JPS6155326A - Fuel injection quantity controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the occurrence of knocking, by altering the setting value in time of high load increment starting according to engine temperature. CONSTITUTION:There are provided with a device (b) detecting whether an engine (a) comes into a state of being high load or not and another device (c) increasing a fuel injection quantity up to the setting value at that point that the engine comes into a state of being high load. In addition, a device (d) detecting engine temperature is installed there and also a device (e) variably controlling the setting value according to the detected engine temperature is installed. Furthermore, a device (f) increasing the fuel injection quantity by degrees up to the specified increment value when the fuel injection quantity eceeds the setting value. With this constitution, knocking is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fuel injection amount control device for increasing the amount of fuel when an internal combustion engine is under high load.

BACKGROUND OF THE INVENTION Most current internal combustion engines increase the amount of fuel during high-load operation to control the air-fuel ratio to be rich (richer than the output air-fuel ratio), thereby suppressing the temperature rise of the exhaust gas flow. Particularly in turbocharged engines, it is necessary to significantly lower the exhaust temperature due to durability and other issues, so there is a tendency to increase the amount of exhaust gas and make the air-fuel ratio richer.

Naturally, when such a high load increase is performed, the fuel consumption rate worsens, but in order to improve this, the operating conditions for the high load increase are divided into areas, and from the time when the high load is reached, the fuel consumption rate is deteriorated. A technique is known in which the dose is increased after a delay time set for each
Publication No. 1241). This technology focuses on the fact that even when the load increases, there is some time leeway until the exhaust gas temperature rises.

However, according to the conventional technique for increasing the delay amount as described above, the following disadvantages occur.

(11) As the load becomes higher and the combustion chamber temperature rises, knocking becomes more likely, so it is undesirable from the viewpoint of engine durability that no increase is made at all during the delay.

(2) When the air-fuel ratio is in kana relief, the exhaust temperature rises quickly and the delay in increasing the amount of fuel can only be delayed for a very short time, so there is little effect on improving fuel efficiency.

(3) Since the chamber fuel ratio remains lean during the delay, sufficient output cannot be obtained and the acceleration feeling is poor.

In order to eliminate the above-mentioned inconvenience, the applicant has proposed that when a high load condition occurs, the amount of fuel is increased immediately without delay up to the output increase value that corresponds to the output air-fuel ratio, but when the output increase value is exceeded, the fuel amount is increased immediately under high load. Prior to the present application, a technique was proposed in which the amount of fuel is gradually increased until the fuel amount is increased to a certain amount.

Problem to be Solved by the Invention However, according to the above-mentioned prior art, since the fuel increase is delayed regardless of the engine temperature, when the engine temperature is high, the fuel amount is too small and knocking occurs immediately after the fuel increase starts. This caused problems with the durability of the engine. If sufficient fuel is supplied immediately after the start of fuel increase to prevent knocking even at high engine temperatures, the initial objective of improving fuel consumption rate, etc., will not be achieved at all.

Means for Solving the Problems First, regarding the configuration of the present invention to solve these problems.
To explain with reference to the drawings, the present invention includes means for detecting whether or not the engine a has entered a high load state, and means C for increasing the fuel injection amount to a set value when the engine a has entered the high load state; means d for detecting engine temperature; means e for variably controlling the set value according to the detected engine temperature; and means for gradually increasing the fuel injection amount to a predetermined increase value when the fuel injection amount exceeds the set value. It is characterized by comprising means f.

The fuel increase value (setting value) at the start of high load fuel increase is changed according to the engine temperature, so if the set value is increased when the engine temperature is high, the amount of fuel increased immediately after the high load fuel increase starts ( Therefore, a sufficient amount of fuel that does not cause non-king will be supplied immediately after the start of the high load increase.This will also shorten the delay time of the high load increase.

In addition, when the engine is at low temperature (at room temperature), the aforementioned set value is made equal to the output increase value, and the increase immediately after the start of high load increase is controlled to be close to the output increase value, and the delay time is lengthened (by which the air-fuel ratio By maintaining the air-fuel ratio near the output air-fuel ratio for as long as possible, it is possible to improve fuel efficiency and increase output.

Example The present invention will be explained in detail below with reference to Examples.

FIG. 2 schematically shows an electronically controlled fuel injection type internal combustion engine in which the engine load is determined from the intake air flow i1Q and the rotational speed N as an embodiment of the present invention. In the figure, numeral 10 is an air flow sensor of the above-mentioned type that is provided in the intake passage 12 and generates a voltage according to the intake air flow rate Q, and 14 is also provided in the intake passage 12 and generates a voltage according to the intake air temperature TIIA. This is an intake air temperature sensor. A throttle valve 16 that operates in conjunction with an accelerator pedal (not shown) is provided in the intake passage 12 downstream of the air flow sensor 10 and the intake temperature sensor 14, and a fuel injection valve 18 is provided in the intake manifold downstream of the throttle valve 16.

A cylinder block 20 of the engine is provided with a water temperature sensor 22 that generates a voltage according to a cooling water temperature TH-.

Detected voltages from the air flow sensor 10, intake temperature sensor 14, and water temperature sensor 22 are sent to a control circuit 24.

The distributor 26 is provided with a cylinder discrimination sensor 28 and a rotation angle sensor 30. Cylinder discrimination sensor 28
A pulse signal is output from the rotation angle sensor 30 at every predetermined angular position before the top dead center of the reference cylinder, for example, at 3606 crank angles, and a pulse signal is output from the rotation angle sensor 30 at every 30'' crank angle.These pulse signals is sent to the control circuit 24.

On the other hand, the control circuit 24 applies a drive pulse to the fuel injection valve 18, thereby causing the fuel injection valve 18 to
The pressurized fuel sent from a fuel supply system (not shown) is intermittently injected into the intake passage near the combustion chamber 34.

FIG. 3 shows the circuit configuration of the control circuit 24 shown in FIG. As is clear from the figure, the control panel circuit 24 includes a microcomputer, which includes a central processing unit (CPU) 40, a random access memory (RAM) 42, and a read only memory (RO).
M) 44, 1st and 2nd person power boats 46 and 48
, an output port 50, a clock generation circuit 52, and a bus 54 that interconnects these and transfers data.

Detection voltages from the air flow sensor 10, intake air temperature sensor 14, and water temperature sensor 22 are sequentially selected by a multiplexer 56, and then sent to an analog/digital (A/D) converter 58.
After being converted into a binary signal by
6 to the microcomputer.

The pulse signals from the cylinder discrimination sensor 28 and the rotation angle sensor 30 are waveform-shaped in the shaping circuit 60 and then applied to the microcomputer via the second output port 48 .

When an injection pulse signal is outputted from the microcomputer to the drive circuit 62 via the output port 50, this signal is converted into a drive pulse, and the fuel injection valve 18 is energized to perform fuel injection.

Next, an example of the operation of the microcomputer will be explained using the flowcharts shown in FIGS. 4 to 6.

FIG. 4 shows a routine for calculating the fuel injection pulse width τ, which is executed during the main routine.

First, in step 100, a high load increase value Kotp is calculated from N and Q/N. This calculation method is shown in FIG. 6 and will be described later. The input data representing the intake air amount Q is stored in a predetermined location in the RAM 420, together with the manual data representing the cooling water temperature T)IW and the intake air temperature T)IA, each time the conversion by the A/D converter 58 is completed. At this time, the intake air iQ/N per unit rotation corresponding to the engine load is calculated from the rotational speed N and the intake air flow rate Q and is stored in the RAM 42. Note that the rotation speed N is determined by a well-known method of measuring the time interval at which a pulse signal from the rotation angle sensor 30, that is, a pulse signal every 30 degrees of crank angle is applied.

In the next step 101, a set value Kpw of the high load increase value Kotp is calculated. This set value Kpw is the cooling water temperature TI
It changes depending on the IW, and the calculation method will be explained in detail later with reference to FIG. 11 or 12.

In the next step 102, the set value Kpiy obtained in step 101 is compared with the high load increase value Kotp, and Kot
If p is less than or equal to Kp- (Kotp≦Kpw), the process proceeds to step 103, where Kotp is directly used to calculate the injection pulse width without regulating Kotp using the upper limit G. That is, in this case, the high load increase will be performed immediately without any delay. The method of calculating τ in step 103 is to calculate the injection pulse width τ using the following equation using a correction coefficient β based on Q/N, Kotp, −cooling water temperature THW, etc., and other correction coefficients α.

(l+β+Kojinp) The calculated injection pulse width τ is temporarily stored in the RAI'142, and after being converted into an injection pulse signal by an injection control routine executed at each predetermined crank angle position, it is sent via the output port 50. and is output to the drive circuit 62.

In step 102, Kotp >Kp
If it is determined to be w, steps 104 to 108 are performed, and the upper limit G of the high load increase value Kotp is determined according to the rotational speed N. Steps 104 to 108 are for calculating the upper limit value G of the relationship as shown in FIG.

In the next step 109, the process routine shown in FIG.
A new upper limit value G is determined by the following formula from the count value Ctd that is incremented every m5ec and the upper limit value G determined in steps 403 to 407.

(provided that N is constant).

In the interrupt processing routine of 4m5ec in FIG. 5, steps 201 and 202 in which Ctd is incremented by
This is a step of regulating d to be less than "2000".

In step 110 of FIG. 4, the G calculated as described above is added to the high load increase value Kotp calculated in the previous routine to finally obtain the upper limit G. Next, in steps 111 and 112, processing is performed to regulate the high load increase value Kotp to be less than the upper limit value G determined as described above. The calculation in step 103 is performed using the Kotp regulated in this way.

As mentioned above, when Kotp exceeds Kpw, Kotp is regulated to be below the upper limit combustion G which gradually increases, so Kot gradually increases and the high load increase is delayed. Become. In addition, the upper limit value G is controlled according to the rotational speed N so that when N is large, G becomes large, so the increase rate at high loads changes as described above according to N, and the actual exhaust gas temperature It is possible to perform an optimal high load increase commensurate with the increase. In addition, if the high load increase value Kotp is less than the set value Kpw, the Ko
Since the amount is increased by the value of tp, the period during which the output air-fuel ratio is kept leaner than the output air-fuel ratio at room temperature becomes shorter, and an increase in output can be expected immediately after the load increases. Moreover, as explained later,
Since the set value Kpw changes according to the cooling water temperature THW, increasing when THW is high, the cooling water temperature T
If HW is high, a high load increase will be performed immediately without delaying to a larger Kotp. As a result, the occurrence of non-king can be reliably suppressed.

FIG. 6 shows in detail the processing contents of step 100 of the processing routine of FIG. In steps 300 to 304, a function TRD relating to N and Q/N as shown in FIG. 7 is determined. The interval number TRD represents the boundary of whether or not to perform a high load increase; if Q/N is TR0 or more, a high load increase is performed, and if Q/N is smaller, it is not performed. The next step 305 is to make this determination,
If Q/N<TRD, proceed to step 306 and
By setting p to Kotp=0.0, no increase is performed.

In the case of Q/N and kTRD, the process first proceeds to step 307 to obtain Kotp. This Kotp3 is the Kotpz according to the Q/N as shown in FIG. 9 and the above-mentioned TI? D, and is calculated from the following formula. Then Ste Nobu 308-311
Therefore, Kotpl of the relationship shown in FIG. 8 according to N
is required. Next, in step 313, the high load increase value Kotp is determined as Kotp = Kotp, X Ko
Determined from tpz. In this way, steps 307~
At step 313, a high load increase value Kotp is determined from N and Q/N according to the operating state at that time. In addition to the processing routine shown in Fig. 6, the method for calculating Kotp is
It may be determined directly from a two-dimensional table with N, or various other methods may be considered.

FIG. 11 shows an example of a method for calculating ρ- in step 101 of the processing routine of FIG.

First, in step 400, it is determined whether the cooling water temperature T)IW is 105° C. or lower. THW≦10
If the temperature is 5°C, it is determined that it is room temperature and the process proceeds to step 401.
Then, an increase value that corresponds to the output air-fuel ratio, which is 13% in this embodiment, is substituted into the set value. As a result, the fuel increase immediately after the start of a high load increase is controlled to be near the output increase value and the delay time is lengthened.As a result, the air-fuel ratio can be maintained near the output air-fuel ratio for as long as possible.This improves fuel efficiency at normal temperatures. , it is possible to increase the output.On the other hand, when THW > 105℃
If so, it is determined that the temperature is high and the process proceeds to step 402.K
If p&4 has a value much larger than the output increase value, for example, Kpw
Substitute =30%. As a result, the amount of fuel increases immediately after the start of the high load increase, and the air-fuel ratio becomes significantly richer immediately after the start of the increase, making it possible to prevent the occurrence of knocking.

FIG. 12 shows another example of a method for calculating Kpiv in step 101 of the processing routine of FIG.

In this example, if THW is 100°C or less, Kp is set to 13% in step 501, and if THW is 120°C or higher, Kpw is set to 30% in step 503, and 100
If °C<THW<120'C, step 504
Kpw is made equal to the linearly interpolated value of 13% and 30%. By controlling <Kpw as shown in FIG. 12, high load increase control can be performed with higher accuracy.

In the example described above, Kp- is changed in accordance with the cooling water temperature THW, but it may be changed in accordance with other parameters representing the engine temperature, such as oil temperature and cylinder block temperature.

Effects of the Invention Since the set value at the start of high load increase is changed according to the engine temperature, it is possible to prevent knocking when the engine is at high temperature, and also to improve fuel efficiency and increase output when the engine is at low temperature.

Since the air-fuel ratio becomes lean as the exhaust temperature rises, the air-fuel ratio can be controlled to the lean side for a longer period of time in view of this increase in exhaust temperature, which also leads to improved fuel efficiency.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the present invention, Figure 2 is a schematic diagram of an embodiment of the present invention, Figure 3 is a block diagram of the control circuit in Figure 2, and Figure 4 is a block diagram of the control circuit of Figure 2.
6 to 6 are flowcharts showing part of the microcomputer program of the control circuit in FIG. 3, FIG. 7 is a characteristic diagram showing the high load increase region, and FIG.
Figure 9 is the characteristic diagram of Q/NKotpz, Figure 10 is the characteristic diagram of Q/NKotpz.
The figure is a characteristic diagram of NG, and FIGS. 11 and 12 are flowcharts showing part of the program of the microcomputer of the control circuit of FIG. 3. DESCRIPTION OF SYMBOLS 10... Engineering/Afro-sensor, 14... Intake temperature sensor, Engineering 8... Fuel injection valve, 22... Water temperature sensor, 2
4... Control circuit, 28... Cylinder discrimination sensor, 3o.
...Rotation angle sensor.

Claims (1)

[Claims] 1. Means for detecting whether the engine is in a high load state, means for increasing the fuel injection amount to a set value when the engine becomes high load, and means for detecting the engine temperature. and means for variably controlling the set value in accordance with the detected engine temperature, and means for gradually increasing the fuel injection amount to a predetermined increase value when the fuel injection amount exceeds the set value. A fuel injection amount control device for an internal combustion engine. 2. The fuel injection amount control device according to claim 1, wherein the set value variable control means makes the set value larger when the engine temperature is high than when the engine temperature is low.