JP2012086662A - Engine start control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine start control device for vehicles, which can set an optimum engine start torque of the right amount for completing engine start in a predetermined time from engine start request, in consideration of variation for each engine rotation stop position immediately before engine start time.SOLUTION: An electric motor running operation region A, in which an output torque range is specified, is set according to a rotation speed Nof the electric motor 12 so that the engine start torque Ts, which is output from an electric motor 12 at engine start time during running of the electric motor, may be calculated based on an engine rotation stop position Pimmediately before engine start time to become a minimum necessary value for the engine start torque Ts to start the engine 14, and so that when the electric motor is running, the electric motor 12 may be operated in a state that remaining power of the engine start torque Ts is left.

Description

  The present invention relates to a vehicle engine start control device, and more particularly to a technique for setting an optimal engine start torque for each rotation stop position of an engine.

  2. Description of the Related Art A vehicular engine start control device is known that includes an electric motor and an engine and is used in a vehicle driven by at least one of the engine and the electric motor. For example, this is the control device described in Patent Document 1.

  In Patent Document 1, when a driver's requested output is detected and the vehicle is driven only by an electric motor, the motor satisfies the above-mentioned requested output within a range that leaves a surplus torque corresponding to a preset engine starting torque. A control device is described that controls the gear ratio of a transmission coupled to an electric motor so as to achieve speed.

Japanese Patent Laid-Open No. 2000-177412

  By the way, when the engine is started by the electric motor only by the electric motor, the engine starting torque for starting the engine is further added to the driving torque for driving the vehicle in order to suppress the occurrence of shock. Is required to be output from. In response to a request for improving drivability, it is required to increase the engine speed to a predetermined value within a predetermined time from the engine start request that is set in advance for the early completion of the engine start. It is desirable that the engine start torque be as small as possible. However, the optimum engine start torque that is sufficient to increase the engine speed to the predetermined speed at the time when the predetermined time elapses is the engine start torque immediately before the start of the engine start. In order to vary for each rotation stop position, in the conventional vehicle engine start control device, the engine start torque is set relatively high so as to cope with the variation. Therefore, the motor travel operating region that defines the output torque range output from the motor for driving the vehicle during motor travel is limited by the magnitude of the engine starting torque set as described above, and the engine is not used. In addition, there is a problem that the vehicle fuel efficiency improvement effect by driving the vehicle with only the electric motor is weakened.

  The present invention has been made against the background of the above circumstances, and the object of the present invention is to provide an optimal engine start torque with no excess or shortage in order to complete the engine start in a predetermined time from the engine start request. An object of the present invention is to provide a vehicular engine start control device that can be optimally set in consideration of variations at each rotation stop position of the engine immediately before starting.

  The gist of the invention according to claim 1 for achieving the object is as follows. (A) A vehicle including an electric motor and an engine started by the electric motor, and driven by at least one of the engine and the electric motor. An engine start control device for a vehicle used, wherein (b) an engine start torque output from the motor when the engine is started while the motor is driven only by the motor is used to rotate the engine immediately before the start of the engine. (C) An output torque range is determined in accordance with the rotational speed of the motor so that the motor operates in a state where a surplus power corresponding to the engine starting torque remains while the motor is running. It is to set the electric motor traveling operation area.

  Further, the gist of the invention according to claim 2 is that, in the invention according to claim 1, the engine start torque is detected immediately before the start of the engine detected from the crank angle of the engine from a previously stored relationship. Is calculated based on the engine rotation stop position.

  The gist of the invention according to claim 3 is that, in the invention according to claim 2, the engine is an in-cylinder injection engine, and the engine starting torque is determined from the relationship stored in advance. The calculation is based on the coolant temperature and the rotation stop position of the engine immediately before the start of the engine detected from the crank angle of the engine.

  The gist of the invention according to claim 4 is that, in the invention according to claim 3, (a) a clutch device is provided between the engine and the electric motor, and (b) the engine It is to be rotated and driven by the engine starting torque transmitted from the electric motor through the clutch device.

  According to the vehicle engine start control device of the first aspect of the present invention, the engine start torque output from the motor when the engine is started while the motor is running only by the motor is the rotation stop position of the engine immediately before the engine start is started. An electric motor travel operation region in which an output torque range is determined in accordance with the rotational speed of the motor is set so that the motor operates in a state where the remaining power for the engine starting torque remains while the motor is traveling. The Therefore, an optimal engine start torque that is sufficient for completing the engine start within a predetermined time can be optimally set in consideration of variations for each engine rotation stop position immediately before the start of the engine start. As a result, the vehicle can be driven by the electric motor as much as possible while leaving a surplus of engine starting torque, and vehicle fuel efficiency is improved.

  According to the vehicle engine start control device of the invention according to claim 2, the engine start torque is detected from the crank angle of the engine based on the relationship stored in advance, and the engine rotation stop immediately before the engine start is started. Since it is calculated on the basis of the position, the engine rotation stop position immediately before the start of the engine, which is detected based on the crank angle of the engine, the optimum engine start torque that is sufficient for the completion of the engine start within the predetermined time is detected. It is possible to set optimally in consideration of each variation.

  According to the vehicle engine start control device of the invention of claim 3, the engine is an in-cylinder injection engine, and the engine start torque is calculated from the relationship between the cooling water temperature of the engine and the engine from the relationship stored in advance. It is calculated based on the rotation stop position of the engine immediately before the start of the engine detected from the crank angle of the engine. Therefore, when the engine is started by direct-injection self-ignition in a direct injection type engine, the optimum engine start torque that is sufficient for completing the engine start in a predetermined time is obtained from the engine cooling water temperature and the engine rotation stop position. Even when there is a variation due to the difference, the optimum engine starting torque can be set in consideration of the variation.

  According to the vehicle engine start control device of the invention of claim 4, the clutch device is provided between the engine and the electric motor, and the engine is driven by the engine start torque transmitted from the electric motor through the clutch device. Since the engine is started by being rotated, when the engine is started, the engine can be rotationally driven by the engine starting torque obtained from the engagement energy of the clutch device in addition to the torque obtained from the explosion energy by ignition.

It is a figure which shows notionally the drive system and control system of the hybrid vehicle of one Example of this invention. It is sectional drawing which shows the electric motor of FIG. 1, a torque converter, and the automatic transmission and crankshaft which were notched partially. It is a functional block diagram for demonstrating the principal part of the control function with which the electronic control apparatus of FIG. 1 was equipped. In the two-dimensional coordinates represented by the motor rotational speed axis and the motor output torque axis, the motor operating area during motor driving, that is, the motor driving operating area in which the output torque range of the motor is determined according to the motor rotating speed is shown. FIG. It is a figure which shows the relationship between an engine rotation stop position and an engine starting torque. It is a figure which shows the relationship between engine cooling water temperature and the learning correction coefficient of engine starting torque. When starting the direct injection engine, if the engine start torque is a constant value regardless of the engine rotation stop position immediately before the start of the engine start, the engine rotation speed is determined to be a predetermined rotation based on the rotation stop position and the engine start request. It is the figure which showed the relationship with time to reach | attain speed. It is a flowchart explaining the principal part of the control action performed by the signal processing of the electronic controller of FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a diagram conceptually showing the structure of a drive system of a hybrid vehicle 10 according to one embodiment of the present invention. As shown in FIG. 1, the hybrid vehicle 10 includes an electric motor 12 and an engine 14 that is started by the electric motor 12. The power from the electric motor 12 and the engine 14 is transmitted to the pair of left and right drive wheels 24 via the torque converter 16, the automatic transmission 18, the differential gear device 20, and the pair of left and right axles 22, respectively. The hybrid vehicle 10 is driven by one, the other, and both of the electric motor 12 and the engine 14. That is, the hybrid vehicle 10 is in any one of the traveling states of motor traveling (motor traveling) using only the electric motor 12, engine traveling using only the engine 14, and hybrid traveling using the electric motor 12 and the engine 14.

  The engine 14 is configured by a direct injection gasoline engine or a diesel engine in which fuel is directly injected into the combustion chamber, and an output member of the engine 14, that is, a crankshaft 26 is connected to a rotor 30 of the electric motor 12 via a clutch 28. Are selectively connected to each other. The rotor 30 of the electric motor 12 is connected to the input member of the torque converter 16, that is, the front cover 32. The clutch 28 is a hydraulic friction engagement device, and interrupts the power transmission path between the clutch shaft 26 and the front cover 32 according to the hydraulic pressure supplied from the hydraulic control circuit 34.

  FIG. 2 is a cross-sectional view showing the electric motor 12, the torque converter 16, the automatic transmission 18 and the crankshaft 26, which are partially cut away, in FIG. The electric motor 12, the torque converter 16, the automatic transmission 18, and the crankshaft 26 are configured substantially symmetrically with respect to their common axis C, and the lower half of the axis C is omitted in FIG. ing.

  As shown in FIG. 2, the electric motor 12, the torque converter 16, and the automatic transmission 18 are accommodated in a transmission case 36. The transmission case 36 is a split type case made of, for example, aluminum die casting, and is fixed to a vehicle body or the like.

  The clutch 28 includes a cylindrical clutch drum 38, a cylindrical clutch hub 40 that is smaller in diameter than the clutch drum 38, provided concentrically with the clutch drum 38 and is rotatable relative to the clutch drum 38, and the clutch drum 38 and the clutch hub. A friction engagement member 42 provided in an annular gap between the friction engagement member 42 and a clutch piston 44 that presses the friction engagement member 42 in the direction of the axis C is provided.

  The clutch drum 38 is integrally fixed to a boss portion 30 a described later of the rotor 30 of the electric motor 12 by, for example, welding, and is provided so as to be rotatable together with the rotor 30.

  The frictional engagement member 42 is provided between a plurality of annular plate-like separators engaged with the clutch drum 38 so as not to rotate relative to each other, and is engaged with the clutch hub 40 so as not to rotate relative to each other. And a plurality of annular plate-like friction plates.

  In the clutch 28 configured as described above, when the friction engagement member 42 is pressed in the direction of the axis C by the clutch piston 44 and the separator and the friction plate are frictionally engaged with each other, the clutch drum 38 and the clutch Relative rotation with the hub 40 is suppressed. As a result, the clutch drum 38 and the clutch hub 40 can transmit power to each other.

  The output end of the crankshaft 26, that is, one end on the side of the electric motor 12, is connected to a rotating shaft 48 connected to the clutch hub 40 of the clutch 28 via drive plates 46 and 47, respectively. The crankshaft 26 and the clutch hub 40 are connected to each other via drive plates 46 and 47 and a rotary shaft 48 so as to be rotatable.

  The electric motor 12 includes a rotor 30 that is rotatably supported around the axis C by a transmission case 36 on the outer peripheral side of the rotating shaft 48, and a stator 50 that is integrally fixed to the transmission case 36 on the outer peripheral side of the rotor 30. It has.

  The rotor 30 is in a state in which a slight gap is provided between the cylindrical boss portion 30a rotatably supported by the transmission case 36 via a pair of bearings 52 and the stator 50 on the inner peripheral side of the stator 50. The rotor part 30b which has the some annular steel plate laminated | stacked by the axial center C direction, and the connection part 30c which connects these boss | hub parts 30a and the rotor part 30b integrally are provided. The rotor 30 is coupled to the front cover 32 via a transmission member 54 that is coupled to the inner peripheral side of the rotor portion 30b and is integrally fixed to the front cover 32 by, for example, welding.

  The stator 50 is annularly wound around a part of the inner circumferential portion of the core 50a in which a plurality of annular steel plates are laminated in the direction of the axis C, and continuously in the circumferential direction. A plurality of coils 50b are provided. The stator 50 is integrally fixed to the transmission case 36 by a plurality of bolts 53 at a plurality of locations in the circumferential direction.

  The electric motor 12 configured as described above is connected to a power storage device (not shown) such as a battery or a capacitor via the inverter 56 of FIG. 1, and the drive current supplied to the coil 50b is adjusted by controlling the inverter 56. As a result, the output torque from the electric motor 12 is increased or decreased. The output torque from the electric motor 12 is output only to the torque converter 16 when the clutch 28 is not engaged, but when the clutch 28 is engaged, a part of the output torque is output to the torque converter 16 and the other part is It is output to the engine 14.

When the engine 14 is started, the engine 14 is driven to rotate by the torque for starting the engine transmitted from the electric motor 12 via the clutch 28, and the engine rotational speed _NE is increased. The engine 14 is started by controlling supply and the like. In other words, the engine 14 is started by the torque obtained from the explosion energy by ignition and the torque obtained from the engagement energy by the clutch 28, that is, the engine start torque T _S transmitted from the electric motor 12 through the clutch 28. This is done by being driven to rotate. At this time, the electric motor 12 functions as an engine starter motor.

  FIG. 1 is also a block diagram illustrating a control system of the hybrid vehicle 10. In FIG. 1, the electronic control unit 58 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The electronic control unit 58 performs signal processing according to a program stored in advance in the ROM while the CPU uses the temporary storage function of the RAM, thereby controlling the output of the engine 14, the start control of the engine 14, and the automatic transmission 18. Shift control, engagement force control of the clutch 28, and the like are executed. The electronic control device 58 functions as a vehicle engine start control device.

Various input signals detected by each sensor provided in the hybrid vehicle 10 are supplied to the electronic control unit 58. Examples of the input signal include a signal representing the accelerator opening Acc [%] detected by the accelerator opening sensor 60, a signal representing the motor rotation speed N _MG [rpm] detected by the motor rotation speed sensor 62, and the engine. A signal representing the engine rotational speed N _E [rpm] detected by the rotational speed sensor 64, a signal representing the rotational angle of the crankshaft 26 detected by the crank position sensor 66, that is, a crank angle ACR [°], and a vehicle speed sensor 68 There is a signal representing the vehicle speed V [km / h], a signal representing the cooling water temperature T _W [° C.] of the engine 14 detected by the water temperature sensor 70, and the like.

  Various output signals are supplied from the electronic control device 58 to each device provided in the hybrid vehicle 10. Examples of the output signal include a signal supplied to the inverter 56 for output control of the electric motor 12 and a signal supplied to the hydraulic control circuit 34 for controlling the engagement force of the clutch 28 and the like.

FIG. 3 is a functional block diagram for explaining the main part of the control function provided in the electronic control unit 58. In FIG. 3, the motor travel control means 72 operates in a state where the motor 12 is operated with only the motor 12, and the motor 12 is left with an engine start torque T _S output from the motor 12 to the engine 14 when the engine is started. Let

4 shows, in a two-dimensional coordinate represented by the output torque shaft of the electric motor speed shaft and the electric motor 12, the operating range of the electric motor 12 in motor driving, that is, the output of the electric motor 12 in accordance with the motor rotation speed N _MG An electric motor travel operation area A in which a torque range is defined is indicated by hatching. Motor cars actuation area A, when a vehicle travels forward by the electric motor 12, the motor 12 is set so as to further output torque scope of the motor 12 being a state capable of outputting the engine starting torque T _S is as possible increases ing. That is, the motor travel operation area A is a value obtained by subtracting the engine starting torque T _S [Nm] from the maximum output torque T _MAX [Nm] of the motor 12 indicated by the solid line in FIG. 4, that is, the value indicated by the dotted line in FIG. Is set in the output torque range.

The motor travel control means 72 outputs the output torque T of the motor 12 corresponding to the driver's required output in the two-dimensional coordinates of the axis indicating the motor rotation speed _NMG and the axis indicating the output torque _TMG of the motor 12 in FIG. _{When the} operating point indicated by the _MG and the motor rotation speed _NMG is within the motor travel operating region A, the motor travel is performed only by the motor 12. Therefore, while the motor is running by the motor running control means 72, the engine 14 can be started by the motor 12 while running the motor according to the output requested by the driver using only the motor 12. That is, it is possible to output, in addition to the driving torque for the vehicle drive output from the electric motor 12 to the drive wheels 24, the engine starting torque T _S for starting the engine from the electric motor 12 to the engine 14.

  While the motor is running, the clutch 28 is basically in an unengaged state except when the engine 14 is started. Then, the output from the electric motor 12 is transmitted to the pair of drive wheels 24 through the torque converter 16, the automatic transmission 18, and the like, so that the vehicle is driven.

The engine start control means 74 determines whether or not the hybrid vehicle 10 is running on an electric motor (during EV running). For example, the engine start control means 74 determines whether or not the operating point indicated by the output torque T _MG of the electric motor 12 and the electric motor rotational speed N _MG corresponding to the driver's requested output is within the electric motor travel operating area A of FIG. Based on the above, it is determined whether or not the hybrid vehicle 10 is running on an electric motor.

Further, the engine start control means 74 has an engine start torque T _S output from the electric motor 12 when starting the engine 14 while the electric motor is running at a minimum necessary value for engine start, that is, a necessary and sufficient value. based manner, a predetermined stored relationship obtained in a rotation stop position, that is the engine rotation stop position P _{BTDC [°]} of the crankshaft 26 of the engine 14 in the engine starting immediately before the start, and cooling water temperature T _W of the engine 14 Te, and calculates the engine starting torque _{T S.} The minimum required value for starting the engine is an optimum value that is sufficient for completing the engine start in a predetermined time set in advance for the purpose of improving drivability, for example, a minimum value for starting the engine. Is a value obtained by adding a predetermined margin such as absorbing variation. The engine rotation stop position P _BTDC is the rotation stop position of the crankshaft 26 when any one of the plurality of pistons of the engine 14 is located at the top dead center (TDC). Is a value represented by an angle from the 0 [°] position to the rear side in the rotation direction.

The engine start control means 74 first detects the engine rotation stop position P _BTDC immediately before the start of the engine based on the crank angle ACR of the engine 14. Subsequently, the standard engine starting torque T _SS is calculated based on the engine rotation stop position P _BTDC from a previously stored relationship as shown in FIG. 5, for example. Subsequently, the temperature correction coefficient a for learning correction according the standard engine starting torque T _SS in the cooling water temperature T _W, a predetermined stored relationship shown in FIG. 6, for example, cooling water temperature T of the engine 14 Calculate based on _W. Subsequently, from the relationship stored in advance (T _S = T _SS × a), from the motor 12 to the engine 14 at the next engine start based on the calculated standard engine start torque T _SS and the temperature correction coefficient a. calculating the engine startup torque T _S to be outputted.

Relationship shown in FIG. 5 and 6, the engine starting torque T _S that is output from the electric motor 12 during motor travel, in accordance with the engine rotation stop position immediately before starting the engine start P _BTDC and the engine coolant temperature T _W, wherein It is experimentally determined in advance so that the minimum value required for starting the engine, that is, an optimal value without excess or deficiency for completion of starting the engine at a preset predetermined time.

7, at the start of a direct injection type engine 14, when the engine starting torque T _S is constant value regardless of the engine rotation stop position P _BTDC immediately before engine start up, the engine rotation stop position P _BTDC When the predetermined rotational speed, or 200 the engine speed _{N E} from the engine start request [rpm], which is a graph showing each relationship between the time t to reach the 400 [rpm], and 600 [rpm]. As shown in FIG. 7, the time t according to the engine start request to the engine rotational speed N _E is raised above the predetermined rotation speed, the engine rotation stop position P _BTDC immediately before engine start up is away from 0 [°] The longer they are, the longer they are. Therefore, the relationship shown in FIG. 5 is that the engine rotation stop position P _BTDC immediately before the start of the engine is farther from 0 [°], that is, 80 [°] before the top dead center than 20 [°] before the top dead center. It is set as the side as the engine starting torque T _S increases.

Further, in the engine 14 for a cylinder injection type straight噴自ignition is performed, the engine 14 is higher viz the engine coolant temperature T _W is increased the higher the ignition rate at high temperatures. Therefore, the torque resulting from the explosion energy by the ignition increases as the engine coolant temperature T _W is higher. Thus, the relationship shown in FIG. 6, as the engine coolant temperature T _W is higher as the engine starting torque T _S is reduced, it is set so that the engine coolant temperature T _W is higher as the temperature correction coefficient a decreases.

Further, the engine start control means 74 determines whether or not the driver's requested output cannot be output only by the electric motor 12 while leaving a surplus power corresponding to the engine start torque T _S during running of the electric motor. That is, it is determined whether or not the sum of the output torque T _MG of the electric motor 12 corresponding to the driver's requested output and the engine starting torque T _S is larger than the maximum output torque T _MAX of the electric motor 12.

If the engine start control means 74 determines in the above determination that the output requested by the driver cannot be output only by the electric motor 12 while remaining the engine start torque T _S , the engine start request is issued. It is determined that it has been done and the engine 14 is started. At that time, the engine start control means 74 outputs the engine start torque T _S from the motor 12 to the engine 14 by engaging the clutch 28 while outputting the output torque T _MG from the motor 12 to the drive wheel 24. Then, after the engine speed _NE is raised to some extent, the engine 14 is started by controlling engine ignition, fuel supply, and the like. Thus, in addition to the driving torque or output torque T _MG for driving the hybrid vehicle 10, the engine starting torque T _S for rotating the engine 14 that is output, the shock at the start of the engine occurs Is to be suppressed. When the engine is started, the lock-up clutch 76 of the torque converter 16 is released to suppress the occurrence of shock.

Further, the engine start control means 74, that as is the motor driving operation region A while leaving the margin of the engine starting torque T _S component output from the electric motor 12 to the engine 14 during the engine start becomes as much as possible increases An electric motor travel operation area A is set. That is, each time the engine start torque T _S is increased or decreased, the engine start control means 74 runs the motor so that the output torque range of the motor 12 becomes as large as possible while remaining the engine start torque T _S. Increase or decrease the operating area A. Given example, when the engine starting torque T _S is corrected to be smaller by a predetermined value △ T, as shown by the one-dot chain line in FIG. 4, the output torque range of the motor 12 is in each electric motor rotation speed N _MG The electric motor traveling operation area A is increased by increasing the value ΔT. Predetermined Further, when the engine starting torque T _S is corrected to be larger by a predetermined value △ T, as indicated by the two-dot chain line in FIG. 4, the output torque range of the motor 12 is in each electric motor rotation speed N _MG The electric motor traveling operation area A is reduced by decreasing the value ΔT.

  FIG. 8 is a flowchart for explaining the main part of the control operation executed by the signal processing of the electronic control unit 58. This flowchart is for explaining the control operation for starting the engine among the control operations by the electronic control unit 58, and is repeatedly executed with a very short cycle time of about several milliseconds to several tens of milliseconds, for example. All the steps in FIG. 5 correspond to the engine start control means 74.

In FIG. 8, in step (hereinafter, “step” is omitted) S <b> 1, for example, the operating point indicated by the output torque T _MG and the motor rotation speed N _{MG of the} motor 12 corresponding to the driver's requested output is shown in FIG. 4. Whether or not the hybrid vehicle 10 is running on an electric motor (EV running) is determined based on whether or not it is within the electric motor running operating area A.

If the determination at S1 is negative, this routine is terminated. When the determination in S1 is affirmative, in S2, the engine starting torque T _S that is output from the electric motor 12 when starting the engine 14 in a motor traveling, the engine starting torque T _S engine start From the relationship obtained in advance so as to be the minimum necessary value for the engine, the rotation stop position P _BTDC [°] of the crankshaft 26 of the engine 14 immediately before the start of the engine, that is, the engine rotation stop position P _BTDC [°] It is calculated on the basis of the water temperature T _W. Specifically, first, based on the crank angle ACR of the engine 14, the engine rotation stop position _PBTDC immediately before the start of the engine is detected. Subsequently, the standard engine start torque T _SS is calculated based on the engine rotation stop position P _BTDC from a previously stored relationship as shown in FIG. Subsequently, the standard engine starting torque T _SS temperature correction coefficient a for learning correction in accordance with the cooling water temperature T _W is, for example, from a pre-stored relationship shown in FIG. 6, the cooling water temperature T of the engine 14 Calculated based on _W. Subsequently, from the relationship stored in advance (T _S = T _SS × a), from the motor 12 to the engine 14 at the next engine start based on the calculated standard engine start torque T _SS and the temperature correction coefficient a. engine starting torque T _S to be outputted is calculated.

Further, in S2, when the engine starting torque T _S is increased or decreased, the motor travel operation region A is set so that the output torque range of the motor 12 becomes as large as possible while remaining the engine starting torque T _S. Is increased or decreased.

Then, in S3, whether the request output by the driver while leaving margin for engine starting torque T _S partial motor 12 only in non-output is determined. Specifically, it is determined whether or not the sum of the output torque T _MG of the electric motor 12 corresponding to the driver's requested output and the engine start torque T _S is larger than the maximum output torque T _MAX of the electric motor 12. . When the sum of the output torque T _MG of the electric motor 12 corresponding to the driver's requested output and the engine starting torque T _S is larger than the maximum output torque T _MAX of the electric motor 12, the remaining power for the engine starting torque T _S is obtained. It is determined that the output requested by the driver cannot be output only by the electric motor 12 while leaving it.

  If the determination in S3 is negative, this routine is terminated. If the determination at S3 is affirmative, it is determined that an engine start request has been made, the engine 14 is started at S4, and this routine is terminated.

As described above, according to the electronic control device 58 of this embodiment that functions as a vehicle engine start control device, the engine start torque output from the motor 12 when the engine 14 is started while the motor is driven by the motor 12 alone. the T _S, is calculated based on the engine rotation stop position P _BTDC at engine start immediately before, during motor travel to the electric motor 12 is operated while leaving a margin of the engine starting torque T _S content, the motor 12 An electric motor travel operation region A in which an output torque range is determined according to the rotational speed _NMG is set. Therefore, an optimum engine starting torque T _S just enough for the engine start completion within a predetermined time, it is optimally set in consideration of variations among the engine rotation stop position P _BTDC in the engine starting immediately before the start it can. Therefore, while leaving margin for engine starting torque T _S content also can drive the hybrid vehicle 10 by as much as possible the electric motor 12, the vehicle fuel economy is improved.

Further, according to the electronic control device 58 of the present embodiment, the engine starting torque T _S for starting the engine 14, a predetermined stored relationship, the engine starting just before the start detected by the crank angle 26 of the engine 14 from being calculated based on the engine rotation stop position P _BTDC in an optimum engine starting torque T _S just enough for the engine start completion within a predetermined time, detected by the crank angle 26 of the engine 14 It can be optimally set in consideration of the variation for each engine rotation stop position P _BTDC immediately before the start of engine start.

Further, according to the electronic control device 58 of the present embodiment, the engine 14 is a direct injection engine, the engine starting torque T _S for starting the engine 14, a predetermined stored relationship, the cooling of the engine 14 It is calculated based on the engine rotation stop position P _BTDC at temperature T _W and the engine starting just before the start detected by the crank angle 26 of the engine 14. Therefore, when the engine is started by direct-injection self-ignition in the direct injection type engine, the optimum engine start torque T _{S that} is sufficient for completing the engine start within a predetermined time is obtained as the engine cooling water temperature T _W. even if and as varied by the difference of the engine rotation stop position P _BTDC, it is possible to set an optimum engine starting torque T _S in consideration of the variation.

Further, according to the electronic control device 58 of the present embodiment, the clutch (clutch device) 28 is provided between the engine 14 and the electric motor 12, and the engine 14 is transmitted from the electric motor 12 via the clutch 28. since the starting torque T _S is caused to start being rotated, at the time of starting the engine, in addition to the torque obtained from the explosion energy by ignition, rotation of the engine 14 by the engine starting torque T _S obtained from the engaging energy of the clutch 28 It can be driven.

  As mentioned above, although one Example of this invention was described in detail with reference to drawings, this invention is not limited to this Example, It can implement in another aspect.

  For example, in the above-described embodiment, the present invention is applied to the hybrid vehicle 10. However, the present invention is not limited to this. For example, an engine as a vehicle driving force source and a well-known starter motor that starts the engine The present invention can be applied even to a vehicle equipped with a vehicle.

  Further, the engine 14 is preferably ignited by injecting fuel at an appropriate injection amount required at the time of starting when predetermined pistons in a plurality of cylinders reach top dead center from various engine starting start positions. It consists of in-cylinder gasoline engines and diesel engines that can be used.

In the above-described embodiment, the engine start torque T _S is determined to be the engine rotation stop position P _BTDC [° from the relationship obtained in advance so that the engine start torque T _S becomes the minimum necessary value for engine start. ] and was adapted to be calculated based on the cooling water temperature T _W of the engine 14, but need not necessarily be calculated based on the coolant temperature T _W. For example, the engine start torque T _S may be calculated based on the engine rotation stop position P _BTDC [°].

  It should be noted that the above description is merely an embodiment, and other examples are not illustrated. However, the present invention is implemented in variously modified and improved modes based on the knowledge of those skilled in the art without departing from the gist of the present invention. Can do.

10: Hybrid vehicle (vehicle)
12: Electric motor 14: Engine (cylinder injection type engine)
58: Electronic control device (vehicle engine start control device)
A: Motor running operation area ACR: Crank angle N _MG : Motor rotation speed P _BTDC : Engine rotation stop position T _S : Engine start torque T _W : Engine coolant temperature

Claims (4)

A vehicle engine start control device for use in a vehicle comprising an electric motor and an engine started by the electric motor, the vehicle being driven by at least one of the engine and the electric motor,
An engine start torque output from the electric motor when starting the engine while the electric motor is running only by the electric motor is calculated based on the rotation stop position of the engine immediately before starting the engine,
An electric motor travel operation region in which an output torque range is determined according to the rotational speed of the electric motor is set so that the electric motor operates in a state where a surplus power corresponding to the engine starting torque is left during the electric motor traveling. A vehicle engine start control device.   2. The vehicle according to claim 1, wherein the engine start torque is calculated based on a pre-stored relationship based on a rotation stop position of the engine immediately before the start of the engine detected from a crank angle of the engine. Engine start control device. The engine is an in-cylinder injection engine,
The engine starting torque is calculated from a relationship stored in advance based on a cooling water temperature of the engine and an engine rotation stop position immediately before the start of the engine detected from a crank angle of the engine. The vehicle engine start control device according to claim 2. A clutch device is provided between the engine and the electric motor,
4. The vehicle engine start control device according to claim 1, wherein the engine is started by being rotationally driven by the engine start torque transmitted from the electric motor through the clutch device. 5.

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