JPS6115261B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic fuel injection control device (EFI) for an internal combustion engine. The present invention relates to an electronic fuel injection control device that controls the amount of fuel injected.

The previously proposed electronic fuel injection control system employs a method in which the basic amount of fuel injection is determined using either the engine's suction negative pressure or throttle valve opening, and the rotational speed.

As an example of this, in a relatively low load region of the engine, a matrix memory (map) with parameters of rotational speed (hereinafter abbreviated as Ne) and suction negative pressure (hereinafter abbreviated as PB) is used to Determine the fuel injection amount, and in other relatively high load areas,
Ne and throttle valve opening (hereinafter abbreviated as θth)
There is a hybrid method that determines the basic fuel injection amount using a matrix memory (map) with

In such a hybrid type electronic fuel injection control system, if at least one of the PB sensor and its wiring fails (damage, disconnection, short circuit, etc.), it will no longer be possible to control fuel supply to the engine in a relatively low load range. , there is a drawback that it becomes impossible to drive a vehicle, etc.

It is also possible to determine the basic fuel injection amount using a matrix memory (map) with PB and Ne as parameters over the entire load range, but in this case also, if a failure occurs in the PB sensor or its connection, There are similar drawbacks.

An object of the present invention is to improve the above-mentioned drawbacks, and to provide an electronic fuel injection system that enables fuel supply to the engine and enables operation of a vehicle even when at least one of the PB sensor and its connection fails. Provides control equipment.

In order to achieve the above object, in the present invention, the basic fuel injection amount is determined using the engine load range that is not used in the normal operating state of the engine, that is, in the example of a hybrid system, the basic fuel injection amount is normally determined using Ne and PB as parameters. Even for relatively low load areas such as When detected, fuel is injected and supplied using Ne and θth as parameters in the entire operating range, regardless of the level of the engine load.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. In the figure, 1 and 2 are first and second variable reluctance shaft rotation sensors, 3 and 4 are Schmitt trigger circuits that receive the outputs of the sensors 1 and 2, respectively, and 5 and 6 are Schmitt trigger circuits 3 and 4, respectively. A circuit that differentiates the output by a clock, 7 is a flip-flop, 9 is a counter,
10 is a latch, and 11 is a memory, such as a ROM, which stores a code for the engine speed Ne corresponding to the count value of the counter 9.

12 is a crystal oscillation circuit, 14 is a frequency divider, 15 is a timing control circuit, 16 is a silicon diaphragm type PB sensor, 17 is an A/D converter, 18 is a latch, and 19 stores an address corresponding to the output of the PB sensor 16. For example, the memory to
ROM, 20 is a memory that stores the basic fuel injection amount Ti using Ne and PB as parameters, e.g. ROM
(or Ne-PB map).

21 is a potentiometer-type θth sensor, 22 is an A/D converter, 23 is a latch, 24 is a memory that stores an address corresponding to the output of the θth sensor 21, such as a ROM, and 25 is a basic fuel injection amount using Ne and θth as parameters. The memory that stores Ti is, for example, ROM (or Ne-θth map).

29 is the thermistor type cooling water temperature (hereinafter referred to as Tw
(abbreviated as ) sensor. Note that the temperature of lubricating oil or the like may be used instead of Tw, and in short, as long as it can represent the engine temperature, it can be adopted as Tw. 32 is an A/D converter, 33 is a latch,
34 is the warm-up increase correction coefficient γ according to the detected value of Tw
A memory such as a ROM stores w, and 35 is a multiplier.

36 is a thermistor type intake temperature (hereinafter abbreviated as T1) sensor, 39 is an A/D converter, 40 is a latch, 41 is an atmospheric pressure (hereinafter abbreviated as P1) sensor, 42 is an A/D converter, 43 is Latsuchi,
47 is a memory, such as a ROM, which stores a mass correction coefficient γa corresponding to the detected values of T1 and P1, and 48 is a multiplier.

49 and 50 are first and second preset counters; 53 and 54 are flip-flops;
57 and 58 are first and second injector coils that control the fuel injection valve, and 61 is a warning indicator light.

Next, the operation of the above embodiment will be explained.

The first and second shaft rotation sensors 1 and 2 detect the reference position of the camshaft, and in this embodiment, these sensors output pulses that are 180 degrees out of phase with each other. These pulse outputs are supplied to Schmitt trigger circuits 3 and 4, respectively, and are waveform-shaped there. The shaped pulses are differentiated by clock differentiators 5 and 6, respectively, and a trigger pulse is generated in synchronization with the rising (or falling) of the pulse.
They become N1 and N2.

Flip-flop 7 is set by trigger pulse N1 and reset by trigger pulse N2. The Q output of flip-flop 7 is applied to AND gate 8 to open this gate. On the other hand, a clock pulse obtained by dividing the output frequency of the crystal oscillation circuit 12 is also applied to the AND gate 8. This allows AND gate 8
A counter 9 counts the clock pulses that have passed through the AND gate 8 during the time that the AND gate 8 is open.

As is clear, the above count value is the trigger pulse
This corresponds to the time difference between N1 and N2 occurrences, that is, the engine rotation speed. The above count value is latch 1
0, and the contents of the ROM 11 addressed by this value become the engine rotational speed Ne at that time. In this embodiment, Ne is represented by an 8-bit code.

The silicon diaphragm type PB sensor 16 detects the engine intake negative pressure PB. The detected analog value is converted into a digital value by the A/D converter 17. As the value of PB changes during a stroke of the engine, it is buffered in latch 18 during each stroke in synchronization with the N1 and/or N2 pulses. This stabilizes the control.

The ROM is controlled by the PB value latched as described above.
19 address and read out the detected value of PB. In this embodiment, PB is represented by an 8-bit code.

The ROM 20 is addressed using both the 8-bit code representing Ne and the 8-bit code representing PB, and the fuel injection pulse width Ti corresponding to the combination of each detected value Ne and PB at that time is read out.

The potentiometer type θth sensor 21 detects the value of θth. The analog detection value of the θth sensor 21 is converted into a digital value by the A/D converter 22. The obtained digital value is processed by N1 and / to prevent data fluctuation during calculation.
Alternatively, it is temporarily stored in the latch 23 in synchronization with N2.

ROM2 by θth stored in latch 23
4, and read out the detected value of θth in 8-bit code. Of the 8-bit code, the lower 7 bits represent the detected value of θth, and
ROM2 along with the 8-bit code representative of
5 is used for addressing, and each detected value at that time
It is used to read out the basic fuel injection pulse width Ti according to the combination of Ne and θth.

Of the 8-bit code of θth, the MSB (most significant bit) is used to determine whether to use the Ne-PB map in ROM20 or the Ne-θth map in ROM25 to read the fuel injection pulse width Ti. It will be done.

For this, the MSB of θth is the or gate 27
It is added to the CS terminal of ROM25 through
Via the or gate 27 and inverter 28
It is added to the CS terminal of ROM20. Therefore,
When the MSB of θth is “0”, that is, the value of θth is less than the expected value (the engine is in a low load state),
The read data from the ROM 20 is transferred to the multiplier 35, while the MSB of θth is "1" - that is,
When the value of θth is larger than the expected value (the engine is in a high load state), the read data from the ROM 25 is transferred to the multiplier 35.

Thermistor type Tw sensor 29 detects the temperature of engine cooling water. Note that, as described above, the temperature of lubricating oil or the like may be used instead, and any data representative of the engine temperature may be used.

The analog detection value of the Tw sensor 29 is converted into a digital value by the A/D converter 32.
The obtained digital value is temporarily stored in latch 33 in synchronization with N1 and/or N2 to prevent data fluctuation during calculation.

ROM34 by Tw stored in latch 33.
The warm-up increase correction coefficient γw
Read out in 8-bit code. The warm-up increase correction coefficient γw is transferred to the multiplier 35, where it is stored in the ROM 20.
or multiplied by the basic fuel injection pulse width Ti read from 25. The obtained product is the γw corrected fuel injection pulse width code, which is 8 in this example.
Represented by bits.

The thermistor type T1 sensor 36 measures the intake air temperature of the engine. The obtained analog detection value is
It is converted into a digital value by the A/D converter 39,
Similarly to the case of θth and Tw detection value, set latch 4.
Temporarily stored in 0. In this embodiment, the value of T1 is represented by 4 bits.

The silicon diaphragm type P1 sensor 41 detects atmospheric pressure. The analog detection value of the P1 sensor 41 is converted into a digital value by the A/D converter 42, and is temporarily stored in the latch 43 in the same manner as the θth and Tw detection values described above. In this embodiment, the value of P1 is represented by 6 bits.

The ROM 47 is addressed by the digital values of the intake air temperature T1 and the atmospheric pressure P1, and the mass correction coefficient γa is read out. The obtained mass correction coefficient γa is transferred to the multiplier 48, where it is multiplied by γw·Ti, which is the output (product) of the multiplier 35.

As a result, an actual fuel injection pulse width output (γw·γa·Ti) 59 that has been subjected to warm-up increase correction and correction according to the mass of intake air is obtained. Actual fuel injection pulse width output 59 is represented in this example by an 8-bit code.

The actual fuel injection pulse width output 59 is input to preset counters 49 and 50, respectively. At the same time, flip-flops 53 and 54 are
Set by a signal synchronized with N1 and N2 pulses. Then, the Q output of each flip-flop is supplied to amplifiers 55 and 56, respectively, and the corresponding injector coils 57 and 58 are energized to start fuel injection.

On the other hand, the Q outputs of flip-flops 53 and 54 open corresponding AND gates 51 and 52 to supply clock pulses to counters 49 and 50, respectively. As a result, the preset values of the preset counters 49 and 50 are counted down. When each count reaches 0, each preset counter 49, 50 generates a borrow signal, which resets flip-flops 53, 54.

In this way, each flip-flop 53,5
When the Q output of No. 4 becomes "0", the energization of the injector coils 57 and 58 is stopped, and fuel injection is completed.

As above, Ne, PB, θth, Tw, T1
And appropriate fuel supply is carried out according to the value of P1.

Figure 2 shows silicon diaphragm type PB sensor 1.
A specific example of connection No. 6 is shown below.

R1 and R2 are resistors that are provided on a silicon diaphragm (not shown) and change their resistance values as the silicon diaphragm is deformed (curved) by the suction negative pressure PB, and R3 and R4 are fixed resistors. . As is clear from the diagram, the resistance R1~
R4 constitutes the bridge. Also, resistor R5
is selected to have a value such that when the ground wire is disconnected, the input to the A/D converter 17 is larger than the value in the normal variation range of PB.

The unbalanced voltage of the bridge is supplied to a differential amplifier 62, and its output is input to the A/D converter 17 as a PB detection value.

The operating point of the A/D converter 17 in this case is
The output digital value is set so that it does not become OO ₁₆ or FF ₁₆ within the normal change range of suction negative pressure PB. When the following abnormality occurs in the PB sensor, the output digital value will be OO ₁₆ or FF ₁₆ .

(1) When the power supply +V connection is disconnected...Vin is 0
volts, and the output digital value will be OO ₁₆ .

(2) When the ground wire is disconnected...Vin rises beyond the normal change range and the output digital value becomes FF ₁₆ .

(3) When the input connection of the A/D converter 17 is disconnected...Vin rises and the output digital value becomes FF ₁₆
become.

(4) When the input connection of the A/D converter is shorted to the ground wire...Vin becomes 0 volts and the output digital value becomes OO ₁₆ .

(5) When the input connection of the A/D converter is shorted to the power supply +V...Vin rises to the power supply voltage and the output digital value becomes FF ₁₆ .

As shown in FIG. 1, the A/D converter 17
Since all output bits of the A/D converter 17 are input to the EX-OR (exclusive OR) gate 26, all output bits of the A/D converter 17 are "1" (i.e., FF ₁₆ ).
or becomes "0" (ie, OO ₁₆ ), the output of the EX-OR gate 26 becomes "0" - that is, its inverted output becomes "1". The inverted output of EX-OR gate 26 is applied to OR gate 27.

Therefore, when the inverted output of the EX-OR gate 26 is "0", that is, when the output of the PB sensor 16 is within the normal operating range, there is no effect on the above-mentioned operation.

However, if the output of the PB sensor 16 exceeds the normal operating range and becomes OO ₁₆ or FF ₁₆ , EX-
The inverted output of the OR gate 26 becomes "1". This output is passed through the OR gate 27 to the CS of the ROM 25.
to the terminal, also OR gate 27 and inverter 2
8 and are respectively input to the CS terminal of the ROM 20.

As a result, when the inverted output of the EX-OR gate 26 becomes "1", the contents of the ROM 25 are always read out. At the same time, EX−OR
The inverted output of 26 is applied to an amplifier 60, and the amplified output lights up a warning indicator light 61. Although not shown, it is also possible to indicate that an abnormality has occurred in the PB sensor circuit by other means such as generating an alarm sound.

As described above, according to the present invention, the basic fuel injection pulse width with Ne and θth as parameters is stored in the ROM over the entire operating range of the engine, and when an abnormality occurs in the PB sensor circuit, , the fuel injection control is determined from Ne−θth from the Ne−PB map.
Since the system automatically switches to the map, there is no possibility that the vehicle will become unable to drive.

In this case, the basic fuel injection pulse width data to be stored in the Ne-θth map, which corresponds to the area where fuel injection amount control is executed according to the Ne-PB map during normal operation, is based on the Ne-PB map during normal operation.
A value larger than the basic fuel injection pulse width data stored in the map is stored. This makes it possible to prevent the A/F ratio from becoming too low and causing engine knocking or the like.

Further, the number of code bits of each data described above is merely an example, and it is natural that the present invention is not limited to this.

Further, although the hybrid electronic fuel injection system has been described above as an example, the present invention is not limited to this, and under normal operating conditions,
It is obvious that the present invention can also be applied to a case where only the PB sensor is used and the basic fuel injection amount data is read out using the Ne-PB map. That is, in this case, prepare the Ne-θth map for backup in advance, detect an abnormality in the PB sensor in the same way as described above, and if an abnormality is detected, Ne-θth map is prepared in advance.
All you have to do is switch from the PB map to the Ne-θth map.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure is a specific circuit diagram of a part thereof. 1, 2...variable reluctance type shaft rotation sensor,
3, 4... Schmitt trigger circuit, 5, 6... Clock differentiation circuit, 9... Counter, 11...
ROM, 16... Silicon diaphragm type PB sensor, 19, 20... ROM, 21... Potentiometer type θth sensor, 24... ROM, 25...
ROM, 29...Tw sensor, 34...ROM, 3
5... Multiplier, 36... Thermistor type Ti sensor, 41... P1 sensor, 47... ROM, 48...
...multiplier.

Claims (1)

[Claims] 1 A first memory that stores the basic fuel injection amount at high load and low load using the throttle valve opening that controls the intake air amount to the engine and the engine rotation speed as parameters, and the engine intake negative pressure and engine rotation speed. The second memory stores the basic fuel injection amount at low load using as a parameter, and the first memory is selected when the engine load is greater than the scheduled value, and the second memory is selected when the engine load is less than the scheduled value. In an electronic fuel injection control device comprising a memory selection means and a means for outputting the memory content of the memory selected as described above as basic fuel injection amount data to control the fuel injection amount, means for detecting that the operation of the sensor is abnormal; and a means for detecting abnormality in the operation of the sensor;
and means for forcibly selecting a memory, wherein the low load basic fuel injection amount stored in the first memory is larger than that stored in the second memory. type fuel injection control device.