JP2013180696A - Control device for hybrid electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a hybrid electric vehicle capable of reliably performing engine starting in any situations, while securing durability of a starter by selecting a proper starting method according to a state of a motor when an engine is started.SOLUTION: When a start request for an engine is made during vehicle travel with the engine being stopped, if a motor 4 is not in a usable state (No in S1) or in a use limited state (No in S2), or if motor usable torque falls short of a threshold required for starting the engine (No in S3), push-starting determination is performed (S5). If push-starting is possible, the engine is started (S7), and if push-starting is impossible, the engine is started by a starter (S6).

Description

  The present invention relates to a control apparatus for a hybrid electric vehicle including an engine and a motor as drive sources, and more particularly to engine start control for starting an engine while the vehicle is running while the engine is stopped.

In recent years, hybrid electric vehicles including an engine and a motor as drive sources have been developed for the purpose of improving fuel consumption and exhaust gas performance.
For example, there is a hybrid electric vehicle in which a clutch is provided between an engine and a motor, and a drive source can be switched by connecting / disconnecting the clutch. In such a hybrid electric vehicle, it is possible to run with only the motor by stopping the engine and disengaging the clutch. When the required driving torque cannot be achieved only by the driving torque of the motor, the driving torque combining the engine and the motor can be used by starting the engine and connecting the clutch.

  In the hybrid electric vehicle, as a method of starting the engine while the vehicle is running, a method of starting the engine by connecting a clutch and starting up the rotation of the engine by the driving torque of the motor has been developed (see Patent Document 1). .

JP 2004-17919 A

However, in a hybrid electric vehicle, when starting a stopped engine, the motor drive torque cannot always be exhibited normally.
For example, when the use of the motor is completely impossible due to a failure or the like, or when the storage amount of the battery that supplies power to the motor (hereinafter referred to as SOC: State Of Charge) is low and the usable torque of the motor is limited Therefore, it is not possible to start the engine by the driving torque of the motor as in Patent Document 1.

On the other hand, if the starter is started using the starter every time the engine is started, the starter is frequently used, and there is a problem that the product life of the starter is shortened.
The present invention has been made to solve such problems, and the object of the present invention is to select an appropriate starting method according to the state of the motor when starting the engine and to ensure the durability of the starter. However, an object of the present invention is to provide a control apparatus for a hybrid electric vehicle that can reliably start the engine.

  In order to achieve the above object, the hybrid electric vehicle control device according to claim 1 is a control device for a hybrid electric vehicle having an engine and a motor as drive sources, and is provided between the engine and the motor. A clutch for connecting and disconnecting the driving force of the engine transmitted from the engine to the driving wheel via the motor, motor state detecting means for detecting the state of the motor, and in the engine stopped state When the engine is requested to start while the vehicle is running, if the motor state detecting means detects that the motor is in a normal state, the motor is started by the motor, and the motor state is detected. If it is detected that the engine cannot be started by the motor, the clutch is connected. Is characterized in that it comprises a, an engine start control means for starting the engine by stormed started by the rotational driving force from the driving wheel side.

In a control apparatus for a hybrid electric vehicle according to a second aspect, in the first aspect, the motor state detection means detects a state where the motor cannot be driven as a state where the engine cannot be started by the motor. It is a feature.
In the hybrid electric vehicle control device according to claim 3, in claim 2, the motor state detection means indicates a state in which a drive torque that can be generated by the motor is limited, and a state in which the engine cannot be started by the motor. It is characterized by detecting as.

According to a fourth aspect of the present invention, there is provided the hybrid electric vehicle control apparatus according to any one of the first to third aspects. This state is detected as a state in which the engine cannot be started by the motor.
According to a fifth aspect of the present invention, there is provided a control apparatus for a hybrid electric vehicle according to any one of the first to fourth aspects, further comprising a transmission having a plurality of shift stages between the motor and the drive wheel, wherein the engine start control means includes: The pushing start is performed only when a pushing start condition that is determined based on at least one of the rotation speed on the output side of the clutch and the gear position of the transmission is satisfied, and when the pushing start condition is not satisfied, the starter To start the engine.

  In the control apparatus for a hybrid electric vehicle according to a sixth aspect, in the fifth aspect, the pushing start condition is an operation region in which the torque shock at the time of the clutch connection is in a predetermined range and the torque required for the pushing start can be achieved. It is characterized by that.

According to the control apparatus for a hybrid electric vehicle according to claims 1 to 4 of the present invention using the above means, when the motor is in a normal state, the engine can be started by the motor, so that a quiet engine start can be performed. .
On the other hand, an engine driven by a motor that cannot drive the motor, is limited in the drive torque that can be generated by the motor, or cannot generate the drive torque required to start the engine. If the engine cannot be started, the engine is not started by the motor, and the engine is started by pushing the rotary drive force from the drive wheel side by connecting the clutch without connecting the clutch.

In this way, when the engine is started, a smooth start can be performed while preventing an increase in the use frequency of the starter by performing a pushing start using the force that the vehicle is traveling without using the starter. it can.
According to the control apparatus for a hybrid electric vehicle of claim 5, the pushing start is performed only when the pushing start condition based on at least one of the rotational speed on the output side of the clutch and the shift stage of the transmission is satisfied, and the condition is satisfied. If not, start the engine using a starter.

Thus, the engine start according to the driving | running state can be performed by using properly pushing start and starter start. As a result, it is possible to reliably start the engine while suppressing the use frequency of the starter as much as possible.
According to the hybrid electric vehicle control apparatus of the sixth aspect, the pushing start condition is set to an operation region in which the torque shock at the time of clutch engagement is within a predetermined range and the torque required for pushing start can be achieved.

  By setting the pushing start condition to such a condition, a reliable pushing start can be performed and a torque shock accompanying the pushing start can be suppressed.

It is a schematic block diagram of the control apparatus of the hybrid electric vehicle in one Embodiment of this invention. It is a flowchart which shows the engine starting control routine which ECU of the control apparatus of the hybrid electric vehicle which concerns on one Embodiment of this invention performs. It is a map for pushing start determination by ECU of the control apparatus of the hybrid electric vehicle which concerns on one Embodiment of this invention.

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 a prime mover that is generally used in automobiles such as a diesel engine and a gasoline engine, and the type thereof is not particularly limited here. The engine 2 is provided with a starter 2a for starting the engine 2. The starter 2a is driven by power supply from an auxiliary battery (not shown), and starts the engine 2 by cranking the engine 2 through a gear.

A clutch 6 is provided between the engine 2 and the motor 4, the output shaft of the engine 2 is on the input shaft (input side) of the clutch 6, and the motor is on the output shaft (output side) of the clutch 6. The four rotation shafts are connected to each other.
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 transmission 8 includes a plurality of gears, shifts the driving force input through the gears corresponding to the selected shift speed, and transmits them to the output 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 battery 18 mounted on the vehicle 1 via an inverter 20, and receives torque from the battery 18 to generate torque. The battery 18 is a secondary battery such as lithium ion or nickel metal hydride, and the inverter 20 converts the DC power from the 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 wheels 16, and the regenerative torque generated by the motor 4 at this time acts as a braking torque for the driving wheels 16 and functions as a so-called regenerative brake. . The AC power is converted into DC power by the inverter 20 and then charged to the 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 the disconnected state. That is, only the torque generated by the motor 4 (hereinafter referred to as motor torque) is transmitted to the drive wheels 16 as the drive torque or braking 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, at this time, when the motor torque is set to 0 and only the engine 2 is operated, only the torque generated by the engine 2 (hereinafter referred to as engine torque) becomes the driving torque or braking torque of the vehicle 1. If the motor 4 is also operated, the sum of the motor torque and the engine torque becomes the driving torque or braking torque of the vehicle 1.

The vehicle 1 is equipped with an ECU (Electronic Control Unit) 22 that integrally controls the engine 2, the motor 4, the clutch 6, and the transmission 8 in order to adjust the distribution of the motor torque and the engine torque. Has been.
The ECU 22 is communicably connected to a control unit (not shown) of each engine 2, motor 4, clutch 6, and transmission 8 using a CAN (Controller Area Network) or the like.

For example, the ECU 22 acquires various information such as engine speed information from the engine 2, motor speed information and motor torque information from the motor 4, currently selected gear stage information from the transmission 8, and SOC information from the battery 18. .
Moreover, ECU22 detects the state of the motor 4 based on the acquired various information (motor state detection means). The state of the motor 4 can be generated by the motor 4 because of a failure of the motor 4 itself, or the temperature of the motor 4 is in a very low temperature state, or the SOC of the battery 18 is below the lower limit value required for driving the motor. The drive torque that can be generated by the motor 4 when the drive torque is 0 (hereinafter referred to as the unusable state), the motor 4 can be used, but the SOC of the battery 18 is relatively low, etc. There are states that are restricted (hereinafter referred to as “use restricted states”), states that are not restricted, but that the drive torque that can be generated by the motor 4 is less than or equal to the threshold value of the drive torque necessary for starting the engine 2, and the like. Then, the ECU 22 detects that the motor 4 is in a normal state, that is, neither in a motor unusable state nor in a motor use restricted state and capable of generating a driving torque sufficient for starting the engine 2.

The ECU 22 configured as described above monitors the SOC of the battery 18 and the driving state of the vehicle 1, optimizes fuel consumption and exhaust gas performance, and performs an operation in accordance with the driving request of the engine 2, motor 4. Control the clutch 6, the transmission 8, etc.
For example, the ECU 22 operates when the engine 2 is stopped only when the motor 2 is stopped, when the driving torque is insufficient only by the motor torque due to acceleration of the vehicle 1 or when the motor 4 is abnormal. When there is a start request, the engine is started by an engine start method corresponding to the state of the motor 4 (engine start control means).

Hereinafter, engine start control of the vehicle 1 performed by the ECU 22 will be described in detail.
Referring now to FIG. 2, there is shown a flowchart showing an engine start control routine executed by the ECU 22, which will be described below with reference to the flowchart. In the engine start control, the ECU 22 receives a start request for the engine 2 when the engine 2 is stopped and the clutch 6 is disconnected and the vehicle 1 is driven only by the motor 4. When executed.

First, as step S1, the ECU 22 determines whether or not the motor 4 is in a usable state. If the determination result is true (Yes), the process proceeds to the next step S2.
In step S2, the ECU 22 determines whether or not the use of the motor 4 is restricted. When the determination result is true (Yes), that is, when the use restriction is not applied to the motor 4, the process proceeds to the next step S3.

In step S <b> 3, the ECU 22 determines whether or not the torque that the motor 4 can use to start the engine 2 (hereinafter referred to as “motor usable torque”) is greater than the threshold value of the driving torque that is required to start the engine 2. Determine. If the determination result is true (Yes), the process proceeds to step S4.
In step S4, since the motor 4 is in a normal state based on the determination results in steps S1 to S3, the ECU 22 starts the engine 2 with the motor 4 and ends the routine. Specifically, the engine start by the motor 4 causes the transmission torque of the motor 4 to be transmitted to the engine 2 by setting the transmission 8 to the neutral state and connecting the clutch 6 to a so-called clutch connection state. The motor 4 increases the drive torque to such an extent that the engine 2 can be started. After the engine 2 is started, when the driving torque of the engine 2 is used for traveling, the clutch 6 is connected, and the transmission 8 also selects a gear position according to the operating state. When the driving torque of the engine 2 is not used for traveling, the clutch 6 is brought into a disconnected state.

On the other hand, if the determination result in step S1 is false (No), that is, if the drive torque that can be generated by the motor 4 is 0 due to a failure or the like, the process proceeds to step S5.
Further, if the determination result in step S2 is false (No), that is, if the drive torque that can be generated by the motor 4 is limited due to insufficient SOC or the like, the process proceeds to step S5.

Furthermore, if the determination result in step S3 is false (No), that is, if the motor usable torque has not reached the threshold value of the driving torque necessary for starting the engine, the process proceeds to step S5.
In step S5, the ECU 22 performs a pushing start determination as to whether or not a so-called pushing start is possible, in which the engine 2 is started by the rotational driving force from the drive wheel 16 side. The pushing start determination is performed based on a pushing start determination map based on the output speed of the clutch 6 and the gear position as shown in FIG.

  The solid line showing the tendency for the clutch rotational speed to increase as the shift speed increases is indicated by the upper limit of the push possible based on the torque shock when the clutch 6 is connected due to the rotational speed difference between the input side and the output side of the clutch 6 and the torque difference. Shows the line. In other words, in the operating range larger than the solid line, the rotational speed difference and the torque difference between the input side and the output side of the clutch 6 with respect to the shift stage are large, and the torque shock when the clutch 6 is connected is also large. In order not to cause discomfort to the driver and the driver, the pushing start is not executed. Note that at the time of step S4, the engine 2 is in a stopped state and the rotational speed on the input side of the clutch 6 is 0. Therefore, the rotational speed difference between the input side and the output side of the clutch 6 is substantially the output side. Is the number of revolutions. Therefore, the rotational speed difference between the input side and the output side of the clutch 6 may be obtained by detecting only the rotational speed on the output side of the clutch 6.

  On the other hand, a dotted line showing a tendency for the clutch rotational speed to decrease as the shift speed increases indicates a pushable lower limit line based on the torque required for pushing. In other words, in the operation region smaller than the dotted line, even when the clutch 6 is connected, the rotational driving force that can start the engine 2 from the drive wheel 16 side cannot be obtained, and therefore, the pushing start is not executed.

  From the above, as shown in FIG. 3, an operation region on the relatively high gear stage side and not less than a solid line and below a dotted line is a pushable region (push start condition). When the driving state of the vehicle 1 is outside the pushable area, the ECU 22 determines that the push start is impossible, and the determination result in step S5 is false (No), and the process proceeds to step S6. On the other hand, if it is within the pushable area, it is determined that the push is possible, the determination result in step S5 is true (Yes), and the process proceeds to step S7.

  In step S6, the ECU 22 starts the engine 2 by the starter 2a because it cannot be pushed and started. After the engine 2 is started by the starter 2a, the clutch 6 is kept connected when the driving torque of the engine 2 is used for traveling, and the clutch 6 is used when the driving torque of the engine 2 is not used for traveling. And the routine is terminated.

  On the other hand, in step S <b> 7, the ECU 22 gradually connects the clutch 6 and transmits the rotational driving force from the drive wheels 16 to the engine 2 in a so-called half-clutch state. After the engine 2 is pushed and started in this way, the clutch 6 remains in the connected state when the driving torque of the engine 2 is used for traveling, and the clutch 6 is disconnected when the driving torque of the engine 2 is not used for traveling. The routine is terminated as follows.

  When the motor 4 is in a normal state and sufficient driving torque can be generated by the engine start control as described above, the engine can be started by the motor 4 to perform a quiet engine start. On the other hand, when the motor 4 is in an unusable state, is in a restricted use state, or cannot generate the driving torque required for starting the engine, the motor 4 cannot start the engine. In some cases, the engine is not started by the motor 4 but is pushed or started by the starter 2a.

When the engine 2 is started, the starter 2a is not used and the force that the vehicle 1 is traveling is used to start the engine 2 so that the starter 2a can be smoothly started while the frequency of use is prevented. it can.
As to whether or not to perform the pushing start, the operating range in which the torque difference between the input side and the output side of the clutch 6 is within a predetermined range and the torque required for pushing start can be achieved is shown in FIG. By making a determination based on the map based on the number and the shift speed, it is possible to perform a reliable pushing start and to suppress a torque shock accompanying the pushing start.

Then, the starter start is performed only when the push start is impossible, and the engine start according to the operating state can be performed by properly using the push start and the starter start in this manner. Thereby, a reliable engine start can be performed while suppressing the frequency of use of the starter 2a as much as possible.
In this manner, the control device for the hybrid electric vehicle according to the present embodiment selects an appropriate starting method according to the state of the motor 4 when starting the engine 2, and ensures the durability of the starter 2a. A reliable engine start can be performed.

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.
For example, in the above embodiment, whether or not the push start is performed in step S4 in FIG. 2 is determined using the push start determination map as shown in FIG. It is not limited to. For example, the range determined only by the clutch rotational speed or only the gear position may be determined as a range that can be pushed and started.

1 Vehicle 2 Engine 2a Starter 4 Motor 6 Clutch 8 Transmission 16 Drive Wheel 18 Battery 22 ECU (Motor State Detection Means, Engine Start Control Means)

Claims (6)

A control device for a hybrid electric vehicle having an engine and a motor as drive sources,
A clutch which is provided between the engine and the motor and which connects and disconnects the driving force of the engine transmitted from the engine to the driving wheels via the motor;
Motor state detecting means for detecting the state of the motor;
When the engine is requested to start while the vehicle is running in the engine stopped state, the motor is started by the motor when the motor state detecting means detects that the motor is in a normal state. When the motor state detecting means detects that the engine cannot be started by the motor, the clutch is connected, and the engine is started by pushing by the rotational driving force from the drive wheel side. Engine start control means for starting;
A control apparatus for a hybrid electric vehicle, comprising:   2. The control apparatus for a hybrid electric vehicle according to claim 1, wherein the motor state detecting means detects a state where the motor cannot be driven as a state where the engine cannot be started by the motor.   3. The hybrid electric system according to claim 1, wherein the motor state detection unit detects a state where a drive torque that can be generated by the motor is limited as a state in which the engine cannot be started by the motor. 4. Automotive control device.   The motor state detection means detects a state where the drive torque that can be generated by the motor is equal to or less than a threshold value of the drive torque necessary for starting the engine as a state in which the engine cannot be started by the motor. The control apparatus for a hybrid electric vehicle according to any one of claims 1 to 3. A transmission having a plurality of shift stages between the motor and the drive wheel;
The engine start control means performs the push start only when the push start condition that is determined based on at least one of the rotation speed on the output side of the clutch and the shift speed of the transmission is satisfied, and the push start condition is satisfied. 5. The control apparatus for a hybrid electric vehicle according to claim 1, wherein if there is not, the engine is started by a starter.   6. The control apparatus for a hybrid electric vehicle according to claim 5, wherein the pushing start condition is an operating range in which a torque shock at the time of clutch engagement is within a predetermined range and a torque required for the pushing start can be achieved.

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