JP2013124083A - Controller of hybrid electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller of a hybrid electric vehicle capable of securing engine start property, while suppressing shortening of product life of an alternator and a starter, in automatic stop and start control of the hybrid electric vehicle.SOLUTION: In the hybrid electric vehicle in which a clutch 6 is provided between the engine 2 and a motor 4, when automatic stop condition of the engine 2 is established (S1), fuel supply to the engine is stopped (S2). When SOC (state of charge) of a high voltage battery 18 is a predetermined stop time SOC or less, engine rotation stop control for stopping engine rotation at a predetermined stop crank angle suitable for starting the engine is performed (S4), and when the SOC is larger than the predetermined stop time SOC, engine rotation stop control is inhibited (S5).

Description

  The present invention relates to a control device that performs automatic stop and automatic start of an engine when a predetermined condition is satisfied in a hybrid electric vehicle including an engine and a motor as drive sources.

In recent years, so-called idle stop / auto start (automatic stop start) control has been performed, which improves the fuel efficiency and exhaust gas performance by automatically stopping the engine during parking and waiting for a signal and starting automatically when starting. ing.
In such automatic stop / start control, it is necessary to start the engine promptly so that the vehicle can be started quickly after the engine is automatically stopped.

The startability of the engine changes depending on the stop position of the piston. If the piston is stopped at a position suitable for cranking, the engine can be started quickly.
In view of this, a technique has been developed in which the piston is stopped at an appropriate position suitable for cranking by a starter by adjusting the target generated current of the alternator when the engine is automatically stopped (see Patent Document 1).

  In recent years, hybrid electric vehicles having an engine and a motor as drive sources have been developed as a means of reducing fuel consumption and improving exhaust gas performance. Automatic stop / start control of the engine is also applied to the hybrid electric vehicle. ing.

JP 2004-17919 A

  However, when the engine is stopped using the alternator every time the engine is automatically stopped as in the technology of the above-mentioned Patent Document 1, there are many opportunities to increase the power generation load of the alternator, and the product life of the alternator is reduced. There's a problem. In addition, the starter that performs cranking of the engine also has a problem that the number of engine starts increases due to the engine automatic stop / start control, and the product life of the starter is reduced.

In particular, in the case of a hybrid electric vehicle, if the engine is stopped and started while the engine and the motor are connected, the mass load of the motor will be applied in addition to the engine, and the load and cranking for stopping the rotation of the engine will be applied. The load increases.
If the technique of Patent Document 1 is applied to such a hybrid electric vehicle, the burden on the alternator for stopping the rotation of the engine is further increased, and the product life of the alternator is further reduced. As for the starter, if the cranking of the engine is performed in a state where the engine and the motor are connected in the hybrid electric vehicle, the burden on the starter increases, and the product life is further reduced.

On the other hand, if the power generation amount of the alternator is increased or the torque that can be generated by the starter is increased, there arises a problem that the alternator and the starter are increased in size.
The present invention has been made to solve such a problem, and an object thereof is to start an engine while suppressing a decrease in product life of an alternator or a starter in an automatic stop start control of a hybrid electric vehicle. It is an object of the present invention to provide a control device for a hybrid electric vehicle that can ensure safety.

  In order to achieve the above object, the hybrid electric vehicle control device according to claim 1 is a hybrid electric vehicle control device capable of selecting an engine and a motor as a drive source, and generates electric power using the driving force of the engine. An alternator for performing the engine, a starter for cranking the engine, engine fuel supply stop control means for stopping fuel supply to the engine when a predetermined engine automatic stop condition is satisfied, Suitable for cranking by the starter with the motor or the alternator when the charge amount of the battery that supplies power to the motor is less than or equal to a predetermined stop charge amount when a predetermined engine automatic stop condition is satisfied Engine rotation stop control for stopping the rotation of the engine at a predetermined stop crank angle Engine rotation stop control means that executes the engine rotation stop control when a charge amount of a battery that executes and supplies power to the motor is larger than the predetermined stop-time charge amount. Yes.

  According to a control apparatus for a hybrid electric vehicle of a second aspect, the driving force of the engine is provided between the engine and the motor according to the first aspect, and is transmitted from the engine to the drive wheels via the motor. The clutch means for connecting and disconnecting and the charge amount of the battery for supplying power to the motor when the predetermined engine automatic start condition is satisfied after the rotation of the engine is stopped is larger than the predetermined start-time charge amount. In some cases, the engine includes: an engine automatic start control unit configured to crank the engine by a torque generated by the motor with the clutch unit connected.

  According to a third aspect of the present invention, there is provided the hybrid electric vehicle control apparatus according to the first or second aspect, wherein the engine drive is provided between the engine and the motor and transmitted from the engine to the drive wheels via the motor. The clutch means for connecting and disconnecting the force, and the charge amount of the battery for supplying power to the motor when the predetermined engine automatic start condition is satisfied after the rotation of the engine is stopped is equal to or less than the predetermined start time charge amount In this case, an engine automatic start control means for cranking the engine by the starter with the clutch means disengaged is provided.

  According to the hybrid electric vehicle control apparatus of the first aspect of the present invention using the above-described means, in the hybrid electric vehicle including the engine and the motor, the battery charge amount (hereinafter referred to as SOC: State Of Charge) during the engine automatic stop control. ) Is less than or equal to a predetermined stop charge amount, engine rotation stop control by a motor or alternator is executed. If the SOC is greater than a predetermined stop charge amount, engine rotation stop control is not executed. To do.

  As described above, when the SOC of the battery is relatively low, the rotation of the engine is stopped at a crank angle suitable for cranking by the starter by using a motor or an alternator during automatic engine stop. As a result, when restarting after automatic engine stop, the piston position of the engine is in a position suitable for cranking by the starter, so that the starter can be started quickly and the load on the starter is also reduced. be able to.

On the other hand, when the SOC capable of cranking the engine using a motor is relatively high, the frequency of use of the alternator can be reduced by not executing the engine rotation stop control when the engine is automatically stopped.
As a result, engine startability can be ensured while suppressing a decrease in the product life of the alternator and starter.

  According to the hybrid electric vehicle control device of the second aspect, in the hybrid electric vehicle in which the clutch means is provided between the engine and the motor, the SOC of the battery is predetermined during the engine automatic start control after the engine is automatically stopped. When it is larger than the SOC at the time of starting, the clutch means is connected and the engine is cranked by the motor.

  In cranking using a motor as a drive source, the influence on startability with respect to the piston stop position of the engine is lower than cranking using a starter, so the SOC of the battery is relatively high at the time of automatic engine start. In this case, by starting the engine with the motor, it is possible to reduce the frequency of use of the starter while suppressing a decrease in the startability of the engine.

  According to the hybrid electric vehicle control apparatus of the third aspect, in the hybrid electric vehicle in which the clutch means is provided between the engine and the motor, the SOC of the battery is predetermined during the automatic engine start control after the automatic engine stop. If it is below the starting SOC, the clutch means is disconnected and the engine is cranked by the starter.

  Thus, when the SOC of the battery is relatively low during the automatic engine start, the clutch means is disengaged to eliminate the mass load of the motor for cranking the engine and reduce the load on the starter at the start. can do.

It is a schematic block diagram of the control apparatus of the hybrid electric vehicle which concerns on one Embodiment of this invention. It is a flowchart which shows the engine automatic stop control routine which integrated ECU of the control apparatus of the hybrid electric vehicle which concerns on one Embodiment of this invention performs. It is a flowchart which shows the engine rotation stop control routine which integrated ECU of the control apparatus of the hybrid electric vehicle which concerns on one Embodiment of this invention performs. It is a flowchart which shows the engine automatic start control routine which integrated ECU of the control apparatus of the hybrid electric vehicle which concerns on one Embodiment of this invention performs.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a control apparatus for a hybrid electric vehicle according to an embodiment of the present invention, which will be described with reference to FIG.
A vehicle 1 shown in FIG. 1 is a hybrid electric vehicle including an engine 2 and a motor 4 as drive sources.

The engine 2 is an internal combustion engine that is generally used for automobiles, such as a diesel engine or a gasoline engine, and is not particularly limited here.
A clutch 6 is provided between the engine 2 and the motor 4. The output shaft of the engine 2 is connected to the input shaft of the clutch 6, and the rotary shaft of the motor 4 is connected to the output shaft of the clutch 6. ing.

The motor 4 is, for example, a permanent magnet type synchronous motor that can generate power, and the rotating shaft of the motor 4 is connected to the input shaft of the transmission 8. The drive force is transmitted from the output shaft of the transmission 8 to the left and right drive wheels 16 via the propeller shaft 10, the differential device 12, and the drive shaft 14.
The motor 4 is connected to a high voltage battery 18 mounted on the vehicle 1 via an inverter 20 and receives a power supply from the high voltage battery 18 to generate drive torque. The high voltage battery 18 is, for example, a secondary battery such as lithium ion or nickel metal hydride, and the inverter 20 converts the DC power from the high voltage battery 18 into AC power and supplies the motor 4 with power. On the other hand, when the vehicle is decelerated, the motor 4 functions as a generator and is regeneratively driven. That is, the motor 4 generates AC power by the driving force transmitted in reverse from the driving wheel 16, and a deceleration resistance is given to the driving wheel 16 by the regenerative torque generated by the motor 4 at this time. Then, the AC power is converted into DC power by the inverter 20 and then charged to the high voltage battery 18 so that the kinetic energy due to the rotation of the drive wheels 16 is recovered as electric energy.

In the vehicle 1 having such a configuration, only the rotating shaft of the motor 4 is mechanically connected to the drive wheels 16 via the transmission 8 when the clutch 6 is in a disconnected state. That is, only the drive torque generated by the motor 4 is transmitted to the drive wheels 16 as the drive torque of the vehicle 1.
On the other hand, when the clutch 6 is in the connected state, the output shaft of the engine 2 is mechanically connected to the transmission 8, the drive wheels 16 and the like via the rotating shaft of the motor 4. That is, when the torque generated by the motor 4 at this time is 0 and only the engine 2 is operated, only the driving torque generated by the engine 2 becomes the driving torque of the vehicle 1. If the motor 4 is also operated, the sum of the driving torque of the motor 4 and the driving torque of the engine 2 becomes the driving torque of the vehicle 1.

In the vehicle 1, an integrated ECU (electronic control unit) 30 that integrally controls the engine 2, the motor 4, the clutch 6, and the transmission 8 to perform various controls such as adjustment of torque distribution of the engine 2 and the motor 4. Is installed.
The integrated ECU 30 is communicably connected to each engine 2, the motor 4, the clutch 6, and the control unit (not shown) of the transmission 8 using a CAN (Controller Area Network).

  Further, the engine 2 is transmitted with a driving force of the engine 2 via a belt (not shown) and rotated to generate an alternator 32 that generates electric power, a starter 34 that performs cranking for starting the engine via a gear, and the engine 2. A crank angle sensor 36 for detecting the crank angle, an alternator 32, a low voltage battery 40 connected to the starter 34, and the like are provided. The alternator 32 can charge the generated power to the high voltage battery 18, and the starter 34 cranks the engine 2 by supplying power from the low voltage battery 40.

  In the present embodiment, the alternator 32 and the starter 34 are connected to the low voltage battery 40, but may be connected to the high voltage battery 18. In that case, a DC / DC converter for stepping up and stepping down the voltage is provided between the alternator 32 and the starter 34 and the high voltage battery 18 to convert the voltage supplied from each.

Further, the vehicle 1 is provided with a shift position sensor 38 that detects a shift position selected by the driver. As the shift position, there are a P range selected when parking, an N range where the gear of the transmission 8 is neutral, a D range selected when traveling, and the like.
The integrated ECU 30 is connected to the alternator 32, starter 34, crank angle sensor 36, and shift position sensor 38 via various control units or directly using CAN or the like. The integrated ECU 30 controls power generation by the alternator 32 so that a predetermined power generation current is generated in the alternator 32, and controls the cranking by the starter 34 by supplying power from the low voltage battery 40 to the starter 34.

Further, the integrated ECU 30 acquires crank angle information detected by the crank angle sensor 36, and calculates the engine speed based on the crank angle information.
Further, the integrated ECU 30 acquires the shift position information detected by the shift position sensor 38, the connection / disconnection information of the clutch 6 from the clutch 6, the SOC (charge amount) information of the high-voltage battery 18, and the like. The clutch 6 is connected / disconnected, the torque distribution of the engine 2 and the motor 4 is selected, and the gear position of the transmission 8 is selected according to the driving state.

  Then, the integrated ECU 30 in this embodiment performs so-called engine automatic stop control (idle stop) that stops fuel supply to the engine 2 when a predetermined engine automatic stop condition is satisfied (engine fuel supply stop control). means). Further, the integrated ECU 30 automatically starts the engine 2 by cranking the engine 2 and restarting the fuel supply when a predetermined engine automatic start condition is satisfied after the engine 2 is automatically stopped. Engine automatic start control (auto start) is performed (engine automatic start control means). Thus, the integrated ECU 30 performs so-called engine automatic stop / start (idle stop / auto start) control.

  Here, for example, the predetermined engine automatic stop condition requires that the vehicle speed is substantially zero, the brake pedal is depressed, and the accelerator pedal is not depressed. Further, when the shift position is a non-traveling range of the P range or the N range, the state where the clutch 6 is connected has elapsed for a predetermined time, and when the shift position is a traveling range such as the D range, the clutch 6 It is a requirement that the disconnected state elapses for a predetermined time.

On the other hand, the predetermined engine automatic start condition is, for example, a state in which the engine automatic stop condition is not satisfied, that is, a case where the depression of the brake pedal is released or the accelerator pedal is depressed regardless of the shift position.
In the vehicle 1, it is possible to use the starter 34 for cranking the engine 2 when the clutch 6 is in the disconnected state, and use the starter 34 or the motor 4 when the clutch 6 is in the connected state. .

Further, in the engine automatic stop control, the integrated ECU 30 performs engine rotation stop control for stopping the rotation of the engine 2 at a predetermined stop crank angle suitable for starting the engine 2 (engine rotation stop control means).
Specifically, engine automatic stop / start control performed by the integrated ECU 30 will be described below.

Referring to FIG. 2, there is shown a flowchart showing an engine automatic stop control routine executed by the integrated ECU 30, which will be described below with reference to the flowchart.
First, as step S1, the integrated ECU 30 determines whether or not the above-described engine automatic stop condition is satisfied. If the determination result is false (No), the routine is returned. On the other hand, if the determination result is true (Yes), the process proceeds to the next step S2 in order to perform engine automatic stop control.

As step S <b> 2, the integrated ECU 30 stops the fuel supply to the engine 2.
In subsequent step S3, the integrated ECU 30 acquires the SOC information from the high voltage battery 18, and determines whether or not the acquired SOC information is greater than a predetermined stop SOC (predetermined charge amount at stop). To do. The predetermined stop-time SOC is set to a minimum SOC (for example, 50%) at which the engine 2 can be stably cranked by the motor 4 after the automatic stop.

When the determination result is false (No), that is, when the SOC is equal to or less than the predetermined stop-time SOC, the process proceeds to step S4.
In step S3, the integrated ECU 30 executes engine rotation stop control, which will be described later, and ends the routine.
On the other hand, if the determination result in step S3 is true (Yes), that is, if the SOC is greater than the predetermined stop-time SOC, the process proceeds to step S5.

In step S5, the integrated ECU 30 prohibits engine rotation stop control and ends the routine. That is, when the SOC is relatively high, the integrated ECU 30 does not execute the engine rotation stop control and naturally stops the rotation of the engine 2.
Here, the engine rotation stop control in step S4 will be described in detail.

Referring to FIG. 3, there is shown a flowchart showing an engine rotation stop control routine performed by the integrated ECU 30, which will be described below based on the flowchart.
First, as step S <b> 10, the integrated ECU 30 acquires crank angle information detected by the crank angle sensor 36.
In step S11, the integrated ECU 30 calculates the engine speed based on the crank angle information, and determines whether or not the engine speed is less than a predetermined speed. The predetermined rotation speed is set to a rotation speed (for example, 10 to 20 rpm) at which the engine rotation can be quickly stopped by the power generation load of the alternator 32 or the regenerative torque of the motor 4, for example. If the determination result is false (No), the process returns to step S10, the crank angle information is acquired again, and the determination of step S11 is repeated. On the other hand, if the determination result is true (Yes), the process proceeds to the next step S12.

In step S12, the integrated ECU 30 stops the engine rotation at a predetermined stop crank angle suitable for starting.
Here, as means for stopping the engine rotation, when the shift position is in the travel range and the clutch 6 is disengaged, the shift position is in the non-travel range and the clutch 6 is connected due to the load accompanying the power generation of the alternator 32. In the case where the motor 2 is regenerated, the rotation of the engine 2 is stopped at a predetermined stop crank angle by applying a force in the direction of stopping the rotation of the engine 2 (retard side) by the regenerative torque of the motor 4.

  More specifically, in the case where the alternator 32 is used, the integrated ECU 30 instructs the alternator 32 to generate power, and the alternator 32 generates power in accordance with the instruction so as to apply a load to the engine 2 and set a predetermined stop crank. The rotation of the engine 2 is stopped at an angle. On the other hand, when using the motor 4, the integrated ECU 30 instructs the motor 4 to generate regenerative torque, and the motor 4 generates regenerative torque in accordance with the instruction so that the engine 2 is loaded and predetermined. The rotation of the engine 2 is stopped at the stopped crank angle.

  The predetermined stop crank angle is set to a crank angle corresponding to a piston position at which the load required for cranking by the starter 34 is minimized in any cylinder of the engine 2, for example. Specifically, as the stop crank angle suitable for cranking by the starter 34, it is preferable that the crank angle at which the piston position is near the bottom dead center in the cylinder in the late intake stroke or the early compression stroke is set as the stop crank angle.

In step S12, the integrated ECU 30 stops the rotation of the engine 2 and then ends the control routine.
Next, the engine automatic start control executed by the integrated ECU 30 after the above-described engine automatic stop control will be described in detail.
Referring to FIG. 4, there is shown a flowchart showing an engine rotation stop control routine performed by the integrated ECU 30, which will be described below based on the flowchart.

In step S20, the integrated ECU 30 determines whether or not the engine automatic start condition described above is satisfied. If the determination result is false (No), the routine is returned. On the other hand, when the determination result is true (Yes), the process proceeds to the next step S21 in order to perform engine automatic start control.
As step S21, the integrated ECU 30 acquires the SOC information from the high voltage battery 18, and determines whether or not the acquired SOC information is larger than a predetermined start-up SOC (predetermined start-up charge amount). . The predetermined start-up SOC is set to a minimum SOC at which the engine 4 can stably perform cranking of the engine 2. The predetermined starting SOC is the same value (for example, 50%) as the predetermined stopping SOC, or is lower than the predetermined stopping SOC.

If the determination result is false (No), that is, if the SOC is equal to or lower than the predetermined start-up SOC, the process proceeds to step S22.
In step S22, the integrated ECU 30 places the clutch 6 in a disconnected state. At this time, if the clutch 6 is already in the disconnected state, the disconnected state is maintained.

In step S23, the integrated ECU 30 cranks the engine 2 with the starter 34, starts the fuel supply by starting the fuel supply, and ends the routine.
On the other hand, if the determination result in step S21 is true (Yes), that is, if the SOC is greater than the predetermined starting SOC, the process proceeds to step S24.

In step S24, the integrated ECU 30 places the clutch 6 in a disconnected state. At this time, if the clutch 6 is already in the disconnected state, the disconnected state is maintained.
In step S24, the integrated ECU 30 cranks the engine 2 by the motor 4, starts the fuel supply by starting the fuel supply, and ends the routine. The cranking by the motor 4 is performed by transmitting the driving torque of the motor 4 to the engine 2 via the connected clutch 6.

As described above, the integrated ECU 30 uses the starter 34 during the engine automatic stop control so that the starter 34 may be used at the start when the SOC of the high voltage battery 18 is relatively low in the automatic stop control of the engine 2. The rotation of the engine 2 is stopped at a crank angle suitable for cranking.
As a result, during the automatic start control of the engine 2, the SOC of the high voltage battery 18 is lower than the predetermined SOC at the start, and when performing cranking by the starter 34, the piston position of the engine 2 is cranked by the starter 34. Therefore, the starter 34 can start the engine quickly, and the load on the starter 34 can be reduced.

Further, when cranking by the starter 34, the clutch 6 is disengaged, thereby eliminating the mass load of the motor 4 required for starting the engine 2 and further reducing the load applied to the starter 34 during starting. Can do.
On the other hand, the integrated ECU 30 can reduce the frequency of use of the alternator 32 by prohibiting the engine rotation stop control when the SOC is higher than the predetermined stop SOC when the engine 2 is automatically stopped.

  Further, in the cranking using the motor 4 as the driving source, the influence on the startability with respect to the piston stop position of the engine 2 is lower than the cranking by the starter 34. Therefore, when the engine 2 is automatically started, the SOC of the battery is reduced. When the engine 2 is relatively high, the start frequency of the starter 34 can be reduced while suppressing a decrease in startability of the engine 2 by connecting the clutch 6 and starting the engine 2 with the motor 4.

As described above, by using the motor 4 together with the alternator 32 and the starter 34 to perform the automatic stop / start control, it is possible to average the usage opportunities of the devices. Thereby, the startability of the engine 2 can be ensured while suppressing a decrease in product life of the alternator 32 and the starter 34.
Although the description of the embodiment of the control apparatus for a hybrid electric vehicle according to the present invention is finished above, the embodiment is not limited to the above embodiment.

  In the above embodiment, the vehicle 1 is a hybrid electric vehicle in which the clutch 6 is provided between the engine 2 and the motor 4, but the vehicle to which the present invention can be applied is not limited to the hybrid electric vehicle having the configuration. Absent. For example, the present invention is also applicable to a hybrid electric vehicle in which an engine and a motor are always connected and a clutch is provided between the motor and a transmission.

  Further, the predetermined engine automatic stop condition and engine automatic start condition in the above embodiment are not limited to those described above, and may be other conditions.

1 vehicle 2 engine 4 motor 6 clutch (clutch means)
30 integrated ECU (engine fuel supply stop control means, engine rotation stop control means, engine automatic start control means)
32 Alternator 34 Starter 36 Crank angle sensor 38 Shift position sensor

Claims (3)

A control device for a hybrid electric vehicle capable of selecting an engine and a motor as a drive source,
An alternator that generates electric power using the driving force of the engine;
A starter provided in the engine for cranking the engine;
Engine fuel supply stop control means for stopping fuel supply to the engine when a predetermined engine automatic stop condition is satisfied;
When the predetermined engine automatic stop condition is satisfied,
When the charge amount of the battery that supplies power to the motor is equal to or less than a predetermined charge amount at the time of stop, the motor or the alternator stops the rotation of the engine at a predetermined stop crank angle suitable for cranking by the starter. Execute engine rotation stop control
When the charge amount of the battery that supplies power to the motor is larger than the predetermined stop-time charge amount, engine rotation stop control means that does not execute the engine rotation stop control;
A control apparatus for a hybrid electric vehicle, comprising: Clutch means provided between the engine and the motor, for connecting and disconnecting the driving force of the engine transmitted from the engine to the driving wheels via the motor;
When the predetermined engine automatic start condition is satisfied after the engine has stopped rotating, if the charge amount of the battery that supplies power to the motor is larger than the predetermined start-up charge amount, the clutch means is connected. As a state, an engine automatic start control means for cranking the engine by the torque generated by the motor;
The control apparatus for a hybrid electric vehicle according to claim 1, comprising: Clutch means provided between the engine and the motor, for connecting and disconnecting the driving force of the engine transmitted from the engine to the driving wheels via the motor;
When the predetermined engine automatic start condition is satisfied after the engine has stopped rotating, if the charge amount of the battery that supplies power to the motor is equal to or less than the predetermined start-time charge amount, the clutch means is disengaged As an engine automatic start control means for cranking the engine by the starter,
The control apparatus for a hybrid electric vehicle according to claim 1, further comprising:

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