JPH02271041A - Intake-air temperature detecting device of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve air-fuel ratio control ability at the transient time of engine driving and at the time of hotly start by providing an outside air temperature detecting means, an engine temperature detecting means, a driving state detecting means, and an intake-air temperature estimation setting means. CONSTITUTION:A control unit 11 also works as an intake-air temperature estimation setting means in an intake-air temperature detecting device. Using a compensation coefficient set according to the intake air flow estimated and set from intake pressure and from engine rotational speed, as well as a compensation coefficient set according to the temperature of cooling water, outside air temperature detected by an outside air temperature sensor 6 is compensated, so as to estimate and set the intake-air temperature. The estimated and set intake-air temperature has sufficient responsibility required even when an engine 1 is driven transiently, and is not to be erroneously set being affected by engine temperature during the starting of the engine or during the idle-driving when the intake air flow is low, and if air density of the fuel supply amount is compensated using the intake-air temperature, air-fuel ratio control ability can be improved.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an intake air temperature detection device for an internal combustion engine.

<Prior art> Devices that electronically control the amount of fuel supplied to an internal combustion engine set the basic amount of fuel supplied or perform variable control based on a combination of either intake pressure or intake air flow rate and engine rotation speed. There are some that set the basic fuel supply amount based on a combination of the opening area of the intake system and the engine rotation speed.
Unless the basic fuel supply amount is set by directly detecting the mass flow rate of the intake air using a hot-wire flowmeter, etc., the intake air temperature (
Hereinafter, it will be abbreviated as intake air temperature. ), and the fuel supply amount is corrected for the air density based on this intake air temperature (see Japanese Utility Model Application No. 60-120239, etc.).

<Problems to be Solved by the Invention> By the way, when detecting the intake air temperature and correcting the air density of the fuel supply amount as described above, a temperature sensor for detecting the intake air temperature is placed at a gathering part of the intake manifold, etc. However, when there is a sudden change in intake air temperature such as during transient operation, the fourth
As shown in the figure, due to the poor responsiveness of the sensor, there was a problem in that good air density correction could not be performed and the air-fuel ratio controllability deteriorated.

Additionally, when starting the engine when it is sufficiently warmed up (hot exhaust), the intake air temperature sensor picks up the heat from the intake manifold, causing the sensor's detection accuracy to deteriorate, as shown in Figure 5. There was also the problem of getting worse.

The present invention has been made in view of the above-mentioned problems, and provides a detection device capable of responsively and accurately detecting intake air temperature. In supply control, the purpose is to improve air-fuel ratio controllability during engine transient operation and hot restart.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. The engine includes an operating state detection means for detecting a related operating state quantity, and an intake air temperature prediction setting means for predicting and setting an intake air temperature by correcting the detected outside air temperature based on the engine temperature and the operating state quantity. An intake air temperature detection device for an internal combustion engine was constructed.

<Function> According to this configuration, the outside air temperature detection means detects the outside air temperature that is not easily influenced by the engine temperature, so the outside air temperature detected by the detection means does not have a response delay or may affect the engine temperature. false positive detections can be avoided.

In addition, when the intake air of the engine is taken in from the outside air and passes through the intake passage, heat is exchanged with the engine.
The heat exchange here is approximately determined by the intake air flow rate and the engine temperature (especially the intake manifold wall temperature), so the engine temperature is detected by the engine temperature detection means, and the operating state detection means is used to adjust the intake air flow rate. Detects related operating state quantities,
The intake air temperature prediction setting means predicts and sets the intake air temperature from the outside air temperature by predicting the state of the heat exchange from these detection results.

<Example> The present invention will be explained in detail below.

In FIG. 2 showing the system configuration of one embodiment, an internal combustion engine 1 includes an air cleaner 2. Air is taken in through the intake duct 3, the throttle chamber 4, and the intake manifold 5. The air cleaner 2 has the outside air temperature TA□ of the engine 1.
Outside air temperature sensor 6 as an outside air temperature detection means for detecting
is provided.

The throttle chamber 4 is provided with a throttle valve 7 that operates in conjunction with an accelerator pedal (not shown) to control the intake air flow rate Q. The throttle valve 7 is attached with a potentiometer for detecting its opening degree TVO, and a throttle sensor 8 including an idle switch 8A that is turned on at its idle position.

The intake manifold 5 downstream of the throttle valve 7 is provided with an intake pressure sensor 9 that detects the intake pressure PB.
An electromagnetic fuel injection valve 1o is provided for each cylinder.

The fuel injection valve 10 is driven to open for a predetermined time by an injection pulse signal output from a control unit 11 containing a microcomputer, which will be described later, in synchronization with the ignition timing, and is driven to a predetermined pressure by a pressure regulator from a fuel pump (not shown). The controlled fuel is injected and supplied into the intake manifold 5.

Further, a water temperature sensor 12 is provided to detect the temperature Tw of cooling water in the cooling jacket of the engine 1.

Since the cooling water temperature Tw represents the engine temperature, the water temperature sensor 12 corresponds to the engine temperature detection means in this embodiment.

The control unit 1 counts the crank unit angle signal PO3 output from the crank angle sensor 15 in synchronization with engine rotation for a certain period of time or outputs a crank reference angle signal REF (4 cylinders) at each predetermined crank angle position. In the case of
Calculate.

The control unit 11 also controls the intake pressure PB detected by the intake pressure sensor 9 and the crank angle sensor 15.
The engine rotation speed N calculated based on the detection signal from
The basic fuel injection amount (basic fuel supply amount) Tp is set based on the air temperature correction coefficient KTSA based on the intake air temperature TSA, and this basic fuel injection 1tTp is corrected based on various operating conditions to determine the final fuel. Calculate the injection amount Ti,
An injection pulse signal with a pulse width corresponding to this fuel injection amount Ti is outputted to the fuel injection valve 10 at a predetermined timing to intermittently supply fuel to the engine 1.

Furthermore, the control unit 11 also serves as an intake air temperature prediction setting means in the intake air temperature detecting device according to the present invention, and adjusts the outside air temperature TAIa detected by the outside air temperature sensor 6 to the intake air pressure PB and the engine rotation speed N. The intake air temperature TSA is predictively set by correcting it by a correction coefficient of 9, which is set according to the intake air flow rate Q that is predicted and set, and a correction coefficient KTw, which is set according to the cooling water temperature Tw.

In this embodiment, as described above, the intake pressure sensor 9 and the crank angle sensor 15 correspond to the driving state detection means.

The prediction setting of the intake air temperature TSA will be explained according to the flowchart of FIG.

First, step 1 (indicated as Sl in the figure).

), the outside air temperature TAI is detected from the outside air temperature sensor 6.
The analog signal output according to the temperature is converted into a digital signal, and the instantaneous value of the outside air temperature TA11 is read.

In the next step 2, the water temperature correction coefficient KTw corresponding to the current cooling water temperature Tw is calculated based on the detected value of the water temperature sensor 12 from the map on the water temperature correction coefficient KTwOROM that is preset according to the cooling water temperature Tw. Search and ask.

In addition, in step 3, the intake pressure PB and the engine rotation speed N
From the map in the ROM where the air amount correction coefficient is set to 0 in advance for each operating state that is divided into multiple states according to the Search and ask.

The above correction coefficients K T w and K o are set in advance by matching through experiments, and the correction coefficient K
For example, Tw may be the intake manifold 5 even if the engine is the same.
If there is a change in the heat transfer coefficient, volume, shape, etc. of the water temperature sensor 12, or if there is a change in the position of the water temperature sensor 12, the optimum value will change.

Then, in step 4, the correction coefficient K T w obtained by searching in step 2.3 is applied to the outside air temperature TA11.

Multiply Ko to obtain intake air temperature TSA (←T□* xKTw
x K' o ).

Air taken into the engine is taken in from outside air via an air cleaner 2, and then heat exchanged when passing through a throttle chamber 4 and an intake manifold 5 before being taken into the cylinder. Therefore, if the temperature of the intake manifold 5 or the like is high, the intake air temperature TSA will be high, and if the amount of air flowing is small, the intake air temperature TSA will be high.

Here, the temperature of the intake manifold 5 etc. is the cooling water temperature Tw
Since the air flow rate Q can be estimated from the intake pressure PB and the engine rotation speed N, the correction coefficient KTw obtained from the outside air temperature TAIll from the cooling water temperature Tw and the correction coefficient obtained from the intake pressure PB and the engine rotation speed N. The intake air temperature TSA can be predicted and set by correcting it with 0.

Since the outside air temperature sensor 6 is located far from the heat generating part of the engine 1, it is not easily affected by the heat generated by the engine 1, and
Since the outside air temperature T a I* has a gentle temperature fluctuation, the detection response does not pose a problem.

In addition, the coolant temperature Tw detected by the water temperature sensor 12 does not show a sudden temperature fluctuation that would cause a delay in response of the sensor, and furthermore, the detection by the intake pressure sensor 9 has almost no response considering the level of the temperature sensor. I can say there will be no delays.

Therefore, the intake air temperature TSA predicted and set in this example is:
It has the necessary and sufficient responsiveness even when the engine 1 is operated transiently, and is not erroneously set due to the influence of the engine temperature when the engine is started or during idling operation with a low intake air flow rate Q. If the air density correction of the fuel supply amount is performed using this intake air temperature TSA, the air-fuel ratio controllability will be improved.

When the intake air temperature TSA is predicted and set from the outside air temperature 'T''AIN as described above, the air density correction coefficient KTSA is obtained by searching from a map etc. based on this intake air temperature TSA, and the basic fuel injection ITp is set based on this air temperature 'T''AIN. The fuel supply amount is corrected using the density correction coefficient KTSA, and the fuel supply amount is set in accordance with the mass air amount.

Setting of the basic fuel injection amount Tp based on the intake pressure PB and the engine rotational speed N is performed, for example, as follows.

First, based on the intake pressure PB, the basic volumetric efficiency correction coefficient K
In addition to setting PB, engine rotation speed N and intake pressure FB
Set the minute correction coefficient KFLAT from and multiply these to obtain the volumetric efficiency correction coefficient KQCYL (←KPBXKFL
AT) is calculated. And this volumetric efficiency correction coefficient KQ
CYL, the intake pressure PB, a constant KCOND based on the injection characteristics of the fuel injection valve 10, and the air density correction coefficient KT.
SA and basic fuel injection tT p (-KCOND
X P B x KQCYLxKTSA) is the operation saler.

In this embodiment, the outside air temperature 'I' is determined based on the intake air flow rate Q predicted from the intake pressure PB and the engine rotational speed N.
Although the configuration is configured to correct AIR, the predicted intake air flow i based on the throttle valve opening TVO and the engine rotation speed N is used instead of the combination of the intake pressure PB and the engine rotation speed N.
Correction may be made based on IQ.

Furthermore, if the air flow meter is not of a type that detects mass flow rate, such as a flap type, the detected value may be used as is for correction. In this case, the operating state detection means is the throttle sensor 8. Crank angle sensor 15. Furthermore, a separately provided air flow meter corresponds to the operating state detection means.

<Effects of the Invention> As explained above, according to the present invention, the intake air temperature of the engine can be detected with good responsiveness, and there is no possibility of false detection due to the influence of the engine temperature. For engines that are not equipped with a sensor that directly detects intake air temperature, by correcting the air density of the fuel supply amount based on the detected intake air temperature, it is possible to improve transient drivability, as well as startability and idle stability. There is.

[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, FIG. 3 is a flowchart showing control details in the same embodiment, and FIGS. 4 and 5 are diagrams for explaining the problems of the conventional device, respectively. 1... Engine 6... Outside temperature sensor 8...
Throttle sensor 9... Intake pressure sensor 11.
...Control unit 12...Water temperature sensor 1
5... Crank angle sensor patent applicant Fujio Sasashima, agent of Japan Electronics Co., Ltd., patent attorney Figure 2

Claims (1)

[Scope of Claims] Outside air temperature detection means for detecting outside air temperature; engine temperature detection means for detecting engine temperature; operating state detection means for detecting an operating state quantity related to the intake air flow rate of the engine; An intake air temperature detection device for an internal combustion engine, comprising: an intake air temperature prediction setting means for predicting and setting an intake air temperature by correcting the outside air temperature based on the engine temperature and the operating state quantity.