JPH03225052A - Fuel injection control device for engine - Google Patents

Abstract

PURPOSE:To prevent the reduction of the rotating speed and output of an engine in a overload operation state by temporarily driving an actuator beyond the maximum injection position to increase the injection quantity when an overload detected signal is outputted. CONSTITUTION:A fuel injection control device 1 is inputted with a voltage signal (es) corresponding to the target rotating speed set by a target rotating speed setter 2 and a voltage signal (en) corresponding to the actual rotating speed of an engine 5 and generates the output voltage (eo) and drives the actuator 7a of a fuel injection device 7 via a pulse width modulating/converting circuit 6 to increase or decrease the fuel injection quantity and controls the rotating speed of the engine 5. An overload detecting circuit 9 detecting the overload state from the voltage signal (en) corresponding to the actual rotating speed of the engine 5 and the output (er) of an upper limit position setter 8 and the voltage signal (ea) corresponding to the position of the actuator 7a is provided, a position detection signal shift circuit 10 is operated by the detected output (em) to temporarily level-shift the voltage signal (ea), thereby the fuel injection quantity under an overload is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection control device when an engine is in an overload operating state.

(Prior art) Proportional-integral-derivative (PID) calculation is performed on the voltage (deviation) for the difference between the actual rotational speed of the engine and the target rotational speed, and the fuel injection amount is adjusted based on the calculated output. Techniques for controlling 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 detecting the rotation of the gear 102 provided on the output shaft 101 using a non-contact engine rotation sensor 103, and generating a pulse signal Pn with a period corresponding to the rotation speed. A corresponding analog voltage e at a frequency-voltage converter (f-V converter) 104. Convert to This voltage e. The deviation Δe between and the voltage e corresponding to the target rotation speed given by the target rotation speed setting means 105 is P.
The ID calculation circuit 106 is manually operated, and the proportional amplifier circuit 107, the integral circuit 108, and the differential circuit 109 perform proportional, integral, and
After each differential calculation is performed, it is applied to the fuel injection device 110 to adjust the fuel injection amount and 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 engine load increases, but the maximum injection position It is not possible to handle engine overloads exceeding . In such an overload operating state, the engine speed will drop. This decrease in rotational speed is accompanied by a decrease in engine output, which may further reduce the driving force of the load or sometimes cause a stall.

Therefore, the present invention provides that the actuator for adjusting the fuel injection amount is located at approximately the maximum injection position in order to prevent a significant decrease in engine speed and an accompanying decrease in engine output in an overload operating state of the engine. If it is not detected that the engine speed is increasing even though it is detected, it is determined that the engine is in an overload operating state and an overload detection signal is output,
Engine fuel that processes this overload detection signal and temporarily increases the injection amount beyond the upper limit injection amount to increase engine output over a certain period of time, improving work efficiency in work with large load factor changes. The present invention aims to provide an injection control device.

(Means for Solving the Problems) In order to solve the above problems, the present invention includes a rotation speed detector that detects the rotation speed of an engine, and a fuel injection amount adjustment actuator that drives a fuel injection amount adjustment actuator according to this output signal to perform fuel injection. A fuel injection control device for an engine that controls the amount of fuel injection includes a position detector that detects the operating position of the actuator, and a position detector that detects that the actuator is at approximately the maximum injection position. An overload detection circuit is provided that outputs an overload detection signal when the rotation speed detected by the rotation speed detector is not detected to be increasing.
When the overload detection signal is output, the actuator is temporarily driven beyond a preset maximum injection position to increase the injection amount.

Furthermore, the increase in the injection amount due to the actuator being temporarily driven beyond the maximum injection position is achieved by shifting the position detection signal, which is configured by a timer circuit that operates based on the overload detection signal, to the output signal of the position detector. More preferably, by superimposing the output signal of the circuit, the output signal of the position detector is temporarily made into a signal indicating an insufficient injection amount, thereby driving the actuator toward the increase side.

(Function) When an overload detection signal is output from the overload detection circuit, the actuator is temporarily driven beyond a preset maximum injection position to increase the injection amount and increase the engine output.

Further, in driving such an actuator, preferably, the overload detection signal is superimposed on the position detection signal via a position detection signal shift circuit, so that the position detection signal apparently detects an insufficient injection amount. Especially,
In order to make up for this shortage, it is driven to the increasing side.

(Example) Embodiments of the present invention will be described below 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 sends a voltage signal e5 corresponding to the target rotation speed set by the target rotation speed setting device 2 to a proportional/integral/differential calculation circuit (hereinafter referred to as a PID circuit) via a superimposition circuit 3.
At the same time, a voltage signal en corresponding to the actual rotation speed of the engine 5 is applied to one input terminal of the engine 5, and a voltage signal en corresponding to the actual rotation speed of the engine 5 is applied to the other input terminal.
Generate the output voltage e0 subjected to differential operation, and perform PWM (
[Pulse Width Modulation] The solenoid actuator 7a of the fuel injection device 7 is driven via the conversion circuit 6 to increase or decrease the fuel injection amount and control the rotation speed of the engine 5,
Furthermore, an overload detection circuit 9 is provided for detecting an overload condition from a voltage signal en corresponding to the actual engine speed, an output er of an upper limit position setting device 8 of the actuator 7a, and a voltage signal e1 corresponding to the position of the actuator 7a. , the detection output e is used to operate the position detection signal shift circuit 10 to temporarily shift the level of the voltage signal e1, thereby controlling the fuel injection amount during overload.

The rotation speed detector 12 generates a pulse signal P with a period proportional to the rotation speed of the engine 5. This pulse signal Pn is converted into an analog voltage e corresponding to the period of the pulse signal Pn by a frequency/voltage conversion circuit (F/V conversion circuit) 13. is converted to

The position of the solenoid actuator 7a is detected by an actuator position detector 14, and the position detection output is converted into a DC signal e by a detection/rectification circuit 15.

is converted to The DC signal e is amplified by the amplifier circuit 16, and its output is input to the superimposing circuit 3.

FIG. 2 is a structural diagram showing an example of the configuration of a solenoid 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, in which 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. Furthermore, a position detector 14 using a differential transformer is provided on the side of the solenoid actuator 7a.

The solenoid actuator 7a uses electromagnetic force to move the actuator 7d in the axial direction according to the amount of current applied to the solenoid 7c. The position detector 14 is a linear displacement detector in which a movable core 14e is inserted into a primary coil 14b and secondary coils 14c and 14d. This detector 14 is activated by exciting the primary coil 14b with low frequency alternating current to activate the movable core 14 connected to the actuator 7d.
Depending on the position of e, the secondary coil 14c is connected with reverse polarity,
The position of the actuator is detected by utilizing changes in the voltage and polarity generated at 14d.

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

The detection/rectification circuit 15 is configured to increase the position detection output voltage e1 when the actuator position detector 14 is located on the fuel injection amount side based on the output of the position detector 14. The output e of the detection/rectification circuit 15 is the amplifier circuit 1
6 amplifies the direct current, and its output is manually input to the superimposing circuit 3.

In the superimposing circuit 3, as shown in FIG. 3, the output DC amplified by the amplifier circuit 16 is differentiated into a voltage corresponding to a change in the actuator position through a differentiating circuit consisting of a capacitor 3a and a resistor 3c, and is inverted by an operational amplifier 3d. It is manually input to the input terminal 3b. The output voltage e1 of the target rotation speed setting circuit 2 is applied to the non-inverting input terminal 3e of the operational amplifier 3d. When the differential input terminal is not applied to the inversion input terminal 3b, the output voltage of the superimposition circuit 3 is the same as the voltage of el, and when the actuator position moves to the fuel increasing side, the superposition is The output voltage of the circuit 3 is configured to be lower than the voltage ei, and higher than the voltage e8 when moving to the fuel depletion side.

FIG. 4 is a circuit diagram showing the actuator upper limit position setting device 8 and the overload detection circuit 9. The overload detection circuit 9 connects the output e of the detection/rectification circuit 15 from an input terminal 9a to a resistor 9b.
, is applied to the input terminal 9e of the voltage comparator 9d via a time constant circuit consisting of a capacitor 90. A set voltage is applied from the actuator upper limit position setter 8 to one input terminal 9f of the voltage comparator 9d. This set voltage is set to be a voltage slightly lower than the output voltage of the detection/rectifier circuit 13 when the actuator 7a is approximately at the maximum fuel injection position, and the maximum fuel injection state is at the resistor 9b.
, if it continues for more than the time constant determined by the capacitor 9c,
The output 9h of the voltage comparator 9d is configured to be at H level.

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

Further, the output voltage en of the F/V conversion circuit 13 is applied to an input terminal 91 of the overload detection circuit 9, and is inputted to one input terminal 9ρ of the voltage comparator 9 via a resistor 9j. A resistor 9n is connected between one input terminal 9°C and tenth input terminal 9m of the voltage comparator 9. Further, the ten input terminal 9m is connected to the ten power supply +V via a resistor 90, and is also connected to GND via a capacitor 9p. Therefore, F
When the output voltage en of the /V conversion circuit 13 is rising with a predetermined time constant, the voltage at the - input terminals 9J:l is higher than the voltage at the ten input terminals 9m, and the output 9r to the voltage comparator 9 is L.
level, but if the output voltage en is not increasing, for example, if it holds the same value for a predetermined time or decreases, the voltage at the 10th input terminal 9m becomes higher than the voltage at the 1st input terminal 9JZ, and the voltage comparator The output 9r of the circuit 9 becomes H level.

Output 9h of voltage comparator 9d for detecting maximum fuel injection state
The outputs 9r from the voltage comparator 9 for determining the rotation speed are each input to an AND circuit 9S.

Therefore, the AND circuit 9S which is the output of the overload detection circuit 9
The output e, , becomes H level only when the rotational speed of the engine 5 is not increasing above a certain speed even though the actuator 7a is at approximately the highest injection position.

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. The timer circuit 20 is configured to apply the output em of the overload detection circuit 9 from the input terminal 10a to the base of the NPN transistor 20b via the resistor 20a, and is connected to the power supply +V and the transistor 20.
A resistor 20c and a capacitor 20d are connected in series between the collectors of the transistor b. The differential amplifier 21 also includes a timer circuit 20.
The output ed is connected to the non-inverting input terminal 21b of the operational amplifier 21a.
A resistor 21e is connected between the inverting input terminal 21c and the output terminal 21d of the operational amplifier 21a,
Further, a resistor 21f is connected between the inverting terminal 21c and the power supply +V. In addition, a diode 21g for backflow prevention is connected between the output terminal 10b and the output terminal 2id of the operational amplifier 21a.
and a current limiting resistor 21h. In addition, 20
e is a diode for discharging the capacitor 20d, and 2
0f is a resistance for discharging.

FIG. 6 is a circuit diagram when the upper limit regulation circuit 11 is constructed from a PID circuit. As shown in FIG. 6, the upper limit regulation circuit 11 has one end connected to an operational amplifier 11a, an integration circuit 25 provided between the output terminal jlb of the operational amplifier 11a, and an inverting input terminal tic, and an inverting input terminal 11c. It is provided with a human resistor 26 in the shape of a tongue, and a differentiating circuit 27 connected in parallel with the resistor 26. The integrating circuit 25 is composed of three elements including a capacitor 25a, a series circuit of a capacitor 25b connected in parallel to the capacitor 25a, and a resistor 25c. The differentiating circuit 27 is composed of a capacitor 27a and a resistor 27b.

Note that lie is a non-inverting input terminal, and 30 is a diode for a switch.

As described above, in the system according to the present invention, when an overload state is detected by the overload detection circuit 9 as shown in FIG. 7, the output e changes 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 non-inverting input terminal 2 of the operational amplifier 21a is turned on.
The input terminal ed of 1b is the input terminal e of the inverting input terminal 21c.
It falls below f (edkuef).

Therefore, since the output e of the operational amplifier 21a becomes L level, a part of the output current of the amplifier circuit 16 flows through the resistor 21h1 diode 21g, and a signal based on the output voltage e1 of the detection rectifier circuit 15 is generated. This will result in a temporary decrease in output.

Further, due to the ON state of the transistor 20b, the capacitor 20d is charged with electric charge from the +V power supply via the resistor 20c, and the output e of the timer circuit 20 increases toward the voltage of the +V power supply with a first-order delay. and operational amplifier 21a
compared with the input terminal ef of the inverting input terminal 21c of ed≦
If ef, the output e1 of the differential amplifier 21 will be at the same potential as the ground, and if ed>ef, it will be amplified by a predetermined gain based on the differential voltage of e, -ef and move toward the voltage of 10 power supply +■. Rise. Therefore, until reaching ef, the output voltage e of the detection rectifier circuit 15 decreases as described above, and the actuator 7a is driven to the increasing side as a signal indicating an apparent insufficient injection amount. In addition, during this period, since the signal input to the input terminal lid of the upper limit regulation circuit 11 is reduced, the output upper limit value of the PID circuit 4 regulated by the upper limit regulation circuit 11 also increases, and the above-mentioned actuator 7a
The output of the PID circuit 4 is allowed to increase temporarily in order to drive the output to the increasing side. By shifting the position detection signal in this way, the injection amount rises from the normal maximum injection amount when an overload is detected, maintains the newly set injection amount, and then slowly returns to normal after a predetermined period of time, as shown in Figure 7. The injection amount is controlled to the maximum injection amount of , and the injection amount can be increased for the time 〇.

In this embodiment, in order to increase the injection amount at the time of overload, the position detection output e of the actuator 7a is temporarily shifted so that the injection amount increases, but instead, the actuator upper limit position setting device 8 The set output er may be temporarily set to the injection amount increasing side.

(Effects of the Invention) As explained above, according to the present invention, when an overload occurs, the load fluctuation zone is expanded 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. Therefore, it is possible to set a high average load rate during work, and it is possible to improve work efficiency in work with large changes in load rate.

[Brief explanation of 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 an example of the configuration of a solenoid actuator and an actuator position detector, and Fig. 3 is a circuit diagram showing a superimposed circuit. , Fig. 4 is a circuit diagram showing the actuator upper limit position setting device and overload detection circuit, Fig. 5 is a circuit diagram showing the position detection signal shift circuit, Fig. 6 is a circuit diagram showing the upper limit regulation circuit, and Fig. 7 is a circuit diagram showing the upper limit regulation circuit. Timing chart,
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 setter, 3...Superimposed circuit, 5...Pa engine, 7...Fuel injection device, 8...Actuator upper limit position setter, 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 (2)

[Claims] (1) In an engine fuel injection control device that includes a rotational speed detector that detects the rotational speed of the engine and a fuel injection amount adjusting actuator that controls the fuel injection amount by driving a fuel injection amount adjusting actuator according to the output signal, the operation of the actuator is provided. A position detector detects the position, and the rotation speed detected by the rotation speed detector is increasing even though the position sensor detects that the actuator is at a substantially maximum injection position. An overload detection circuit is provided that outputs an overload detection signal when the overload detection signal is not detected, and when the overload detection signal is output, the actuator is temporarily driven beyond the preset maximum injection position to reduce the injection amount. 1. A fuel injection control device for an engine, characterized in that it is configured to increase the amount of fuel injection. (2) The increase in the injection amount due to the actuator being temporarily driven beyond the maximum injection position is determined by applying a position detection signal to the output signal of the position detector, which is composed of a timer circuit that operates based on the overload detection signal. 2. The fuel injection control device for an engine according to claim 1, wherein the output signal of the position detector is temporarily made into an injection amount insufficient signal by superimposing the output signal of the shift circuit to drive the actuator toward an increase side. .