JPS61108847A - Control device of fuel increase in quantity in internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve exhaust emission by adjusting fuel increase in quantity according to the cooling water temperature in high load operation and increasing fuel increase in quantity according to passing time from the start of fuel increase in quantity and leading ignition timing according to the fuel increase in quantity. CONSTITUTION:A fuel injection amount arithmetic means A calculating fuel injection amount according to engine load and a fuel increase in quantity start timing setting means B outputting a timer drive signal for setting a fuel increase in quantity start timing when the engine load is over a predetermined value are provided. And an increase in quantity correcting means E correcting fuel increase in quantity read out from a fuel increase in quantity memory means C according to the cooling water temperature the longer is passing time from the fuel increase in quantity start time counted by a timer means D is provided. And an ignition timing lead angle correcting means H correcting the lead angle read out from a lead angle amount memory means F in correspondence with the fuel injection amount from the means E the more the long is the passing time, and adding it to a basic ignition timing by an ignition timing arithmetic means G is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel increase control device for an internal combustion engine, and in particular to an OTP (OTP) adopted to prevent an increase in exhaust temperature.
Over Temperature Protection
The present invention relates to a control device that controls the amount of fuel increase according to engine water temperature in fuel increase control called on) increase.

[Conventional technology]

Generally, the exhaust manifold, catalyst, 0□ sensor, etc. installed in the exhaust system of an internal combustion engine are heated to a high temperature under high load conditions such as high speed ranges and acceleration ranges, and the exhaust temperature reaches 850°C.
If the temperature exceeds this level, cracks in the exhaust manifold and deterioration of characteristics of the catalyst, 02 sensor, etc. will occur.

In order to prevent this, conventionally, when the load is high, the temperature of the exhaust system is lowered by increasing the amount of injected fuel and optimizing the air-fuel ratio.

[Problems to be solved by the invention] If the amount of injected fuel is simply increased during high load conditions, the amount of injected fuel will be increased unnecessarily even when the exhaust temperature is below 850°C, resulting in worsening fuel efficiency. Not only
There is a problem in that unnecessary exhaust gas containing HC and Co increases, resulting in poor emissions.

[Means for solving problems]

An object of the present invention has been made to solve the above-mentioned problems, and the purpose of the present invention is to reduce the amount of additional fuel when the engine cooling water temperature is low and reduce the amount of additional fuel when the engine cooling water temperature is high in a high load state of the internal combustion engine. The generation of emissions is suppressed as much as possible by increasing the amount of fuel, further increasing the fuel amount according to the elapsed time from the start of the fuel increase, and advancing the ignition timing according to the increase in fuel amount. An object of the present invention is to provide a fuel increase amount control device for an internal combustion engine.

The structure of the present invention for achieving the above object is shown in FIG. In FIG. 1, the fuel increase control device includes a fuel injection amount calculation means, a fuel increase start timing setting means, a timer means, a fuel increase storage means, a fuel increase correction means, a fuel injection control means, and an ignition timing. It includes a calculation means, an advance amount storage means, an ignition timing advance correction means, and an ignition timing control means.

The fuel injection amount calculation means calculates the fuel injection amount according to the load of the internal combustion engine.

The fuel increase start timing setting means outputs a timer drive signal for setting the fuel increase start timing when the load on the internal combustion engine is greater than a predetermined value.

The timer means starts and starts depending on the timer drive signal.
Count the elapsed time since the fuel increase start time.

The fuel increase storage means stores an increase in fuel amount corresponding to the engine cooling water temperature of the internal combustion engine, and in this case, the fuel increase amount corresponds to be smaller as the engine cooling water temperature is lower.

The fuel increase correction means further increases the amount of fuel read out from the fuel increase storage means in accordance with the engine cooling water temperature so that the amount increases as the elapsed time increases, and adjusts the fuel injection amount to
Add the corrected fuel increase amount.

The fuel injection control means controls fuel injection to the internal combustion engine based on the corrected fuel injection amount obtained according to the output of the fuel increase correction means.

The ignition timing calculation means calculates the basic ignition timing according to the load and rotational speed of the internal combustion engine.

The advance angle amount storage means stores an advance angle amount corresponding to the corrected fuel injection amount obtained according to the output of the fuel increase correction means, and in this case, the advance angle amount becomes smaller as the corrected fuel injection amount is smaller. It is being dealt with as if it were less.

The ignition timing advance correction means corrects the advance amount sequentially output from the advance amount storage means in response to the corrected fuel injection amount so that it increases as the elapsed time increases, and adjusts the advance amount to the basic ignition timing. Add the corrected advance angle amount.

The ignition timing control means controls the ignition timing of the internal combustion engine according to the output of the ignition timing advance correction means.

[For production]

Even if the internal combustion engine is under high load, the exhaust temperature will immediately drop to 85.
Since the high temperature does not reach 0° C., even if a high load state occurs, the amount of fuel is not increased to a certain level immediately, but is increased in accordance with the engine water temperature and the elapsed time of the high load state. As a result, fuel consumption can be saved, the generation of emissions can be reduced, and overheating of the exhaust system can be appropriately prevented. During the fuel increase period, when the engine cooling water temperature is low, the fuel increase is small, so the air-fuel ratio is leaner than with conventional fuel increase, but the ignition timing advance is corrected according to the fuel increase. Occurrence of knocking is prevented.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings from FIG. 2 onwards.

FIG. 2 schematically shows an example of an electronically controlled fuel injection type internal combustion engine as an embodiment of the present invention. (The same concept also holds true for carburetor fuel-supplied internal combustion engines.) In the figure, 10 represents the engine body, and 12
14 represents an intake passage, 14 represents a combustion chamber of one cylinder, and 16 represents an exhaust passage. Intake air taken in through an air cleaner (not shown) is connected to an air flow sensor 18.
The flow rate is detected by The intake air flow rate is controlled by a throttle valve 20 that is linked to an accelerator pedal (not shown). The intake air that has completely 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 a control circuit 30 via a line 28 from a fuel supply system (not shown). Pressurized fuel is intermittently injected into the intake passage 12 (intake port portion) near the intake valve 24.

In the combustion chamber 14, the exhaust gas after combustion is passed through the exhaust valve 3.
2 and the exhaust passage 16, and further via the three-way catalytic converter 34 to the atmosphere.

The air flow sensor 18 is provided in the intake passage 12 upstream of the throttle valve 20 and generates a voltage depending on the intake air flow rate. This output voltage is fed to the control circuit 30 via line 36.

A crank angle sensor 4 is installed in the distributor 38 of the engine.
0 and 42 are installed, and these sensors 40
, 42, the crankshaft is 30°.

After each 360° rotation, a pulse signal is generated, and these pulse signals are fed into the control circuit 30 via lines 44 and 46, respectively.

No. 8 is sent to the control circuit 30 via a line 50 from a throttle position switch 48 which is interlocked with the throttle valve 20 and closes when the throttle valve 20 is in the fully open position (idle position).

The exhaust passage I6 is provided with a 0□ sensor 52 that generates an output in response to the oxygen concentration in the exhaust gas, and the output voltage is sent to the control circuit 30 via a line 54.

The three-way catalytic converter 34 is provided downstream of the 02 sensor 52, and simultaneously purifies three harmful components, HC, CO, and NOx, in the exhaust gas.

A water temperature sensor 56 that detects the engine cooling water temperature and generates a voltage according to the temperature is attached to the cylinder block. The output voltage from this water temperature sensor 56 is sent to the control circuit 30 via line 58.

FIG. 3 is a block diagram showing an example of the configuration of the control circuit 30 shown in FIG.

Voltage signal from air flow sensor 18, 0□ sensor 52
and the voltage signal from the water temperature sensor 56 are fed into an analog-to-digital (A/D) converter 70 having an analog multiplexer function, which sequentially converts the 2 It is converted into a forward signal.

A pulse signal every 30' 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 (110 circuit) 74, thereby generating a binary signal representing the rotational speed of the engine. It is formed. Pulse signals for every 360 degrees of crank angle from the crank angle sensor 42 are sent to the same ■10 circuit 74, and
It is used to form an interrupt request signal, a fuel injection start signal, a cylinder discrimination signal, etc. for fuel injection pulse width calculation in cooperation with the above-mentioned pulse signal for each degree.

"l""o" from throttle position switch 48
The binary signal is similarly sent to a predetermined bit position of the 10 circuit 74 and temporarily stored.

A well-known fuel injection sensor circuit including a presettable down counter and a register is provided in the input/output circuit (110 circuit) 76, and the pulse width is determined from binary data regarding the injection pulse width sent from the MPU 72. form an ejection pulse signal with This injection pulse signal is sent sequentially or simultaneously to the fuel injection valves 26a to 26d via a drive circuit (not shown) to energize them.

As a result, the amount of fuel corresponding to the pulse width of the injection pulse signal is injected.

A/D converter 70. The I10 circuits 74 and 76 are connected to the main components of the microcomputer, such as an MPtl 72, a random access memory (RAM) 78, a read-only memory (ROM) 80, and a timer 81 via a common bus 82. Transfer of data and instructions, etc. is performed via the bus 82.

1? OM 80 Niha, main processing routine program, interrupt processing routine program for calculating fuel injection pulse width and ignition timing according to the present invention, interrupt processing routine program for calculating coefficients such as partial lean correction coefficient,
and other programs, as well as various data necessary for their arithmetic processing, are stored in advance. ROM
80, as shown in FIG. 5, the engine cooling water temperature THW and the fuel increase are set so that the lower the engine cooling water temperature THW, the smaller the fuel increase X, and the higher the engine cooling water temperature THW, the larger the fuel increase X. A table is stored in which the relationship with X is established in advance. In addition, ROM 80 has
As shown in Fig. 6, a relationship is established between the fuel injection pulse width τ and the advance amount B so that the greater the calculated fuel injection pulse width (injection time), the greater the advance amount B of the ignition timing. The attached table is stored.

As the control circuit 30, various configurations different from those described above can be applied. For example, without providing a speed signal forming circuit in the I10 circuit 74, the 1'1 PII 72 directly receives the pulse signal at each predetermined crank angle and forms the speed signal using software. Alternatively, without providing a fuel injection control device in the I10 circuit 76, the configuration may be such that a signal having a logical value of "I" is generated only for a time corresponding to the injection pulse width using software.

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

FIG. 4 is a flowchart showing a fuel injection time and ignition timing calculation control routine for explaining the operation of the control circuit 10 of FIG. Referring to FIG. 4, interrupt step 401 is started at every predetermined crank angle, eg, 360°A. In step 402, the air flow sensor 18
The intake air amount Q, the rotational speed N from the crank angle sensor 40, and the engine cooling water temperature THW from the water temperature sensor 56 are taken in.

Next, in step 403, basic ignition timing α is calculated from a two-dimensional map of rotational speed N and load Q/N, and in step 404, basic injection is calculated from load Q/N. Next, in step 405, the fuel injection time τ becomes τ=τ.・CPL
'Calculated by CFII・C0+τ9. however,
ro is the basic injection quantity, CPL is the partial lean correction coefficient, C0 is the feedback correction coefficient, C0 is the other correction coefficient determined by calculating the injection quantity with the injection time, engine cooling water temperature 1"HW, etc., and τ9 is invalid. This is the injection time.Next, in step 406, it is determined whether the flag FL is "1" or not.Furthermore, the flag FL (="l") indicates that the engine was in a high load state in the previous calculation cycle. Here, if it is assumed that the engine was in a low load state during the previous calculation cycle, the flow of step 406 proceeds to step 407.In step 407, the negative of the engine,
It is determined whether the load is larger than a predetermined value. This determination is
For example, this is performed based on the ratio Q/H of intake air IJQ and rotational speed N.

Normally, if the intake air amount Q is 140 m/hour or more, it is determined that the vehicle is in a high load state. Here again, if the engine is in a low load state, the process proceeds to step 408, where the fuel injection time τ is preset in the presettable down counter in the I10 circuit 76 (FIG. 3), and as a result, the time τ An amount of fuel corresponding to the amount of fuel will be sent into the combustion chamber of the engine body 1. Next, in step 409, the ignition timing α is set to I
10 is set in another presettable down counter in circuit 76. The routine then ends at step 410.

Next, when the engine load changes from low load to high load,
The flow from step 407 to step 408 described above switches to the flow from step 407 to step 411. In step 411, a flag FL is set to indicate a high load state, and the process proceeds to step 412. In step 412, the table in the ROM 80 is searched for the fuel increase X corresponding to the engine cooling water temperature THW taken in in step 402, and in step 413, the read fuel increase X is stored in a predetermined area in the RAM 78 as the increase A. Store. Next, in step 414, timer 81 is started. As described above, the relationship between the fuel amount increase X and the engine cooling water temperature is such that the fuel amount increase X increases as the engine cooling water temperature increases. This is based on the consideration that when the engine cooling water temperature is relatively low, the exhaust temperature does not rise rapidly even under high load conditions, and therefore only a small amount of fuel is required.

In the next calculation cycle, flag FL="1", so the flow at step 406 proceeds to step 415. In step 415, similarly to step 407, the load state of the engine is determined. If the engine is maintained in a high load state, the count value of the timer 81, that is, the elapsed time T from step 414, is determined in step 416.
Read. Then, in step 417, step 40
Therefore, the corrected fuel injection time not only depends on the fuel increase A corresponding to the engine coolant temperature THW, but also because the elapsed time T7 is long. As you can see, the number of cases is increasing. The reason why the fuel injection time is made to depend on the elapsed time Tn in this way is that even when the engine enters a high load state, the exhaust temperature does not rise immediately, and the amount of fuel is increased for a short time after the engine enters a high load state. This is to keep it to a minimum.

After step 417, in step 418, the ignition timing advance angle IB corresponding to the corrected fuel injection time τ calculated in step 417 is searched from another table in the ROM 80, and the read advance angle amount B, The elapsed time T7 read in step 416 and step 403B not only depend on the corrected fuel injection time τ, but also on the elapsed time Tfi.
It also depends on. The purpose of the above calculation in step 419 is as follows. In other words, when the engine is under high load, the more fuel there is, the richer the air-fuel ratio becomes.
As shown in Fig. 6, the longer the fuel injection time τ, the greater the advance angle B.
needs to be made larger. Further, as the elapsed time T from the time the engine entered the high load state becomes longer, the fuel increase amount increases, so it is necessary to increase the advance angle amount as the elapsed time T7 becomes longer.

The corrected fuel injection time τ and the corrected advance angle amount α calculated in steps 417 and 419 are set in the registers in the I10 circuit 76 in steps 408 and 409, respectively, and then, in step 410, this routine is ended.

In this way, when the flow passes through step 417 and the fuel amount is increased, and when the flow passes through step 419 and the ignition timing advance timing is controlled, from then on, as long as the high load state is maintained, Fuel increases will continue. However, if it is determined at step 415 that the engine is in a low load state, step 415 to step 41
The flow to Step 6 switches from Step 415 to Step 420, and as a result, the flag FL is cleared and the fuel increase is stopped, and in Step 421, the timer 8
1 will be reset.

In the above-described embodiment, the intake air amount Q and the rotational speed N are used as the engine load determination parameters, but other operating state parameters such as the throttle valve opening degree or the basic injection amount τ. may be used as a load discrimination parameter. Also,
The fuel increase correction was performed by lengthening the fuel injection time τ according to the engine cooling water temperature and the elapsed time of the high load state, but it may also be performed by other means such as providing another fuel injection valve.

〔Effect of the invention〕

As explained above, according to the present invention, even in a high load state, the fuel increase correction is changed according to the engine cooling water temperature and the elapsed time of the high load state, so that overheating can be prevented. It is possible to simultaneously improve fuel efficiency and reduce deterioration of emissions. Furthermore, since the advance timing of the ignition timing is changed according to the amount of injected fuel and the elapsed time of the high load state, the fuel is appropriately ignited according to the air-fuel ratio.

[Brief explanation of the drawing]

FIG. 1 is an overall block diagram for explaining the present invention in detail, FIG. 2 is an overall schematic diagram showing an embodiment of the control device for an internal combustion engine according to the present invention, and FIG. 3 is the control circuit of FIG. 2. 10, FIG. 4 is a flowchart for explaining the operation of the control circuit 10 shown in FIG. 2, FIG. 5 is a graph showing the relationship between engine cooling water temperature and fuel increase, and FIG. It is a graph which shows the relationship between injection time and the amount of advance of ignition timing. 102FA main body ts: air flow sensor, 30:
Control circuit, 40, 42: Crank angle sensor, 56
:Water temperature sensor.

Claims (1)

[Scope of Claims] 1. Fuel injection amount calculation means for calculating the fuel injection amount according to the load of the internal combustion engine, and a timer drive signal for setting the fuel increase start timing when the load of the internal combustion engine is larger than a predetermined value. a timer means that starts in response to the timer drive signal and counts the elapsed time from the fuel increase start time; and a timer means that starts in response to the timer drive signal and counts the elapsed time from the fuel increase start time; and stores an amount of fuel increase corresponding to the engine cooling water temperature of the internal combustion engine. In this case, the fuel increase storage means is arranged so that the lower the engine cooling water temperature, the smaller the fuel increase amount, and the fuel increase amount read out from the fuel increase storage means in accordance with the engine cooling water temperature. further increases the amount as the elapsed time increases, and adds the corrected fuel increase amount to the fuel injection amount; correction obtained according to the output of the fuel increase correction means; a fuel injection control means for controlling fuel injection to the internal combustion engine based on the fuel injection amount determined by the internal combustion engine; an ignition timing calculation means for calculating a basic ignition timing according to the load and rotational speed of the internal combustion engine; and a fuel increase correction means. An advance angle corresponding to a corrected fuel injection amount obtained according to the output is stored, and in this case, the advance angle is made to correspond to a smaller value as the corrected fuel injection amount is smaller. ignition amount storage means, correcting the advance amount read from the advance amount storage means in accordance with the corrected fuel injection amount so that it increases as the elapsed time increases; An ignition timing advance correction means for adding the corrected advance amount; and an ignition timing control means for controlling the ignition timing of the internal combustion engine according to the output of the ignition timing advance correction means. A fuel increase control device for an internal combustion engine.