Misfire determination apparatus for internal combustion engine

Patent metadata

Field	Value
Publication number	US-2016334305-A1
Application number	US-201615138721-A
Country	US
Kind code	A1
Filing date	Apr 26, 2016
Priority date	May 14, 2015
Publication date	Nov 17, 2016
Grant date	—

Abstract

A misfire determination apparatus includes a rotation variation amount acquisition unit that obtains a rotation variation amount (ΔNE), which is a difference between a first angular velocity variation amount (Δω 1 ) obtained during an expansion stroke of an arbitrary cylinder of a multi-cylinder internal combustion engine and a second angular velocity variation amount (Δω 2 ) having been obtained in relation to a cylinder that has reached the expansion stroke N (where N is a positive integer) revolutions of a crankshaft before the arbitrary cylinder reaches the expansion stroke, and a misfire determination unit that, when the obtained rotation variation amount (ΔNE) exceeds a predetermined threshold (ΔNEth), determines that a misfire has not occurred in the internal combustion engine when a predetermined condition is established, and determines that a misfire has occurred in the internal combustion engine when the predetermined condition is not established.

First claim

What is claimed is:

1 . A misfire determination apparatus for an internal combustion engine, the misfire determination apparatus comprising:
an angular velocity variation amount acquisition unit configured to:
(i) obtain a crank angle velocity on the basis of a time required for a crankshaft to rotate through a predetermined rotation angle width from a first crank angle to a second crank angle during an expansion stroke of each cylinder of a multi-cylinder internal combustion engine, and
(ii) obtain an angular velocity variation amount, the angular velocity variation amount being a difference in the crank angle velocity between two cylinders that reach the expansion stroke consecutively;
a rotation variation amount acquisition unit configured to obtain a rotation variation amount, the rotation variation amount being a difference between a first angular velocity variation amount and a second angular velocity variation amount, the first angular velocity variation amount being obtained by the angular velocity variation amount acquisition unit during the expansion stroke of an arbitrary cylinder among the respective cylinders, and the second angular velocity variation amount having been obtained by the angular velocity variation amount acquisition unit in relation to a cylinder that has reached the expansion stroke in a Nth revolution of the crankshaft before the arbitrary cylinder reaches the expansion stroke, the N being a positive integer; and a misfire determination unit configured to: when the rotation variation amount obtained by the rotation variation amount acquisition unit exceeds a predetermined threshold,
(i) determine that a misfire has not occurred in the internal combustion engine when a predetermined condition is established, the predetermined condition being established when a magnitude of the second angular velocity variation amount is greater than a magnitude of the first angular velocity variation amount and the second angular velocity variation amount has a sign by which a value of the rotation variation amount relating to the arbitrary cylinder is oriented in a direction for exceeding the predetermined threshold, and
(ii) determine that a misfire has occurred in the internal combustion engine when the predetermined condition is not established.

2 . The misfire determination apparatus for an internal combustion engine according to claim 1 , wherein the misfire determination unit is configured to execute the misfire determination after replacing the rotation variation amount relating to the arbitrary cylinder with a value that does not exceed the predetermined threshold when the predetermined condition is established.

3 . The misfire determination apparatus for an internal combustion engine according to claim 1 , wherein the misfire determination unit is configured to execute the misfire determination after replacing the rotation variation amount relating to the arbitrary cylinder with 0 when the predetermined condition is established.

Assignees

• Toyota Motor Co Ltd

Inventors

• Hyodo Junji

Classifications

• F02D41/1498

  measuring engine roughness · CPC title

• F02D41/22

  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)} · CPC title

• F02D41/2403

  using essentially up/down counters · CPC title

• Y02T10/40

  Engine management systems · CPC title

• F02D41/009

  using means for generating position or synchronisation signals · CPC title