JPH0344651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for diagnosing failure of an exhaust valve of a diesel engine based on the CO value leaked while the exhaust valve is closed.

[Prior Art] Conventionally, a device shown in FIG. 5 has been employed as a means for diagnosing a failure in an exhaust valve of a diesel engine. That is, in Fig. 5, 1 is a diesel engine, 2a to 2f are cylinders, 3a to 3f are indicator sockets, 4a is a pressure pick-up attached to the indicator socket 3a of No. 1 cylinder 2a, and 4b is an indicator of No. 2 cylinder 2b. A pressure pickup is attached to the pickup 3b, 6 is an oscilloscope, and 5a and 5b are electric wires connecting the pickups 4a and 4b to the oscilloscope 6, respectively.

FIG. 6 shows an acupressure chart recorded on the oscilloscope 6, in which the solid line is an example of a normal acupressure chart, and the broken line is an example of an abnormal acupressure chart.

If the performance value of diesel engine 1 shows an abnormality, for example, if the exhaust temperature rises or the fuel efficiency worsens, collect a shiatsu chart and compare it with the standard value. If the overall performance value is low, there is an abnormality in the exhaust valve. Diagnose as yes. As a method of comparison, Indicator Kotoku 3
This is done by connecting the strain gauge type pressure pickups 4a and 4b attached to the oscilloscopes 4a and 3b to a two-channel oscilloscope 6, and superimposing the images displayed on the oscilloscope 6.

In other words, the shiatsu diagram for No. 2 cylinder 2b is now No.
If the acupressure diagrams of the other cylinders 2c to 2f except for the No. 1 cylinder 2a are substantially the same, the acupressure diagram of the No. 2 cylinder 2b is diagnosed as a standard value, and this is as shown by the solid line in FIG. 6. When the acupressure diagram of the No. 1 cylinder 2a is superimposed on this acupressure diagram and they match, it is diagnosed that there is no abnormality in the exhaust valve of the No. 1 cylinder 2a. If the exhaust valve of No. 1 cylinder 2a malfunctions, the gas inside the cylinder will leak toward the exhaust pipe even when the valve is closed, so the shiatsu chart will look like a broken line, and the pressure will be lower than in a normal case. Diagnose as abnormal.

[Problems to be Solved by the Invention] However, with the above-mentioned conventional device, since the two images are compared visually, judgment is subject to subjectivity, and since the images are small, judgment cannot be made unless there is a fairly large difference. Because strain gauge type pickups have temperature drift, they have poor accuracy in low pressure areas, which is an important factor in determination.

Due to these reasons, the accuracy was low, and there was a problem that could not be determined unless it was a fairly major failure.

The present invention aims to eliminate subjective judgment and provide a highly accurate exhaust valve failure diagnosis device for a diesel engine.

[Means for Solving the Problems] In the present invention, the sampling valve installed at the cylinder outlet of the diesel engine is opened only while the exhaust valve is opened in the first operation, and the sampling valve is opened in the second operation. A controller that opens the sampling valve during the combustion period and carbon monoxide CO in the exhaust gas collected by opening the sampling valve.
A CO analyzer that analyzes CO and the CO obtained in the first operation.
A comparator that calculates the value A, calculates the CO value B obtained in the second operation, and compares the respective CO values A and B. If the CO value B≦A, it is displayed as normal, and if B>A, it is displayed as normal. The present invention is characterized by comprising an output device that displays an abnormality.

[Function] In a diesel engine, if the exhaust valve is damaged, gas inside the cylinder will leak from the combustion chamber to the exhaust pipe even when the exhaust valve is closed. During the combustion period when the exhaust valve is closed, this leaking gas contains a large amount of unburned components, and among these unburnt components, carbon monoxide (CO) can be analyzed at low cost and with high precision.
If CO is captured at the right time and analyzed with a CO analyzer, it is possible to diagnose the exhaust valve failure.

Therefore, according to the present invention, a sampling valve is installed at the cylinder outlet, first, the exhaust gas is sampled during the period when the exhaust valve is open, and its CO is analyzed. When the exhaust valve inside is closed, the exhaust gas is collected and analyzed for CO.
Let the CO value at that time be B. Compare A and B,
If B≦A, the exhaust valve is diagnosed as normal, and if B>A, it is diagnosed as abnormal. This allows diagnosis of exhaust valve failure.

[Example] The present invention will be described below based on an example shown in FIGS. 1 to 4.

In Figure 1, 1 is a diesel engine, 2a~
2f is a cylinder, 13 is an exhaust pipe, 14a to 14f
15a to 15f are exhaust gas intake ports provided in the middle of each branch pipe 14a to 14f, and 16 is a branch pipe (cylinder outlet) that connects each cylinder 2a to 2f and the exhaust pipe 13. 17 is an electromagnetic sampling valve, a CO analyzer,
18 is a cord that connects the sampling valve 16 and the CO analyzer 17, 19 is a controller that opens and closes the sampling valve 16, 20 is a cord that connects the sampling valve 16 and the controller 19, 21 is a rotation angle sensor, and 22 functions as a comparator. a computer, 23 a cord connecting the rotation angle sensor 21 and the computer 22, 24 an input device, 2
5 is an output device.

FIG. 2 is a detailed view of the vicinity of the mounting location of the sampling valve 16, where 30 is an exhaust valve, 31 is a combustion chamber, and 3
2 is a piston, and 33 is a fuel injection valve.

FIG. 3 is a diagram explaining the opening/closing timing of the sampling valve 16, and FIG. 4 is a flowchart of software for diagnosing a failure of the exhaust valve 30.

Next, the operation of this embodiment will be explained.

The rotation speed of the engine 1, the landing timing, the combustion period, the opening timing (EVO) of the exhaust valve 30, the closing timing (EVC) of the exhaust valve 30, etc. are input into the input device 24 of the computer 22, and the controller 19 is activated. Set as the valve control signal for the first operation.

Then, as shown in FIG. 3, the sampling valve 16 closes from the opening timing (EVO) to the closing timing (EVC) of the exhaust valve 30, and the exhaust gas during this period is sampled and sent to the CO analyzer 17. . The CO analyzer 17 analyzes carbon monoxide CO in the collected exhaust gas, and sends this value to the computer 22. Let this value be A.

The controller 19 is then set to the valve control signal for the second operation. Then, as shown in FIG. 3, the sampling valve 16 opens when the exhaust valve 30 is closed during the combustion period to sample the exhaust gas in the branch pipe 14a. This collected exhaust gas is
The CO in the exhaust gas is sent to a CO analyzer 17, and the CO in the collected exhaust gas is analyzed in this CO analyzer 17. This value is sent to computer 22. Let this value be B.

Since the computer 22 has a comparison function, it compares the analysis values A and B, and causes the output device 25 to output the comparison result.

Generally speaking, the exhaust valve 30
The gas within the combustion chamber 31, which is closed during the combustion period, contains a large amount of CO.

Therefore, if the exhaust valve 30 is normal, there will be no leakage from the exhaust valve 30, which is closed during the combustion period, and the gas in the combustion chamber 31 will flow out toward the branch pipe 14a to which the sampling valve 16 is attached. Therefore, the value of B is the same as the value of A. On the other hand, if there is an abnormality in the exhaust valve 30 and the airtightness is impaired, the gas in the combustion chamber 31 will be transferred to the branch pipe 1 during the combustion period.
4a, and the value of B becomes higher than the value of A. Utilizing such a phenomenon, failure diagnosis of the exhaust valve 30 can be performed by incorporating software as shown in FIG. 4 into the computer 22. That is, necessary information is input into the input device 24 of the computer 22, the CO value A obtained by the first operation is determined, the CO value B obtained by the second operation is determined, and these A and B are calculated. Compare the
If A and B are equal, it is determined to be normal, and if B is larger than A, it is determined to be abnormal, and the result is output to the output device 25.
to be displayed.

[Effects of the Invention] As explained above, according to the present invention, all exhaust valve failures are handled by mechanical and electrical devices, so there is no need for human judgment, accurate judgment can be made by objective judgment, and it is possible to quickly Can make decisions. in this case,
Carbon monoxide in exhaust gas is used as a determining factor.
Since the analysis is performed using a CO analyzer, the accuracy is high and the equipment is inexpensive. Furthermore, if the accuracy of the exhaust valve gradually deteriorates, there is an advantage that by recording the temporal change in the difference between the B value and the A value, it is possible to predict a failure of the exhaust valve from the change.

[Brief explanation of drawings]

Figures 1 to 4 show an embodiment of the present invention, with Figure 1 being an overall configuration diagram, Figure 2 being a sectional view showing the cylinder part of the engine, and Figure 3 explaining the opening/closing timing of the sampling valve. FIG. 4 is a flowchart explaining the processing procedure of a computer, FIG. 5 is a conventional configuration diagram, and FIG. 6 is a characteristic diagram explaining conventional diagnosis. 1... Diesel engine, 2a-2f... cylinder, 13... exhaust pipe, 14a-14f... branch pipe, 16... sampling valve, 17... CO analyzer, 19... controller, 22... computer, 24...Input device, 25...Output device, 30
...Exhaust valve, 31...Combustion chamber.

Claims (1)

[Scope of Claims] 1. A sampling valve installed downstream of the exhaust valve in the exhaust passage of a diesel engine; a first operation causes the sampling valve to open when the exhaust valve is opened, and a second operation causes the sampling valve to open during combustion. a controller that opens a sampling valve when the exhaust valve of the exhaust valve is closed; a carbon monoxide analyzer that analyzes carbon monoxide CO in the exhaust gas sampled by opening the sampling valve; a comparator that calculates the obtained CO value A and also calculates the CO value B obtained in the second operation, and compares these respective CO values A and B;
An exhaust valve failure diagnosis device for a diesel engine, comprising: an output device that displays normal when the compared CO value is B≦A, and displays abnormal when B>A.