JPH0394134A - Intake pressure detecting device for internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress the detection response delay by predicting and setting the variation quantity of intake pressure in the pressure propagation time corresponding to length of a piping, in the case on intake pressure sensor is connected to an intake passage through the piping, and correcting a detection value of the intake pressure. CONSTITUTION:In the case an intake pressure sensor 9 is allowed to communicate and connected to an intake passage through a piping 9a, the variation quantity of intake pressure in the propagation time of pressure corresponding to length of the piping 9a for allowing the sensor 9 and an intake manihold 5 to communicate and connecting them is predicted and set in a control unit 11. Also, by correcting a detection value of the intake pressure, based on this detection delay prediction quantity, the generation of a detection response delay of the sensor 9 can be suppressed even if the piping 9a becomes long and the propagation time of the pressure becomes long.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an intake pressure detection device for an internal combustion engine, and more specifically, a response delay due to the length of piping that communicates and connects an intake passage of an internal combustion engine with an intake pressure sensor. The present invention relates to a device capable of correcting.

Conventional technology> An electronic control device for an internal combustion engine is equipped with a sensor that detects the intake pressure PB, and based on the intake pressure PB detected by the intake pressure sensor and the engine rotation speed detected by a crank angle sensor, etc. A device that controls the fuel supply to an engine by setting the fuel supply amount is generally known as the D-JETRO system (see Japanese Patent Laid-Open No. 58-150040, etc.).

Problems to be Solved by the Invention> By the way, when providing the intake pressure sensor as described above,
The intake pressure sensor is integrally provided on a board constituting a control unit installed in a vehicle interior, etc., and piping is extended from the intake manifold of the internal combustion engine to guide the intake pressure to the sensor on the control unit. In some cases, the sensor may be configured to simplify sensor installation and wiring. In this case, the intake pressure propagates through the piping at approximately the speed of sound and is detected by the sensor, so if the piping is short, the response delay is negligible and no special measures are required. When the piping is extended into the vehicle interior, the length thereof reaches, for example, 2 to 4 m, and the propagation time due to the length of the piping may impair the detection response of the sensor.

The propagation time is 5.9 ms when the speed of sound is approximately 340 m/s, so for example, when the pipe length l is 2 m.
Furthermore, when the pipe length 2 is 3.4 m, a propagation time of 10 ms is required.As shown in Figure 6, the longer the pipe, the greater the response delay when the intake pressure changes. Therefore, when the piping length l is set long, it is necessary to take some measure against response delay in order to ensure transient detection performance.

The present invention has been made in view of the above problems, and when a sensor for detecting intake pressure is communicated with an intake passage through a relatively long pipe, it is possible to compensate for the response delay due to the propagation time in the pipe. The purpose is to provide a detection device.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. 1, the intake throttle valve is connected to the intake passage downstream of the intake throttle valve via piping and outputs a detection signal corresponding to the intake pressure of the engine. an intake pressure detection means, a change rate calculation means for calculating a change rate in a predetermined unit time of a detection signal output from the intake pressure detection means, and a pressure propagation time determined by the length of the piping and the change rate based on the change rate. a detection delay error amount setting means for predicting and setting a detection delay error amount, and correcting the detection signal by the intake pressure detection means based on the detection delay error amount predicted and set by the detection delay error amount setting means; Including a delay correction means that uses the result as the final detected value! The intake pressure detection device for engine A was constructed.

<Operation> In this structure, the intake pressure detection means is connected to the intake passage on the downstream side of the intake throttle valve via piping, and outputs a detection signal corresponding to the intake pressure of the engine. The change rate calculation means calculates the change rate of the detection signal in a predetermined unit time, and the detection delay error amount setting means calculates the change rate of the detection signal based on the change rate and the pressure propagation time determined by the length of the piping. A detection delay error amount corresponding to a change in detection delay due to propagation in the piping is predicted and set.

The delay correction means corrects the detection signal by the intake pressure detection means based on the detection delay error amount, and uses the correction result as the final detection signal.

<Example> Examples of the present invention will be described below.

In FIG. 2 showing the system configuration of one embodiment, air is taken into an internal combustion engine 1 via an air cleaner 2, intake ducts 1 and 3, a throttle chamber 4, and an intake manifold 5. The air cleaner 2 has an intake air (atmospheric) temperature TA.
An intake air temperature sensor 6 is provided to detect ("C).The throttle chamber 4 includes a throttle valve (intake throttle valve) 7 that variably controls the opening area of the throttle chamber 4 in conjunction with an accelerator pedal (not shown). is provided to control the intake air flow rate Q.

The throttle valve 7 has a potentiometer for detecting the TVO and a fully closed position (idle position).
A throttle sensor 8 including an idle switch 8A that is turned ON is attached.

The intake manifold 5 downstream of the throttle valve 7 is provided with an intake pressure sensor 9, which serves as an intake pressure detection means for detecting the intake pressure PB, and is connected to the intake manifold 5 through a pipe 9a. A valve 10 is provided.

The fuel injection valve 10 is driven to open by a drive pulse signal output from a control unit 1 having a built-in microcomputer, which will be described later, in synchronization with engine rotation, and is fed under pressure from a fuel pump (not shown) to a predetermined level by a pressure leg rake. Pressure-controlled fuel is injected and supplied into the intake manifold 5. That is, fuel injection valve 1
The amount of fuel supplied at 0 is controlled by the valve opening driving time of the fuel injection valve 10.

Furthermore, a water temperature sensor 12 is provided to detect the cooling water temperature Tw in the cooling jacket of the engine 1, and the exhaust passage 1
An oxygen sensor 14 is provided within the engine 3 to detect the air-fuel ratio of the intake air-fuel mixture by detecting the oxygen concentration in the exhaust gas.

The control unit 11 counts the crank unit angle signal POS every 1° or every 2° outputted from the crank angle sensor 15 for a certain period of time, or the crank reference angle signal REF( In the case of a four-cylinder engine, the engine rotational speed N is detected by measuring one circumference (every 180 degrees).

The control unit 11 calculates the basic fuel injection amount TpPB based on the intake pressure PB detected by the intake pressure sensor 9, and also calculates the basic fuel injection amount TpPB.
The final fuel injection amount Ti is calculated by applying various corrections to PB according to the engine operating state, and the fuel injection valve 10 is controlled to open based on this fuel injection amount Ti.

Here, the sampling process of the intake pressure PB and the fuel injection amount T performed by the control unit 11 and the fuel injection amount T
The calculation settings for i will be explained according to the program shown in flowchart 1 of FIGS. 3 to 5.

In this embodiment, the functions of the change rate calculation means, the detection delay error amount setting means, and the delay correction means are performed by the third
The software is provided as shown in the flowcharts of FIGS.

The program shown in flowchart 1 in Figure 3 is 4ms.
First, in step 1 (indicated as S1 in the figure, the same applies hereinafter), the intake pressure sensor 9
The intake pressure PB is determined by map conversion based on the detection signal (sensor output) output corresponding to the intake pressure PB.

Then, in the next step 2, the deviation between the intake pressure PB obtained in step 1 this time and the intake pressure PB also obtained in step 1 during the previous execution is calculated, and this deviation is calculated for 4 ms, which is the execution cycle of this program. Set the change rate ΔPB of the hit (per unit time).

In the next step 3, a correction value PBhos corresponding to the detection delay error amount is calculated according to the following equation.

Here, the propagation time is defined as the pressure propagating at approximately the speed of sound in the piping 9 that communicates and connects the intake pressure sensor 9 and the intake manifold 5.
It is the time for propagation in a, and the length l of the pipe 9a is the speed of sound (
ξ340m/s).

In the correction value PBhos calculated by the above formula, ΔPB
Since the rate of change of the intake pressure PB per lms is calculated by /4ms, by multiplying this by the propagation time, the propagation time, in other words, the change rate of the intake pressure PB during the response delay time corresponding to the length of the pipe 9a is calculated. The amount of change is calculated, and the amount of change in the propagation time is predicted and set from the latest change rate ΔPB, and this amount of change corresponds to the detection delay error of the intake pressure sensor 9 with respect to the latest intake pressure PB in the intake manifold 5. presume that it is a thing.

In the next step 4, the correction value PBho obtained in step 3 is added to the intake pressure PB obtained in step 1.
s is converted and corrected, and the final intake pressure PBs is set.

In this way, the amount of change in the intake pressure PB during the propagation time is predicted and set according to the length of the pipe 9a that communicates and connects the intake pressure sensor 9 and the intake manifold 5, and the intake pressure PB is adjusted based on the predicted amount of detection delay. By correcting the detected value, even if the piping 9a becomes longer and the propagation time becomes longer due to, for example, installing the intake pressure sensor 9a in the passenger compartment, the response delay due to the propagation time can be compensated for. , it is possible to ensure detection responsiveness during transient operation, and as a result,
It is possible to improve the accuracy during transient times of setting the fuel injection amount based on the intake pressure PB.

Next, the process of setting the fuel injection amount based on the intake pressure PBs with the transient detection delay corrected as described above will be explained according to the program shown in the flowchart of FIG.

This program is executed every 10 ms, and first, in step 11, the basic fuel injection amount TpPB is calculated based on q 10 according to the following equation.

T p P 13'-KCONDX P B
sXKQCYLXKTA Here, KCOND is a constant based on the injection characteristics of the fuel injection valve IO, and KQCYL is a volumetric efficiency correction coefficient, which is set based on the intake pressure PBs and the engine rotation speed N. Furthermore, KTA is an intake air temperature correction coefficient that is set based on the intake air temperature TA detected by the intake air temperature sensor 6.

In the next step 12, the basic fuel injection amount 'rpPB calculated in step 11 is subjected to various corrections as shown in Figure 2 to calculate the final fuel injection amount Ti.

T i+-Tp PBXLMDXCOEF+Ts In the above equation, LMD is a correction coefficient, COEF, for feedback correcting the air-fuel ratio of the engine intake air-fuel mixture detected by the oxygen sensor 14 to the target air-fuel ratio (stoichiometric air-fuel ratio).
are various correction coefficients that are mainly set based on the cooling water temperature Tw detected by the water temperature sensor 12, and Ts is the fuel injection valve 1.
This is a correction amount for correcting a change in the invalid injection time of the fuel injection valve 10 due to a voltage change of a battery (not shown) which is a driving power source of the fuel injection valve 10.

A drive pulse signal corresponding to the fuel injection amount Ti, which is updated every 10 ms in this way, is output to each fuel injection valve 10 according to the flowchart of FIG. The program shown in the flowchart of FIG. 5 is executed every time the reference angle signal REF is output from the crank angle sensor 15, and in step 21, the pulse width corresponding to the latest set fuel injection amount Ti is set. A drive pulse signal with
The fuel is output to the fuel injection valve 10 separately so as to match the timing with the intake stroke of each cylinder.

<Effects of the Invention> As explained above, according to the present invention, when a sensor that detects the intake pressure of an internal combustion engine is connected to the intake passage via piping, pressure propagation determined by the length of the piping is prevented. Since the detected value is corrected by predicting the detection response delay based on time and the rate of change of intake pressure per unit time, a delay in the sensor's detection response occurs when the intake pressure is transient. This has the effect that, for example, the transient response of fuel supply control based on the intake pressure can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the present invention, FIGS. 3 to 5 are flow charts showing control details in the above embodiment, and FIG. The figure does not show the response delay characteristics of the intake pressure sensor according to the length of the piping, but is a time chart 1.

Claims (1)

[Scope of Claims] An intake pressure detection means that is connected to an intake passage on the downstream side of an intake throttle valve via piping and outputs a detection signal corresponding to the intake pressure of the engine; and a detection output from the intake pressure detection means. a change rate calculating means for calculating a change rate of a signal in a predetermined unit time; and a detection delay error amount setting means for predicting and setting a detection delay error amount based on the pressure propagation time determined by the length of the piping and the change rate. , delay correction means for correcting the detection signal by the intake pressure detection means based on the detection delay error amount predicted and set by the detection delay error amount setting means, and making the correction result a final detected value. An intake pressure detection device for an internal combustion engine, characterized in that: