Abstract:
An electric hair cutting apparatus having a motor for rotating a shaft, which, rotates an eccentric about the axis of the shaft, but not about the central axis of the eccentric, A cylindrical bearing is positioned around the eccentric. A drive tip is provided with a follower end which is shaped and positioned to engage with the bearing surrounding the eccentric. As the eccentric rotates, the bearing alternately pushes on left and right arms of the follower end of the drive tip, causing the drive tip to oscillate back and forth about a pivot point, The angle of the bearing with respect to the eccentric allows for generally continuous contact between the arms of the follower end of the drive tip with the bearing, even throughout the pivoting of the drive tip.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an electric hair cutting apparatus and, more particularly, to an apparatus including a bearing angled with respect to the eccentric on which it resides, to maintain flush contact with the follower surface of the drive tip. 
     BACKGROUND OF THE INVENTION 
     In general, an electric hair cutting apparatus includes a fixed primary blade and a secondary reciprocating blade. A motor causes the reciprocating blade to move side-to-side with respect to the fixed blade, trimming any hair therebetween. Often, an eccentric is used to translate straight-line rotation created by the motor into the side-to-side motion needed to move the reciprocating blade. A shaft from the motor, which rotates about its central longitudinal axis, is generally connected to the eccentric. In some constructions, the shaft is connected to the eccentric at a position which is off-center from the central axis of the eccentric, such that rotation of the shaft causes the eccentric to revolve around an axis other than the central axis of the eccentric. This off-center rotation of the eccentric can be used to induce side-to-side motion of the reciprocating blade. 
     However, mechanically translating the rotational motion of the eccentric into side-to-side motion generally involves physically contacting the eccentric (or a flange extending from the eccentric) with another component, such as a drive tip, which drives the reciprocating blade. As the eccentric rotates, it physically pushes on the drive tip, creating a point of wear. Further, maintaining proper contact between the eccentric and the drive tip can be somewhat difficult. The wear and tear, as well as loose hair build-up can cause inefficient or ineffective contact with the eccentric. 
     Further, as the eccentric rotates, it inherently creates a moving center of mass for the clippers. This is felt as a vibration to the user, due to the high RPM at which the eccentric is rotating. Such vibration is undesirable to users. 
     It is therefore desirable to provide a hair cutting apparatus with less wear and tear on the internal components, and which exhibits less vibration during use. 
     SUMMARY OF THE INVENTION 
     The present invention includes an electric hair cutting apparatus including an angled eccentric bearing. In one embodiment, a shaft extends from a motor, and interfaces with an eccentric off-center from the central axis of the eccentric. As the motor causes the shaft to rotate, the shaft in turn causes the eccentric to rotate about the axis of the shaft, but not about the central axis of the eccentric. A cylindrical bearing is positioned around the eccentric such that the central axis of the bearing is at a slight angle with respect to the central axis of the eccentric. A drive tip is provided with a follower end and a blade end and pivot point therebetween. The follower end of the drive tip is shaped and positioned to engage with the bearing surrounding the eccentric. As the eccentric rotates, the bearing alternately pushes on the left and right arms of the follower end of the drive tip, causing the drive tip to oscillate back and forth about the pivot point. The angle of the bearing allows for generally continuous contact between the arms of the follower end of the drive tip with the bearing, even throughout the pivoting of the drive tip. The pivoting motion of the drive tip causes its other end—the blade end of the drive tip, to oscillate back and forth as well. The blade end of the drive tip is connected to the reciprocating blade, which causes the reciprocating blade to oscillate back and forth as well. 
     Additionally, the moving parts of the apparatus are preferably supported by a front motor housing. By positioning dampers between the external housing of the apparatus and the front motor housing, much of the vibration caused by the movement of the eccentric, blades, etc., can be reduced before it reaches the housing and the user. By supporting substantially all of these components with the front motor housing, none of the moving components interact the external housing directly. Thereby, the additional dampers are able to act upon substantially all vibrations caused by such components. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front elevation view of electric hair clippers according to an embodiment of the present invention. 
         FIG. 2  is a front elevation view of the electric hair clippers of  FIG. 1 , with the front portion of the outer housing removed. 
         FIG. 3  is a close-up view of the drive tip and eccentric of  FIG. 2 . 
         FIG. 4A  is a close-up view of a drive tip with the pivot shaft exposed, with the drive tip and eccentric in a first position. 
         FIG. 4B  is a close-up view of a drive tip with the pivot shaft exposed, with the drive tip and eccentric in a second position. 
         FIG. 5  is a perspective view of a drive tip. 
         FIG. 6  is another front elevation view of electric hair clippers, with the front portion of the outer housing removed. 
         FIG. 7A  is an internal view of the front portion of an outer housing. 
         FIG. 7B  is an internal view of the back portion of an outer housing. 
         FIG. 8A  is a top view of a hood connected to the housing. 
         FIG. 8B  is a bottom view of the hood. 
     
    
    
     It should be understood that the present drawings are not necessarily to scale and that the embodiments disclosed herein are sometimes illustrated by fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted. It should also be understood that the invention is not necessarily limited to the particular embodiments illustrated herein. Like numbers utilized throughout the various figures designate like or similar parts or structure. 
     DETAILED DESCRIPTION 
     Referring now to the drawings and, more particularly, to  FIG. 1 , a front elevation view of an electric hair cutting apparatus  1  according to the teachings of the present invention is shown. Electric hair cutting apparatus  1  includes a housing  10  which is generally hollow and houses the internal workings of the apparatus  1 . A manual switch  15  is provided for turning the apparatus  1  on and off. The switch  15  may also include various speed settings. At one end of the apparatus  1  are the fixed blade  20  and the reciprocating blade  25 , as is known in the art. The reciprocating blade  25  oscillates back and forth, left and right, so as to cut hair which enters between the teeth of the blades  20 ,  25 . 
       FIG. 2  is a front elevation view similar to  FIG. 1 , but with one side of housing  10  removed for better viewing of the internal workings of the apparatus  1 . As can be seen, housing  10  houses a drive tip  30 , which interacts with a bearing  50  around an eccentric  40 . The eccentric  40  is mechanically connected to a motor  60  by shaft  45 , such that motor  60  causes the eccentric  40  to rotate via shaft  45 . Actuation of switch  15  allows electricity to flow into and power the motor  60 , which, through a series of events and mechanisms described hereinbelow, causes the reciprocating blade  25  to oscillate relate to the fixed blade  20 . 
     As can be seen in  FIG. 3 , the drive tip  30  has two ends—a blade end  32  and a follower end  36 —separated by a pivot point  35 . The blade end  32  includes a groove  34  for accepting a flange connected to the reciprocating blade  25 . Thereby, movement of the blade end  32  of the drive tip  30  causes movement of the reciprocating blade  25 . The follower end  36  of the drive tip  30  includes left and right arms  38 A,  38 B with respective internal follower surfaces  39 A,  39 B. The arms  38 A,  38 B extend from the drive tip  30  on opposing sides of the eccentric  40  and bearing  50 . Follower surfaces  39 A,  39 B of arms  38 A,  38 B may stay generally in continuous contact with the bearing  50  as it rotates. 
     As can be seen in  FIGS. 4A and 4B , shaft  45  extends from motor  60  to eccentric  40 , but does not connect to eccentric  40  at the central axis B of eccentric  40 . Rather, shaft  45  connects to eccentric  40  off center, such that eccentric  40  rotates about the longitudinal axis A of shaft  45  but not central axis B of eccentric  40 . Thus, the shaft  45  divides the eccentric  40  into a major portion  42  which extends ftom the center of rotation A to the farthest edge of the bearing  50 , and a minor portion  43  which extends from the center of rotation A to the nearest edge of the bearing  50 , as shown in  FIG. 4A . 
     Thus, as the shaft  45  causes the eccentric  40  and bearing  50  to rotate about axis A, the anus  38 A,  38 B follow the movement of the eccentric  40  and bearing  50 . For example, in  FIG. 4A , the major portion  42  is positioned toward the left arm  38 A, such that the drive tip  30  has pivoted toward the left arm  38 A. Similarly, in  FIG. 4B , the major portion  42  has rotated so as to be positioned toward the right arm  38 B, such that the drive tip  30  has oscillated and pivoted toward the right arm  38 B. The drive tip  30  is thereby caused to pivot about the pivot point  35  by the rotation of the eccentric  40  and bearing  50  about axis A. 
     Additionally, the bearing  50  is preferably positioned on the eccentric  40  at an angle such that the central bearing axis C passes generally through the pivot point  35 , As will be understood, when the drive tip  30  pivots about the pivot point  35 , the angle of the arms  38 A,  38 B changes relative to the axis of rotation A of the shaft  45 . Angling the bearing  50  so that its central axis C passes through the pivot point  35  causes the bearing  50  to remain perpendicular to the longitudinal axis of the drive tip  30  throughout oscillation of the drive tip  30  and rotation of the eccentric  40  and bearing  50 . This allows the follower surfaces  39 A,  39 B of arms  38 A,  38 B to remain parallel with the side wails of the bearing  50 , for better contact and less wear therebetween. 
     Without angling the bearing  50  on the eccentric  40 , the bearing  50  would not remain perpendicular to the drive tip  30  as the drive tip  30  oscillates. In such a situation, the follower surfaces  39 A,  39 B of arms  38 A,  38 B would be flush with the side-walls of the bearing  50  only when the longitudinal axis of the drive tip  30  is parallel with the axis of rotation B of the eccentric  40 . When the drive tip  30  is not in line with this axis B, the follower surfaces  39 A,  39 B of arms  38 A,  38 B would not make flush contact the bearing  50 , and instead would contact the bearing  50  at a relatively small point. This minimal contact would increase loading and wear at the small contact point, and reduces wear to avoid or delay the onset of excessive wear opening the cap between the parts, and a decrease in sweep of the drive tip  30 . Similarly, angling the bearing  50  is preferably to curving the outer surface of the bearing  50  for similar reasons—the loading and wear at the point of contact would be higher than desired. 
     Bearing  50  may be removable from eccentric  40  for easy replacement, or may be integral with eccentric  40  such that replacement requires replacing the eccentric  40  as well. The bearing  50  is flushingly mounted about the eccentric  40  so as to prevent hair build-up between the hearing  50  and the eccentric  40 . Additionally, a weight could be added to the eccentric to counterbalance the mass of the reciprocating blade  25  to reduce vibration. However, it should he understood that increasing the weight of the eccentric  40  will also create a greater load on motor  60 . Similarly, weight may he added to the follower end  36  of the drive tip  30  to counterbalance the mass of the reciprocating blade  25  to reduce vibration. Again, however, adding such weight would create a greater load on motor  60 . As such, the weight of the eccentric  40  and/or drive tip  30  may be user adjustable, either by replacing these components with lighter or heavier components as desired, or by physically adding weights to existing components as desired. 
     In this regard, drive tip  30  may be structured and adapted for tool-less removal. In one embodiment as shown in  FIGS. 4A and 4B , the drive tip  30  pivots about a pivot shaft  80 . As can he better seen in  FIG. 5 , a drive tip retainer  70  is attached to the drive tip  30 . Projections  75  extend into the hollow column of the drive tip  30  through which the pivot shaft  80  extends. When installed, the projections  75  snap into a groove in the pivot shaft  80 , allowing the user to remove the drive tip  30  without tools. Alternatively, the drive tip may he secured in place by a screw or the like. Preferably, the drive tip  30  is concentric in shape, and may be sized and shape to be used in a range of blade drive pockets of various hair clippers. 
     The drive tip  30  can include a relief cut, living hinge, which allows the drive tip  30  to be fit snugly into a range of blade drive pockets. The relief cut in the drive tip  30  allows for fitting in a large sized drive pocket without deflection of a portion of the drive tip  30 , and for fitting a small size drive pocket by a deflection in at least a portion of the drive tip  30 . The snug fit of the drive tip  30  in the blade drive pocket reduces the noise and vibration produced therein. 
     Apparatus  1  may also include a front motor housing  90 . Front motor housing  90  houses or is attached to the motor  60 . In one embodiment, as shown in  FIG. 6 , front motor housing  90  supports the drive mechanisms of the apparatus  1 . Front motor housing  90  may include pivot shaft  80 , or pivot shaft  80  may be attached to front motor housing  90 . The pivot shah  80  may be further reinforced by a cross bar  85 , which may also be a part of or attached to the front motor housing  90 . By using the front motor housing  90  as the support mechanism for the pivot drive mechanism discussed above, the tolerance loop is shortened, allowing for a tighter fitting mechanism with better wear properties for its components and better overall quality. 
     The front motor housing  90  may be made of zinc, or another suitably strong metal. Additionally, zinc is preferred because of its weight. Weight, along with sweep and speed are the three main factors that significantly affect vibration. Placing much of the weight of the apparatus  1  close to blades  20 ,  25  via the front motor housing  90 , vibration can be greatly reduced. The metal front motor housing  90  also helps to dissipate heat out from the apparatus  1 . Some prior art hair clippers have attempted to vent heat down the sides of the clipper, but have had problems with hair entrapment, excess noise and an unwanted breeze. Without any heat dissipation, the clipper will maintain a higher temperature and have a shorter life. Thus, the metal front motor housing  90  helps to dissipate the heat, and any exposed surface of the front motor housing  90  may be ribbed to increase surface area. Such a design further allows for the apparatus  1  to be sealed from contamination. A sealed housing  10  reduced hair entrapment. Such seals can be made by foam (where moving parts are to be sealed) and/or with elastomeric features. 
     Thus, as can be seen in  FIG. 6 , the clipping core (comprised of the motor  60 , front motor housing  90  and the pivot drive mechanism) is preferably a self-contained unit. By installing various damping and vibration isolation structures, the clipping core can be largely isolated and decoupled from the housing  10  with respect to heat and vibrations.  FIGS. 7A and 7B , which illustrate front and back portions  10 A,  10 B of housing  10 . As can be seen in  FIG. 7A , the front portion  10 A includes isolation mounts  100 A and  102 A. As can be seen in  FIG. 7B , the back portion  10 B includes isolation mounts  100 B,  102 B and  104 B. Preferably, each of the isolation mounts is made of a material which dampens vibrations and/or heat. As shown in  FIGS. 7A and 7B , the isolation mounts take the form of elastomeric ribs, though other structures are contemplated. In one embodiment, the isolation mounts may be formed in an overmolding process. However, in other embodiments, separate parts may be used to serve as the isolation mounts, which would allow for changing the properties of the mounts in terms of shape and durometer to optimize the system and minimize vibration. 
     Additionally, as shown in  FIG. 7A , additional dampers  106 A,  108 A and  110 A may also be used to isolate the hood  112  drive mechanism and blades  20 ,  25 . Such dampers  106 A,  108 A and  110 A are preferably elastomeric pads which are proud of the housing  10 . Additionally, a foam seal may preload the front portion  10 A of the housing  10 , thereby reducing the chances for vibration. 
     Referring to  FIGS. 8A and 8B , the hood  112  is affixed to the front portion  10 A of the housing  10 , covering at least the drive tip  30 , bearing  50  and eccentric  40 . The hood  112  can be connected to the housing with attachment members  113 , such as screws. The hood  112  can includes a foam seal  116  about its periphery, which can preload the hood  112  against the front portion  10 A of the housing  10  to prevent or reduce the vibration of the hood  112  against the front portion  10 A of the housing  10 . 
     Thus, there has been shown and described several embodiments of an electric hair cutting apparatus. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present invention will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.