JP4491739B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that calculates the rotational speed of the internal combustion engine.

In general, in an engine (internal combustion engine) control system, an engine rotation speed is calculated at a predetermined period in order to grasp an engine operating state, and is described in, for example, Patent Document 1 (Japanese Patent No. 3490541). In addition, every time the crankshaft of the engine rotates by a predetermined crank angle, the time difference of each pulse signal output from the sensor is calculated, and a certain number of time differences corresponding to one stroke of the engine (ie, 180 ° C. A) is obtained. By calculating the engine rotation speed based on the sum total calculated value (that is, the time required for one stroke), the influence of the sparseness of the pulse signal generation frequency during one stroke (the fluctuation of the pulse signal generation cycle) is averaged. There is one that calculates the engine speed.
Japanese Patent No. 3490541 (first page, etc.)

  In recent years, in order to further improve the fuel consumption, exhaust emission, drivability, etc. of the engine, it has been required to accurately control the combustion state and generated torque of the engine. It is necessary to accurately grasp the actual combustion state and generated torque.

  In general, since the generated torque changes according to the combustion state of the engine and the engine rotational speed changes, the engine rotational speed becomes information for evaluating the combustion state and the generated torque. However, in the technique of the above-mentioned Patent Document 1, in order to obtain the engine rotation speed that averages the influence of the density of the generation of pulse signals in one stroke (engine rotation fluctuation due to changes in the combustion state and generated torque), the combustion state and Correlation between the generated torque and the engine speed becomes low. When controlling the engine combustion state and generated torque, if the engine rotation speed, which has a low correlation with the combustion state and generated torque, is used as information on the combustion state and generated torque, the engine combustion state and generated torque are accurate. It cannot be controlled well.

  The present invention has been made in consideration of such circumstances, and therefore the object of the present invention is to calculate the rotational speed of an internal combustion engine having a high correlation with the combustion state and generated torque of the internal combustion engine. An object of the present invention is to provide a control device for an internal combustion engine.

Considering that combustion period in accordance with the ignition timing of the internal combustion engine is changed, according to claim 1 invention is provided with means for setting the predetermined rotational speed calculation section immediately after the ignition timing of the internal combustion engine, the it is obtained to calculate the rotational speed of the internal combustion engine based on the angular velocity information of the crank shaft at a predetermined rotational speed calculation section set by means. If the rotation speed calculation section is set based on the ignition timing as described above, the rotation speed calculation section can be changed corresponding to the change of the combustion period according to the ignition timing and is not affected by the ignition timing. In addition, the rotational speed of the internal combustion engine having a high correlation with the combustion state and the generated torque can be calculated.

In general, since a control system for an internal combustion engine is provided with a crank angle sensor that outputs a crank angle signal every time the crankshaft rotates by a predetermined crank angle, the crank angle signal of the crank angle sensor as in claim 2. It is preferable to calculate angular speed information of the crankshaft in the rotational speed calculation section based on the above. By using the crank angle signal of the crank angle sensor, it is possible to accurately calculate angular speed information of the crankshaft in the rotational speed calculation section (for example, the time required for the crankshaft to rotate in the rotational speed calculation section).

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 for detecting the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 for introducing air into each cylinder of the engine 11, and a fuel injection valve 21 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 20 of each cylinder. Yes. Further, a spark plug 22 is attached to each cylinder of the cylinder head of the engine 11, and the air-fuel mixture in the cylinder is ignited by the spark discharge of each spark plug 22.

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying gas is provided.

  Also, a coolant temperature sensor 26 that detects the coolant temperature and a crank angle signal (pulse signal) are output to the cylinder block of the engine 11 every time the crankshaft 27 of the engine 11 rotates a predetermined crank angle (for example, 6 ° C.). A crank angle sensor 28 is attached. Here, “° C. A” is a unit representing a crank angle, and is a unit of the same dimension as “°” which is a general unit of angle. Based on the crank angle signal of the crank angle sensor 28, the crank angle and the engine speed are detected.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 29. The ECU 29 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby determine the fuel injection amount of the fuel injection valve 21 according to the engine operating state. The ignition timing of the spark plug 22 is controlled.

  At that time, the ECU 29 executes an engine rotation speed calculation program shown in FIG. 3 to be described later, whereby a predetermined rotation speed calculation section (near the combustion TDC (combustion stroke top dead center)) of each cylinder of the engine 11 is set. Angular speed information of the crankshaft 27 (for example, the crankshaft 27 rotates in the rotational speed calculation section) in the rotational speed calculation section set before and after the combustion TDC or the rotational speed calculation section set immediately after the combustion TDC). Is calculated), and the engine speed is calculated based on the angular velocity information.

  The engine 11 generates combustion of the air-fuel mixture in the vicinity of the combustion TDC, generates torque according to the combustion state, and changes the angular acceleration (amount of change in angular velocity) of the crankshaft 27 according to the generated torque (FIG. Therefore, the angular speed information of the crankshaft 27 in the rotational speed calculation section set in the vicinity of the combustion TDC is information that accurately reflects the combustion state and the generated torque, and the engine rotational speed is calculated based on the angular speed information. Thus, the engine rotational speed having a high correlation with the combustion state of the engine 11 and the generated torque is calculated.

  Specifically, first, as shown in FIG. 2, every time the crankshaft 27 rotates 30 ° C., it was necessary for the crankshaft 27 to rotate 30 ° A based on the crank angle signal of the crank angle sensor 28. Time T30 is calculated. Here, T30 in the crank angle range from 30 ° C. A before combustion TDC to combustion TDC is T30 (1), and T30 in the crank angle range from combustion TDC to 30 ° C. after combustion TDC is T30 (2). Further, T30 in the crank angle range from 30 ° C. after combustion TDC to 60 ° C. after combustion TDC is T30 (3), and T30 in the crank angle range from 60 ° C. A after combustion TDC to 90 ° C. after combustion TDC is T30. T30 (4).

  Thereafter, the rotational speed set in the vicinity of the combustion TDC using T30 (1) to T30 (4) in the vicinity of the combustion TDC for each combustion stroke of the engine 11 by a method according to the number of cylinders of the engine 11 described later. As the angular velocity information of the crankshaft 27 in the calculation section, a section rotation time Tx [s] required for the crankshaft 27 to rotate in the rotation speed calculation section is calculated, and this section rotation time Tx is calculated as the engine speed NE [rpm]. Convert to

《8 cylinder engine》
(a) In the case of an 8-cylinder engine (combustion interval is 90 ° C. A), the rotation speed calculation section is set to a crank angle range of 30 ° C. from the combustion TDC to 30 ° C. after the combustion TDC to calculate the rotation speed. Make the section shorter than the combustion interval.

In this case, T30 (2) from the combustion TDC to 30 ° C. after the combustion TDC is defined as a section rotation time Tx [s] required for the crankshaft 27 to rotate in the rotation speed calculation section.
Tx = T30 (2)
The engine speed NE [rpm] is calculated by the following equation using the section rotation time Tx [s].
NE = 60 / (Tx × 360/30)

  (b) Further, the rotation speed calculation section may be set to a crank angle range of 30 ° C. from 30 ° C. after combustion TDC to 60 ° C. after combustion TDC.

In this case, T30 (3) from 30 ° C. A after combustion TDC to 60 ° C. after combustion TDC is defined as a section rotation time Tx [s] required for the crankshaft 27 to rotate in the rotation speed calculation section.
Tx = T30 (3)
The engine speed NE [rpm] is calculated by the following equation using the section rotation time Tx [s].
NE = 60 / (Tx × 360/30)

<< 4 cylinder engine or 6 cylinder engine >>
(c) In the case of a 4-cylinder engine (combustion interval is 180 ° C. A) or a 6-cylinder engine (combustion interval is 120 ° C. A), the rotational speed calculation section is 60 ° C. A from the combustion TDC to 60 ° C. after the combustion TDC. The rotation speed calculation section is set shorter than the combustion interval.

In this case, the crankshaft 27 rotates by adding T30 (2) from the combustion TDC to 30 ° C. A after the combustion TDC and T30 (3) from 30 ° C. A after the combustion TDC to 60 ° C. after the combustion TDC. The section rotation time Tx [s] required to rotate the speed calculation section is obtained.
Tx = T30 (2) + T30 (3)
The engine speed NE [rpm] is calculated by the following equation using the section rotation time Tx [s].
NE = 60 / (Tx × 360/60)

  (d) The rotation speed calculation section may be set to a crank angle range of 60 ° C. from 30 ° C. before combustion TDC to 30 ° C. after combustion TDC.

In this case, T30 (1) from 30 ° C. A before combustion TDC to combustion TDC and T30 (2) from combustion TDC to 30 ° C. A after combustion TDC are added, and the crankshaft 27 defines the rotation speed calculation section. The section rotation time Tx [s] required for rotation is obtained.
Tx = T30 (1) + T30 (2)
The engine speed NE [rpm] is calculated by the following equation using the section rotation time Tx [s].
NE = 60 / (Tx × 360/60)

  (e) In the case of a 4-cylinder engine or a 6-cylinder engine, the rotation speed calculation section is set to a crank angle range of 90 ° C. from the combustion TDC to 90 ° C. after the combustion TDC. It may be shorter than the combustion interval.

In this case, T30 (2) from combustion TDC to 30 ° C. A after combustion TDC, T30 (3) from 30 ° C. A after combustion TDC to 60 ° C. after combustion TDC, and combustion TDC from 60 ° C. after combustion TDC. Thereafter, T30 (4) up to 90 ° C. is added to obtain the section rotation time Tx [s] required for the crankshaft 27 to rotate in the rotation speed calculation section.
Tx = T30 (2) + T30 (3) + T30 (4)
The engine speed NE [rpm] is calculated by the following equation using the section rotation time Tx [s].
NE = 60 / (Tx × 360/90)

  (f) Further, the rotation speed calculation section may be set to a crank angle range of 90 ° C. from 30 ° C. before combustion TDC to 60 ° C. after combustion TDC.

In this case, T30 (1) from 30 ° C. before combustion TDC to combustion TDC, T30 (2) from combustion TDC to 30 ° C. after combustion TDC, and 30 ° C. after combustion TDC to 60 ° C. after combustion TDC. T30 (3) up to is obtained to obtain the section rotation time Tx [s] required for the crankshaft 27 to rotate in the rotation speed calculation section.
Tx = T30 (1) + T30 (2) + T30 (3)
The engine speed NE [rpm] is calculated by the following equation using the section rotation time Tx [s].
NE = 60 / (Tx × 360/90)

  For example, in the case of an 8-cylinder engine, the rotation speed calculation section is changed to a crank temperature of 30 ° C. from 10 ° C. A before combustion TDC to 20 ° C. after combustion TDC. An angular range may be set. In the case of a 4-cylinder engine or a 6-cylinder engine, the rotation speed calculation section is set to a crank angle range of 60 ° C. from 10 ° C. before combustion TDC to 50 ° C. after combustion TDC, or The speed calculation section may be set to a crank angle range of 90 ° C. from 10 ° C. A before combustion TDC to 80 ° C. after combustion TDC.

The calculation of the engine rotation speed described above is executed by the ECU 29 according to the engine rotation speed calculation program of FIG. The processing contents of this program will be described below.
The engine speed calculation program shown in FIG. 3 is executed at a predetermined cycle while the ECU 29 is turned on, and serves as a speed calculation means in the claims.

  When this program is started, first, at step 101, every time the crankshaft 27 rotates 30 ° C., it takes 30 ° C. to rotate the crankshaft 27 based on the crank angle signal of the crank angle sensor 28. Time T30 is calculated.

  Thereafter, the process proceeds to step 102, and the angular speed of the crankshaft 27 in the rotational speed calculation section set near the combustion TDC is used for each combustion stroke of the engine 11 using T30 (1) to T30 (4) near the combustion TDC. As information, the section rotation time Tx [s] required for the crankshaft 27 to rotate in the rotation speed calculation section is calculated.

  Thereafter, the process proceeds to step 103, and for each combustion stroke of the engine 11, the section rotation time Tx [s] required for the crankshaft 27 to rotate the rotation speed calculation section is converted into the engine rotation speed NE [rpm].

  In the conventional engine speed calculation method, as shown by a dotted line in FIG. 4, the engine speed is calculated by averaging the effects of engine speed fluctuations due to changes in the combustion state of the engine 11 and the generated torque. Correlation between the combustion state and generated torque and the engine rotation speed becomes low.

  On the other hand, in the present embodiment, as indicated by a solid line in FIG. 4, a rotation speed calculation section set in the vicinity of the combustion TDC of each cylinder of the engine 11 (rotation speed calculation set before and after the combustion TDC). The angular speed information of the crankshaft 27 (for example, the time required for the crankshaft 27 to rotate in the rotational speed calculation section) in the section or the rotational speed calculation section set immediately after the combustion TDC) is calculated, and the angular speed information is used as the angular speed information. Since the engine rotation speed is calculated based on this, it is possible to calculate the engine rotation speed having high correlation with the combustion state of the engine 11 and the generated torque. Thereby, when controlling the combustion state and the generated torque of the engine 11, the engine rotation speed having a high correlation with the combustion state and the generated torque can be used as information on the combustion state and the generated torque. Even under a situation where the generated torque changes suddenly during operation or the like, the generated torque of the engine 11 can be accurately controlled.

  Further, in this embodiment, in the case of an 8-cylinder engine (combustion interval is 90 ° C. A), the rotational speed calculation section is set to a 30 ° C. crank angle range immediately after the combustion TDC or 30 ° C. A before and after the combustion TDC. In the case of an 8-cylinder engine with a relatively short combustion interval, the rotation speed calculation section is made shorter than the combustion interval so that it is not affected by the preceding and following combustion strokes. It is possible to calculate the engine rotation speed having a high correlation with the combustion state and generated torque of the combustion stroke.

  Further, in this embodiment, in the case of a 4-cylinder engine (combustion interval is 180 ° C. A) or a 6-cylinder engine (combustion interval is 120 ° C. A), the rotational speed calculation section is 60 ° C. A or 90 ° immediately after the combustion TDC. Since the crank angle range of ℃ A and the crank angle range of 60 ℃ A or 90 ℃ A before and after the combustion TDC are set, the rotational speed calculation section is made shorter than the combustion interval, and the combustion stroke before and after While calculating the engine rotation speed that is highly correlated with the combustion state and generated torque of the current combustion stroke without being influenced by the engine speed, the calculation speed of the engine rotation speed is improved by increasing the rotation speed calculation section appropriately. Can be made.

  In the case of a 4-cylinder engine or a 6-cylinder engine, the rotation speed calculation section is set to a crank angle range of 30 ° C. immediately after the combustion TDC, or a crank angle range of 30 ° C. before and after the combustion TDC, or In the case of an 8-cylinder engine, the rotation speed calculation section may be set to a crank angle range of 60 ° C. immediately after the combustion TDC or a crank angle range of 60 ° C. before and after the combustion TDC. The calculation interval is not limited to the crank angle range described in the above embodiment, and may be changed as appropriate.

  In the above embodiment, the rotation speed calculation section is set in the crank angle range based on the combustion TDC. However, the crank angle range immediately after the ignition timing (for example, ignition from ignition timing to the ignition timing) is set. The rotation speed calculation section may be set in a crank angle range from 30 ° C. A after the ignition timing or a crank angle range from 30 ° C. A after the ignition timing to 60 ° C. after the ignition timing. In this way, the rotation speed calculation section can be changed corresponding to the change of the combustion period according to the ignition timing, and the correlation with the combustion state and generated torque is high regardless of the ignition timing. The engine rotation speed can be calculated.

  In the above embodiment, the engine speed NE is calculated using the time required for the crankshaft 27 to rotate in the rotation speed calculation section as the angular speed information of the crankshaft 27 in the rotation speed calculation section. The engine rotational speed NE may be calculated using the angular speed or angular acceleration of the crankshaft 27 in the rotational speed calculation section.

  The scope of application of the present invention is not limited to a four-cylinder engine, a six-cylinder engine, and an eight-cylinder engine, but an engine having another number of cylinders (for example, a three-cylinder engine, a five-cylinder engine, a ten-cylinder engine, a twelve-cylinder engine, etc. The present invention may be applied to:

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a figure for demonstrating the calculation method of T30. It is a flowchart which shows the flow of a process of an engine speed calculation program. It is a time chart which shows the execution example of the engine speed calculation of a present Example. It is a figure which shows the relationship between generated torque and angular acceleration.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 27 ... Crankshaft, 28 ... Crank angle sensor, 29 ... ECU (rotation) Speed calculation means)

Claims (2)

Means for setting a predetermined rotational speed calculation section immediately after the ignition timing of the internal combustion engine, and the rotational speed of the internal combustion engine based on the angular speed of the crankshaft in the predetermined rotational speed calculation section set by the means or information correlated therewith A control apparatus for an internal combustion engine, comprising: a rotation speed calculation means for calculating A crank angle sensor that outputs a crank angle signal each time the crankshaft rotates a predetermined crank angle;
2. The control device for an internal combustion engine according to claim 1, wherein the rotation speed calculation unit calculates an angular speed of a crankshaft in the rotation speed calculation section or information correlated therewith based on the crank angle signal.

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