JP2006300599A - Rotation detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise a coil output voltage in a rotation detector. <P>SOLUTION: The rotation detector is provided with a stator 3 and an inductor 2. Protrusions 21 and recesses 22 are formed at regular intervals in the overall circumference of a circumferential surface of the inductor 2. The stator 30 is provided with a permanent magnet 30; a first yoke 31 joined to one pole on one side of the permanent magnet 30; and a second yoke 32 jointed to the other pole on the other end of the permanent magnet 30. The first yoke 31 and the second yoke 32 are each provided with magnetic poles 41-43 and 44-46 in such a way as to be opposed to the circumferential surface of the inductor 2 at the intervals of gaps g<SB>1</SB>-g<SB>6</SB>, and coils 51-56 are each fitted in the magnetic poles 41-46. The magnetic poles 41-43 of the first yoke 31 and the magnetic poles 44-46 of the second yoke 32 are symmetrically arranged, and coils (53 and 54, 52 and 55, and 51 and 56) of the symmetrically arranged magnetic poles are connected in parallel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a rotation detector that outputs an AC signal corresponding to a rotation speed in an industrial rotary machine.

This type of rotation detector is conventionally used for acquiring various control information such as a vehicle brake control device, a sliding detector for detecting idling and sliding, a monitor device such as navigation, a point detector, and a speedometer. It has been.

Patent Document 1 discloses a conventional rotation detector. In FIG. 1 of Patent Document 1, an inductor is coupled to a rotating body whose rotational speed is to be measured (for example, a motor shaft of a main motor that is a drive mechanism), and a convex portion and a concave portion are equidistant from this inductor. Are alternately provided over the entire circumference of the inductor.
A power generation unit is provided opposite to the outer periphery of the inductor, and the power generation unit includes a permanent magnet and magnetic pole pieces bonded to both sides thereof. Three magnetic poles are formed on each of the two magnetic pole pieces so as to face each other with a predetermined gap between the convex portion and the concave portion of the inductor. A coil having a predetermined number of turns is fitted to each magnetic pole.

When the inductor rotates in this configuration, the magnetic flux passes each time the convex portion of the inductor passes near the magnetic pole, and an induced electromotive force is generated in the corresponding coil. Accordingly, an AC signal having a frequency determined by the pitch of the convex portion and the rotational speed of the inductor is output from each coil.
Japanese Patent No. 3000787 (FIG. 1, 0007, 0008)

Here, in the rotation detector as described above, it is generally required that the output voltage of the coil be large in order to improve the accuracy and stability of the control system using the AC signal obtained from the rotation detector.

In order to meet such needs, for example, the gap between the inductor and the magnetic pole is reduced, and the magnetic resistance between the magnetic pole and the convex portion when the convex portion passes through the facing portion of the magnetic pole is reduced. It is conceivable to increase the output voltage of the coil. However, if the gap is set small, the risk of damage due to the contact between the convex portion and the magnetic pole increases. Further, the adjustment work for setting the gap to be a small distance and preventing the convex portion and the magnetic pole from coming into contact with each other becomes complicated.

Means and effects for solving the problems

The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

According to an aspect of the present invention, a rotation detector configured as follows is provided. A stator and an inductor are provided. On the circumferential surface of the inductor, irregularities are formed at equal intervals over the entire circumference. The stator includes a permanent magnet and a first magnetic pole piece joined to a pole on one side of the permanent magnet;
A second magnetic pole piece joined to the other pole of the permanent magnet. Said first pole piece and second
Each of the pole pieces is provided with a magnetic pole so as to face the concave and convex portions of the inductor with a gap. A coil is fitted to each of the magnetic poles. At least two of the plurality of coils provided are connected in parallel.

Thereby, the inductive reactance (reaction reactance) of the coil that hinders the flow of current can be reduced, and the output voltage from the coil can be increased. As a result, the stability and accuracy of control are improved on the device side that uses the signal. In particular, it is easy to increase the output voltage in the high-speed rotation region, and the configuration can be particularly suitable as a rotation detector when the inductor rotates at high speed. Further, since it is possible to increase the output voltage of the coil without reducing the gap between the magnetic pole and the inductor, it is possible to reduce manufacturing costs and adjustment efforts.

◆ In the rotation detector, the coils connected in parallel have the same phase or 180
The position of the magnetic pole corresponding to the coil is preferably set so that signals with different phases are output.

As a result, the coils need only be simply connected in parallel or connected in parallel in the opposite direction, which simplifies wiring and reduces manufacturing costs.

The above rotation detector is preferably configured as follows. The first magnetic pole piece and the second magnetic pole piece include a plurality of magnetic poles, and each magnetic pole of one magnetic pole piece is
The magnetic poles of the other magnetic pole piece are provided at positions that are symmetrical with respect to the permanent magnet. The coils corresponding to the magnetic poles of the first magnetic pole piece and the second magnetic pole piece at symmetrical positions are connected in parallel.

In this configuration, even when the stator is translated in order to adjust the gap, the amount of change in the gap of the magnetic pole at the symmetrical position is equal to each other, so that it is easy to equalize the output voltages of the coils connected in parallel. Stable signal output can be obtained.

Next, embodiments of the invention will be described. FIG. 1 is a cross-sectional view showing the overall configuration of a rotation detector according to an embodiment of the present invention, FIG. 2 is a schematic view showing a state in which the rotation detector is attached, and FIG. FIG. 4 is a view showing the positional relationship between the magnetic poles, and FIG. 5 is a wiring diagram of the coils.

As shown in FIG. 2, the rotation detector 1 as an embodiment of the present invention is provided at one end of a rotating shaft 61 that is rotatably supported by a bearing (not shown). Specifically, one end of the rotating shaft 61 is inserted into the shaft box 62, and the gear 2 is fixed to that portion.

Next, the structure of the rotation detector 1 will be described with reference to FIG. 1, FIG. 3, and FIG. A rotation detector 1 according to the first embodiment shown in FIG. 1 includes an inductor (the gear) 2 that is rotatably provided, and the inductor 2.
And the stator 3 attached to the axle box 62 (FIG. 2) so as to face the outer periphery of the main body.

The inductor 2 is fixed to the rotating shaft 61 as described above, and rotates integrally with the rotating shaft 61. And as shown in FIG. 1, the convex part 21 and the recessed part 22 are alternately arrange | positioned at equal intervals on the outer periphery of the inductor 2 over the perimeter.

The stator 3 is provided with a permanent magnet 30 so that its magnetic axis is along the circumferential direction of the inductor 2, and a first yoke (first magnetic pole piece) 31 is provided on the N pole of the permanent magnet 30. , S pole is second
The yokes (second magnetic pole pieces) 32 are joined. As the yokes 31 and 32, for example, those made of pure iron can be adopted. From the first yoke 31, the first magnetic pole 41 and the second magnetic pole 42 are
A third magnetic pole 43 and a fourth magnetic pole 44 protrude from the second yoke 32 toward the inductor 2 side. The tip surfaces of the magnetic poles 41 to 44 have a predetermined gap with respect to the outer peripheral edge of the inductor 2 (FIG. 1).
And facing each other with a gap g) shown in FIG. The size of the gap g is, for example, 0.
It is considered to be 5 to 2.0 millimeters.

In FIG. 1, the first to fourth coils 51 having a predetermined number of turns are provided on the first to fourth magnetic poles 41 to 44.
-54 are respectively fitted so that the outputs of these coils 51-54 can be taken out via the cable 55. The permanent magnet 30, the yokes 31 and 32, and the coils 51 to 54 are covered with a housing 33 and a mold cover 34, and the interior is filled with a molding material such as polyurethane rubber. The tips of the magnetic poles 41 to 44 penetrate through the mold cover 34 and are exposed.

In the above configuration, when the inductor 2 rotates in the direction of the thick arrow in FIG. 1 as the rotating shaft 61 rotates, the coils 51 described above correspond to the pitch and dimensions of the convex portions 21 provided on the inductor 2. ~
54, the magnetic flux passes each time the convex portion 21 passes the facing positions of the corresponding magnetic poles 41 to 44, and an electromotive force is generated. Therefore, from each coil 51-54, the convex part 2 provided in the inductor 2 is demonstrated.
An AC signal having a frequency determined by the pitch p of 1 and the rotational speed of the inductor 2 (the rotational speed of the rotating shaft 61) can be obtained. In addition, the space | interval in which the convex part 21 is provided is hereafter called "convex part pitch."

As shown in FIG. 4, the first magnetic pole 41 and the second magnetic pole 42 provided adjacent to each other in the first yoke 31 on one side of the permanent magnet 30 have the first coil 51 of the first magnetic pole 41. When the output AC signal is used as a reference of the AC signal, the convex pitch p is set so that the output AC signal of the second coil 52 of the second magnetic pole 42 is generated with a 180 ° delay or a leading phase with respect to the reference. Therefore, the distance between the first magnetic pole 41 and the second magnetic pole 42 is set.

Further, in the third magnetic pole 43 of the second yoke 32 on the other side, the convex portion pitch p of the inductor 2 is generated so that the output AC signal of the third coil 53 fitted to the third magnetic pole 43 is generated with a phase equal to the reference.
Therefore, the distance between the first magnetic pole 41 and the third magnetic pole 43 is set. Further, in the fourth magnetic pole 44, the first magnetic pole is related to the convex pitch p so that the output AC signal of the fourth coil 54 fitted to the fourth magnetic pole 44 is generated with a 90 ° delay or advance phase from the reference. 41 and fourth magnetic pole 44
And set the distance. The output of the third coil 53 is 9 with respect to the fourth coil 54.
The same is true for a phase delayed by 0 °.

In this embodiment, as shown in FIG. 5, the first coil 51 and the third coil 53 are connected in parallel,
Furthermore, by connecting the second coil 52 in parallel in the opposite direction to form a coil set, an AC signal as the reference can be obtained from the coil set. On the other hand, the AC signal obtained from the fourth coil 54 has a phase delay of 90 ° with respect to the reference.

That is, when the inductor 2 rotates in the direction of the thick arrow in FIG.
An output signal as a reference phase is output from a coil set in which 53 is connected in parallel, an output signal delayed by 90 ° from the reference phase is output from the fourth coil 54, and the convex portion 21 of the inductor 2 is connected to each magnetic pole 41.
Will be output in a cycle passing through .about.44.

In the present embodiment, as described above, the coils 51 to 5 fitted to the four magnetic poles 41 to 44 are used.
4, the first to third coils 51 to 53 are connected in parallel. As a result, the inductive reactance (reaction reactance) of the coil that hinders the flow of current can be reduced, and the output voltage from the coils 51 to 53 can be increased. This improves the accuracy and stability of control on the side of the control device that takes out and uses the signals of the coils 51 to 53 through the cable 55. Alternatively, since the room for increasing the gap (gap g in FIGS. 1 and 3) is increased by the contribution of the increase in output voltage, assembly is facilitated and the manufacturing cost can be reduced.

Here, in general, the reactance increases in proportion to the frequency of the AC signal. In this respect, in the present embodiment, since the reactance can be reduced inherently by the parallel connection of the coils 51 to 53, a large output voltage can be obtained even if the frequency is increased. That is, even when the rotary shaft 61 rotates at a high speed, a sufficient output voltage can be obtained, which is suitable for detecting rotation in a high rotation range.

In the present embodiment, since the three coils 51 to 53 are connected in parallel, the magnitude of the reaction reactance can be reduced to one-third that when a signal is extracted from a single coil.
However, for example, only two coils of the first coil 51 and the second coil 52 or only two coils of the first coil 51 and the third coil 53 may be connected in parallel.
In this case, the reaction reactance can be halved.

FIG. 6 shows a second embodiment. In the second embodiment, three magnetic poles are formed in each of the yokes 31 and 32, and a total of six magnetic poles 41 to 46 are provided as a whole. Gaps g _{1 to} g ₆ are formed between the magnetic poles 41 to 46 and the peripheral surface of the inductor 2. Also, the six magnetic poles 41
Coils 51 to 56 are fitted to each of .about.46.

A third magnetic pole 43 formed on the first yoke 31 and a fourth magnetic pole 4 formed on the second yoke 32.
4 are arranged at positions symmetrical to each other across the permanent magnet 30. In detail,
When the virtual plane Q including the center of the permanent magnet 30 and the rotation axis of the inductor 2 is considered, both the magnetic poles 43 and 44 sandwich the virtual plane Q so that the distance from the virtual plane Q is equal. Are arranged on opposite sides of each other. The lengths of the magnetic poles 43 and 44 are equal to each other. Similarly, the second magnetic pole 42 and the fifth magnetic pole 45, and the first magnetic pole 41 and the sixth magnetic pole 46 are arranged symmetrically with respect to the permanent magnet 30.

As shown in FIG. 7 as a wiring diagram, coils (53 and 54, 52 and 55, 51 and 56) corresponding to the above-described three magnetic pole sets arranged symmetrically with each other are connected in parallel. Note that the magnetic pole pairs (43 and 44, 42 and 45, 41 and 46) corresponding to the coil sets connected in parallel have the same positional relationship or 180 ° different phases, and the positional relationship thereof is the convex pitch p. It is necessary to set in relation to.

In addition to the above-described reactance reduction effect, the second embodiment also has the following effects. That is, when adjusting the gaps g _{1 to} g ₆ between the magnetic poles 41 to 46 of the rotation detector 1 and the inductor 2, it is necessary to make the entire stator 3 close to or away from the inductor 2. is there.
That is, the gaps g ₁ to g ₆ cannot be individually adjusted for the _six magnetic poles 41 to 46,
All six can only be moved close to or away from the inductor 2 at the same time.

Accordingly, it is necessary to adjust the gaps g ₁ to g ₆ by moving the stator 3 in the direction of the white arrow in FIG. 6, but the gaps g ₁ to g of the three magnetic poles 41 to 43 of the first yoke 31 are not limited. Since the directions of g ₃ are different from each other, the amount of change in each gap (Δg _{1 to} Δg ₃ ) when the stator 3 is moved in the direction by the unit amount is different from each other. Similarly, in the second yoke 32, the stator 3
Of the gaps of each of the three magnetic poles 44 to 46 (Δg
_{4 to} Δg ₆ ) are different from each other.

On the other hand, since the magnetic poles are arranged symmetrically in the second embodiment, the amount of gap change between the symmetrically arranged magnetic poles is equal (Δg ₃ = Δg ₄ , Δg ₂ = Δg ₅ , Δg ₁ = Δg ₆ ). this is,
This means that the amount of change in magnetic path resistance is the same between the symmetric magnetic poles, so that it is easy to equalize the output voltages of the coil groups (53 and 54, 52 and 55, 51 and 56) connected in parallel. Become. This means that a backflow of current to the coil can be prevented and a stable signal output can be obtained.

Note that the parallel connection of the coils of the symmetrically arranged magnetic poles as described above is not limited to the configuration of the six magnetic poles as shown in FIG. 6 but can be applied to a configuration of four magnetic poles (the first embodiment). Of course.

Furthermore, in the above-described embodiment, the following configuration may be adopted. FIG. 8 shows a modification and corresponds to FIG. That is, in the configuration of FIG. 8, the outer diameters of the coils 51 and 52 fitted to the magnetic poles 41 and 42 are increased by increasing the thickness of the permanent magnet 30 and the thickness of the base portion of the yoke 31 as compared with the case of FIG. The thickness L of the base portions of the permanent magnet 30 and the yoke 31 is substantially equal. As a result, a large output signal can be obtained without enlarging the stator 3 so much. Or the thickness L of the base part of the permanent magnet 30 or the yoke 31 may be less than the winding outer diameter of the coils 51 and 52.

Further, in order to increase the output while maintaining the compactness of the stator 3, the configuration shown in FIG. 9 can be adopted. In FIG. 9, the yoke 31 forming the magnetic poles 41 and 42 is made of a silicon steel plate or the like. As a result, the eddy current that prevents the generation of magnetic flux can be reduced, and the coil 51
-The output voltage of 52 can be increased. The yoke 31 has a base having a thickness of the magnetic pole 41.
The thickness L of the permanent magnet 30 is substantially equal to the winding outer diameter of the coils 51 and 52 fitted to the magnetic poles 41 and 42. That is, the thickness L of the permanent magnet 30 is larger than the thickness of the yoke 31. As a result, the entire stator 3 is not increased in size so much that the sectional area of the permanent magnet 30 is increased to increase the amount of magnetic flux passing through the magnetic circuit. However, the thickness L of the permanent magnet 30 may be equal to the thickness of the yoke 31.

In the configuration of FIG. 9, for example, iron reinforcing plates 58.
58 is joined to increase the amount of magnetic flux from the permanent magnet 30 by increasing the magnetic path. In addition,
The dimension obtained by adding the thickness of the two reinforcing plates 58 and 58 to the thickness of the base portion of the yoke 31 is the permanent magnet 30.
The thickness L of the coil 51 and the winding outer diameter of the coils 51 and 52 are substantially equal. Thereby, the output voltage of the coils 51 and 52 can be increased while effectively suppressing the increase in size of the stator 3.

The embodiments and modifications described above can be implemented with various modifications. For example, the number of magnetic poles may be any number, and it is only necessary that coils fitted to at least two of the magnetic poles are connected in parallel.

In addition, in the two magnetic poles corresponding to the coils connected in parallel, it is sufficient if the output phases of the coils are different from each other by 180 ° (or the same phase is sufficient). Neither need be equal to the reference phase. In addition, the position of the other magnetic poles is arbitrary, considering the phase of the required signal, how to connect the coils, the specifications and applications of the rotation detector, etc. Set it.

Also, not only when the coils are simply connected in parallel, but for example when there are three coils,
Two coils may be connected in parallel, and the remaining one may be connected in series.

Further, it is not always necessary to provide one stator 3. For example, when multiple outputs are required and there is a sufficient mounting space, a plurality of stators 3 are provided for one inductor 2. May be. Furthermore, the direction of the permanent magnet 30 may be opposite, and the S pole may be joined to the first yoke 31 and the N pole may be joined to the second yoke 32.

Further, the above embodiment is an example of the rotation detector of the rotating shaft. However, the present invention is not limited to this. For example, the speed of various rotating bodies such as a rotating speed sensor and a motor shaft of an electric motor is detected. In addition, the rotation detector of the present invention can be applied.

Sectional drawing which showed the whole structure of the rotation detector which concerns on 1st Embodiment of this invention. The schematic diagram which shows a mode that a rotation detector is attached. FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1. The figure which shows the positional relationship of each magnetic pole. The wiring diagram of the coil of a rotation detector. Sectional drawing of the rotation detector of 2nd Embodiment. The wiring diagram of the coil in 2nd Embodiment. The figure which shows the modification of a structure of a stator. The figure which shows another modification of a structure of a stator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotation detector 2 Inductor 3 Stator 21 Convex part 22 Concave part 30 Permanent magnet 31 1st yoke (1st pole piece)
32 Second yoke (second pole piece)
41-44 magnetic pole 51-54 coil

Claims (3)

A stator and an inductor,
On the peripheral surface of the inductor, irregularities are formed at equal intervals over the entire circumference.
The stator is
With permanent magnets,
A first pole piece joined to a pole on one side of the permanent magnet;
A second pole piece joined to the other pole of the permanent magnet;
With
Each of the first magnetic pole piece and the second magnetic pole piece is provided with a magnetic pole so as to face the unevenness of the inductor with a gap therebetween,
A coil is fitted to each of the magnetic poles,
A rotation detector, wherein at least two of the plurality of coils are connected in parallel. The rotation detector according to claim 1,
A rotation detector, wherein the positions of magnetic poles corresponding to the coils are set so that the coils connected in parallel output signals having the same phase or different phases by 180 °. The rotation detector according to claim 1 or 2,
The first magnetic pole piece and the second magnetic pole piece have a plurality of magnetic poles, and the magnetic poles of one magnetic pole piece are provided at positions symmetrical with respect to the magnetic poles of the other magnetic pole piece and the permanent magnet. And
The rotation detector according to claim 1, wherein the coils corresponding to the magnetic poles of the first magnetic pole piece and the second magnetic pole piece at symmetrical positions are connected in parallel.

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