JP2615569B2 - Fuel injection amount control device for internal combustion engine - Google Patents

Description

Description: Object of the Invention [Industrial application field] The present invention relates to a fuel injection amount control device for an internal combustion engine, in particular, by detecting the intake air amount of the internal combustion engine by a moving vane type air flow meter. The present invention relates to a fuel injection amount control device for an internal combustion engine that calculates a fuel injection amount.

2. Description of the Related Art Conventionally, there has been provided a fuel injection amount control device that improves an operating state of an internal combustion engine by supplying an optimal amount of fuel to the internal combustion engine.

As one of the fuel injection amount control devices, for example, as shown in JP-A-59-170432, the measurement member is displaced by the intake air of the engine, and the displacement amount is converted into an electric signal to thereby obtain the intake air. Some include a moving vane type air flow meter for detecting the amount. This type of fuel injection amount control device calculates a basic injection amount according to the load state of the internal combustion engine, which obtains the intake air amount detected by the air flow meter as one parameter, and adds the basic injection amount to the operating state of the internal combustion engine. Make various corrections according to
The fuel injection amount is controlled.

[Problems to be Solved by the Invention] However, the above-described conventional fuel injection amount control device has the following problems and is not yet satisfactory.

That is, when the driver is idling, the accelerator pedal is
When a so-called tip-in operation of returning by / 8 steps or 1 to 2 seconds is performed, an overshoot occurs in the output of the air flow meter due to inertia of the moving vane. Then, the fuel injection amount supplied to the internal combustion engine is not the actual intake air amount, but is eventually increased by the output signal from the overshooted air flow meter, and the fuel is excessively supplied accordingly.
There has been a problem that the air-fuel ratio becomes temporarily overrich, and as a result, idle stability is reduced.

The present invention has been made in view of the above problems, and in a fuel injection amount control device for an internal combustion engine using a moving vane type air flow meter, even if a tip-in operation is performed, good idle stability is achieved. It is an object of the present invention to provide a fuel injection amount control device for an internal combustion engine.

Configuration of the Invention [Means for Solving the Problems] To achieve the above object, the following configuration is adopted as means for solving the problems of the present invention. That is, according to the present invention, as shown in the basic configuration diagram of FIG. 1, an air flow meter M2 for detecting the intake air amount of the internal combustion engine M1 by a moving vane method, and an intake air amount Q detected by the air flow meter M2 Based on the load Q / NE calculated from the
A fuel injection amount calculating device M3 for calculating a fuel injection amount to be supplied to the internal combustion engine M1. When the throttle valve is opened during the idling operation, the throttle valve is opened. The degree of opening is equal to or less than a predetermined opening degree and a predetermined time has not elapsed after the opening. Excessive fuel prevention that prevents the fuel injection amount calculated by the fuel injection amount calculation means M3 from becoming excessive when it is determined that the predetermined time has not elapsed after the opening is made to the opening degree or less. The gist of the present invention is a fuel injection amount control device for an internal combustion engine, characterized by comprising means M5 and M5.

Here, the fuel injection amount calculating means M3 is an air flow meter M2.
The intake air amount detected at
The fuel injection amount to be supplied to the internal combustion engine M1 is calculated.In general, a basic fuel injection amount is calculated according to a load Q / NE of the internal combustion engine M1 obtained from the intake air amount Q and the rotation speed NE. The means for correcting the basic fuel injection amount with various correction coefficients to calculate the fuel injection amount corresponds to this means.

Excessive fuel prevention means M5 is the fuel injection when the determination means M4 determines that the predetermined time has not elapsed after the throttle valve was opened to a predetermined opening or less during idling operation. This is to prevent the fuel injection amount calculated by the amount calculation means M3 from becoming excessive. As the excess fuel prevention means M5, for example, an upper limit is set to the basic fuel injection amount calculated by the fuel injection amount calculation means M3, or the execution of the increase correction of the basic fuel injection amount during the high load operation state is prohibited. You may comprise. Further, an upper limit may be provided for the actual fuel injection amount calculated by performing various corrections on the basic fuel injection amount.

[Operation] In the fuel injection amount control device for an internal combustion engine of the present invention configured as described above, the determination means M4 determines that the throttle valve is opened to a predetermined opening or less during idling operation and the predetermined time after opening. While it is determined that has not elapsed, the excess fuel prevention means M5 operates to prevent the fuel injection amount calculation means M3 from calculating an excessive fuel injection amount. As a result, it is possible to prevent the air-fuel ratio from temporarily becoming over-rich due to the overshoot of the air flow meter M2.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing an internal combustion engine equipped with a fuel injection amount control device according to an embodiment of the present invention and peripheral devices thereof.

As shown, a vehicle equipped with the fuel injection amount control device of the present embodiment includes an internal combustion engine 1 and an automatic transmission 3 coupled to an output shaft 2 of the internal combustion engine 1 and transmitting engine output to driving wheels (not shown). In addition, the engine control device 5 controls the fuel injection amount and the ignition timing of the internal combustion engine 1 to control its output torque, and the automatic transmission control device 7 controls the shift of the automatic transmission 3.

As shown in the figure, an internal combustion engine 1 draws air from the atmosphere, mixes fuel and air injected from a fuel injection valve 8 and guides the mixture to an intake port 9, and an electric spark formed in a spark plug 12. The combustion chamber 15 is configured to take out the energy of the combustion of the air-fuel mixture ignited as a rotational motion through a piston 14 and an exhaust system 18 that discharges the gas through a gas exhaust port 17 after combustion.

The intake system 10 includes, from the upstream, an air flow meter 21 for detecting the intake air amount Q, a throttle valve 23 for controlling the intake air amount, and a surge tank 25 for smoothing the pulsating flow of the intake air. The intake air amount Q is controlled by the opening degree of a throttle valve 23 linked to an accelerator pedal (not shown), and a moving vane 27 built in the air flow meter 21 is provided.
Is detected by the displacement of Further, the intake system 10 has a built-in idle switch which is turned on when the throttle valve 23 is fully opened, and a throttle sensor 30 for detecting the opening degree of the throttle valve 23, and an intake air temperature sensor 31 for detecting the temperature of the intake air. Is provided.

Air taken in through the intake system 10 and the fuel injection valve 8
The air-fuel mixture with the injected fuel is drawn into the combustion chamber 15 and ignited after being compressed by the piston 14, and the air-fuel mixture is ignited by an electric spark formed in the ignition plug 12. A spark plug 12 provided in each cylinder of the internal combustion engine 1 is connected to an output shaft 2 by a high pressure cord (not shown).
The igniter 33 is connected to a distributor 35 that distributes the high voltage generated in the igniter 33 in synchronization with the rotation of the igniter 33. In the distributor 35, a cylinder discriminating sensor 36 for generating one pulse for one rotation of the output shaft 2 and a rotation speed sensor 37 for generating one pulse every 30 degrees of the output shaft 2 are provided.

It is ignited by spark ignition and burns explosively, piston 14
The air-fuel mixture whose pressure has been lowered is then discharged as exhaust gas. This exhaust system 18 includes an oxygen concentration sensor (hereinafter referred to as an O ₂ sensor) 38 that detects the air-fuel ratio of the air-fuel mixture based on the composition of the exhaust gas. Is provided.

The cylinder block 39 of the internal combustion engine 1 is cooled by circulating cooling water, and the temperature THW of the cooling water is detected by a cooling water temperature sensor 41.

Further, a key switch 43 for starting the internal combustion engine 1 and a starter motor 44 are provided.

The output signals of the above-described sensors for detecting the operation state of the internal combustion engine are input to the engine control device 5, and control of the fuel injection valve 8, the igniter 33, and the like is performed according to the operation state of the internal combustion engine 1.

Next, the automatic transmission 3 is provided with a vehicle speed sensor 47 for detecting a vehicle speed V based on the rotation speed of the output shaft 45 and a shift position sensor 49 for detecting a shift position SP of the automatic transmission 3. The automatic transmission 3 transmits a control signal from the automatic transmission control device 7 to a transmission solenoid valve.
Shift control is performed by receiving signals from the lock-up solenoid valves 53 and 52, and the control of the shift mechanism and the automatic shift control device is well known, and therefore the description thereof is omitted.

Next, the configuration of the engine control device 5 will be described with reference to the block diagram of FIG.

As shown in FIG. 3, the engine control unit 5 inputs and calculates data in accordance with a control program, and also performs a central processing unit (hereinafter simply referred to as a CPU) 60 for performing processing for controlling operation of various devices. A read-only memory (hereinafter simply referred to as a ROM) 61 for storing a control program and initial data, and a random access memory (hereinafter simply referred to as a ROM) for temporarily reading and writing data input to the engine control device 5 and data necessary for arithmetic control. A backup random access memory (hereinafter simply referred to as a backup RAM) as a non-volatile memory backed up by a battery so as to retain data necessary for the subsequent operation of the internal combustion engine even when the key switch 21 is turned off and the key switch 21 is turned off. ) 63 mainly. Further, the internal combustion engine 1 is supplied via buffers 64, 65, 66, a multiplexer 67, and an A / D converter 68, or via buffers 69, 70.
, A cooling water temperature sensor 41, an intake air temperature sensor 31, and a vehicle speed sensor 4 provided in the automatic transmission 3.
7, The output signal from the shift position sensor 49 is sent to the CPU 60, and the multiplexer 67 and the A / D converter 68 from the CPU 60.
, An oxygen concentration sensor 38, a cylinder discriminating sensor 36, and a rotation speed sensor 37 via an input / output port 71 for outputting a control signal of the same, a buffer 72, a converter 73, or a shaping circuit 74 for shaping a waveform, or directly. Output signals from the key switch 43 and the throttle sensor 30 to the CPU 60
And an input / output boat 75 that sends the data to the input / output boat 75. Drive circuits 77, 7 for driving the fuel injection valve 8 and the igniter 33
8 also has output ports 79 and 80 for outputting signals from the CPU 60. The components of the engine control device 5 described above are connected to each other by a bus line 81 serving as a signal and data path.

Although not shown in FIG. 3, the engine control device 5 is also connected to the automatic transmission control device 7 via an input / output port 75, so that data can be transferred between the two. I have.

Next, a process related to the fuel injection amount control executed by the engine control device 5 will be described.

FIG. 4 is a flowchart showing a fuel injection time TAU determination routine executed by the engine control device 5, FIG. 5 is a flowchart showing a chip-in detection routine corresponding to a subroutine of the fuel injection time TAU determination routine,
It is.

When the process is started as shown in FIG.
100 is executed, the air flow meter 21 and the rotation speed sensor 3
Based on the output of 7, the rotational speed NE of the internal combustion engine 1 and the intake air amount Q are calculated.

Subsequently, in step 110, the load Q / NE is calculated from the operation information of the two basic internal combustion engines 1, and then the basic fuel injection amount (basic fuel injection time) which is the optimum fuel supply amount for the load. TP is calculated by the calculation formula in ROM61.

In the following step 120, the processing of the chip-in detection routine is executed. The chip-in detection routine detects a chip-in state of a vehicle from detection signals of various sensors provided in the internal combustion engine. When the chip-in state is detected, a value of 1 is set to a chip-in flag FT. ing. More specifically, the processing shown in the flowchart of FIG. 5 corresponds to the chip-in detection routine, and is executed from step 130 of FIG. 5 after execution of step 110 of FIG.

In step 130, it is determined whether or not an idle switch built in the throttle sensor 30 is in an ON state. If “YES” in step 130, that is, if it is determined to be in the ON state,
The process proceeds to step 132. In step 132, the idle flag FIDL indicating that the idle switch is on
Is set to 1 and the value 0 is set to the chip-in flag FT in the following step 134. After the processing of step 134, the processing moves to “RETURN”, and this routine ends once. On the other hand, if “NO” is determined in step 130, the process proceeds to step 136. In step 136, it is determined whether or not the above-mentioned idle flag FIDL has the value 1. If "YES" in step 136, that is, if FIDL = 1,
The process proceeds to step 138. In step 138, it is determined whether or not an injector counter CINJ indicating the number of fuel injections since the time when the idle switch was turned off is smaller than a predetermined value A. "YES" in step 138, that is, CINJ
If the determination is <A, the process proceeds to step 140, and it is determined from the output signal of the shift position sensor 49 whether the automatic transmission 3 is not in the neutral range. If “YES” in step 140, that is, if it is determined that the engine is not in the neutral range, the process proceeds to step 142, in which the cooling water temperature THW detected by the cooling water temperature sensor 41 is greater than a predetermined value, in this embodiment, 60 ° C. Is determined. Step 142
If "YES", that is, if it is determined that THW> 60 ° C., the process proceeds to step 144, where the rotational speed NE of the internal combustion engine 1 detected by the rotational speed sensor 37 is smaller than a predetermined value, 700 rpm in this embodiment. Is determined. "YES" in step 144, that is,
If it is determined that NE <700 rpm, the process proceeds to step 148, where the throttle opening TA detected by the throttle sensor 30 is detected.
Is smaller than a predetermined value, in this embodiment, 20 °.

If “YES” is determined in step 148, that is, if TA <20 °, the process proceeds to step 150. At step 150, the value 1 is set to the chip-in flag FT, and at step 152, the injector counter CINJ is incremented by one. After that, the processing shifts to “RETURN”, and this routine ends once.

On the other hand, if “NO” is determined in each of the determination processes from step 136 to step 148, the process proceeds to step 154. In step 154, the value 0 is set in the chip-in flag FT. In the following step 156, the value 0 is set in the idle flag FIDL. In the following step 158, the injector counter CINJ is cleared to 0. Thereafter, the process proceeds to “RETUTN”, and this routine ends once. That is,
In the above-described chip-in detection routine, the automatic transmission 3 is not in the neutral state, the cooling water temperature THW is higher than 60 ° C, the rotation speed NE is lower than 700 rpm, and the vehicle speed SPD is 10 km for a predetermined time after exiting the idle state. / h and the throttle opening TA is smaller than 20 °, the tip-in flag FT indicates that the vehicle is in the tip-in state.
Is set to the value 1.

After the end of the chip-in detection routine, the process proceeds to step 160 in FIG.

In step 160, the rotational speed NE captured in step 100
And the load Q / NE calculated using the intake air amount Q is a predetermined value B
It is determined whether it is greater than. In step 160, "YE
S ”, that is, when it is determined that Q / NE ≧ B, the next step 170
The processing moves to. In step 170, it is determined whether or not the chip-in flag FT has a value of 0, and "YES", that is, FT = 0
If so, the process proceeds to step 180. In step 180, the value 0.2 is set to the high load correction coefficient FTOP for increasing and correcting the basic fuel injection amount TP during the high load operation of the internal combustion engine 1. On the other hand, if “NO” is determined in step 160 or if “NO” is determined in step 170, the process proceeds to step 190, where the above-described high-load correction coefficient F
TOP is set to the value 0. After performing the processing of step 180 or step 190, the processing moves to step 200.

In step 200, the correction coefficient F during the high-load operation described above is used.
A correction coefficient K for the basic fuel injection amount TP other than TOP is calculated. The correction coefficient K is determined based on information from various sensors. For example, various corrections such as a correction coefficient learned from the previous operating state of the internal combustion engine 1 and an air-fuel ratio feedback correction coefficient based on the output of the oxygen concentration sensor 38 are provided. It is calculated as the sum of the values. In the following step 210, the actual fuel injection amount (fuel injection time) TAU to be actually executed using the high load correction coefficient FTOP and the correction coefficient K obtained as described above is calculated using the following equation. is there.

TAU = TP × (FTOP + 1) × K + TAUV Here, TAUV indicates a voltage correction injection time for correcting a change in the response time of the injector due to the battery voltage. In the following step 220, the actual fuel injection time TAU obtained in this way is stored in the RAM 62, and the processing of this routine ends.

The actual fuel injection time T stored in the RAM 62 in this manner
The AU is appropriately read in another fuel injection execution routine, and the internal combustion engine 1 is operated by injecting a fuel amount from the fuel injection valve 8 into the internal combustion engine 1 for a time corresponding to the actual fuel injection time TAU. The Rukoto.

That is, the above-described fuel injection time TAU determination routine executes the increase correction of the basic fuel injection amount TP when the load Q / NE of the internal combustion engine 1 is equal to or more than the predetermined value B and the vehicle is not in the chip-in state. Even if the NE is equal to or larger than the predetermined value B, the above-described increase correction is not executed when the vehicle is in the chip-in state. Therefore, as shown in the graph of FIG. 6, which shows the relationship between the actual fuel injection time TAU and the rotation speed of the internal combustion engine 1,
When the throttle opening TA changes to a trapezoidal shape due to the tip-in operation of the accelerator pedal, the load Q / NE based on the intake air amount detected by the air flow meter 21 greatly changes in a protruding manner, and conventionally, the actual fuel injection time TAU is reduced. Where the amount is greatly increased as shown by the dotted line in the figure, the increase is limited as shown in the figure. As a result, the air-fuel ratio does not become over-rich, and the rotational speed NE of the internal combustion engine 1 is stabilized as shown in FIG. The one-dot broken line in the figure shows the engine speed NE in the case where the conventional increase restriction is not performed. Conventionally, the engine speed NE has been greatly disturbed, and idling has been unstable.

Therefore, according to the fuel injection amount control device for an internal combustion engine of the present embodiment, the rotation of the internal combustion engine 1 is stabilized as described above, and as a result, the idle stability is improved.

In the above embodiment, the present invention is applied to the running range of a vehicle equipped with an automatic transmission. The present invention is applied to the running range of an automatic transmission in which a tip-in operation is frequently performed with a load applied to the internal combustion engine. The invention is particularly effective. The present invention can be applied to a manual transmission vehicle instead of the above embodiment.

Further, in the above embodiment, when the tip-in state is detected, execution of the correction of the basic fuel injection amount TP based on the high load correction coefficient FTOP is prohibited, but instead of the above embodiment, for example, When the chip-in state is detected,
A determination may be made as to whether the basic fuel injection amount TP detected at 110 is greater than a predetermined value, and if the basic fuel injection amount TP is equal to or greater than the predetermined value, the basic fuel injection amount TP may be limited by the predetermined value. Also,
For example, at the time of detecting the chip-in state, it is determined whether the actual fuel injection amount TAU calculated in step 210 is larger than a predetermined value.
The TAU may be limited.

As mentioned above, although one Example of this invention was described in full detail, this invention is not limited to the said Example at all, and can be various aspects in the range which does not deviate from the summary of this invention.

Effects of the Invention In the fuel injection amount control device for an internal combustion engine of the present invention described in detail above, when the throttle valve is opened to a predetermined opening or less during idling operation, the throttle valve is opened until a predetermined time elapses after the opening. During this time, measures such as upper limit guard for the basic fuel injection amount or the actual fuel injection amount and prohibition of increase correction during high-load operation are performed so that the fuel injection amount does not become an excessive value.

As a result, the air-fuel ratio does not become over-rich due to the influence of the overshoot of the air flow meter, and the idle stability can be improved.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a schematic configuration diagram showing an internal combustion engine equipped with a fuel injection amount control device according to one embodiment of the present invention, and peripheral devices thereof, and FIG. FIG. 4 is a block diagram of an engine control device which is a component of the embodiment;
5 to 5 are flowcharts showing a control process executed by the engine control device, and FIG. 6 is an explanatory diagram for explaining a control process executed by the engine control device. DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Automatic transmission 5 ... Engine control device 8 ... Fuel injection valve 21 ... Air flow meter 37 ... Rotation speed sensor 41 ... Cooling water temperature sensor 47 ... Vehicle speed sensor 49 ... Shift position Sensor

Claims (1)

(57) [Claims] An air flow meter for detecting an amount of intake air of an internal combustion engine by a moving vane method, and a load calculated from at least the amount of intake air detected by the air flow meter and an engine speed. And a fuel injection amount calculating means for calculating a fuel injection amount to be supplied to the engine. When the throttle valve is opened during an idle operation, the opening of the throttle valve is opened by a predetermined amount. And a determining means for determining whether or not a predetermined time has not elapsed after the opening, and the determining means determines that the throttle valve is opened to a predetermined opening or less during idle operation. If it is determined that the predetermined time has not elapsed after the fuel injection, the fuel injection amount calculated by the fuel injection amount calculating means is prevented from being excessive. A fuel injection amount control device for an internal combustion engine, comprising: a fuel prevention unit;