This application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2010-029669 filed on Feb. 15, 2010, the entire content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a brushless DC motor provided with a coil having an end portion with a specific connecting structure.
2. Related Art
Some kinds of brushless DC motors, in which a disc-shaped substrate having a sensor IC and a driving circuit is provided on an axial one side surface of a stator wound with a coil, are known. In this structure, a method for connecting an end of a coil wound around a terminal of an insulator to the substrate is complicated, and positioning of the substrate with respect to the stator and the sensor IC is required. Furthermore, after the winding operation, the end of the coil must be connected to a part of the substrate, whereby many operating steps are required in assembling.
Relating to the above technique, Japanese Patent Application, First Publication No. 2001-245455 discloses a motor in which a cylindrical receiver for a control substrate mounted to a stator is provided. In the structure, plural protruding ribs for positioning and engaging the control substrate and plural protruding ribs in which the end portions thereof are abutting around a circumferential surface of the control substrate and receiving the control substrate are formed on a circumferential surface of the cylindrical receiver in the vicinity of an edge thereof. Furthermore, slits for temporary engaging ends of a coil of the stator are formed on the abutting surfaces of the ribs which receive the control substrate in such a way that the positions of the slits coincide with the terminals for connecting the coil of the control substrate.
Japanese Patent Application, First Publication No. 2007-143295 discloses a structure in which a radial protrusion is formed on a substrate having a driving circuit and a sensor circuit, whereby the coil wound around a stator is connected to the protrusion. In the structure, the protrusion is partially connected to the coil and the unconnected portion thereof absorbs thermal stress, so that disconnection of the coil can be avoided.
According to conventional methods, the connecting structure of the end of the coil wound around the terminal with respect to the substrate is complicated. Furthermore, the end of the coil must be connected to a part of the substrate after the winding operation, whereby many operating steps are required. For example, according to a technique disclosed by Japanese Patent Application, First Publication No. 2001-245455, the coil must be subjected to temporary engaging and removing therefrom, and must be connected to the substrate, so that many operating steps and parts are required.
According to the technique disclosed by Japanese Patent Application, First Publication No. 2007-143295, a protrusion of the substrate is radially protruding, so that the winding operation of the coil around a stator and the winding operation of the end of the coil around the protrusion of the substrate cannot be sequentially performed in an assembling step, and must be performed in individual steps. The reason for this is that, in the above condition, a small Brush DC motor is restricted to have a radially sufficient space and the radial protrusion which can be automatically wound with the coil cannot be easily formed.
In view of the above background of the technique, an object of the present invention is to provide a brushless DC motor in which the winding operation can be easily performed and assembling steps can be reduced compared to conventional techniques.
According to a first aspect of the present invention, the brushless DC motor includes a housing having an upper and a lower housings, a stator including a stator core and a coil wound around the stator core, a rotor rotatably disposed in the stator, an annular terminal block disposed in an axial side of the stator and provided with an axially protruding terminal connected to an end of the coil, a disc-shaped substrate holding the annular terminal block with the stator and provided with a sensor IC and a driving circuit, the substrate provided with a fitting portion closely fitted by the terminal wherein the terminal of the terminal block is closely fitted to the fitting portion of the substrate and the end of the coil is electronically connected to the substrate via a portion in which the end of the coil is connected to the terminal.
According to the first aspect of the present invention, since the terminal is axially protruding, even if the radial space in the structure is restricted, a winding operation with respect to the terminal by the autocontrolled winding apparatus can be easily performed. Therefore, the winding operation of the coil around the stator core and subsequent winding operation of the end of the coil around the terminal of the terminal block can be sequentially performed by an autocontrolled winding apparatus. Positioning of the end of the coil with respect to the terminal portion of the substrate can be completed by axially abutting the terminal block at the substrate and closely fitting of the terminal to the fitting portion of the substrate. Therefore, the end of the coil is easily connected to the substrate. Furthermore, the terminal bock is positioned with respect to the substrate by fitting the terminal of the terminal block to the fitting portion of the substrate, so that the substrate can be easily positioned. Thus, the winding operation in the present invention can be easily performed compared to conventional techniques and a brushless DC motor having reduced producing steps can be obtained.
According to a second aspect of the present invention, the terminal block has an axial protrusion closely fitted into a recessed portion formed on the axially circumferential surface of the stator. According to the second aspect, the protrusion of the terminal block is fitted into the recessed portion of the stator core, so that the stator core is positioned with respect to the terminal block. Therefore, positioning between the sensor IC on the substrate and the stator core can be performed without a special jig.
According to a third aspect of the present invention, the terminal block is made from an insulating material and is integrally molded with the terminal.
According to a fourth aspect of the present invention, in one of the first to the third aspects, the terminal block has a recessed portion in the periphery of the terminal thereof, whereby the coil is connected easily.
According to a fifth aspect of the present invention, in one of the first to the fourth aspects, an end portion of the terminal of the terminal block closely fitted into the substrate is not connected by the coil.
According to a sixth aspect of the present invention, axial dimension of the terminal block except for axial dimensions of the terminal axially formed thereon and the axial protrusion therefrom is defined as “A”, axial dimension of the coil wound around the stator core is defined as “B”, and axial dimension of the stator core is defined as “C”, and “A”, “B”, and “C” satisfy the following formula.
A>(B−C)/2
According to a seventh aspect of the present invention, in one of the first to the sixth aspects, the substrate is provided with a land on the surface facing to the terminal block in the periphery of the fitting portion, whereby the end of the coil which is wound around the terminal is connected to the land via an electrical connection. According to the seventh aspect of the embodiment, the end of the coil connected to the terminal is electrically connected to the land by, for example, soldering or reflowing.
According to the first aspect of the present invention, the brushless DC motor in which the winding operation can be easily performed and assembling steps can be reduced compared to the conventional technique.
According to the second aspect of the present invention, positioning of the substrate with respect to the stator core can be easily performed by closely fitting of the protrusion of the terminal block to the recessed portion of the stator core.
According to the third aspect of the present invention, integrally molded parts are applied, so that the cost of the parts and production thereof can be reduced.
According to the fourth aspect of the present invention, stable winding of the end of the coil and the winding operation by the autocontrolled winding apparatus can be easily performed by using the recessed portion.
According to the fifth aspect of the present invention, the terminal can be accurately fitted into the fitting portion.
According to the sixth aspect of the present invention, the stator can be axially positioned by determining thickness of the terminal block.
According to the seventh aspect of the present invention, electrical connecting of the coil to the substrate can be accurately and reliably performed by using the land.
The shaft 9 of the rotor 11 is rotatably held with respect to an upper housing 13 by a bearing 10a and is rotatably held with respect to a lower housing 14 by a bearing 10b. By this structure, the rotor 11 is rotatable with respect to the upper housing 13 and the lower housing 14.
The upper housing 13 and the lower housing 14 are integrally fixed to each other and form a housing of the brushless DC motor. A stator core 2 is held in the inside of the housing composed of the upper housing 13 and the lower housing 14. The stator core 2 is provided with six pole teeth 2b disposed at an equal angle interval and each pole tooth 2b is wound with a coil 3 working as a stator coil. The permanent magnet 12 of the rotor 11 is faced to the inner circumferential surfaces of the pole tooth 2b of the stator 1 with a gap and the rotor 11 is rotatably disposed in the stator 1.
As shown in
The terminal block 4 is provided with a terminal 4a (4a1 and 4a2) axially protruding toward the substrate 5. The terminal 4a is integrally molded with the terminal block 4. The peripheral portions of the terminals 4a1 and 4a2 are axially notched, whereby the protruding lengths thereof are added with lengths of the notched portions.
The substrate 5 is a substantially disc-shaped electronic substrate in which a through hole penetrated by the shaft 9 is formed at the center thereof. A sensor IC 6 for detecting angular positions of the rotor 11 and a driving circuit (not shown) for supplying a driving current to the coil 3 are provided on the surface of the substrate 5. A notched portion 5a (5a1 and 5a2) to closely fit with the terminal 4a (4a1 and 4a2) is provided on an edge portion of the substrate 5. The notched portion 5a (5a1 and 5a2) is one example of the portion closely fitted by the terminal 4a. A land 5b (5b1 and 5b2) composed of a conductive pattern is provided at the periphery of the edge of the notched portion 5a (5a1 and 5a2) on the surface of the substrate 5. The land 5b is connected to the circuit pattern on the substrate 5.
As shown in
A>(B−C)/2
Furthermore, axial distance between an inner surface of the upper housing 13 and an upper surface of the stator core 2 is defined “D”, and “D” satisfies the following formula.
D>(B−C)/2
Since the values A to D satisfy the above formulas, the stator 1 is axially positioned by the axial dimension (height) A of the terminal block 4 and the coil 3 wound around the stator core 2 is not abutted at the substrate 5 and the upper housing 13.
An example of assembling the structure of the stator is explained hereinafter. First, in the condition shown in
The six pole teeth 2b are wound with a wire and six coils 3 are provided. The terminal 4a1 is wound with an end of the wire at the base thereof before forming the coil 3 and the terminal 4a2 is wound with another end of the wire at the base thereof after forming the coil 3. This operation is performed by an autocontrolled winding apparatus. The above condition of the structure is shown in
The terminals 4a1 and 4a2 of the terminal block 4 are positioned at the notched portions 5a1 and 5a2 of the substrate 5, whereby the terminals 4a1 and 4a2 are fitted thereto. In this operation, the coiled portion 3a is abutted at the land 5b2 (see
As above mentioned, the brushless DC motor of the embodiment, as shown in
According to the above structure, by using the terminals 4a1 and 4a2, treatment of the end portions of the coil 3, electronically connecting of the coil 3 to the substrate 5, and positioning of the substrate 5 with respect to the terminal block 4 are performed. Therefore, assembling steps thereof can be reduced. Furthermore, since the terminals 4a1 and 4a2 are axially protruding, sufficient protruding length of the terminals can be obtained in a limited space and the working operation for winding by an autocontrolled winding apparatus can be easily performed. Therefore, winding operation can be easily performed compared to the conventional technique.
That is, the terminals 4a1 and 4a2 are fitted into the notched portions 5a1 and 5a2, as typically shown in
As shown in
The terminal block 4 is integrally molded with the terminal 4a and is made from the insulating material. In this structure, cost of parts and production cost can be reduced, and high accuracy in the structure of the terminal 4a as a member for positioning can be obtained.
As shown in
As typically shown in
As shown in
A>1/2(B−C)
In this structure, the stator 1 can be axially positioned by the terminal block 4 without the special jig, whereby the assembling steps thereof can be simplified.
As shown in
It should be noted that the notched portion 5a may simply be a recessed portion fitted by the terminals 4a1 and 4a2. Therefore, the notched portion with a bottom, an opening portion with a bottom or an opening portion without a bottom may be applied instead of the notched portion 5a. The above condition of the structure may also be applied to the structure of the positioning recessed portion 2a. The present invention is not limited to the above embodiments and includes variations obvious to those skilled in the art, and effects of the invention are not restricted by the above embodiments. That is, various additions, modifications, and partial omissions are possible within the scope of the concept and the objects of the invention, as claimed and equivalents thereof.
The present invention may be used for brushless DC motors.
Number | Date | Country | Kind |
---|---|---|---|
2010-029669 | Feb 2010 | JP | national |