JP5281668B2 - General-purpose engine electronic governor device and hunting control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic governor device capable of preventing rotating speed hunting of a general purpose engine and keeping a rotating speed thereof constant. <P>SOLUTION: The electronic governor device includes: a rotation speed sensor 35 that detects a rotating speed of the general purpose engine; a hunting determination means 55 that calculates a rotating speed deviation between the detected rotating speed and the number of a target rotating speed with prescribed control cycles, employs a sum of a plurality of control cycles of the calculated result as a hunting indicator, and determines that hunting occurs if the hunting indicator is successively equal to or more than a threshold value; and a throttle valve opening calculation means 43 that lowers a control gain of a control opening of a throttle valve 9 if the hunting determination means 55 determines that the hunting occurs. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to an electronic governor device for a general-purpose engine, and relates to an electronic governor device for a general-purpose engine that controls the rotation speed to be constant with respect to a load fluctuation of the general-purpose engine by controlling opening and closing of a throttle valve.

In general, mechanical governors consisting of weights and springs have been the mainstream in general-purpose engines, but in work machines that do not like rotational fluctuations such as generators, the throttle valve of the carburetor is operated by an actuator such as a stepping motor. Some electronic governor devices are used.
In general-purpose engines, a structure in which an air-fuel mixture obtained by mixing air and gasoline fuel using a carburetor is ignited by a spark plug in a combustion chamber is employed.

The relationship between the amount of air flowing through the carburetor with respect to the throttle opening, that is, the relationship between the engine output and the throttle opening, is that the pressure difference between the upstream side and the downstream side of the throttle valve decreases as the throttle opening increases. In general, as shown in FIG. 6, the smaller the throttle opening, the larger the change in the intake air amount with respect to the change in the throttle opening, and the larger the throttle opening, the more the intake air amount with respect to the change in the throttle opening. It is known that the change becomes small, and the adjustment amount of the throttle opening varies depending on the load region.
For this reason, when the followability of the throttle opening with respect to the load fluctuation is poor, a so-called hunting phenomenon in which the engine speed fluctuates may occur.
On the other hand, a general-purpose engine is often used at a constant rotational speed, and a general-purpose engine for a generator needs to perform a stable constant-rotation operation in order to generate power at a constant frequency. Therefore, stable operation with good responsiveness to load fluctuations (power generation load fluctuations) is desired.

For example, Japanese Patent No. 4294012 (Patent Document 1) is disclosed as a prior art document that suppresses hunting by controlling the throttle opening in accordance with load fluctuations of a general-purpose engine.
Patent Document 1 discloses control hunting by a throttle control means for an abnormality in which a sensor output signal fluctuates repeatedly when a sensor abnormality occurs due to poor contact of a throttle opening sensor with respect to an output value of an accelerator opening sensor. There is disclosed a technique for determining and lowering a predetermined control gain value to prevent an inadvertent increase in engine speed and engine stall.
Japanese Patent No. 3766765 (patent document 2) describes hunting of the governor by comparing the change over time of the position of the fuel rack driven by the governor of the diesel engine with the change over time during normal operation. It can be reliably and automatically determined, and contributes to labor saving and efficiency improvement of engine operation.

Japanese Patent No. 4294012 Japanese Patent No. 3766765

However, in the case of a general-purpose engine, a constant rotational speed is always required for load fluctuations on the general-purpose engine. However, Patent Document 1 is mounted on a vehicle, and the value of an accelerator opening sensor and the throttle opening This is a comparison with the sensor output, and does not keep the rotational speed constant even if a load fluctuation occurs.
Patent Document 2 detects the hunting of the governor by comparing the change over time in the fuel rack position of the diesel engine with the change over time during normal operation, and does not control the throttle opening.
Therefore, when the rotational speed of the general-purpose engine is detected and the detected rotational speed has an absolute difference equal to or larger than the threshold with respect to the target rotational speed, it is determined as hunting and the control gain of the throttle valve is reduced ( The purpose is to improve the performance of general-purpose engines by preventing hunting), keeping the general-purpose engine speed constant.

In order to solve such a problem, the present invention provides a general-purpose engine electronic governor device, and a rotation speed sensor for detecting the rotation speed of the general-purpose engine;
In a predetermined control cycle, the rotational speed deviation between the rotational speed detected by the rotational speed sensor and the target rotational speed is calculated, and the sum of a plurality of control periods of the calculation results is used as a hunting index. Hunting determination means for determining that hunting has occurred when the threshold value is exceeded,
Throttle valve control means is provided for reducing the control gain of the throttle valve control opening when it is determined by the hunting determination means that hunting has occurred.

  With such a configuration, the control gain of the throttle valve can be made slow, and hunting caused by engine load fluctuation can be quickly corrected to ensure a stable engine output.

In the present invention, preferably, the hunting index of the hunting determination means is
Σerpm = | erpm (n-4) | + | erpm (n-3) | + | erpm (n− 2 ) | + | erpm (n− 1 ) | + | erpm (n) | ≧ 200 rpm
However, it is preferable that | erpm | = the absolute difference between the target rotational speed and the engine rotational speed.

  With such a configuration, equipment that is generally used with a general-purpose engine as a power source is subject to severe load fluctuations, so that stable output can be secured by detecting and responding to early (small) rotation fluctuations. Thus, the effect of ensuring that the performance on the device side can be exhibited reliably is obtained.

  Preferably, in the present invention, when the Σerpm ≧ 200 rpm is detected a plurality of times, the hunting determination means determines that hunting has occurred, and based on the determination, the throttle valve control means determines the control gain of the throttle valve. It is good to lower.

  With such a configuration, the hunting index Σerpm ≧ 200 rpm is reduced, and the control gain is lowered when the number of detection times of Σerpm ≧ 200 rpm is continued a plurality of times, so that the change due to the occurrence of hunting and the influence of external changes is ensured. As a result, the engine can be prevented from becoming an unstable factor in general-purpose engine operation, and stable engine operation can be ensured.

  In the present invention, it is preferable that the number of times of control of the throttle valve control means is set to once between engine start and stop.

  With such a configuration, hunting is not a control problem, but may be a malfunction based on mechanical or fuel on the engine side. If gain control is repeated, gain may become too small and control may become impossible. Is prevented from occurring.

  In the present invention, preferably, in the electronic governor device for a general-purpose engine, the rotation speed of the general-purpose engine detected by the rotation speed sensor is equal to the rotation speed detected by the rotation speed sensor and the target rotation in a predetermined control cycle. A step of calculating a rotational speed deviation with respect to the number and determining a sum of a plurality of control cycles of the calculation result, and counting whether the threshold value or more has occurred a prescribed number of times, and when hunting occurs when the prescribed value is reached A step of determining, and a step of lowering a throttle valve control gain when the threshold value or more occurs a predetermined number of times.

  With such a configuration, the detected rotational speed of the general-purpose engine calculates a rotational speed deviation between the rotational speed detected by the rotational speed sensor and the target rotational speed in a predetermined control cycle, and a plurality of the calculated results It is determined whether the sum of the control cycles is equal to or greater than a threshold value, and it is counted whether the threshold value or more has occurred a prescribed number of times. Hunting can be corrected quickly to ensure stable engine output.

  When the rotational speed detected by the rotational speed sensor of the general-purpose engine has an absolute difference greater than or equal to the threshold value with respect to the target rotational speed, it is determined that hunting has occurred when the rotational speed fluctuates. By reducing the control gain of the control opening, the control fluctuation of the throttle valve can be slowed, and the hunting caused by the engine load fluctuation can be corrected quickly to ensure a stable engine output.

The external appearance side view of the general purpose engine which concerns on embodiment of this invention is shown. The external appearance top view of the general purpose engine which concerns on embodiment of this invention is shown. 1 is an overall configuration block diagram including an electronic governor device according to an embodiment of the present invention. The explanatory view showing the hunting index generating situation concerning the embodiment of the present invention along the control cycle is shown. The hunting detection control flowchart which concerns on embodiment of this invention is shown. It is explanatory drawing which shows the relationship between a throttle opening and air quantity (engine output).

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to specific examples unless otherwise specifically described. Only.

  As shown in FIGS. 1 and 2, the general-purpose engine 1 is composed of a single-cylinder four-cycle engine, and the engine body 3 is disposed at an inclination. An intake passage 5 is connected to a side portion of the engine body 3, and a carburetor 7 is attached to the upstream side of the intake passage 5. A throttle valve 9 (see FIG. 3) is disposed inside the carburetor 7, and the throttle valve 9 is driven to open and close by a stepping motor (actuator) 11 for driving the throttle valve 9 disposed at the end of the carburetor 7. The

A stepping motor 11 that opens and closes the throttle valve 9 is operated by a command from the motor driver unit 13 of the electronic governor device 2 (see FIG. 3).
A mixture of air and fuel (gasoline) adjusted by the throttle valve 9 is supplied to the engine combustion chamber and combusted, and then discharged from the exhaust muffler 15 through the exhaust passage.

As shown in FIG. 2, various engine loads are attached to the output shaft 17 of the engine body 3. In this embodiment, an example in which the generator 19 is attached is shown. A flywheel 21 connected to a crankshaft (not shown) is attached to the opposite side of the output shaft 17, and the alternating current generated by the flywheel magnet 23 and the power generation coil 25 is passed through a rectifier circuit (not shown). After being rectified to a direct current, it is supplied to a spark plug (not shown) through the ignition coil 29 of the ignition device 27.
The ignition device 27 is started to operate by turning on the main switch 33 (see FIG. 3).

Further, a crank angle sensor (rotation angle sensor) 35 including a pickup (not shown) is provided in the vicinity of the flywheel 21, and a pulse is output at every predetermined crank angle and input to the rotation speed detection unit 37 of the electronic governor device 2. Is done.
An ignition signal from the ignition coil 29 is also input to the rotation speed detection unit 37 as an ignition pulse.

The electronic governor device 2 of the general-purpose engine 1 configured as described above will be described.
As shown in FIG. 3, the electronic governor device 2 includes a target rotational speed input unit 41, a rotational speed detection unit 37, a throttle opening calculation unit 43, and a motor drive unit 13.

The target engine speed input unit 41 sets a target engine speed according to the application of the engine load attached to the output shaft 17.
In the case of the generator 19, the target rotational speed is set to the rotational speed corresponding to the power generation frequency.
The rotation speed detector 37 detects the rotation pulse signal from the crank angle sensor (rotation angle sensor) 35 and the ignition pulse signal from the ignition coil 29 and outputs the engine rotation speed signal to the throttle opening calculation means 43. To do.
The motor driver unit 13 receives a throttle operation command signal from the throttle opening calculation means 43 and outputs an operation control signal to the throttle valve 9 to the stepping motor 11.

  The throttle opening calculation means 43 includes a stable operation determination means 45 for determining whether the engine is operating at a stable rotation speed with respect to the target rotation speed set by the target rotation speed input unit 41, and the stable operation determination means. 45, when the throttle opening degree when determined to be stable is about 60% or more of the throttle fully open, the operation region determination means 47 for determining whether or not the throttle opening is about 60% or more. When the determination is made, the throttle valve 9 is rotated by the throttle valve 9 in the closing direction at a certain opening degree, and the throttle valve control means for controlling the rotation of the throttle valve 9 until immediately before the stable operation determination means 45 determines that it is unstable. A certain throttle control means 49 and when the engine load increases, the throttle valve 9 is fully opened and then the throttle valve 9 is closed to the target rotational speed. Whether or not the engine is hunting when the rotation pulse input to the rotational speed detection unit 37 fluctuates up and down with respect to the target rotational speed, and the load increasing throttle control means 51 that rotates to control the target rotational speed to balance with the target rotational speed Hunting determination means 55 for determining whether or not.

As described above, the hunting determination unit 55 calculates the throttle opening when it is determined that hunting has occurred because the rotation pulse input to the rotation speed detection unit 37 fluctuates up and down with respect to the target rotation speed. The means 43 transmits an operation command for reducing the control gain.
The hunting index of the hunting determination means 55 that determines that hunting has occurred is determined by the following formula. (Control cycle)
Σerpm = | erpm (n-4) | + | erpm (n-3) | + | erpm (n− 2 ) | + | erpm (n− 1 ) | + | erpm (n) | ≧ 200 rpm
However, | erpm | = target rotational speed−engine rotational speed And, in FIG. 4, the horizontal axis represents the engine rotational control cycle, and the vertical axis represents the absolute value of the difference between the target rotational speed and the actual rotational speed (rotational speed deviation) ≧ 200 rpm. Then, when it occurs 10 times, the hunting determination means 55 determines that hunting has occurred.
In addition, the reason why the value of the hunting index is determined to be absolute value ≧ 200 rpm is based on the results of experiments in our company, in the generator most used as the load side of this general-purpose engine, the occurrence of load fluctuation of the generator is detected promptly Therefore, stable operation and maintenance control can be performed by quick response, and the function of the generator can be fully exhibited.

A hunting detection method will be described with reference to the flowchart of FIG.
Starting from step S1, in step S2, it is confirmed whether hunting control has been performed from the start of the engine to the present time. If it has been performed, YES is selected and the process returns to step S14, where hunting control is performed. Not.
If hunting control is not performed, NO is selected and the process proceeds to step S3.
In step S3, it is determined whether or not the engine rotational fluctuation satisfies the target rotational speed−engine rotational speed = absolute difference Σerpm ≧ 200 rpm (hunting index).
If the absolute difference Σerpm ≦ 200 rpm, the process proceeds to step S11 with NO. In step S11, the hunting flag is not set and the process proceeds to step S12. In step S12, it is determined whether target rotational speed−engine rotational speed = absolute difference Σerpm ≧ 15 rpm. This determines whether or not the engine rotation is stable. If the absolute engine speed difference is greater than or equal to 15 rpm, it is determined that there is a fluctuation in the speed but it is not hunting, NO is selected, and the process proceeds to step S14 and returns.
In step S12, when the engine speed is an absolute difference Σerpm ≦ 15 rpm, it is determined that the engine is operating stably with respect to the target speed, and YES is selected, and the process proceeds to step S13. In step S13, the hunting count is reset to 0 (zero), and the process proceeds to step S14 and returns.

On the other hand, in step S3, it is determined whether or not the engine rotational fluctuation satisfies target rotational speed−engine rotational speed = absolute difference Σerpm ≧ 200 rpm. If the absolute difference Σerpm ≧ 200 rpm, the process proceeds to step S4 with YES, and hunting flag = 1 is set in step S4. In step S5, it is determined whether or not the previous (control cycle) hunting index has exceeded 200 rpm. If it has not exceeded 200 rpm, YES is selected, and the process proceeds to step S6. In step S6, hunting count + 1 is added.
In step S7, it is determined whether hunting count = 10. If YES, the process proceeds to step S8. In step S8, it is detected that hunting has occurred, and a command is issued to the motor driver unit 13 to perform an operation of decreasing the opening degree control gain of the throttle valve 9 (decreasing the sensitivity).
In step S9, a hunting control execution flag = 1 is set.
Furthermore, it progresses to step S10, a hunting count is reset to 0 (zero), and it progresses to step S14 and returns.

On the other hand, if the previous (control cycle) hunting index exceeds 200 rpm in step S5, NO is selected and the process proceeds to step S14.
In step S7, if hunting count = 10 has not been reached, NO is selected and the process proceeds to step S14.
That is, when the engine rotation is not stabilized and is not counted ten times continuously, it is determined that the hunting control execution standard has not been reached, and the operation of lowering the opening control gain (thinning the sensitivity) of the throttle valve 9 is not performed. .

In the present embodiment, as described above, the control for lowering the opening control gain of the throttle valve 9 in this control flow is limited to one time from the engine start to the stop.
The reason is that the hunting that occurs is not a problem in control, but may be a malfunction based on mechanical or fuel on the engine side. If gain control is repeated, the gain becomes too small and control becomes impossible. This is to prevent sex.

When the detected absolute speed of the general-purpose engine exceeds a threshold value with respect to the target speed reaches the specified number of times, the control fluctuation of the throttle valve is slowed down to quickly correct the hunting caused by the engine load fluctuation. Thus, stable engine output can be secured.

  It may be used for an electronic governor device of a general-purpose engine that controls opening / closing of a throttle valve of a general-purpose engine using the electronic governor device so that the rotation speed is controlled to be constant with respect to a load change.

1 General-purpose engine
2 Electronic governor device 3 Engine body 5 Fuel gas supply control device 7 Vaporizer 9 Throttle valve 11 Stepping motor 13 Motor driver unit 27 Ignition device 29 Ignition coil 35 Rotation pulse 37 Rotation number detection unit 41 Target rotation number input unit 43 Throttle opening Calculation means 45 Stable operation determination means 47 Operation region determination means 49 Stable throttle control means 55 Hunting determination means

Claims (5)

In an electronic governor device of a general-purpose engine, a rotational speed sensor that detects the rotational speed of the general-purpose engine;
In a predetermined control cycle, the rotational speed deviation between the rotational speed detected by the rotational speed sensor and the target rotational speed is calculated, and the sum of a plurality of control periods of the calculation results is used as a hunting index. Hunting determination means for determining that hunting has occurred when the threshold value is exceeded,
An electronic governor device for a general-purpose engine, comprising throttle valve control means for reducing a control gain of a throttle valve control opening when it is determined by the hunting determination means that hunting has occurred. The hunting index of the hunting determination means is
Σerpm = | erpm (n-4) | + | erpm (n-3) | + | erpm (n− 2 ) | + | erpm (n− 1 ) | + | erpm (n) | ≧ 200 rpm
The electronic governor device for a general-purpose engine according to claim 1, wherein | erpm | = target rotational speed-absolute difference between engine rotational speeds.   When the Σerpm ≧ 200 rpm is detected a plurality of times, the hunting determination means determines that hunting has occurred, and the throttle valve control means decreases the control gain of the throttle valve based on the determination. An electronic governor device for a general-purpose engine according to claim 2.   2. The electronic governor device for a general-purpose engine according to claim 1, wherein the number of times of control of the throttle valve control means is set to once between engine start and stop.   In the electronic governor device of a general-purpose engine, the rotational speed of the general-purpose engine detected by the rotational speed sensor calculates the rotational speed deviation between the rotational speed detected by the rotational speed sensor and the target rotational speed in a predetermined control cycle. Determining a sum of a plurality of control cycles of the calculation result, counting whether the threshold value or more has occurred a predetermined number of times, and determining that hunting has occurred when the threshold value is reached, and exceeding the threshold value or more And a step of lowering the throttle valve control gain when a predetermined number of times occurs, a hunting control method for an electronic governor device of a general-purpose engine.

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