Abstract:
A linear actuator is configured to provide the moving force for adjustable furniture, such as beds, chairs, or tables. The linear actuator includes a drive assembly, rigid arm, and linkage assembly. The rigid arm includes a pusher block with one or more attachment projections where the linkage assembly is attached.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/445,432, filed on Jul. 29, 2014 and entitled LINEAR ACTUATOR, which claims the benefit of U.S. Provisional Application No. 61/862,409, filed Aug. 5, 2013 and entitled IMPROVED LINEAR ACTUATOR, both of which are hereby incorporated by this reference in their entireties. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present disclosure reveals a new design for a linear actuator that modifies the positioning in adjustable furniture 
       BACKGROUND 
       [0003]    A linear actuator is an actuator that creates motion in a straight line, in contrast to the circular motion of a conventional electric motor. Linear actuators are widely used within the area of adjustable furniture, such as beds, chairs, or tables, where they may be used for adjusting the position of adjustable furniture, such as the lifting and reclining of motion chairs, the height of a table, or the position of the mattress surface of a bed. The actuator is typically comprised of an electric motor drive assembly that drives a threaded spindle. The spindle is retained within a rigid arm, and the electric motor drive assembly is attached to the rigid arm with a plurality of threaded fasteners. A pusher block is threaded onto the spindle and is secured in linear recesses within the arm. As the electric motor drive assembly turns the spindle, the pusher block moves from one end of the arm to the other end. The direction of movement is determined by the direction of the spindle&#39;s rotation. 
         [0004]    One end of the prior art actuators may be secured to the adjustable furniture by a rear mounting bracket. The actuators are also attached to the furniture by a pair of levers or linkages. One end of the respective linkages is secured to the pusher block with a plurality of threaded fasteners. The other end of the respective linkages communicates with the furniture. Movement of the pusher block moves the linkages and adjusts the position of the furniture. 
         [0005]    The prior art linear actuators are costly to manufacture. Connection of the electric motor drive assembly to the rigid arm using threaded fasteners is disadvantageous because it is a time-consuming and complicated method of assembling the actuators. The prior art actuators are also difficult to mount on adjustable furniture. Use of threaded fasteners on the pusher block makes it difficult for assembly line workers to align the furniture so that the levers line up with threaded apertures in the pusher block. 
         [0006]    Accordingly, there is a need for a linear actuator that can be quickly assembled and mounted onto adjustable furniture. 
       SUMMARY 
       [0007]    The terms “invention,” “the invention,” “this invention” and “the present invention” used in this patent are intended to refer broadly to all of the subject matter of this patent and the patent claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the patent claims below. Embodiments of the invention covered by this patent are defined by the claims below, not this summary. This summary is a high-level overview of various embodiments of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification of this patent, any or all drawings, and each claim. 
         [0008]    The present invention relates to an improved linear actuator. The improved linear actuator is designed to provide the moving force for adjustable furniture, such as beds, chairs, or tables. The improved linear actuator overcomes problems with the prior art by reducing the number of necessary parts and simplifying assembly to save production costs. 
         [0009]    While the improved linear actuator is directed at use of the actuator in adjustable furniture, the improved linear actuator may be adapted for use in machine tools and industrial machinery, in computer peripherals such as disk drives and printers, in valves and dampers, and in many other places where linear motion is required. 
         [0010]    Various implementations described in the present disclosure can include additional systems, methods, features, and advantages, which cannot necessarily be expressly disclosed herein but will be apparent to one of ordinary skill in the art upon examination of the following detailed description and accompanying drawings. It is intended that all such systems, methods, features, and advantages be included within the present disclosure and protected by the accompanying claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The features and components of the following figures are illustrated to emphasize the general principles of the present disclosure. Corresponding features and components throughout the figures can be designated by matching reference characters for the sake of consistency and clarity. 
           [0012]      FIG. 1  is a front perspective view of one embodiment of a linear actuator. 
           [0013]      FIG. 2  is a perspective view of an alternative embodiment of a linear actuator. 
           [0014]      FIG. 3  is a sectional view of the linear actuator of  FIG. 2 . 
           [0015]      FIG. 4  is a side view of the linear actuator of  FIG. 1 . 
           [0016]      FIG. 5  is a perspective view of an alternative embodiment of a linear actuator. 
           [0017]      FIG. 6  is a sectional view of the linear actuator of  FIG. 5 . 
           [0018]      FIG. 7  is a rear perspective view of the linear actuator of  FIG. 1 . 
           [0019]      FIG. 8  is an enlarged view of the dis-assembled rigid arm and drive motor of the linear actuator of  FIG. 1 . 
           [0020]      FIG. 9  is an enlarged view of the dis-assembled rigid arm and holder of the linear actuator of  FIG. 1 . 
           [0021]      FIG. 10  is an exploded assembly view of the linear actuator of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    The subject matter of embodiments of the present invention is described here with specificity to meet statutory requirements, but this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explicitly described. Directional references such as “up,” “down,” “top,” “left,” “right,” “front,” “back,” and “corners,” among others are intended to refer to the orientation as illustrated and described in the figure (or figures) to which the components and directions are referencing. 
         [0023]      FIGS. 1, 4, and 7  illustrate an embodiment of a linear actuator  16  according to the present disclosure. An electric drive motor assembly  2  is connected to a rigid arm  3 . The rigid arm  3  is formed of stainless steel or other suitable material, and also includes a plastic cover  17 . A threaded spindle  5  is retained inside the arm. A spindle nut  6  is threaded onto the spindle  5 , and a pusher block  7  is attached to the spindle nut  6 . The pusher block  7  straddles the rigid arm  3  and slides up and down the arm  3  as the electric drive motor assembly  2  turns the spindle  5 . A holder  4  is attached to the other end of the rigid arm  3  to retain one end of the spindle  5  and to provide mounting points for the actuator. 
         [0024]    The pusher block  7  provides a connection point for communicating force generated by the improved linear actuator  16  to the adjustable furniture. To simplify assembly of the actuator  16  with adjustable furniture, the top of the pusher block  7  incorporates a clevis  18 . Apertures in the clevis  18  are adapted to receive a clevis pin  19  or other suitable fastener. A single linkage  8  connects the pusher block  7  to a torque tube assembly  14 . An aperture at the lower end of the single linkage  8  is adapted to receive the clevis pin  19 . A cotter pin  20  may be used to secure the clevis pin  19 . Use of a clevis pin  19  to attach the linkage  8  and pusher block  7  eliminates the need for additional brackets and threaded fasteners to facilitate the attachment. The pin  19  also eliminates the need to mold threaded screw-receiving apertures into the pusher block  7 . 
         [0025]    The clevis  18  may also be incorporated onto one or more sides of the pusher block  7  (see  FIGS. 2, 3, 5, and 6 ).  FIG. 2  depicts an embodiment of the improved actuator  16  with the clevis  18  incorporated into the side of the pusher block  7 . In this embodiment, a clevis pin  19  is used to secure the linkage  8 .  FIG. 3  is a cross sectional view of this embodiment.  FIG. 5  depicts an embodiment of the improved actuator  16  with the clevis  18  incorporated into the side of the pusher block  7 , with a threaded bolt  11  securing the linkage  8 .  FIG. 6  is a cross sectional view of this embodiment. 
         [0026]      FIG. 4  is a side view of the improved actuator  16 . The single linkage  8  has a unique lever shape that may be adapted to fit specific requirements for different embodiments of adjustable furniture. A single dual angle bracket  13  is moveably attached to the upper end of the linkage  8  and may be attached to a torque tube assembly  14  that transmits the force of the actuator  16  to the adjustable furniture.  FIG. 7  is a rear view of the improved linear actuator  16 . A bolt  12  (see  FIG. 7 ) or similar fastener moveably secures the upper end of the single linkage  8  to the dual angle bracket  13 . Threaded fasteners  15  secure the dual angle bracket to the torque tube assembly  14 . The torque tube assembly  14  communicates with the adjustable furniture (not shown). A clevis pin  19  secures the lower end of the linkage  8  to the clevis  18  at the top of the pusher block  7 . A cotter pin  20  secures the clevis pin  19 . The improved linear actuator  16  simplifies the process of attaching the actuator  16  to the furniture because the clevis  18  makes it easier for assembly workers to align the furniture, torque tube assembly  14 , linkage  8 , and pusher block  7 . Additionally, assembly can be simplified through use of a single linkage  8 . 
         [0027]    The improved linear actuator  16  contains other improvements that reduce time to assemble the actuator  16 .  FIG. 8  is a close up view of a disassembled electric drive motor assembly  2  and rigid arm  3 . The end of the rigid arm  3  contains one or more slots  21 . The slots  21  are adapted to receive one or more prongs  22  molded into the base of the drive motor assembly  2 . The slots  21  and prongs  22  allow the drive motor assembly  2  to be pressed onto the rigid arm  3  when the improved linear actuator  16  is assembled. The prongs  22  apply pressure to the arm  3  to securely hold the drive assembly  2  and rigid arm  3  together. Use of the slots  21  and prongs  22  eliminates the use of threaded fasteners to secure the drive assembly  2  and arm  3  together, decreasing manufacturing time. 
         [0028]      FIG. 9  is a close up view of a disassembled rigid arm  3  and holder  4 . The rigid arm  3  incorporates one or more fastener receiving channels  23 . One or more fasteners  24  pass through one or more apertures  25  in the holder  4 . In this embodiment threaded screws are used as fasteners  24 , but other appropriate fasteners may be used. During assembly, the holder  4  is positioned next to the rigid arm  3  so the apertures  25  in the holder  4  align with the fastener receiving channels  23  in the arm  3 . The fasteners  24  are then installed, securing the holder  4  to the rigid arm  3 . The use of one or more threaded screws to secure the holder  4  to the arm  3  simplifies assembly of the improved linear actuator  16  and leads to faster production. 
         [0029]      FIG. 10  is a perspective view of the disassembled improved linear actuator  16  with the pusher block  7  already positioned on the spindle  5 . The electric drive motor assembly  2  is comprised of an electric motor  26 , lower assembly cover  27 , and upper assembly cover  28 . One or more threaded screws  29  secure the electric motor  26  to the lower assembly cover  27  and a series of threaded screws  30  secures the upper assembly cover  28  to the lower assembly cover  27 . A worm gear (not shown) is attached to the output shaft  31  of the electric motor  26 . The worm gear turns a worm wheel  32  attached to the end of the threaded spindle  5 . One end of the worm wheel  32  rests in a worm wheel bearing  33  to facilitate rotation of the spindle  5 . 
         [0030]    The spindle  5  rests within the rigid arm  3 . A plastic cover  17  shields the spindle  5 . The spindle nut  6  is threaded onto the spindle  5  and is attached to the pusher block  7 . Switches  34  are mounted within the rigid arm  3  using threaded screws  35 . The switches  34  sense the position of the pusher block  7  and are connected to the controls (not shown) and power source (not shown) for the improved linear actuator  16 . When the pusher block  7  contacts a switch  34 , power to the electric motor  26  is cut and travel of the pusher block  7  is stopped. 
         [0031]    The holder  4  is attached to the end of the rigid arm  3  using threaded fasteners  24  that are screwed into fastener receiving channels  23  in the rigid arm  3 . The holder  4  may incorporate apertures  36  for receiving fasteners  37  that can be used to attach the actuator  16  to mounting points on the frame of a piece of adjustable furniture. 
         [0032]    The foregoing description of preferred embodiments for the improved linear actuator is presented for the purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments are chosen and described in an effort to provide the best illustration of the principles of the invention and its practical applications, and to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. 
         [0033]    It should be emphasized that the above-described aspects are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present disclosure. Many variations and modifications can be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the present disclosure. All such modifications and variations are intended to be included herein within the scope of the present disclosure, and all possible claims to individual aspects or combinations of elements or steps are intended to be supported by the present disclosure. Moreover, although specific terms are employed herein, as well as in the claims that follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the described invention, nor the claims that follow.