JP2013160167A - Apparatus for processing sensor signal for engine control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable correction in consideration for changes of delay time due to a temperature, an individual difference or aging when correcting delay of an analog filter circuit.SOLUTION: An electronic control device 1 converts a sensor signal of a CPS2 into a digital signal for each prescribed crank angle by an A/D conversion circuit 4a of a microcomputer 4 via an analog filter circuit 5. As for the sensor signal of the CPS2, an input signal and an output signal of the analog filter circuit 5 are input into an input capture 4b of the microcomputer 4 via a comparison circuit 7. The microcomputer 4 calculates delay time Td by the analog filter circuit 5 from a time difference of the rising timing of the input signal. Correction processing of the delay time of the digital signal converted by the A/D conversion circuit 4a is performed on the basis of information on the delay time Td.

Description

  The present invention relates to a sensor signal processing apparatus for engine control.

  In the control of the vehicle engine, when performing fine control according to the crank angle, it is required to acquire an accurate sensor signal synchronized with the crank angle. On the other hand, when the engine is controlled by a sensor signal obtained from the sensor, it is necessary to convert it into a digital signal for processing by a control device such as a microcomputer. In this case, signal processing is performed through an analog filter serving as an anti-aliasing filter in relation to converting an analog sensor signal output from the sensor into a digital signal. At this time, if the sensor signal is filtered with an analog filter, a phase lag occurs, which needs to be corrected. As a method of performing such correction, for example, there is a technique disclosed in Patent Document 1.

JP 2008-169728 A

  The above-described technology employs a configuration in which the delay is corrected by a digital filter. However, since discrete components constituting the analog filter circuit have initial tolerance, temperature tolerance, or durability tolerance, the delay time of the analog filter circuit is uniform. Cannot be determined. For this reason, the configuration using the digital filter has a problem that correction processing for compensating for these tolerances cannot be performed.

  The present invention has been made in consideration of the above circumstances, and its purpose is to correct initial delay of components constituting an analog filter, temperature when correcting a delay generated when a sensor signal is filtered by an analog filter, and a temperature. It is an object of the present invention to provide a sensor signal processing apparatus capable of performing correction in consideration of a change in delay time due to tolerance or tolerance tolerance such as aging.

  The sensor signal processing device for engine control according to claim 1 is an analog filter circuit to which a sensor signal from a sensor used for controlling an engine of a vehicle is input, and an analog sensor signal output from the analog filter circuit. A / D conversion means for converting the signal into a digital signal, delay time detection means for detecting a delay time due to filtering from the sensor signal at the time of input and output to the analog filter circuit, and the delay time detection means And correction means for correcting the phase delay of the digital signal output from the A / D conversion means using the delay time information.

  As a result, when correcting the delay time required after A / D conversion for the sensor signal from the sensor, the delay time of the analog filter circuit is directly detected. The phase lag can be corrected reliably.

Overall electrical configuration diagram showing the first embodiment Waveform diagram of input signal and output signal of analog filter circuit Flow chart of delay time detection and correction processing Flowchart of delay time detection and correction processing showing the second embodiment Whole electrical configuration diagram showing a third embodiment Flow chart of delay time detection and correction processing Flowchart of delay time detection and correction processing according to the fourth embodiment

(First embodiment)
Hereinafter, the first embodiment will be described with reference to FIGS.
In FIG. 1, an electronic control unit 1 which is a sensor signal processing unit for engine control includes a CPS (cylinder pressure sensor) 2 which is a sensor for detecting the rotational state of the engine and an NE (number of number) for detecting the rotational position of the cylinder. engine speed) The sensor signal from the sensor 3 is input and processed. The CPS 2 outputs the sensor signal of the internal pressure accompanying the rotation of the cylinder as one cycle (crank angle 720 ° CA (crank angle)) corresponding to two rotations of the rotating shaft. The NE sensor 3 outputs an angle signal having a peak every 1 ° CA in crank angle.

  The electronic control unit 1 is mainly composed of a microcomputer 4. The microcomputer 4 has an A / D conversion circuit 4a as A / D conversion means and an input capture 4b as delay time detection means at the input stage. I have. An analog filter circuit 5 is connected to the A / D conversion circuit 4a, and is connected to the CPS 2 via an input circuit 6 including a resistor 6a and a capacitor 6b.

  The analog filter circuit 5 is a discrete component in which a buffer circuit 5a is provided at the input stage, a low-pass filter including resistors 5b and 5c and capacitors 5d and 5e is provided on the output side, and a buffer circuit 5f is provided at the output stage. It is a configuration. When the sensor signal from the CPS 2 is input, the analog filter circuit 5 passes a predetermined low frequency and inputs it to the A / D conversion circuit 4a, and cuts a signal in a high frequency region prior to A / D conversion. It is responsible for the anti-aliasing filter function.

  A comparison circuit 7 as a comparison means is connected to the input capture 4b. The comparison circuit 7 includes two comparators 7a and 7b, and also includes resistors 7c and 7d that generate a reference voltage Vs. One comparator 7a receives the output signal S1 of the input circuit 6, compares it with the reference voltage Vs, and inputs it to the input capture 4b. The other comparator 7b receives the output signal S2 of the analog filter circuit 5, compares it with the reference voltage Vs, and inputs it to the input capture 4b.

  The output terminal of the NE sensor 3 is connected to the waveform shaping circuit 9 via an input circuit 8 comprising resistors 8a and 8b and a capacitor 8c. The waveform shaping circuit 9 includes a comparator 9a and resistors 9b and 9c. The microcomputer 9 compares the sensor signal of the NE sensor 3 with the reference voltage Vp set by the resistors 9b and 9c in the comparator 9a. 4 Thereby, the microcomputer 4 receives an angle signal from the NE sensor 3 every 1 ° CA as a crank angle.

  Although not shown, a temperature detection signal for detecting the engine temperature and a cylinder discrimination signal are input to the electronic control unit 1 and input to the microcomputer 4.

Next, the operation of the above configuration will be described with reference to FIGS.
The analog filter circuit 5 performs anti-aliasing at the input stage of the A / D conversion circuit 4a as described above, and cuts a high-frequency signal having a predetermined frequency or higher superimposed on the sensor signal. Actually, since the frequency is very high with respect to the frequency of the sensor signal and the amplitude is small, a phase difference occurs between the input signal S1 and the output signal S2, but the waveform changes greatly. Absent.

  The delay time (phase delay) Td generated when the sensor signal of CPS 2 is input to the microcomputer 4 via the analog filter circuit 5 is directly determined by the phase difference from the input signal S 1 and the output signal S 2 to the analog filter circuit 5. Detected. FIG. 2C shows the input signal S1 and the output signal S2. In order to detect the delay time (phase delay) Td from these, the microcomputer 4 uses an input capture 4b. Prior to that, waveform shaping is performed by the comparison circuit 7.

  In the comparison circuit 7, the power supply voltage Vd is generated by dividing the power supply voltage Vd by the resistors 7c and 7d as the reference voltage Vs, and this is set in the comparators 7a and 7b. Each of the comparators 7a and 7b outputs a high level signal when the input signal S1 and the output signal S2 exceed the reference voltage Vs. When the signals from the comparators 7a and 7b are input, the input capture 4b of the microcomputer 4 detects the rising timing of these signals, and detects the phase difference from the difference between the rising times of the two signals. Data of the detected phase difference (delay time Td) is stored in a memory such as an internal RAM, and is read out and used for correction described later.

  On the other hand, the analog output signal S2 from the analog filter circuit 5 is input to the A / D conversion circuit 4a of the microcomputer 4 and A / D converted at a predetermined timing to obtain a digital signal. The microcomputer 4 performs A / D conversion processing corresponding to the signal for every 5 ° CA among the detection signals for every 1 ° CA of the crank angle inputted from the NE sensor 3 via the waveform shaping circuit 9. Then, with respect to the digital signal obtained at this time, the phase delay of the signal is corrected based on the data of the delay time Td stored in the memory as described above. The microcomputer 4 controls the engine based on the signal from the CPS 2 thus obtained.

Next, the delay time detection and correction processing operation will be described with reference to the flowchart of FIG.
The flowchart shown in FIG. 3 shows the processing contents executed by the microcomputer 4. The microcomputer 4 is programmed to execute a flowchart according to a signal for each crank angle of 1 ° CA input from the NE sensor 3.

  That is, when the microcomputer 4 starts the program, first, the counter of the crank angle is added and advanced by 1 ° CA (A1), and the counter value of the advanced crank angle is reduced by “1” from a multiple of 5. It is determined whether it is a value (= (5 × i−1) ° CA?) (A2). If it does not correspond to this angle, it is subsequently determined whether or not the counter value of the crank angle is a multiple of 5 (5 × i) (A3).

  When the counter value of the crank angle becomes (5 × i−1) ° CA and the microcomputer 4 determines “YES” in step A2, the signal input from the comparison circuit 7 is input to the edge of the edge by the input capture 4b. Detection is performed (A4). The input signal S1 and the output signal S2 to the analog filter circuit 5 are respectively compared with the reference voltage Vs by the comparison circuit 7, and when the waveform-shaped signal which is the comparison result is input to the input capture 4b, its rising timing Edges are detected. The microcomputer 4 calculates the time difference between the edges as a delay time Td (A5), stores it in a RAM, which is a memory provided therein (A6), and ends the program.

  Next, when the counter value of the crank angle advances by 1 ° CA and becomes (5 × i) ° CA, and the microcomputer 4 determines “YES” in step A3, it passes through the analog filter circuit 5 and performs anti-aliasing. The filtered output signal S2 is taken in (A7) and converted into a digital signal by the A / D conversion circuit 4a (A8). Thereafter, the microcomputer 4 reads the delay time Td stored previously from the RAM (A9), corrects the phase delay of the digital signal obtained by A / D conversion based on the data of the delay time Td (A10), The process ends.

  Thereafter, every time the counter value of the crank angle becomes (5 × i−1) ° CA or (5 × i) ° CA, the microcomputer 4 repeatedly executes the above-described processing, and every time the crank angle is 5 ° CA. The output signal of the analog filter circuit 5 is A / D converted to correct the delay time. As a result, even when a phase delay due to initial tolerance, temperature tolerance, and durability tolerance of each component constituting the analog filter circuit 5 occurs, the delay time Td is detected and corrected each time so that the crank angle is accurately determined. It becomes possible to acquire the sensor signal of CPS2 synchronized with the.

  According to this embodiment, signals S1 and S2 before and after passing through the analog filter circuit 5 are compared with the input sensor signal by the comparison circuit 7, and the rising timing is detected by the input capture 4b of the microcomputer 4. Then, the phase difference between the two is calculated as a delay time (phase delay time) Td and stored in a RAM which is an internal memory. By correcting the A / D converted digital signal using the delay time Td stored in the RAM, the phase can be accurately adjusted regardless of the characteristics of the resistors 5b and 5c and the capacitors 5d and 5e used in the analog filter circuit 5. Corrections can be made. This also makes it possible to improve the accuracy of phase correction at low cost without adjusting the resistors 5b and 5c and the capacitors 5d and 5e used in the analog filter circuit 5.

Further, according to the above embodiment, the delay time Td of the output signal S2 of the analog filter circuit 5 is detected prior to the A / D conversion every time the A / D conversion is performed. It is possible to correct the sensor signal of the CPS 2 by reliably following the variation of the delay time Td caused by the tolerance of the components constituting the circuit 5.
Then, the input signal S1 and the output signal S2 of the analog filter circuit 5 are input to the microcomputer 4 as signals that have been subjected to waveform shaping by the comparison circuit 7, so that the delay time Td can be accurately detected with a simple and inexpensive configuration. it can.

  Further, in the microcomputer 4, the signal from the comparison circuit 7 is input by the input capture 4 b to detect the edge, so that the detection operation can be quickly performed using the function of the microcomputer 4, and the software processing It is possible to avoid the occurrence of defects due to the delay of the start timing as compared with the case where

(Second Embodiment)
FIG. 4 shows a second embodiment of the present invention, which differs from the first embodiment in that the detection operation of the delay time Td and the correction operation of the sensor signal of CPS 2 are performed simultaneously.
That is, every time the crank angle advances by 1 ° CA, the microcomputer 4 executes the program and adds the count value (B1), but the counter value becomes (5 × i) ° CA, and the microcomputer 4 If “YES” is determined in B2, the edge of the signal input from the comparison circuit 7 is detected by the input capture 4b in the same manner as in the first embodiment (B3), and the time difference between these edges is calculated as the delay time Td. (B4).

Thereafter, the microcomputer 4 takes in the output signal S2 that has passed through the analog filter circuit 5 and has been subjected to anti-aliasing filtering (B5), and converts it into a digital signal by the A / D conversion circuit 4a (B6). Thereafter, the microcomputer 4 corrects the digital signal obtained by the A / D conversion with the data of the delay time Td calculated in step B4 (B7), and ends the process.
Thereafter, every time the counter value of the crank angle becomes (5 × i) ° CA, the microcomputer 4 repeatedly executes the above-described processing, A / D-converts the output signal of the analog filter circuit 5 and sets the delay time. Make corrections.

Also by such 2nd Embodiment, the effect similar to 1st Embodiment can be acquired.
Further, in this embodiment, since the detection operation of the delay time Td and the correction process of the sensor signal are performed in a lump, the processing load on the microcomputer 4 can be reduced at other crank angle count values. Can be executed.

(Third embodiment)
5 and 6 show a third embodiment of the present invention. The difference from the first embodiment is that a plurality of sensors used for engine control are provided.
In FIG. 5, as an overall configuration, compared to the configuration of the first embodiment in FIG. 1, the electronic control device 1 a includes three CPSs 10 to 12 as other sensors in addition to the CPS 2 as a sensor. . This corresponds to a situation where a CPS is provided for each cylinder when the engine has four cylinders, for example. Analog filter circuits 13 to 15 are provided corresponding to the three additional CPSs 10 to 12, respectively. Furthermore, A / D conversion circuits 4c to 4e are added to the inside of the microcomputer 4 so as to correspond to the added CPSs 10 to 12, respectively.

  Note that in contrast to the addition of these CPSs 10 to 12, the input capture 4b for detecting the delay time is not added, and the configuration corresponding to the CPS 2 is merely provided. For example, when the phase delay due to the temperature tolerance / durability tolerance of each component constituting each of the analog filter circuits 5 and 13 to 15 provided corresponding to the CPSs 2 and 10 to 12 is not significantly different All delay times Td can be corrected by measuring the delay time Td of one analog filter circuit 5 as a representative.

  The microcomputer 4 performs the same delay time detection and correction processing as in the first embodiment for each of the CPSs 2 and 10 to 12 corresponding to each cylinder. As shown in FIG. 6 (a), with respect to the sensor signal of CPS2 provided in each cylinder, the microcomputer 4 determines that the counter value of CPS2 when the counter value of the crank angle of each cylinder becomes (5 × i−1) ° CA. The delay time Td is calculated (C1 to C6), and the program ends. Thereafter, when the counter value of the crank angle of each cylinder advances by 1 ° CA and reaches (5 × i) ° CA, the microcomputer 4 determines “YES” in step C3, and analogizes each CPS 2, 10-12. The output signals that have passed through the filter circuits 5 and 13 to 15 and subjected to anti-aliasing filtering are taken in (FIGS. 6B to 6E, D1a to D1d), and digitalized by the A / D conversion circuits 4a and 4c to 4e. It converts into a signal (Drawing 6 (b)-(e), D2a-D2d). Thereafter, the microcomputer 4 reads the previously stored delay time Td from the RAM (FIGS. 6B to 6E, D3a to D3d), and is obtained by A / D conversion using the data of the delay time Td. The digital signal is corrected (FIGS. 6B to 6E, D4a to D4d), and the process ends.

  Thereafter, every time the counter value of the crank angle becomes (5 × i−1) ° CA or (5 × i) ° CA for each cylinder, the microcomputer 4 repeatedly executes the above processing, and the crank angle 5 The delay time is corrected by A / D converting the output signals of the analog filter circuits 5 and 13 to 15 for each CA. As a result, even if a phase delay due to temperature tolerance / durability tolerance of each component constituting the analog filter circuits 5 and 13 to 15 occurs, the delay time Td is detected and corrected each time so that the crank angle is obtained. It is possible to acquire a CPS2 sensor signal that is accurately synchronized.

  According to the present embodiment as described above, the delay time of one CPS 2 is detected and stored in the RAM for the CPSs 2 and 10 to 12 provided corresponding to the cylinders, and the four CPSs 2 and 10 to 12 are stored. Regardless of the characteristics of the components used in each analog filter circuit 5, 13 to 15, the sensor signal can be accurately corrected by correcting the digital signal that has been A / D converted using the delay time Td of the analog filter circuit 5. The phase can be corrected.

(Fourth embodiment)
FIG. 7 shows a fourth embodiment of the present invention. The following description will be focused on differences from the first embodiment. In this embodiment, the delay time Td is calculated and corrected at the same timing as in the first embodiment. In the process of calculating the delay time Td, the average value of a plurality of delay time information is recalculated and calculated. The delay time Td (ave) is used.

  When the microcomputer 4 starts the program of FIG. 7, when the counter value of the crank angle reaches (5 × i−1) ° CA (executes E1 to E3 and “YES” in E2), CPS2 The delay time Td is calculated by taking in the output of the analog filter circuit 5 through which the sensor signal passes (E4, E5). Thereafter, the microcomputer 4 reads the average delay time Td (ave) of the data of the delay time Td detected so far (E7), and uses the average delay time Td (ave) and the detected delay time Td as an average delay time. Td (ave) is recalculated (E7) and stored in the RAM (E8).

  Next, when the crank angle counter value advances by 1 ° CA and reaches (5 × i) ° CA (“YES” in E3), the microcomputer 4 outputs the output signal of the analog filter circuit 5 as described above. S2 is captured (E9) and converted into a digital signal by the A / D conversion circuit 4a (E10). Subsequently, the microcomputer 4 reads the average delay time Td (ave) stored in the RAM (E11), corrects the digital signal obtained by the A / D conversion (E12), and ends the processing.

Thereby, by obtaining the average value of the data of the plurality of delay times Td detected in the past, the fluctuation of the delay time Td due to accidental noise or the like can be absorbed to improve the detection accuracy of the data of the delay time Td. It is possible to correct the delay time with certainty.
In the above case, in the recalculation processing of the average delay time Td (ave), information on the average delay time of a past fixed time (for example, 5 minutes) is used, and the average value with the newly calculated delay time Td is calculated. There are a method of calculating, a method of recalculating the average value of data of the predetermined delay times Td in the past, and the like. Also, the average delay time Td (ave) can be obtained by performing a plurality of delay time detection processes prior to the A / D conversion process and calculating an average value thereof.

  According to the fourth embodiment, the same effect as that of the first embodiment can be obtained, and furthermore, a highly accurate delay time can be detected and an A / D converted digital signal can be corrected. it can.

(Other embodiments)
In addition, this invention is not limited only to one embodiment mentioned above, It can apply to various embodiment in the range which does not deviate from the summary, For example, it can deform | transform or expand as follows. .

  In each of the above embodiments, the case where the delay time generated in the analog filter circuit 5 is detected every time A / D conversion is performed has been described. When there is relatively little change in the delay time characteristic, the data of the delay time detected once can be used for a plurality of correction processes. In this case, it is a condition that the characteristic of the delay time does not change suddenly and is relatively stable. Accordingly, it is possible to set a condition such that the frequency of delay time detection is performed at regular intervals, for example, and the burden of delay time detection processing by the microcomputer 4 can be reduced.

The A / D conversion means uses an A / D conversion circuit 4 a attached to the microcomputer 4, but an A / D conversion circuit may be provided separately from the microcomputer 4.
In the third embodiment, the delay time of one analog filter circuit is detected and corrected for a plurality of analog filter circuits 5 and 13 to 15, but each analog filter circuit 5 and 13 to 15 is supported. Then, the delay time may be individually detected and corrected for each sensor signal.

The timing for performing the A / D conversion is set to a crank angle of 5 ° CA, but other than this, it can be performed at an appropriate angle such as 10 ° CA or 20 ° CA.
Although the case of CPS2 was shown as a sensor, it can also be applied to correction of the delay time of the sensor signal of a sensor used for other engine control. As a sensor, for example, it can be applied to a knock sensor or the like.

  In the drawings, 1, 1a is an electronic control device (sensor signal processing device), 2, 10-12 are CPS (sensor), 3 is an NE sensor, 4 is a microcomputer (correction means), 4a, 4c-4e are A. / D conversion circuit (A / D conversion means), 4b is an input capture (delay time detection means), 5, 13-15 are analog filter circuits, and 7 is a comparison circuit (comparison means).

Claims (10)

An analog filter circuit to which a sensor signal from a sensor used for controlling a vehicle engine is input;
A / D conversion means for converting an analog sensor signal output from the analog filter circuit into a digital signal;
A delay time detecting means for detecting a delay time by filtering from the sensor signal at the time of input and output to the analog filter circuit;
Correction means for correcting the phase delay of the digital signal output from the A / D conversion means using the information on the delay time detected by the delay time detection means;
A sensor signal processing apparatus for engine control, comprising: The sensor signal processing apparatus for engine control according to claim 1,
A plurality of sensors used to control the engine of the vehicle are provided,
The analog filter circuit to which the sensor signal is input and the A / D conversion means are provided in a plurality corresponding to each of the plurality of sensors,
The delay time detection means is provided to detect the delay time for a sensor signal input to one of the plurality of analog filter circuits,
The correction means corrects the phase delay of the digital signals output from all the A / D conversion means using the information on the delay time detected by the delay time detection means. Sensor signal processing device. The sensor signal processing device for engine control according to claim 1 or 2,
A rotation angle detecting means for inputting a sensor signal of a rotation sensor for detecting rotation of the engine and acquiring an engine rotation angle signal;
The A / D conversion means converts an analog sensor signal into a digital signal at a timing of a rotation angle signal detected for each predetermined rotation angle detected by the rotation angle detection means,
The delay time detection means detects the delay time at the timing of a rotation angle signal detected by the rotation angle detection means for each predetermined rotation angle, and is a sensor signal processing apparatus for engine control. The sensor signal processing device for engine control according to claim 1 or 2,
A rotation angle detecting means for inputting a sensor signal of a rotation sensor for detecting rotation of the engine and acquiring an engine rotation angle signal;
The A / D conversion means converts an analog sensor signal into a digital signal at a timing of a rotation angle signal detected for each predetermined rotation angle detected by the rotation angle detection means,
The delay time detection means detects the delay time when the rotation angle detection means detects a rotation angle signal after a predetermined time has elapsed, and is a sensor signal processing apparatus for engine control. . The sensor signal processing device for engine control according to claim 3 or 4,
The delay time detection means detects the delay time at the same timing as the conversion processing by the A / D conversion means, and is a sensor signal processing apparatus for engine control. The sensor signal processing device for engine control according to claim 3 or 4,
The delay time detection means detects the delay time at the timing of a rotation angle signal detected prior to the conversion processing by the A / D conversion means, and processes the sensor signal for engine control. apparatus. The sensor signal processing device for engine control according to claim 1 or 2,
A rotation angle detecting means for inputting a sensor signal of a rotation sensor for detecting rotation of the engine and acquiring an engine rotation angle signal;
The A / D conversion means converts an analog sensor signal into a digital signal at a timing of a rotation angle signal detected for each predetermined rotation angle detected by the rotation angle detection means,
The delay time detecting means detects the delay time when the rotation angle detecting means detects the rotation angle signal a plurality of times, and calculates the delay time by averaging the obtained plurality of delay times. A sensor signal processing apparatus for engine control. The sensor signal processing device for engine control according to any one of claims 1 to 7,
The delay time detection means includes comparison means for comparing the sensor signals at the time of input and output to the analog filter circuit with a predetermined reference level, and detects the delay time from the comparison result output by the comparison means. A sensor signal processing apparatus for engine control. The sensor signal processing apparatus for engine control according to claim 8,
The delay time detection means has an input capture function, and captures the comparison result output of the comparison means by the input capture function. The sensor signal processing device for engine control according to any one of claims 1 to 9,
A sensor signal processing device for engine control, wherein the sensor is a cylinder pressure sensor (CPS).

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