JP2000213440A - Starter of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a starter of internal combustion engine which is surely capable of starting of internal combustion engine even in a system using an electric motor of low torque performance. SOLUTION: This starter provided to a hybrid car comprises a transmission clutch 10 which connects or disconnects between a crankshaft 6 of engine 2 to or from an output shaft 8 of an electric motor 4, and the transmission clutch 10 is actuated by an actuator 12. In an ECU 14, rotation of the electric motor 4 is previously carried out in a state in which the transmission clutch 10 is disconnected, and the transmission clutch 10 is connected when the rotation reaches a predetermined value. Accordingly, cranking of the engine 2 is performed by using inertia torque of the electric motor 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine starting apparatus for suitably starting an internal combustion engine.

[0002]

2. Related Background Art For example, Japanese Patent No. 2672081 discloses a starter for an internal combustion engine in which a power transmission and a power source are combined. This known starting device includes a planetary gear mechanism that can be connected to the electric motor, the engine, and the transmission, respectively, and distributes the torque of the electric motor to the engine and the transmission by selectively switching the connection state of the planetary gear mechanism. Or can be entered only to the engine.

[0003]

According to the above-mentioned known starting device, for example, when the vehicle is stopped, the torque of the electric motor is supplied only to the engine, and when the vehicle is running, the torque of the electric motor is transmitted to the transmission. It is recognized that the engine can be started in any case by supplying the power to the engine while transmitting the power to the engine.

However, since the known starting device transmits the torque of the electric motor to the engine via a complicated mechanism, the electric motor is required to have an excessive torque performance. In this regard, if one focuses solely on miniaturization of the electric motor, the torque transmission mechanism can be simplified, but the electric motor can overcome its cranking resistance even when the engine is cold, for example. Therefore, there is still a certain limit to miniaturization of the electric motor because it is necessary to ensure sufficient torque performance.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an internal combustion engine that can reliably start an internal combustion engine without requiring an electric motor to have excessive torque performance. An object of the present invention is to provide a starting device for an engine.

[0006]

According to a first aspect of the present invention, there is provided a starting device for an internal combustion engine, comprising: a clutch means for connecting a crankshaft of the internal combustion engine and an output shaft of an electric motor to each other by engagement; And control means for controlling the operation of the electric motor. The control means starts the rotation of the electric motor in a state in which the engagement of the clutch means is released, and when the rotation reaches a predetermined connection rotation speed. Control to engage the clutch means.

[0007] According to the above-described starting device, a fixed inertia torque is stored in the electric motor by starting up the rotation up to the connection rotation speed. When the clutch means is engaged, the torque of the electric motor is transmitted to the crankshaft, and cranking of the internal combustion engine is started. At this time, in addition to the output torque of the electric motor, the cranking can be performed by using the above inertia torque.
The original torque performance of the electric motor can be reduced.

Further, when the rotation of the electric motor drops to a predetermined disconnection rotation speed due to the engagement of the clutch means, the control means releases the engagement of the clutch means. In this case, the rotation of the electric motor is restarted by the disengagement of the clutch means, and the inertia torque is recovered.
Thereafter, when the rotation of the electric motor reaches the above-mentioned connection rotation speed, the control means re-engages the clutch means, whereby the cranking of the internal combustion engine is performed intermittently.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the internal combustion engine starting device of the present invention is applied to, for example, a vehicle engine will be described below. Referring to FIG. 1, there is schematically shown a configuration of a drive system of a hybrid vehicle equipped with the starting device of the embodiment. Specifically, the hybrid vehicle includes an engine 2 and an electric motor 4 as its driving sources, and a crankshaft 6 of the engine 2 and an output shaft 8 of the electric motor 4 can be connected to each other via a transmission clutch 10. ing.
As shown, the transmission clutch 10 includes an actuator 12
The connection / disconnection of the actuator 12 is operated through the actuator 12, and a hydraulic drive circuit (not shown) is connected to the actuator 12, for example. The drive of the actuator 12 using the hydraulic drive circuit is controlled by an electronic control unit (ECU) 14.

The output shaft 8 of the electric motor 4 is connected to the transmission 1
The transmission 16 includes, for example, a belt-type continuously variable transmission, and its transmission pulley ratio control is performed by an ECU.
14. Further, the output shaft 1 of the transmission 16
8 is the differential gear 2 via the starting clutch 20
2 are connected. The connection and disconnection of the starting clutch 20 is operated by the actuator 24, so that the amount of torque transmitted from the output shaft 18 to the driving wheels W can be adjusted. In addition,
The drive control of the actuator 24 is also performed by the ECU 14.

As the engine 2 of the hybrid vehicle, for example, a direct injection type spark ignition gasoline engine is applied. Therefore, the fuel injection valve 26 is provided so as to be able to inject fuel directly into its combustion chamber. I have. The operations of the fuel injection valve 26 and the ignition plug 28 are controlled by the ECU 14. The electric motor 4 receives power from a battery (not shown) to generate output torque,
The power generated by the power generation can be charged into the battery, and the power transmission / reception control between them can also be performed by the ECU 14.

The rotation speeds of the engine 2 and the electric motor 4 are as follows.
The sensor signals can be detected by an engine speed sensor 30 (engine speed detecting means) and a motor speed sensor 32 (motor speed detecting means), respectively. Are supplied to the ECU 14. ECU 14
Has a built-in program related to the start of the engine 2, and can execute the start control of the engine 2 based on the start program.

Referring to FIG. 2, there is shown an engine start control routine executed by the ECU 14. The starting device according to the present embodiment can function in this starting control routine. Hereinafter, the operation of the starting device will be described with reference to this flowchart. In step S10, first, the engine 2
It is determined whether or not there is a start request for. Conditions for satisfying this start request can be set freely, for example, whether or not the driver operates a key, the amount of depression of an accelerator pedal,
When the output of the engine 2 is required based on various information such as a decrease in the state of charge of the battery, it is determined that a predetermined start request is satisfied.

If the above-described start request is satisfied, the process proceeds to step S12, and it is determined whether the vehicle is stopped. This determination can be made, for example, based on a sensor signal from a vehicle speed sensor (not shown). If the determination results in step S10 and step S12 are both true (Yes), step S14 and subsequent steps of the start control routine are executed.

In step S14, the starting clutch 20 is disengaged. Specifically, the ECU 14 controls the above-described hydraulic drive circuit to drive the actuator 24 to release the engagement of the starting clutch 20. In step S16, whether low is determined from the cutting rotational speed Nm ₀ the motor rotation speed Nm is below. Specifically, this determination can be made based on a sensor signal from the motor speed sensor 32. In this case, since the hybrid vehicle is stopped (step S12 = true), the electric motor 4 is still stopped at the first time of the control routine. Therefore, the result of the determination in step S16 is true, and the process proceeds to step S18.

In step S18, the transmission clutch 10 is disconnected. In this case, the ECU 14
Is controlled to release the engagement of the transmission clutch 10. If the transmission clutch 10 is already disconnected while the hybrid vehicle is stopped, this step S18 is performed.
Is simply executed. In step S20, the rotation of the electric motor 4 is increased. In this case, the ECU 14
Starts power supply to the electric motor 4 and actually starts the electric motor 4. Note that, as described above, the starting clutch 2
0 and the transmission clutch 10 are both disconnected,
The rotation of the electric motor 4 is not transmitted to the engine 2 or the drive wheels W.

In step S22, it is determined whether or not the motor rotation speed Nm has reached a predetermined connection rotation speed NmA.
Until the motor rotation speed Nm reaches the connection rotation speed NmA, the determination result in step S22 is false (No), and the process proceeds to step S26. In step S26,
It is determined whether or not the rotation speed Ne of the engine 2 has reached a predetermined starting rotation speed NeA. In this case, since the engine 2 is stopped and the transmission clutch 10 is disengaged (step S18), the determination result in step S26 is false, and the control routine returns without executing step S28 and subsequent steps. Is done.

Referring now to FIG. 3, there is shown a temporal change in the connection state of the transmission clutch 20 and the rotational speeds of the engine 2 and the electric motor 4 accompanying the execution of the engine start control routine described above. For example, when the above-mentioned request for starting the time t ₁ is satisfied, it is launched motor rotation speed Nm from time t ₁ as shown. Until the motor rotation speed Nm reaches the connection rotation speed NmA, the above-described step S1 is performed.
The procedure from 0 to S26 is repeated, during which the motor rotation speed Nm is continuously raised.

Thereafter, the motor rotation speed Nm is changed to the connection rotation speed N.
When the current reaches mA (time t ₂ ), the result of the determination in step S22 becomes true. In this case, step S24 is executed before step S26. When step S24 is executed, the ECU14 is engaged to the transfer clutch 10 by controlling the operation of the actuator 12, as shown in FIG. 3, the connection state of the transmission clutch 10 from the time t ₂ is gradually engaged ( ON) side.

In the relationship between the connection rotation speed NmA and the cutting rotation speed Nm ₀ , the connection rotation speed NmA is set to a larger value (NmA> Nm ₀ ). Therefore, beyond (step S16 = false) time t ₁ the motor rotation speed Nm cutting rotation speed Nm ₀ after, therefore, even if step S18 has not been bypassed, the motor rotation speed Nm connections rpm NmA
Step S24 is not executed until the time is reached.

Further, the connection control of the transmission clutch 10 described above, when the output shaft 8 and the crankshaft 6 are connected to each other, actually the engine 2 cranking from time t ₂ is started, shown in Figure 3 from the time t ₂ as the engine 2
The rotation speed Ne gradually increases. Engine 2 like this
When the engine rotation speed Ne reaches the starting rotation speed NeA by the cranking of (2), the determination result in step S26 becomes true. In this case, step S28 of the control routine is executed, and fuel injection and ignition are started.

In step S28, the ECU 14 controls the energization of the fuel injection valve 26 and the spark plug 28 to operate the fuel injection valve 26 and the spark plug 28, respectively.
Fuel injection is started at time t ₃ as shown in FIG. 3, also, the spark is also started. Next step S30
Then, it is determined whether or not the engine speed Ne has reached a predetermined speed NeB. This rotation speed NeB is the engine 2
Is set to the rotation speed level for determining the start completion (complete explosion) of the engine, and in relation to the above-described start rotation speed NeA,
This rotation speed NeB is set to a larger value (N
eA <NeB).

Therefore, while the start of the engine 2 has not been completed, the determination result in step S30 is false. In this case, the start control routine is returned, and the procedure of steps S10 to S30 is repeatedly executed. On the other hand, as the engaging force of the transfer clutch 10 gradually increases, the motor rotational speed Nm from time t ₂ as shown in FIG. 3 decreases gradually. When the motor rotation speed Nm decreases to the cutting rotation speed Nm ₀ , the above-described step S
Since the result of the determination at 16 is true, step S18 is executed in this case.

[0024] As shown in FIG. 3, the time t ₄ the motor rotation speed Nm falls to the cutting rotation speed Nm _0, the transmission clutch 10 step S18 is executed is disconnected. In this case, the ECU 14 controls the operation of the actuator 12 and immediately releases (OFF) the engagement of the transmission clutch 10 as shown in FIG. After time t ₂ , even if the motor rotation speed Nm decreases and the determination result in step S22 becomes false, and step S24 is bypassed, as described above, until step S18 is executed,
The transmission clutch 10 is not disconnected.

On the other hand, by the execution of step S20, the rotation of the electric motor 4 is pulled, the motor rotation speed Nm from time t ₄ as shown in FIG. 3 rises significantly. Thereafter, the motor rotational speed Nm reaches the connection rotation speed NMA (time t _5), the transmission clutch 10 step S24 is executed is connected as described above. In Figure 3, between times t ₅ ~ time t _7, which is repeated the same procedure as the time t ₂ ~ time t ₅ as described above, when ECU14 has the motor rotation speed Nm is decreased to cut rotational speed Nm _0, When the engagement of the transmission clutch 10 is released (time t ₆ ) and the motor rotation speed Nm reaches the connection rotation speed NmA, the transmission clutch 10 is disengaged.
Are engaged (time t ₇ ).

Thereafter, the start of the engine 2 is completed (complete explosion).
Then, when the engine speed Ne reaches the above-described speed NeB (time t ₈ ), the result of the determination in step S30 becomes true, and steps S32 and S34 are continuously executed. In this case, the ECU 14 controls the operation of the actuator 12 to disconnect the connection of the transmission clutch 10 and stops the power supply to the electric motor 4. Step S3
When S2 is executed, the ECU 14 ends the engine start control routine.

As described above, when the engine 2 is started, the rotation of the electric motor 4 is first started with the transmission clutch 10 disengaged. During this time, a certain inertia torque is stored in the electric motor 4. Can be When the transmission clutch 10 is connected, the engine 2 is cranked by using the inertia torque of the electric motor 4. Therefore, the electric motor 4 to be mounted on the hybrid vehicle does not require extremely large torque performance. In this regard, for example, even when the engine 2 is cold started, the engine 2 can be reliably started using the electric motor 4 having low torque performance.
It is also effective in preventing over specification of the vehicle.

In addition, even if the above-mentioned cranking is performed,
When the start of the gin 2 is not completed (step S30 = false)
Means that the transmission clutch 10 is once disconnected and then the electric motor
4 is started again (steps S16 to S20).
Therefore, cranking cycle until the start of the engine 2 is completed
Rolling up can be repeated. The present invention
Without being limited to the one embodiment described above,
It is feasible. In the above-described start control routine,
Continuous rotation speed NmA and cutting rotation speed Nm ₀The specific value of
Depending on the specifications of the electric motor 4, it can be changed as appropriate,
Learning is corrected to an appropriate value by repeating the execution of
It can also be configured.

In the above-described embodiment, the case where the starting of the engine 2 is completed by repeating the cranking of the engine 2 a plurality of times and inputting the torque of the electric motor 4 three times is described. The present invention is not intended to require a plurality of torque inputs. Therefore, if the start of the engine 2 is completed between times t ₃ ~ time t ₄ in the above embodiment (step S30
= True), the control routine can be ended by executing steps S32 and S34 before the determination in step S16 becomes true.

In addition, it goes without saying that the present invention is widely applicable not only to engines mounted on hybrid vehicles and automobiles but also to other starting devices for internal combustion engines.

[0031]

As described above, according to the internal combustion engine starting apparatus of the present invention (claim 1), the internal combustion engine can be efficiently started using the electric motor having low torque performance. . Further, when the rotation of the electric motor decreases during the cranking, the engagement of the clutch means is released (claim 2). Therefore, the operation is performed by restarting the rotation of the electric motor and repeating the cranking. Can be ensured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a drive system of a hybrid vehicle equipped with a starting device according to an embodiment.

FIG. 2 is a flowchart of an engine start control routine.

FIG. 3 is a time chart for explaining the operation of the starting device.

[Explanation of symbols]

 2 Engine 4 Electric motor 6 Crankshaft 8 Output shaft 10 Transmission clutch (clutch means) 12 Actuator (clutch means) 14 ECU (Control means) 26 Fuel injection valve 28 Spark plug 30 Engine speed sensor 32 Motor speed sensor

Claims (2)

[Claims] An engine speed detecting means for detecting a speed of the internal combustion engine; an electric motor for cranking the internal combustion engine; a motor speed detecting means for detecting a speed of the electric motor; Clutch means provided between the internal combustion engine and the electric motor for connecting a crankshaft of the internal combustion engine and an output shaft of the electric motor to each other by engagement; and controlling operation of the electric motor and the clutch means. Control means, wherein the control means starts the rotation of the electric motor in a state in which the clutch means is disengaged, and engages the clutch means when this rotation reaches a predetermined connection speed. A starting device for an internal combustion engine, comprising: 2. The control device according to claim 1, wherein when the rotation of the electric motor decreases to a predetermined disconnection speed by the engagement of the clutch, the engagement of the clutch is released. 3. The starting device for an internal combustion engine according to claim 1.