JPH09177591A - Atmospheric pressure estimating device in internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate the atmospheric pressure with a high precision without being influenced by the detection error of throttle valve opening even when it is large. SOLUTION: When the feedback control of idling speed is under execution, cooling water temperature is a prescribed value or more, and a battery voltage is within a prescribed range, it is judged that an atmospheric pressure estimating condition is established (S1), the opening average value ISC1 for a prescribed period of an ISC valve is calculated (S3) in the state where an external load is forcedly OFF (S2). The opening average value ISC2 within a prescribed period of the ISC valve is calculated (S5) in the state where the external load is forcedly ON (S4). Thereafter, the external load is returned to the state before main routine execution (S6), intake air temperature is read (S7), the opening deviation (ISC2-ISC1) of the ISC valve changed by ON/OFF of the external load is divided by the intake air temperature, and the atmospheric pressure is estimated in reference to a map or by arithmetic operation on the basis of this value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine provided with a fuel supply device for setting a basic fuel supply amount based on, for example, an intake air flow rate to the engine, and more particularly to a large amount necessary for correcting the fuel supply amount and the like. The present invention relates to a technique for estimating atmospheric pressure.

[0002]

2. Description of the Related Art Conventionally, as an electronically controlled fuel supply device for an internal combustion engine, there is one that sets a basic fuel supply amount based on the intake air flow rate to the engine (referred to as an L-JETRO system). That is, based on the intake air flow rate, the fuel supply amount corresponding to the intake charging efficiency is set by correction based on the intake temperature, etc., and an injection pulse signal corresponding to the fuel supply amount is output to the electromagnetic fuel injection valve to output the fuel. The supply is controlled.

By the way, when correcting the fuel supply amount in consideration of the intake charging efficiency, it is necessary to detect the atmospheric pressure which changes depending on the altitude at which the vehicle is traveling. As a method of detecting the atmospheric pressure, 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 detecting the atmospheric pressure. Therefore, as a method of estimating the atmospheric pressure using an existing sensor, an intake air flow rate to the engine detected as a mass flow rate by an air flow meter, and a volume flow rate obtained from the opening degree of the throttle valve and the engine rotation speed are used. A method for estimating the atmospheric pressure from the intake air flow rate and the intake air temperature by calculation has been developed (see the flowchart of FIG. 5; details will be described later).

[0004]

However, in the potentiometer type throttle sensor generally used for detecting the opening of the throttle valve, the allowable range of variation in sensor output with respect to the opening of the throttle valve is defined as shown in FIG. In such a case, as shown in FIG. 7, 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
Due to the detection error of the throttle valve opening, there is a large error particularly on the low opening side, and there is a risk that the atmospheric pressure estimation accuracy using the intake air flow rate as the volume flow rate may be reduced. Therefore, in view of the above conventional problems, the present invention provides a large internal combustion engine capable of highly accurately estimating the atmospheric pressure without being affected by the detection error even when the throttle valve opening detection error is large. An object is to provide an atmospheric pressure estimation device.

[0006]

Therefore, according to the invention described in claim 1, as shown in FIG. 1, the idle rotation speed for performing feedback correction control of the intake air flow rate so as to attain the target rotation speed during the idle operation of the engine. A control means A and an external load B whose intake air flow rate changes according to the operating state,
An external load control means C for controlling the operation of the external load,
Estimating condition determining means D for determining whether a condition for estimating the atmospheric pressure including an idle operating condition is satisfied, and the external load control means for determining when the atmospheric pressure estimating condition is satisfied. Deviation calculating means E for changing the operating state of the external load and calculating a deviation of a value related to the correction amount of the intake air flow rate during the operation and non-operation of the external load within a predetermined period, and based on the deviation And an atmospheric pressure estimating means F for estimating the atmospheric pressure.

With this configuration, when it is determined by the estimation condition determination means that the atmospheric pressure estimation condition is satisfied,
The external load is turned ON / OFF by the external load control means,
The atmospheric pressure is accurately estimated by the atmospheric pressure estimating means based on the deviation of the value related to the intake air flow rate correction amount when the external load is turned on / off. The invention according to claim 2 is provided with an intake air temperature detecting means for detecting an intake air temperature of intake air to the engine, and the atmospheric pressure estimating means detects the deviation calculated by the deviation calculating means and the intake temperature detecting means. The atmospheric pressure is estimated based on the intake air temperature obtained.

With this configuration, since the atmospheric pressure is estimated based on the intake air temperature in addition to the deviation calculated by the deviation calculating means, temperature correction is performed in consideration of the volume flow rate change that changes according to the intake air temperature. , The atmospheric pressure estimation accuracy is improved.
The invention according to claim 3 is provided with an engine temperature detecting means for detecting an engine temperature and a voltage detecting means for detecting a voltage between terminals of a battery, and the estimation condition determining means is a feedback by the idle rotation speed control means. When the correction control is being performed, the engine temperature is equal to or higher than the predetermined value, and the terminal voltage is within the predetermined range, it is determined that the atmospheric pressure estimation condition is satisfied.

With this configuration, it is possible to determine the state where the feedback correction control of the stable idle rotation speed is being performed while the warm-up operation of the engine is completed and the battery voltage is stable. External load ON / OFF
The change in the intake air flow rate due to is accurately calculated. In the invention according to claim 4, the deviation calculated by the deviation calculating means is a deviation of an average value of the feedback correction amount.

In this way, the deviation of the average value of the feedback correction amount during the operation and non-operation of the external load within the predetermined period is calculated, and the atmospheric pressure is estimated with high accuracy based on this deviation. In the invention according to claim 5, the deviation calculated by the deviation calculating means is a deviation of an average value of the intake air flow rate required by the engine.

In this way, the deviation of the average value of the intake air flow rate required by the engine during the operation and non-operation of the external load within the predetermined period is calculated, and the atmospheric pressure is accurately calculated based on this deviation. Presumed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In FIG. 2 showing a system configuration of an embodiment of an atmospheric pressure estimation device according to the present invention, an internal combustion engine 1
Air is taken into the air through the air cleaner 2, the intake duct 3, and the intake manifold 4. And the intake duct 3
Is provided with a throttle valve 5 which opens and closes in conjunction with an accelerator pedal (not shown), and the throttle valve 5 adjusts the flow rate of intake air to the internal combustion engine 1.

Further, an auxiliary air passage 6 for bypassing the throttle valve 5 interposed in the intake duct 3 is provided, and the opening / closing of the auxiliary air passage 6 is duty-controlled by a control unit 9 containing a microcomputer. An electromagnetic idle control valve 7 is installed. On the other hand, the intake manifold 4 is provided with an electromagnetic fuel injection valve 8 for each cylinder. This fuel injection valve 8
Supplies fuel whose pressure is adjusted to a predetermined pressure by a pressure regulator (not shown) to the engine intermittently in response to an injection pulse signal from the control unit 9.

Here, output signals from various sensors are input to the control unit 9 in order to determine drive pulse signals to the idle control valve 7 and the fuel injection valve 8, respectively. As these various sensors, an intake air temperature sensor 10 (intake air temperature detecting means) for detecting an intake air temperature T sucked into the engine, a hot wire type air flow meter 11 for detecting an intake air flow rate Q to the engine, and a throttle valve 5 are attached. The throttle sensor 12 for detecting the opening TVO of the throttle valve 5 and the idle switch 13 which is turned on at the idle position (fully closed position) of the throttle valve 5, the rotation for extracting the rotation signal from the crankshaft and detecting the engine rotation speed Ne. speed sensor 14, a water temperature sensor 15 for detecting the cooling water temperature T _W representing the provided engine temperature to the water jacket of the internal combustion engine 1 (engine temperature detector), and the terminal voltage of the vehicle battery (not shown) A voltage sensor 16 (voltage detecting means) for detecting V _B is provided.

Besides this, the magnitude of the load is substantially constant.
The required intake air flow rate Q to the engine changes depending on the operating condition.
Externalizing air conditioners and rear defoggers
The load 17 is controlled by the control unit 9.
ing. And idle control in such a system
The valve 7 is for idle operation in which the idle switch 13 is turned on.
During rotation, the engine speed detected by the rotation speed sensor 14
Cooling speed Ne detected by water temperature sensor 15
Water temperature T_WClose to the target rotation speed Ne 'set based on
The control signal from the control unit 9
Feedback control that opens and closes is being performed. this
Opening and closing control is performed by turning on the signal from the idle switch 13.
In a predetermined idle state, the cooling water temperature T _W, Engine rotation
Battery detected by speed Ne and voltage sensor 16
Revoltage V_BThe control unit 9
The duty ratio of the pulse signal supplied to the idle control valve 7
It is done by changing.

Further, the control unit 9 calculates the basic fuel supply amount T _P based on the detected intake air flow rate Q and the engine rotation speed Ne, and further, the cooling water temperature T _W and the estimated atmospheric pressure Pa, etc. The effective fuel supply amount Te is calculated by performing the correction in consideration of the intake charging efficiency, and the injection pulse signal corresponding to the effective fuel supply amount Te is supplied to the fuel injection valve 8.

The control unit 9 has a function as an estimation condition determination means, an external load control means, a deviation calculation means and an atmospheric pressure estimation means, and the control unit 9, the auxiliary air passage 6 and the idle control. Valve 7
The idle rotation speed control means is configured to include.
Here, in order to clarify the problems of the conventional atmospheric pressure estimation process and to clarify the necessity of the present invention, the conventional atmospheric pressure estimation process will be described below with reference to the flowchart of FIG.

In step 10 (abbreviated as S10 in the drawing; the same applies hereinafter), the throttle opening TVO is read from the throttle sensor 12. In step 11, the engine rotation speed Ne is read from the rotation speed sensor 14. In step 12, the map or the like in which the volume flow rate (intake air flow rate) V to the engine is stored in advance using the throttle opening TVO and the engine rotation speed Ne as parameters, and the throttle opening TVO and the throttle opening TVO read in steps 10 and 11 are referred to. The volume flow rate V is searched based on the engine rotation speed Ne.

In step 13, the air flow meter 11
Read the mass flow rate (intake air flow rate) Q from the engine to the engine.
In step 14, the intake air temperature T is read from the intake air temperature sensor 10. In step 15, the atmospheric pressure Pa is estimated by the following equation based on the retrieved volumetric flow rate V, read mass flow rate Q, and intake air temperature T.

Pa = func (Q · T / V) where func (x) is the atmospheric pressure Pa with x as a parameter.
Shows a function or a map for obtaining By performing such atmospheric pressure estimation processing, the atmospheric pressure can be estimated without newly providing an expensive atmospheric pressure sensor. However, as described above, when the throttle valve 5 is at a low opening, the throttle sensor 1
Since the opening degree detection error of 2 is large, the accuracy of the volume flow rate V decreases, and as a result, the estimation accuracy of the atmospheric pressure Pa decreases.

Therefore, according to the present invention, the atmospheric pressure estimation process of the flowchart shown in FIG. 3 is performed in addition to the atmospheric pressure estimation process shown in FIG. The pressure can be estimated. Hereinafter, the details of the atmospheric pressure estimation processing according to the present invention will be described in detail. This atmospheric pressure estimation process is performed by forcibly turning on / off external loads such as the air conditioner and the rear defogger during idle operation when the engine load is almost constant, and the intake air flow rate (auxiliary This is done by paying attention to the fact that the air flow rate Q changes, and in particular, if the above operation is performed during the feedback control of the stable idle rotation speed, the atmospheric pressure can be estimated with high accuracy.

In step 1, it is judged whether or not the conditions for estimating the atmospheric pressure are satisfied. Specifically, the feedback control of the idle rotation speed is being executed, the cooling water temperature T _W detected by the water temperature sensor 15 is equal to or higher than a predetermined value (T _W ≧ T ₁ ), and is detected by the voltage sensor 16. The battery voltage V _B is within a predetermined range (V ₁ ≦ V
_{When B} ≤ V ₂ ) it is determined that the atmospheric pressure can be estimated. The reason is that the idle speed is considered to be stable when the engine warm-up operation is completed and the battery voltage is stable. In such a state, the idle load is turned ON / OFF by the external load. This is because the opening degree of the control valve 7 is controlled with high accuracy and the atmospheric pressure estimation accuracy is improved. Then, if the estimation condition is satisfied, the process proceeds to step 2, and if the estimation condition is not satisfied, the process of step 1 is repeated until it is satisfied. The process of step 1 corresponds to the estimation condition determining means.

In step 2, the external load 17 such as the air conditioner and the rear defogger is forcibly turned off. The external load 17 is not limited to the air conditioner or the rear defogger, and may be any known load whose load is substantially constant. In step 3, the opening degree average value ISC1 of the idle control valve (ISC valve) 7 within a predetermined period when the external load 17 is OFF is calculated.
This is because the rotation fluctuation is taken into consideration, and the idle control valve 7
The average opening degree value ISC1 can be obtained from the average value of the duty ratios of the drive pulse signals to the.

In step 4, the external load 17 such as the air conditioner and the rear defogger is forcibly turned on. In step 5, the opening average value ISC2 of the idle control valve (ISC valve) 7 within a predetermined period when the external load 17 is ON is calculated. In step 6, the external load 17 is returned to the state before execution of this routine. In this process, when the atmospheric pressure is estimated, the external load 17 automatically turns O
This is done in order to avoid leaving N (when the initial state is OFF).

In step 7, the intake air temperature T is read from the intake air temperature sensor 10. In step 8, while the external load 17 is ON / OFF, the changed opening degree deviation (ISC2-ISC1) of the idle control valve 7 is divided by the intake air temperature T, and based on this value, atmospheric pressure is obtained by referring to or calculating a map or the like. Pa
Is estimated. Here, the reason why it is divided by the intake air temperature T is that the opening deviation (ISC2-ISC1) is temperature-corrected and the volume flow rate change due to temperature is removed. The processing in step 8 (second half) corresponds to the atmospheric pressure estimating means, and the processing in steps 2 to 8 (first half) also corresponds to the deviation calculating means.

According to the atmospheric pressure estimation process described above, the atmospheric pressure estimation can be performed with high accuracy without being affected by the detection error of the throttle valve opening during the idling operation, where the conventional atmospheric pressure estimation cannot be performed with high accuracy. You will be able to do it. Further, since the atmospheric pressure can be estimated by the existing sensor, the cost does not increase due to the addition of new parts. Therefore, by using the atmospheric pressure estimation process according to the present invention together with the conventional atmospheric pressure estimation process, the atmospheric pressure estimation can be performed with high accuracy over the entire opening of the throttle valve 7.

Next, the atmospheric pressure estimation processing in which a part of the flowchart of FIG. 3 is modified is shown in the flowchart of FIG.
This uses the average value of the feedback correction amount [ISC control I portion (integration portion)] in the idle rotation speed control instead of the average opening degree value of the idle control valve 7 within a predetermined period. The steps different from the atmospheric pressure estimation processing shown in the flowchart of FIG. 3 will be briefly described below.

In step 3 ', the external load 17 is turned off.
In this state, the average value ISC1 for the ISC control I within the predetermined period is calculated. In step 4, the external load 17 is forcibly turned on. In step 5 ', the external load 17
The average value ISC2 for the ISC control I within the predetermined period in the state where is ON is calculated.

The effect of such atmospheric pressure estimation processing is shown in FIG.
Since it is the same as that of the flowchart of FIG. In the present embodiment, the average value of the opening degree of the idle control valve 7 or the average value of the ISC control I is used, but the present invention is not limited to this, and for example, the idle control valve 7 such as the intake air flow rate required by the engine may be used. Any value that correlates with the motion may be used.

[0030]

As described above, according to the first aspect of the invention, when the estimation condition determining means determines that the atmospheric pressure estimation condition is satisfied, the external load control means controls the external load. ON / OFF, external load ON / O
Since the atmospheric pressure is estimated by the atmospheric pressure estimation means based on the deviation of the value related to the intake air flow rate correction amount during FF,
In the idling operation where the atmospheric pressure could not be estimated with high accuracy in the past, the detection error of the throttle valve opening was not affected,
The atmospheric pressure can be estimated with high accuracy. That is, if the atmospheric pressure estimation according to the present invention is performed separately from the conventional atmospheric pressure estimation, the atmospheric pressure can be estimated with high accuracy over the entire opening of the throttle valve.

Further, since the atmospheric pressure is estimated by the existing sensor, there is no increase in cost due to the addition of new parts. According to the second aspect of the invention, temperature correction for the volumetric flow rate change that changes with temperature is performed based on the detected intake air temperature, so the atmospheric pressure estimation accuracy can be improved.

According to the third aspect of the present invention, the atmospheric pressure is estimated only when the feedback correction control of the idle rotation speed is being stably performed, so that the external load is turned on / off. The change in the intake air flow rate due to OFF is calculated with high accuracy, and thus the atmospheric pressure estimation accuracy can be further improved. According to the invention described in claims 4 and 5, the average value of the feedback correction amount is defined as the deviation of the average value of the values related to the correction amount of the intake air flow rate during the operation and the non-operation of the external load within the predetermined period. Of the intake air flow rate, or the deviation of the average value of the intake air flow rate required by the engine, the atmospheric pressure can be estimated with high accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claim 1 of the present invention.

FIG. 2 is a system configuration diagram showing an embodiment of an atmospheric pressure estimation device according to the present invention.

FIG. 3 is a flowchart showing an atmospheric pressure estimation process of the above.

FIG. 4 is a flowchart showing another atmospheric pressure estimation process of the above.

FIG. 5 is a flowchart showing a conventional atmospheric pressure estimation process.

FIG. 6 is a diagram showing an output variation of the throttle sensor.

FIG. 7 is a diagram showing variations in opening detection due to variations in output.

[Explanation of symbols]

 1 Internal Combustion Engine 6 Auxiliary Air Passage 7 Idle Control Valve 9 Control Unit 10 Intake Temperature Sensor 15 Water Temperature Sensor 16 Voltage Sensor 17 External Load

Claims (5)

[Claims] 1. An idle rotation speed control means for performing feedback correction control of an intake air flow rate so as to attain a target rotation speed during idle operation of an engine, an external load that changes the intake air flow rate according to an operating state, and the external load. External load control means for controlling the operation of the load, estimation condition determination means for determining whether conditions for estimating the atmospheric pressure including idle operating conditions are satisfied, and determination is made that the atmospheric pressure estimation conditions are satisfied. When the external load is controlled, the external load control means changes the operating state of the external load to calculate a deviation of a value related to the correction amount of the intake air flow rate during the operation and the non-operation of the external load within a predetermined period. And an atmospheric pressure estimating unit for estimating the atmospheric pressure based on the deviation. 2. An intake air temperature detecting means for detecting an intake air temperature of intake air to the engine, wherein the atmospheric pressure estimating means includes the deviation calculated by the deviation calculating means and the intake air detected by the intake temperature detecting means. The atmospheric pressure estimation device for an internal combustion engine according to claim 1, wherein the atmospheric pressure is estimated based on the temperature. 3. An engine temperature detecting means for detecting an engine temperature,
A voltage detection unit that detects a voltage between terminals of the battery, wherein the estimation condition determination unit is in feedback correction control by the idle rotation speed control unit, the engine temperature is equal to or higher than a predetermined value, and The atmospheric pressure estimation device for an internal combustion engine according to claim 1 or 2, wherein it is determined that the atmospheric pressure estimation condition is satisfied when the voltage is within a predetermined range. 4. The atmospheric pressure estimation in an internal combustion engine according to claim 1, wherein the deviation calculated by the deviation calculating means is a deviation of an average value of the feedback correction amount. apparatus. 5. The internal combustion engine according to claim 1, wherein the deviation calculated by the deviation calculating means is a deviation of an average value of an intake air flow rate required by the engine. Atmospheric pressure estimation device in.