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  Commutator motorThe Patent Description & Claims data below is from USPTO Patent Application 20070013252. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] The present invention relates to a commutator motor, and more particularly, to a commutator motor which is employed for a power tool or the like and mainly driven by a battery, and is relatively large in size. [0002] As a motor employed for the power tool or the like, a commutator motor is known, and the commutator motor of this type is generally driven by a battery. [0003] Japanese Patent Application Publication No. Hei-11-136883 discloses a commutator motor which is relatively small in size. The commutator motor includes a housing, a stator, an armature, a brush and a commutator, and the stator includes a cylindrical stator yoke which is substantially rectangular columnar in contour and a field magnet. The inner peripheral surface of the stator yoke is circular in a section vertically taken along an axial direction thereof, while an outer peripheral surface of the stator yoke has a rectangular cross-section. The rectangular outer surface portion has four corners, and a yoke section projecting radially outwardly is provided at each corner. A field magnet is disposed between the neighboring two yoke sections. Therefore, there are four field magnets in total which are fixed to positions that are radially outside of the stator yoke and opposite to each other in the diameter direction of the stator yoke. The stator yoke is structured by stacking steel plates on each other, and the field magnet is formed of a permanent magnet. Four field magnetic poles are generated at the stator by the field magnet, and a magnetic field is developed by the four field magnetic poles. [0004] The brush is fixed to the housing through a brush retaining device. The housing is substantially cylindrical and coaxially connected to the stator yoke in an immovable manner. The brush retaining device is disposed on and protrudes radially inwardly from an inner peripheral surface of the housing, and the brush projects inwardly in the radial direction of the housing by the brush retaining device. The brush is electrically connected to a battery that constitutes a power source. [0005] The armature is disposed inside of the stator and includes a shaft, a core and a coil. The shaft is disposed at the position of the axial center of the stator yoke so as to be rotatable with respect to the stator yoke. The core is fixed to the shaft and has a plurality of slots formed therein. A conductor wire is wound around the core while being hooked by the slots, and the wounded conductor wire forms a coil. Also, the substantially columnar commutator is coaxially fixed to the shaft at a position on the shaft opposing the brush, and the shaft is so structured as to rotate together with the commutator and the core. The commutator is electrically connected to the coil and always comes in contact with the brush. An electrical current is supplied to the coil through the brush and the commutator so that a rotational torque is developed in the armature. [0006] In the conventional commutator motor described above, the stator yoke is structured by stacking the steel plates on each other. However, there is no disclosure of a method for coupling the adjacent steel plates to each other in the stacking direction. For example, it is conceivable that the adjacent steel plates are fixed to each other by caulking. However, because the conventional permanent magnet commutator motor is small in size, there is a fear that the steel plates are deformed when concaves and convexes are formed on the steel plates for caulking, and it is actually impossible to fix the steel plates by caulking. Also, because the field magnet is disposed on the radially outer side of the stator yoke, the magnetic flux cannot be effectively utilized, which lowers performance of the motor. SUMMARY OF THE INVENTION [0007] Under the above circumstances, it is an object of the present invention to provide a commutator motor which can effectively utilize the magnetic flux in which steel plates adjacent to each other in the stacking direction are fixed to each other by caulking so as to be coupled to each other to provide a stator yoke. [0008] This and other objects of the present invention will be attained by a commutator motor including an improved stator, and an armature. The stator includes a stator yoke and a field magnet. The stator yoke has a tubular shape and extends in its axial direction and has an inner peripheral surface. The field magnet is fixed to the inner peripheral surface of the stator yoke for providing a field magnetic pole in the stator. The armature is rotatably disposed within the stator. The stator yoke is constituted by a plurality of plate-like annular bodies having iron parts which are stacked on each other coaxially in the axial direction of the stator yoke. Alternatively, the stator yoke is constituted by a plurality of substantially identically configured iron plate-like arcuate bodies disposed at such position as to form a part of virtual annular bodies and which are stacked on each other coaxially in the axial direction of the stator yoke. The plurality of plate-like annular bodies or the plate-like arcuate bodies adjacent to each other in the stacked direction are fixedly connected to each other by caulking. [0009] In the commutator motor of the present invention, because a field magnet is disposed on the inner peripheral surface of the stator yoke, the magnetic flux can be effectively utilized, to thereby provide a high-performance commutator motor. Also, because a plurality of annular bodies or arcuate bodies that are adjacent to each other in the stacking direction are fixedly connected to each other by caulking, it is possible that the stator yoke can be readily manufactured by stacking the plurality of annular bodies on each other. [0010] Also, because a plurality of plate-like annular bodies or arcuate bodies are coaxially stacked in the axial direction of the stator yoke to structure the stator yoke, the thickness of the annular body or arcuate body in the axial direction can be set to a minimum unit, and the number of stacked annular bodies or arcuate bodies is set to a desired number, thereby being capable of arbitrarily setting the length of the stator yoke in the axial direction. Since the number of stacked annular bodies or arcuate bodies can be automatically set in a pressing machine, the setting of the axial length can be easily changed without the necessity of replacing the machine even if the various stator yokes having axial lengths different from each other are to be manufactured. Accordingly, in manufacturing the stator yokes different in the axial length, the costs can be reduced. Also, because the annular bodies or arcuate bodies are manufactured by the pressing machine, the configuration of the annular bodies or arcuate bodies can be made an arbitrary shape by changing the die of the pressing machine. For example, it is easy to partially dispose convex portions or the like on the inner peripheral surface of the annular bodies. BRIEF DESCRIPTION OF THE DRAWINGS [0011] In the drawings: [0012] FIG. 1 is a cross-sectional view showing an essential portion of a commutator motor according to a first embodiment of the present invention; [0013] FIG. 2 is a cross-sectional view taken along a line II-II of FIG. 1; [0014] FIG. 3 is a cross-sectional view showing a stator of the commutator motor according to the first embodiment of the present invention; [0015] FIG. 4 is a side view showing an essential portion in a state where annular bodies are stacked on each other in a stator yoke of the commutator motor according to the first embodiment of the present invention; [0016] FIG. 5 is a cross-sectional view showing a stator of a commutator motor according to a second embodiment of the present invention; [0017] FIG. 6 is a cross-sectional view showing a stator in a commutator motor according to a third embodiment of the present invention; [0018] FIG. 7 is a conceptual view showing a flow of a main magnetic flux and a flow of an armature reaction magnetic flux in the commutator motor according to the first embodiment of the present invention; [0019] FIG. 8 is a cross-sectional view showing a stator of a commutator motor according to a fourth embodiment of the present invention; [0020] FIG. 9 is a cross-sectional view showing a stator of a commutator motor according to a modification to the first embodiment of the present invention; [0021] FIG. 10 is a cross-sectional view showing a stator of a commutator motor according to a first modification to the second embodiment of the present invention; Continue reading... Full patent description for Commutator motor Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Commutator motor patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Commutator motor or other areas of interest. ### Previous Patent Application: Pdc motor-generator Next Patent Application: Transverse flux electrical machine with segmented core stator Industry Class: Electrical generator or motor structure ### FreshPatents.com Support Thank you for viewing the Commutator motor patent info. IP-related news and info Results in 0.44491 seconds Other interesting Feshpatents.com categories: Novartis , Pfizer , Philips , Polaroid , Procter & Gamble , |
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