JP2012041936A - Electronic control device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic control device of an engine with a simple structure, capable of automatically controlling the rotational speed and fuel injecting amount of the engine.SOLUTION: In the electronic control device of the engine having the stepping motor 20 opening and closing the throttle valve 13 and the electronic control unit 21 operating the target engine rotational speed setter 25 and the stepping motor 20 and controlling the rotational speed Ne and the fuel injecting amount Q of the engine, the electronic control unit 21 increases and decreases the pulse number input into the stepping motor 20 so as to match the rotational speed of the engine E to the target value, the electronic control unit 21 holds the map 32 showing the relation of the input pulse number to the stepping motor 20, the rotational speed and the fuel injecting amount of the engine, the fuel injecting amount Q is determined from the map 32 based on the pulse number and the rotational speed of the engine input into the stepping motor 20.

Description

  The present invention controls a stepping motor that opens and closes a throttle valve of a fuel injection type engine, and controls the number of input pulses to the stepping motor so as to control the opening and closing of the throttle valve. The present invention relates to an engine electronic control device including an electronic control unit for controlling a fuel injection amount.

  In a conventional engine control device, as disclosed in Patent Document 1 below, a choke valve and a throttle valve of a carburetor are operated by a centrifugal governor and an auto choke device.

JP 2006-242143 A

  However, when a fuel injection method without a choke valve is adopted for the engine, the conventional control device as described above cannot be adopted.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an engine electronic control device having a simple configuration capable of automatically controlling the fuel injection amount.

  In order to achieve the above object, the present invention provides a stepping motor that opens and closes a throttle valve of a fuel injection type engine, and increases and decreases the number of input pulses to the stepping motor to control the opening and closing of the throttle valve. And an electronic control unit for controlling the fuel injection amount in accordance with the number of pulses and the engine speed, wherein the electronic control unit includes the number of input pulses to the stepping motor, the engine speed, and A first feature is that a map showing the relationship between the fuel injection amounts is held, and the fuel injection amount is determined from the map based on the number of pulses to the stepping motor and the engine speed.

  According to the present invention, in addition to the first feature, the stepping motor and the throttle valve are connected via a reduction gear device that reduces the rotation of the stepping motor and transmits it to the throttle valve. A second feature is that the device is configured such that the reduction ratio increases with a decrease in the opening of the throttle valve.

  In addition to the first feature, the present invention further includes an engine temperature sensor that detects the temperature of the engine, and thirdly, the electronic control unit corrects the fuel injection amount in accordance with an output of the engine temperature sensor. It is characterized by.

In addition to the first feature, the present invention further includes an O ₂ sensor for detecting the O ₂ concentration in the exhaust gas of the engine, and the electronic control unit controls the fuel injection amount in accordance with the output of the O ₂ sensor. Correction is the fourth feature.

  According to the first aspect of the present invention, the electronic control unit holds a map indicating the relationship between the number of input pulses to the stepping motor, the engine speed, and the fuel injection amount corresponding to the throttle valve opening. Since the fuel injection amount is determined from the map on the basis of the number of input pulses to the motor and the engine speed, the control of the fuel injection amount can eliminate the need for a throttle sensor and simplify the configuration of the engine electronic control unit. it can.

  According to the second feature of the present invention, the amount of change in the opening of the throttle valve due to one input pulse to the stepping motor decreases as it goes to the low opening side of the throttle valve. The resolution of the throttle valve opening in the degree range (engine low load range) is improved. As a result, the engine speed and fuel injection amount can be precisely controlled in the engine low load range.

  According to the third feature of the present invention, during the warm-up operation of the engine, the fuel injection amount is increased, and a good warm-up operation of the engine can be ensured.

  According to the fourth aspect of the present invention, during operation at a high altitude where the atmospheric pressure is low, even when the air-fuel ratio of the intake air becomes rich due to a decrease in atmospheric pressure, the fuel injection amount is automatically reduced to automatically reach the appropriate air-fuel ratio. It can be controlled to stabilize the operation of the engine at high altitudes and contribute to low fuel consumption and exhaust purification.

1 is an overall schematic diagram of an electronic control device for a general-purpose engine according to the present invention. FIG. 2 is an enlarged sectional view taken along line 2-2 in FIG. 1. The flowchart which shows the learning operation | movement of the electronic control unit at the time of engine starting. Flowchart showing the procedure for the electronic control unit to control the engine speed during engine operation Flow chart showing the procedure for the electronic control unit to control the fuel injection amount during engine operation The relationship map of the number of input pulses to the stepping motor and the opening of the throttle valve. A relationship map of the number of input pulses to the stepping motor, engine speed, and basic fuel injection amount.

  Embodiments of the present invention will be described below on the basis of preferred embodiments of the present invention shown in the accompanying drawings.

  1 is an overall schematic diagram of an electronic control device for a general-purpose engine according to the present invention, FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1, and FIG. 3 is a flowchart showing a learning operation of the electronic control unit at the time of starting the engine. 4 is a flowchart showing a procedure for the engine speed control performed by the electronic control unit during engine operation, FIG. 5 is a flowchart for a procedure performed by the electronic control unit for controlling the fuel injection amount during engine operation, and FIG. FIG. 7 is a relationship map of the number of input pulses and the throttle valve opening, and FIG. 7 is a relationship map of the number of input pulses to the stepping motor, the engine speed, and the basic fuel injection amount.

  First, in FIG. 1, a fuel-injection general-purpose engine E is used as a power source for a work machine 10 such as a portable generator, snowplow, lawn mower, etc., and a throttle body is provided on one side of the cylinder head. 11 are joined. The throttle body 11 includes an intake passage 12 connected to the intake port of the engine E, and a valve shaft 13 a of a butterfly throttle valve 13 that opens and closes the intake passage 12 is rotatably supported by the throttle body 11. The throttle body 11 is provided with a fuel injection valve 14 that can inject fuel toward the intake port of the engine E. A fuel tank 15 is attached to the upper part of the engine E, and an electric type fuel tank 15 can be supplied to the fuel injection valve 14 by sucking and pressurizing the fuel stored in the tank during operation of the engine E. A fuel pump 16 is installed.

  An output shaft 20 a of a stepping motor 20 supported by the throttle body 11 is connected to the valve shaft 13 a of the throttle valve 13 via a reduction gear device 26. Therefore, the rotation of the output shaft 20a of the stepping motor 20 is decelerated by the reduction gear device 26 and transmitted to the valve shaft 13a to open and close the throttle valve 13.

  The operation of the electric pump 16, the fuel injection valve 14, and the stepping motor 20 is controlled by the electronic control unit 21 based on various operation information of the engine E. The various operation information of the engine E input to the electronic control unit 21 includes an on / off state of the engine switch 22, an engine speed Ne (hereinafter referred to as engine speed), and an opening degree of the throttle valve 13 (hereinafter referred to as engine speed). , The throttle valve opening), the temperature T of the engine E (hereinafter referred to as the engine temperature), the target engine speed Nt set by the operator, etc., and the engine speed to detect the engine speed Ne. Number sensor 23 and engine temperature sensor 24 for detecting engine temperature T (in the case of an air-cooled engine, the temperature of the engine body itself such as a cylinder head is detected, or in the case of a water-cooled engine, the temperature of a cooling water is detected. Is provided on the engine E. Further, a target engine speed setting means 25 is provided in the engine E or the work machine 10 in order to input the target engine speed Nt set by the operator to the electronic control unit 21.

  The stepping motor 20 is stepped by a DC pulse input from the electronic control unit 21. In this embodiment, the reference position of the throttle valve 13 is set to a fully open position, and 94 stepping motors 20 are moved from the fully open position to the stepping motor 20. When the DC pulse is input and the stepping motor 20 is stepped 94 times, the throttle valve 13 is rotated to the fully closed position. During this period, the number of pulses input to the stepping motor 20 is electronically controlled. It is counted by a pulse counter 29 built in the unit 21. Thus, the number of pulses counted by the pulse counter 29 from the reference position (fully opened position) of the throttle valve 13 is a numerical value indicating the opening degree of the throttle valve 13.

  As shown in FIG. 2, the reduction gear device 26 is configured such that its reduction ratio increases as the opening of the throttle valve 13 decreases. Specifically, the reduction gear device 26 includes a drive elliptic gear 27 fixed to the output shaft 20a of the stepping motor 20 and a drive elliptic gear 27 fixed to the valve shaft 13a and meshed with the drive elliptic gear 27. When the throttle valve 13 is in the fully closed state, the reduction gear ratio is maximized by meshing the small diameter portion of the drive elliptic gear 27 and the large diameter portion of the driven elliptic gear 28. As a result, as shown in a map 31 of FIG. 6, the amount of change in the opening of the throttle valve 13 with respect to the one-step operation of the stepping motor 20 (operation when the stepping motor 20 receives one pulse) is It decreases with going to the low opening side. The relationship map 31 between the number of input pulses and the throttle valve opening in FIG. 6 is installed in the electronic control unit 21.

Further, the basic fuel injection amount Q ₁ corresponding to the number of pulses and the engine speed Ne is shown in the map 32 of FIG. 7, and this map 32 is also installed in the electronic control unit 21.

  Next, the operation of this embodiment will be described with reference to the flowcharts shown in FIGS.

  When the engine switch 22 is turned on when the engine E is started, the electronic control unit 21 performs start learning according to the flowchart of FIG. That is, when the engine switch 22 is turned on in the first step S1, 94 + N DC pulses in the opening direction of the throttle valve 13 are input to the stepping motor 20 in the second step S2, thereby opening the throttle valve 13 fully. . Here, 94 + N DC pulses are input to the stepping motor 20 regardless of whether the throttle valve 13 is in the fully closed position or the intermediate opening position before starting the engine. This is because it rotates. If the throttle valve 13 is fully opened before the number of input pulses reaches 94 + N, the remaining input pulses are simply invalidated and the throttle valve 13 is kept fully open. Note that N is an excessive number of input pulses in consideration of slippage of the operation of the stepping motor 20, and for example, N = 3 to 5 is appropriate.

  Next, in the third step S3, the pulse counter 29 is set to zero so that the fully opened position of the throttle valve 13 is set to the reference position (initialization of the pulse counter 29). In the fourth step S4, the start of the engine E is permitted. Starting the engine at the fully open position of the throttle valve 13 is effective in improving the startability of the engine. If the fully closed position of the throttle valve 13 is set as the reference position, then a step of opening the throttle valve 13 to a predetermined starting opening (intermediate opening) is necessary, and the control becomes complicated accordingly.

  Next, when the operator starts the engine E by operating the starter, the electronic control unit 21 operates the stepping motor 20 according to the flowchart of FIG. The number is controlled to the target rotational speed Nt set by the operator.

  That is, the target engine speed Nt set by the target engine speed setting means 25 is read in the fifth step S5, and in the sixth step S6, the actual engine speed Ne (hereinafter referred to as the engine speed Ne) is output from the output of the engine speed sensor 23. The actual engine speed Ne is read), the target engine speed Nt−α = the lower limit target engine speed Ntmin is set in the seventh step S7, and the target engine speed Nt + α = the upper limit target engine speed is set in the eighth step S8. Ntmax is set, and it is determined whether or not the actual engine speed Ne is greater than the lower limit target engine speed Ntmin in the ninth step S9, and if it is determined to be large, the actual engine speed Ne is determined in the tenth step S10. Is smaller than the upper limit target engine speed Ntmax. In step S11, one pulse is input to the stepping motor 20 in the closing direction of the throttle valve 13, and in the twelfth step S12, the pulse counter 29 counts the number of +1 pulses, and then the process returns to the fifth step S5. By repeating this, the throttle valve 13 is gradually closed, and the actual engine speed Ne decreases toward the upper limit target engine speed Ntmax.

  On the other hand, when it is determined in the ninth step S9 that the actual engine speed Ne is smaller than the lower limit target engine speed Ntmin, one pulse is input to the stepping motor 20 in the opening direction of the throttle valve 13 in the thirteenth step S13. In the fourteenth step S14, after the pulse counter 29 counts the number of one pulse, the process returns to the fifth step S5. By repeating this, the throttle valve 13 is gradually opened, and the actual engine speed Ne increases toward the lower limit target engine speed Ntmin.

  Finally, in the tenth step S10, it is determined that the actual engine speed Ne is smaller than the upper limit target engine speed Ntmax, and the actual engine speed Ne is within an allowable range of the target engine speed Nt. Automatically fits in. At this time, hunting of engine rotation is suppressed as much as possible by setting the lower limit target engine speed Ntmin and the upper limit target engine speed Ntmax. For example, approximately 20 rpm is appropriate for the allowable range (Ntmax−Ntmin) of the target engine speed Nt.

  As described above, in the control of the engine speed, the electronic control unit 21 treats the number of pulses input to the stepping motor 20 counted by the pulse counter 29 as the opening of the throttle valve 13 (in other words, engine load). Therefore, a throttle sensor for directly detecting the opening of the throttle valve 13 is not required, and the configuration of the engine electronic control device can be simplified.

  The electronic control unit 21 controls the fuel injection amount Q from the fuel injection valve 14 according to the flowchart of FIG.

That is, the actual engine speed Ne is read in the fifteenth step S15, the input pulse number to the stepping motor 20 counted by the pulse counter 29 is read in the sixteenth step S16, and the actual engine speed Ne and the Based on the number of input pulses, the basic fuel injection amount Q ₁ is read from the map 32 of FIG. 7, the output of the engine temperature sensor 24 is read in 18th step S18, and the engine temperature T is warmed up in 19th step S19. large whether determined from T _1, if you not greater discrimination proceeds to a twentieth step S20, after setting the engine temperature correction value beta, the said basic fuel injection quantity Q ₁ in the step S21 The injection amount Q is calculated by multiplying the engine temperature correction value β, and the fuel of the fuel injection amount Q is supplied to the fuel injection valve 1 in the 22nd step S22. The fuel injection amount Q is reset in the 23rd step S23, and the process returns to the 15th step S15. Accordingly, in the nineteenth step S19, when the engine E is an engine temperature is determined to not reached the warm-up completion temperature T ₁ of in warm-up operation, will be the fuel injection amount is increased, a good engine Warm-up operation can be ensured.

Also when the engine temperature T is determined to greater than the warm-up completion temperature T ₁ of at 19 the step S19 proceeds to the twenty-fourth step S24, reads the O ₂ concentration in the exhaust gas from the output of the O ₂ sensor 30. At this time, if the O ₂ concentration is greater than or equal to a predetermined value, the air-fuel ratio of the intake air mixture of the engine E is rich, and if it is less than the predetermined value, it is determined to be lean. Then, the process proceeds to the 25th step S25, where the O ₂ concentration correction value γ is set (this correction value γ is, for example, 0.9 for the rich and 1.1 for the lean), and the 26th step S26. The basic fuel injection amount Q ₁ is multiplied by the O ₂ concentration correction value γ to calculate the injection amount Q, and the process proceeds to the 22nd step S22. Therefore, when the air-fuel ratio of the air-fuel mixture becomes rich due to a decrease in atmospheric pressure during operation at a high altitude where the atmospheric pressure is low, the fuel injection amount Q is automatically reduced and automatically controlled to an appropriate air-fuel ratio. Therefore, it is possible to stabilize the operation of the engine E at a high altitude and contribute to low fuel consumption and exhaust purification.

  As described above, also in the control of the fuel injection amount Q, the electronic control unit 21 determines the number of input pulses to the stepping motor 20 counted by the pulse counter 29, the opening of the throttle valve 13 (in other words, engine load). Therefore, a throttle sensor that directly detects the opening of the throttle valve 13 is not required, and the configuration of the electronic control unit of the engine can be simplified.

  Further, the reduction ratio of the reduction gear device 26 that transmits the rotation of the stepping motor 20 to the throttle valve 13 is made variable as described above, and the throttle valve by one input pulse to the stepping motor 20 as shown in the map 31 of FIG. Since the amount of change in the opening 13 decreases as the throttle valve 13 moves toward the lower opening, the throttle valve opening in the low opening range of the throttle valve 13 (engine low load range) is reduced. As a result, the engine speed and the fuel injection amount can be precisely controlled in the low load range of the engine.

  The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention.

E ... Engine Ne ... Engine speed Q ... Fuel injection amount 13 ... Throttle valve 14 ... Fuel injection valve 20 ... Stepping motor 21 ... Electronic control unit 23 ... -Engine speed sensor 24 ... Engine temperature sensor 26 ... Reduction gear device 32 ... Map showing the relationship between the number of input pulses to the stepping motor, engine speed and fuel injection amount

Claims (4)

A stepping motor (20) for driving the throttle valve (13) of the fuel injection engine (E) to open / close, and increasing / decreasing the number of input pulses to the stepping motor (20) to control the opening / closing of the throttle valve (13). , An electronic control unit for an engine comprising an electronic control unit (21) for controlling the fuel injection amount (Q) according to the input pulse number and the engine speed (Ne),
The electronic control unit (21) holds a map (32) indicating the relationship among the number of input pulses to the stepping motor (20), the engine speed, and the fuel injection amount, and is supplied to the stepping motor (20). An electronic control unit for an engine, wherein a fuel injection amount (Q) is determined from the map (32) based on a pulse number and an engine speed. The engine electronic control unit according to claim 1,
The stepping motor (20) and the throttle valve (13) are connected via a reduction gear device (26) that reduces the rotation of the stepping motor (20) and transmits it to the throttle valve (13). An electronic control unit for an engine, characterized in that the reduction gear device (26) is configured such that the reduction ratio increases with a decrease in the opening of the throttle valve (13). The engine electronic control unit according to claim 1,
An engine temperature sensor (24) for detecting the temperature of the engine (E) is provided, and the electronic control unit (21) corrects the fuel injection amount (Q) according to the output of the engine temperature sensor (24). The electronic control unit for the engine. The engine electronic control unit according to claim 1,
An O ₂ sensor (30) for detecting the O ₂ concentration in the exhaust gas of the engine (E) is provided, and the electronic control unit (21) responds to the output of the O ₂ sensor (30) by the electronic control unit (21). An electronic control device for an engine characterized by correcting

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