JP4089942B2 - Engine speed control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine speed control device, and more particularly to an engine speed control device in consideration of a load.
[0002]
[Prior art]
Many engine generators used as AC power supply devices use an inverter device in order to stabilize the output frequency. In this type of engine generator, an engine coupled to the generator is driven to generate alternating current, which is once converted into direct current, and then converted into a commercial frequency by an inverter device to be output. In the generator using the inverter device, since the output frequency does not depend on the engine speed, output control according to the load can be performed by controlling the engine speed.
[0003]
For example, an inverter type engine generator described in Japanese Patent Laid-Open No. 5-18285 detects a load based on an output current of an inverter device, and performs engine throttle control based on the detection result. In this way, the output voltage can be maintained almost constant regardless of load fluctuations.
[0004]
In the throttle control, a control amount is calculated by inputting a difference signal of the current rotation speed (actual rotation speed) with respect to the target rotation speed and a change speed signal of the rotation speed to a central processing unit (CPU). Adjust the fuel supply amount by changing the throttle opening. The present applicant controls the throttle opening in a control device for an engine driving a generator so as to maintain a conduction angle of a semiconductor element constituting a converter for rectifying an output alternating current of the generator at a predetermined value. (Japanese Patent Laid-Open No. 11-308896).
[0005]
[Problems to be solved by the invention]
In a conventional engine control apparatus, when calculating a control amount by inputting a difference signal of an actual rotation speed with respect to a target rotation speed and a change speed signal of the rotation speed to the CPU, in order to increase the responsiveness at the time of sudden load change, the CPU Therefore, it is necessary to frequently open and close the throttle based on the calculation result.
[0006]
However, if the throttle is frequently controlled to open and close, not only when the load changes suddenly but also when the load is stable, the throttle is frequently opened and closed, so the engine speed cannot be stabilized. There is.
[0007]
Changes in driving sound due to unstable engine speed cause auditory discomfort. Therefore, in order to eliminate this unpleasant feeling, it tends to be a stable setting, that is, a setting that does not frequently open and close the throttle, but in that case, the response at the time of sudden load change must be sacrificed. There is a tendency to say.
[0008]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an engine speed control device capable of controlling the throttle opening to an appropriate throttle opening both when the load suddenly changes and when the load is stable. There is.
[0009]
[Means for Solving the Problems]
To achieve the above object, the present invention provides an engine speed control device having a fuel supply amount adjusting means for adjusting a fuel supply amount so as to eliminate a deviation of an actual engine speed from a target engine speed. And calculating means for periodically calculating the control value of the fuel supply amount for maintaining the engine speed at the target speed, and when the calculated control value is larger than the predetermined value, the calculation period Each time the fuel supply amount adjusting means is energized according to the control value, and the calculated control value is smaller than the predetermined value, the control value is increased according to the detected control value. The fuel supply amount adjusting means is energized according to the magnitude of the control value for each calculation cycle in which the thinning number is thinned for a small control value and thinned for a small control value according to a large number of thinning times. There is a first feature in that is configured to be.
[0010]
Further, the present invention includes counter means for counting the number of thinning out of the calculation cycle, the counter means being reset when the fuel supply amount adjusting means is energized, and the count value by the counter means is A second feature is that the fuel supply amount adjusting means is energized when the number of thinnings set according to the magnitude of the control value is reached.
[0011]
According to the above feature, since the control value is calculated according to the deviation of the actual rotation speed with respect to the target rotation speed, the deviation for each calculation cycle increases as the detected control value increases. That is, when the control value is large, it is determined that a load fluctuation that causes a large deviation has occurred. Accordingly, in response to this large load fluctuation, the fuel supply amount adjusting means is energized every control value calculation cycle. On the other hand, when the detected control value is small, it is determined that a small load fluctuation has occurred, so the fuel supply amount adjusting means is not energized for each calculation period, and the control value is determined according to the control value. The smaller the value is, the greater the number of thinning-out times that are set, the power is energized at every thinned-out calculation cycle.
[0012]
In particular, according to the second feature, the count value of the counter means for counting the number of times of thinning is identified, and the fuel supply amount is adjusted based on the count value and the number of times of thinning set according to the magnitude of the control value. It is determined whether it is time to activate the means.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 is a block diagram showing a configuration of an engine generator to which a control device according to an embodiment of the present invention is applied. An internal combustion engine (engine) 2 is connected to a magnet type multipolar generator (hereinafter simply referred to as “generator”) 1, and the generator 1 is driven by the engine 2 to be multiphase (typically three phases). Generate alternating current. The converter 3 has a rectifier circuit in which thyristors as semiconductor elements are assembled in a bridge, and the alternating current generated by the generator 1 is full-wave rectified by the converter 3 and converted into direct current. This direct current is input to the inverter 4. The inverter 4 converts the input direct current into a single-phase alternating current at a commercial frequency (for example, 50 Hz) and supplies it to the external load 5.
[0014]
A stepping motor 7 is coupled to the throttle valve 6 of the engine 2, and the opening degree of the throttle valve 6 is controlled according to the number of pulses supplied to the stepping motor 7. The engine speed is determined based on the fuel supply amount corresponding to the throttle opening.
[0015]
Voltage detector 8 detects the output voltage of converter 3. The thyristor driving circuit 9 compares a set voltage (for example, 170 V) as a target given in advance with the output voltage, and a known appropriate value is set so that the measured actual output voltage of the converter 3 becomes equal to the set voltage. By using this method, the conduction of the thyristor constituting the converter 3 is controlled. With such a configuration, the output voltage of the converter 3 is held at the set voltage in the output current range corresponding to the conduction angle control range of the thyristor.
[0016]
FIG. 1 is a block diagram showing the configuration of the fuel amount control unit 10. The conduction angle detector 101 detects the conduction angle of the thyristor based on the control signal output from the thyristor driving circuit 9 to the converter 3. The conduction angle is continuously detected at a predetermined cycle, and the average conduction angle is calculated. The average conduction angle is preferably calculated by moving average of continuous data for a predetermined number of times (for example, 10 times).
[0017]
The average conduction angle calculated by the thyristor conduction angle detection unit 101 is input to the deviation detection unit 102, and a deviation from the target conduction angle is detected. That is, it is determined based on the average conduction angle of the thyristor whether or not the generator 1 is being operated with a sufficient output. The target conduction angle is set to 80%, for example. The target conduction angle should have a certain hysteresis like a general control target. The target conduction angle may be variable according to the engine temperature. For example, the target conduction angle is reduced when the engine temperature is low. In this way, the engine speed is controlled to the target speed so that the deviation detected by the deviation detector 102 becomes “0”, and the generator 1 is maintained in a state where there is room.
[0018]
The target rotation speed update unit 103 outputs a rotation speed adjustment amount according to the deviation input from the deviation detection unit 102. The target rotational speed storage unit 104 adds the target rotational speed adjustment amount input from the target rotational speed update unit 103 to the already stored target rotational speed to obtain a new target rotational speed. The target rotational speed is updated within the range of the maximum rotational speed or the minimum rotational speed set in the maximum / minimum rotational speed setting unit 105. As a result of adding the target rotational speed adjustment amount, when the target rotational speed is out of the range, the target rotational speed is limited to the maximum rotational speed or the minimum rotational speed. The reason why the minimum rotational speed is defined is that the thyristor conduction angle does not deteriorate the stability at no load to light load by reacting to a slight rotational speed change.
[0019]
The rotation speed detection unit 106 detects the rotation speed of the generator 1. Based on the actual rotational speed input from the rotational speed detection unit 106 and the target rotational speed read from the target rotational speed storage unit 104, the control amount calculation unit 107 sets the deviation of the actual rotational speed from the target rotational speed to zero. The control amount is calculated by a known appropriate method (for example, proportionality, integration, and differentiation). The throttle control unit 108 outputs the number of pulses for driving the stepping motor 7 according to the calculation result in the control amount calculation unit.
[0020]
The control amount reflection determination unit 109 determines whether to immediately reflect the number of pulses output from the throttle control unit 108 on the movement of the stepping motor 7. The criteria for determination will be described later. When permission is given from the determination unit 109, the calculation result of the throttle control unit 108 is supplied to the stepping motor 7. The stepping motor 7 rotates in response to this and changes the throttle opening.
[0021]
The number of pulses output in this way is representative of load fluctuations for each calculation cycle. That is, when the number of pulses is large, the load varies greatly in each calculation cycle, in other words, when the load suddenly changes. On the other hand, the case where the number of pulses is small is the case where the load fluctuation is small, in other words, the case where the load is stable. When the load suddenly changes, the fuel supply amount must be increased rapidly so as to cope with the sudden change. When the load is stable, the fuel supply amount may be increased gradually.
[0022]
Therefore, in this embodiment, the calculation period of the number of pulses is fixed, and whether or not the number of pulses output from the throttle control unit 108 is reflected in the change in the throttle opening is controlled according to the magnitude of the number of pulses. The amount reflection determination unit 109 makes the determination.
[0023]
FIG. 3 is a diagram showing the correspondence between the number of pulses output from the throttle control unit 108 and the interval (reflection period) at which this number of pulses is reflected in the throttle opening. The calculation period of the number of pulses in the control amount calculation unit 107 is 10 ms, and the number of pulses is determined by an integrated value every 10 ms. The rotation angle of the throttle valve 6 is 70 °, and this rotation angle corresponds to 100 steps (number of pulses) of the stepping motor 7. That is, the resolution of the stepping motor is 0.7 °.
[0024]
In the example of FIG. 3, when the integrated value of the number of pulses is “7” or more, the reflection period is 10 ms, and the calculated number of pulses is immediately reflected in the change in the throttle opening. When the integrated value of the number of pulses is “3, 4, 5, 6”, the reflection period is 20 ms, and the calculated number of pulses is reflected in the change in the throttle opening every two calculation periods. . That is, the calculation result is thinned out once. Further, when the number of pulses is “0, 1, 2”, the reflection period is 30 ms, and the calculated number of pulses is reflected in the change in the throttle opening every three calculation periods. That is, the calculation result is thinned out twice. This reflection period is preferably common to both the opening and closing directions of the throttle valve 6.
[0025]
FIG. 4 shows a reflection example of the pulse number to the stepping motor 7 based on the correspondence relationship between the pulse number and the reflection period. In FIG. 4, the pulse number “1” is calculated in the first time (cycle 1). Since the reflection cycle of the pulse number “1” is 30 ms, the calculation result of this pulse number is based on the movement of the stepping motor 7. Not reflected. In the second calculation (cycle 2), since the number of pulses is “0”, the calculation result is not reflected in the stepping motor 7. In the third calculation (cycle 3), the number of pulses is “1”, and the calculation result is not reflected twice immediately before, so the calculation result is reflected in the stepping motor 7. In the fourth calculation (cycle 4), the number of pulses “2” is calculated, but since the previous calculation result has just been reflected, this calculation result is ignored.
[0026]
The reflection period of the pulse number “4” obtained in the subsequent fifth calculation (cycle 5) is 20 ms. Since the calculation result was thinned out immediately before, the calculation result “4” is the stepping motor 7. It is reflected in the movement. Since the number of pulses obtained by the sixth calculation (cycle 6) is “7”, and there is a large load fluctuation, the calculation result is immediately reflected in the movement of the stepping motor 7.
[0027]
FIG. 5 is a flowchart illustrating an example of processing of the control amount reflection determination unit that determines whether or not the calculation result of the control amount calculation unit 107 is reflected in the movement of the stepping motor 7. In step S <b> 1, it is determined whether a control amount, that is, the number of pulses is output from the control amount calculation unit 107. If it is determined that the number of pulses has been output, the process proceeds to step S2 to determine whether or not the number of output pulses is “7” or more. If the number of output pulses is equal to or greater than “7”, it is determined that a sudden change in the load has occurred, and thus the process proceeds to step S3 to generate a pulse number output permission to the throttle control unit 108. In step S4, the counter value C representing the number of times (number of cycles) in which the calculation result in the control amount calculation unit 107 is not reflected in the opening / closing operation of the throttle valve 6 is cleared.
[0028]
If the number of output pulses is not "7" or more, the process proceeds to step S5, and it is determined whether or not the number of output pulses is "6-3". If the number of output pulses is “6-3”, it is determined that a moderate load change has occurred, and the process proceeds to step S6, where the counter value C is incremented (+1). In step S7, it is determined whether or not the counter value C is “2” or more. If the counter value C is equal to or greater than “2”, it is determined that it is the second cycle since the previous pulse number was output, and thus the process proceeds to step S3 to allow the throttle control unit 108 to output the pulse number. If the counter value C is less than “2”, the number of pulses calculated in the current calculation cycle is not reflected in the throttle control.
[0029]
If the number of pulses output from the control amount calculation unit 107 is neither “7” nor “6-3”, the result in Step S5 is negative and the process proceeds to Step S8 to determine whether the number of pulses is “2” or less. . If the number of output pulses is equal to or less than “2”, it is determined that the degree of load change is small, and the process proceeds to step S9 to increment the counter value C. In step S10, it is determined whether or not the counter value C is “3” or more. If the counter value C is equal to or greater than “3”, it is determined that it is the third cycle since the previous pulse number was output, and thus the process proceeds to step S3 to allow the throttle control unit 108 to output the pulse number. If the counter value C is less than “3”, the number of pulses calculated in the current calculation cycle is not reflected in the throttle control. If it is determined in step S8 that the number of pulses is not “2” or less, an error is determined, and the process returns to step S1.
[0030]
As described above, in the present embodiment, when a sudden load change occurs, the control amount is reflected at every control amount calculation cycle, and the throttle valve 6 is rotated. On the other hand, for moderate load fluctuations and small load fluctuations, the control amount is not immediately reflected in the movement of the throttle valve 6, but is reflected in the next or the next calculation cycle.
[0031]
In the present embodiment, a carburetor type engine is assumed, but the present invention can also be applied to a fuel injection type engine. In that case, the control amount of the fuel supply amount corresponds to the duty supplied to the fuel injection valve.
[0032]
【The invention's effect】
As is apparent from the above description, according to the first and second aspects of the invention, when the deviation of the actual rotational speed from the target rotational speed of the engine is large, the control value of the fuel supply amount adjusting means becomes large. The fuel supply amount is adjusted every calculation cycle. Therefore, it is possible to adjust the fuel supply amount by following well even when the load changes suddenly. On the other hand, when the change in the load is small, the fuel supply amount adjusting means is not energized every calculation cycle, so that a stable operation state can be maintained.
[0033]
According to the second aspect of the present invention, the fuel supply amount can be appropriately adjusted according to the load state by simple control for discriminating between the set thinning number for each control value and the value of the counter means for the thinning number. Can do.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a fuel amount control unit according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of an engine generator to which a control device according to an embodiment of the present invention is applied.
FIG. 3 is a diagram illustrating a correspondence between a control amount (number of pulses) and a reflection period of the number of pulses.
FIG. 4 is a diagram showing an example of reflection of the number of pulses to the stepping motor based on the correspondence between the number of pulses and the reflection period.
FIG. 5 is a flowchart illustrating an example of processing of a control amount reflection determination unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Generator, 2 ... Engine, 3 ... Converter (DC power supply circuit), 4 ... Inverter (switching device), 6 ... Throttle valve, 7 ... Stepping motor, 8 ... Voltage detection part, 9 ... Thyristor drive circuit, 10 ... Fuel amount control unit, 107 ... Control amount calculation unit, 108 ... Throttle control unit, 109 ... Control amount reflection determination unit

Claims (2)

In an engine speed control device having a fuel supply amount adjusting means for adjusting a fuel supply amount so as to eliminate a deviation of an actual speed with respect to a target engine speed,
Computation means for periodically computing a control value of the fuel supply amount for maintaining the engine speed at the target speed based on the deviation,
When the calculated control value is larger than the scheduled value, the fuel supply amount adjusting means is energized according to the control value for each calculation cycle,
When the calculated control value is smaller than the predetermined value, according to the size of the detected control value, the large control value is according to a small number of thinning times, and the small control value is according to a large number of thinning times. An engine speed control device characterized in that the fuel supply amount adjusting means is energized in accordance with the magnitude of the control value at each calculation cycle to be thinned out. Counter means for counting the number of thinning out of the calculation cycle, the counter means being reset when the fuel supply amount adjusting means is energized,
2. The engine according to claim 1, wherein the fuel supply amount adjusting means is energized when the count value by the counter means reaches the number of thinnings set in accordance with the magnitude of the control value. Rotational speed control device.

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