JP6075179B2 - Rotation detector - Google Patents

Description

  The present invention relates to a rotation detection device that detects a rotation reference position of a rotating body.

  Conventionally, for example, Patent Document 1 proposes a determination device configured to detect a rotation reference position of a rotating body from a rotation signal of the rotating body detected by a sensor. The sensor outputs a rotation signal every time it faces a plurality of protrusions provided at equal intervals on the outer periphery of the rotating body. The rotating body is provided with a missing tooth portion having a protrusion. This missing tooth portion indicates the rotation reference position of the rotating body.

  Then, the determination device inputs a rotation signal from the sensor as needed, calculates a ratio of time intervals of the rotation signal, that is, a differential value of the time ratio of the rotation signal, and compares this differential value with a threshold value to detect the absence of the rotating body. Detect teeth. In this way, the determination device detects the rotation reference position of the rotating body.

JP 2012-167554 A

  However, in the above-described conventional technology, the determination device employs a method for determining a missing tooth portion using a time ratio of rotation signals. For this reason, there is a possibility that the differential value of the time ratio of the rotation signal exceeds the threshold value when the timing at which the determination device inputs the rotation signal from the sensor changes due to an instantaneous change in the rotation speed of the rotating body. . Therefore, there is a problem that the determination device erroneously detects the missing tooth portion. As described above, the conventional determination device has a problem that sufficient detection accuracy of the rotation reference position of the rotating body cannot be obtained.

  The present invention has been made in view of the above points, and has an object to provide a rotation detection device that can prevent erroneous detection of the rotation reference position of the rotating body and can improve the detection accuracy of the rotation reference position of the rotating body. To do.

  In order to achieve the above object, according to the first aspect of the present invention, a rotating body provided with an outer peripheral portion (21) and a rotation reference portion (23) indicating a rotation reference position at a part of the outer peripheral portion (21). A rotation detection device configured to detect a rotation reference position with respect to the rotation of (20), and is characterized by the following points.

First, it arrange | positions so that the outer peripheral part (21) of a rotary body (20) may be opposed, and while rotating a rotary body (20), while outputting the detection signal according to the position of an outer peripheral part (21), a rotary body The rotation reference position is detected by detecting the switching from the outer periphery (21) to the rotation reference portion (23) based on the gap with (20), and the rotation reference portion (23) to the outer periphery (21). A rotation detection sensor (30) for outputting a rotation reference position signal indicating position information of the rotation reference position at a detection timing at which the change from the rotation reference portion (23) to the outer peripheral portion (21) is detected by detecting the switch to I have.

In addition, a signal processing unit (40) that receives a detection signal and a rotation reference position signal from the rotation detection sensor (30) and acquires the rotation reference position based on the rotation reference position signal is provided. Moreover, rotation detecting sensor (30), after detecting the rotation reference position, in the period from the rotation reference part (23) until detecting the switching of the outer peripheral section (21), and outputs the rotation reference position signal A notice signal indicating this is output to the signal processing unit (40).

  According to this, since the position of the rotation reference portion (23) is detected by the rotation detection sensor (30), even if an instantaneous change in the rotation speed of the rotating body (20) occurs, the rotation reference portion (23 The rotation reference position is reliably detected without depending on the temporal change in the detection period. That is, the temporal determination of detecting the rotation reference position based on the detection period of the rotation reference unit (23) can be abolished. Therefore, erroneous detection of the rotation reference position of the rotating body (20) can be prevented, and the detection accuracy of the rotation reference position of the rotating body (20) can be improved.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

1 is a configuration diagram of an internal combustion engine to which a rotation detection device according to a first embodiment of the present invention is applied. It is the figure which showed the arrangement | positioning relationship between a signal rotor and a rotation detection sensor. It is the timing chart which showed the waveform signal, detection signal, and rotation reference position signal corresponding to the protrusion and missing tooth part of a signal rotor. It is a schematic diagram which produces | generates an angle signal and a missing tooth signal from a detection signal and a rotation reference position signal in ECU. It is a timing chart for demonstrating that a missing tooth signal is not produced | generated, even if a rotation nonuniformity arises in a signal rotor. In 2nd Embodiment, it is a timing chart which showed the waveform signal, the detection signal, and the rotation reference position signal. In 3rd Embodiment, it is a timing chart which showed the waveform signal, the detection signal, and the warning signal. In 4th Embodiment, it is a timing chart which showed the waveform signal, the detection signal (angle signal), and the rotation reference position signal (missing tooth signal).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The rotation detection device according to the present invention is used, for example, as a crank angle determination device for an internal combustion engine. As shown in FIG. 1, the rotation detection device includes a rotation detection sensor 30 disposed to face an outer peripheral portion 21 of a signal rotor 20 fixed to a crankshaft 11 of an engine 10 that is an internal combustion engine, and the engine 10. And an ECU (Electrical Control Unit) 40 that performs various controls.

  In the internal combustion engine, an intake pipe 13 is connected to the intake port 12 of the engine 10, and an exhaust pipe 15 is connected to the exhaust port 14 of the engine 10. A fuel injection valve 16 for injecting fuel toward the intake port 12 is attached in the vicinity of the intake port 12 of each cylinder. Further, a spark plug 17 is attached to the cylinder head of the engine 10 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of the spark plug 17 of each cylinder. The operations of the fuel injection valve 16 and the spark plug 17 are controlled by the ECU 40.

  As shown in FIG. 2, a plurality of protrusions 22 are provided at equal intervals on the outer peripheral portion 21 of the signal rotor 20, and a missing tooth portion 23 lacking one or more protrusions 22 at a specific crank angle is provided. Is provided. This missing tooth portion 23 corresponds to the rotation reference position of the signal rotor 20, that is, the reference angle of the crank angle. In the present embodiment, for example, 34 protrusions 22 are provided on the outer peripheral portion 21 of the signal rotor 20. Further, the missing tooth portion 23 is a portion of the outer peripheral portion 21 of the signal rotor 20 where, for example, two protrusions 22 are missing.

  The rotation detection sensor 30 is a sensor that outputs a pulsed detection signal corresponding to the position of the outer peripheral portion 21, that is, the crank angle as the signal rotor 20 rotates. The rotation detection sensor 30 is a so-called crank angle sensor.

  The rotation detection sensor 30 includes, for example, a first magnetoresistive element pair made up of a first magnetoresistive element and a second magnetoresistive element (not shown) and a second magnetoresistive element pair made up of a third magnetoresistive element and a fourth magnetoresistive element. And a processing operation circuit (not shown) for processing a signal detected by each magnetoresistive element. One set and two pairs of magnetoresistive elements are arranged to face the signal rotor 20. The first magnetoresistive element 1 and the second magnetoresistive element of the first magnetoresistive element pair constituting the half bridge circuit, and the third magnetoresistive element and the fourth magnetism of the second magnetoresistive element pair constituting the half bridge circuit. Each midpoint with the resistive element is connected to a processing arithmetic circuit.

  According to such a configuration of the rotation detection sensor 30, the pair and two pairs of magnetoresistive elements change the resistance value according to the rotational position of the signal rotor 20, that is, the presence or absence of the protrusion 22. As a result, the voltage at the midpoint of the magnetoresistive element changes. Therefore, the processing arithmetic circuit of the rotation detection sensor 30 acquires the change in the midpoint voltage as the waveform signal as the signal rotor 20 rotates. Then, the processing arithmetic circuit generates a detection signal obtained by binarizing the waveform signal by comparing the amplitude of the waveform signal with the binarization threshold value. Therefore, the rotation detection sensor 30 outputs a detection signal every time the protrusion 22 faces.

  The rotation detection sensor 30 detects the rotation reference position of the signal rotor 20 by detecting the switching from the protrusion 22 provided on the outer peripheral portion 21 to the missing tooth portion 23 based on the gap with the signal rotor 20. It has a function. Further, the rotation detection sensor 30 has a function of detecting a change from the toothless portion 23 to the protrusion 22 provided on the outer peripheral portion 21 and outputting a rotation reference position signal indicating position information of the rotation reference position at the detection timing. Have. In the present embodiment, the rotation detection sensor 30 outputs the rotation reference position signal with an amplitude larger than that of the detection signal. That is, the rotation reference position signal also includes detection signal information.

  The ECU 40 has a function of inputting a detection signal and a rotation reference position signal from the rotation detection sensor 30, and acquiring the position of the toothless portion 23 of the signal rotor 20, that is, the rotation reference position based on these signals. For this reason, as shown in FIG. 1, the ECU 40 includes a waveform processing unit 41 and a CPU 42.

  The waveform processing section 41 generates a first comparator 43 that generates an angle signal that indicates a crank angle from the detection signal and the rotation reference position signal, and a second that generates a missing tooth signal that indicates the position of the missing tooth portion 23 from the rotation reference position signal. And a comparator 44. In the present embodiment, each comparator is configured such that the first comparator 43 detects the detection signal and the rotation reference position signal, and the second comparator 44 detects only the rotation reference position signal based on the amplitude of each signal. Threshold values 43 and 44 are set.

  Therefore, the first comparator 43 outputs an angle signal corresponding to the rotation angle of the signal rotor 20 every time the detection signal and the rotation reference position signal are input. On the other hand, every time the rotation reference position signal is input, the second comparator 44 outputs a missing tooth signal indicating the position of the missing tooth portion 23, that is, the rotation reference position of the signal rotor 20.

  The CPU 42 has a function of acquiring the rotation reference position of the signal rotor 20, that is, the position of the missing tooth portion 23 by inputting the missing tooth signal from the waveform processing portion 41. Moreover, CPU42 acquires which angle signal shows the position of the missing tooth part 23 based on a missing tooth signal by inputting an angle signal. Thereby, the CPU 42 can acquire the rotation angle of the signal rotor 20.

  The ECU 40 is mainly composed of a microcomputer including a CPU 42, and is configured to execute various engine control programs stored in a built-in ROM. The ECU 40 inputs signals from sensors such as a throttle opening sensor, an intake pipe pressure sensor, and a coolant temperature sensor (not shown) installed in the engine 10, and the fuel injection amount of the fuel injection valve 16 according to the engine operating state. The ignition timing of the spark plug 17, the throttle opening (intake air amount) and the like are controlled. The above is the overall configuration of the rotation detection device according to the present embodiment.

  Next, the operation of the rotation detection device will be described. First, as shown in FIG. 3, when the signal rotor 20 rotates, the rotation detection sensor 30 acquires a waveform signal based on a change in the gap between the rotation detection sensor 30 and the outer peripheral portion 21 of the signal rotor 20.

  In addition, in FIG. 3, the outer peripheral part 21 of the disk-shaped signal rotor 20 is drawn linearly. In addition, the protrusion 22 on the upstream side of the toothless portion 23 in the rotation direction of the signal rotor 20 is first, and second and third in order. On the other hand, the protrusion 22 on the downstream side of the tooth missing portion 23 is the 34th, and the 33rd, 32nd, and 31st in this order.

  Then, the rotation detection sensor 30 compares the amplitude of the waveform signal with the binarization threshold. When the amplitude of the waveform signal is larger than the binarization threshold, for example, Lo, and when the amplitude of the waveform signal is smaller than the binarization threshold. Generates and outputs a Hi detection signal, for example. Here, the amplitude of the waveform signal is the same in the outer peripheral portion 21 of the signal rotor 20 where the protrusions 22 are arranged at equal intervals. Specifically, the amplitudes of the waveform signals corresponding to the second to 33rd protrusions 22 are the same.

  On the other hand, the amplitude of the waveform signal corresponding to the 34th projection 22 when switching from the 34th projection 22 to the missing tooth portion 23 is larger than the amplitude of the waveform signal corresponding to each of the second to 33rd projections 22. growing. Similarly, the amplitude of the waveform signal corresponding to the first projection 22 when switching from the missing tooth portion 23 to the first projection 22 is also based on the amplitude of the waveform signal corresponding to each of the second to 33rd projections 22. Also grows. This is because the change in the gap between the rotation detection sensor 30 and the outer peripheral portion 21 of the signal rotor 20 is not constant.

  Therefore, after time T1, the rotation detection sensor 30 detects that the amplitude of the waveform signal has become larger than normal. For example, the rotation detection sensor 30 detects the switching from the 34th protrusion 22 to the missing tooth portion 23 by comparing the amplitude of the waveform signal with a switching threshold. Thereby, the rotation detection sensor 30 detects the rotation reference position of the signal rotor 20 at the time point T2.

  Subsequently, at time T3, the rotation detection sensor 30 detects switching from the toothless portion 23 to the first protrusion 22 based on a change in the amplitude of the waveform signal. That is, it is detected that the amplitude of the waveform signal has exceeded the binarization threshold. Then, the rotation detection sensor 30 outputs a rotation reference position signal indicating the position information of the rotation reference position at the time point T3. In the present embodiment, the rotation detection sensor 30 outputs a signal having an amplitude larger than the amplitude of the detection signal as the rotation reference position signal.

  Thereafter, after time T4, the amplitude of the waveform signal does not exceed the switching threshold. Therefore, the rotation detection sensor 30 generates detection signals corresponding to the second to 33rd protrusions 22 and outputs the detection signals to the ECU 40.

  As shown in FIG. 4, the ECU 40 inputs a detection signal and a rotation reference position signal from the rotation detection sensor 30. Accordingly, the waveform processing unit 41 generates an angle signal corresponding to the detection signal and the rotation reference position signal by the first comparator 43. In addition, the waveform processing unit 41 detects only the rotation reference position signal by the second comparator 44 and generates a missing tooth signal corresponding to the rotation reference position signal. Since the amplitudes of the detection signal and the rotation reference position signal are different from each other, the waveform processing unit 41 can discriminate between the detection signal and the rotation reference position signal.

  And CPU42 acquires the rotation reference position which is the position of the missing tooth part 23 of the signal rotor 20 as a reference angle of a crank angle by inputting a missing tooth signal. Further, the CPU 42 controls the fuel injection valve 16, the spark plug 17 and the like using the information of the rotation reference position.

  As described above, in the present embodiment, the rotation reference position of the missing tooth portion 23 is indicated from the rotation detection sensor 30 by utilizing the fact that the amplitude of the waveform signal is changed by switching between the protrusion 22 and the missing tooth portion 23. The rotation reference position signal is output. Further, the ECU 40 is characterized in that a missing tooth signal is acquired from the rotation reference position signal. As a result, for example, as shown in FIG. 5, even if an instantaneous change in the rotation speed of the signal rotor 20 occurs and rotation irregularity occurs in the signal rotor 20, the rotation detection sensor 30 indicates the rotation reference position. It is possible to prevent the rotation reference position signal from being generated.

  In particular, when the internal combustion engine is started at a low temperature (starting at −10 ° C. or lower), the engine rotation speed (cranking rotation speed) decreases due to an increase in friction. Along with this, the compression torque of the compression stroke causes the fluctuation of the engine rotation speed to increase near the compression TDC (compression top dead center), and the time interval of the detection signal tends to fluctuate greatly as shown in FIG. For this reason, although it is not the missing tooth part 23, the time ratio between detection signals exceeds the threshold value near the compression TDC and may be erroneously detected as the missing tooth part 23. However, in this embodiment, since the temporal determination of detecting the rotation reference position based on the detection period of the missing tooth portion 23 is abolished, the rotation equivalent to the missing tooth time during which the missing tooth portion 23 is detected. Even if the uneven time occurs, the missing tooth signal is not generated. Therefore, it is possible to reliably detect the rotation reference position without depending on the temporal change in the detection period of the missing tooth portion 23, and to prevent erroneous detection of the rotation reference position.

  In addition, since the rotation reference position can be reliably detected, the detection accuracy of the rotation reference position of the signal rotor 20 can be improved. In recent years, there is a demand for increasing the angular resolution of the crank angle, that is, reducing the angular interval, which can be satisfied.

  As for the correspondence relationship between the description of the present embodiment and the description of the claims, the signal rotor 20 corresponds to the “rotary body” of the claims, and the missing tooth portion 23 corresponds to the “rotation” of the claims. Corresponds to “reference part”. The ECU 40 corresponds to a “signal processing unit” in the claims. Further, the engine 10 corresponds to the “internal combustion engine” in the claims.

(Second Embodiment)
In the present embodiment, parts different from the first embodiment will be described. In the present embodiment, as shown in FIG. 6, when the rotation detection sensor 30 outputs the rotation reference position signal at time T3, the rotation detection position signal outputs a rotation reference position signal having a pulse width larger than the pulse width of the detection signal. For example, the rotation detection sensor 30 outputs a rotation reference position signal having a pulse width that is four times the pulse width of the detection signal.

  In the waveform processing unit 41, the first comparator 43 detects the detection signal and the rotation reference position signal, and the second comparator 44 detects only the rotation reference position signal based on the pulse width of each signal. In addition, threshold values of the comparators 43 and 44 are set. Therefore, the waveform processing unit 41 generates an angle signal corresponding to the detection signal and the rotation reference position signal by the first comparator 43, and generates a missing tooth signal corresponding to the rotation reference position signal by the second comparator 44.

  As described above, the detection signal and the rotation reference position signal can be discriminated in the waveform processing unit 41 by making the pulse widths of the detection signal and the rotation reference position signal different. Further, since the amplitudes of the detection signal and the rotation reference position signal are the same, there is an advantage that a margin for noise can be increased.

(Third embodiment)
In the present embodiment, parts different from the first and second embodiments will be described. As described above, the missing tooth portion 23 has already been detected at the time point T2. Therefore, in the present embodiment, as shown in FIG. 7, the rotation detection sensor 30 outputs a warning signal at the time T2 ′ after the time T2 and before the time T3.

  That is, the rotation detection sensor 30 performs the rotation reference at the time T3 in a period S1 after the time T2 when the rotation reference position is detected and before the time T3 when the switching from the toothless portion 23 to the first protrusion 22 is detected. A notice signal indicating that a position signal is to be output is output to the ECU 40. As a result, it is possible to quickly and surely notify the ECU 40 that the next signal is the rotation reference position signal in advance during the period S1 in which the rotation detection sensor 30 has already detected the tooth missing portion 23. For this reason, the ECU 40 can grasp the missing tooth signal before acquiring the missing tooth signal and can be used for engine control.

  The ECU 40 may be configured to recognize the notice signal. For example, as shown in FIG. 4, the warning signal may be extracted by using the second comparator 44 in the waveform processing unit 41. In this case, the amplitude and pulse width of the notice signal may be changed with respect to the detection signal. Of course, the amplitude and pulse width of the rotation reference position signal may be changed with respect to the detection signal as in the above embodiments.

  Further, the ECU 40 may input the detection signal itself to the CPU 42 to detect the presence / absence of the warning signal in the period S1. The CPU 42 recognizes that the next signal after the notice signal is a rotation reference position signal, that is, a missing tooth signal. In this case, it is not necessary to change the amplitude and pulse width of the rotation reference position signal with respect to the detection signal. As shown in FIG. 5, even if the rotation irregularity of the signal rotor 20 occurs, the warning signal is not output from the rotation detection sensor 30 during the period in which the rotation irregularity time occurs. There is no detection.

(Fourth embodiment)
In the present embodiment, parts different from the first to third embodiments will be described. In the present embodiment, as shown in FIG. 8, the rotation detection sensor 30 generates a detection signal and a rotation reference position signal from the waveform signal, and outputs each signal. For this reason, the rotation detection sensor 30 has a terminal (not shown) that outputs a detection signal as an angle signal and a terminal (not shown) that outputs a rotation reference position signal as a missing tooth signal. Then, the rotation detection sensor 30 outputs a detection signal (angle signal) and a rotation reference position signal (missing tooth signal) to the ECU 40 from dedicated terminals.

  The ECU 40 has a terminal (not shown) corresponding to each signal, and is configured to input each signal separately. Therefore, in this embodiment, the ECU 40 may not have the waveform processing unit 41. As described above, the signal output from the rotation detection sensor 30 can be originally separated into the angle signal and the missing tooth signal.

(Other embodiments)
The configuration of the rotation detection device shown in each of the above embodiments is merely an example, and is not limited to the configuration shown above, and other configurations that can realize the present invention can be used. For example, the rotation detection device may be applied when detecting the rotation angle of the signal rotor fixed to the camshaft of the engine 10 instead of the crank angle. Further, the configurations of the rotation detection sensor 30 and the ECU 40 are merely examples, and may be configured by other circuit elements.

  In the first embodiment, the amplitude of the rotation reference position signal is larger than the amplitude of the detection signal, but this is an example for identifying each signal. Accordingly, the amplitude of the rotation reference position signal may be made smaller than the amplitude of the detection signal. As described above, the rotation detection sensor 30 may be configured to change the amplitude of the rotation reference position signal with respect to the amplitude of the detection signal and output it. ECU40 should just be the structure which can identify each signal.

  Similarly, in the second embodiment, the pulse width of the rotation reference position signal is made larger than the pulse width of the detection signal, but this is an example for identifying each signal. Therefore, the rotation detection sensor 30 may be configured to change the pulse width of the rotation reference position signal with respect to the pulse width of the detection signal.

  Furthermore, in the fourth embodiment, the warning signal shown in the third embodiment may be output. In this case, for example, a warning signal can be output from a terminal that outputs a detection signal (angle signal).

  The application of the rotation detection device is not limited to the internal combustion engine. Also for the signal rotor 20, the rotation reference portion indicating the rotation reference position may be provided with another reference instead of the missing tooth portion 23. That is, it is only necessary that the outer peripheral portion 21 of the signal rotor 20 and the rotation reference portion indicating the rotation reference position be provided on a part of the outer peripheral portion 21.

10 Engine (Internal combustion engine)
11 Crankshaft 20 Signal rotor (Rotating body)
21 Peripheral part 22 Projection 23 Missing tooth part
30 Rotation detection sensor 40 ECU (signal processing unit)

Claims (3)

The rotation reference position is detected with respect to the rotation of the rotating body (20) provided with an outer peripheral portion (21) and a rotation reference portion (23) indicating a rotation reference position at a part of the outer peripheral portion (21). A rotation detection device configured to:
The rotating body (20) is disposed so as to face the outer peripheral portion (21), and outputs a detection signal corresponding to the position of the outer peripheral portion (21) as the rotating body (20) rotates. Based on the gap with the rotating body (20), the rotation reference position is detected by detecting the switching from the outer peripheral portion (21) to the rotation reference portion (23), and the rotation reference portion (23). A rotation reference position signal indicating position information of the rotation reference position at a detection timing at which a change from the rotation reference part (23) to the outer periphery (21) is detected by detecting a change from the outer periphery (21) to the outer periphery (21) A rotation detection sensor (30) for outputting
A signal processing unit (40) for inputting the detection signal and the rotation reference position signal from the rotation detection sensor (30) and acquiring the rotation reference position based on the rotation reference position signal;
With
The rotation detection sensor (30) detects the rotation reference position signal in a period after detecting the rotation reference position and before detecting a switch from the rotation reference part (23) to the outer peripheral part (21). A rotation detection device that outputs a warning signal indicating output to the signal processing unit (40). The rotation detection device according to claim 1 , wherein the rotation detection sensor (30) outputs the rotation reference position signal by changing an amplitude of the detection signal with respect to an amplitude of the detection signal. The rotation detection device according to claim 1 , wherein the rotation detection sensor (30) outputs a pulse width of the rotation reference position signal changed with respect to a pulse width of the detection signal.

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