JP2016160858A - Crank angle correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crank angle correction device capable of correcting a crank angle by accurately detecting a tooth missing section even when pulse omission occurs on a crank signal in sections excluding the tooth missing section.SOLUTION: A crank angle correction device includes a first edge interval measuring portion for measuring an edge interval of pulses in a crank signal, a second edge interval measuring portion for measuring an edge interval of pulses in a cam signal, a section detecting portion for detecting a section of a length corresponding to a tooth missing section on the basis of the edge interval measured by the first edge interval measuring portion, a determining portion for determining whether the detected section is the tooth missing section determined in advance to the cam signal or not, on the basis of a lapse of time from the edge of the pulse in the cam signal and the edge interval measured by the second edge interval measuring portion, when the section of the length corresponding to the tooth missing section is detected by the section detecting portion, and a crank angle correcting portion for correcting the crank angle by using the section determined as the tooth missing section by the determining portion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus for correcting a crank angle used for vehicle engine control.

  In a vehicle, the crank angle is used to determine the engine fuel injection and ignition control timing. The crank angle is detected by a crank angle detection device from a crank signal generated by the crank angle sensor. The crank angle sensor detects teeth provided at predetermined angular intervals on the outer periphery of the crank rotor fixed to the crankshaft, and generates a crank signal by generating a pulse corresponding to the position of each tooth.

  In order to correct the crank angle based on the crank signal and specify the engine control timing, it is necessary to know the angle position in one cycle of the crank angle. Normally, a missing tooth section is provided in the crank signal by detecting a missing tooth provided at the angle reference position on the outer periphery of the crank rotor by a crank angle sensor. The angular position of the crank angle can be known by detecting the missing tooth section and referring to the phase of the cam signal used for cylinder discrimination.

  The missing tooth section is a section in which a predetermined number of crank pulses are thinned out, and has an edge interval larger than the edge interval between successive crank pulses. Therefore, when the input edge interval is larger than a predetermined multiple of the edge interval input immediately before, it is detected that a missing tooth section has appeared.

  When a section that is not a missing tooth section is erroneously detected as a missing tooth section, the angle count is corrected based on the erroneously detected section and the engine control timing is incorrect, so a method for preventing erroneous detection has been proposed. Patent Document 1 discloses a configuration that avoids erroneous detection of a missing tooth section due to noise superimposed on a crank signal. Noise can be an edge interrupted between crank pulses due to superposition. Therefore, when an edge interval between successive crank pulses is input following an edge interval between crank pulses and noise, erroneous detection of a missing tooth section may occur. In Patent Document 1, when an edge interval that can be a missing tooth interval is detected, the original missing tooth interval is detected by detecting whether the edge interval immediately after the interval is an edge interval between crank pulses. It is determined whether or not it has been done.

JP 2013-108366 A

  However, in the above-described conventional method, when a missing pulse is generated in a crank signal other than a missing tooth section, there is a possibility that a section in which the missing pulse is generated is erroneously detected as a missing tooth section. There is no technique having a criterion for determining whether or not the pulse missing section is a missing tooth section when the missing pulse section is the same length as the missing tooth section.

  In view of the above problems, the present invention provides a crank angle correction device capable of correctly detecting a missing tooth section and correcting a crank angle even if a missing pulse occurs in a crank signal other than the missing tooth section. is there.

  A first invention is a crank angle correction device that corrects a crank angle based on an input crank signal and a cam signal, and a first edge interval measuring unit that measures an edge interval of pulses in the crank signal; A section having a length corresponding to a missing tooth section based on the second edge interval measuring unit for measuring the edge interval of the pulse in the cam signal and the edge interval measured by the first edge interval measuring unit When a section having a length corresponding to a missing tooth section is detected by the section detecting section, and the section detecting section detects the passage of time from the edge of the pulse in the cam signal, and the second edge interval measurement A determination unit that determines whether or not the detected interval is a predetermined missing tooth interval for the cam signal based on the edge interval measured by the unit; and the missing tooth interval by the determination unit Using the determined section and a, a crank angle correction unit that corrects the crank angle.

  According to the first invention, when the section detector detects a section having a length corresponding to the missing tooth section based on the edge interval of the pulse in the crank signal measured by the first edge interval measuring section, the determination The unit makes the following determination. The determination unit determines whether the detected interval is predetermined for the cam signal based on the elapsed time from the edge of the pulse in the cam signal and the edge interval measured by the second edge interval measurement unit. It is determined whether or not the tooth section. The crank angle correction unit corrects the crank angle using the section determined as the missing tooth section by the determination unit. Therefore, a missing pulse section that occurs outside the missing tooth section in the crank signal is not a predetermined missing tooth section for the cam signal, and is not erroneously determined to be a missing tooth section. The crank angle is corrected based on the correctly detected missing tooth section.

  According to the present invention, it is possible to provide a crank angle correction device capable of correctly detecting a missing tooth section and correcting the crank angle even if a missing pulse occurs outside the missing tooth section in the crank signal.

The block diagram which shows the structure of the crank angle correction apparatus which concerns on embodiment of this invention. Signal waveform diagram for explaining the operation of the crank angle correction device according to the embodiment of the present invention The flowchart explaining operation | movement of the crank angle correction apparatus which concerns on embodiment of this invention. Signal waveform diagram illustrating another process of the crank angle correction device according to the embodiment of the present invention Timing chart explaining the effect of the crank angle correction device according to the embodiment of the present invention

Hereinafter, embodiments will be described in detail with reference to FIGS.
[Overview]
The crank angle correction device according to the present embodiment detects a section having a length corresponding to a missing tooth section based on an edge interval of pulses (crank pulses) in a crank signal. Based on the elapsed time from the edge of the pulse in the cam signal (the pulse whose level transitions to high and low) and the measured edge interval, the detected interval is predetermined for the cam signal. It is determined whether or not the tooth section. The crank angle is corrected using a section determined as a missing tooth section. Therefore, a missing pulse section that occurs outside the missing tooth section in the crank signal is not a predetermined missing tooth section for the cam signal, and is not erroneously determined to be a missing tooth section. The crank angle is corrected based on the correctly detected missing tooth section.

[Crank signal and cam signal]
First, the crank signal and cam signal will be described. FIG. 2I shows examples of the crank signal and cam signal waveforms. Each position in the crank signal and the cam signal is represented by a phase, and time advances in the positive direction of the phase axis. The crank signal output from the crank angle sensor 3 has a waveform in which crank pulses P are arranged as shown in FIG. In the two crank pulses P before and after, the interval from the rising edge of the preceding pulse to the rising edge of the subsequent pulse is defined as the edge interval v. The value of the edge interval v is represented by a phase difference. The edge interval v in the section where there is no missing pulse has the minimum value α, and the edge interval v in the missing tooth section has the value β (α <β). The phase difference of such a period on the phase axis is obtained by determining the ratio of the measurement time of the period to the measurement time of α, where α is a reference phase difference.

  The cam signal output from the cam position sensor 4 has a waveform in which a positive cycle and a negative cycle are alternately switched. FIG. 2I shows a waveform of one polarity cycle of the cam signal. The cycle has a waveform in which a level transition is performed so as to switch between a high value and a low value in a period T. The other polarity cycle has a waveform whose phase is inverted from that of the waveform. When the current time is represented by phase O, in each of phases A to F sequentially shown from the phase O in the past, an edge that is a place where the level transition of the cam signal has occurred appears. In FIG. 2I, the period T includes a high period ZA, a low period AB, a high period BC, a low period CD, a high period DE, including a period OZ to be input of the cam signal. It consists of each partial section of the low period EF. However, the waveform of the cam signal is not a waveform in which the lengths of all the partial sections are equal.

The missing tooth section of the crank signal appears at a predetermined phase of the cam signal. That is, the missing tooth section appears at a predetermined position (phase) with respect to each edge of the cam signal. In the case of the cam signal shown in (I) of FIG. 2, assuming that the missing tooth section appears at the current time (phase O), the period OA = t _k0 , the period AB = t _k1 , the period BC = t _k2 , the period CD = t _k3 , period DE = t _k4 , period EF = t _k5 . In this case, the appearance position (phase O) of the missing tooth section is at a position separated from the edge (phase A) input immediately before the cam signal by a phase difference of t _k0 . In addition, other edges are present in the order of the phase difference of t _k1 , t _k2 , t _k3 , t _k4 , and t _k5 in order from the edge input immediately before, and the position where the missing tooth section appears is The phase difference from the other edge to the phase O is at a position separated by an accumulation.

[Configuration of crank angle correction device]

  FIG. 1 shows a configuration of a crank angle correction device 1 according to the present embodiment. The crank angle correction device 1 corrects the crank angle based on the input crank signal and cam signal, and inputs a trigger signal based on the crank angle cycle timing to the engine control device 2. The engine control device 2 outputs engine control signals such as fuel injection and ignition at a timing according to the input trigger signal. Below, the detailed structure of the crank angle correction apparatus 1 is demonstrated.

  The crank angle correction apparatus 1 includes a first edge interval measurement unit 11, a section detection unit 12, a second edge interval measurement unit 21, an edge interval storage unit 22, a missing tooth section determination unit 23, a known amount storage unit 24, a clock A source generation unit 31, an angle counter unit 32, a cam signal value measurement unit 33, an angle counter correction unit 34, and a compare match interrupt unit 35 are provided. The edge interval storage unit 22, the missing tooth section determination unit 23, and the known amount storage unit 24 constitute a determination unit 1a. The clock source generation unit 31, the angle counter unit 32, the cam signal value measurement unit 33, the angle counter correction unit 34, and the compare match interrupt unit 35 constitute a crank angle correction unit 1b.

  The first edge interval measuring unit 11 measures each edge interval v of the crank signal input from the crank angle sensor 3 every time the rising edge of the crank pulse P appears. The section detector 12 detects a section of an edge interval corresponding to the length of the missing tooth section (hereinafter referred to as “missing tooth equivalent section”). If the ratio of the edge interval v of the section appearing at the current time (phase O) to the edge interval v of the section appearing immediately before is β / α, the edge interval v of the section appearing at the current time is missing. It shall correspond to the length of the section. The section detection unit 12 inputs that the missing tooth equivalent section has been detected to an edge interval storage unit 22 and a missing tooth section determination unit 23 described later.

The second edge interval measuring unit 21 stores the edge position of the input cam signal, and measures the edge interval that defines the length of the partial section every time the input of the partial section of the cam signal is completed. . In FIG. 2 (II), the edge intervals of the period AB, the period BC, the period CD, the period DE, and the period EF, which are the partial sections, are sequentially shown as t ₁ , t ₂ , t ₃ , t ₄ , and t _5. ing. In the following description, when representatively describing each edge interval, it is referred to as an edge interval t.

[Configuration of judgment unit]
Next, a detailed configuration of the determination unit 1a will be described. The determination unit 1a determines whether or not the missing tooth equivalent section detected by the first edge interval measuring unit 11 is a missing tooth section. As shown in FIG. 2 (II), a pulse missing section in the crank signal having an edge interval v of β but not a missing tooth section is described with reference to the cam signal in FIG. It appears at a position different from the predetermined position. Therefore, the determination unit 1a determines whether or not the missing tooth equivalent section is a predetermined missing tooth section for the cam signal based on the position of the missing tooth equivalent section with respect to the edge of the cam signal.

  The edge interval storage unit 22 stores the edge interval t measured by the second edge interval measurement unit 21 and the position where the latest edge is input. When the number of level transitions in one polarity cycle of the cam signal is n (n is an integer of 2 or more), the number of edge intervals t to be stored is set to n-1 in order from the latest. Each time the edge interval is newly measured, the stored information on the oldest edge interval is deleted. In FIG. 2 (II), since the number of level transitions is 6, a total of 5 edge intervals t are always stored. Of the stored edge intervals t, the i-th (i is a natural number) counted from the latest one is the i-th generation edge interval, and in FIG. 2 (II), from the first generation to the fifth generation The edge interval is stored. Further, when the fact that a missing tooth equivalent section is detected from the section detection unit 12 is input to the edge interval storage unit 22, n−1 number of edge intervals t and the latest edge are input from the edge interval storage unit 22. The missing position is read by the missing tooth section determination unit 23.

When a missing tooth equivalent section is input from the section detecting unit 12 as input, the missing tooth section determining unit 23 determines whether or not the missing tooth equivalent section is a missing tooth section. The known amount storage unit 24 stores, as known values of the cam signal used for the determination, the values of t _k0 to t _k5 described in (I) of FIG. 2 and the value of a determination allowable error Δt described later. ing. Details of this determination processing will be described later.

[Configuration of crank angle correction unit]
The crank angle correction unit 1b corrects the crank angle based on the section determined as the missing tooth section by the determination unit 1a. The clock source generation unit 31 receives the edge interval v from the first edge interval measurement unit 11. The clock source generation unit 31 obtains a clock signal having a cycle of 1 CA (crank angle) from the minimum edge interval v (= α) by multiplication. The clock signal is input to the angle counter unit 32. The angle counter unit 32 counts the number of clocks of the clock signal input from the clock source generation unit 31 to obtain a change in the crank angle phase. For example, in a four-stroke engine, the period T in FIG. 2 (I) has a length of 360 CA, and one engine cycle period has a length of 720 CA.

  The cam signal value measurement unit 33 sequentially measures the high or low value of the cam signal and inputs it to the angle counter correction unit 34. The angle counter correction unit 34 performs an input to the angle counter unit 32 according to the determination result by the missing tooth section determination unit 23. If the section of the edge interval v is a missing tooth section, the count value corresponding to the known angular position where the missing tooth section is located is the angle counter as the correct count value that the angle counter unit 32 should currently take. Input to the unit 32. If the interval of the edge interval v is not a missing tooth interval, an instruction to set the correction amount from the count value corresponding to the terminal side edge position of the interval of the edge interval v to zero is input to the angle counter unit 32.

  Since the cam signal has a positive cycle and a negative cycle as described above, the angle counter unit 32 uses the input content from the cam signal value measurement unit 33 to determine the correct count value to be taken at present. Check the positive and negative phases with reference. The angle counter unit 32 corrects the angle position of the crank angle by matching its own count value with the input from the angle counter correction unit 34, and performs subsequent counting.

  The compare match interrupt unit 35 inputs a trigger for generating an event to the engine control device 2 at a timing when the count value input from the angle counter unit 32 reaches an angular position at which each event of engine control is generated.

[Processing by judgment unit]
Next, details of processing by the determination unit 1a will be described with reference to FIG.

  Consider a state in which a missing tooth equivalent section (v = β) appears in the crank signal as shown in (II) of FIG. In this case, the missing tooth section determination unit 23 performs the following process.

First, when it is input that the missing tooth equivalent section is detected from the section detecting unit 12, the missing tooth section determining unit 23 starts from the latest edge (phase A) of the input cam signal to the current time (phase O). An interval t ₀ corresponding to the elapsed time until is measured. The position where the latest edge is input is read from the edge interval storage unit 22. Here, it is assumed that there is no signal delay in the crank angle correction apparatus 1. Then, the missing tooth section determination unit 23 reads the values of t _k0 and Δt from the known amount storage unit 24, and t ₀
t _k0 −Δt ≦ t ₀ ≦ t _k0 + Δt (1)
It is determined whether or not the above is satisfied. The missing tooth section determination unit 23 determines that the missing tooth equivalent section is not a predetermined missing tooth section for the cam signal when t ₀ does not satisfy the expression (1). The missing tooth section determination unit 23 further performs the following process when t ₀ satisfies the expression (1).

The missing tooth section determination unit 23 measures the first generation edge interval t ₁ (period AB) of the input cam signal. Then, the missing tooth section determination unit 23 reads the values of t _k1 and Δt from the known amount storage unit 24, and t ₁
t _k1 −Δt ≦ t ₁ ≦ t _k1 + Δt (2)
It is determined whether or not the above is satisfied. The missing tooth section determination unit 23 determines that the missing tooth equivalent section is not a predetermined missing tooth section for the cam signal when t ₁ does not satisfy the expression (2).

Toothless section determination unit 23, thus, measures the i-th generation edge interval t _i of the input cam signal, as long as the edge interval t _i is within a specified range of t _ki ± Delta] t, the i n- Increase by 1 to 1. Then, when the missing tooth section determining unit 23 determines that the edge interval t _i is not in the range of t _ki ± Δt, the missing tooth equivalent section is not a predetermined missing tooth section for the cam signal. judge. On the other hand, when the missing tooth section determination unit 23 determines that the edge interval t _i is in the range of t _ki ± Δt for all i, the missing tooth equivalent section is a predetermined missing tooth section for the cam signal. Judge that there is.

  Next, the above-described processing procedure by the missing tooth section determination unit 23 is summarized in the flowchart of FIG. The flow of FIG. 3 may be performed by an IC or LSI, or may be performed by a processor executing a program read from a storage medium.

First, in step S101, the missing tooth section determination unit 23, when the fact that the missing tooth equivalent section has been detected is input from the section detection unit 12, the current edge position (phase A) of the input cam signal is detected. The interval t ₀ until the time (phase O) is measured. In the subsequent step S102, the generation number i to be read out of the edge interval t of the cam signal stored in the edge interval storage unit 22 is set to zero.

  In the next step S103, whether or not i ≦ n−1 (n is the number of level transitions in one polarity cycle of the cam signal), that is, whether or not the generation number i is in the range of the number of generations stored. Determine whether or not. If i ≦ n−1 in step S103, the process proceeds to step S104, and if i = n, the process proceeds to step S106.

In step S104, it is determined whether or not the conditional expression t _ki −Δt ≦ t ₁ ≦ t _ki + Δt is satisfied. If the conditional expression is satisfied in step S104, the process proceeds to step S105. If the conditional expression is not satisfied, the process proceeds to step S107.

  In step S105, i is incremented by one. When the process of step S105 ends, the process returns to step S103.

  In step S106, it is determined that the detected missing tooth equivalent section is a missing tooth section predetermined for the cam signal. In step S107, it is determined that the detected missing tooth equivalent section is not a predetermined missing tooth section for the cam signal. Thus, this flow ends.

In addition, the determination process of a missing tooth section as shown in FIG. 4 is also possible. In this process, the missing tooth equivalent section (v = β) is missing based only on whether or not the interval t ₀ from the latest edge of the cam signal to the current time (phase O) satisfies the above expression (1). It is determined whether or not the tooth section.

FIG. 4 shows a cam signal having, for example, three edges (phases A, B, and C) in the period T. When the missing tooth section appears, the interval t _k0 from the latest edge (phase A) of the cam signal to the current time (phase O) is greater than the edge interval t _k1 of the period AB and the edge interval t _{k2 of the} period BC. May be big. In this case, the interval t ₀ of the measured period OA is (1) if the specified range of the formula, the edge interval t ₁ and the measured period BC of the measured period AB of edge interval t ₂ It does not happen that either is not within the specified range. Therefore, it is determined that the said toothless corresponds sections if it meets the spacing t ₀ (1) formula is a toothless section, and (1) the missing tooth corresponds interval if not satisfied expression is not toothless section determination Is possible.

[Effects of the embodiment, etc.]
Next, the effect by this embodiment is demonstrated. In FIG. 4, a missing tooth section of the crank signal indicated as “missing tooth” appears in each positive and negative cycle of the cam signal, and a pulse missing that is not a missing tooth section indicated as “non-missing tooth” in a cycle with the cam signal. Indicates the state where the section appears. When a normal angle count of the crank angle is performed, a constant count as indicated by a solid line is performed from 0CA to 720CA, and is reset to 0CA when reaching 720CA.

  According to the conventional crank angle detection method, when the missing pulse section is erroneously detected as a missing tooth section, as shown by the dotted line, when the missing pulse section ends, the angle count value is detected at the next edge detection event timing. Is erroneously corrected to the value to be taken after the end of the missing tooth section. As a result, the angle count value is reset when 720CA is reached after erroneous correction, and the angle count value in the cycle having the opposite polarity of the cam signal is further erroneously taken at the event timing after the next missing tooth section. It is corrected. The angle count value whose phase has been inverted gradually returns to the normal value at the event timing after the missing tooth section that appears two more times later. As described above, in the conventional method, if it is erroneously determined that the missing pulse section in the crank signal is a missing tooth section, the crank angle may be greatly shifted due to erroneous correction.

On the other hand, according to the crank angle detection method of the crank angle correction device 1 of the present embodiment, the pulse missing section that is not the missing tooth section (the missing tooth equivalent section) is determined by the determination process starting from the measurement of the interval t ₀ as described above. ) Is not a missing tooth section. As a result, as indicated by the dotted line, the count is continued without correcting the angle count value even when the pulse missing period ends. As a result, the angle counter value is corrected to a value to be taken at the event timing after the next missing tooth section, so that the normal angle counter value can be quickly restored. As described above, the crank angle correction apparatus 1 exhibits high robustness against noise in the crank signal that forms a section where a missing pulse equivalent to the missing tooth section has occurred. Thereby, highly accurate engine control becomes possible. This also reduces energy loss due to conventional erroneous control and contributes to improved fuel efficiency.

  As described above, according to the crank angle correction device 1, when a section having a length corresponding to the missing tooth section is detected based on the edge interval v measured by the first edge interval measuring unit 11, the determination is made. The unit 1a makes the following determination. The determination unit 1a predetermines the detected interval for the cam signal based on the elapsed time from the edge of the pulse in the cam signal and the edge interval measured by the second edge interval measurement unit 21. It is determined whether or not it is a missing tooth section. Then, the crank angle correction unit 1b corrects the crank angle using the section determined as the missing tooth section by the determination unit 1a. Therefore, a missing pulse section that occurs outside the missing tooth section in the crank signal is not a predetermined missing tooth section for the cam signal, and is not erroneously determined to be a missing tooth section. The crank angle is corrected based on the correctly detected missing tooth section. Therefore, it is possible to provide a crank angle correction device that can correctly detect a missing tooth section even if a missing pulse occurs outside the missing tooth section in the crank signal.

  The present invention is applicable to engine vehicles and the like.

DESCRIPTION OF SYMBOLS 1 Crank angle correction | amendment apparatus 1a Determination part 1b Crank angle correction | amendment part 2 Engine control apparatus 3 Crank angle sensor 4 Cam position sensor 11 1st edge space | interval measurement part 12 Section detection part 21 2nd edge space | interval measurement part 22 Edge space | interval memory | storage part 23 Missing tooth section determination unit 24 Known amount storage unit 31 Clock source generation unit 32 Angle counter unit 33 Cam signal value measurement unit 34 Angle counter correction unit 35 Compare match interrupt unit O, A, B, C, D, E, F, Z phase P crank pulse i generation number n number of level transitions t ₀ interval t, t ₁ , t ₂ , t ₃ , t ₄ , t ₅ edge interval v edge interval α, β value

Claims (1)

A crank angle correction device that corrects a crank angle based on an input crank signal and a cam signal,
A first edge interval measuring unit for measuring an edge interval of pulses in the crank signal;
A second edge interval measuring unit for measuring an edge interval of pulses in the cam signal;
A section detecting unit for detecting a section having a length corresponding to a missing tooth section based on the edge interval measured by the first edge interval measuring section;
When a section having a length corresponding to the missing tooth section is detected by the section detection unit, the time elapsed from the edge of the pulse in the cam signal, and the edge interval measured by the second edge interval measurement unit, A determination unit that determines whether or not the detected section is a predetermined missing tooth section with respect to the cam signal;
A crank angle correction unit that corrects the crank angle using the section determined to be a missing tooth section by the determination unit;
A crank angle correction device comprising:

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