Device and method for detecting misfire in engine

Patent metadata

Field	Value
Publication number	US-11441507-B2
Application number	US-201716305581-A
Country	US
Kind code	B2
Filing date	Mar 21, 2017
Priority date	Feb 8, 2017
Publication date	Sep 13, 2022
Grant date	Sep 13, 2022

Abstract

The present invention provides a device and method for detecting a misfire in an engine, the device being provided with: a rotation speed sensor (43) as a supercharger rotation speed measurement unit for measuring a rotation speed (Nt) of a supercharger (23); a misfire index calculation unit (51) that calculates a misfire index (Yt) from a degree of change in the rotation speed (Nt) of the supercharger (23), the rotation speed being measured by the rotation speed sensor (43); and a misfire determination unit (52) that determines a misfire in an engine (10) when the misfire index (Yt) calculated by the misfire index calculation unit (51) exceeds a pre-set determination value (D).

First claim

The invention claimed is:

1. An engine misfire detection device comprising:
a rotation speed sensor measuring a rotation speed of a supercharger,
a sensor signal processing unit configured to:
calculate a misfire index yt from a degree of change in the rotation speed of the supercharger measured by the rotation speed sensor; and
determine a misfire in an engine when the calculated misfire index yt exceeds a pre-set determination value,
wherein
the misfire index calculating calculates the misfire index yt based on a decrease rate ΔNt of the rotation speed of the supercharger, the decrease rate ΔNt being calculated by using the following equation (1):
Δ Nt ( t n )=[−1×{ Nt ( t n )− Nt ( t n−1 )}/ Nt ( t n−1 )]×100  (1)

where Nt(t n ) is the rotation speed of the supercharger at a measurement time t n which any one of pistons included in the engine reaches a top dead center position, and Nt(t n−1 ) is a rotation speed of the supercharger at a measurement time t n−1 which another piston reaches a top dead center position, the measurement time t n−1 is one measurement time before t n .

2. The engine misfire detection device according to claim 1 , wherein the misfire index calculating calculates as the misfire index yt based on the decrease rate ΔNt of the rotation speed Nt of the supercharger and by using the following equation (2)
yt ( t n )=−Δ Nt ( t n )+Δ Nt ( t n−1 )  (2).

3. The engine misfire detection device according to claim 1 , wherein a crank angle sensor measuring a crank is provided and the misfire determining specifies a misfiring cylinder based on the crank angle measured by the crank angle sensor when the misfire in the engine is determined.

4. An engine misfire detection method comprising:
measuring a rotation speed of a supercharger;
calculating a misfire index yt from a degree of change in the rotation speed of the supercharger; and
determining a misfire in an engine when the misfire index yt exceeds a pre-set determination value, wherein
at the calculating the misfire index yt, the misfire index yt is calculated based on a decrease rate ΔNt of the rotation speed of the supercharger, the decrease rate ΔNt being calculated by using the following equation.:
Δ Nt ( t n )=[−1×{ Nt ( t n )− Nt ( t n−1 )}/ Nt ( t n-1 )]×100  (1)

where Nt(t n ) is the rotation speed of the supercharger at a measurement time t n which any one of pistons included in the engine reaches a top dead center position, and Nt(t n−1 ) is a rotation speed of the supercharger at a measurement time t n−1 which another piston reaches a top dead center position, the measurement time t 1−1 is one measurement before t 1 .

5. The engine misfire detection device according to claim 2 , wherein a crank angle sensors measuring a crank angle is provided and the misfire determining specifies a misfiring cylinder based on the crank angle measured by the crank angle sensor when the misfire in the engine is determined.

6. The engine misfire detection method according to claim 4 , wherein the calculating of the misfire index yt is performed based on the decrease rate ΔNt of the rotation speed Nt of the supercharger and by using the following equation (2):
yt ( t n )=−Δ Nt ( t n )+Δ Nt ( t n−1 )  (2).

7. The engine s ire detection m method according to claim 4 , further comprising:
measuring a crank angle, and
specifying a misfiring cylinder based on the measured crank angle when the misfire in the engine is determined.

Assignees

• Mitsubishi Heavy Ind Engine & Turbocharger Ltd

Inventors

• Sase Ryo
• Noguchi Shintarou

Classifications

• F02D41/009

  using means for generating position or synchronisation signals · CPC title

• F02D2200/1015

  Engines misfires · CPC title

• G01M15/11

  by detecting misfire · CPC title

• F02D41/0007 Primary

  for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12) · CPC title

• F02D23/00

  Controlling engines characterised by their being supercharged · CPC title