JP2740567B2 - Engine speed control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rotation speed control device when an engine is in an overload operation state.

(Prior Art) A proportional / integral / differential (PID) operation is performed on a voltage (deviation) corresponding to a difference between an actual engine speed and a target engine speed, and a fuel injection amount is adjusted based on the operation output. Techniques for controlling the engine speed are known.

 FIG. 4 is a block diagram showing a conventional control system.

The rotation speed of the engine 100 is determined by the gear 102 provided on the output shaft 101.
Rotation is detected by a non-contact type engine rotation sensor 103,
A pulse signal P _n of the period corresponding to the rotational speed is generated, the signal P _n frequency - converting the voltage converter corresponding to the analog voltage e _n in (F-V converter) 104. Enter the difference Δe between the voltage e _s, corresponding to the target speed given by the voltage e _n and the target rotational speed setting means 105 in the PID operation circuit 106, the proportional amplifier 107, integrating circuit 108, the differentiating circuit 109 After performing each operation of proportional, integral, and derivative, respectively, the fuel injection device 110
To adjust the fuel injection amount to control the rotation speed of the engine 100.

(Problems to be Solved by the Invention) In a device that performs this type of feedback control, a fuel injection mechanism (actuator) is driven to further increase the fuel injection amount (fuel supply amount) as the engine load increases. However, it cannot cope with engine overload exceeding the maximum injection position. In such an overload operation state, the engine speed decreases. This decrease in the number of revolutions is accompanied by a decrease in the output of the engine, which may lead to a further decrease in the driving force of the load and sometimes cause a stall.

For example, when driving a synchronous generator that generates commercial frequency power as a load, if a load such as a mercury lamp or an electric motor through which a temporary large current flows at startup is connected to the output side of the generator, the generator itself will The engine becomes temporarily overloaded and an engine overload condition occurs. When the engine speed decreases with this overload, the power of the engine, that is, the output power of the generator also decreases, and it takes time to return to the steady operation of the device despite the temporary overload, During this time, the output frequency of the generator also decreases.

On the other hand, in the patent application (Japanese Patent Application No. 1-295632) filed by the applicant of the present invention, a significant decrease in the engine speed and a concomitant decrease in the engine output in an overload operation state of the engine are described. In order to prevent this, if the rotation speed discrimination means does not detect that the engine rotation speed is increasing even though the fuel injection amount adjusting mechanism is detected to be at the substantially maximum injection position, the engine may be overdriven. By determining that the vehicle is in the load operation state and outputting an overload detection signal, and by controlling the engine load with the overload detection signal, the engine power can be reduced without lowering the engine speed. It proposes an engine speed control device that can be used at the maximum.

By the way, when this is to be applied to a fuel supply amount adjusting mechanism in which the upper limit of operation of the actuator is mechanically restricted, such as a throttle control device of a gasoline engine, the maximum position of the actuator and the maximum position of the feedback signal are determined. However, it is difficult to assemble them with the actual assembly.However, if the maximum position of the feedback signal is set to a position exceeding the mechanical maximum position of the actuator, there is a problem that the control performance is significantly reduced. Was.

The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to detect an engine overload state in a case where the upper limit of operation of an actuator is mechanically regulated. And outputs a signal to suppress the engine load side, or gives a warning to the user side, etc., to prevent the engine speed from dropping due to the engine overload and effectively use the maximum output of the engine. It is an object to provide an engine speed control device.

(Means for Solving the Problems) In order to solve the above problems, an engine speed control device of an engine according to the present invention is an engine speed control device of an engine driven work machine that drives a work machine with an engine, A fuel supply device having a supply amount adjusting mechanism, an electromagnetic actuator for driving the fuel supply amount adjusting mechanism, and an energization state detecting means for detecting a fuel supply amount of the fuel supply device as a signal corresponding to an energization current of the electromagnetic actuator When,
An engine speed detecting means for outputting a signal corresponding to the engine speed as a signal corresponding to the engine speed, and a maximum fuel supply state for determining whether or not the fuel supply amount detected by the power supply state detecting means is substantially the maximum supply amount Detecting means for detecting whether or not the engine speed detected by the speed detecting means is increasing at a rate of change equal to or higher than a predetermined value. If the engine speed is not determined to be increasing at a rate of change equal to or greater than a predetermined value by the engine speed determination means even though it is determined that The engine is maintained and controlled to a substantially maximum output state by outputting a load state signal to reduce the load on the work implement itself.

When the engine load is composed of a generator,
Control may be performed so that the output set voltage of the automatic voltage regulator of the generator is apparently reduced by the overload signal.

(Operation) The engine rotation speed control device according to the present invention includes a fuel supply amount adjusting mechanism, a fuel supply device having an electromagnetic actuator for driving the fuel supply amount adjustment mechanism, and a fuel supply amount of the fuel supply device. Energization state detection means for detecting as a signal corresponding to the energization current of the electromagnetic actuator, engine rotation number detection means for outputting the engine speed as a signal corresponding to the rotation number, and fuel supply detected by the energization state detection means Maximum fuel supply state detecting means for determining whether or not the amount is substantially the maximum supply amount, and determining whether or not the engine speed detected by the speed detecting means is increasing at a rate of change equal to or higher than a predetermined value. Since the rotation speed discriminating means is provided, the rotation speed discriminating means is provided even if the fuel supply amount is determined to be substantially maximum by the maximum fuel supply amount state detecting means. Therefore, when it is not determined that the engine speed is increasing at a rate of change equal to or higher than the predetermined value, the overload control unit outputs an overload state signal to the work implement to reduce the load on the work implement itself to reduce the load on the work implement itself. It is possible to maintain and control a substantially maximum output state. As a result, it is possible to prevent a significant decrease in the number of revolutions of the engine and a resulting decrease in the engine output.

When the engine load is a generator, the output speed of the automatic voltage regulator of the generator is apparently reduced by the overload detection signal, so that the engine speed can be maintained at a predetermined speed. Even when a synchronous generator is used, its output frequency is kept stable.

(Example) Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an overall system configuration diagram of an engine generator provided with an engine speed control device according to the present invention.

The engine generator 1 includes a rotation speed control device 3 for automatically controlling the engine rotation speed by adjusting the amount of fuel supplied to the engine 2.
And a generator 4 driven by the engine 2.

The rotation speed control device 3 applies a voltage e _s corresponding to the target rotation speed set by the target rotation setting circuit 5 to one input of a proportional / integral / differential operation circuit (hereinafter referred to as a PID circuit) 7 via a superimposing circuit 6. It is applied with the machine terminals 7a, by applying a voltage signal e _n corresponding to the actual revolution speed of the engine 2 to the other input terminal 7b, proportional-integral to the differential voltage of the two voltage signals (e _s -e _n)・
An output voltage e _o that has been subjected to a differential operation is generated, and is output via a PWM (pulse width modulation) conversion circuit 8 to an NPN power transistor _Tr.
In this switching operation, the solenoid type actuator 9a of the throttle control device 9 as a fuel supply amount adjusting mechanism is driven to increase or decrease the fuel supply amount, thereby controlling the rotation speed of the engine 2.

Revolution detecting means 10 constituting engine revolution detecting means 10
Outputs a pulse signal P _n of a period proportional to the rotational speed of the engine, the pulse signal P _n is the frequency - converted by voltage conversion circuit 11 into an analog voltage e _n corresponding to the period of the pulse signal P _n.

The position of the solenoid actuator 9a is detected by an actuator position sensor 12, and the position detection output 12a is converted into _a DC signal ea by _a detection / rectification circuit 13. DC signal
e _a is amplified by the noninverting amplifier 14, the output 14a is inputted to the inverting input terminal 6b of the operational amplifier 6d in superimposing circuit 6 through the capacitor 6a.

When detection and rectifying circuit 13 is an actuator position sensor 12 based on the output 12a of the actuator position sensor 12 is positioned on the fuel increase side the throttle opening increases, and is configured such that the position detection output voltage e _a is increased. The output e _a of the detection / rectification circuit 13 is DC-amplified by the non-inverting amplification circuit 14,
The voltage corresponding to the change in the actuator position is differentiated through a differentiating circuit including the capacitor 6a and the resistor 6c, and is input to the inverting input terminal 6b of the operational amplifier 6d. The non-inverting input terminal 6e of the operational amplifier 6d output voltage e _s desired speed setting circuit 5 is applied. In a state where the differential input voltage to the inverting input terminal 6b is not applied, the output voltage of the superimposing circuit 6 is the same as the voltage of e _s, if the actuator position is moved to the fuel increase side by the input from the differentiation circuit 6a, 6c, the output voltage of the superimposing circuit 6 becomes a voltage lower than the voltage e _s, when moved to the fuel decrease side is configured to be a voltage higher than the voltage e _s.

The PID circuit 7 includes an operational amplifier 7c and an integrating circuit 15 provided between an output terminal 7d and an inverting input terminal 7e of the operational amplifier 7c.
And an input resistor 16 having one end connected to the inverting input terminal 7e;
An arithmetic circuit is configured by the input resistance and the differentiating circuit 17 connected in parallel. The integrating circuit 15 includes a capacitor 15a,
It is composed of three elements consisting of a series circuit of a capacitor 15b and a resistor 15c connected in parallel to the capacitor 15a. The differentiating circuit 17 is configured by a series circuit of a capacitor 17a and a resistor 17b.

The power transistor _Tr connects the base B to the PWM conversion circuit 8
The collector C is connected to one end of a parallel circuit of the solenoid type actuator 9a and the diode D, and the emitter E is connected to GND.

Output voltage V _CE collector C is the resistance 18b from the input terminal 18a of the energization state detection means 18, and 18C, through a smoothing circuit comprising a capacitor 18d of the voltage comparator 18e - applied to the input terminal 18f. A reference voltage is applied to a + input terminal 18g of the voltage comparator 18e from a reference voltage generation circuit 18h. The reference voltage is the collector-emitter voltage V _CE when the current supplied to the solenoid actuator 9a of the throttle control device 9 becomes substantially maximum state. Therefore, during normal control, the input voltage to the-input terminal 18f of the voltage comparator 18e is +
Since the input voltage is larger than the input voltage of the input terminal 18g, this detecting means 1
The output 18i of the output 8 is at the L level, but when the current supplied to the solenoid actuator 9a is substantially at the maximum value, the -input terminal 18f
The output 18i is at the H level since the input voltage of the + input terminal 18g is higher than that of the + input terminal 18g.

Frequency - the output voltage e _n of the voltage conversion circuit 11 is applied to the input terminal 19a of the rotation speed determining means 19, through the resistor 19b of the voltage comparator 19d - is input to the input terminal 19c. Voltage comparator 19d
A resistor 19f is connected between the negative input terminal 19c and the positive input terminal 19e. Further, the + input terminal 19e is connected to a + power supply + V via a resistor 19g, and to a GND via a capacitor 19h. Therefore, the frequency - If the output voltage e _n of the voltage conversion circuit 11 has risen at a predetermined time constant, - higher than the voltage of the voltage input terminal 19c is + input terminal 19e, the output 19i of the voltage comparator 19d is is a L level, when the output voltage e _n is or reduce to hold the predetermined time the same value, + voltage input terminal 19e is - becomes higher than the voltage of the input terminal 19c, the output of the voltage comparator 19d 19i Becomes H level.

Output 18i of energization state detection means 18 and rotation speed determination means 1
The outputs 19i of the 9 are input to the AND circuit 20a in the engine overload control means 20 constituting the overload control means, and the output thereof drives the transistor 20c via the resistor 20b. When the transistor 20c is turned on, a current is supplied via the resistor 3b in a path of terminal 3c-terminal 4a-light emitting diode in the synchronous generator 4-terminal 4b-terminal 3a, and the engine 2 is driven to the synchronous generator 4 side. Notify that an overload condition has occurred.

The generator 4 is configured to, when receiving the engine overload signal, reduce the output voltage of the power generation output terminals 4c and 4d to reduce the power supplied to the electric load 21.

 FIG. 2 is a circuit configuration diagram of the generator.

The generator 4 includes a winding part 22 and an output voltage adjusting circuit 23.

The winding part 22 includes a field winding 22b wound around the rotor 22a,
An output winding 22c, an output voltage detection winding 22d, and an excitation winding 22e for supplying current to the field winding 22b are provided on the stator side. The output winding 22c is connected to the power generation output terminals 4c and 4d.

The AC voltage generated in the exciting winding 22e is full-wave rectified by a diode bridge 24, smoothed by a capacitor 25, and a base current is supplied to a transistor 27 via a base resistor 26, so that the transistor 27 is turned on and the field winding is turned on. It is configured to supply current to line 22b.

The AC voltage generated in the voltage detecting winding 22d is full-wave rectified by the diode bridge 28, and becomes a voltage waveform including a pulsating component as shown in FIG. 3A by a smoothing circuit including a resistor 29 and a capacitor 30. After being smoothed, the voltage is divided by the resistors 31 and 32, and the divided voltage is applied to the Zener diode 33.
Is applied to the base of the transistor 34.

When the AC voltage generated in the voltage detection winding 22d is higher than a predetermined voltage value, the period during which the base current is supplied to the transistor 34 (the period indicated by oblique lines in FIG. Is turned on → the transistor 27 is turned off, the period during which the current supply to the field winding 21b is cut off becomes longer, and the power generation output voltage decreases. Thus, the field stopper 21
By may differ a current supply time to b, and the power output terminal 4c, the output voltage e _o generated between 4d holds the rated value. The diode 3 connected in parallel to the field winding 22b
5 is the field winding 2 during the switching operation of the transistor 27.
This is a cross-flow diode for absorbing the surge generated in 2b.

A light emitting diode 36a, which is the primary side of the photocoupler 36, is interposed between the terminals 4a and 4b, and the secondary side phototransistor 3
When 6b is turned on, the capacitor 39 is routed through the diode 37, the phototransistor 36b, the resistor 38, and the capacitor 39.
Is charged, and this voltage is applied to the anode side of the Zener diode 33 via the diode 40 and the resistor 41. Therefore, the voltage on the anode side of the Zener diode 33 becomes the third voltage.
As shown in FIG. 3B, the pulsating flow becomes smaller, and the period for driving the transistor 34 to the ON state becomes longer.
Output voltage drops.

With the above configuration, when the electric load 21 of the generator 4 exceeds the rating of the engine generator 1 and the rotational speed of the engine 2 does not increase even when the fuel supply to the engine 2 is maximized. An output voltage adjusting circuit on the generator 4 side based on the output of the engine overload control means 20 in the rotational speed control device 3.
A signal indicating that the overload condition is present is transmitted to 23, and the output voltage adjusting circuit 23 sets the generated output voltage to a value lower than the rated output voltage, so that the power supplied from the generator 4 to the electric load 21 is reduced. .

Therefore, the overload state of the engine 2 is eliminated, the feedback control system of the rotation speed control device 3 returns to the normal operation state, and the engine 2 rotates at the target rotation speed.
The power generation frequency of the generator 4 is kept constant.

In this embodiment, the throttle control device is used as the fuel supply amount adjusting mechanism. However, the present invention can of course be applied to a fuel injection device having a structure in which the upper limit of operation of the actuator is mechanically restricted. That is.

(Effect of the Invention) As described above, the engine speed control apparatus according to the present invention provides a fuel supply amount adjusting mechanism, a fuel supply apparatus having an electromagnetic actuator for driving the fuel supply amount adjusting mechanism, and a fuel supply amount adjusting mechanism. Energization state detection means for detecting a fuel supply amount of the device as a signal corresponding to the energization current of the electromagnetic actuator, engine rotation number detection means for outputting an engine speed as a signal corresponding to the rotation number, and energization state detection Maximum fuel supply state detecting means for determining whether the fuel supply amount detected by the means is substantially the maximum supply amount,
Rotation speed determination means for determining whether the engine rotation speed detected by the rotation speed detection means is increasing at a rate of change equal to or greater than a predetermined value. If the engine speed is not determined to be increasing at a change rate equal to or higher than the predetermined value by the engine speed determination unit, the overload control unit sends an overload state signal to the work implement. Output of the work machine to reduce the load on the work implement itself, it is possible to maintain and control the engine at approximately the maximum output state, so even if the engine is temporarily overloaded, the engine speed can be reduced. Therefore, the operation can be continued by maximizing the output power of the engine.

In addition, when applied to an engine generator, by apparently lowering the output set voltage of the automatic voltage regulator based on the overload detection signal, the electrical load of the generator becomes heavy,
In other words, when an overload condition occurs in the engine, the amount of power supplied to the electrical load is limited, so a load that temporarily flows a large current, such as a mercury lamp or electric motor, is connected as the generator load. In this case, it is possible to quickly return to the steady operation by using the output of the engine to the maximum by suppressing the decrease in the engine speed and use the synchronous generator because the engine speed does not fluctuate. The power generation frequency can be kept stable.

[Brief description of the drawings]

1 is an overall system configuration diagram of an engine generator having an engine speed control device according to the present invention, FIG. 2 is a circuit configuration diagram of the generator, and FIG. 3 is an output detection winding in an output voltage adjustment circuit. FIG. 4 is a block diagram of a conventional fuel injection amount control system. In the drawings, 1 is an engine generator, 2 is an engine, 3
Is a rotation speed control device, 4 is a generator, 5 is a target rotation setting circuit, 6 is a superposition circuit, 7 is a proportional / integral / differential circuit (PID circuit), 8 is a PWM conversion circuit, 9 is a throttle control device, 9a
Is a solenoid actuator, 10 is a rotation speed detection circuit,
11 is a frequency-voltage conversion circuit, 12 is an actuator position sensor, 18 is an energization state detection unit, 19 is a rotation speed determination unit, 20
Is the engine overload control means, 21 is the electrical load of the generator,
22 is a winding part, 22a is a rotor, 22b is a field winding, 22c is an output winding, 22d is a voltage detection winding, 22e is an excitation winding, 23 is an output voltage adjustment circuit, and 36 is a photocoupler. is there.

Claims (2)

(57) [Claims] An engine speed control device for an engine-driven work machine that drives a work machine with an engine, comprising: a fuel supply amount adjustment mechanism; and an electromagnetic actuator that drives the fuel supply amount adjustment mechanism. Energization state detection means for detecting a fuel supply amount of the fuel supply device as a signal corresponding to an energization current of the electromagnetic actuator; and engine speed detection means for outputting an engine speed as a signal corresponding to the engine speed. Maximum fuel supply state detection means for determining whether the fuel supply amount detected by the energization state detection means is substantially the maximum supply amount, and an engine speed detected by the rotation speed detection means being a predetermined value. Rotation speed determining means for determining whether or not the fuel supply rate is increasing at the above-mentioned rate of change. If the engine speed is not determined to be increasing at a rate of change equal to or greater than a predetermined value by the engine speed determining means, though the engine speed is determined to be large, the overload control means sends the engine to the work machine. An engine speed control device, wherein a load state signal is output to reduce the load on the work implement itself, thereby maintaining and controlling the engine at a substantially maximum output state. 2. The work machine comprises a generator,
The load on the engine is reduced by reducing the output voltage of the generator when an overload state signal is input to the generator.
An engine speed control device according to any one of the preceding claims.