JPS58178831A - Fuel injection control device - Google Patents

Abstract

PURPOSE:To prevent decrease in a fuel injection quantity when a battery voltage drops, by arranging such that there may take place a reduction of resistance value in a resistor connected with a solenoid valve for controlling an electric current in response to a voltage drop, in a fuel injection control device for a gas turbine engine. CONSTITUTION:While a start signal S7 is retained ON, a transistor 8 is turned ON and a relay 9 is energized, thereby causing a contactor of the relay 9 to switch ON for starting an operation. Upon the contactor of the relay 9 being switched ON, the relay 10 is also energized for turning ON all of its four contacts. Thus, a resistor R2 is short-circuited and solenoid valves 6 and 7 are brought into contact with a battery VB solely via a resistor R3. In this manner, solenoid valves 6 and 7 are energized with an ample voltage even when a battery voltage drops at the start-up operation, thereby allowing these valves to receive an ample driving current in response to signals S5 and S6 indicative a fuel injection timing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection control device for an internal combustion engine, particularly a gas turbine engine, and more specifically, to a technique for preventing a reduction in fuel injection amount due to a drop in battery voltage during startup or the like.

As a conventional fuel injection control device for a gas turbine engine, there is one shown in FIG. 1, for example.

In FIG. 1, for example, there is one actuation device composed of a microco/peater, a rotation speed signal S1 of a combination generator turbine, a rotation speed signal S2 of a power turbine, a start command signal S3, a stop command signal 84, etc., for various operations. A signal indicating the state is input manually, a fuel injection amount corresponding to the operating state is calculated, and fuel injection signals S5 and S6 are output.

The fuel injection signals S5 and 860 are PWM (pulse width modulation) signals, and have a period τ as shown in FIG. is constant, and the pulse widths (data) τ1, τ2, τ3 have values corresponding to the fuel injection amount.

The above fuel injection signals S5, S6 are applied to the transistor 4.5 via the driver circuit 2, respectively.

A solenoid that controls the fuel flow rate of the main injector.
- The solenoid valves 6 (there are 6) and the solenoid valves 7 that control the fuel flow rate of the sub-injectors are each connected to the battery 3 via a current limiting resistor t1.

While the fuel injection signal S5 is °°1'', the transistor 4 is turned on and the solenoid valve 6 is opened, and while the fuel injection signal S6 is °°1'', the transistor 5 is turned on and the solenoid valve 6 is opened. Valve 7 is now open.

Therefore, by controlling the solenoid valve 6.7 by setting the pulse width of the fuel injection signals S5 and S6 to a value corresponding to the fuel injection amount, the desired amount of fuel corresponding to the operating state can be injected from the main and sub-injectors. You can do it.

The sub-injector constantly injects a certain amount of fuel necessary for the gas turbine engine to continue steady operation.
, and the main intake 7 is used to vary the amount of fuel injection depending on the operating conditions.

A series circuit of a resistor and a capacitor connected in parallel with the switching transistor 4.5 is an energy absorption circuit when current is interrupted.

As can be seen from Figure 2, the solenoid pulp current is
After the fuel injection signal rises, it rises with some time delay. Therefore, the solenoid valve actually opens with some delay from the rise of the fuel injection signal.

In conventional devices such as those mentioned above, when the battery voltage decreases due to a large current flowing through the starter motor, ignition device, or other starting device during startup, the delay in opening the solenoid valve increases, or the solenoid valve does not open properly. There is a problem in that the amount of fuel injected decreases or fuel is no longer injected.

Below, the problems listed in -]2 will be explained.

FIG. 6 is a characteristic diagram of the rotational speed Ngg of the comfort turbine, the rotational speed NPT of the power turbine, and the battery voltage.

6. As can be seen from Figure 5, starting starts at time O,
When the starter motor and ignition system operate, the battery voltage, which is normally 25V, drops to about 17 to 18V.

Next, FIG. 4 is a diagram showing the relationship between the fuel flow rate of the solenoid valve and the drive pulse coefficient using the battery voltage as a parameter. Note that the frequency of the drive pulse is 5 Q Ilz.

As can be seen from Figure 4, when the voltage becomes 20V, the fuel flow rate decreases a little, and when the voltage increases to 16V, not only does the fuel flow rate decrease significantly, but the fuel flow rate and the duty are no longer proportional. , making accurate control impossible.

Therefore, as mentioned above, the battery voltage is 17 when starting.
If the voltage drops by about 18V, the actual fuel injection amount will be significantly lower than the control target value, which may make starting difficult.

Note that the problem described in -1- occurs not only at the time of starting, but also when the battery voltage becomes low F due to overdischarge or the like.

4. The present invention has been made to solve the above problems, and provides a fuel injection control device for a gas turbine engine that can accurately control the fuel injection amount even when the battery voltage drops during startup etc. The purpose is to

In order to achieve the above object, the present invention provides a means for short-circuiting part or all of the current limiting resistor connected in series with the solenoid valve when the battery voltage drops such as when the starter motor is activated. The structure is such that the voltage applied to the solenoid valve does not drop even during startup.

The present invention will be described in detail below based on the drawings.

FIG. 5 is a diagram showing one embodiment of the present invention, and shows a circuit for short-circuiting a current limiting resistor at the time of starting.

In FIG. 5, 8 is a transistor, 9 is a relay with normally open contacts, 10 is a relay with four normally open contacts, and the same reference numerals as in FIG. 1 indicate the same components.
is a signal that becomes °°1'' only while a starter switch (not shown) is turned on at the time of starting.

Next, the effect will be explained.

While the start signal S7 is at P1'' at the time of starting, the transistor 8 is turned on, the relay 9 is energized, and its contact is turned on.

Therefore, a starting device (starter motor and ignition device) (not shown) is connected to the batch +) Vs to start the engine.

Furthermore, when the contacts of the relay 9 are turned on, the relay 10 is also excited, and all of its four contacts are turned on.

Therefore, the resistor R12 is all short-circuited, and the solenoid valves 6 and 7 are connected to the battery 8 via the resistor R.

As mentioned above, the value of the resistor I is, for example, the resistor R in FIG.
Since the value is set to 7 of 1, even if the battery voltage drops at startup, sufficient voltage will be applied to the solenoid valves 6 and 7, and the fuel injection amount will be 7.

Sufficient drive current should flow according to numbers S5 and S6. Therefore, there is no possibility that the delay in the opening timing of the solenoid valve will become large.

In FIG. 5, the series circuit of a resistor and a capacitor connected in parallel to L/-9 and its contact is an energy absorption circuit when current is cut off.

Figure 6 is a characteristic comparison diagram of the circuits in Figures 1 and 5. In the waveform of the solenoid valve current (drive current), the broken line is the characteristic of the circuit in Figure 1, and the solid line is the characteristic of the circuit in Figure 5. shows.

As you can see from Figure 6, the battery voltage is 25V at startup.
When the voltage drops from 18V to 18V, in the circuit shown in FIG. 1, the rise of the solenoid valve current is delayed and the maximum value of the current also decreases. As a result, the opening time of the solenoid valve becomes shorter and the fuel flow rate decreases significantly.

On the other hand, in the circuit shown in FIG. 5, the delay in rising and the maximum value are the same as in normal times, so accurate fuel control can be performed.

Next, FIG. 7 shows another embodiment of the present invention, in which the value of the current limiting resistor is changed according to the value of the battery voltage.

In FIG. 7, a battery voltage signal S8 is a signal corresponding to the battery voltage.

The arithmetic device 11 has the following functions in addition to the same functions as the arithmetic device 1 shown in FIG.

That is, the arithmetic device 11 inputs the battery voltage signal S8 and outputs "1" or "0" depending on the value of the battery voltage.
The six types of control signals SS and S with the value of
1011 Output.

The values of the above control signals S, ~S, 1 are, for example, as shown in FIG.
'', the control signal S11 becomes ``1'' when the voltage is 14V or less.

Next, the transistors 12 to 14 are turned on when the control signals S and S11 applied to each become "1",
Energize relays 15-17.

Relays 15 to 17 each have 4 normally open contacts.
- When the relay 15 is energized, the resistor ■t4 is short-circuited, when the relay 16 is energized, the resistor R5 is short-circuited, and when the relay 17 is energized, the resistor ■(.6) is short-circuited.

The value of the resistor connected in series to the solenoid valves 6 and 7 changes in four stages depending on the battery voltage, as shown in FIG. 8, and becomes smaller as the battery voltage decreases.

As mentioned above, the circuit shown in Fig. 7 is configured to change the value of the current limiting resistor according to the battery voltage, so the battery voltage In the embodiment shown in FIG. 7, which can prevent a decrease in the fuel injection amount due to the decrease,
Although the case where the resistance value is switched in four stages has been exemplified, it is easily possible to switch the resistance value in more stages.

However, the present invention is not limited to gas turbine engines, but can also be applied to fuel injection systems for other types of engines.

As explained above, according to the present invention, when the battery voltage is low, the current limiting resistance of the solenoid valve is reduced, so that even when the battery voltage is low, the solenoid valve This eliminates the possibility that the valve opening timing is delayed or that the solenoid valve does not open, and the fuel injection amount can always be accurately controlled.

Note that the embodiment shown in FIG. 5 allows the above-mentioned resistance value switching to be performed only at the time of starting without detecting the battery voltage using a simple circuit, and the embodiment d-1 shown in FIG. This allows precise control to be performed in accordance with the battery voltage at all times.

[Brief explanation of drawings]

Fig. 1 is an example of a conventional device, Fig. 2 is a signal waveform diagram of the circuit shown in Fig. 1, Fig. 4 is a battery voltage characteristic diagram at startup, and Fig. 4 is a graph of fuel flow rate with battery voltage as a parameter. Figure 5 is a diagram showing an embodiment of the present invention.
6 is a signal waveform diagram of the circuit of FIG. 5, FIG. 7 is another embodiment of the present invention, and FIG. 8 is a diagram showing the relationship between battery voltage and resistance value. Explanation of symbols 1-Arithmetic unit 2.3...Triver circuit 4.
5. Transistor 6... Solenoid 7 for main injector. Solenoid 8 for sub-injector. Transistor 9.10... Relay 11. Arithmetic device 12-14. Transistor 15-17. Relay agent Junnosuke Nakatoshi. Sunny n

Claims (2)

[Claims] (1) In a fuel injection control device that controls the fuel flow rate to an injector by controlling the opening and closing of a solenoid valve, the value of the current limiting resistor connected between the solenoid valve and the power supply is determined by the power supply voltage. A fuel injection control device characterized by comprising a means for reducing the amount of fuel when the fuel decreases. (2) The fuel injection control device according to claim 1, wherein the means is configured to short-circuit part or all of the resistor while the starter is operating. . (b) The fuel injection control device according to claim 1, wherein the means is configured to switch the value of the resistor in accordance with the power supply voltage.