Abstract:
A vibrator motor has a stationary piece and a moving piece hinged at one end. The moving piece does not generate substantial internal spring forces under the influence of an electromagnetic field, because it does not have a tail bracket. Other parts of conventional motors are also eliminated, so the motor is easier and less expensive to manufacture. In addition, the motor can be assembled and tuned before installation, which increases the ability to automate assembly.

Description:
[0001]    This invention relates to vibrator motors, and more particularly to vibrator motors for hair clippers and the like that have fewer parts than conventional vibrator motors, and can be installed in a case after the motor is assembled.  
         BACKGROUND OF THE INVENTION  
         [0002]    Vibrator motors are available in a variety of configurations. Typically, the motor includes a stack of stationary laminations secured inside a case for a hair clipper or other device. A coil wrapped around the stationary laminations produces varying electromagnetic fields that drive a complimentary set of moving laminations.  
           [0003]    The moving laminations are typically secured in an appropriate location with respect to the stationary laminations using a spring-like tail bracket. At least one, and usually two or three, pole faces are formed where the stationary and moving laminations are close to each other. One end of the tail bracket is secured to an end of the moving laminations, and the other end of the tail bracket is secured to the housing or the stationary laminations. The tail bracket/moving laminations assembly forms an arm of sorts that is attached at one end and open at the other. The open end of the moving laminations reciprocates to drive a clipper blade or some other device.  
           [0004]    In addition to the tail bracket, conventional vibrator motors also have a mechanical spring system that allows the motor to be tuned to a proper resonant frequency so that it operates properly. The spring system also determines the position of the moving laminations and clipper blades when the coil is not energized. A typical spring system has two coil springs. When the coil is energized by alternating current, the tail bracket, the spring system and the electromagnetic fields generated by the coil make the clipper blade or other device reciprocate. Motor tuning is accomplished by adjusting the stiffness of the springs in the spring system to obtain good performance, usually by turning an appropriate screw which adjusts the tension in the springs. If not properly tuned the motor will not have sufficient power, or it will flutter or clatter and essentially operate in an uncontrolled manner or not operate at all.  
           [0005]    Many things affect tuning, including the weight of the moving parts, the weight of the stationary parts, the length of the moving part of the arm, the energy release rate of the tuning springs, the alignment of the pole faces, the stiffness of the tail bracket, and other factors. Variations in any of these aspects of the device can cause problems in operation, and problems in manufacturing and assembly.  
           [0006]    Variations in the tail bracket present particularly difficult manufacturing challenges. If the tail bracket material thickness or hardness varies even slightly, the resonant frequency (the speed at which the arm vibrates naturally) is affected, since the force required to move the arm is related to the stiffness of the tail bracket. Even variations in bends in the tail bracket can cause assembly problems, because they can make the motor untunable.  
           [0007]    The tail bracket acts as a secondary tuning spring in addition to the two coil type tuning springs. If the neutral unsprung position of the tail bracket in the assembly is not the same as the neutral position of the arm when the clipper has been tuned, the tail bracket works against one of the tuning springs, applying a heavier load to one of the tuning springs than to the other. This causes the resonant frequency to change, since the spring load changes in order to compensate for the bias load applied by the tail bracket. Moreover, the force required to move the arm also varies under these conditions. Variations in tail bracket bends also affect the orientation of the blades, and in some cases make it difficult to properly align the blades of hair clippers.  
           [0008]    Another problem with known vibrator motors is that they require several pieces that must be assembled together in the case. The case is usually molded from plastic, which can have substantial dimensional variation due to warping and dimensional variation inherent in the molding process. These variations can create manufacturing and assembly problems.  
           [0009]    Dimensional variations of the pieces assembled in the case can create additional manufacturing and assembly problems. For example, if the drive finger is the wrong length, it can cause tuning problems due to the change in resonant frequency caused by a change in the length of the arm. In hair clippers, a drive finger that is too long can make it impossible to align the tips of the bottom blade teeth with the tips of the top blade teeth so that they have the correct overlap distance. If the drive finger is crooked, it can cause a crooked appearance of the top blade. If the drive finger is too far to the right or left, the teeth of the bottom blade might not be able to be adjusted to line up with the top blade teeth, causing a loss of cutting performance.  
           [0010]    Dimensional variations can also cause misalignment of the pole faces of the stationary and moving laminations. If there is excessive variation in the case, and/or in the arm assembly, the pole faces of the arm laminations will not be aligned with the pole faces of the coil laminations. There can be a vertical misalignment or the laminations can be twisted such that there may be a larger gap between poles near the top than at the bottom, or vice versa. Also, one of the poles may be closer together than the other poles. In any of these cases, the motor will not operate as efficiently as if the poles were well aligned, because the magnetic gap will be larger than it should be at some place, resulting in loss of power and/or efficiency or higher than normal power consumption.  
           [0011]    These problems can occur when one part, such as the case, is out of tolerance, or when the parts are individually within acceptable tolerances, but the cumulative variations from desired specifications is unacceptably high. Tolerance accumulation problems are often difficult to identify and resolve, particularly where the number of parts is high.  
           [0012]    In some conventional motors, the tuning springs are located at the rear or bottom of the motor, away from the drive end of the arm. This can also cause tuning problems, because the springs have poor leverage.  
           [0013]    In all, conventional motors have a relatively high number of parts which make them expensive and difficult to manufacture and assemble. Automation is also difficult because the designs are fairly complicated. Accordingly, there is a need for vibrator motors that are easier to manufacture and assemble, and are more adaptable to automated manufacture and assembly.  
           [0014]    Accordingly, one object of this invention is to provide new and improved vibrator motors.  
           [0015]    Another object is to provide new and improved vibrator motors for hair clippers and the like.  
           [0016]    Another object is to provide new and improved vibrator motors that are less expensive and easier to manufacture and assemble than conventional motors.  
           [0017]    Yet another object is to provide new and improved vibrator motors that do not have a tail bracket or the problems associated with tail brackets just discussed. A still further object is to provide new and improved vibrator motors that are less susceptible to parts tolerance build-up.  
           [0018]    Still another object is to provide new and improved vibrator motors having fewer parts than conventional motors.  
           [0019]    Still another object is to provide new and improved vibrator motors that can be pre-assembled and installed in a case after assembly.  
         SUMMARY OF THE INVENTION  
         [0020]    In keeping with one aspect of this invention, a vibrator motor has a stationary piece and a moving piece. One end of the moving piece is hinged to an end of the stationary piece. The pieces are open at the other end, where complementary pole faces on the stationary and moving pieces are separated from each other by at least one predetermined variable gap. Another gap is typically provided near the hinge, and other gaps may be provided, if desired.  
           [0021]    A coil is wound around a bobbin on the stationary piece. When the coil is energized with alternating current, it generates magnetic flux that flows through the stationary piece and the moving piece. The flux crosses the gap just above the hinge, as well as the gap at the other end of the motor pieces.  
           [0022]    A bias spring system plays the primary role in establishing the size of the gap between the stationary and moving pieces, and the resonant frequency of the motor during operation. The bias on the spring system can be adjusted to obtain an acceptable gap and resonant frequency. An extension on the bobbin and a drive member on the moving piece provide support for the spring system.  
           [0023]    The open vibrating end of the moving piece has sufficient power to drive a device such as the moving blade of a hair clipper or the like. The entire motor can be assembled and installed in a case as a single unit. In fact, the motor can even be tested and tuned outside of the case, before installation, if desired.  
           [0024]    The moving piece is hinged directly to the stationary piece without a tail bracket, and the moving piece does not generate substantial internal spring forces under the influence of the magnetic field. The tail bracket and other parts of conventional motors are eliminated entirely, and the motor is less expensive to manufacture. It is also easier to manufacture and assemble because it has fewer parts, less cumulative tolerance among parts, and a simpler system for establishing the resonant frequency. In addition, the motor can be assembled and tuned before installation, which increases the ability to automate assembly. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    The above mentioned and other features of this invention and the manner of obtaining them will become more apparent, and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, in which:  
         [0026]    [0026]FIG. 1 is a partially cutaway perspective view of a vibrator motor made in accordance with the principles of this invention;  
         [0027]    [0027]FIG. 2 is a plan view of the stationary and moving pieces used in the motor of FIG. 1;  
         [0028]    [0028]FIGS. 3, 4 and  5  are perspective views of a coil bobbin used in the motor of FIG. 1, with FIG. 5 showing the stationary piece installed in the bobbin;  
         [0029]    [0029]FIG. 6 is a perspective view of a drive member used in the motor of FIG. 1;  
         [0030]    [0030]FIG. 7 is a perspective view of a hinge holder for the motor of FIG. 1;  
         [0031]    [0031]FIG. 8 is a perspective view of the pieces of FIG. 2, showing the moving piece retained to the stationary piece by the holder of FIG. 7;  
         [0032]    [0032]FIG. 9 is a plan view of the motor of FIG. 1 installed in a hair clipper; and  
         [0033]    [0033]FIG. 10 is a perspective view of the case of the hair clipper of FIG. 9.  
     
    
     DETAILED DESCRIPTION  
       [0034]    As seen in FIGS. 1 and 2, a vibrator motor  10  includes a stationary piece  12  and a moving piece  14 . The pieces  12 ,  14  can be made of a plurality of stacked laminations, or solid material.  
         [0035]    The stationary piece  12  and the moving piece  14  form a hinge  16  at one end. Hinging can be accomplished in many ways. In FIGS. 1 and 2, the hinge end of the stationary piece  12  is circular on an outer surface, like a hinge pin, with an opening  18  for an installation screw, as will be seen. The hinge end of the moving piece  14  is curved on an inside surface to at least partially surround the curved portion of the stationary piece  12  and form a hinge barrel. Preferably, clearance between the pieces in the hinge is as minimal as possible, while still allowing the moving piece  14  to rotate in operation.  
         [0036]    The hinge  16  may be lined with plastic  19  (FIG. 2) or any other suitable low friction material, if desired, to reduce wear and dissipate heat, if desired. Grease slots  20  may be provided in the moving piece  14 , as in FIG. 1, or in the stationary piece  12 . Though not shown, it is contemplated that the hinge  16  could also be made by providing the moving piece  14  with a hinge pin and the stationary piece  12  with a hinge barrel.  
         [0037]    When assembled, the motor  10  has two gaps  21 ,  22  (FIG. 2) between the stationary piece  12  and the moving piece  14 . While the embodiment shown in FIGS. 1 and 2 has a generally L shaped stationary piece and two gaps, other configurations are possible, such as a C shape with two gaps, an E shape with three gaps, etc. The surfaces that form the gaps  21 ,  22  are pole faces. Preferably, the pole faces of the gap  21  form a plane that generally intersects the axis of the opening  18 .  
         [0038]    The motor  10  also includes a coil bobbin  23  (FIG. 3) having an opening  24  (FIG. 4) that allows the bobbin  23  to be placed around the stationary piece  12  by slipping the bobbin over the hinge end  16  of the stationary piece  12 , as seen in FIG. 5. A coil  25  (FIG. 1) is wound around a winding portion  26  of the bobbin  23 , preferably before installation. In some products, such as massagers, the coil can be wound around the moving piece instead of the stationary piece.  
         [0039]    The bobbin  23  also has an arm  27  used to support a movement control device such as a spring system  28  (FIG. 1). A screw hole  29  is also provided for motor installation purposes. The screw hole  29  preferably goes through a bobbin gusset  30 , adding rigidity to the arm when assembled in the case. The bobbin  23  can be made in many ways, but is preferably molded in the one piece configuration shown in FIG. 1.  
         [0040]    The spring system  28  (FIG. 1) is located toward an open end  31  of the stationary piece  12  and the moving piece  14 . The spring system  28  determines the position of the moving piece  14 , and plays a part in determining the resonant frequency of the moving piece  14  and the amplitude of its vibrations during operations. The spring system  28  includes a first spring  32 , a second spring  33 , and an adjusting screw  34  that threadedly engages an opening  35  in the bobbin  23 . The screw  34  preferably has a chamfer  36  (FIG. 9) that limits lateral movement of the spring  32 , and a groove  37  in a wall  38  also limits lateral movement of the spring  32 . Lateral movement of the spring  33  is limited by a groove  39  in a wall  40  and a groove or indentation  41  in a wall  42 .  
         [0041]    The end of the stationary piece  12  at the open end  31  has an opening  43  that aligns with the opening  29  in the bobbin  23  for installation purposes. The end of the moving piece  14  at the open end  31  is configured to accept and secure a drive member  44  (FIG. 6). Using a C shaped end configuration  45  shown in FIG. 2, and a T shaped end configuration  46  for the drive member  44 , as shown in FIG. 6, the drive member can be easily secured to the open or moving end of the piece  14  by slipping the end  46  into end  45  up to a side wall  47 . A notch  48  (FIG. 2) facilitates bending or crimping of an end  49  of the moving piece  14 , to more tightly secure the drive member  44  to the moving piece  14  after installation. It is also contemplated that the drive member  44  and the moving piece  14  could be fabricated as one piece. In any event, the drive member is on the moving piece.  
         [0042]    The screw  34  (FIG. 1) passes through an opening  50  (FIG. 6) in the drive member  44 . The spring  32  (FIG. 1) is held under tension between the head of the screw  34  and the wall  38  of the drive member  44 . Tension is maintained in the spring  33  by the wall  40  in the drive member  44  and the wall  42  in the arm  27  of the bobbin  23 . The arm  27  is threaded to secure the screw  34  in place, while allowing easy adjustment of the screw  34  for tuning purposes.  
         [0043]    The moving piece  14  can be secured with respect to the stationary piece  12  at the hinge  16  in any suitable way, such as a screw and a washer, or a screw and a holder  60 , shown in FIGS. 7 and 8. The holder  60  has a bottom surface  62  that rests on the stationary piece  12  surrounding the opening  18  to secure the stationary piece  12  axially with respect to an axis  63 , a second surface  64  having a surface  66  on a flexible, resilient finger that holds the moving piece  14  down and in proper alignment with the stationary piece  12 , and a top surface  68  by which the holder  60  can be held in place. By allowing the surface  66  to function independently of the surface  62 , the hinge holder  60  can be tightened axially as much as desired, without inhibiting rotation of the moving piece  14 .  
         [0044]    The device  60  also includes a second surface  72  on another spring finger  73  that places lateral or radial pressure on the moving piece  14 , to stabilize the moving piece  14  during operation by eliminating excessive chatter in the hinge. The surface  72  preferably presses against the moving piece  14 , as shown.  
         [0045]    The motor  10  is shown installed in a hair clipper  80  in FIG. 9. In addition to the motor  10 , the hair clipper  80  includes a case  82 , a fixed, detachable or adjustable stationary blade  84 , and a moving blade  86  positioned opposite the blade  84  and appropriately secured, as in U.S. Pat. No. 5,068,966, entitled “Blade Assembly For Electric Hair Clippers”, incorporated by reference in its entirety. The moving blade  86  is operatively connected to the drive member  44 . A power switch and power source are typically connected to wires  87  of the motor  10 , as well, and a cover (not shown) encloses the case  82 .  
         [0046]    The case  82  (FIG. 10) is typically molded plastic, and includes a first threaded boss  88  for an installation screw  89 , and a second threaded boss  90  for an installation screw  91 . The boss  90  has an inner rim  92  and an outer rim  93 , the rims  92 ,  93  being separated by a space  94 . The outer rim  93  is a bearing surface for the moving piece  14 . The outer rim  93  can be lowered to accept a washer, ball bearing, etc., if desired. The screw  91  presses the stationary piece against the rim  92 , without placing pressure on the moving piece. In this manner, motor operation is not affected by the torque placed on the screw  91 .  
         [0047]    The motor  10  can be easily pre-assembled and installed in the case  82  as a single unit by placing the assembled motor in the case such that the drive member  44  is operatively connected to the moving blade  86 , and securing the motor with screws  89 ,  91 . The screws  89 ,  91  are secured in threaded openings in the case  82 . While the motor  10  may be tuned before installation in the case  82 , if desired, it can also be tuned after installation.  
         [0048]    The hair clipper  80  can be easily manufactured by securing the stationery blade  84  to the case, usually by screws, and placing the moving blade  86  adjacent the blade  84 , usually using a spring that allows the blade  86  to reciprocate to cut hair. The motor  10  is then installed in the case  80  using screws  89 ,  91 , with the drive member  44  engaging the moving blade  86 . A cover is then placed over the case  80  and secured.  
         [0049]    While the motor of this invention has been described with respect to a hair clipper, many other applications are contemplated, such as shavers, engravers, electric scissors, air pumps, sprayers, massagers and any other device that can operate with a vibrator motor. In products such as massagers, the moving piece can vibrate openly, without a driver.  
         [0050]    While the principles of the invention have been described above in connection with specific apparatus and applications, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention.