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Thermal resistor type air flow measuring apparatus

Imported: 24 Feb '17 | Published: 06 Jan '04

Chihiro Kobayashi, Shinya Igarashi, Masayuki Kozawa, Atsushi Kanke

USPTO - Utility Patents

Abstract

To correct properly the error of the thermal resistor type air flow measuring apparatus caused by the pulsation in the intake pipe in detecting the air flow of the internal combustion engine, a thermal resistor is placed in a passage inside the auxiliary air passage into which the reverse flow hardly flows directly and the error caused by the reverse flow is prevented. The existence of the reverse flow is judged by the ratio of the amplitude to the mean value using the maximum value, the minimum value and the mean value of the forward air flow waveform, and the error caused by the increase of the forward air flow is corrected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the schematic structure of the present invention.

FIG. 2 is a graph figured with the maximum value and the minimum value detected by the thermal resistor in the bend route and with combined values with those extremal values.

FIG. 3 is a graph showing a relation between the pulsation amplitude divided by the mean value and the detection error.

FIG. 4 is a graph showing waveforms before and after the correction so that the pulsation amplitude may be reduced while the minimum value is fixed as one example of the correcting method of the present invention.

FIG. 5 is a graph showing an intake air signal vs. air flow signal relation before and after the correction, showing an effect of the present invention.

FIG. 6 is a frequency characteristic of the thermal resistor.

FIG. 7 is a characteristic graph showing a comparison of the correction operations using the linear approximation and the square/linear approximation with respect to the correction coefficient.

FIG. 8 is a waveform in case that the thermal resistor is placed in the main air passage.

FIG. 9 is a characteristic graph figured with the maximum value and the minimum value detected by the thermal resistor in the main air passage and with combined values with those extremal values.

FIG. 10 is a block diagram showing a schematic structure in case of using the engine control unit as one embodiment of the present invention.

FIG. 11 is a block diagram showing a schematic structure in case of detecting the engine speed and the load state in the thermal resistor type air flow measuring apparatus as one embodiment of the present invention.

FIG. 12 is a characteristic graph showing an erroneous detection for the stepwise change in the air flow in the present invention.

FIG. 13 is a mechanism showing a reduction (binary phenomena) of the output caused by the pulsation amplitude of the thermal resistor.

FIG. 14 is a characteristic graph showing the intake negative pressure on the horizontal axis and the mean air flow velocity on the vertical axis plotted with values obtained by measuring separately the forward air flow velocity and the reverse air flow velocity in the intake pipe.

FIG. 15 is a characteristic graph showing a pulsation amplitude state for the individual intake negative pressure in the intake pipe.

FIG. 16 is a schematic circuit structure of the thermal resistor type air flow measuring apparatus.

FIG. 17 is a vertical cross-section view of the thermal resistor type air flow measuring apparatus.

FIG. 18 is a projected view of FIG. 17 from the upper stream side.

FIG. 19 is a system configuration of the internal combustion engine.

Claims

1. A thermal resistor type air flow measuring apparatus, comprising

2. A thermal resistor type air flow measuring apparatus of claim 1, wherein

3. A thermal resistor type air flow measuring apparatus of claim 2, wherein

4. A thermal resistor type air flow measuring apparatus of claim 3 wherein

5. A thermal resistor type air flow measuring apparatus of claim 2, wherein

6. A thermal resistor type air flow measuring apparatus of claim 5 wherein

7. A thermal resistor type air flow measuring apparatus of claim 2, further comprising

8. A thermal resistor type air flow measuring apparatus of claim 2, further comprising

9. A thermal resistor type air flow measuring apparatus of claim 2, wherein

F=said maximum value−said minimum value)/((said maximum value+said minimum value)/2).

10. A thermal resistor type air flow measuring apparatus of claim 1, further comprising

11. A thermal resistor type air flow measuring apparatus of claim 1, further comprising

12. A thermal resistor type air flow measuring apparatus of claim 1, wherein

F=said maximum value−said minimum value)/((said maximum value+said minimum value)/2).

13. A control apparatus for an internal combustion engines, comprising

14. A thermal resistor type air flow measuring apparatus, comprising

15. A thermal resistor type air flow measuring apparatus of claim 14, wherein

F=(said maximum value−said minimum value)/((said maximum value+said minimum value/2).

16. A thermal resistor type air flow measuring apparatus of claim 14, further comprising

17. A thermal resistor type air flow measuring apparatus of claim 14, further comprising

18. A control apparatus for an internal combustion engines, comprising

19. A control apparatus for an internal combustion engine, comprising

20. A reverse flow judging method of a thermal resistor type air flow measuring apparatus having

21. An error correcting method of a thermal resistor type air flow measuring apparatus having