JPH0355775B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a monitoring device for monitoring the operating state of an internal combustion engine such as a multi-cylinder diesel engine.

<Prior art> This type of monitoring device uses a cylinder-specific temperature sensor that detects the exhaust gas temperature of each cylinder of an engine, and a collective temperature sensor that detects the collective exhaust temperature at an exhaust gas pipe where exhaust gas from multiple cylinders joins. The operating state of the engine is identified based on the detection signals from each of the temperature sensors.

By the way, in conventional monitoring devices, abnormality is determined separately based on the detection signal from the cylinder-specific temperature sensor and the detection signal from the collective temperature sensor, so it is determined that an abnormality has occurred in a certain cylinder. In this case, it was unclear whether the abnormality was due to a misfire or abnormal combustion in the cylinder, or whether it was due to a failure of the temperature sensor itself. Therefore, it has been difficult to take appropriate countermeasures when determining an abnormality.

<Object of the invention> The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to accurately determine the mode of abnormality in each cylinder and to enable appropriate countermeasures to be taken. .

<Structure of the Invention> In order to achieve the above object, the present invention has the following features:
As shown in the functional block diagram in the figure, the exhaust temperature of each cylinder detected by cylinder temperature sensors A, . . . is compared with a reference value to determine which cylinder has an exhaust temperature abnormality. In response to the abnormality determination output from the separate abnormality determination means B and the cylinder-specific abnormality determination means B, the collective exhaust temperature detected by the collective temperature sensor C is compared with the collective exhaust temperature at another exhaust manifold pipe or a reference value. A monitoring device for a multi-cylinder engine is provided with an abnormality mode determining means D for determining whether the cylinder for which the exhaust temperature abnormality has been determined is an abnormality in the cylinder-specific temperature sensor A or combustion abnormality.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings. FIG. 2 is a configuration diagram of a monitoring device according to an embodiment of the present invention, and the monitoring device includes a six-cylinder engine 1, six cylinder-specific temperature sensors 2, ..., and two collective temperature sensors. 3a, 3
b, a first monitor circuit 4, and a second monitor circuit 5.

Each cylinder 6, . . . of the engine 1 is directly connected to an exhaust branch pipe 7, . The exhaust branch pipes 2 are grouped in groups of three and merge into one exhaust manifold pipe 8a, 8b (total two), and are connected to a turbocharger turbine chamber 9. Collective temperature sensors 3a and 3b are attached to 8b, respectively.
The detection signal of the cylinder-specific temperature sensor 2 is applied to a first monitor circuit 4, and the detection signal of the collective temperature sensors 3a, 3b is applied to a second monitor circuit 5.

The first monitor circuit 4 displays the temperature of each cylinder based on the detection signal of the temperature sensor 2 for each cylinder, and also determines whether an abnormality has occurred in any cylinder. It also functionally includes cylinder-specific abnormality determination means B shown in FIG. As shown in the block diagram of FIG. 3, this first monitor circuit 4 includes a CPU 10 and a ROM 1.
1, RAM 12, input/output port 13, and A/
It consists of a D converter 14 and a display 15, and detection signals from the temperature sensors 2 for each cylinder are input to the A/D converter 14 through amplifiers 16, respectively.

Further, the second monitor circuit 5 monitors the turbine output, etc. based on the detection signals of the collective temperature sensors 3a and 3b, and also determines the mode of abnormality for the cylinder in which it has been determined that the exhaust temperature is abnormal. It also functionally includes abnormality state determining means D shown in FIG. This second monitor circuit 5, as shown in the block diagram of FIG.
17, ROM 18, RAM 19, input/output port 20, A/D converter 21, and display 2
2, the detection signals of collective temperature sensors 3a and 3b are input to the A/D converter 21 through amplifiers 23a and 23b, respectively, and communication is performed with the first monitor circuit 4 through the input/output port 20. It's getting old.

Next, the operation of the above configuration will be explained based on the flowcharts of FIGS. 4 and 5.

The flowchart in Figure 4 shows the first monitor circuit that detects exhaust temperature abnormalities in each cylinder in the first monitor circuit.
Showing the routine. First, in step Sa1, the exhaust gas temperature of each cylinder 6, which is the detection signal of the cylinder-specific temperature sensor 2, is input.

Steps Sa2 to Sa8 are steps for detecting an abnormality in the exhaust gas temperature for each cylinder. In step Sa2, it is determined whether the exhaust temperature of each cylinder 6 is higher than a certain high temperature reference value (450°C), and this is determined. If "No" is determined in step Sa2, it is determined in the next step Sa3 whether the high temperature is higher than the variable high temperature reference value (average value of exhaust gas temperature by cylinder + 30℃), and "No" is determined in step Sa3. Once the decision is made, the steps
Sa4 determines whether the temperature is below the variable low temperature reference value (average exhaust temperature for each cylinder - 30°C).

If the judgments in steps Sa2 to Sa4 are all "No", that is, if there is no abnormality in the exhaust temperature, the process proceeds to step Sa8, where the flags Fa, Fb, and Fc set so far are cleared. Then, proceed to step Sa9, but if a “Yes” determination is made in any of steps Sa2 to Sa4, proceed to step Sa5, 6, or 7, and proceed to step Sa9.
The corresponding flags Fa, Fb, and Fc are set at Sa5, 6, and 7, and the process advances to step Sa9.

In step Sa9, a communication line is opened with the second monitor circuit 5 through the input/output port 13, and data regarding abnormality determination for each cylinder in the first monitor circuit 4 is transmitted to the second monitor circuit 5. Then, in step Sa10, the display 15 displays that it has been determined that the exhaust gas temperature is abnormal for one of the cylinders. At this stage, it is only known that exhaust temperature abnormality has been determined for one of the cylinders 6, and whether the abnormality is due to a misfire or abnormal fuel generation in that cylinder 6, or whether the temperature sensor 2 for each cylinder is It is unclear whether this was due to a malfunction.

The flowchart in FIG. 5 shows a second routine for determining the type of abnormality in the second monitor circuit 5. First, in step Sb1, the collective exhaust temperature from the collective temperature sensors 3a and 3b is input.

Then, in step Sb2, the first monitor circuit 4
It is determined whether or not an abnormal exhaust temperature for each cylinder has been detected. If there is communication from the first monitor circuit 4, this second routine is interrupted at any time to receive data from the first monitor circuit 4 regarding abnormalities in the exhaust gas temperature for each cylinder. Therefore,
If no abnormal data is transmitted from the first monitor circuit 4 before step Sb2, the judgment in step Sb2 is "No", and in that case, the step
Skipping to step Sb6, if abnormal data regarding any cylinder 6 is transmitted from the first monitor circuit 4, the judgment in step Sb2 is "Yes".
In that case, proceed to step Sb3.

In step Sb3, two collective temperature sensors 3
The collective exhaust gas temperatures from a and 3b are compared, and it is determined whether there is a difference of 30°C or more between the two collective exhaust temperatures. If a misfire or abnormal combustion actually occurred in cylinder 6, where the exhaust temperature was abnormal,
There should be a large difference between the collective exhaust temperature of the exhaust manifold pipes 8a and 8b leading to the cylinder 6 and the collective exhaust temperature of the other exhaust manifold pipes 8b and 8a. If abnormal combustion has not occurred and cylinder temperature sensor 2 is malfunctioning,
The exhaust gas temperatures of all cylinders 6 are averaged, and there should be no large difference between the two collective exhaust temperatures. Therefore, if it is determined in step Sb3 that there is no difference of more than a certain amount between the two collective exhaust temperatures, this means that the cylinder temperature sensor 2 has failed, and in that case, the process moves to step Sb4. Then, a flag Fd indicating a failure of the cylinder temperature sensor 2 is set. On the other hand, if it is determined in step Sb3 that there is a difference of more than a certain amount between the collective exhaust gas temperatures, this means that the cylinder-specific temperature sensor 2 is normal and that a misfire or abnormal combustion has actually occurred in the cylinder 6. In that case, proceed to step Sb5 and set a misfire or abnormal combustion flag Fe. When either flag Fd or Fe is set, the state of the abnormality is displayed on the display 22 in step Sb6.

In the above embodiment, by utilizing the fact that there are two exhaust manifold pipes 8a and 8b and each of them is provided with a manifold temperature sensor 3a and 3b, both the manifold temperature sensors
The mode of abnormality was determined by comparing the collective exhaust gas temperatures from a and 3b with each other. A value obtained by adding or subtracting a certain value) may be set, and the mode of abnormality may be determined by comparing this reference value with the collective exhaust gas temperature. By comparing the collective exhaust gas temperature with the reference value in this way, the present invention can also be implemented in a monitoring device for a multi-cylinder engine having only one exhaust pipe.

<Effects of the Invention> As described above, according to the present invention, an abnormality in the exhaust gas temperature is detected for any cylinder by the cylinder-specific abnormality determination means, and the abnormality state determination means in the next stage detects the abnormality based on the collective exhaust temperature. Since this aspect is determined, it is possible to determine whether a misfire or abnormal combustion is actually occurring in the cylinder with the abnormal exhaust temperature, or whether the temperature sensor is malfunctioning, and appropriate countermeasures can be taken.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a configuration diagram of an embodiment of the present invention, and FIG. 3 is a block diagram of the first and second monitor circuits.
FIG. 4 is a flowchart showing the abnormality determination operation in the first monitor circuit, and FIG. 5 is a flowchart showing the abnormality state determination operation in the second monitor circuit. 1... Engine, 2... Cylinder temperature sensor, 3a,
3b... collective temperature sensor, 4... first monitor circuit, 5... second monitor circuit.

Claims (1)

[Scope of Claims] 1. A cylinder-specific temperature sensor that detects the exhaust gas temperature of each cylinder of the engine, and a polymerization temperature sensor that detects the collective exhaust temperature at an exhaust manifold where exhaust gas from a plurality of cylinders joins, In a monitoring device for a multi-cylinder engine that identifies the operating state of the engine based on detection signals from each temperature sensor, the exhaust temperature of each cylinder is compared with a reference value to determine whether an abnormal exhaust temperature is detected for any cylinder. a cylinder-by-cylinder abnormality determining means for determining whether a cylinder-by-cylinder abnormality determining means has occurred, and comparing the collective exhaust temperature with the collective exhaust temperature in another exhaust manifold pipe or a reference value in response to the abnormality determination output from the cylinder-by-cylinder abnormality determining means; A monitoring device for a multi-cylinder engine, comprising: abnormality mode determining means for determining whether the cylinder in which the exhaust temperature abnormality has been determined is an abnormality in a cylinder-specific temperature sensor or an abnormality in combustion.