Patent Publication Number: US-2009235785-A1

Title: Gear system for a wrench

Description:
BACKGROUND 
     1. Field of Invention 
     This invention relates generally to a gear system useful for a wrench for grabbing and turning an object. 
     2. Related Art 
     Substantially all modern vehicles that incorporate internal combustion engines use lubricating oil that circulates through the engine during operation. These engines use oil filter cartridges for removing dirt and other particles from the lubricating oil, so that the particles do not circulate through the engine undesirably. Draining out the dirty oil and replacing it with new oil, as well as the replacement of the oil filter, is a routine engine maintenance procedure that are performed for these types of vehicles that rely on internal combustion engines. The size of the oil filters vary among the different engines. 
     Changing the oil filter requires a tool not only because the oil filter can sometimes be hot enough to cause a burn but also because sufficient torque needs to be applied to tighten or loosen the oil filter. One of the tools commonly used to take out and replace the oil filter is a band type oil filter wrench made of a single, thin, circular metal band with a long handle on the side for lateral wrenching drive. However, this oil filter wrench is awkward and inconvenient to use because the oil filter is usually located in a tight, crowded spot of an engine block underneath a vehicle. The limited space around the oil filter makes it challenging to use the long handle band wrench, which has its wrenching axis around the periphery of the oil filter. Due to the space limitation around the oil filter and the slippery surface of the metal band, it is difficult to get a solid grip around the oil filter with the circular metal band wrench. An adjustable, compact, and easy-to-use wrench that can grip/grab an object (e.g., a cylindrical object) securely is desired. 
     SUMMARY 
     In one aspect, the invention is a novel gear mechanism. The gear mechanism includes a structure having a spiral-pattern groove with an axis extending through a center of the spiral-pattern groove. An arm with teeth extends across the spiral-pattern groove. The teeth on the arm are shaped and arranged to fit into the spiral-pattern groove such that when the structure is rotated about the axis, the arm moves toward or away from the center of the spiral-pattern groove depending on the direction of rotation. 
     In another aspect, the invention is a wrench for grabbing an object. The wrench includes a gear structure having a spiral-pattern groove with an axis extending through a center of the spiral-pattern groove. A plurality of arms are coupled to the structure, wherein each of the arms extends across a part of the spiral-pattern groove and has teeth that fit into the spiral-pattern groove such that when the structure is rotated about the axis, the teeth slide in the spiral-pattern groove to move the arms toward or away from the center of the spiral-pattern groove depending on the direction of rotation. 
     Other features and aspects of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the features in accordance with embodiments of the invention. The summary is not intended to limit the scope of the invention, which is defined solely by the claims attached hereto. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a wrench that incorporates the gear system of the invention. 
         FIG. 2A  is a perspective view of a gear structure having a spiral-pattern groove. 
         FIG. 2B  is a perspective view of a gripping structure that is designed to fit with the gear structure of  FIG. 2A . 
         FIG. 2C  is a housing that is designed to couple with the gear structure of  FIG. 2A . 
         FIG. 3A  and  FIG. 3B  are cross-sectional views of the wrench of  FIG. 1  with the gripping structure in different positions. 
         FIG. 4A  and  FIG. 4B  are plan views of the teeth on the gripping structure of  FIG. 2B . 
         FIG. 5A  and  FIG. 5B  are cross-sectional views of the gripping structure engaged with the spiral-pattern groove in different embodiments of the invention. 
         FIG. 6  is a perspective view of an alternative embodiment of a wrench that incorporates the gear system of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, reference is made to the accompanying drawings which illustrate several embodiments of the present invention. It is understood that other embodiments may be utilized and mechanical, compositional, structural, and operational changes may be made without departing from the spirit and scope of the present disclosure. The following detailed description is not to be taken in a limiting sense, and the scope of the embodiments of the present invention is defined only by the claims of the issued patent. 
     It will be understood that when an element or layer is referred to as being “on”, “connected to” or “coupled to” another element or layer, it can be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled to” another element or layer, there are no intervening elements or layers present. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
       FIG. 1  is a perspective view of a wrench  10  that incorporates the gear system of the invention. The wrench  10  may be used for clamping and opening a cylindrical object, including but not limited to an automotive oil filter. The wrench  10  has a housing  20  that holds the gear mechanism, a gripping structure  30 , and a shaft  40  that extends from the housing  20 . The shaft  40  is hollow and may extend substantially orthogonally to a surface of the housing  20 . Each of the gripping structure  30  has a paddle  32  that contacts and grips the cylindrical object and an arm  34  that connects the paddle  32  to the gear system in the housing  20 . The arm  34  moves in and out of the housing  20  as shown by an arrow  36 . The positions of the arms  34  depend on the size of the object being gripped—the bigger the object, the farther out the arms  34  will extend from the housing  20 . 
     A bolt  58  sits at the top of the shaft  40  and is used to adjust the size of the “grip.” As will be explained below, the bolt  58  can be turned in the directions shown by an arrow  44 , for example by using a ratchet (see  FIG. 3A  below). Turning the bolt  58  turns the gear mechanism that sits in the housing  20 , adjusting the positions of the gripping structures  30 . By turning the bolt  58 , a user widens or tightens the “grip” of the wrench  10  to fit the size of the object that is being gripped. If rotated in one direction of the arrow  44 , the gripping structures  30  extend farther out of the housing  20  to grip a wide object. If rotated in the opposite direction of the arrow  44 , the gripping structures  30  retract into the housing  20  to tightly grip a smaller object. All (four, in the embodiment shown) the gripping structures  30  move at the same time. 
     A handle  42  is coupled to the shaft  40  and is useful for turning the wrench  10  to loosen or tighten the gripped object. The handle  42  facilitates a user to turn the entire wrench  10  and apply the necessary torque. Typically, a user would first turn the bolt  58  to tighten the wrench&#39;s grip around an object, and then turn the wrench  10  using the handle  42  to turn the gripped object. 
       FIGS. 2A ,  2 B, and  2 C show various parts that make up the wrench  10 .  FIG. 2A  shows a gear structure  50  having a spiral-pattern groove  54 . The spiral-pattern may be right-hand threaded or left-hand threaded. As shown, a rod  56  extends from the center of the spiral pattern groove  54  orthogonally to the substantially circular plane of the spiral-pattern groove. The rod  56  is designed to fit with a bolt  58  so that turning the bolt  58  would turn the rod  56 . When the rod  56  is turned, the spiral-pattern groove  54  turns too. One end of the rod  56  may be threaded for secure coupling with the bolt  58 . 
       FIG. 2B  shows the gripping structure  30  that fits with the gear structure  50 . As shown, the gripping structure  30  has an arm  34  having a proximal end  31  and a distal end  33 , and the paddle  32  coupled to the distal end  33 . The arm  34  has one or more teeth  38  formed on it, and the teeth  38  are sized, shaped, and arranged to fit with the spiral-pattern groove  54  of the gear structure  50  such that when the gripping mechanism  30  is combined with the gear structure  50 , the teeth  38  are engaged with the spiral pattern groove  54 . This way, turning the spiral-pattern groove  54  radially pulls the gripping structure  30  in toward the center of the spiral-pattern or pushes it out in the opposite direction. The teeth  38  “ride” the spiral as it turns, continuously moving onto the outer spirals with larger diameters (when the gripping mechanism is pushed out to accommodate a larger object) or moving onto the smaller inner spirals (when the gripping mechanism is pulled in to accommodate a smaller object). Where the arm  34  has only one tooth, the arm  34  functions in substantially the same manner as the arm  34  with multiple teeth. 
     The paddle  32  is shown to be attached to form an angle θ with respect to the arm  34 . This angle θ may be adjusted to fit the application and the shape of the object to be gripped but is typically between about 80 degrees and 120 degrees for gripping-type application. In the embodiment shown, the arm  34  is long enough to lay approximately halfway across the spiral-pattern groove  54  and still extend out of the housing  20 . Hence, the arm  34  is longer than the radius of the spiral-pattern groove  54 . In another embodiment, the arm  34  may be shorter than the radius of the spiral-pattern groove  54  such that it does not extend all the way to the center of the spiral-pattern groove  54 . 
     Where multiple gripping mechanisms  30  are employed, all the gripping mechanisms  30  may have substantially the same structure. In some embodiments, positions of the teeth  38  may vary slightly among the gripping mechanisms  30  to accommodate the spiral so that all the gripping mechanisms lie at approximately equal distance from the center of the spiral. 
       FIG. 2C  shows the housing  20  designed to couple with the gear structure  50 . The housing  20  has a lid  22  that is designed to cover the spiral-pattern groove  54 , and the shaft  40  protrudes from the center of the lid  22 . The rod  56  (see  FIG. 2A ) extends into the shaft  40  through a hole  24  when the housing  20  is combined with the gear structure  50 . The lid  22  has radially extending grooves  26  formed on the surface and contacts the spiral-pattern gear  54 . These radial grooves  26  are shaped and sized to accommodate the gripping structures  30 . Although four equally-spaced radial grooves  26  are shown in  FIG. 2C , this is not a limitation of the invention and the location and number of the grooves  26  may be adapted to the desired application. When the wrench  10  is assembled, the gripping structures  30  get sandwiched between the lid  62  and the spiral-pattern groove  54 , held in place by the radial grooves  26 . When the wrench  10  is assembled and the bolt  58  is turned, the gear structure  50  is turned but not the housing  20 . This allows the gripping mechanisms  30  to “ride” the spiral groove  54  to extend farther out or retract. 
       FIG. 3A  is a cross-sectional view of the wrench  10  of  FIG. 1  that shows how the gear structure  50 , the gripping mechanism  30 , and the housing  20  fit together upon assembly. For clarity of illustration, only one gripping structure  30  is shown. The teeth  38  of the gripping structure  30  are engaged with the spiral-pattern groove  54  of the gear structure  50 , and the arms  34  are held in place by the radial grooves  26  in the housing  20  (see  FIG. 2C ). A ratchet  70  may be used to turn the bolt  58 , which in turn turns the spiral-pattern groove  54  and moves the gripping structure  30  in/out of the housing  20 . A ring  60  may be placed around the outer edge of the lid  22  (e.g., by welding it on the bottom surface of the lid  22  after the arms are in place) to stabilize the gripping mechanism  30  as it slides in and out of the housing  20 . 
       FIG. 3B  is a cross-sectional view of the wrench  10  of  FIG. 3A  with the gripping mechanism  30  extended farther out than in  FIG. 3A .  FIG. 3B  also shows how the position of the handle  42  can be adjusted. 
       FIG. 3A  and  FIG. 3B  show that the lid  22  and the spiral-pattern groove  54  are not flat but sloped all around downward (with respect to  FIG. 3 ) so that the center of the spiral pattern is higher than the edge. The spiral-pattern groove may be described as being formed on an outer surface of a cone with the vertex portion cut off so that there is no pointy portion. The slope of the cone is not a limitation of the invention but may be formed to optimize the functioning of the gear structure  50  in pulling in and pushing out the gripping structures  30 . This slope may also be adjusted to best accommodate the shape of the object being gripped. 
     The curvature of the spiral in the spiral-pattern groove  54  changes with its distance from the center. To help the teeth  38  engage securely with the spiral-pattern groove  54  regardless of the position of the arm  34  on the spiral-pattern groove  54 , the teeth  38  are designed to accommodate different curvatures.  FIG. 4A  is a plan view of the teeth  38  showing how each tooth has two different curvatures and how the curvatures vary between teeth  38 . For simplicity of illustration, the particular view shows three teeth: a first tooth  38   a , a second tooth  38   b , and a third tooth  38   c . In this embodiment, each tooth has a concave surface and a convex surface, and the concave surface is closer to the proximal end  31 . The concave surface  38   a - 1  of the first tooth  38   a  is curved more drastically than the convex surface  38   a - 2 . The concave surface  38   b - 1  of the second tooth  38   b  is curved less than the convex surface  38   a - 2  of the first tooth  38   a , and the convex surface  38   b - 2  of the second tooth  38   b  is curved even less than the concave surface  38   b - 1 . The surface of the tooth that is farther away from the proximal end  31  has less of a curvature. This way, regardless of whether the curvature of the engaging spiral-pattern groove  54  is large or small, the teeth  38  will engage with the groove  54  securely. 
       FIG. 4B  shows another embodiment of the arm  34 . Unlike the embodiment shown in  FIG. 4A , each tooth has two convex surfaces in this embodiment. The curvatures of the convex surfaces may be varied with distance from the proximal end  31 . Each tooth  38   a ,  38   b ,  38   c  may have the same curvature for both surfaces or different curvatures. 
       FIG. 5A  and  FIG. 5B  are cross-sectional views of the arm  34  of the gripping structure  30  engaged with the spiral groove  54  of the gear structure  50 . In the embodiment of  FIG. 5A , the spiral-pattern groove  54  is formed so that the sidewalls of the groove form an approximately 90-degree angle with respect to the bottom of the groove. In this case, the teeth  38  of the arm  34  are formed to fit well with such spiral design. In the embodiment of  FIG. 5B , however, the sidewalls of the groove in the spiral pattern are slanted or angled. As mentioned above, the spiral pattern may be sloped all around so that the center of the spiral pattern is higher than the edge of the pattern. In this case, having slanted grooves as in  FIG. 5B  will help the teeth  38  engage more securely with the gear structure  50  by increasing the pulling force between the teeth  38  and the sidewall of the groove. The teeth  38  are shaped with a slant as well, to fit with the slanted groove design. 
       FIG. 6  shows an alternative embodiment for the wrench  10 . Unlike the embodiment of  FIG. 1 , which provides a handle  42  for turning the wrench  10 , the embodiment of  FIG. 6  has a shaft  40  with a polygonal outer shape. With this embodiment, the wrench  10  would be turned with a wrench. Although the particular shaft  40  shown in  FIG. 6  has a hexagonal outer cross-sectional shape, this is not a limitation of the invention. 
     While the invention has been described in terms of particular embodiments and illustrative figures, those of ordinary skill in the art will recognize that the invention is not limited to the embodiments or figures described. Therefore, it should be understood that the invention can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is not intended to be exhaustive or to limit the invention to the precise form disclosed. It should be understood that the invention can be practiced with modification and alteration and that the invention be limited only by the claims and the equivalents thereof.