# US 11,441,507 B2 · Device and method for detecting misfire in engine

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- Number: US 11,441,507 B2
- Document ID: US11441507B2
- Status: Granted
- Kind: B2
- Application number: 16/305,581
- Filed: 2017-03-21
- Published: 2020-07-23
- Granted: 2022-09-13
- Earliest claimed: 2017-02-08
- Assignees: Mitsubishi Heavy Industries Engine & Turbocharger, Ltd.
- Applicants: Mitsubishi Heavy Industries Engine & Turbocharger, Ltd.
- Inventors: Ryo Sase; Shintarou Noguchi
- Web page: https://patentgrep.com/patent/US11441507B2

## CPC

- F02D 41/0007: {for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12)}
- F02D 41/22: Safety or indicating devices for abnormal conditions {(in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809)}
- F02D 23/00: Controlling engines characterised by their being supercharged
- F02D 41/009: {using means for generating position or synchronisation signals}
- F02D 41/221: {relating to the failure of actuators or electrically driven elements}
- G01M 15/11: by detecting misfire
- F02D 2200/1015: Engines misfires
- F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W)
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## 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).

## Claims

### Claim 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):
ΔNt(tn)=[−1×{Nt(tn)−Nt(tn−1)}/Nt(tn−1)]×100 (1)
where Nt(tn) is the rotation speed of the supercharger at a measurement time tn which any one of pistons included in the engine reaches a top dead center position, and Nt(tn−1) is a rotation speed of the supercharger at a measurement time tn−1 which another piston reaches a top dead center position, the measurement time tn−1 is one measurement time before tn.

### Claim 2 (depends on 1)

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(tn)=−ΔNt(tn)+ΔNt(tn−1) (2).

### Claim 3 (depends on 1)

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.

### Claim 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.:
ΔNt(tn)=[−1×{Nt(tn)−Nt(tn−1)}/Nt(tn-1)]×100 (1)
where Nt(tn) is the rotation speed of the supercharger at a measurement time tn which any one of pistons included in the engine reaches a top dead center position, and Nt(tn−1) is a rotation speed of the supercharger at a measurement time tn−1 which another piston reaches a top dead center position, the measurement time t1−1 is one measurement before t1.

### Claim 5 (depends on 2)

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.

### Claim 6 (depends on 4)

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(tn)=−ΔNt(tn)+ΔNt(tn−1) (2).

### Claim 7 (depends on 4)

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.