JPH08261033A - Deposit detection device for engine - Google Patents

Abstract

PURPOSE: To confirm deposit without disassembling an engine body by stopping fuel injection in an optional one cylinder in a specified time, afterward restarting it, and comparing the number of revolution of an engine until the air-fuel ratio at this time reaches a target value with a reference value for determining the presence of deposit. CONSTITUTION: Deposit adhesion is determined, for instance, for a first cylinder of a straight type four-cylinder engine. In such a case, operation of an injector 103 of the first cylinder is stopped. After a specified time passed, the operation of the injector 103 is restarted. In the case that the deposit does not present, a rich signal indicating the rich air-fuel ratio of the first cylinder is output by means of an O2 sensor when a piston of the fourth cylinder is at a compression top dead center four times after re-injection. In the case that deposit presents, the signal is output when the piston of the fourth cylinder is at a compression top dead center six times after re-injection. The deposit is detected by means of an ECU 105, paying attention to difference between injection times from the time changeover to a rich state from a lean state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine deposit detecting device for detecting whether or not deposits of hydrocarbons (HC) and the like are present inside an engine.

[0002]

2. Description of the Related Art An engine burns fuel and uses a force generated at the time of combustion as a power source. When the engine is used for many years, a deposit (so-called deposit) is generated. Examples of the deposits generated on the engine include
There are hydrocarbons (HC) and the like. Hydrocarbons (H
C) is due to the air-fuel mixture layer left unburned along the wall of the combustion chamber after the propagation of the flame, in other words, a portion of the fuel left unburned. The air-fuel mixture layer left unburned along the combustion chamber wall after propagation of the flame is a phenomenon caused by the fact that the air-fuel mixture near the wall is cooled by the combustion chamber wall and therefore did not burn before the flame arrived.

Of the air-fuel mixture layer left unburned in this manner, mainly hydrocarbons (HC) are intake surfaces which are the upper surface of the intake valve which is the intake valve of the engine and the intake holes around the upper surface of the intake valve. Deposits on the manifold as deposits. When deposits adhere, some of the fuel injected from the fuel injection part (injector) of the engine is absorbed by the deposits, and the air-fuel ratio originally required for the engine cannot be obtained. The power of the engine cannot be obtained.

In the case of an engine having deposits, a part of the fuel injected by the fuel injection unit is absorbed by the deposits at the time of starting the engine, so that the required air-fuel ratio cannot be obtained and it is difficult to start the engine. Also, problems such as unstable idling occur. As described above, the presence of the deposit causes various troubles to the engine, and therefore it is necessary to detect and remove the deposit.

In the past, however, since there was no device for detecting the presence or absence of deposits, in the event of a failure, diagnosis is first performed on other systems that are easy to inspect, and only when there is no abnormality in those systems, The engine body was disassembled and visually checked for the presence of deposits.

[0006]

However, according to the above conventional technique, in order to confirm the presence or absence of deposits,
Since the engine body needs to be disassembled, the number of man-hours required for the engine body and the devices around the body are large and large, and the work is not easy.

For example, if there is a problem in the system that can be easily diagnosed and it is intermittent,
Since the mechanic judges that there is no malfunction in the system or other easily diagnosable system, and spends a lot of man-hours to disassemble the engine and check the deposits, it may be the first time that a misdiagnosis is noticed. However, it was desired to be able to easily confirm the deposits so that unnecessary work is not performed.

Particularly, when a beginner mechanic who does not have sufficient knowledge about disassembling the engine performs the work of confirming the deposit, there is a fear that it may take more work than necessary, so that the deposit can be easily confirmed. Or a device was desired.

The present invention has been made in view of such conventional problems, and an object thereof is to make it possible to easily confirm the presence or absence of deposits without disassembling the engine body.

[0010]

In order to achieve the above object, an engine deposit detecting device according to a first aspect of the present invention is for detecting the engine speed and the engine speed detecting means for detecting the engine speed. Air-fuel ratio detection means installed in the exhaust system,
The fuel injection means provided for each cylinder for injecting fuel and the detection results of the rotational speed detection means and the air-fuel ratio detection means are input in accordance with a prestored control program, and the fuel injection means is operated. In an engine control device including control means for controlling, an air-fuel ratio changing means for arbitrarily changing the air-fuel ratio of the engine, and an air-fuel ratio of the engine via the air-fuel ratio changing means, When the fuel injection of any one cylinder is stopped for a certain period of time and then restarted to start the deposit detection, and the deposit detection is started by the deposit detection starting means, The air-fuel ratio is input from the air-fuel ratio detection means and compared with a predetermined target value, and the rotation speed detected by the rotation speed detection means and the reference value are compared until the air-fuel ratio reaches the target value. If the number of revolutions is equal to or higher than a reference value, a deposit determination unit that determines that there is a deposit in the one arbitrary cylinder and a determination result output unit that outputs the determination result of the deposit determination unit are provided. It is a thing.

According to a second aspect of the engine deposit detecting apparatus, the air-fuel ratio changing means, the deposit detection starting means and the deposit determining means are arranged in a control board of the engine control device. Is.

Further, in the engine deposit detecting device according to a third aspect of the present invention, the air-fuel ratio changing means, the deposit detection starting means, and the deposit determining means are arranged in a housing separate from the engine control device. It is used by connecting to the engine control device as needed.

[0013]

In the engine deposit detecting apparatus of the present invention (claim 1), the deposit detection starting means changes the air-fuel ratio of the engine through the air-fuel ratio changing means, and any one cylinder is operated through the control means. When the fuel injection is stopped for a certain time and then restarted to start the deposit detection, the deposit determination means inputs the air-fuel ratio from the air-fuel ratio detection means, compares it with a predetermined target value, and Until the fuel ratio reaches the target value, the rotation speed detected by the rotation speed detection means is compared with the reference value, and if the rotation speed is equal to or higher than the reference value, it is determined that there is a deposit in one of the cylinders. By outputting the determination result by the determination result output means, the presence or absence of deposits can be confirmed without disassembling the engine body.

According to the engine deposit detecting device of the present invention (claim 2), the air-fuel ratio changing means, the deposit detection starting means and the deposit judging means are the same as those of claim 1. By being arranged in the substrate, the presence or absence of deposits can be detected at any time as needed.

Further, in the engine deposit detecting device (claim 3) of the present invention, the air-fuel ratio changing means, the deposit detection starting means and the deposit determining means in claim 1 are different from the engine control device. It's located in another enclosure,
By using it by connecting to the engine control device as needed, the presence or absence of deposit can be detected by connecting the engine deposit detection device without changing the configuration of the conventional engine control device. Become.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The engine deposit detecting apparatus of the present invention will be described in detail below in the order of [First Embodiment] and [Second Embodiment] with reference to the drawings.

[Embodiment 1] First, regarding the engine deposit detecting apparatus of Embodiment 1, the construction of the engine deposit detecting apparatus, the deposit detecting principle of the present invention, and the operation of the engine deposit detecting process are in this order. explain.

Configuration of Engine Deposit Detection Device FIG. 1 shows a schematic configuration of an engine deposit detection device according to the first embodiment. In the first embodiment, the engine deposit detection device is installed in an engine control unit of an engine control device. It was installed in.

In the figure, reference numeral 101 designates an in-line four-cylinder engine which is a target of deposit detection.
A crank angle sensor 102, an injector 103, an O ₂ sensor 104, a water temperature sensor, an idle switch and the like are attached. The crank angle sensor 102 is the engine 1
The crank position and rotation speed of 01 are detected, and a binary pulse of high-low is output. By measuring the frequency of this pulse, it is possible to determine the rotational speed of the engine 101 and whether or not the piston of each cylinder is at the compression top dead center. The number of cylinders of engine 101 is not particularly limited.

The injector 103 is a fuel injection means for injecting fuel, and is provided for each cylinder. The O ₂ sensor 104 is installed in the exhaust pipe of the engine 101 and measures the oxygen concentration of the exhaust gas and is used as an air-fuel ratio detecting means. The output signal of the O ₂ sensor 104 makes the air-fuel ratio rich based on the theoretical air-fuel ratio. Or you can be lean.

The engine control unit 105 is
It is a microcomputer including an input / output port 106, a CPU 107, a ROM 108 and a RAM 109.
The engine control unit 105 receives signals from sensors such as a crank angle sensor 102, an O ₂ sensor 104, and a water temperature sensor, and operates actuators (not shown) based on these signals to control the engine 101. Along with the role, it also plays the role of the air-fuel ratio changing unit, the deposit detection starting unit, and the deposit determining unit of the engine deposit detecting apparatus of the first embodiment.

The engine warning light 110 is generally provided in a combination meter section (not shown) of a vehicle, and is a lamp for outputting a failure alarm based on the diagnosis result of the engine control device. In the first embodiment, when the engine control unit 105 determines whether or not there is a deposit, the engine warning light 110 is used as a determination result output unit that outputs the determination result.

The operating state of the engine 101 can be determined by a crank angle sensor 102 which detects the crank angle of the engine 101. Crank angle sensor 102
Detects the rotational position of each cylinder of the engine 101 and outputs the detection result as a binary pulse. The binary pulse outputs a high signal when the piston of each cylinder is located at the top dead center of compression and exhaust in each cylinder rotation of the engine 101, and the piston of each cylinder reaches the bottom dead center of expansion and intake. If there is, a low signal is output.

Further, it can be judged whether the air-fuel ratio of the engine 101 is the stoichiometric air-fuel ratio or not based on the measurement results of the crank angle sensor 102 and the O ₂ sensor 104. More specifically, a high signal output from the crank angle sensor 102,
Alternatively, in synchronization with the low signal, depending on whether the result detected by the O ₂ sensor 104 is rich, which is a state of rich oxygen, or lean, which is a state of thin oxygen, the engine 1
It is possible to determine whether the air-fuel ratio of the specific cylinder 01 is the stoichiometric air-fuel ratio.

Principle of Detecting Deposits of the Present Invention Next, the principle of detecting deposits of the present invention will be described.
Engine 101 deposits have been
By using, the deposits on the upper surface of the intake valve umbrella and on the intake manifold around the intake valve.

If deposits are deposited, the injector 10
Since a part of the fuel injected from No. 3 is adsorbed by the deposit, the air-fuel ratio originally required cannot be obtained. However, when the fuel injection amount of the injector 103 is constant, such as during idling after warming up of the engine 101 or during constant running, the fuel is sufficiently adsorbed to the deposit before that, and hence the deposit is not used thereafter. There is no problem that the adsorption of fuel due to is eliminated, the amount of fuel required by the engine 101 is supplied into the combustion chamber, and the required air-fuel ratio cannot be obtained.

However, at the time of starting the engine 101, the fuel has not been adsorbed in the deposit before that,
A part of the fuel injected at the time of start-up is adsorbed on the deposit, and the total amount required by the engine 101 (the total amount of the fuel injected from the injector 103) cannot be supplied to the combustion chamber. As a result, the engine 101 suffers from a trouble phenomenon such as a start failure or rough idle (idling is not constant).

Further, at the time of starting or accelerating, a part of the fuel usually adheres to the intake manifold or the umbrella of the intake valve as a wall flow and does not reach the combustion chamber. Therefore, in the engine control unit 105, it adheres to the wall flow. The amount of fuel is increased in consideration of the amount of fuel, but if there is a deposit on the umbrella of the intake manifold or intake valve, the surface area of the intake manifold or intake valve will increase by the amount of the deposit, and as a result, it will adhere to the wall flow. As the fuel increases, the amount of fuel required by the engine 101 is not supplied to the combustion chamber, resulting in trouble phenomena such as poor acceleration and breathing.

On the other hand, O for measuring the concentration of oxygen in the exhaust gas
_As shown in the characteristic diagram of FIG. 2, the _two- sensor 104 has a characteristic that when the air-fuel ratio is lean, the output is small and when the air-fuel ratio is rich, the output is large when the air-fuel ratio is lean.
Further, the output of the O ₂ sensor 104 changes greatly in the characteristics near the stoichiometric air-fuel ratio, and for example, when the engine is idling, a signal indicating rich or lean when the actual air-fuel ratio is the stoichiometric air-fuel ratio. Will be output.

Therefore, if the operation of the injector 103 of a specific cylinder is stopped when the output of the O ₂ sensor 104 is rich, the air-fuel ratio of that cylinder becomes thin, so that the exhaust gas of that cylinder contains O ₂ sensor. The O ₂ sensor 104 outputs a signal indicating lean only when the position 104 is passed. Then, the injector 10 stopped from this state
When the operation of No. 3 is restarted, the air-fuel ratio of the cylinder returns to the same state as before the stop, and the O ₂ sensor 104 again outputs a signal indicating rich.

Here, when there is no deposit in the cylinder,
The O ₂ sensor 10 can be operated with a small number of injections of the injector 103.
4. A signal indicating rich is output from No. 4, but if there is a deposit, the fuel is adsorbed to the deposit, so that the O ₂ sensor 104 outputs a signal indicating that there is more than normal. This requires the number of injections of the injector 103.

Therefore, after the injector 103 of any one cylinder is stopped for a certain period of time and then restarted,
At that time, it is possible to detect whether or not there is a deposit in the corresponding cylinder based on the number of injections of the injector 103 until the rich output from the O ₂ sensor 104.

Here, a more specific description will be given with reference to FIG. FIG. 3 shows an example of the No. 1 cylinder. The injector 103 required for the output of the O ₂ sensor 104 to switch from lean to rich in the case where the deposit is attached to the No. 1 cylinder and the case where the deposit is not attached. FIG. 6 is an explanatory diagram showing a difference in the number of injections of the above.

As shown, the injector 10 of the first cylinder
When the operation of No. 3 is stopped, the O ₂ sensor 104 always outputs a lean signal indicating that the air-fuel ratio of the No. 1 cylinder is lean when the piston of the No. 4 cylinder reaches the compression top dead center. After that, when the injector 103 of the first cylinder is restarted, when the deposit is not accumulated, when the piston of the fourth cylinder has reached the compression top dead center four times after the re-injection, that is, of the first cylinder. When the injector 103 has injected four times, the O ₂ sensor 104 outputs a rich signal indicating that the air-fuel ratio of the first cylinder is rich. On the other hand, when the deposit is accumulated, when the piston of the fourth cylinder reaches the compression top dead center six times after re-injection, that is, when the injector 103 of the first cylinder injects six times, the O ₂ sensor 10
No. 4 outputs a rich signal indicating that the air-fuel ratio of the first cylinder is rich.

As described above, it can be seen that there is a difference in the number of injections until the O ₂ sensor 104 switches from lean to rich after fuel re-injection, depending on the presence or absence of deposits. The present invention focuses on the difference in the number of injections until switching from lean to rich, and detects the presence or absence of deposits.

Operation of Engine Deposit Detection Process Next, the engine deposit detection process will be described in detail with reference to the flowchart of FIG. First, it is confirmed by a power balance test whether or not the vehicle to be diagnosed is in a diagnosable state (S401). The engine deposit detection process cannot be performed unless the ignition system and injector system of each cylinder are normal. Therefore, each cylinder is inspected by the power balance test. If all cylinders are normal, the process proceeds to step S402, If the cylinder is not normal, terminate the process and inspect the defective part judged by the power balance test.

In step S402, each parameter is initialized. Parameter A is the O ₂ sensor 1 when any injector 103 among the injectors 103 arranged in each cylinder is re-injected from the stopped state.
Shows the number of reference signals of a specific one-cylinder that is injected by an arbitrary injector 103 until 04 determines that it is lean to rich, that is, the number of injections after re-injection of the injector 103 arranged in the specific one-cylinder that is stopped. ing.

The parameter B is a parameter for preventing the reference signal of the specific one cylinder, which has been once counted, from being erroneously counted again in the next loop. The parameter i indicates the number of a specific cylinder of the injector 103 to be stopped. In the first embodiment, i = 1 since the specific one cylinder is the first cylinder. It goes without saying that the other cylinder may be used instead of the first cylinder.

The parameter x indicates the number of the cylinder whose piston is at the compression top dead center when the exhaust gas of the i-th cylinder (first cylinder in the first embodiment) passes through the O ₂ sensor 104. In the case of the first embodiment, the exhaust gas of the first cylinder is O ₂
When passing through the sensor 104, the piston is at the compression top dead center in the fourth cylinder, so x = 4 is set.

In step S403, the injector 10
Adjust the amount of fuel to be injected at 3 and change it to 3% rich from the theoretical air-fuel ratio. This step is a step for stabilizing the output of the O ₂ sensor 104 which is unstable near the stoichiometric air-fuel ratio, and by setting the output to 3% richer than the stoichiometric air-fuel ratio, the output of the O ₂ sensor 104 becomes a rich signal. This is so that It should be noted that although the richness is set to 3% in the present embodiment, it is not particularly limited to this and any value may be used as long as the output of the O ₂ sensor 104 is stable.

Next, in step S404, when the exhaust gas after 3% rich stoichiometric air-fuel ratio passes through the O ₂ sensor 104, whether the output of the O ₂ sensor 104 actually is on the rich side to decide. Here, the O ₂ sensor 104
If the output is rich, the process proceeds to step S405, where O
_{2 If} the output of the sensor 104 is not rich, the target deposit cannot be detected even if the following steps are executed, so the processing ends. It should be noted that, without terminating the processing here, for example, after performing processing such as re-adjusting the amount of fuel injected by the injector 103 and changing the stoichiometric air-fuel ratio to 5% rich, the determination in step S403 is performed again. It may be executed.

In step S405, the operation of the injector 103 of the i-th cylinder is stopped for 10 seconds. That is,
The fuel injection of the injector 103 of the i-th cylinder is stopped for 10 seconds. Therefore, at this time, the O ₂ sensor 104 outputs lean when the exhaust gas of the i-th cylinder passes.

Next, in step S406, the injector 103 of the i-th cylinder is operated to start fuel injection again. Then, in step S407, after re-injection, O ₂
The output of the sensor 104 is monitored, and it is determined in step S408 whether the output of the O ₂ sensor 104 is lean. If it is lean, the process proceeds to step S411, and if it is not lean, step S409.
Go to.

In step S409, the O ₂ sensor 104
Is not lean (that is, rich), it is determined whether or not there is a reference signal for the xth cylinder. If there is no reference signal for the x-th cylinder, the re-injected cylinder is other than the first cylinder, and it can be understood that the rich signal is due to the exhaust gas other than the first cylinder.
Return to 07. On the contrary, if there is the reference signal of the x-th cylinder, the re-injected cylinder is the i-th cylinder, and it can be understood that it is the rich signal due to the exhaust gas of the i-th cylinder.
Go to 0.

As a condition for reaching step S410, a rich output from the O ₂ sensor 104 is obtained when the number of injections (parameter A) of the injector 103 after re-injection is 4 times or less by steps S411 to S416 described later. Since it is the case that there was, it can be determined here that there is no deposit. Therefore, in step S410, an OK signal (for example, continuous lighting) is displayed via the engine warning light 110, and the process ends.

In step S411, it is determined whether or not the reference signal of the xth cylinder is detected. Where x
If there is no reference signal for the No. cylinder, it is understood that the re-injected cylinder is other than the No. i cylinder, and it is a rich signal due to exhaust gas other than the No. i cylinder, so in step S412, the reference signal for the same No. cylinder x is set to 1 The parameter B is reset to 0 as a part of the process for counting only once, and the process returns to step S407.

On the other hand, when the reference signal of the x-th cylinder is detected in step S411, the injected cylinder is the i-th cylinder, and it is known that the lean signal is due to the exhaust gas of the i-th cylinder. Therefore, in step S413, As a part of the processing for counting the reference signal of the same x-th cylinder only once, it is determined whether or not the parameter B = x,
If the parameter B = x, it is determined that the reference signal of the corresponding xth cylinder has already been counted once, and step S
Return to 407.

On the contrary, if the parameter B is not x, it is judged that the counting of the reference signal of the corresponding xth cylinder has started, the parameter B is set to x in step S414, and the parameter A is set in step S415. 1 is added and the number of times of the reference signal of the xth cylinder is counted. In the first embodiment, the number of reference signals of the fourth cylinder, that is, the number of times the injector 103 has injected after re-injection is counted.

Next, in step S416, it is determined whether or not the numerical value (counting number) of the parameter A is larger than 5, which is a preset reference value. Here, if it is smaller than 5, the processing from step S407 onward is repeated again, and the output of the O ₂ sensor 104 is read again. The preset reference value 5 is a value set based on "4" which is the number of times until the injector 103 becomes rich after re-injection when there is no deposit on the engine 101, as shown in FIG. is there.

On the other hand, when the value of the parameter A is larger than 5, in other words, the number of times "4" until the engine 101 becomes rich after re-injection when there is no deposit is exceeded, so it is deposited in the i-th cylinder. It is determined that there is an object, and step S41
At 7, the NG signal (for example, blinking lighting) is displayed via the engine warning light 110, and the process ends.

In the first embodiment, steps S407-
The process of S417 is performed in 1 msec. Engine 1
The state of 01 is idling after warming up. When the parameter i = 1, the parameter x =
Although it is set to 4, when diagnosing other cylinders,
Table 1 shows the relationship between i and x.

[0052]

[Table 1]

As described above, according to the first embodiment, after the operation of the injector 103 of the i-th cylinder is stopped for a certain period of time, the operation of the injector 103 is restarted and the number of fuel injections is four times. In the meantime, the presence or absence of deposits in the i-th cylinder can be detected depending on whether or not the signal detected by the O ₂ sensor 104 becomes rich in the exhaust gas of the i-th cylinder. The presence or absence of deposits can be easily confirmed. Further, since the deposit can be automatically detected, the work can be easily performed regardless of the skill level of the mechanic.

[Second Embodiment] An engine deposit detecting device according to a second embodiment is configured as another device independent of the engine control device. That is, in the first embodiment of FIG. 1, the engine control unit 105 realizes the roles of the air-fuel ratio changing unit, the deposit detection starting unit, and the deposit determining unit of the engine deposit detecting device. A macro computer separate from the control unit 105 is arranged in an independent housing to form an engine deposit detection device, which is used by connecting to the engine control unit 105 as necessary.

FIG. 5 shows a schematic structure of the engine deposit detecting device 501 of the second embodiment. As shown in the figure, it comprises a deposit detecting control unit 502 and a display section 507 having a liquid crystal display screen. The deposit detection control unit 502 includes an input / output port 503 and a CPU 50.
4, a ROM 505 and a RAM 506. The rest of the configuration is the same as that of the first embodiment, so the description is omitted.

The above deposit detection control unit 50
2 connects the input / output port 503 to the input / output port 106 of the engine control unit 105 to capture signals from the crank angle sensor 102 and the O ₂ sensor 104 and control the injector 103 via the engine control unit 105. I do.

In the conventional vehicle, when the engine failure is diagnosed, the engine failure is diagnosed by connecting a dedicated engine failure diagnostic machine (consult device) to the diagnostic connector provided in the driver fuse box. Since a method of making a diagnosis by connecting a diagnostic machine to the engine control unit 105 has become common, the diagnostic connector can be used to easily connect the input / output port 503 and the input / output port 106. .

Of course, the engine deposit diagnosing device 501 of the second embodiment may be constructed by adding the engine deposit detecting process to the conventional engine failure diagnosing machine.

In the above configuration, the deposit detection control unit 502 executes the same operation as the flowchart of the first embodiment of FIG. 4, and the deposit detection result is displayed on the display unit 50.
By displaying in 7, it is possible to obtain the same effect as that of the first embodiment.

In the first and second embodiments described above, the inline 4-cylinder engine is taken as an example of the engine 101, but it goes without saying that the present invention can be implemented irrespective of the number of cylinders and the number of banks. is there.

[0061]

As described above, in the engine deposit detecting apparatus (claim 1) of the present invention, the deposit detection starting means changes the air-fuel ratio of the engine through the air-fuel ratio changing means and controls the engine. When the fuel injection in any one cylinder is stopped for a certain period of time through the means and then restarted to start the deposit detection, the deposit determination means inputs the air-fuel ratio from the air-fuel ratio detection means to a predetermined value. And the reference value is compared until the air-fuel ratio reaches the target value. If the rotation speed is equal to or higher than the reference value Since it is determined that there is a deposit and the determination result output means outputs the determination result, the presence or absence of the deposit can be easily confirmed without disassembling the engine body. In addition, since deposits can be automatically detected without disassembling the engine body, work can be performed easily regardless of the skill of the mechanic, and the number of work steps can be significantly reduced. it can.

In the engine deposit detecting device (claim 2) of the present invention, the air-fuel ratio changing means, the deposit detection starting means and the deposit judging means in claim 1 are controlled by the engine control device. Since it is arranged in the substrate, the presence or absence of deposits can be detected at any time as needed.

In the engine deposit detecting device (claim 3) of the present invention, the air-fuel ratio changing means, the deposit detection starting means and the deposit determining means in claim 1 are different from the engine control device. It's located in another enclosure,
Since it is configured to be used by connecting to the engine control device as needed, the presence or absence of deposits can be detected by simply connecting the engine deposit detection device without changing the configuration of the conventional engine control device. can do.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an engine deposit detection device according to a first embodiment.

FIG. 2 is an explanatory diagram showing characteristics of an O ₂ sensor.

FIG. 3 is an explanatory diagram showing the difference in the number of injections of the injector required to switch the output of the O ₂ sensor from lean to rich when deposits are attached to the cylinder and when deposits are not attached. .

FIG. 4 is a flowchart showing an operation of deposit detection processing of the engine of the present invention.

FIG. 5 is a schematic configuration diagram of an engine deposit detection device according to a second embodiment.

[Explanation of symbols]

Reference Signs List 101 engine 102 crank angle sensor 103 injector 104 O ₂ sensor 105 engine control unit 110 engine warning light 501 engine deposit detection device 502 deposit detection control unit 507 display unit

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G05B 23/02 302 7531-3H G05B 15/02 A

Claims (3)

[Claims] 1. A rotation speed detection means for detecting the rotation speed of an engine, an air-fuel ratio detection means installed in an exhaust system for detecting an air-fuel ratio, and each cylinder for injecting fuel. An engine control device comprising fuel injection means and control means for controlling the fuel injection means by inputting the detection results of the rotation speed detection means and the air-fuel ratio detection means according to a prestored control program, Air-fuel ratio changing means for arbitrarily changing the air-fuel ratio of the engine, the air-fuel ratio of the engine is changed through the air-fuel ratio changing means, and the fuel injection of any one cylinder is performed for a certain period of time through the control means. After the deposit detection is started by the deposit detection starting means for restarting the deposit detection after the stop, and when the deposit detection is started by the deposit detection starting means, air-fuel ratio is detected by the air-fuel ratio detecting means. The ratio is input and compared with a predetermined target value. Until the air-fuel ratio reaches the target value, the rotational speed detected by the rotational speed detecting means is compared with a reference value. For example, a deposit detection means for an engine, comprising: deposit determination means for determining that there is a deposit in any one cylinder; and determination result output means for outputting a determination result of the deposit determination means. apparatus. 2. The engine deposit according to claim 1, wherein the air-fuel ratio changing unit, the deposit detection starting unit, and the deposit determining unit are arranged in a control board of the engine control unit. Detection device. 3. The air-fuel ratio changing means, the deposit detection starting means, and the deposit determining means are arranged in a housing separate from the engine control device, and are connected to the engine control device as necessary. The deposit detecting device for an engine according to claim 1, wherein the deposit detecting device is used.