JP2009074410A - Method and device for detecting clogging of air cleaner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine fuel feed system having a speed density control system for fuel injection control which enables a predetermined person to easily recognize the clogging of an air cleaner when the air cleaner is clogged. <P>SOLUTION: In this method of detecting the clogging of an air cleaner by an electronic control unit 10A which is an engine fuel injection control device in which the speed density control system is adopted to determine a fuel injection amount by predicting an intake air amount from the detected engine rotational speed and intake pipe pressure values, the difference between the averaged value and the minimum value of the intake pipe pressures which are continuously detected is calculated. When the difference is at least smaller than a predetermined clogging determination value, the air cleaner 2 is determined to be clogged, and a trouble code lamp 100 serving as a display means is lit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air cleaner clogging detection method and detection apparatus, and more particularly to an air cleaner clogging detection method for detecting and displaying an air cleaner clogging in an engine fuel supply system employing a speed density system. And a detection apparatus.

  In a general-purpose engine having a relatively simple structure and many small ones, as described in Japanese Patent Laid-Open No. 5-240105, the engine rotation speed is increased because the air flow sensor is relatively expensive and also serves as an intake resistance. A speed density type fuel injection control in which the fuel injection amount is determined by estimating the intake air amount from the speed and the intake pipe pressure value is often used.

  Further, such a general-purpose engine is often used in a situation where a large amount of dust or fine dust is mixed in the intake air, such as when used in a lawn mower. For this reason, the air cleaner provided on the inlet side of the intake pipe of the engine is clogged with dust and dirt, and troubles that affect engine performance frequently occur. This trouble is caused by the air cleaner being clogged, the intake pipe is throttled upstream of the throttle valve, the amount of intake air is reduced, and the engine output is reduced.

  Referring to FIG. 7 showing a layout diagram of a conventional engine system based on the control method described above, in an engine system in which an intake pipe pressure sensor 12 is disposed only on one cylinder 6 side of a two-cylinder general-purpose engine, When the speed density method is adopted in the fuel injection control executed by the control unit 10B, the air cleaner 2 is clogged and the pressure in the air cleaner 2 portion is lowered even with the same intake air amount, and the intake pipe pressure other than the intake stroke is also reduced. Therefore, the average value of the intake pipe pressure is lower than when the air cleaner 2 is not clogged.

  Therefore, the calculated air density is reduced, and the amount of fuel injected from the injectors 7 and 8 is calculated to be small. As a result, the air-fuel ratio tends to become lean. FIG. 6 is a graph showing the relationship between the intake pipe pressure and the air-fuel ratio when the air cleaner inlet is artificially closed to create a state when the air cleaner is clogged. As the air cleaner clogs progresses, the air cleaner becomes empty. It can be seen that the fuel ratio becomes lean.

In addition, the air cleaner is clogged, so that the engine output is also reduced, and the original performance of the engine cannot be exhibited. For this reason, it is desirable that a driver, an operator, or the like recognize this in a short time from the occurrence of clogging of the air cleaner and immediately eliminate the cause of the clogging.
JP-A-5-240105

  The present invention is intended to solve the above-described problems. When an air cleaner is clogged in an engine fuel supply system that uses a speed density control system for fuel injection control, The problem is to make it possible for a person to recognize immediately.

  Therefore, the present invention provides a method for detecting clogging of an air cleaner in a fuel injection control device for an engine that employs a speed density control system that determines a fuel injection amount by estimating an intake air amount from the detected engine rotation speed and intake pipe pressure value. Then, the difference between the average value and the minimum value of the intake pipe pressure detected continuously is calculated, and at least when this difference is smaller than a predetermined clogging judgment value, it is judged that the air cleaner is clogged, The display is performed by a predetermined display means.

  Utilizing the fact that the difference between the average value and the minimum value of the intake pipe pressure becomes smaller than the normal value as the clogging of the air cleaner progresses, the clogging is calculated and set in advance through experiments. When it becomes smaller than the judgment value, it is judged that the air cleaner is clogged, so that it can be detected in a short time from the occurrence of clogging and given to a predetermined person such as a driver / worker. It becomes possible to inform reliably.

  Further, in this case, in addition to the difference in the intake pipe pressure being smaller than the clogging judgment value, the minimum value of the intake pipe pressure at that time is a predetermined high value corresponding to the minimum value of the intake pipe pressure during high load operation. If it is determined that the air cleaner is clogged only when the load judgment value is larger than the load judgment value, the average value and minimum value of the intake pipe pressure are higher than when the air cleaner is clogged when the engine speed is high. Cases in which the difference is small can be excluded, and more accurate determination can be performed.

  In addition, the fuel injection control device is connected to the intake pipe pressure detecting means to continuously detect the intake pipe pressure and the storage means stores a clogging detection program for the air cleaner, and the air cleaner is connected to the air cleaner when detecting the clogging of the air cleaner. Display means for displaying the clogging state of the air cleaner, and the clogging detection device of the air cleaner is characterized in that the clogging detection method of the air cleaner described above is implemented. It can be detected by time and surely recognized by a predetermined person.

  According to the present invention, which determines the clogged state of the air cleaner using the difference between the average value and the minimum value of the detected intake pipe pressure, a predetermined person recognizes this immediately when the air cleaner is clogged. become able to.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  Referring to FIG. 1 showing an arrangement diagram of an engine system having an electronic control unit 10A, which is an air cleaner clogging detection apparatus for carrying out the air cleaner clogging determination method of the present embodiment, engine 1 is a two-cylinder general-purpose engine. Yes, branching intake pipes 5 and 6 extending from one air cleaner 2 are connected to the cylinders 3 and 4, respectively. In the intake pipe 6 connected to one cylinder 4, the intake pipe pressure is detected. The pressure sensor 12 is arranged to continuously output detection signals to the electronic control unit 10A.

  Further, the engine 1 is provided with a crank position sensor 13 so as to continuously output the engine rotation speed to the electronic control unit 10A. The electronic control unit 10A estimates the intake air amount using the detected intake pipe pressure value and the engine speed, and determines the fuel injection amount that realizes the optimum air-fuel ratio in a predetermined procedure based on the estimated intake air amount. It also serves as a fuel injection control device for executing fuel injection control by a so-called speed density control system that outputs a drive signal to 7 and 8.

  The electronic control unit 10A has the same configuration as that of a general fuel injection control device in hardware, but the content of the air cleaner clogging detection method executed by the air cleaner clogging detection program stored in the storage unit. It has a characteristic. Further, the electronic control unit 10A is connected with a failure code lamp 100 which is a display means for displaying the clogging state of the air cleaner. The electronic control unit 10A executes the clogging determination control of the air cleaner, which will be described in detail below. It is also characterized in that when it is determined that the air cleaner is clogged, it is output to the failure code lamp 100 and turned on.

  From the graph of FIG. 4 showing the waveform diagram of the intake pipe pressure when the engine is fully loaded in this engine system, it can be seen that the intake pipe pressure tends to be low throughout the area when the air cleaner is clogged. Usually, the area where the intake pipe pressure is low is considered as the intake stroke, but when the air cleaner is clogged, the area other than the intake stroke is also low, so the average value of the calculated intake pipe pressure is low and the average The difference between the value and the minimum value tends to be small.

  FIG. 5 is a graph showing the relationship between the average value and the minimum value of the intake pipe pressure when the air cleaner is clogged. From this graph, it can be seen that the difference between the average value and the minimum value of the intake pipe pressure becomes smaller as the air cleaner 2 becomes clogged. Utilizing this characteristic, the present invention is characterized in that the clogged state of the air cleaner is detected from the difference between the average value and the minimum value of the intake pipe pressure.

  FIG. 2 is a block diagram showing a procedure of air cleaner clogging determination control by the electronic control unit 10A which is the air cleaner clogging detection apparatus of the present embodiment.

  When the air cleaner clogging determination control is started, an intake pipe pressure average value Pav is obtained from the detected intake pipe pressure (A1), and an intake pipe pressure minimum value Pun is obtained (A2). Then, the difference between the intake pipe pressure average value Pav and the minimum intake pipe pressure value Pun is obtained, and this difference is compared with a predetermined clogging judgment value (A3). If this difference is larger than the clogging judgment value, Returning, if smaller, the first condition for determining whether the air cleaner is clogged is assumed, and the process proceeds to the next determination of the second condition.

  Then, the intake pipe pressure value minimum value Pun is compared with a predetermined high load determination value according to the minimum value of the intake pipe pressure during high load operation (A4), and the intake pipe pressure value minimum value Pun is larger. Only when it is determined that the air cleaner is clogged (A5), it is output to the fault code lamp and turned on (A6).

  Thus, in addition to the difference between the intake pipe pressure average value Pav and the minimum intake pipe pressure value Pun being smaller than the clogging judgment value, it is confirmed that the intake pipe pressure value minimum value Pun is larger than the high load judgment value. The reason for the determination is as follows.

  Referring to the graph of FIG. 3, this shows the intake pipe pressure when the throttle valve is at the idle opening, but the difference between the average value and the minimum value of the intake pipe pressure becomes smaller when the engine speed is high. Thus, when the air cleaner is clogged, it may be smaller than the difference between the average value of the intake pipe pressure at the full load and the minimum value. Further, the minimum intake pipe pressure value Pun at this time is lower than the minimum intake pipe pressure value Pun when the air cleaner is clogged. Therefore, in order to exclude this case in the clogging determination, it is a condition that the minimum intake pipe pressure value Pun at that time is larger than the predetermined high load determination value according to the minimum intake pipe pressure value Pun during high load operation. Is.

  The electronic control unit 10, which is a device for detecting clogging of the air cleaner, can detect clogging of the air cleaner in a short time accurately by performing such processing, and by turning on the fault code lamp, the driver, the operator, etc. The predetermined person can be surely recognized in a short time the clogged state of the air cleaner. Note that the clogging determination value and the high load determination value described above can be calculated as optimum values by a plurality of experiments or computer simulations, respectively, and may be set in advance in the clogging detection program of the air cleaner.

  In addition, the air cleaner detection device of the present embodiment uses an existing engine fuel injection control device that employs a speed density method, and additionally installs the air cleaner clogging detection program described above in software, In addition, it can be obtained simply by adding a fault code lamp, and the installation does not involve an excessive cost increase.

  As described above, regarding an engine fuel supply system that uses a speed density method for fuel injection control, according to the present invention, when an air cleaner is clogged, a predetermined person can reliably recognize this in a short time. It became so.

1 is a layout diagram of an engine system according to an embodiment of the present invention. The flowchart which shows the control procedure by the clogging detection apparatus of the air cleaner of this Embodiment. The graph which shows the average value and minimum value of the intake pipe pressure at the time of a throttle valve idling opening degree. A graph for comparing the fluctuation of the intake pipe pressure when the air cleaner is normal and when the air cleaner is clogged. The graph for comparing the difference of the average value of the intake pipe pressure according to the degree of clogging at the time of clogging of an air cleaner, and the minimum value. The graph which shows the fluctuation | variation of the air fuel ratio according to the degree of clogging when an air cleaner is clogged artificially. The layout of the engine system of a prior art example.

Explanation of symbols

1 Engine, 2 Air Cleaner, 3, 4 Cylinder, 5, 6 Intake Pipeline, 7, 8 Injector, 10A Electronic Control Unit, 12 Pressure Sensor, 13 Crank Position Sensor, 100 Fault Code Lamp

Claims (3)

  A method for detecting clogging of an air cleaner in a fuel injection control device of an engine that employs a speed density control system that determines a fuel injection amount by estimating an intake air amount from a detected engine rotational speed and an intake pipe pressure value. The difference between the average value and the minimum value of the detected intake pipe pressure is calculated, and at least when the difference is smaller than the predetermined clogging judgment value, it is judged that the air cleaner is clogged, and the predetermined display A clogging detection method for an air cleaner, characterized in that the occurrence of clogging is displayed by means.   In addition to the difference being smaller than the clogging determination value, the minimum value of the intake pipe pressure at that time is larger than a predetermined high load determination value corresponding to the minimum value of the intake pipe pressure during high load operation. 2. The method of determining clogging of an air cleaner according to claim 1, wherein it is determined that the air cleaner is clogged only in a case. The fuel injection control device connected to the intake pipe pressure detecting means for continuously detecting the intake pipe pressure and storing the air cleaner clogging detection program in the storage means, and the clogging detection of the air cleaner connected to the fuel injection control apparatus The air cleaner clogging detection apparatus according to claim 1 or 2, further comprising the display means for displaying an air cleaner clogging state at times.

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