JP2017114321A - Hybrid vehicle - Google Patents

Abstract

When a power source for creep travel is switched from a motor generator to an internal combustion engine, the power of a battery consumed by execution of creep travel by the motor generator can be recovered while performing creep travel by the internal combustion engine. To provide a hybrid vehicle. In the creep travel control state, the HCU transmits the power output from the motor generator to the drive wheels until the state of charge of the battery becomes equal to or less than a first specified amount TH1 (step S2). When the state of charge of the battery becomes equal to or less than the first specified amount TH1 (step S1), the drive of the motor generator is stopped and creep running is executed by the power of the internal combustion engine (step S3). [Selection] Figure 3

Description

  The present invention relates to a hybrid vehicle.

  The hybrid vehicle includes an internal combustion engine and a motor generator in order to drive the vehicle. The hybrid vehicle has an EV traveling mode in which the internal combustion engine is stopped for the purpose of reducing fuel consumption and environmental load, and the vehicle can be driven only by a motor generator.

  Further, in a hybrid vehicle, even when the accelerator petal is not operated, if the shift position is at a travelable position (a shift position where forward travel or reverse travel is possible), at least the internal combustion engine or the motor generator The vehicle has a travel mode (creep travel mode) in which either one of the powers can be used to move the vehicle at an ultra-low speed. This creep travel is used for travel during traffic jams. For example, Patent Document 1 discloses creep driving by an engine in a hybrid vehicle.

  In creep driving of a hybrid vehicle, even if the battery is initially charged well and creep driving is performed with the power of only the motor generator, the traffic jam situation continues for a long time, exceeding the limit of creep driving with the power of the motor generator alone It is known that it can be automatically switched to creep running by the power of the internal combustion engine.

Japanese Patent Laid-Open No. 11-141365

  However, Patent Document 1 does not disclose a switching technique, and the well-known switching control is such that the power source is switched from the motor generator to the internal combustion engine, and the battery consumed in the execution of creep running by the motor generator. Power recovery was not considered.

  The present invention has been made in order to solve the above-described problems. When the power source for creep travel is switched from the motor generator to the internal combustion engine, the motor generator performs creep travel by the internal combustion engine. An object of the present invention is to provide a hybrid vehicle capable of recovering the electric power of the battery consumed by the execution of creep running by the vehicle.

  One aspect of a hybrid vehicle according to the present invention that solves the above-described problems is equipped with a hybrid engine that includes an internal combustion engine and a motor generator, and drives the vehicle with power output from at least one of the internal combustion engine and the motor generator. Connecting means for connecting or disconnecting power between the internal combustion engine and driving wheels, a control unit for controlling the vehicle using the power, and a driver's request for the control unit A creep running control means for running the vehicle with at least one of the powers even when there is no driving force, and a battery for supplying electric power for running the vehicle with the power of the motor generator. In the case where the creeping means is implemented by the power of the internal combustion engine by connecting a contact means, Until conducting state exceeds a set value, running the power generation control by the motor-generator power is applied to the battery.

  In the present invention, when creep running by the power of the internal combustion engine is executed according to the state of charge of the battery, the power generation control by the motor generator is also executed in parallel, so that the power of the battery can be recovered. Accordingly, it is possible to prepare an environment in which the battery power stored at the same time can be used while creeping using the power of the internal combustion engine.

  Here, according to a second aspect, in the hybrid vehicle according to the first aspect, the electric power applied to the battery by the power generation control is caused by a change in road surface condition during creep running by the power of the internal combustion engine. Accordingly, the power of the motor generator is added to the power of the internal combustion engine. In this way, the added electric power can be used when it is difficult to continue creep travel only by the power of the internal combustion engine due to changes in road surface conditions (decrease in vehicle speed). There is no need to step on the accelerator petal. Thereby, since creep running can be maintained, it can contribute to reduction of fuel consumption. Furthermore, in order to maintain creep travel, problems such as clutch wear and heat generation that occur when the clutch is frequently used can be prevented.

  The third aspect of the present invention is that the road surface condition to which the power of the motor generator is applied is an uphill road. In this way, even if the road surface condition changes to an uphill road, the creep running is maintained without overworking the clutch such as a half-clutch or without activating the accelerator petal to increase the power of the internal combustion engine. It is possible.

FIG. 1 is a configuration diagram showing a main part of a hybrid vehicle according to an embodiment of the present invention. FIG. 2 is a functional block diagram of the hybrid vehicle according to the embodiment of the present invention. FIG. 3 is a flowchart showing creep travel processing of the hybrid vehicle according to the embodiment of the present invention. FIG. 4 is a timing chart for explaining the operation of the hybrid vehicle according to the embodiment of the present invention.

  Hereinafter, a hybrid vehicle according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a 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) 10 that comprehensively controls the hybrid vehicle 1. 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, an INVCM (Invertor Control Module) 14, A low voltage BMS (Battery Management System) 15 and a high voltage BMS 16 are included.

  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 the present embodiment, the ISG 20 functions as an electric motor under the control of the ISGCM 13, thereby restarting the engine 2 from a stopped state by the idling stop function. 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 a constantly meshing transmission mechanism 25 including a parallel shaft gear mechanism, a clutch 26 constituted by a normally closed type dry clutch, a differential mechanism 27, and an actuator (not shown).

  The transmission 3 is configured as a so-called AMT (Automated Manual Transmission). The actuator controlled by the TCM 12 switches the gear position in the transmission mechanism 25 and connects and disengages the clutch 26. 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.

  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, and at least one of the engine 2 and the motor generator 4 outputs. It is designed to run with power.

  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 engine 2 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 the present embodiment, second power storage device 31 is formed 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 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 the skidding of the hybrid vehicle 1, 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 stabilizes the protected load 38 while taking into account the charging state (remaining charge amount) of the first power storage device 30 and the second power storage device 31 and the operation requests to the general load 37 and the protected load 38. Therefore, the switches 40 and 41 may be controlled differently from the above-described example with priority given to operation.

  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. The computer unit includes a flash memory to be stored, an input port, and an output port.

  The ROMs of these computer units store various constants, various maps, etc., 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. .

  That is, when the CPU executes a program stored in the ROM using the RAM as a work area, these computer units are used 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.

  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.

  As shown in FIG. 2, the HCU in the present embodiment has a function as a control unit 50 that controls the power for driving the hybrid vehicle 1. The HCU 10 transmits driving force for creep traveling to the drive wheels 5.

  For example, the HCU 10 detects the value of the brake stroke sensor 52 that detects the amount of operation of the brake pedal 51 when the hybrid vehicle 1 is stopped and the shift speed indicated by the information obtained from the TCM 12 is the forward speed or the reverse speed. The creep running is executed on the condition that the value becomes equal to or less than the predetermined value M1. The predetermined value M1 is a threshold value set in advance to detect that the driver has released the braking of the hybrid vehicle 1.

  When the detected value of the accelerator opening sensor 54 that detects the operation amount of the accelerator pedal 53 becomes equal to or greater than the predetermined value M2, the HCU 10 ends the creep travel. The predetermined value M2 is a threshold value for detecting that the driver has requested the driving of the hybrid vehicle 1, and is an adaptive value determined experimentally in advance.

  The HCU 10 instructs the INVCM 14 to execute creep running with the power output from the motor generator 4 until the state of charge (SOC) of the third power storage device 33 becomes equal to or less than the first specified value TH1. The first specified value TH1 is a predetermined value.

  When the state of charge (SOC) of the third power storage device 33 becomes equal to or less than the first specified value TH1 during execution of creep travel, the HCU 10 changes the power source for executing creep travel from the motor generator 4 to the engine 2.

  Hereinafter, as a changing process, the INVCM 14 is instructed to stop driving the motor generator 4 first. Next, the power source is changed to the engine 2, and the ECM 11 is instructed so that the power for continuing the creep travel is output from the engine 2.

  The HCU 10 performs power generation using the power generation function of the motor generator 4 while continuing creep travel by the engine 2 until the state of charge (SOC) of the third power storage device 33 reaches the second specified value. 3 Instructs INVCM 14 to charge power storage device 33.

  The second specified value TH2 is larger than the first specified value TH1, and is set to a value that prevents the third power storage device 33 from being overcharged.

  The HCU 10 is set so that the amount of torque generated by the motor generator 4 does not exceed the amount of engine torque used for creep travel, and the hybrid vehicle 1 is prevented from running backward.

  In the present embodiment, a clutch 26 is provided on the transmission path for the power from the engine 2 to the drive wheels 5. For this reason, while the vehicle 1 is creeping with the power output from the engine 2, the vehicle 1 continues to maintain the creep driving only with the power of the engine 2 even though the road surface condition has changed to an uphill. The heavy use of the half-clutch may cause the clutch 26 to generate heat or wear.

  When the HCU 10 determines that the road surface condition has changed from a flat road to an uphill by known means obtained from a stability control device (not shown) mounted on the vehicle, the engine on the flat road During creep running with power 2, power is output from the motor generator 4 using the electric power stored in the third power storage device 33 by power generation of the motor generator 4, and added to creep running with the power of the engine 2.

  Next, the operation will be described using the flowchart of FIG. FIG. 3 is a flowchart of a creep travel control process executed based on a program stored in the HCU. This flowchart is repeatedly executed in a predetermined cycle during creep running.

  First, in step S1, the HCU 10 determines whether or not the state of charge (SOC) of the third power storage device 33 (hereinafter simply referred to as “battery”) is equal to or less than the first specified value TH1.

  If it is determined in step S1 that the state of charge of the battery is not less than or equal to the first specified value TH1, the HCU 10 advances the creep travel control process (hereinafter simply referred to as “process”) to step S3.

  In step S <b> 2, the HCU 10 transmits the power (hereinafter also referred to as “MG power”) output from the motor generator 4 (simply referred to as “MG” in the figure) to the drive wheels 5 to creep the hybrid vehicle 1. Let it run. After executing step S2, the HCU 10 ends the process.

  In step S <b> 3, the HCU 10 stops driving the motor generator 4 and starts the engine 2 at the same time. As a result, the power source of torque for driving the vehicle is changed from the motor generator 4 to the engine 2. At the time of this change, the drive stop timing of the motor generator 4 and the start timing of the engine 2 are finely adjusted so that the driver does not feel a change shock. The HCU changes the power source for creep running to the engine 2 and simultaneously starts regenerative power generation by the motor generator 4 using a part of the power of the engine 2. After executing Step S3, the HCU 10 advances the process to Step S4.

  In step S4, the HCU 10 determines whether or not the state of charge of the battery is greater than or equal to the second specified value TH2. If it is determined that the state of charge of the battery is not equal to or greater than the second specified value TH2, the HCU 10 advances the process to step S6. Conversely, if step S4 is positive, that is, if it is determined that the state of charge of the battery is equal to or greater than the second specified value TH2, the HCU 10 advances the process to step S5.

  In step S5, the HCU 10 stops the regenerative power generation by the MG 4. After executing Step S5, the HCU 10 advances the process to Step S6.

  In step S6, the HCU 10 determines whether or not the road surface condition is an uphill road (uphill). If it is determined that the road surface condition is an uphill road, the HCU 10 advances the process to step S7. When it is determined that the road surface condition is not an uphill road, the HCU 10 ends the process.

  In step S <b> 7, the HCU 10 transmits MG power to the drive wheels 5 in addition to the power output from the engine 2 to execute creep travel. After executing step S7, the HCU 10 ends the process.

  FIG. 4 is a time chart when the control process shown in the flowchart of FIG. 3 is executed, and is an example of creep running.

  In FIG. 4, the vertical axis represents the road surface condition (indicating the road surface inclination), the vehicle speed, the battery charge state (SOC), the output torque Tm of the motor generator 4, and the output torque Te of the engine 2 from above. ing.

  At time t0, since the state of charge of the battery is good, the engine 2 is stopped, and the start by creep running from the situation where the vehicle is stopped is started. In this case, since the road surface condition is a flat road (the inclination is zero) and the state of charge (SOC) of the battery is larger than the first specified value TH1, creep running is started by the power of the motor generator 4. Is shown.

  If the creep running is continued only with the power of the motor generator 4, the battery power is consumed. When the state of charge (SOC) of the battery eventually falls below the first specified value TH1, the motor generator 4 is stopped and the engine 2 is turned off. Start (time t1). At the same time as the start of the engine 2 is completed and power for creep running is output, the motor generator 4 starts regenerative power generation.

  When creep running by the power of the engine 2 and regenerative power generation by the motor generator 4 are continued, the state of charge (SOC) of the battery is recovered by regenerative power generation, and when the second specified value TH2 or more is reached, regenerative power generation by the motor generator 4 is performed. Stop. At the same time, the power for regenerative power generation becomes unnecessary, so the power of the engine 2 is also reduced (time t2).

  If the road surface condition changes from a flat road to an uphill road during creep running with only the engine 2 in a state where the battery charging state is equal to or greater than the second specified value, creep driving cannot be maintained with the power of the engine 2 alone. Then, the power of the motor generator 4 is added to the power of the engine 2 and the creep running is maintained by the two powers (time t3).

  As described above, according to the present embodiment, when the creep running by the power of the engine 2 is executed according to the state of charge (SOC) of the battery, the power generation control by the motor generator 4 is also executed in parallel. It is possible to restore the power. As a result, it is possible to prepare an environment where the battery power stored at the same time can be used while creeping using the power of the engine 2.

  In the present embodiment, the electric power applied to the battery by the power generation control by the motor generator 4 is the power of the engine 2 as the power of the motor generator 4 according to the change of the road surface condition during creep running by the power of the engine 2. It is possible to add to.

  In this way, the added electric power can be used when it is difficult to continue creep travel only by the power of the engine 2 due to a change in road surface conditions (decrease in vehicle speed). There is no need to step on the accelerator petal. Thereby, since creep running can be maintained, it can contribute to reduction of fuel consumption. Furthermore, in order to maintain creep travel, problems such as clutch wear and heat generation that occur when the clutch is frequently used can be prevented.

  Furthermore, the present embodiment is that the road surface condition to which the power of the motor generator is applied is an uphill road. In this way, even if the road surface condition changes to an uphill road, the creep running is maintained without overworking the clutch such as a half-clutch, or without operating the accelerator petal to increase the power of the engine 2. It is possible.

  Therefore, in the present embodiment, since the power transmitted from the engine 2 is transmitted to the drive wheels 5 and the motor generator 4 regenerates the power from the power transmitted from the engine 2, the speed of the hybrid vehicle 1 varies. This can be suppressed and the power transmitted from the engine 2 can be used effectively.

  As mentioned above, although embodiment of this invention was disclosed, it is clear that a change can be added to this embodiment, without deviating from the scope of the present invention. The embodiments of the present invention are disclosed on the assumption that equivalents to which such changes are made are included in the invention described in the claims.

1 Hybrid vehicle 2 Engine (internal combustion engine)
4 Motor generator 5 Drive wheel 10 HCU (control unit, creep travel control means)
26 Clutch (connection / disconnection means)
33 Third power storage device (battery)

Claims (3)

A vehicle equipped with a hybrid engine comprising an internal combustion engine and a motor generator, wherein the vehicle is driven by power output from at least one of the internal combustion engine and the motor generator,
Connecting / disconnecting means for connecting or disconnecting power between the internal combustion engine and the drive wheel;
A control unit for controlling the vehicle using the power;
Creep driving control means for driving the vehicle with at least one of the powers without the driver's required driving force with respect to the control unit;
A battery for supplying electric power for running the vehicle by the power of the motor generator,
In the case where the connecting / disconnecting means is connected and the creep running means is implemented by the power of the internal combustion engine,
Until the state of charge of the battery exceeds a set value, power generation control by the motor generator is executed to apply electric power to the battery.   The electric power applied to the battery by the power generation control is added to the power of the internal combustion engine as the power of the motor generator according to a change in road surface conditions during creep travel by the power of the internal combustion engine. 1. The hybrid vehicle according to 1.   The hybrid vehicle according to claim 2, wherein the road surface condition to which the power of the motor generator is applied is an uphill road.