JP2008267352A - Crank angle correction device and crank angle correction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crank angle correction device and a crank angle correction method capable of calculating an accurate correction value of a crank angle by using a cylinder pressure waveform in one cycle without averaging cylinder pressure waveforms of a plurality of cycles. <P>SOLUTION: In-cylinder pressure in a combustion chamber in a non-combustion condition including maximum cylinder pressure at a compression top dead center, and time sequence data of crank angle detected by a crank angle sensor corresponding to the in-cylinder are acquired (step S3). A plurality of pairs of crank angles corresponding to cylinder pressure getting to the same value before and after a point where the maximum cylinder pressure is acquired are specified (step 7). Intermediate values of the pair of crank angles are calculated and an average value of the intermediate values is calculated (step S8). A crank angle correction value correcting the crank angle detected by the crank angle sensor is calculated based on a crank angle corresponding to the compression top dead center detected by the crank angle sensor and the average value of the intermediate values (step S9). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a crank angle correction device and a crank angle correction method in an internal combustion engine.

  In general, in various internal combustion engines, the crank angle of a crankshaft is detected using a crank angle sensor, and the detected crank angle is used for obtaining the rotational speed of the internal combustion engine, setting the ignition timing, and the like. The crank angle sensor used for detecting the crank angle is a magnetic sensor or a photoelectric sensor including a rotor plate (signal plate) fixed to the crankshaft, and is generally built in a distributor. In this case, the detection accuracy of the crank angle by the crank angle sensor greatly depends on the processing accuracy and mounting accuracy of the distributor and the rotor plate. For this reason, the detected value of the crank angle sensor may actually deviate from the actual crank angle (true value).

  Recently, ignition timing control, valve control, and the like have been performed using in-cylinder pressure based on crank angle timing. In such control, precise control is difficult unless an accurate crank angle is obtained.

  For example, Patent Documents 1 to 3 disclose a technique for correcting the crank angle.

  To correct the crank angle, the cylinder pressure waveform during motoring is parabolically approximated by utilizing the fact that the cylinder pressure waveform during engine motoring (non-combustion) is axisymmetric with respect to compression top dead center. Thus, there is known a method of calculating the crank angle at the compression top dead center and calculating a correction value for correcting the crank angle detected by the crank angle sensor using the crank angle.

JP 2005-180356 A Japanese Patent Laid-Open No. 3-47471 JP-A-8-28338

  By the way, the crank angle at the compression top dead center is calculated by approximating the in-cylinder pressure waveform during motoring of the engine by a parabola, and a correction value for correcting the crank angle detected by the crank angle sensor is calculated using this crank angle. In principle, the influence of minute noise, A / D conversion error, etc. is likely to cause a large error in the calculated value in the method. Therefore, in practice, if the cylinder pressure data for several tens of cycles is not averaged, high accuracy is required. A correction value cannot be obtained.

  In addition, in order to calculate the average of the in-cylinder pressure data of a plurality of cycles, the motoring waveform when the fuel is cut when the vehicle is decelerated must be used. Until the fuel cut control is performed, the crank angle correction value is calculated. Can't get.

  Furthermore, it is difficult to calculate a highly accurate correction value of the crank angle unless an in-cylinder pressure waveform having a sufficient number of cycles is obtained.

  The present invention has been made in view of the above circumstances, and an object thereof is to obtain an accurate crank angle by using in-cylinder pressure data in one cycle without averaging the in-cylinder pressure data in a plurality of cycles. An object of the present invention is to provide a crank angle correction device and a crank angle correction method capable of calculating a correction value.

  Another object of the present invention is to provide a crank angle correction device and a crank angle correction method capable of calculating an accurate crank angle correction value immediately after engine startup.

  A crank angle correction device according to the present invention is a cylinder that acquires time-series data of a cylinder angle detected by a crank angle sensor corresponding to an in-cylinder pressure of a combustion chamber in a non-combustion state including a maximum in-cylinder pressure at a compression top dead center. From the internal pressure / crank angle acquisition means and the acquired time series data of the in-cylinder pressure and the crank angle, a plurality of pairs of crank angles respectively corresponding to in-cylinder pressures having the same value before and after the time of acquiring the maximum in-cylinder pressure are obtained. Crank angle specifying means for specifying in-cylinder pressure, an average value calculating means for calculating an intermediate value between the pair of crank angles, and calculating an average value of the intermediate values, and an average value calculated by the average value calculating means The crank angle detected by the crank angle sensor is corrected based on the crank angle corresponding to the compression top dead center detected by the crank angle sensor. A crank angle correction value calculating means for calculating a link angle correction value, is characterized by.

  According to this configuration, since it is possible to perform the averaging process using only the in-cylinder pressure data for one cycle including the actually measured maximum in-cylinder pressure, it is difficult to be influenced by noise, and the in-cylinder pressure data for one cycle is used. The crank angle correction value can be calculated with high accuracy.

  The said structure WHEREIN: The said cylinder pressure waveform acquisition means can employ | adopt the structure which acquires the said cylinder pressure at the time of cranking.

  According to this configuration, the crank angle correction value can be calculated with high accuracy immediately after the engine is started.

  The crank angle correction method according to the present invention acquires the in-cylinder pressure of the combustion chamber in the non-combustion state including the maximum in-cylinder pressure at the compression top dead center and the time-series data of the crank angle detected by the corresponding crank angle sensor, From the acquired in-cylinder pressure and time-series data of the crank angle, a plurality of a pair of crank angles corresponding to the in-cylinder pressure having the same value before and after the time when the maximum in-cylinder pressure is acquired are specified, And calculating an average value of these intermediate values, and based on the average value of the intermediate values and the crank angle corresponding to the compression top dead center detected by the crank angle sensor, A crank angle correction value for correcting the detected crank angle is calculated.

  The said structure WHEREIN: The structure which acquires the said cylinder pressure at the time of cranking is employable.

  According to the present invention, it is possible to calculate an accurate crank angle correction value without averaging the cylinder pressure data of a plurality of cycles.

  Further, according to the present invention, it is possible to calculate an accurate crank angle correction value from the time of engine start.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.

  FIG. 1 is a conceptual diagram of an example of an engine system to which an embodiment of the present invention is applied.

  The engine 10 is of a type in which fuel is injected from a fuel injection valve 11 into an intake port 12 and ignited by a spark plug 13.

  A valve operating mechanism including an intake valve 17 that opens and closes the intake port 12 and an exhaust valve 18 that opens and closes the exhaust port 15 is incorporated in the cylinder head 16 in which the intake port 12 and the exhaust port 15 facing the combustion chamber 14 are formed. ing. In addition to the fuel injection valve 11, the ignition plug 13 that ignites the air-fuel mixture in the combustion chamber 14, and the ignition coil 19 that generates sparks in the ignition plug 13, an in-cylinder pressure sensor for detecting the pressure in the combustion chamber 14 20 is also mounted on the cylinder head 16. A signal detected by the in-cylinder pressure sensor 20 is output to the ECU 21.

  At the upstream end side of the intake pipe 23 connected to the cylinder head 16 so as to communicate with the intake port 12 and defining the intake passage 22 together with the intake port 12, dust and the like contained in the atmosphere are removed to remove the intake passage 22. An air cleaner 24 is provided for guiding the air. A throttle valve 25 that adjusts the opening degree of the intake passage 22 based on the amount of depression of an accelerator pedal (not shown) that is operated by the driver is incorporated in the portion of the intake pipe 23 that is located downstream of the air cleaner 24. ing. The throttle valve 25 is provided with a throttle opening degree sensor 26 for detecting the opening degree, and the detection information is output to the ECU 21. In this embodiment, the accelerator pedal and the throttle valve 25 are mechanically connected. However, the depression operation of the accelerator pedal and the opening / closing operation of the throttle valve 25 are separated, and the opening / closing operation of the throttle valve 25 is performed using an actuator. It may be one that can be electrically controlled.

  A surge tank 27 is formed in the middle of the intake pipe 23 between the throttle valve 25 and the air cleaner 24, and flows in the intake passage 22 in the middle of the intake pipe 23 between the surge tank 27 and the air cleaner 24. An air flow meter 28 that detects the intake air flow rate and outputs it to the ECU 21 is attached. The attachment position of the air flow meter 28 in the intake pipe 23 may be upstream from the attachment position of the throttle valve 25, and is not limited to the position shown in FIG.

  In the middle of the exhaust pipe 30 connected to the cylinder head 16 so as to communicate with the exhaust port 15 and defining the exhaust passage 29 together with the exhaust port 15, harmful substances generated by combustion of the air-fuel mixture in the combustion chamber 14 are present. A three-way catalyst 31 for detoxification is incorporated. It is also effective to incorporate a plurality of three-way catalysts 31 in series along the exhaust passage 29. In the middle of the exhaust pipe 30 between the three-way catalyst 31 and the exhaust port 15, an A / F sensor 32 that detects the air-fuel ratio in the exhaust gas flowing in the exhaust passage 29 and outputs it to the ECU 21 is provided. . Since the A / F sensor 32 in this embodiment uses zirconia as a detection element, a heater 32a that promotes activation thereof is incorporated in the A / F sensor 32. The heater 32a receives electric power from the ECU 21 and quickly raises the detection element to its activation temperature.

  Therefore, the intake air supplied from the intake pipe 23 into the combustion chamber 14 through the air cleaner 24 forms an air-fuel mixture with the fuel injected from the fuel injection valve 11 into the intake port 12 and is ignited by the spark of the spark plug 13. The exhaust gas thus generated is exhausted through the three-way catalyst 31 from the exhaust pipe 30 to the atmosphere.

  A crank angle sensor 37 that detects the rotational phase of the crankshaft 36 to which the piston 33 is coupled via the connecting rod 35, that is, the crank angle, and outputs the detected crank angle to the ECU 21 is attached to the cylinder block 34 in which the piston 33 reciprocates. It has been.

  The ECU 21 is composed of hardware such as an input / output circuit (not shown) such as a CPU, ROM, RAM, and A / D converter, a storage device, and required software, and signals from the ignition key switch 38 and the in-cylinder pressure described above. Based on the detection information from the sensor 20, the throttle opening sensor 26, the A / F sensor 32, the crank angle sensor 37, and the air flow meter 28, the fuel is operated so that the engine 10 can be smoothly operated according to a preset program. The operations of the injection valve 11, the ignition coil 19, the heater 32a of the A / F sensor 32, and the like are controlled.

  Further, the ECU 21 samples the detection values of the crank angle sensor 37 and the in-cylinder pressure sensor 20 every minute time (sampling time), and stores and holds them in a predetermined storage area (buffer) of the ECU 20.

  The ECU 21 constitutes the crank angle correction device of the present invention.

  Next, an example of the crank angle correction process by the ECU 21 will be described with reference to FIGS. FIG. 2 is a flowchart showing an example of the procedure of the crank angle correction process, and FIG. 3 is a graph for illustrating a method of calculating the crank angle correction value.

  First, when the ignition switch is turned on (step S1), cranking is started (step S2). In this state, the combustion chamber of the engine 10 is not combusting.

Next, the in-cylinder pressure and the corresponding crank angle are sampled (step S3). As shown in FIG. 3, when cranking is started, the in-cylinder pressure P increases from the minimum in-cylinder pressure P _{0 as} the crank angle increases, takes the maximum in-cylinder pressure P _max at the compression top dead center, It will descend again. The ECU 21 samples the in-cylinder pressure P and the corresponding crank angle θ every predetermined sampling time (step S3). That is, the ECU 21 acquires time-series data of the in-cylinder pressure P and the crank angle θ detected by the crank angle sensor 37 corresponding thereto. This time series data is data for one cycle. Note that the waveform of the in-cylinder pressure P of the combustion chamber in the non-combustion state is substantially line symmetric with respect to the compression top dead center, as shown in FIG. Further, the processing in step S3 constitutes in-cylinder pressure / crank angle acquisition means.

Next, the minimum in-cylinder pressure P ₀ and the maximum in-cylinder pressure P _max are obtained from the sampled in-cylinder pressure P and the corresponding time-series data of the crank angle θ (step S4).

Next, the crank angle θ _TDC corresponding to the compression top dead center detected by the crank angle sensor 37 is acquired from the detected value of the crank angle sensor 37 sampled (step S5). The crank angle θ _TDC depends on the processing accuracy and mounting accuracy of the rotor plate of the crank angle sensor 37.

Next, a representative in-cylinder pressure P _k (k = 1, 2,..., N−1, N = integer) is determined by the following equation between the minimum in-cylinder pressure P ₀ and the maximum in-cylinder pressure P _max ( Step S6).

Next, the crank angles θ _k and θ _k ′ at the in-cylinder pressure P _k are acquired (step S7). The crank angles θ _k and θ _k ′ are a pair of crank angles corresponding to the in-cylinder pressure P _k that is the same before and after the time when the maximum in-cylinder pressure P _max is acquired. Incidentally, the crank angle specifying means is constituted by the processing of step S7.

Next, the average value θ _T is calculated by the following equation (step S8). That is, an intermediate value (θ _k + θ _k ′) / 2 (k = 1 to N−1) between the pair of crank angles θ _k and θ _k ′ is calculated, and these N−1 intermediate values (θ _k + θ _k ') / 2 of an average value theta _T. The average value calculation means is configured by the processing in step S8.

Subsequently, based on the average value θ _T and the crank angle θ _TDC corresponding to the compression top dead center detected by the crank angle sensor 37, the crank angle correction value Δθ for correcting the crank angle CA detected by the crank angle sensor 37 is next Calculation is performed using an equation (step S9). Note that the crank angle correction value calculation means is configured by the processing of step S9.

Next, assuming that the crank angle detected by the crank angle sensor 37 after calculating the crank angle correction value Δθ is CA ₀ and the corrected crank angle is CA, the corrected crank angle CA is obtained by the following equation (step) S10).

After the crank angle correction value [Delta] [theta] is calculated, CA ₀ crank angle detected by the crank angle sensor 37 is corrected by the crank angle correction value [Delta] [theta], the crank angle CA after correction is used to control the engine 10.

As described above, in this embodiment, instead of averaging the in-cylinder pressure waveform of a plurality of cycles, an intermediate value between a pair of crank angles θ _k and θ _k ′ obtained from the in-cylinder pressure waveform of one cycle ( Since the crank angle correction value Δθ is calculated based on the averaging process of θ _k + θ _k ′) / 2 (k = 1 to N−1), the in-cylinder pressure waveform over a plurality of cycles is unnecessary, and the influence of noise is suppressed. In addition, a highly accurate crank angle correction value Δθ can be obtained from cranking (engine start).

  Further, according to the present embodiment, the crank angle correction value Δθ can be calculated using the in-cylinder pressure waveform at the time of cranking, so that the crank angle can be corrected with high accuracy immediately after the engine 10 is started.

  In the present embodiment, the case where the crank angle correction value Δθ is calculated at the time of cranking has been described. However, the present invention is not limited to this. For example, the crank angle correction value Δθ is calculated using the in-cylinder pressure waveform when the fuel is cut when the vehicle is decelerated. It is also possible to calculate the angle correction value Δθ. Further, by calculating the average of the crank angle correction value Δθ calculated at the time of cranking and the crank angle correction value Δθ calculated at the time of fuel cut, the reliability of the crank angle correction value Δθ is further improved.

1 is a conceptual diagram of an example of an engine system to which an embodiment of the present invention is applied. It is a flowchart which shows an example of the procedure of a crank angle correction process. It is a graph for demonstrating the calculation method of a crank angle correction value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Engine 11 ... Fuel injection valve 12 ... Intake port 13 ... Spark plug 14 ... Combustion chamber 15 ... Exhaust port 16 ... Cylinder head 17 ... Intake valve 18 ... Exhaust valve 19 ... Ignition coil 20 ... In-cylinder pressure sensor 21 ... ECU
37 ... Crank angle sensor P ... In-cylinder pressure θ ... Crank angle

Claims (4)

In-cylinder pressure / crank angle acquisition means for acquiring in-cylinder pressure of the combustion chamber in the non-combustion state including the maximum in-cylinder pressure at compression top dead center and crank angle time series data detected by a crank angle sensor corresponding thereto;
Crank angle specifying means for specifying, for a plurality of cylinder pressures, a pair of crank angles respectively corresponding to the cylinder pressures having the same value before and after the time when the maximum cylinder pressure is acquired, from the acquired time series data of the cylinder pressure and crank angle When,
An average value calculating means for calculating an intermediate value between the pair of crank angles and calculating an average value of these intermediate values;
A crank angle correction value for correcting the crank angle detected by the crank angle sensor based on the average value calculated by the average value calculating means and the crank angle corresponding to the compression top dead center detected by the crank angle sensor. A crank angle correction value calculating means for calculating;
A crank angle correction device comprising:   The crank angle correction device according to claim 1, wherein the in-cylinder pressure acquisition unit acquires the in-cylinder pressure at the time of cranking. Obtain time series data of the cylinder pressure detected by the crank angle sensor corresponding to the cylinder pressure of the combustion chamber in the non-combustion state including the maximum cylinder pressure at the compression top dead center,
From the acquired in-cylinder pressure and the time-series data of the crank angle, a pair of crank angles respectively corresponding to the in-cylinder pressure having the same value before and after the time when the maximum in-cylinder pressure is acquired are specified for a plurality of in-cylinder pressures
Calculating an intermediate value between the pair of crank angles, and calculating an average value of these intermediate values;
A crank angle correction value for correcting a crank angle detected by the crank angle sensor is calculated based on an average value of the intermediate values and a crank angle corresponding to the compression top dead center detected by the crank angle sensor.
A crank angle correction method characterized by the above.   4. The crank angle correction method according to claim 3, wherein the in-cylinder pressure at the time of cranking is acquired.

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