JP6077486B2 - Rotary contactless power supply transformer - Google Patents

Description

  The present invention relates to an improvement in the structure of a transformer for supplying electric power to a circuit placed on a rotating body in order to detect various physical quantities of the rotating body in a machine.

  When detecting various physical quantities of a rotating body, there is an obstacle in that it cannot be wired directly to a detector or a circuit placed on the rotating body side from the fixed side. A known method for supplying electric power to a rotating body includes a slip ring mechanism. However, the slip ring mechanism needs to be precisely processed and assembled in order to maintain good mechanical contact between the brush and the slip ring over a long period of time. It was. In addition to preventing leakage from slip rings and brushes, the brushes wear out, requiring regular replacement and maintenance of parts. Furthermore, since dust is generated during wear, suction and cleaning inside the casing are also necessary.

  On the other hand, an AC conversion circuit is required for a rotary contactless power supply transformer because it uses electromagnetic induction, but since it is noncontact, contact failure does not occur, insulation is easy, and maintenance is not required. Is progressing.

  When the primary side transformer is attached to the outer peripheral fixed side of the rotating shaft, the primary side core is configured to cover the rotating shaft, the secondary side core, and the secondary side coil all around. There was a problem of increasing. In particular, when the diameter of the rotating shaft is increased, the diameter of the secondary core is increased accordingly, and the outer diameter of the primary core is also increased, which is a factor in increasing the size of the device and increasing the manufacturing cost. It was.

  On the other hand, a primary side coil is wound around a substantially U-shaped primary core, and a secondary coil provided on the rotating side is bitten into the inside of the approximately U-shape. A device that has a structure that reduces the size of the device and reduces manufacturing costs is known. (For example, see Patent Document 1)

  In addition, a substantially C-shaped primary core is used to wind a coil at a plurality of locations, and the secondary coil provided on the rotating side has a substantially C-shaped core as in Patent Document 1. Structures that bite into the interior are also known. This is to improve the power supply efficiency by optimizing the position where the secondary coil bites. (For example, see Patent Document 2)

JP 2000-58355 A JP 2011-243816 A Utility Model Registration No. 3175976

However, in the techniques described in Patent Literature 1 and Patent Literature 2, the primary side core is configured to sandwich the secondary side coil, and the portion where the primary side core exists in the rotational radius direction becomes large, and the device It cannot be said that it is sufficient for downsizing.
At the same time, a space for installing the primary side core and a space for arranging a plate for winding the secondary side coil are also required in the direction of the rotation axis, which leads to an increase in the size of the apparatus.

  Further, the secondary coil is inserted into the opening of the primary core, and the assembling method is very limited. That is, after the secondary coil is installed on the rotating shaft side, it is assembled into the housing, the primary core is moved in the axial direction with the opening sandwiching the secondary coil, and the housing is placed at a predetermined position. Positioning and fixing to the body. Therefore, so-called drop assembly of the primary core and automatic assembly by a robot or the like are extremely difficult.

In particular, in the embodiments described in Patent Document 1 and Patent Document 2, since the secondary coil is wound around a vinyl chloride plate, it is difficult to increase the processing accuracy of this plate and distortion is likely to occur. Therefore, it can be said that it is difficult to ensure the positioning accuracy between the primary core and the secondary coil.

  Further, in Patent Document 3, since the secondary core uses a hollow cylindrical ferrite core, the size of the secondary core increases with a large rotational axis, and the thickness and weight increase accordingly. The problem was that it became expensive. In particular, a large size ferrite core has a difficulty in dimensional accuracy, and additional work on the ferrite core is required to assemble with a fitting to the rotating shaft.

  On the other hand, in the wiring drawn out from the secondary side coil, if it passes through the surface of the secondary side core, it becomes difficult to reduce the distance between the primary side core and the secondary side core, which occurs between the cores. Magnetic flux decreases. In view of this, it has been practiced to carve a groove for wiring on the secondary core and embed the wiring there. As a result, the distance between the cores can be shortened, but it is necessary to devise measures such as increasing the cost of the secondary side core by groove processing and bonding so that the wiring does not protrude from the groove.

  Therefore, it is conceivable to make a hole in this hollow cylindrical ferrite and pull it out through the wiring. In this case, since the secondary side core needs to be drilled, the cost is increased, and it is necessary to insert the wiring into the hole after winding the coil, so that the assembly is very difficult.

  The present invention has been made in order to solve the above-described conventional problems, and is a circuit that is easy to assemble and is placed on a rotating body at a low cost, while being capable of downsizing the apparatus. An object of the present invention is to provide a rotary contactless power supply transformer that supplies electric power.

The present invention
A primary core made of a U-shaped magnetic body having protrusions on both sides;
A primary coil wound between the protrusions of the primary core;
A secondary core provided in a coaxial cylindrical shape with a rotation shaft rotatably supported;
It is arranged on the outer periphery of the secondary side core so as to be sandwiched between the protrusions of the primary side core, and is wound in the direction of the rotation axis with the same width as the primary side coil so as to face the primary side coil. In the rotary contactless power supply transformer comprising the secondary side coil,
The surface of the primary core facing the secondary core has a polyhedral shape that is recessed along the outer peripheral surface of the secondary core,
The secondary core is formed of a strip-like magnetic material having a width larger than at least the axial length of the rotation axis of the primary core, and is wound and fixed to the rotation shaft with a joint. It is said.

The secondary side core state, and are formed by laminating the sintered ferrite with a resin film,
An electric wire drawn from the secondary coil passes through the joint of the secondary core, and is in a groove having a shape larger than at least the cross-sectional dimension of the electric wire provided on the rotary shaft in the axial direction of the rotary shaft. along, Rukoto wired in between the rotary shaft and the secondary core is desirable.

Furthermore, it is preferable that the joint has a portion that extends in a winding direction of the secondary coil around the rotating shaft between the protrusions of the primary core and intersects the groove .

It is a disassembled perspective view of the torque sensor which has a rotary non-contact electric power feeding transformer concerning the embodiment of the present invention. It is a block diagram which shows the structure of the torque sensor which has a rotary type non-contact electric power feeding transformer which concerns on embodiment of this invention. It is a perspective view which shows the rotary type non-contact electric power feeding transformer which concerns on embodiment of this invention. It is a side view which shows the rotary non-contact electric power feeding transformer which concerns on embodiment of invention. It is a perspective view which shows the rotary type non-contact electric power feeding transformer which concerns on embodiment of this invention. It is the perspective view which abbreviate | omitted and represented the rotary type non-contact electric power feeding transformer which concerns on embodiment of this invention. It is an expanded view of the Example of the rotary non-contact electric power feeding transformer which concerns on embodiment of this invention.

  Hereinafter, a rotary contactless power transfer transformer according to an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view of a torque sensor having a rotary contactless power supply transformer according to an embodiment of the present invention. FIG. 2 is a block diagram of the electric circuit of the torque sensor.

As shown in FIGS. 1 and 2, the torque sensor 42 is rotatably supported by a side wall 8 attached to the housing 9 via a rolling bearing 4, and a strain generating body and a power transmission shaft are provided. A rotating shaft 1 is also provided.

The rotating shaft 1 has a strain generating portion 18 having a function of a strain generating body. The strain generating portion has strength in the axial direction of the rotating shaft and does not deform, but bends in the torsional direction. Here, the strain gauge 2 is bonded, and the torque applied to the rotating shaft 1 is measured.

The rotating side substrate 3 is fixed to the rotating shaft 1 so as to be sandwiched between fixing nuts 11, and a detection circuit 30 (see FIG. 2) is provided on the rotating side substrate 3. The detection circuit 30 is connected to the strain gauge 2 to form a Wheatstone bridge circuit together with the resistance, an amplification circuit for amplifying and converting a resistance value change of the strain gauge 2 into a voltage signal, and output from the Wheatstone bridge circuit. It comprises a modulation circuit for converting an analog output into a digital signal and transmitting it by infrared communication such as IrDA. The modulated signal is emitted and transmitted by the LED 31.

On the other hand, the stationary substrate 7 is fixed to the housing 9, and an output circuit 41 is provided on the stationary substrate 7. The output circuit 41 includes an amplification circuit that receives and amplifies the detection signal from the detection circuit 30, and a demodulation circuit that converts the amplified detection signal into an analog signal. 7 and the external connector 12 connected by an electric wire or the like.

Further, a switching circuit 34 that supplies power to the output circuit 30 is provided on the fixed-side substrate 7, and power is supplied from an external DC power supply 33 through the external connection connector 12. The switching circuit 34 generally converts a DC power source into an AC power source, but a power source such as a flyback converter may be used.

A primary side core 16 of U-shaped ferrite having protrusions at both ends is attached to the fixed side substrate 7 via a primary side core holder 14. A primary coil 6 formed by winding a copper wire is provided between the projecting portions of the primary core 16. Electric power is supplied from the switching circuit 34 to the primary coil 6. Note that the opening portion of the housing 9 corresponding to the fixed substrate 7 is closed with a lid 10.

  On the other hand, the secondary side of the rotary transformer is configured on the rotary shaft 1 so as to face the primary side coil 6 and the primary side core 16 at a predetermined interval. The secondary side core 15 is provided by being wound around the rotary shaft 1, and the secondary side coil 5 formed by winding a copper wire around the outer periphery of the secondary side core 15 is provided. The details of the relationship between the primary side core 16 and the secondary side core 15 will be described later.

  Since the present embodiment is configured as described above, when an electric current converted into an alternating current by the switching circuit 34 is supplied to the primary side coil 6 via the external DC power supply 33, an AC magnetic field is generated, and this AC magnetic field is generated. Is transmitted through the secondary core 15 on the rotating shaft side, so that a current is induced in the secondary coil 5.

The induced current is supplied to the strain gauge 2 and the detection circuit 30 through the rectification circuit 35 and the stabilization circuit 36 provided in the rotation side substrate 3.
With the above mechanism, power is supplied to the detection circuit 30 in a non-contact manner. Further, power is also supplied to the output circuit 41 from the DC power supply 33.

  In actual torque measurement, when torque is applied to the rotating shaft 1, the strain generating portion 18 of the rotating shaft 1 is distorted in accordance with the magnitude of the torque, and the magnitude of the distortion is a change in the resistance value of the strain gauge 2. Is detected by the detection circuit 30 and communicated with the output circuit 41 by infrared rays. That is, the analog signal generated by the change in the resistance value is digitized and modulated by A / D conversion, and light is transmitted from the LED 31. The light receiving element 32 receives this and sends it to the output circuit 41.

The output circuit 41 amplifies the received signal, converts it into an analog signal by a D / A converter, that is, a demodulation circuit 40, and outputs it as a voltage signal corresponding to the detected torque. The output voltage signal is displayed on a display or the like by known means.

  Next, with reference to FIGS. 3 and 4, an embodiment of the rotary contactless power supply transformer of the present invention will be described. FIG. 3 is a perspective view showing the main part of the rotary contactless power supply transformer of the present invention, and FIG. 4 shows the positional relationship of the main part of the rotary contactless power supply transformer in the axial direction of the rotary shaft 1. It is the side view shown.

The primary core 16 has a U-shaped cross section with protrusions at both ends. In this embodiment, this material is a low-loss ferrite material. The primary core 16 is fixed to the fixed substrate 7 via the primary core holder 14. The primary side core holder 14 is made of resin or the like and holds the primary side core 16 so as to surround it.

The primary side coil 6 is wound a predetermined number of times between both protrusions of the primary side core 16, and the end of the primary side coil 6 is connected to the switching circuit 34 of the fixed side substrate 7.

On the other hand, the constituent member of the non-contact power supply transformer 17 on the secondary side that forms a pair with the primary side core 16 and the primary side coil 6, that is, the secondary side core 15 and the secondary side coil 5 are wound around the rotary shaft 1. It is provided as follows.

  The secondary core 15 is formed to be slightly larger in the rotation axis direction than the width of both protrusions of the primary core 16 and is a strip-shaped sheet of ferrite. This sheet is thin and flexible, and a sintered ferrite sheet is used. That is, this ferrite is laminated with a polyethylene terephthalate (PET) film through an adhesive layer, and further, an adhesive layer is provided on one side so as to be attached to a component or the like and covered with a peelable paper. In this embodiment, a laminated sheet having a total thickness of about 0.15 mm is used and can be easily attached to a curved surface.

Therefore, since the hollow cylindrical ferrite core is not used, a dedicated die for manufacturing the ferrite core is not required, and the amount of ferrite used is small, which is extremely advantageous in terms of cost.
In particular, in a product with many lineups with different diameters of rotating shafts depending on the magnitude of torque to be measured, such as a torque sensor, a hollow cylindrical ferrite core must be incorporated in accordance with each. When this thin sheet is used, the outer shape can be easily cut with a cutter knife or the like, and it is excellent in that it can flexibly correspond to each lineup.

The secondary side core 15 is fixed to the rotating shaft 1 by an adhesive layer laminated on an adhesive or a resin film so as to keep a constant distance from the protrusion of the primary side core 16, and the secondary side core 15 It has a structure in which both sides are fixed by the presser 13 to prevent floating.

In the non-contact power feeding, the distance between the primary side core 16 and the secondary side core 15 and the displacement of the opposing surface greatly reduce the magnetic flux, so that the primary side core 16 and the secondary side core 15 are rotated when the rotary shaft 1 is rotated. It is desirable that the interval is as narrow as possible and always constant. Therefore, the surface where the first protrusion 45a and the second protrusion 45b of the primary core 16 are opposed to the secondary core 15 is the surface of the secondary core 15 with the axis of the rotating shaft 1 as the center. To form a cylindrical surface having a predetermined interval.

FIG. 5 is a perspective view of a main part of the rotary contactless power supply transformer, showing a modification of the tip of both protrusions of the primary core 16. A surface facing the secondary core 15 of the first protrusion 45a and the second protrusion 45b of the primary core 16 is configured by a plurality of surfaces, and is maintained at approximately the same distance as the secondary core 15. It is also possible to make it. That is, as the diameter of the rotary shaft 1 increases, the secondary core 15 becomes closer to a flat surface. Therefore, if the surface is cut by a polygon centered on the axis of the rotary shaft 1, the distance is fixed to some extent. Because it is kept. In this case, although there is a slight decrease in the magnetic flux, it can be realized at a lower cost compared to the cylindrical surface. It can be selected as appropriate according to the specifications.

The secondary coil 5 is wound on the secondary core 15, and the winding width is the same as that of the primary coil 6, and the first protrusion 45 a of the primary core 16. And it is provided so that it may be located between the 2nd protrusion 45b.

By the way, since the secondary side core 15 is a strip-like sheet as described above, the secondary side core 15 is wound and fixed to the rotary shaft 1. However, since the secondary side core 15 is wound around the entire circumference of the rotary shaft 1, a joint is necessarily formed. Occur. It is desirable to provide this joint with as little gap as possible.

In the embodiment of the present invention, a thin strip-shaped sheet having a thickness of 0.15 mm is used, and as described above, the release paper can be peeled off and stuck on the adhesive layer, so that the rotation shaft has a minimum gap. 1 can be pasted.

FIG. 6 is a perspective view of the rotary contactless power feeding device of the present embodiment shown in FIG. 3 with some members omitted. Further, the secondary core 15 is expressed translucently for easy explanation.
7 expands the primary side core 16, the secondary side core 15, and the secondary side coil 5 along the rotational direction A of the rotary shaft 1 of the rotary contactless power feeding device of the present embodiment shown in FIG. FIG.
Hereinafter, the secondary core 15 and the secondary coil 5 will be described with reference to FIGS. 6 and 7.
In this embodiment, a plurality of joints 43a and joints 43b are provided in the direction perpendicular to the winding direction of the secondary core 15 around the rotary shaft 1, that is, in the x direction shown in FIG.

The use of this strip-shaped sheet facilitates the wiring of the secondary coil 5.

  As described above, when the wiring from the secondary side coil 5 is installed on the surface of the secondary side core 15, both protrusions (the first protrusion 45a or the second protrusion 45a) of the primary side core 16 by the thickness of the electric wire. The gap between the protrusion 45b) and the secondary core 15 increases, the magnetic flux generated between the cores decreases, and it becomes difficult to obtain the desired power supply performance.

On the other hand, in this embodiment, the lead wire 5a of the secondary coil 5 is inserted between the lower surface of the secondary core 15 and the rotary shaft 1 at the joint 43c in the unfolding direction y shown in FIG. Wiring to the rotation side substrate 3 is performed. A groove 44 having a width and a depth greater than the cross-sectional dimension of the leader line is provided in the path of the rotating shaft 1 with which the leader 5a contacts, thereby facilitating wiring.

If a gap is generated in the joint 43c, the magnetic flux is divided, and the power feeding performance is degraded. Actually, since it is necessary to pass the lead wire 5a of the secondary coil 5, a slight gap is generated. Accordingly, the length B in the deployment direction y direction of the joint 43c is shortened as much as possible, and the joint 43c is provided with a slight overlap allowance in the x direction so that the assembly work can be easily performed while ensuring the power feeding performance. It can be carried out.

In actual assembly, the rotation-side substrate 3 is inserted into the rotation shaft 1 and fixed with the fixing nut 11. Next, one side of the secondary side core presser 13a is passed through the rotary shaft in advance, and is made to stand by in the vicinity of the fixing nut 11. The secondary core 15 is wrapped around a rotating shaft and pasted, leaving the release paper only in the vicinity of the portion covering the groove 44 of the secondary core 15. At that time, the vicinity of the groove 44 of the secondary core 15 is slightly floated. Thereafter, the secondary coil 5 is wound a predetermined number of times, and the secondary core 15 floating on the lead wire 5a is turned up and guided to the groove 44 through the joint 43c. Thereafter, the release paper is removed, and the remaining part of the secondary core 15 may be bonded to the rotary shaft 1. Since the secondary core 15 is a thin sheet and deforms flexibly, this operation can be easily performed.

  Thereafter, the secondary side core presser 13a that has been waiting is fitted into the secondary side core 15, and the other secondary side core presser 13b is fitted, and the secondary side core 15 is surely lifted off the rotary shaft 1. It is fixed without any problems.

Therefore, the lead wire 5a of the secondary side coil 5 is wired along the groove 44 under the secondary side core 15 and the secondary side core retainer 13, and is electrically connected to the rotating side substrate 3. The Therefore, power is supplied to the detection circuit 30 on the rotation side substrate 3 by a non-contact power feeding method.

In the present embodiment, the secondary core 15 is provided with joints of a plurality of line segments perpendicular to the winding direction around the rotating shaft 1, that is, in the x direction, but is perpendicular to the winding direction. Needless to say, there is no limitation or limitation which is a connection between straight line segments, and it can be realized by a curve or the like.

It is desirable that the lead wire 5a of the secondary coil 5 is wired under the lower surface via the joint of the secondary core 15 so that the y-direction component of the joint is as small as possible. This is because the strength of the magnetic flux can be secured by reducing the y-direction component of the joint of the secondary core 15.

  The present invention has been described based on the embodiments. It should be understood by those skilled in the art that the form of the present embodiment is an exemplification, and various modifications can be made to each component, and such modifications are also within the scope of the present invention.

  As described above, in the rotary contactless power supply transformer according to the present invention, the rotating secondary side core is formed by winding a strip sheet having a joint around the rotating shaft to form a magnetic flux with the primary side core. It is possible to provide a rotary non-contact power supply transformer that is stable and that facilitates the wiring of the secondary coil.

DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Strain gauge 3 Rotation side board | substrate 4 Bearing 5 Secondary side coil 5a Leader 6 Primary side coil 7 Fixed side board | substrate 8 Side wall 9 Housing | casing 10 Lid body 11 Fixing nut 12 External connection connector 13a 13b Secondary side Core retainer 14 Primary side core holder 15 Secondary side core 16 Primary side core 17 Non-contact power supply transformer 18 Strain generating portion 30 Detection circuit 31 LED
32 Photodetector 33 DC power supply 34 Switching circuit 35 Rectifying circuit 36 Stabilizing circuit 37 Amplifying circuit 38 Modulating circuit 39 Amplifying circuit 40 Demodulating circuit 41 Output circuit 42 Torque sensor 43a First joint 43b Second joint 43c Third Seam 44 groove 45a first protrusion 45b second protrusion

Claims (3)

A primary core made of a U-shaped magnetic body having protrusions on both sides;
A primary coil wound between the protrusions of the primary core;
A secondary core provided in a coaxial cylindrical shape with a rotation shaft rotatably supported;
On the outer periphery of the secondary side core, disposed so as to be sandwiched between the protrusions of the primary side core, facing the primary side coil and having a rotational axis substantially the same width as the primary side coil A secondary coil wound in a direction;
In a rotary contactless power supply transformer comprising:
The surface of the primary core facing the secondary core has a polyhedral shape that is recessed along the outer peripheral surface of the secondary core,
The secondary core is formed of a strip-like magnetic material having a width larger than at least the axial length of the rotary shaft of the primary core, and is wound and fixed to the rotary shaft with a joint. Yes,
Rotating contactless power transformer characterized by that. The secondary core is state, and are formed by laminating the sintered ferrite with a resin film,
An electric wire drawn from the secondary coil passes through the joint of the secondary core, and is in a groove having a shape larger than at least the cross-sectional dimension of the electric wire provided on the rotary shaft in the axial direction of the rotary shaft. The rotary non-contact power supply transformer according to claim 1, wherein the rotary non-contact power supply transformer is wired between the secondary core and the rotating shaft along the axis . The joint includes a portion that extends in a winding direction of the secondary coil around the rotating shaft between the protrusions of the primary core and intersects the groove. Item 3. The rotary contactless power supply transformer according to Item 2 .