JPS58126439A - Fuel supply control method and device for internal combustion engine - Google Patents

Abstract

PURPOSE:To spread a range of fuel cut operation and improve a rate of fuel consumption, by performing recut operation of fuel supply when a brake device is applied and stopping the recut operation when the brake device is not applied. CONSTITUTION:A control circuit 30 again performs cut operation of fuel supply when speed of an engine by a signal of a crank angle sensor 40 is between the first preset value performed with a cut of fuel supply and the second preset value restarted with the supply further when the engine again becomes a deceleration condition. When this recut operation is performed, the circuit 30 decides a brake device of the engine if operated or not by a signal of a brake switch 54, to perform the recut operation at application of the brake device, while not to perform the both cut operations at no application of the brake device. Accordingly, even if the speed of fuel resetting is low set, a torque shock due to the cut operation is not so generated, while a range of fuel cut operation can be spread to improve fuel consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for controlling the supply of fuel to an internal combustion engine, and more particularly to a method and apparatus for controlling a fuel supply cut operation.

When the engine is in deceleration operation and the rotational speed of the engine is equal to or higher than a predetermined rotational speed for cutting fuel supply (hereinafter referred to as fuel cut rotational speed), a fuel cut operation is performed, and after that, deceleration operation is terminated. Alternatively, the above fuel cut operation is performed when the rotation speed becomes lower than the fuel cut rotation speed (3), which is predetermined at a lower value (hereinafter referred to as the fuel return rotation speed). The technology of controlling the restart of fuel supply and thereby improving the fuel consumption rate and reducing the amount of harmful components in exhaust gas is well known. It is best to set the return rotation speed to a lower value to widen the area in which fuel is cut.However, if the fuel cut operation is performed to a low rotation speed, sudden torque fluctuations may occur when fuel supply is resumed. This causes a shock to the engine and its vehicle.For this reason, in the conventional technology, the fuel return rotational speed cannot be lowered much, and the fuel consumption rate cannot be expected to be improved much at all.

Regarding the technology for switching and controlling the fuel return rotational speed to a high rotational value or a low rotational value using on/off signals of a vehicle speed switch, clutch switch, neutral switch, or brake switch, etc., see Utility Model Application No. 54-113.
This is already known from Publication No. 922 and the like. However, the table shows that even with this type of method (4), the torque shock caused by the fuel cut operation could not be sufficiently suppressed.

Therefore, the present invention solves the above problems of the prior art, and an object of the present invention is to improve the fuel consumption rate without increasing the torque shock accompanying the fuel supply cut operation, or to improve the fuel consumption rate without increasing the torque shock accompanying the fuel supply cut operation. On the contrary, the method of the present invention for achieving the above-mentioned object is to provide a fuel supply control method and device capable of reducing the occurrence of the above-mentioned torque shock as soon as the fuel consumption rate deteriorates. The fuel supply cut operation is performed when the engine rotational speed is between the first set value for cutting fuel supply and the second set value for restarting fuel supply, and the engine is in deceleration operation again. In the fuel supply control method performed again, it is detected whether or not the engine braking device is operating, and if it is operating, the fuel supply re-cut operation is performed, whereas if it is not operating, the nuclear fuel supply is re-cut. The apparatus of the present invention is characterized in that the apparatus of the present invention has a means for detecting the engine rotation speed, a means for detecting that the engine is in a deceleration operating state,
means for detecting whether or not a braking device of an engine is operating; at least one intermittently operated fuel injection valve; and a fuel injection system for supplying a fuel injection signal having a pulse width depending on an idle state to the injector. a control means, and the means determines that the detected rotational speed is between a first setting value for cutting fuel supply and a second setting value for restarting fuel supply, and that the rotational speed is in a deceleration operating state. means for generating a fuel supply cut signal when the braking device is detected and the braking device is detected by the means, and transmitting the fuel injection signal to the injector in response to the fuel supply cut signal. It is characterized by being equipped with a means to prevent it.

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

FIG. 1 schematically shows an example of an electronically controlled fuel injection type internal combustion engine as an embodiment of the present invention. In the figure, 10 represents the engine body, 12 represents an intake passage, 14 represents a combustion chamber of one cylinder, and 16 represents an exhaust passage. The flow of intake air taken in through an air cleaner (not shown) is detected by an air flow sensor 18, and the flow rate of the intake air is controlled by a throttle valve 20 that is linked to an accelerator pedal (not shown). The intake air that has passed through the throttle valve 20 is guided to the combustion chamber 14 of each cylinder via the surge tank 22 and each intake valve 24.

The fuel injection valve 26 is actually provided for each cylinder, and is controlled to open and close in response to electrical drive pulses sent from the control circuit 30 via the line 28, and is designed to provide a powerful fuel supply as shown in the figure. The pressurized fuel sent from the system is intermittently injected into the intake passage 12 (intake port section) near the intake valve 24, and the exhaust gas after being combusted in the combustion chamber 14 is transferred to the exhaust valve 32.
and the catalytic converter 34 via the exhaust passage 16
An air flow sensor 18 is provided in the intake passage 12 upstream of the throttle valve 20, and
Generates a voltage according to the intake air flow rate. This output voltage is sent to a control circuit 30 via a line 36 (7).A crank angle sensor 4 is connected to an engine distributor 38.
0 and 42 are installed, these sensors 40,
From 42, the crankshaft is 30 degrees.

A pulse signal is output each time it rotates 360°,
These pulse signals are sent to the control circuit 30 via lines 44 and 46, respectively.The throttle valve 20 operates in conjunction with the throttle position switch, which is closed when the throttle valve 20 is in the fully closed position (idle position). The signal from 48 is fed to control circuit 30 via line 50.

A signal from the limit switch that closes when the brake pedal 52 is depressed is sent to the control circuit 30 via a line 56. A magnet rotates in conjunction with the rotation of the speedometer cable. and a reed switch.
8 outputs a pulse signal having a frequency corresponding to the running speed of the vehicle, and this pulse signal is sent to the control circuit 30 via a line 60.

(8) FIG. 2 is a block diagram showing a configuration example of the control circuit 30 shown in FIG. 1.

Voltage signal from air flow sensor 18 and vehicle speed sensor 5
The pulse signal sent from 8 is frequency-voltage (F/V
) The voltage signal obtained by F/V conversion in the converter 62 is
The signal is sent to an analog-to-digital (A/D) converter 70 having an analog multiplexer function, and is sequentially converted into a binary signal according to instructions from a microprocessor (MPU) 72.

A pulse signal every 30 degrees of crank angle from the crank angle sensor 40 is sent to a well-known speed signal forming circuit provided in the input/output circuit (I10 circuit) 74, and is thereby used to generate a binary signal representing the rotational speed of the engine. A signal is formed. The pulse signal for each crank angle of 360° from the crank angle sensor 42 is the same (sent to the I10 circuit 74,
It is used in cooperation with the above-mentioned pulse signal for each `` to form an interrupt request signal for fuel injection pulse width calculation, a solvent injection start signal, a cylinder discrimination signal, etc.

The binary signals of 11' and "O" from the throttle position switch 48 and brake switch 54 are also ■10
The signal is sent to a predetermined pit position in the circuit 74 and temporarily stored.

A well-known fuel injection control circuit including a presettable down counter and a register is provided in the input/output circuit (I10 circuit) 76, and the pulse is determined based on binary data regarding the injection pulse width sent from the MPU 72. The injection pulse signals forming an injection pulse signal having a width are sequentially or simultaneously sent to the fuel injection valves 26a to 26d via a gate circuit 84 and a drive circuit (not shown) to energize them. This causes fuel to be injected according to the pulse width of the fuel injection pulse signal. The gate circuit 84 is closed in response to a fuel cut instruction signal sent from the MPTJ 72 to a predetermined pit position of the I10 circuit 76, thereby cutting off the injection pulse signal and performing a fuel supply cut operation.

The A/D converter 70 and I/Q circuits 74 and 76 are connected to the main components of the microcomputer, such as an MPU 72, a random access memory (RAM) 7B, and a read-only memory (ROT 14) 80, via a common bus 82. Data and instructions are transferred via this bus 82.

The ROM 80 contains a main processing routine program, an I+ processing routine program for calculating the fuel injection pulse width, a vll for forming a fuel cut instruction signal, a 1 processing routine program, and other programs necessary for these calculation processes. As the control circuit 30 in which various data are stored in advance, various configurations different from those described above can be applied. For example, without providing a speed signal forming circuit in the engine circuit 74, it is possible to configure the MPU 72 to directly receive a pulse signal for each predetermined crank angle and form the speed signal using software. Further, without providing a fuel injection control circuit in the I10 circuit 76, it may be configured such that a signal having a logical value of "1" is generated only for a time corresponding to the injection pulse width using software. Furthermore, it is also possible to configure the gate circuit 84 without providing the gate circuit 84 and to achieve its function by software.

Next, the operation of the above-mentioned microcomputer will be explained.

During its main processing routine, the MPU 72 retrieves the latest data representing the engine rotational speed N from r/.

The data is taken in from the circuit 74 and stored in the RAM 78. Also A/
'By the human/D conversion completion interrupt from the D converter 70, the latest data representing the intake airflow cover Q of the engine and the latest data representing the vehicle speed VS are received and stored in the RAM 78.

The MPU 72 executes a processing routine as shown in FIG. 3 in response to an interrupt request signal generated at a predetermined crank angle position, and calculates the fuel injection pulse width τ.

Although this type of processing routine is well known, its contents will be briefly explained. First, in step 90, the CPU 72 reads the intake air flow rate data Q and rotational speed data from the RAM 78, and in step 91, reads the basic injection pulse width τ. τ. Calculated from =K・−9・. however,
K is a constant. Then, in step 92, the basic injection pulse width τ. , a total correction coefficient R1 determined according to various correction coefficients, and a value τ corresponding to the invalid injection time of the fuel injection valve.
7, the final injection pulse width τ is calculated from the following formula: τ=τ.・R1τ7 In the next step 93, data corresponding to the calculated injection pulse width τ will be set in the aforementioned register of the I10 circuit 76. FIG. 4 shows an interrupt processing routine for creating a fuel cut instruction signal. There is. The MPU 72 executes the processing routine shown in FIG. 4 in response to an interrupt request signal generated at predetermined time intervals. First, in step 100, the MPU 7
2 determines whether the signal from the throttle position switch 48 is logic "0#", that is, whether or not the throttle position switch 48 is on. "NO"
In this case, the throttle valve 20 is open and the engine is not in a deceleration operating state, so the process proceeds to step 101 and the fuel cut flag FFc is set to "O#".If the fuel cut flag FFC is F and c=O , fuel cut instruction signal is also 1
0#, the gate circuit 84 is opened and normal fuel injection is performed. That is, if the low speed position switch 48, in which the fuel cut operation is not performed, is on, the process proceeds to step 102, where it is determined whether the vehicle path vS is less than or equal to a predetermined value. If VS≦A, the program proceeds to step 103 and determines whether the signal from the brake switch 54 is a logic 10'', that is, whether the brake switch 54 is on.N
If the brake pedal 52 is not depressed, the program proceeds to step 104 and sets the brake flag F to '0''. On the other hand, if it is determined that the brake switch 54 is on and therefore the brake pedal 52 is depressed, the program proceeds to step 05 and the brake flag F is set to @1#. When the process of step 105 is completed, the program proceeds to step 106, where it is determined whether or not the brake 7 lag FB' set during the previous execution of this process routine is 1#. When F11' = 1, that is, the previous brake flag F, 1' and the current brake flag F
If both B and B are "1", in other words, if the brake operation is performed continuously, the program proceeds to step 107. On the other hand, if FB'=0, the program is executed at step 10.
Proceed to step 8. That is, if the current brake flag FB is 0'', or if the current brake flag F is ``Town'' but the previous brake flag F, is 10#, the process proceeds to step 108. Therefore, if the brake operation is not being performed or if it is being performed, it is only an intermittent force, then the process proceeds to step 108. In step 108, it is determined whether the engine rotation speed N is less than the fuel cut rotation speed NFC.

1NO#, that is, if Nyc≦N, the program returns to step Ill via steps ]09 and 110.
Then, the fuel cut flag FFc is set to 11". As a result, the fuel cut instruction signal becomes "1". Therefore, in this case, the fuel cut operation (15) is definitely performed.

Finally, in step 109, the value n representing the number of times the operation from fuel supply cut to fuel supply restart has occurred between the fuel cut rotation speed NFC and the fuel return rotation speed N2c,L is set to "0#". is set to

Further, in step 110, a hysteresis flag FH used to perform a hysteresis operation regarding the rotational speed for fuel cut and restart is set to "1".

On the other hand, if it is determined in step 108 that N (N, c), the program proceeds to step]12.Step 1]
In step 2, it is determined whether the operation from fuel supply cut to fuel supply restart has been performed, and if 'YES',
In step]13, after increasing n by @1'', if the answer is "NO", the process directly proceeds to step 1.14.In step]14, it is determined whether n≧1. , engine rotation speed N is fuel cut rotation speed N2
This is to prohibit the fuel re-cutting operation from being performed after c. If so, step 10]
The process proceeds to step 115, where FFc←0 is set, and the fuel cut operation is performed again.

In Step 1]5, it is determined whether the engine rotational speed N is higher than the fuel return rotational speed NrcR.
In this case, the process advances to step 101 via step 116, and fuel is supplied. Finally, in step 116, the hysteresis flag F□ is set to "0".NFcR
If <N, it is checked in step 117 whether FHHF2 or not. In other words, after the rotational speed N has once exceeded the fuel cut rotational speed NFC, NFcR<N
< Check whether it has become Nyc. 'NO''
If so, proceed to step 101 and do not perform the fuel cut, and only if “YES” proceed to step 1 [Proceed to 1 and perform the fuel cut operation] In step 8, the current brake flag FB is set to FB′←FB. The flag is then held as the previous brake flag in the next processing routine. When the processing in step 118 is completed, the program returns from this interrupt processing routine to the main processing routine.

The above description relates to the operation when the vehicle speed VS is less than or equal to the set value A and the brake is not operated at all or is operated intermittently.

If the vehicle speed VS is less than the set value A and the brake is continuously operated, the process proceeds from step 06 to step 107, as described above. In step 107, substantially the same processing as in step 108 described above is performed. However, N
If <N, c, proceed to step]15. That is, when the brake is continuously operated, if N exceeds N2c, fuel cut operation is performed during deceleration, and then Nrcn
< N < NP (!) Even if the vehicle is in the range, a fuel re-cut operation is performed during deceleration.

On the other hand, if it is determined in step 102 that the vehicle speed VS exceeds the set speed, the program proceeds to step]19 and performs the processing in step 120 or 121. That is, when the brake switch 54 is on, FIl←1 is processed, and when it is off, FB←0 is processed, and the process then proceeds to step 107, where N, c, < N (N,
Even in the range c, control is performed such as re-cutting the fuel during deceleration.

FIG. 5 is a diagram illustrating the operation of the processing routine in FIG. 4. FIG.
) indicates that the brake is being operated forcefully or intermittently. In the figure, the horizontal axis represents engine rotational speed N and the vertical axis represents time.

Further, the solid line indicates the range in which the fuel supply operation is performed, and the broken line indicates the range in which the fuel supply cut operation is performed. Same figure (3
), when the brake is operated, etc., the engine rotational speed N is lower than the fuel cut rotational speed N2c, acceleration is performed once, fuel supply is resumed, and then when deceleration is applied, the fuel supply is resumed. A cutting operation is performed. This is because the fuel cut shock is reduced by braking during brake operation (continuous operation), so even if the fuel cut operation is performed at low rotation speeds, there will not be much adverse effect.
As shown in , if no brake operation is performed, N,
Below c, the fuel re-cut operation is prohibited to prevent the occurrence of rupture (19) due to fuel cut.

As described above, according to the present invention, the fuel supply re-cut operation is performed when the brake system is activated, and the re-cut operation is not performed when the brake system is not activated, so the fuel return rotational speed is set to a low value. However, the torque shock associated with the fuel cut operation does not occur so much, and the range of the fuel cut operation can be expanded, so the fuel consumption rate can be significantly reduced.

In addition to the above-described embodiments, the present invention also includes an engine that controls fuel injection by detecting the change-over state parameters of other engines;
In other words, it can also be applied to an engine that uses a carburetor to control the amount of fuel supplied.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is a block diagram of the control circuit in FIG. 1, and FIGS. 3 and 4 are flowcharts of part of the program for controlling the operation of the circuit in FIG. 2. , 5th
Figures (A) and (B) are explanatory diagrams of the operation of this embodiment. 18... Air flow sensor, (20) 20... Throttle valve, 26... Fuel injection valve,
30... Control circuit, 40.42... Crank angle sensor, 48... Throttle position switch, 52...
...Brake pedal, 54...Brake switch, 58...Vehicle speed sensor, 72...MPU
%74, , 76-Ilo circuit, 78-RAM. 80...ROM, 84...Gate circuit. Patent applicant Toyota Motor Corporation Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Akira Yamaguchi

Claims (1)

[Claims] 1. The engine rotational speed is between the first set value for cutting fuel supply and the second set value for restarting fuel supply, and the engine is again in a deceleration operating state. In a fuel supply control method in which a fuel supply cut operation is performed again at a time when a braking device of an engine is operating, it is detected whether or not a braking device of an engine is operating, and if it is operating, the fuel supply re-cut operation is performed; 1. A fuel supply control method for an internal combustion engine, characterized in that the fuel supply re-cutting operation cannot be performed if the fuel supply is not completed. 2. The fuel supply control method according to claim 1, wherein the fuel supply re-cutting operation is performed only once. 3. When the running speed of a vehicle equipped with the engine exceeds a predetermined value, the fuel supply re-cut operation is performed regardless of whether or not the braking device is operating. The fuel supply control method according to item 1 or 2. 4. Detection of whether the braking device of the engine is operating is to detect whether the braking device is operating continuously over time.Claims 1 and 2 The fuel supply control method according to item 1 or 3. 5. means for detecting the engine rotational speed, means for detecting that the engine is in a deceleration operating state, means for detecting whether or not the engine braking device is operating, and at least one intermittent operation. a fuel injection control means for supplying a fuel injection signal having a pulse width according to an operating state to the injector, and a first setting value at which the detected rotational speed causes a fuel supply cut and a fuel supply. and a second set value for restarting the fuel supply, when the means detects that the vehicle is in a deceleration driving state, and the means detects that the braking device is operating, the fuel supply cut signal is output. A fuel supply control device for an internal combustion engine, comprising: means for generating a fuel injection signal; and means for preventing transmission of the fuel injection signal to the injection valve in response to the fuel supply cut signal. 6. The fuel supply cut signal generating means also performs braking even when the detected rotational speed is between the first set value and the second set value and the means detects that the driving state is decelerated. A fuel supply control device (7) according to claim 5, wherein the fuel supply control device (7) generates a fuel supply cut signal when it is detected that the device is not operating; The fuel supply control device according to claim 5, wherein the fuel supply control device is means for detecting whether or not a brake pedal is energized.