JP2017100473A - Motor assist control device of hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor assist control device of a hybrid vehicle capable of executing assist in a more efficient vehicle speed region by stable motor torque.SOLUTION: A motor assist control device of a hybrid vehicle includes an assist determination section 72 for determining permission or prohibition of assist by a motor generator 4 on the basis of discharge power calculated on the basis of a charging state of a third electrical storage device 33 and a battery temperature and a vehicle speed. The assist determination section 72 permits the assist by the motor generator 4 in all the vehicle speed regions when the discharge power is a prescribed second power or more, permits the assist by the motor generator 4 in only a prescribed low vehicle speed region when the discharge power is less than a prescribed first power, and permits the assist by the motor generator 4 in only a prescribed middle/low vehicle speed region when the discharge power is the first power or more and less than the second power.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a motor assist control device for a hybrid vehicle.

  In general, a hybrid vehicle includes an engine and a motor driven by electric power supplied from a battery as driving sources, and travels while assisting the engine torque of the engine with the motor torque of the motor.

  As a conventional motor assist device for a hybrid vehicle, one described in Patent Document 1 is known. In the case of the battery described in Patent Document 1, when the battery is charged and close to full charge, the motor actively assists in all the load areas of the engine, and the battery charge is low below a predetermined value. The motor assists only in the high load region of the engine. Thereby, the hybrid vehicle described in Patent Literature 1 can perform a reasonable assist according to the state of charge of the battery.

JP 2012-212062 A

  Here, the battery has a temperature characteristic that discharge power that can be discharged from the battery becomes unstable as the battery temperature (cell temperature or the like) becomes higher. If the discharge power of the battery becomes unstable, the motor torque of the motor becomes unstable, and assistance with stable motor torque cannot be performed.

  However, the device described in Patent Document 1 does not take into consideration the temperature characteristics of the battery, and there is a problem in that it is not possible to perform assist with stable motor torque.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a motor assist control device for a hybrid vehicle capable of performing assist in an efficient vehicle speed range with stable motor torque.

  One aspect of the invention of a motor assist control device for a hybrid vehicle that solves the above problems includes an engine and a motor as drive sources, and when the vehicle accelerates, the motor torque of the motor is applied to the drive wheels to drive the vehicle. A motor assist control device for a hybrid vehicle that assists, a vehicle speed detection unit that detects a vehicle speed, a charge state detection unit that detects a charge state of a battery, a battery temperature detection unit that detects a battery temperature of the battery, A discharge power calculation unit that calculates discharge power that can be discharged by the battery when assisting by the motor based on the charge state detected by the charge state detection unit and the battery temperature detected by the battery temperature detection unit And the discharge power calculated by the discharge power calculation unit and the vehicle speed detected by the vehicle speed detection unit. An assist determination unit that determines permission or prohibition of assist by the motor, and the assist determination unit performs the assist by the motor when the discharge power is greater than or equal to a predetermined second power. When the discharge power is less than a predetermined first power, the motor assists only in a predetermined low vehicle speed range, and the discharge power is not less than the first power and less than the second power. In some cases, the assist by the motor is permitted only in a predetermined low and medium vehicle speed range.

  According to the present invention, it is possible to assist in an efficient vehicle speed range with a stable motor torque.

FIG. 1 is a diagram illustrating a motor assist control device for a hybrid vehicle according to an embodiment of the present invention, and is a configuration diagram of the hybrid vehicle. FIG. 2 is a diagram showing a motor assist control device for a hybrid vehicle according to an embodiment of the present invention, and is a configuration diagram of the motor assist control device. FIG. 3 is a flowchart illustrating an assist determination operation by the motor assist control device for a hybrid vehicle according to the embodiment of the present invention. FIG. 4 is a diagram illustrating the relationship between the vehicle speed and the motor torque in the motor assist control device for a hybrid vehicle according to one embodiment of the present invention. FIG. 5 is a diagram for explaining the relationship among the discharge power, the vehicle speed, and the motor torque in the hybrid vehicle motor assist control device according to the embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. Hereinafter, a vehicle equipped with a drive control device according to an embodiment of the present invention will be described.

  As shown in FIG. 1, the hybrid vehicle 1 includes an engine 2 as an internal combustion engine, a transmission 3, a motor generator 4, drive wheels 5, and an HCU (Hybrid Control Unit) that comprehensively controls the hybrid vehicle 1. 10, an ECM (Engine Control Module) 11 that controls the engine 2, a TCM (Transmission Control Module) 12 that controls the transmission 3, an ISGCM (Integrated Starter Generator Control Module) 13, and an INVCM (Invertor Control Module) 14 And a low voltage BMS (Battery Management System) 15 and a high voltage BMS 16.

  The engine 2 is formed with a plurality of cylinders. In the present embodiment, the engine 2 is configured to perform a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke for each cylinder.

  The engine 2 is connected with an ISG (Integrated Starter Generator) 20 and a starter 21. The ISG 20 is connected to the crankshaft 18 of the engine 2 via a belt 22 or the like. The ISG 20 has a function of an electric motor that starts the engine 2 by rotating when supplied with electric power, and a function of a generator that converts rotational force input from the crankshaft 18 into electric power.

  In this embodiment, the ISG 20 is configured to restart the engine 2 from a stopped state by the idling stop function by functioning as an electric motor under the control of the ISGCM 13. The ISG 20 can also assist the traveling of the hybrid vehicle 1 by functioning as an electric motor.

  The starter 21 includes a motor and a pinion gear (not shown). The starter 21 rotates the crankshaft 18 by rotating the motor to give the engine 2 a starting torque. As described above, the engine 2 is started by the starter 21 and restarted by the ISG 20 from the stop state by the idling stop function.

  The transmission 3 shifts the rotation output from the engine 2 and drives the drive wheels 5 via the drive shaft 23. The transmission 3 includes an always-meshing transmission mechanism 25 including a parallel shaft gear mechanism, a clutch 26 including a dry single-plate clutch, a differential mechanism 27, a clutch actuator 51, and a shift actuator 52. Yes.

  The clutch actuator 51 is configured to connect and disconnect (disconnect and connect) the clutch 26 under the control of the TCM 12. The shift actuator 52 switches a gear position by moving a shift sleeve (not shown) of the transmission mechanism 25 under the control of the TCM 12. Hereinafter, switching the gear stage by disengaging the clutch 26 is also simply referred to as shifting.

  As described above, the transmission 3 is configured as an automatic transmission called AMT (Automated Manual Transmission) that can automatically shift gears under the control of the TCM 12. The differential mechanism 27 is configured to transmit the power output by the speed change mechanism 25 to the drive shaft 23.

  The motor generator 4 is connected to the differential mechanism 27 via a power transmission mechanism 28 such as a chain. The motor generator 4 functions as an electric motor. The motor generator 4 constitutes a motor in the present invention.

  Thus, the hybrid vehicle 1 forms a parallel hybrid system that can use the power of both the engine 2 and the motor generator 4 for driving the vehicle. The hybrid vehicle 1 travels with power generated by at least one of the engine 2 and the motor generator 4.

  The hybrid vehicle 1 assists the engine torque of the engine 2 by using only the engine torque generated by the engine 2, traveling only by the motor torque generated by the motor generator 4 (EV traveling), and using the motor torque as an assist torque. Travel (assist travel) is possible. Thus, the hybrid vehicle 1 has an EV travel function and an assist travel function.

  The motor generator 4 also functions as a generator and generates power when the hybrid vehicle 1 travels. The motor generator 4 may be connected to any part of the power transmission path from the transmission 3 to the drive wheel 5 so as to be able to transmit power, and is not necessarily connected to the differential mechanism 27.

  The hybrid vehicle 1 includes a first power storage device 30, a low voltage power pack 32 including a second power storage device 31, a high voltage power pack 34 including a third power storage device 33, a high voltage cable 35, and a low voltage cable 36. And.

  The 1st electrical storage apparatus 30, the 2nd electrical storage apparatus 31, and the 3rd electrical storage apparatus 33 are comprised from the rechargeable secondary battery. First power storage device 30 is formed of a lead battery. The second power storage device 31 is a power storage device with higher output and higher energy density than the first power storage device 30.

  The second power storage device 31 can be charged in a shorter time than the first power storage device 30. In this embodiment, the 2nd electrical storage apparatus 31 consists of a lithium ion battery. The second power storage device 31 may be a nickel hydride storage battery.

  The first power storage device 30 and the second power storage device 31 are low-voltage batteries in which the number of cells is set so as to generate an output voltage of about 12V. The 3rd electrical storage apparatus 33 consists of a nickel hydride storage battery or a lithium ion battery, for example.

  The third power storage device 33 is a high voltage battery in which the number of cells is set so as to generate a higher voltage than the first power storage device 30 and the second power storage device 31, and generates an output voltage of 100V, for example. The state such as the remaining capacity of the third power storage device 33 is managed by the high voltage BMS 16.

  The hybrid vehicle 1 is provided with a general load 37 and a protected load 38 as electric loads. The general load 37 and the protected load 38 are electric loads other than the starter 21 and the ISG 20.

  The protected load 38 is an electric load that always requires a stable power supply. The protected load 38 includes a stability control device 38A that prevents a side slip of the vehicle, an electric power steering control device 38B that electrically assists the operating force of the steering wheel, and a headlight 38C. The protected load 38 also includes instrument panel lamps and meters (not shown) and a car navigation system.

  The general load 37 is an electric load that is temporarily used without requiring stable power supply as compared with the protected load 38. The general load 37 includes, for example, a wiper (not shown) and an electric cooling fan that blows cooling air to the engine 2.

  The low voltage power pack 32 includes switches 40 and 41 and a low voltage BMS 15 in addition to the second power storage device 31. The first power storage device 30 and the second power storage device 31 are connected to the starter 21, the ISG 20, the general load 37 as an electrical load, and the protected load 38 via a low voltage cable 36 so as to be able to supply power. Yes. The first power storage device 30 and the second power storage device 31 are electrically connected in parallel to the protected load 38.

  The switch 40 is provided in the low voltage cable 36 between the second power storage device 31 and the protected load 38. The switch 41 is provided in the low voltage cable 36 between the first power storage device 30 and the protected load 38.

  The low voltage BMS 15 controls charging / discharging of the second power storage device 31 and power supply to the protected load 38 by controlling opening and closing of the switches 40 and 41. When the engine 2 is stopped due to idling stop, the low voltage BMS 15 closes the switch 40 and opens the switch 41, thereby supplying power from the second power storage device 31 having high output and high energy density to the protected load 38. It comes to supply.

  When the engine 2 is started by the starter 21 and when the engine 2 stopped by the idling stop control is restarted by the ISG 20, the low voltage BMS 15 opens the switch 41 and opens the switch 41. Electric power is supplied from the power storage device 30 to the starter 21 or the ISG 20. When the switch 40 is closed and the switch 41 is opened, power is also supplied from the first power storage device 30 to the general load 37.

  As described above, the first power storage device 30 supplies at least electric power to the starter 21 and the ISG 20 as starters for starting the engine 2. The second power storage device 31 supplies at least power to the general load 37 and the protected load 38.

  The second power storage device 31 is connected so as to be able to supply power to both the general load 37 and the protected load 38. However, the second power storage device 31 preferentially supplies power to the protected load 38 that always requires stable power supply. Thus, the switches 40 and 41 are controlled by the low voltage BMS 15.

  The low voltage BMS 15 is charged to the first power storage device 30 and the second power storage device 31 (also referred to as SOC: State Of Charge, power storage state, remaining charge amount, charge capacity), and to the general load 37 and the protected load 38. The switches 40 and 41 may be controlled differently from the above-mentioned example in consideration of the operation requirements of the above, giving priority to stable operation of the protected load 38.

  The high voltage power pack 34 includes an inverter 45, INVCM 14, and high voltage BMS 16 in addition to the third power storage device 33. The high voltage power pack 34 is connected to the motor generator 4 via a high voltage cable 35 so that electric power can be supplied.

  The inverter 45 is configured to mutually convert AC power applied to the high voltage cable 35 and DC power applied to the third power storage device 33 under the control of the INVCM 14. For example, when powering the motor generator 4, the INVCM 14 converts the DC power discharged by the third power storage device 33 into AC power by the inverter 45 and supplies the AC power to the motor generator 4.

  When the motor generator 4 is regenerated, the INVCM 14 converts the AC power generated by the motor generator 4 into DC power by the inverter 45 and charges the third power storage device 33.

  HCU10, ECM11, TCM12, ISGCM13, INVCM14, low voltage BMS15 and high voltage BMS16 are respectively CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), backup data, etc. Is constituted by a computer unit having a flash memory for storing, an input port, and an output port.

  The ROMs of these computer units store various constants and maps, and programs for causing the computer units to function as the HCU 10, ECM 11, TCM 12, ISGCM 13, INVCM 14, low voltage BMS 15 and high voltage BMS 16, respectively. Yes.

  That is, when the CPU executes a program stored in the ROM using the RAM as a work area, these computer units are referred to as the HCU 10, ECM 11, TCM 12, ISGCM 13, INVCM 14, low voltage BMS 15, and high voltage BMS 16 in this embodiment. Each functions.

  In the present embodiment, the ECM 11 performs idling stop control. In this idling stop control, the ECM 11 stops the engine 2 when a predetermined stop condition is satisfied, and restarts the engine 2 by driving the ISG 20 via the ISGCM 13 when the predetermined restart condition is satisfied. . For this reason, unnecessary idling of the engine 2 is not performed, and the fuel efficiency of the hybrid vehicle 1 can be improved.

  In the present embodiment, the ECM 11 stops the engine 2 with a predetermined stop condition that the vehicle is in a stopped state (the vehicle speed is zero). Thus, the hybrid vehicle 1 is provided with a stop IS (Idling Stop) function that performs idling stop when the vehicle stops.

  The hybrid vehicle 1 is provided with CAN communication lines 48 and 49 for forming an in-vehicle LAN (Local Area Network) conforming to a standard such as CAN (Controller Area Network).

  The HCU 10 is connected to the INVCM 14 and the high voltage BMS 16 by a CAN communication line 48. The HCU 10, INVCM 14 and high voltage BMS 16 mutually transmit and receive signals such as control signals via the CAN communication line 48.

  The HCU 10 is connected to the ECM 11, the TCM 12, the ISGCM 13 and the low voltage BMS 15 by a CAN communication line 49. The HCU 10, ECM 11, TCM 12, ISGCM 13, and low voltage BMS 15 mutually transmit and receive signals such as control signals via the CAN communication line 49.

  Further, the hybrid vehicle 1 of the present embodiment has a gap filling function. The gap filling function is a function of driving the motor generator 4 during the shift of the transmission 3 and applying the torque of the motor generator 4 to the drive wheels 5.

  The HCU 10 implements the gap filling function by executing the gap filling control operation when the operation is permitted. While the transmission 3 is shifting, the clutch 26 is disengaged and engine torque cannot be transmitted from the engine 2 to the drive wheels 5. For this reason, the HCU 10 applies the motor torque (assist torque) generated by the power running operation of the motor generator 4 to the drive wheels 5 in the gap filling control operation. By this gap filling function, the feeling of deceleration due to the disengagement of the clutch 26 during the shift is suppressed, and the running performance of the vehicle can be improved.

  In FIG. 2, the hybrid vehicle 1 includes the engine 2 and the motor generator 4 as drive sources, as described above, and applies the motor torque of the motor generator 4 to the drive wheels 5 when the vehicle accelerates. Assist driving. The assist running by the motor generator 4 is performed using the electric power of the third power storage device 33 on the condition that the accelerator opening is 100% (fully open).

  The hybrid vehicle 1 also includes a vehicle speed detection unit 63 that detects the vehicle speed, a charge state detection unit 61 that detects the charge state of the third power storage device 33, and a battery temperature detection unit that detects the battery temperature of the third power storage device 33. 62.

  The charging state detection unit 61 detects the charging state of the third power storage device 33 based on the inter-terminal voltage and the input / output current of the third power storage device 33 detected by the high voltage BMS 16. The battery temperature detection unit 62 detects the cell temperature of the third power storage device 33 as the battery temperature. The battery temperature detection unit 62 may detect the surface temperature of the exterior of the third power storage device 33 as the battery temperature.

  The hybrid vehicle 1 also includes an accelerator opening detector 64 that detects the accelerator opening. The accelerator opening detector 64 detects the amount of depression of an accelerator pedal (not shown) as the accelerator opening. The accelerator opening takes a value of 0% when the accelerator pedal is not depressed, and takes a value of 100% when the accelerator pedal is fully depressed.

  The HCU 10 includes a discharge power calculation unit 71 and an assist determination unit 72. Based on the state of charge detected by the state of charge detection unit 61 and the battery temperature detected by the battery temperature detection unit 62, the discharge power calculation unit 71 determines whether the third power storage device 33 is A dischargeable power (hereinafter referred to as discharge power) is calculated.

  The assist determination unit 72 determines permission or prohibition of assist by the motor generator 4 based on the discharge power calculated by the discharge power calculation unit 71 and the vehicle speed detected by the vehicle speed detection unit 63.

  When the discharge power is equal to or higher than the predetermined second power, the assist determination unit 72 permits the motor generator 4 to assist in the entire vehicle speed range.

  Further, when the discharge power is less than the predetermined first power, the assist determination unit 72 permits the assist by the motor generator 4 only in a predetermined low vehicle speed region. The first power is smaller than the second power.

  In addition, when the discharge power is equal to or higher than the first power and lower than the second power, the assist determination unit 72 permits the assist by the motor generator 4 only in a predetermined medium and low vehicle speed region. The medium / low vehicle speed region includes a low vehicle speed region and a medium vehicle speed region.

  As an example, the low vehicle speed region is 0 km / h or more and less than 50 km / h, the medium vehicle speed region is 50 km / h or more and less than 80 km / h, and the high vehicle speed region is 80 km / h or more. In this example, the middle / low vehicle speed region is 0 km / h or more and less than 80 km / h. The boundary point between the low vehicle speed region and the medium vehicle speed region is 50 km / h, and the boundary point between the medium vehicle speed region and the high vehicle speed region is 80 km / h.

  The assist determination unit 72 permits the assist by the motor generator 4 for a predetermined time limit. This time limit is, for example, 10 seconds. The assist determination unit 72 prohibits the assist by the motor generator 4 when the gear position of the transmission 3 is set to a gear position (reverse gear) when the vehicle is moving backward.

  The transmission 3 is configured to be able to switch the gear position according to the traveling state of the vehicle. The transmission 3 is configured to be able to select one of a manual mode for switching the gear position according to the driver's operation and an automatic gear shift mode for automatically switching the gear position according to the traveling state of the vehicle.

  The assist determination unit 72 prohibits assist by the motor generator 4 when the manual mode is selected.

  The boundary point between the vehicle speed region in which assist by the motor generator 4 is permitted by the assist determination unit 72 and the vehicle speed region in which assistance by the motor generator 4 is prohibited is coincident with the shift stage switching timing in the transmission 3. . For example, when the boundary points at which the assist by the motor generator 4 is permitted or prohibited are 50 km / h and 80 km / h, the shift stage switching timing in the transmission 3 is also set to 50 km / h and 80 km / h.

  The assist determination operation executed in the motor assist control device for a hybrid vehicle configured as described above will be described with reference to the flowchart shown in FIG.

  In the assist determination operation of FIG. 3, first, the HCU 10 determines whether or not the accelerator opening is 100% (fully open) (step S1).

  If the accelerator opening is not 100% in step S1, the HCU 10 prohibits the assist by the motor generator 4 (step S6) and ends this flowchart.

  When the accelerator opening is 100% in step S1, the HCU 10 discharges power (dischargeable power) of the third power storage device 33 at the time of assisting based on the charge state of the third power storage device 33 and the battery temperature. Is calculated (step S2). In FIG. 3, the third power storage device 33 is referred to as a battery.

  Following step S2, the HCU 10 determines whether or not the discharge power is equal to or greater than a predetermined second power (step S3).

  If the discharge power is greater than or equal to the second power in step S3, the HCU 10 proceeds to step S4 and permits assist by the motor generator 4. When the assist is permitted, the HCU 10 powers the motor generator 4 to generate motor torque, and assists the running of the vehicle with this motor torque.

  If the discharge power is not equal to or greater than the second power in step S3, the HCU 10 determines whether or not the discharge power is equal to or greater than the predetermined first power (step S7).

  If the discharge power is greater than or equal to the first power in step S7, the HCU 10 determines whether or not the current vehicle speed is in a predetermined medium / low speed vehicle speed region (step S8). Here, HCU10 discriminate | determines that it is a medium-low vehicle speed area | region, when a vehicle speed is 0 km / h or more and less than 80 km / h, for example.

  When the vehicle speed is in the medium / low speed vehicle speed region in step S8, the HCU 10 proceeds to step S4 and permits the assist by the motor generator 4.

  If the discharge power is not equal to or greater than the first power in step S8, that is, if the discharge power is less than the first power, the HCU 10 determines whether or not the current vehicle speed is in the low vehicle speed region (step S9). . Here, the HCU 10 determines that the vehicle is in the middle / low vehicle speed region when the vehicle speed is, for example, less than 50 km / h.

  When the vehicle speed is in the low vehicle speed region in step S9, the HCU 10 proceeds to step S4 and permits the assist by the motor generator 4.

  If the vehicle speed is not in the low vehicle speed region in step S9, the HCU 10 prohibits the assist by the motor generator 4 (step S6) and ends this flowchart. Note that the case where the vehicle speed is not in the low vehicle speed region in step S9 is the case where the vehicle is stopped or the vehicle is moving backward. When the vehicle is stopped and moving backward, the assist by the motor generator 4 is prohibited and the assist is not performed.

  After step S4, the HCU 10 determines whether or not a predetermined time limit (for example, 10 seconds) has been exceeded after the assist is started (step S5). If the time limit is exceeded, the assist by the motor generator 4 is prohibited (step S5). S6) This flowchart is terminated.

  According to the assist determination operation in FIG. 3, when the driver seeks the maximum acceleration and depresses the accelerator pedal to 100% (fully open), the HCU 10 has the discharge power (dischargeable power) of the third power storage device 33 as the first. In the case of two or more electric powers, the assist by the motor generator 4 is permitted in the entire vehicle speed region, that is, in the low vehicle speed region, the medium vehicle speed region, and the high vehicle speed region.

  When the discharge power is greater than or equal to the first power and less than the second power, the assist by the motor generator 4 is permitted in the middle and low vehicle speed regions, that is, in the low vehicle speed region and the medium vehicle speed region. Further, when the discharge power is less than the first power, the assist by the motor generator 4 is permitted in the low vehicle speed region.

  The operational effects of the motor assist control device for a hybrid vehicle according to the present embodiment described above will be described.

  The motor assist control device for a hybrid vehicle according to this embodiment includes a vehicle speed detection unit 63 that detects a vehicle speed, a charge state detection unit 61 that detects a charge state of the third power storage device 33, and a battery temperature of the third power storage device 33. And a battery temperature detection unit 62 for detection.

  In addition, the motor assist control device for the hybrid vehicle performs the third operation when the assist by the motor generator 4 is performed based on the charge state detected by the charge state detection unit 61 and the battery temperature detected by the battery temperature detection unit 62. A discharge power calculation unit 71 that calculates the discharge power that can be discharged by the power storage device 33 is provided.

  Further, the motor assist control device for the hybrid vehicle assists determining permission or prohibition of assist by the motor generator 4 based on the discharge power calculated by the discharge power calculation unit 71 and the vehicle speed detected by the vehicle speed detection unit 63. A determination unit 72 is provided.

  Then, the assist determination unit 72 permits the assist by the motor generator 4 in the entire vehicle speed region when the discharge power is equal to or greater than the predetermined second power, and when the discharge power is less than the predetermined first power, When the assist by the generator 4 is permitted only in a predetermined low vehicle speed range and the discharge power is equal to or higher than the first power and lower than the second power, the assist by the motor generator 4 is permitted only in the predetermined medium and low vehicle speed range.

  With this configuration, as the discharge power calculated from the state of charge of the third power storage device 33 and the battery temperature decreases, the vehicle speed regions to be assisted by the motor generator 4 are the full vehicle speed region, the medium low vehicle speed region, the low vehicle speed region. It is limited to sequentially.

  As described above, since the vehicle speed region where the assist is performed is limited based on the state of charge of the third power storage device 33, the vehicle speed region where the assist is performed decreases as the charge state of the third power storage device 33 decreases. Can be limited to.

  For this reason, in the low-speed side vehicle speed range, the motor torque for the same discharge power is larger than in the high-speed side vehicle speed range, so the assist should be performed in a state where both the power efficiency and the efficiency of the assist effect are good. Can do.

  On the other hand, by not performing the assist in the vehicle speed range on the high vehicle speed side, the charging state of the third power storage device 33 can be suppressed from being significantly lowered, and the assist is performed with a stable motor torque in the vehicle speed region on the low vehicle speed side. it can.

  In addition, since the vehicle speed region where the assist is performed is limited in consideration of the battery temperature, the vehicle speed region where the assist is performed can be limited to the low speed side when the battery temperature is high and the discharge power is not stable. Thereby, the further raise of battery temperature can be prevented and assistance can be implemented with the stable motor torque.

  As a result, the assist can be performed in the efficient vehicle speed region by the stable motor torque.

  Here, with reference to FIG. 4, FIG. 5, the relationship between discharge electric power and motor torque is demonstrated. 4 and 5, the vertical axis represents axle torque [N · m], and the horizontal axis represents vehicle speed [km / h]. FIG. 4 shows the axle torque as a solid line when the vehicle accelerates while the gear position of the transmission 3 is sequentially switched from the first gear to the fifth gear. FIG. 4 shows the maximum motor torque (constant power curve) that can be generated by the motor generator 4 when the discharge power is constant by a broken line. FIG. 5 represents the maximum motor torque (constant power curve) that can be generated by the motor generator 4 when the discharge power is at normal output, at the time of reduction, and at the time of extreme reduction, by broken lines. 4 and 5, the vertical axis represents the value obtained by converting the motor torque into the axle torque.

  In FIG. 4, the maximum motor torque that can be generated by the motor generator 4 decreases as the vehicle speed increases even if the discharge power is the same. For example, the motor torque Tb at the vehicle speed Vb is smaller than the motor torque Ta at the vehicle speed Va (value smaller than Vb).

  Since the motor generator 4 has such characteristics, when the vehicle speed is low, the assist can be performed with a larger motor torque than when the vehicle speed is high, and the acceleration feeling felt by the driver is also increased. In other words, the assist effect (motor torque) felt by the driver can be increased when the vehicle speed is low.

  In the present embodiment, as the discharge power that can be discharged by the third power storage device 33 becomes smaller, the vehicle speed region in which the assist is performed is sequentially prohibited from the high vehicle speed region. Further, the assist by the motor generator 4 is performed even when the discharge power is less than the first power.

  In FIG. 5, the maximum motor torque that can be generated by the motor generator 4 (also referred to as a fully open performance up torque in the figure) decreases as the discharge power decreases from the normal output to the extremely low level after the discharge power decreases. ing. Further, in order for the driver to realize the assist effect by the assist of the motor generator 4, the motor torque needs to satisfy a certain necessary minimum torque.

  In FIG. 5, the motor torque when the discharge power is reduced can satisfy the required minimum torque (required minimum value) up to the vehicle speed B, but the motor torque when the discharge power is extremely reduced is the vehicle speed A (a value smaller than the vehicle speed B). Only the required minimum torque (minimum required value) can be satisfied. This necessary minimum torque is set in the HCU 10 as a conforming value.

  In addition, the motor assist control device for a hybrid vehicle according to the present embodiment includes the transmission 3 that can switch the gear position according to the traveling state of the vehicle, and the vehicle speed at which the assist determination by the motor generator 4 is permitted by the assist determination unit 72. The boundary point between the region and the vehicle speed region in which the assist by the motor generator 4 is prohibited is made coincident with the shift speed change execution timing in the transmission 3.

  With this configuration, the presence / absence of assist by the motor generator 4 is switched at the shift execution timing of the transmission 3 to change the acceleration of the vehicle when the assist is switched. It can be absorbed by changes in acceleration. For this reason, it is possible to prevent the driver from feeling uncomfortable by recognizing the change of assist.

  Specifically, as shown in FIG. 4, the boundary point (for example, 50 km / h) between the low vehicle speed region and the medium vehicle speed region is made to coincide with the switching execution timing of the transmission 3 from the second gear to the third gear. Yes. Further, the boundary point (for example, 80 km / h) between the medium vehicle speed region and the high vehicle speed region is made coincident with the switching execution timing of the transmission 3 from the 4th gear to the 5th gear.

  Note that the gear shift switching timing in the transmission 3 is changed by an acceleration request from the driver (accelerator pedal depression amount) or the like. May be changed.

  Further, in the motor assist control device for a hybrid vehicle of the present embodiment, the assist determination unit 72 permits the assist by the motor generator 4 for a predetermined time limit (for example, 10 seconds).

  With this configuration, since the assist by the motor generator 4 is limited to a predetermined time limit, it is possible to prevent the cell temperature of the third power storage device 33 from rising due to the execution of the assist, and to stabilize the motor torque. Can do. Moreover, it can suppress that the charge condition of the 3rd electrical storage apparatus 33 falls extremely by implementation of assist.

  Further, the motor assist control device for a hybrid vehicle of the present embodiment includes a transmission 3 that can switch the gear position according to the running state of the vehicle, and the assist determination unit 72 determines that the gear position of the transmission 3 is reverse to the vehicle. If the current gear position is set, assist by the motor generator 4 is prohibited.

  With this configuration, since the assist by the motor generator 4 is unnecessary when the vehicle is moving backward, it is possible to suppress unnecessary charging and reducing the charge state of the third power storage device 33.

  In addition, the hybrid vehicle motor assist control device according to the present embodiment can select one of a manual mode for switching the shift stage according to the driver's operation and an automatic shift mode for automatically switching the shift stage according to the running state of the vehicle. And an assist determination unit 72 that prohibits assist by the motor generator 4 when the manual mode is selected.

  Here, in the manual mode, the driver requires various operations to be directly reflected in the traveling state, and desires a direct operational feeling as the driver intends. For this reason, when the manual mode is selected, the assist by the motor generator 4 is prohibited, so that the driver can drive as intended, and the charge state of the third power storage device 33 can be prevented from being lowered. .

  In the manual mode, the above-described gap filling control operation is also not performed, so that a direct operational feeling as intended by the driver can be realized.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

DESCRIPTION OF SYMBOLS 1 Hybrid vehicle 2 Engine 3 Transmission 4 Motor generator (motor)
5 Drive Wheel 61 Charging State Detection Unit 62 Battery Temperature Detection Unit 63 Vehicle Speed Detection Unit 71 Discharge Power Calculation Unit 72 Assist Determination Unit

Claims (5)

A motor assist control device for a hybrid vehicle that includes an engine and a motor as a drive source, and assists driving of the vehicle by applying motor torque of the motor to drive wheels when the vehicle accelerates,
A vehicle speed detector for detecting the vehicle speed;
A charge state detection unit for detecting a charge state of the battery;
A battery temperature detector for detecting a battery temperature of the battery;
Discharge power calculation that calculates discharge power that can be discharged by the battery when the assist is performed by the motor, based on the charge state detected by the charge state detection unit and the battery temperature detected by the battery temperature detection unit And
An assist determination unit that determines permission or prohibition of assist by the motor based on the discharge power calculated by the discharge power calculation unit and the vehicle speed detected by the vehicle speed detection unit;
The assist determination unit
When the discharge power is greater than or equal to a predetermined second power, the assist by the motor is permitted in the entire vehicle speed range,
When the discharge power is less than a predetermined first power, the assist by the motor is permitted only in a predetermined low vehicle speed region,
When the discharge power is equal to or higher than the first power and lower than the second power, the assist by the motor is permitted only in a predetermined medium and low vehicle speed region, and the motor assist control device for a hybrid vehicle is characterized in that: It has a transmission that can switch gears according to the running state of the vehicle,
A boundary point between a vehicle speed region in which assistance by the motor is permitted by the assist determination unit and a vehicle speed region in which assistance by the motor is prohibited is made coincident with the timing for performing the shift stage switching in the transmission. The motor assist control device for a hybrid vehicle according to claim 1.   3. The motor assist control device for a hybrid vehicle according to claim 1, wherein the assist determination unit permits the assist by the motor to be limited to a predetermined time limit. 4. Provided with a transmission capable of changing gears according to the running state of the vehicle,
The assist determination unit prohibits assist by the motor when the shift stage of the transmission is set to a shift stage when the vehicle is moving backward. The motor assist control device for a hybrid vehicle according to the item. A motor assist control device for a hybrid vehicle that includes an engine and a motor as drive sources, and assists driving of the vehicle by applying motor torque of the motor to drive wheels when the vehicle accelerates,
A transmission capable of selecting one of a manual mode for switching a shift stage according to a driver's operation and an automatic shift mode for automatically switching the shift stage according to a driving state of the vehicle;
A motor assist control device for a hybrid vehicle, comprising: an assist determination unit that prohibits assist by the motor when the manual mode is selected.