RU2038675C1 - Small-sized motor rotor and its manufacturing process - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: small-sized motor rotor that has shaft mounting commutator, coil varistor, and ring building up magnetic tension to hold spherical surface of shaft tight against thrust bearing, is characterized in that coil is wound on commutator built up of laminations with projecting portions joined together by means of themoplastic compound. Commutator has slot receiving varistor. End portions of mentioned coil are placed above projecting parts of commutator and shaft is double-step structure. Manufacturing process for this rotor involves winding of coil groups onto cylindrical mandrel followed by their molding. Prior to winding onto mandrel, commutator is installed with its slot accommodating varistor electrically connected with commutator laminations, then coil sections are wound from wire covered with thermoplastic adhesive layer on mandrel, with end portions above projecting parts of commutator, by means of easily removable arbor. In the course of winding, coil leads immediately wound on projecting laminations of commutator and then winding is blown down with hot air for short time not over 20 s for pre-holding of winding turns on mandrel. Rotor is removed from mandrel and mounted on other one heated to 100-150 C; hollow cylinder heated to same temperature is gradually fitted onto coil. Entire assembly is then heated to not lower than 150 C and rotor is held at this temperature for to not lower than 150 C and rotor is held at this temperature for at least 15 min depending on rotor design; then rotor is cooled down to 20 60 C and removed from mandrel; coil leads and commutator laminations are soldered. EFFECT: simplified design of commutator and rotor as a whole; facilitated procedure, reduced labour consumption. 2 cl, 2 dwg

Description

 The invention relates to mechanical engineering, namely to the design and manufacture of a hollow DC motor. Such motors are used when a slight inertia of the rotor is required, associated with a short start time, and increased engine reliability.

 A small-sized engine with a hollow rotor is known, the walls of which are formed by a winding pressed into plastic, the winding has a cylindrical shape. The ends of the winding sections are displayed to the collector, which is mounted on the shaft.

 The disadvantage of this engine is the high complexity of manufacturing, low reliability and the difficulty of automating the manufacture of an engine of this design.

 A small-sized engine is known, the rotor of which contains a shaft with a flange mounted on it for fastening the winding, a collector consisting of a metal contact of complex shape and filled with thermosetting plastic, a varistor mounted on the terminals of the collector and located in the hole formed in the frontal parts of the coil, the coil itself and the ring creating magnetic tension to clamp the spherical surface of the shaft to the thrust bearing.

 The disadvantage of this device is the high complexity of the design, due to the presence of parts of complex shape (collector and flange) made by metal cutting, the relatively large diameter of the working part of the collector, which reduces the reliability of the engine. In addition, such an engine has significant active losses in the frontal part of the coil, due to the presence of holes for installing the varistor. Such an engine design is very difficult to automate.

 A known method of manufacturing a rotor of a small engine by winding coil groups on a cylindrical mandrel having a conical surface on one of the ends, followed by their molding. Before winding onto the mandrel, templates are installed, the number of templates corresponding to the number of reel-up groups being wound, and the inner surface of each part has a recess corresponding to the section profile, then all reel-groups are wound, then the templates are retracted and the winding is fixed with a hollow glass.

 The disadvantage of this method is the high complexity and complexity of manufacture.

 The objective of the invention is to create a simple design of the rotor and simplify the technology of its manufacture. The consequence of solving this problem is to increase engine reliability.

 The problem is solved in the device by the fact that in the rotor of a small engine containing a shaft with a collector mounted on it, a coil, a varistor and a ring that creates magnetic tension to clamp the spherical surface of the shaft against the thrust bearing, the coil is wound on a manifold, which is a lamella fastened together with using thermoplastic mass and having a groove for installing the varistor, the frontal parts of the coil are located on top of the varistor, and the shaft is made in two stages.

 Simplification of the design is achieved due to the fact that the collector is structurally a disk of thermoplastic mass, in which lamellas made, for example, of round wire are fixed. This disk simultaneously performs the function of a collector and a flange for mounting the coil.

 Improving the reliability of the engine by reducing the diameter of the working part of the collector with the simultaneous introduction of a supporting surface for axial loads of the shaft. For this, the engine shaft is made stepped. In the area of the collector, the shaft diameter is reduced, since in this part only axial load is applied to the shaft, and the radial load is practically absent, which makes it possible to reduce the diameter of the shaft in the zone of the collector with respect to the diameter of the entire shaft. The diameter reduction is limited by technological capabilities and a given axial load on the engine axis.

The problem in the method is solved by the fact that in the method of manufacturing a hollow rotor by winding coil groups on a cylindrical mandrel with their subsequent molding, a collector is installed before winding on the mandrel, in the grooves of which are placed a varistor electrically connected to the collector lamellas, then sections of the coil are wound on the mandrel with placement the frontal parts of the coil over the collector assembly using easily removable templates with a wire with a thermoplastic adhesive layer, and during winding the coil leads are immediately wound onto a protrusion guides lamella collector, whereupon winding blowing hot air for a short time (no more than 20) for preliminary fixation of winding turns on the mandrel, the mandrel is removed from the rotor and rearranging the other heated to 100-150 ^{° C,} and gently pushed onto the coil hollow cylinder, also heated to this temperature, and then the entire structure is heated to a temperature not lower than ¹⁵⁰ ° C and held at this temperature for a rotor at least 5 minutes, depending on the complexity of the rotor, then cooled to 20-60 ^{° C,} after which the rotor is recovered and produce soldering coil leads to collector lamellas.

 In the prototype, after the manufacture of the coil, it is necessary to assemble the collector and coil, then fix the conclusions of the coil on the lamellas of the collector and seal the conclusions.

 In the proposed method, the simplification of the manufacturing process of the rotor of a small engine is achieved due to the fact that the coil is wound directly on the collector and not the coil, but the finished rotor is removed from the mandrel.

 Figure 1 shows the rotor of a small engine; figure 2 collector.

 The small-sized engine rotor contains a collector 1, consisting of a stepped shaft 2, lamellas 3, mounted on the shaft using a thermoplastic mass 4, in which a seat for a varistor 5, a coil 6 and a metal ring 7 is made.

 The device operates as follows.

 The rotor is located in the air gap of the electric motor between the cylindrical magnet and the motor housing. Thus, the rotor is in a magnetic field created by a permanent magnet. The current in the coil 6 is fed through the lamellas 3 of the collector. The magnetic field resulting from the passage of current through the coil interacts with the magnetic field of a permanent magnet. As a result of this interaction, electromagnetic forces arise, causing the rotor to move around its axis, i.e. the rotor is rotated.

To manufacture the rotor of a small-sized engine by the proposed method, it is necessary to install a collector on the mandrel, previously made by pressing them into the thermoplastic mass of the lamellas and rotor shaft, then install a varistor in the groove of the collector and draw the templates. After this, sectional winding of the coil on the collector is performed, and after winding each section of the coil, the output of the coil is secured to the corresponding protruding lamella. Winding is carried out with a wire with a thermoplastic adhesive layer. After winding is completed, coil turns are heated with a jet of hot air supplied through a flexible air duct, at the end of which a heater is installed. Blowing is carried out for a short period of time, which is sufficient for the thermoplastic insulation of the wire to soften and coalesce together, i.e. preliminary fixation of coil turns is provided. The final sintering and molding of the coil is carried out on another mandrel preheated, for example, in a heating cabinet. A rotor is mounted on this mandrel, which has openings for the rotor shaft, and a cylinder is inserted onto it, also heated in a cabinet. Preheating of the mandrel and a cylinder of this design reduces the assembly effort and prevents damage to the windings, as at an elevated temperature greater than 100 ^{° C.} ductility provided by winding coils without compromising its integrity. The resulting structure is heated to 175 ± 20 ^about With, for example, in a heating cabinet, and maintained at this temperature for the time required for the final molding of the coil. Then produce cooling structure in air at room temperature to 20-60 ° ^C. Then construct disassembled and the finished rotor is removed, producing the soldering terminals of the coil to the commutator bars.

 If necessary, to increase the rigidity of the rotor design, the frontal parts of the coil are impregnated with low viscosity adhesive, i.e. the frontal parts of the coil adhere to the collector.

Claims (2)

 1. The rotor of a small engine containing a shaft with a collector mounted on it with conductive elements, a coil winding, a varistor electrically connected to the conductive elements of the collector, and an annular element to provide magnetic tension and clamp the spherical surface of the shaft to the thrust bearing of the motor, characterized in that the shaft is made two-stage, the collector's conductive elements are made in the form of lamellas with parts protruding above the collector surface, fastened together by a thermoplastic with the mass, the collector is made with a groove in which the varistor is placed, the winding sections and its frontal parts are placed over the protruding parts of the collector. 2. A method of manufacturing a rotor of a small engine, according to which sections of the coil winding of the rotor are wound on a cylindrical mandrel using a template and their subsequent molding is carried out, characterized in that a collector is installed on the cylindrical mandrel before winding, placed in its groove a varistor, then wound on the collector with a wire with a thermoplastic adhesive layer of the coil winding section with the placement of its frontal parts on top of the collector and at the same time fix the conclusions of the coil coil sections the slots on the protruding parts of the lamellas, then blow the coil with hot air for no more than 20 s to pre-fix the turns of the winding, remove the rotor from the cylindrical mandrel and transfer it to another mandrel, preheated to 100 150 ^o C, smoothly insert the full technological winding onto the coil winding the cylinder is also preheated to the indicated temperature, then the entire structure is heated to a temperature of at least 150 ^o C and maintained at it for at least 15 minutes, then cooled to 20 60 ^o C, the rotor is removed and producing t soldering the conclusions of the coil winding to the collector lamellas.

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