JP2002357494A - Rotation sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation sensor in which parameters to give effects to the impedance of excitation coils can be set plane-symmetric, and in which a lead wire led out of the excitation coil can be set the shortest. SOLUTION: This rotation sensor is provided with a first rotor 11 having a first conductive layer 11c and to be installed on a first shaft, a fixed core having two excitation coils 12c, and core main bodies 12a and 12b for respectively containing the excitation coils, that is installed on a fixed member, and a second rotor 13 having a main body 13a molded in a cylindrical form, and a second conductive layer 13b, that is installed on a second shaft which makes relative rotation to the first shaft. The rotation angles of both shafts or a relative rotation angle between them are contactlessly detected based on fluctuation of inductance of the excitation coils 12c in accordance with rotation of the first and the second rotors. The fixed core 12 has cases 12e and 12f covering the core main bodies 12a and 12b, and having lead-out parts 12j for leading out the lead wires 12h of the excitation coils 12c, and an intermediate member 12d disposed between both cases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a rotation sensor.

[0002]

2. Description of the Related Art As a rotation sensor for detecting a torque between two relatively rotating shafts having two rotating bodies (rotor) and a fixed body having an exciting coil, for example, a relative rotation is provided via a torsion bar. 2. Description of the Related Art There is known a rotation sensor that detects a torque on a handle shaft of an automobile to which two rotating shafts are connected and uses the torque for smooth electronic control of a steering device.

In such a rotation sensor, detection accuracy fluctuates due to disturbances such as environmental temperature fluctuations, electromagnetic noise, fluctuations in the oscillating frequency of the oscillating circuit, power supply voltage and assembly errors, and the torque can be accurately detected. In order to avoid this, the above-mentioned disturbance is canceled by using two excitation coils. By the way, when the rotation sensor is used for a moving body such as an automobile,
Electromagnetic compatibility (EMC) to prevent the effects of electromagnetic waves between in-vehicle devices
Strict standards have been established. Specifically, electromagnetic interference that does not emit electromagnetic waves to the outside of the rotation sensor (EMI: elec
There are two standards: tro-magnetic interference) and electromagnetic susceptibility to external electromagnetic waves (EMS: electro-magnetic susceptibility).

For this reason, in the rotation sensor, a core main body accommodating an exciting coil is accommodated in a case. In this case, as the material of the case, a conductive material such as a metal such as aluminum is used in consideration of strength and an electromagnetic shielding effect. A fixed case using such a case is, for example,
As in the fixed case 1 shown in FIG. 4, two core bodies 1a accommodating the excitation coil 1b are combined with a cylindrical body 1d and a lid 1e.
Is assembled via a spacer 1f made of a conductive material (for example, aluminum). In this case, the spacer 1f is used to arrange the two exciting coils 1b so as to be symmetrical in shape and electromagnetically with respect to the spacer 1f, and to appropriately cancel the disturbance.

[0005]

Incidentally, in the above fixed case, the case is manufactured by a die casting method from the viewpoint of mass production. In this case, since the main body 1d is cylindrical, a cutting allowance (pulling taper) for die cutting is required. If there is such an allowance, the molded case 1c is separated from the core body 1a by a gap C as shown in the figure.
Occurs. The (three-dimensional) size of the gap C is such that the two core bodies 1a and the spacer 1f are accommodated in the body 1d and the lid 1e
Of the accuracy when assembling with
And the lid 1e depending on the magnitude of the fixing force.

Theoretically, the magnitude and direction of the vector of the eddy current induced in the core body 1a and the inner surface of the portion of the body 1d accommodating the core body 1a differ depending on the size of the gap C. Fluctuates. In order to solve this, it is effective means to increase the mutual compensation effect by making the gap C between the two core bodies 1a and 1d the same.

However, in the conventional rotation sensor, it is very difficult to increase the plane symmetry of the gap C by making the gap C between the two core bodies 1a and 1d the same. Further, the gap C is also affected by the fixing force between the main body 1d and the lid 1e, and varies depending on the size thereof. Moreover, in order to lead the lead wires (not shown) of the two exciting coils 1b to the outside while minimizing ambient noise as much as possible, the fixed case 1 has a small inductance, that is,
It had to be as short as possible.

The present invention has been made in view of the above points, and has effects on not only the two core bodies but also the impedance of the exciting coil, such as the effective relative permeability around the exciting coil and the gap between the core body and the case. It is another object of the present invention to provide a rotation sensor including a fixed case capable of giving each parameter a plane symmetry and minimizing a lead wire led out of the excitation coil.

[0009]

According to the present invention, in order to achieve the above object, a first rotor having a first conductor layer arranged in a circumferential direction and attached to a first shaft,
The apparatus has two exciting coils arranged at a predetermined interval in the rotation axis direction of the first rotor, and a core body that individually accommodates the exciting coils, and is spaced apart from the first rotor in a radial direction. Fixed core attached to the fixing member by placing
A main body formed into a cylindrical shape from an insulating magnetic material; and a second conductor layer disposed on the main body in two stages. The first conductor is spaced apart from the first rotor by a predetermined distance in the radial direction. A second rotor attached to a second shaft that rotates relative to the other shaft, based on a change in inductance of the exciting coil accompanying rotation of the first and second rotors,
In a rotation sensor that detects the rotation angle or the relative rotation angle of the two shafts in a non-contact manner, the fixed core covers the two core bodies, respectively, and has a lead portion for leading a lead wire of the excitation coil. The structure includes a case made of a conductive material and an intermediate member made of a conductive material disposed between the two cases.

Preferably, the two cases are fixed to the intermediate member and accommodate the two core bodies.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the rotation sensor according to the present invention, for example, a rotation sensor for detecting torque of a steering shaft transmitted from a driving shaft to a driven shaft via a torsion bar in an automobile will be described. This will be described in detail with reference to FIGS.

As shown in FIG. 1, the rotation sensor 10 includes a first rotor 11, a fixed core 12, and a second rotor 13, and a high-frequency AC current flows through two exciting coils 12b of the fixed core 12, which will be described later. 1 rotor 11 and 2nd rotor 1
3 is used to detect a torque based on the relative rotation angle. Here, although not shown, the steering shaft has a driving shaft on the steering wheel side connected to a driven shaft on the wheel side via a torsion bar, and the driving shaft is ±
Relative rotation within a range of 8 °.

The first rotor 11 is disposed between the second rotor 13 and the fixed core 12, and is attached to the driving shaft. The first rotor 11 is formed of a synthetic resin having electrical insulation properties and excellent moldability by uniformly arranging a plurality of blades 11b parallel to the rotation axis Art on the outer periphery of the flange 11a. Each wing plate 11b is formed at an interval corresponding to each copper foil 13a described later, and a copper foil 11c is provided on the outer surface.

At this time, the first rotor 11 is
A conductor layer having a certain thickness (for example, a copper foil of 0.2 mm, or a material of aluminum, silver, or the like) is applied to the copper foil 13a on the inner surface or the inner surface of the cylindrical body made of an insulating material. They may be arranged evenly in correspondence. The fixed core 12 is arranged with a slight gap of about several mm in the radial direction from the first rotor 11, and is fixed to a fixed member (not shown) located near the steering shaft. Fixed core 12
As shown in FIG. 1, core bodies 12a and 12b accommodating an exciting coil 12c, a spacer 12d, an upper case 12
e, a lower case 12f and a side case 12g, which are assembled by fixing them with screws or rivets.

The core bodies 12a and 12b are made of Ni--Zn, Mn--Zn, Mg--Z
Sintered body obtained by sintering n-based ferrite, nylon, polypropylene (PP), polyphenylene sulfide (PP
S) An insulating magnetic material obtained by mixing a soft magnetic material powder of Ni-Zn or Mn-Zn based ferrite with a soft magnetic material of 10 to 70% by volume in an electrically insulating thermoplastic synthetic resin such as an ABS resin. From the shape of a ring.

Each of the exciting coils 12c has a core body 12a,
A lead wire 12h extends from 12b to the outside, is connected to a signal processing circuit described later, and an alternating current flows from the signal processing circuit. As shown in FIG. 2, the spacer 12d is disposed between the upper case 12e and the lower case 12f such that the upper case 12e and the lower case 12f are plane-symmetric with respect to the spacer 12d. This is a disk-shaped intermediate member made of a conductive material such as silver.

The cases 12e, 12f and 12g are formed of a conductive material having a shielding property against an alternating magnetic field, for example, a metal such as aluminum or copper or a synthetic resin containing carbon. The upper case 12e and the lower case 12f
Each of the cores 12a and 12b is covered with a ring and is formed in a ring shape, and a groove-shaped lead-out portion 12j for leading out the lead wire 12h is formed on a side portion. The upper case 12e and the lower case 12f are manufactured by a die casting method, and a gap C is formed between the core bodies 12a and 12b as shown in FIG.

Here, the upper case 12e and the core body 12a
And the gap C formed between the lower case 12f and the core main body 12b is due to the allowance (detach taper) at the time of manufacture, and is vertically symmetrical with respect to the spacer 12d. , Exaggerated from the actual gap. Also, a plurality of insertion holes into which screws are inserted into one of the upper case 12e and the lower case 12f and the spacer 12d, and a plurality of tap holes in the other case are provided, and as shown in FIG. Case 12e and lower case 12f
Are arranged while securing plane symmetry via the spacer 12d,
Each hole is fixed with one screw, for example. In this case, since one screw serves as a common fixing member for the upper case 12e and the lower case 12f, the fixing force between the upper case 12e and the spacer 12d, and the lower case 12f and the spacer 12d
And the fixing relationship with the fixing force can be made substantially the same.

The side case 12g is screwed to the side of the upper case 12e and the lower case 12f, and a substrate 12k having a signal processing circuit formed on the lower surface is attached to the lower part. The second rotor 13 is attached to a predetermined position in the axial direction of the driven shaft that rotates relatively to the driven shaft. As shown in FIG. 1, the second rotor 13 has a main body 13a formed of the same insulating magnetic material as the fixed core 12 in a cylindrical shape, and a lower rotor 13c. While being arranged in two stages in the direction,
A plurality of copper foils 13b are provided at predetermined intervals in the circumferential direction, for example, at an interval of 30 ° at a central angle by alternately shifting the positions vertically. Here, the second rotor 13 can be made of a material such as aluminum or silver instead of the copper foil 13b as long as it is a conductor layer. These conductor layers including the copper foil 13b are made of an insulating magnetic material. It may be embedded inside.

The rotation sensor 10 configured as described above
Attaches a first rotor 11 to the driving shaft and a second rotor 13 to the driven shaft, and fixes the fixed core 12 to the fixing member. As shown in FIG. , The lower cover 15 at the bottom,
Installed and assembled to the steering device. The rotation sensor 10 detects the torque of the steering shaft transmitted from the driving shaft to the driven shaft via the torsion bar by operating the steering handle.
On the basis of the relative rotation angle between the first rotor 11 and the second rotor 13, based on the relationship between a previously determined torque acting between the driving shaft and the driven shaft and the relative rotation angle between both shafts. You can ask.

At this time, the rotation sensor 10 is
An upper case 12e and a lower case 12f that respectively cover the lead wires 12a and 12b and that lead out the lead wire 12h of the exciting coil 12c;
fixed core 1 having a spacer 12d disposed between
2 is used. The upper case 12e and the lower case 12f are arranged via a spacer 12d so as to be vertically symmetrical, and a gap C formed between the upper case 12e and the lower case 12f and the core bodies 12a and 12b is formed. ,
It is vertically symmetric with respect to the spacer 12d. Moreover, in the fixed core 12, the lead wires 12h of the two exciting coils 12c are led out from the lead-out portions 12j of the upper case 12e and the lower case 12f.

Therefore, the rotation sensor 10 can arrange the two exciting coils 12c in plane symmetry, and can minimize the lead wire 12h led out of the exciting coil 12c. Here, the rotation sensor 10 in FIG.
Although an example of measuring the relative rotation within the range of ± 8 ° between the two shafts has been described, if the rotation sensor is configured as shown in FIG. 3, the relative rotation within the range of ± 90 ° is measured. be able to. That is, the rotation angle or the relative rotation angle of the shafts SF1, SF2 can be detected in a non-contact manner based on the inductance variation of the exciting coil accompanying the rotation of the first and second rotors.

Here, the rotation sensor 20 described below has the same configuration as the rotation sensor 10 except that the configuration of the first rotor 21 and the second rotor 23 is slightly different from that of the rotation sensor 10. Therefore, in the following description and FIG. 3, the rotation sensor 20 uses the same reference numerals for the fixed core 12, the upper cover 14, and the lower cover 15 to omit redundant description, and omit the first rotor 21 and the second rotor 21.
The rotor 23 will be described.

The first rotor 21 is disposed between the second rotor 23 and the fixed core 12, similarly to the first rotor 11,
Attached to the driving shaft. First rotor 21
As shown in FIG. 3, a blade 21b parallel to the rotation axis Art is formed on the outer periphery of the flange 21a over a half circumference in the circumferential direction using the same synthetic resin as the first rotor 11.
The copper foil 21c is provided on the outer surface of the wing plate 21b.

At this time, similarly to the first rotor 11, the first rotor 21 has a conductor layer (for example, a fixed thickness) on the inner surface of the blade 21b or the inner surface or inside of the cylindrical body made of an insulating material. (A copper foil of 0.2 mm or of a material such as aluminum or silver) may be arranged corresponding to the copper foil 23a. Similarly to the second rotor 13, the second rotor 23 is attached to a predetermined position in the axial direction of the driven shaft that rotates relatively to the main driving shaft. The second rotor 23 has a main body 23a formed of the same insulating magnetic material as the fixed core 12 in a cylindrical shape, and a lower rotor 23c. Body 2
3a is, as shown in FIG.
Copper foil 23 arranged in a row and shifted vertically
b is provided over a half circumference along the circumferential direction. Here, for the second rotor 23, similarly to the second rotor 13, a material such as aluminum or silver can be used instead of the copper foil 23b, and these conductor layers including the copper foil 23b are formed of a main body 23a. It may be embedded inside.

Although each of the above embodiments has been described with reference to the case of a rotation sensor for detecting torque, it is also possible to detect a rotation angle. Further, the rotation sensor of the present invention may be a sensor for determining a relative rotation angle, a rotation angle, and a torque between rotating shafts rotating with each other, such as a robot arm, in addition to the steering shaft of the automobile described in the above embodiment. It can be used for anything.

[0027]

According to the first and second aspects of the present invention, the impedance of the exciting coil is affected not only by the two core bodies but also by the effective relative permeability around the exciting coil and the gap between the core body and the case. It is also possible to provide a rotation sensor including a fixed case that can make each parameter plane-symmetric and minimize the length of a lead wire led out of the excitation coil.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a rotation sensor of the present invention.

FIG. 2 is a sectional view of a fixed case used in the rotation sensor of FIG.

FIG. 3 is an exploded perspective view showing another embodiment of the rotation sensor of the present invention.

FIG. 4 is a cross-sectional view of a fixed case used in a conventional rotation sensor.

[Explanation of symbols]

 Reference Signs List 10 rotation sensor 11 first rotor 11a flange 11b blade 11c copper foil (first conductor layer) 12 fixed core 12a, 12b core body 12c excitation coil 12d spacer (intermediate member) 12e upper case 12f lower case 12g side case 12h lead Line 12j Derivation unit 12k Substrate 13 Second rotor 13a Main body 13b Copper foil (second conductor layer) 13c Lower rotor 14 Upper cover 15 Lower cover 20 Rotation sensor 21 Flange 21b Blade 21c Copper foil (first conductor layer) 23 Second rotor 23a Main body 23b Copper foil (second conductor layer) 23c Lower rotor Art Rotation axis

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Nakamoto 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Inventor Kengo Tanaka 2-6-1 Marunouchi, Chiyoda-ku, Tokyo No. Furukawa Electric Co., Ltd. (72) Inventor Kazuhiko Matsuzaki 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Masakazu Matsui 2-6-1 Marunouchi, Chiyoda-ku, Tokyo No. Furukawa Electric Co., Ltd. (72) Inventor Kosuke Yamawaki 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Tomotaka Watanabe 2-6-1 Marunouchi, Chiyoda-ku, Tokyo No. Furukawa Electric Co., Ltd. (72) Inventor Masahiro Hasegawa 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. F Term (reference) 2F063 AA35 AA36 BA08 BA22 CA08 DA01 GA08 GA34 KA01 2F077 AA21 CC02 FF03 FF13 FF31 VV02 VV11 WW03

Claims (2)

[Claims] 1. A first rotor having a first conductor layer arranged in a circumferential direction, attached to a first shaft, and arranged at a predetermined interval in a rotation axis direction of the first rotor. A fixed core that has two excitation coils and a core body that individually accommodates the excitation coils, and is attached to a fixed member at a radial distance from the first rotor; A main body to be molded; and a second conductor layer disposed on the main body in two stages. The main body is rotated relative to the first shaft at a predetermined radial distance from the first rotor. A second rotor attached to a second shaft, wherein a rotation angle or a relative rotation angle of the two shafts is non-contact based on an inductance change of the excitation coil accompanying rotation of the first and second rotors. Rotation sensor detected by In the fixed core, the two core bodies respectively cover the two core bodies,
A rotation sensor, comprising: a case made of a conductive material having a lead-out portion for leading a lead wire of the exciting coil; and an intermediate member made of a conductive material disposed between the two cases. 2. The rotation sensor according to claim 1, wherein the two cases are fixed to the intermediate member and house the two core bodies.