JP2000240484A - Hybrid electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low fuel consumption vehicle to control operation of an engine and an M/G(an electric motor/generator) and improve fuel consumption without complicating a mechanism. SOLUTION: When this vehicle is in a discharge permission mode, an M/G 6 is operated as a motor and by reducing an engine load or stopping the engine, the coefficient of fuel consumption of the engine 1 is caused to make access to a best fuel consumption region or an engine 1 is stopped, and the best fuel consumption region is kept to obtain TOTAL target torque. Further, when it is in a charge demand mode, the M/G 6 is operated as a generator and by increasing an engine load, the coefficient of fuel consumption of the engine 1 is caused to make access to the best fuel consumption region, and with the fuel consumption region of the engine 1 kept at the best fuel consumption region, charge of a battery 14 is carried out and the TOTAL target torque is obtained, and fuel consumption is improved without complicating a mechanism to provide a low fuel consumption vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid electric vehicle equipped with an internal combustion engine capable of switching at least between a stoichiometric air-fuel ratio and a lean air-fuel ratio, and an electric motor which serves as a power source of the vehicle together with the internal combustion engine.

[0002]

2. Description of the Related Art In order to improve exhaust gas performance and fuel efficiency, various hybrid electric vehicles that obtain a driving force by an internal combustion engine (engine) and an electric motor (motor) have been developed. Hybrid electric vehicles include a type that generates driving power by using a motor and a power source for the motor using an engine, and a type that uses a motor and an engine to obtain driving force. 2. Description of the Related Art Techniques have been disclosed in the related art that have various operation modes in which an engine is driven when the vehicle is running or required, and in which the driving of the engine can be stopped even while the vehicle is running.

On the other hand, in order to reduce harmful exhaust gas components and improve fuel efficiency, instead of an intake pipe injection engine that injects fuel into an intake pipe, a multi-cylinder in-cylinder injection engine that directly injects fuel into a combustion chamber is used. Various (in-cylinder injection engines) have been proposed. The in-cylinder injection engine is configured to switch between an intake stroke injection mode in which fuel injection is mainly performed in an intake stroke and a compression stroke injection mode in which fuel injection is mainly performed in a compression stroke in accordance with an operation state. Lean combustion operation (lean operation) is possible as a lean air-fuel ratio depending on the state.

[0004] Also in a hybrid electric vehicle, an in-cylinder injection engine capable of performing a lean operation by switching at least between a lean air-fuel ratio and a theoretical (stoichiometric) air-fuel ratio is applied as an engine (for example, Japanese Patent Laid-Open No. 9-79063).
Reference). In hybrid electric vehicles to which the direct injection engine is applied, to improve drivability, etc.
Various control of the operating state has been devised.

[0005]

In recent years, there has been a growing demand for improved exhaust gas performance and improved fuel efficiency. Even in a hybrid electric vehicle to which a direct injection engine is applied, further improvement in fuel efficiency is required. Is desired. On the other hand, vehicle manufacturing costs and the like tend to be increasingly suppressed,
It is necessary to avoid complication of the mechanism, and at present, it is desired to improve fuel efficiency without complicating the mechanism.

The present invention has been made in view of the above circumstances, and an internal combustion engine capable of operating at least by switching the air-fuel ratio between lean and stoichiometric is applied, thereby improving the fuel efficiency without complicating the mechanism. It is an object of the present invention to provide a hybrid electric vehicle which can be used.

[0007]

According to the present invention, there is provided a power source for a vehicle together with an internal combustion engine capable of switching between a theoretical (stoichiometric) air-fuel ratio and a lean air-fuel ratio leaner than the stoichiometric air-fuel ratio. When the required load derived by the required load deriving means is not located in the best fuel consumption region of the lean air-fuel ratio or the stoichiometric air-fuel ratio of the internal combustion engine by the required load deriving means, the motor is adapted to respond to the output of the battery state detecting means. The operation of the internal combustion engine and the electric motor is controlled by the operation control means. At this time, if the output of the battery state detection means can be discharged, the motor is operated as a power source to reduce the load on the internal combustion engine so that the fuel efficiency of the internal combustion engine approaches the best fuel efficiency area or the internal combustion engine is activated. Stop. Further, when the output of the battery state detecting means is in the charging required state, the motor is operated as a generator to increase the load on the internal combustion engine so that the fuel efficiency of the internal combustion engine approaches the best fuel efficiency region.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, as an internal combustion engine (engine) capable of operating lean by switching the air-fuel ratio between at least lean and stoichiometric, the air-fuel ratio of the air-fuel mixture is controlled to be leaner than the stoichiometric air-fuel ratio, and the air-fuel ratio is set in the combustion chamber. Although a multi-cylinder in-cylinder injection engine in which fuel is directly injected is described as an example, a multi-cylinder in-cylinder engine can be operated at least by switching the air-fuel ratio between lean and stoichiometric. The present invention can be applied to other than the direct injection engine. Further, although a vehicle having a continuously variable transmission has been described as an example of an automatic transmission, the present invention can be applied to a vehicle having an automatic transmission other than the continuously variable transmission. .

FIG. 1 is a schematic configuration of a hybrid electric vehicle according to an embodiment of the present invention, FIG. 2 is a schematic configuration of a multi-cylinder in-cylinder injection engine, FIG. 4 to 7 show control maps for operating the engine and the electric motor, and FIG. 8 shows a flowchart for controlling the operation of the engine and the electric motor.

As shown in FIG. 1, an output shaft 2 of an in-cylinder injection engine (engine) 1 is connected to a continuously variable transmission (CVT) via a clutch 3 and a double pinion type planetary gear mechanism 4 for switching between forward and reverse. 5 input side. An electric motor / generator (M / G) 6 as an electric motor also serving as an engine start motor is connected to the input side of the CVT 5. The output side of the CVT 5 is connected to a differential 8 via a starting clutch 7, and the driving force is transmitted to driving wheels 9. It should be noted that reference numeral 41 in FIG.
Is a brake for stopping the ring gear of the planetary gear mechanism 4.

The output side of the CVT 5 is connected to a differential 8 via a starting clutch 7, and a driving force is transmitted to driving wheels 9. CV
T5 is configured such that a belt 13 is stretched over an input pulley 11 and an output pulley 12 whose groove widths can be changed, and by changing the groove widths of the input pulley 11 and the output pulley 12, a predetermined gear ratio is obtained. You can get it.

The battery 14 connected to the M / G 6 is provided with a charge detection sensor 15 as battery state detection means. The charge detection sensor 15 detects the charge of the battery 14 and detects the detected charge. Is input to an electronic control unit (ECU) 16. Information on the accelerator opening and the engine rotation speed Ne is input to the ECU 16, and the driving of the engine 1 and the control of the operating state of the M / G 6 are performed based on various information.

As shown in FIG. 2, a spark plug 23 is attached to a cylinder head 22 of the engine 1 for each cylinder, and an electromagnetic fuel injection valve 24 is attached to each cylinder. The injection port of the fuel injection valve 24 is opened in the combustion chamber 25, and the fuel injected from the fuel injection valve 24 is directly injected into the combustion chamber 25. A piston 27 is supported on the cylinder 26 of the engine 1 so as to be slidable in the vertical direction, and a cavity 28 that is depressed in a hemispherical shape is formed on the top surface of the piston 27. The cavity 28 generates a reverse tumble flow in the intake flow opposite to the normal tumble flow.

An intake port 29 and an exhaust port 30 facing the combustion chamber 25 are formed in the cylinder head 22. The intake port 29 is opened and closed by driving an intake valve 31, and the exhaust port 30 is opened and closed by driving an exhaust valve 32. . An intake pipe 34 is connected to the intake port 29, and a surge tank, an air cleaner, a throttle body, and the like (not shown) are connected to the intake pipe 34. On the other hand, an exhaust pipe 35 is connected to the exhaust port 30, and the exhaust pipe 35 is provided with a catalyst 16 and a muffler (not shown).

The ECU 16 includes an input / output device, a storage device for storing control programs and control maps, a central processing unit, and timers and counters. ECU1
6, comprehensive control of the hybrid electric vehicle including the engine 1 and the M / G 6 is performed. The detection information of the various sensors is input to the ECU 16, and the ECU 16 determines the fuel injection mode, the fuel injection amount, the ignition timing, and the like based on the detection information of the various sensors.
4 and the ignition plug 23 are controlled.

In the above-described hybrid vehicle, the on / off of the clutch 3 and the drive control of the engine 1 are
The M / G 6 alone transmits the driving force to the input side of the CVT 5 to drive the drive wheels 9 and, if necessary, the engine 1 to drive the M / G
There are various operation modes for driving the drive wheels 9 by transmitting the driving force to the input side of the CVT 5 by using the G 6 and the engine 1 together. That is, if the M / G 6 is operated with the motor in a state where the clutch 3 is turned off and the brake 41 is turned off, the motor runs in the motor alone mode. . When the clutch 3 is turned on and the brake 41 is turned off, the planetary gear mechanism 4 rotates integrally with the output shaft of the engine 1. If you operate the motor 6, you can use the engine / motor combined driving mode, M / G 6
When the power generation operation is performed, the driving mode becomes the combined use of the engine and the generator. The engine 1 is started by transmitting the motor output of the M / G 6 to the output shaft of the engine 1 in this state. In a state where the clutch 3 is turned off and the brake 41 is turned on, the carrier of the planetary gear mechanism 4 rotates in reverse with respect to the output shaft of the engine 1, so that the engine can be driven backward by the output of the engine.

In the case of traveling by the M / G 6 alone, the clutch 3
Is turned off and the input pulley 11 of CVT 5 is
To drive the drive wheels 9. When starting the engine 1, the clutch 3 is engaged, the output shaft of the M / G 6 is connected to the output shaft 2 of the engine 1, and the engine 1 is started.
Is rotated by the M / G 6, and the engine 1 is started by controlling ignition and fuel supply of the engine 1.

In the engine 1, the intake air flowing into the combustion chamber 25 from the intake port 29 forms a reverse tumble flow, and injects fuel after the middle stage of the compression stroke to utilize the reverse tumble flow to make a top portion of the combustion chamber 25. Spark plug 23 arranged at the center
, A small amount of fuel is collected only in the vicinity of, and an extremely lean air-fuel ratio state is formed in a portion separated from the ignition plug. By setting the stoichiometric air-fuel ratio or the rich air-fuel ratio only in the vicinity of the ignition plug 23, fuel consumption is suppressed while achieving stable stratified combustion (stratified super-lean combustion).

When a high output is obtained from the engine, the fuel from the injector 28 is injected into the intake stroke to homogenize the entire combustion chamber 25, and the inside of the combustion chamber 25 is adjusted to a stoichiometric air-fuel ratio or a lean air-fuel ratio. Premix combustion is performed with the mixture being in a mixed state. Of course, a higher output can be obtained by the stoichiometric air-fuel ratio or the rich air-fuel ratio than by the lean air-fuel ratio. In this case, too, the fuel injection is performed at a timing such that the fuel is sufficiently atomized and vaporized. High output is obtained efficiently.

The ECU 23 determines the fuel injection mode by searching the current fuel injection area from a fuel injection map (not shown) based on the operating load Pe and the engine speed Ne according to the opening of the throttle valve. I do. For example, when both the load Pe and the engine rotation speed Ne are small, the fuel injection mode is set to the compression stroke injection mode, and the fuel is injected in the compression stroke.On the other hand, when the load Pe increases or the engine rotation speed Ne increases, the fuel is injected. The injection mode is an intake stroke injection mode, in which fuel is injected in the intake stroke. Then, a target air-fuel ratio in each fuel injection mode is set, an appropriate amount of fuel injection is determined based on the target air-fuel ratio, and the drive of the fuel injection valve 24 is controlled in accordance with the amount of fuel injection.
The drive of the ignition plug 23 is controlled.

In the hybrid electric vehicle having the above configuration,
Engine 1 and M / G 6 are the power sources. As shown in FIG. 3, the ECU 16 sends a request load (TOT) to the power source.
(AL target torque), accelerator opening and engine speed Ne
And a TOTAL target torque deriving means 51 as required load deriving means for deriving based on the target torque. That is, the TOTAL target torque deriving means 51 stores the TOTAL target torque based on the accelerator opening and the engine speed Ne as a map F1 shown in FIG.

As shown in FIG. 3, the ECU 23
Engine speed Ne and TOTAL target torque deriving means 51
Region setting means 52 for setting a region of the optimum fuel efficiency based on the TOTAL target torque derived in the above. That is, the region setting means 52 stores an operation region of the optimum fuel efficiency based on the TOTAL target torque and the engine speed Ne as shown in FIG.
Are stored as a map in the state shown in FIG. The map shown in FIG. 5 is an equal fuel consumption rate line (P1 (g / psh) to P6 (g / psh): P1
Based on <P2 <P3 <P4 <P5 <P5), the operation ranges are divided and stored in the stoichiometric and rich air-fuel ratio optimal fuel efficiency operation regions. The region is the stoichiometric best air-fuel ratio region,
The region is a rich best air-fuel ratio region.

In the ECU 16, as shown in FIG. 3, the engine 1 and the M / G are controlled in accordance with the charge amount of the battery 14 detected by the charge amount detection sensor 15 for the region set by the region setting means 52. A target torque setting means 53 for setting the target torque of the target torque setting means 5;
The engine 1 and the M / G 6 are controlled by the engine control means 54 and the M / G control means 55 based on the target torque set in Step 3.
Is controlled (operation control means). That is, the TOTAL target torque (required load) derived by the TOTAL target torque deriving means 51 as the required load deriving means is the engine 1
The operation of the M / G 6 is controlled in accordance with the output of the charge amount detection sensor 15 when it is not positioned alone in the best fuel efficiency region (region) of the lean air-fuel ratio or the stoichiometric air-fuel ratio. .

Specifically, as described above, the battery 1
If the charging of the engine 4 is sufficient, the M / G 6 is operated as a power source to reduce the load on the engine 1 so that the fuel efficiency of the engine 1 approaches the best air-fuel ratio region (region), or 1 is stopped. If the battery 14 is not sufficiently charged, the M / G 6 is operated as a generator to increase the load on the engine 1 to bring the fuel efficiency of the engine 1 closer to the best air-fuel ratio region (region). Has a function.

The operation of the operation control means will be described more specifically with reference to FIGS.

As shown in FIG. 8, in step S1, TOTAL
The target torque is read from the map shown in FIG. 4, and it is determined in step S2 whether or not the current mode is a charge request mode that requires charging of the battery 14. Since the initial state is not the charge request mode,
Is discharged, and the M / G 6 can be operated as a motor. Step S
In 3, it is determined whether or not the charge amount detected by the charge amount detection sensor 15 is lower than the value of the charge determination 2 which is the second lower limit value (a value at which charging needs to be started: for example, 50%). .

In the initial state, it is determined in step S3 that the charged amount is not less than the value of the charge determination 2, that is, it is determined that charging is not necessary. In step S4, the mode is set to the discharge permission mode, and in step S5, the discharge permission mode is set. Map shown in 6 (a) (b)
The engine target torque and the motor target torque are read based on F2 and F3. In the maps F2 and F3, the torque of the engine 1 and the torque of the M / G 6 in the discharge permission mode (which can be operated using the M / G 6 as a power source) are set with respect to the TOTAL target torque, respectively. . The torque line Tq obtained by adding the torque of the engine 1 and the torque of the M / G 6 is shown in FIG.
As shown in (c), the torque becomes equal to the TOTAL target torque, and in FIG. 6 (a), a torque line Tq added to the torque of the engine 1 is shown by a dotted line.

After reading the engine target torque and the motor target torque in step S5, the air-fuel ratio, throttle opening, fuel injection timing, ignition timing, EGR amount, etc. of the engine 1 are controlled in step S6 so that the target torque is obtained. At the same time, the M / G 6 is operated mainly as a motor so that the target torque is obtained. That is, in the discharge permission mode, the engine 1 and the M / G are controlled by the engine target torque and the motor target torque shown in FIGS.
6 is controlled.

That is, as shown in FIGS. 6A and 6B, while the TOTAL target torque is up to T1, the fuel consumption region of the engine 1 is out of the best fuel consumption region and the M / G 6 alone outputs the TOTAL target torque. As a result, the driving of the engine 1 is stopped and M / G 6
Only operate and run on M / G6.

When the TOTAL target torque is between T1 and T3,
This is the range where the engine 1 is driven in the lean best fuel ratio range. During the period from T1 to T1a, the engine 1 can be driven with the lean air-fuel ratio even if the engine 1 alone outputs the TOTAL target torque, but deviates from the lean best fuel ratio. Would. Therefore, the target torque of the engine 1 is set to be larger than the TOTAL target torque, and the engine 1 is driven in the lean best fuel consumption region. In order to offset this torque, the M / G 6 is operated as a generator, and the engine 1 can be driven in the lean best fuel consumption region without changing the total target torque.

When the TOTAL target torque is between T1 and T2,
Even when the engine 1 alone outputs the TOTAL target torque, the engine 1 can be driven within the lean best fuel consumption region. Therefore, there is no need to operate the M / G 6 as a motor or a generator. In the present embodiment, the map is formed so that the M / G 6 is operated as a generator so that a larger amount of charge can be secured within a range where the engine target torque does not deviate from the lean best fuel consumption region.

When the TOTAL target torque is between T2 and T3,
When the fuel consumption region of the engine 1 is between the best fuel consumption region of the lean air-fuel ratio and the best fuel consumption region of the stoichiometric air-fuel ratio, and the engine 1 alone is driven to obtain the TOTAL target torque, it deviates from the best fuel consumption region. Therefore, the TOTAL target torque
During the period from T2 to T3, the engine 1 is driven at a lean air-fuel ratio, the M / G 6 is operated as a motor, and the engine 1 is driven at a lean air-fuel ratio and the M / G 6 is operated.
As a result, the fuel efficiency region of the engine 1 alone exists between the lean air-fuel ratio and the best fuel efficiency region of the stoichiometric air-fuel ratio.
Even when the target torque is reached, the fuel consumption range of the engine 1 can be maintained in the best fuel consumption range of the lean air-fuel ratio.

When the TOTAL target torque is between T3 and T4,
This is a range in which the engine 1 is driven in the stoichiometric best air-fuel ratio region. While the TOTAL target torque is between T3 and T3a, the engine 1 can be driven at the stoichiometric air-fuel ratio even when the TOTAL target torque is output by itself, but the engine 1 is out of the stoichiometric best fuel economy region. Therefore, the target torque of the engine is set larger than the TOTAL target torque, and the engine is driven in the stoichiometric best fuel consumption area. To offset this increase in torque, the M / G 6 was operated as a generator,
It is possible to drive the engine 1 in the stoichiometric best fuel economy region without changing the target torque.

When the TOTAL target torque is between T3 and T4,
Even if the engine 1 alone outputs the TOTAL target torque, the engine 1 can be driven within the stoichiometric best fuel consumption region. Therefore, it is not necessary to operate the M / G 6 as a motor or a generator. In the present embodiment, the map is formed so that the M / G 6 is operated as a generator so that a larger amount of charge can be secured within a range in which the engine target torque does not deviate from the stoichiometric best fuel consumption region.

When the TOTAL target torque is between T4 and T5,
It is in the area exceeding the maximum torque in the stoichiometric best fuel consumption area of the engine 1, and the TOTAL target torque cannot be obtained in the stoichiometric best fuel consumption area of the engine 1 alone. Therefore, T
While the OTAL target torque is between T4 and T5, the engine 1 is driven at the maximum torque in the stoichiometric best fuel economy area and M / G
6 is operated as a motor to compensate for the insufficient torque. As a result, even when the TOTAL target torque cannot be obtained by the engine 1 alone, the TOTAL target torque can be obtained by maintaining the fuel efficiency region of the engine 1 in the best fuel efficiency region of the stoichiometric air-fuel ratio.

When the TOTAL target torque is T5 or more, the engine 1 is driven at the maximum torque in the stoichiometric best fuel economy area,
Even if the M / G 6 is driven as a motor at maximum, the TOTAL target torque is not reached, so the engine 1 is driven out of the stoichiometric best fuel consumption region to increase the torque. In addition, TOT
When the AL target torque is 0 or less, the motor target torque is mapped on the discharge side, but this is to prevent overcharging of the battery. Therefore, if regenerative control is emphasized, it may be mapped to the charging side.

As described above, in the discharge permission mode, the M / G 6 is operated as a motor to reduce the load on the engine 1 so that the fuel efficiency of the engine 1 approaches the best fuel efficiency region. ing. Also, M / G 6
Is operated as a motor to stop the engine 1. For this reason, the TOTAL target torque can be obtained while keeping the fuel consumption region of the engine 1 in the best fuel consumption region, and the fuel consumption can be improved without complicating the mechanism.

The above is the processing when it is determined that the charge amount is not below the value of the charge determination 2 in the discharge permission mode. On the other hand, when the operation is continued and the charge amount of the battery 14 decreases, the charge amount detected by the charge amount detection sensor 15 becomes the second lower limit value (a value that requires the start of charging: for example, even in the discharge permission mode). 50%)
Is determined to be smaller than the value of (1) in step S3. When it is determined in step S3 that the charge amount is lower than the value of the charge determination 2, the mode is set to the charge request mode in step S7.

After setting the charging request mode in step S7, the engine target torque and the motor target torque are read out in step S8 based on the maps F4 and F5 shown in FIGS. In maps F4 and F5, (M / G
6 as a generator) the torque of the engine 1 and
The torque of M / G 6 is set for each TOTAL target torque. The torque line Tq obtained by adding the torque of the engine 1 and the torque of the M / G 6 is, as shown in FIG.
7A, the torque line Tq added to the torque of the engine 1 is indicated by a dotted line.

After reading out the engine target torque and the motor target torque in step S7, the air-fuel ratio, throttle opening, fuel injection timing, ignition timing, EGR amount, etc. of the engine 1 are controlled in step S8 so that the target torque is obtained. At the same time, the M / G 6 is operated mainly as a generator so that the target torque is obtained. That is, in the charging request mode, the engine 1 and the M / G are controlled by the engine target torque and the motor target torque shown in FIGS.
6 is controlled.

That is, as shown in FIGS. 7 (a) and 7 (b), while the TOTAL target torque is between 0 and T11a, the fuel consumption region of the engine 1 is out of the best fuel consumption region and the M / G 6 is mainly driven by itself. However, since the engine is in the charge request mode, the engine 1 is driven at a lean air-fuel ratio (increase the load on the engine 1), and the M / G 6 is operated as a generator to drive the engine 1 at a lean air-fuel ratio. And the battery 14 is charged. Thus, the battery 14 can be charged while the fuel consumption region of the engine 1 is kept in the best fuel consumption region of the lean air-fuel ratio.

While the TOTAL target torque is between T11a and T12, the engine 1 can be driven in the lean best fuel consumption region even if the TOTAL target torque is output by itself. Operates the M / G 6 as a generator within a range that does not deviate from the lean best fuel consumption area.

When the TOTAL target torque is between T12 and T14, the fuel consumption range of the engine 1 is between the best fuel consumption range of the lean air-fuel ratio and the best fuel consumption range of the stoichiometric air-fuel ratio, and the best range of the stoichiometric air-fuel ratio. In the charge request mode, in this case, the load of the engine 1 is increased to drive the engine 1 in the stoichiometric best fuel consumption region, and the M / G 6 is operated as a generator to charge the battery 14. Thus, the battery 14 can be charged while the fuel consumption area of the engine 1 is maintained at the stoichiometric best fuel consumption area.

Since the TOTAL target torque is beyond the maximum torque in the stoichiometric best fuel consumption area of the engine 1 after T14 and T15, it is necessary to drive the engine 1 at a stoichiometric air-fuel ratio outside the stoichiometric best fuel consumption area. if there is
The M / G 6 is operated as a motor, and is driven by driving the engine 1 at the stoichiometric air-fuel ratio and operating the M / G 6.

As described above, in the charging request mode, the M / G 6 is operated as a generator to increase the load on the engine 1 so that the fuel efficiency of the engine 1 approaches the best fuel efficiency area. Has become. For this reason, the battery 14 can be charged while keeping the fuel consumption region of the engine 1 in the best fuel consumption region, and the TOTAL target torque can be obtained, so that the fuel consumption can be improved without complicating the mechanism.

The above is the processing when the charging request mode is set. On the other hand, after the mode is changed to the charge request mode in step S7, it is determined in step S2 that the current mode is the charge request mode that requires charging of the battery 14. When it is determined in step S2 that the current mode is the charge request mode, in step S9, the charge determination is performed so that the charge amount of the battery 14 is at the first lower limit (the minimum value at which discharge is sufficiently possible: for example, 60%). It is determined whether the number exceeds one. Note that the value of the charge determination 1 is set to a value larger than the value of the charge determination 2 described above, and a state in which hysteresis is provided between a value at which charging needs to be started and a minimum value at which discharge is sufficiently possible. It has become.

If it is determined in step S9 that the charge amount of the battery 14 exceeds the charge determination 1, the process proceeds to step S2, and it is determined in step S9 that the charge amount of the battery 14 does not exceed the charge determination 1. Step S
Then, the processing shifts to step S7. Then, as described above, the engine 1 and the M / G are set so that the target torque is obtained in each mode.
By controlling the operation of the M / G 6 and operating the M / G 6 by motor, the fuel consumption range of the engine 1 is maintained in the best fuel consumption range so as to obtain the TOTAL target torque. The target torque is obtained while charging the battery 14 in a state where the fuel efficiency region is maintained in the best fuel efficiency region.

When the hybrid electric vehicle is in the discharge permission mode, the M / G 6 is operated as a motor to reduce the load on the engine 1 so that the fuel efficiency of the engine 1 approaches the best fuel efficiency area. Or M /
Since the engine 6 is stopped by operating G6 as a motor, the TOTAL target torque can be obtained while keeping the fuel consumption range of the engine 1 in the best fuel consumption range. In addition, when the vehicle is in the charge request mode, the M / G 6 is operated as a generator to increase the load on the engine 1 so that the fuel efficiency of the engine 1 approaches the best fuel efficiency region. The battery 14 is charged while keeping the region in the best fuel consumption region, and the TOTAL target torque can be obtained. For this reason, the operation of the engine 1 and the M / G 6 is controlled without complicating the mechanism, and it is possible to improve the fuel efficiency and to achieve a fuel-efficient vehicle.

In the maps of FIGS. 6 and 7 of the above embodiment, when outputting a target torque equal to or less than the stoichiometric best fuel consumption region of the engine 1, the engine 1 is driven in the lean or stoichiometric best fuel consumption region. However, even if the engine 1 is not driven within the above-described best fuel consumption region, the fuel consumption can be improved only by operating the M / G 6 so as to approach the best fuel consumption region.

[0050]

The hybrid electric vehicle of the present invention includes an internal combustion engine capable of switching between at least a stoichiometric air-fuel ratio and a lean air-fuel ratio leaner than the stoichiometric air-fuel ratio, and an electric motor serving as a power source of the vehicle. The operation of the internal combustion engine and the electric motor according to the output of the battery state detection means when the required load derived by the load derivation means is not located in the best fuel efficiency region of the lean air-fuel ratio or the stoichiometric air-fuel ratio of the internal combustion engine by itself. Is controlled by the operation control means, and when the output of the battery state detection means can be discharged, the electric motor is operated as a power source to reduce the load on the internal combustion engine, thereby reducing the fuel consumption rate of the internal combustion engine. The engine should be brought closer to the best fuel economy region or the internal combustion engine should be stopped. In this case, the motor is operated as a generator to increase the load on the internal combustion engine so that the fuel efficiency of the internal combustion engine is brought closer to the best fuel efficiency area. Is maintained in the best fuel consumption region, a desired torque can be obtained, and the battery can be charged while maintaining the fuel consumption region of the internal combustion engine in the best fuel consumption region, and the desired torque can be obtained.

As a result, the operation of the internal combustion engine and the electric motor capable of performing the lean operation by switching at least to the stoichiometric air-fuel ratio and a lean air-fuel ratio leaner than the stoichiometric air-fuel ratio is efficiently controlled, and the mechanism is not complicated. It is possible to improve the fuel efficiency and make the vehicle fuel efficient.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a hybrid electric vehicle according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a multi-cylinder in-cylinder injection engine.

FIG. 3 is a block diagram of a main part of the control device.

FIG. 4 is a control map for operating an engine and an electric motor.

FIG. 5 is a control map for operating the engine.

FIG. 6 is a control map for operating an engine and an electric motor.

FIG. 7 is a control map for operating the engine and the electric motor.

FIG. 8 is an operation control flowchart of an engine and an electric motor.

[Explanation of symbols]

 1 In-cylinder injection engine (engine) 3 Clutch 5 Continuously variable transmission (CVT) 6 Electric motor / generator (M / G) 14 Battery 15 Charge detection sensor 16 Electronic control unit (ECU) 51 TOTAL target torque deriving means 52 Area setting means 53 Target torque setting means 54 Engine control means 55 M / G control means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme Court ゛ (Reference) F02D 41/04 305 (72) Inventor Masato Kuchita 5-33-8 Shiba 5-chome, Minato-ku, Tokyo Mitsubishi Motors In-house F-term (reference) 3G093 AA05 AA06 AA07 AA16 AB00 BA19 BA22 DA01 DA06 DB00 DB19 EA00 EA04 EA05 EA13 EB00 EB09 EC02 FA10 FA11 FB06 3G301 HA01 HA04 HA13 HA15 HA17 JA02 LA00 LB04 LC03 MA01 MA19 NA08 NC01 NE19

Claims (1)

[Claims] An internal combustion engine capable of switching between at least a stoichiometric air-fuel ratio and a lean air-fuel ratio that is leaner than the stoichiometric air-fuel ratio, an electric motor serving as a power source of a vehicle together with the internal combustion engine, and a battery connected to the electric motor A battery state detecting means for detecting a state of charge, a required load deriving means for deriving a required load on the power source, and a required air load derived by the required load deriving means is a lean air-fuel ratio of the internal combustion engine alone. Or operation control means for controlling the operation of the internal combustion engine and the electric motor in accordance with the output of the battery state detection means when the battery is not located in the best fuel efficiency region of the stoichiometric air-fuel ratio. By operating the electric motor as a power source and reducing the load on the internal combustion engine, the fuel efficiency of the internal combustion engine is brought closer to the best fuel consumption area, or the internal combustion engine is And a function of operating the electric motor as a generator to increase the load on the internal combustion engine so as to bring the fuel efficiency of the internal combustion engine closer to the best fuel consumption range. Electric car.