JP2690582B2 - Engine fuel injection control device - Google Patents

Description

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

(Prior Art) The voltage (deviation) with respect to the difference between the actual engine speed and the target engine speed is subjected to proportional / integral / derivative (PID) calculation, and the fuel injection amount is adjusted based on the calculated output, Techniques for controlling the engine speed are known.

 FIG. 8 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.

(Problem to be Solved by the Invention) In a device that performs this type of feedback control, the fuel injection mechanism (actuator) is driven to further increase the fuel injection amount as the load of the engine increases. It is not possible to cope with engine overload that exceeds the limit. In such an overload operation state, the engine speed decreases. This decrease in the rotational speed is accompanied by a decrease in the engine output, which may result in a further decrease in the driving force of the load and sometimes cause a stall.

Therefore, in the present invention, in order to prevent a significant decrease in the engine speed and a accompanying decrease in the engine output when the engine is overloaded, the fuel injection amount adjusting actuator may be located at a substantially maximum injection position. Only when it is detected that the engine speed is rising even though it is detected, it is judged that the load exceeds the allowable amount and it is judged that the engine is overloaded and the overload is detected. In addition to outputting a signal, this overload detection signal is processed to temporarily increase the injection amount above the upper limit injection amount to increase the engine output within a certain time range, thereby improving work efficiency in work with large load factor changes. It is intended to provide a fuel injection control device for an engine that can improve the fuel consumption.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a rotation speed detector that detects the rotation speed of an engine, and a fuel injection amount adjustment actuator that is driven according to the output signal to drive fuel injection. In a fuel injection control device for an engine that controls a quantity, a position detector that detects an operating position of the actuator, and the position detector detect that the actuator is at a substantially maximum injection position, An overload detection circuit is provided that outputs an overload detection signal by determining that the load has exceeded the allowable amount only when it is not detected that the rotation speed detected by the rotation speed detector is increasing. When is output, the output signal of the position detector is temporarily level-shifted to generate an injection amount insufficient signal and the actuator is driven to the increasing side. By doing so, the actuator is temporarily driven beyond a preset maximum injection position to increase the injection amount.

(Operation) When the overload detection signal is output, the output signal of the position detector is temporarily set to a signal indicating the injection amount is insufficient to drive the actuator toward the increasing side, so that the actuator temporarily sets the maximum injection amount. The engine output can be increased by driving beyond the position to increase the injection amount.

(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 a fuel injection control device according to the present invention.

The fuel injection control device 1 outputs a voltage signal e _s corresponding to the target rotation speed set by the target rotation speed setting device 2 via the superposition circuit 3 to a proportional / integral / derivative calculation circuit (hereinafter referred to as a PID circuit) 4
Is applied to one input terminal of the engine 5 and a voltage signal e _n corresponding to the actual engine speed of the engine 5 is applied to the other input terminal, and is proportional / integrated / differentiated to the difference voltage between the voltage signals e _s and e _n. Generates the calculated output voltage e _o , PWM (pulse width modulation)
The solenoid type actuator 7a of the fuel injection device 7 is driven through the conversion circuit 6 to increase or decrease the fuel injection amount to control the rotation speed of the engine 5, and further, the voltage signal e corresponding to the actual rotation speed of the engine. comprises an overload detection circuit 9 for detecting the overload state from the voltage signal e _a corresponding to the position of the output e _r actuator 7a of the upper limit position setter 8 _n and an actuator 7a, the position detected by the detection output e _m The signal shift circuit 10 is operated to temporarily shift the level of the voltage signal e _a to control the fuel injection amount during overload.

The rotation speed detector 12 outputs a pulse signal P _n having a cycle proportional to the rotation speed of the engine 5, and the pulse signal p _n has a frequency
The voltage conversion circuit (F / V conversion circuit) 13 converts the analog signal e _n corresponding to the cycle of the pulse signal p _n .

The position of the solenoid type actuator 7a is detected by the actuator position detector 14, and the position detection output is converted into _a DC signal e _a by the detection / rectification circuit 15. The DC signal e _a is amplified by the amplification circuit 16, and its output is input to the superposition circuit 3.

FIG. 2 is a structural diagram showing a configuration example of a solenoid type actuator and an actuator position detector.

FIG. 2 shows an example of driving the control rack 7b of the fuel injection device 7 for a diesel engine. One end of the solenoid type actuator 7a fixed to the side of the fuel injection device 7 is connected to the control rack 7b. Further, a position detector 14 using a differential transformer is provided on the side of the solenoid type actuator 7a.

The solenoid type actuator 7a moves the actuator 7d in the axial direction by an electromagnetic force according to the amount of electricity supplied to the solenoid 7c. The position detector 14 is a linear displacement detector in which the movable core 14e is inserted in the primary coil 14b and the secondary coils 14c and 14d. This detector 14 has a primary coil 14
By exciting b with low-frequency AC, actuator 7
The position of the actuator is detected by utilizing the fact that the voltage and the polarity generated in the secondary coils 14c and 14d connected in reverse polarity change depending on the position of the movable core 14e connected to d.

 Returning to FIG. 1, the description will be continued.

The detection / rectification circuit 15 is configured to increase the position detection output voltage e _a when the actuator position detector 14 is positioned on the fuel injection amount increasing side based on the output of the position detector 14. The output e _a of the detection / rectification circuit 15 is DC-amplified by the amplification circuit 16, and its output is input to the superposition circuit 3.

In the superposition circuit 3, as shown in FIG. 3, the output that has been DC-amplified by the amplification circuit 16 is differentiated into a voltage corresponding to the actuator position change through a differentiation circuit composed of a capacitor 3a and a resistor 3c, and the inverted input of the operational amplifier 3d. Input to terminal 3b. The output voltage e _s of the target rotation speed setting circuit 2 is applied to the non-inverting input terminal 3e of the operational amplifier 3d. Inverting input terminal
When the differential input voltage is not applied to 3b, the superposition circuit 3
The output voltage equal to the voltage of e _s, if the actuator position is moved to the fuel increase side differentiating circuit 3a, the input from 3c, the output voltage of the superimposing circuit 3 becomes a voltage lower than the voltage e _s, fuel It is configured to be a voltage higher than the voltage e _s has been moved to the reduction side.

FIG. 4 is a circuit diagram showing the actuator upper limit position setter 8 and the overload detection circuit 9. The overload detection circuit 9 outputs the output e _a of the detection / rectification circuit 15 from the input terminal 9a through a time constant circuit composed of a resistor 9b and a capacitor 9c to the + of the voltage comparator 9d.
Applied to input terminal 9e. -Input terminal of voltage comparator 9d
A set voltage is applied to 9f from the actuator upper limit position setter 8. This set voltage is set to be a voltage slightly lower than the output voltage of the detection / rectification circuit 13 when the actuator 7a is at the substantially maximum fuel injection position, and the maximum fuel injection state is the resistance 9b and the capacitor. If the time constant determined by 9c or more continues, the output 9h of the voltage comparator 9d becomes H
It is configured to be a level.

The maximum fuel injection state may be detected by detecting that the solenoid type actuator 7a has moved to a predetermined position with a limit switch or the like.

The output voltage e _n of F / V converter circuit 13 is applied to an input terminal 9i of the overload detection circuit 9, the voltage comparator via a resistor 9j
Input to 9k-input terminal 9l. A resistor 9n is connected between the − input terminal 9l and the + input terminal 9m of the voltage comparator 9k. Furthermore, the + input terminal 9m is connected to the + power supply + V via the resistor 9o.
Is also connected to GND via the capacitor 9p. Therefore, when the output voltage e _n of F / V converter circuit 13 is increased with a predetermined time constant, - higher than the voltage of the voltage + input terminal 9m of the input terminals 9l, output 9r of the voltage comparator 9k is is a L level, when the output voltage e _n is not on the rise, for example, in the case of either or phenomenon holds the predetermined time the same value, + voltage input terminal 9m is - becomes higher than the voltage of the input terminal 9l, voltage The output 9r of the comparator 9k becomes H level.

The output 9h of the voltage comparator 9d that detects the maximum fuel injection state and the output 9r of the voltage comparator 9k that determines the rotational speed are input to the AND circuit 9s.

Therefore, the AND circuit 9s which is the output of the overload detection circuit 9
The output e _m of the actuator 7a is despite the approximately maximum injection position, the H level only when not being raised at a certain level or higher speed with the rotational speed of the engine 5.

FIG. 5 is a circuit diagram showing the position detection signal shift circuit 10. The position detection signal shift circuit 10 includes a timer circuit 20 and a differential amplifier 21. Timer circuit 20 through a resistor 20a to output e _m of overload detection circuit 9 from the input terminal 10a
Configured to apply to the base of NPN transistor 20b,
Resistor 20c between + power supply + V and collector of transistor 20b,
The capacitor 20d is connected in series. Also the differential amplifier 21
Is configured so that the output ed of the timer circuit 20 is applied to the non-inverting input terminal 21b of the operational amplifier 21a, the resistor 21e is connected between the inverting input terminal 21c and the output terminal 21d of the operational amplifier 21a, and the inverting terminal 21c and A resistor 21f is connected between + power supply and V. Also, the output terminal 10b and the output terminal 21d of the operational amplifier 21a are
A diode 21g for backflow prevention and a resistor 21h for current limiting are connected in between. 20e is a diode for discharging the capacitor 20d, and 20f is a resistor for discharging.

FIG. 6 is a circuit diagram when the upper limit regulating circuit 11 is composed of a PID circuit. The upper limit regulating circuit 11 includes an operational amplifier 11a and an output terminal 11b of the operational amplifier 11a as shown in FIG.
And an inverting input terminal 11c, an integrating circuit 25, an input resistor 26 having one end connected to the inverting input terminal 11c, and a differentiating circuit 27 connected in parallel with the input resistor 26.
The integrating circuit 25 is composed of three elements including a capacitor 25a and a series circuit of a capacitor 25b and a resistor 25c connected in parallel to the capacitor 25a. Differentiating circuit 27 is a capacitor 27
It consists of a and resistor 27b. In addition, 11e is a non-inverting input terminal, and 30 is a diode for a switch.

System according to the present invention as explained above, when an overload condition is detected by the overload detection circuit 9, as shown in FIG. 7, the output e _m is changed from the L level to the H level. Then, the transistor 20b of the position detection signal shift circuit 10 is turned on, and the input voltage e _d of the non-inverting input terminal 21b of the operational amplifier 21a becomes lower than the input voltage e _f of the inverting input terminal 21c (e _d <e _f ).

Therefore, the output e _g of the operational amplifier 21a becomes L level, so that a part of the output current of the amplifier circuit 16 flows in via the resistor 21h and the diode 21g, and the output voltage e _a of the detection rectifier circuit 15 is reached. The resulting signal output will temporarily drop.

Further, due to the ON state of the transistor 20b, the capacitor 20d is charged with the electric charge from the + power source + V via the resistor 20c, and the output e _d of the timer circuit 20 rises to the + power source + V voltage with a primary delay. Then, compared with the input voltage e _f of the inverting input terminal 21c of the operational amplifier 21a, if e _d ≤e _f , the output e _g of the differential amplifier 21 has the same potential as the ground, and if e _d > e _f , e It rises toward the voltage of the amplified + supply + V by a predetermined gain based on the difference voltage _d -e _f. Therefore, as described above, the output voltage e _a of the detection rectifier circuit 15 decreases until e _f is reached, and the actuator 7a is driven to the increasing side as an apparent injection amount insufficient signal. Further, during this period, the signal input to the input terminal 11d of the upper limit regulating circuit 11 is lowered, so the PID circuit 4 regulated by the upper limit regulating circuit 11
The output upper limit of the
To allow a temporary increase in the output of the PID circuit 4 for driving the PID circuit to the increase side. By shifting the position detection signal in this way, the injection amount rises from the normal maximum injection amount at the time of overload detection to maintain the newly set injection amount as shown in FIG. The injection amount can be increased during the time t _o by controlling the maximum injection amount of.

In the present embodiment, the injection quantity of the position detection output e _a of the actuator 7a to increase the overload factory injection amount temporarily shifted to increase, the actuator limit locator instead 8 It is also possible to temporarily set the set output e _{r of the above} to the injection amount increasing side.

(Effects of the Invention) As described above, according to the present invention, the load variation zone is widened by temporarily increasing the injection amount and increasing the engine output for a certain period of time within the range allowed by the engine strength during overload. Therefore, the average load factor during work can be set high, and the work efficiency in work in which the load factor changes greatly can be improved.

[Brief description of the drawings]

FIG. 1 is an overall system configuration diagram of a fuel injection control device according to the present invention, FIG. 2 is a structural diagram showing a configuration example of a solenoid actuator and an actuator position detector, and FIG.
FIG. 4 is a circuit diagram showing a superposition circuit, FIG. 4 is a circuit diagram showing an actuator upper limit position setter and an overload detection circuit, FIG. 5 is a circuit diagram showing a position detection signal shift circuit, and FIG. 6 is an upper limit regulation circuit. The circuit diagram shown in FIG. 7, FIG. 7 is a timing chart, and FIG. 8 is a block diagram of a conventional fuel injection amount control system. DESCRIPTION OF SYMBOLS 1 ... Fuel injection control device, 2 ... Target rotation speed setting device, 3 ... Superimposition circuit, 5 ... Engine, 7 ... Fuel injection device, 8 ... Actuator upper limit position setting device, 9 ... Overload detection circuit, 10 ... Position detection signal Shift circuit, 12 ... Rotation speed detector, 14 ... Actuator position detector, 20 ... Timer circuit, 21 ... Differential amplifier.

Claims (1)

(57) [Claims] 1. A rotation speed detector for detecting a rotation speed of an engine, and a fuel injection control device for an engine for controlling a fuel injection quantity by driving a fuel injection quantity adjusting actuator according to the output signal. And a position detector that detects the operating position of the actuator, and the number of revolutions detected by the number of revolutions detector is increasing while the position detector detects that the actuator is at the substantially maximum injection position. An overload detection circuit that outputs an overload detection signal by determining that the load has exceeded the allowable amount only when it is not detected is provided, and when the overload detection signal is output, the output signal of the position detector Is temporarily level-shifted to generate an injection amount shortage signal and drive the actuator toward the increasing side, so that the actuator temporarily A fuel injection control device for an engine, characterized in that the fuel injection control device is configured to drive beyond a maximum injection position set for the purpose of increasing the injection amount.