JP3466207B2 - Operation stroke identification method and identification device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for identifying the instantaneous operating stroke of each cylinder of a 4-stroke engine.
The 4-stroke engine includes a crankshaft angle generator,
A sensor associated with each cylinder, said sensor outputting a signal which is a measure for the combustion chamber pressure equivalent, and an apparatus for carrying out this method.

The four strokes (strokes) of such an engine are hereinafter referred to as an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke. In the electronic control process, it is important to accurately identify the operating stroke of each cylinder, for example to set the ignition timing or the injection period.

[0003]

2. Description of the Prior Art In practice, for example, a method using a signal from a camshaft sensor is used to identify a stroke. The camshaft rotates once for every two rotations of the crankshaft. Accordingly, one camshaft sensor signal is output for each 720 ° rotation of the crankshaft. Based on the engine structure, the generation of this sensor signal is associated with the operating stroke of the individual cylinder.

According to another known method, an inductive sensor is provided, which sensor outputs one signal for every 720 ° of crank angle. This is because one ignition signal is applied to each cylinder at this angular interval.

Motion stroke identification at angular intervals less than 720 ° is possible when the pressure sensor signal is used for cylinder identification. In this case, one pressure sensor each
Each is assigned to one cylinder. A method using this type of sensor is described in DE-A-4002228. It is shown in this publication that it is possible to identify every 720 ° / n crankshaft angle. Here, n is the number of cylinders of the 4-stroke engine. Such high-speed cylinder identification is possible only when the signal course of at least one pressure sensor is monitored in a predetermined crank angle range.

Problems that have not been noticed in the prior art occur during engine startup. Note the following in this context: That is, the crankshaft angle signal can be detected quickly after the starter is operated, i.e. when a relatively low minimum speed is reached, but the absolute value of this signal must be determined only after an explicit signal of angle is detected. It means that you can In other words, it becomes possible only when the signal of the camshaft sensor or the sensor of the ignition cord, for example, the signal of the inductive sensor is detected. If such a signal is detected, the crank angle range can be set and the course of the signal of the at least one pressure sensor can be monitored in this predetermined range for accurate operating stroke identification. .

When the above-described conventional method and apparatus are applied at the time of starting a four-stroke engine, it may occur that a relatively large angular range of the crankshaft is swept before the actual stroke of each cylinder is identified. In an engine that takes in fuel, the fuel is taken in before identifying the operating stroke in all regions, but this fuel is exhausted from the engine without being burned. This is because it is completely unclear which cylinder should be fired when. When the engine uses an injector, the unburned fuel problem is solved as follows. That is, the fuel injection is started only after the ignition timing can be set. However, even in such an engine, if fuel metering is started for each cylinder, when the first ignition timing is determined, an ignitable air-fuel mixture already exists.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and a device for quickly identifying the instantaneous stroke of each cylinder of a 4-stroke engine, even when the 4-stroke engine is being started.

[0009]

SUMMARY OF THE INVENTION According to the invention, the above-mentioned object is to identify the operating stroke at the start of the engine, as soon as the crankshaft angle signal is sent from the crankshaft angle generator, Detecting and storing a signal, among the assigned sensors, detecting a cylinder whose sensor signal shows a pressure course of a pressure maximum, at the same time when a threshold condition for the sensor signal is fulfilled, this Indicating the presence of compressed gas, and-determining the cylinders that meet the threshold conditions as in the expansion stroke, corresponding each operating stroke to other cylinders according to the structure of the engine, Where the threshold level is
The solution is constructed and arranged such that only the maximum pressure value that develops for the cylinder in question when the compression stroke and the expansion stroke change is identified.

The device according to the invention for identifying the instantaneous stroke of each cylinder of an Otto type engine has a crankshaft angle sensor and a sensor for each cylinder, which sensor corresponds to the combustion chamber pressure equivalent of that cylinder. It sends out a signal that is a measure and additionally has a movement stroke identification device. The device is configured to implement a motion stroke identification method.

The method and apparatus of the present invention takes advantage of the fact that it is known exactly which sensor signal originated from which cylinder. Therefore, find out which cylinder has the maximum pressure value under high pressure. In this case, the maximum pressure value occurs both during the exhaust stroke and the subsequent intake stroke, and between the compression stroke and the subsequent expansion stroke. However, the maximum pressure value of the latter is much larger than that of the former. Therefore, the two maximum pressure values are clearly distinguishable. The larger of the two maxima is clearly detected. As soon as such a maximum value for a cylinder is detected, it is established that this cylinder is in the expansion stroke. The operating strokes of the other cylinders are also determined based on the engine structure. This detection is completely independent of whether or not a signal representing the absolute angle has already been identified.

[0012] The method and development of the invention not only identify the instantaneous stroke of each cylinder, but also allow the crankshaft angle to be estimated with sufficient accuracy to set the ignition timing. The device therefor has a crankshaft angle calculation device, which calculates the instantaneous crankshaft angle by the number of increments between the increment in the presence of said maximum pressure value and the instantaneous increment. Calculate from each angular interval, the number of the cylinder with this maximum pressure value.

When the engine is, for example, a 6-cylinder engine, each 1
It is known that for every 20 ° of crankshaft angle, one cylinder relative to the other reaches the above-mentioned high maximum pressure value and thus enters the expansion stroke. Crankshaft angle 0 ° (= 720 °)
Is set to be 60 ° before the start of the expansion stroke of the first cylinder in the ignition sequence, the sixth cylinder in the ignition sequence will enter the expansion stroke at a crankshaft angle of 660 °. When it is determined that the maximum pressure value for the sixth cylinder is delayed by 3 increments of the signal of the crankshaft angle sensor at the time of engine start, the crankshaft position at the time of discrimination is after 3 angle increments of 660 °. There will be. If one angle segment is 3 ° (this is a typical example), the crankshaft angle at the time of identification is 669 °. This crankshaft angle is known only with the accuracy with which the maximum pressure value can be identified. This accuracy is ± 1 to 2 increments and depends on the cost in identifying the maximum value. This corresponds to ± 3 ° to ± 6 ° in angle, which is sufficient for coarse adjustment of ignition. When the signal from the camshaft sensor, the ignition signal sensor or the crankshaft mark sensor is measured in the signal example that clearly shows the crankshaft angle, the above-mentioned uncertain state disappears and the crankshaft angle does not generate an error. Assuming that, it is known exactly thereafter. However, since errors are unavoidable, further stroke identification is performed even after the engine start period has elapsed, and a further signal accurately representing the angular position of the crankshaft is sampled.
This is done by conventional methods.

The combustion chamber pressure equivalent amount detected in each cylinder can be directly set as the combustion chamber pressure. However, more advantageously, the combustion chamber pressure is indirectly measured using pressure relief. Pressure relief occurs on the piezo ring below the spark plug or cylinder head screw. Washers of this kind are offered by various manufacturers.

As already mentioned, it is important in the method and apparatus of the present invention to identify high maximum pressure values. The presence of sufficiently high pressure for discrimination accuracy is detected as follows. That is, either the absolute value of the measured signal is above a threshold or the difference between the two signals is above another threshold. The second condition is more accurate than the first condition and is possibly detected with higher reliability. However, there is a delay in the identification of the operation stroke and the identification of the angle. In general, the reliability of the identification can be said to increase as the evaluation complexity increases, but the final identification is also delayed. How much it costs to operate a sufficiently reliable method depends, for example, on the time course of the measured signal. If there is an engine in which the pressure of the cylinder rises to the top dead center relatively quickly during compression, and then rapidly drops again when the dead center is exceeded, there is no problem in accurately identifying the maximum value.
On the other hand, if the agency is configured so that a relatively large maximum value region occurs near top dead center, the evaluation to identify the true maximum value point as accurately as possible is more costly. It takes. If only the identification of the operating stroke is a problem, and at the same time the crankshaft angle does not have to be set as accurately as possible, the cost of the maximum value identification can be relatively low.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus of FIG. 1 has a four-cycle engine 10 with six cylinders Z1 to Z6, an operation stroke identifying device 11, a crankshaft angle calculating device 12 and a control device 13. The crankshaft position of the engine is the crankshaft angle sensor 1
Detected by 4. This sensor outputs the crankshaft angle signal KWW to the operation stroke identification device 11 and the crankshaft angle calculation device 12 every 3 ° of the crankshaft angle. Similarly, the crankshaft mark signal KWM is also output to the control device 13 every 360 ° of the crankshaft angle. The combustion chamber pressures of the cylinders Z1 to Z6 are detected by the pressure sensors S1 to S6. The lab deals with pressure sensitive washers beneath each spark plug in the cylinder. Accordingly, these sensors measure pressure relief and output an associated electrical signal in the exemplary embodiment. However, the following always shows the pressure of belonging. The sensor signals P1 to P6 are supplied to the operation stroke identifying device 11.

FIG. 2 shows the non-ignition pressure profile measured for the six cylinders of the engine 10 of FIG. The maximum value has reached about 3.8 bar. The pressure threshold is shown at 3 bar. Crankshaft angle signal KW
After the engine is started, W can be detected after the straight line shown vertically. Only when it becomes possible to detect the motion stroke identification device 11
Can evaluate the signals P1 to P6 from the sensors S1 to S6. In the angular region shown in FIG. 2, three cylinders reach their maximum values after the vertical straight line. That is, the cylinders Z5, Z3 and Z6. The pressure maxima of cylinders Z5 and Z6 are then large maxima with pressures above the threshold PSW of 3 bar. Therefore, it is the maximum value of the pressure generated between the compression stroke and the expansion stroke. On the other hand, cylinder Z3
The maximum value for is only above 1 bar.
That is, this is the maximum value that occurs between the exhaust stroke and the intake stroke. This latter maximum is not well discerned.
Therefore, for cylinder identification and crankshaft angle detection,
Only large maximum values above the threshold PSW are used. The first pressure maximum value that exceeds the threshold value PSW is the maximum value of the cylinder Z5. In FIG. 2, it is assumed that this pressure maximum is identified in the next increment after the maximum of the crankshaft angle signal KWW. Based on the engine structure, it is known that the alternation between the compression stroke and the expansion stroke for cylinder Z5 is at a crankshaft angle of 540 °. The angle difference between crankshaft angle increments until the next increment is 3 °. In this case, the crankshaft angle signal whose occurrence has been identified is associated with the absolute crankshaft angle 543 ° if there was a pressure maximum in the previous increment. In Figure 2, this angle is "c
a. 543 "", which means that this angle contains an error, i.e. its accuracy depends here on the accuracy with which the pressure maximum for cylinder Z5 can be detected. Is possible only after the crankshaft angle mark KWM has been generated, the value 0 ° being associated with the associated crankshaft angle signal.

Therefore, before the maximum pressure value for the cylinder Z5 is detected, that is, before the angle 543 °, the absolute angle is not associated with the crankshaft angle signal KWW. The aforementioned angle and crankshaft angle mark K
The absolute angle is almost known during the occurrence of the WM and then exactly. In this region, the ignition timing can be set by the control device 13 using a known absolute angle. As a result, in the case of cylinder Z6, it is possible to ignite the cylinder even though the mark that enables accurate angle correspondence is not obtained.

Based on the flow charts of FIGS. 3 to 6,
An advantageous embodiment for operating stroke identification and crankshaft angle detection will be described. The method according to FIG. 3 shows a general configuration, and FIGS. 4 to 6 show the details. In these drawings, "Z" represents the cylinder number of the ignition sequence. "DECFL
"AG" is a flag indicating whether the pressure is decreasing (in that case, "1") or increasing (in this case, "0") in the cylinder number Z. "SWFLAGZ"
Is a flag indicating whether the pressure threshold value PSW in FIG. 2 is exceeded (“1”) or not (“0”) by the pressure for the cylinder Z.

In steps s3.1 to s3.4, the flag DECFLAGZ is set to 1 and the flag SWFLAGZ is set.
Is set to 0 for all cylinders. Then first
As soon as the increment signal KWW is generated by the crankshaft angle sensor 14 (step s3.5), the signal PZ is detected and stored for all cylinders ZN (step s3.6). This forms the basis for signal comparison. Subsequently, the step is repeatedly executed for all the cylinders ZN by the new increment signal from the crankshaft angle sensor 14. This step tests whether there is a pressure maximum that simultaneously fulfills the threshold condition.

The step to be repeatedly executed is step s.
Started by 3.7. In this step s3.7,
It is checked whether the next increment signal comes from the crankshaft angle sensor. Immediately after generation, the sensor signal PZ is measured and stored for all cylinders ZN (step s3.8). The number of cylinders is then initialized, incremented and checked to see if all cylinder pressures have already been evaluated for instantaneous increments. If the evaluation should still be done, step s3.1 after the passage of mark A.
At 2, it is checked whether the threshold condition is met. If not, then after the passage of mark C it is checked at the same time whether another cylinder has to be evaluated (steps s3.10 and s3.11). On the other hand, if the maximum value exists, the engine structure data of the number of the cylinder having the pressure maximum value and the instantaneous crankshaft angle is calculated from the number of increments between the increment for the pressure maximum value and the instantaneous increment. Then, the operation stroke is associated with each cylinder. Then the program progress ends.

Threshold condition step s is shown in FIGS.
A modified example for 3.12 is shown. The modified embodiment of FIG. 4 operates with an absolute pressure threshold and a differential pressure threshold of FIG. In FIG. 4, in step s3.12.1, it is checked whether the pressure PZ for the cylinder Z is above the threshold pressure PSW (see FIG. 2). If it is not on the upper side, mark C follows, otherwise mark B follows. According to FIG. 5, step s
In 3.12.2, the pressure difference ΔPZ is first calculated. Here, for example, a pressure difference over a predetermined number of increments can be handled. Alternatively, if the pressure change is unidirectional in a continuous manner, then an instantaneous difference can be formed with respect to the initial measured pressure or the extreme pressure. As soon as the pressure difference ΔPZ is calculated, it is checked whether the pressure difference ΔPZ exceeds the threshold value DPSW (step s3.12.3). If it is not above the mark C, the mark B is reached otherwise.

FIG. 6 shows an embodiment for step s3.13 of FIG. In step s3.13.1, it is checked whether the instantaneous pressure PZ measured for one cylinder is less than the pressure PZVOR stored in the previous increment. If not small, the pressure rises and the DEC
FLAGZ is set to 0 (step s3.13.
2) And then reach mark E. Otherwise, in step s3.13.3, it is checked whether DECFLAGZ is 0. If it is not 0, the pressure has already dropped during the previous angle increment and reaches the mark E again. In other cases, the mark D follows because the maximum value test is affirmative.
This is because step s3.13.1 was reset at the previous increment, even though the pressure actually dropped.
This is because ECFLAGZ indicates that the pressure has increased before.

The pressure test according to FIG. 6 can be constructed simply as follows. That is, a relatively small change in pressure is allowed except for 8 in the comparison step s3.13.1 so that the angle increment represents a large angle region.
It is arranged to ensure that pressure changes are clearly discerned, even in the region of relatively flat pressure maxima, from one increment signal to another. With this configuration, highly reliable results can be obtained. For example, the pressure may not be evaluated for each crankshaft angle signal for every 3 ° of crankshaft angle, but may be evaluated for example for every third signal. In that case, even if the reversal of the pressure change direction is detected, it is not clear at all whether the reversal is 3 ° or 6 °. This example shows that measurement certainty and angular resolution are conflicting requirements in detecting the pressure maximum. Depending on the respective application, the person skilled in the art has to make a suitable optimum configuration.

[0025]

According to the present invention, even when the 4-stroke engine is started, it is possible to quickly identify the instantaneous operation stroke of each cylinder of the 4-stroke engine.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a 6-cylinder 4-stroke engine having an operation stroke identification device, a crankshaft angle calculation device, and a control device.

2 is a diagram showing the pressure curve for the six cylinders of the engine of FIG. 1 with respect to the crankshaft angle.

FIG. 3 is a flow chart for explaining the method of the present invention.

FIG. 4 is a modified embodiment of the flowchart of FIG.

5 is a modified embodiment of the flowchart of FIG.

6 is a method step for realizing the method steps between the marks B, D, E of the flowchart of FIG.

[Explanation of symbols]

10 4-stroke engine 11 Motion stroke identification device 12 Crankshaft angle calculator 13 Control device Z1-Z6 cylinder S1 to S6 sensors

Front page continued (72) Inventor Eckart Damson Germany Gerlingen Panoramastraße 9 (72) Inventor Martin Klenk Germany Backnängstraßemannstraße 11 (72) Inventor Vinfried Moser Germany Ludwigsburg Grundweinberge 14 (56) Bibliography 2-40944 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02D 43/00-45/00 F02D 41/00-41 / 40

Claims (5)

(57) [Claims] 1. A method for identifying each instantaneous stroke of a cylinder of a 4-stroke engine, the 4-stroke engine having a crankshaft angle generator and a sensor associated with each cylinder, the sensor comprising: as soon as the crankshaft angle signal from the crank shaft angle generator is sent, - in the identification method of the type for outputting a signal which is a measure for the combustion chamber pressure equivalent amount, in order to identify the operation stroke at the start of the engine, Detecting and storing a signal from the sensor, and-detecting , among the assigned sensors, a cylinder in which the sensor signal shows a pressure course of a pressure maximum value, and at the same time, when a threshold condition for the sensor signal is satisfied, is intended to indicate that the compressed gas in the cylinder is present, - determines that the cylinder in which the threshold condition is met in the expansion stroke, the machine According to the structure of the above, each operation stroke is associated with another cylinder, and the threshold level is identified only by the maximum pressure value generated in the cylinder when the compression stroke and the expansion stroke change. Has been selected to
An operation stroke identification method characterized by the above. 2. A crank angle to be detected, the number of increments between the increment at the maximum pressure and the increment at the time of detecting the pressure value, the angular interval per increment, and the maximum pressure value. The method according to claim 1, which is calculated from the cylinder number and the engine structure data. 3. As a threshold condition, the cylinder is assigned to the cylinder.
3. The method according to claim 1, wherein the sensor signal of the sensor is checked whether it is above a threshold value. 4. The method according to claim 1, wherein the threshold condition is to check whether the difference between two sensor signals spaced by a plurality of increments before and after the pressure maximum exceeds a difference threshold. 5. A crankshaft angle generator (14)
And a sensor (S1 to S6) assigned to each cylinder for identifying the instantaneous operation stroke of each cylinder of the 4-stroke engine (10) , wherein the sensors (S1 to S6) are , The combustion chamber of each cylinder
Instrumentation of the type which outputs a signal which is a measure of relative pressure equivalent amount
In the apparatus , a movement stroke identification device (11) is provided, which identification device immediately after the crankshaft angle generator (14) sends out a crankshaft angle signal.
~ S6) is detected and stored, and further , among the assigned sensors, the cylinder whose sensor signal shows the pressure course of the maximum pressure is detected, and at the same time, the sensor signal to the sensor signal is detected. When the threshold condition is satisfied, this indicates that compressed gas is present in the cylinder, and it is determined that the cylinder satisfying the threshold condition is in the expansion stroke, and the respective operation strokes are set according to the structure of the engine. Corresponding to other cylinders, wherein the threshold level is selected so that only the maximum pressure value generated in the cylinder when the compression stroke and the expansion stroke change is identified. Characterized motion stroke identification device.