JPS5938423B2 - Fuel control circuit for fuel injection pump for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel control circuit for a fuel injection pump for an internal combustion engine.

For example, in an electric fuel control system for a diesel engine,
Due to the correlation between limiting harmful exhaust gas concentration and effectively obtaining output torque, the maximum fuel injection amount characteristics (full load characteristics) for the engine can be arbitrarily adjusted non-linearly with respect to changes in engine speed. Required to be set.

To meet this requirement, devices in which the full load characteristics are electronically set using an analog function generator have been proposed, for example, in Japanese Patent Publication No. 47-38329 and Japanese Patent Application Laid-Open No. 47-35525.

On the other hand, the flammability limit in these engines depends on the air-fuel ratio, but if the air pressure taken into the engine changes, the air density changes, and the air-fuel ratio changes accordingly. In Japanese Patent No. 40226, intake air pressure is detected and correction is made for this change.

However, since the air-fuel ratio also changes depending on the intake air temperature, if this correction is not taken into account, there is a risk that a large amount of harmful exhaust gas will be generated.

An object of the present invention is to perform combustion in an internal combustion engine at a more appropriate air-fuel ratio based on the concept of correcting the maximum fuel injection amount supplied to an internal combustion engine according to the temperature of air taken into the engine. The aim is to further reduce the generation of harmful exhaust gases and black smoke.

In the present invention, there is provided a control signal calculation means for calculating a fuel adjustment member control signal corresponding to the engine rotation speed and an accelerator operation amount, and a control signal calculation means for calculating a fuel adjustment member control signal that exceeds a predetermined value corresponding to the engine rotation speed. a limiting means for applying the fuel regulating member control signal to the fuel regulating member actuator in a manner such that the fuel regulating member control signal is not affected; and a correcting means for correcting a predetermined value of the limiting means in accordance with the temperature of air taken into the engine. and the correction means corrects the change in the density of the intake air based on the change in the intake air temperature, thereby correcting the change in the air-fuel ratio of the engine. A fuel control circuit for an injection pump is provided.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows one embodiment of a fuel control circuit 10 according to the present invention.

In the fuel control circuit 10, a rotation signal from a diesel engine (not shown) is input to a terminal 12, an accelerator signal corresponding to the operation amount of the accelerator is input to a terminal 22, and a fuel adjustment signal of a fuel injection pump (not shown) is input to a terminal 14. A position signal corresponding to the position of the rod is input as a feedback signal.

Then, from the terminal 16, an actuation signal corresponding to the rotational speed and the operation amount of the accelerator is outputted to the actuator of the fuel adjustment rod.

The fuel control circuit 10 includes a speed voltage generation circuit 18 that generates a speed voltage E1 proportional to the rotation speed V based on a rotation signal S1, which is a pulse signal whose frequency increases in proportion to the engine rotation speed, and a speed voltage generation circuit 18 that generates a speed voltage E1 proportional to the rotation speed V. It has a position signal generating circuit 20 that generates a position voltage E2 having a magnitude corresponding to the position of the fuel adjustment rod based on the position signal S2.

The speed voltage generation circuit 18 is an integral amplifier circuit composed of an operational amplifier A1, resistors R1 to R8, and a capacitor C1, and is configured to control the frequency of the rotation signal S1, that is, the rotation speed V.
It is possible to generate a speed voltage E1 proportional to (see FIG. 2).

The position signal generating circuit 20 includes an operational amplifier A2 and resistors R9 to R13, and obtains a position voltage E2 from the position signal S2.

Note that terminal 1 is a power supply terminal.

These speed voltage E1 and position voltage E2 are input to a control voltage generation circuit.

The control voltage generation circuit includes a first control voltage generation circuit 24 that generates a first control voltage E3 corresponding to the fuel injection amount when the engine is idling, and a second control voltage generation circuit 24 that generates a first control voltage E3 that corresponds to the fuel injection amount when the engine is at full load. Second control voltage generation circuit 26 that generates leg voltage E4
and a third control voltage generation circuit 28 that generates a third control voltage E5 determined in accordance with the accelerator operation amount a and the rotational speed V of the engine.

The first control voltage generation circuit 24 includes an operational amplifier A3 and a resistor R.
14, R1, and the speed voltage E1 is inputted to the inverting input terminal of the operational amplifier A4 via the buffer amplification section and the input resistor R16.

A bias resistor R is connected to the non-inverting input terminal of the operational amplifier A4.
A bias voltage is applied by R18 and R19 via an input resistor R1□.

Further, a position voltage E2 is applied to the inverting input terminal via a resistor R2o, so that the operational amplifier A4
The output voltage of the operational amplifier A3, that is, the first control voltage E3 is
As the composite value of the output voltage and the position voltage E2 increases, its magnitude decreases.

However, the combined value is higher than the divided voltage value at the connection point determined by the values of resistors R18 and R1 (if this happens, the magnitude of voltage E3 will output a constant voltage approximately equal to the ground potential). It becomes like this.

That is, the first control voltage E3 changes as shown in FIG. 3a with respect to changes in the rotational speed V.

The characteristics of the first control voltage E3 with respect to the rotational speed V can be arbitrarily selected as shown by the dotted line in the figure by appropriately setting the values of the resistors R18 and R19 according to the characteristics of the engine.

Here, the symbol R2 is a feedback resistor, and the symbol R2□ is an output resistor.

The configuration of the second control voltage generation circuit 26 is similar to the first control voltage generation circuit 24 except that it does not include a buffer amplification section.

That is, the speed voltage E1 and the position voltage E2 are input to the inverting input terminal of the operational amplifier A5 via resistors R23 and R24, respectively, so that the output voltage decreases as the rotational speed V of the engine increases. It has become.

In this circuit, a bias voltage larger than the bias voltage applied to the non-inverting input terminal of the operational amplifier A4 is applied to the non-inverting input terminal of the resistor R2.

Therefore, the second control voltage E4 changes as shown in FIG. 3 with respect to changes in the rotational speed V.

Here, R28 is a feedback resistor.

The third control voltage generation circuit 28 can change the voltage applied to the inverting input terminal of the operational amplifier A6 in accordance with the accelerator signal S3 having a magnitude corresponding to the accelerator operation amount a inputted from the terminal 22. It has the same configuration as the first control voltage generation circuit 24 except for the following points.

Here, A7 is an operational amplifier for buffer amplification, and R29
thru R37 are resistors.

In this circuit, as shown in FIG. 3C, the characteristic of the rotational speed V versus the output voltage E5 can be changed in accordance with an arbitrary accelerator operation amount ai, that is, in accordance with the accelerator signal S3.

Each of the first and second control voltages E3. E4 is each diode D
1. A third control voltage E, is applied to terminal 16 via resistor R37.

The control voltage appearing at terminal 16 is therefore
0 action, whichever is greater of the first control voltage E3 and the third control voltage E5, and the diode D2
For zero action, the voltage is the smaller of the second control voltage E4 and the third control voltage E5.

That is, as shown in FIG. 3d, the upper limit of the third control voltage E5 is limited by the second control voltage E4, and the lower limit thereof is limited by the first control voltage E3.

Therefore, a control voltage is output from the terminal 16 in accordance with all operating conditions when the engine is idling, at full load, and at an intermediate load.

The fuel control circuit 10 further sets the maximum value of the fuel injection amount to a predetermined value with respect to the rotation speed when the control voltage becomes high as the load increases. A limit voltage generation circuit 30 is provided that generates a limit voltage to limit the voltage to a predetermined value according to the voltage.

The limit voltage generation circuit 30 generates a speed voltage E which is a rotational speed signal.
1, and each outputs a partial restriction voltage having a predetermined slope and a predetermined magnitude in response to a change in the speed voltage E1.

In the illustrated example, operational amplifiers A32Ag t Alo
Three partially limited voltage generation circuits 32 mainly composed of:
34.36 are provided.

In the partially limited voltage generation circuit 32, a speed voltage E1 is applied to a non-inverting input terminal of an operational amplifier A8 via a resistor R38, and a speed voltage E1 is applied to an inverting input terminal of the operational amplifier A8 via a resistor R39.
A bias voltage is applied by , R,1.

A feedback resistor R is connected between the inverting input terminal and the output terminal.
42 are connected.

The bias voltage to the inverting input terminal is the rotation speed v7b″Z
The output voltage E6 is set to be equal to the value of the speed voltage E1 at the time of V1, and therefore this output voltage E6 is as shown in FIG.
As shown in (), the partial limiting voltage decreases as the rotational speed (2) increases from zero, and becomes R6-0 when V=V.

The molding pressure generation circuit 34 is used to generate a partially limited voltage when the rotational speed is between v1 and v2.

In the partial limit voltage generation circuit 34, the speed voltage E1 is inputted to the inverting input terminal, and the output voltage E7 of the operational amplifier A9 starts to increase from the value of the speed voltage E1 when it becomes v-vl, and becomes v-v2. R7 is the value of speed voltage E1 when
The values of the resistors R43 to R4□ are set so that the output is saturated.

Therefore, the output voltage E7 becomes a partially limited voltage that changes as shown in FIG.

The partial limited voltage generation circuit 36 is the partial uniform voltage generation circuit 32.
It has the same circuit configuration as .

Then, adjust the values of resistors R48 to R52 so that V is
2 (and the maximum rotational speed of the engine is smaller than 3), the characteristics for output voltage E81 degrees V are 4th.
A partially limited voltage as shown in Figure C is generated.

Each of these output voltages E6 jE7 is a partially limited voltage.
．． R8 is input to a combining circuit 38 which combines these respective output voltages to create the required limiting voltage for changes in engine speed.

The combining circuit 38 is an adder mainly composed of an operational amplifier A1□, and each output voltage E67 R is connected to its inverting input terminal.
7 and R8 are input through variable human resistors R53, R54, and R35, and position voltage E2 is input through resistor R56.

On the other hand, a bias resistor R67 is connected to the non-inverting input terminal.
R58 is connected to an input resistor R59, and a feedback resistor R60 is connected to the output terminal.

Therefore, each output voltage E6, R72R8 is connected to the resistor R5
3 to R55 are weighted and combined, and as shown in FIG. 4d, a printing voltage E9 having a predetermined value with respect to the rotational speed V is obtained.

This limited voltage E9 is applied to the terminal 16 via the diode D3.

Since the anode of the diode D3 is connected to the terminal 16, when the control voltage is lower than the limit voltage E9, the diode D3 becomes reverse biased, and therefore the control voltage is outputted to the terminal 16 as is.

On the other hand, when the control voltage is higher than the limiting voltage E9, the diode D3 becomes forward biased and therefore the terminal 1
6, a limit voltage E9 determined by the rotational speed at that time is output.

That is, the output voltage Eout from the terminal 16 is supplied to the fuel regulating rod actuator in such a way that the control voltage does not exceed a predetermined limit voltage corresponding to the rotational speed (see FIG. 5).

As can be readily understood from the above description, the manner in which the limiting voltage changes with respect to the rotational speed can be made to have the desired characteristics required by appropriately setting the values of the resistors mentioned above.

According to this device, for example, when the accelerator operation amount a is a2 in FIG. 5, the load increases and the rotational speed V decreases, and v=v1.
When , the control voltage matches the limit voltage and E o
The value of ut will never exceed the limit voltage value EVI corresponding to the rotational speed vl at this time.

That is, this limited voltage defines a so-called full Q characteristic.

Resistors R53, R54°R5 in the limited voltage generation circuit 30
The output voltage E from the level shift circuit 50 is connected to the connection point 5.
1o is derived.

Depending on the environmental conditions of the level shift circuit 50 &L engine, the limit voltage E9 from the synthesis circuit 38 is applied to the temperature of the air taken into the engine in order to provide the required maximum fuel injection amount characteristics according to the rotational speed of the engine. This circuit shifts the level according to the current level, and is mainly composed of an operational amplifier A1□.

A resistor R7□ is connected to the inverting input terminal of this operational amplifier A12.
, R7□, and R74, and the non-inverting input terminals are connected to resistors R73 and R7.
, and a thermistor TH apply a bias voltage.

Therefore, the voltage applied to the non-inverting input terminal is low when the temperature is high (and high when the temperature is low).

Therefore, the output voltage E1o of the output terminal is also low when the temperature is high and high when the temperature is low.

This output voltage E1° is inputted to the inverting input terminal of the operational amplifier A1□ via the resistor R70.

Therefore, as shown in FIG. 6, the level of the limiting voltage E9 is uniformly shifted with respect to the rotational speed as shown by the dotted line in accordance with the temperature.

However, when the outside temperature is high and the air density is low, as shown in dotted line A (the level of limiting voltage decreases uniformly, the maximum amount of fuel supply is suppressed lower than at normal temperature). , it is possible to effectively prevent black smoke from being generated in exhaust gas due to oversupply of fuel.

When the outside air temperature becomes low, the level increases uniformly as shown by the dotted line, and as the air density becomes thicker, the maximum amount of fuel to be supplied can be increased to ensure effective operation of the engine.

According to the present invention, since the maximum fuel injection amount supplied to the internal combustion engine is corrected on the fuel section side of the internal combustion engine fuel injection pump according to the temperature of the air taken into the engine, combustion in the internal combustion engine is This is done at a more appropriate air-fuel ratio, thereby further reducing the generation of harmful exhaust gases and black smoke.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of an embodiment of the present invention, Figures 2 and 3 a =
d, FIGS. 4a to 4d, and FIG. 5 are characteristic diagrams of voltages at various parts, respectively, and FIG. 6 is a characteristic diagram showing changes in the limiting voltage of the embodiment of the apparatus shown in FIG. 10... Fuel control circuit, 18... Speed voltage generation circuit, 24... First control voltage generation circuit, 26... Second control voltage generation circuit , 28...
. . . Third control voltage generation circuit, 30 .・・・・・・
・Level shift number, a... Accelerator operation amount,
El... Speed voltage, R3... First control voltage, R4... Second swing leg voltage, E,...
・Third control voltage, R6, R7, R8...output voltage, R9...limiting voltage, Elo...output voltage, D3...diode, ■・・・・・・
Rotational speed.

Claims (1)

[Claims] 1. A control signal calculation means for calculating a fuel adjustment member control signal corresponding to the rotational speed of the engine and the amount of accelerator operation, and a control signal calculating means for calculating a fuel adjustment member control signal corresponding to the rotational speed of the engine, and a control signal calculating means to prevent the fuel adjustment member control signal from exceeding a predetermined value corresponding to the rotational speed of the engine. limiting means for applying the fuel adjustment member control signal to the fuel adjustment member actuator;
a correction means for correcting a predetermined value of the air IJ according to the temperature of the air taken into the engine; 1. A fuel control circuit for a fuel injection pump for an internal combustion engine, characterized in that the circuit corrects the change in the air-fuel ratio of the engine.