Abstract:
A motorized hand tool such as a cordless ratchet wrench is configured for reducing assembly and disassembly processes. The motorized hand tool includes a motor end plate that may be fastened to a drive member such as a ratchet head assembly without the use of fasteners or assembly tooling such as presses, fixtures or hammers. A flange on the motor end plate can pass through a keyway in a periphery of the ratchet head assembly and may be then be rotated out of the keyway and into a peripheral slot of the ratchet head assembly. A rib protruding inwardly from a clamshell housing portion of the tool closes the keyway to prevent the flange on the motor end plate from rotating back into the keyway.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present application relates to a motorized hand tool for applying torque to a work piece. More particularly, the present application relates to a motor coupling to a head assembly of a motorized hand tool. 
       BACKGROUND OF THE INVENTION 
       [0002]    Power hand tools such as motorized ratchet wrenches and drivers are commonly used in automotive, industrial and household applications to install and remove threaded fasteners and to apply a torque and/or angular displacement to a work piece such as a threaded fastener, for example. Motorized hand tools such as cordless power ratchets and drivers generally include an electric motor contained in a clamshell housing along with other components such as switches, light emitting diodes (LEDs), and batteries, for example. The clamshell housing generally includes two or more housing portions fastened together by fasteners such as screws or rivets. 
         [0003]    The process of assembling a motor subassembly to a drive member such as a ratchet head housing in a motorized hand tool generally involves the use elaborate fixtures, presses and/or hammers, for example. Current process for assembling a motor subassembly to a ratchet housing involve fastening a motor end plate to a ratchet head housing with fasteners such as pins or screws. Manufacturing tooling including presses, fixtures and hammers are used to install the fasteners. Disassembly of the ratchet heads housing from the motor end plate involves the use of a hammer and punch to remove the fasteners. The resulting subassemblies have been difficult to disassemble without causing damage to its constituent components. 
       SUMMARY OF THE INVENTION 
       [0004]    According to embodiments of the present application, a motorized hand tool such as a cordless ratchet wrench includes a motor end plate that may be fastened to a drive member such as a ratchet head assembly without the use of fasteners or assembly tooling such as presses, fixtures or hammers. A flange on the motor end plate can pass through a keyway in a periphery of the ratchet head assembly and may then be rotated out of the keyway and into a peripheral slot of the ratchet head assembly. In one example, the motor end plate compresses a compressible member such as a rubber O-ring or steel wave washer to absorb clearance tolerances and provide a tight fit. 
         [0005]    The motor end plate may be assembled from the keyway into the slot by applying a 90 degree rotation of the motor end plate relative to the ratchet head assembly around a main axis of the motorized hand tool to secure a motor assembly to the ratchet head assembly. A clamshell housing assembled around the motor assembly includes an inwardly protruding rib portion that substantially fills the keyway and prevents the motor end plate from rotating back out of the slot. 
         [0006]    The motor assembly may be disassembled from the ratchet head assembly by removing the clamshell housing and by applying a 90 degree rotation of the motor end plate relative to the ratchet head assembly around the main axis of the motorized hand tool so that the flange of the motor end plate is aligned to clear the keyway. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    For the purpose of facilitating an understanding of the subject matter sought to be protected, there are illustrated in the accompanying drawings embodiments thereof, from an inspection of which, when considered in connection with the following description, the subject matter sought to be protected, its construction and operation, and many of its advantages should be readily understood and appreciated. 
           [0008]      FIG. 1A  is a side view drawing illustrating a cordless ratchet tool including a ratchet head assembly coupled to a motor assembly in accordance with an embodiment of the present application. 
           [0009]      FIG. 1B  is a top view drawing illustrating a cordless ratchet tool including a ratchet head assembly coupled to a motor assembly in accordance with an embodiment of the present application. 
           [0010]      FIG. 2  is an exploded view drawing of a ratchet head, motor and clamshell housing assembly of a cordless ratchet tool in accordance with an embodiment of the present application. 
           [0011]      FIG. 3  is an exploded view drawing of a ratchet head, motor, switch and clamshell housing assembly of a cordless ratchet tool in accordance with an embodiment of the present application. 
           [0012]      FIG. 4A  is an illustration of a ratchet head and motor subassembly of a cordless ratchet tool in accordance with an embodiment of the present application. 
           [0013]      FIG. 4B  is an illustration of a ratchet head housing of a cordless ratchet tool in accordance with an embodiment of the present application. 
           [0014]      FIG. 4C  is a cross sectional view of a ratchet head housing of a cordless ratchet tool in accordance with an embodiment of the present application. 
           [0015]      FIG. 4D  is an illustration of a motor end plate of a cordless ratchet tool in accordance with an embodiment of the present application. 
           [0016]      FIG. 5  is an illustration of a clamshell housing portion in accordance with an embodiment of the present application. 
           [0017]      FIG. 6  is a process flow diagram illustrating a method of assembling a cordless ratchet tool in accordance with an embodiment of the present application. 
           [0018]      FIG. 7  is a process flow diagram illustrating a method of disassembling a cordless ratchet tool in accordance with an embodiment of the present application. 
       
    
    
       [0019]    It should be understood that the comments included in the notes as well as the materials, dimensions and tolerances discussed therein are simply proposals such that one skilled in the art would be able to modify the proposals within the scope of the present application. 
       DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0020]    While this invention is susceptible of embodiments in many different forms, there is shown in the drawings, and will herein be described in detail, a preferred embodiment of the invention with the understanding that the present application is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to embodiments illustrated. 
         [0021]    Embodiments of the present application may be implemented in a motorized hand tool such as the cordless ratchet tool shown in  FIG. 1A  The cordless ratchet tool  100  includes a handle portion  102  coupled to a driver portion  104  The driver portion  104  may include a ratchet head assembly  106  including a ratchet housing  112 , ratchet head  110 , and selector knob  108 , for example. The handle portion  102  may include a main housing  114  enclosing an electric motor, a switch assembly and one or more status indicators such as light emitting diodes, for example.  FIG. 1B  shows a top view of the cordless ratchet tool  100 . Referring to  FIG. 1B , the main housing  114  may be assembled from two or more clamshell housing portions  116 ,  118  fastened together and securely attached to the ratchet head assembly  104 . 
         [0022]      FIG. 2  shows a ratchet head assembly  206  of a cordless ratchet tool assembly  200  coupled to a motor assembly  220  according to an aspect of the present application. A first clamshell housing portion  216  and second clamshell housing portion  218  of the cordless ratchet tool assembly  200  are configured for assembly around the motor assembly  220  and the ratchet head assembly  206 . 
         [0023]      FIG. 3  shows a ratchet head assembly  306  of a cordless ratchet tool assembly  300  coupled to a motor assembly  320  and a switch assembly  322  according to another aspect of the present application. A first clamshell housing portion  316  and second clamshell housing portion  318  of the cordless ratchet tool assembly  300  are configured for assembly around the motor assembly  320 . 
         [0024]    A ratchet head and motor subassembly  400  according to an aspect of the present application is described with reference to  FIGS. 4A-4D . The ratchet head and motor subassembly  400  shown in  FIG. 4A  includes a motor assembly  420  coupled to a ratchet head assembly  406 . The motor assembly  420  includes an electric motor  420  coupled to a motor end plate such as the motor end plate  424  shown in  FIG. 4D . 
         [0025]    The motor end plate  426  may be fastened to the electric motor  424  by fasteners such as rivets or screws through fastener holes  430 , for example. According to an aspect of the present application, the motor end plate  426  includes one or more outwardly protruding semi-annular flanges  428 . The flanges  428  are configured to fit in a semi-annular slot  432  formed by an undercut behind a lip  434  around a periphery in the ratchet head housing  412 . One or more discontinuities in the lip  434  create one or more apertures  436  that are sized to receive each of the one or more flanges  428  of the motor end plate  426  during assembly of the motor end plate  426  to the ratchet head housing  412  and during disassembly of the motor end plate  426  from the ratchet head housing  412 . The motor end plate  426 , may also include one or more detent structures (not shown) configured to provide tactile indications of proper rotation displacement during assembly. 
         [0026]    According to aspects of the present application, the motor assembly  420  is coupled to the ratchet head housing  412  by pushing the flanges  428  of the motor end plate  426  through the apertures  436  in the lip  434  of the ratchet head housing  412  then rotating the motor assembly  420  relative to the ratchet head housing  412  until the flanges  428  of the motor end plate  426  are secured in the semi-annular slot  432  of the ratchet head housing  412 . In one example, the flanges  428  and apertures  436  are sized so that the motor assembly  420  may be rotated in  90  degrees in either direction to engage the semi-annular slots  432  of the ratchet head housing  412  during an assembly process or to disengage the semi-annular slots  432  of the ratchet head housing during a disassembly process. A compressible member (not shown) such as a steel wave washer or an O-ring made from a compressible material such as rubber, or other elastomer, for example, may be installed between the motor assembly  420  and the ratchet head housing  412  to absorb dimensional tolerances. The compressible member is compressed during assembly of the motor assembly  420  to the ratchet head housing  412  and provides pressure between the flange  428  and lip  434  that facilitates a tight fit and alignment of drive gears, for example. 
         [0027]    According to another aspect of the present application, a rib protruding inwardly from one or more clamshell housing portions is shaped to substantially fill the one or more apertures  436  when the clam shell housing is assembled to the ratchet head and motor subassembly  400 . Referring to  FIG. 5 , one or more semi-annular ribs  536  in a first clamshell housing portion  516  are shaped to fit into and substantially fill the one or more apertures  436 , for example. The semi-annular ribs  536  prevent the motor end plate  426  from rotating out of the slot  432  in the ratchet head housing  412 . 
         [0028]      FIG. 6  is a process flow diagram illustrating a process  600  for assembling a motorized hand tool according to an aspect of the present application. As shown, the process  600  begins and proceeds to step  602 , which includes aligning a semi-annular flange portion of a motor end plate with an aperture in a ratchet head assembly. In step  604 , the process includes passing a motor end plate into the ratchet head assembly after aligning the semi-annular flange portion. In step  606 , the process includes moving the semi-annular flange portion out of the aperture and into a peripheral slot of the ratchet head assembly by rotating the motor end plate. In step  608 , the process includes obstructing rotation of the motor end plate from the peripheral slot. 
         [0029]    According to an aspect of the present application, an inwardly protruding rib portion of a clamshell housing may be aligned with the aperture. The rib portion may be placed in the aperture to assemble the clamshell housing around the ratchet head assembly so that the rib portion obstructs rotation of the motor end plate from the peripheral slot. 
         [0030]      FIG. 7  is a process flow diagram illustrating a process  700  for assembling a motorized hand tool according to an aspect of the present application. As shown, the disassembly process  700  begins and proceeds to step  701 , which includes removing a member obstructing rotation of a motor end plate. In step  702 , the process includes moving a semi-annular flange portion of a motor end plate out of a peripheral slot of a ratchet head assembly and into an aperture in the ratchet head assembly by rotating the motor end plate. In block  704 , the disassembly process includes aligning the semi-annular flange portion of a motor end plate with the aperture. In block  706 , the disassembly process includes passing a motor end plate out of the ratchet head assembly after aligning the semi-annular flange portion. According to an aspect of the present application, the disassembly process may also include opening the aperture by removing a clamshell housing portion from around the ratchet head housing before rotating the motor end plate housing. 
         [0031]    As discussed above, the aspects of the present application are described in terms of a cordless ratchet tool  100  as shown in  FIG. 1 . However, it should be understood that aspects of the present application could be implanted in other motorized hand tools. For example, and without limitation, the motorized hand tool can be ratchet wrench, open wrench, screw driver, nut driver, or any other tool capable of applying torque to a work piece. 
         [0032]    As used herein, the term “coupled” or “communicably coupled” can mean any physical, electrical, magnetic, or other connection, either direct or indirect, between two parties. The term “coupled” is not limited to a fixed direct coupling between two entities. 
         [0033]    The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. While particular embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the broader aspects of applicants&#39; contribution. The actual scope of the protection sought is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.