JPS6293473A - Detecting device for internal pressure of intake pipe in internal combustion engine - Google Patents

Abstract

PURPOSE:To compensate a fuel adhering rate or the like, by correcting a value in this time by a correction amount, in which a differential amount between sample values of intake pipe internal pressure in this time and the time before the preceding time is multiplied by a correction coefficient, while decreasing said correction coefficient for a predetermined period immediately after starting. CONSTITUTION:A control circuit 12, inputting an intake pipe internal pressure, crank angle signal, etc. from sensors 5-8, calculates an engine speed by TDC timing to be stored in a RAM 19 with a sample value of intake pipe internal pressure. Next, a CPU 13, multiplying a difference between the sample value in this time of the intake pipe internal pressure and the sample value in the time before the preceding time by a correction coefficient, obtains a correction amount to be added to the value in this time, performing its correction, and a fuel injection time is calculated by the engine speed or the like. Here the correction coefficient is decreased for a period from after starting to a time after a predetermined period. In this way, a large fuel adhering rate in a low temperature in the vicinity of a combustion chamber after starting or a small fuel vaporizing rate can be compensated.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operating state control device for an internal combustion engine, and more particularly to a detection device for detecting engine intake pipe internal pressure included in such a device. In a device that controls the operating state of an internal combustion engine by controlling the fuel supply to the internal combustion engine or the amount of intake air, the internal pressure of the intake pipe downstream of the throttle valve, the engine speed, etc. The so-called engine parameters of the engine are detected to obtain electrical signals representing each engine parameter. On the other hand, in order to control the operating state more quickly and accurately, a so-called microcomputer is often used. According to a predetermined operation program stored in advance in the storage means, for example, the engine 17)
Top Dead Center) The CPU performs arithmetic operations in synchronization with the timing.
In synchronization with the operation, engine parameters such as the C intake pipe internal pressure signal are sampled to obtain sample values, which are stored in the storage means and read out to perform calculation operations, and the fuel injection valve is opened according to the calculation results. The engine operating condition is adjusted by adjusting the valve time, etc. However, the operating state of an internal combustion engine changes from moment to moment, and the intake pipe internal pressure is an especially important parameter, and it is not easy to detect this using only a single sample value and control the operating state accurately. do not have. Therefore, among the ripple values of the intake pipe internal pressure, the current value is corrected by the sample value before the previous value, and the oil cylinder is corrected by 1.

One possible method is to predict or determine the actual intake pipe internal pressure. However, if the mode of the correction equation in such a prediction method is fixed regardless of the engine condition, the prediction result by the correction fftHX may not be appropriate to use especially for fuel supply amount control depending on the engine operating condition. occurs and there is 1. [115l] Accordingly, an object of the present invention is to provide an intake pipe internal pressure detecting device that contributes to accurate engine operating state control, particularly fuel supply amount control, in accordance with changes in engine operating state. In the intake pipe internal pressure detection device according to the present invention, the current value is selected from among the sample values obtained by sampling the analog signal representing the intake pipe internal pressure at a timing synchronized with the engine rotation speed, for example, TDC timing. The difference between the current value and the number value before the previous value will be corrected by adding a correction valve obtained by multiplying the correction coefficient, and the correction coefficient will be decreased after a predetermined period of time after the engine starts. There is. Missing-1-1 Hereinafter, examples will be described in detail with reference to the accompanying drawings. FIG. 1 shows a fuel injection type internal combustion engine including an intake pipe internal pressure detecting device according to the present invention, 1 is an air filter, and intake air that has passed through this filter 1 passes through an intake pipe 2 to an engine 3. The amount of air is regulated by a throttle valve 4 provided in the intake pipe 2. 5 is a potentiometer, for example, which measures the opening degree (θTH) of the throttle valve 4.
); 6 is the absolute pressure PB downstream of the throttle valve 4 in the intake pipe 2;
7 is a cooling water temperature sensor that generates an output voltage at a level corresponding to the cooling water temperature of the engine 3; 8 is a crankshaft (not shown) of the engine 3; A crank angle sensor generates a pulse signal (TDC signal) when the rotation angle is at top dead center (TDC), 9 is an exhaust pipe, and 10 is a three-way catalyst. Reference numeral 11 denotes an injector, which is installed in the intake pipe 2 near the intake valve (not shown) of the engine 3, and is designed to supply the carrot 3 with fuel according to the input pulse time. The respective output voltages of the throttle opening sensor 5, the intake absolute pressure sensor 6, the cold pressure sensor 7, and the crank angle sensor 8 are input to the control circuit 12. The control circuit 12 includes, for example, a microprocessor or a microcomputer, and controls the basic fuel injection time Ti and the basic fuel injection time Ti by multiplying it by an increase or decrease correction coefficient in accordance with a predetermined program to be described later. A calculation process for the fuel injection time T011+ corresponding to the obtained increased fuel injection period is performed. FIG. 2 is a block diagram showing a specific configuration of the control circuit 12. In FIG. 2, the control circuit 12 has a CPU (central processing circuit) 13 that starts digital calculations in accordance with a program to be described later. An input/output bus 14 is connected to the CPU 13, and the CPU 1
A data signal or an address signal is input/output to/from 3. The input/output bus 14 includes an A/D converter 15.
, MPX (multiplexer) 16, counter 17, R
An OM (read only memory) 18, one RAM (random access memory), and a drive circuit 20 for the injector 11 are connected to each. MPX16 is a switch that selectively relays and supplies any one of the output signals of sensors 5 to 7 to the A/D converter 15 via the level conversion circuit 21 in accordance with the command from CP (J13). The /D converter 15 converts the supplied analog signal and digital data in synchronization with the TDC pulse.The counter 17 measures the generation cycle of the TDC signal of the crank angle sensor 8 supplied via the waveform shaping circuit 22. It is well known that the output pulse of the crank angle sensor 8 is synchronized with the engine rotation, and the engine rotation speed Ne can be obtained based on this output pulse. In this program, first, engine rotational speed data N e (N) obtained based on the T[)C signal is calculated (step S+). Note that there are various methods to obtain N e (N), such as a method in which a voltage representing the engine speed is obtained by resetting the integrating circuit with a pulse synchronized with the engine speed, and this is sampled. Are known. The sample value data N e (N) of the engine speed thus obtained and the sample value data P, A(N) of the intake pipe internal pressure PBA obtained via the A/D converter 15 are stored in a predetermined area of the RAM 190 (step 82 ). Next, using the previously memorized previous value PBA (N-1), the value P8A (N-2), the value PBA (N-3), etc., which have already been stored, the current value (N) is corrected. A cylinder is performed (step S3). This predicted oil cylinder will be described later with reference to FIG. p , , -y When the sub-operation is completed,
Increase coefficient after startup K, temperature correction coefficient □8, atmospheric pressure S
T Correction coefficient K PA-02 feedback correction coefficient K. 2
Calculate various correction coefficients such as (step S4),
, then sample value data θ of throttle opening θTH
□, , (N) are fetched and stored in the RAM 19 (step Ss). Then, N e (N) and step S3
Based on the predicted PBA, the basic value T of the opening time of the injection valve 11 is determined by a predetermined calculation formula or by performing a map search.
1 (step Sg >. Obtained basic value Ti
The final injection time TO is calculated by multiplying by the above correction coefficient.
In step S7), the valve opening command is sent to the drive circuit 20.
step $8), thereby ejector 1
1 opens the valve. FIG. 4 shows the subroutine program for the P8Ay measurement calculation by the CPU 13 described above. First, the change detection sample number interval m+, m2 (m, <m2)
For example, set them to 2 and 3 (Step 5IO)
The current values P, A (old) and the guard value PGD are compared (step 511). If PBA(N) is greater than PGD, the prediction calculation is not performed as PBA=PBA(N) (step 511). 512).If PBA(N) is less than or equal to PGD, compare the maximum correction coefficient KA8□ after startup with the reference value KASTR1 (step 813).
When KJ stiffness is small, it is determined that the initial period is in progress, and the predicted oil cylinder is not performed as the operation of step S12, that is, PBA-PBA(N). This is because during a predetermined period after the start of operation, the PBA is in an unstable state in which it decreases as the engine speed increases, and if the prediction calculation predicts a smaller PB during this period, it will actually cause the engine to deteriorate. This is because it increases instability, which is undesirable. K ≧K Narutogi judges that the predetermined period of ^ST ASTRl has ended after starting, and sets the throttle opening data θ□,,(N) and the idle reference opening θ10.
The engine rotation data N e (N) is compared with the idle determination value NA (step 514). Now, if θ(N)≦θTO and Ne(N)<NA and H, then the change in P ΔP8A= P8A(N)
-PA BA(N-1111) and step S+s>, ΔP,
By comparing the absolute value of ΔPr with the reference value ΔPr, it is determined whether the engine is in a transient operating state (step 516). When the absolute value of ΔPBA is smaller than the reference value ΔP, the change in PBA is sufficiently small, so it is determined that the engine is in a nearly steady operating state, and Pi is not predicted and PBA(N) is set (step 512 ). As long as the absolute value of ΔPBA is greater than ΔP, the correction coefficient φ is set to φ0 (step $17), and then ΔPBA and the guard value ΔP6□. (step 818), ΔP
If BA exceeds ΔPGHO, ΔP = ΔPGHO (step 519). B^ However, when the value of ΔPBA is negative, it is natural that ΔPGHO is also negative. Next, the throttle opening data θ,,(N) is 01. or if the engine rotational speed data N e (N) exceeds NA, N e (N) is compared with the high speed determination value N71 (step S?o). When Ne(N) exceeds zi, the engine is in high speed mode and performs predictive calculations f P
BA=P BA(N) and Le(step S+z),
When Ne (N) is 71 or less, the engine speed is in the medium speed range, and ΔP8A = PBA (N) - P8
A(N-'r#2) (step 521). As mentioned above, m2 is, for example, 3. Δ obtained in this way
The absolute value of P8A is compared with the reference value ΔP (step 322), and if 1ΔPBA1≧ΔPr, it is determined whether PBA is positive or negative (step 523). If PBA is zero or positive under engine acceleration, φ=φ] (step 524), compare ΔP with the guard value PGI+1, step SA δ), ΔP ≧ΔP GH1<r Raba ΔP, 8-to PG
H1A then step S), ΔP <ΔP CG1 then B
A Proceed to the next step. In addition, if ΔPBA is negative, such as under engine deceleration, φ−φL
(step 527), ΔPBA and guard value ΔP6
[Compare with 1 (step 528). ΔP is ΔP
In the following cases, change ΔPBA to ΔP6,1 BA
GLI is made equal (step 829), and when it is greater than ΔPB^ΔPGL1, O>ΔPBA>ΔPGL1, and ΔP
Leave the value of BA unchanged and proceed to the next step. -l 1 - The prediction calculation of PBA using φ and ΔP thus obtained and AI is P8. = P BA (N) 4-φ・ΔPBA
(Step 53)). Obtained P
, Ae final guard value PPRD (step 53
1), if PBA≧PPRD, set PBA=PPRO; step S32); if PBA<PPRD, the process ends directly. In the above calculation, when predicting and correcting the current values P and A(N), the current value P8. (N) and the value P (N-
2) is used, and in the medium speed rotation B^ area, the current value PBA (N) and the previous 44 times value PBA (
The difference from G.3) is defined as ΔPBA. If anything, T
If the correction period is fixedly synchronized with the DC synchronization sampling period, the fluctuation period of the actual PBA will not change much even when the engine speed increases, so when the engine speed increases, the fluctuation period of the PBA will change. As a result, the correction period becomes too short, and the fluctuation of PBA is predicted too much, and the predicted "BA" greatly exceeds the next P, A (N + 1), and in the next prediction calculation, the PBAe is once again predicted to be smaller. A phenomenon like this occurs, and the predicted P becomes the actual PB
This is because it includes extra fluctuations compared to the fluctuations of A. In other words, when the engine speed increases and the time interval between TDC pulses becomes smaller, the interval for taking the sample values of PBA, which is the basis for predicting 1] B^, is calculated in terms of TDC number. For wide variations in actual PBA, predictive calculations are performed using sample values P8A(N) that occur at approximately constant time intervals despite variations in engine speed. FIG. 5 shows a subroutine program for calculating the correction coefficients φ, φ, and φ1° used in the prediction calculation routine described above. In this subroutine, first, it is determined whether the initialization condition that it is immediately after starting (cranking) is satisfied (step 840), and if the initialization condition is satisfied, φ-φ, φ-φ □2, φ1°−02tl −φ, 2 is initialized (step $41). In addition, φo
2, φ□2, φ, 2 is, for example, 6.0.6.0.4
．． It is 5. If the initialization condition is not satisfied after the start (cranking) state is completed, tit, φ11 and φ□
1 (step 542), and if φI≦φH1, φ is directly set to φ1 (step S43). Here, φ□1 is assumed to be 2.0, for example. φ11〉
If φH1, determine whether the discrimination parameter φ is O or not (step 544), and if φ−〇, count value Cφ
= CTWn (step 545), CTHl is C, edge 0, CT depending on the engine temperature T, as shown below.
The value of kl, CT, or 42 is preset by another routine program. Next, φ is set to 1 (step 84G), and the value of φ□ is maintained as it is. Next, in the case of φ-1, Cφ
Determine whether Cφ is zero (step 547), and if Cφ is not zero, set it as Cφ−1 (step 548);
φ□ is maintained as it is. (Step 543). If Cφ=0, it means that the down-count is finished, and φ-0 is set (step Sa), and Δ11 is subtracted from φ11 to obtain a new φ1 (step Ss). Through the above calculations from step 42 to step S, φ1 changes as shown by the stepped solid line in FIG. 6 according to the TDC number, and reaches φ111 from φ2. ]12 Similarly, steps S52 to S6 are performed for φL and φD.
The calculation is performed by o and S62 to S7o, and finally φ becomes φ,1, and φ. is φ. Set to 1. Note that φ, 1, φ. For example, the value of 1 is 1.5 and 3.
．． Leave it at 0. In the end, the relationships are set as φ0>φ] and >φ[. By doing this, P and A at idle
? While ensuring 1m positive response, PB in the medium speed range
When correcting the increase side of
This is to compensate in advance for the response delay of the control system during the reduction side correction, the fuel evaporation edge in the intake system, etc. Also, φ. By gradually decreasing the values of , φ1, and φ from immediately after the engine starts, the PBA, which has a low fuel adhesion rate and low fuel vaporization rate due to the low temperature near the combustion chamber immediately after engine startup, is increased. The aim is to obtain sufficient fuel supply by making predictions. FIG. 7 is a subroutine program for calculating the post-start increase coefficient KA8□. That is, first, it is determined that the engine has just been cranked by detecting a change in the starter switch from on to off (step 58o). If the engine has just been cranked,
Set the value of parameter CA8□. is obtained from the CAsAs-bull stored in a predetermined storage area according to (step 5
81). An example of the CAS□ table is shown in the graph of FIG. In addition, CA8□. For example, the value of C^8.4 is 1゜7.1.5, 1.3.1.2.1.15
It is. In this way, when C is found, K-CA8,・AST
Find K as 8STK. (Step 582). Next, the slope switching values K and K are calculated using the following formula (Step 583). That is, K.A.
STRO-(KAST "RASTO+'
K = (K -1)R, □1+1ASTR1
AST where R and R are constants, for example ASTOAST1 0.5 and 0.3. On the other hand, in the next cycle immediately after cranking, the engine temperature (cooling water temperature) ■, 4 and the extremely low temperature discrimination value TWDP
Step 584) TI4 is the king. , compare K and K when they are smaller ^ST
85TIIO (step 585), and if KAs□ is greater than KAs□RO, set ΔKA8□-D KSTO (step 886). If K is smaller than K, compare the magnitude of KASTASTllo and K (step 5AST
ASTRl 87), if K is a person than K, then KAS1
'RAST ＾5TIt1 >K >K, and ΔKAS□−DKAS
Set TO68th block to S block old 1 (Step S). K <K na8
8 AST ASTRl RabaΔK
AST-KAS1'R2 (step S8°). Engine temperature TW is king. Togis of 91 and above are KA8□ and K.
Comparing the size with ASTRo (step 59o), K
When AST>KASTRO (ΔKAST −DKA
STl and "AST≦K ASTRO's throat is ΔKAS
T-RI^ST2 (step 589). Using ΔK thus obtained, a new KAST A8□ is obtained as KAST-ΔKAs■ (step 591). Now, DKAS□. 〉
D>D, and T<T, AS of IDP
Tl ni ^ST2
In the case of W, the change in KA8□ is as shown by the solid line in Figure 9, and when T ≧T, the change in KA8□ is as shown by the solid line in Figure 9.
1 DP Looks like the dashed line. KAS□ thus obtained is compared with 1 (step $92), and when KAST<1, KAST=1 is set (step 593), and when KA8□≧1, the process ends directly. As is clear from FIG. 9, the period 5TRI during which KAS□ reaches K from its initial value immediately after cranking is regarded as the predetermined period after the engine is started. In addition, in order to know the predetermined period after starting the engine, an independent variable K is prepared and it is changed from immediately after engine cranking to T.
Subtract (down count) a predetermined value for each DC pulse,
When the variable K reaches a predetermined reference value, the predetermined period after startup may end. 1 inch pull 3LJ As is clear from the above, the intake pipe internal pressure detection device according to the present invention obtains the result by multiplying the difference between the current value and the previous sample value among the sample values of the intake pipe internal pressure signal by a correction coefficient. The corrected current value obtained by adding the corrected correction valve to the current value is set as the intake pipe internal pressure, and the correction coefficient is decreased by J5 within a predetermined period of time after the engine is started. This is preferable for use in a fuel supply control device because it can compensate for a large fuel deposition rate or a small fuel evaporation rate that occurs at low temperatures near the engine combustion chamber during a predetermined period of time.

[Brief explanation of drawings]

1 and 2 are block diagrams showing an operating state control device for an internal combustion engine including an intake pipe internal pressure detection device according to the present invention, and FIG. 3 is a block diagram showing the operating state control device equipment shown in FIGS. 1 and 2. FIG. 4 and FIG. 5 are flowcharts showing the operation program of the intake pipe internal pressure detection device according to the present invention, and FIG. 7 is a flowchart showing a correction coefficient calculation program used in the program shown in the flowchart of FIG. 6, and FIG. 8 is a graph showing the variation of the correction coefficient obtained by the program shown in FIG. 7. FIG. 9 is a graph showing how the correction coefficient obtained by the program shown in FIG. 7 changes. Explanation of symbols of main parts 1... Intake filter 2... Intake pipe 4... Throttle valve 5... Throttle opening sensor 6...・Intake absolute pressure sensor 7... Cooling water temperature sensor 8... Crank angle sensor 9... Exhaust pipe 10... Three-way catalyst

Claims (3)

[Claims] (1) a pressure detector that generates an intake pipe internal pressure signal representing the intake pipe internal pressure downstream of the throttle valve of the internal combustion engine; a rotational speed detection means that generates an engine rotational speed signal representing the engine rotational speed of the internal combustion engine; sampling means for obtaining an intake pipe internal pressure sample value by sampling the intake pipe internal pressure signal in synchronization with the engine speed of the internal combustion engine; storage means for sequentially storing the sample values; a correction means that adds a correction amount obtained by multiplying the difference from the sample value by a predetermined correction coefficient to the current sample value to correct the current sample value to obtain a correction value, and converts the correction value into the intake pipe internal pressure. The intake pipe internal pressure detection device includes a post-start detection means for detecting after the start of the internal combustion engine, and the correction means sets the correction coefficient to an initial value according to an output of the post-start detection means, An intake pipe internal pressure detection device characterized in that the initial value is gradually decreased within a predetermined period after startup. (2) The intake pipe internal pressure detection device according to claim 1, wherein the correction means reduces the correction coefficient at a reduction rate determined depending on engine temperature. (3) The intake pipe internal pressure detection device according to claim 1, wherein the correction means determines the initial value and subsequent correction coefficients according to engine operating conditions.