JP2008019810A - Electronic governor for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure the freedom of measuring timing of a solenoid driving current and improve measurement accuracy by reflecting correlation of a detected current value and change in a solenoid driving current value and a power source voltage, in an electronic governor for an engine. <P>SOLUTION: In the electronic governor 9 for the engine, a solenoid driving circuit 10 for dosing a fuel by adapting a control signal to a switching element 2 and actuating a solenoid 3, a side of the switching element 2 is connected to ground and a shunt resistance 8 is provided in a ground passage. The electronic governor 9 for the engine is provided with an LPF (Low Pass Filter) 30 between the shunt resistance 8 and a potential difference measurement part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technology for a control circuit configuration of an electronic governor for an engine.

  Conventionally, an electronic governor is known as a device for optimally controlling the fuel injection amount of an engine. The electronic governor performs current control when electromagnetically driving the rack position with a solenoid for adjusting the fuel injection amount. That is, the set rotational speed is detected by the accelerator sensor, the actual rotational speed is detected by the rotational speed sensor, and the rack position is set so that the rotational deviation becomes small. Further, the actual rack position is detected by the rack position sensor, and the solenoid drive current is calculated so that the positional deviation from the set position becomes small. Then, the switching element is opened / closed by calculating the duty ratio of the switching element (switching time ratio of the switching element) so that the solenoid driving current is generated.

First, a conventional solenoid drive circuit configuration of a general electronic governor will be briefly described.
As shown in FIG. 14, the solenoid drive circuit 400 includes a power supply 401 and a switching element 402. A DC power source such as a battery is used as the power source 401, and the switching element 402 is opened and closed to energize the solenoid 403 from the power source 401. A transistor or the like is used as the switching element 402, and the amount of current supplied to the solenoid 403 is determined by the switching ratio of the switching element 402 and the voltage of the power source 401.
The switching element 402 is opened and closed by a Pulse Width Modulation signal (hereinafter referred to as a PWM signal Pw). Here, the switching element 402 is closed when the PWM signal Pw is ON, and the switching element 402 is opened when the PWM signal Pw is OFF.
Further, in order to protect the switching element 402 from the induced voltage of the solenoid 403 generated by opening the switching element 402, a flywheel diode 406 is connected to the solenoid drive circuit 400 in parallel with the solenoid 403. The flywheel diode 406 allows current to pass only from the switching element 402 side to the power source 401 side. Even if the switching element 402 is opened and an induced voltage is generated in the solenoid 403, a reflux circuit 405 is formed in which a closed loop is formed between the solenoid 403 and the fly-hole diode 406, and a current caused by the induced voltage is circulated. Therefore, it is possible to prevent an induced voltage from being applied to the switching element 402 in the open state.
In the following, a known solenoid drive circuit configuration in which a shunt resistor for measuring an actual solenoid drive current is provided for the basic solenoid drive circuit 400 will be introduced.

As shown in FIG. 15, there has conventionally been a configuration in which a shunt resistor 108 is provided between a solenoid 103 and a flywheel diode 106.
However, in the conventional circuit configuration, when the switching element 102 is opened, the reflux circuit 105 is not grounded (floating from GND), so that an insulation amplifier is required for potential difference measurement (actual solenoid drive current measurement) at the shunt resistor 106. The cost increases accordingly. Furthermore, since the shunt resistor is provided in the reflux circuit 105, the circuit design freedom is limited.

As shown in FIG. 16, Patent Document 1 discloses a solenoid drive circuit 200 in which a switching element 202 is provided on the primary side of the power supply 201 and a return circuit 205 is provided on the secondary side of the GND 207, and a shunt resistor 208 is provided in the return circuit 205. The configuration is disclosed (203a in FIG. 3 of Patent Document 1).
However, the circuit configuration of Patent Document 1 requires a circuit for overcurrent protection because the switching element 202 is damaged when the switching element 202 is closed when a ground fault occurs in the return circuit 205. It tends to be expensive.

As shown in FIG. 17, Patent Document 2 discloses a configuration of a solenoid driving circuit 300 in which a shunt resistor 308 is provided between a switching element 302 and a GND 307.
However, in the circuit configuration of Patent Document 2, since the shunt resistor 308 is insulated from the power source 301 when the switching element 302 is opened, the current waveform becomes intermittent. Therefore, in the circuit configuration of Patent Document 2, current can be measured only at the timing when the switching element 302 is closed.
Japanese Patent No. 3563407 JP 2004-3000987 A

  Therefore, the problem to be solved is to secure the degree of freedom of the measurement timing of the solenoid drive current in light of the above-mentioned problems of the prior art. In addition, the measurement accuracy is improved by reflecting the correlation between the detected current value and the solenoid drive current value or the change in the power supply voltage.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, according to the first aspect of the present invention, one side of the switching element is grounded by a solenoid driving circuit that applies a control signal to the switching element to operate a solenoid to perform fuel metering, and a shunt resistor is provided in the grounding path. In the engine electronic governor, an LPF is provided between the shunt resistor and the potential difference measuring unit.

  According to a second aspect of the present invention, in the engine electronic governor according to the first aspect, the solenoid drive current is calculated from the detected current based on the correlation between the detected current at the shunt resistance stored in advance and the solenoid drive current, and the switching element is operated. This is fed back to the signal calculation means.

  According to a third aspect of the present invention, in the engine electronic governor according to the second aspect, the calculated solenoid driving current is corrected based on a correlation with a change in power supply voltage of the solenoid driving current stored in advance.

  According to a fourth aspect of the present invention, in the engine electronic governor according to the first aspect, an assumed detection current is calculated from the target current based on a correlation between the target current stored in advance and the detection current at the shunt resistor, and a switching element operation signal calculation The signal is input to the means as a target signal.

  According to a fifth aspect of the present invention, in the electronic governor engine for an engine according to the fourth aspect, the assumed detection current is corrected based on a correlation between a detection current stored in advance and a change in power supply voltage.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect of the present invention, it is possible to prevent the terminal voltage of the shunt resistor from becoming intermittent by the LPF filtering. That is, the measurement timing of the solenoid drive current can be set freely.

  According to the second aspect, in addition to the effect of the first aspect, even when the detected current by the filtering of the LPF does not coincide with the solenoid driving current, it is possible to replace the detected current with the solenoid driving current.

  In the third aspect, in addition to the effect of the second aspect, it is possible to follow a change in the solenoid drive current due to a change in the power supply voltage.

  According to the fourth aspect of the present invention, in addition to the effect of the first aspect, the correction based on the correlation is performed outside the feedback process of the detection current at the shunt resistor. Although the correction calculation in the feedback process may adversely affect the control characteristics depending on the configuration, the configuration of the fourth aspect can eliminate the influence of the correction calculation. That is, the stability of the control calculation can be improved.

  According to the fifth aspect, in addition to the effect of the fourth aspect, it is possible to follow the change in the solenoid drive current due to the change in the power supply voltage.

Next, embodiments of the invention will be described.
1 is a block diagram showing the overall configuration of an electronic governor of a diesel engine according to the present invention, FIG. 2 is a solenoid drive circuit diagram of the electronic governor, and FIG. 3 is a current waveform diagram showing a waveform of a detected current filtered by an LPF. It is.
4 is a graph showing the correlation between the detected current filtered by the LPF and the solenoid drive current, FIG. 5 is a graph showing the detected current correction map, and FIG. 6 is a block diagram showing another control system for the solenoid drive current. is there.
FIG. 7 is a graph showing the correlation between the detected current filtered by the LPF and the solenoid drive current when the power supply voltages are different, FIG. 8 is a graph showing the first power supply voltage correction map, and FIG. 9 is a graph showing changes in the power supply voltage. It is a block diagram which shows the control system of the added solenoid drive current.
FIG. 10 is a block diagram showing another control system for solenoid drive current, FIG. 11 is a target current correction map, and FIG. 12 is a block diagram showing another control system for solenoid drive current.
13 is a graph showing a second power supply voltage correction map, FIG. 14 is a basic solenoid drive circuit diagram, and FIG. 15 is a conventional solenoid drive circuit diagram.
16 is a solenoid drive circuit diagram of Patent Document 1, and FIG. 17 is a solenoid drive circuit diagram of Patent Document 2.

Here, the embodiment of the present invention will be described in detail with reference to FIGS.
First, the electronic governor 9 according to the embodiment of the present invention will be briefly described with reference to FIG.
As shown in FIG. 1, the electronic governor 9 is a governor device that includes an electronic control unit (hereinafter referred to as ECU 4) and a solenoid 3. The electronic governor 9 is provided in a fuel injection pump (not shown) of a diesel engine (not shown). The electronic governor 9 drives the fuel rack 11 for adjusting the fuel supply amount by the solenoid 3 so that the engine speed N matches the target speed Nm.
The fuel rack 11 is biased to the outside of the solenoid 3 by a spring 12. On the other hand, the fuel rack 11 is drawn into the solenoid 3 by energizing the solenoid 3. With such a configuration, the fuel rack position R can be adjusted based on the balance between the pull-in force corresponding to the energization amount of the solenoid 3 and the urging force of the spring 12.

Similarly, as shown in FIG. 1, for the electronic governor 9, the ECU 4 includes a PWM output calculation unit 21, a target current calculation unit 22, a target rack position calculation unit 23, and a solenoid drive circuit 10. The actual engine speed N is detected by a rotation speed sensor (not shown). The target rack position calculation unit 23 calculates the target rack position 33 so that the rotational deviation between the target engine speed Nm and the actual engine speed N is small. The actual rack position R is detected by a rack position sensor (not shown). The target current calculation unit 22 calculates the target drive current Pm so that the positional deviation between the target rack position Rm and the actual rack position R is small.
The PWM output calculation unit 21 calculates the PWM signal Pw so that the current deviation between the target drive current Pm detected by the solenoid drive circuit 10 and the detected current Pb (details will be described later) becomes small. The amount of current from the power source 1 to the solenoid 3 is controlled by controlling the duty ratio of the switching element 2 by the PWM signal Pw.
With such a configuration, the engine speed N is controlled to the target engine speed Nm while feedback control is performed in each of the arithmetic units 21, 22, and 23 with the actual value directed to the target value.

Next, the solenoid drive circuit 10 according to the present invention will be described in detail with reference to FIG.
FIG. 2 is a diagram showing the solenoid drive circuit 10 of FIG. As shown in FIG. 2, the solenoid drive circuit 10 is configured such that the solenoid 3, the switching element 2, and the shunt resistor 8 are connected in series from the power supply 1 to the GND 7. As the power source 1, a DC power source such as a battery is used. The switching element 2 is a transistor or the like. With such a configuration, the solenoid 1 is energized from the power source 1 according to the switching ratio of the switching element 2. The GND 7 is so-called grounding.

The solenoid drive circuit 10 connects the flywheel diode 6 to the solenoid 3 in parallel. The flywheel diode 6 allows current to pass only from the switching element 2 side to the power source 1 side. Even if the switching element 2 is opened and an induced voltage is generated in the solenoid 3, a reflux circuit 5 is formed in which a closed loop is formed between the solenoid 3 and the fly-hole diode 6, and a current caused by the induced voltage is circulated. Therefore, it is possible to prevent an induced voltage from being applied to the switching element 2 in the open state.
Furthermore, the solenoid drive circuit 10 connects the shunt resistor 8 between the switching element 2 and the GND 7. The shunt resistor 8 is a current measurement resistor that measures current by measuring a voltage drop (potential difference) at both ends. Here, the solenoid drive circuit 10 is provided with an LPF 30 in parallel with the shunt resistor 8. The LPF 30 includes a resistor 31 and a capacitor 32. The LPF 30 is a filter circuit that removes high frequency components and extracts low frequency components.
Since the LPF 30 relaxes a sudden voltage change, even if the shunt resistor 8 is intermittently connected to the power source 1 by opening and closing the switching element 2, the potential difference change of the shunt resistor 8 becomes continuous. Hereinafter, the detection current at the shunt resistor 8 is Pb.

Next, the detection current Pb will be described in detail with reference to FIG.
As shown in FIG. 3, the detection current Pb is filtered by the relaxation of the current change of the LPF 30, and therefore has a continuously changing waveform (solid line A in FIG. 3). Therefore, the sampling timing for reading the detection current Pb can be freely set. On the other hand, when the LPF 30 is not connected to the shunt resistor 8 (for example, the solenoid drive circuit 300 in FIG. 17), since the shunt resistor 308 is insulated from the power supply 301 when the duty is OFF, the current value becomes 0 and changes discontinuously. It becomes a waveform (broken line B in FIG. 3). Therefore, the sampling timing for reading the detected current must be set only when the duty is ON.
In this way, by providing the solenoid drive circuit 10 with the LPF 30 in parallel with the shunt resistor 8, even when the shunt resistor 8 is provided outside the reflux circuit 5, the degree of freedom in timing of current measurement can be secured.

Next, the correlation between the detected current Pb and the solenoid drive current P will be described with reference to FIG.
As shown in FIG. 4, when the horizontal axis is the detection current Pb and the vertical axis is the solenoid drive current P that actually flows through the solenoid drive circuit 10 at that time, it is proportionally linear at first, but as the detection current Pb increases. Correlation with decreasing slope is obtained. That is, the detected current Pb is not in agreement with the solenoid drive current Pb, but has a 1: 1 correlation. Therefore, correction described later is performed. This correlation is obtained by measuring the solenoid drive current P and the detection current P in a static state at each duty ratio when the duty ratio of the PWM signal Pw is changed.

Next, the detected current correction map 41 will be described in detail with reference to FIG.
As shown in FIG. 5, in the detected current correction map 41, the vertical axis indicates the estimated solenoid drive current Ps with respect to the detected current Pb on the horizontal axis. The detected current correction map 41 is a correction map that is calculated backward based on the correlation (see FIG. 4) between the detected current Pb and the solenoid drive current P that actually flows through the solenoid drive circuit 10. The detection current correction map 41 is stored in the detection current correction unit 24 in advance.

Next, the control system 51 for the solenoid drive current P will be described in detail with reference to FIG.
As shown in FIG. 6, the control system 51 is a system in which the target value is the target drive current Pm and the control amount is the solenoid drive current P. The control system 51 has a configuration in which the PWM output calculation unit 21, the switching element 2, and the solenoid 3 are arranged in the output signal path, and the shunt resistor 8, the LPF 30, and the detection current correction unit 24 are arranged in the feedback path.
With such a configuration, the solenoid drive current P is detected by the shunt resistor 8 and then filtered by the LPF 30 to obtain a detection current Pb. The detected current Pb is converted into the estimated solenoid drive current Ps by the detected current correction map 41 stored in the detected current correction unit 24.
Further, the PWM output calculation unit 21 calculates the PWM signal Pw so that the current deviation between the estimated solenoid drive current Ps and the target drive current Pm becomes small. The switching element 2 operates the solenoid 3 according to the duty ratio formed by the PWM signal Pw to generate the solenoid driving current P.
In this way, for example, even when the detection current Pb by LPF filtering does not match the solenoid drive current P, the detection current Pb can be replaced with the solenoid drive current P. That is, in the solenoid drive circuit 10, since the solenoid drive current P can be estimated by measuring the current on the GND7 side, the shunt resistor 8 can be provided outside the return circuit 5, and an insulation amplifier for current measurement can be omitted.

Next, the case where the power supply voltage V changes is demonstrated about the correlation of the detection current Pb and the solenoid drive current P using FIG.
As shown in FIG. 7, when the horizontal axis is the detection current Pb and the vertical axis is the solenoid driving current P that actually flows through the solenoid driving circuit 10 at that time, the correlation when the power supply voltage V is the rated voltage Vk and A correlation different from the rated voltage Vk is obtained in the case of the power supply voltage Va lower than the rated voltage Vk and in the case of the power supply voltage Vb higher than the rated voltage Vk.
That is, even when the same detection current Pb is detected, the solenoid drive current P varies depending on the power supply voltage.

Next, the first power supply voltage correction map 42 will be described in detail with reference to FIG.
As shown in FIG. 8, the first power supply voltage correction map 42 shows the estimated solenoid drive current Ps obtained by the detected current correction map 41 of FIG. 6, and the vertical axis shows the power supply voltage V of the estimated solenoid drive current Ps. It is the map which showed the correction value (alpha) corresponding to a change. The estimated solenoid drive current Ps on the horizontal axis is assumed to be when the power supply voltage V is the rated voltage Vk. The correction value α is calculated from the correlation between the solenoid drive current when the power supply voltage V shown in FIG. 7 is the rated voltage Vk and the solenoid drive current when the power supply voltage V is Va or Vb. The power supply voltage correction map 42 is stored in the first power supply voltage correction unit 25 in advance.

Next, the control system 52 for the solenoid drive current P will be described in detail with reference to FIG.
As shown in FIG. 9, the control system 52 is a system in which the target drive current Pm is a target value and the control amount is a solenoid drive current P. The control system 52 arranges the PWM output calculation unit 21, the switching element 2, and the solenoid 3 in the output signal path, and arranges the shunt resistor 8, the LPF 30, the detection current correction unit 24, and the first power supply voltage correction unit 25 in the feedback path. It is configured.
With such a configuration, the solenoid drive current P is detected by the shunt resistor 8 and then filtered by the LPF 30 to obtain a detection current Pb. The detected current Pb is converted into the estimated solenoid drive current Ps by the detected current correction map 41 stored in the detected current correction unit 24. The estimated solenoid drive current Ps is converted into the actual solenoid drive current Pr by the correction value α calculated by the power supply voltage correction map 42 stored in the first power supply voltage correction unit 25.
The PWM output calculation unit 21 calculates the PWM signal Pw so that the current deviation between the actual solenoid drive current Pr and the target drive current Pm becomes small. The switching element 2 operates the solenoid 3 according to the duty ratio formed by the PWM signal Pw to generate the solenoid driving current P.
By adopting such a system configuration, for example, even when the power supply voltage V increases or decreases from the rated voltage Vk, it is possible to replace the detected current with the solenoid drive current in consideration of this. Thus, in the solenoid drive circuit 10, the measurement accuracy of the solenoid drive current P is improved.

Here, another embodiment based on the control systems 51 and 52 will be described in detail with reference to FIGS. 10 to 13.
First, the control system 53 of the solenoid drive current P will be described in detail with reference to FIG.
As shown in FIG. 10, the control system 53 is a system in which the target drive current Pm is a target value and the control amount is a solenoid drive current P. The control system 53 has a configuration in which the PWM output calculation unit 21, the switching element 2, and the solenoid 3 are arranged in the output signal path, the shunt resistor 8 and the LPF 30 are arranged in the feedback path, and the target current correction unit 26 is arranged in the input path. Has been.
With such a configuration, the solenoid drive current P is detected by the shunt resistor 8 and then filtered by the LPF 30 to obtain a detection current Pb. Further, the target drive current Pm is converted into the target detection current Px by the target current correction map 43 stored in the target current correction unit 26. Details of the target current correction map 43 will be described later.
Further, the PWM output calculation unit 21 calculates the PWM signal Pw so that the current deviation between the detection current Pb and the target detection current Px becomes small. The switching element 2 operates the solenoid 3 according to the duty ratio formed by the PWM signal Pw to generate the solenoid driving current P.
In this way, as compared with the control system 51 for the solenoid drive current P, the correction calculation by the detection current correction unit 24 is performed outside the feedback path. The correction calculation in the feedback path may adversely affect the control characteristics depending on the configuration. However, by performing the correction calculation outside the feedback path, the adverse effect of the correction calculation is eliminated and the stability of the control calculation is improved. Has improved.

Next, the target current correction map 43 will be described in detail with reference to FIG.
As shown in FIG. 11, the target current correction map 43 is a map in which the target detection current Px is shown on the vertical axis with respect to the target drive current Pm on the horizontal axis. The target detection current Px is calculated backward from the correlation between the solenoid drive current P and the detection current Pb shown in FIG. The target current correction map 43 is stored in the target current correction unit 26 in advance.

Next, the control system 54 for the solenoid drive current P will be described in detail with reference to FIG.
As shown in FIG. 12, the control system 54 is a system in which the target drive current Pm is a target value and the control amount is a solenoid drive current P. The control system 54 arranges the PWM output calculation unit 21, the switching element 2, and the solenoid 3 in the output signal path, arranges the shunt resistor 8 and the LPF 30 in the feedback path, and sets the target current correction unit 26 and the second power supply voltage in the input path. The correction unit 27 is arranged.
With such a configuration, the solenoid drive current P is detected by the shunt resistor 8 and then filtered by the LPF 30 to obtain a detection current Pb.
Further, the target drive current Pm is converted into the target detection current Px by the target current correction map 43 stored in the target current correction unit 26. The target detection current Px is converted into the actual target detection current Py by the correction value β calculated by the second power supply voltage correction map 44 stored in the second power supply voltage correction unit 27. Details of the second power supply voltage correction map 44 will be described later.
Furthermore, the PWM output calculation unit 21 calculates the PWM signal Pw so that the current deviation between the detection current Pb and the actual target detection current Py becomes small. The switching element 2 operates the solenoid 3 according to the duty ratio formed by the PWM signal Pw to generate the solenoid driving current P.
In this way, as compared with the control system 52 for the solenoid drive current P, the correction calculation in the detection current correction unit 24 and the first power supply voltage correction unit 25 is performed outside the feedback path. The correction calculation in the feedback path may adversely affect the control characteristics depending on the configuration. However, by performing the correction calculation outside the feedback path, the adverse effect of the correction calculation is eliminated and the stability of the control calculation is improved. Has improved.

Next, the second power supply voltage correction map 44 will be described in detail with reference to FIG.
As shown in FIG. 13, the second power supply voltage correction map 44 is a map in which the vertical axis indicates the correction value β corresponding to the change in the power supply voltage V with respect to the target detection current Px on the horizontal axis. It is. The estimated solenoid drive current Ps on the horizontal axis is assumed to be when the power supply voltage V is the rated voltage Vk. The correction value β corresponds to the correlation between the solenoid drive current P and the detection current Pb shown in FIG. 4, the solenoid drive current when the power supply voltage V is the rated voltage Vk shown in FIG. 7, and the power supply voltage V is Va or Vb. It is calculated backward from the correlation with the solenoid drive current. The second power supply voltage correction map 44 is stored in the second power supply voltage correction unit 27 in advance.

The block diagram which shows the whole structure of the electronic governor of the diesel engine which concerns on this invention. The solenoid drive circuit diagram of an electronic governor. The current waveform figure which shows the waveform of the detection electric current filtered by LPF. The graph which shows the correlation with the detection electric current filtered with LPF, and a solenoid drive current. The graph which shows a detection electric current correction map. The block diagram which shows another control system of solenoid drive current. The graph which shows the correlation with the detection electric current filtered by LPF when a power supply voltage differs, and a solenoid drive current. The graph which shows a 1st power supply voltage correction map. The block diagram which shows the control system of the solenoid drive current which considered the change of the power supply voltage. The block diagram which shows another control system of solenoid drive current. The target electric current correction map figure. The block diagram which shows another control system of solenoid drive current. The graph which shows a 2nd power supply voltage correction map. Basic solenoid drive circuit diagram. The conventional solenoid drive circuit diagram. The solenoid drive circuit diagram of patent document 1. FIG. The solenoid drive circuit diagram of patent document 2. FIG.

Explanation of symbols

3 Solenoid 8 Shunt resistor 9 Electronic governor for engine 10 Solenoid drive circuit 21 PWM output calculation unit 30 LPF
P Solenoid drive current Pw PWM signal Pm Target drive current Pb Detection current Ps Estimated solenoid drive current Pr Actual solenoid drive current Px Target detection current Py Actual target detection current V Power supply voltage

Claims (5)

In an electronic governor for an engine in which a control signal is applied to a switching element to operate a solenoid to perform fuel metering, and one side of the switching element is grounded and a shunt resistor is provided in the grounding path.
An engine electronic governor, wherein an LPF (= Low Pass Filter) is provided between the shunt resistor and the potential difference measuring unit. The electronic governor for an engine according to claim 1,
An engine electronic governor, wherein a solenoid drive current is calculated from the detected current based on a correlation between a detected current at a shunt resistor stored in advance and a solenoid drive current, and fed back to a switching element operation signal calculation means. The electronic governor for an engine according to claim 2,
An engine electronic governor, wherein the calculated solenoid drive current is corrected based on a correlation with a change in power supply voltage of a solenoid drive current stored in advance. The electronic governor for an engine according to claim 1,
An engine electronic governor, wherein an assumed detection current is calculated from the target current based on a correlation between a target current stored in advance and a detection current at a shunt resistor, and is input as a target signal to a switching element operation signal calculation means. The electronic governor engine for an engine according to claim 4,
An electronic governor for an engine, wherein the assumed detection current is corrected based on a correlation between a detection current stored in advance and a change in power supply voltage.

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