JPH045701Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention detects misfires in each cylinder from the rate of change in exhaust temperature based on input signals from exhaust temperature sensors installed in each cylinder of an internal combustion engine. ) for a misfire detection device for an internal combustion engine.

<Conventional technology> Conventionally, for example, detection of a misfire in a diesel engine is performed by
It is done as follows. That is, each cylinder of a diesel engine is equipped with an exhaust temperature sensor that detects the exhaust temperature, and detection signals from these sensors are input to a measuring device or recorder and displayed and recorded as a measured value. If there is a misfire, that cylinder will not ignite, and the temperature rise rate of the exhaust gas will slow down. Therefore, the driver should look at the above measured values and compare and consider the exhaust temperature difference between cylinders or the exhaust temperature of each individual cylinder. to determine whether there is a misfire.

<Problems to be solved by the invention> However, the above-mentioned conventional misfire detection method for diesel engines does not require determining whether the exhaust gas temperature of each cylinder exceeds the value indicated by the measurement value displayed on the measuring instrument, etc.
Because the engine relies primarily on the experience of experts familiar with diesel engines who operate the engine, it is necessary to have an expert constantly check the actual measurement data of exhaust temperature in order to maintain operation, which saves labor and manpower during engine operation. It has the disadvantage of not being able to be standardized, and it also has the disadvantage of being susceptible to errors because it is made by humans.

Furthermore, in the conventional misfire detection method described above, the presence or absence of a misfire is determined based only on the exhaust temperature of each cylinder at a certain point in time or the exhaust temperature difference between cylinders, so a misfire cannot necessarily be detected immediately after startup. In addition, the accumulation of unburned gas due to a misfire cannot be detected, and therefore, the detection of a misfire is delayed, resulting in serious failure or damage to the engine. In other words, if a large amount of unburned gas discharged from a misfiring cylinder and accumulated in the exhaust pipe 5, supercharger 6, flue 7, etc. shown in Fig. 1 ignites and explodes, these engine parts will be destroyed. It's obvious.

Therefore, the purpose of this invention is to automatically detect misfiring cylinders at an early stage by checking the rate of increase in exhaust gas temperature of each cylinder immediately after engine startup, and to prevent engine damage due to misfires. An object of the present invention is to provide a misfire detection device for an internal combustion engine that can contribute to labor saving and efficiency of operation.

<Means for Solving the Problems> In order to achieve the above object, the misfire detection device for an internal combustion engine of the present invention uses an exhaust temperature sensor provided in each cylinder of the internal combustion engine, and an ignition cylinder sensor for a certain period of time immediately after startup. storage means for storing a lower limit value of the rate of change in exhaust gas temperature; and rate-of-change calculation means for calculating the rate of change in the exhaust gas temperature of each cylinder during a certain period of time immediately after the activation based on the input signal from the exhaust temperature sensor; a determining means for comparing and determining the calculated rate of change with the lower limit value; and when the determining means determines that the calculated rate of change is less than the lower limit value, a signal indicating a misfire is sent together with a symbol representing the cylinder number. The present invention is characterized by comprising an output means for outputting the output.

<Operation> Now, assume that a misfire occurs in a certain cylinder of the internal combustion engine immediately after startup. Then, the exhaust gas temperature of the cylinder is detected by the exhaust gas temperature sensor and input as a detection signal to the rate of change calculation means. The change rate calculation means calculates the change rate of the exhaust gas temperature of the cylinder for a certain period of time immediately after startup based on the input detection signal, and the discrimination means calculates the change rate of the exhaust gas temperature of the cylinder for a certain period of time immediately after startup, and the determination means calculates the change rate of the exhaust gas temperature of the cylinder for a certain period of time immediately after startup, and the determination means calculates the change rate of the exhaust gas temperature of the cylinder for a certain period of time immediately after startup, and the determination means calculates the change rate of the exhaust gas temperature of the cylinder for a certain period of time immediately after startup, and the determination means calculates the change rate of the exhaust gas temperature of the cylinder for a certain period of time immediately after starting. Compare the rate of change in the exhaust gas temperature of the ignition cylinder over a certain period of time with the lower limit value,
Discern. In this case, the cylinder is not ignited, and the rate of change (increase rate) of the exhaust gas temperature is determined to be less than the lower limit value, so that the output means outputs a signal indicating a misfire together with the cylinder number. On the other hand, input signals from the exhaust temperature sensors of other ignited cylinders are also processed in the same manner as described above.
In this case, since the cylinder is ignited, the determining means determines that the rate of change in exhaust temperature is greater than or equal to the lower limit value,
The output means does not output any signal.

<Example> Hereinafter, the present invention will be explained in detail with reference to the illustrated example.

FIG. 1 is a schematic diagram of a diesel engine equipped with the misfire detection device of the present invention, and 1 is a diesel engine;
Reference numerals 2, 2, . . . indicate an exhaust temperature sensor consisting of a thermocouple or a temperature measuring resistor provided in each cylinder of the diesel engine 1 to detect the exhaust gas temperature, and 3 indicates a storage means, a rate of change calculation means, and a discrimination means, which will be described later. and an output means, a computer as a misfire detection device that performs predetermined calculations based on the detection signal input from the exhaust temperature sensor 2; 4 is a display that displays information regarding cylinder misfires output from the computer 3; device, 5 is an exhaust pipe connected to each cylinder, 6
is a supercharger provided in this exhaust pipe 5, and 7 is a flue connected to this supercharger 6.

The storage means of the computer 3 stores a lower limit value and an upper limit value of the rate of change in the exhaust gas temperature of the ignition cylinder during a predetermined fixed period of time immediately after engine startup.
That is, as shown in Fig. 2, when the engine starts at time _t0 , the exhaust temperature T of the ignition cylinder increases as shown by the solid line in the figure, and the exhaust temperature of the misfired cylinder increases as shown by the dashed line in the figure because there is no combustion. As in, there is almost no increase. Therefore,
The average rate of increase dT/dt in the exhaust temperature of normally ignited cylinders during a certain period of time (for example, several seconds) from time t ₁ to t ₂ immediately after startup is determined by experiment, and its lower limit value δ ₁ and upper limit value δ are calculated. ₂ (see Figure 3) is stored in the storage means. On the other hand, the rate of change calculation means of the computer 3 calculates the rate of change dTi of the exhaust gas temperature Ti (i: cylinder number) of each cylinder during the certain period of time ( _t1 to t2) based on the input signal from the exhaust temperature sensor ₂ . /
dt is determined, and the determination means is the determined rate of change dTi/
The magnitude of dt and the lower limit value δ ₁ and upper limit value δ ₂ stored in the storage means are compared and determined. That is, the rate of change dTi/dt obtained moment by moment for the above-mentioned fixed time for the time series data input from each exhaust temperature sensor 2.
It is determined whether or not the change rate dTi/dt is in the region of δ ₁ to _{δ 2} indicated by diagonal lines in FIG. Display device 4 displays the signal together with a signal representing the cylinder number i.
On the other hand, if it is determined that the rate of change dTi/dt exceeds the upper limit value _δ2 , the output means similarly outputs a signal representing "excessive fuel supply".

The operation of the misfire detection device, ie, the computer 3, having the above configuration will be described below with reference to the flowchart shown in FIG.

Now, diesel engine 1 is at time t ₀ (see Figure 2)
When the engine is started, time series data of the exhaust temperature can be read from the exhaust gas temperature sensor 2 of each cylinder into the computer 3 in step S1 for a certain period of time from time _t1 to time _t2 immediately after the start. The rate of change calculating means of the computer 3 calculates the rate of change dTi/dt of the time-series data from each cylinder moment by moment in step S2, and the determining means first calculates the rate of change dTi/dt as determined in step S3. The magnitude is compared and determined with the lower limit value δ ₁ stored in advance in the storage means. and,
If it is determined that the rate of change dTi/dt is less than the lower limit value δ ₁ (dTi/dt<δ ₁ ), there is no rise in the predetermined exhaust temperature, so the process proceeds to step S5, and the output means outputs a signal indicating "misfire". It is output to the display device 4 along with a signal representing the cylinder number i, and the display device 4 displays this. If it is determined that the rate of change dTi/dt is greater than or equal to the lower limit value δ ₁ (dTi/dt≧δ ₁ ), step S4 Proceed to. In step S4, the change rate dTi/dt is then compared and determined with respect to the pre-stored upper limit value _δ2 .
If it is determined that dTi/dt>δ ₂ , the rise in exhaust temperature is excessive, so the process proceeds to step S6, where the output means outputs a signal indicating "excessive fuel supply" to the display device 4 in the same way as described above, and displays this. On the other hand, dTi/
If it is determined that dt≦δ ₂ , it is determined that the increase in exhaust gas temperature is appropriate and no display is performed.

In this way, the cylinder in which the misfire has occurred is automatically discovered within a short period of time immediately after startup, and is immediately displayed on the display device 4 together with the cylinder number, so that unburned gas due to the misfire is prevented from entering the exhaust pipe 5, etc. Countermeasures can be taken before a large amount of gas accumulates, and damage to engine parts due to explosion of accumulated unburned gas can be effectively prevented. In addition, since the computer 4 automatically determines the presence or absence of a misfire based on experimental data given in advance, there is no need for experts to constantly check measured data as in the past, which saves labor and manpower for engine operation. Of course, the reliability of the calculation and determination can be improved. Furthermore, in the above embodiment, even if the rate of increase in exhaust gas temperature exceeds the upper limit value _δ2 , the display device 4
Since this information is displayed together with the cylinder number, there is an advantage that oversupply of fuel can be detected early.

Incidentally, in the above embodiment, in the case of misfire or excessive fuel supply, only the display device 4 displays the information, but it is also possible to receive a signal from the output means of the computer 3 and sound an alarm buzzer or the like.

<Effects of the invention> As is clear from the above explanation, the misfire detection device for an internal heat engine of the invention detects the rate of change in the exhaust gas temperature of each cylinder during a certain period of time immediately after startup based on the input signal from the exhaust temperature sensor. is calculated using a rate of change calculation means,
When the determined rate of change is compared and determined by the determining means with a lower limit value of the rate of change in the exhaust gas temperature of the ignition cylinder over the above-mentioned certain period of time stored in advance in the storage means, and the rate of change is determined to be less than the lower limit value. Since the output means outputs a signal indicating a misfire together with a signal indicating the cylinder number, a general driver, not an expert, can determine whether or not a cylinder misfire has occurred due to an abnormal rate of change in exhaust temperature. This can be easily and accurately determined immediately after startup, making it possible to prevent engine damage due to explosions of unburned gas due to misfires, greatly contributing to labor savings and efficiency in engine operation.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a diesel engine equipped with the misfire detection device of the present invention, Fig. 2 is a diagram showing the change in exhaust temperature of the ignition cylinder and the misfire cylinder over time, and Fig. 3 is the rate of change of the exhaust temperature of the ignition cylinder. FIG. 4 is a flowchart showing the process flow of the misfire detection device. 1... Diesel engine, 2, 2... Exhaust temperature sensor, 3... Computer, 4... Display device, 5
……Exhaust pipe.

Claims (1)

[Scope of utility model registration request] An exhaust temperature sensor provided in each cylinder of the internal heat engine, a storage means for storing a lower limit value of the rate of change in the exhaust gas temperature of the ignition cylinder during a certain period of time immediately after startup, and an input signal from the exhaust temperature sensor. a rate of change calculation means for calculating the rate of change in the exhaust gas temperature of each cylinder during a certain period of time immediately after the start-up, and a determining means for comparing and determining the calculated rate of change and the lower limit value;
A misfire detection device for an internal combustion engine, comprising an output means for outputting a signal representing a misfire together with a signal representing a cylinder number when the determination means determines that the calculated rate of change is less than the lower limit value. .