JP2010179806A - Hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid vehicle capable of improving energy efficiency of a vehicle. <P>SOLUTION: Power for travel when the energy efficiency of the vehicle that reduces because the efficiency of the engine becomes lower than the best efficiency as the power for travel becomes smaller when engine drive travel is performed and the energy efficiency of the vehicle that increases because loss of an electrical driving system becomes smaller as the power for travel becomes smaller when motor travel is performed are equal is set as a start/stop threshold value for starting and stopping an engine. Drive control is performed using power that becomes smaller as the voltage of the high voltage system becomes higher as a start/stop threshold value based on the characteristics of a hybrid vehicle in which the energy efficiency of the vehicle is reduced because the loss of the electrical driving system becomes larger as voltage of a high voltage system becomes higher when the engine is intermittently operated. Thereby, the energy efficiency of the vehicle can be improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hybrid vehicle.

  Conventionally, this type of hybrid vehicle includes an engine, a first motor generator, a planetary gear connected to the front wheel side to which the engine and the first motor generator are connected, and a second motor generator connected to the front wheel side. A battery and a booster circuit that boosts DC power from the battery and supplies the booster to an inverter that drives the first and second motor generators, and the travel power required for the vehicle to travel is below the stop power threshold Sometimes, the engine is stopped and the engine is started when the running power exceeds the starting power threshold (see, for example, Patent Document 1). In this vehicle, engine stop is prohibited when the vehicle speed is equal to or higher than the vehicle speed threshold, and the battery is protected by changing the vehicle speed threshold according to the state of the battery.

JP 2006-170128 A

  In general, in a hybrid vehicle, one of the problems is to improve the energy efficiency of the vehicle. Therefore, in the above-described hybrid vehicle, it is conceivable that the threshold value to be compared with the power required for traveling is determined in consideration of engine efficiency and electrical loss. In other words, when the power required for driving is reduced, if the engine continues to run and the output power is low, the engine cannot be operated efficiently and the power required for driving increases. If the engine is stopped and the vehicle continues to run using only the power from the second motor generator, the loss of the battery and the two motor generators will increase. Although it is conceivable to set a threshold value for starting and stopping the engine so as to improve efficiency, it is desired to further improve the energy efficiency of the vehicle.

  The main purpose of the hybrid vehicle of the present invention is to improve the energy efficiency of the hybrid vehicle.

  The hybrid vehicle of the present invention employs the following means in order to achieve the main object described above.

The hybrid vehicle of the present invention
A planetary gear mechanism in which three rotating elements are connected to three axes of an engine, a generator capable of inputting / outputting power, an output shaft of the engine, a rotating shaft of the generator, and a driving shaft connected to a driving wheel. And an electric motor capable of inputting / outputting power to / from the drive shaft, a chargeable / dischargeable battery, a low voltage system to which the battery is connected, and a high voltage system to which the generator and the electric motor are connected A voltage adjusting circuit for adjusting the voltage of the high voltage system with respect to the voltage of the low voltage system, and a driving power corresponding to the required driving force required for traveling from the engine to output the required driving force When the engine is running, the energy efficiency of the vehicle, which decreases as the power for traveling decreases, becomes lower than the maximum efficiency of the engine, and the engine is stopped. The electric motor drive system includes the generator, the electric motor, the battery, and the voltage adjustment circuit as the traveling power decreases when the electric motor travels using only the power from the electric motor and travels with the required driving force. When the engine is intermittently operated as the start / stop threshold for starting or stopping the engine when the energy efficiency of the vehicle that rises due to the loss of the vehicle becomes equal, the engine operation is performed. The voltage adjustment circuit so that the voltage of the high voltage system becomes a target voltage set based on the driving state of the generator and the motor when the power for traveling becomes less than the start / stop threshold during traveling. The engine, the generator, and the motor are controlled so that the motor travel is performed with voltage adjustment control for controlling the motor. Control that controls the engine, the generator, and the motor so that the engine operation traveling is performed with the voltage adjustment control when the traveling power becomes equal to or greater than the start / stop threshold during the electric motor traveling. A hybrid vehicle comprising:
The control means is configured to control the high voltage system based on a characteristic of the vehicle in which the energy efficiency of the vehicle decreases due to the loss of the electric drive system increasing as the voltage of the high voltage system increases when the motor travels. Is a means for controlling by using a power that decreases as the voltage increases as the start / stop threshold,
It is characterized by that.

  In the hybrid vehicle of the present invention, when the driving power corresponding to the required driving force required for driving is output from the engine and the engine driving driving is performed using the required driving force, the smaller the driving power, The vehicle energy efficiency decreases when the efficiency is lower than the maximum efficiency of the engine, and when the motor is driven with the required driving force using only the power from the motor while the operation of the engine is stopped, The smaller the power is, the smaller the loss of the electric drive system including the generator, motor, battery, and voltage regulator circuit becomes, so that the power for traveling when the energy efficiency of the rising vehicle becomes equal is started and stopped. When the engine is intermittently operated as a starting / stopping threshold value, the running power starts and stops during engine driving When the engine voltage is less than the value, the engine is operated so that the motor travels with voltage adjustment control for controlling the voltage adjustment circuit so that the voltage of the high voltage system becomes a target voltage set based on the driving state of the generator and the motor. Controls the generator and motor, and controls the engine, generator, and motor so that the engine operation traveling is performed with voltage adjustment control when the traveling power exceeds the start / stop threshold during motor traveling. . Furthermore, the higher the voltage of the high voltage system is, the higher the voltage of the high voltage system is, the higher the voltage of the high voltage system is. Control using power as a start / stop threshold. As a result, the higher the voltage of the high voltage system, the greater the loss of the electric drive system, and the lower the energy efficiency of the vehicle, the lower the energy efficiency of the vehicle. The energy efficiency can be improved.

1 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 20 as an embodiment of the present invention. A state in which the start / stop threshold value of the engine 32 is set based on the high-voltage system voltage, the driving power, the efficiency of the engine 32 when the engine is driven and the loss of the electric drive system when the motor is driven. It is explanatory drawing demonstrated. 4 is an explanatory diagram showing an example of a start / stop threshold of an engine 32. FIG.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of the configuration of a hybrid vehicle 20 as an embodiment of the present invention. In the hybrid vehicle 20 of the embodiment, as shown in the figure, a carrier is connected to an engine 32 that uses gasoline or light oil as fuel, an engine electronic control unit 36 that drives and controls the engine 32, and a crankshaft 34 of the engine 32. And a planetary gear 38 having a ring gear connected to a drive shaft 22 connected to the drive wheels 26a and 26b via a differential gear 24, and a motor having a rotor connected to the sun gear of the planetary gear 38, for example, as a synchronous generator motor. 41, for example, a motor 42 configured as a synchronous generator motor and having a rotor connected to the drive shaft 22, inverters 43 and 44 for driving the motors 41 and 42, and switching elements (not shown) of the inverters 43 and 44 By controlling the switching, the motor 41, 2 is electrically connected to a motor electronic control unit 46 that controls the driving of the motor 2, a battery 48 that is configured as a secondary battery and can be charged and discharged, a power line to which the inverters 43 and 44 are connected, and the battery 48. A booster circuit 49 that boosts the DC power of the battery 48 and supplies it to the inverters 43 and 44 side, or steps down the DC power of the inverters 43 and 44 and supplies it to the battery 48 side, and detects the position of the shift lever. From the shift position from the shift position sensor 52, the accelerator opening from the accelerator pedal position sensor 54 that detects the depression amount of the accelerator pedal, the brake position from the brake pedal position sensor 56 that detects the depression amount of the brake pedal, and the vehicle speed sensor 57 The figure of the booster circuit 49 while inputting the vehicle speed A switching element does not output a signal for switching control comprises the hybrid electronic control unit 50 for controlling the entire vehicle communicates with the engine electronic control unit 36 and a motor electronic control unit 46.

  The hybrid vehicle 20 of the embodiment basically travels by drive control described below that is executed by the hybrid electronic control unit 50. In the hybrid electronic control unit 50, first, a required torque required for the drive shaft 22 for traveling is set according to the accelerator opening from the accelerator pedal position sensor 54 and the vehicle speed from the vehicle speed sensor 57, and the required torque is set. Is multiplied by the number of revolutions of the drive shaft 22 (for example, the number of revolutions obtained by multiplying the number of revolutions of the motor 42 or the vehicle speed by a conversion factor) to calculate the traveling power required for traveling and the battery from the calculated traveling power The engine command as the power to be output from the engine 32 by subtracting the correction power (positive value when discharging from the battery 48) for charging / discharging the battery 48 obtained according to the ratio (SOC) of the charge capacity of 48 Set the power. Then, the engine command power is compared with a start / stop threshold value for starting and stopping the engine 32. When the engine command power becomes equal to or greater than the start / stop threshold value while the operation of the engine 32 is stopped, the engine 32 is stopped. When the engine command power becomes less than the start / stop threshold when the engine 32 is operating, the operation of the engine 32 is stopped. When the operation of the engine 32 is continued or after the engine 32 is started, an operation line (for example, fuel efficiency) that can output the engine command power efficiently from the engine 32 and the relationship between the rotational speed and torque of the engine 32. The target rotational speed and target torque of the engine 32 are set using the optimal operation line), and the rotational speed of the engine 32 is within the range of the input / output limit as the maximum power that can charge and discharge the battery 48. A torque command as a torque to be output from the motor 41 is set by the rotational speed feedback control so as to be a number, and when the motor 41 is driven by the torque command from the required torque, the drive shaft 22 is connected via the planetary gear 38. The torque obtained by subtracting the torque acting on is set as a torque command for the motor 42. The set target rotational speed and target torque of the engine 32 are transmitted to the engine electronic control unit 36, and torque commands for the motors 41 and 42 are transmitted to the motor electronic control unit 46. The engine electronic control unit 36 that has received the target rotational speed and the target torque executes intake air amount control, fuel injection control, ignition control, etc. of the engine 32 so that the engine 32 is operated by the target rotational speed and the target torque. The motor electronic control unit 46 that has received the torque commands of the motors 41 and 42 performs switching control of the switching elements of the inverters 43 and 44 so that the motors 41 and 42 are driven by the torque commands. Thus, basically, the traveling power corresponding to the required torque can be output from the engine 32 to travel with the required torque (hereinafter referred to as engine operation traveling). On the other hand, when the operation stop of the engine 32 is continued or after the operation of the engine 32 is stopped, a value 0 is set in the torque command of the motor 41 and the required torque is set within the range of the input / output limit of the battery 48. 42, and the set torque command for the motors 41 and 42 is transmitted to the motor electronic control unit 46. The motor electronic control unit 46 that has received the torque commands of the motors 41 and 42 performs switching control of the switching elements of the inverters 43 and 44 so that the motors 41 and 42 are driven by the torque commands. As a result, the operation of the engine 32 is stopped, and the vehicle can travel with the required torque using only the power from the motor 42 (hereinafter referred to as motor travel). With this control, the hybrid vehicle 20 according to the embodiment outputs a required torque corresponding to the accelerator opening to the drive shaft 22 while charging / discharging the battery within the input / output limit range of the battery 48 with intermittent operation of the engine 32. Then run.

  The start / stop threshold when the engine 32 is intermittently operated is such that the energy efficiency of the vehicle decreases because the efficiency of the engine 32 becomes lower than the maximum efficiency as the traveling power decreases when the engine is operated. The smaller the driving power when the vehicle is traveling, the loss of the electric drive system composed of the motors 41 and 42, the inverters 43 and 44, the battery 48, the booster circuit 49, etc. As a driving power when the energy efficiency of the vehicle that rises as the current becomes smaller is basically equal to a value determined in advance through experimentation or analysis.

  The booster circuit 49 is controlled by the boost control executed in parallel with the drive control described above by the hybrid electronic control unit 50. In the step-up control, the rotational speed and driving of each of the motors 41 and 42 calculated by the motor electronic control unit 46 based on a signal from a rotational position detection sensor (not shown) that detects the rotational positions of the rotors of the motors 41 and 42. The torque command of each of the motors 41 and 42 set by the control is input, and the booster circuit 49 is used using a map predetermined within the rated voltage range of the motor 41 based on the rotation speed of the motor 41 and the torque command. The voltage required for the inverters 41 and 42 and the motors 41 and 42 (hereinafter referred to as a high voltage system) is set, and the voltage required for the high voltage system is similarly set based on the rotational speed of the motor 42 and the torque command. The larger one of the set voltages is set as a high voltage target voltage (for example, 300V, 500V, 600V, etc.). Then, switching control of a switching element (not shown) of the booster circuit 49 is performed so that a high voltage system voltage becomes a target voltage with respect to a voltage (for example, 200 V) on the battery 48 side (hereinafter referred to as a low voltage system) from the booster circuit 49. .

  In the hybrid vehicle 20 of the embodiment, the voltage of the high voltage system varies depending on the driving state of the motors 41 and 42 by such boost control, and thus the loss of the electric drive system also varies. For this reason, as a start / stop threshold value when the engine 32 is intermittently operated, a uniform value determined in advance without considering fluctuations in the loss of the electric drive system (for example, power based on the average value of the voltage of the high voltage system). From the viewpoint of vehicle energy efficiency, the timing for starting or stopping the engine 32 may be too early or too late. FIG. 2 shows the start / stop threshold value of the engine 32 based on the voltage of the high voltage system, the power for running, the efficiency of the engine 32 when the engine is running, and the loss of the electric drive system when the motor is run. The state of setting is shown. In the figure, as shown on the upper side of the horizontal axis of the traveling power, when the engine is driven regardless of the traveling power, the lower the traveling power output from the engine 32, the higher the efficiency of the engine 32 and its maximum. As shown on the lower side of the horizontal axis of the driving power, the motor driving is performed regardless of the driving power, as shown in the lower side of the horizontal axis of the driving power, as shown in the lower side of the horizontal axis of the driving power. When this is done, the smaller the power for driving, the smaller the loss of the electric drive system (in the figure, HV loss), and the higher the energy efficiency of the vehicle, that is, the efficiency of the engine 32 and its maximum efficiency. There is a place where the difference between the two and the loss of the electric drive system are balanced. This balance point is based on the characteristics of the hybrid vehicle 20 that the loss of the electric drive system increases and the energy efficiency of the vehicle decreases as the voltage of the high voltage system (step-up 300V, step-up 500V in the figure) increases. The higher the voltage is, the lower the running power becomes the balance point, and the running power corresponding to this balancing point is used as the start / stop threshold.

  Specifically, the relationship between the voltage of the high voltage system and the start / stop threshold is determined in advance by experiment or analysis and stored in the ROM of the hybrid electronic control unit 50 as a start / stop threshold setting map, and the booster circuit 49 In addition, a high voltage system voltage is input from a voltage sensor (not shown) attached to the power lines on the inverters 43 and 44 side, and the input stop voltage is applied to this start / stop threshold setting map to use the start / stop threshold value derived. Thus, the above-described drive control is performed and the engine 32 can be intermittently operated. FIG. 3 shows an example of the start / stop threshold set by the start / stop threshold setting map. In this example, a slightly different start / stop threshold is used depending on the vehicle speed. As described above, in the hybrid vehicle 20 of the embodiment, the drive control is performed using the power that becomes smaller as the voltage of the high voltage system becomes higher as the start / stop threshold based on the characteristics of the vehicle. However, the energy efficiency of the vehicle can be improved as compared with the case where the drive control is performed using the determined start / stop threshold regardless of the above.

  According to the hybrid vehicle 20 of the embodiment described above, as the start / stop threshold for starting or stopping the engine 32 when the engine 32 is intermittently operated, the higher the voltage of the high voltage system, the more the electric drive system loss. Based on the characteristics of the hybrid vehicle 20 in which the energy efficiency of the vehicle decreases due to the increase, the drive control is performed using the power that decreases as the high voltage system increases, so that the energy efficiency of the vehicle can be improved.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the engine 32 corresponds to the “engine”, the motor 41 corresponds to the “generator”, the motor 42 corresponds to the “electric motor”, the planetary gear 38 corresponds to the “planetary gear mechanism”, and the battery 48 It corresponds to “battery”, the booster circuit 49 corresponds to “voltage adjustment circuit”, and the engine command power is output when the engine command power based on the travel power and the correction power corresponding to the required torque is equal to or greater than the start / stop threshold. The target rotational speed and the target torque are set, the torque command of the motor 41 is set so that the rotational speed of the engine 32 is the target rotational speed within the range of the input / output restriction of the battery 48, and the required torque and the torque command of the motor 41 are set. The torque command of the motor 42 is set based on the above, and the value 0 is set to the torque command of the motor 41 when the engine command power is less than the start / stop threshold. In both cases, the required torque is set to the torque command of the motor 42 within the range of the input / output limitation of the battery 48, and drive control is performed to transmit both torque commands to the motor electronic control unit 36. The lower the driving power when driving, the lower the efficiency of the engine 32 becomes lower than its maximum efficiency, and the lower the energy efficiency of the vehicle and the lower the driving power when running the motor, the electric drive system. This is the power for driving when the energy efficiency of the vehicle that rises as the loss of the vehicle becomes equal, and the higher the voltage of the high voltage system, the greater the loss of the electric drive system, so the energy efficiency of the vehicle decreases. Based on the characteristics of the hybrid vehicle 20, drive control is performed using power that decreases as the voltage of the high-voltage system increases. The hybrid electronic control unit 50 that performs step-up control for controlling the step-up circuit 49 so that the high-voltage system voltage becomes a target voltage set based on the driving state of the motors 41 and 42, and the target rotational speed and target torque. The engine electronic control unit 36 that controls the engine 32 and the motor electronic control unit 46 that controls the motors 41 and 42 by a torque command correspond to “control means”.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the manufacturing industry of hybrid vehicles.

  20 Hybrid Vehicle, 22 Drive Shaft, 24 Differential Gear, 26a, 26b Drive Wheel, 32 Engine, 34 Crankshaft, 36 Engine Electronic Control Unit, 38 Planetary Gear, 41, 42 Motor, 43, 44 Inverter, 46 Motor Electronic Control Unit, 48 battery, 49 booster circuit, 50 hybrid electronic control unit, 52 shift position sensor, 54 accelerator pedal position sensor, 56 brake pedal position sensor, 57 vehicle speed sensor.

Claims (1)

A planetary gear mechanism in which three rotating elements are connected to three axes of an engine, a generator capable of inputting / outputting power, an output shaft of the engine, a rotating shaft of the generator, and a driving shaft connected to a driving wheel. And an electric motor capable of inputting / outputting power to / from the drive shaft, a chargeable / dischargeable battery, a low voltage system to which the battery is connected, and a high voltage system to which the generator and the electric motor are connected A voltage adjusting circuit for adjusting the voltage of the high voltage system with respect to the voltage of the low voltage system, and a driving power corresponding to the required driving force required for traveling from the engine to output the required driving force When the engine is running, the energy efficiency of the vehicle, which decreases as the power for traveling decreases, becomes lower than the maximum efficiency of the engine, and the engine is stopped. The electric motor drive system includes the generator, the electric motor, the battery, and the voltage adjustment circuit as the traveling power decreases when the electric motor travels using only the power from the electric motor and travels with the required driving force. When the engine is intermittently operated as the start / stop threshold for starting or stopping the engine when the energy efficiency of the vehicle that rises due to the loss of the vehicle becomes equal, the engine operation is performed. The voltage adjustment circuit so that the voltage of the high voltage system becomes a target voltage set based on the driving state of the generator and the motor when the power for traveling becomes less than the start / stop threshold during traveling. The engine, the generator, and the motor are controlled so that the motor travel is performed with voltage adjustment control for controlling the motor. Control that controls the engine, the generator, and the motor so that the engine operation traveling is performed with the voltage adjustment control when the traveling power becomes equal to or greater than the start / stop threshold during the electric motor traveling. A hybrid vehicle comprising:
The control means is configured to control the high voltage system based on a characteristic of the vehicle in which the energy efficiency of the vehicle decreases due to the loss of the electric drive system increasing as the voltage of the high voltage system increases when the motor travels. Is a means for controlling by using a power that decreases as the voltage increases as the start / stop threshold,
A hybrid vehicle characterized by that.

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