JPH0584834B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for diagnosing failure of a fuel injection valve in a multi-cylinder diesel engine.

[Prior art] Generally, the fuel injection device of a diesel engine has a fifth
It is configured as shown in the figure. i.e. 1
01 is a piston of the engine, 102 is a cylinder cover of the engine, 103 is a combustion chamber of the engine, and 100 is a fuel injection valve that injects fuel into the combustion chamber 103. Further, 104 is a valve holder that holds the fuel injection valve 100, 105 is a needle valve that is housed in the valve holder 104 and has a conical tip, 106 is a fuel reservoir, and 107 is the needle valve 10.
5 is a valve seat, 108 is a spring that presses the needle valve 105, 109 is a fuel injection hole for injecting fuel into the combustion chamber 103, and 110 is a fuel reservoir 10.
This is a fuel introduction pipe that leads fuel to 6.

120 is a fuel injection pump, 121 is a camshaft driven by a crankshaft (not shown);
22 is a cam formed on this camshaft 121;
3 is a plunger operated by the cam 122, 124 is a refueling port for supplying fuel, 125
126 is a fuel supply pipe, 126 is a fuel supply tank, and 127 is a fuel discharge valve.

To explain the operation of such a fuel injection device,
When the camshaft 121 rotates due to engine rotation, the cam 122 rotates, so the fuel injection pump 12
0 plunger 123 moves up and down. When the fuel supply port 124 is closed by the side surface of the plunger 123 while the plunger 123 moves upward, fuel is pressurized on the upper surface of the plunger 123. Therefore, the fuel is transferred from the fuel discharge valve 127 to the fuel introduction pipe 11.
0 to the fuel reservoir 106 of the fuel injection valve 100. This increases the fuel pressure in the fuel reservoir 106, and this fuel pressure pushes the needle valve 105 upward against the force of the spring 108.

When the piston 101, which is raised by the rotation of the engine, reaches near the top dead center, the needle valve 105 is pushed up by the fuel pressure in the fuel reservoir 106 of the fuel injection valve 100, and the fuel in the fuel reservoir 106 is pushed up. Injection hole 1 from between needle valve 105 and valve seat 107
The fuel is injected into the combustion chamber 103 through 09. Therefore, fuel is injected into the combustion chamber 103, which is pressurized and heated due to the raised piston 101, and the injected fuel is combusted.

The plunger 123 of the fuel injection pump 120 further rises, and the notch 123a of the plunger 123
When the portion reaches the refueling port 124, the fuel that was at the top of the plunger 123 is released to the refueling tank 126 through the refueling port 124, so that the pressure in the fuel reservoir 106 of the fuel injection valve 100 decreases.
The needle valve 105 descends under the pressure of the spring 108, seats on the valve seat 107, and finishes the injection.

In a fuel injection device having such a function, the needle valve 105 may become damaged due to long-term engine operation.
This may damage the contact surfaces of the valve seat 107, resulting in poor oil-tightness between these contact surfaces. If such oil tightness occurs, the fuel injection pressure may decrease, oil leakage may occur, or combustion gas may leak into the injection valve 10.
This can cause problems such as water entering the engine, resulting in a significant drop in engine performance.

Therefore, it is desirable to detect poor contact between the needle valve 105 and the valve seat 107, that is, a malfunction of the fuel injection valve 100, at an early stage.

[Problems to be Solved by the Invention] However, in the past, there was no method to determine fuel injector failure, that is, poor oil tightness, during operation of a diesel engine. The method used was to remove the fuel injector and check it with a hand tester.

However, such a method is not only time-consuming, but also has the disadvantage that individual variations occur in the determination of measurement, making it impossible to expect a reliable and highly accurate diagnosis.

The present invention aims to provide a failure diagnosis device for a fuel injection valve in a multi-cylinder diesel engine that is easy to diagnose, has no individual variation in judgment, and has high accuracy.

[Means for Solving the Problems] The present invention includes a sampling valve for sampling exhaust gas installed in an exhaust passage downstream of an exhaust valve of a cylinder equipped with a fuel injection valve to be subjected to failure diagnosis; a controller that opens the sampling valve while the exhaust valve is open in a first operation and opens the sampling valve while the exhaust valve is closed in a second operation; A CO analyzer that analyzes the concentration of carbon monoxide CO in the exhaust gas sampled by opening the sampling valve, and calculates the CO concentration value A obtained in the first operation,
A comparator that calculates the CO concentration value B obtained in the second operation and compares the respective CO concentration values A and B;
It is characterized by comprising an output device that displays normal when the concentration value A is almost the same as the CO concentration value B, and displays abnormal when A>B.

[Function] In a multi-cylinder diesel engine, if the fuel injection valve of a certain cylinder is damaged, the fuel in the fuel injection valve leaks into the combustion chamber through the injection hole when the fuel injection valve is in the closed state, and this leakage occurs. Since the fuel does not mix well with air, a large amount of unburned gas (raw gas) is produced.
occurs. Carbon monoxide (CO), which can be analyzed inexpensively and accurately among the components of this unburned gas, can be captured at the right time when the exhaust valve is closed and when it is open, and analyzed with a CO analyzer. This makes it possible to diagnose failures.

That is, according to the present invention, a sampling valve for sampling exhaust gas is installed in the exhaust passage downstream of the exhaust valve of a cylinder equipped with a fuel injection valve to be subjected to failure diagnosis, and first, a sampling valve for sampling exhaust gas is installed during the opening period of the exhaust valve. Collect the exhaust gas and analyze its CO concentration, take the CO concentration value at that time as A, then collect the exhaust gas when the exhaust valve is closed, analyze the CO concentration, and calculate the CO concentration value at that time. Let be B. Compare A and B, and if A and B are almost equal, the fuel injection valve is diagnosed as normal, and A>B
If so, diagnose it as abnormal. This makes it possible to diagnose a failure of the fuel injection valve.

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

In Fig. 1, 1 is a multi-cylinder diesel engine;
2a to 2f are cylinders, 13 is an exhaust pipe serving as a collecting pipe, and 14a to 14f are cylinders 2.
a branch pipe connecting a to 2f and the exhaust pipe 13;
15a to 15f are exhaust gas intake ports provided in the middle of each branch pipe 14a to 14f, 16 is an electromagnetic sampling valve for exhaust gas sampling attached to the exhaust gas intake port 14a, 17 is a CO analyzer, and 18 is the sampling valve mentioned above. Pipe connecting 16 and CO analyzer 17,
19 is a controller that opens and closes the sampling valve 16; 20 is the sampling valve 16 and the controller 1;
Cord connecting 9, 21 is rotation angle sensor, 2
2 is a computer with a function as a comparator;
23 is a cord connecting the rotation angle sensor 21 and the computer 22, 24 is an input device, and 25 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, 103 is a combustion chamber,
101 is a piston, and 100 is a fuel injection valve similar to the conventional one. The sampling valve 16 is located downstream of the exhaust valve 30 and is attached to the branch pipe 14a, and the branch pipe 14a is assembled into the exhaust pipe 13.

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.

The operation of this embodiment will be explained using these drawings.

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 Figure 3, the sampling valve 16 opens (ON) between the opening timing (EVO) and closing timing (EVC) of the exhaust valve 30, and the exhaust gas during this period is sampled for CO analysis. Send to a total of 17 people. The CO analyzer 17 analyzes the carbon monoxide CO concentration in the collected exhaust gas, and the value of this CO concentration is sent to the computer 22.
send to Let this CO concentration value be A.

The controller 19 is then set to the valve control signal for the second operation. Then, the sampling valve 16 detects the valve closing timing (EVC) as shown in FIG.
It opens (ON) between the valve opening timing (EVO) and the exhaust gas in the branch pipe 14a during this period is sampled. This collected exhaust gas is sent to the CO analyzer 17.
The CO concentration in the exhaust gas collected by the CO analyzer 17 is analyzed. This CO concentration value is sent to the computer 22. Let this CO concentration value be B.

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

Normally, when the oil tightness of the fuel injection valve 100 in the combustion chamber 103 to be diagnosed has deteriorated, fuel leaks from between the needle valve 105 and the valve seat 107, causing incomplete combustion and normal operation. Compared to the case of the fuel injection valve 100, the component of carbon monoxide CO increases.

In a multi-cylinder engine, the CO concentration in the exhaust gas in the branch pipe 14a while the exhaust valve 20 is closed is:
This branch pipe 14a is an exhaust pipe 13 corresponding to a collecting pipe.
Another combustion chamber 1 with a normal fuel injection valve via
CO in the branch pipe of the other combustion chamber 103, which is equipped with a normal fuel injection valve because it communicates with the branch pipe of 03.
It can be considered that it is close to the concentration. Therefore, exhaust valve 2
0 is closed, the sampling valve 16 is opened to sample the exhaust gas in the branch pipe 14a, and the CO concentration value in this exhaust gas is analyzed by the CO analyzer 17. this
This is the CO concentration value B when the CO concentration is normal.

Further, while the exhaust valve 30 is open, exhaust gas flows from the combustion chamber 103 to the branch pipe 14a, so if the sampling valve 16 is opened during this time, the combustion chamber equipped with the fuel injection valve 100 to be diagnosed If the exhaust gas in the chamber 103 can be sampled, and incomplete combustion has occurred in this case, the carbon monoxide CO component will increase compared to the case of a normal fuel injection valve 100, and this CO concentration value will be The CO concentration value will be A when it is abnormal.

As mentioned above, if the fuel injection valve 100 has, for example, poor oil tightness, the A value will be high.
When comparing and B, the relationship A>B is established.

Using this phenomenon, the computer 22
By incorporating software as shown in FIG. 4 into the exhaust valve 30, a failure diagnosis of the exhaust valve 30 can be performed. That is, the input device 24 of the computer 22
Input the necessary information to obtain the CO concentration value A obtained in the first operation, obtain the CO concentration value B obtained in the second operation, compare these A and B, and If B is equal, it is determined to be normal, and A is equal to B.
If it is larger, it is determined that there is an abnormality, and the result is displayed on the output device 25.

[Effects of the Invention] As explained above, according to the present invention, failures of fuel injection valves can be detected entirely by mechanical and electrical devices, so diagnosis is not only simple, but also
Accurate judgments can be made based on objective judgments, and moreover, judgments can be made quickly. In this case, carbon monoxide in the exhaust gas is used as the determining material and analyzed with a CO analyzer, resulting in high accuracy and inexpensive equipment. In addition, the accuracy of the fuel injector may gradually deteriorate, and in such cases, by recording the temporal change in the difference between the B value and the A value, it is possible to predict fuel injector failure from the change. There are advantages such as being able to

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention, FIG. 1 is an overall configuration diagram of a multi-cylinder diesel engine, FIG. 2 is a sectional view showing the cylinder part of the engine,
FIG. 3 is a diagram illustrating the opening and closing timing of the sampling valve, FIG. 4 is a flowchart illustrating the processing procedure of a computer, and FIG. 5 is a diagram illustrating the overall configuration of a conventional fuel injection system. 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, 100...Fuel injection valve, 101...
Piston, 103... combustion chamber, 105... needle valve,
107...Benza.

Claims (1)

[Scope of Claims] 1. A sampling valve for sampling exhaust gas installed in an exhaust passage downstream of an exhaust valve of a cylinder equipped with a fuel injection valve to be subjected to failure diagnosis; a controller that opens the sampling valve when the exhaust valve is opened, and opens the sampling valve when the exhaust valve is closed in a second operation; A carbon monoxide analyzer that analyzes the concentration of carbon CO, calculates the CO concentration value A obtained in the first operation above, calculates the CO concentration value B obtained in the second operation, and calculates the CO concentration of each of these. a comparator that compares the values A and B; and a comparator that compares the values A and B;
An output device that displays that the fuel injection valve is normal when the concentration values B are almost equal to each other, and displays that the fuel injection valve is abnormal when A>B; Fault diagnosis device.