JP5822453B2 - Engine start control device for hybrid vehicle - Google Patents

Description

  The present invention is a first clutch interposed between the engine and the motor generator and capable of continuously changing the torque capacity, and interposed between the motor generator and the transmission and continuously changing the torque capacity. The present invention relates to an engine start control device for a hybrid vehicle in which a hybrid drive system is configured with a possible second clutch or the like.

  2. Description of the Related Art Conventionally, an engine start control device for a hybrid vehicle provided with an engine start control means is known (see, for example, Patent Document 1).

  Such an engine start control device for a hybrid vehicle has engine start control means for controlling the first and second clutches, the motor generator, and the engine of the hybrid drive system.

  The hybrid drive system includes an engine, a motor generator, a first clutch that is interposed between the engine and the motor generator and capable of continuously changing torque capacity, and is interposed between the motor generator and drive wheels. And a transmission that changes the gear ratio stepwise or steplessly, and a second clutch that is interposed between the motor generator and the transmission and that can continuously change the torque capacity.

  The engine start control means engages the first clutch and starts the engine in a state where the motor rotation speed is increased to an idling value when the engine is started.

JP 2007-69789 A

  However, in the conventional engine start control device for a hybrid vehicle, when the engine water temperature or the battery temperature is low, the battery output or the engine output is reduced, but the engine and the motor generator are rotating at an idle equivalent. From the number of revolutions, it was not known whether the engine had sufficient torque against the friction when the engine was started. For this reason, it is necessary to consider a safety margin that compensates for sufficient engine torque when the power generation torque and the driving force are applied after the start is completed.

  The present invention has been made paying attention to the above-described problem, and provides an engine start control device for a hybrid vehicle that can determine that the engine has a sufficient torque against friction when the engine is started. Objective.

In order to achieve the above object, the present invention provides a hybrid drive system having an engine and a motor generator, a control means for controlling the motor generator and the engine, and a battery for detecting the temperature of a battery that supplies power to the motor generator. An engine start control device for a hybrid vehicle that includes a temperature sensor and an engine water temperature sensor that detects a water temperature of the engine, and rotates the crankshaft of the engine by rotation of the motor generator when the engine is started.

The control means sets the target motor rotation speed of the motor generator to a predetermined low rotation speed when the temperature detected by the battery temperature sensor or the engine water temperature sensor is equal to or lower than a predetermined low temperature when starting the engine. When the engine is rotated at a low speed, the engine is first exploded at this low speed, and then the target motor speed is set to a predetermined high speed and the engine is rotated at a high speed, the target speed of the engine is set to Set the engine speed higher than the high engine speed, make the engine rotate at a high speed,
When the rotational speed of the engine is increased from low to high, the lower limit torque of the motor generator that performs rotational speed control to match the actual motor rotational speed with the target motor rotational speed is set to zero, and the motor generator Torque is prevented from becoming negative, and when the torque of the motor generator continues below a predetermined value for a predetermined time or more, power generation of the motor generator is permitted.

  According to this invention, when the engine is started, the engine can sufficiently output torque against the friction, and power can be generated or a driving force can be input promptly after the engine has been started.

It is a powertrain block diagram which shows the powertrain of the hybrid vehicle to which the control apparatus of Example 1 was applied. It is a control system block diagram which shows the control system of the hybrid vehicle to which the control apparatus of Example 1 was applied. FIG. 3 is a calculation block diagram illustrating an integrated controller according to the first embodiment. It is a map figure which shows the steady target torque map (a) and MG assist torque map (b) which are used with the control apparatus of Example 1. It is a map figure which shows the engine start stop line map used with the control apparatus of Example 1. FIG. It is a characteristic view which shows the request | requirement power generation output during driving | running | working with respect to battery SOC used with the control apparatus of Example 1. It is a characteristic view which shows the best fuel consumption line of the engine used with the control apparatus of Example 1. FIG. 3 is a shift map diagram illustrating an example of shift lines in the automatic transmission according to the first embodiment. 6 is a flowchart illustrating a flow of mode transition control processing executed by the integrated controller according to the first embodiment. 3 is a time chart of a mode transition control process executed by the integrated controller according to the first embodiment.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that are embodiments of an engine start control device for a hybrid vehicle according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram illustrating a hybrid drive system of a hybrid vehicle to which the engine start control device of the embodiment is applied.

  The hybrid drive system includes an engine 1, a motor generator 2, an automatic transmission 3, a first clutch 4 (mode switching means), a second clutch 5, a differential gear 6, and tires 7 and 7 (drive wheels). And.

  The hybrid vehicle according to the embodiment has a power train configuration including an engine, one motor, and two clutches. The driving mode includes a HEV mode in which the first clutch 4 is engaged and an EV mode in which the first clutch 4 is released. Have.

  The engine 1 has an output shaft connected to an input shaft of a motor generator 2 (abbreviated MG) via a first clutch 4 (abbreviated CL1) having a variable torque capacity.

  The motor generator 2 has an output shaft connected to an input shaft of an automatic transmission 3 (abbreviated as AT).

  The automatic transmission 3 has tires 7 and 7 connected to its output shaft via a differential gear 6.

  The second clutch 4 (abbreviated as CL2) uses one of the engaging elements of a clutch / brake having a variable torque capacity that is responsible for power transmission in the transmission, which varies depending on the shift state of the automatic transmission 3. . As a result, the automatic transmission 3 synthesizes the power of the engine 1 input via the first clutch 4 and the power input from the motor generator 2 and outputs them to the tires 7 and 7.

  For the first clutch 4 and the second clutch 4, for example, a wet multi-plate clutch that can continuously control the oil flow rate and hydraulic pressure with a proportional solenoid may be used. This power train system has two operation modes according to the connection state of the first clutch 4. When the first clutch 4 is disconnected, the power train system is an EV mode that runs only with the power of the motor generator 2. In the connection state 4, the HEV mode travels with the power of the engine 1 and the motor generator 2.

  The power train includes an engine rotation sensor 10 that detects the rotation speed of the engine 1, an MG rotation sensor 11 that detects the rotation speed of the motor generator 2, and an AT input that detects the input shaft rotation speed of the automatic transmission 3. A rotation sensor 12 and an AT output rotation sensor 13 for detecting the output shaft rotation speed of the automatic transmission 3 are provided.

  FIG. 2 is a control system configuration diagram illustrating a hybrid vehicle control system to which the control device of the first embodiment is applied. Hereinafter, the control system configuration will be described with reference to FIG.

  As shown in FIG. 2, the control system according to the first embodiment includes an integrated controller (control means) 20, an engine controller 21, a motor controller 22, an inverter 8, a battery 9, a solenoid valve 14, and a solenoid valve 15. An accelerator opening sensor 17, a brake hydraulic pressure sensor 23, an SOC sensor 16, an engine water temperature sensor 401 that detects the water temperature of the engine 1, and a battery temperature sensor 402 that detects the temperature of the battery 9. . The integrated controller 20, the engine water temperature sensor 401, and the battery temperature sensor 402 constitute an engine start control device.

  The integrated controller 20 performs integrated control of operating points of the powertrain system. The integrated controller 20 selects an operation mode capable of realizing the driving force desired by the driver according to the accelerator opening APO, the battery state of charge SOC, and the vehicle speed VSP (proportional to the automatic transmission output shaft rotational speed). . Then, the target MG torque and the target MG rotation speed are instructed to the motor controller 22, the target engine torque is instructed to the engine controller 21, and the drive signals are instructed to the solenoid valves 14 and 15.

  The engine controller 21 controls the engine 1. The motor controller 22 controls the motor generator 2. The inverter 8 drives the motor generator 2. The battery 9 stores electrical energy. The solenoid valve 14 controls the hydraulic pressure of the first clutch 4. The solenoid valve 15 controls the hydraulic pressure of the second clutch 5. The accelerator opening sensor 17 detects an accelerator opening (APO). The brake oil pressure sensor 23 detects brake oil pressure (BPS). The SOC sensor 16 detects the state of charge of the battery 9.

  FIG. 3 is a calculation block diagram illustrating the integrated controller 20 according to the first embodiment. Hereinafter, the configuration of the integrated controller 20 will be described with reference to FIG.

  As shown in FIG. 3, the integrated controller 20 includes a target drive torque calculation unit 100, a mode selection unit 200, a target power generation output calculation unit 300, an operating point command unit 400, and a shift control unit 500. ing.

  The target drive torque calculation unit 100 uses the target steady drive torque map shown in FIG. 4 (a) and the MG assist torque map shown in FIG. 4 (b) to calculate the target steady drive from the accelerator opening APO and the vehicle speed VSP. Calculate torque and MG assist torque.

  The mode selection unit 200 calculates an operation mode (HEV mode, EV mode) using the engine start / stop line map set at the accelerator opening for each vehicle speed shown in FIG. As indicated by the characteristics of the engine start line (SOC high, SOC low) and the engine stop line (SOC high, SOC low), the engine start line and the engine stop line are shown in FIG. Is set as a characteristic that decreases in the direction of decreasing.

  Here, in the engine start process, when the accelerator opening APO exceeds the engine start line shown in FIG. 5 in the EV mode state, the torque of the second clutch 5 is caused to slip the second clutch 5 to the half-clutch state. Control the capacity. Then, after determining that the second clutch 5 has started slipping, the first clutch 4 is started to be engaged and the engine speed is increased. When the engine speed reaches a speed at which the initial explosion is possible, the engine 1 is burned and the first clutch 4 is completely engaged when the motor speed and the engine speed become close. Thereafter, the second clutch 5 is locked up and transitioned to the HEV mode.

  The target power generation output calculation unit 300 calculates a target power generation output from the battery SOC using the traveling power generation request output map shown in FIG. Further, an output necessary for increasing the engine torque from the current operating point to the best fuel consumption line shown in FIG. 7 is calculated, and an output smaller than the target power generation output is added to the engine output as a required output.

  The operating point command unit 400 inputs the accelerator opening APO, the target steady torque, the MG assist torque, the target mode, the vehicle speed VSP, and the required power generation output. Then, using these input information as the operating point reaching target, a transient target engine torque, target MG torque, target CL2 torque capacity, target speed ratio, and CL1 solenoid current command are calculated.

  Further, when the operating point command unit 400 starts the engine 1 by directly connecting the motor generator 2 and the engine 1 by the first clutch 4, the temperature detected by the engine water temperature sensor 401 or the battery temperature sensor 402 is low. First, set the target motor speed to the low cranking speed, and then gradually increase the target motor speed to the high cranking speed. The number is set to a value higher than its high rotation.

  The shift control unit 500 drives and controls the solenoid valve in the automatic transmission 3 so as to achieve these from the target CL2 torque capacity and the target gear ratio. FIG. 8 shows an example of a shift line map used in the shift control. From the vehicle speed VSP and the accelerator opening APO, it is determined how many of the next shift stage from the current shift stage, and if there is a shift request, the shift clutch is controlled to change the speed.

[Operation]
Next, the processing operation of the control process executed by the integrated controller 10 of the FR hybrid vehicle will be described based on the flowchart shown in FIG. 9 and the time chart shown in FIG.

When the vehicle accessory switch ACC is turned on at time t0 in FIG. 10, the integrated controller 20 starts an engine start control operation based on the flowchart shown in FIG.
Here, in FIG. 10, Mnd represents a target motor rotation speed setting line of the motor generator 2, and EMn represents the actual rotation speed of the motor generator 2 (actual motor rotation speed) and the actual rotation speed of the engine 1 (actual engine rotation speed). Number) actual rotation characteristic line. In this target motor rotation speed setting line Mnd, N1 indicates the target low rotation speed of the motor generator 2, Nx indicates the target increase rotation speed for gradually increasing the rotation speed of the motor generator 2 from the target low rotation speed N1, N2 indicates the target high rotation speed of the motor generator 2 (N1 <Nx <N2). Further, Mt represents the actual motor torque curve of the motor generator 2 (actual motor torque line), Mt0 is minimum torque of the motor torque line Mt "0Nm", Mt1 the phase of the motor torque line Mt (Phase) 1 The upper motor torque at is greater than the lower limit torque Mt0.

  Etd represents a target engine torque setting line of the engine 1, and Etx represents an actual torque change line of the engine 1. In the target engine torque setting line Etd, Etd1 indicates the target engine low rotation torque, and Etd2 indicates the target engine high rotation torque. KT is an engagement torque line indicating the engagement torque of the second clutch 5.

  When the accessory switch ACC of the vehicle is turned on, the integrated controller 20 determines whether or not the ignition IGN is turned on in step S1. If it is determined in this determination that the ignition IGN is not turned on, the process ends. If the ignition IGN is turned on at the time t1 in FIG. 10, the process proceeds to step S2.

  In step 2, it is determined whether or not the battery temperature is low (extremely low) based on a temperature detection signal from the battery temperature sensor 402. If no, the process proceeds to step 12, and if yes, the process proceeds to step 3.

  In step 12, it is determined whether or not the engine water temperature is low (extremely low) based on the water temperature detection signal from the engine water temperature sensor 401. If no, the process ends. If yes, the process proceeds to step 3.

  That is, when the battery temperature or the engine water temperature is low, the process proceeds to step 3, and otherwise the process ends. The judgment in each step 1, 2, and 12 is performed by the integrated controller 20, and the engine water temperature and the battery temperature are obtained through the CAN system of the vehicle.

  In step 3, the target rotational speed of the motor generator 2 is set to the low cranking rotational speed N1, the first clutch 4 is engaged, and the motor generator 2 is rotated at the target rotational speed N1 (FIG. 10). Time t1). At this time, the second clutch 5 is released. Then, the engine 1 is rotated at a low cranking speed N1 by the rotation of the motor generator 2.

That is, in the period of Phase 1 of FIG. 10, the engine 1 in the stopped state will by cranking rotation of low rotation, is intended to initial combustion engine 1.

Here, cranking means rotating the crankshaft of the engine 1, and cranking speed means the crankshaft speed of the engine 1. Further, the actual motor torque (actual motor torque) will Mt1 In Phase 1.

In the period of this Phase 1, to compensate for the battery output of 6 kw. Further, in order to detect the rotational speed of the engine 1, it is necessary to rotate the engine 1 three times (72 rpm) in 2.5 seconds. Therefore, in this embodiment, the target rotational speed N1 is set to 150 rpm. Furthermore, the lower limit torque of the motor generator 2 is set to 0 Nm so that the engine speed is not depressed. The period of Phase 1 (point t1~ time t2) is about 2.5 seconds.

  When the engine 1 begins to detonate for the first time, the actual rotational speeds of the engine 1 and the motor generator 2 increase (time t2 in FIG. 10).

In step 4, whether the engine speed is equal to or more than a threshold is namely it is determined whether Phase 1 is completed, the process returns to step 3, if no, Step 3 and 4 until the engine rotational speed is equal to or greater than the threshold value The processing operation is repeated. Here, the threshold value is, for example, 500 rpm. When the engine speed becomes equal to or greater than the threshold value, it is determined as YES in step 4 and the process proceeds to step 5.

In step 5, the target rotational speed of the motor generator 2 is increased to the cranking rotational speed N2 of high rotation (time t3 to time t4 in FIG. 10). That is a state of Phase 2 shown in FIG. 10. In the period of the Phase 2, to compensate for the battery output of 2.8 kw, it is intended to gradually increase the target rotation speed Nx to not power wasted, but to a so-called ramp-up. At this time, the lower limit torque of the motor generator 2 is set to 0 Nm so that the rotational speed of the engine 1 is not depressed.

  In step 6, it is determined whether or not the target rotational speed of the motor generator 2 has reached a high cranking rotational speed. If yes, the process proceeds to step 7, and if no, the process returns to step 5. That is, the processing operations of Steps 5 and 6 are repeatedly performed until the target rotational speed Nx reaches the high cranking rotational speed N2.

  Here, when the rotation of the engine 1 exceeds the target low speed N1 and the engine 1 is operated, the actual motor torque Mt1 indicated by the motor torque line Mt starts to decrease from the time t2, so that the negative torque to the motor generator 2 is reduced. That is, the torque amount (FB amount) in the direction opposite to the rotation direction of the motor generator 2 is reduced (restricted), and the cranking rotation speed of the engine 1 can be quickly increased to the high rotation side. The time required to overcome the friction (friction resistance) of one movable part and complete the start-up can be shortened.

  In step 7, the target rotational speed of the motor generator 2 is set to a high cranking rotational speed N2 (time t4 in FIG. 10).

  In step 8, the target rotational speed of the engine 1 is set to a value EN3 (EN3 = N2 + α) obtained by adding α to the target rotational speed N2 of the motor generator 2.

  In step 9, it is determined whether or not the time during which the torque of the motor generator 2 (actual motor torque) is equal to or less than a predetermined value (negative or less) has continued for a predetermined time or more. If so, the process returns to step 7, and the processing operations of steps 7 to 9 are repeated until the time during which the actual motor torque is negative or less continues for a predetermined time or longer.

  Here, when the engine 1 starts to generate torque, the torque of the motor generator 2 (actual motor torque) decreases. When the engine 1 generates a sufficient torque against the friction, the actual motor torque becomes negative (time t5 in FIG. 10).

  The actual motor torque is obtained by the integrated controller 20 from the current and voltage of the motor generator 2.

Processing period in step 7-9 is equivalent to a period of Phase 3 shown in FIG. 10, the period of the Phase 3, the engine 1 is torque by the engine speed 1000rpm causes the complete explosion of the engine 1 It is a period to wait until it is put out. In this period, for example, a battery output of 2.8 kw is compensated.

  When the time during which the actual motor torque is negative (time t5 to time t6) exceeds a predetermined time, the process proceeds to step 10.

  In step 10, power generation is permitted. In other words, the actual motor torque of the motor generator 2 continues to be negative or lower for a predetermined time or longer, so that the engine 1 outputs a sufficient torque against the friction. For this reason, even if the motor generator 2 generates power, no engine stall occurs, and the motor generator 2 can quickly generate power without considering the safety margin as in the prior art.

  In step 11, an increase in the engagement torque of the second clutch 5 is permitted and the clutch 5 is engaged. As in step 10, since the engine 1 outputs a sufficient torque against the friction, it is possible to prevent engine stall due to a load on the engine 1.

Next, the effects of the engine start control device for a hybrid vehicle configured as described above will be summarized below.
(1) Since the target rotational speed of the engine 1 is set to a value added to the target rotational speed of the motor generator 2 in step 8, the engine 1 rotates at a rotational speed higher than the idle rotational speed. For this reason, when the engine is started, the engine 1 can output a sufficient torque against the friction, and the motor generator 2 can quickly generate power, or the driving force of the engine 1 can be input to the transmission 3. Can do.
(2) In the Phase 1 and 2 are shown in FIG. 10, since a lower limit torque of the motor generator 2 to 0 Nm, without inhibiting the rotation rise of the engine 1 can be quickly the reduction of the friction of the engine 1.
(3) As shown in steps 9 and 10, power generation is permitted when the time during which the torque of the motor generator 2 is less than negative continues for a predetermined time or longer. The power generation is permitted after the torque is reliably output, and therefore the engine stall caused by the load applied to the engine 1 by the power generation can be reliably prevented.
(4) Similarly, since the torque increase of the second clutch 5 is permitted when the time during which the torque of the motor generator 2 is negative or less continues for a predetermined time or more, the engine 1 is sufficiently resistant to the friction when the engine is started. The torque increase is permitted after the torque is reliably output, and therefore engine stall due to the load applied to the engine 1 due to the engagement of the second clutch 5 can be reliably prevented.

  As mentioned above, although the engine start control apparatus of the hybrid vehicle of this invention has been demonstrated based on the Example, it is not restricted to these Examples about a concrete structure, It concerns on each claim of a claim Design changes and additions are allowed without departing from the scope of the invention.

For example, in step 4, but the end of Phase 1 are judged by whether or not the engine rotational speed is equal to or larger than the threshold may be determined by time. For example, the determination may be made based on whether or not 2.5 seconds have elapsed since the start of cranking.

  In the above-described embodiment, the second clutch 5 is provided in the automatic transmission 3. However, the present invention is not limited to this. For example, the second clutch 5 is provided between the motor generator 2 and the automatic transmission 3, or between the automatic transmission 3 and the differential gear 6. You may provide between.

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Motor generator 4 ... 1st clutch (mode switching means)
5 ... Second clutch (clutch element)
7. Tires (drive wheels)
9 ... Battery 10 ... Engine rotation sensor (Engine operation detection means)
11 ... MG rotation sensor (motor rotation sensor)
20 ... Integrated controller (engine start control means)
401 ... Engine water temperature sensor 402 ... Battery temperature sensor 600 ... Engine start control device

Claims (2)

In a hybrid drive system having an engine and a motor generator, control means for controlling the motor generator and the engine;
A battery temperature sensor for detecting a temperature of a battery for supplying electric power to the motor generator;
An engine water temperature sensor for detecting the water temperature of the engine ,
An engine start control device for a hybrid vehicle that rotates a crankshaft of the engine by rotation of the motor generator when starting the engine,
The control means sets the target motor rotation speed of the motor generator to a predetermined low rotation speed when the temperature detected by the battery temperature sensor or the engine water temperature sensor is equal to or lower than a predetermined low temperature when starting the engine. When the engine is rotated at a low speed, the engine is first exploded at this low speed, and then the target motor speed is set to a predetermined high speed and the engine is rotated at a high speed, the target speed of the engine is set to Set the engine speed higher than the high engine speed, make the engine rotate at a high speed,
When the rotational speed of the engine is increased from low to high, the lower limit torque of the motor generator that performs rotational speed control to match the actual motor rotational speed with the target motor rotational speed is set to zero, and the motor generator An engine start control device for a hybrid vehicle that prevents the torque from becoming negative and permits the motor generator to generate electric power when the torque of the motor generator continues below a predetermined value for a predetermined time or more . A clutch interposed between the motor generator and the drive wheel;
2. The hybrid vehicle according to claim 1, wherein the rotational speed of the engine is increased to a high speed, and the fastening force of the clutch is increased when the torque of the motor generator continues below a predetermined value for a predetermined time or longer. Engine start control device.