and second motor generators are not rotated even when current is supplied to the first and second motor generators during both motor travel modes. When the determination is made, the differential rotation control is executed while maintaining the two-motor running mode. The differential rotation control is control that allows the rotation of the first rotation element by setting the friction engagement device in a half-engaged state while suppressing the fluctuation of the vehicle driving force by the output of the first motor generator.

  According to such a configuration, even when the first motor generator is in the locked state during the both-motor running mode, the friction engagement device is changed to the half-engaged state to allow the rotation of the first rotating element. The locked state of the first motor generator can be released, and the thermal load on the electrical equipment for driving the first motor generator and the first motor generator can be reduced. Furthermore, since the fluctuation of the vehicle driving force is suppressed by the output of the first motor generator, the thermal load can be reduced while maintaining the vehicle driving force and ensuring the stability.

  Preferably, the vehicle includes an electric device for driving the first and second motor generators. The controller controls the amount of increase in the temperature of the first motor generator per unit time, the amount of increase in the temperature of the second motor generator per unit time, and the increase in the temperature of the electric device per unit time during the both motor travel modes. Based on at least one of the quantities, it is determined whether or not the lock state is established.

  According to such a configuration, the presence or absence of the locked state can be determined based on the amount of increase in the temperature of each motor generator and the temperature of the electrical equipment for driving each motor generator per unit time.

  Preferably, the control device decreases the absolute value of the rotation speed of the first rotation element during the differential rotation control as the temperature of the oil supplied to the friction engagement device is higher.

  According to such a configuration, the higher the oil temperature, the smaller the absolute value (the amount of heat generated by the friction engagement device) of the first rotation element during the differential rotation control, so that the friction engagement device is overheated. A decrease in durability can be suppressed.

  Preferably, the control device decreases the absolute value of the rotation speed of the first rotation element during the differential rotation control as the time during which the differential rotation control is continued is longer.

  According to such a configuration, as the time during which the differential rotation control is continued (the time during which the friction engagement device is continuously slid) is longer, the absolute value (friction) of the rotation speed of the first rotation element during the differential rotation control is longer. The amount of heat generated by the slippage of the engagement device) is reduced, so that a decrease in durability due to overheating of the friction engagement device can be suppressed.

  Preferably, the control device increases the absolute value of the rotation speed of the first rotation element during execution of the differential rotation control as the time during which the first rotation element is maintained in the fixed state before execution of the differential rotation control is longer. To do.

  According to such a configuration, in view of the fact that the lubricating oil is not supplied around the first rotating element in the state where the first rotating element is fixed, the longer the time during which the first rotating element is maintained in the fixed state, The rotation of the first rotating element during execution of the differential rotation control can be promoted to facilitate the supply of lubricating oil to the components around the first rotating element.

  Preferably, the control device increases the torque sharing ratio of the first motor generator with respect to the required drive torque when executing the differential rotation control than when not executing the differential rotation control.

  According to such a configuration, by increasing the torque sharing ratio of the first motor generator, the torque sharing ratio of the second motor generator is reduced, so that the current flowing through the second motor generator is also reduced. Therefore, the heat load of the second motor generator can be suitably reduced while maintaining the vehicle driving torque.

It is a figure which shows the whole structure of a vehicle. It is the block diagram which showed the structure of the control apparatus. It is a figure which shows the action | operation engagement table | surface of the clutch C1 and brake B1 in each driving mode. FIG. 7 is a nomographic chart in the HV traveling mode (low gear stage Lo). It is a collinear diagram in HV driving mode (high gear stage Hi). It is an alignment chart in the single motor travel mode. It is a collinear diagram in both motor drive modes. It is the figure which illustrated the correspondence of vehicle speed, demanded driving force, and run mode. It is a nomograph (the 1) in the case of moving forward during both motor travel by differential rotation control. FIG. 6 is a collinear diagram (No. 2) in the case where the vehicle moves forward during both motor traveling by the differential rotation control. It is a nomograph (the 1) in the case of going backwards during both-motors run by differential rotation control. FIG. 10 is a collinear diagram (No. 2) in the case where the vehicle travels backward while both motors are traveling under differential rotation control. It is a flowchart (the 1) which shows the process sequence of a control apparatus. It is a figure which shows typically the change of the control state at the time of switching from the both motor drive by fixed control to the both motor drive by differential rotation control. It is a flowchart (the 2) which shows the process sequence of a control apparatus. It is a figure which shows an example of the relationship between oil temperature and the tolerance | permissible_range of differential rotation speed (DELTA) N.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Overall configuration of hybrid vehicle]
FIG. 1 is a diagram illustrating an overall configuration of a vehicle 1 including a drive device according to the present embodiment. The vehicle 1 includes an engine 10, a first motor generator (hereinafter referred to as “first MG”) 20, a second motor generator (hereinafter referred to as “second MG”) 30, and inverters for driving the first MG 20 and the second MG 30, respectively. 25, 35, a transmission 40, a differential gear (planetary gear device) 50, a counter shaft (output shaft) 70, a differential gear 80, drive wheels 90, and a control device 100.

  The vehicle 1 is an FF (front engine / front drive) type hybrid vehicle that travels using at least one of the power of the engine 10, the first MG 20, and the second MG 30. The driving method of the vehicle 1 is not limited to the FF method, and may be an FR (front engine / rear drive) method.

  The engine 10 is, for example, an internal combustion engine such as a gasoline engine or a diesel engine. The engine 10 is controlled by a control signal from the control device 100.

  First MG 20 and second MG 30 are, for example, permanent magnet type three-phase (U-phase, V-phase, W-phase) AC rotating electrical machines including a rotor in which permanent magnets are embedded. The rotation shaft 21 of the first MG 20 is disposed coaxially with the crankshaft of the engine 10. The rotation shaft 31 of the second MG 30 is arranged in parallel with the rotation shaft 21 of the first MG 20. The counter shaft (output shaft) 70 is arranged in parallel with the rotation shaft 21 of the first MG 20 and the rotation shaft 31 of the second MG 30.

  First MG 20 and second MG 30 are driven by inverters 25 and 35, respectively. Inverter 25 is controlled by a control signal from control device 100, converts DC power from a vehicle battery (not shown) into three-phase AC power, and supplies the same to first MG 20. Similarly, inverter 35 is controlled by a control signal from control device 100, converts DC power from an in-vehicle driving battery (not shown) into three-phase AC power, and supplies the same to second MG 30. The second MG 30 is also driven by the electric power generated by the first MG 20.

  The transmission 40 is provided between the engine 10 and the differential device 50, changes the rotation of the engine 10, and outputs it to the differential device 50. The transmission 40 includes a single pinion planetary gear mechanism including a sun gear S1, a pinion gear P1, a ring gear R1, and a carrier CA1, a clutch C1, and a brake B1.

  Carrier CA1 is coupled to the crankshaft of engine 10. The pinion gear P1 is disposed between the sun gear S1 and the ring gear R1, and meshes with the sun gear S1 and the ring gear R1, respectively. Pinion gear P1 is supported by carrier CA1 so as to be capable of rotating and revolving.

  The rotational speed of the sun gear S1, the rotational speed of the carrier CA1 (that is, the rotational speed of the engine 10), and the rotational speed of the ring gear R1, as will be described later, are related by a straight line on the nomograph (that is, any two rotations). If the speed is determined, the remaining rotational speed is also determined).

  The clutch C1 is a hydraulic friction engagement element capable of connecting the sun gear S1 and the carrier CA1. When the clutch C1 is engaged, the sun gear S1 and the carrier CA1 are connected. When the clutch C1 is released, the sun gear S1 and the carrier CA1 are disconnected.

  The brake B1 is a hydraulic friction engagement element that can restrict (lock) the rotation of the sun gear S1. When the brake B1 is engaged, the sun gear S1 is fixed to the gear case (vehicle body), so that the rotation of the sun gear S1 is restricted. When the brake B1 is released, the sun gear S1 is disconnected from the gear case (vehicle body), so that the sun gear S1 is allowed to rotate.

  The speed ratio of the transmission 40 (the ratio between the rotational speed of the carrier CA1 as an input element and the rotational speed of the ring gear R1 as an output element, specifically, the rotational speed of the carrier CA1 / the rotational speed of the ring gear R1) is determined by the clutch C1. And switching according to the combination of engagement and release of the brake B1. When the clutch C1 is engaged and the brake B1 is released, a low gear stage Lo having a gear ratio of 1.0 (directly connected state) is formed. When the clutch C1 is released and the brake B1 is engaged, a high gear stage Hi is formed in which the gear ratio becomes a value smaller than 1.0 (for example, 0.7, so-called overdrive state). Note that when the clutch C1 is engaged and the brake B1 is engaged, the rotation of the sun gear S1 and the carrier CA1 is restricted, so that the rotation of the ring gear R1 is also restricted.

  The differential device 50 is a single pinion type planetary gear device including a sun gear S2, a pinion gear P2, a ring gear R2, and a carrier CA2. The carrier CA2 of the differential device 50 is connected to a ring gear R1 that is an output element of the transmission 40, and rotates integrally with the ring gear R1.

  Pinion gear P2 is arranged between sun gear S2 and ring gear R2, and meshes with sun gear S2 and ring gear R2, respectively. Pinion gear P2 is supported by carrier CA2 so as to be capable of rotating and revolving.

  Sun gear S2 is coupled to rotating shaft 21 of first MG 20. A counter drive gear 51 is connected to the ring gear R2. The counter drive gear 51 is an output gear of the differential device 50 that rotates integrally with the ring gear R2.

  As described later, the rotational speed of the sun gear S2 (that is, the rotational speed of the first MG 20), the rotational speed of the carrier CA2, and the rotational speed of the ring gear R2 are connected in a straight line on the nomograph (that is, any two rotations). If the speed is determined, the remaining rotational speed is also determined). Therefore, by adjusting the rotation speed of the first MG 20, the ratio between the rotation speed of the carrier CA2 and the ring gear R2 can be switched steplessly.

  The counter shaft (output shaft) 70 is provided with a driven gear 71 and a drive gear 72. The driven gear 71 meshes with the counter drive gear 51 of the differential device 50. The power of the engine 10 and the first MG 20 is transmitted to the counter shaft (output shaft) 70 via the counter drive gear 51 of the differential device 50.

  The transmission device 40 and the differential device 50 are connected in series on a power transmission path from the engine 10 to the counter shaft (output shaft) 70. Therefore, the rotation of the engine 10 is transmitted to the counter shaft (output shaft) 70 after being shifted by the transmission 40 and the differential device 50.

  The driven gear 71 also meshes with the reduction gear 32 connected to the rotation shaft 31 of the second MG 30. That is, the power of the second MG 30 is transmitted to the counter shaft (output shaft) 70 via the reduction gear 32.

  The drive gear 72 meshes with the diff ring gear 81 of the differential gear 80. The differential gear 80 is connected to the left and right drive wheels 90 via left and right drive shafts 82, respectively. That is, the rotation of the counter shaft (output shaft) 70 is transmitted to the left and right drive shafts 82 via the differential gear 80.

  The vehicle 1 includes an electric oil pump (hereinafter also referred to as “EOP”) 61, a mechanical oil pump (hereinafter also referred to as “MOP”) 62, and a hydraulic circuit 63 as a configuration for driving the transmission 40. The EOP 61 is driven by a motor (hereinafter also referred to as “internal motor”) provided therein, generates hydraulic pressure, and supplies it to the hydraulic circuit 63. The internal motor of the EOP 61 is controlled by a control signal from the control device 100. The MOP 62 is connected to the carrier CA2 of the differential device 50 and is operated by the power transmitted from the carrier CA2 to generate hydraulic pressure. Therefore, when the carrier CA2 is rotated, the MOP 62 is also operated, and when the carrier CA2 is stopped, the MOP 62 is also stopped.

  The hydraulic circuit 63 uses a hydraulic pressure supplied from at least one of the EOP 61 and the MOP 62 as a source pressure, and supplies a hydraulic pressure (hereinafter also referred to as “C1 hydraulic pressure”) to the clutch C1 of the transmission 40 and a hydraulic pressure (hereinafter referred to as “C1 hydraulic pressure”) to the brake B1. (Also referred to as “B1 oil pressure”). Each solenoid valve for driving the clutch C1 and the brake B1 in the hydraulic circuit 63 is controlled by a control signal from the control device 100.

[Configuration of control device]
FIG. 2 is a block diagram showing the configuration of the control device 100 in FIG. Control device 100 includes an HVECU (Electric Control Unit) 150, MGECU 160, and engine ECU 170. Each of HVECU 150, MGECU 160, and engine ECU 170 is an electronic control unit including a computer. Note that the number of ECUs is not limited to three, and may be integrated into one ECU as a whole, or may be divided into two or four or more numbers.

  The MGECU 160 controls the first MG 20 and the second MG 30. For example, the MGECU 160 controls the output torque of the first MG 20 by adjusting the current value supplied to the first MG 20, and controls the output torque of the second MG 30 by adjusting the current value supplied to the second MG 30. .

  The engine ECU 170 controls the engine 10. The engine ECU 170 performs, for example, control of the opening degree of the electronic throttle valve of the engine 10, engine ignition control by outputting an ignition signal, fuel injection control to the engine 10, and the like. The engine ECU 170 controls the output torque of the engine 10 by electronic throttle valve opening control, injection control, ignition control, and the like.

  The HVECU 150 performs integrated control of the entire vehicle. A vehicle speed sensor, an accelerator opening sensor, an MG1 rotation speed sensor, an MG2 rotation speed sensor, an output shaft rotation speed sensor, a battery sensor, and the like are connected to the HVECU 150. With these sensors, the HVECU 150 causes the vehicle speed, the accelerator opening, the rotational speed (rotational speed) of the first MG 20, the rotational speed (rotational speed) of the second MG 30, the rotational speed (rotational speed) of the output shaft of the power transmission device, for driving The battery's SOC (State Of Charge) or the like is acquired.

  Further, a mode select switch, an MG1 temperature sensor, an MG2 temperature sensor, an oil temperature sensor, an outside air temperature sensor, an inclination sensor, and the like are connected to the HVECU 150. With these sensors, the HVECU 150 causes the mode requested by the user, the temperature of the first MG 20, the temperature of the second MG 30, the temperature of the oil supplied to the clutch C 1 and the brake B 1 of the transmission 40 (hereinafter also simply referred to as “oil temperature”). ), Obtain outside air temperature, road slope, etc.

  The HVECU 150 calculates a required driving force, a required driving torque, and the like for the vehicle based on the acquired information. Based on the calculated required value, HVECU 150 outputs torque of first MG 20 (hereinafter also referred to as “MG1 torque”), output torque of second MG 30 (hereinafter also referred to as “MG2 torque”), and engine 10. The output torque (hereinafter also referred to as “engine torque”) is determined. HVECU 150 outputs a command value for MG1 torque and a command value for MG2 torque to MGECU 160. Further, HVECU 150 outputs an engine torque command value to engine ECU 170.

  The HVECU 150 controls the clutch C1 and the brake B1 of the transmission 40 according to a travel mode described later. HVECU 150 outputs C1 oil pressure command value PbC1 and B1 oil pressure command value PbB1 to the solenoid valve of hydraulic circuit 63 in FIG.

[Driving mode of vehicle 1]
The control device 100 causes the vehicle 1 to travel in a hybrid travel mode (hereinafter referred to as “HV travel mode”) or a motor travel mode (hereinafter referred to as “EV travel mode”). The HV travel mode is a travel mode in which the vehicle 1 travels with the power of the engine 10 and the second MG 30. The EV travel mode is a travel mode in which the engine 10 is stopped and the vehicle 1 is traveled by at least one power of the first MG 20 or the second MG 30.

  The EV travel mode is further subdivided into a single motor travel mode and a dual motor travel mode. The single motor travel mode is a travel mode in which the vehicle 1 travels with the power of the second MG 30 alone. The both motor travel mode is a travel mode in which the vehicle 1 travels with the power of both the first MG 20 and the second MG 30.

  FIG. 3 is a diagram showing an operation engagement table of the clutch C1 and the brake B1 of the transmission 40 in each travel mode. In FIG. 2, “C1”, “B1”, “MG1”, and “MG2” indicate the clutch C1, the brake B1, the first MG20, and the second MG30, respectively. The circles (◯) in the C1 and B1 columns indicate “engaged”, the “×” indicates “released”, and the triangle (Δ) indicates either the clutch C1 or the brake B1 during engine braking. Indicates that Further, “G” in the MG1 column and MG2 column indicates that the operation is mainly performed as a generator, and “M” indicates that the operation is mainly performed as a motor.

  In the HV traveling mode, the control device 100 switches the gear ratio of the transmission 40 according to the vehicle speed. When the vehicle 1 is moved forward in the middle / low speed range or when the vehicle 1 is moved backward, the control device 100 forms the low gear stage Lo by engaging the clutch C1 and releasing the brake B1 (see FIG. 4 described later). ). On the other hand, when the vehicle 1 is advanced in the high speed range, the control device 100 forms the high gear stage Hi by releasing the clutch C1 and engaging the brake B1 (see FIG. 5 described later). Further, in the HV traveling mode, control device 100 operates first MG 20 mainly as a generator, and operates second MG 20 mainly as a motor.

  In the EV travel mode, the control device 100 selectively switches between the single motor travel mode and the both motor travel mode described above.

  When a driving force (a force for moving forward or backward) is applied to the vehicle 1 in the single motor traveling mode, the control device 100 releases the clutch C1 and releases the brake B1, thereby setting the transmission device 40 in a neutral state (power is applied). State of not transmitting). On the other hand, when the engine brake is applied to the vehicle 1 in the single motor travel mode, the control device 100 engages either the clutch C1 or the brake B1. As a result, the rotation of the drive wheel 90 is transmitted to the engine 10, thereby causing a so-called engine brake state in which the engine 10 is rotated. In the single motor travel mode, control device 100 operates first MG 20 mainly as a generator and second MG 20 mainly as a motor (see FIG. 6 described later).

  When the vehicle 1 travels (forwards or reverses) in the dual motor travel mode, the control device 100 regulates (locks) the rotation of the ring gear R1 of the transmission 40 by engaging the clutch C1 and engaging the brake B1. To do. Thereby, the rotation of the carrier CA2 of the differential gear 50 connected to the ring gear R1 of the transmission 40 is also restricted (locked). Then, control device 100 operates first MG 20 and second MG 20 mainly as motors (see FIG. 7 described later).

  4 to 7 are alignment charts during the HV traveling mode (low gear stage Lo), during the HV traveling mode (high gear stage Hi), during the single motor traveling mode, and during both motor traveling modes, respectively. 4 to 7, “S1”, “CA1”, and “R1” respectively indicate the sun gear S1, the carrier CA1, and the ring gear R1 of the transmission 40, and “S2”, “CA2”, and “R2” indicate differential devices, respectively. 50 sun gear S2, carrier CA2, and ring gear R2 are shown.

  With reference to FIG. 4, the control state in the case of traveling forward at the low gear stage Lo during the HV traveling mode will be described. When the low gear stage Lo is formed, the clutch C1 is engaged and the brake B1 is released, so that the rotation elements S1, CA1, R1 of the transmission 40 rotate together. Thereby, the ring gear R1 of the transmission 40 also rotates at the same rotational speed as the carrier CA1, and the rotation of the engine 10 is transmitted from the ring gear R1 to the carrier CA2 of the differential device 50 at the same rotational speed. That is, the torque of the engine 10 (hereinafter referred to as “engine torque Te”) input to the carrier CA1 of the transmission 40 is transmitted from the ring gear R1 of the transmission 40 to the carrier CA2 of the differential device 50. The torque output from the ring gear R1 (hereinafter referred to as “transmission part output torque Tr1”) is the same as the engine torque Te (Te = Tr1) when the low gear stage Lo is formed.

  The rotation of the engine 10 transmitted to the carrier CA2 of the differential device 50 is steplessly changed by the rotational speed of the sun gear S2 (rotational speed of the first MG 20) and transmitted to the ring gear R2 of the differential device 50. At this time, control device 100 causes the torque of first MG 20 (hereinafter referred to as “first MG torque Tm1”) to act in the negative direction. Thereby, the first MG torque Tm1 acts as a reaction torque for transmitting the engine torque Te input to the carrier CA2 to the ring gear R2.

  Engine torque Te transmitted to ring gear R2 (hereinafter referred to as “engine transmission torque Tec”) is transmitted from counter drive gear 51 to counter shaft (output shaft) 70 and acts as a driving force for vehicle 1.

  Further, the torque of the second MG 30 (hereinafter referred to as “second MG torque Tm2”) is transmitted from the reduction gear 32 to the counter shaft (output shaft) 70 and acts as a driving force of the vehicle 1. Therefore, in the HV traveling mode, the vehicle 1 travels using the engine transmission torque Tec and the second MG torque Tm2.

  Next, with reference to FIG. 5, the control state when the vehicle is traveling forward at the high gear stage Hi during the HV traveling mode will be described. Since the brake B1 is engaged when the high gear stage Hi is formed, the rotation of the sun gear S1 is restricted. Accordingly, the rotation of the engine 10 input to the carrier CA1 of the transmission 40 is increased and transmitted from the ring gear R1 of the transmission 40 to the carrier CA2 of the differential device 50. Therefore, the transmission output torque Tr1 is smaller than the engine torque Te (Te> Tr1).

  Next, with reference to FIG. 6, the control state in the case of traveling forward during the single motor traveling mode will be described. In the single motor travel mode, control device 100 stops engine 10 and operates second MG 30 as a motor. Therefore, in the single motor travel mode, the vehicle 1 travels using the second MG torque Tm2.

  At this time, control device 100 feedback-controls first MG torque Tm1 so that the rotational speed of sun gear S2 becomes zero. Therefore, the sun gear S2 does not rotate. On the other hand, since the clutch C1 and the brake B1 of the transmission 40 are released, the rotation of the carrier CA2 of the differential device 50 is not restricted. Therefore, ring gear R2 of differential device 50, carrier CA2 and ring gear R1 of transmission 40 are rotated (idled) in the same direction as the rotation direction of second MG 30 in conjunction with the rotation of second MG 30.

  On the other hand, the carrier CA1 of the transmission 40 is maintained in a stopped state when the engine 10 is stopped. The sun gear S1 of the transmission 40 is rotated (idled) in a direction opposite to the rotation direction of the ring gear R1 in conjunction with the rotation of the ring gear R1.

  Next, with reference to FIG. 7, the control state in the case of traveling forward during the both-motor traveling mode will be described. In the both-motor running mode, the control device 100 stops the engine 10, engages the clutch C1 of the transmission 40, and engages the brake B1. Thereby, rotation of the sun gear S1, the carrier CA1, and the ring gear R1 of the transmission 40 is restricted. By restricting the rotation of the ring gear R1 of the transmission 40, the rotation of the carrier CA2 of the differential device 50 is also restricted (locked). In the following description, the control for locking (fixing) the carrier CA2 of the differential device 50 by engaging the friction engagement elements (the clutch C1 and the brake B1) of the transmission 40 is also referred to as “fixing control”.

  In a state where carrier CA2 is fixed by the fixing control, control device 100 operates first MG 20 and second MG 30 as motors. Specifically, the second MG 30 is rotated positively using the second MG torque Tm2 as a positive torque, and the first MG 20 is rotated negatively using the first MG torque Tm1 as a negative torque. First MG torque Tm1 is transmitted to ring gear R2 using carrier CA2 as a fulcrum. First MG torque Tm1 (hereinafter referred to as “first MG transmission torque Tm1c”) transmitted to ring gear R2 acts in the positive direction and is transmitted to counter shaft (output shaft) 70. Therefore, in both motor travel modes, vehicle 1 travels using first MG transmission torque Tm1c and second MG torque Tm2.

  Control device 100 adjusts the torque sharing ratio between first MG torque Tm1 and second MG torque Tm2 with respect to the required drive torque so that the required torque is satisfied by the sum of first MG transmission torque Tm1c and second MG torque Tm2.

[Switch driving mode]
When the SOC of the drive battery is lower than the threshold value, the control device 100 operates the engine 10 to charge the drive battery and causes the vehicle 1 to travel in the HV travel mode. On the other hand, when the SOC of the driving battery is higher than the threshold value, control device 100 switches the traveling mode of vehicle 1 based on the vehicle speed and the required driving force.

  FIG. 8 is a diagram illustrating a correspondence relationship between the vehicle speed, the required driving force, and the traveling mode when the SOC of the driving battery is higher than the threshold value. In FIG. 8, the boundary line L <b> 1 corresponds to the output possible driving force of the second MG, and the boundary line L <b> 2 corresponds to the sum of the output possible driving force of the first MG 20 and the output possible driving force of the second MG 30.

  In the region below the boundary line L1, the required driving force can be output by the second MG 30 alone. Therefore, the control device 100 causes the vehicle 1 to travel in the single motor travel mode.

  In the region exceeding the boundary line L1 and less than the boundary line L2, the second MG 30 alone cannot output the required driving force, but the first MG 20 and the second MG 30 can output the required driving force. Causes the vehicle 1 to travel in both motor travel modes.

  In the region exceeding the boundary line L2, the required driving force cannot be output by both the first MG 20 and the second MG 30, so the control device 100 causes the vehicle 1 to travel in the HV traveling mode.

[Both motor running by differential rotation control]
In the vehicle 1 having the above-described configuration, the carrier of the differential device 50 is controlled by the above-described fixing control (control for engaging the clutch C1 and the brake B1 of the transmission 40) during the both-motor traveling mode. CA2 is fixed.

  The operating device 50 is configured such that when any two rotational speeds of the three rotational elements of the carrier CA2, the sun gear S2, and the ring gear R2 are determined, the remaining one rotational speed is determined. For this reason, when the vehicle 1 stops while both motors are driven by the fixed control, the rotation of the ring gear R2 in addition to the carrier CA2 of the differential device 50 is also restricted, so that the remaining sun gear S2 is also restricted. Therefore, during a period in which torque is output from the first MG 20 and the second MG 30 in a vehicle stop state such as an initial start on an uphill road, the rotation elements CA2, S2, and R2 of the differential device 50 are all fixed to zero and the first MG 20 and Since the rotation of the second MG 30 is restricted, no current phase change occurs in the first MG 20 and the second MG 30 and the current flows in a concentrated manner in only one of the three phases (U phase, V phase, W phase) ( Hereinafter also referred to as “single phase lock”. If the single-phase lock continues, the thermal load on inverters 25 and 35 that drive first MG 20 and second MG 30, and further, first MG 20 and second MG 30 may increase.

  Therefore, the control device 100 according to the present embodiment determines whether or not the above-described single-phase lock is generated or whether or not the above-described single-phase lock is predicted to occur during both-motor driving by the fixed control. (Hereinafter referred to as “single-phase lock determination process”). When it is determined by the single-phase lock determination process that single-phase lock has occurred or single-phase lock is predicted to occur, the control device 100 executes “differential rotation control” instead of fixed control. Thus, the single-phase lock of the first MG 20 is avoided. “Differential rotation control” means that the clutch C1 or the brake B1 of the transmission 40 is changed to the half-engaged state (slip state) while suppressing the fluctuation of the vehicle driving force by the output of the first MG 20. This is control that allows rotation of the carrier CA2. Hereinafter, the differential rotation control will be described in detail.

  9 and 10 are collinear diagrams in the case where the vehicle moves forward while the two motors are running under the differential rotation control. FIG. 9 shows a case where the brake B1 is slipped by reducing the B1 hydraulic pressure to a predetermined slip pressure while the clutch C1 is engaged. FIG. 10 shows a case where the clutch C1 is slipped by reducing the C1 hydraulic pressure to a predetermined slip pressure while the brake B1 is engaged.

  In any case, by performing differential rotation control during forward traveling in the both-motor traveling mode, the difference between the carrier CA2 of the differential device 50 in accordance with the slip amount (slip amount) of the clutch C1 or the brake B1. It rotates slightly in the negative direction at the rotational speed ΔN. Thereby, even if the rotation of the ring gear R2 is restricted when the vehicle is stopped on an uphill road or the like, the sun gear S2 can be rotated. Therefore, when a single-phase lock has occurred in the first MG 20, it can be released from the single-phase lock. Moreover, when it is predicted that single phase lock will occur in the first MG 20, it is possible to avoid falling into single phase lock in advance by performing differential rotation control in advance.

  11 and 12 are collinear diagrams in the case where the vehicle travels backward while both motors are running under the differential rotation control. FIG. 11 shows a case where the brake B1 is slipped by reducing the B1 hydraulic pressure to a predetermined slip pressure while the clutch C1 is engaged. FIG. 12 shows a case where the clutch C1 is slipped by reducing the C1 hydraulic pressure to a predetermined slip pressure while the brake B1 is engaged.

  In any case, the differential rotation control is executed during reverse traveling in the both-motor traveling mode, so that the difference between the carrier CA2 of the differential device 50 and the slip amount (slip amount) of the clutch C1 or the brake B1. It rotates slightly in the positive direction at the rotational speed ΔN. Accordingly, as in the case described with reference to FIGS. 9 and 10, the sun gear S <b> 2 can be rotated even if the rotation of the ring gear R <b> 2 is restricted, so that the single-phase lock of the first MG 20 can be avoided.

  Further, as shown in FIGS. 11 and 12, when the differential rotation control is executed during the reverse travel of both motors, the carrier CA1 (that is, the engine 10) of the transmission 40 is rotated in the positive direction in advance. Therefore, when starting the engine 10, it is not necessary to crank the engine 10 separately, and the start response can be improved.

  During the differential rotation control, the friction engagement element (clutch C1 or brake B1) of the transmission 40 is not completely released but is in a slip state and has a torque capacity corresponding to a predetermined slip pressure. doing. Therefore, the rotation of the carrier CA2 can be allowed while acting the carrier CA2 as a fulcrum for transmitting the first MG torque Tm1 to the ring gear R2.

  Further, during the differential rotation control, the control device 100 outputs the output of the first MG 20 so as to suppress fluctuations in the vehicle driving force while maintaining the hydraulic pressure supplied to the friction engagement element to be slipped at a predetermined slip hydraulic pressure. adjust. Specifically, control device 100 feedback-controls first MG torque Tm1 so that the rotation speed of first MG 20 becomes a predetermined target rotation speed. As another method for suppressing the fluctuation of the vehicle driving force, a method of feedback controlling the rotational speed of the first MG 20 may be adopted so that the first MG torque Tm1 becomes a predetermined target torque. By such output adjustment of the first MG 20, the torque and rotational speed transmitted to the output shaft 70 are kept constant, and fluctuations in the vehicle driving force are suppressed.

  The friction engagement element to be slipped during the differential rotation control may be the brake B1 or the clutch C1. Therefore, the friction engagement element to be slipped may be fixed to one of the brake B1 and the clutch C1, and the brake B1 and the clutch C1 may be switched periodically in consideration of durability and the like. Below, the case where the friction engagement element made to slip during differential rotation control is made into brake B1 is illustrated exemplarily.

  FIG. 13 is a flowchart illustrating a processing procedure when the control device 100 executes the differential rotation control. This flowchart is repeatedly executed at a predetermined cycle.

  In step (hereinafter, step is abbreviated as “S”) 10, control device 100 determines whether or not both motors are running. If both motors are not traveling (NO in S10), control device 100 ends the process.

  When both motors are running (YES in S10), in S11, control device 100 performs the above-described single-phase lock determination process. Specifically, control device 100 determines whether or not a single-phase lock has occurred and whether or not a single-phase lock is predicted to occur.

  For example, control device 100 determines that a single-phase lock has occurred when current is continuously flowing to at least one of first MG 20 and second MG 30G while the vehicle is stopped during fixed control. Control device 100 determines that a single-phase lock is predicted to occur, for example, when the road surface gradient is equal to or higher than a predetermined value and the vehicle speed is lower than a predetermined value during fixed control.

  When single-phase lock has not occurred and it is not predicted that single-phase lock will occur (NO in S11), control device 100 continues the above-described fixed control in S15. That is, the control device 100 maintains the fixed state of the carrier CA2 of the differential device 50 by maintaining the state where the clutch C1 of the transmission 40 is engaged and the brake B1 is engaged (see FIG. 7 described above). .

  When single-phase lock has occurred or when it is predicted that single-phase lock will occur (YES in S11), in S12, control device 100 includes the oil temperature in the range from lower limit temperature TL to upper limit temperature TH. It is determined whether or not. This determination is a process for determining whether or not the oil temperature is a temperature suitable for differential rotation control. That is, when the oil temperature is lower than the lower limit temperature TL, the viscosity of the oil is high, the controllability when the brake B1 is brought into the slip state by the differential rotation control is deteriorated, and the brake B1 is in the planned slip state. You may not be able to do it. Further, when the oil temperature is higher than the upper limit temperature TH, the durability of the brake B1 may be deteriorated due to a thermal load when the brake B1 is brought into the slip state by the differential rotation control. Considering these, in the present embodiment, the execution of the differential rotation control is limited in accordance with the oil temperature in consideration of the controllability of the differential rotation control and the durability of the brake B1.

  If the oil temperature is not included in the range from the lower limit temperature TL to the upper limit temperature TH (NO in S12), the oil temperature is not a temperature suitable for the differential rotation control. Continue fixed control. However, the control device 100 limits the upper limit values of the currents of the first MG 20 and the second MG 30 in order to reduce the thermal load due to the single-phase lock, compared to the case where the fixed control is executed in S15.

  When oil temperature is included in the range from lower limit temperature TL to upper limit temperature TH (YES in S12), since oil temperature is a temperature suitable for differential rotation control, control device 100 performs fixed control in S13. Instead, the above-described differential rotation control is executed. That is, the control device 100 reduces the B1 hydraulic pressure to a predetermined slip pressure while keeping the clutch C1 engaged, and changes the brake B1 to the half-engaged state while suppressing the fluctuation of the vehicle driving force by the output of the first MG 20. . Thereby, rotation of carrier CA2 of differential device 50 is permitted, and a single phase lock can be avoided, suppressing change in vehicle driving force.

  FIG. 14 is a diagram schematically illustrating a change in the control state when switching from both motor traveling by fixed control to both motor traveling by differential rotation control. The time is shown on the horizontal axis of FIG. 14, and the vertical axis shows the engine speed (rotation speed of the engine 10), MG1 torque (first MG torque Tm1), MG1 speed (rotation speed of the first MG20), The states of MG2 torque (second MG torque Tm2), MG2 rotation speed (rotational speed of second MG30), C1 hydraulic pressure, B1 hydraulic pressure, and differential rotation control are shown.

  Prior to time t1, the C1 hydraulic pressure and the B1 hydraulic pressure are maintained at the engagement pressure by the fixing control, respectively, and the clutch C1 and the brake B1 are completely engaged.

  If it is predicted that a single-phase lock will occur at time t1, differential rotation control is started and the B1 hydraulic pressure starts to decrease, and a predetermined slip pressure is reached at time t2. As a result, the brake B1 enters the slip state and the rotation of the carrier CA2 is allowed, so that even if the rotation of the ring gear R2 is restricted while the vehicle is stopped, the sun gear S2 can be rotated. Therefore, it is possible to avoid in advance that the first MG 20 falls into a single-phase lock.

  After time t2, the MG1 torque is feedback-controlled so that the MG1 rotation speed becomes constant at a predetermined target rotation speed while the B1 oil pressure is maintained at a predetermined slip pressure. Thereby, the fluctuation | variation of the vehicle driving force by differential rotation control can be suppressed appropriately.

  As described above, the control device 100 according to the present embodiment performs the above-described differential rotation control while both motors are running under the fixed control, thereby suppressing the fluctuation of the vehicle driving force and the thermal load due to the single-phase lock. Can be reduced.

The above-described embodiment can be modified as follows, for example.
<Modification 1>
In the above-described embodiment, in the single-phase lock determination process, it is determined that a single-phase lock has occurred when current is continuously supplied to at least one of the first MG 20 and the second MG 30G while the vehicle is stopped during the fixed control. Explained when to do. However, the method for determining the presence or absence of single-phase lock is not limited to the method described in the above embodiment.

  For example, when single-phase lock occurs, the ambient temperature of each MG tends to increase more rapidly than normal driving (when single-phase lock is not generated) due to current concentration. Therefore, the presence / absence of single-phase lock is determined based on the rate of temperature increase (the amount of increase per unit time) of the first MG 20, the second MG 30, the inverters 25 and 35, the power cable connecting each MG and each inverter, and the like. You may do it.

  FIG. 15 is a flowchart illustrating a processing procedure of the control device 100 when the differential rotation control is executed based on the result of determining the presence or absence of the single-phase lock based on the temperature increase rates of the first MG 20 and the second MG 30. Of the steps shown in FIG. 15, the steps given the same numbers as the steps shown in FIG. 13 described above have already been described, and detailed description thereof will not be repeated here.

  When the oil temperature is included in the range from the lower limit temperature TL to the upper limit temperature TH while both motors are running (YES in S10 and YES in S12), the controller 100 determines that the temperature increase rate of the first MG 20 is S20. It is determined whether or not it is less than a reference value, and it is determined in S21 whether or not the temperature increase rate of the second MG 30 is less than the reference value.

  When temperature increase rate of first MG 20 is less than the reference value and temperature increase rate of second MG 30 is also less than the reference value (YES in S20 and YES in S21), control device 100 causes single-phase lock. In step S15, the fixed control is continued.

  On the other hand, when the temperature increase rate of first MG 20 is equal to or higher than the reference value (NO in S20), or when the temperature increase rate of second MG 30 is equal to or higher than the reference value (NO in S21), control device 100 is a single phase. It is determined that lock has occurred, and differential rotation control is executed instead of fixed control in S13.

  When executing the differential rotation control in S13, the control device 100 determines in S23 whether or not the duration of the differential rotation control is greater than or equal to a reference value. If the duration of differential rotation control is greater than or equal to the reference value (YES in S23), the friction engagement element (clutch C1 or brake B1) that enters the slip state may generate heat and controllability and durability may deteriorate. Therefore, the control device 100 moves the process to S15 and switches to fixed control.

  As described above, the presence / absence of the single-phase lock may be determined based on the temperature increase rate of the first MG 20 and the second MG 30.

<Modification 2>
The absolute value of the rotation speed of the carrier CA2 during the differential rotation control (differential rotation speed ΔN), or the engagement torque of the friction engagement element that is brought into a half-engaged state by the differential rotation control (hereinafter also referred to as “half-engagement torque”). ) May be changed according to the oil temperature.

  FIG. 16 is a diagram illustrating an example of the relationship between the oil temperature and the allowable range of the differential rotation speed ΔN. As shown in FIG. 16, in the region where the oil temperature is high, the differential rotation speed ΔN is reduced by narrowing the allowable range of the differential rotation speed ΔN in accordance with the increase in the oil temperature. Thereby, the durable fall of the friction engagement element by overheating can be suppressed. In the region where the oil temperature is low, the differential rotational speed ΔN is reduced by narrowing the allowable range of the differential rotational speed ΔN according to the decrease in the oil temperature. Thereby, the destabilization of controllability caused by the low oil temperature can be suppressed as much as possible.

  Although not shown in FIG. 16, when the oil temperature is low, by increasing the allowable range of the differential rotation speed ΔN, it is possible to realize early warm-up with the heat generated by the slip of the friction engagement element. Also good.

<Modification 3>
The differential rotation speed ΔN or the half-engagement torque may be changed according to the time during which both motors are running or the time during which the differential rotation control is continued.

  For example, the differential rotation speed ΔN may be decreased as the time during which the differential rotation control is continued is longer. Thereby, overheating of the frictional engagement element that is brought into the slip state by the differential rotation control can be suppressed, and the frictional engagement element can be protected.

  Further, for example, the difference rotational speed ΔN may be increased as the time during which both motors are driven by the fixed control is longer. That is, normally, the lubricating oil is supplied to the pinion gear P2 of the differential device 50 by using the centrifugal force of the carrier CA2 to blow the lubricating oil in the radial direction from the shaft. Since the carrier CA2 is fixed while the two motors are driven by the fixing control, the above-described operation cannot be obtained, and the lubricating oil cannot be supplied to the pinion gear P2. Further, since the MOP 62 is stopped by fixing the carrier CA2, there is a concern that the lubricating oil in the differential device 50 is insufficient. Therefore, when the two-motor traveling by the fixed control is switched to the two-motor traveling by the differential rotation control, the difference rotational speed ΔN by the differential rotation control is increased as the time during which the both motor traveling by the fixed control is continued is longer. You may do it. Thereby, since rotation of carrier CA2 can be accelerated | stimulated and supply of the lubricating oil to pinion gear P2 can be accelerated | stimulated, the lack of lubricating oil of pinion gear P2 can be eliminated.

<Modification 4>
During both motor traveling by the differential rotation control, the torque sharing ratio of the first MG 20 with respect to the required drive torque may be made higher than during both motor traveling by the fixed control. By increasing the torque sharing ratio of the first MG 20, the torque sharing ratio of the second MG 30 is lowered, so that the current flowing through the second MG 30 is also lowered. Therefore, the heat load of the second MG 30 can be suitably reduced while maintaining the vehicle driving torque.

<Modification 4>
In the above-described embodiment, the case where the “transmission unit 40” capable of changing the transmission gear ratio is used as a means for fixing or allowing the rotation of the carrier CA2 of the differential device 50 during the traveling of both motors. .

  However, the means for fixing or allowing the rotation of the carrier CA2 does not necessarily have to change the gear ratio. For example, instead of or in addition to the transmission unit 40, a brake element for fixing the carrier CA2 of the differential device 50 is added, and the rotation of the carrier CA2 is fixed or permitted by using this brake element during traveling of both motors. You may make it.

The above-described embodiment and its modifications can be combined as appropriate.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 vehicle, 10 engine, 20 1st MG, 30 2nd MG, 25, 35 inverter, 32 reduction gear, 40 transmission, 50 actuator, 51 counter drive gear, 61 EOP, 62 MOP, 63 hydraulic circuit, 70 output shaft, 71 driven gear, 72 drive gear, 80 differential gear, 81 differential ring gear, 82 drive shaft, 90 drive wheel, 100 control device, B1 brake, C1 clutch, CA1, CA2 carrier, P1, P2 pinion gear, R1, R2 ring gear, S1, S2 Sun gear.

Claims (5)

A drive device for a vehicle that travels using the output of at least one of an engine, a first motor generator, and a second motor generator,
A first rotating element connected to the engine; a second rotating element connected to the first motor generator; and a third rotating element connected to the second motor generator and drive wheels; A differential configured to determine the remaining one rotation speed when any two rotation speeds of the first to third rotation elements are determined; and
A friction engagement device for fixing the first rotating element of the differential;
In the two-motor running mode in which the engine is stopped and the vehicle is driven using the outputs of both the first and second motor generators, the friction engagement device is brought into the engaged state. A control device that executes with the rotating element fixed,
The control device determines whether the first and second motor generators are in a locked state in which the first and second motor generators do not rotate even when current is supplied to the first and second motor generators during the both motor travel modes, When it is determined that it is in the locked state, the differential rotation control is executed while maintaining the both motor travel modes,
The differential rotation control is a control that allows the rotation of the first rotation element by setting the friction engagement device in a half-engaged state while suppressing the fluctuation of the vehicle driving force by the output of the first motor generator. Oh it is,
The control device decreases the absolute value of the rotation speed of the first rotation element during the differential rotation control as the time during which the differential rotation control is continued is longer . A drive device for a vehicle that travels using the output of at least one of an engine, a first motor generator, and a second motor generator,
A first rotating element connected to the engine; a second rotating element connected to the first motor generator; and a third rotating element connected to the second motor generator and drive wheels; A differential configured to determine the remaining one rotation speed when any two rotation speeds of the first to third rotation elements are determined; and
A friction engagement device for fixing the first rotating element of the differential;
In the two-motor running mode in which the engine is stopped and the vehicle is driven using the outputs of both the first and second motor generators, the friction engagement device is brought into the engaged state. A control device that executes with the rotating element fixed,
The control device determines whether the first and second motor generators are in a locked state in which the first and second motor generators do not rotate even when current is supplied to the first and second motor generators during the both motor travel modes, When it is determined that it is in the locked state, the differential rotation control is executed while maintaining the both motor travel modes,
The differential rotation control is a control that allows the rotation of the first rotation element by setting the friction engagement device in a half-engaged state while suppressing the fluctuation of the vehicle driving force by the output of the first motor generator. Yes,
The control device increases the absolute value of the rotation speed of the first rotation element during execution of the differential rotation control as the time during which the first rotation element is maintained in the fixed state before execution of the differential rotation control is longer. A vehicle drive device that increases the size of the vehicle. The vehicle includes an electric device for driving the first and second motor generators,
The controller controls the amount of increase in the temperature of the first motor generator per unit time, the amount of increase in the temperature of the second motor generator per unit time, and the temperature of the electric device during the both motor travel modes. based on at least one of the amount of increase per unit time, it determines whether the is in the locked state, the vehicle driving apparatus according to claim 1 or 2. 4. The control device according to claim 1, wherein the control device decreases the absolute value of the rotation speed of the first rotation element during the differential rotation control as the temperature of the oil supplied to the friction engagement device is higher . The vehicle drive device described in 1. The controller, when executing the differential speed control, than without running the differential speed control, increasing the torque sharing ratio of the first motor-generator to the request driving torque, claim 1-4 The vehicle drive device described in 1.

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