JPS61294156A - Estimation-detection of outside-air temperature on the upstream of throttle valve of internal-combustion engine - Google Patents

Abstract

PURPOSE:To cut cost by removing an outside air temperature sensor by estimation-detecting the outside air temperature from a prescribed calculation equation, using each output signal of an engine cooling water temperature sensor and an intake air temperature sensor. CONSTITUTION:During engine operation, the intake air temperature Ta and the intake negative pressure Pba in a suction pipe 7 are detected by a Ta sensor 10 and a Pba sensor 11, respectively, and the cooling-water temperature Tw in the vicinity of a suction valve 1 is detected by a Tw sensor 12, and the engine revolution speed Ne is detected by an Ne sensor 13. In a microcomputer 17, the first correction coefficient KQa is determined according to the product of Pba and Ne by using a prescribed table memorized into a memory 16. Then, using the above-described data Tw, Ta and KQa and a constant value Kamb determined according to the mechanical structure and dimension of the engine which are previously memorized as constant values in the memory 16, the outside air temperature Tamb is estimation-calculated, using Tamb=KQa(Ta-Tw)Kamb+Tw.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for predicting and detecting outside air temperature upstream of a throttle valve of an internal combustion engine. An internal combustion engine system that predicts and detects the outside air temperature at a predetermined position of a throttle valve-1 second flow based on the temperature and the intake air temperature detected by an intake air temperature sensor installed at a predetermined position in the intake pipe downstream of the throttle valve. The present invention relates to a method for predicting and detecting outside air temperature upstream of a throttle valve.

(Prior art) Electronic fuel injection devices using the speed density method (negative pressure detection control method in the intake pipe) measure the amount of air inhaled per intake by measuring the negative pressure in the intake pipe and the intake air temperature. It detects the amount of air and adjusts the amount of fuel injected accordingly.

However, in this speed-density method, during idling, the injection amount of fuel 1 is inappropriate for the amount of intake air, so the engine speed tends to hunt. Therefore, in order to prevent hunting, it is necessary to correct the fuel injection amount according to the atmospheric pressure upstream of the throttle valve and the outside temperature.

Therefore, the conventional speed/density method requires an outside temperature sensor.

Furthermore, in order to operate an emission device such as an FGR or a low temperature device that controls the injection of fuel 191 at low temperatures, it is necessary to detect the outside air temperature upstream of the thrower valve. For this reason, conventional vehicles equipped with emission devices and low-temperature devices always require an outside temperature sensor.

(Problems to be Solved by the Invention) The above-described conventional technology has the disadvantage that the internal combustion engine is expensive due to the necessity of installing an outside air temperature sensor.

The present invention has been made to overcome the above-mentioned drawbacks.

(Means and Effects for Solving the Problems) In order to solve the above-mentioned drawbacks, the present invention aims to reduce the humidity of the engine cooling water that is cooling near the intake valve and to reduce the humidity at a predetermined position in the intake pipe downstream of the throttle valve. The feature is that the outside air temperature sensor can be omitted by predicting and detecting the outside air humidity at a predetermined position upstream of the throttle valve based on the intake air temperature detected by the installed intake air temperature sensor.

It should be noted that an engine temperature sensor that detects the temperature of engine cooling water is indispensable as a sensor necessary for determining the operating state of the engine.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 2 shows that the internal combustion engine is
If of a device that predicts and detects the outside air temperature upstream of the 1-1 valve
! 1 (llIi'J If).

In the same figure, there are intake valves 1 and 1 at the top of cylinder 3.
One valve and two valves are provided. Screw 1 inside cylinder 3
The crank 4 repeatedly reciprocates and applies rotational force to the crank 5. The injection nozzle 6 injects fuel near the intake port (=I) which is opened and closed by the intake valve 1.

Note that the injection foot of this fuel 31 is determined by known means.

An intake manifold chamber 8 is provided on the upstream side of the intake pipe 7, which is one of the intake manifolds.Roughly, a throttle valve 9 is provided on the negative side of the intake manifold chamber 8. The upstream side of this slot valve 9 is in communication with the outside air through the AC reach 1B.

Further, the intake air temperature sensor (Ta sensor) 10 is connected to the intake pipe 7.
The internal intake air temperature la is detected and a digital l'-a signal is supplied to the input/output processing circuit (interface) 14 of the microcomputer 17.

Pl)a sensor 11 detects the pressure (negative pressure) pb in the intake pipe 7
a and supplies a digital Pba signal to the interface 14.

The TW sensor 12 detects the engine coolant temperature, particularly the engine coolant temperature Tv11 near the intake valve 1, and supplies it to the digital Tw multiplier signal interface 1/'I.

The Ne sensor 13 detects the engine speed NO and supplies a digital Ne signal to the interface 1/1.

The microcomputer 17 includes, in addition to the ink-face 1/1, a central processing unit (CPU) 15J5 and a storage device (memory) 1G.

Here, a basic method for predicting and detecting the outside air temperature upstream of the throttle valve 9 according to the present invention will be explained.

FIG. 3 is a graph showing the relationship between the distance in the intake passage from the position of the Tw sensor 12 of the internal combustion engine and the temperature.

Now, if we assume that no air is flowing in the intake pipe 7, the temperature distribution of the intake pipe 7 and, by extension, the air in the intake passage will be the temperature detected by the Tw sensor 12, that is, the engine cooling near the intake valve 1. The water temperature T'y11 is a distance of 1 ta from the water temperature T'y11.

The reason for this is that the air in the intake passage receives heat from the inner wall of the intake passage, so the temperature of the inner wall is considered to be almost the same, while the temperature of the inner wall of the intake passage is determined by heat conduction from the cylinder 3. This is because it falls in proportion to the distance.

Therefore, when air is not flowing in the intake passage, the outside air temperature T amb at the scheduled position upstream of the throttle valve 9, which is a distance l tamb away from the TW sensor 12, is expressed by the following equation (1).

Tamb - (Ta - Tw) Kamb + Tw
-...-<1) However, Kamb is L tamb
/ lta.

However, in reality, intake air flows within the intake passage. For this reason, the temperature of the air within the intake passage does not match the temperature of the inner wall of the intake passage.

Specifically, the intake air temperature Ta detected by the Ta sensor 10 is detected as a lower value than when it is assumed that no air is flowing. As a result, (Ta-” of the above formula (1)
If the term (lW) is used as is, it is not possible to accurately calculate the outside air humidity amb.

Therefore, in this example, a first correction coefficient KQa is experimentally determined in order to appropriately correct the term (Ta - Tw) and obtain an accurate outside air temperature Tamb. was included in equation (1).

The following equation (2) is an equation that includes the first correction coefficient KQa.

Tamb −KQa(Ta −Tw) Kamb +
Tw... (2) Note that KQa is determined as a function of the product of - negative pressure circle in the intake pipe) a and the engine rotational speed Ne, which represents the amount of intake air. FIG. 4 is a graph showing the function of (1'baxNe) and KQa.

Here, at the planned position upstream of the throttle valve 9, which is located from the center 12 to the road head,
11- A specific method for predicting and detecting the outside air temperature T amb will be explained using the flow chart shown in FIG.

In FIG. 1, in step S1, lw sensor 12
The cooling water temperature TW near the intake valve 1 is read based on the signal from the intake valve 1.

Step S2... According to the signal from the Ta sensor 10,
The intake air temperature l'a in the intake pipe 7 is read.

Step S3: The negative pressure pba in the intake pipe 7 is read based on the signal from the pba sensor 11.

Step S4... According to the signal from the Ne sensor 13,
Read engine speed Ne.

Step S5: Step S3 and step $
Find the product of the negative pressure Pba read in step 4 and the engine speed Ne.

Step S6...According to the product of Pba and Ne obtained in step S5, (yen) ax Ne e) ~ K Q
The first correction coefficient KQa is determined from the a table (see FIG. 4). Note that the (PbaXNe) to KQa files are stored in advance in the memory 1G.

Step S7: Based on l'-w, la and K Q a determined in steps S1, S2 and S6, and l (aml) stored in advance as a constant value in the memory 16. Then, the above equation (2) is calculated to calculate the outside air humidity T amb.

Note that, as is clear from the above, the above-mentioned Kamb is a constant value determined by the mechanical structure and dimensions of the engine. −Instead of pull, (PbaxNe) ~(KQaxKam
b) Create a table, store it in the memory 16 in advance, and calculate (KQa xl(a
It is also possible to read the value of mb).

By the way, the above was an explanation of the case of a multi-point injection system having an injection nozzle 6 for each cylinder. There is a single-point injection system in which a single injection nozzle is installed.

Hereinafter, a method for predicting and detecting outside air temperature Tamb using this single point injection method (second embodiment) will be described.

This second embodiment is different from the first embodiment, which is based on the multi-point injection method described above, because the injection nozzle is disposed near the throttle valve 9. Compared to the embodiment, the intake air is cooled by the latent heat of vaporization of the fuel.

As a result, the intake air temperature Ta detected by the la sensor 10 has a lower value than in the first embodiment.

Therefore, based on the above equation (2), the outside air temperature T a
In order to accurately calculate mb, (Ta −
A second correction coefficient KTou that appropriately corrects the term Tw )
It is necessary to experimentally find t and calculate it into equation (2).

Equation (3) shown below includes the second correction coefficient KHout.

Lower amb = KQa −K T out(la −
Tw)) (amb Jucho W...
...(3) In addition, K-"out LJ: is determined as a function of the fuel amount at the opening time of llj. Specifically,
- It is determined as a function of the product of the opening time of the injection nozzle per intake air, 1-out, the engine rotational speed, and Ne. FIG. 5 is a graph showing the relationship between (Tout xNe) and KTout.

Here, regarding a specific method of predicting and detecting the outside air temperature T amb at the scheduled position of the throttle valve 9'' second flow, which is separated by a distance of 1 tamb from the sensor 12 in the second embodiment, the method shown in FIG. This will be explained using flowcharts 1 to 1.

Incidentally, steps 81 to S6 in FIG. 6 are exactly the same as steps 81 to S6 in FIG. 1 relating to the first embodiment described above, so a description thereof will be omitted.

Step S7: The valve opening time 1out per intake of the injection nozzle detected by a known method is read.

Step S8: The product of the valve opening time To old read in step S7 and step S4 and the engine rotation speed Ne is calculated.

Step S9...T ou obtained in step S8 above
Depending on the product of t and Ne, (TOutXNe) ~ KTou
The second correction coefficient is calculated from the t table (see Figure 5).
Determine t. In addition, (ding out xNe) ~ KHo
The ut table is stored in memory 16 in advance.

Step 810...Ding w, l determined in step S1, step S2, step S6 and step S9
a , ) (based on Qa and out and Ka amb stored in advance in the memory 16 as a constant value,
The outside air temperature amb is calculated by calculating the above equation (3).

Note that, similarly to the first embodiment, in this second embodiment, instead of the (PI)aXNe ) ~KQa table, (pbaxNe) ~(KQa xKamb)
Of course, it is also possible to create a table, store it in the memory 16 in advance, and read out the value of (KQa xKamb) corresponding to the product of Pba and Ne.

(Effects of the Invention) As is clear from the explanations below, according to the present invention, the following effects are achieved.

(1) By using a TW sensor (engine temperature sensor) that detects the engine cooling water temperature and a Ta sensor (intake air temperature sensor) that detects the temperature in the intake pipe, which are normally installed in an internal combustion engine. , the outside temperature at a predetermined position upstream of the throttle valve can be predicted and detected.

As a result, an outside air temperature sensor is not required, and the structure of the internal combustion engine can be simplified and the cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is a flowchart illustrating a first embodiment of the method of the invention. FIG. 2 is a schematic diagram of an apparatus for carrying out the method of the present invention. FIG. 3 is a graph showing the relationship between the distance in the intake passage of the internal combustion engine from the Tw center position and the temperature. FIG. 4 is a graph showing the relationship between (pbaxNe) and KQa. Figure 5 shows (Tout x
3 is a graph showing the relationship between Ne) and KTout. 6th
The figure is a flowchart illustrating a second embodiment of the method of the invention. DESCRIPTION OF SYMBOLS 1... Intake valve, 6... Injection nozzle, 7... Intake pipe, 9... Throttle valve, 10... L-a sensor, 1
1... pba sensor 12... Ding W sensor, 13...
・・Ne sensor, 14・・Interface, 15・
...cpu.

Claims (4)

[Claims] (1) Engine cooling water temperature detection means for detecting the temperature of the engine cooling water that cools the vicinity of the intake valve of the internal combustion engine; and intake air turbidity detection means for detecting the intake air humidity at a predetermined position in the intake pipe downstream of the throttle valve. A method for predicting and detecting outside air temperature upstream of a throttle valve of an internal combustion engine, comprising: a difference between the engine cooling water temperature and the intake air humidity;
As a function of the distance from the engine coolant temperature detection means to the intake air temperature detection means and the distance from the engine coolant temperature detection means to the planned position upstream of the throttle valve, the outside air at the planned position upstream of the throttle valve A method for predicting and detecting outside air temperature upstream of a throttle valve of an internal combustion engine, characterized in that temperature is calculated. (2) The calculation of the outside air temperature is based on the difference between the engine coolant temperature and the intake air temperature, a first correction coefficient preset as a function of the intake air amount, and the position of the engine coolant temperature detection means. to the planned position upstream of the throttle valve and the quotient obtained by dividing the distance from the position of the engine cooling water temperature detection means to the intake air temperature detection means. 2. A method for predicting and detecting an outside air temperature upstream of a throttle valve of an internal combustion engine according to claim 1, characterized in that the outside air temperature is subtracted from the water temperature. (3) engine cooling water temperature detection means for detecting the temperature of engine cooling water cooling the vicinity of the intake valve of the internal combustion engine; and intake air temperature detection means for detecting the intake air temperature at a predetermined position in the intake pipe downstream of the throttle valve; A method for predicting and detecting an outside air temperature upstream of a throttle valve of an internal combustion engine, the method comprising: a fuel supply means disposed upstream of the intake air temperature detecting means; Humidity as a function of the distance from the water humidity detection means to the intake air temperature detection means and the distance from the engine cooling water humidity detection means to the planned position upstream of the throttle valve is calculated, and the obtained temperature is The internal combustion engine is characterized in that the outside air temperature at a predetermined position upstream of the throttle valve is calculated by correcting it with a second correction coefficient that is preset as a function of the amount of fuel supplied from the fuel supply means. A method for predicting and detecting outside air humidity upstream of an engine throttle valve. (4) The calculation of the outside air temperature is based on the difference between the engine cooling water temperature and the intake air humidity, a first correction coefficient preset as a function of the intake air amount, and the fuel supplied from the fuel supply means. a second correction coefficient preset as a function of the quantity, a distance from the position of the engine coolant humidity detection means to a scheduled position upstream of the throttle valve, and the intake air temperature detection from the position of the engine coolant temperature detection means. The product obtained by dividing the distance to the means and multiplying it by the quotient obtained is
4. A method for predicting and detecting an outside air temperature upstream of a throttle valve of an internal combustion engine according to claim 3, characterized in that the temperature is subtracted from the engine cooling water temperature.