JPS5949415B2 - Rotation speed detection device for electronically controlled fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotational speed detection device for an electronically controlled fuel injection device, which is used in an electronically controlled fuel injection device and detects the engine rotational speed based on an engine operating state other than the actual engine rotational speed.

Conventionally, electronically controlled fuel injection devices have been known as devices that supply fuel to internal combustion engines.This device cuts fuel when the engine decelerates, and increases the amount of fuel when starting or under high load. There is.

This fuel cut and fuel increase are advantageous in that they enable accurate fuel supply to the engine, but since both are related to the engine speed, the means for detecting the engine speed is extremely complicated.

That is, a rotation speed detector must be provided to determine the rotation speed range, and a separate comparator must be provided to compare the detected rotation speed with each set value.

As a result, as the number of elements increases, the cost and reliability of the device increases.

The present invention solves the above problem by generating a reference pulse signal whose time width changes depending on the engine condition such as the throttle valve opening of the engine, and by changing the time width of this reference pulse signal and every predetermined rotational position of the engine. By comparing the generation period of a pulse signal with a time width indicating the amount of fuel injection generated during the engine rotation, the engine speed can be detected indirectly with a simple configuration, without increasing the cost of the device, and furthermore, When the opening degree is below the set value, the time width of the reference pulse signal is corrected according to the engine temperature, so rotation speed detection for electronically controlled fuel injection devices does not cause a decrease in reliability in fuel cut control. The purpose is to provide equipment.

An embodiment of the present invention shown in the drawings will be described below.

In FIG. 1, reference numeral 1 denotes an ignition (IG) coil that detects an engine rotational speed signal in the form of a voltage waveform, 2 a waveform shaping circuit that shapes the voltage waveform to prevent malfunctions, and 3
In the case of a 6-cylinder engine, electromagnetic injection valve 1 injects fuel every engine revolution.
This frequency dividing circuit 3 is a child frequency dividing circuit for operating the electromagnetic injection valve 11 once or more in one rotation of the engine. Of course.

4 is an arithmetic circuit which inputs a signal corresponding to the intake air amount from the intake air amount detector 5 and divides the intake air amount of the engine by the engine speed, that is, calculates the amount of air sucked into one cylinder in one stroke. This outputs a pulse signal T1 having a pulse time width t1 proportional to .

6 is a multiplication circuit which increases or multiplies the pulse time width t1 of the pulse signal T1 outputted from the arithmetic circuit 4 by various signals from the status detector γ that detects the engine cooling water amount, intake air temperature, etc., and generates a pulse. Pulse signal t with time width t2
2.

Reference numeral 8 denotes a voltage correction circuit which inputs the pulse signal T2 from the multiplication circuit 6 and outputs a voltage correction pulse signal T3 having a time width t8 to correct changes in the fuel injection amount from the electromagnetic injection valve 11 depending on the applied voltage. It is something to do.

9 is an OR circuit which receives pulse signals TI, T2, from the arithmetic circuit 4, the multiplication circuit 6, and the voltage correction circuit 8;
Input T11 and calculate the pulse time width (t 1 + t 2 +
supplying the pulse signal T of t a ) to the output circuit 10;
The electromagnetic injection valve 11 is operated according to the time width of the pulse signal T (t1+t
The valve is kept open for a period of 2 ++ 8) to supply the optimum amount of fuel into the engine according to the operating condition of the engine.

The above configuration and operation are known as an electronically controlled fuel injection system.

12 is a reference pulse generation circuit using a retriggerable monostable multivibrator; 13 is a reference pulse generation circuit 12 synchronized with the period of the pulse signal T1 synchronized with the engine rotation from the arithmetic circuit 4 and the pulse signal T1; This is a comparison circuit that compares the time width tv of the pulse signal Tv from .

The pulse time width tv of the reference pulse generation circuit 12 changes according to the input signal, and the starter drive detector 14, which detects the engine starting state, and the throttle detector 15, which detects the opening degree of the throttle valve, generate the reference pulse. Generation circuit 1
It is connected to 2.

Further, when the throttle opening is less than the set value, the reference pulse generating circuit 12 generates a pulse signal Tv according to the engine temperature.
A temperature correction circuit 16 is connected to the reference pulse generation circuit 12 in order to change the time width tv.

This configuration is for detecting the engine speed indirectly from the operating state of the engine.

As shown in FIG.
, resistors 121, 122, 123° 124, transistors 125, 126, inverters 12γ, 129, NAND
Consists of gate 128, buffer gate) 1201,
A low-level signal is input to the buffer controller 1201 from the starter drive detector 14 while the starter is driving, that is, when the engine start switch is closed, and to the inverter 129, a low-level signal is input when the throttle valve opening is below a set value. A high level signal is input from the throttle detector 15.

The comparison circuit 13 is composed of a D flip-flop 130, an AND gate 131, and buffer gates 32 and 133.

The temperature correction circuit 16 includes a thermistor 160 for engine temperature detection, resistors 161 to 166,) transistors 167, .
168 and a diode 169.

Next, the operation of the configuration shown in FIG. 2 will be explained with reference to FIG. 3.

First, when the engine is started and the starter is being driven, the starter drive detector 14 inputs a ++O++ double signal (low level signal) to the reference pulse generation circuit 12, and the inverter 127
The transistor 126 is turned off in order to generate a high level signal (II+multiple signal high level signal).

At this time, since the NAND gate 128 also generates the II II I+ signal, the transistor 125 is also turned off.

Therefore, no current flows through resistors 121 and 122, and resistor 1
Monostable multivibrator 1200 operates with a time constant determined by 23, 124 and capacitor 120.

This monostable multivibrator 1200 is synchronized with a pulse signal T1 having a time width t1 shown in FIG.
1 pulse signal Tv is generated.

The voltage across the capacitor 120 at this time is illustrated by the characteristic line b1 in FIG. 3B, and the time width tvl depends on the characteristic line b1.

The time width tvt of the pulse signal TV is set corresponding to the first set rotation speed of the engine. For example, the period of the pulse signal T1 when the engine speed is the first set rotation speed of 40 rpm is If it is 150m5, the time width tvl is also 15
It is set to 0m5.

During normal engine operation after the engine has been started, the starter is not driven, so the signal from the starter drive detector 14 to 1'1'1
The signal is input to the reference pulse generation circuit 12.

This signal is inverted by the inverter 121 and becomes II O+
Since it becomes a + signal, the transistor 126 is turned on, and current flows through the resistor 121.

At this time, if the throttle valve opening changes from a state above the set value to a state below the set value, the throttle detector 15
The signal input to the reference pulse generation circuit 12 from ++
The NAND gate 12 is inverted from the O++ level to the II I I+ level and is inverted by the inverter 129.
8 generates a signal II I If times.

Therefore, the transistor 125 is turned off,
No current flows through the resistor 122.

On the other hand, if the throttle valve opening is below the set value, the inverter 12
9 is generated, the transistor 168 of the temperature correction circuit 16 is in the OFF state, and the transistor 161 is turned off due to the temperature dependent characteristics of the thermistor 160.
The base potential of becomes higher as the engine temperature becomes lower.

Therefore, the emitter-follower connected transistor 16
The emitter potential of No. 7 increases as the engine temperature decreases.

This emitter potential is connected to the resistor 166 and diode 169.
The signal is input to the reference pulse generation circuit 12 via the reference pulse generating circuit 12.

In this way, the monostable multivibrator 1200 has capacitor 120 and resistors 121, 123, 124, 16
6, and generates a pulse signal Tv having a time width t2 as shown in FIG. 3C in synchronization with the pulse signal T1 shown in FIG. 3A from the arithmetic circuit 4.

The voltage across the capacitor 1200 at this time is shown by the characteristic line b2 in FIG. 3B, and the time width tv2 depends on the characteristic line b2.

As mentioned above, since the current flowing through the resistor 166 changes depending on the engine temperature, the lower the engine temperature, the greater the slope of the characteristic line b2, and the time width t of the pulse signal TV.
v2 becomes smaller.

This time width jv2 is set corresponding to the second set rotation speed of the engine, and when the temperature correction circuit 16 does not make temperature correction, for example, the engine speed is set to the second set rotation speed 16.
The period of pulse signal T1 at 00 rpm is 37.5 ms
If so, the time width t2 is also set to 37.5 ms.

Then, due to the action of the temperature correction circuit 160 described above, the lower the engine temperature, the smaller the time width tv2 of the pulse signal Tv2, and as a result, the lower the engine temperature is, the higher the second set rotation speed is set.

Next, when the starter is not driven and the throttle valve opening is above the set value, the "10" 1 signal is input from the throttle detector 15 to the reference pulse generation circuit 12, so the NAN
D-gate 128 produces the IIOI+ signal.

Therefore, since both transistors 125 and 126 are in the ON state, the monostable multivibrator 1200 is
and resistor 166 no longer participates in the time constant.

This is because the transistor 167 of the temperature correction circuit 16.
This is because 168 are in the OFF and ON states, respectively.

At this time, the voltage across the capacitor 120 changes as shown by the characteristic line b8 in FIG. 3B, and the monostable multivibrator 1200 synchronizes with the pulse signal T1 shown in FIG. 3A.
A pulse signal TV having a constant time width tv3 shown in FIG. 3C is generated.

This time width tv3 is set corresponding to the third engine rotation speed, for example, when the engine rotation speed is the third set rotation speed 40.
If the period of the pulse signal T1 at 00 rpm is 20 m5, the time width tv3 is also set to 20 m5.

That is, the time width of the reference pulse TV generated by the reference pulse generation circuit 12 according to the input signal of the throttle valve opening and the starter drive state is the time width tv1 corresponding to the first set rotation speed when the starter is being driven; When the valve opening is below the set value, the time width jv2 corresponds to the second set rotation speed that changes depending on the engine temperature, and when the throttle valve opening is above the set value, the third set rotation speed is set. The time width tva corresponds to .

The D flip-flop 130 of the comparator circuit 13 compares the period of the pulse signal T1 input from the arithmetic circuit 4 to the clock terminal C with the time width tv of the pulse signal TV input from the reference pulse generation circuit 12 to the data terminal. However, when the period of the pulse signal T1 is smaller than the time width tv, the Q output and the RI output receive the II I II times signal and the II O signal, respectively.
I+II, and vice versa produces the opposite signal.

As is well known, the period of the pulse signal T1 from the arithmetic circuit 4 is inversely proportional to the engine rotation speed. The Q and Q outputs of II I I+ double signal and II □ I+ respectively
A double signal is generated.

Therefore, an 11" signal is generated at the terminal 100 connected to the Q output via the buffer 133 when the engine rotation speed is below the first set rotation speed (for example, 400 rpm), and the first
When the rotation speed is higher than the set rotation speed, an It □ It times signal is generated.

Also, if the engine rotation speed is set to a second set rotation speed (for example, 1600r
pm), and only when the throttle valve opening is below the set value, the Q output and A connected to the throttle detector 15 are
II II I! to the terminal 300 via the ND gate 131
A double signal is generated.

Furthermore, the engine rotation speed is set to a third set rotation speed (for example, 4ooor
pm), an "11" signal is generated at the terminal 200 connected to the Q output via the buffer 132, and a 10"1 signal is generated when the rotation speed is greater than the third set rotation speed.

Therefore, the engine speed can be indirectly detected by the signal levels generated at the terminals 100, 200, and 300. For example, when an II I n signal is generated at the terminal 100, the amount of fuel for starting the engine is increased in response to this signal. can be caused to occur in the terminal-controlled fuel injector, and the terminal 200
1. When the II double signal is generated, the fuel amount can be increased in the same way to increase the engine output, and the terminal 300 is also connected to the I
When the t I I+ signal is generated, a fuel cut can be made to decelerate the engine.

Moreover, the second set rotation speed is corrected and set higher according to the engine temperature, especially as the engine temperature becomes lower. Even during so-called fast idling, where air is introduced and the rotational speed is stabilized, the problem of the rotational speed rising and fuel cut-off is eliminated.

In the above embodiment, the pulse signal T1 of the arithmetic circuit 4 is used as the pulse signal related to the engine rotation speed, but a pulse signal generated by the frequency dividing circuit 3 and having a time width inversely proportional to the number of engine circuits may be used. Further, a signal indicating an engine operating state other than the throttle valve opening and the starter driving state may be inputted to the reference pulse generating circuit 12 to set an even higher set rotation speed.

Further, the output level of the signal indicating the comparison result between the set rotational speed and the engine rotational speed may be changed and inverted as appropriate.

As described above, in the present invention, a reference pulse signal whose time width changes depending on the opening state of the engine throttle valve, etc. is generated, and the engine rotation speed is set according to the time width of this reference pulse signal. The pulse signal and the generation period of the pulse signal from the fuel injection amount calculation means that forms a pulse signal with a time width indicating the fuel injection amount according to the engine parameters at each predetermined rotational position of the engine (in other words, this generation period corresponds to the predetermined rotational position) (This value indicates the time width depending on the engine speed) to detect whether or not the engine speed has reached the set speed. In the following cases, the time width is corrected according to the engine temperature, so there is no need to increase the rotation speed comparison means each time the set rotation speed increases, and the engine speed can be detected with a simple configuration. ,
This has an excellent effect in that it does not increase the cost of the device and does not cause a decrease in reliability in fuel cut control.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention, FIG. 2 is an electrical wiring diagram showing the detailed configuration of the main parts of FIG. 1, and FIG. 3 is a second diagram for explaining the operation of the present invention. It is a signal waveform diagram of each part inside. 12... Reference pulse generation circuit, 13... Comparison circuit,
14... Starter drive detector, 15... Throttle detector, 16... Temperature correction circuit.

Claims (1)

[Claims] 1. A fuel injection amount calculation means that forms a pulse signal with a time width indicating the fuel injection amount according to engine parameters at each predetermined rotational position of the engine; and a throttle opening detector that detects the opening of the throttle valve of the engine; A reference pulse that generates a reference pulse signal indicating a set rotation speed in synchronization with the pulse signal from the fuel injection amount calculation means, and that changes the time width of this reference pulse signal in accordance with the detection output of the throttle opening degree detector. generation means; temperature correction means for correcting the time width of the reference pulse signal generated by the reference pulse generation means according to the engine temperature when the opening degree of the throttle valve is below a set value; and the fuel injection amount calculation means. and comparing means for comparing the generation period of the pulse signal of the reference pulse signal with the time width of the reference pulse signal from the reference pulse generating means, and determining whether or not the rotation speed of the engine has reached the set rotation speed based on the output signal of the comparison means. A rotation speed detection device for an electronically controlled fuel injection device, characterized in that it detects whether