JP6003809B2 - 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. Further, the rotating body is provided with a missing tooth portion indicating the rotation reference position of the rotating body. The missing tooth portion is a portion lacking any of the plurality of protrusions.

  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, the determination device erroneously detects the missing tooth portion, and there is a problem that sufficient detection accuracy of the rotation reference position of the rotating body cannot be obtained.

  In view of the above points, an object of the present invention is to provide a rotation detection device that can improve the detection accuracy of the rotation reference position of a rotating body.

  In order to achieve the above object, in the invention described in claim 1, the outer peripheral portion (11) and the rotation reference portion (13, 14) indicating the rotation reference position are provided in a part of the outer peripheral portion (11). A rotation detection device configured to detect the rotation reference position with respect to the rotation of the rotating body (10), is characterized by the following points.

  That is, the first magnetoresistive element (23a) and the second magnetoresistive element (23b) are connected in series, and the first magnetoresistive element (23a) and the second magnetoresistive element with the rotation of the rotating body (10). A first magnetoresistive element pair (23) for detecting a change in resistance value when the element (23b) is affected by a magnetic field is provided.

  Also, an amplification amplifier (26) that converts a change in resistance value of the first magnetoresistive element pair (23) into a waveform signal, and a peak that receives the waveform signal and detects the peak value or bottom value of the amplitude of the waveform signal. A bottom detection unit (27) and a determination unit (30) for inputting a peak value or a bottom value detected by the peak / bottom detection unit (27) and acquiring a rotation reference position based on the peak value or the bottom value; It is equipped with.

And a 1st magnetoresistive element pair (23) respond | corresponds to the 1st waveform corresponding to an outer peripheral part (11) as a waveform signal, and the switching from an outer peripheral part (11) to a rotation reference | standard part (13, 14). In addition, a signal including a second waveform having an amplitude larger than that of the first waveform is output. Furthermore, the peak / bottom detector (27) is characterized in that it detects a peak value or a bottom value of the amplitude of the second waveform which is larger than the amplitude of the first waveform.
Further, the third magnetoresistive element (24a) and the fourth magnetoresistive element (24b) are connected in series, and the third magnetoresistive element (24a) and the fourth magnetoresistive element with the rotation of the rotating body (10). A second magnetoresistive element pair (24) that outputs a first detection signal based on a change in resistance value when the element (24b) is affected by a magnetic field is provided.
The fifth magnetoresistive element (25a) and the sixth magnetoresistive element (25b) are connected in series, and the fifth magnetoresistive element (25a) and the sixth magnetoresistive element ( 25b) includes a third magnetoresistive element pair (25) that outputs a second detection signal based on a change in resistance value when affected by a magnetic field.
The first detection signal and the second detection signal are input, an angle signal corresponding to the rotation angle of the rotating body (10) is generated from the first detection signal and the second detection signal, and the angle signal and the binarization threshold value are generated. A binarization unit (28, 29, 33, 34, 36) for binarizing the angle signal by comparison is provided.
Then, the determination unit (30) inputs the angle signal from the binarization unit (28, 29, 33, 34, 36) and outputs the angle signal to the outside, while the rise of the binarized angle signal A rotation reference position signal indicating position information of the rotation reference position is output to the outside based on the edge or the falling edge.

  According to this, based on the difference in amplitude between the amplitude of the first waveform and the amplitude of the second waveform included in the waveform signal, the peak or bottom value of the amplitude of the waveform signal is determined by the peak / bottom detector (27). Detected. Therefore, even if an instantaneous change in the rotation speed of the rotating body (10) occurs, the rotation reference position can be reliably set without depending on the temporal change in the detection period of the rotation reference unit (13, 14). Can be detected. Therefore, erroneous detection of the rotation reference position of the rotator (10) can be prevented, and the detection accuracy of the rotation reference position of the rotator (10) 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.

It is the figure which showed the arrangement | positioning relationship between the rotation detection apparatus which concerns on 1st Embodiment of this invention, and a signal rotor. It is the figure which showed the circuit structure of the rotation detection apparatus. It is a figure for demonstrating the 1st waveform and 2nd waveform which are contained in a waveform signal. It is a top view of the sensor chip which showed arrangement | positioning of each magnetoresistive element pair. It is a timing chart for demonstrating the action | operation of a rotation detection apparatus. It is a figure for demonstrating the waveform signal corresponding to the signal rotor which concerns on 2nd Embodiment. It is a figure for demonstrating the angle signal corresponding to the signal rotor which concerns on 2nd Embodiment. It is the figure which showed the circuit structure of the rotation detection apparatus which concerns on 3rd Embodiment.

  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, a rotation detection device 20 is disposed so as to face the outer peripheral portion 11 of a disk-shaped signal rotor 10 fixed to a crankshaft of an engine that is an internal combustion engine. In addition, in FIG. 1, the outer peripheral part 11 of the disk-shaped signal rotor 10 is drawn extending linearly.

  A plurality of protrusions 12 are provided at equal intervals on the outer peripheral portion 11 of the signal rotor 10, and a missing tooth portion 13 in which one or more protrusions 12 are missing at a specific crank angle is provided. This missing tooth portion 13 corresponds to the rotation reference position of the signal rotor 10, that is, the reference angle of the crank angle. In the present embodiment, for example, 34 protrusions 12 are provided on the outer peripheral portion 11 of the signal rotor 10. Further, the missing tooth portion 13 is a portion of the outer peripheral portion 11 of the signal rotor 10 where, for example, two protrusions 12 are missing.

  The rotation detecting device 20 includes a bias magnet 21 and a sensor chip 22 disposed at a predetermined position with respect to the bias magnet 21. The bias magnet 21 serves to increase the magnetic field detection sensitivity of the rotation detection device 20 by a certain amount. The sensor chip 22 is configured to output a pulse-shaped detection signal corresponding to the position of the outer peripheral portion, that is, the crank angle as the signal rotor 10 rotates.

  Specifically, as shown in FIG. 2, the sensor chip 22 includes first to third magnetoresistive element pairs 23 to 25, a voltage follower circuit 26, a peak / bottom detection determination / holding circuit 27, an operational amplifier 28, and a comparator. 29, an angle signal determination circuit 30, a first output transistor 31, and a second output transistor 32.

  The first to third magnetoresistive element pairs 23 to 25 are sensing units configured to output waveform signals according to the rotation of the signal rotor 10. The first magnetoresistive element pair 23 is a sensing unit for facilitating detection of the missing tooth portion 13 of the signal rotor 10. The second magnetoresistive element pair 24 and the third magnetoresistive element pair 25 are sensing units for detecting unevenness of the outer peripheral portion 11 of the signal rotor 10.

  The first magnetoresistive element pair 23 is configured by connecting a first magnetoresistive element 23a (MR1) and a second magnetoresistive element 23b (MR2) in series between a power supply (VCC) and a ground (GND). . The first magnetoresistive element pair 23 detects a change in resistance value when the first magnetoresistive element 23 a and the second magnetoresistive element 23 b are affected by the magnetic field as the signal rotor 10 rotates. The first magnetoresistive element pair 23 outputs the voltage at the midpoint 23c of the first magnetoresistive element 23a and the second magnetoresistive element 23b as a waveform signal based on the change in the resistance value. As shown in FIG. 3, the first magnetoresistive element pair 23 is switched to a first waveform corresponding to the outer peripheral portion 11 on which the protrusion 12 is formed and a switching from the outer peripheral portion 11 to the missing tooth portion 13 as a waveform signal. A signal including a second waveform corresponding to and having a larger amplitude than the first waveform is output.

  The first waveform is a waveform that appears in accordance with the unevenness of the signal rotor 10 in which the toothless portion 13 is not provided in the signal rotor 10, as shown by the dashed waveform in FIG. 3. On the other hand, the second waveform is a waveform having an amplitude larger than the amplitude of the first waveform corresponding to the protrusions 12 positioned before and after the missing tooth portion 13, as shown by the solid line waveform in FIG. That is, the second waveform corresponds to both switching from the protrusion 12 to the missing tooth portion 13 and switching from the missing tooth portion 13 to the protrusion 12. The amplitude of the second waveform corresponding to the switching from the protrusion 12 to the missing tooth portion 13 corresponds to the bottom value of the amplitude of the waveform signal. Further, the amplitude of the second waveform corresponding to the switching from the toothless portion 13 to the protrusion 12 corresponds to the peak value of the amplitude of the waveform signal.

  Since the signal rotor 10 is provided with the toothless portion 13, as shown by the solid line waveform in FIG. 3, the waveform signal is generated in the first waveform corresponding to the unevenness due to the protrusion 12 and the toothless portion 13. The waveform is a combination of the corresponding second waveform. The “toothless rotor” in FIG. 3 indicates the signal rotor 10 with the missing tooth portion 13, and the “normal tooth rotor” indicates the signal rotor without the missing tooth portion 13.

  The second magnetoresistive element pair 24 is configured by connecting a third magnetoresistive element 24a (MR3) and a fourth magnetoresistive element 24b (MR4) in series between a power source and the ground. The second magnetoresistive element pair 24 has a third magnetic resistance based on a change in resistance value when the third magnetoresistive element 24a and the fourth magnetoresistive element 24b are affected by the magnetic field as the signal rotor 10 rotates. The voltage at the midpoint 24c of the resistor element 24a and the fourth magnetoresistive element 24b is output as the first detection signal.

  The third magnetoresistive element pair 25 is configured by connecting a fifth magnetoresistive element 25a (MR5) and a sixth magnetoresistive element 25b (MR6) in series between a power source and the ground. The third magnetoresistive element pair 25 has a fifth magnetic resistance based on a change in resistance value when the fifth magnetoresistive element 25a and the sixth magnetoresistive element 25b are affected by the magnetic field as the signal rotor 10 rotates. The voltage at the midpoint 25c of the resistance element 25a and the sixth magnetoresistance element 25b is output as the second detection signal.

  As described above, each of the magnetoresistive element pairs 23 to 25 constitutes a half bridge circuit. Further, as shown in FIG. 4, the first magnetoresistive element pair 23 is disposed in the center of the sensor chip 22 on the signal rotor 10 side. Further, the second magnetoresistive element pair 24 and the third magnetoresistive element pair 25 are respectively arranged so as to sandwich the first magnetoresistive element pair 23 at the end of the sensor chip 22 on the signal rotor 10 side.

  The first magnetoresistive element pair 23 is arranged so that the first magnetoresistive element 23a and the second magnetoresistive element 23b are at an angle of 45 ° and −45 ° with respect to the magnetic center of the bias magnetic field, that is, with respect to each other. It is arranged in a letter shape. Similarly, the third magnetoresistive element 24a and the fourth magnetoresistive element 24b of the second magnetoresistive element pair 24 and the fifth magnetoresistive element 25a and the sixth magnetoresistive element 25b of the third magnetoresistive element pair 25 are also shaped like a letter C. Are arranged respectively.

  The voltage follower circuit 26 shown in FIG. 2 is an amplifier circuit that receives a waveform signal from the first magnetoresistive element pair 23, converts the impedance, and outputs it to the peak / bottom detection determination / holding circuit 27. That is, the voltage follower circuit 26 converts the change in the resistance value of the first magnetoresistive element pair 23 into a waveform signal amplified by a predetermined amplification factor.

  The peak / bottom detection determination / holding circuit 27 is a circuit that receives the waveform signal from the voltage follower circuit 26, detects the peak value and the bottom value of the amplitude of the waveform signal, and holds the detected peak value and bottom value. is there. As described above, since the waveform signal is composed of the first waveform and the second waveform, the peak / bottom detection determination / holding circuit 27 has the peak value or bottom of the amplitude of the second waveform larger than the amplitude of the first waveform. Detect value. The peak / bottom detection determination / holding circuit 27 holds the peak value and the bottom value until reset.

  The operational amplifier 28 receives the first detection signal from the second magnetoresistive element pair 24 and also receives the second detection signal from the third magnetoresistive element pair 25, and the signal difference between the first detection signal and the second detection signal. That is, it is a differential amplifier circuit that amplifies the voltage difference. That is, the operational amplifier 28 generates a wave-shaped angle signal corresponding to the rotation angle of the signal rotor 10 and outputs it to the comparator 29.

  The comparator 29 is a circuit that generates a binarized angle signal by comparing the amplitude of the angle signal with a binarization threshold value. For example, the comparator 29 outputs the Lo signal as a binarized angle signal when the amplitude of the angle signal is larger than the binarization threshold, and Hi when the amplitude of the angle signal is smaller than the binarization threshold. Is output as a binarized angle signal. Hereinafter, “binarized angle signal” is also referred to as “binarized signal”.

  The binarization threshold value connects the first resistor 33 and the second resistor 34 connected in series between the power source and the ground, and the midpoint 35 of the first resistor 33 and the second resistor 34 and the output terminal of the comparator 29. It is set by the resistance ratio of the third resistor 36. That is, the voltage value at the midpoint 35 of the first resistor 33 and the second resistor 34 corresponds to the binarization threshold value.

  The angle signal determination circuit 30 is a circuit unit having a binarized signal output function and a rotation reference position output function. The binarized signal output function is a function in which the angle signal determination circuit 30 inputs a binarized signal from the comparator 29 and outputs a detection signal corresponding to the binarized signal to the outside. The angle signal determination circuit 30 controls the first output transistor 31 in order to output the detection signal to the outside. For example, the angle signal determination circuit 30 outputs a Hi signal to the first output transistor 31 when the binarized signal is a Hi signal, and outputs a Lo signal to the first output transistor 31 when the binarized signal is a Lo signal. Output.

  Further, the rotation reference position output function is such that the angle signal determination circuit 30 inputs the peak value or bottom value of the amplitude of the waveform signal from the peak / bottom detection determination / holding circuit 27 and the rotation reference position based on the peak value or bottom value. To get. The angle signal determination circuit 30 has a function of outputting a rotation reference position signal indicating the position information of the rotation reference position to the outside based on the rising edge or the falling edge of the binarized signal. The angle signal determination circuit 30 controls the second output transistor 32 in order to output the rotation reference position signal to the outside. For example, the angle signal determination circuit 30 outputs a Hi signal to the second output transistor 32 when outputting the rotation reference position signal to the outside.

  Here, the Hi signal output from the angle signal determination circuit 30 to the second output transistor 32 functions as a reset signal for resetting the peak value or the bottom value held in the peak / bottom detection determination / holding circuit 27.

  The first output transistor 31 is switching means for outputting an output signal to the outside by controlling the gate by the angle signal determination circuit 30. The first output transistor 31 is connected between the fifth resistor 38 and the ground with respect to the series connection of the fourth resistor 37 and the fifth resistor 38 connected to the power source.

  The first output transistor 31 is turned on when a Hi signal is input from the angle signal determination circuit 30 to the gate. As a result, when the first output transistor 31 is ON, the voltage (for example, 2.5 V) at the midpoint 39 of the fourth resistor 37 and the fifth resistor 38 is output to the outside as the first output transistor. When 31 is OFF, the voltage of the power supply (for example, 5V) is output to the outside as an output signal.

  The second output transistor 32 is a switching means for outputting a rotation reference position signal indicating position information of the rotation reference position by controlling the gate by the angle signal determination circuit 30. The second output transistor 32 is connected between the midpoint 39 and the ground.

  The second output transistor 32 is turned on when a Hi signal is input from the angle signal determination circuit 30 to the gate. Thereby, when the second output transistor 32 is ON, the midpoint 39 is connected to the ground, and therefore the ground voltage (for example, 0 V) is output to the outside as the rotation reference position signal. The above is the overall configuration of the rotation detection device 20 according to the present embodiment.

  Next, the operation of the rotation detection device 20 will be described. First, as shown in FIG. 5, when the signal rotor 10 rotates, the rotation detection device 20 acquires a waveform signal and an angle signal based on a change in the gap between the rotation detection device 20 and the outer peripheral portion 11 of the signal rotor 10. To do.

  In addition, in FIG. 5, the outer peripheral part 11 of the disk-shaped signal rotor 10 is drawn linearly. Further, the protrusion 12 on the upstream side of the toothless portion 13 in the rotation direction of the signal rotor 10 is the first, and the second and third are in order. On the other hand, the protrusion 12 on the downstream side of the toothless portion 13 is the 34th, and the 33rd, 32nd, and 31st in that order.

  The peak / bottom detection determination / holding circuit 27 monitors the amplitude of the waveform signal. When the signal rotor 10 rotates in the direction shown in FIG. 5, the bottom value is first held in the peak / bottom detection determination / holding circuit 27, and thereafter the peak value is held. These peak values or bottom values are output from the peak / bottom detection determination / holding circuit 27 to the angle signal determination circuit 30.

  In the comparator 29, the amplitude of the angle signal is compared with the binarization threshold value, and a binarized signal (binarized angle signal) is generated. If the amplitude of the angle signal is greater than the binarization threshold, for example, Lo, and if the amplitude of the angle signal is less than the binarization threshold, for example, a binary signal of Hi is generated by the comparator 29 and output to the angle signal determination circuit 30. Is done.

  The amplitude of the angle signal corresponding to the 34th projection 12 when switching from the 34th projection 12 to the missing tooth portion 13 is larger than the amplitude of the angle signal corresponding to each of the second to 33rd projections 12. growing. Similarly, the amplitude of the angle signal corresponding to the first protrusion 12 when switching from the toothless portion 13 to the first protrusion 12 is also based on the amplitude of the angle signal corresponding to each of the second to 33rd protrusions 12. Also grows. This is because the change in the gap between the rotation detection device 20 and the outer peripheral portion 11 of the signal rotor 10 is not constant.

  As described above, the peak value or bottom value of the waveform signal and the binarized signal are input to the angle signal determination circuit 30 as needed. Accordingly, the angle signal determination circuit 30 performs processing for outputting the binarized signal and the rotation reference position signal to the outside as output signals.

  Specifically, at the time point T <b> 1, the angle signal falls below the binarization threshold value, so the Hi binarization signal is input to the angle signal determination circuit 30. Accordingly, the first output transistor 31 is turned off by the angle signal determination circuit 30. At this time T1, the peak value and the bottom value held in the peak / bottom detection determination / holding circuit 27 are reset, and the rotation reference position is not detected. Therefore, the second output transistor 32 is turned off by the angle signal determination circuit 30. As a result, in the circuit shown in FIG. 2, since the power supply voltage (5 V) is applied to the midpoint 39, the power supply voltage is output to the outside as an output signal.

  Subsequently, at time T <b> 2 in FIG. 5, since the angle signal exceeds the binarization threshold, the Lo binarization signal is input to the angle signal determination circuit 30. Accordingly, the first output transistor 31 is turned on by the angle signal determination circuit 30. Further, since the rotation reference position is not acquired in the angle signal determination circuit 30, the second output transistor 32 is also turned off. As a result, in the circuit shown in FIG. 2, a voltage (2.5 V) corresponding to the resistance ratio of the fourth resistor 37 and the fifth resistor 38 is applied to the middle point 39, so that the voltage is output to the outside as an output signal. Is output.

  Then, after the time T2, the angle signal determination circuit 30 detects the switching from the protrusion 12 to the missing tooth portion 13. The peak / bottom detection determination / holding circuit 27 detects and holds the bottom value of the amplitude of the waveform signal and outputs it to the angle signal determination circuit 30. As a result, at the time T3, the angle signal determination circuit 30 acquires the rotation reference position.

  At time T4, the outer peripheral portion 11 of the signal rotor 10 is switched from the toothless portion 13 to the protrusion 12 in the same manner as at time T2. Thereby, since the angle signal exceeds the binarization threshold value, the binarization signal falls from Hi to Lo. Then, the first output transistor 31 and the second output transistor 32 are turned on by the angle signal determination circuit 30 based on the falling edge of the binarized signal. 2 is connected to the ground in the circuit shown in FIG. 2, the ground voltage (0 V) is output to the outside as a rotation reference position signal indicating the position information of the rotation reference position. In the present embodiment, a signal having an amplitude larger than the amplitude of the detection signal corresponding to the binarized signal is output as the rotation reference position signal.

  Further, when the second output transistor 32 is turned on, a reset signal is input from the angle signal determination circuit 30 to the peak / bottom detection determination / holding circuit 27. As a result, the peak value and the bottom value held in the peak / bottom detection determination / holding circuit 27 are reset. As described above, since the second output transistor 32 is turned on after the time T4, the peak / bottom detection determination / holding circuit 27 does not hold the peak value but uses only the bottom value. When the rotation direction of the signal rotor 10 is reversed, only the peak value is detected and held and used.

  Thereafter, at the time T5, the angle signal falls below the binarization threshold value, so that the first output transistor 31 and the second output transistor 32 are turned off. After time T5, a detection signal corresponding to the binarized signal is output.

  Then, the engine ECU inputs the detection signal and the rotation reference position signal from the rotation detection device 20, so that the rotation angle of the signal rotor 10 and the rotation reference position, which is the position of the toothless portion 13 of the signal rotor 10, are changed according to the crank angle. Obtained as a reference angle. Further, the engine ECU controls the fuel injection valve, the spark plug, and the like using the information on the rotation reference position.

  As described above, in the present embodiment, the waveform signal is generated by the first magnetoresistive element pair 23 different from the second magnetoresistive element 23 b and the third magnetoresistive element pair 25 for detecting the rotation angle of the signal rotor 10. It is characterized by detection. Thus, based on the difference in amplitude between the amplitude of the first waveform and the amplitude of the second waveform included in the waveform signal, the peak / bottom detection waveform is determined by the peak / bottom detection determination / holding circuit 27. Can be detected. For this reason, even if an instantaneous change or the like of the rotation speed of the signal rotor 10 occurs and rotation unevenness occurs in the signal rotor 10, a rotation reference position signal indicating the rotation reference position is not generated in the angle signal determination circuit 30. Can be.

  Further, the rotation reference position can be set without depending on the accuracy of the shape of the outer peripheral portion 11 and the toothless portion 13 of the signal rotor 10, that is, without depending on the accuracy of the gap between the first magnetoresistive element pair 23 and the signal rotor 10. Can be detected. Therefore, erroneous detection of the rotation reference position of the signal rotor 10 can be prevented, and detection accuracy of the rotation reference position of the signal rotor 10 can be improved.

  In addition, regarding the correspondence between the description of the present embodiment and the description of the claims, the signal rotor 10 corresponds to the “rotary body” in the claims, and the missing tooth portion 13 corresponds to the “rotation” in the claims. Corresponds to “reference part”. The voltage follower circuit 26 corresponds to the “amplification amplifier” in the claims, and the peak / bottom detection determination / holding circuit 27 corresponds to the “peak / bottom detection unit” in the claims. Further, the operational amplifier 28, the comparator 29, and the resistors 33, 34, and 36 correspond to the “binarization unit” in the claims, and the angle signal determination circuit 30 corresponds to the “determination unit” in the claims.

(Second Embodiment)
In the present embodiment, parts different from the first embodiment will be described. In the first embodiment, the toothless portion 13 of the signal rotor 10 indicates the rotation reference position. However, in this embodiment, the long mountain portion provided in a part of the outer peripheral portion 11 of the signal rotor 10 sets the rotation reference position. It is configured as shown.

  Specifically, as shown in FIG. 6, a waveform signal corresponding to the long peak portion 14 of the signal rotor 10 is detected by the first magnetoresistive element pair 23. For example, the peak value of the waveform signal appears when the concave portion of the signal rotor 10 is switched to the long mountain portion 14. Further, the bottom value of the waveform signal appears when switching from the long peak portion 14 of the signal rotor 10 to the concave portion. One of the peak value and the bottom value appears first according to the rotation direction of the signal rotor 10. Based on the peak value or the bottom value of the amplitude of the waveform signal, the angle signal determination circuit 30 outputs a rotation reference position signal to the outside.

  On the other hand, as shown in FIG. 7, the amplitude of the angle signal obtained by the operational amplifier 28 does not change so much by switching between the long peak portion 14 and the concave portion. This angle signal is binarized by the comparator 29 and output to the outside by the angle signal determination circuit 30. As described above, the binarized angle signal and the rotation reference position signal are obtained for the one provided with the long mountain portion 14 as the means for indicating the rotation reference position of the signal rotor 10 as in the first embodiment. Can do.

  6 and 7 show the signal rotor 10 with the long mountain portion 14 provided, and the “normal tooth rotor” shows the signal rotor without the missing tooth portion 13. As for the correspondence between the description of the present embodiment and the description of the claims, the Nagayama portion 14 corresponds to the “rotation reference portion” of the claims.

(Third embodiment)
In the present embodiment, parts different from the first and second embodiments will be described. As shown in FIG. 8, the rotation detection device includes only the first magnetoresistive element pair 23 as a sensing unit that detects the rotation of the signal rotor 10. That is, in the present embodiment, the second magnetoresistive element pair 24 and the third magnetoresistive element pair 25 are not provided in the rotation detection device. Therefore, the rotation detection device detects the rotation angle and rotation reference position of the signal rotor 10 based on the output of the first magnetoresistive element pair 23.

  For this reason, the voltage follower circuit 26 is connected not only to the peak / bottom detection determination / holding circuit 27 but also to the comparator 29. As a result, the waveform signal input from the voltage follower circuit 26 to the comparator 29 becomes an angle signal. As shown in FIG. 3 described above, the waveform signal includes a first waveform corresponding to the outer peripheral portion 11 where the protrusion 12 is formed in the signal rotor 10. A waveform signal including the first waveform is input to the comparator 29 as an angle signal. Therefore, the comparator 29 generates a binarized angle signal by comparing the amplitude of the angle signal input from the voltage follower circuit 26 with the binarization threshold value. The resistance values of the resistors 33, 34, and 36 are set according to the angle signal.

  As described above, the rotation detection device can have a minimum configuration including one first magnetoresistive element pair 23. Even with such a configuration, both the rotation angle and the rotation reference position of the signal rotor 10 can be acquired from the signal output from the first magnetoresistive element pair 23.

(Other embodiments)
The configuration of the rotation detection device 20 shown in each of the above embodiments is an example, and is not limited to the configuration shown above, and may be another configuration that can realize the present invention. For example, the configuration for outputting the detection signal and the rotation reference position signal to the outside is not limited to the first output transistor 31 or the like. For example, the rotation reference position signal having a pulse width larger than the pulse width of the detection signal may be output. Conversely, the rotation detection device 20 may output a rotation reference position signal having a pulse width smaller than the pulse width of the detection signal.

  On the other hand, in the first embodiment, the amplitude of the rotation reference position signal is made 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. Thus, the rotation detection device 20 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.

  Further, since the rotation reference position information has already been obtained before the rotation reference position signal is output from the angle signal determination circuit 30 to the outside, for example, the rotation reference position signal is output between time T3 and time T4 in FIG. A configuration may be used in which a warning signal indicating that this is to be performed is output to the outside. As a result, the engine ECU can grasp the rotation reference position signal before acquiring the rotation reference position signal, and can use this advance information for engine control.

  Further, the rotation detection device 20 may have 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. Thereby, the rotation detection apparatus 20 can output a detection signal (binarized angle signal) and a rotation reference position signal from the dedicated terminals to the engine ECU.

  The application of the rotation detection device 20 is not limited to an internal combustion engine. Also for the signal rotor 10, the rotation reference portion indicating the rotation reference position may be provided with another means instead of the missing tooth portion 13 and the long mountain portion 14. That is, it is only necessary that the outer peripheral portion 11 of the signal rotor 10 and a rotation reference portion indicating the rotation reference position be provided on a part of the outer peripheral portion 11.

10 Signal rotor (rotating body)
11 outer peripheral part 13 missing tooth part (rotation reference part)
23 1st magnetoresistive element pair 23a 1st magnetoresistive element 23b 2nd magnetoresistive element 26 Voltage follower circuit (amplification amplifier)
27 Peak / Bottom Detection Judgment / Holding Circuit (Peak / Bottom Detection Unit)
30 Angle signal determination circuit (determination unit)

Claims (1)

The rotation reference position is detected with respect to the rotation of the rotating body (10) provided with an outer peripheral part (11) and a rotation reference part (13, 14) indicating a rotation reference position at a part of the outer peripheral part (11). A rotation detector configured to:
A first magnetoresistive element (23a) and a second magnetoresistive element (23b) are connected in series, and the first magnetoresistive element (23a) and the second magnetic element are rotated along with the rotation of the rotating body (10). A first magnetoresistive element pair (23) for detecting a change in resistance value when the resistance element (23b) is affected by a magnetic field;
An amplification amplifier (26) for converting a change in resistance value of the first magnetoresistive element pair (23) into a waveform signal;
A peak / bottom detector (27) for inputting the waveform signal and detecting a peak value or a bottom value of an amplitude of the waveform signal;
A determination unit (30) for inputting the peak value or the bottom value detected by the peak / bottom detection unit (27) and acquiring the rotation reference position based on the peak value or the bottom value;
With
The first magnetoresistive element pair (23) has, as the waveform signal, a first waveform corresponding to the outer peripheral portion (11), and switching from the outer peripheral portion (11) to the rotation reference portion (13, 14). And a signal including a second waveform having a larger amplitude than that of the first waveform,
The peak / bottom detector (27) detects a peak value or a bottom value of the amplitude of the second waveform that is larger than the amplitude of the first waveform ,
Further, the third magnetoresistive element (24a) and the fourth magnetoresistive element (24b) are connected in series. The third magnetoresistive element (24a) and the A second magnetoresistive element pair (24) that outputs a first detection signal based on a change in resistance value when the four magnetoresistive elements (24b) are affected by a magnetic field;
A fifth magnetoresistive element (25a) and a sixth magnetoresistive element (25b) are connected in series, and the fifth magnetoresistive element (25a) and the sixth magnetic resistor are coupled with the rotation of the rotating body (10). A third magnetoresistive element pair (25) that outputs a second detection signal based on a change in resistance value when the resistance element (25b) is affected by a magnetic field;
The first detection signal and the second detection signal are input, an angle signal corresponding to a rotation angle of the rotating body (10) is generated from the first detection signal and the second detection signal, and the angle signal and A binarization unit (28, 29, 33, 34, 36) for binarizing the angle signal by comparing with a binarization threshold;
With
The determination unit (30) inputs the angle signal from the binarization unit (28, 29, 33, 34, 36) and outputs the angle signal to the outside, while the binarized angle signal A rotation detection device that outputs a rotation reference position signal indicating position information of the rotation reference position based on a rising edge or a falling edge of the rotation detection device.

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