Abstract:
A gear shift assembly includes a base, a cylindrical collar extending from the base, a shift rod having generally spherical tip at a first end thereof for engaging a corresponding socket of a transmission, inner and outer gimbal spheres mounted on the shift rod and supported in the collar whereby the outer truncated gimbal sphere may pivot in the collar in a first direction when the shift rod is moved in the first direction and wherein the inner gimbal sphere is supported in the outer truncated gimbal sphere whereby the inner gimbal sphere may pivot inside the outer truncated gimbal sphere in a second direction substantially perpendicular to the first direction when the shift rod is moved in the second direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application for Patent Ser. No. 61/034,247, filed Mar. 6, 2008, and entitled GEAR SHIFT ASSEMBLY, the specification of which is incorporated herein in its entirety by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The current invention relates to gear shifter mechanisms for transmissions, and in particular to a gear shift assembly for a manual transmission of an automobile. 
       BACKGROUND 
       [0003]    Manual shift transmissions found in typical automotive application represents one step of the two step mechanical torque multiplication process (the other step is the rear end differential unit) necessary for an internal combustion engine to operate within an RPM range wherein it produces an ideal level of torque and horsepower for optimal performance and mileage at the varying speeds the vehicle is to be operated. The typical internal combustion engine has torque and horsepower bands wherein the torque and horsepower produced will vary proportionally with the RPM. The typical modern gasoline internal combustion engine useable torque range begins at around 1500 RPM and peaks out at about 4500 RPM so that under ideal conditions, a driver wishes to keep engine RPM within that range or band of power until such time as the vehicle has attained a given desired speed. The rear end differential in a vehicle is usually a fixed drive ratio that cannot be altered unless it is mechanically modified. Therefore, in order to keep an engine RPM within a usable power band, the transmission provides the required varying gear ratios. In order for the driver to select the appropriate gear ratio inside the transmission for this purpose, a device known as a transmission shifter provides the driver with the necessary mechanical connection to the internal transmission gear selection mechanism. 
         [0004]      FIGS. 10-16  illustrate transmissions and gear shifters in accordance with the PRIOR ART. There exist numerous manufacturers of manual transmissions, and the shifter technology has evolved considerably in the past 25 years. Manual transmissions since automobiles first made their appearance in the late 1800&#39;s through the end of 1970&#39;s typically employed an external linkage apparatus that provided a mechanical connection between a shift lever that the driver would move in accordance with a given shift pattern for the transmission being operated and typically up to 3 levers or arms that protruded from various locations on the longitudinal side of the transmission as shown in  FIG. 10  and  FIG. 11 . These levers or arms in turn were connected to forks inside the transmission that when actuated externally via the shifter linkage would move a collar element containing teeth that would engage with a given gear being selected thus engaging that gear in the transmission. Being external to the transmission case and therefore exposed to the elements, the shifter linkage would often suffer considerable wear and require periodic adjustments or repair in order to make sure the gears were being properly selected and fully engaged when the driver move the shifter lever. 
         [0005]    By the early 1980&#39;s a new shifter linkage design began to emerge that replaced the external shift linkage design wherein the shift linkage functionality was built into the transmission case itself in the form of device called a rail gear selector as shown in  FIG. 12  and  FIG. 13 . 
         [0006]    This new design vastly decreased the complexity of the shifter itself by internalizing shifter linkages which also removed them from exposure to the elements. The new shifter design (see  FIG. 14 ) included a single lever assembly having a shift handle at one end (for the driver to grasp and move in order to select gears) and a simple small spherical tip at the other end which would be inserted into an opening on the top of the transmission gear box and rest in a actuator lever having a matching spherically hollowed out cavity. 
         [0007]      FIG. 10  depicts the older late 1950&#39;s through early 1980&#39;s transmission shifter and linkage design and  FIG. 11  shows the same shifter installed on a typical four speed transmission of the time. 
         [0008]      FIG. 12  shows a simplistic diagram of the internal workings of the newer style transmission depicted in  FIG. 13  wherein the entire external gear shift linkage as shown in  FIGS. 10 and 11  has been completely eliminated and an entirely new design has been implemented where the linkage and gear shift mechanism is now internalized inside the transmission. The resulting changes streamline the exterior of the shifter by eliminating external shifter linkage with a simpler design that requires a ball at the end of a rod to rest in the gear selector socket shown in  FIG. 12 . 
         [0009]    The resulting gear shifter itself as shown in  FIG. 14  is simplified compared to prior designs.  FIG. 15  shows a transmission without the shifter installed to illustrate the socket where the ball at the end of the shifter rod is inserted to enable shifting of transmission gears. A variant of the new style transmission shown in  FIG. 13  appears in  FIG. 16  offering three separate positions where shifter can be installed (denoted as Positions  1 ,  2  and  3  in  FIG. 16 ). This position selection allows for variations of driver positions in the vehicle that can vary depending on the wheelbase and interior design of a given vehicle. 
         [0010]    Current shifter designs consist of a simple central ball and socket mechanism. Protruding from the bottom of the central ball is a short rod ending with a spherically shaped tip at its base that is inserted into the socket mechanism of the transmission. Extending upwards in the opposite direction from the central ball of the ball and socket mechanism is a simple rectangular shaft that typically has threaded bolt holes so that a shifter handle can be bolted to it on one end and the other end of the shifter handle is threaded so that a shifter handle can be screwed on to its end. 
         [0011]    Current shifter designs tend to be utilitarian and are designed to be made as inexpensively as possible. As a result, these designs are usually cosmetically unappealing and are typically concealed with some sort of leather or rubber boot so that only the actual shifter handle is visible inside the automobile interior. This cosmetically unappealing design is used regardless of the vehicle, even for vehicles costing hundreds of thousands of dollars. 
       SUMMARY 
       [0012]    According to the present disclosure, in one aspect thereof, a gear shift assembly is provided. The gear shift assembly includes a base having a central aperture for receiving a shift rod. The gear shift assembly also includes a generally cylindrical collar that extends upwardly from the base. A shift rod with a generally spherical tip at a first end for engaging a corresponding socket of a transmission is provided. The shift rod includes a handle at a second end. The shift rod passes through an inner gimbal sphere such that the inner gimbal sphere is positioned between the first and second ends of the shift rod. An outer gimbal sphere is provided that includes an upper outer truncated gimbal hemisphere and a lower truncated gimbal hemisphere. The outer gimbal sphere defines a generally spherical inner cavity for receiving the inner gimbal sphere. 
         [0013]    The outer truncated gimbal sphere is supported in the collar such that the outer truncated gimbal sphere may pivot in the collar in a first direction when the shift rod is moved in the first direction. Further, the inner gimbal sphere is supported in the outer truncated gimbal sphere such that the inner gimbal sphere may pivot inside the outer truncated gimbal sphere in a second direction substantially perpendicular to the first direction when the shift rod is moved in the second direction. The assembly further includes a substantially rigid trim cap. The trim cap has upper and lower openings and a central passage extending therebetween. The shift rod passes though the trim cap with at least a portion of the inner gimbal sphere exposed though through the upper opening. In one embodiment, a portion of the outer gimbal sphere may be exposed through the upper opening. The trim cap engages the collar to secure the trim cap to base. 
         [0014]    The present disclosure, in another aspect thereof, provides a gear shift assembly that includes a base that has a central aperture for receiving a shift rod therethrough. The base includes a plurality of openings for fastening the base to a transmission. A generally cylindrical collar that extends upwardly from the base has an upper wall, a threaded exterior surface, a plurality of spaced apart screw holes extending through the collar and the base, and two opposed semicylindrical openings formed in the top wall of the collar. An upper outer truncated gimbal hemisphere has a bottom wall with four semicylindrical recesses formed at ninety degree intervals in the bottom wall and a plurality of spaced apart screw holes extending into the bottom wall. A lower outer truncated gimbal hemisphere has a top wall with four semicylindrical recesses formed at ninety degree intervals in the top wall and a plurality of screw holes extending through the lower outer truncated gimbal hemisphere. A plurality of screws extend through the screw holes to secure the upper and lower gimbal spheres halves together such that the upper and lower outer gimbal hemispheres form an outer truncated gimbal sphere. The outer truncated gimbal sphere defines a generally spherical inner cavity that opens on opposed sides of the outer, truncated gimbal sphere with the semicylindrical recesses in opposed relationship to form four cylindrical pin receiving openings at ninety degree intervals around a circumference of the outer truncated gimbal sphere. 
         [0015]    A shift rod having spherical tip at a first end thereof for engaging a corresponding socket of a transmission, a handle at a second end thereof and a pivot pin receiving opening formed between the first and second ends is provided. The inner gimbal sphere is positioned between the first and second ends of the shift rod with opposed openings aligned with the pin receiving opening of the shift rod. The inner gimbal sphere is received in the generally spherical inner cavity of the outer, truncated gimbal sphere with the shift rod passing through the collar and central aperture of the base. A first pivot pin extends through the inner gimbal sphere and shift rod. The pivot pin is positioned in opposed ones of the cylindrical pin receiving openings of the truncated outer gimbal sphere. Thus, the inner gimbal sphere may pivot inside the outer gimbal sphere in a first direction when the shift rod is moved in the first direction. 
         [0016]    Second pivot pins are positioned in opposed ones of the cylindrical pin receiving openings and extend from the outer truncated gimbal sphere to engage the opposed semicylindrical openings formed in the top wall of the collar. Thus, the outer truncated gimbal sphere may pivot in the collar in a second direction substantially perpendicular to the first direction when the shift rod is moved in the second direction. 
         [0017]    A plurality of springs are interposed between the base and the outer truncated gimbal sphere. The springs bias the outer truncated gimbal sphere and shifter shaft to a center position. A retaining ring is configured to fit over the upper outer truncated gimbal hemisphere. A plurality of screws extends through the base, the collar and engage the retaining ring to secure the outer, truncated gimbal sphere within the collar. 
         [0018]    A substantially rigid trim cap, having a small diameter upper opening and a large diameter lower opening with a central passage extending between the upper opening and lower opening, is provided. The shifter shaft passes though the trim cap with at least a portion of the inner gimbal sphere exposed though through the small diameter upper opening. The trim cap has internal threads formed around the circumference passage at the lower end for engaging the outer threaded surface of the collar to secure the trim cap to the collar, thereby securing a trim plate to the base. 
         [0019]    The present disclosure, in still another aspect thereof, provides a gear shift assembly comprising a frame, an outer gimbal member and an inner gimbal member. The frame has an upper exterior surface defining a substantially circular first aperture having a first inner diameter. The outer gimbal member is rotatably mounted to the frame to allow rotation relative to the frame about a first axis. An upper portion of the outer gimbal member has a ring-shaped exterior configuration defining a substantially circular outer surface having a second outer diameter and a substantially circular second aperture having a second inner diameter. The second outer diameter is substantially equal to the first inner diameter minus a clearance distance. The outer gimbal member is disposed within the frame such that the upper portion of the outer gimbal member is positioned within the first aperture. The inner gimbal member is rotatably mounted to the outer gimbal member to allow rotation relative to the outer gimbal member about a second axis. The second axis is oriented substantially perpendicular to the first axis. An upper portion of the inner gimbal member has an exterior configuration defining a substantially circular outer surface having a third outer diameter. The third outer diameter is substantially equal to the second inner diameter minus a clearance distance. The inner gimbal member is disposed within the outer gimbal member such that the upper portion of the inner gimbal member is positioned within the second aperture. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0020]    For a more complete understanding, reference is now made to the following description taken in conjunction with the accompanying Drawings in which: 
           [0021]      FIG. 1  is a perspective view of a gear shift assembly according to the present disclosure; 
           [0022]      FIG. 2  is a top view of the base of the shifter assembly of  FIG. 1 ; 
           [0023]      FIG. 3  is a first exploded view of the shifter assembly of  FIG. 1  with some parts omitted for clarity; 
           [0024]      FIG. 4  is a side view of the inner and outer gimbal spheres of the shift assembly of  FIG. 1 ; 
           [0025]      FIG. 5  is a second exploded view of the shift assembly of  FIG. 1  with some parts omitted for clarity; 
           [0026]      FIG. 6  is a first sectional view of the shift assembly of  FIG. 1 ; 
           [0027]      FIG. 7  is a second sectional view of the shift assembly of  FIG. 1  taken at 90° from the sectional view of  FIG. 6 ; 
           [0028]      FIG. 8  is a second perspective view of a shift assembly according to the present disclosure; 
           [0029]      FIG. 9  is a perspective view of the shift assembly of  FIG. 1  installed in an open cockpit, two seat roadster style automobile; 
           [0030]      FIG. 10  shows a vintage shifter and linkage design according to the PRIOR ART; 
           [0031]      FIG. 11  shows the PRIOR ART shifter and linkage design of  FIG. 10  installed on a vintage transmission; 
           [0032]      FIG. 12  shows a schematic diagram of a newer transmission according to the PRIOR ART; 
           [0033]      FIG. 13  shows an external view of the PRIOR ART transmission of  FIG. 12 ; 
           [0034]      FIG. 14  shows another gear shifter design according to the PRIOR ART; 
           [0035]      FIG. 15  shows another PRIOR ART transmission without the shifter installed; and 
           [0036]      FIG. 16  shows a variant of the PRIOR ART transmission of  FIG. 13  with multiple gear shifter mounting locations. 
       
    
    
     DETAILED DESCRIPTION  
       [0037]    Referring now to the drawings, wherein like reference numbers are used herein to designate like elements throughout, the various views and embodiments of a gear shift assembly are illustrated and described, and other possible embodiments are described. The figures are not necessarily drawn to scale, and in some instances the drawings have been exaggerated and/or simplified in places for illustrative purposes only. One of ordinary skill in the art will appreciate the many possible applications and variations based on the following examples of possible embodiments. 
         [0038]      FIG. 1  is a perspective view of a gear shift assembly  10  according to this disclosure. Gear shift assembly  10  is adapted for use with manual transmissions, in particular manual transmissions having four to six speeds. Assembly  10  includes a base  12 , a trim cap  18 , a shift rod  14 , and a handle  16  mounted on the shift rod. As illustrated, base  12  includes a plurality of openings such as bolt holes  20  arranged around the perimeter of the base at locations corresponding to the bolt pattern of a transmission on which the gear shift assembly is mounted. In the illustrated embodiment, base  12  has a rectangular configuration, however, other geometries such as circular, triangular or oblong may be used so long as the openings  20  are correctly positioned in the base to enable shift assembly  10  to match the belt pattern on the applicable transmission. 
         [0039]      FIG. 2  is a top view of base  12  of shift assembly  10 . Base  12  includes a central aperture  22  through which the shift rod of assembly  10  extends to the transmission. Base  12  includes a cylindrical collar  24  extending upwardly from the base. Collar  24  may be integrally formed with base  12  or otherwise fastened to the base. A plurality of openings or screw holes  30  extend through base  12  and collar  24  in a spaced apart relationship around the circumference of the collar. Collar  24  includes a top wall  26  having a pair of semi-cylindrical openings  28  formed in the top wall. 
         [0040]      FIG. 3  is an exploded view of gear shift assembly  10  with the shift rod omitted for clarity. Assembly  10  includes an inner gimbal sphere  56  having a central opening  60  through which shift rod  14  passes. Inter gimbal sphere  56  also includes a pin receiving hole  58  extending through both sides of the inner gimbal sphere that receives a pivot pin  64  for securing shift rod  14  in the inner gimbal sphere. Inner gimbal sphere  56  is received in a lower outer gimbal hemisphere  40 , which has the shape of a truncated hemisphere. Lower outer gimbal hemisphere  40  has a top wall  44  and a plurality of screw holes  46  formed through the hemisphere and upper wall  44 . Four semi-cylindrical recesses  42  are formed in the lower outer gimbal hemisphere  40 . An upper outer gimbal hemisphere  32 , also having the shape of a truncated hemisphere, fits over inner gimbal sphere  56  and includes a bottom wall  34  having a plurality of screw holes  38  formed therein. Upper gimbal hemisphere  32  also includes four semi-cylindrical recesses  36  formed in a bottom wall  34  thereof. 
         [0041]      FIG. 4  is a side view of inner gimbal sphere  56  positioned in upper and lower gimbal hemispheres  32  and  40 . Upper and lower gimbal hemispheres  32  and  40  together form an outer gimbal sphere  50  having truncated upper and lower sides. Outer gimbal sphere  50  defines a generally spherical inner cavity  52  having a geometry corresponding to the outer surface of inner gimbal sphere  56 . Outer gimbal sphere  50  and inner gimbal sphere  56  are formed to have a relatively tight clearance therebetween on the order of several thousandths of an inch or less. As illustrated, the semi-cylindrical recesses  36  and  42 , formed in the upper and lower gimbal hemispheres  32  and  40  form four cylindrical pin receiving openings  54 . 
         [0042]    Referring again to  FIG. 3 , upper gimbal hemisphere  32  is secured to lower gimbal hemisphere  40  with a plurality of screws  48  that extend through screw holes  46  and  38  in the upper and lower gimbal hemispheres. In the illustrated embodiment, a plurality of cut-outs  45  are formed in the lower gimbal hemisphere in the area of screw holes  46 . In other embodiments, cut-outs  45  may be omitted. A retaining ring  70  configured to fit over upper gimbal hemisphere  32  includes a plurality of threaded openings  84  formed around the circumference of the retaining ring. A plurality of cap head screws  72  extend up through base  12 , screw holes  30  and collar  24  and engage threaded openings  84  of retaining ring  70  to secure the inner and outer gimbal spheres  56  and  50  in the collar. 
         [0043]      FIG. 5  is a partial exploded view of gear shift assembly  10  with parts omitted for clarity. As illustrated, inner gimbal sphere  56  is positioned approximately midway along the length of shift rod  14  and is secured onto the shift rod with pivot pin  64  that extends through pin receiving holes  58  and a corresponding hole in the shift rod. The ends of pivot pin  64  are received in two of the four pin receiving openings  54  ( FIG. 4 ) in outer gimbal sphere  50 . This configuration allows shift rod  14  and inner gimbal sphere  56  to pivot in the fore and aft direction within the outer gimbal sphere  50 . 
         [0044]    A pair of short pivot pins  62  are retained in the remaining two cylindrical pin receiving openings  54  in outer gimbal sphere  50 . The ends of short pivot pin  62  are received in semi-cylindrical recesses  28  formed in collar  24 . This configuration allows the shift rod, inner gimbal sphere and outer gimbal sphere to pivot from side to side within collar  24 . A pair of followers  68  are received in springs  66  interposed between base  12  and the lower outer gimbal hemisphere  40 . Springs  66  bias the outer hemisphere  50  and shift rod  14  to a center position. Followers  68  prevent springs  66  from wearing against the bottom of outer hemisphere  40 . 
         [0045]      FIG. 6  is a partial sectional view taken through short pivot pins  62  of shift assembly  10 . In one embodiment, short pivot pins  62  are secured in position in lower outer gimbal hemisphere  40  with set screws  86 . As illustrated, shift rod  14  includes a spherical tip formed at the end of the shift rod opposite handle  14 . Spherical tip  80  is configured to engage a corresponding feature in the transmission that assembly  10  is mounted on. 
         [0046]      FIG. 7  is a second sectional view of shift assembly  10  taken through pivot pin  64  of  FIG. 5 . As illustrated, pivot pin  64  passes through a pivot hole  88  formed in shift rod  14 . The ends of pivot pin  64  are received in pivot receiving holes  54  ( FIG. 4 ) formed in outer gimbal sphere  50  to enable the shift rod to pivot around the pin in a fore and aft direction. 
         [0047]    Referring again to  FIG. 3 , trim cap  18  has a generally hemispherical configuration with a central opening or passage  79  extending between a small diameter upper opening  76  and a large diameter lower opening  78 . Trim cap  18  also includes internal threads  82  formed around the circumference of central passage  80  adjacent to large diameter lower opening  78 . Threads  82  are configured to engage a threaded surface  74  of collar  24  to secure the trim cap to base  12 . 
         [0048]      FIG. 8  is a perspective view of a shift assembly  10  according to the disclosure incorporating a trim plate  90 . In the embodiment shown in  FIG. 8 , a trim plate  90  is configured to fit over base  12 . Trim plate  90  is secured onto base  12  by trim cap  18  which is secured to collar  24 . 
         [0049]      FIG. 9  is a perspective view of shift assembly according to the disclosure installed in an open cockpit two seat roadster style automobile. In contrast to the unsightly rubber or leather boots used to cover prior art shift assemblies trim cap  18  and trim plate  84  are formed from substantially rigid materials such as metals or suitable plastics. The exposed surfaces of trim plate  84 , trim cap  18  and the exposed portion of inner sphere  56  may be polished or otherwise treated to present in an aesthetically pleasing appearance. 
         [0050]    It will be appreciated by those skilled in the art having the benefit of this disclosure that this gear shift assembly provides a gear shift assembly for a manual transmission of a vehicle. It should be understood that the drawings and detailed description herein are to be regarded in an illustrative rather than a restrictive manner, and are not intended to be limiting to the particular forms and examples disclosed. On the contrary, included are any further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments apparent to those of ordinary skill in the art, without departing from the spirit and scope hereof, as defined by the following claims. Thus, it is intended that the following claims be interpreted to embrace all such further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments.