Glow plug energization control apparatus and method

Abstract

There is provided an energization control apparatus for a glow plug in an engine, including a post-start glow section to control energization of a resistance heater of the glow plug by a battery after start of the engine. The post-start glow section is configured to evaluate revolution stability of the engine and control the energization of the resistance heater according to a first control pattern when the engine revolution stability is higher than or equal to a threshold level and according to a second control pattern that achieves a higher temperature of the sheath heater than the first control pattern when the engine revolution stability is lower than the threshold level.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a glow plug energization control system equipped with a glow plug energization control apparatus according to one embodiment of the present invention.

FIG. 2 is a section view of a glow plug controllable by the glow plug energization control system according to one embodiment of the present invention.

FIG. 3 is a schematic view showing how the glow plug is mounted on an engine cylinder block.

FIG. 4 is a flowchart for a main energization control routine of the glow plug energization control apparatus according to one embodiment of the present invention.

FIG. 5 is a flowchart for a start signal input processing subroutine of the glow plug energization control apparatus according to one embodiment of the present invention.

FIGS. 6 and 7 are flowcharts for duty ratio calculation subroutines of the glow plug energization control apparatus according to one embodiment of the present invention.

FIG. 8 is a flowchart for a standard deviation calculation subroutine of the glow plug energization control apparatus according to one embodiment of the present invention.

FIG. 9 is a flowchart for a cranking glow control subroutine of the glow plug energization control apparatus according to one embodiment of the present invention.

FIG. 10 is a flowchart for a high-temperature post-start glow control subroutine of the glow plug energization control apparatus according to one embodiment of the present invention.

FIG. 11 is a flowchart for a low-temperature post-start glow control subroutine of the glow plug energization control apparatus according to one embodiment of the present invention.

FIG. 12 is a flowchart for a pre-glow control subroutine of the glow plug energization control apparatus according to one embodiment of the present invention.

FIG. 13 is a flowchart for an upkeep glow control subroutine of the glow plug energization control apparatus according to one embodiment of the present invention.

FIGS. 14A, 14B and 14C are graphs showing changes in resistance heater temperature, engine speed and engine speed standard deviation under glow plug energization control according to one embodiment of the present invention and according to the earlier technology.

Claims

1. An energization control apparatus for a glow plug in an engine, comprising: a post-start glow section to control energization of a resistance heater of the glow plug by a battery after start of the engine, wherein the post-start glow section is configured to:evaluate revolution stability of the engine; andcontrol the energization of the resistance heater according to a first control pattern when the engine revolution stability is higher than or equal to a threshold level and according to a second control pattern that achieves a higher temperature of the sheath heater than the first control pattern when the engine revolution stability is lower than the threshold level.

2. The energization control apparatus as recited in claim 1, wherein the post-start glow section is configured to communicate with the external device, retrieve information relating to a revolution number of the engine from the external device and evaluate the engine revolution stability based on the retrieved information.

3. The energization control apparatus as recited in claim 2, wherein the post-start glow section is configured to calculate a moving standard deviation of the engine revolution number from the retrieved information and determine that the engine revolution stability is lower than the threshold level when the calculated moving standard deviation is larger than a threshold value.

4. The energization control apparatus as recited in claim 1, wherein the post-start glow section is configured to control the energization of the resistance heater according to the first control pattern in such a manner as to adjust the temperature of the resistance heater to a first target post-start glow temperature.

5. The energization control apparatus as recited in claim 4, wherein the post-start glow section is configured to calculate a first duty ratio of a voltage waveform applied to the glow plug based on a resistance value of the resistance heater and perform PWM control on the energization of the resistance heater with the calculated first duty ratio so as to adjust the temperature of the resistance heater to the first target post-start glow temperature.

6. The energization control apparatus as recited in claim 4, wherein the post-start glow section is configured to control the energization of the resistance heater according to the second control pattern in such a manner as to adjust the temperature of the resistance heater to a second target post-start glow temperature higher than the first target post-start glow temperature.

7. The energization control apparatus as recited in claim 6, wherein the post-start glow section is configured to calculate a second duty ratio of the voltage waveform applied to the glow plug based on the resistance value of the resistance heater and perform PWM control on the energization of the resistance heater with the calculated second duty ratio so as to adjust the temperature of the resistance heater to the second target post-start glow temperature.

8. An energization control apparatus for a glow plug in an engine, comprising: judging means for judging start of the engine;evaluating means for evaluating revolution stability of the engine;low-temperature post-start glow means for controlling energization of a resistance heater of the glow plug so as to attain a first target post-start glow temperature when the engine revolution stability is higher than or equal to a threshold level after the start of the engine; andhigh-temperature post-start glow means for controlling the energization of the resistance heater of the glow plug so as to attain a second target post-start glow temperature higher than the first target post-start glow temperature when the engine revolution stability is lower than the threshold level after the start of the engine.

9. An energization control method for a glow plug in an engine, comprising: judging start of the engine;evaluating revolution stability of the engine;controlling energization of a resistance heater of the glow plug so as to attain a first target post-start glow temperature when the engine revolution stability is higher than or equal to a threshold level after the start of the engine; andcontrolling the energization of the resistance heater of the glow plug so as to attain a second target post-start glow temperature higher than the first target post-start glow temperature when the engine revolution stability is lower than the threshold level after the start of the engine.