JPH0353461B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a combustion chamber sensor for supplying measuring signals corresponding to the course of the combustion process in an internal combustion engine, in order to adjust the operating elements of the internal combustion engine, and The present invention relates to an internal combustion engine control device having a reference mark sensor that generates a signal corresponding to a position.
In this case, the time-controlled evaluation circuit or the microprocessor is configured to define two time intervals in each case starting from the signal corresponding to the predetermined crank position.

Prior Art In order to control an internal combustion engine, the pressure inside the combustion chamber,
It is known to use combustion chamber sensors to detect light intensity, ion flow, etc. Depending on the combustion chamber signal generated in this way, the operating elements of the internal combustion engine, such as the fuel supply device, the ignition device, the combustion gas evacuation device, etc.
It is also known to adjust turbochargers and the like.

A device for adjusting the ignition system of an internal combustion engine of a motor vehicle is known from DE 29 35 725 A1. In this device, the signal of an ion flow sensor arranged in the combustion chamber is evaluated.
Furthermore, characteristics of the combustion process are detected from the ion flow signal and correlated with a reference signal, and finally a corrective signal is generated for adjusting the ignition timing forward.

However, the known device only adjusts the ignition point, which has the disadvantage that only very coarse corrections are possible. In particular, limit states in the operating limit region of the engine cannot be detected at all or only extremely incompletely.

Effects of the Invention In contrast, the device of the present invention having the features set forth in claim 1 can accurately detect normal combustion, combustion with a slow flame propagation velocity, and combustion stoppage, and therefore This has the advantage that the internal combustion engine can be well controlled. The internal combustion engine can therefore be controlled in such a way that exhaust gases and driving comfort are optimally balanced. Furthermore, the device according to the invention can also be used to detect engine knocking.

The implementation section describes improved embodiments of the device according to the invention.

In an advantageous embodiment of the invention, an ion current sensor integrally formed in the series spark plug of the engine is used. In this way, there is no need to provide an additional transmitter in the combustion chamber.

In other embodiments of the invention, signals occurring at different time intervals can be simply logically combined. Therefore,
Measured values can be easily processed in a microcomputer.

DESCRIPTION OF EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1, FIG. 2, and FIG. 3 are diagrams representing measurement signals of the combustion chamber sensor during normal combustion, during combustion with a slow flame propagation velocity, or when combustion is stopped, respectively.

In FIGS. 1 to 3, the horizontal axis represents the angle α of the crankshaft, and the measurement signals 10, 11, and 12 are represented on the vertical axis, and the top dead center OT is selected as the origin. The measurement signal in this case is the ion current signal I generated by the ion current sensor. However, it is of course also possible to use other signals known in the art, for example measurement signals of the pressure, light intensity, temperature, etc. in the combustion chamber.

As shown in FIG. 1, the ion current signal I rises after the ignition point ZZP, records a first maximum value before top dead center, a second maximum value after top dead center, and then It decreases towards 0. In the present invention, two time intervals A and B are defined. In that case, time interval A corresponds approximately to the period of normal combustion, and time interval B is the period following each. During normal combustion,
The measurement signal 10 in the second time interval B is approximately equal to zero. threshold value for the first time interval A
If I ₁ is defined as a threshold value I ₂ for the second time interval B, the following can be easily seen. That is, during normal combustion shown in FIG. 1, the measured value 1 at time interval A.
0 is above the threshold and in time interval B it is below the threshold.

FIG. 2 shows the measurement signal 11 during combustion with a slow flame propagation velocity. In this case, the measurement signal 11 registers a maximum value above the threshold value I ₂ in the time interval B.

FIG. 3 shows the measurement signal 13 when combustion is stopped. In this case, there is no measurement signal in either time interval A or B. In other words, it is 0. Therefore, the measurement signal does not exceed the thresholds I ₁ , I ₂ .

In the present invention, the measurement signal 1 during normal combustion
0, signal 1 during combustion with slow flame propagation velocity
1, and the signal 12 at the end of combustion, the signals which reached the thresholds I ₁ , I ₂ during the time intervals A, B are logically combined.

FIG. 4 is a block circuit diagram of a first embodiment of the present invention. 20 here designates a combustion chamber sensor, preferably an ion flow sensor located in the series spark plug. Combustion chamber sensor 20 is arranged on combustion chamber wall 21 . The measurement signal I is fed to an evaluation circuit 22, which is connected to a changeover switch 23. The fiducial mark 24 is also operatively coupled to a fiducial mark sensor 25, which generates a fiducial mark signal BM. The signal BM is fed to an evaluation circuit 26 which is a time control element. Evaluation circuit 2
6 controls the changeover switch 23 over time so that the changeover switch 23 is at the position shown in the figure during the time interval A and is at a position not shown during the time interval B.
In the illustrated position, the changeover switch 23 is connected to the first comparator 27. The comparison input of the comparator 27 is connected to the threshold value _I1 .
When taking a position not shown, selector switch 23
is connected to the second comparator 28. This comparator 28 is supplied with a threshold value I ₂ . Delay elements 29, 30 are connected to the comparators 27, 28, in which the output signals of the comparators 27, 28 are held until the evaluation of the combustion chamber cycle is completed. In the embodiment shown in FIG. 4, the NOR gate 3 has delay elements 29 and 30 connected to its input side.
1 performs a logical connection. In that case
The NOR gate 31 is connected to the first switch 32,
The delay element 30 is connected to a second switch 33 in addition to the NOR gate 31. switch 32, 33
is used to bridge the resistors 34 and 35. Resistors 34, 35 together with another resistor 36 form a voltage divider, which is supplied with a control current IR. The voltage drop across the resistors 34-36 is supplied to an operating member of the internal combustion engine, for example a fuel supply 37 or an ignition device 38.

The apparatus shown in FIG. 4 operates as follows.

Due to the time control of the evaluation circuit 26, the measurement signal I
is the threshold value in the comparator 27 in the time interval A.
I ₁ and in time interval B the comparator 28
is compared with the threshold _I2 . During normal combustion as shown in FIG. 1, the measured signal exceeds the threshold value I ₁ in the time interval A and falls below the threshold value I ₂ in the time interval B. Correspondingly, the output of the comparator 27 has a logic value of 1.
At the output of the comparator 28, a logical value 0 occurs. Therefore, NOR gate 31 is blocked and switches 32, 33 remain in the positions shown. Resistors 34, 35 are therefore bridged and the voltage drop of control current I _R across resistor 36 generates a control signal to, for example, fuel supply device 37.

When the internal combustion engine reaches its operating limits, the flame propagation velocity slows down. In this case, the measurement signal exceeds the threshold value I ₁ in the time interval A and also exceeds the threshold value I ₂ in the time interval B, as shown in FIG. Therefore, switch 32 remains closed since NOR gate 31 is blocked. However, since the logical value of comparator 28 transitions from 0 to 1, switch 33 is opened. Therefore, the resistance 35 is added to the resistance 36, and the control signal to the fuel supply device 37 becomes larger. As a result, the amount of fuel supplied also increases.

As shown in FIG. 3, when combustion stops, the logical values of both comparators 27 and 28 become 0. Then, the NOR gate 31 is controlled to be conductive, and
Switch 32 is opened. Resistor 34 has a larger resistance value than resistor 35, for example, and therefore the total resistance value becomes even larger. As a result, a larger amount of fuel is supplied than during slow combustion.

The configuration of resistors 34, 35, and 36 is merely an example and is provided to increase the amount of fuel supplied when the operating conditions of the engine change.
Therefore, in addition to this, the characteristics of the operating member can be changed in response to changes in the operating state of the engine as described above.

FIG. 5 shows a modification of the device shown in FIG.
In this case, when the operating states "slow flame propagation combustion" and "combustion stop" are reached, two memories, e.g. flip-flops 39, 40
is set. flip flop 39,40
is called periodically by the microcomputer 41 to which the reference signal BM is supplied. The microcomputer 41 checks the state of the flip-flops 39, 40 at the instants determined by the signal BM, which correspond to the time intervals A, B and are adapted to the individual control elements 37, 38.

FIG. 6 shows another embodiment of the device according to the invention. In this device, the measurement signal I and the threshold value I ₁ ,
The comparison with I ₂ is performed in the microcomputer 41. For this purpose, the measurement signal I is
In converter 42, it is converted to be suitable for processing on a microcomputer. That is, converter 4
At the output of 2, the instantaneous value of the measurement signal I appears as a digital signal. Microcomputer 41
examines the output signal of the converter 42 periodically, ie at times corresponding to the time intervals A, B, depending on the signal BM. This instantaneous value is then compared with threshold values I ₁ and I ₂ stored in memory. Measurement signal I
One of the operating members 37, 38 is controlled in the manner described above depending on whether or not the thresholds I ₁ and I ₂ have been reached.

In the above embodiment, delayed combustion was detected by a positive signal in time interval B, and combustion stop was detected by a 0 signal in both time intervals A and B. However, this logical combination is shown merely as an example. Therefore, the 0 signal in time interval A and the positive signal in time interval B may be used to detect fuel with a slow frame propagation velocity, and the 0 signal in time interval A alone may be used to detect fuel stoppage. It is also possible to detect.

Furthermore, other known control devices can be used instead of the operating members 37, 38, which have been given by way of example only in the above embodiments. For example, in a preferred embodiment of the invention an integral motion control device is used.
Furthermore, it is also possible to control the operating members 37, 38 together. Therefore, the ignition point and the combustion supply amount as well as the composition of the exhaust gas can be controlled simultaneously.

[Brief explanation of drawings]

Figure 1 is a diagram showing the value of the measurement signal I of the combustion chamber sensor during normal combustion, Figure 2 is a diagram showing the value of signal I during combustion with a slow flame propagation velocity, and Figure 3 is a diagram showing the value of signal I during combustion with a slow flame propagation velocity. A diagram showing the value of signal I at the time of stop; FIG. 4 is a block circuit diagram of the first embodiment of the device according to the present invention; FIG. 5 is a partially modified embodiment of the embodiment shown in FIG. 4. FIG. 6 is a block circuit diagram of a second embodiment of the device according to the invention. 10, 11, 12, I...Measurement signal, 20...
Combustion chamber sensor, 21... Combustion chamber wall, 22, 26...
...Evaluation circuit, 23...Selector switch, 24...Reference mark, 25...Reference mark sensor, 27,
28... Comparator, 29, 30... Delay element, 31... NOR gate, 32, 33... Switch, 34, 35, 36... Resistor, 37... Fuel supply device, 38... Ignition device, 39, 40...Flip-flop, 41...Microcomputer, 42...A/D converter, BM...Reference mark signal, _I1 , _I2 ...Threshold value, I _R ...Control current, A, B
...Time interval, ZZP...Ignition point, OT...Top dead center, α...Crankshaft angle.

Claims (1)

Claims: 1. Combustion chamber sensor 20, which supplies measuring signals 10, 11, 12 corresponding to the course of the combustion process in the internal combustion engine for adjusting the operating elements 37, 38 of the internal combustion engine, and a predetermined crankshaft. and a reference mark sensor 25 which generates a position-corresponding signal BM, in which case a time-controlled evaluation circuit 26 or a microprocessor 41 is used to generate a signal BM corresponding to the predetermined crank position OT. In an internal combustion engine control device, starting from a signal BM, two time intervals A and B are determined in each case, the first time interval A being a period corresponding to normal combustion, and the second time interval B being a period corresponding to normal combustion. The measurement signals 10 and 11 in the two time intervals A and B are set to a threshold value for the purpose of detecting combustion with a slow flame propagation velocity and combustion stoppage. An internal combustion engine control device characterized in that it compares I ₁ and I ₂ and further adjusts the settings of operating members 37 and 38 depending on whether or not the threshold values I ₁ and I ₂ are reached. . 2. The device according to claim 1, wherein the combustion chamber sensor 20 is an ion flow sensor. 3 A slow combustion of the flame propagation velocity is detected by the measurement signal exceeding the threshold value I ₂ in the second time interval B, and the measurement signal exceeds the threshold values I ₁ and I ₂ in the two time intervals A and B. 3. The device according to claim 1, wherein cessation of combustion is detected when the temperature decreases below the specified level. 4 When combustion with a slow flame propagation velocity is detected, the fuel supply device 37 increases the fuel supply amount by a first value, and when it detects that combustion has stopped, increases the fuel supply amount by a second value larger than the first value. The device according to any one of claims 1 to 3, which increases the amount of fuel supplied by a value of . 5 A changeover switch 23 is provided which is controlled as a function of the reference mark sensor 25, via which the measurement signals 10, 11, 12 are
5. The device according to claim 1, wherein the comparators 27, 28 are connected to an operating member via a logical coupling circuit. 6 Signal memory 29 for comparators 27 and 28,
30, 39, 40 are connected, and these signal memories 29, 30, 39, 40 are periodically called by a microcomputer 41, and the microcomputer 41 controls the operating member. Device. 7 Measurement signals 10, 11, 12 are sent to A/D converter 4
2 directly to the microcomputer 41, which receives the measurement signals 10, 11, 12 and the predetermined threshold value I ₁ , at the time they are derived from the signal BM of the reference mark sensor 25.
Claims 1 to 2 that periodically compare I ₂ with
Apparatus according to any of paragraph 4.