A full winding pitch would possess a value of 6 with a throw of 1 to 7. In addition, the outer circumferential surface of the stator core is formed with fixation grooves for fixing the core sheets and alignment grooves for mounting the stator core on a housing of the electric motor as well as the engaging grooves with which the tool is engaged.
Winding Factors for Different Winding Patterns.
It is used extensively in step motors and switched-reluctance motors. Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims.
This pattern places two adjacent coils strategically and equidistantly around the stator with each of the three phases having one set of two adjacent coils and three sets of single coils pattern from Veinott and Martin, These factors can be identified as follows: As described above, since the slots 6 are formed in a skewed state in stacking the core sheets, special operation and device for skewing the core sheets are not needed.
As described above, a plurality of core sheets are formed so as to stepwise shift the corresponding recesses formed in the outer edges of the core sheets coil slot forming the same groove from each other with respect to the slot openings 15 formed in the inner edges by a predetermined angle, and the core sheets are stacked so that the slots 6 are located parallel to the axis L, and the coil 7 is inserted into the slots 6.
Note the shorter length of these coils because the end turns are shorter while the segments of the turns conductors within the appropriate stator slots remain the same length. The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: This group of fractional-pitch windings has a pitch less than 1 when an even stator slot count is employed.
A coil not shown is inserted into the slots 6 of coil slot stator core 1 thereby to form the stator. This winding pattern is used in larger three-phase ac motors to decrease the harmonic content of both the voltage and mmf waveforms. The core sheet 10 has an inner edge 10 a and an outer edge 10 b thereof.
The alignment grooves 4 are used for positioning the stator core 1 in mounting the stator core 1 on a housing of a motor not shown. The stator core 1 is so formed that a plurality of core sheets each of which has a disc-like shape are stacked.
The fixation grooves 3 are used for fixing the stacked core sheets by welding. The grooves 2, 3 and 4 are in parallel with the axis L of the stator core 1. This causes the grooves 2, 3 and 4 to be aligned without wave, thereby to skew the slots 6 without wave. The method of forming the stator according to the second embodiment will now be described with reference to FIG.
Furthermore, since the fixation grooves 3 are located parallel to the axis L, the torch is moved vertically upon welding, which prevents cost rise of welding equipment. Each core sheet also has a plurality of recesses formed in the outer edge thereof thereby to form a plurality of engaging grooves in the outer circumferential surface of the stator core.
The starting points for the coils must meet the pattern of coil placements shown. Subsequently, an engaging tool 20 is engaged with the engaging groove 2 for skewing the core sheets.
Three of the core sheets are shown in FIG. The average of these two variable-pitch coils should equal the integral winding pitch for a 3-phase 2-pole slot design, which is 6. Three is selected for the pattern shown in Fig. The stator according to claim 1wherein the groove is used for skewing the core sheets.
The stator core 1 is formed of a cylindrical shape and has a hollow portion 8 formed of a cylindrical shape. The slots are in parallel with an axis of the stator core, in which a coil is inserted. The coil is inserted in the slot.
The concentric winding with variable pitch has been used extensively in larger integral-horsepower units, particularly by the various electric winding repair houses. Adjacent recesses coil slot, 12 have a pair of recesses 13, 14 in the middle thereof, which are adjacent to each other, and therefore, four pairs of the recesses 13, 14 are formed in the outer edge 10 b.
The stator according to claim 1wherein the groove is used for fixing the stacked core sheets by welding. Note the position of the teeth for the slot stator. Furthermore, since the alignment grooves 4 are located parallel to the axis L, a positioning pin can be easily inserted into the alignment groove 4 in mounting the stator on the motor housing not shownwhich improves positioning accuracy.
Thus, the slots 6 are formed in a skewed state. The stator core has a groove formed in an outer circumferential surface thereof and a slot in which the coil is inserted. The outer circumferential surface of the stator core 1 is formed with four engaging grooves 2, four fixation grooves 3 and four alignment grooves 4. This winding pattern will reduce end-turn height and coil lengths by 10 to 15 percent.
Also, a method of forming a stator according to the present invention provides the following second features. A nine-slot eight-pole winding is very popular, as well as a nine-slot six-pole. That is, although the grooves 2, 3 and 4 formed in the outer circumferential surface are inclined with respect to the axis L by stacking the core sheets so as to align the slot openings 15, the slots 6 coil slot by aligning the corresponding slot openings 15 are inclined with respect to the axis L by locating the three grooves parallel to the axis L.
This technique is very similar to that of short-pitch lap windings used in brush dc motors.