JP7052511B2 - Engine start control - Google Patents

Description

The present invention relates to an engine start control device for starting an engine having a plurality of cylinders and pistons by using a motor.

Generally, in a vehicle such as an automobile, a flywheel is rotated by a starter motor to start an engine of an internal combustion engine. On the other hand, in a hybrid electric vehicle (HEV) that combines an internal combustion engine and an electric drive motor as a vehicle drive source, it is considered to abolish the starter motor and start the engine with the motor torque of the drive motor. There is. In this case, it has been pointed out that it is necessary to leave surplus power in the power battery of the drive motor in preparation for starting the engine, which limits the allowable cruising range of electric traveling.

On the other hand, for example, when the engine of an automobile provided with an idling stop function is started, a technique is known in which the engine is quickly started by temporarily rotating the engine in the reverse direction (see Patent Document 1). In this technique, when the engine is started, the compression stroke cylinder at the time of stop, which was in the state of the compression stroke when the engine is stopped, is burned and the piston is pushed down. That is, the engine is rotated in the reverse direction. Along with this, the piston of the expansion stroke cylinder at the time of stop is pushed up and the pressure inside the cylinder is increased. By burning such an expansion stroke cylinder, the engine can be started in a forward rotation with high starting energy.

Japanese Unexamined Patent Publication No. 2004-124753

However, in the above-mentioned reverse rotation start of the engine, there is a problem that the difficulty of controlling the piston position for establishing the first combustion in the compression stroke cylinder at the time of stop is high. That is, the range of the piston position where combustion is established is narrow, and it is very difficult to control the stop position at which the piston is stopped at the combustion establishment position when the engine is stopped.

An object of the present invention is to provide an engine start control device capable of suppressing power consumption of a motor and facilitating start control while applying the techniques of starting an engine by a motor and starting the reverse rotation of the engine. It is in.

The engine start control device according to one aspect of the present invention includes a motor capable of driving an engine having a plurality of cylinders and pistons for burning fuel, a combustion control unit for controlling combustion operation in the cylinders, and an operation of the motor. The motor control unit includes, among the plurality of cylinders, the piston of the stopped compression stroke cylinder, which is in the state of the compression stroke when the engine is stopped, at the time of starting the engine. The motor drive amount is set according to the piston stop position of the compression stroke cylinder when the engine is stopped so that the engine stops after moving to a predetermined reference position that does not exceed the compression top dead point. After the motor control unit operates the motor with the motor drive amount, the engine is temporarily rotated in the reverse direction by burning the compression stroke cylinder when the engine is stopped, and then the expansion stroke is performed when the engine is stopped. The stopped expansion stroke cylinder in the state is burned to rotate the engine in the forward direction.

According to the engine start control device, the motor control unit sets a motor drive amount such that the piston of the compression stroke cylinder at the time of stop moves to a predetermined reference position that does not exceed the compression top dead center and then stops. When moving the piston, the largest torque is required at the timing of passing through the compression top dead center where the in-cylinder pressure is the highest. Therefore, when the engine is started by the motor, if the motor drive amount is set so as to rotate the engine to the range where the piston passes the compression top dead center, the motor consumes a large amount of electric power. In the above configuration, only the motor drive amount required for moving the piston to the reference position is set, so that the power consumption by the motor can be suppressed.

The combustion control unit burns the stopped compression stroke cylinder after the piston of the stopped compression stroke cylinder moves to the reference position due to the motor drive amount, and temporarily reverses the rotation of the engine. At this time, since the in-cylinder pressure is increased by the piston moved to the reference position, combustion is likely to occur. Further, when the engine is stopped, the piston is moved to the reference position by the motor drive amount regardless of the position (crank angle) where the piston of the compression stroke cylinder at the time of stop is stopped, so that the combustion is stably generated. Can be made to. Therefore, the combustion of the expansion stroke cylinder at the time of stop, which is executed after that, is also stable, and the engine can be reliably started in the forward rotation.

In the engine start control device, it is desirable that the reference position is set to a position on the advance angle side via a predetermined avoidance region with respect to the compression top dead center.

Since the avoidance region is close to the compression top dead center, it is a region where the in-cylinder pressure of the cylinder becomes high. According to the above-mentioned start control device, the motor drive amount is set so that the piston does not reach the avoidance region. Therefore, the power consumption of the motor can be suppressed.

In the engine start control device, it is desirable that the motor control unit acquires data that is a variable factor of the operating resistance of the piston at the time of starting the engine and corrects the motor drive amount.

According to this engine start control device, since the motor drive amount is set in consideration of the variable factor, the piston can be directed to an accurate target position (reference position). The variable factors are, for example, engine water temperature, engine oil temperature, atmospheric pressure, and the like. Therefore, even if the variable factor intervenes when the engine is started, it is possible to increase the certainty of combustion due to the reverse rotation in the compression stroke cylinder when stopped.

In the engine start control device, when the motor control unit sets the motor drive amount, the engine is started, when the operator performs the engine start operation, or when a predetermined engine stop condition is satisfied. It is desirable to include when a predetermined engine restart condition is satisfied after the engine is stopped.

According to this engine start control device, it is possible to suppress the power consumption of the motor and facilitate the start control both at the time of manual start of the engine and at the time of automatic start from idling stop or the like.

In the engine start control device, the engine is mounted on the vehicle together with an electric drive motor as a drive source for driving the vehicle, and the electric drive motor can drive the engine. It is desirable that it also serves as a motor.

According to this engine start control device, the use of a part called a starter motor can be omitted, and the power consumption of the electric drive motor can be suppressed. Therefore, the cruising range of electric traveling can be lengthened.

According to the present invention, there is provided an engine start control device capable of suppressing power consumption of a motor and facilitating start control while applying the techniques of starting an engine by a motor and starting the reverse rotation of the engine. Can be done.

FIG. 1 is a system diagram of a hybrid vehicle to which the engine start control device according to the present invention is applied. FIG. 2 is a schematic cross-sectional view showing the configuration of the engine. FIG. 3 is a diagram for explaining reverse rotation start control according to a comparative example. 4 (A) to 4 (C) are diagrams for explaining the operation by the reverse rotation start control according to the comparative example. 5 (A) to 5 (C) are diagrams for explaining the flow state of the fuel sprayed in the combustion chamber. FIG. 6 is a diagram for explaining the concept of reverse rotation start control according to the present invention. 7 (A) to 7 (D) are diagrams for explaining the operation by the reverse rotation start control according to the present invention. FIG. 8 is a graph showing a setting example of the motor torque. FIG. 9 is a time chart showing the operation of the four cylinders when the engine is started. FIG. 10 is a diagram for explaining an embodiment in which the start mode is set according to the stop position of the piston. FIG. 11 is a flowchart showing an example of engine start control according to the present embodiment. FIG. 12 is a flowchart of the start mode I. FIG. 13 is a flowchart of the start mode II. 14 (A) to 14 (C) are diagrams for explaining the operation of the start mode II. FIG. 15 is a flowchart of the start mode III. 16 (A) to 16 (D) are diagrams for explaining the operation of the start mode III.

[Construction of HEV]
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. First, the configuration of a hybrid electric vehicle HEV (vehicle) to which the engine start control device according to the present invention is applied will be described with reference to the system diagram of FIG. The hybrid electric vehicle HEV has an engine 1 that is a drive source of the vehicle HEV, a motor 20 that is also a drive source of the vehicle HEV and is for electric drive, and a drive force generated by the engine 1 and the motor 20 at an appropriate gear ratio. It includes a transmission 30 that transmits to the drive wheel W and a VCM (Vehicle Control Module) 40 that controls the overall operation of the vehicle HEV.

The engine 1 is a four-cycle internal combustion engine engine including a plurality of cylinders 2 for burning fuel such as gasoline. FIG. 1 shows an example in which four cylinders 2 are arranged in series. The combustion operation in the cylinder 2 is controlled by the PCM (Powertrain Control Module) 17 (a part of the combustion control unit). FIG. 2 is a schematic cross-sectional view showing the configuration of the engine 1, where only one cylinder 2 is shown. The engine 1 can reciprocate to each of the cylinder block 3 in which the cylinder 2 is formed, the cylinder head 4 attached to the upper surface of the cylinder block 3 so as to close the upper opening of each cylinder 2, and each cylinder 2. Includes a plurality of pistons 5 inserted into.

A pent-roof combustion chamber 6 is defined above the piston 5. In the combustion chamber 6, the air-fuel mixture of fuel and air is burned, and the piston 5 pushed down by the expansion force due to the combustion reciprocates in the vertical direction. Below the piston 5, a crank shaft 7, which is an output shaft of the engine 1, is provided. The crank shaft 7 is connected to the piston 5 via a connecting rod 8 and is rotationally driven according to the reciprocating motion of the piston 5.

The cylinder head 4 has an intake port 9 and an exhaust port 10 that open to the combustion chamber 6, an intake valve 11 that opens and closes the intake port 9, an exhaust valve 12 that opens and closes the exhaust port 10, and an intake valve 11 and an exhaust valve 12. Is assembled with valve mechanisms 13 and 14 that open and close in conjunction with the rotation of the crank shaft 7. Further, the cylinder head 4 is provided with a spark plug 15 that forcibly ignites the air-fuel mixture in the combustion chamber 6 to generate combustion, and an injector 16 that injects fuel into the combustion chamber 6. The electrode portion of the spark plug 15 is arranged near the central portion of the ceiling surface of the combustion chamber 6, while the fuel injection valve of the injector 16 is arranged near the side wall of the combustion chamber 6. A cavity 5A for receiving the fuel injected from the injector 16 is formed on the crown surface of the piston 5.

Returning to FIG. 1, the inverter 21 and the battery 22 are electrically connected to the motor 20. The motor 20 is, for example, a motor made of an Akisha gap type synchronous motor. The motor 20 functions as an electric motor that generates a driving force for propelling an electric vehicle HEV by being driven by the electric power supplied from the battery 22, while the motor 20 is rotationally driven by the regenerative force to charge the battery 22 with electric power. Also works as. The inverter 21 converts the DC power of the battery 22 into AC power and supplies it to the motor 20. At the time of regeneration, the inverter 21 converts the AC power generated by the motor 20 into DC power and charges the battery 22.

The transmission 30 is an automatic transmission that automatically shifts to a required gear ratio, and has a plurality of power transmission paths and a plurality of power transmission paths that are selected from among these paths to form a power transmission path having a specific gear ratio. It is equipped with a speed change clutch 31. The gear ratio of the transmission 30 is controlled by the TCM (Transmission Control Module) 32. The output of the transmission 30 is transmitted to the drive wheels W via the differential 33.

A first clutch 34 is arranged in the power transmission path between the engine 1 and the motor 20. Further, a second clutch 35 is arranged in the power transmission path between the motor 20 and the transmission 30. The first and second clutches 34 and 35 are for engaging and disengaging power transmission in the power transmission path, and are composed of, for example, a wet multi-plate clutch having a plurality of clutch plates soaked in oil. When the first and second clutches 34 and 35 are engaged, the engine 1 mainly drives the drive wheels W via the transmission 30 (engine running mode). In this state, the motor 20 can also assist the driving of the engine. On the other hand, when the first clutch 34 is in the released state and the second clutch 35 is in the engaged state, the electric traveling mode is set in which the drive wheels W are driven by only the motor 20 via the transmission 30. This state is also used during regenerative operation (during charging).

Further, in the present embodiment, the engine 1 can be driven by the motor 20. That is, no starter motor or the like is attached to the engine 1, and the electric drive motor 20 also serves as a motor for driving the engine 1 when the engine 1 is started. When the engine is started, the first clutch 34 is engaged and the second clutch 35 is released, and the motor torque generated by the motor 20 is applied to the engine 1 (engine starting mode).

The VCM 40 controls the operations of the engine 1, the motor 20, the transmission 30, and the first and second clutches 34 and 35 based on the sensors installed in various parts of the vehicle HEV and the operation information given by the operator. In FIG. 1, as the sensors, an engine oil temperature sensor SN1 for measuring the temperature of engine lubricating oil, an engine water temperature sensor SN2 for measuring the temperature of engine cooling water, and a crank shaft 7 for detecting the engine rotation speed and the position of the piston 5. The crank angle sensor SN3 for detecting the rotation angle of the engine and the pressure sensor SN4 for measuring the pressure in the driving environment are shown. In addition, accelerator opening information, intake / exhaust pressure, temperature information, and the like are input to the VCM 40.

The VCM 40 functionally includes an engine control unit 41 (a part of the combustion control unit), a motor control unit 42, a clutch control unit 43, and a transmission control unit 44. The engine control unit 41 controls various operations related to the engine 1, for example, the ignition timing of the ignition plug 15, the timing of fuel injection by the injector 16, the fuel injection amount, the amount of air taken into the combustion chamber 6, and the like via the PCM 17. , Control the engine torque.

The motor control unit 42 controls the operation of the motor 20 via the inverter 21. Specifically, the motor control unit 42 sets the required motor torque based on the information from the various sensors described above, controls the inverter 21 so that the motor 20 outputs the motor torque, and controls the motor from the battery 22. 20 is supplied with the required power. The motor control unit 42 controls the inverter 21 during the regenerative operation to control the charging operation of the battery 22. Further, in the present embodiment, when the engine 1 is started, the motor control unit 42 positions the piston 5 of the stopped compression stroke cylinder 2, which is in the state of the compression stroke when the engine 1 is stopped, at a predetermined position not exceeding the compression top dead center. The motor torque is set according to the stop position of the piston 5 and the motor 20 is operated so as to stop after moving to. This point will be described in detail later.

The clutch control unit 43 controls the engagement / release operation of the first and second clutches 34 and 35. Through the control of the engagement / release operation, the clutch control unit 43 executes at least the control of switching between the engine running mode (drive assist mode), the electric running mode, and the engine starting mode described above. The transmission control unit 44 controls the gear ratio of the transmission 30 via the TCM 32 according to the output torque, the vehicle speed, and the load set according to the driving scene.

[Reverse start control according to the comparative example]
In an automobile equipped with an idling stop function, it is required to promptly start the engine when the engine is restarted after the idling stop. In this case, a starting method that requires a considerable amount of time to complete starting, such as starting the engine via cranking that drives the engine output shaft with a starter motor, is not desirable. Therefore, when the engine is started, a reverse rotation start control that promptly starts the engine by temporarily rotating the engine in the reverse direction may be adopted. This reverse rotation start control is also adopted in this embodiment, but first, the conventional reverse reverse start control will be described as a comparative example.

FIG. 3 is a diagram for explaining the reverse rotation start control according to the comparative example, and FIGS. 4A to 4C are diagrams for explaining the operation of the engine by the reverse rotation start control according to the comparative example. In these figures, of the four cylinders 2 included in the engine 1, the stopped compression stroke cylinder 2a that was in the state of the compression stroke when the engine 1 was stopped and the stopped expansion stroke cylinder 2b that was in the state of the expansion stroke. Is schematically shown. In FIG. 3, “P1” indicates the stop position of the piston 5 when the engine 1 is stopped. FIG. 4A simply shows the positions of the pistons 5a and 5b in the cylinders 2a and 2b when the engine is stopped.

In the reverse rotation start control, the first ignition IG1 which is the first ignition is executed in the compression stroke cylinder 2a at the time of stop. As a result, combustion occurs in the compression stroke cylinder 2a when stopped, and as shown in FIG. 4B, the piston 5a is pushed down. That is, the engine 1 rotates in the reverse direction. Along with this, the piston 5b of the expansion stroke cylinder 2b at the time of stop is pushed up, and the in-cylinder pressure of the cylinder 2b is increased. Subsequently, the second ignition IG2, which is the second ignition, is executed in the expansion stroke cylinder 2b when stopped. As a result, combustion occurs in the expansion stroke cylinder 2b when stopped, and as shown in FIG. 4C, the piston 5b is pushed down. That is, the engine 1 rotates in the forward direction. Since this combustion occurs in a state where the in-cylinder pressure of the cylinder 2b is increased, the engine can be started in the forward rotation with high starting energy.

However, in the above-mentioned reverse rotation start, there is a problem that the difficulty of controlling the piston position for establishing the first combustion in the compression stroke cylinder 2a at the time of stop is high. That is, as added to FIG. 3, the stop range PA of the piston 5a that can obtain a high ignition probability in the compression stroke cylinder 2a at the time of stop is limited to a narrow range (PA = BTDC 60 deg to 102 deg in FIG. 3). Has been done. For example, when the engine 1 is temporarily stopped by idling stop control, it is difficult to stop the piston 5a in such a narrow stop range PA.

The lower limit of the stop range PA (BTDC102deg) is the timing at which the intake valve 11 starts to close, and if it is on the advance side than this, the airtightness of the cylinder 2a cannot be ensured, so that combustion is not successful. The upper limit of the stop range PA (BTDC60deg) is such that the air-fuel mixture containing the fuel sprayed from the injector 16 before the first ignition IG1 in the cylinder 2a can be satisfactorily flowed into the arrangement position of the electrode portion of the spark plug 15. The upper limit of the crank angle that can be achieved. This point will be described with reference to FIG.

5 (A) to 5 (C) are views for explaining the flow state of the fuel sprayed from the injector 16 into the combustion chamber 6. FIG. 5A shows the flow state of the atomized fuel when the piston 5 (5a) is stopped at the stop position P1 in FIG. 3 in the cylinder 2. A cavity 5A is recessed in the crown surface of the piston 5. A squish area 5S is formed around the cavity 5A so as to be inclined downward toward the outer peripheral edge of the piston 5 so as to be along the pent-roof type ceiling surface of the combustion chamber 6. The atomized fuel released from one side wall position of the combustion chamber 6 is guided by the squish area 5S to reach the other side wall position of the combustion chamber 6 and upward along the other side wall, as shown by the arrow A1. It is folded back and faces the electrode portion of the spark plug 15 arranged in the center of the ceiling surface of the combustion chamber 6. Therefore, the probability that the atomized fuel can be ignited by the first ignition IG1 becomes extremely high. The upper limit at which the flow of the atomized fuel indicated by the arrow A1 can be obtained is the upper limit of the stop range PA.

FIG. 5B shows that when the piston 5 exceeds the upper limit of the stop range PA and approaches the compression top dead center (BTDC 54 deg) and is stopped, fuel is sprayed from the injector 16 into the combustion chamber 6. The flow state of the atomized fuel in the case is shown. In this case, since the piston 5 is raised too much, as shown by the arrow A2, the spray fuel collides with the cavity 5A, the flow direction is changed, and the squish area 5S is not guided. Therefore, the return flow of the spray fuel as shown by the arrow A1 does not occur, and it becomes difficult for the spray fuel to reach the electrode portion of the spark plug 15. Therefore, the ignition probability of the atomized fuel by the first ignition IG1 is remarkably lowered. Further, as shown in FIG. 5C, if the piston 5 is lowered too much, the squish area 5S cannot serve to guide the atomized fuel upward. That is, as shown by the arrow A3, the spray fuel is folded downward at the position of the other side wall of the combustion chamber 6, and it is also difficult for the spray fuel to reach the electrode portion of the spark plug 15.

From the above, if the piston 5 does not stop within the stop range PA, for example, if the piston 5 does not stop at the stop position P1, the combustion condition for reverse rotation is not satisfied in the cylinder 2. That is, reverse start control cannot be performed, and there is no choice but to select another start control. However, when the engine is stopped, it is impossible to always spontaneously stop the piston 5 within a narrow stop range PA = BTDC 60 deg to 102 deg. Further, even if the control for stopping the piston 5 within the stop range PA by applying a brake to the piston 5 is performed, it is complicated and difficult. In particular, in the hybrid electric vehicle HEV of the present embodiment, the motor 20 can rotate the engine 1, but cannot forcibly stop the rotation, so that it is inherently difficult to control the stop of the piston 5. Therefore, in the method of the comparative example, there is a problem that the reverse rotation start control cannot always be performed. Further, the range of BTDC 60 deg to 102 deg cannot be said to be a region where the in-cylinder pressure is large in the cylinder 2, and there is also a problem that a large reverse rotation energy cannot be obtained even if combustion is established.

[Reverse start control according to this embodiment]
In view of the above problems, in the present embodiment, reverse rotation start control can be reliably performed regardless of the stop position of the piston 5 (5a) of the compression stroke cylinder 2 (2a) at the time of stop, and a large reverse rotation energy is obtained. Provided is a reverse rotation start control capable of obtaining (reverse rotation driving force). 6A and 6B are diagrams for explaining the concept of reverse rotation start control according to the present embodiment, and FIGS. 7A to 7D are diagrams for explaining the operation by the reverse rotation start control.

The major difference from the above comparative example is that, in the present embodiment, the piston 5a of the compression stroke cylinder 2a at the time of stop is crossed the compression top dead center (TDC) before being reverse-combusted at the time of starting the engine. It is a point to move to a predetermined reference position P0. For the reference position P0, a crank angle capable of sufficiently increasing the in-cylinder pressure of the compression stroke cylinder 2a when stopped is selected. For example, the reference position P0 can be set in the range of BTDC 50 deg to 15 deg, preferably in the range of BTDC 40 deg to 20 deg.

The motor control unit 42 (FIG. 1) causes the piston 5a when the engine 1 is stopped so that the piston 5a stopped at a random crank angle position moves to the reference position P0 and then stops when the engine 1 is started. Set the motor torque (motor drive amount) according to the stop position of. That is, as shown in FIG. 6, when the piston 5a is stopped at the stop position P11, the motor control unit 42 moves the piston 5a from the stop position P11 to the reference position P0 within a limited start time. Set the motor torque T1 that can be used.

Similarly, when the piston 5a is stopped at the stop position P12 closer to the bottom dead center (BDC) than P11, a motor torque T2 capable of moving the piston 5a from the stop position P12 to the reference position P0 is set. do. Further, when the piston 5a is stopped at the stop position P12 which is closer to the BDC than the P12, the motor torque T3 capable of moving the piston 5a from the stop position P13 to the reference position P0 is set.

Even if the piston 5a is stopped at any of the stop positions P11, P12, and P13, it is necessary to move the piston 5a to the reference position P0 within a predetermined start time, so that the motor torque is T1 <T2 <T3. It becomes a relationship. FIG. 8 is a graph schematically showing the relationship between the stop position of the piston 5a and the motor torque. The closer the stop position of the piston 5a is from the reference position P0 to the BDC, the larger the set motor torque tends to be. In reality, the set motor torque may not have a linear relationship with the crank angle as shown in FIG. The motor control unit 42 controls the inverter 21 so that the motor 20 outputs the set motor torque, and supplies the required electric power from the battery 22 to the motor 20.

The purpose of setting the reference position P0 in the range of, for example, BTDC 40 deg to 20 deg is to increase the in-cylinder pressure of the cylinder 2a to improve the ignitability, while suppressing the power consumption of the motor 20. When moving the piston 5a, the timing at which the largest torque is required is the timing at which the TDC with the highest in-cylinder pressure is passed. Therefore, when the engine is to be rotated to the extent that the piston 5a passes through the TDC, a large motor torque is required, and the motor 20 consumes a large amount of electric power. However, the reference position P0 of this embodiment is set to a crank angle that does not exceed the TDC. Therefore, a relatively small motor torque for moving the piston 5a from the stop positions P11, P12, and P13 to the reference position P0 is sufficient. Therefore, the power consumption by the motor 20 can be suppressed.

Further, as shown in FIG. 6, the reference position P0 is set to a position on the advance angle side of the TDC via a predetermined avoidance region Px. Since this avoidance region Px is close to the TDC, it is a region where the in-cylinder pressure of the cylinder 2a becomes considerably high when the piston 5a reaches the avoidance region Px. Attempting to push the piston 5a up to such an avoidance region Px requires a considerable amount of motor torque, although it is lower than when passing through the TDC. However, in the present embodiment, since the reference position P0 is set by removing the avoidance region Px of the crank angle close to the TDC, the motor torque can be suppressed.

The motor control unit 42 corrects and sets the above motor torque according to various conditions. The motor torque depends on the operating resistance of the piston. For example, when the piston 5a is moved from the stop position P13 in FIG. 6 to the reference position P0 by the motor torque, the larger the operating resistance of the piston 5a, the larger the motor torque is required. Here, the operating resistance of the piston 5a varies depending on various variable factors. The variable factors are, for example, engine water temperature, engine oil temperature, atmospheric pressure, and the like. The sliding resistance of the piston 5a may change depending on the temperature of the engine cooling water or the lubricating oil. In addition, the altitude (atmospheric pressure) at which the vehicle HEV travels also affects the sliding resistance. Therefore, when the engine 1 is started, the motor control unit 42 acquires the current measurement data from the engine oil temperature sensor SN1, the engine water temperature sensor SN2, and the pressure sensor SN4, and corrects the motor torque. As a result, the piston 5a can be accurately moved to the reference position P0 even if a variable factor of sliding resistance intervenes when the engine is started.

The operation of the reverse rotation start control of the present embodiment will be described with reference to FIGS. 7 (A) to 7 (D). FIG. 7A shows a stop compression stroke cylinder 2a (stop compression) in a state of compression stroke when the engine 1 is stopped and a stop expansion stroke cylinder 2b (stop expansion) in an expansion stroke state. , Is a diagram schematically showing the stop positions of the respective pistons 5a and 5b. It is assumed that the piston 5a of the compression stroke cylinder 2a at the time of stop is stopped at the stop position Ps at a certain crank angle.

When the engine 1 is started from the state of FIG. 7A, the VCM 40 executes a predetermined reverse rotation start control. Here, when the engine 1 is started, the engine is started when the operator performs a start operation of the engine 1 by pressing a start button provided on the hybrid electric vehicle HEV, or when a predetermined engine stop condition is satisfied. Includes when a predetermined engine restart condition is satisfied after stopping. In the latter case, in the case of idling stop, the engine stop condition is, for example, when the operator steps on the brake pedal to stop, or the select bar is in the "P" range, and the engine restart condition is, for example, the brake pedal. It is when the operator takes his foot off. That is, in the present embodiment, the engine start includes both the manual start of the engine 1 and the automatic start from the idling stop or the like.

At the time of starting the engine, the motor control unit 42 calculates the motor torque T required to move the piston 5a from the stop position Ps to the reference position P0. At this time, the motor torque T is corrected with reference to the measurement data of the sensors SN1, SN2, and SN4 described above. The clutch control unit 43 controls to disengage the second clutch 35 while engaging the first clutch 34. Then, the motor control unit 42 gives the calculated motor torque T to the motor 20. That is, the motor control unit 42 controls the inverter 21 to supply electric power to the motor 20 so that the motor 20 generates the required motor torque T.

As a result, as shown in FIG. 7B, the motor 20 starts the operation of pushing up the piston 5a toward the reference position P0. Along with this, the piston 5b of the expansion stroke cylinder 2b at the time of stop is pushed down by the reaction. At an appropriate timing while the piston 5a moves from the stop position Ps to the reference position P0, the engine control unit 41 controls the injector 16 of the stop compression stroke cylinder 2a to inject fuel into the cylinder 2a.

When the piston 5a reaches the reference position P0, the engine control unit 41 controls the spark plug 15 of the cylinder 2a to ignite the air-fuel mixture in the cylinder 2a for the first time after the start, that is, the first ignition IG1. To execute. As a result, as shown in FIG. 7C, combustion occurs in the compression stroke cylinder 2a when stopped, and the piston 5a is pushed down by the combustion pressure. That is, the engine 1 temporarily rotates in the reverse direction. By the reaction, the piston 5b of the expansion stroke cylinder 2b at the time of stop is pushed up. Therefore, the air in the cylinder 2b is compressed, and the in-cylinder pressure rises.

Next, the engine control unit 41 controls the injector 16 of the expansion stroke cylinder 2b when stopped to inject fuel into the cylinder 2b, and controls the spark plug 15 of the cylinder 2b to ignite the second time. 2 Ignition IG2 is executed. As a result, as shown in FIG. 7 (D), combustion occurs in the expansion stroke cylinder 2b when stopped, and the piston 5b is pushed down by the combustion pressure. That is, the engine 1 rotates in the forward direction. Hereinafter, the engine 1 is put into an operating state by executing the same operation in the other cylinder 2.

In the above, the operation has been described focusing on the compression stroke cylinder 2a at the stop and the expansion stroke cylinder 2b at the stop, but the operation of the four cylinders 2 at the time of starting the engine will be described with reference to the time chart of FIG. The reference numerals # 1 to # 4 in the figure represent four cylinders. In FIG. 9, the timing at which the engine is stopped is shown as "stop position Ps". Here, the # 3 cylinder is a compression stroke cylinder when stopped, and the # 1 cylinder is an expansion stroke cylinder when stopped. Further, the # 2 cylinder is an exhaust stroke cylinder when stopped, and the # 4 cylinder is an intake stroke cylinder when stopped. For each cycle of the # 1 to # 4 cylinders, the valve opening periods IV1 to IV4 of the intake valve 11 and the valve opening periods EV1 to EV4 of the exhaust valve 12 are added.

As described above, the piston 5 of the # 3 cylinder is moved by the motor 20 from the stop position Ps to the reference position P0. That is, the period during which the piston 5 is moved in the forward rotation direction from the stop position Ps to the reference position P0 is the drive period of the motor 20. During this drive period, the first fuel injection F1 which is the first fuel injection after the start is executed in the # 3 cylinder, and then the first ignition IG1 which is the first ignition operation after the start is executed. As a result, combustion occurs in the # 3 cylinder, and the engine 1 temporarily rotates in the reverse direction.

The second fuel injection F2 is executed in the # 1 cylinder at an appropriate timing during the above-mentioned reverse rotation period, and the second ignition IG2 is executed in the vicinity of the compression top of the # 1 cylinder. As a result, combustion occurs in the # 1 cylinder, and the engine 1 rotates in the forward direction. In a normal cycle, it is the # 3 cylinder that is burned next, but this # 3 cylinder cannot be used because it has already been burned during the compression stroke to generate the previous reverse rotation. Therefore, skipping the # 3 cylinder, the third fuel injection F3 is executed in the # 4 cylinder during the compression stroke, and the third ignition IG3 is executed during the expansion stroke. Subsequently, in the # 2 cylinder, the fourth fuel injection F4 is executed during the compression stroke, and the fourth ignition is executed during the expansion stroke.

According to the embodiment described above, the piston 5a of the compression stroke cylinder 2a at the time of stop is moved to the reference position P0 by the drive of the motor 20, and then the cylinder 2a is burned to temporarily reverse the rotation of the engine 1. .. Therefore, regardless of the position (crank angle) where the piston 5a of the cylinder 2a is stopped when the engine is stopped, the piston 5a is moved to the reference position P0 by the motor torque, so that combustion is stably generated in the cylinder 2a. be able to. Further, since the in-cylinder pressure of the cylinder 2a is increased by the piston 5a moved to the reference position P0, not only the ignitability to the air-fuel mixture is good, but also a large reverse rotation energy (reverse rotation driving force) is generated. Can be made to. Therefore, it is possible to increase the in-cylinder pressure of the expansion stroke cylinder 2b at the time of stopping in which combustion is performed following the cylinder 2a, and it is possible to smoothly start the forward rotation of the engine 1 thereafter.

Further, since the motor torque is only used to move the piston to the reference position P0, the power consumption by the motor 20 can be suppressed. Therefore, in the hybrid electric vehicle HEV in which the starter motor is abolished and the engine 1 is started by the motor torque of the motor 20, the usage amount of the battery 22 can be suppressed. Therefore, in a hybrid electric vehicle HEV in which it is necessary to leave surplus power in the battery in preparation for starting the engine, it is possible to extend the allowable cruising range of electric traveling.

[Starting control according to the piston stop position]
In the above embodiment, an example is shown in which the piston 5a of the compression stroke cylinder 2a at the time of stopping is simply moved to the reference position P0 when the engine is started. However, depending on the stop position of the piston 5a, it may be better to execute another start control. Here, an example in which the above-mentioned reverse rotation start control and another start control are used properly according to the piston stop position will be described.

FIG. 10 is a diagram for explaining an embodiment in which the start mode is set according to the stop position of the piston. FIG. 10 shows the operating regions of the stopped compression stroke cylinder 2a and the stopped expansion stroke cylinder 2b in relation to the crank angle. The compression stroke cylinder 2a at the stop is divided into three regions, a region (1), a region (2), and a region (3). The region (1) is a region between BDC and BTDC80deg, the region (2) is a region between BTDC80deg and BTDC60deg, and the region (3) is a region between BTDC60deg and TDC. Here, the BTDC 80deg is a crank angle corresponding to the intake valve closing position P (IVC) in which the intake valve 11 is completely closed in the compression stroke cylinder 2a when stopped. Further, the BTDC 60deg is an upper limit crank angle capable of satisfactorily guiding the air-fuel mixture to the spark plug 15 as described above with reference to FIG. 5A. These crank angles are just an example.

A region (2A) substantially corresponding to the range of the crank angle in the above region (2) and a region (3A) substantially corresponding to the range of the crank angle in the above region (3) are set in the expansion stroke cylinder 2b when stopped. Has been done. The region (2A) is a region before and after the exhaust valve opening position P (EVOS) at which the exhaust valve 12 begins to open in the expansion stroke cylinder 2b when stopped. Here, an example is shown in which the advance side end of the region (2A) is set to 90 deg and the retard side end is set to 138 deg. 138 deg is a crank angle corresponding to the exhaust valve open position P (EVOC) in which the exhaust valve 12 is fully opened, and is a crank angle substantially corresponding to the retard side end (BTDC 60 deg) in the above region (2). The region (3A) is a region from the exhaust valve open position P (EVOC) to the BDC.

In the VCM 40, when the engine 1 is stopped, whether the piston 5a of the compression stroke cylinder 2a at the stop is stopped in any of the above regions (1) to (3), and the piston 5b of the expansion stroke cylinder 2b at the stop is described above. A start mode is selected and a predetermined engine start control is executed based on whether the engine is stopped in the area (2A) or (3A). The stop positions of the pistons 5a and 5b when the engine is stopped are detected based on the measured values of the crank angle sensor SN3.

When the piston 5a is stopped in the region (1), the VCM 40 moves the piston 5a of the stopped compression stroke cylinder 2a to the reference position P0 by the motor torque as the start mode I as described above based on FIG. By combusting the cylinder 2a at the first start, the reverse start control for temporarily rotating the engine 1 in the reverse direction is executed. When the piston 5a is stopped in the region (2), the VCM 40 does not execute the reverse rotation start control described above. In this case, the VCM 40 executes the start control in which the expansion stroke cylinder 2b at the time of stop is burned at the first start and the engine 1 is rotated in the forward direction as the start mode II (see FIG. 14). When the piston 5a is stopped in the region (3), the VCM 40 does not perform the first combustion at the stop compression stroke cylinder 2a and the stop expansion stroke cylinder 2b. In this case, in the start mode III, the VCM 40 temporarily reverses the engine 1 by moving the piston 5c of the intake stroke cylinder 2c at the time of stop to the reference position P0 by the motor torque and burning the cylinder 2c at the first start. Execute reverse rotation start control to rotate. Hereinafter, these start modes I, II, and III will be described with reference to FIG.

FIG. 11 is a flowchart showing an example of starting control of the engine 1 by the VCM 40. The VCM 40 confirms that the engine 1 is in the stopped state on the premise of executing the start control (step S1). Next, the VCM 40 confirms whether or not there is an instruction to start the engine 1 (step S2). The start instruction here includes a predetermined engine restart condition after the engine 1 is stopped due to the satisfaction of a predetermined engine stop condition, for example, when restarting the engine 1 temporarily stopped by the idling stop operation. This includes a start instruction when the above is satisfied and a start instruction when the operator of the hybrid electric vehicle HEV performs the engine start operation. When there is no start instruction of the engine 1 (NO in step S2), the VCM 40 suspends the start control.

When there is an instruction to start the engine 1 (YES in step S2), the VCM 40 determines whether the stop position of the piston 5a of the compression stroke cylinder 2a at the time of stop is in any of the above regions (1) to (3). (Step S3). Specifically, the VCM 40 derives the stopped crank angle of the piston 5a based on the measured value (piston stop position information) of the crank angle sensor SN3. Then, the VCM 40 determines which of the crank angle ranges predetermined to partition the regions (1) to (3).

Subsequently, the motor control unit 42 of the VCM 40 sets the motor torque for operating the motor 20 when the engine 1 is started (step S4). When the start mode I is selected, the motor torque set in step S4 moves the piston 5a of the stopped compression stroke cylinder 2a to the reference position P0 by the motor 20 within a predetermined start period as described above. It is the motor torque required to make it. As will be described later, in the case of the start mode II, the motor torque required for the start assist is set by the motor 20 when the engine 1 is started in the forward rotation. Further, in the case of the start mode III, the motor torque required to move the piston 5c of the intake stroke cylinder 2c at the stop to the reference position P0 by the motor 20 is set.

Hereinafter, the VCM 40 sets any of the start modes I to III based on the determination result of step S3 (steps S5 and S6). In step S3, when it is determined that the stop position of the piston 5a of the compression stroke cylinder 2a at the time of stop is in the region (1) (YES in step S5), the start mode I is set (step S11; FIG. 12). When it is determined that the stop position of the piston 5a is not in the region (1) (NO in step S5) and is in the region (2) (YES in step S6), the start mode II is set (step S21; FIG. 13). ). Further, when the stop position of the piston 5a is not the region (2) (NO in step S6), the start mode III is set (step S31; FIG. 15).

<Starting mode I>
FIG. 12 is a flowchart showing the operation of the start mode I. The flow shown here is substantially the same as the operation described above with reference to FIG. 7. In FIG. 12, the operations of the compression stroke cylinder 2a at the stop and the expansion stroke cylinder 2b at the stop are described in series, but the operations of both cylinders 2a and 2b may be partially overlapped (the following flowchart). But the same).

The motor control unit 42 controls the inverter 21 so that the motor 20 generates the motor torque set in step S3, and drives the motor 20 (step S101). After generating the motor torque, the motor 20 is stopped (step S102). In parallel with the operation of the motor 20, a process for the compression stroke cylinder 2a at the time of stop is executed. That is, the engine control unit 41 controls the injector 16 of the cylinder 2a to execute the fuel injection operation for the cylinder 2a (step S12). With the stop of the motor 20 (step S102), the piston 5a reaches the reference position P0 (step S13).

After that (or immediately before reaching), the engine control unit 41 controls the spark plug 15 of the cylinder 2a to perform the first ignition of the first start in the cylinder 2a (step S14). As a result, combustion occurs in the cylinder 2a, and the piston 5a is pushed down from the reference position P0 toward the advance angle side. That is, the engine 1 temporarily rotates in the reverse direction (step S15).

Along with this reverse rotation, the piston 5b of the expansion stroke cylinder 2b at the time of stopping starts to rise, and the air in the cylinder 2b is gradually compressed. In this state, the engine control unit 41 controls the injector 16 of the cylinder 2b to execute the fuel injection operation for the cylinder 2b (step S16). Then, when the piston 5b reaches a predetermined crank angle in the cylinder 2b (step S17), the engine control unit 41 controls the spark plug 15 of the cylinder 2b to perform the second ignition for the second start in the cylinder 2b. (Step S18). As a result, combustion occurs in the cylinder 2b, and the piston 5b is pushed down to the retard side. That is, the engine 1 rotates in the forward direction (step S19). After that, ignition is performed from the third start onward, and the engine 1 is started.

<Starting mode II>
In the region (2) where the start mode II is selected, the piston 5a of the compression stroke cylinder 2a at the time of stop stops closer to the TDC than the intake valve closing position P (IVC), which is the closing time of the intake valve 11. It is in a state of being. In this case, the engine control unit 41 does not execute the reverse rotation start control as in the start mode I. This is because when the stop position of the piston 5a is on the TDC side of the closing time of the intake valve 11, the compression allowance of the combustion chamber 6 in the cylinder 2a by the piston 5a is small. That is, since the inside of the cylinder 2a returns to the atmospheric pressure when the engine is stopped, the closer the piston 5a is to the TDC, the smaller the degree of increase in the cylinder pressure is even if the piston 5a is moved to the reference position P0. Therefore, even if the cylinder 2a in which the piston 5a is stopped is burned in the region (2), stable combustion may not be ensured or sufficient starting power may not be obtained. That is, useless combustion may be performed in the cylinder 2a.

In this start mode II, the engine control unit 41 does not execute combustion for reverse rotation in the compression stroke cylinder 2a at the time of stop, but burns the expansion stroke cylinder 2b at the stop at the first start to correct the engine 1. Rotate start. As shown in FIG. 10, when the piston 5a is present in the region (2) of the cylinder 2a, the piston 5b of the cylinder 2b is present in the region (2A). In this case, the stop position of the piston 5b is a position on the TDC side of the exhaust valve open position P (EVOC = 138deg).

When the piston 5b is stopped on the BDC side of the exhaust valve open position P (EVOC), the airtightness of the cylinder 2b is not ensured, so that the cylinder 2b cannot be used for the first combustion at the start. However, when the piston 5b is stopped on the TDC side of the exhaust valve open position P (EVOC), the airtightness of the cylinder 2b can be ensured. The intake valve 11 starts to open at the exhaust valve opening start position P (EVOS = 116deg), but since it is not completely opened, combustion can be generated. In fact, as added to FIG. 10, the ignition rate in the region (2A) is high, and the average in-cylinder maximum pressure Pmax in the range of the crank angle of 116 deg to 138 deg is also high.

From the above, in the start mode II, the expansion stroke cylinder 2b at the time of stop is used for the first combustion of the start. However, unlike the start mode I, the operation of pushing up the piston 5b is omitted, so that the in-cylinder pressure of the cylinder 2b tends to be insufficient. Therefore, it is assumed that the piston 5 cannot be sufficiently torqued to pass through the TDC in each cylinder 2 at the initial stage of starting. Therefore, the driving force of the motor 20 is assistedly applied to the engine 1 at the initial stage of starting to ensure smooth starting.

13 is a flowchart showing the operation of the start mode II, and FIGS. 14 (A) to 14 (C) are diagrams for explaining the operation of the start mode II. FIG. 14A schematically shows the stop positions of the pistons 5a and 5b of the compression stroke cylinder 2a at the stop and the expansion stroke cylinder 2b at the stop when the start mode II is selected. In this case, the piston 5a of the cylinder 2a is located closer to the TDC than the intake valve closing position P (IVC), and the piston 5b of the cylinder 2b is located closer to the TDC side than the exhaust valve opening position P (EVOC). Each is stopped.

When the start mode II is executed, the clutch control unit 43 controls to disengage the second clutch 35 while engaging the first clutch 34. This is to assist the start by the motor 20. The motor control unit 42 sets the motor torque required to perform the start assist. Then, the motor control unit 42 controls the inverter 21 so that the motor 20 generates the set motor torque, starts driving the motor 20 (step S201), and gives the motor torque for start assist to the engine 1.

In parallel with the operation of the motor 20, a process for the expansion stroke cylinder 2b at the time of stop is executed. That is, the engine control unit 41 controls the injector 16 of the cylinder 2b to execute the fuel injection operation for the cylinder 2b (step S22). When the piston 5b reaches a predetermined crank angle in the cylinder 2b (step S23), the engine control unit 41 controls the spark plug 15 of the cylinder 2b to start 1 in the cylinder 2b as shown in FIG. 14 (B). The first ignition IG21 is performed for the second time (step S24). As a result, combustion occurs in the cylinder 2b, and the piston 5b is pushed down to the retard side with the assistance of the driving force of the motor 20. That is, the engine 1 rotates in the forward direction (step S25).

Subsequently, the engine control unit 41 controls the injector 16 of the compression stroke cylinder 2a when stopped to execute the fuel injection operation for the cylinder 2a (step S26). At this stage, the cylinder 2a is in the expansion stroke. Then, when the piston 5a reaches a predetermined crank angle in the cylinder 2a (step S27), the engine control unit 41 controls the spark plug 15 of the cylinder 2a in the cylinder 2b as shown in FIG. 14C. The second ignition IG22 for the second start is performed (step S28). As a result, combustion occurs in the cylinder 2a, the piston 5a is pushed down to the retard side, and the engine 1 rotates in the forward direction (step S29). The start assist is continued until the stage of the second ignition IG22, and then the motor 20 is stopped (step S202). After that, ignition is performed from the third start onward, and the engine 1 is started.

<Starting mode III>
The region (3) in which the start mode III is selected is a region in which the piston 5a of the compression stroke cylinder 2a at the time of stop is closer to the TDC than the region (2) above, which is closer to the intake valve closing position P (IVC). .. As shown in FIG. 10, when the piston 5a is present in the region (3) of the cylinder 2a, the piston 5b of the cylinder 2b is present in the region (3A). In this case, the stop position of the piston 5b is a position on the BDC side of the exhaust valve open position P (EVOC). Therefore, since the airtightness cannot be ensured, the cylinder 2b cannot be used for the first combustion at the start. Of course, the reverse rotation start using the cylinder 2a cannot be used because the compression allowance due to the movement of the piston 5a by the motor 20 becomes smaller than that of the start mode II. Therefore, in the start mode III, the engine control unit 41 does not execute the first combustion using the cylinders 2a and 2b. Instead, in this start mode III, the engine control unit 41 executes the first combustion of the start using the intake intake stroke cylinder 2c (FIG. 16) at the time of stop, and starts the engine 1 in the reverse rotation.

15 is a flowchart of the start mode III, and FIGS. 16A to 16D are diagrams for explaining the operation of the start mode III. FIG. 16A schematically shows the stop positions of the pistons 5a and 5b of the compression stroke cylinder 2a at the stop and the expansion stroke cylinder 2b at the stop when the start mode III is selected. In this case, the piston 5a of the cylinder 2a is located closer to the TDC than the intake valve closing position P (IVC), and the piston 5b of the cylinder 2b is located closer to the BDC side than the exhaust valve opening position P (EVOC). Each is stopped. Referring to FIG. 10, the piston 5a of the cylinder 2a is stopped in the region (3) closest to the TDC. In this case, the piston 5c of the intake stroke cylinder 2c at the time of stop is located in the range of the crank angle corresponding to the region (3A) of FIG.

In the start mode III, the piston 5c of the intake stroke cylinder 2c at the time of stop is moved to the above-mentioned reference position P0 by the driving force of the motor 20, and the first combustion of the start is executed by the cylinder 2c. In this combustion, the engine 1 is rotated in the reverse direction to increase the in-cylinder pressure of another cylinder (for example, the compression stroke cylinder 2a when stopped), and then the second combustion is executed to start the engine 1 in the forward rotation. When the start mode III is executed, the clutch control unit 43 controls to disengage the second clutch 35 while engaging the first clutch 34. As shown in FIG. 16B, the motor control unit 42 calculates the motor torque required to move the piston 5c of the cylinder 2c from its stop position Ps to the reference position P0 through the BDC. At this time, the motor torque is corrected with reference to the measurement data of the sensors SN1, SN2, and SN4.

With reference to FIG. 15, the motor control unit 42 controls the inverter 21 so that the motor 20 generates the set motor torque, and drives the motor 20 (step S301). After generating the motor torque, the motor 20 is stopped (step S302). As a result, as shown in FIG. 16C, the piston 5c of the intake stroke cylinder 2c at the time of stop is moved toward the reference position P0. In parallel with the operation of the motor 20, the process for the intake stroke cylinder 2c at the time of stop is executed. That is, the engine control unit 41 controls the injector 16 of the cylinder 2c to execute the fuel injection operation for the cylinder 2c (step S32). With the stop of the motor 20 (step S302), the piston 5c reaches the reference position P0 (step S33). At this time, the piston 5a of the compression stroke cylinder 2a at the time of stop is lowered, and the compression allowance is secured.

After that (or just before arrival), the engine control unit 41 controls the spark plug 15 of the cylinder 2c to perform the first ignition IG31 of the first start in the cylinder 2c as shown in FIG. 16 (D) (step). S34). As a result, combustion occurs in the cylinder 2c, and the piston 5c is pushed down from the reference position P0 toward the advance angle side. That is, the engine 1 temporarily rotates in the reverse direction (step S35).

Along with this reverse rotation, the piston 5a of the compression stroke cylinder 2a at the time of stop starts to rise, and the air in the cylinder 2b is gradually compressed. Since the piston 5c of the cylinder 2c is moved in a forward rotation beyond the BDC by the motor torque, the cylinder 2a is in the expansion stroke. In this state, the engine control unit 41 controls the injector 16 of the cylinder 2a to execute the fuel injection operation for the cylinder 2a (step S36). Then, when the piston 5a reaches a predetermined crank angle in the cylinder 2a (step S37), the engine control unit 41 controls the spark plug 15 of the cylinder 2a to perform the second ignition for the second start in the cylinder 2a. (Step S38). As a result, combustion occurs in the cylinder 2a, and the piston 5a is pushed down to the retard side. That is, the engine 1 rotates in the forward direction (step S39). After that, ignition is performed from the third start onward, and the engine 1 is started.

[Modification Embodiment]
Although the embodiment of the present invention has been described above, the present invention is not limited to this, and the following modified embodiments can be taken.

(1) In the above embodiment, an example is shown in which the motor torque according to the stop position of the piston 5a of the compression stroke cylinder 2a at the time of stop is set as the motor drive amount of the motor 20 set by the motor control unit 42. When there is a margin in the engine start period, the motor torque is kept constant, and the drive time (motor drive amount) of the motor 20 is set according to the distance from the stop position of the piston 5a to the reference position P0. Is also good.

(2) In the above embodiment, an example is shown in which the engine start control device according to the present invention is applied to a hybrid electric vehicle HEV. The present invention is not limited to the hybrid electric vehicle HEV, and can be applied to various vehicles and power devices configured so that an internal combustion engine such as a gasoline engine or a diesel engine can be driven by a motor.

(3) In the above embodiment, an example is shown in which the engine 1 is started from a state in which the hybrid electric vehicle HEV is stopped. The above-mentioned start control is also applied when the engine 1 in the stopped state is started and switched to the engine running mode while the automobile HEV is running, that is, while the vehicle is running in the electric running mode using the motor 20 as a drive source. be able to. In this case, instead of the method of moving the piston 5 to the reference position by the motor 20, the driving force during traveling is transmitted to the engine 1 by the operation of the first clutch 34, so that the piston 5 is moved to the reference position. You can do it.

Specifically, when a switching instruction is given to the engine running mode while running in the electric running mode, the clutch control unit 43 puts the first clutch 34 in the half-clutch state or puts the first clutch 34 in the engaged state for a moment. , The driving force is transmitted to the engine 1 in the stopped state. As a result, for example, the piston 5a of the compression stroke cylinder 2a at the time of stop shown in FIG. 7A is directed from the stop position Ps to the reference position P0. The operation for stopping the piston 5a at the reference position P0 is disengagement of the first clutch 34. That is, the clutch control unit 43 engages or semi-engages the first clutch 34 only while the piston 5a is moved from the stop position Ps to the reference position P0. Instead of the stop operation, combustion for reverse rotation may be performed in the compression stroke cylinder 2a at the time of stop, and the driving force of the reverse combustion generated at that time may be used for braking the piston 5a.

1 Engine 2, 2a, 2b, 2c Cylinder 5, 5a, 5b, 5c Piston 11 Intake valve 12 Exhaust valve 15 Spark plug 16 Injector 17 PCM (part of combustion control unit)
20 motor (electric drive motor)
21 Inverter 22 Battery 30 Transmission 40 VCM
41 Engine control unit (part of combustion control unit)
42 Motor control unit HEV hybrid vehicle P0 reference position Ps, P1, P11, P12, P13 piston stop position Px avoidance area

Claims (5)

A motor that can drive an engine with multiple cylinders and pistons that burn fuel,
A combustion control unit that controls the combustion operation in the cylinder,
A motor control unit that controls the operation of the motor is provided.
The motor control unit has a predetermined reference that the piston of the stopped compression stroke cylinder, which is in the state of the compression stroke when the engine is stopped, does not exceed the compression top dead center when the engine is started. The motor drive amount is set according to the piston stop position of the compression stroke cylinder at the time of stop when the engine is stopped so that the engine stops after moving to the position.
The combustion control unit
After the motor control unit operates the motor with the motor drive amount, the engine is temporarily rotated in the reverse direction by burning the compression stroke cylinder when stopped.
Next, an engine start control device that burns a stopped expansion stroke cylinder that is in an expansion stroke state when the engine is stopped to rotate the engine in a forward direction. In the engine start control device according to claim 1,
The reference position is an engine start control device set to a position on the advance angle side via a predetermined avoidance region with respect to the compression top dead center. In the engine start control device according to claim 1 or 2.
The motor control unit is an engine start control device that acquires data that is a variable factor of the operating resistance of the piston when the engine is started and corrects the motor drive amount. The engine start control device according to any one of claims 1 to 3.
When the engine is started, the motor control unit sets the motor drive amount.
When the operator starts the engine, or
An engine start control device including when a predetermined engine restart condition is satisfied after the engine is stopped due to the establishment of a predetermined engine stop condition. In the engine start control device according to any one of claims 1 to 4.
The engine is mounted on the vehicle together with an electric drive motor as a drive source for driving the vehicle.
An engine start control device in which the electric drive motor also serves as a motor capable of driving the engine.

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