JP2009103617A - Rotation detection sensor - Google Patents

Abstract

Provided is a rotation detection sensor capable of detecting and outputting a sensor abnormality by the sensor itself without depending on the rotation speed of a rotating body.
SOLUTION: Two rotation detection units 1 that respectively output pulsed rotation detection signals S1 and S2 according to the rotation of a rotating body 30, and two-phase rotation detection signals S1 that are respectively output from the rotation detection unit 1. Based on S2, when the rotation direction detection unit 4 that detects the rotation direction of the rotation body 30, the abnormality detection unit 6 that detects an abnormality of the rotation detection unit 1, and the rotation detection unit 1 are normal, the rotation body 30 When the rotation detection unit 1 is abnormal, one of the first output signal and the second output signal is generated and output. Includes a signal processing unit 8 having a different pulse shape and generating and outputting a third output signal indicating the abnormal state and the rotation speed of the rotating body 30.
[Selection] Figure 1

Description

  The present invention relates to a rotation detection sensor that detects a rotation direction and a rotation speed of a rotating body and outputs a waveform that varies depending on the rotation direction at a timing corresponding to the rotation speed.

  In-vehicle systems such as anti-lock brake systems (ABS) and stable vehicle control systems for vehicles use rotation detection sensors that detect the rotational speed (number of rotations) and rotation direction of wheels as rotating bodies. Has been.

  Japanese Patent Application Laid-Open Publication No. 2003-259542, which is cited below, discloses a technique of a detection signal processing device of a rotation sensor that outputs a signal that can indicate the rotation direction (rotation in the forward direction or rotation in the reverse direction) together with the rotation speed of the rotating body. It is disclosed. This output signal indicates the rotation speed of the rotator according to the pulse period, and indicates the rotation direction of the rotator by the pulse waveform (pulse width, amplitude, shape, etc.).

  The detection signal processing apparatus is configured to be able to output the output signal including information other than the rotation speed and the rotation direction. Then, such other information is added to the output signal after the rotation speed of the rotating body becomes equal to or higher than a predetermined rotation speed. At this time, the output signal continues to indicate the rotation speed of the rotating body by the pulse period, but does not indicate the rotation direction of the rotating body by the pulse waveform. The waveform of the pulse is used not to indicate the direction of rotation but to indicate additional information related to rotation. When the rotating body starts to rotate in either the forward rotation direction or the reverse rotation direction and the rotation speed is equal to or higher than the predetermined rotation speed, the rotation direction does not change suddenly. That is, even if a signal indicating the rotation direction is not output, it can be assumed that the rotation direction recognized by the already output signal is maintained, and therefore additional information related to rotation is indicated using the pulse waveform. Here, the additional information includes a detection result of an abnormal state such as a failure of the rotation sensor. The detection signal processing apparatus of Patent Document 1 includes an error code generation circuit that generates an error code indicating an abnormal state of a rotation sensor as additional information related to rotation. The abnormal state of the rotation sensor can be transmitted to a subsequent control device such as an ECU (electronic control unit) via an output signal.

  Japanese Patent Application Laid-Open Publication No. 2004-259542, which is cited below, describes a method for determining an abnormal state of a rotation sensor by comparing output signals of four rotation sensors provided on four wheels on the front, rear, left, and right of the vehicle with an ECU. ing. For example, when the rotation direction of the rotating body detected by one sensor is different from the rotation directions detected by the other three rotation sensors, the one rotation sensor is determined to be in an abnormal state.

Japanese Patent Laid-Open No. 2001-165951 (paragraphs 6-11, 25-46, FIG. 3, FIG. 7, FIG. 8, etc.) JP 2002-228673 A (8th paragraph, FIG. 1, etc.)

  The technique described in Patent Document 1 does not superimpose another signal indicating additional information related to rotation on an output signal indicating the rotation speed. Therefore, it is possible to transmit additional information related to rotation without being restricted by the rotation speed, for example, the rotation speed increases and the interval between pulses indicating the rotation speed is shortened, making it difficult to superimpose other signals. it can. In addition, the possibility that other signals superimposed on the rotation speed signal are adversely affected by noise is reduced. However, in the technique of Patent Document 1, an abnormal state of the rotation sensor can be transmitted only after the rotation speed of the rotating body is equal to or higher than a predetermined rotation speed. Further, the detection signal processing device of Patent Document 1 includes an error code generation circuit that generates an error code indicating an abnormal state of the rotation sensor. For this reason, there is a risk of increasing the circuit scale of the detection signal processing device as the signal processing function increases. When the detection signal processing device is constituted by an integrated circuit or the like, there is a possibility that the chip area constituting the integrated circuit is increased and the cost is increased. Alternatively, when the rotation detection unit of the rotation sensor and the signal processing circuit that processes various signals are made into one chip, the increase in the chip area reduces the degree of freedom for mounting the chip as the rotation sensor, and the chip area An increase in this becomes a limitation in downsizing the rotation sensor.

  The method described in Patent Document 2 is for determining abnormality of the rotation sensor in a control device such as an ECU other than the rotation sensor, and the abnormality cannot be determined by the single rotation sensor.

  The present invention is an invention related to a rotation detection sensor created in view of the above-described problems, and detects an abnormal state of the rotation detection sensor by the rotation detection sensor itself without depending on the rotation speed of the rotating body. It is an object to make it possible to output the detection result.

The characteristic configuration of the rotation detection sensor according to the present invention for achieving the above object is as follows:
Two rotation detectors that each output a pulsed rotation detection signal in accordance with the rotation of the rotating body;
Based on the two-phase rotation detection signals output from the rotation detection unit, a rotation direction detection unit that detects the rotation direction of the rotating body,
An abnormality detection unit for detecting an abnormality of the rotation detection unit;
Based on the detection results of the rotation detection unit, the rotation direction detection unit, and the abnormality detection unit,
When the rotating body rotates in the positive direction, a pulsed first output signal indicating the rotating direction and rotation speed of the rotating body is generated and output,
When the rotating body rotates in the reverse direction, the second output signal has a pulse shape different from the first output signal, and generates and outputs a second output signal indicating the rotation direction and the rotation speed of the rotating body,
When one of the rotation detectors is abnormal, a third output signal having a pulse shape different from the first output signal and the second output signal and indicating the abnormal state and the rotation speed of the rotating body is generated. A signal processing unit for outputting
It is in the point provided with.

According to this characteristic configuration, when one of the rotation detection units is abnormal, the third output signal indicating the abnormal state and the rotation speed of the rotating body is output from the rotation detection sensor regardless of the rotation speed of the rotating body. Is output. The rotation detection sensor of the present invention does not enable output of a signal indicating an abnormal state after the speed of the rotating body exceeds a predetermined speed, unlike the conventional sensor, but indicates an abnormal state regardless of the rotational speed. A signal (third output signal) can be output. The third output signal can indicate at least the rotational speed. Therefore, the control device that receives the output of the rotation detection sensor and performs various controls can obtain information on the rotation speed of the rotating body that is considered to be the most important even if any one of the rotation detection units is abnormal. Can do. Further, since the third output signal is a signal having a waveform different from that of the first output signal and the second output signal indicating the rotation direction, the control device does not obtain erroneous rotation direction information. Further, since the third output signal indicating the abnormal state is generated and output by the determination in the rotation detection sensor, a control device different from the rotation detection sensor is not required for detecting the abnormal state.
As described above, according to this characteristic configuration, it is possible to provide a rotation detection sensor capable of detecting and outputting an abnormality of the rotation sensor by the rotation detection sensor itself without depending on the rotation speed of the rotating body. Is possible.

  The rotation detection sensor according to the present invention further includes a reset unit that resets the rotation detection unit based on a detection result of the abnormality detection unit.

  The abnormal state occurring in the rotation detection unit may be resolved by returning the setting of the rotation detection unit to the initial state, that is, resetting. Conventionally, such a reset is performed by turning off the power to the sensor and turning it on again. Such an operation is performed by a control device that controls the sensor. Therefore, it is necessary to transmit the abnormality to the control device even if it is a minor abnormality and to have the controller perform a reset operation. For this reason, even if an abnormality is resolved by resetting, it takes time to resolve the abnormality. According to this characteristic configuration, the rotation detection sensor can reset the rotation detection unit without operating the power supply. Accordingly, an abnormality that can be resolved by resetting can be quickly resolved. In addition, the control device that receives the detection signal from the rotation detection sensor can receive a normal output signal without performing extra control.

  Further, in the rotation detection sensor according to the present invention, when the abnormality detection unit determines that any one of the two-phase rotation detection signals does not switch pulses for a predetermined time, or a predetermined voltage range. When it is determined that the rotation detector is out of the range, an abnormality of the rotation detection unit is detected.

  According to this characteristic configuration, the abnormality of the rotation detection unit is detected based on the signal state of the rotation detection signal. Therefore, the abnormality detection unit can be configured with a simple circuit configuration.

The rotation detection sensor according to the present invention is characterized in that the signal processing unit generates and outputs the first output signal, the second output signal, and the third output signal as follows.
That is, when the abnormality detection unit does not detect an abnormality of the rotation detection unit, the signal processing unit uses a two-phase rotation detection signal and has a waveform different from any of the two-phase rotation detection signals. The first output signal and the second output signal are generated and output.
In addition, when the abnormality detection unit detects an abnormality of the rotation detection unit, the signal processing unit outputs a normal rotation detection signal of the two-phase rotation detection signals as the third output signal. To do.

  According to this characteristic configuration, when one of the two-phase rotation detection signals is abnormal, a normal rotation detection signal is output as the third output signal. Since the rotation detection signal includes information indicating the rotation speed in only one phase, the rotation detection signal is a signal that functions sufficiently as at least a third output signal indicating the rotation speed. Therefore, the third output signal indicating an abnormal state can be generated using a simple circuit such as a multiplexer without using a complicated circuit such as an error code generation circuit.

  Further, the signal processing unit of the rotation detection sensor according to the present invention provides the first output according to the state of the other pulse in a section in which one of the two-phase rotation detection signals is at a high level. A signal and the second output signal are generated.

  When the rotation detector is normal, the two-phase rotation detection signals are signals having different phases. Accordingly, the state of the other pulse in the section in which the pulse of one rotation detection signal is at a high level varies depending on the rotation direction. According to this characteristic configuration, the first output signal and the second output signal are generated according to the state of the other pulse in the section in which one pulse of the two-phase rotation detection signal is at the high level. Accordingly, it is possible to generate the first output signal and the second output signal having different pulse shapes depending on the rotation direction. In addition, when an abnormality occurs in the rotation detection unit, the second output signal cannot be generated using the two-phase rotation detection signal, and therefore an output signal is generated using one of the rotation detection signals. Is done. Therefore, the pulse shape of the signal output from the rotation detection sensor differs between normal and abnormal. At this time, if the normal rotation detection signal is output as the third output signal among the two-phase rotation detection signals, the first output signal, the second output signal, and the third output signal can be clearly defined with a simple configuration. It can be distinguished and is suitable. As a result, the control device that receives the output signal from the rotation detection sensor and performs various controls can accurately acquire information from the output from the rotation detection sensor.

  In addition, the signal processing unit of the rotation detection sensor according to the present invention superimposes the other pulse in a section in which one pulse of the two-phase rotation detection signal is at a high level. A signal and the second output signal are generated.

  According to this characteristic configuration, when the rotation detection unit is normal, a waveform in which a part of the other is superimposed on one of the two-phase rotation detection signals is output from the rotation detection sensor. When the rotation detector is normal, the two-phase rotation detection signals are signals having different phases. Accordingly, the section in which the pulse of one rotation detection signal is at a high level and the section in which the other pulse is at a high level differs depending on the rotation direction. Therefore, a first output signal and a second output signal having different pulse shapes according to the rotation direction are generated by superimposing the other pulse in a section where one of the rotation detection signals is at a high level. can do. When an abnormality occurs in the rotation detection unit, only one of the normal rotation detection signals can be used, and the other abnormal rotation detection signal cannot be superimposed. For this reason, an output signal is generated using one of the rotation detection signals. Therefore, the pulse shape of the signal output from the rotation detection sensor differs between normal and abnormal. At this time, if the normal rotation detection signal is output as the third output signal among the two-phase rotation detection signals, the first output signal, the second output signal, and the third output signal can be clearly defined with a simple configuration. It can be distinguished and is suitable. As a result, the control device that receives the output signal from the rotation detection sensor and performs various controls can accurately acquire information from the output from the rotation detection sensor.

[First Embodiment]
Embodiments of the present invention will be described below with reference to the drawings, taking as an example the case where the present invention is applied to a rotation detection sensor that detects the rotation of a vehicle wheel. The rotation detection sensor is provided on each wheel in order to detect a rotation state of each wheel necessary for control of an in-vehicle system such as an anti-lock brake system (ABS) or a vehicle stable running control device.

  FIG. 1 is a block diagram schematically illustrating a configuration example of the rotation detection sensor of the present embodiment. As shown in FIG. 1, the rotation detection sensor 20 is installed in the vicinity of a rotating body 30 that is a target for detecting a rotation direction and a rotation speed (rotation speed / rotation frequency). The rotating body 30 is provided with a magnet 31 that rotates integrally with a wheel (not shown). The magnets 31 are provided at a predetermined pitch in the circumferential direction on the outer peripheral portion of the rotating body 30. Further, the magnet 31 is magnetized so as to be alternately N-pole and S-pole toward the radially outer side. For the sake of simplicity, FIG. 1 shows a case where 12 poles (six pole pairs) are formed.

  The rotation detection sensor 20 has two magnetic detection units 1 (rotation detection units) having the magnetic sensor 2. The magnetic sensor 2 is configured using a magnetoresistive element. The rotation detection sensor 20 is arranged such that the first magnetic sensor 2 </ b> A and the second magnetic sensor 2 </ b> B are opposed to the magnet 31 of the rotating body 30. The first magnetic sensor 2A and the second magnetic sensor 2B have a distance obtained by adding or subtracting a distance of 1/4 of the pitch to a distance that is an integral multiple of the distance between the pair of N poles and S poles of the magnet 31. Arranged.

  Although the outputs of the first magnetic sensor 2A and the second magnetic sensor 2B are sinusoidal, they are shaped by the preprocessing unit 3 (3A, 3B). The preprocessing unit 3 includes an impedance conversion circuit, an amplifier circuit, a comparator, and the like. Then, the magnetic detection unit 1 (1A, 1B) outputs a rotation detection signal S (S1 and S2) having a rectangular wave shape as shown in FIG. Here, the rotation detection signal S1 is a signal output from the first magnetic detection unit 1A, and the rotation detection signal S2 is a signal output from the second magnetic detection unit 1B. As described above, the first magnetic sensor 2 </ b> A and the second magnetic sensor 2 </ b> B are arranged at a distance obtained by adding or subtracting a distance that is a quarter of the pitch to a distance that is an integral multiple of the pitch of the magnets 31. Accordingly, the rotation detection signals S1 and S2 are signals whose phases are substantially different from each other by a quarter period as shown in FIG.

  Although details will be described later, the rotational direction of the rotating body 30 can be detected by the phase difference between the two-phase rotation detection signals S1 and S2. FIG. 2 shows the waveforms of the rotation detection signals S1 and S2 when the rotating body 30 rotates forward. FIG. 3 to be described later shows waveforms of the rotation detection signals S1 and S2 when the rotating body 30 rotates in the reverse direction.

  The rotation detection sensor 20 functions in addition to the magnetic detection unit 1, the rotation direction detection unit 4, the rotation speed detection unit 5, the abnormality detection unit 6, the reset unit 7, the signal processing unit 8, the current output unit 9, the power supply unit 10, and the like. Has a part. Hereinafter, each functional unit will be described.

  The rotation direction detection unit 4 detects the rotation direction of the rotating body 30 based on the two-phase rotation detection signals S1 and S2 output from the two magnetic detection units 1A and 1B. As shown in FIG. 2, when the rotating body 30 rotates in the positive direction, the phase of the rotation detection signal S1 of the first magnetic sensor 2A is ahead of the phase of the rotation detection signal S2 of the second magnetic sensor 2B. . However, when the rotating body 30 rotates in the reverse direction as shown in FIG. 3, the phase of the rotation detection signal S2 of the second magnetic sensor 2B is ahead of the phase of the rotation detection signal S1 of the first magnetic sensor 2A. It is out. Therefore, the rotation direction can be detected from the phase relationship between the two-phase rotation detection signals S1 and S2. The rotation direction detector 4 detects the rotation direction of the rotating body 30 based on this principle.

  The rotation speed detector 5 detects the rotation speed of the rotating body 30 using at least one of the two-phase rotation detection signals S1 and S2. The rotation detection signals S1 and S2 are signals having the same frequency according to the rotation speed of the rotating body, only having different phases. Therefore, by measuring the frequency of one of the rotation detection signals, the rotation speed (rotation frequency / number of rotations) of the rotating body 30 can be detected. For example, the rotation speed detection unit 5 may be configured to detect the rotation speed using only the rotation detection signal S1. The rotation detection signal S2 may be used when the rotation detection signal S1 cannot be used, such as when the magnetic detection unit 1A is abnormal. Naturally, conversely, the rotation detection signal S2 may be used at the normal time, and the rotation detection signal S1 may be used when the magnetic detection unit S2 is abnormal. Further, the rotation speed may be detected by using both of the rotation detection signals S1 and S2, and the average thereof may be taken.

  The abnormality detection unit 6 is a functional unit that detects an abnormality of the magnetic detection unit 1. The abnormality detection unit 6 detects the abnormality by measuring the states of the rotation detection signals S1 and S2. 4 and 5 show examples of waveforms when the rotation detection signal S (S1, S2) is not normal.

  As shown in FIG. 4, the abnormality detection unit 6 determines that the rotation detection signal S is not normal when there is no change in the pulse over a predetermined time T set longer than the time of one cycle of a normal pulse. judge. Then, the abnormality of the magnetic detection unit 1 corresponding to the rotation detection signal S is detected. Note that the time of one cycle of the pulse of the rotation detection signal S varies depending on the rotation speed of the rotating body 30, and therefore it is preferable to change the predetermined time T according to the rotation speed detected by the rotation speed detector 5.

  Further, as shown in FIG. 5, the abnormality detection unit 6 determines that the rotation detection signal S is not normal when the rotation detection signal S is out of one or both of a predetermined Hi voltage range and Lo voltage range. judge. Then, the abnormality of the magnetic detection unit 1 corresponding to the rotation detection signal S is detected.

  The abnormality as described above is caused by a threshold value shift or an abnormality in offset adjustment or gain adjustment in the signal processing for the output of the magnetic sensor 2 performed in the preprocessing unit 3. . The pre-processing unit 3 includes a disturbance of the magnetic field in the space acting on the magnetic sensor 2 due to the iron piece adsorbed to the rotating body 30 for a short time, a change in the magnitude or magnetic flux density of the magnetic field sensed by the magnetic sensor 2, a sudden temperature It tries to follow various changes by changing various parameters such as threshold values and offset values. If a mismatch occurs at this time, the rotation detection signal S output from the magnetic detection unit 1 via the preprocessing unit 3 becomes abnormal. The reset unit 7 is a functional unit that resets the magnetic detection unit 1 in which an abnormality is detected based on the detection result of the abnormality detection unit 6. Specifically, the threshold value, the Hi voltage range, the Lo voltage range, the peak voltage setting value, the bottom voltage setting value, the offset value, the gain, and the like in the preprocessing unit 3 are returned to the initial values. The reset unit 7 may be configured to reset both the magnetic detection units 1 including the normal magnetic detection unit 1.

  The signal processing unit 8 is a functional unit that generates and outputs a signal indicating the rotation direction and rotation speed, or a signal indicating the abnormal state and rotation speed of the magnetic detection unit 1. A signal Q1 illustrated in FIG. 2 is an example of an output signal (first output signal) that is generated and output when the rotating body 30 rotates in the forward direction. The signal Q2 shown in FIG. 3 is an example of an output signal (second output signal) that is generated and output when the rotating body 30 rotates in the reverse direction. The signal Q3 shown in FIG. 6 is an example of an output signal (third output signal) that is generated and output when the second magnetic detection unit 1B is abnormal and the rotation detection signal S2 is abnormal.

  The first output signal Q1 and the second output signal Q2 shown in FIG. 2 and FIG. 3 are states of the pulse of the other rotation detection S2 in the section where the pulse of one rotation detection signal S1 is in the Hi state (high level). Is generated according to Specifically, the first output signal Q1 and the second output signal Q2 are waveforms in which the rotation detection signal S2 of the second magnetic detection unit 2A is superimposed when the rotation detection signal S1 of the first magnetic detection unit 1A is in the Hi state. Is generated as As shown in FIGS. 2 and 3, a pulse having a width narrower than the pulse width in the Hi state of the rotation detection signal S1 is superimposed on the pulse in the Hi state.

  Thus, the first output signal Q1 and the second output signal Q2 are signals generated using the two-phase rotation detection signals S1 and S2, and have different waveforms from the two-phase rotation detection signals S1 and S2. Signal. Further, as is apparent from FIGS. 2 and 3, the first output signal Q1 and the second output signal Q2 are different in positions where a narrow pulse is superimposed depending on the rotation direction. That is, the first output signal Q1 and the second output signal Q2 are signals having different pulse shapes. Due to the difference in pulse shape (waveform), the first output signal Q1 and the second output signal Q2 are output signals each including information indicating the rotation direction. On the other hand, the pulse periods of the first output signal Q1 and the second output signal Q2 are the same as those of the rotation detection signal S1 (and S2). Accordingly, the first output signal Q1 and the second output signal Q2 are output signals each including information indicating the rotational speed. That is, the first output signal Q1 and the second output signal Q2 are signals indicating the rotation direction by the pulse shape and the rotation speed by the pulse period (frequency).

  The third output signal Q3 is a signal having a waveform different from that of the first output signal Q1 and the second output signal Q2. That is, each pulse of the third output signal Q3 has a different shape from the pulse of the first output signal Q1 and the pulse of the second output signal Q2. As in the prior art described in Patent Document 1, the pulse of the first output signal Q1 and the pulse of the second output signal Q2 are combined to form a waveform different from the first output signal Q1 and the second output signal Q2 as a whole. It is possible to do. However, with this method, it is not possible to represent the presence or absence of an abnormality or the direction of rotation with a single pulse. Therefore, the control device that receives the output signal Q of the rotation detection sensor 20 and acquires information cannot acquire information such as the presence / absence of an abnormality and the rotation direction from a single pulse. However, if the present invention is applied, the third output signal Q3 has a pulse shape different from the pulses of the first output signal S1 and the second output signal S2, so that the presence or absence of abnormality can be expressed by a single pulse. it can.

  In the present embodiment, the third output signal Q3 is generated using a normal rotation detection signal among the rotation detection signals S1 and S2. As an example, the signal processing unit 8 can output the normal rotation detection signal S as it is as the third output signal Q3. As described above, in the present embodiment, the first output signal S1 and the second output signal S2 are generated with a pulse shape different from that of the rotation detection signals S1 and S2. Therefore, even if the normal rotation detection signal S is used as it is as the third output signal Q3, the signal has a pulse shape different from that of the first output signal Q1 and the second output signal S2.

  FIG. 6 shows an example of the third output signal Q3. The example shown in FIG. 6 shows a case where the second magnetic detection unit 1B has an abnormality and the rotation detection signal S2 is not normal. In this example, since the rotation detection signal S1 of the first magnetic detection unit 1A is normal, the rotation detection signal S1 is output as the third output signal. The third output signal Q3 has a different pulse shape from the first output signal Q1 and the second output signal Q2, and this pulse shape does not indicate the direction of rotation but indicates that the magnetic detection unit 1 is abnormal. Show. On the other hand, the pulse period of the third output signal Q3 is the same as that of the rotation detection signal S1 or S2 used to generate the third output signal Q3. Accordingly, the third output signal Q3 is an output signal that indicates the rotation speed according to the cycle of the pulse, like the first output signal Q1 and the second output signal Q2.

  As described above, two-phase rotation detection signals S1 and S2 are necessary for detecting the rotation direction. However, any one of the rotation detection signals S1 or S2 is sufficient for detecting the rotation speed. The third output signal Q3 output when the magnetic detection unit 1 is abnormal includes at least information indicating the rotation speed. Therefore, even if an abnormality occurs in one of the magnetic detection units 1A and 1B, if the other is normal, the rotation detection sensor 20 can detect at least the rotation speed of the rotating body 30.

  In the present embodiment, the rotation detection sensor 20 outputs information such as the rotation direction, the rotation speed, and the presence / absence of abnormality of the magnetic detection unit 1 as a current output signal. For this reason, the rotation detection sensor 20 includes a current output unit 9. The current output unit 9 receives supply of current from the power supply 10 and outputs the output signal Q (Q1, Q2, Q3) from the signal processing unit 8 as a current output signal. The current output unit 9 outputs the output signal Q with a small current value when the output signal Q is at the Lo level, and outputs the output signal Q by adding a predetermined current when the output signal Q is at the Hi level.

  Note that the pulse shape of each output signal Q shown in FIGS. 2, 3, and 6 can be appropriately changed. It is sufficient that the first output signal Q1, the second output signal Q2, and the third output signal Q3 are configured to be distinguishable depending on the pulse shape.

  FIG. 7 is a flowchart showing an example of a signal processing procedure of the rotation detection sensor 20 having the above-described function. As described above, the abnormality detection unit 6 detects whether or not the rotation detection signal S is abnormal. When there is no abnormality, the signal processing unit 8 generates and outputs the first output signal S1 or the second output signal S2 in accordance with the rotation direction detected by the rotation direction detection unit 4.

  When it is determined that the rotation detection signal S is abnormal, the reset unit 7 resets the abnormal magnetic detection unit 1A or 1B. Then, the abnormality detection unit 6 detects again whether or not the rotation detection signal S is abnormal. Here, if the abnormal state has been eliminated, the signal processing unit 8 generates and outputs the first output signal S1 or the second output signal S2 in accordance with the rotation direction detected by the rotation direction detection unit 4. .

  If the abnormal state is not resolved even when the magnetic detection unit 1 is reset by the reset unit 7, the signal processing unit 8 generates and outputs a third output signal S3.

[Second Embodiment]
The output signal Q is not limited to the examples shown in FIGS. 2, 3, and 6 and can take various forms. 8, 9, and 10 are waveform diagrams illustrating a second example of the output signal of the rotation detection sensor 20. FIG. 8 shows the output signal (first output signal Q1) of the rotation detection sensor 20 during forward rotation, and FIG. 9 shows the output signal (second output signal Q2) of the rotation detection sensor 20 during reverse rotation. Yes.

  As in the first embodiment, the first output signal Q1 and the second output signal Q2 are pulses of the other rotation detection signal S2 in a section in which the pulse of one rotation detection signal S1 is in the Hi state (high level). It is generated according to the state. Specifically, when the rotation detection signal S1 of the first magnetic detection unit 1A is in the Hi state and the rotation detection signal S2 of the second magnetic detection unit 1B is in the Hi state, the rotation detection signal S1 and the rotation detection signal S2 A logical sum pulse is output as the first output signal Q1. That is, the first output signal Q1 is output as a signal having a pulse width wider than the pulse width of the rotation detection signals S1 and S2 in the Hi state. When the rotation detection signal S1 of the first magnetic detection unit 1A is in the Hi state and the rotation detection signal S2 of the second magnetic detection unit 1B is in the Lo state (low level), the logic of the rotation detection signal S1 and the rotation detection signal S2 The product pulse is output as the second output signal Q2. That is, the second output signal Q2 is output as a signal having a pulse width narrower than the pulse width of the rotation detection signals S1 and S2 in the Hi state. The pulse of the second output signal Q2 has a narrower shape in the Hi section than the pulse of the first output signal Q1. This pulse width indicates the direction of rotation.

  As described above, the first output signal Q1 and the second output signal Q2 can be generated by performing a logical operation on the two-phase rotation detection signals S1 and S2, but are generated as follows. You can also That is, a signal that rises when one rotation detection signal S1 rises and falls when the other rotation detection signal S2 falls may be the first output signal Q1 and the second output signal Q2. When the other rotation detection signal S2 rises later than one rotation detection signal S1, the pulse width of the Hi section becomes longer, and a first output signal Q1 as shown in FIG. 8 is obtained. When the rotation detection signal S2 of the other rises before the rotation detection signal S1, the rotation detection signal S2 falls before the rotation detection signal S1, so that the pulse width of the Hi section is shortened. A second output signal Q2 as shown in FIG.

  FIG. 10 shows an output signal (third output signal Q3) of the rotation detection sensor 20 when the magnetic detection unit 1 is in an abnormal state. In this example, among the two-phase rotation detection signals S1 and S2, the third output signal Q3 is output with the same pulse width as the pulse width of the Hi section of the normal rotation detection signal. The pulse of the third output signal Q3 is a pulse having a width different from that of the first output signal Q1 and the second output signal Q2. In this example, the pulse width of the third output signal Q3 is narrower than the pulse width of the first output signal Q1 in the Hi period. This is a pulse having a width wider than the pulse width of the signal Q2. An abnormal state of the magnetic detection unit 1 is indicated by this pulse width.

  The pulse width relationships shown in FIGS. 8 to 10 can be changed as appropriate. For example, the pulse width of the first output signal Q1 may be narrower than that of the second output signal Q2. Further, of the two-phase rotation detection signals S1 and S2, the third output signal Q3 is not limited to being output with the same pulse width as the pulse width of the Hi section of the normal rotation detection signal, It may be output with a different pulse width. It is sufficient that the first output signal Q1, the second output signal Q2, and the third output signal Q3 are configured to be distinguishable depending on the pulse width.

[Third Embodiment]
11, 12, and 13 are waveform diagrams showing a third example of the output signal of the rotation detection sensor 20. FIG. 11 shows the output signal (first output signal Q1) of the rotation detection sensor 20 during forward rotation, and FIG. 12 shows the output signal (second output signal Q2) of the rotation detection sensor 20 during reverse rotation. Yes.

  As in the first embodiment, the first output signal Q1 and the second output signal Q2 are pulses of the other rotation detection signal S2 in a section in which the pulse of one rotation detection signal S1 is in the Hi state (high level). It is generated according to the state. Specifically, when the rotation detection signal S1 of the first magnetic detection unit 1A is in the Hi state (at the time of rising), if the rotation detection signal S2 of the second magnetic detection unit 1B is in the Lo state, the rotation detection signal A signal having a smaller amplitude of the pulse in the Hi state than S1 and S2 is output as the first output signal Q1. When the rotation detection signal S1 of the first magnetic detection unit 1A is in the Hi state and the rotation detection signal S2 of the second magnetic detection unit 1B is in the Hi state, the pulse of the Hi state is higher than the rotation detection signals S1 and S2. A signal having a large amplitude is output as the second output signal Q2. The pulse of the first output signal Q1 has a smaller amplitude in the Hi section than the pulse of the second output signal Q2. This amplitude indicates the direction of rotation.

  FIG. 13 shows an output signal (third output signal Q3) of the rotation detection sensor 20 when the magnetic detection unit 1 is in an abnormal state. In this example, among the two-phase rotation detection signals S1 and S2, the third output signal Q3 is output with the same amplitude as that of the Hi section of the normal rotation detection signal. The pulse of the third output signal Q3 is a pulse having a different amplitude from that of the first output signal Q1 and the second output signal Q2. In this example, the pulse is larger than the amplitude of the first output signal Q1 in the Hi section, and the second output signal The pulse has an amplitude smaller than the amplitude of Q2. This amplitude indicates an abnormal state of the magnetic detection unit 1.

  The amplitude relationship shown in FIGS. 11 to 13 can be changed as appropriate. For example, the amplitude of the second output signal Q2 may be smaller than that of the first output signal Q1. In addition, the second output detection signal Q3 is not limited to having the same amplitude as that of the Hi section of the normal rotation detection signal among the two-phase rotation detection signals S1 and S2. It may be output with a pulse width. It is sufficient that the first output signal Q1, the second output signal Q2, and the third output signal Q3 are configured to be distinguishable depending on the amplitude.

[Fourth Embodiment]
As described above, the time of one cycle of the rotation detection signal S varies depending on the rotation speed of the rotating body 30. When the rotating body 30 starts rotating or when the rotation direction is switched, the rotation speed is very slow. Therefore, the pulse period of the rotation detection signal S becomes very long. As described above, when the abnormality detection unit 6 detects an abnormality in the magnetic detection unit 1 because the change in the pulse of the rotation detection signal S does not occur over the predetermined time T, the predetermined time T serving as a determination criterion is set to the emergency time. Need to be set to a long time. Even when the predetermined time T is changed according to the rotation speed, when the rotation speed is very low, the abnormality is not substantially detected. Therefore, it is preferable that the abnormality determination is performed after the rotational speed of the rotating body 30 reaches a predetermined rotational speed (frequency).

  FIG. 14 is a flowchart showing processing in which the above-described modification is added to the flowchart shown in FIG. First, it is determined whether or not the frequency of the rotation detection signal S measured by the rotation speed detector 5 is equal to or higher than a predetermined frequency. When it is determined that the frequency is less than the predetermined frequency, the frequency determination of the rotation detection signal S is repeatedly executed.

  When it is determined that the frequency of the rotation detection signal S is equal to or higher than the predetermined frequency, the abnormality detection unit 6 detects whether or not the rotation detection signal S is abnormal as described above. When there is no abnormality, the signal processing unit 8 generates and outputs the first output signal S1 or the second output signal S2 in accordance with the rotation direction detected by the rotation direction detection unit 4.

  When it is determined that the rotation detection signal S is abnormal, the reset unit 7 resets the abnormal magnetic detection unit 1A or 1B. Then, the abnormality detection unit 6 detects again whether or not the rotation detection signal S is abnormal. Here, if the abnormal state has been eliminated, the signal processing unit 8 generates and outputs the first output signal S1 or the second output signal S2 in accordance with the rotation direction detected by the rotation direction detection unit 4. .

  If the abnormal state is not resolved even when the magnetic detection unit 1 is reset by the reset unit 7, the signal processing unit 8 generates and outputs a third output signal S3.

  As described above, according to the present invention, it is possible to provide a rotation detection sensor capable of detecting and outputting a sensor abnormality by the sensor itself without depending on the rotation speed of the rotating body.

The block diagram which shows the structural example of the rotation detection sensor of this embodiment typically Waveform diagram showing an example of the rotation detection signal during forward rotation and an example of the output signal of the rotation detection sensor Waveform diagram showing an example of the rotation detection signal during reverse rotation and an example of the output signal of the rotation detection sensor Waveform diagram showing an example of an abnormal rotation detection signal Waveform diagram showing an example of an abnormal rotation detection signal Waveform diagram showing an example of the rotation detection signal at the time of abnormality and an example of the output signal of the rotation detection sensor Flow chart showing an example of signal processing procedure of rotation detection sensor Waveform diagram showing a second example of the output signal of the rotation detection sensor during forward rotation Waveform diagram showing a second example of the output signal of the rotation detection sensor during reverse rotation Waveform diagram showing a second example of the output signal of the rotation detection sensor at the time of abnormality Waveform diagram showing a third example of the output signal of the rotation detection sensor during forward rotation Waveform diagram showing a third example of the output signal of the rotation detection sensor during reverse rotation Waveform diagram showing a third example of the output signal of the rotation detection sensor at the time of abnormality Flow chart showing another example of signal processing procedure of rotation detection sensor

Explanation of symbols

1, 1A, 1B: Magnetic detection unit (rotation detection unit)
4: rotation direction detection unit 6: abnormality detection unit 7: reset unit 8: signal processing unit 30: rotating body Q: output signal Q1: first output signal Q2: second output signal Q3: third output signals S, S1, S2: Rotation detection signal T: Predetermined time

Claims (6)

Two rotation detectors that each output a pulsed rotation detection signal in accordance with the rotation of the rotating body;
Based on the two-phase rotation detection signals output from the rotation detection unit, a rotation direction detection unit that detects the rotation direction of the rotating body,
An abnormality detection unit for detecting an abnormality of the rotation detection unit;
Based on the detection results of the rotation detection unit, the rotation direction detection unit, and the abnormality detection unit,
When the rotating body rotates in the positive direction, a pulsed first output signal indicating the rotating direction and rotation speed of the rotating body is generated and output,
When the rotating body rotates in the reverse direction, the second output signal has a pulse shape different from the first output signal, and generates and outputs a second output signal indicating the rotation direction and the rotation speed of the rotating body,
When one of the rotation detectors is abnormal, a third output signal having a pulse shape different from the first output signal and the second output signal and indicating the abnormal state and the rotation speed of the rotating body is generated. A signal processing unit for outputting
A rotation detection sensor comprising:   The rotation detection sensor according to claim 1, further comprising a reset unit that resets the rotation detection unit based on a detection result of the abnormality detection unit.   When the abnormality detection unit determines that any one of the two-phase rotation detection signals does not switch a pulse for a predetermined time, or determines that it is out of a predetermined voltage range, The rotation detection sensor according to claim 1, wherein an abnormality of the rotation detection unit is detected. The signal processing unit
When the abnormality detection unit does not detect an abnormality of the rotation detection unit, the first output signal having a waveform different from any of the two-phase rotation detection signals and the first phase are detected using the two-phase rotation detection signal. Generate and output two output signals,
When the abnormality detection unit detects an abnormality in the rotation detection unit, the normal rotation detection signal is output as the third output signal among the two-phase rotation detection signals.
The rotation detection sensor as described in any one of Claims 1-3.   The signal processing unit generates the first output signal and the second output signal according to the state of the other pulse in a section where one of the two-phase rotation detection signals is at a high level. The rotation detection sensor as described in any one of Claims 1-4.   The signal processing unit generates the first output signal and the second output signal by superimposing the other pulse in a section in which one of the two-phase rotation detection signals is at a high level. The rotation detection sensor as described in any one of Claims 1-4.

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