JP2742551B2 - Rotation sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a rotation sensor that magnetically detects the rotation of a rotating body and generates a detection signal having a frequency corresponding to the rotating speed and the rotating direction of the rotating body. It is about.

[Conventional technology]

This type of rotation sensor is, for example, interlocked with a rotating part that rotates as the vehicle travels, and is used, for example, as a sensor that generates a traveling signal having a cycle corresponding to the traveling speed of the vehicle. Some are shown in the figure.

First, in the rotation sensor of FIG. 13, reference numeral 11 denotes N, S
A rotating magnet provided so that a plurality of magnetic poles are alternately magnetized and rotated about a rotating shaft 11a, and a Hall element 12 is installed in close proximity to the peripheral surface of the rotating magnet 11 in which N and S magnetic poles are magnetized. And outputs an electric signal corresponding to the N and S magnetic poles on the peripheral surface of the opposed rotating magnet 11. Reference numeral 13 denotes an amplifier that amplifies a detection signal output from the semiconductor magnetic sensor 12.

In this rotation sensor, when the rotating magnet 11 rotates, the magnetic pole on the peripheral surface of the rotating magnet 11 facing the semiconductor magnetic sensor 12 becomes N,
Alternating with S, an electric signal corresponding to this is generated at the output of the semiconductor magnetic sensor 12. This electrical signal is
Thus, the pulse signal is converted into a pulse signal having a frequency corresponding to the rotation speed of the rotating magnet 11.

Therefore, by monitoring the frequency of the pulse signal, for example, the traveling speed of the vehicle can be detected.

In the rotation sensor shown in FIG. 14, reference numeral 14 denotes a gear-shaped rotating body made of a magnetic material and having an uneven portion formed on its peripheral surface, and 15 denotes a magnet 15b and a magnet 15b in a cap-shaped case 15a made of a magnetic material. A magnetic circuit configured to house a center pole 15c made of a body, and between the magnet 15a and the center pole 15c of the magnetic circuit 15, a magnetic flux flowing through the magnetic circuit 15 is detected. A semiconductor magnetic sensor 12 that generates an electric signal according to the size of the sensor is arranged. This electric signal is amplified by the amplifier 13 and output.

In this rotation sensor, when the rotating body 14 rotates and the protrusion on the peripheral surface intermittently approaches the center pole 15c, the magnetic gap G between the center pole 15c and the case 15a decreases, and the magnet 15b → Center pole 15c → Rotating body 14
→ The magnetic resistance of the magnetic circuit 15 including the case 15 a → the magnet 15 b is reduced, and the amount of magnetic flux φ passing through the magnetic circuit 15 is increased. On the other hand, when the recess faces the center pole 15, the magnetic gap G increases, and the magnetic resistance of the magnetic circuit 15 increases, so that the amount of magnetic flux φ passing through the magnetic circuit 15 decreases.

The magnetic flux in the above magnetic flux loop consists of the center pole 15c and the rotating body 1.
4 is maximum when the magnetic gap G is minimum, and the magnetic flux changes according to the size of the magnetic gap G.

Therefore, the rotation of the rotating body 14 causes the magnetic gap G
Changes, the magnetic flux changes sinusoidally according to the rotation angle θ of the rotating body 14, as shown in FIG. Therefore, as shown in FIG. 15, a predetermined threshold level _φth is set for the amplifier 13 that amplifies and shapes the electric signal from the semiconductor magnetic sensor 12,
A pulse signal is output such that the pulse signal becomes H level when the level is higher than the threshold level and L level when the level is lower. Since the frequency of the pulse signal corresponds to the initial rotation of the rotating body 14, the rotation speed of the rotating body can be known from the frequency of the pulse signal.

In order to detect the rotation direction of the rotating body using the rotation sensor as shown in FIGS. 13 and 14, the plurality of semiconductor magnetic sensors 12 and the magnetic circuit 15 are connected to the rotating magnet 11 and the rotating body 14.
These rotating magnets 11 and rotating bodies 14 are spaced
And each semiconductor magnetic sensor 12 and magnetic circuit 15
The rotation direction is detected by the phase difference between the outputs.

[Problems to be solved by the invention]

In the configuration of the individual rotation sensors that constitute the conventional rotation sensor device capable of detecting the rotation direction described above, the rotation sensor of FIG. 13 uses a dedicated rotation magnet 11 in which N and S magnetic poles are alternately magnetized.
In addition, if the number of pulses per rotation of the rotating magnet 11 is increased, the diameter of the rotating magnet 11 must be increased, which makes it difficult to realize the method and increases the cost.

In the rotation sensor shown in FIG. 14, when the magnetic gap G fluctuates due to a dimensional error or a temperature change due to component variation, the amplitude of the magnetic flux changes in accordance with the magnetic gap as shown by a dotted line in FIG.

Therefore, when the change in magnetic flux due to the amplitude and the minimum amplitude is considered in advance, the threshold level of the magnetic sensor 12 must be set within the range of the difference between the maximum values (Δφ in FIG. 15). Therefore, the threshold level setting with high accuracy is required, and the stability and reliability of the pulse signal as the detection signal are reduced.

In particular, in order to detect the rotation direction of the rotating body by using a plurality of the rotation sensors described above, it is necessary to attach detectors having the same characteristics to the rotating body at a plurality of locations with different mechanical phase differences. In addition to increasing the cost, the magnetic flux generated in each rotation sensor spreads in the rotation direction of the adjacent rotating body, so that magnetic interference occurs between the rotation sensors and the output of each rotation sensor is generated. Madness,
There has been a problem that accurate detection of the rotation direction cannot be performed.

Therefore, the present invention provides a rotation sensor capable of detecting a rotation direction that can prevent the occurrence of magnetic interference that hinders accurate detection of the rotation direction while improving the reliability and stability of the rotation detection. The challenge is to provide

[Means for solving the problem]

In order to solve the above-mentioned problems, a rotation sensor according to the present invention is provided with a rotating body made of a magnetic body and provided adjacent to the rotating body so as to face the rotating body and generate a magnetic flux flowing through the rotating body. First and second magnetic circuits are provided opposite to the rotating body and adjacent to the rotating body in the direction of rotation to generate a magnetic flux flowing through the rotating body, and the first and second magnetic circuits and the rotating body rotate. With a predetermined phase difference in the direction,
A third magnetic circuit and a third magnetic circuit which are arranged so as to be shifted from the first and second magnetic circuits in the direction of the rotation axis of the rotating body and are provided integrally with the first and second magnetic circuits; When the rotator is at a position where it is magnetically coupled to the first or second magnetic circuit, the first or second magnetic circuit and the rotator may be connected to a first magnetic path provided in a common magnetic path of a magnetic flux loop formed by the rotator. A first magnetic detecting means and a magnetic flux loop formed by the third or fourth magnetic circuit and the rotating body when the rotating body is at a position magnetically coupled to the third or fourth magnetic circuit; A second magnetic detecting means provided in a common magnetic path, wherein the first and second magnetic detecting means output a detection signal having a frequency and a predetermined phase difference according to a rotation speed of the rotating body. It is characterized by:

(Operation)

In the above configuration, when the rotating body is magnetically coupled to the first magnetic circuit, a magnetic flux flows in a predetermined direction by the rotating body and the first magnetic circuit. When the rotating body is magnetically coupled to the second magnetic circuit, a magnetic flux flows in the same direction as described above by the rotating body and the second magnetic circuit. Since the first magnetic detecting means is provided in a common magnetic path through which the two magnetic fluxes flow, the direction of the magnetic flux passing through the detecting means is the first magnetic detecting means.
And the second magnetic circuit.

Therefore, an AC signal that changes to positive or negative is output to the output of the first magnetic detection means.

Still further, the rotator has a third phase difference having a predetermined phase difference in the rotation direction of the rotator with the first and second magnetic circuits, in the same manner as magnetically coupling the first and second magnetic circuits. 4th
Similarly, the second magnetic detecting means outputs an alternating output having a phase difference from the first magnetic detecting means and having a phase difference between positive and negative.

For this reason, the rotation of the rotating body and the detection of the direction of the rotating body based on the AC signals respectively output from the first and second magnetic detection units are accurately and stably performed.

The first and second magnetic circuits have a predetermined phase difference in the rotation direction of the rotating body with respect to the first and second magnetic circuits, and the third and fourth magnetic circuits provided integrally therewith are replaced with the first and second magnetic circuits. , The position thereof is shifted in the direction of the rotation axis of the rotating body, so that the magnetic flux generated in the first and second magnetic circuits and the third
And a magnetic flux generated in the fourth magnetic circuit, there is an interval in the rotation axis direction of the rotating body, and these two magnetic fluxes do not interfere with each other.
That is, magnetic interference between the first and second magnetic circuits and the third and fourth magnetic circuits is prevented.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 (a) and 1 (b) are views showing an embodiment of a rotation sensor according to the present invention, in which 1 is a rotating body made of a magnetic material and rotating according to a predetermined measurement amount. In the figure, the gear is rotatable in either a clockwise direction or a counterclockwise direction, and has a gear shape in which concave portions 1a and convex portions 1b are alternately formed on a peripheral portion thereof.

In FIG. 1 (a), 2A and 3A denote first and second magnetic circuits, and in FIG. 1 (b), 2B and 3B denote third and fourth magnetic circuits, respectively. The two magnetic circuits 2A, 3A and the third and fourth magnetic circuits 2B, 3B are formed by integrating two sets of rotation sensors as shown in FIG.

That is, the first and second magnetic circuits 2A and 3A and the third and fourth magnetic circuits 2B and 3B are configured. As shown in FIG. 6, the rotation sensor of the present embodiment in which two sets are integrated has a substantially E-shape having left and right poles whose tip portions are respectively N and S poles and a neutral point 20a therebetween. Two integrated magnets 20
As shown in FIG. 2, both molded magnets 20 are shifted back and forth, and one magnet is shifted left and right so that one N pole and the neutral point 20a overlap each other, and the other S pole and the neutral point 20a overlap each other. And a magnetic sensor 35a, 35b provided on each neutral point 20a. The depth D before and after the magnet 33 (see FIG. 2) is set to be equal to or less than the thickness of the projection 1b of the rotating body 1.

FIG. 3 is a perspective view showing the first and second magnetic circuits 2A, 3A. The magnetic circuit 2A, 3A is housed in a case 9 and the detection signal from the magnetic sensor 35a is read. It is connected to terminal 10a of connector 10 via line l.

Although not shown, the case 9 accommodates the third and fourth magnetic circuits 2B and 3B together with the first and second magnetic circuits 2A and 3A.

That is, in FIG. 3, the first and second magnets 33
Although only the formed magnet 20 and the magnetic sensor 35a forming the magnetic circuits 2A and 3A are shown, actually, the formed magnet 20 and the magnetic sensor 35b forming the third and fourth magnetic circuits 2B and 3B are shown. Also, they are housed inside the case 9 shifted to the front, rear, left and right in the above-described manner with respect to the molded magnets 20 constituting the first and second magnetic circuits 2A and 3A.

Then, the magnet 33 is mounted together with the case 9 in a hole provided in the mounting case 32 and then fixed by the screw 36.

As a result, the case 9 is disposed so as to face the rotating body 1, and the magnet 33 is formed between the projection 1 b of the rotating body 1 and the gap t.
Are located to face each other.

In the above configuration, the operation is shown in FIG.
This will be described with reference to (b) and FIG. Here, for the sake of simplicity, the magnet 33 is replaced with the two molded magnets described above.
The operation will be described for each of the molded magnets 20.

First, as shown in FIG. 4 (a), the projection 1b of the rotating body 1
When the molded magnet 20 of the (third) magnetic circuit 2A (2B) is located close to the left pole and the neutral point 20a side in the drawing, the first (third) magnetic circuit 2A (2B) And the rotating body 1 are magnetically coupled, and the pole on the left side in the figure → the rotating body 1 → the neutral point 20
a → A magnetic flux loop of the left pole in the figure is formed.

Therefore, the magnetic flux phi _a of the flux loop flows as shown in the counterclockwise direction, its magnitude depending on the magnetic gap between the rotating body 1 of the projection 1b and the left side in the drawing of the pole and the neutral point 20a changes I do. Therefore, the magnetic flux passing through the neutral point 20a in the magnetic flux loop is directed upward in the drawing, and the magnetic flux flowing through the magnetic sensor 35a (35b) with respect to the rotation angle θ of the rotating body 1 is positive as shown by the characteristic a in FIG. Sine wave half-wave characteristic in the direction.

Further, as shown in FIG. 4 (b), the convex portion 1b of the rotating body 1 is
When the molded magnet 20 of the (fourth) magnetic circuit 3A (3B) approaches the pole on the right side and the neutral point 20a side in the figure, the second (fourth)
Magnetic circuit 3A (3B) and the rotating body 1 are magnetically coupled to form a magnetic flux loop of the right pole in the figure → the neutral point 20a → the rotating body 1 → the right pole in the figure.

The magnetic flux φ _b of this magnetic flux loop is formed in the counterclockwise direction similarly to the magnetic flux φ _a, and its magnitude is determined according to the magnetic gap between the convex portion 1 b of the rotating body 1, the right pole in the drawing, and the neutral point 20 a. Change. Therefore, a common magnetic path of the first and second (third and fourth) magnetic circuits 2A and 3A (2B and 3B), that is, a second (fourth) magnetic circuit 3A ( Three
The flux phi _b by B), the magnetic circuit 2A of the first (3) (2
The downward direction in the drawing in a direction opposite to the magnetic flux phi _a by B). Therefore, the magnetic sensor 35a (35
The magnetic flux flowing in b) has a sine wave half-wave characteristic in the negative direction as shown by the characteristic b in FIG.

Further, when the convex portion 1b of the rotating body 1 is positioned between the left pole and the right pole of the molded magnet 20 in FIG.
The magnetic flux passing through 20a has the same magnitude but opposite directions, and is canceled out to zero. Therefore, the magnetic sensor 35a (35
In b), a sinusoidal alternating magnetic flux as shown in FIG. 5 combining the above characteristics a and b is applied.

Therefore, if the threshold level of the magnetic sensor 35a (35b) is set in each of the positive and negative directions, a pulse signal which becomes H level corresponding to each peak value is obtained as a detection signal. At this time, the rotor 1
When the gap between the convex portion 1b and the neutral point 20a and the right and left poles in FIG. 4 changes, as the magnetic gap increases as shown in FIG. 5, the amplitude of the magnetic flux decreases. If the sine wave signals a and b having the minimum amplitude of the magnetic flux are set to values that can be detected (the levels φ _th1 and φ _{th2 in} FIG. 5), the magnetic gap changes due to variations in parts and changes in temperature, and the magnetic flux amplitude changes. Also, since there is a margin in the threshold level, a pulse signal as a detection signal can be reliably obtained.

Since the frequency of the pulse signal corresponds to the number of rotations of the rotating body 1 and the number of rotations corresponds to a predetermined measurement amount, the rotation speed of the rotation body, and hence the predetermined measurement amount, is subtracted from the frequency of the pulse signal. Can be detected.

The first and second magnetic circuits 2A and 3A and the third and fourth magnetic circuits 2B and 3B are displaced in the direction of rotation of the rotating body 1, so that the first and second magnetic circuits 2A and 3B are applied to the magnetic sensor 35a. Between the sine-wave AC magnetic flux as shown in FIG. 5 and the sine-wave AC magnetic flux applied to the magnetic sensor 35b as shown in FIG. 5, there are first and second magnetic circuits 2A and 3A, and third and fourth magnetic circuits. Magnetic circuit 2B
And 3B, there is a phase difference corresponding to the displacement in the rotation direction of the rotating body 1.

Therefore, the rotation direction of the rotating body 1 can be detected from the phase difference.

This will be described in detail with reference to FIGS. 10 (a) to 10 (e). In FIGS. 10 (a) to 10 (c), the first
And a second magnetic circuit 2A, 3A collectively indicated by the reference character m _1, third and fourth magnetic circuit 2B, 3B collectively reference numerals m
Indicated by ₂ .

The magnetic circuit m ₁ in a state where the convex portion 1b of the rotating body 1 not approach becomes magnetic distribution as shown in Figure No. 10 (b), the magnetic circuit m ₂ magnetic as shown in Figure No. 10 (c) the form of the phase is delayed 90 ° from the circuit m _1.

In this state, the rotating body 1 rotates and the convex portion 1b is moved to the magnetic circuit m _1.
When the magnetic pole N approaches the magnetic pole S from the magnetic pole N via the neutral point, a detection signal substantially similar to the magnetic flux distribution shown in FIG. 10B is obtained from the magnetic sensor 35a. The magnetic sensor 35a from Similarly magnetic sensor 35b even in the magnetic circuit m ₂
A detection signal delayed by 90 ° from the detection signal is obtained.

The detection signals of these magnetic sensors 35a and 35b are converted into pulse signals by the circuit shown in FIG. That is, the output pulse based on the magnetic sensor 35a, as shown in FIG. 10 (d), H next predetermined time me rising from the position where the convex portion 1b of the rotating body 1 is opposed to the N pole of the magnetic circuit m ₁ Later it will be L. The output pulse based on the magnetic sensor 35b is an output pulse delayed by 90 ° from the output pulse based on the magnetic sensor 35a as shown in FIG. 10 (e). The rising and falling differential points of these output pulses can be arbitrarily adjusted by setting the differential points of the hysteresis amplifier 41 of the circuit shown in FIG.

Based on the above configuration, the rotating body 1 is rotated, the detection projection 1b of the peripheral edge portion thereof, when approaching from the direction of the magnetic circuit m ₁ pole N shown in Figure 10, which is detected by the magnetic sensor 35a The signal is output as a pulse through the circuit shown in FIG. Subsequently, the magnetic sensor 35b attached to the magnetic circuit m ^2, a pulse is output with a delay of a predetermined time from the pulse based on the magnetic sensor 35a.

The rotational direction of the rotating body 1 is determined by determining the temporal sequence of these two pulses by a logic circuit (not shown), and the rotational speed is also determined by measuring the number of pulses.

With the above-described configuration, the first and second magnetic circuits 2A and 3A and the third and fourth magnetic circuits 2B and 3B
Since the position of the rotating body 1 is shifted in the direction of the rotating shaft, a gap in the rotating shaft direction of the rotating body 1 is generated between the magnetic flux flowing through the magnetic sensor 35a and the magnetic flux flowing through the magnetic sensor 35b. Interference is prevented.

Therefore, by preventing the interference between the two magnetic fluxes, the magnetic sensor
It is possible to prevent the output of 35a and 35b from being affected, and to accurately detect the rotation direction of the rotating body 1.

Note that a magnetic resistance element that detects the direction of a magnetic field, a Hall element that detects the magnitude of a magnetic flux, or the like may be used as the magnetic sensor 35a (35b).

 Next, another embodiment will be described.

In this other embodiment, instead of the magnet 33, as shown in FIG. 11 (a), the center is projected as an S pole, the left and right ends are respectively N poles, and the height is aligned with the N pole. Further, a magnet 40 integrally formed with a shape in which a magnetic neutral point lower than these poles is protruded between the S pole and the N pole is used. Then, the magnetic sensors 35a and 35b are respectively mounted on the neutral points. The magnetic flux distribution of the magnet 40 in a state where the convex portion 1b of the rotating body 1 does not approach is as shown in FIG. 11 (b). When the rotating body 1 is projection 1b rotates and passes close to the magnet 40, the detection signal of the magnetic sensor 35a is the same shape as in the magnetic circuit m ₁ described above, also the signal detected by the magnetic sensor 35b is S It is symmetrical with the detection signal of the magnetic sensor 35a about the pole.

In this case as well, the signals detected by the magnetic sensors 35a and 35b are each converted into pulses by the circuit shown in FIG. 12, and as described above, the rotation of the pulses is determined by determining the time order of these pulses by a logic circuit. Determine the direction of rotation of the body.

And also in the case of this embodiment, both magnetic sensors 35a, 35
The magnetic flux flowing through b generates an interval in the direction of the rotation axis of the rotating body 1 to prevent the two magnetic fluxes from interfering with each other, thereby preventing the output of the magnetic sensors 35a and 35b from being affected, and The rotation direction of the body 1 can be accurately detected.

In order to adjust the width between the N and S poles in accordance with the width of the convex portion 1b of the rotating body 1, the first and second magnetic circuits 2A and 3A, and the third and fourth magnetic circuits 2B, As shown in FIG. 7, rectangular magnets 21, 21 are provided on the left and right sides of a yoke 22 made of a magnetic material having a convex cross section, instead of each of the molded magnets 20 of the magnet 33 constituting the 3B.
The pitch L is adjusted according to the width of the projection 1b of the rotating body 1,
The tip may be used by bonding one end to the N pole and the other end to the S pole.

If the width of the convex portion 1b of the rotating body 1 is small and the pitch L cannot be reduced to that extent, as shown in FIG. A center having the same height as the auxiliary poles 23, 23 is provided above the magnetic sensor 8 provided at the magnetic neutral point between the magnets 21, 21 by mounting the auxiliary poles 23, 23. The pole 24 can be mounted and used.

In any case, when the rotating body 1 is not approaching, the magnetic flux distribution is as shown in FIG.

〔The invention's effect〕

According to the present invention as described above, the first and second magnetic detecting means can reliably detect the rotation of the rotating body even with respect to the variation of the components and the temperature change, and the reliability and stability can be improved. Is improved. Further, the first and second magnetic detecting means can also detect a state where the rotating body is not rotating.

Then, when determining the rotation direction of the rotating body based on the phase difference of the rotation of the rotating body detected by the first and second magnetic detecting means, the first and second magnetic detecting means are configured. Since the first and second magnetic circuits and the third and fourth magnetic circuits are integrally configured, the cost of designing, processing, assembling, etc. can be reduced as compared with using a plurality of detectors. In addition, reliability can be improved.

In particular, since the third and fourth magnetic circuits are displaced in the direction of the rotation axis of the rotating body with respect to the first and second magnetic circuits, the magnetic flux generated in the first and second magnetic circuits , And a magnetic flux generated in the third and fourth magnetic circuits, to generate an interval in the direction of the rotation axis of the rotating body.
In addition, it is possible to prevent the occurrence of magnetic interference between the second magnetic circuit and the third and fourth magnetic circuits, and to accurately detect the rotation direction.

[Brief description of the drawings]

1 (a) and 1 (b) are side views showing an embodiment of a rotation sensor according to the present invention, FIG. 2 is a perspective view showing the magnets of FIGS. 1 (a) and (b), and FIG. FIGS. 1 (a) and 1 (b) are perspective views showing the magnetic circuit, FIG. 4 is a view for explaining the operation of the rotation sensor according to the present invention, and FIG. 5 is FIGS. 1 (a) and (b). FIG. 6 is a diagram showing characteristics of magnetic flux flowing through the magnetic sensor with respect to the rotation angle of the rotator in FIG. 6, FIG. 6 is a perspective view showing another magnetic circuit, FIG. 7 is a perspective view showing another magnetic circuit, and FIG. FIG. 9 is a front view showing another magnetic circuit, FIG. 9 is a partially cutaway side view showing one embodiment of a rotation sensor for judging a rotation direction, FIG. 10 (a) is a perspective view showing a magnetic circuit, FIG. b) is a diagram showing the magnetic flux distribution of the first magnetic circuit, FIG. 10 (c) is a diagram showing the magnetic flux distribution of the second magnetic circuit, and FIG. 10 (d) is the first magnetic circuit. FIG. 10 (e) is a view of an output pulse based on a detection signal of the second magnetic detection means, and FIG. 11 (a) is a front view showing another magnetic circuit. FIG. 11 (b) is a diagram showing the magnetic flux distribution, FIG. 12 is an electric circuit diagram for converting a detection signal of the Hall element into a pulse, and FIGS. 13 and 14 are examples of a conventional rotation sensor. FIG. 15 is a diagram showing characteristics of magnetic flux with respect to rotation of the rotating body in the example of FIG. 1 ... rotator, 2A ... first magnetic circuit, 3A ... second magnetic circuit, 2B ... third magnetic circuit, 3B ... fourth magnetic circuit, 33 ... magnet, 35a, 35b …… A magnetic sensor.

Claims (1)

(57) [Claims] A rotator made of a magnetic material, provided adjacent to the rotator in the direction of rotation thereof;
First and second magnetic circuits for generating a magnetic flux flowing through the rotating body, provided opposite to the rotating body and adjacent to the rotating direction,
It generates a magnetic flux flowing through the rotating body, has a predetermined phase difference with the first and second magnetic circuits in the rotating direction of the rotating body, and has a position difference between the first and second magnetic circuits and the rotating body rotating axis direction. A third magnetic circuit and a third magnetic circuit provided integrally with the first and second magnetic circuits so as to be shifted from each other, and the rotating body is magnetically coupled to the first or second magnetic circuit. A first magnetic detecting means provided in a common magnetic path of a magnetic flux loop formed by the first or second magnetic circuit and the rotating body, when the rotating body is in the third or fourth position; A second magnetic detection unit provided in a common magnetic path of a magnetic flux loop formed by the third or fourth magnetic circuit and the rotating body when the magnetic circuit is at a position magnetically coupled to the magnetic circuit; The first and second magnetism detecting means have a frequency and a frequency corresponding to the rotation speed of the rotating body. And outputs a detection signal having a phase difference of a constant, the rotation sensor, characterized in that.