JPH0821292A - Altitude deciding device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve altitude decision precision by detecting a flow rate of intake air as a flow rate of a mass, estimating a flow rate of intake air from the opening area of an intake system and the number of revolutions of an engine, and deciding an altitude through comparison therebetween. CONSTITUTION:During running of a vehicle, a control unit 17 is constituted to compute the total opening area alpha of an engine intake system based on a throttle valve opening by a throttle sensor 13a and the opening duty of an idle control valve 15. By referring to a map wherein the intake air flow rate Q of an engine is previously stored from the total opening area alpha and an engine rotation speed Ne serving as a parameter, the corresponding intake air flow rate Q is estimated and computed. It is then discriminated whether a throttle valve opening TVO exceeds a reference opening ATVO (a reference area) and when it exceeds the reference opening, a ratio (x) between the intake air flow rate Q as a mass flow rate detected by an airflow meter 12 and an estimated and computed intake air flow rate Q is determined. From the ratio (x), an altitude is decided and served as control of a fuel feed amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an altitude determining apparatus for an internal combustion engine, and more particularly to an apparatus for detecting the intake air flow rate of the engine as a volume flow rate and a mass flow rate, and comparing the two to determine the altitude.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine for a vehicle,
In some cases, the altitude must be determined in order to correct the amount of fuel supplied to the engine, the automatic transmission position in an automatic transmission combined with the engine, and the like to appropriate values suitable for high-altitude traveling. As a method of determining the altitude, there is a method of directly detecting the atmospheric pressure by an atmospheric pressure sensor, but it is costly to provide a new atmospheric pressure sensor for the altitude determination. Therefore, as a method of determining altitude using an existing sensor provided for electronically controlled fuel injection control, etc., the intake air flow rate of the engine detected as a mass flow rate by an air flow meter and the opening area of the throttle valve A method for determining the altitude has been developed based on comparison with the intake air flow rate as a volumetric flow rate obtained from the engine rotation speed.

That is, in a system including a sensor capable of detecting the intake air flow rate as a mass flow rate, such as a hot wire type air flow meter, when the vehicle is traveling in a highland where the air density is reduced, the air density is reduced. Whereas the air flow meter detects a commensurate intake air flow rate, the intake air flow rate as a volumetric flow rate obtained from the throttle valve opening degree and the engine speed becomes a value irrelevant to the change in air density. Air density (altitude) due to the difference between the two
The change of can be determined.

[0004]

However, in the potentiometer type throttle sensor which is generally used for detecting the opening of the throttle valve, the allowable range of variations in sensor output with respect to the opening of the throttle valve is defined as shown in FIG. In this case, as shown in FIG. 6, the opening degree detection error due to the output variation becomes larger on the low opening side where the output is smaller, and it is difficult to detect the opening degree with high accuracy on the low opening side.

Therefore, the intake air flow rate as the volume flow rate obtained from the throttle valve opening and the engine rotation speed is also
There is a possibility that the accuracy of the altitude determination using the intake air flow rate as the volume flow rate is deteriorated due to being affected by the detection error of the throttle valve opening and having a large error particularly on the low opening side. there were. The present invention has been made in view of the above problems, and an object of the present invention is to provide an altitude determination device in an internal combustion engine that can avoid deterioration in altitude determination accuracy affected by a throttle valve opening detection error. .

[0006]

Therefore, an altitude determining device in an internal combustion engine according to the invention of claim 1 is constructed as shown in FIG. In FIG. 1, the rotational speed detecting means detects the rotational speed of the engine, the opening area detecting means detects the opening area of the engine intake system which is variably controlled, and the intake air flow rate detecting means detects the intake air flow rate of the engine by the mass flow rate. To detect as.

Further, the intake air flow rate estimating means estimates and calculates the intake air flow rate of the engine based on the detected rotational speed and opening area. Then, the altitude determination means, only when the opening area detected by the opening area detecting means is equal to or larger than a predetermined reference area, the intake air flow rate detected by the intake air flow rate detecting means and the intake air flow rate estimating means. The altitude is determined based on the intake air flow rate estimated in.

In the altitude determining device according to the second aspect of the present invention, the opening area detecting means includes a throttle valve opening degree detecting means for continuously detecting the opening degree of the throttle valve provided in the engine intake system. On the other hand, a detection error learning correction means for learning and correcting a detection error of the throttle valve opening detection means is provided, and the throttle valve opening detected by the altitude determination means by the throttle valve opening detection means is predetermined. When it is equal to or larger than the reference opening of the above, it is set as an opening area condition for altitude determination, and when the detection error learning correction means learns and corrects the detection error of the throttle valve opening detection means, it is compared with the non-learning correction. The reference opening is shifted to a lower opening.

In the altitude determination device according to the third aspect of the present invention, an idle switch that is turned on at the fully closed position of the throttle valve and a full switch that is turned on at the fully opened position of the throttle valve are provided, and the detection error learning is performed. The correction means
ON / OFF of the idle switch and full switch
The detection error of the throttle valve opening detecting means is learned and corrected based on the detection value of the throttle valve opening detecting means at each switching.

[0010]

In the altitude determining device according to the invention of claim 1, the intake air flow rate of the engine is detected as a mass flow rate, and
The intake air flow rate of the engine is estimated and calculated from the opening area of the intake system and the engine rotation speed. Then, the change in the air density due to the change in altitude is detected by comparing the intake air flow rate as the estimated and calculated volume flow rate with the intake air flow rate detected as the mass flow rate.

Here, the error in the intake air flow rate estimation calculation caused by the detection error of the opening area detection means is
Since the smaller the opening area is, the larger the area tends to be. Therefore, by setting the condition that the opening area is equal to or larger than the reference area as the altitude determination condition, it is possible to prevent the accuracy of the altitude determination from being significantly deteriorated due to the detection error of the opening area. In the altitude determination device according to the second aspect of the present invention, the opening of the throttle valve is detected as a value indicating the opening area of the intake system, and the altitude is determined when the opening of the throttle valve is equal to or larger than the predetermined opening. When the learning correction of the detection error by the means for detecting the opening of the throttle valve is performed, the detection error of the opening decreases,
The reference opening is shifted to the lower opening side to allow the altitude determination on the lower opening side so that the opportunity for the altitude determination is secured.

In the altitude determination device according to the invention of claim 3, the idle switch and the full switch are turned on and off.
By sampling the opening detection result based on the switching time point, the detection output at the fully closed position and the fully opened position is obtained, and the detection error of the throttle valve opening detection means is learned based on this.

[0013]

Embodiments of the present invention will be described below. In FIG. 2 showing an embodiment, air is drawn into a vehicle internal combustion engine 1 through an air cleaner 2, a throttle chamber 3 and an intake manifold 4. Then, the combustion exhaust gas from the engine 1 is discharged into the atmosphere through the exhaust manifold 5, the exhaust duct 6, the three-way catalyst 7, and the muffler 8.

The throttle chamber 3 is provided with a throttle valve 9 which opens and closes in conjunction with an accelerator pedal (not shown), and the throttle valve 9 adjusts the intake air amount of the engine 1. Each cylinder (#
The spark plugs 10 are mounted so as to face the combustion chambers 1 to # 4), and the mixture is ignited and burned by the spark ignition by the spark plugs 10.

A crank angle sensor 11 for detecting a crank angle through rotation of the cam shaft is provided on a cam shaft (not shown) of the engine 1. This crank angle sensor 11
In the four-cylinder engine 1 of the present embodiment, the reference angle signal REF for each crank angle of 180 ° corresponding to the stroke phase difference between the cylinders.
And a unit angle signal POS for each unit crank angle (1 ° or 2 °).

Here, the generation cycle of the reference angle signal REF or the unit angle signal POS within a unit time.
The engine rotation speed Ne can be obtained based on the number of occurrences of the above, and the crank angle sensor 11 corresponds to the rotation speed detection means in this embodiment. Further, a hot wire type air flow meter 12 for detecting the intake air flow rate Q of the engine is provided on the upstream side of the throttle valve 9. The hot-wire air flow meter 12 detects the intake air flow rate Q of the engine as a mass flow rate based on the change in the resistance value of the temperature-sensitive resistance due to the intake air flow rate, and corresponds to the intake air flow rate detecting means in this embodiment. .

Further, the throttle valve 9 is a potentiometer type throttle sensor 13a (throttle valve opening detecting means) for continuously detecting the opening (angle) TVO, and it is turned on at the fully closed position of the throttle valve 9. Idle switch
13b, a full switch 13c that is turned on when the throttle valve 9 is fully opened is integrally provided. Further, an auxiliary air passage 14 that bypasses the throttle valve 9 is provided, and an electromagnetic idle control valve 15 whose opening and closing is duty-controlled by a control unit 17 is interposed in the auxiliary air passage 14.

On the other hand, each branch of the intake manifold 4 is provided with an electromagnetic fuel injection valve 16 for each cylinder. The fuel injection valve 16 intermittently injects the fuel adjusted to a predetermined pressure by a pressure regulator (not shown) into the engine in response to an injection pulse signal from the control unit 17. Here, the crank angle sensor 11,
Detection signals from the air flow meter 12, the throttle sensor 13a, the idle switch 13b, and the full switch 13c are output to a control unit 17 provided for engine control, and the control unit 17 outputs the injection pulse signal based on these detection signals. Pulse width and the opening duty of the idle control valve 15 are controlled.

Further, the control unit 17 carries out an altitude determination as shown in the flow charts of FIGS. 3 and 4, and the determination result is used for the correction control of the fuel injection amount and the internal combustion engine 1
It is used for shift control in an automatic transmission combined with. In the present embodiment, the functions of the intake air flow rate estimation means, the altitude determination means, the detection error learning correction means, and the opening area detection means are the same as those of the control unit 17 as shown in the flow charts of FIGS.
Is equipped with software.

In the flowchart of FIG. 3, in step 1 (denoted as S1 in the figure; the same applies hereinafter), the intake air flow rate Q as the mass flow rate detected by the air flow meter 12 (intake air flow rate detecting means) is read. Step 2
Then, the output signal (voltage signal) of the throttle sensor 13a (throttle valve opening detection means) is read.

In step 3, the throttle sensor 13
It is determined whether or not the learning of the detection variation of a has been completed. If the learning has not been completed, the process proceeds to step 4, where a preset output (voltage) -opening (angle) conversion table is referred to, and the output signal read in step 2 is used as the throttle valve. Convert to opening TVO.

On the other hand, when the learning is completed, the routine proceeds to step 5, where the throttle valve opening TVO is adjusted from the output so as to compensate the detection error based on the learning result.
Is calculated (detection error learning correction means). The variation learning of the opening degree detection will be described in detail later. When the throttle valve opening TVO is obtained in step 4 or step 5, in step 6, the opening duty of the idle control valve 15 and a first idle control not shown are used as parameters related to the opening area variably controlled by the engine intake system. O of device (hereinafter abbreviated as FICD)
Refer to N / OFF signal.

The FICD is the idle control valve.
Similar to 15, it is provided in an intake passage provided by bypassing the throttle valve 9 and is controlled to open / close based on an air conditioner signal. In step 7, the total opening area α of the engine intake system is calculated based on the throttle valve opening TVO, the opening duty of the idle control valve 15, and the ON / OFF of the FICD (opening area detecting means). In the present embodiment, as will be described later, the intake air flow rate (volume flow rate) of the engine is estimated and calculated based on the opening area of the intake system that is variably controlled and the engine rotation speed Ne. Therefore, only the throttle valve opening TVO is used. When the opening area is specified, the flow rate of the air sucked into the engine 1 via the idle control valve 15 and the FICD becomes an error, so that the idle control valve other than the throttle valve opening TVO is set as described above. 15 and FIC
The total opening area α of the engine intake system including the opening area controlled by D is determined.

The total opening area α is the throttle valve opening T
VO, valve opening duty, etc. are converted into opening areas by a preset conversion table, and the opening areas are summed up. In step 8, the engine rotation speed Ne calculated based on the detection signal from the crank angle sensor 11 is read.

Then, in step 9, a map in which the intake air flow rate Q of the engine is stored using the total opening area α and the engine speed Ne as parameters in advance is referred to, and the total opening area α calculated in step 7 is set. The intake air flow rate Q corresponding to the engine speed Ne read in step 8 is searched (intake air flow rate estimation means). That is, in step 9, the intake air flow rate as the volumetric flow rate of the engine is estimated and calculated from the total opening area α and the engine rotation speed Ne.

At the next step 10, similarly to step 3, it is determined whether or not the detection variation of the throttle sensor 13a has been learned. Here, if the learning has been completed, the process proceeds to step 11, and it is determined whether or not the throttle valve opening TVO obtained in step 5 is equal to or larger than the reference opening ATVO (reference area). If learning has not been completed, the routine proceeds to step 12, where the throttle valve opening TVO obtained in step 4 is equal to or larger than the reference opening BTVO (reference area) which is a value on the open side of the reference opening ATVO. Or not.

When the opening TVO is less than the reference opening ATVO, BTVO, this routine is terminated without performing altitude detection, and the reference opening ATVO, BTVO is reached.
When the opening is TVO above, the routine proceeds to step 13 to detect the altitude. Even if the detection output of the throttle sensor 13a is within a certain error range irrespective of the opening as shown in FIG. 5, such an error is generated at the low output side (low opening side as shown in FIG. 6). ), High output side (high opening side)
Therefore, a large variation in angle detection will occur as compared with.

Therefore, the throttle valve opening T
Since the VO detection accuracy decreases, the estimation accuracy of the intake air flow rate in step 9 decreases as the opening degree decreases, and the altitude determination using the estimated and calculated intake air flow rate is performed. The accuracy will deteriorate. Therefore, by making the altitude determination only on the high opening side where the variation in the degree of opening detection is sufficiently small, it is possible to prevent the accuracy of the altitude determination from being deteriorated due to the variation in the degree of opening detection. is there.

Therefore, in order to ensure the accuracy of the altitude determination, it is desirable to make the altitude determination on the higher opening side as much as possible. Since it becomes possible to obtain the necessary and sufficient opening detection accuracy on the side, if variation learning has been completed, the opening range that allows altitude determination to be performed by shifting the reference opening to a lower opening side. To the lower opening side,
The chance of altitude judgment is secured.

In step 13, the intake air flow rate Q (in the figure, A as the mass flow rate detected by the air flow meter 12
FMQ) and the intake air flow rate Q (denoted as α-NeQ in the figure) as a volume flow rate estimated and calculated from the total opening area α and the engine rotation speed Ne.
AFMQ / α-NeQ). Here, when the altitude increases and the air density decreases, the intake air flow rate Q as a mass flow rate detected by the air flow meter 12 decreases even under the same conditions of the total opening area α and the engine rotation speed Ne. On the other hand, the intake air flow rate Q as a volume flow rate estimated and calculated from the total opening area α and the engine rotation speed Ne is not affected by the air density, and the characteristic of the estimated calculation is adapted to the air density on the level ground. Then, the intake air flow rate Q obtained on a level ground is estimated and calculated regardless of the altitude.

Therefore, on flat ground, the ratio x becomes approximately 1, but becomes smaller as the altitude becomes higher. Therefore, it is possible to judge the altitude from the ratio x. Step 14 (altitude judgment) Means), the smaller the ratio x, the higher the altitude. Next, the manner of learning the detection variation of the throttle valve opening TVO (detection error learning correction means) will be described with reference to the flowchart of FIG.

In the flowchart of FIG. 4, first, in step 21, the idle switch 13b is turned off → O.
At the time of N switching, that is, when the throttle valve 9 changes from the intermediate opening to the fully closed position, the detection output of the throttle sensor 13a is read as ITVO. In step 22, the detection output of the throttle sensor 13a is read as FTVO when the full switch 13c is switched from OFF to ON, that is, when the throttle valve 9 changes from the intermediate opening to the fully open position.

Then, at step 23, the detection output FTVO from the fully open position to the detection output IT at the fully closed position.
The value obtained by subtracting VO is divided by the angle from the fully open position to the fully closed position, and the amount of change in the detected output when the throttle valve opening TVO changes by a unit angle is slope y (←
Calculated as (FTVO-ITVO) / (fully closed-fully opened degree)).

In this embodiment, the detection output ITV
O, FTVO, and the state in which the slope y is calculated,
It is assumed that the detection variation learning of the throttle sensor 13a has been completed. In step 24, the opening TVO in which the detection variation is corrected is calculated as follows based on the detection output of the throttle sensor 13a at that time, the detection output ITVO at the fully closed position, and the inclination y. To do.

Opening TVO ← (detection output-ITVO) / inclination y In step 5, the calculation in step 24 is performed. When variation learning is completed, the opening calculated in step 24 is used as a reference. When the opening is ATVO or more, altitude determination is performed. Thus, in the system including the idle switch 13b and the full switch 13c, the idle switch 13a is in the ON state and the full switch 13c is in the O state.
By experiencing both N state, throttle sensor 13
The variation in the detection characteristic of a can be easily learned.

[0036]

As described above, according to the altitude determination device for an internal combustion engine according to the first aspect of the invention, the accuracy of detecting the opening area of the engine intake system is poor, and the intake air flow rate as the volume flow rate is estimated. There is an effect that it is possible to avoid that the altitude is erroneously determined when the accuracy is low.

In the altitude determination device according to the second aspect of the present invention, when the learning error of the detection error of the means for detecting the throttle valve opening indicating the opening area is corrected, the opening range for the altitude determination is made lower. Since the shift is made to the opening side, there is an effect that it is possible to secure an opportunity to make an altitude determination without deteriorating the detection accuracy.

In the altitude determining device according to the third aspect of the present invention, there is an effect that learning of the detection error of the throttle valve opening can be easily performed by using an idle switch and a full switch.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of an apparatus according to the invention of claim 1.

FIG. 2 is a system configuration diagram of an embodiment of the present invention.

FIG. 3 is a flowchart showing altitude determination control according to the embodiment.

FIG. 4 is a flowchart showing variation learning of opening degree detection in the embodiment.

FIG. 5 is a diagram showing variations in the output of the throttle sensor.

FIG. 6 is a diagram showing variations in opening detection due to variations in output.

[Explanation of symbols]

 1 Internal Combustion Engine 9 Throttle Valve 11 Crank Angle Sensor 12 Air Flow Meter 13a Throttle Sensor 13b Idle Switch 13c Full Switch 17 Control Unit

Claims (3)

[Claims] 1. A rotation speed detecting means for detecting a rotation speed of an engine, an opening area detecting means for detecting an opening area of an engine intake system which is variably controlled, and an intake air for detecting an intake air flow rate of the engine as a mass flow rate. Flow rate detecting means, intake air flow rate estimating means for estimating and calculating the intake air flow rate of the engine based on the detected rotational speed and opening area, and the opening area detected by the opening area detecting means is a predetermined reference area. Only when the above is true, the altitude determination means for determining the altitude based on the intake air flow rate detected by the intake air flow rate detection means and the intake air flow rate estimated by the intake air flow rate estimation means is included. An altitude determination device in an internal combustion engine, which is configured. 2. The opening area detecting means includes a throttle valve opening detecting means for continuously detecting the opening degree of a throttle valve installed in an engine intake system, while the throttle valve opening degree is provided. A detection error learning correction unit for learning and correcting the detection error of the detection unit is provided, and the altitude determination unit sets the altitude when the throttle valve opening detected by the throttle valve opening detection unit is equal to or larger than a predetermined reference opening. When the detection error learning correction means corrects the detection error of the throttle valve opening detection means while making the determination of the opening area condition, the reference opening degree is lower than that in the non-learning correction time. The altitude determination device for an internal combustion engine according to claim 1, wherein the altitude determination device is configured to shift to the side. 3. An idle switch which is turned on when the throttle valve is fully closed and an O switch when the throttle valve is fully opened.
N full switch is provided, and the detection error learning correction means turns on the idle switch and the full switch.
The altitude determination device for an internal combustion engine according to claim 2, wherein the detection error of the throttle valve opening detection means is learned and corrected based on the detection value of the throttle valve opening detection means at each OFF switching.