Patent Publication Number: US-2006010938-A1

Title: Monoblock rotor for a washing machine

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application claims the benefit of Brazilian Utility Model Application Serial No. MU8401086, filed May 24, 2004, which is incorporated by reference in its entirety herein. This application is also related to Brazilian Utility Model Application Serial Nos. MU8400819 and MU8400820, both filed Apr. 29, 2004, which are incorporated by reference in their entirety herein.  
     FIELD OF THE INVENTION  
      The present invention is generally an improved monoblock rotor for interconnection to a shaft that drives an agitator of a washing machine. More specifically, one embodiment of the present invention utilizes a monoblock rotor for operable interconnection, via a plurality of pins, to epicycloidal gears that are part of a gearbox that is responsible for the oscillatory and gyrational motions of washing machine tubs.  
     BACKGROUND OF THE INVENTION  
      It is widely known that household appliances offer great help in the performance of various domestic chores. With respect to clothes washing, the technical sphere has developed vertical and horizontal machines that include tubs equipped with motor driven shafts that perform balancing and rotational agitating motions to clean and substantially suction water from the clothes being cleaned. Generally, a cylindrical container that receives the clothes is coupled to a primary shaft whose outer perimeter is coupled to a centrifuging mechanism and to the tub. An inner perimeter of the primary shaft is operably interconnected to a secondary shaft that links a central washing machine agitator, e.g., for vertical washers, to an oscillatory motion mechanism.  
      The gearbox responsible for the oscillatory and gyratory motions of the agitator and the cylindrical container is made up of a cylindrical housing equipped in its inner perimeter with an annular gear, which meshes with epicycloidal gears that are formed in a planetary assembly that are rotatably interconnected to a rotor in the form of a “clover.” The rotor is operably interconnected to the secondary shaft that is interconnected to the central washing agitator. In addition, the rotor is provided on one end with four perpendicular pins positioned on each branch of the clover that are adapted to rotatably bear four identical planetary gears. The planetary gears have teeth that interface with the teeth of the annular ring and with teeth of a sun gear. The sun gear is coupled to the end of a third shaft that projects through a central part of the primary shaft and which is given oscillatory motion by the machine=s transmission gearbox. The gearbox proportions are such that the planetary gears follow the rotational motion of the sun gear in the same direction, but at a lower speed.  
      In its ordinary form, the abovementioned works acceptably, and has satisfactory durability. However, with respect to the clover-shaped rotor, there are inconveniences in relation to the components production process, since the rotor pins that bear the planetary gears need to be perfectly perpendicular to each other and positioned at right angles to the rotor. If this minimum tolerance is not met, the synchronism of the system and the gearbox=s freedom of movement will be impaired. Currently, the clover-shaped rotor is manufactured by sintering, i.e., molded by compressing a mixture of powdered alloys to form a hard coherent mass. Holes in the rotor are obtained by the protuberances and cavities properly positioned in the mold, thus eliminating the need for later perforation. The part obtained meets the design=s dimensional tolerances, however, after a subsequent heating process that hardens the part, the holes may become warped due to structural settling and stress relief of the sintered mass=particles. These aberrations generally cause a deviation in parallelism, including deviation of the right angle between the pins and the rotor, thereby impairing the performance of the mechanical component when assembled in the gearbox. Further, the millimetrical difference in parallelism between the four perpendicular pins and, consequently, between the planetary gears, the sun gear and/or the annular gear will result in cracking, splitting and the occurrence of other defects that lead to rejection of parts or premature failure. Finally, the sintering process is complex and has several stages of execution, in addition to using materials and equipments of high cost, such as presses and kilns.  
      Thus, it is a long felt need in the field of washing machines to provide a strengthened rotor that is not prone to early failure and is cost effective to produce. The following disclosure describes an improved monoblock rotor in the shape of a clover that is constructed preferably of a phenolic-based, high-resistance polymer.  
     SUMMARY OF THE INVENTION  
      It is an aspect of the present invention to provide a rotor for use in a washing machine gearbox that is low cost, feasible to produce, robust, safe and practical by reducing the number of manufacturing steps.  
      It is another aspect of the present invention to provide a manufacturing method that contributes towards better accuracy in the fabrication of perpendicular pins that are interconnected to the rotor. Further, one embodiment of the present invention includes a manufacturing process that reduces the number of steps and enables insertion of a secondary shaft in the injection mold itself, thus reducing costs of the entire operation.  
      It is still yet another aspect of the present invention to provide a rotor that is more efficient, longer lasting, light and would lower production costs, conveniently embodied and arranged to perform its functions with unmatched sufficiency and versatility, without the above-described drawbacks.  
      It is yet another aspect of the present invention to provide a process to construct a polymeric monoblock rotor with all the aesthetic and functional qualities of those known in the prior art however designed and developed according to the latest method of forming. More specifically, one embodiment of the present invention is formed using high-resistance polymer to construct a one-piece component that includes the rotor wherein at least four pins radiate perpendicularly therefrom to provide locations for the rotatable interconnection of planetary gears. One skilled in the art will therefore appreciate that the present invention is extremely simple in construction and quite feasible, nevertheless possesses excellent practical and functional results with an innovative construction compared to known methods.  
      Thus, it is one aspect of the present invention to provide a monoblock rotor which comprises: 
          a rotor having at least one appendage depending from a centralized hub; and     a pin emanating substantially perpendicular from said at least one appendage, said pin adapted for rotatable interconnection to a planetary gear of an epicycloidal gearing system.        

      The Summary of the Invention is neither intended nor should it be construed as being representative of the full extent and scope of the present invention. The present invention is set forth in various levels of detail in the Summary of the Invention as well as in the attached drawings and the Detailed Description of the Invention and no limitation as to the scope of the present invention is intended by either the inclusion or non-inclusion of elements, components, etc. in this Summary of the Invention. Additional aspects of the present invention will become more readily apparent from the Detail Description, particularly when taken together with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and together with the general description of the invention given above and the detailed description of the drawings given below, serve to explain the principles of these inventions.  
       FIG. 1 —is a front sectional view of a typical washing machine;  
       FIG. 2 —is a bottom perspective view of a shaft that includes a monoblock rotor;  
       FIG. 3 —is a partial perspective view of the monoblock rotor;  
       FIG. 4 —is a front view of the embodiment shown in  FIG. 2 ;  
       FIG. 5 —is a bottom plan view of the embodiment shown in  FIG. 2 ;  
       FIG. 6 —is a top plan view of the embodiment shown in  FIG. 2 ; and  
       FIG. 7 —is a perspective view of an injector, illustrating the monoblock rotor, after being injected directly to the end of the shaft.  
    
    
      It should be understood that the drawings are not necessarily to scale. In certain instances, details that are not necessary for an understanding of the invention or that render other details difficult to perceive may have been omitted. It should be understood, of course, that the invention is not necessarily limited to the particular embodiments illustrated herein.  
     DETAILED DESCRIPTION  
      Referring now to  FIGS. 1-6 , vertical washing machines  5  generally utilize a gearbox  7  that is equipped in its inner perimeter with an annular gear that meshes with four planetarily arranged epicycloidal gears that are rotatably interconnected to a rotor  4  via perpendicular shafts  3 . The rotor  4  is in turn connected to a secondary shaft  2  that is connected to a central washing agitator  9 . The teeth of the epicyclodal gears interface with those of the annular ring and the teeth of a sun gear. As the sun gear rotates, the planetary gears rotate in the same direction, but at a slower speed. The sun gear is coupled to the end of a shaft that projects through a central part of the cylindrical gearbox housing  7  and which is oscillated by a transmission assembly of the washing machine  5 . The cylindrical gearbox  7 , together with an outer primary shaft  10 , is also coupled to the perimeter of a centrifuging mechanism and to the tub  12  of the washing machine  5 .  
      Referring specifically now to  FIGS. 2-6 , a shaft and rotor for use with the washing machine  5  is shown. More specifically, a monoblock rotor assembly  1  is provided that is preferably made of a phenolic-based, high-resistance polymer injection molding. The injection process also provides pins  3  associated perpendicularly to the clover-like branches  4  of the rotor  1 . The pins provide locations for the four identical planetary gears, whose teeth mesh with teeth of the annular teeth located on an inner periphery of the gearbox  7 . The teeth of the planetary gears also interface with teeth of a sun gear that is operably interconnected to the transmission system of the washing machine  5 .  
      Referring now to  FIG. 7 , an injector for fabricating a one-piece monoblock rotor as shown. More specifically, one embodiment of the present invention includes a rotor that is directly molded onto the secondary shaft. Here, the high-resistance polymer material is injected directly into a mold that is placed adjacent to one end of the secondary shaft, thereby producing a monoblock rotor onto that end of the shaft after molding is completed. This method of construction necessarily will reduce the steps required in fabricating a washing machine gear box.  
      While various embodiment of the present invention have been described in detail, it is apparent that modifications and alterations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and alterations are within the scope and spirit of the present invention, as set forth in the following claims.