JPH0239618B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is an engine equipped with an alternator, and is capable of controlling the engine speed to prevent the engine speed from decreasing when an electrical load is applied. It is related to the device.

(Prior art) Conventionally, in automobiles, the engine speed is controlled to a constant value by detecting the input timing of the engine load of an air conditioning compressor or the like during idling operation, and correcting the intake air amount, fuel, etc. accordingly. There is an engine speed control device designed to do this.

Among them, for example, Japanese Patent Laid-Open No. 54-98413 is an attempt to prevent the engine speed from decreasing when the engine load suddenly increases due to turning on an air conditioning compressor or changing the shift lever of an automatic car. There is something shown in the publication No.

This conventional technology provides a separate intake control valve to directly and forcibly correct the intake air amount without going through the normal engine control loop in order to speed up the response on the engine side. It is designed to operate according to load input timing such as turning on or switching the shift lever.

However, in the case of this conventional technology, even if the amount of air supplied to the engine is corrected promptly at the input timing of the load, it takes a long time before the engine can actually respond.
After all, a certain amount of time is required, which inevitably causes a follow-up delay. As a result, drawbacks such as a momentary drop in engine speed and stalling cannot be completely eliminated. Therefore, in order to eliminate such drawbacks, first the input timing of the above load is detected, and the above load is not operated from the time of detection until the engine side actually takes action (until the rotation speed increases). There was one that applied a delay to prohibit.

However, although this configuration that delays load operation can prevent a temporary drop in engine speed, the delay in load operation itself is not a good thing; Depending on the type of load, it may not be possible to adopt the above configuration.

(Object of the Invention) The present invention has been made in view of the above-mentioned points. In particular, in a device in which an alternator is driven by an engine, it is possible to cause a delay in the operation of the load when an electrical load is input. It is an object of the present invention to provide an engine rotation speed control device that can prevent the engine rotation speed from decreasing even temporarily.

(Means for Achieving the Object) In order to achieve the above object, the present invention provides a battery that serves as a power supply source for the load when the generated voltage of the alternator is lower than the load voltage, and the generated voltage is lower than the battery voltage. In an engine equipped with an engine-driven alternator that serves as a power supply source for the load when the electrical load is large, a load input detection means for detecting that an electrical load is input; Engine control means that increases the amount of engine intake air corresponding to the amount of electrical load; and field current control that increases the field current of the alternator in accordance with the input load current value required to drive the electrical load. and the load input detection means operates when the load input detection means detects a load input, and the engine output reaches an output value that can maintain the driving state of the inputted electrical load by controlling the increase in engine intake air amount by the engine control means. and field current limiting means for limiting increase control of the field current by the field current controlling means during a predetermined period of time.

(Function) According to the above configuration, when an electrical load is input in the idling operating state, the intake air amount is first corrected to increase the engine, and at the same time the engine speed reaches a predetermined value corresponding to the correction amount. Until this point is reached, increasing control of the field current will be restricted.

Therefore, even when an electrical load is input, the field current does not increase in accordance with the load until the engine speed reaches a sufficient corresponding value, and the alternator no longer becomes a factor in reducing the engine speed.
On the other hand, voltage is supplied from the battery to the electrical load at the same time as the input, and the electrical load immediately becomes operational.

(Example) In the drawings, FIGS. 1 to 3 show a first embodiment of the present invention, FIGS. 4 to 6 show a second embodiment of the present invention, and FIG. 1 and 2 respectively show a third embodiment of the present invention.

First, a first embodiment shown in FIGS. 1 to 3 will be explained.

First, FIG. 2 is a system block diagram showing a schematic configuration of the engine speed control device in the first embodiment, FIG. 1 is an electric circuit diagram of the main part thereof, and FIG. This is a time chart of the main parts of the signal in the figure.

In FIG. 2, reference numeral 1 indicates an engine, 2 a cylinder, 3 an intake pipe, and 4 an exhaust pipe. In the intake pipe 3, there is an intake air temperature sensor 6 located in the air cleaner section 5, an air flow meter 7 on the intake downstream side of the air cleaner section 5, and a throttle valve 8 and a throttle opening sensor 9 on the intake downstream side. are provided respectively, and the other exhaust pipe 4 is provided with an O ₂ sensor 10. Further, reference numeral 11 is a fuel injector provided at the engine side end of the intake pipe 3, 12 is a water temperature sensor for detecting the temperature of cooling water, 13 is a solenoid valve for controlling intake air amount, 1
4 is an air valve for fast idle up. The solenoid valve 13 and the fast idle up air valve 14 are each provided in a bypass passage 41 that bypasses the throttle valve 8 in the intake pipe 3. moreover,
Reference numeral 15 is a pressure sensor that detects negative pressure within the intake pipe 3, and reference numeral 16 is an alternator driven by the engine.

Each of the above-mentioned members indicated by reference numerals 6 to 16 is connected to the engine electronic control device 17, and
Based on a predetermined control program, various controls are performed depending on the operating state and load amount of the engine.

On the other hand, the engine electronic control device 17 is further connected to a load input detection means 20 for detecting input of electrical loads such as a distributor 18 for engine ignition, an igniter 19, and a headlight. Note that the reference numeral 21 is a battery.

Here, the basic operation of the engine 1 shown in FIG. 2 during idling operation will be explained.
The throttle opening degree signal from the engine and the engine speed signal from the distributor 18 (which in this embodiment also serves as the engine speed detecting means in the claims) are input to the engine electronic control device 17, and Therefore, when it is determined that the engine 1 is in the idle operating state, the intake air amount is controlled by the solenoid valve (corresponding to engine control means in the claims) 13 provided in the bypass passage 41, At the same time, the fuel injection amount is also controlled and the idle speed is controlled.

That is, when the engine 1 is in an idling operating state, if the rotational speed of the engine 1 deviates from the set idle rotational speed by turning on and off various loads, the opening degree of the solenoid valve 13 is feedback-controlled, and accordingly The intake air amount and fuel injection amount are controlled so that the engine speed converges to the target speed. In this case, the loads that cause the engine speed to fluctuate include mechanical loads such as air conditioning compressors, and electrical loads such as headlamps and power window motors. Even if the engine is under load, when the engine speed during idle operation deviates from the set idle speed due to the ON/OFF of the load, the above-described feedback control of the speed is performed. In addition, the air valve 1 for fast idle up is provided in parallel with the solenoid valve 13.
4 is maintained at a constant opening independently of the solenoid valve 13 when the engine 1 is in a low temperature state, such as immediately after starting (detected by the water temperature signal from the water temperature sensor 12), and controls the idle speed of the engine 1. It functions to maintain the rotational speed above a predetermined rotational speed, which is higher than the normal idle rotational speed.

Next, the main control circuits of the engine control system shown in FIG. 2 that are relevant to the present invention will be described with reference to FIG. 1.

In FIG. 1, the reference numeral 20 is the load input detection means described above, which detects when the load switch 23 of the electrical load 22 such as a headlight or a motor for a power seat is turned on (FIG. 3a). A predetermined load detection signal (FIG. 3b) consisting of, for example, a differential pulse is generated. This load detection signal is sent to the load correction circuit 24 provided in the engine control circuit shown in FIG.
6, respectively supplied to the switching circuit 27.

The load correction circuit 24 operates in response to the input of the load detection signal (FIG. 3d), determines the amount of correction (increase) in the amount of intake air supplied to the engine, and generates an output corresponding to the amount of correction. It is supplied to the engine speed control circuit 28. Engine speed control circuit 28
is operated to increase the rotational speed of the engine by controlling the opening degree of the solenoid valve 13 shown in FIG. 2 in accordance with the above-mentioned correction amount.

The battery voltage comparison circuit 25 compares the actual battery voltage at the time of load input with reference to the battery voltage limit value required for normal operation of the engine electronic control device 17, and when the actual battery voltage is higher than the reference value, It generates an H output to set the timing adjustment circuit 29 in the next stage, and on the other hand, when the actual battery voltage is below the reference value, it generates an L output to reset the timing adjustment circuit 29.

Further, the engine rotation speed detection circuit 26 detects whether or not the load on the engine side due to the operation of the load correction circuit 24 can be handled, that is, detects the engine rotation speed corresponding to the load amount, and determines whether or not the response state is possible. and generates an H output when it cannot be handled.

The timing adjustment circuit 29 has a function as, for example, an AND circuit, and generates an output at the timing when the outputs of the battery voltage comparison circuit 25 and the engine rotation speed detection circuit 26 are both in the H state, and The movable terminal 30 is switched from the contact 27a side to the contact 27b side. On the other hand, the contact 27a of the switching circuit 27 is directly connected to the monostable multivibrator circuit 32, and the other contact 27b is connected to the monostable multivibrator circuit 32 via the field current adjusting means 31 until the engine is ready. Therefore, the load input detection signal of the load input detection means 20 indicates that the actual battery voltage is determined by the electronic control unit 17 when the load is input as described above.
If the engine speed does not correspond to the load at a reference voltage higher than the reference voltage required for the operation of At the same time, if the actual battery voltage is lower than the reference voltage and the engine speed sufficiently corresponds to the load, the trigger signal is directly supplied to the monostable multivibrator circuit 32.

On the other hand, the monostable multivibrator circuit 32 is
As the duty ratio variable signal of the oscillation output, an engine rotation speed detection signal is supplied from the engine rotation speed detection circuit 26, and a pulse signal (FIG. 3c) having a duty ratio corresponding to the signal value is generated.

On the other hand, the movable terminal 30 of the switching circuit 27
In the normal state on the a side, the field current adjusting means 31 is cut off, and the field current is normally controlled in accordance with the original load current.

Next, reference numeral 34 is a voltage adjustment circuit (IC regulator) as a means for controlling the generated voltage of the alternator;
Reference numeral 35 is a field coil of the alternator 16, and reference numeral 36 is a diode trio circuit for full-wave rectification of the alternator 16. The L terminal of the voltage adjustment circuit 34 is connected to one side of the field coil 35 and the load side, the F terminal is connected to the other side of the field coil 35, and the E terminal is connected to the ground side. In the case of this embodiment, the reference value setting section for field current adjustment (limiting) operation is, for example, resistors R ₁ and R ₂
and an auxiliary power supply E inserted in parallel with the voltage dividing circuit and connected to the battery ₂₁ via a switch S. (voltage applied to) is controlled in relation to the L point voltage.

In other words, considering the normal low-speed rotation state with switch S turned OFF, the alternator 16
The generated current is passed through the auxiliary diodes D ₁ to _{D 3} to the field coil 35 and the F terminal and L
It is supplied to the terminal and battery 21, respectively. On the other hand, the current of the auxiliary power supply E is the Zener diode ZD
It is supplied to the above-mentioned resistors R ₁ and R ₂ on the side. In this state, the value of the resistor R ₂ is small, and the Zener diode ZD does not become conductive depending on the value of the current flowing through the resistor R ₂ . Therefore, in this state, as the engine speed increases, the field current flowing through the field coil 35 also increases accordingly. From this state, if switch S is turned on, the voltage across resistor _R2 will change to a Zener diode due to the above field current.
The value increases to a value sufficient to make ZD conductive, and the Zener diode ZD becomes conductive, so that transistor Q ₁ is turned on, while transistors Q ₂ ,
Since _Q3 is turned off, the field current rapidly decreases, and the voltage generated by the alternator 16 also decreases.
Then, when the voltage across resistor _R2 decreases, again,
Zener diode ZD is turned off and the above operation is repeated again.

That is, for example, in the above-mentioned low-speed rotation state, the battery voltage at the time of the load input (Fig. 3 e) is detected by the battery voltage detection means 40, and the battery voltage detection means 40 converts the detection signal into the battery voltage. The reference value adjustment means 33 having a determination function is supplied. The reference value adjusting means 33 operates when the battery voltage is below a predetermined value (t in Figure 3 e), generates the output of the monostable multivibrator circuit 32 as its output, and turns off the switch S which is in the OFF state. Turn it on. the result,
The battery 21 in the voltage drop state is substantially separated from the voltage dividing circuit of the resistors R ₁ and R ₂ , and the voltage of the auxiliary power supply E acts on the L point as the battery voltage. And the resistance of the voltage divider circuit
R ₂ has the above normal voltage V ₁ state (A in Figure 3 f)
The current from the auxiliary power source E and the field current are supplied, and the reference voltage generated across the resistor _R2 is set to a constant value higher than the previous value by a predetermined value. Therefore, the value of the field current itself is also maintained at a constant value (FIG. 3g) set thereby. This holding state continues until the movable terminal 30 of the switching circuit 27 is switched to the contact 27a side unless another load is input, that is, until the engine speed becomes a state corresponding to the load input. In this case, if another load is input within or outside the field current adjustment time, the corresponding load input detection means 20 will generate a differential pulse at the rising edge each time. From that point on, the field current adjusting means 31 operates again to gradually increase the field current,
After a predetermined time, it is configured to operate to maintain a constant value that is a predetermined value larger than before.

Therefore, in the above configuration, even if an electrical load is input, the field current will not increase at all due to the action of the auxiliary power source E until the engine side can sufficiently respond to it. Since it does not act as a load on the engine, the engine speed does not decrease when the load is input.

During this time, current is supplied from the battery 21 to the input electrical load, and the electrical load becomes operational at the same time as the input. Note that the operation of the electrical load by the battery 21 is a temporary reduction until the engine is able to respond to the electrical load (the engine speed actually increases), and normally the time is less than 1 second at most. It is.

When the rotational speed of the engine increases to a predetermined set rotational speed to correspond to the electrical load, a field current corresponding to the electrical load current is supplied as described above. In that case, the engine output required to drive the alternator 16 also increases, but at that time the engine speed is increased to a speed that can sufficiently handle the electrical load, so the input of the electrical load is increased. Problems such as poor idle speed and engine stalling caused by this can be prevented.

In the above embodiment, the battery voltage is detected in synchronization with the load input, and when the detected value is below a predetermined value, the auxiliary power supply E is turned on, and the field current is controlled using the absolute value of the battery power supply as a whole. The reference voltage of the first embodiment is made variable, but as another embodiment developed from this first embodiment, the following (1):
A configuration like (2) is also possible.

(1) The amount of voltage drop in the battery itself is specifically detected, and the value of resistor R ₂ is made variable according to the detected value (for example, resistor R ₂ is made a voltage variable resistor).

(2) For example, a current limiting means is employed to set the output current of the alternator itself to a predetermined upper limit value. In this case, by setting the upper limit value to be slightly higher than the value before the load input, the load on the battery itself can be reduced by that much and the life of the battery can be extended.

Furthermore, in the above embodiment, the reference value adjustment time for field current control is determined by detecting the engine speed, but this can also be specifically set in advance using a timer. It is.

Next, a second embodiment of the present invention shown in FIGS. 4 to 6 will be described. This second embodiment realizes the same functions as those of the first embodiment as the contents of a control program of an electronic control device. FIG. 4 shows a block diagram of the control circuit of the engine speed control device according to the second embodiment, and FIG.
Figures A and B are flowcharts of the control operation, and FIG. 6 is a time chart of operating signals of the main parts of the control circuit of FIG. 4.

First, in FIG. 4, the reference numeral 37 is energized by turning on the load switch 23 (FIG. 6a).
This is a differentiation circuit as a load input detection means for obtaining the differential pulse in the rising state (Fig. 6b),
The output pulse is supplied to a monostable multivibrator circuit 38 as a trigger signal. The monostable multivibrator circuit 38 is triggered by the differential pulse and has a variable transmission time constant in response to an engine rotational speed detection signal supplied from an engine electronic control device 39, which will be described later. An output pulse (FIG. 6c) with a pulse width corresponding to the number of rotations (the lower the rotation speed, the larger the width) is generated, and this pulse signal is input to the engine electronic control device 39.

The engine electronic control device 39 further includes a first
A field current (FIG. 6d) is detected and supplied from a voltage adjustment circuit 36 similar to that in the embodiment described above, and a battery voltage detection signal is supplied from a battery voltage detection circuit 40.

In FIG. 4, the voltage adjustment circuit indicated by the reference numeral 36, as well as the alternator 16, field coil 35, battery 21, etc., have exactly the same configuration as those of the first embodiment shown in FIG. , works similarly.

Next, the above control operation will be explained.

Figure 5A shows the field current detection signal.
The first one that performs interrupt operation by turning ON or OFF.
FIG. 5B is a flowchart showing the second control operation in which an interrupt operation is performed by the output signal of the differentiating circuit 37 as the load input detection means.

Now, if the Zener diode ZD of the voltage adjustment circuit 36 in FIG. 4 is ON, the transistors Q ₂ ,
Since Q ₃ is OFF, no field current flows,
The field current detection signal becomes H, and this H signal indicates that the field current is OFF. On the other hand, the above Zener diode
When ZD is OFF, transistors Q ₂ and Q ₃
Since it is ON, the field current detection signal is L, indicating that the field current is ON, and the detection signal becomes a signal in which these H and L are continuous (FIG. 6d).

When the field current is turned on, the control program of the electronic control unit 39 is interrupted and the first control operation is started.

When the control operation starts, first, in step _S1 , a predetermined interrupt time is set in consideration of the engine response time, and in the next step _S2 , it is determined whether the field current rises or falls. According to the determination result, in the case of a rise, the L level time (OFF time) from the load input time of the field current to a predetermined time before that is counted (step S ₃ ). next,
Each cycle (OFF time) of each L level signal within the counting time is individually calculated (step S ₄ ).
Then, the average value of the OFF time is calculated by dividing the total value by the number of pieces (step _S5 ).

On the other hand, if the judgment result in step _S2 is falling, first, in step _S6 , the existence time (ON time) of the H level signal from the time of load input to a predetermined time before that is counted, and then in step S6. Count their individual times in _S7 . Then, in step _S8 , the average value thereof is calculated in the same manner as in step _S5 , and in step _S9 , the duty ratio of the two is calculated. The control operation then returns to its original state.

On the other hand, a second control operation is performed in parallel to the first control operation. In this second control operation, as in the case of the first embodiment, first, the battery voltage is detected based on the voltage necessary for the operation of the electronic control unit 39, and it is determined that the detected voltage is above a certain value. Starts interrupt operation as a condition.

That is, first, in step _S11 , it is determined whether or not the battery voltage is above a certain value, and if it is below the certain value, the duty ratio generating operation of the first control operation is reset (step S12) and the step _S12 is started. At _S13 , the switch S is turned off, and the field current control signal (Fig. 6e) to the voltage adjustment circuit 34 is always maintained in the H state (normal charging state).

On the other hand, if the battery voltage is above a certain value as a result of the battery voltage determination, the monostable multivibrator circuit 38 is triggered by the output of the differentiation circuit 37 as the load input detection means described above.
The interrupt operation is started by the output signal (FIG. 6c), and first, in step _S14 , it is determined whether the signal is rising or falling. Then, in the case of falling, step S ₁₂ is performed in the same way as when the battery voltage is below the above-mentioned fixed value with no load input.
Switch S is turned OFF by _S13 , and the field current control signal is always in the H state.

On the other hand, when the output of the monostable multivibrator circuit 38 is rising, the duty ratio calculated in the first control operation described above is changed to the data signal (sixth
d) is supplied to the switch S as a reference value adjustment signal for field current control. Switch S
is driven ON and OFF according to the duty ratio of this signal, and when viewed as an average value within a predetermined time until the engine responds, the field current is the permissible limit value for the engine speed drop. When the load current is large, it is maintained at a constant value (FIG. 6f) that is smaller than the load current value.

Therefore, even when an electrical load is input,
The alternator 16 itself does not immediately become a load that causes a decrease in engine speed, and the engine speed decreases little. Moreover, the field current that corresponds to the load current is actually applied only after the correction of the intake air amount on the engine side has been completed and the engine is in a state that can sufficiently handle the load. The decrease in the number can also be sufficiently suppressed. And during this time,
Since the electrical load is supplied with voltage from the battery 21, it goes without saying that the electrical load itself becomes operational at the same time as the voltage is input.

Furthermore, a third embodiment of the present invention shown in FIG. 7 will be described. FIG. 7 shows a hardware configuration of the same functions as those of the second embodiment shown in FIG. 4 described above.

In addition, the alternator 16 and the field coil 35, the diode trio circuit 36, the power generation voltage adjustment circuit 34 of the alternator 16, the battery 21,
The load 28, load switch 23, etc. are
Since it is exactly the same as the one in the figure and performs the same operation, its explanation will be omitted with the explanation of FIG. 4.

Next, in FIG. 7, reference numeral 37 is a load input detection means for detecting that the electrical load 28 is applied to the output circuit of the alternator 16 or battery 28 by turning on the load switch 23 (FIG. 6a). The differential circuit outputs the load input detection signal shown in FIG. 6b at the time of detection. This output signal is sent to a load correction circuit 24 similar to that shown in FIG.
and a monostable multivibrator circuit 38, respectively.

The load correction circuit 24 operates in response to the load input detection signal (FIG. 6d), and similarly to the case described above, in order to correct the engine intake air amount according to the load amount and increase the engine speed ( act so as not to deteriorate).

On the other hand, the monostable multivibrator circuit 38 is
The duty ratio of the generated pulses is varied according to the detected value of the engine rotation speed that is triggered by the load input detection signal and is supplied from the engine rotation speed detection circuit 26, and the duty ratio (rotation speed) according to the engine rotation speed is varied. A pulse signal (FIG. 6c) with a lower number is larger) is output.

On the other hand, in the load input state during idling, the engine speed is low and the voltage generated by the alternator 16 itself is low, so the battery 21 acts as a power supply source for the load 28 in this state. Therefore, the terminal voltage of the battery 21 (sixth
Figure e) is greatly reduced by the above load input. As a result, the alternator 16, which is already in a power generation state, comes to act as an engine load to further increase the field current generated by the generated current.

Next, in such a state, the output of the monostable multivibrator circuit 38 is supplied to a battery voltage determination circuit 42 serving as a reference value adjusting means. The battery voltage determination circuit 42 detects the detection value (sixth
Based on FIG. Turn on/off the switch S similar to the case in Figure 4.
Control. Then, when the switch S is turned on, the auxiliary power source E is inserted in parallel to the battery 21 via the switch S, and the fourth
Just as in the case shown in the figure, the battery voltage for the L terminal of the generated voltage adjustment circuit 34 of the alternator 16 is backed up by the voltage of the auxiliary power supply E (FIG. 6f) and maintained at a normal value (V ₁ ).
As a result, the voltage across the resistor _R2 also increases, and the timing for turning on the Zener diode ZD becomes longer. As a result, just as in the case of Fig. 4, until the response on the engine side is completed after load input, the field current of alternator 16 will be a predetermined value higher than the value before load input, when viewed as an average value. a constant value higher than the load current (6th
(g), that is, the engine rotational speed is limited within the permissible limit value for lowering the engine speed. Therefore, the alternator 16 is prevented from becoming a factor in reducing the engine speed when the electrical load is applied.

In addition, in each of the above embodiments, if another load is inputted again during the field current adjustment (reference value adjustment) time described above, the reference voltage is changed to the engine rotation speed accordingly. The field current is adjusted arbitrarily to some extent within the allowable limit value of the decrease, and stepwise control is performed so as to increase the field current by a certain amount. Thereby, even if a continuous load is input, it is possible to suppress fluctuations in engine speed to a minimum. In this case, if a new load is input immediately after the above adjustment time has elapsed, the same control as above can be performed again from that point, as described above. It is more effective to set the reference value (the immediately preceding value) according to the amount of increase in the number of rotations because it can reduce the battery burden.

(Effects of the Invention) As explained above, the present invention provides a battery that serves as a power supply source for the load when the generated voltage of the alternator is lower than the load voltage, and a battery that serves as the power supply source for the load when the generated voltage of the alternator is higher than the battery voltage. In an engine equipped with an engine-driven alternator serving as a power supply source, a load input detection means for detecting that an electrical load is input; an engine control means that performs an increase correction of the corresponding engine intake air amount; a field current control means that increases and controls the field current of the alternator in accordance with the load current value required to drive the input electrical load; and the load input. It operates when the detection means detects the load input, and within a predetermined period of time until the engine output reaches an output value that can maintain the driving state of the input electrical load due to the increase control of the engine intake air amount by the engine control means. The present invention is characterized in that it comprises field current limiting means for limiting increase control of the field current by the field current controlling means.

Therefore, according to the present invention, even during idling operation, it is possible to operate the electrical load at the same time as the electrical load is input, and the engine corrects the intake air amount accordingly. On the other hand, the increase control of the field current is restricted until the engine side can respond to the electrical load. Therefore, even if an electrical load such as a headlight or a power seat motor is applied during idling, the alternator itself is unlikely to cause a decrease in the rotational speed of the engine, and the engine rotational speed will not decrease much when the load is input. In addition, when the field current is finally applied in accordance with the load current value, the engine side has already taken adequate measures, so the drop in engine speed in that case can be suppressed to a minimum, and the engine is idling. Problems such as rotational problems and engine stalling during operation can be prevented.

Furthermore, by setting the limit value of the field current to a value that is smaller than the load current value but larger than the value before load input by a predetermined value, the load on the battery itself is reduced accordingly, thereby extending the life of the battery. There is also the advantage that it becomes possible.

[Brief explanation of drawings]

FIG. 1 is a control circuit diagram of main parts of an engine rotation speed control device according to a first embodiment of the present invention, and a second embodiment of the present invention is shown in FIG.
The figure is a system block diagram showing the control circuit of the engine rotation speed control device in the above embodiment.
5 is a time chart of the signals of the main parts of the control circuit shown in FIG. 1, FIG. 4 is a control circuit diagram of the main parts of the engine speed control device according to the second embodiment of the present invention A and B are flowcharts for explaining the control operation of the control circuit shown in FIG. 4,
FIG. 6 is a time chart of signals of essential parts of the control circuit of FIG. 4, and FIG. 7 is a control circuit diagram of an engine rotation speed control device in a third embodiment of the present invention. 1...Engine, 16...Alternator, 1
7, 39... Engine electronic control device, 20... Load input detection means, 21... Battery, 22... Electric load, 24... Load correction circuit, 26... Engine rotation speed detection circuit, 28... Engine rotation numerical control circuit, 31... field current adjustment means, 32,
38... Monostable multivibrator circuit, 33...
...Reference value adjustment means, 35...Field coil,
37...Differential circuit, 42...Battery voltage judgment circuit, _E1 ...Auxiliary power supply, _S1 ...Switch, _R1 , _R2
...Divider resistance.

Claims (1)

[Claims] 1. An engine equipped with a battery that serves as a power supply source for the load when the generated voltage of the alternator is lower than the load voltage, and an engine-driven alternator that serves as the power supply source for the load when the generated voltage is higher than the battery voltage. load input detection means for detecting that an electrical load is input; and engine control means for increasing the engine intake air amount corresponding to the load amount of the electrical load when the electrical load is input; field current control means for increasing and controlling the field current of the alternator in accordance with the input load current value required to drive the electrical load; and field current control means that operates when the load input detection means detects a load input, A field that limits the increase control of the field current by the field current control means within a predetermined time until the engine output reaches an output value that can maintain the driving state of the input electrical load due to the increase control of the engine intake air amount. An engine rotation speed control device comprising current limiting means.