JPH01200034A - Fuel injection quantity control system for internal combustion engine - Google Patents

Abstract

PURPOSE:To always keep the air fuel ratio at a constant value by allowing one injection quantity obtained from the engine revolution speed and the intake pipe pressure to accord with the other injection quantity obtained from the intake pipe pressure and the throttle valve opening degree and obtaining the actual injection quantity on the basis of one injection quantity. CONSTITUTION:Combustion air is supplied into a plurality of combustion chambers El and Em of an internal combustion engine 13 from a plurality of suction valves Cl and Cm, and fuel is supplied from a plurality of fuel injection valves Bl and Bm. Each fuel injection valve Bl, Bm is controlled by a processing device 31 on the basis of the detection signals supplied from the detectors 19, 28, and 30 for detecting the intake pipe pressure, crank angle, and the opening degree of a throttle valve. In this case, the output of a valve opening degree detector 30 is corrected so that one injection quantity obtained from the intake pipe pressure and throttle valve opening degree accords with the other injection quantity obtained from the engine revolution speed and the intake pipe pressure. Then, the actual injection quantity is obtained on the basis of one injection quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for controlling the fuel injection amount of an internal combustion engine.

Conventional technologyIn the so-called electronically controlled fuel injection system between internal combustion engines, 1
In the conventional technique, which is a typical method for determining the fuel injection amount, the fuel injection amount is determined based on the rotational speed per unit time of the internal combustion engine and the intake pipe pressure. However, although this prior art has good stability, when the throttle valve opening changes suddenly, the intake pipe pressure detected by the pressure detector installed in the intake path does not correspond to the opening/closing operation of the throttle valve. Therefore, in order to accurately follow the opening and closing operations of the throttle valve to determine the fuel injection amount, it is necessary to At times, it was necessary to make complex corrections.

In order to solve this problem of the prior art, in a method previously proposed by the present applicant, the fuel injection amount is determined from the throttle valve opening and the rotational speed of the internal combustion engine. With this method, there is no response delay, and the fuel injection amount can be determined by accurately following the opening and closing operations of the throttle valve. However, with this method, errors due to manufacturing variations and matching of the valve opening detector that detects the throttle valve opening, or the throttle valve opening stored as a table,
An error occurs in the read fuel injection amount due to an error in the interpolation of the fuel injection amount data depending on the rotation speed, and it may not be possible to maintain the air-fuel ratio optimally. Further, when the throttle valve opening is small, the fuel injection amount changes greatly due to slight fluctuations in the throttle valve opening, resulting in poor stability.

Problems to be Solved by the Invention An object of the present invention is to provide an internal combustion engine that has good stability and transient response and is capable of determining an accurate fuel injection amount in response to opening and closing operations of a throttle valve. An object of the present invention is to provide a fuel injection amount control method.

Means for Solving the Problems The present invention calculates the injection amount TPI from the rotational speed Ne per unit time of the internal combustion engine and the intake pipe pressure Pm, and supplies combustion air to the internal combustion engine based on the intake pipe pressure Pm. determine the injection amount TP2 from the throttle valve opening θ and correct the output of the valve opening detector that detects the throttle valve opening θ so that the injection amount TP2 matches the injection amount TPI; This is a fuel injection amount control method for an internal combustion engine characterized by determining the actual fuel injection amount TAU in relation to the injection amount TP2.

Further, in the present invention, when the internal combustion engine is in a steady state with no acceleration or deceleration, the actual fuel injection amount TAU is: TAU=TP1+η(TP
This is a fuel injection amount control method for an internal combustion engine, characterized in that the injection amount TP2 is determined by 2-TP, 1), and the injection amount TP2 is set as the actual fuel injection amount TAU during the transition period when the acceleration/deceleration is performed.

Furthermore, in the present invention, during the steady state, the injection amount TP
This is a fuel injection amount control method for an internal combustion engine, characterized in that I is the actual fuel injection amount TAU, and during the transient period, the injection amount TP2 is the actual fuel injection amount TAU.

Further, the present invention sets the injection amount TP2 as the actual fuel injection amount TAU regardless of the acceleration/deceleration state of the internal combustion engine, and adjusts the output of the valve opening degree detector to bring the injection amount TP2 closer to the injection amount TPI. This is a fuel injection amount control method for an internal combustion engine characterized by not performing correction.

Furthermore, the present invention provides an output of the valve opening degree detector for making the injection amount TP2 an actual fuel injection amount TAU and bringing the injection amount TP2 closer to the injection amount TPI regardless of the acceleration/deceleration state of the internal combustion engine. This is a fuel injection amount control method for an internal combustion engine, which is characterized in that the correction is performed slowly.

According to the present invention, first, the injection amount T P'l is determined from the rotational speed Ne per unit time of the internal combustion engine and the intake pipe pressure Pro.
seek. This injection amount TPI has good stability, so immediately after the opening θ of the throttle valve that supplies combustion air to the internal combustion engine changes rapidly due to acceleration or deceleration, this injection amount TPI has good stability. TPI is equal to its value before the change and is stable.

Next, the injection amount TP2 is determined from the intake pipe pressure Pm and the throttle valve opening θ. This injection amount TP2 follows the change in the throttle valve opening θ, and therefore, this injection amount TP2 is determined at a relatively early stage of the transient state in which the throttle valve opening θ is rapidly changed as described above. It can correspond to the final value of the valve opening degree θ.

Further, the output of the valve opening detector that detects the throttle valve opening θ is corrected so that the injection amount TP2 matches the injection amount TPI, and therefore the output of the valve opening detector that detects the throttle valve opening θ is
The actual fuel injection amount TAU determined based on has good stability and responsiveness, and can accurately respond to changes in intake air and keep the air-fuel ratio constant.

Further, according to the present invention, when the internal combustion engine is in a steady state without acceleration or deceleration, where η is a coefficient for correcting the intake delay due to the air supply path between the throttle valve and the combustion chamber, TAU=TPl+η The actual fuel injection amount TAtJ is determined from (TP2-TPI). Further, during the transition period when the acceleration/deceleration is performed, the injection amount TP2 is changed to the actual fuel injection amount TAU.
Fuel injection is performed as follows. Therefore, fuel injection can be performed with high precision during steady state and with good responsiveness during transient state.

Furthermore, according to the present invention, fuel injection is performed by setting the injection amount TPI to the actual fuel injection JilTAU during the steady state, and setting the injection amount TP2 to the fuel injection amount TAU during the transient period. Therefore, good stability and transient response can be obtained without performing complicated arithmetic processing.

Further, according to the present invention, regardless of the state of the internal combustion engine,
Injection is performed with the injection amount TP2 as the actual fuel injection amount TAU, and in this case, the output of the valve opening detector is not corrected to bring the injection amount TP2 closer to the injection amount TPI, or correction is performed slowly. be exposed. Therefore, the configuration can be simplified, and it can have instantaneous transient response and improve stability.

Embodiment FIG. 1 is a block diagram of an embodiment of the present invention. A plurality of combustion chambers E1 to Ern are formed in the internal combustion engine 13,
Combustion air is supplied to these combustion chambers E1 to Em from an intake pipe 15. A throttle valve 16 is interposed in the intake pipe 15 . Combustion air via the throttle valve 16 is guided from the surge tank 14 to intake pipes A1 to Am provided individually for each combustion chamber E1 to Em. Each intake pipe A”
Fuel injection valves 81 to Bm are provided in the combustion chambers E1 to Em, respectively, and the fuel injection valves 81 to Bm perform injection at a fuel injection amount TAU determined by a processing device 31, which will be described later, in each explosion stroke in each combustion chamber E1 to Em. In each combustion chamber E1 to Em,
Intake valves 01 to Cm and exhaust valves D1 to Dm are provided, respectively. The internal combustion engine 13 includes, for example, spark plugs G1 to G.
The four thermosurge tanks 14 with m have an intake pipe pressure P
One pressure detector is provided to detect rn.

The intake pipe 15 is provided with a temperature detector 27 that detects intake air temperature. The internal combustion engine 13 is provided with a crank angle detector 28 for detecting the crank angle, and is also provided with a valve opening detector 30 for detecting the opening θ of the throttle valve 16. The temperature of the cooling water of the internal combustion engine 13 is detected by a temperature detector 24 . An oxygen concentration detector 21 is provided in the middle of the exhaust pipe 20, and the exhaust gas is purified by a three-way catalyst 22 and discharged to the outside.

A processing device 31 realized by a microcomputer or the like includes an input interface 32, an analog/digital converter 33 that converts an input analog signal into a digital signal, a processing circuit 34, and an output interface 35.
and a memory 36. Memory 36 includes read-only memory and random access memory. In the embodiment of the present invention, in response to outputs from the detectors 19, 24, 28, 30, etc., the fuel injection cap TAU for each stroke of fuel injected from the fuel injection valves 81 to Bm is controlled.

On the other hand, in the automobile manufacturer, the intake pipe pressure Pm at each rotation speed Ne of the internal combustion engine 13 as shown in FIG.
The relationship with the injection amount TPI is measured, and the measurement results are stored in the memory 36 as a map as shown in FIG.

Similarly, the relationship between the intake pipe pressure Pm and the intake air flow JtQ at each throttle valve opening θ as shown in FIG. The data on the injection amount TP2 is stored in the memory 36 as a map as shown in FIG.

Note that FIG. 4 shows the experimental results of the present inventor, in which line 11 is for the case where the throttle valve opening θ is 1.7'', line 12 is 5°, line 13 is 10°, and line 14 is 15°, line 15 is 20°,
Line 16 is 25°, line 17 is 30°, line 18 is 35'', line 19 is 40@, line flO is 45''), lie:ie 11
1j: 50°.

Now, when the throttle valve opening degree θ suddenly increases at time t1 as shown in FIG. 6(1), the intake pipe pressure Pm of the surge tank 14 detected by the pressure detector 19 is As shown in (2), it follows with a response delay. Therefore, as shown by the virtual line in Fig. 6 (3), the injection amount TPI determined using this intake pipe pressure Pm is equal to the value before the sudden change in the throttle valve opening θ immediately after the change. ,stable.

Further, the injection amount TP2 corresponding to the throttle valve opening degree θ changes as shown by the broken line in FIG. 6(3). This injection amount TP2 and the injection amount TP1 are shown at six times t1 to t2, which are equal to each other before time t1 and after time t2, in a steady state where the intake pipe pressure Pm corresponds to the throttle valve opening θ. For example, the transient state caused by
This is done using Pm or the like.

Therefore, when injection is performed with the injection amount TPI determined from the intake pipe pressure Pm, which changes relatively slowly with respect to changes in the throttle valve opening θ, the fluctuation is small and stable, but the intake pipe pressure Pm changes relatively slowly when the throttle valve opens. As the degree θ changes, there is a delay in response to the incoming intake air, and therefore, for example, as shown in FIG.
When the value suddenly increases, the air-fuel ratio becomes lean, resulting in poor transient response.

In addition, when fuel is injected using the injection amount TP2,
Although it has good transient response, as is clear from FIG. 4, when the throttle valve opening θ is small, the injection amount TP2 fluctuates greatly due to a slight change in the intake pipe pressure Pm. , poor stability.

Further, between the throttle valve opening θ detected by the valve opening detector 30 and the intake air actually flowing into the combustion chambers E1 to Ern, there is an intake pipe 15 located downstream of the throttle valve 16.
, the influence of the intake paths such as the surge tank 14 and the intake pipes A1 to Am causes a deviation, and for example, as shown in FIG. 6, when the throttle valve opening θ suddenly increases, the injection If injection is performed with the amount TP2, the air-fuel ratio will be in a rich state. Furthermore, the output of the valve opening detector 30 may differ from the actual throttle valve opening θ due to manufacturing variations or matching errors in the valve opening detector 30, or dirt adhering to the throttle valve 16, etc. may occur. Therefore, in this embodiment, the actual fuel injection amount TAU is determined as follows.
seek.

That is, the correction coefficient η for the intake delay of intake air into the combustion chambers A1 to Am due to the intake path consisting of the intake pipe 15 downstream of the throttle valve 16, the surge tank 14, and each intake pipe line A1 to Am was experimentally determined. Then, calculate the actual fuel injection amount TAU based on the formula below.

TAU=TP1+η(TP2-TPI)...(1
) The correction coefficient η for the intake delay is, for example, 0.7 to 0.
8, which varies depending on the vehicle type, and is stored in the memory 36 in the same way as the data shown in FIG. 3 and 5121 described above. The difference between the injection amount TP2 and the basic injection amount TPI corresponds to the theoretical change in the intake air flow rate in the transient state, and by multiplying this difference by the correction coefficient η, the influence of the intake path etc. can be reduced. It is possible to determine the injection amount corresponding to the change in the actual intake air flow rate.

By adding the injection amount determined in this way to the injection amount TPI and correcting the injection amount TPI, a fuel injection amount TAU that has good stability and transient response and takes into account the response delay of intake air can be determined. The air-fuel ratio can be kept constant.

Furthermore, as mentioned above, in the steady state, the injection amount TPI and the injection amount TP2 should be equal, so the injection amount T
The valve opening degree detector 3 is corrected by correcting the throttle valve opening degree θ so that P2 becomes equal to the injection amount TP1.

The accurate throttle valve opening degree θ can be obtained by absorbing detection errors due to manufacturing variations, matching errors, or dust adhesion to the throttle valve 16, etc.

FIG. 7 shows the operation for detecting the rotational speed Ne of the internal combustion engine 13, in which the rotational speed Ne detected by the crank angle detector 28 in step r+l is digitally converted and processed by the analog/digital converter 33. timesfi'g
34. This operation is performed every time the analog/digital converter 33 performs a conversion operation.

FIG. 8 shows the operation for determining the injection amount TPI, which is performed every time the intake pipe pressure Pro detected by one pressure detector is digitally converted by the analog/digital converter 33. In step nL1, the intake pipe pressure Pm detected by the pressure detection 819 is converted from analog to digital and read. In step n12, the basic injection amount TP1 corresponding to the rotational speed Ne obtained in step n1 and the intake pipe pressure Pm obtained in step nll is stored in the memory 3 based on the map shown in FIG. Read from

FIG. 9 shows the operation for determining the injection amount TP2, which is performed every time the throttle valve opening θ detected by the valve opening detector 30 is digitally converted by the analog/digital converter 33.

In step r121, the throttle valve opening θ detected by the valve opening detector 30 is converted from analog to digital and read. In step n22, step n21
The corrected throttle valve opening θH is obtained by adding the throttle valve opening θ obtained in the above and the correction value θG obtained as described above. In step n23, the rotation speed Ne obtained in step n1 and 5 steps nil are
The injection amount TP2 corresponding to the intake pipe pressure Pm obtained in step r122 and the corrected throttle valve opening θH obtained in step r122 is read out from the memory 36 based on the map shown in FIG. Ru.

FIG. 10 shows the actual fuel injection amount TAU in one embodiment of the present invention.
For example, 1 of the internal combustion engine 13
This is done for each step. In step n31, the injection amount TP2
The difference M between the injection amount TPI and the injection amount TPI is determined. step n32
Then, it is determined whether this difference M exceeds 0,
When this is the case, that is, during acceleration when the injection amount TP2, which has a fast response, is larger than the injection JiTP1, which has a slow response, the process moves to step n33. In step 1133, the product of the intake delay correction coefficient η and the absolute value IM+ of the difference M is added to the injection amount TPI, that is, the fuel injection JuTAU is determined according to the first equation described above, and the process moves to step n34. In step n32, when the difference M is less than O, that is, during deceleration, the process moves to step n35, and the injection amount TP
1, the absolute value I of the intake delay correction coefficient η and the difference M
The fuel injection amount TAU is obtained by subtracting the amount from MI,
The process moves to step r134. In step n34, step n33. The fuel injection valves B1 to Bm are driven to inject fuel in accordance with the fuel injection amount TAU determined in step n35.

FIG. 11 shows the updating operation of the correction value θG of the throttle valve opening θ, which is performed, for example, every 10 msec.

In step r141, it is determined whether the injection amount TP2 is larger than the injection amount TPI, and if so, 1 is subtracted from this correction value θG in step n42, and if not, 1 is subtracted from this correction value θG in step n43.
is added.

FIG. 12 shows the operation for determining the actual fuel injection amount TAU in another embodiment of the present invention, and this operation is similar to the operation shown in FIG. 10 described above, and corresponding parts are the same. Add a reference mark. In this example, step n 30
In this step, it is determined whether the internal combustion engine 13 is in an acceleration/deceleration state based on, for example, the time change rate of the intake pipe pressure Pro, and if so, that is, in an acceleration/deceleration state, the process moves to step ri31, and the steps n31 to n33 described above are performed. ．．
If the process like n35 is performed, or otherwise, that is, in a steady state, the process moves to step rI36, and the injection amount T
P2 is the actual fuel injection amount TAU.

Further, as still another embodiment of the present invention, in the steady state of the internal combustion engine 13, the injection amount TPI is changed to the actual fuel injection amount TAU.
The injection amount TP2 may be set to the actual fuel injection amount TAU during a transition period where acceleration or deceleration is performed. In this case, without performing arithmetic processing like the first equation above,
Good stability and transient response can be obtained.

Furthermore, in order to simplify the structure, regardless of the acceleration/deceleration state of the internal combustion engine 13, the injection amount TP2 is always set to the actual fuel injection amount TAU, and the throttle valve opening degree θ is corrected as shown in FIG. The action may be prevented, −
Alternatively, as shown in FIGS. 13 and 14, when the time rate of change Δθ of the throttle valve opening θ or the time rate of change ΔPm of the intake pipe pressure Pm changes greatly, the correction operation shown in FIG. The processing time required for this may be increased, that is, the processing operation may be performed slowly to provide instantaneous transient response and improve stability.

Effects of the Invention As described above, according to the present invention, the relatively stable injection amount TPI determined from the rotation speed Ne per unit time of the internal combustion engine and the intake pipe pressure Pm is determined by adjusting the intake pipe pressure Pm and the throttle valve opening. Injection amount TP with good response determined from degree θ
Since the output of the valve opening degree detector is corrected so that the values 2 and 2 match, and the actual fuel injection amount TAU is determined in relation to the injection amount TP2, good stability and transient response are achieved. Therefore, the air-fuel ratio can be kept constant even during a transient period in which the throttle valve opening degree θ is suddenly changed.

Also, so that the injection amount TP2 matches the injection amount TP1,
Since the output of the valve opening detector is corrected, errors caused by manufacturing variations and matching errors in the valve opening detector, or dust adhesion to the throttle valve can be absorbed, and the throttle valve opening can be corrected. The fuel injection amount determined from the degree θ is the air-fuel ratio. & can be set to a value.

Further, according to the present invention, the actual fuel injection amount TAU is determined based on the above-mentioned equation 1 during steady state, and is set to the injection amount TP2 during transient state, so that high precision during steady state and good response during transient state can be achieved. Fuel injection can be performed with

Furthermore, according to the present invention, the injection amount TPI is set to the actual fuel injection amount TA during steady state, and the injection amount TP2 is set to the actual fuel injection amount TA during transient state.
Since U is used, good stability and transient response can be obtained without performing complicated arithmetic processing.

Further, according to the present invention, the injection amount TP2 is set to the actual fuel injection amount TAU, and correction for bringing the injection amount TP2 closer to the injection amount TP1 is not performed or is performed slowly, thereby simplifying the configuration. In addition, it has instantaneous transient response and improves stability6.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, and Fig. 2 shows intake pipe pressure Pm and injection amount T at each rotation speed Ne of the internal combustion engine.
3 is a graph showing how the relationship shown in FIG. 2 is stored in the memory 36, and FIG. 4 is a graph showing the relationship between the intake pipe pressure P rn and the injection J at each throttle valve opening θ.
Graph showing the relationship with iTP2, No. 52 is a diagram showing how the relationship shown in No. 4I2I is stored in the memory 36, No. 6
11 is a waveform diagram for explaining the operation of the first embodiment, FIGS. 7 to 11 are flowcharts for explaining the operation of one embodiment of the present invention, and FIG. Flowcharts 1312I and 14 are graphs for explaining changes in processing time for correcting the throttle valve opening θ in still other embodiments of the present invention. 13... Internal combustion engine, 14... Surge tank, 15.
...Intake pipe, 16...Throttle valve, one...Pressure detector, 20...Exhaust pipe, 24.27...Temperature detector, 28...Crank angle detector, 30...・Valve opening detector, 31...processing device, B1-Brn...fuel injection valve, E1-Ern...combustion chamber, G1-Grn
...Spark plug agent Patent attorney Number of strokes Keiichi N2 diagram Figure 3 N5 diagram (rpm) Figure 4 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10
Figures and others f') To the spoon Figure 11 Figure 0 processing Figure 12 Figure 13 Figure 14 △Pm

Claims (5)

[Claims] (1) Determine the injection amount TP1 from the rotation speed Ne per unit time of the internal combustion engine and the intake pipe pressure Pm, and calculate the injection amount TP1 from the intake pipe pressure Pm and the opening degree θ of the throttle valve that supplies combustion air to the internal combustion engine. determine the injection amount TP2 from the above, correct the output of the valve opening detector that detects the throttle valve opening θ so that the injection amount TP2 matches the injection amount TP1, and calculate the injection amount TP2 in relation to the injection amount TP2. A fuel injection amount control method for an internal combustion engine characterized by determining an actual fuel injection amount TAU. (2) During steady state when the internal combustion engine is not accelerating or decelerating, the actual fuel injection amount TAU is determined by TAU=TP1+η(TP2-TP1), where η is the intake delay correction coefficient for the combustion chamber. 2. The fuel injection amount control method for an internal combustion engine according to claim 1, wherein the injection amount TP2 is set to the actual fuel injection amount TAU during a transition period in which the acceleration/deceleration is performed. (3) In the steady state, the injection amount TP1 is the actual fuel injection amount TAU, and in the transient period, the injection amount TP2 is the actual fuel injection amount TAU. fuel injection amount control method for internal combustion engines. (4) Regardless of the acceleration/deceleration state of the internal combustion engine, the injection amount TP2 is set as the actual fuel injection amount TAU, and the injection amount TP
2. The fuel injection amount control system for an internal combustion engine according to claim 1, wherein the output of the valve opening degree detector is not corrected in order to bring the amount of injection TP2 closer to the injection amount TP1. (5) Regardless of the acceleration/deceleration state of the internal combustion engine, the injection amount TP2 is set as the actual fuel injection amount TAU, and the injection amount TP
2. The fuel injection amount control method for an internal combustion engine according to claim 1, wherein the output of the valve opening detector is slowly corrected in order to bring the amount of injection TP2 closer to the injection amount TP1.