Internal combustion engine start controller

Abstract

An internal combustion engine start controller in a vehicle that includes: a power source; an internal combustion engine that is started by using electric power supplied from the power source; a first motor; and a first electric power converter that is constructed so as to be able to perform electric power conversion between the power source and the first motor through switching control of power semiconductor elements is provided. The start controller includes: a start detecting device for detecting whether the engine is in a starting operation; and a first frequency setting device that, when the engine is in a starting operation, sets a switching frequency of the first electric power converter to a frequency lower than that used when the engine is not in a starting operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The features, advantages thereof, and technical and industrial significance of this invention will be better understood by reading the following detailed description of preferred embodiments of the invention, when considered in connection with the accompanying drawings, in which:

FIG. 1 is a block diagram for explaining a configuration of a hybrid vehicle shown as an example of a vehicle in which an internal combustion engine start controller according to an embodiment of the present invention is installed;

FIG. 2 is a control block diagram for explaining a motor control system in the hybrid vehicle shown in FIG. 1;

FIG. 3 is a waveform diagram for explaining pulse width modulation (PWM) control performed by a PWM signal generation section shown in FIG. 2;

FIG. 4 is a flow chart for explaining an engine start control according to the embodiment of the present invention;

FIG. 5 is a block diagram showing a first example of a system for changing a carrier frequency;

FIG. 6 is a block diagram showing a second example of a system for changing a carrier frequency;

FIG. 7 is a diagram for explaining an example of control in which the carrier frequency of an inverter is variably set in accordance with the temperature of a power source; and

FIG. 8 is a block diagram showing an engine starting system of an automobile provided with an economy running system, according to a modified example of the embodiment of the present invention.

Claims

1. An internal combustion engine start controller in a vehicle that includes: a power source; an internal combustion engine that is started by using electric power supplied from the power source; a first motor; and a first electric power converter that is constructed so as to be able to perform electric power conversion between the power source and the first motor through switching control of power semiconductor elements, the controller comprising: a start detecting device for detecting whether the engine is in a starting operation; anda first frequency setting device that, when the engine is in a starting operation, sets a switching frequency of the first electric power converter to a frequency lower than that used when the engine is not in a starting operation.

2. The internal combustion engine start controller according to claim 1, wherein the first motor is configured so as to be able to produce power for starting the engine when the engine is in a starting operation, and so as to have an operating period of time other than when the engine is in a starting operation.

3. The internal combustion engine start controller according to claim 2, wherein the first motor is configured so as to be able to generate electricity by using a rotational force produced by the engine when the engine is in operation, andthe first electric power converter is controlled so as to convert electric power generated by the first motor to electric power with which it is possible to charge the power source.

4. The internal combustion engine start controller according to claim 3, further comprising: a low temperature detector for detecting a low temperature state of the power source based on a detected temperature of the power source, wherein,even when the engine is in a starting operation, if the low temperature state of the power source is not detected by the low temperature detector, the first frequency setting device sets the switching frequency of the first electric power converter to substantially the same frequency as that used when the engine is not in a starting operation.

5. The internal combustion engine start controller according to claim 4, wherein, when the engine is in a starting operation, if the low temperature state of the power source is detected by the low temperature detector, the first frequency setting device sets the switching frequency of the first electric power converter to a frequency lower than that used when the engine is not in a starting operation, according to the detected temperature of the power source.

6. The internal combustion engine start controller according to claim 1, further comprising: a low temperature detector for detecting a low temperature state of the power source based on a detected temperature of the power source, wherein,even when the engine is in a starting operation, if the low temperature state of the power source is not detected by the low temperature detector, the first frequency setting device sets the switching frequency of the first electric power converter to substantially the same frequency as that used when the engine is not in a starting operation.

7. The internal combustion engine start controller according to claim 1, wherein the vehicle further includes:a second motor that is driven by using the electric power supplied from the power source and is connected to a drive shaft that is different from a shaft to that the first motor is connected; anda second electric power converter constructed so as to be able to perform electric power conversion between the power source and the second motor through switching control of the power semiconductor elements, andthe start controller further comprises:a second frequency setting device that, when the engine is in a starting operation, sets a switching frequency of the second electric power converter to a frequency lower than that used when the engine is not in a starting operation.

8. The internal combustion engine start controller according to claim 7, further comprising: a low temperature detector for detecting a low temperature state of the power source based on a detected temperature of the power source, wherein,even when the engine is in a starting operation, if the low temperature state of the power source is not detected by the low temperature detector, the first and second frequency setting devices respectively set the switching frequency of the first electric power converter and the switching frequency of the second electric power converter to substantially the same frequencies as those used when the engine is not in a starting operation.

9. The internal combustion engine start controller according to claim 8, wherein, when the engine is in a starting operation, if the low temperature state of the power source is detected by the low temperature detector, the first and second frequency setting devices determine whether to set the switching frequency of the first electric power converter and the switching frequency of the second electric power converter, respectively, to frequencies lower than those used when the engine is not in a starting operation, based on the detected temperature of the power source.

10. The internal combustion engine start controller according to claim 7, wherein power output from the second motor is transmitted to the drive shaft of the vehicle.

11. The internal combustion engine start controller according to claim 10, further comprising: a low temperature detector for detecting a low temperature state of the power source based on a detected temperature of the power source, wherein,even when the engine is in a starting operation, if the low temperature state of the power source is not detected by the low temperature detector, the first and second frequency setting devices respectively set the switching frequency of the first electric power converter and the switching frequency of the second electric power converter to substantially the same frequencies as those used when the engine is not in a starting operation.

12. The internal combustion engine start controller according to claim 11, wherein when the engine is in a starting operation, if the low temperature state of the power source is detected by the low temperature detector, the first and second frequency setting devices determine whether to set the switching frequency of the first electric power converter and the switching frequency of the second electric power converter, respectively, to frequencies lower than those used when the engine is not in a starting operation, based on the detected temperature of the power source.