Abstract: An induction motor capable of obtaining a high power characteristic in a wide range without producing induced voltage. A winding for each phase is composed of a plurality of winding components having the same number of turns. When high torque is needed with low speed rotation, a Y-connection in which winding components for each phase are connected in series is formed as shown in FIG. 2a. For medium low speed rotation, a &Dgr;-connection in which winding components for each phase are connected in series is formed as shown in FIG. 2b. For medium high speed rotation, a Y-connection in which winding components for each phase are connected in parallel is formed as shown in FIG. 2c. For high speed rotation, a &agr;-connection in which winding components for each phase are connected in parallel is formed as shown in FIG. 2d. Using the entire winding for each phase, the number of turns is decreased stage by stage to switch from low speed rotation to high speed rotation.

Abstract: A reactor (32) and a switch (35) are interposed in parallel between U-phase, V-phase and W-phase on a power source side (31) and U, V and W terminals on a motor side (33). A changeover switch )37) is interposed between Z, X and Y terminals on the motor side (33) and the U, V and W terminals on the motor side (33). When the switch (35) is set to OFF, the changeover switch (37) is set to ON, and the switch (35) is set up so as to interconnect Z, X and Y terminals, windings of the motor are set up in the form of Y-connection, so that the motor and a power source are connected directly to each other. On the other hand, when the changeover switch (37) is switched over to OFF, and the switch (35) is set up so as to interconnect Z, X and Y terminals to the U, V and W terminals, the windings of the motor are set up in the form of &Dgr;-connection, so that the motor and the power source are connected together through the reactor (32).

Abstract: In a cage rotor for an induction motor, a end ring (22) for connecting conductive rods (20) to one another is covered with a reinforcing member (24). The reinforcing member (24) is obtained by integrally forming a tube-like portion (26) having an inner diameter which is substantially equal to the diameter of a central through hole (14) of a laminated core (26), an annular end wall (28) extending radially outward from one end of the tube-like portion (26) in an axial direction, and an annular engagement wall (30) extending radially outward from the other end of the tube-like portion (26) in the axial direction.

Abstract: The invention relates to an apparatus for casting a conductor of a cage rotor of an induction motor. A rotor core (13) comprising a laminated steel sheets is housed in a recess portion of a casting mold, an upper end portion thereof is held by a holding portion (70) and molten metal is supplied into a plurality of slots formed in the rotor core, thereby forming a plurality of conductor rods and a pair of end rings connecting the ends of the conductor rods with one another. The holding portion (70) comprises a cup (72) and a cylinder (73), and an axial dimension of the cup (72) is selected in correspondence to an axial dimension of the rotor core (13) housed in the recess portion of the casting mold. Further, by using a double cylinder (77, 79) in the holding portion (70), a rotor having higher quality can be obtained. For this reason, the same conductor casting apparatus can be used for casting the conductor of the rotor having different axial lengths and qualities depending on specifications.

Abstract: A stator (76), a rotor (82), and frame bodies (84, 86) to fixedly hold a stator core (74) therebetween in an axial direction are assembled into a motor. Further, a shaft (78) of the rotor and the frame body (86) are mutually coupled through a coupler (106) with no ability for relative rotation. While integrally rotating the frame bodies (84, 86), the stator (76), and the rotor (82) forming the motor about an axis of the rotor (82), a lathe is used to machine mounting surfaces (96a, 100a) of the frame body (84), which will be in direct contact with a surface of an object on which the motor is mounted.

Abstract: A rotor core (12) of a squirrel-cage rotor of an induction motor is housed in a recess (14) of a mold (18) of a conductor casting apparatus (10). A composite cylinder device (68) is fixed on the upper side of the mold (18) or on the side remoter from the pouring gate thereof, and the rotor core 12 is held in a predetermined position in the recess 14 by one piston (70). The other piston (72) locally pressurizes a molten metal that fills an end-connector ring cavity (66) defined between the rotor core (12) and the recess (14) on the side remoter from the pouring gate.

Abstract: An air-cooled type electric motor (20) includes a rotor, a stator includes a stator core (28), and a front support member (32) and a rear support member (34) arranged at both axial ends of the stator core (28). A plurality of air passages (42), extending continuously in an axial direction, are provided in the stator core (28), the front support member (32), and the rear support member (34). A centrifugal blower unit (50) is placed at further rear side of the rear support member (34). Because the centrifugal blower unit (50) has a large pressure rise, air, surrounding the motor and sufficient to cause an effective cooling, can be made to flow into the air passages (42) with a smaller diameter. A drive section (56) of the blower unit (50) is fixed directly to the rear support member (34) by bolts (72). Consequently, an electric wire (74) for the drive section (56) extends through the interior space of the motor (20), and is connected to a terminal box (48).

Abstract: A method and apparatus for controlling an induction motor having at least high speed windings and reduced speed windings divides the reduced speed windings into first and second portions. The first and second portions of the reduced speed windings are electrically connected in series and a voltage is applied to the first and second portions of the reduced speed windings when it is desired to operate the induction motor at a reduced speed. The first and second portions of the reduced speed windings are electrically disconnected and a voltage is applied to the high speed windings when it is desired to operate the induction motor at a high speed. The induction motor has three sets of windings extending from a middle region, each set of windings having an inner winding toward the middle region and an outer winding away from the middle region.

Abstract: An electric motor includes a covering member for covering the outer periphery of a stator core, to improve the cooling efficiency of an air-cooling system of the motor. The covering member is fixed to a stator while defining a cavity therebetween in fluidic communication with air passages formed directly in the stator core. When an blower unit mounted on the motor operates, an ambient air surrounding the motor is introduced into the cavity, and then flows from the cavity into the air passages, so as to actively absorb heat generated in the stator from the outer peripheral surface of the stator core and the tubular wall surfaces of the air passages. Thereafter, the air is discharged from the air passages out of the motor.

Abstract: A terminal box for a motor is made of a thick plastic plate and includes a plurality of closed windows provided on the terminal box. Each of the closed windows is made of a thin plastic plate. The plurality of closed windows are each surrounded by a groove which is one of a plurality of concentric circular grooves. The terminal box is also provided with a plurality of radial linear grooves passing through a center of the concentric circular grooves to produce an open window for positioning a conduit therein when one of the plurality of closed windows is broken.

Abstract: A multi-function machine tool provided with a motor-driven spindle on which each of a plurality of sub-motor units having individual drive motors and tools, respectively, can be removably mounted to perform a plurality of machining operations in order to comply with a change in the machining conditions and a change in the material of workpieces to be machined. The drive motors of the sub-motor units exert different output performances, i.e., different rated rotating speeds and different output torques, and can be electrically connected to the electric powers lines and control signal lines provided for the spindle head.

Abstract: An improved supporting arrangement for a bearing in an electric motor is provided for preventing the development of fretting corrosion. The electric motor comprises a housing, the housing including a longitudinal axis and bores at either end thereof so that the bores are aligned to the longitudinal axis, a rotating shaft extending along the longitudinal axis through the bores, and bearings for rotationally supporting the rotating shaft at either end thereof, the bearings being provided within the respective bores.

Abstract: A squirrel-cage rotor 10 includes a plurality of slots 16 for accommodating secondary conductors 18 along the outer circumferential surface of a laminated core 14 fixed to a rotor shaft 12. Each slot 16 is defined by a wall having a generally elliptical profile in which a maximum circumferential distance D is larger than a maximum radial distance d in a given section orthogonal to an axis and axially penetrates near the outer circumferential surface of the laminated core 14. The radial inner profile of the slot 16 has a shape in which the tangents on given two points adjacent to the radial innermost portion of each slot wall do not cross at an acute angle in a section orthogonal to the axis, in order to prevent a stress concentration.

Abstract: An air-cooled motor having cooling-air passages each formed by a plurality of small ventilation passages extending through a front housing, a stator, and a rear housing, constructed in one piece. Cuttings are prevented from being accumulated at inlets of cooling-air passages. For example, the cooling-air passages are formed of ten small ventilation passages, each defined between adjacent ones of eleven ribs each forming part of the stator. All the eleven ribs are provided with respective front housing ribs. End faces of the front housing ribs on the cooling-air inlet side are uniform in height, and positioned in an identical plane. Cooling air flows into the small ventilation passages in the direction of an arrow.

Abstract: A holding member (22) which can hold a predetermined axial-length laminated core member by pressing down both axial end faces thereof is used to hold a short laminated core member (24) and a spacing element (48) having a thickness generally equal to the difference between the axial lengths of those laminated core members. The spacing element is disposed at a position between one axial end face of the laminated core member (24) and a lid element (32) of the holding member (22). The laminated core member (24) and the spacing element (48) are both held by the holding member (22) and are introduced into the mold (20) to form a conductor portion integrally with a predetermined axial-length laminated core member held by the holding member (22). In this state, molten metal is poured into slots (38) of the laminated core member (24) and annular cavities (44, 46), and thus a conductor portion is formed integrally with the laminated core member (24) when the molten metal is set.

Abstract: A method of producing a squirrel-cage rotor for an induction motor, which includes a plurality of secondary conductors arranged respectively in through holes (16) of a laminated core (14), and a pair of end rings connecting the secondary conductors with one another at both axial ends of the laminated core (14). Each of a pair of reinforcing members (22) includes a cylindrical wall (26), an annular multi-aperture wall (28) provided with apertures (32) and extending in a radial inward direction from one edge of the cylindrical wall (26), and an annular end wall (30) extending generally parallel to the multi-aperture wall (28) in a radial inward direction from another edge of the cylindrical wall (26). Each reinforcing member (22) is arranged in a manner in which the multi-aperture wall (28) is brought into contact with one of the axial end faces of the laminated core (14) while the apertures (32) communicate with the through holes (16).

Abstract: Liquid cooled stator jacket and a method for extruding a billet of aluminum alloy to form a stator jacket. The billet of aluminum alloy is extruded to form a plurality of conduits along the longitudinal direction of the billet and to form a plurality of thickness lightening holes along the longitudinal direction of the billet. The thickness lightening holes are equally spaced in a circumferential direction of the billet and the conduits are arranged on both sides of each of the thickness lightening holes.

Abstract: A squirrel-cage rotor (10) includes a laminated core (14) fixed to a rotor shaft (12), a plurality of secondary conductors (18) arranged respectively in a plurality of through holes (16) formed through the laminated core (14), a pair of end rings (20) connected to the secondary conductors (18) at axial ends of the laminated core (14), and a pair of reinforcing members (22, 23) respectively covering the end rings (20). The secondary conductors (18) and the end rings (20) are integrally formed through a casting process, and are connected with the laminated core (14) and the reinforcing members (22, 23).

Abstract: A rotor 14 for a high speed induction type ac motor having a construction such that the rotor is provided with an iron core 20 provided, at the periphery thereof, with a plurality of through-bores 22 in which electro-conductive rods 24 made of aluminum rod members are forcibly inserted in a press-fitting manner so as to form opposite projections from the axial opposite ends of the iron core 20, electro-conductive end rings 26 connected to the projections of the electro-conductive rods 24, and slitted pins 30 press-fit in small blind bores 32 formed in the projections of the electro-conductive rods 24 to thereby fixedly attach the electro-conductive rings 26 to the opposite end faces of the iron core 20.

Abstract: A control method and apparatus for actuating an induction motor which is capable of generating a sufficiently large output in a wide speed region. In such an induction motor, each of Y-connection phase windings of the induction motor is divided into two split windings 5t and 3t at a predetermined split ratio (for example, 5:3). When a rotational speed of the induction motor is in a low speed region, only the changeover switch MC2 is turned on to supply exciting current to both of the split windings 5t and 3t. When the rotational speed of the induction motor is in a middle speed region, only the changeover switch MC3 is turned on to exclusively supply exciting current to the split windings 5t. Furthermore, when the rotational speed of the induction motor is in a high speed region, only the changeover switch MC1 is turned on to exclusively supply exciting current to the split windings 3t.