Fuji Jukogyo Kabushiki Kaisha

Subaru Corporation

Ryuichiro Imai

Izuru Kawahira

Atsushi Takahashi

Yoshinori Yamada

Hiromi Hirase

A protocol conversion device includes a converter and a communicator. The converter makes a protocol conversion of vehicle data acquired from a vehicle by communication based on a first protocol, into vehicle data in a format of HTTP or HTTPS as a second protocol. The vehicle data is directed to diagnosis of the vehicle. The communicator transmits the vehicle data protocol-converted by the converter, to a communication terminal that is able to execute, by communication based on the second protocol, a vehicle diagnosis program held by a web server. The converter makes a protocol conversion of data transmitted from the communication terminal by the communication based on the second protocol, into data in a first protocol format. The communicator transmits, to the vehicle by the communication based on the first protocol, the data in the first protocol format that is protocol-converted by the converter.

Protocol conversion device and vehicle diagnostic system

A method of discriminating the misfire of a multicylinder engine for each cylinder (FIG. 1A), comprising the steps of discriminating a cylinder number (#i) at a present combustion stroke (S101); calculating a present momentum at the present combustion stroke, in a period in which no combustive work is done (S105); computing a second momentum at a second stroke preceding the present combustion stroke two times, in a period in which no combustive work is done (S106); averaging the present and second momentums (S107); deriving a first momentum at a first stroke preceding the present combustion stroke one time, in a period in which no combustive work is done (S107); taking a difference between the averaged momentum and the first momentum (S107); setting a misfire judgement level from a map of combustion conditions in a function of said first momentum and engine load data (S108); and comparing the difference with the misfire judgement level (S109), thereby to judge the misfire condition for each cylinder without being affected by a manufactural allowance.

Misfire discriminating method for an engine

A method of discriminating the misfire of a multicylinder engine for each cylinder (FIG. 1 A), comprising the steps of discriminating a cylinder number (#i) at a present combustion stroke (S101); calculating a present momentum at the present combustion stroke, in a period in which no combustive work is done (S105); computing a second momentum at a second stroke preceding the present combustion stroke two times, in a period in which no combustive work is done (S106); averaging the present and second momentums (S107); deriving a first momentum at a first stroke preceding the present combustion stroke one time, in a period in which no combustive work is done (S107); taking a difference between the averaged momentum and the first momentum (S107); setting a misfire judgement level from a map of combustion conditions in a function of said first momentum and engine load data (S108); and comparing the difference with the misfire judgement level (S109), thereby to judge the misfire condition for each cylinder without being affected by a manufactural allowance.

A misfire diagnosis apparatus for an internal combustion engine having a plurality of cylinders, comprising momentum change rate calculating device (M1), momentum change rate comparing device (M2), misfire judging device (M3) and average momentum change rate learning value setting device (M4). A momentum change rate calculated by the calculating device (M1) is compared with an average momentum change rate learning value by the comparing device (M2) in light of a learning value map (MMP.DELTA.N.sub.l) corresponding to the operating conditions of a pertinent cylinder. The result of the comparison is compared with a misfire judgement level by the judging device (M3) in light of a misfire judgement level map (MMP.DELTA.N.sub.LEVEL) corresponding to the operating conditions of the pertinent cylinder. The setting device (M4) sets and updates the learning value of the learning value map (MMP.DELTA.N.sub.l).

Misfire diagnosis apparatus for an internal combustion engine

The device for monitoring the combustion state of each cylinder is provided in a multi-cylinder engine and determining if combustion abnormality occurs in the cylinder. The misfiring determining circuit compares an engine speed of a previous interval with that of a current interval, calculates the speed variation of a cylinder between both intervals, and determines the misfiring level by comparing the variation with the misfiring determining level. A cylinder misfiring time counting circuit counts the misfiring time of each cylinder and informs a cylinder misfiring time calculating circuit of the counting result. The cylinder misfiring time calculating circuit serves to average the misfiring time. A cylinder abnormal misfiring determining circuit compares the average misfiring time with a predetermined misfiring time maximum value for detecting the abnormal misfiring in each cylinder.

Engine misfiring determining device

A period when the combustion of an engine is not performed is detected at two points before and after the top dead center of the cylinder in the expansion stroke. Engine speeds in both the periods are detected and the speed difference between the detected periods is calculated. Mean speed difference is calculated. The mean speed difference is compared with a predetermined limit value, thereby estimating combustion condition of the cylinder.

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Tokyo, Japan

Ryuichiro Imai