JPH1144611A - Engine test method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] An engine test method capable of more reliably detecting a malfunction of an engine in a combustion stability test by imposing more severe conditions than conditions at the time of lean combustion in an actual vehicle. The purpose is to provide. SOLUTION: A misfire is performed using a predetermined control amount as a parameter for one engine in which all elements affecting the misfire occurrence rate are normal elements and for another engine including an abnormal element in the elements affecting the misfire occurrence rate. The occurrence rate is measured, and then the determined misfire occurrence rate is divided into a high misfire occurrence rate area and a low misfire occurrence rate area based on a predetermined reference value. And the area where the misfire rate of the other engines is high,
A determination area for determining the presence / absence of the abnormal element is provided, and the control amount of the engine to be tested is set in the determination area, and the misfire occurrence rate is compared with the reference value. The presence or absence of the abnormal element is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for testing an engine. Specifically, it is applied to a test of combustion stability in lean combustion.

[0002]

2. Description of the Related Art Due to social needs such as energy saving and global environment improvement, while maintaining clean exhaust gas characteristics,
Engines capable of lean burn exceeding the stoichiometric air-fuel ratio are being developed. Particularly, in a direct injection engine in which fuel is directly injected into a combustion chamber and ignited, in a high load region, fuel is uniformly mixed in an intake process and burned near a stoichiometric air-fuel ratio to obtain a high output, while a partial output is obtained. In the load range, the fuel is stratified in the late stage of the compression process, and the fuel is lean burned, thereby realizing fuel saving.

[0003] Such a direct-injection engine has preferable characteristics that, during lean combustion, atomized fuel is intensively supplied to the vicinity of the ignition plug, so that combustion is stable and misfire is unlikely to occur. However, it is also a fact that the misfire occurrence rate is affected by the fuel injection angle of the engine, the discharge gap of the spark plug, the opening / closing timing of the intake valve, and the like. In view of engine quality control,
A test of combustion stability as shown in FIG.

In this test, as shown in FIG.
First, the engine is started, then, after the warm-up operation, a partial load operation is performed so as to reach the determination region, and then, misfire detection is performed in the determination region. The determination area is set to an engine output of 2000 rpm and an engine output of 6 horsepower (matching point) as shown in FIG. 2 in consideration of the state of lean combustion in an actual vehicle.

[0005] In the misfire detection, the number of misfires occurring per fixed time is measured, and if the number of misfires exceeds a predetermined value, it is determined that combustion of the engine is unstable. When it is determined from such a combustion stability test that the combustion of the engine is unstable, factors that affect the misfire occurrence rate, such as the fuel injection angle of the engine, the discharge gap of the spark plug, or the intake air The re-inspection is performed because there is a high possibility that there is a defect in any of the valve opening / closing timings.

[0006]

As described above, the in-cylinder injection engine has a characteristic that it burns very stably during lean combustion and is basically resistant to misfiring. Even if there are some problems with the engine, it is difficult to misfire, and it is difficult to detect engine problems. In other words, the excellent characteristics of the direct injection engine do not appear on the surface while suppressing other problems.

[0007] However, if the above-mentioned troubles progress after shipment without any such troubles being found in the engine, even the in-cylinder injection engine does not burn stably during lean burn. Idling may be upset and engine stall may occur. Therefore, before the shipment, various criteria for the above-mentioned combustion test were examined so that such a defect could be found, but it was difficult to set an appropriate criteria.

The present invention has been made in view of the above-mentioned prior art, and imposes more severe conditions on lean combustion in an actual vehicle, so that engine failure can be more reliably determined in a combustion stability test. An object of the present invention is to provide a test method of an engine that can be detected.

[0009]

According to a first aspect of the present invention, there is provided a method for testing an engine, comprising: an engine in which all factors affecting a misfire occurrence rate are normal elements; The misfire occurrence rate is measured using a predetermined control amount as a parameter for each of the other engines that include an abnormal element as an element affecting the misfire rate, and then the obtained misfire occurrence rate is determined based on a predetermined reference value. And a region where the misfire occurrence rate of the one engine is low and the region where the misfire occurrence rate of the other engine is high is determined in order to determine the presence or absence of the abnormal element. Further, by setting the control amount of the engine to be tested in the determination region and comparing the misfire occurrence rate with the reference value, the abnormal condition of the engine is determined. And judging the presence or absence of.

According to a second aspect of the present invention, there is provided an engine test method according to the first aspect, wherein the factors affecting the misfire occurrence rate include a fuel injection angle of an engine, a discharge gap of a spark plug, It includes at least one of opening / closing timing of an intake / exhaust valve, a fuel injection shape, an intake port shape, or a fuel injection amount.

According to a third aspect of the present invention, there is provided an engine test method according to the first or second aspect, wherein the predetermined control amount is at least one of a fuel injection timing and an ignition timing of the engine. It is characterized by including.

According to a fourth aspect of the present invention, there is provided a method for testing an engine according to the first to third aspects of the present invention, wherein the engine directly injects fuel into a combustion chamber and ignites the engine. It is characterized by being.

[Operation] If there is a malfunction in the engine, it will not stably burn and will easily misfire at the time of lean combustion. For example, when the ignition timing and the injection end timing are changed, as shown in FIG. 1, a region where the misfire rate of the engine is high and a region where the misfire rate is low are divided. A is wide, but when there is an abnormality in the engine, the area B (shown by diagonal lines in the figure) where stable combustion is possible becomes narrow.

As shown in FIG. 1, the matching points, which are the ignition timing and the injection end timing in consideration of the state of lean combustion in the actual vehicle, are included in both the region A and the region B, and thus affect the misfire rate. Even if there is an abnormality in the element such as the injection timing, the fuel burns stably and the abnormality cannot be found.

Therefore, in the present invention, a portion included in the area A and not included in the area B is set as a determination area. As a result, stable combustion is not performed except when the engine is normal, that is, when there is an abnormality in the engine, so that the abnormality can be reliably detected.

For example, if the ignition timing is shifted from the matching point and a portion included in the area A but not included in the area B is determined as a determination area, it is determined that there is an abnormality in the injection angle, and that the discharge of the spark plug It is possible to reliably detect that the gap is small and that the opening / closing timing of the intake / exhaust valve is shifted.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. 1 to 4 show a method for testing combustion stability of an engine according to one embodiment of the present invention. This embodiment is applied to a direct injection engine. In the present embodiment, as shown in FIG. 4, a dynamometer 2 is connected to the engine 1, and an ignition timing switching signal and the like are transmitted to the engine 1 and the dynamometer 2 through the operation control ECU 3 and the control sequencer 4. This is for detecting the presence or absence of misfire by shifting the ignition timing and the injection timing to preset points.

For example, as shown in FIG. 3 (b), the engine 1 is first started, then, after a warm-up operation, a partial load operation is performed so as to reach a determination region. Shift to perform misfire detection. Here, the determination region is an engine speed of 2000 rpm, 6 rpm shown in FIG.
The horsepower engine output (matching point)
At the time of misfire detection, the ignition timing and the injection timing are shifted. The ignition timing and the injection timing are set to be more severe than the conditions at the time of lean burn in an actual vehicle. Specifically, as shown in FIG. 1, it is included in a region A where stable combustion is possible when the engine is normal, but not included in a region B where stable combustion is possible when the engine is abnormal. Range.

That is, first, the limit value of the misfire occurrence rate which does not cause any practical problem is preset as a reference value of the misfire occurrence rate (determined misfire occurrence rate P described later). Prepare an engine that is all normal and an engine that includes an abnormal element in the above elements, then change the misfire occurrence rate and the fuel injection timing for each of them and check the misfire occurrence rate at each point. The engine is classified into a region where the misfire occurrence rate of each engine is high and a region where the misfire occurrence rate is low based on the value. An area with a high rate is set as a determination area for examining the presence or absence of an abnormal element in the engine to be tested.

For example, by controlling the ignition timing earlier or later than the above matching point, the injection angle is abnormal, the discharge gap of the ignition plug is small, and the opening / closing timing of the intake / exhaust valve is shifted. Can be reliably detected. The misfire detection includes the number of misfires at a fixed engine speed (not the rotational speed),
That is, if the engine speed is constant, the number of misfires occurring per fixed time is measured, and if the number of misfires exceeds a predetermined value, it is determined that the combustion of the engine is unstable.

For a more specific embodiment of the present invention, FIG.
This will be described with reference to FIG. First, the preparation work of ~
After the operation, the operating conditions (throttle opening, air
Engine speed) (step S1), and then test
The number of revolutions M, the number of determination areas N, and the determination misfire occurrence rate P
Set (step S2). Here, the test rotation speed M and
Is the number of engine revolutions per one judgment area (predetermined
Value), and the determination area number N is, as shown in FIG.
Judgment area A₁, A_Two, ... A _nIs the number of Also, the judgment area
A₁, A_Two, ... A_nIs from ignition timing and fuel injection timing.
Is stored in a memory in advance. Judgment misfire
The live rate P is a determination value (predetermined value) of the misfire occurrence rate.

[0022] Subsequently, the set reads the determination region A ₁ from the memory (step S3, S4), for detecting a misfire by fluctuation of (partial load) performs the operation (step S5), and the rotation signal (crank angle signal) ( Step S6). Then, the number of misfires occurring until the engine rotational speed reaches the predetermined rotational speed M is counted (step S7), the misfire occurrence rate p is calculated (step S8), and compared with the determined misfire occurrence rate P (step S9). ). By the time the misfire occurrence rate p is determined misfire occurrence rate P above, determines that the determination region A ₁ abnormality is detected (step S11). At this time, the operator is notified of the rejection of the engine by a suitable means such as a lamp or a buzzer, and the test step of the engine is completed.

On the other hand, when the misfire occurrence rate p is not smaller than the determination misfire occurrence rate P, by repeating the move to the next determination area A ₂ (step S10), and from step S4 to step S9, all the determination area A _1, a _2, measures the misfire occurrence rate p for ... a _n. All judgment areas A ₁ ,
When A _2, ... misfire occurrence rate p measured for A _n is not smaller than the determination misfire occurrence rate P, it is determined to be normal with respect to the misfire rate.

If it is determined that the misfire rate is normal as described above, the fuel injection angle of the engine, the discharge gap of the spark plug, the opening / closing timing of the intake / exhaust valve, etc. It is found that there is no defect, and conversely, the determination areas A ₁ , A _{2 ,.}
Is determined to be abnormal, it is highly likely that any of the above elements has a problem.

The present invention is preferably applied to a direct injection type engine which stably burns during lean combustion. However, the present invention can be similarly applied to other lean combustion engines, and similar effects can be obtained. Is played. Further, in the above-described embodiment, the misfire occurrence rate is measured by controlling the fuel injection timing or the ignition timing of the engine as a parameter as shown in FIG. 1 for ease of control. However, the present invention is not limited to this. Instead, other control amounts may be controlled as parameters as long as the misfire occurrence rate can be measured.

Further, factors affecting the misfire occurrence rate are
However, the present invention is not limited to the one shown in the above-described embodiment.
Suitable for injection shape, intake port shape, fuel injection amount, etc.
It can be used. Note that these misfiring rates
Each determination area A for each of the influencing elements ₁,
A_Two, ... A_nIf there is a one-to-one correspondence, in which area misfire
By knowing that the incidence rate is out of judgment,
It is possible to detect whether an element is abnormal,
You can take action.

[0027]

As described above, according to the first aspect of the present invention, the normality or abnormality of the engine can be ensured by the simple operation of confirming the misfire occurrence rate in the previously selected judgment region. Can be determined. The selection of the above-mentioned region is extremely easy because at least two types of engines are prepared and the misfire occurrence rate is measured. According to the second aspect of the present invention, a meaningful and effective test can be performed by including an important factor influencing the misfire occurrence rate when selecting the above-described determination region. According to the third aspect of the present invention, the test workability can be further improved by using easily controllable parameters when measuring the misfire occurrence rate. Further, according to the invention of claim 4, since the occurrence of misfire during lean burn can be reduced, it is possible to realize an engine that can effectively exhibit the effects of the method of the present invention.

[Brief description of the drawings]

FIG. 1 is a graph showing a normal stable region and a stable region at the time of failure according to the present invention.

FIG. 2 is a graph showing a performance curve of an engine.

FIG. 3A is a flowchart illustrating a test of combustion stability of an engine according to a conventional example, and FIG. 3B is a flowchart illustrating a test of combustion stability of an engine according to an embodiment of the present invention. is there.

FIG. 4 is a schematic diagram of equipment used for testing combustion stability of an engine according to one embodiment of the present invention.

FIG. 5 is a flowchart showing a more specific embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 engine 2 dynamometer 3 operation control ECU 4 control sequencer

 ──────────────────────────────────────────────────の Continued from the front page (72) Inventor Hiroyuki Tachibana 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation

Claims (4)

[Claims] A predetermined control amount is used as a parameter for one engine in which all elements affecting the misfire occurrence rate are normal elements and for another engine including an abnormal element in the elements affecting the misfire occurrence rate. The misfire occurrence rate is measured, and then, the obtained misfire occurrence rate is divided into a high misfire occurrence rate area and a low misfire occurrence rate area based on a predetermined reference value. Area where the misfire rate of the other engines is high
A determination area for determining the presence / absence of the abnormal element is provided, and the control amount of the engine to be tested is set in the determination area, and the misfire occurrence rate is compared with the reference value. Determining the presence or absence of the abnormal element in the engine. 2. Factors affecting the misfire occurrence rate are:
Engine fuel injection angle, spark plug discharge gap,
2. The engine test method according to claim 1, further comprising at least one of an opening / closing timing of an intake / exhaust valve, a fuel injection shape, an intake port shape, and a fuel injection amount. 3. The engine test method according to claim 1, wherein the predetermined control amount includes at least one of an engine fuel injection timing and an ignition timing. 4. The test method for an engine according to claim 1, wherein the engine is a direct injection engine in which fuel is directly injected into a combustion chamber and ignited.