JP2008201182A - Driving device of hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further improve the starting performance of a vehicle on a low μ road of a steep slope by enabling a first driving wheel and second driving wheel to rapidly generate a driving force at the start time of the vehicle. <P>SOLUTION: During start standby (S8 is YES), a forward/backward switching device 22 is put into a neutral state (S9), output control (S10) of an engine 12 is performed, the rotation speed NG of a power generator 48 is increased to a target rotation speed NGT, and the power capable of being generated by the power generator 48 is increased. Therefore, a predetermined power can be immediately generated by power generation control of the generator 48 by the power generation controlling means 114 at the start time of the vehicle, a predetermined driving wheel is rapidly generated in the rear wheel 32 by operation of a motor 68 by the generated power, and hence the vehicle can be started even on the low μ road or the like of the steep slope where the start only by a front wheel 30 is difficult. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drive device for a hybrid vehicle that rotationally drives a first drive wheel by an engine and rotates a second drive wheel by operating an electric motor with electric power obtained by a generator that is rotationally driven by the engine. In particular, the present invention relates to an improvement in driving force control when starting using both the first driving wheel and the second driving wheel.

(a) an engine that rotationally drives the first drive wheel; (b) a generator that generates electric power when mechanically driven by the engine; and (c) an electric power generated by the generator. An electric motor that generates a power running torque by being supplied and rotationally drives a second driving wheel different from the first driving wheel; and (d) rotationally drives both the first driving wheel and the second driving wheel. When starting a vehicle, there is provided a hybrid vehicle drive device having start-time power generation control means for performing power generation control of the generator so as to generate electric power necessary to operate the electric motor with a predetermined power running torque. Are known. The apparatus described in Patent Document 1 is an example thereof, and by increasing and correcting the engine rotation speed so that the generator is driven to rotate at a rotation speed that can generate electric power necessary for starting the vehicle by the generator, The second drive wheel can be driven to rotate by operating the electric motor with a large power running torque, and the start performance on a steep low μ road or the like is improved together with the first drive wheel.
JP 2005-161933 A

  However, in the above-mentioned Patent Document 1, the accelerator speed is increased and corrected after the accelerator is turned on (depressing the pedal), and the vehicle is stopped by the brake device until the engine speed increases. There is a problem that a delay time is generated from when the engine is turned on until the engine speed actually increases and the vehicle starts.

  The present invention has been made in the background of the above circumstances, and the object of the present invention is to enable both the first drive wheel and the second drive wheel to be rapidly rotated at the start of the vehicle so that the steep slope is reduced. The purpose is to further improve the starting performance of the vehicle on the road.

  In order to achieve such an object, the present invention includes (a) an engine that rotationally drives the first drive wheel via an intermittent device capable of transmitting and interrupting power, and (b) mechanically driven by the engine. And (c) a power running torque is generated by supplying the power generated by the generator, and a second driving wheel different from the first driving wheel is driven to rotate. And (d) generating electric power necessary to operate the electric motor with a predetermined power running torque when both the first driving wheel and the second driving wheel are rotationally driven to start the vehicle. And a power generation control means at the time of starting to perform power generation control of the generator, (e) while the vehicle is stopped when the brake is braked, the intermittent device is in a disconnected state, To the engine Ri, characterized in that a generator rotation increasing means during stopping of increasing an amount of power that can be generated by increasing the rotational speed of the generator.

  According to a second aspect of the invention, in the hybrid vehicle drive device of the first aspect, the generator rotation increasing means during stopping increases the rotational speed of the generator greatly as the road surface gradient increases according to the road surface gradient. And

  In such a hybrid vehicle drive device, in order to increase the electric power that can be generated by turning off the intermittent device and increasing the rotational speed of the generator by the engine while the vehicle is being braked and stopped. When the vehicle is started after the brake is released, it is possible to immediately generate a predetermined power by controlling the power generation by the power generation control means at the time of starting, and the electric motor is operated by the generated power to drive the second drive. A predetermined driving force can be quickly generated in the wheel. In addition, by connecting the intermittent device in conjunction with the brake release operation, the engine can quickly generate a predetermined driving force on the first drive wheel. Consequently, the brake release operation or the accelerator ON operation ( It is possible to quickly generate the driving force of both the first driving wheel and the second driving wheel in accordance with the output request operation), and the vehicle can be used even on a steep low μ road that is difficult to start with only the first driving wheel. Can be started immediately.

  In the second invention, since the generator rotation speed is greatly increased as the road surface gradient is larger, the electric power that can be generated by the generator is increased, and a large driving force can be generated in the second driving wheel by the electric motor when the vehicle starts. Thus, the starting performance of the vehicle on the uphill road is further improved. That is, if the driving force of the second driving wheel is insufficient, a large load is applied to the first driving wheel, which may cause the first driving wheel to slip and become unable to start, or the vehicle may slide down. By increasing the driving force of the two driving wheels in accordance with the road surface gradient, it is possible to prevent such start failure and sliding down.

  The first driving wheel and the second driving wheel are both provided with a pair of left and right wheels, for example, one and the other of the front and rear wheels in a four-wheel drive vehicle, for example, the first driving wheel is the front wheel. The second drive wheel is the rear wheel, but it may be reversed. The intermittent device interposed between the engine and the first drive wheel is an automatic transmission or a forward / reverse switching device that can establish a neutral for interrupting power transmission. The engine is an internal combustion engine such as a gasoline engine or a diesel engine that generates power by burning fuel.

  The generator driven to rotate by the engine only needs to have at least a power generation function, and an alternator or the like is preferably used. However, a motor generator or the like capable of powering can be used as necessary. This generator can generate larger electric power as the rotational speed becomes higher, and can control generated electric power by controlling field current, for example. The generator may be directly connected to the engine and rotated integrally with the engine. Alternatively, the generator may be rotated by the engine via a transmission device such as a pulley or a gear. Even if it is the same, it may be designed to be rotated at a reduced speed or increased speed.

  The electric motor that rotationally drives the second drive wheel only needs to have at least a power running function, and a motor generator that can generate electric power can be adopted as necessary.

  The power generation control means at the start is configured to perform power generation control of the generator so as to generate electric power necessary to operate the electric motor with a predetermined power running torque determined according to the accelerator operation amount, for example. The power generation control may be performed so that the electric motor can be operated with a predetermined power running torque (corresponding to a creep torque) even during non-operation. It is also possible to perform power generation control so that the electric motor can be operated with a predetermined power running torque determined using the accelerator operation amount and the road surface gradient as parameters. For example, the power generation control is performed only when the road surface gradient is a predetermined value or more. On a flat road with a small road gradient, the vehicle may be started with only the first drive wheels without performing power generation control.

  The power generation control means at the time of starting is, for example, a vehicle in which the brake is turned off (release operation) or the accelerator is turned on without performing power generation control while the vehicle is stopped while the brake is turned on (braking operation). It is comprised so that electric power generation control may be performed at the time of start. When starting the vehicle to perform power generation control, not only when the brake is completely released, but also when the brake force or the operation force is reduced to a predetermined value or less, the brake OFF operation includes such a mode. Further, the power generation control can be performed both at the time of forward start and at the time of reverse start. However, only one of them may be executed, for example, only at the time of forward start.

  While the vehicle is stopped when the generator rotation increasing means is stopped by the engine to increase the rotation speed of the generator while the vehicle is stopped, the normal brake is turned ON by, for example, a foot brake depressing operation. However, the parking brake may be turned on. Since the brake is operated as described above, there is no fear that the vehicle starts to move on a slope or the like even when the interrupting device is in a shut-off state.

  Further, it is not necessary to constantly increase the generator rotational speed while the vehicle is stopped while the brake is being operated. When the shift lever is operated to a vehicle travel position such as the D position, The engine speed may be increased only when the driver is expected to turn off the brake or start the vehicle, such as when the power (hydraulic pressure, etc.) starts to decrease. Execution permission conditions can also be set.

  Further, when the power generation control means at the time of starting performs power generation control only when the road surface gradient is not less than a predetermined value and does not perform power generation control on a flat road with a small road surface gradient, It is not necessary to increase the rotational speed, and it is sufficient to execute it only when the road surface gradient is a predetermined value or more. When the power generation control means at the time of starting performs power generation control according to the road surface gradient, the road surface gradient is below a predetermined value, the power generated by the generator is small, and it is not necessary to increase the generator rotation speed. Increase control of the generator rotation speed by the generator rotation increasing means is not necessary. In addition, when the power generation control means at the start performs power generation control only at the time of forward start, in other words, only when there is a possibility of starting forward, for example, when the shift lever is operated to the operation position for forward travel. For example, the rotation increase control may be performed only when there is a possibility that the power generation control by the starting power generation control means is performed.

  In the second aspect of the invention, the generator rotational speed is greatly increased as the road surface gradient increases according to the road surface gradient. However, when the first invention is implemented, the engine rotational speed is not related to the road surface gradient, for example. May be set to a predetermined constant rotational speed higher than the idle rotational speed, and the generator rotational speed may be increased by a certain amount.

  In the second invention, for example, the generator rotational speed, that is, the engine rotational speed is increased stepwise or continuously in accordance with the road gradient. In this case, even when the starting power generation control means is in the accelerator OFF state, a predetermined power running torque (corresponding to creep torque) determined according to the road surface gradient is set so that the vehicle does not slide down regardless of the road surface gradient. In the case of performing power generation control so that the electric motor can be operated, the generator rotation increasing means during stopping can generate electric power necessary to operate the electric motor with the power running torque. It is desirable to set the increase amount of the rotation speed, and it may be larger than that. Considering the vehicle weight including the number of passengers and the loaded weight in addition to the road surface gradient, it is also possible to perform power generation control at start-up and generator rotation increase control during stopping so that the vehicle does not slide down, for example. is there.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a drive device 6 for a hybrid vehicle to which the present invention is applied. The driving device 6 includes a front wheel driving device 10 for driving the left and right front wheels 30L and 30R (hereinafter, simply referred to as the front wheel 30 when left and right are not distinguished), and the left and right front wheels 30L and 30R. A rear wheel drive device 8 for driving the rear wheels 32L and 32R (hereinafter simply referred to as the rear wheel 32 when left and right are not distinguished) and an electronic control device 70 for controlling these drive devices are provided. In this embodiment, the front wheels 30L and 30R are first drive wheels, and the rear wheels 32L and 32R are second drive wheels.

  The rear wheel drive device 8 is provided with an electric motor 68 that receives power supply and generates a power running torque. The output of the electric motor 68 is transmitted to the differential gear device 46 via the speed reducer 38 and the clutch 44. The left and right rear wheels 32L and 32R are distributed. For example, a DC motor is used as the electric motor 68. When electric power generated by a generator 48, which will be described later, is supplied, a power running torque is generated by the electric power. The clutch 44 is disposed between the speed reducer 38 and the differential gear device 46, and the power between the speed reducer 38 and the differential gear device 46 is achieved by engaging or releasing the clutch 44. Is switched between the transmission state and the cutoff state. For example, when the electric motor 68 is not operated, that is, when the vehicle is driven only by the front wheels 30, the power transmission is cut off, and the electric motor 68 is dragged by rotating the rear wheel 32. When the motor is rotated and fuel consumption is deteriorated or the electric motor 68 is a DC motor, the durability of the electric motor 68 is improved by preventing wear of components such as a commutator.

  Also, each wheel 30L, 30R, 32L, 32R is provided with a wheel speed sensor 52L, 52R, 54L, 54R, respectively, and the electronic controller 70 is informed about the rotational speed of each wheel 30L, 30R, 32L, 32R. Supply. Each wheel 30L, 30R, 32L, 32R is provided with a brake 40R, 40L, 42R, 42L, respectively, and is operated so as to reduce the rotational speed of each wheel according to an instruction from the electronic control unit 70. It is done.

  FIG. 2 is a skeleton diagram of the front wheel drive device 10. This front-wheel drive device 10 is of a horizontal type and is suitably used for an FF (front engine / front drive) type vehicle, and includes an engine 12 as a driving force source for traveling. The output of the engine 12 composed of an internal combustion engine such as a gasoline engine is supplied from a torque converter 14 as a fluid power transmission device, a forward / reverse switching device 22, a belt-type continuously variable transmission (CVT) 16, a reduction gear. 36 to the differential gear device 50 and distributed to the left and right main drive wheels (front wheels) 30L, 30R. On the other hand, the output of the engine 12 is also transmitted to a generator 48 mechanically connected to the crankshaft of the engine 12 via a pulley and a transmission belt, and the generator 48 is rotated by the output of the engine 12. It is designed to be driven. The generator 48 is an alternator or the like.

  The torque converter 14 includes a pump impeller 14p connected to a crankshaft of the engine 12 and a turbine impeller 14t connected to a forward / reverse switching device 22 via a turbine shaft 28, and transmits power via a fluid. Is supposed to do. Further, a lockup clutch 18 is provided between the pump impeller 14p and the turbine impeller 14t, and the lockup control device 88 (see FIG. 3) controls the engagement side oil chamber and the release side oil chamber. The hydraulic pressure supply is switched to be engaged or released, and the pump impeller 14p and the turbine impeller 14t are integrally rotated by being completely engaged. The pump impeller 14p includes a mechanical oil pump 56 that generates hydraulic pressure for controlling the speed of the continuously variable transmission 16, generating belt clamping pressure, or supplying lubricating oil to each part. Is provided.

  The forward / reverse switching device 22 is configured by a double pinion type planetary gear device, the turbine shaft 28 of the torque converter 14 is connected to the sun gear 22s, and the input shaft 58 of the continuously variable transmission 16 is connected to the carrier 22c. ing. When the forward clutch 24 disposed between the carrier 22c and the sun gear 22s is engaged, the forward / reverse switching device 22 is rotated integrally, and the turbine shaft 28 is directly connected to the input shaft 58, and the forward direction. The forward drive state in which the driving force is transmitted to the front wheels 30 is set. When the reverse brake 26 disposed between the ring gear 22r and the housing is engaged and the forward clutch 24 is released, the input shaft 58 is rotated reversely with respect to the turbine shaft 28, and the reverse direction is reached. The reverse drive state in which the drive force is transmitted to the front wheels 30 is set. Further, when both the forward clutch 24 and the reverse brake 26 are released, a neutral state where power transmission is interrupted is obtained. In this embodiment, the forward / reverse switching device 22 functions as an intermittent device.

  The continuously variable transmission 16 includes an input-side variable pulley 60 having a variable effective diameter provided on the input shaft 28, an output-side variable pulley 64 having a variable effective diameter provided on the output shaft 66, and variable pulleys thereof. A transmission belt 62 wound around 60 and 64 is provided, and power is transmitted through a frictional force between the variable pulleys 60 and 64 and the transmission belt 62. Each of the variable pulleys 60 and 64 has a variable V-groove width and is provided with a hydraulic cylinder. The hydraulic pressure of the hydraulic cylinder of the input-side variable pulley 60 is controlled by a transmission control device 86 (see FIG. 3). The V groove width of both variable pulleys 60 and 64 is changed to change the engagement diameter (effective diameter) of the transmission belt 62, and the gear ratio γ (= input shaft rotational speed NIN / output shaft rotational speed NOUT) is continuously increased. Can be changed.

  Further, the hydraulic pressure of the hydraulic cylinder of the output side variable pulley 64 is regulated by a clamping pressure control device 87 (see FIG. 3) so that the transmission belt 62 does not slip. The clamping pressure control device 87 includes a solenoid valve that is duty-controlled by the electronic control device 70, and the hydraulic pressure of the hydraulic cylinder of the output-side variable pulley 64 is continuously controlled by the solenoid valve. The belt clamping pressure, that is, the frictional force between the variable pulleys 60 and 64 and the transmission belt 62 is increased or decreased.

FIG. 3 is a block diagram for explaining a control system provided in the vehicle for controlling the engine 12 and the continuously variable transmission 16 shown in FIGS. 1 and 2, and the electronic controller 70 includes the wheel speed sensor. In addition to 52L, 52R, 54L, and 54R, an engine speed sensor 72, a turbine speed sensor 73, a throttle sensor 74 with an idle switch, a coolant temperature sensor 76, a CVT oil temperature sensor 77, an accelerator operation amount sensor 78, and a foot brake switch 79 , A lever position sensor 80, a front / rear G sensor 71, a four-wheel drive switch 82, a snow mode switch 83, etc. are connected, and the rotational speed (wheel speed) of each wheel 30L, 30R, 32L, 32R, the rotational speed of the engine 12 (engine Rotational speed) NE, turbine shaft 28 rotational speed (turbine rotational speed) NT, electronic throttle 20 fully closed state (idle state) and its opening (throttle valve opening) (see FIG. 1) theta _TH, the engine 12 coolant temperature T _W, a hydraulic circuit, such as the continuously variable transmission 16 oil temperature T _CVT, Operation amount (accelerator operation amount) Acc of an accelerator operation member such as an accelerator pedal, presence / absence of operation of a foot brake which is a service brake, lever position (operation position) P _{SH of} the shift lever 81, vehicle front and rear G (acceleration), 4 Signals indicating the selection of a four-wheel drive mode for traveling by wheel drive, the selection of a snow mode for shifting according to a shift condition (such as a shift map) suitable for driving on a low μ road such as a snowy road, etc. are supplied. Yes.

  A vehicle speed (body speed) V can be calculated based on signals from the wheel speed sensors 52L, 52R, 54L, 54R, and the vehicle speed V is determined based on the rotational speed (output of the output shaft 66 of the continuously variable transmission 16). Corresponding to shaft rotation speed NOUT. The turbine rotational speed NT coincides with the rotational speed (input shaft rotational speed) NIN of the input shaft 58 during forward traveling with the forward clutch 24 engaged. The accelerator operation amount Acc represents the driver's requested output amount. The front-rear G sensor 71 detects the front-rear G (acceleration) of the vehicle, but can determine the road surface gradient Φ from the front-rear G and the vehicle speed V, and also functions as a gradient sensor. The four-wheel drive switch 82 and the snow mode switch 83 are provided, for example, around the shift lever 81, an instrument panel, and the like, and are switched by the driver according to the driver's preference and driving conditions.

  The electronic control unit 70 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM, and signals according to a program stored in the ROM in advance. By performing the processing, output control of the engine 12, shift control of the continuously variable transmission 16, belt clamping pressure control, power generation control of the motor 48, and the like are executed. It is configured separately for control purposes. FIG. 4 is a block diagram for explaining a control function executed by signal processing of the electronic control unit 70, and functionally includes an engine control means 110, a shift control means 112, and a power generation control means 114.

The engine control means 110 controls the output of the engine 12, and controls the fuel injection device 84 (see FIG. 3) for controlling the fuel injection amount in addition to controlling the opening and closing of the electronic throttle valve 20, thereby controlling the ignition timing. Therefore, the ignition device 85 such as an igniter is controlled. Control of the electronic throttle valve 20 is basically defined as parameters the accelerator operation amount Acc as shown in FIG. 5, it controls the throttle valve opening theta _TH greater the accelerator operation amount Acc increases increases. The fuel injection amount and the like are controlled in conjunction with the throttle valve opening _θTH .

  The speed change control means 112 performs speed change control of the belt-type continuously variable transmission 16 and belt clamping pressure control, and also performs neutral control in which the forward / reverse switching device 22 is electrically neutral. As shown in FIG. 6, the target rotational speed NINT on the input side is calculated from a predetermined shift map using the accelerator operation amount Acc representing the driver's required output amount and the vehicle speed V as parameters, and the actual input shaft rotational speed NIN is calculated. Shift control of the continuously variable transmission 16 is performed in accordance with such deviation so as to coincide with the target rotational speed NINT. That is, the supply and discharge of hydraulic fluid to and from the hydraulic cylinder of the input side variable pulley 60 is controlled by feedback controlling the solenoid valve of the speed change control device 86. The shift map in FIG. 6 corresponds to a shift condition, and a target rotational speed NINT that sets a larger speed ratio γ as the vehicle speed V is smaller and the accelerator operation amount Acc is larger is set. Further, since the vehicle speed V corresponds to the output shaft rotational speed NOUT, the target rotational speed NINT, which is the target value of the input shaft rotational speed NIN, corresponds to the target speed ratio, and the minimum speed ratio γmin of the continuously variable transmission 16 and the maximum speed change. It is determined within the range of the ratio γmax. The shift map is stored in advance in the storage device 98 (see FIG. 3).

  In the belt clamping pressure control, for example, as shown in FIG. 7, the required hydraulic pressure (corresponding to the belt clamping pressure) determined in advance so that belt slip does not occur with the accelerator operation amount Acc corresponding to the transmission torque and the gear ratio γ as parameters. The clamping pressure of the continuously variable transmission 16 is controlled according to the map. That is, the hydraulic pressure of the hydraulic cylinder of the output-side variable pulley 64 corresponding to the belt clamping pressure of the continuously variable transmission 16 is controlled by controlling the duty ratio of the exciting current for the solenoid valve of the clamping pressure control device 87. To do. The necessary oil pressure map of FIG. 7 is stored in advance in the storage device 98 in the same manner as the shift map.

  In the neutral control, both the forward clutch 24 and the reverse brake 26 of the forward / reverse switching device 22 are electrically released. These clutches 24 and brakes 26 are switched between engaged and disengaged states by, for example, a hydraulic circuit mechanically switched by a manual valve connected to a shift lever 81, and the forward drive such as “D” is performed. The forward clutch 24 is engaged when it is operated to the reverse position, and the reverse brake 26 is engaged when it is operated to the reverse travel position such as “R”. When the parking position such as “N” or the neutral position is operated, the clutch 24 and the brake 26 are both released. On the other hand, a solenoid valve or the like for switching the hydraulic circuit is provided so that the hydraulic pressure is forcibly drained. In the neutral control, the clutch 24 and the brake 26 are released together by switching the hydraulic circuit by the solenoid valve. .

  The power generation control means 114 controls the power generation of the generator 48 when the four-wheel drive switch 82 is turned ON and the four-wheel drive mode is selected and at the time of starting, and the motor 68 generates a power running torque with the generated power. Can be generated. That is, the generator 48 has a power generation characteristic as shown in FIG. 8A, for example, and can generate larger electric power (corresponding to voltage × current) as the rotational speed NG of the generator 48 increases. The electric motor 68 has output characteristics as shown in FIG. 8B, for example, and can generate a larger output (corresponding to torque × rotational speed) as the electric power supplied from the generator 48 increases. The solid line, the alternate long and short dash line, and the broken line graph in FIG. 8 (a) are isoelectric lines with the same generated power, and the solid line, the alternate long and short dash line in FIG. 8 (b) are equal output lines with the same output. The solid lines, the alternate long and short dash lines, and the broken lines correspond to each other, and the motor 68 can be operated with a larger output as the generator rotational speed NG increases. Further, the solid line, the alternate long and short dash line, and the broken line in FIG. 8 (a) are cases where the power generation control is performed with the maximum generated power determined according to the rotational speed NG, that is, the field current being 100%. Accordingly, the generated power can be reduced. If the field current = 0%, the generated power becomes zero. Therefore, when the field current = 100% and the solid line power generation characteristic is obtained, power generation can be performed with the one-dot chain line or broken line characteristic by reducing the field current.

  In the four-wheel drive mode, for example, the load distribution ratio between the front wheels 30 and the rear wheels 32 that bear the load of the vehicle body is obtained based on the front and rear G detected by the front and rear G sensor 71, and the load distribution ratio, The driving force distribution ratio of the front and rear wheels is determined based on the driver's requested driving torque, vehicle speed V, vehicle acceleration, and the like, which are obtained using the accelerator operation amount Acc and the vehicle speed V as parameters, and the motor 68 depends on the driving force distribution ratio. The power generation control of the generator 48, that is, the field current is controlled according to the generator rotational speed NG so that a predetermined power running torque can be generated.

  Further, when the vehicle starts from the vehicle speed V = 0, the power generation control is performed in accordance with, for example, the flowchart of FIG. 9 so that the vehicle starts in the four-wheel drive state including the case of the four-wheel drive mode. The time when the vehicle starts is, for example, a period from when the vehicle speed V = 0 to about 5 to 10 km / hour. In step R1 in FIG. 9, it is determined whether or not the vehicle is starting, for example, whether or not the foot brake is changed from ON to OFF at the vehicle speed V = 0, or the foot brake stepping force or brake force (brake hydraulic pressure, etc.). Judgment is made based on whether or not the vehicle has fallen to a predetermined value or less, and if it is determined that the vehicle is starting, step R2 and subsequent steps are executed. In step R2, the road gradient Φ is calculated based on the longitudinal G detected by the longitudinal G sensor 71, and in step R3, the road gradient Φ and the accelerator operation amount Acc are used as parameters according to a predetermined map, arithmetic expression, or the like. Then, the necessary motor torque, that is, the power running torque necessary for starting by rotating the rear wheel 32 by the electric motor 68 is calculated. This necessary motor torque map and calculation formula show that the rear wheel 32 has a large shared load so that the rear wheel driving force can be obtained with an appropriate driving force distribution ratio of the front and rear wheels even on a low μ road such as a snowy road. It is determined so as to increase as the road surface gradient Φ increases, and is stored in the storage device 98 in advance. In addition, even when the accelerator operation amount Acc = 0, the rear wheel driving force (corresponding to the creep torque) is set so that the vehicle will not slide down, and the vehicle weight including the number of passengers and the loaded weight is determined. It can also be set in consideration. Further, in this embodiment, a predetermined necessary motor torque is set so that the vehicle starts in a four-wheel drive state even on a flat road with a small road surface gradient Φ.

  In the next step R4, the required power required to operate the electric motor 68 with the required motor torque is calculated from a predetermined map, arithmetic expression, or the like. The map and calculation formula for obtaining the required power are determined based on the output characteristics of the electric motor 68 shown in FIG. 8B, for example, and stored in the storage device 98 in advance. In step R5, the generator 48 is controlled to generate the necessary power. That is, since the power generated by the generator 48 varies depending on the rotational speed NG as shown in FIG. 8A, the field current is controlled so that the necessary power is obtained according to the rotational speed NG. Of the power generation control by the power generation control means 114, the part that performs power generation control at the time of vehicle start according to the flowchart of FIG. 9 corresponds to the power generation control means at start.

  Then, the electric power of the electric motor 68 is controlled by the electric power generated by the electric generator 48 by the electric power generation control at the time of starting, and the motor 68 is operated with the necessary motor torque in the step R3, so that an appropriate value is obtained according to the road surface gradient Φ. The rear wheel driving force can be generated with the driving force distribution ratio of the front and rear wheels, and the driving force is generated on the front and rear wheels even on low μ roads with a large road gradient Φ, etc. Excellent starting performance can be obtained in accordance with the accelerator operation amount Acc.

  Here, on the uphill road where the road surface gradient Φ is large, the shared load of the rear wheel 32 increases, and accordingly, the necessary motor torque and the necessary power of the electric motor 68 are increased, which is apparent from the power generation characteristics of FIG. Thus, unless the rotational speed NG of the generator 48 is increased, the required power cannot be obtained even if the field current for power generation is set to 100%. That is, if the engine rotational speed NE remains at the idle rotational speed while the vehicle is stopped, the rotational speed NG of the generator 48 is slow, so that the electric power is not increased until the engine rotational speed NE increases with the accelerator ON operation. Insufficient rear wheel driving force may not be obtained due to a shortage, and there is a risk that a large load is applied to the front wheel 30 and the vehicle slips or the vehicle slides down.

  On the other hand, the electronic control unit 70 of the present embodiment further includes a generator rotation increasing means 120 during stoppage, and the rotation speed NG of the generator 48 is set in advance according to the road surface gradient Φ while the vehicle is stopped. By increasing the electric power, it is possible to quickly generate large electric power by the electric power generation control by the electric power generation control means 114 when the vehicle starts, and a predetermined rear wheel driving force can be obtained from the beginning.

FIG. 10 is a flowchart for specifically explaining the processing contents of the stopped generator rotation increasing means 120. In step S1, the road surface gradient Φ is calculated in the same manner as in step R2, and in step S2, as in step R3. Thus, the required motor torque is calculated, and in step S3, the required power is calculated in the same manner as in step R4. In this case, the power generation control by the power generation control means 114 is not performed while the vehicle is in the brake-on state where the foot brake is depressed, but here the accelerator operation amount θ Calculate the required power based on the required motor torque when _TH = 0.

  In step S4, the target rotational speed NGT of the generator 48 necessary for generating the necessary power is calculated from a predetermined map, arithmetic expression, or the like. Based on the power generation characteristics shown in FIG. 8 (a), for example, the required power can be obtained when the power generation control is performed with the field current set to 100% based on the power generation characteristics shown in FIG. And is stored in the storage device 98 in advance.

In step S5, a target engine rotation speed NET for rotating the generator 48 at the target rotation speed NGT is calculated using the transmission gear ratio between them, and the engine 12 is operated at the target engine rotation speed NET. To calculate the target engine torque, specifically, the target throttle valve opening θ _TH T. This target throttle valve opening θ _TH T is, for example, a feedback control that increases or decreases in accordance with a deviation such that the engine rotational speed NE becomes the target rotational speed NET, and whether the forward / reverse switching device 22 is in the neutral state. It can be calculated by feedforward control obtained according to a predetermined arithmetic expression using the engine load as a parameter, such as whether or not the generator 48 is under power generation control, and the feedforward control and the feedback control are used in combination. Can also be requested. The target engine rotational speed NET is guarded with an idle rotational speed as a lower limit, and is limited to an idle rotational speed or higher, and the target throttle valve opening θ _TH T is controlled according to the map of FIG. A guard whose lower limit is the throttle valve opening degree θ _TH set according to the amount Acc is applied, and is limited to the throttle valve opening degree θ _TH or more.

  In the next step S6, it is determined whether or not the operation position of the shift lever 81 is “N” for blocking. If “N”, there is no intention to start yet, and the process ends. If it is not “N”, step S7 is executed to determine whether or not the operation position of the shift lever 81 is “D” for forward travel. If it is not “D”, that is, “R” for reverse travel or parking In the case of “P”, the process ends as it is, and only in the case of “D”, step S8 and subsequent steps are executed. These steps S6 and S7 may be executed before step S1. If there are other operation positions for forward traveling that perform shift control within a predetermined shift range in which the lower limit (high speed side) of the gear ratio γ is limited, the operation position is operated to those operation positions. Even in the case where it is, it is determined that step S8 and subsequent steps are executed.

  In step S8, it is determined whether or not the vehicle is waiting to start based on, for example, whether or not the vehicle speed is V = 0 and the brake is depressed so that the foot brake is depressed. If the vehicle is on standby, neutral control is executed in step S9. . The neutral control in step S9 is to forcibly set the forward / reverse switching device 22 to the neutral state (blocking state). Specifically, by outputting a neutral command to the shift control means 112, the shift control means 112 is provided. Thus, the hydraulic circuit is switched, and the forward clutch 24 in the engaged state is released. As a result, power transmission from the engine 12 to the front wheels 30 is interrupted, but since the foot brake is in an ON state, there is no fear that the vehicle will slide down due to gravity on the uphill.

In the next step S10, a command for setting the throttle valve opening θ _TH of the engine 12 to the target throttle valve opening θ _TH T obtained in step S5 is output to the engine control means 110. As a result, the throttle valve opening θ _TH is set to the target throttle valve opening θ _TH T by the engine control means 110, and the fuel injection amount and the like are controlled in conjunction with the throttle valve opening θ _TH. Is increased to the target engine rotational speed NET, and the rotational speed NG of the generator 48 is set to the target rotational speed NGT accordingly.

On the other hand, if the determination in step S8 is NO (No), that is, if the foot brake stepping operation is released, step S11 and subsequent steps are executed. The determination in step S8 is preferably determined in the same manner as in step R1 for determining whether or not the vehicle is starting when performing power generation control at the time of starting. In step S11, by outputting a command to release the neutral control to the shift control means 112, the hydraulic control circuit is switched by the shift control means 112, the forward clutch 24 is engaged, and the forward drive state is established. Then, the driving force is transmitted from the engine 12 to the front wheels 30. In step S12, it is determined whether or not the vehicle is starting, that is, whether or not it is less than a predetermined vehicle speed (V = about 5 to 10 km / hour) at which power generation control is performed by the power generation control means 114, and exceeds the predetermined vehicle speed. However, the process is terminated as it is, but the step S10 is executed during the start of the vehicle below the predetermined vehicle speed, and the output control of the engine 12 is performed according to the target throttle valve opening θ _TH T.

  Here, when the determination in step S8 is NO, that is, when the vehicle is started when the foot brake is turned off (including the case where the operating force or the braking force is reduced to a predetermined value or less), the power generation control means 114 While the power generation control at the time of starting is performed, the electric motor 68 is controlled by the power generated by the power generation control to generate a predetermined driving force on the rear wheel, but the determination in step S8 is a start waiting for YES Since the rotational speed NG of the generator 48 is increased to the target rotational speed NGT that can generate the predetermined required power determined according to the road surface gradient Φ, the power generation control is performed with the release of the foot brake. As a result, the necessary power is promptly generated. As a result, even on an uphill road with a large road surface gradient Φ, necessary power can be obtained quickly as the power generation control starts, and the motor 68 is power-running controlled with the generated power. The rear wheel driving force is generated with the wheel driving force distribution ratio, and the generated power is insufficient due to insufficient rotation speed of the generator 48 at the beginning of power generation control, so that sufficient rear wheel driving force cannot be obtained. The front wheel 30 is prevented from slipping and the vehicle from sliding down.

  As described above, in the hybrid vehicle drive device 6 of the present embodiment, during the start-up waiting state in the brake-on state in which the brake pedal is depressed (YES in Step S8), the forward / reverse switching device 22 is set in Step S9. In addition to neutral, the engine output control is performed in step S10 to increase the rotational speed NG of the generator 48 mechanically driven by the engine 12 to the target rotational speed NGT, and the electric power that can be generated by the generator 48. Therefore, when the foot brake is turned off and the vehicle is started, predetermined power can be generated immediately by generating control of the generator 48 by the power generation control means 114 in step R5. Thus, the electric motor 68 can be operated to quickly generate a predetermined driving force on the rear wheel 32.Further, in step S11, the neutral control is terminated, and the forward clutch 24 of the forward / reverse switching device 22 is connected to enter the forward drive state, whereby the engine 12 promptly generates a predetermined driving force on the front wheels 30. As a result, when the vehicle starts with the brake pedal turned off, it is possible to quickly generate the driving force of both the front wheels 30 and the rear wheels 32, and the steep slope is difficult to start with only the front wheels 30. The vehicle can be started quickly even on μ roads.

  Further, in this embodiment, as the road surface gradient Φ increases, the rotational speed NG of the generator 48 is greatly increased, and the electric power that can be generated by the generator 48 is increased. It can be generated on the wheel 32, and the starting performance of the vehicle on the uphill road is further improved. That is, if the driving force of the rear wheel 32 is insufficient, a large load is applied to the front wheel 30, which may cause the front wheel 30 to slip and make it impossible to start, or the vehicle may slide down. Is increased in accordance with the road surface gradient Φ, so that it is not possible to start or slide down.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention is implemented in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

1 is a schematic configuration diagram of a drive device for a hybrid vehicle to which the present invention is applied. FIG. 2 is a skeleton diagram illustrating a front wheel drive device provided in the hybrid vehicle of FIG. 1. It is a block diagram explaining the control system with which the hybrid vehicle of FIG. 1 is equipped. It is a block diagram explaining the principal part of the control function with which the electronic control apparatus of FIG. 3 is provided. FIG. 5 is a diagram showing an example of a map used when the engine control means of FIG. 4 controls the throttle valve opening degree θ _TH according to the accelerator operation amount Acc. FIG. 5 is a diagram showing an example of a shift map used when the shift control means of FIG. 4 obtains a target rotational speed NINT by shift control. FIG. 5 is a diagram showing an example of a required hydraulic pressure map used when the shift control means of FIG. 4 obtains the required hydraulic pressure by controlling the belt clamping pressure. FIG. 5 is a diagram showing an example of the power generation characteristics of a generator that is controlled by the power generation control unit of FIG. 4 and the output characteristics of a motor that is powering controlled by the power generated by the generator. 5 is a flowchart for specifically explaining the processing contents of start-time power generation control executed by the power generation control means of FIG. 4. FIG. 5 is a flowchart for specifically explaining the processing contents of the stopped generator rotation increasing means of FIG. 4. FIG.

Explanation of symbols

  6: Drive device for hybrid vehicle 12: Engine 22: Forward / reverse switching device (intermittent device) 30L, 30R: Front wheel (first drive wheel) 32L, 32R: Rear wheel (second drive wheel) 48: Generator 68: Electric motor 70: Electronic control unit 71: Front / rear G sensor 114: Power generation control means (power generation control means at start) 120: Generator rotation increasing means during stopping

Claims (2)

An engine that rotationally drives the first drive wheel via an intermittent device capable of transmitting and interrupting power;
A generator that generates electric power by being mechanically driven by the engine;
An electric motor that generates a power running torque by being supplied with the electric power generated by the generator and rotationally drives a second drive wheel different from the first drive wheel;
When the vehicle is started by rotating both the first drive wheel and the second drive wheel, the power generation control of the generator is generated so as to generate electric power necessary to operate the electric motor with a predetermined power running torque. Power generation control means for starting,
In the drive device of the hybrid vehicle having
A stopping generator rotation increasing means for increasing the electric power that can be generated by increasing the rotation speed of the generator by the engine while the vehicle is stopped while the brake is being braked. A drive device for a hybrid vehicle characterized by being provided. The stopping power generator rotation increasing means increases the rotational speed of the power generator as the road surface gradient increases in accordance with the road surface gradient.

Images