JP2024067963A - Rotation Sensor - Google Patents

Abstract

[Problem] To provide a rotation sensor capable of detecting rotation speed with high accuracy. [Solution] A first flange portion 8 that protrudes in the radial direction of a rotating shaft 22 is attached to the tip of the rotating shaft 22 of a motor 2. A target 3 has a fitting recess 35 into which the first flange portion 8 is fitted. The target 3 is rotatably supported by a reference part 5. A coil spring 10 biases the target 3 in the vertical direction to press it against the reference part 5. The target 3 rotates while making sliding contact with the reference part 5. [Selected Figure] Figure 1

Description

The present invention relates to a rotation sensor.

A rotation sensor that uses eddy currents has been proposed to detect the rotation speed of a motor. This rotation sensor rotates a target in response to the rotation of the motor, generating eddy currents in the target. A detection unit mounted on a wiring board detects the eddy currents generated in the target, thereby detecting the rotation speed of the motor.

In conventional rotation sensors, the motor's rotating shaft is pressed into the target, which is then rotated. For this reason, when thrust play occurs in the motor's rotating shaft, the target also moves in the thrust direction (axial direction). This causes the distance between the target and the wiring board to fluctuate, making it impossible to detect the rotation speed with high accuracy.

The present invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide a rotation sensor that can detect rotation speed with high accuracy.

In order to achieve the above-mentioned object, a rotation sensor according to the present invention has the following features.
A motor;
a conductor that rotates in response to rotation of a rotary shaft of the motor;
A wiring board having a detection unit mounted thereon for detecting an eddy current generated in the conductor due to the rotation of the conductor.
A rotation sensor comprising:
The motor further includes a first flange portion extending in a radial direction of the rotary shaft of the motor,
The conductor has a fitting recess into which the first flange portion is fitted.
It is a rotation sensor.

The present invention provides a rotation sensor that can detect rotation speed with high accuracy.

The present invention has been briefly described above. The details of the present invention will become clearer by reading the following description of the embodiment of the invention (hereinafter referred to as "embodiment") with reference to the attached drawings.

FIG. 1 is a schematic cross-sectional view showing an embodiment of a rotation sensor of the present invention. FIG. 2 is a circuit diagram showing details of a detection unit mounted on the wiring board shown in FIG. FIG. 3 is a top view of the target shown in FIG. FIG. 4 is a bottom view of the target shown in FIG.

Specific embodiments of the present invention are described below with reference to the drawings.

For the sake of convenience, "upper" and "lower" are defined as shown in FIG. 1. The upper and lower directions correspond to the "axial direction" of the present invention.

The rotation sensor 1 of this embodiment is a sensor that detects the rotation speed of a motor 2. As shown in FIG. 1, the rotation sensor 1 includes a motor 2, a target 3 as a conductor, a wiring board 4, and a reference component 5. The motor 2 is provided, for example, to drive the wheels of an automobile. The motor 2 has a cylindrical motor body 21 and a rotating shaft 22 that protrudes upward from the motor body 21. The rotating shaft 22 rotates around an axis that is in the vertical direction. In this embodiment, the motor body 21 of the motor 2 is mounted on a flat motor fixing component 6 that is perpendicular to the vertical direction.

The target 3 is made of a conductor such as metal, and rotates in response to the rotation of the rotating shaft 22 of the motor 2. Details of the target 3 will be described later. The wiring board 4 is provided in a flat plate shape, and is equipped with a detection unit 7 (see Figure 2) for detecting eddy currents generated in the target 3. As shown in Figure 2, the detection unit 7 has a coil pattern 71 printed on the wiring board 4, a current-carrying unit 72 that energizes the coil pattern 71, and a voltage detection unit 73 that detects the voltage across the coil pattern 71.

When the current supplying unit 72 applies current to the coil pattern 71, a magnetic field is generated in the coil pattern 71. When the target 3 is rotated, the magnetic field penetrating the target 3 changes, and an eddy current is generated in the target 3. The eddy current generated in the target 3 varies according to the rotation speed of the target 3. When an eddy current is generated in the target 3, an induced voltage is generated in the coil pattern 71 that cancels the magnetic field fluctuation caused by the eddy current. Therefore, the amount of change in the voltage across the coil pattern 71 detected by the voltage detection unit 73 corresponds to the eddy current, i.e., the rotation speed of the motor 2.

As shown in FIG. 1, the wiring board 4 is fixed to the underside of the reference component 5. The reference component 5 is disposed above the motor fixing component 6. At least a portion of the reference component 5 is flat and disposed vertically in the up-down direction.

The rotation sensor 1 further includes a first flange portion 8 that is attached to the tip of the rotating shaft 22 of the motor 2 and protrudes in the radial direction of the rotating shaft 22. In this embodiment, the first flange portion 8 protrudes in the radial direction of the rotating shaft 22 around the entire circumference of the rotating shaft 22. In this embodiment, an example will be described in which the first flange portion 8 is composed of two parts, a first part 81 and a second part 82. The first part 81 is provided with a press-in hole 83 into which the rotating shaft 22 is press-fitted. The upper end of the first part 81 is formed in a flange shape and protrudes in the radial direction.

The second part 82 has a recess 84 on its underside into which the upper end of the first part 81 is press-fitted. In this embodiment, the second part 82 is, for example, rectangular when viewed from above.

Next, the target 3 will be described in detail. In this embodiment, the target 3 is rotatably supported by the reference part 5 and is arranged to rotate in response to the rotation of the rotation shaft 22. The target 3 has a target body 31 as a conductive body in which eddy currents are generated, a convex portion 32 protruding upward from the target body 31, a shaft portion 33 protruding upward from the convex portion 32, a convex portion 34 protruding downward from the target body 31, and a fitting recess 35 provided on the underside of the convex portion 34.

In this embodiment, as shown in Figs. 3 and 4, the target body 31 has a central portion 311 and a plurality of wing portions 312 arranged around the central portion 311. The shape of the target body 31 is not limited to that shown in Figs. 3 and 4, and may be any shape that allows eddy currents to be generated. As shown in Fig. 3, the protrusion 32 protrudes upward from the central portion 311 of the target body 31. The protrusion 32 is arranged in a circular shape when viewed from above. As shown in Fig. 1, the shaft portion 33 protrudes coaxially with the rotation shaft 22. As shown in Fig. 3, the shaft portion 33 is also arranged in a circular shape when viewed from above.

As shown in FIG. 1, the reference part 5 has a through hole 51 through which the shaft part 33 of the target 3 passes. The shaft part 33 passes through this through hole 51, and is positioned so that its tip protrudes above the reference part 5.

As shown in FIG. 4, the protrusion 34 protrudes downward from the center 311 of the target body 31. The protrusion 34 is circular when viewed from below. The fitting recess 35 is rectangular when viewed from below so as to fit into the second part 82 of the first flange 8. As shown in FIG. 1, a gap S1 is provided between the target 3 and the first flange 8 in the radial direction, and a gap S2 is also provided in the vertical direction.

The rotation sensor 1 includes a second flange portion 9, a coil spring 10, and a bearing 11. The second flange portion 9 is attached to the tip protruding from the through hole 51 of the shaft portion 33, and is provided to protrude in the radial direction of the shaft portion 33. In this embodiment, the second flange portion 9 is composed of a well-known E-ring and washer. The E-ring fixes the washer to the tip of the shaft portion 33. The washer is provided in a ring shape, and is provided to protrude from the radial direction around the entire circumference of the shaft portion 33.

The coil spring 10 is provided between the second flange portion 9 and the reference component 5, and the shaft portion 33 is inserted. The coil spring 10 biases the second flange portion 9 so as to pull it upward. The above-mentioned convex portion 32 is provided with a diameter larger than the bottom opening of the through hole 51. Therefore, when the second flange portion 9 is pulled upward by the coil spring 10, the edge of the convex portion 32 comes into contact with the edge of the bottom opening of the through hole 51, biasing the target 3 against the bottom surface of the reference component 5.

The bearing 11 is a well-known bearing. In this embodiment, the bearing 11 is press-fitted into the through hole 51 and fixed. The shaft portion 33 of the target 3 is inserted into the bearing 11.

The wiring board 4 is fixed to the underside of the reference component 5. An insertion hole 41 is provided in the center into which the protrusion 32 of the target 3 is inserted, and the wing 312 and the wiring board 4 are arranged to face each other in the vertical direction.

According to the above-described embodiment, the first flange portion 8 attached to the tip of the rotating shaft 22 of the motor 2 is fitted into the fitting recess 35 of the target 3, so that the rotation of the rotating shaft 22 can be transmitted to the target 3. As a result, a gap S1 is generated between the first flange portion 8 and the fitting recess 35 of the target 3, so that the thrust play of the rotating shaft 22 is less likely to be transmitted to the target 3, and the rotation speed can be detected with high accuracy.

According to the embodiment described above, the target 3 is rotatably supported on the reference part 5, so that a gap S2 can be provided in the vertical direction between the first flange portion 8 and the target 3. This makes it even more difficult for thrust play of the rotating shaft 22 to be transmitted to the target 3, and allows the rotation speed to be detected with high accuracy.

According to the embodiment described above, the coil spring 10 biases the target 3 upward in the vertical direction, pressing it against the reference part 5, and the conductor 3 rotates while sliding against the reference part 5. This makes it possible to suppress fluctuations in the vertical position of the target 3 and fluctuations in the vertical distance between the target 3 and the wiring board 4. This makes it possible to detect the rotation speed with even greater accuracy.

According to the embodiment described above, the reference part 5 is provided with a through hole 51 through which the shaft portion 33 of the target 3 passes, and the coil spring 10 is provided between the second flange portion 9 and the reference part 5. This allows the target 3 to be biased in the vertical direction by the coil spring 10 and pressed against the reference part 5 with a simple configuration.

According to the embodiment described above, the rotation sensor 1 has a bearing 11 into which the shaft portion 33 of the target 3 is inserted and which is press-fitted into the through-hole 51 of the reference part 5. By providing the bearing 11, the target 3 can rotate more smoothly, and the rotation speed can be detected with even greater accuracy.

According to the embodiment described above, the protrusion 32 is provided so as to be in sliding contact with the periphery of the through hole 51 of the reference part 5. Since the sliding contact area between the target 3 and the reference part 5 can be reduced, the target 3 can be rotated more smoothly, and the rotation speed can be detected with even greater accuracy.

The present invention is not limited to the above-described embodiment, and can be modified, improved, etc. as appropriate. In addition, the material, shape, size, number, location, etc. of each component in the above-described embodiment are arbitrary as long as they can achieve the present invention, and are not limited.

In the above-described embodiment, the target 3 is supported by the reference part 5, but this is not limited to the above. The target 3 may be supported by the motor 2.

In the above-described embodiment, the target 3 is pressed against the reference component 5 by the coil spring 10, but this is not limited to this. The coil spring 10 is not essential and may be omitted.

In the above-described embodiment, the rotation sensor 1 is equipped with a bearing 11, but this is not limited to this. The bearing 11 is not essential and may be omitted.

In the above-described embodiment, the first flange portion 8 is composed of two parts provided separately from the rotating shaft 22, but this is not limited to the above. The first flange portion 8 may be composed of one part provided separately from the rotating shaft 22, or may be provided integrally with the rotating shaft 22.

In addition, in the above embodiment, the first flange portion 8 is provided in a rectangular shape when viewed from above, but this is not limited to this. The first flange portion 8 may have any shape as long as it can fit into the fitting recess 35 of the target 3 and transmit the rotation of the rotation shaft 22 to the target 3, and may be provided in a triangular shape, for example.

Here, the features of the embodiments of the rotation sensor according to the present invention described above will be briefly summarized and listed in the following [1] to [6].
[1]
A motor (2);
a conductor (3) that rotates in response to rotation of a rotating shaft (22) of the motor (2);
and a wiring board (4) on which a detection unit (7) is mounted for detecting an eddy current generated in the conductor (3) due to the rotation of the conductor (3).
A rotation sensor (1),
The rotary shaft (22) further includes a first flange portion (8) extending in a radial direction thereof,
The conductor (3) has a fitting recess (35) into which the first flange portion (8) is fitted.
Rotation sensor (1).

According to the configuration of [1] above, the first flange portion (8) fits into the fitting recess (35) of the conductor (3), and the rotation of the rotating shaft (22) can be transmitted to the conductor (3). In addition, since a gap (S1) is generated between the first flange portion (8) and the conductor (3), thrust play of the rotating shaft (22) is less likely to be transmitted to the conductor (3), and the rotation speed can be detected with high accuracy.

[2]
In the rotation sensor (1) according to [1],
A reference component (5) to which the wiring board (4) is fixed is provided;
The conductor (3) is rotatably supported on the reference part (5).
Rotation sensor (1).

According to the configuration of [2] above, the conductor (3) is rotatably supported on the reference part (5), so that a gap (S2) can be provided in the axial direction between the first flange portion (8) and the conductor (3). This makes it even more difficult for thrust play of the rotating shaft (22) to be transmitted to the conductor (3), allowing the rotation speed to be detected with high accuracy.

[3]
In the rotation sensor (1) according to [2],
The electric conductor (3) is further provided with a biasing member (10) that biases the electric conductor (3) in the axial direction (up and down direction) of the rotation shaft (22) to press the electric conductor (3) against the reference component (5),
The conductor (3) is provided so as to rotate while being in sliding contact with the reference part (5).
Rotation sensor (1).

According to the configuration of [3] above, the biasing member (10) biases the conductor (3) in the axial direction of the rotation shaft (22) to press it against the reference part (5). This makes it possible to suppress the conductor (3) from moving in the axial direction (up and down), and to detect the rotation speed with even greater accuracy.

[4]
In the rotation sensor (1) according to [3],
The conductor (3) has a shaft portion (33) provided coaxially with the rotation shaft (22),
The reference component (5) is provided with a through hole (51) through which the shaft portion (33) of the conductor (3) passes,
The shaft portion (33) further includes a second flange portion (9) provided at a portion of the shaft portion (33) protruding from the through hole (51) and extending radially outward from the shaft portion (33),
The biasing member (10) is provided between the second flange portion (9) and the reference component (5).
Rotation sensor (1).

According to the configuration of [4] above, with a simple configuration, the conductor (3) can be urged in the axial direction (up and down direction) of the rotation shaft (22) by the urging member (10) to press it against the reference part (5).

[5]
In the rotation sensor (1) according to [4],
The shaft portion (33) of the conductor (3) is inserted into a bearing (11) press-fitted into the through hole (51) of the reference component (5).
Rotation sensor (1).

According to the configuration of [5] above, by providing a bearing (11), the conductor (3) can be rotated more smoothly, and the rotation speed can be detected with even greater accuracy.

[6]
In the rotation sensor (1) according to [4],
The conductor (3) has a conductor body (31) in which the eddy current is generated, and a protrusion (32) protruding from the conductor body (31),
The shaft portion (33) is provided so as to protrude from the protruding portion (32),
The protrusion (32) is provided so as to be in sliding contact with the periphery of the through hole (51) of the reference component (5).
Rotation sensor (1).

According to the configuration of [6] above, the protrusion (32) is provided so as to slide around the through hole (51) of the reference part (5). This reduces the sliding area between the conductor (3) and the reference part (5), allowing the conductor (3) to rotate more smoothly and the rotation speed to be detected with even greater accuracy.

1 Rotation sensor 2 Motor 3 Conductor (target)
4 Wiring board 5 Reference component 7 Detection portion 8 First flange portion 9 Second flange portion 10 Coil spring (biasing member)
11 Bearing 22 Rotating shaft 31 Target body (conductor body)
32 Convex portion 33 Shaft portion 35 Fitting recess 51 Through hole

Claims (6)

A motor;
a conductor that rotates in response to rotation of a rotary shaft of the motor;
A wiring board having a detection unit mounted thereon for detecting an eddy current generated in the conductor due to the rotation of the conductor.
A rotation sensor comprising:
The motor further includes a first flange portion extending in a radial direction of the rotary shaft of the motor,
The conductor has a fitting recess into which the first flange portion is fitted.
Rotation sensor. 2. The rotation sensor according to claim 1,
a reference component to which the wiring board is fixed;
The conductor is rotatably supported on the reference component.
Rotation sensor. 3. The rotation sensor according to claim 2,
a biasing member that biases the conductor in the axial direction of the rotation shaft to press the conductor against the reference component;
The conductor is provided so as to rotate while being in sliding contact with the reference part.
Rotation sensor. 4. The rotation sensor according to claim 3,
the conductor has a shaft portion provided coaxially with the rotation shaft,
the reference component is provided with a through hole through which the shaft portion of the conductor passes,
A second flange portion is provided on a portion of the shaft portion protruding from the through hole and protruding in a radial direction of the shaft portion,
The biasing member is provided between the second flange portion and the reference component.
Rotation sensor. 5. The rotation sensor according to claim 4,
The shaft portion of the conductor is inserted into a bearing press-fitted into the through hole of the reference component.
Rotation sensor. 5. The rotation sensor according to claim 4,
The conductor has a conductor body in which the eddy current is generated and a protrusion protruding from the conductor body,
The shaft portion is provided so as to protrude from the protruding portion,
The protrusion is provided so as to be in sliding contact with the periphery of the through hole of the reference component.
Rotation sensor.

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