JP2007327364A - Stop position control system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the accuracy of stop position control by optimizing the magnitude of a compressive reaction force in a stop position control system of an internal combustion engine for stopping a crankshaft in the range of a desired target crank angle when the internal combustion engine is stopped. <P>SOLUTION: In this stop position control system of an internal combustion engine for controlling the opening of a throttle valve to a desired target opening when the stop position control of the internal combustion engine is performed, the density of the air sucked into the internal combustion engine when the stop position control is performed is detected, the density is so corrected that the higher the detected density is, the smaller the target opening is, i.e., and the density is so corrected that the lower the detected density is, the larger the target opening is. Consequently, the magnitude of the compressive reaction is nearly constant even under any use environment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for stopping a crankshaft at a desired position when the operation of an internal combustion engine is stopped.

  In recent years, in order to improve the restartability of an internal combustion engine mounted on a vehicle or the like, development of a technique for stopping the crankshaft in a desired target crank angle range has been advanced. In this type of technology, if the compression reaction force of the intake air becomes large when the operation of the internal combustion engine is stopped, there is a possibility that an increase in vibration or a variation in the stop position of the crankshaft may occur.

On the other hand, a technique for reducing the compression reaction force as much as possible by reducing the opening of the throttle valve when the operation of the internal combustion engine is stopped has been proposed (see, for example, Patent Document 1).
JP 2000-257458 A European Patent Application Publication No. 1367246

  By the way, the magnitude of the compression reaction force changes in accordance with the density of air taken into the internal combustion engine (hereinafter referred to as “intake density”). However, since the opening degree of the throttle valve is determined without considering the intake air density in the conventional technology, the magnitude of the compression reaction force may be excessive or excessive. If the magnitude of the compression reaction force becomes too large or too small, the crankshaft may not stop within the target crank angle range.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a compression position control system for an internal combustion engine that stops a crankshaft in a desired target crank angle range when the operation of the internal combustion engine is stopped. It is to improve the accuracy of the stop position control by optimizing the magnitude of the reaction force.

  In order to solve the above-described problems, the present invention provides a stop position control system for an internal combustion engine that controls the opening degree of a throttle valve to a desired target opening degree when the stop position control of the internal combustion engine is performed. Thus, by correcting the target opening degree, the magnitude of the compression reaction force is suppressed from becoming an unexpected magnitude.

  Specifically, the present invention relates to a stop position control system for an internal combustion engine that controls the opening of a throttle valve to a predetermined target opening when stop position control is performed to stop the crankshaft of the internal combustion engine within a target crank angle range. And detecting means for detecting the density of air sucked into the internal combustion engine, and correcting means for correcting the target opening degree according to the density detected by the detecting means.

  If the opening of the throttle valve fluctuates during the period from when the combustion of the internal combustion engine is stopped until the rotation of the crankshaft stops, the intake pipe negative pressure and compression reaction force become unstable. May deviate from the target crank angle range.

  For this reason, it is preferable that the opening degree of the throttle valve is fixed to a predetermined target opening degree during the above period. By the way, since the use environment of an internal combustion engine is various, the said target opening degree may become inadequate.

  For example, when the internal combustion engine is used at a high altitude or at a high temperature, the intake air density is different between the internal combustion engine at a low altitude or at a low temperature. If set to, the magnitude of the compression reaction force may be excessively large or small.

  On the other hand, if the target opening is corrected according to the intake air density, the compression reaction force can be made substantially constant under any use environment, so the probability that the crankshaft will stop within the target crank angle range is increased. Can be increased.

  In the present invention, the correction means corrects the target opening of the throttle valve to become smaller as the intake density detected by the detecting means becomes higher, and the target opening of the throttle valve becomes lower as the intake density detected by the detecting means becomes lower. You may make it correct | amend so that may become large.

  The magnitude of the compression reaction force increases as the mass of air sucked into the internal combustion engine (hereinafter simply referred to as “intake air amount”) increases and decreases as the intake air amount of the internal combustion engine decreases. Further, the intake air amount of the internal combustion engine increases as the intake air density increases, and decreases as the intake air density decreases.

  Therefore, if the target opening degree of the throttle valve opening is made smaller as the intake air density detected by the detecting means becomes higher, an unnecessary increase in the intake air amount is suppressed, so that the compression reaction force may become excessive. It is suppressed.

  On the other hand, if the target opening degree of the throttle valve opening is increased as the intake air density detected by the detecting means becomes lower, an unnecessary decrease in the intake air amount is suppressed, so that the compression reaction force may become too small. It is suppressed.

  The detection means according to the present invention may detect the atmospheric pressure and the intake air temperature as physical quantities correlated with the intake air density. In this case, the correction means performs correction so that the target opening of the throttle valve becomes smaller as the atmospheric pressure detected by the detection means becomes higher and the intake air temperature becomes lower, and the atmospheric pressure detected by the detection means becomes lower and the intake air becomes lower. Correction may be made so that the target opening of the throttle valve increases as the temperature increases.

  According to the present invention, in the stop position control system for an internal combustion engine that stops the crankshaft in a desired target crank angle range when the operation of the internal combustion engine is stopped, the compression reaction force of the intake air can be optimized. The accuracy of stop position control can be improved.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied.

  The internal combustion engine shown in FIG. 1 is a 4-stroke cycle spark ignition internal combustion engine (gasoline engine) having a plurality of cylinders 2. An intake passage 3 and an exhaust passage 4 communicate with the cylinder 2 of the internal combustion engine 1.

A fuel injection valve 5 that injects fuel into the cylinder 2 is provided in the intake passage 3. Further, the intake passage 3 is provided with a throttle valve 6 for controlling the amount of air flowing through the intake passage 3. In the intake passage 3 upstream of the throttle valve 6, an intake air temperature sensor 7 that outputs an electrical signal corresponding to the temperature of the air flowing through the intake passage 3 (intake air temperature), and the intake air flowing through the intake passage 3 An atmospheric pressure sensor 18 for outputting an electrical signal corresponding to the pressure (atmospheric pressure) is provided.

  Further, the internal combustion engine 1 is provided with an intake valve 8 that opens and closes an open end of the intake passage 3 facing the cylinder 2 and an exhaust valve 9 that opens and closes an open end of the exhaust passage 4 facing the cylinder 2. The intake valve 8 and the exhaust valve 9 are driven to open and close by an intake camshaft 10 and an exhaust camshaft 11, respectively.

  A spark plug 12 for igniting the air-fuel mixture flowing into the cylinder 2 is disposed at the upper part of the cylinder 2. A piston 13 is slidably provided in the cylinder 2. The piston 13 is connected to the crankshaft 15 via a connecting rod 14. A crank position sensor 16 that detects a rotation angle of the crankshaft 15 is disposed in the internal combustion engine 1 in the vicinity of the crankshaft 15.

  The internal combustion engine 1 configured as described above is provided with an ECU 17. The ECU 17 is an electronic control unit that includes a CPU, a ROM, a RAM, and the like. Measurement values of various sensors such as the intake air temperature sensor 7, the atmospheric pressure sensor 18, and the crank position sensor 16 described above are input to the ECU 17.

  The ECU 17 controls the fuel injection valve 5, the throttle valve 6, and the spark plug 12 based on the measurement values of the various sensors described above. For example, the ECU 17 performs stop position control for stopping the crankshaft 15 in a desired target crank angle range when the operation stop condition of the internal combustion engine 1 is satisfied.

  Hereinafter, stop position control in the present embodiment will be described.

  The stop position of the crankshaft 15 is determined according to the magnitude of the inertia energy that the crankshaft 15 has when the combustion of the internal combustion engine 1 is stopped. The magnitude of the inertia energy correlates with the engine speed at the time of combustion stop (hereinafter referred to as “combustion stop speed”). For this reason, it can be said that the stop position of the crankshaft 15 correlates with the combustion stop rotational speed.

  Therefore, when the combustion of the internal combustion engine 1 is stopped when the engine speed is in a specific range, the crankshaft 15 stops in a substantially constant crank angle range.

  Therefore, when the operation stop condition of the internal combustion engine 1 is satisfied, the ECU 17 stops the combustion of the internal combustion engine 1 after converging the engine speed to a predetermined combustion stop speed range. Specifically, as shown in FIG. 2, the ECU 17 converges the engine speed to a predetermined combustion stop speed range A when the operation stop condition of the internal combustion engine 1 is satisfied (t1 in FIG. 2). Rotational speed control is started accordingly.

  As a method for carrying out the rotational speed control, a method for converging the engine rotational speed to the combustion stop rotational speed range A by adjusting the opening degree of the throttle valve 6, or an engine rotational speed by adjusting the ignition timing of the spark plug 12. Can be exemplified as a method of converging to the combustion stop rotational speed range A.

  When the engine speed converges to the combustion stop speed range A by the above-described method (t2 in FIG. 2), the ECU 17 stops the combustion of the internal combustion engine 1 by stopping the operation of the fuel injection valve 5 and the spark plug 12. Stop.

  By the way, if the opening of the throttle valve 6 fluctuates after the combustion of the internal combustion engine 1 is stopped, the magnitude of the rotational resistance of the crankshaft 15 (force against the rotation of the crankshaft) fluctuates, so the stop position of the crankshaft 15 is There is a possibility of deviating from the target crank angle range.

  For this reason, it is preferable that the opening degree of the throttle valve 6 is fixed to a predetermined target opening degree after the combustion of the internal combustion engine 1 is stopped. Furthermore, it is preferable that the target opening degree is as small as possible. This is because, when the opening of the throttle valve 6 is made relatively large after the combustion of the internal combustion engine 1 is stopped, the compression reaction force of the intake air increases, so that the vibration of the internal combustion engine 1 increases and the stop position of the crankshaft 15 is increased. This is because there is a possibility of deviating from the target crank angle range.

  It should be noted that the magnitude of the compression reaction force described above varies depending on the use environment of the internal combustion engine 1 even if the opening degree of the throttle valve 6 is equal. For example, when the internal combustion engine 1 is used at a high altitude or at a high temperature, the compression reaction force becomes small because the intake air density becomes low. On the other hand, when the internal combustion engine 1 is used at a low altitude or at a low temperature, since the intake air density becomes high, the compression reaction force increases.

  Therefore, when the internal combustion engine 1 is used at a high altitude or at a high temperature, the target opening degree is set to be equal when the internal combustion engine 1 is used at a low altitude or at a low temperature. Then, there is a possibility that the magnitude of the compression reaction force is excessively large or small.

  Therefore, in the stop position control of this embodiment, the ECU 17 corrects the target opening of the throttle valve 6 after the combustion of the internal combustion engine 1 is stopped according to the intake density. Since the intake air density correlates with the atmospheric pressure and the intake air temperature, the ECU 17 corrects the target opening based on the measured value of the intake air temperature sensor 7 (intake air temperature) and the measured value of the atmospheric pressure sensor 18 (atmospheric pressure). To do.

  FIG. 3 shows a map that defines the relationship among the intake air temperature, the atmospheric pressure, and the target opening of the throttle valve 6. The intake air density increases as the intake air temperature decreases and the atmospheric pressure increases, and decreases as the intake air temperature increases and the atmospheric pressure decreases. For this reason, in the map of FIG. 3, the target opening of the throttle valve 6 is set to be smaller as the intake air temperature is lower and the atmospheric pressure is higher, and to be larger as the intake air temperature is higher and the atmospheric pressure is lower. .

  When the target opening of the throttle valve 6 after the combustion stop of the internal combustion engine 1 is determined as described above, the compression reaction force is made substantially constant regardless of the environment in which the internal combustion engine 1 is used. Can do. As a result, the probability that the crankshaft 15 stops within the target crank angle range increases.

  Next, the flow of stop position control of the present embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing a stop position control routine in the present embodiment. The stop position control routine is a routine stored in advance in the ROM of the ECU 17 and is repeatedly executed by the ECU 17 at predetermined intervals.

  In the stop position control routine of FIG. 4, the ECU 17 first determines in S101 whether or not an operation stop condition for the internal combustion engine 1 is satisfied. Examples of the operation stop condition of the internal combustion engine 1 include a manual stop condition (manual operation of turning off the ignition switch) and establishment of an idle stop condition.

  If a negative determination is made in S101, the ECU 17 once ends the execution of this routine. On the other hand, if an affirmative determination is made in S101, the ECU 17 proceeds to S102.

In S102, the ECU 17 reads the measured value (atmospheric pressure) of the atmospheric pressure sensor 18. Next, the ECU 17 reads the measured value (intake air temperature) of the intake air temperature sensor 7 in S103.

  In S104, the ECU 17 calculates the target opening degree θth of the throttle valve 6. Specifically, the ECU 17 calculates the target opening θth based on the atmospheric pressure read in S102, the intake air temperature read in S103, and the map of FIG.

  In S105, the ECU 17 starts executing the rotational speed control so as to converge the engine rotational speed to the combustion stop rotational speed range A.

  In S106, the ECU 17 determines whether or not the engine rotational speed Ne has converged to the combustion stop rotational speed range A. Specifically, the ECU 17 determines whether or not the engine speed Ne is not less than the lower limit value Nemin and not more than the upper limit value Nemax of the combustion stop speed range A.

  If a negative determination is made in S106, the ECU 17 proceeds to S109 and controls the throttle opening to the opening θidl during idling. When the rotation speed control is performed by adjusting the opening degree of the throttle valve 6, the ECU 17 controls the throttle valve 6 based on the opening degree determined in the rotation speed control.

  If an affirmative determination is made in S106, the ECU 17 proceeds to S107. In S107, the ECU 17 stops the combustion of the internal combustion engine 1 by stopping the operation of the fuel injection valve 5 and the spark plug 12.

  In S108, the ECU 17 controls the throttle valve 6 so that the opening of the throttle valve 6 becomes the target opening θth calculated in S104.

  As described above, the ECU 17 executes the stop position control routine of FIG. 4 to realize the detecting means and the correcting means according to the present invention.

  Therefore, according to the stop position control of the present embodiment, the magnitude of the compression reaction force after the combustion stop of the internal combustion engine 1 becomes substantially constant regardless of the environment in which the internal combustion engine 1 is used. As a result, the probability that the crankshaft 15 stops within the target crank angle range can be increased.

1 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied. It is a figure which shows the behavior of the engine speed at the time of stop position control execution. It is a figure which shows the map which prescribed | regulated the relationship between atmospheric pressure, intake temperature, and the opening degree of a throttle valve. It is a flowchart which shows the stop position control routine in a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 6 ... Throttle valve 7 ... Intake temperature sensor 12 ... Spark plug 15 ... Crankshaft 16 ...・ Crank position sensor 17 ・ ・ ・ ・ ECU
18 .... Atmospheric pressure sensor

Claims (2)

In a stop position control system for an internal combustion engine that controls the opening of a throttle valve to a predetermined target opening when stop position control for stopping the crankshaft of the internal combustion engine within a target crank angle range is performed,
Detecting means for detecting the density of air sucked into the internal combustion engine;
Correction means for correcting the target opening according to the density detected by the detection means;
An internal combustion engine stop position control system comprising:   2. The correction means according to claim 1, wherein the correction is performed so that the target opening becomes smaller as the density detected by the detection means becomes higher, and the target opening becomes larger as the density detected by the detection means becomes lower. A stop position control system for an internal combustion engine, wherein correction is performed so that

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