Patent Application
20100156401
1. Field of the Invention
The present invention relates to a magnetic resolver, the construction of which enhances the productivity in making the magnetic resolver, and a method of manufacturing the same.
2. Description of the Related Art
An electric motor controller that includes a Hall IC (integrated circuit) for detecting the position of a rotor may be manufactured by forming a printed board having a doughnut shape that surrounds the shaft of the rotor. Then, a first cutout is made in the printed board on the inner-diameter side of the doughnut-shaped printed board to provide the Hall IC therein, and a second cutout in the printed board on the outer-diameter side thereof to draw out the leads (see, Japanese Patent Publication No. 7-79542 (“JP 7-79542”), for example).
Generally, conventional magnetic resolvers include a rotatable rotor core; a stator core, with two stator plates that sandwich the rotor core from above and below, and that have convex, protruding poles arranged along the circumference of the stator core; and thin-film coils that are wound around the respective protruding poles of the stator core, and detect the rotation angle of the rotor core by using the fact that the inductance of a coil varies with the rotation angle of the rotor core (see, Japanese Utility Model Application Publication No. 5-3921 (“JP 5-3921”), for example).
In a conventional resolver as described in JP 5-3921, the thin-film coils are formed on a substrate in a pattern, which results in a thinner resolver body as compared to a conventional resolver in which wire is wound around the convex cores on the stator that face the rotor in the radial directions. In addition, it becomes unnecessary to wind wire to obtain coils. However, JP 5-3921 fails to disclose a specific configuration of a substrate on which the thin-film coils are formed. If a doughnut-shaped (annular) substrate is used as described in JP 7-79542 cited above, an inferior yield rate is brought about when a plurality of annular substrates are cut out of a substrate material.
The present invention provides a magnetic resolver in a shape obtained by dividing an annular resolver, thus, allowing a plurality of substrates to be produced from a substrate material, thereby improving the yield rate, and provides a method of manufacturing the magnetic resolver.
A magnetic resolver according to a first aspect of the present invention includes: an annular stator portion having a protruding core; an annular coil substrate on which a coil portion, which is disposed around the protruding core, is formed as a patterned thin-film coil; and a rotor portion that faces the stator portion from above with the coil substrate interposed therebetween, wherein the amount of overlap between a top face of the protruding core and the rotor portion when viewed from above varies as a rotation angle of the rotor portion relative to the stator portion varies. The annular coil substrate is constituted of substrate pieces that have shapes obtained by dividing the annular shape.
A magnetic resolver according to a second aspect of the present invention is similar to that of the first aspect of the present invention, except that the substrate piece is a laminated substrate piece that is obtained by laminating a plurality of substrate pieces, on each of which at least one patterned coil is formed. With the magnetic resolver according the second aspect of the present invention, it is possible to achieve a necessary number of windings of coils without increasing the diameter of the magnetic resolver.
A magnetic resolver according to a third aspect of the present invention further includes: an annular cover that covers the coil substrate from above, sandwiching the coil substrate between the annular cover and the stator portion, and that integrates the stator portion and the coil substrate. The connection terminal for electrically connecting the patterned coils formed on their respective substrate pieces may be integrally formed with the cover. With the magnetic resolver according to the third aspect of the present invention, it is possible to easily establish an electric connection between the patterned coils of different substrate pieces.
A fourth aspect of the present invention is a method of manufacturing a magnetic resolver, including: forming, on a substrate material, a plurality of patterned thin-film coils that correspond to a plurality of coil portions, and forming a through hole in the substrate material at the center of each patterned coil; cutting the substrate material into a plurality of substrate pieces so that each substrate piece has at least one patterned coil; forming an annular coil substrate, the shape of which corresponds to the annular shape of the stator portion, by attaching, from above, at least two substrate pieces to an annular stator portion having a protruding core that is passed through the through hole; attaching a rotor portion onto the annular coil substrate from above, wherein the amount of overlap between a top face of the protruding core and the rotor portion when viewed from above varies as a rotation angle of the rotor portion relative to the stator portion varies; and electrically connecting the coil portions formed on their respective substrate pieces of the annular coil substrate.
The foregoing and further objects, features and advantages of the invention will become apparent from the following description of example embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:
Embodiments of the invention will be described below with reference to the drawings.
The magnetic resolver 10 of this embodiment is a variable reluctance (VR) resolver, and, as shown in
The rotor plate 40 is made of an iron-based magnetic material, and has an annular shape. The rotor plate 40 is typically formed of a lamination consisting of magnetic steel sheets (made of ferrosilicon, for example). The profile of the rotor plate 40 does not have a fixed diameter thus the radius periodically varies (the details of the profile will be described later). An angular multiplication factor, N, that determines the periodic variation of the radius may be appropriately determined depending on the resolution required.
The rotor plate 40 is fixed to the rotary shaft 42. The rotary shaft 42 is a shaft of which the rotation angle is to be detected by the magnetic resolver 10, and may be an output shaft of a motor, for example. A positioning protrusion 44a is formed on the periphery of a center hole 44 of the rotor plate 40, and a groove 42a corresponding to the protrusion 44a is cut in the outer circumferential surface of the rotary shaft 42 along the axial direction. The rotary shaft 42 is inserted into the rotor plate 40 in an angular relation such that the protrusion 44a fits in the groove 42a. In this way, the rotor plate 40 is held in a fixed position on the rotary shaft 42. It should be noted that the way in which the rotor plate 40 may be fixed to the rotary shaft 42 is arbitrary. A means for restricting the movement of the rotor plate 40 in the axial direction relative to the rotary shaft 42 may be additionally provided.
The base plate 20 is made of an iron-based magnetic material, and has an annular shape. The base plate 20 is typically formed of a lamination consisting of magnetic steel sheets (made of ferrosilicon, for example). The center of the annular shape of the base plate 20 coincides with the center of a rotary shaft 42 of the rotor portion.
On the base plate 20, protruding cores 22 are formed. The cores 22 are made of an iron-based magnetic material (ferrosilicon, for example) as in the case of the base plate 20. The cores 22 may be integrally formed with the base plate 20 by machining or etching, for example, or otherwise may be formed by placing, on the base plate 20, columnar laminations that are formed separately.
In this embodiment, every core 22 is a columnar protrusion having the same shape. The cores 22 are regularly arranged on the annular base plate 20 along the circumference thereof. Specifically, the centers of the cores 22 (the centers of the circles) are located on the same radius circle with the rotary shaft 42 of the rotor portion centered, at evenly spaced angular positions. In the particular embodiment shown in the drawings, for example, ten cores 22 (ten poles) are formed at 36-degree intervals.
Positioning protrusions 24 are formed on the base plate 20 along the periphery. Two pairs (24a, 24b) of positioning protrusions 24 are formed. The interval between the two positioning protrusions of one pair along the circumference is set to the same interval as that between the two positioning protrusions of the other pair along the circumference. However, this interval is set so that it differs from the interval between two positioning protrusions 24a and 24b along the circumference that belong to different pairs and are adjacent to each other. Specifically, one positioning protrusion 24a is disposed at a position that is shifted from the position of the other positioning protrusion 24a of the same pair by a first angle α, while the position of the one positioning protrusion 24a is shifted from the position of a positioning protrusion 24b of the other pair by a second angle β (≠ first angle α). Reasons for adopting this setting will be described later.
The coil substrate 30 has an annular shape, and through holes 32, through which the cores 22 are passed, are made in the coil substrate 30 along the circumference. Each through hole 32 has a circular shape corresponding to the shape of the core 22, more specifically, a circular shape with a radius equal to or slightly greater than the radius of the core 22. The through holes 32 are regularly arranged in the annular coil substrate 30 along the circumference thereof. Specifically, the centers of the through holes 32 (the centers of the circles) are located on the same radius circle with the rotary shaft 42 of the rotor portion centered, at evenly spaced angular positions. In the embodiment shown in the drawings, ten through holes 32 (ten poles) are made at 36-degree intervals, corresponding to the cores 22.
A patterned coil 34 having a spiral shape is printed around each through hole 32. The patterned coils 34 are formed by printing an electrically conductive material, such as copper, on a substrate material 90 (insulating substrate) described later. The patterned coils 34 on the same coil substrate 30 are connected in series. The connection between the patterned coils 34 may be realized by printing connection lines (electrically conductive film) 35 on the substrate material 90, except the connection portions realized by inter-substrate connection terminals 37 described later. In this case, the printing to connect the patterned coils 34 may be carried out concurrently with the printing of the patterned coils 34, so that it is possible to efficiently implement the formation of the patterned coils 34 and the electric connection therebetween on the coil substrate 30.
The protruding cores 22 pass through the through holes 32 of the coil substrate 30 when the coil substrate 30 is placed on the base plate 20. In this way, around one through hole 32, the coil portion of one pole is formed by the corresponding patterned coil 34.
It is preferable that the coil substrate 30 be provided for each of the phases (1-phase input/2-phase output, in this embodiment) individually. In the embodiment shown in the drawings, each of the coil substrate 30 that serves as excitation coils (hereinafter also referred to as “the excitation coil substrate 30a”), the coil substrate 30 that serves as coils for outputting a cosine-phase signal (hereinafter also referred to as “the cosine-phase coil substrate 30b”), and the coil substrate 30 that serves as coils for outputting a sine-phase signal (hereinafter also referred to as “the sine-phase coil substrate 30c”) are provided in separate coil substrates 30. By forming separate coil substrates 30 for each respective phase, it is possible to change the configuration of the patterned coils 34 of each phase (the adjustment or alteration to the number of windings, the winding direction or the like) without changing the coil substrate 30 of another phase, so that versatility is improved. In addition, it is possible to flexibly respond to the addition or change of the phases. For the sake of convenience in explanation, each of the plurality of insulating substrates constituting the coil substrate 30 is also referred to as the coil substrate.
It is preferable that the coil substrates 30a, 30b and 30c for each phase be formed by stacking or laminating a plurality of the coil substrates 30. In this case, the patterned coils 34 of the same pole on the coil substrates 30 of the respective layers are electrically connected in series by using via holes (not shown). In this way, it is possible to efficiently provide the required number of windings of the coil for each pole without unnecessarily increasing the radial width of the annular coil substrates 30a, 30b and 30c.
In this embodiment, the excitation coil substrate 30a is formed by stacking two layers of the coil substrates 30, and each of the cosine-phase coil substrate 30b and the sine-phase coil substrate 30c is formed by stacking six layers of the coil substrates 30. The number of windings and the winding direction of the patterned coils 34 of each pole on each of the coil substrates 30 of the respective phases are determined so that a desired sine-phase output and a desired cosine-phase output are induced as the rotor plate 40 rotates (that is, as the area of overlap between the core 22 and the rotor plate 40 varies with the rotation), as described below.
A cover 70 is placed on the top of the coil substrate 30 (the sine-phase coil substrate 30c in this embodiment) that is the uppermost one of the coil substrates stacked on the base plate 20 as described above. The cover 70 has an annular shape corresponding to the shape of the coil substrate 30. As in the case of the coil substrate 30, through holes 74 through which the cores 22 are passed are formed in the cover 70. The through holes 74 have a circular shape corresponding to the shape of the cores 22. Specifically, the radius of the circular shape is equal to or slightly greater than the radius of the core 22. The through holes 74 are regularly arranged in the annular cover 70 along the circumference. Securing tabs 72 are formed on the outer edge of the cover 70. The securing tabs 72 are formed such that the tip portions thereof engage with (hook onto) the outer edge of the base plate 20. In the embodiment shown in the drawings, three securing tabs 72 are provided along the periphery of the cover 70 at equal intervals.
The cover 70 is provided with a connection terminal 76 and the inter-substrate connection terminals 37 (see
One end of the excitation coil (which means all of the patterned coils 34 that are connected in series on the excitation coil substrate 30a) formed on the excitation coil substrate 30a as described above is connected to a ground via the connection terminal 76, and the other end thereof is connected to an AC power source via the connection terminal 76. During operation, the AC power source applies an AC input voltage of 4 V, for example, across the excitation coil formed on the excitation coil substrate 30a.
One end of the sine-phase coil (which means all of the patterned coils 34 that are connected in series on the sine-phase coil substrate 30c) formed on the sine-phase coil substrate 30c as described above is connected to the ground via the connection terminal 76, and the other end thereof is connected to a signal processor (not shown) via the connection terminal 76. In this way, a sine-phase output voltage (induced voltage) is supplied to the signal processor mentioned above. In this embodiment, the sum of the voltages, each of which is induced across the corresponding one of the ten poles, is supplied as the sine-phase output voltage.
Similarly, one end of the cosine-phase coil (which means all of the patterned coils 34 that are connected in series on the cosine-phase coil substrate 30b) formed on the cosine-phase coil substrate 30b as described above is connected to the ground via the connection terminal 76, and the other end thereof is connected to the signal processor (not shown) via the connection terminal 76. In this way, a cosine-phase output voltage (induced voltage) is supplied to the signal processor mentioned above. In this embodiment, the sum of the voltages, each of which is induced across the corresponding one of the ten poles, is supplied as the cosine-phase output voltage.
The signal processor detects the rotation angle θ of the rotor plate 40 (the rotation angle θ of the rotary shaft 42) with the use of the following equation, based on the sine-phase output voltage and the cosine-phase output voltage:
θ=1/N·tan−1 (ECOS-GND/ESIN-GND)
where ECOS-GND is the cosine-phase output voltage, and ESIN-GND is the sine-phase output voltage.
Next, details of main components of the magnetic resolver 10 of the embodiment described above will be explained.
In this embodiment, each coil substrate 30 is constituted of substrate pieces 301 and 302 having a semiannular shape that is obtained by dividing an annular shape into two halves, as shown in
In each of the substrate pieces 301 and 302, two positioning notches 31 are formed symmetrically. The positioning notches 31 have a shape that fits with the positioning protrusion 24 on the periphery of the base plate 20. The two positioning notches 31 of the pair formed in the substrate piece 301 are provided at the positions one of which may be shifted from the other by the first angle α, which corresponds to the interval between the positioning protrusions 24 of the corresponding pair along the circumference. Similarly, the two positioning notches 31 of the pair formed in the substrate piece 302 are provided at the positions one of which is shifted from the other by the first angle α. Reasons for adopting this setting will be described later.
In each of the substrate pieces 301 and 302, terminal connection portions 36a to 36c, which are electrically connected to the inter-substrate connection terminals 37, will also be described later. Four terminal connection portions 39 that are electrically connected to the connection terminal 76 are formed in the substrate piece 301. The terminal connection portions 36a to 36c, and 39 may be formed as via-holes that are made in the substrate pieces 301 and 302.
When completely annular coil substrates are produced from a substrate material 90, as shown in
On the other hand, if semiannular substrate pieces are produced from the substrate material 90, as in accordance with this embodiment, as shown in
The excitation coil substrate 30a, the cosine-phase coil substrate 30b and the sine-phase coil substrate 30c are stacked on the base plate 20. The order in which the coil substrates 30a, 30b and 30c of the respective phases are stacked is arbitrary. The coil substrates 30 of the respective layers may be sequentially stacked on a layer-by-layer basis, wherein corresponding semiannular substrate pieces 301 and 302 are paired. By disposing a pair of semiannular substrate pieces 301 and 302 on the base plate 20, a completely annular coil substrate 30 is formed. At this time, the semiannular substrate pieces 301 and 302 are assembled such that the positioning protrusions 24 provided on the periphery of the base plate 20 fit in the positioning notches 31. As described above with reference to
Alternatively, the semiannular substrate pieces 301 of all the layers or of several layers may be stacked and bonded in advance, and the bonded semiannular substrate pieces 301 as a unit may be attached to the base plate 20 (see
As shown in
When the cover 70 is attached to the coil substrate 30, the inter-substrate connection terminals 37a to 37c are inserted into the corresponding terminal connection portions 36a to 36c (see
As shown in
Similarly, when the cover 70 is attached to the coil substrate 30, the pin terminals 76a are inserted into the terminal connection portions 39 of the substrate pieces 301 and 302. The pin terminals 76a and the terminal connection portions 39 are electrically connected by an appropriate method (such as soldering, welding and press-fitting). In this way, the electrical connection between the connection terminal 76 and the coils of the respective phases is established.
As described above, in this embodiment, even if the coil substrate 30 is constituted of a plurality of divided substrate pieces 301 and 302, when the inter-substrate connection terminals 37a to 37c are integrally formed with the cover 70, it is possible to establish the electric connection between the substrate pieces 301 and 302 relatively easily when the cover 70 is attached to the coil substrate 30. Needless to say, the inter-substrate connection terminals 37a to 37c are separately provided from the cover 70.
In the embodiment shown in
In the embodiment shown in
With regard to the substrate pieces 303, the flexibility in cutting pieces of material from the substrate material is high as in the case of the substrate pieces 301 and 302 in the above-described embodiment. Accordingly, when a dense arrangement for cutting pieces of material out of the substrate material is adopted, it is possible to produce a relatively large number of coil substrates 30 (substrate pieces 303).
The size of the substrate pieces 303 (the way in which the coil substrate 30 is divided) is arbitrary. In addition, it is possible to select the most suitable pattern of partition after considering the increase in the number of parts with the improvement in the yield rate with respect to material.
For example, although, in the embodiments described above, the patterned coils 34 are printed on an insulating substrate, the patterned coils 34 may be formed by any method of forming patterned coils 34 made of electrically conductive film (thin film). The patterned coils 34 may be formed by using another printing technology, such as a film transfer method, by disposing and bonding a film, in which a similar coil pattern is formed, on the substrate, or by stamping, vapor deposition, etc.
In addition, although, in the embodiments described above, the annular coil substrate 30 is constituted of the substrate pieces (301 and 302, or 303) that have the same shape, the annular coil substrate 30 may be formed of substrate pieces that have different shapes. For example, the annular coil substrate 30 may be formed by combining a semiannular substrate piece that has a central angle of about 120°, and a semiannular substrate piece that has a central angle of about 240°.
Although, in the above embodiments, the “1-phase input/2-phase output” configuration is adopted, “1-phase input/1-phase output” configuration may be adopted. The particular configuration of the phase is arbitrary.
Although example embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiment. Various modifications and substitutions can be made to the above-described embodiment without departing from the scope of the present invention. The present invention may be used in all kinds of apparatuses that detect the rotation angle of a rotor, such as, for example, rotation angle sensors that detect a rotation angle of a shaft in a power steering system.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-111266 | Apr 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB07/00937 | 4/12/2007 | WO | 00 | 10/7/2008 |
