Abstract:
A flexible locking dipstick module useful with a motor vehicle transmission including a transmission case. A transmission dipstick is disposed within a housing which has one end thereof affixed to the transmission case and extends therefrom to a location within the engine compartment of a motor vehicle. Each end of the module includes a quick disconnect locking coupling providing for ready installation of the dipstick housing and its associated dipstick. Each coupling further provides protection against blow out of the dipstick in the event of inordinate build up of pressure within the transmission. Further, one portion of the outboard coupling may be employed as a liquid-tight closure for a dipstick entry opening in the transmission case during removal and/or storage of the transmission case.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Not Applicable 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable 
   FIELD OF INVENTION 
   This invention relates to motor vehicle parts and accessories and particularly to dipsticks useful in the transmission case for a motor vehicle. 
   BACKGROUND OF INVENTION 
   In motor vehicles, dipsticks are employed for purposes of visual inspection of the quantity (and to a lesser degree of the quality) of transmission fluid located within a closed transmission case of a motor vehicle. In general, transmission cases of motor vehicles commonly are provided with an opening leading from external of the transmission case into the interior of the case. Often this opening is provided with a fitting, such as a hollow tube. A first end of the tube is mounted in the opening leading into the transmission case. The tube extends from the fitting to a termination location within the engine compartment of the vehicle, but remote from the transmission case. Thus, the open terminal end of the tube is readily accessible within the engine compartment of a motor vehicle. An elongated removable dipstick may be inserted into the terminal end of the tube and into the interior of the transmission case. Within the transmission case, the end of the dipstick becomes immersed within the fluid disposed within the case. The extent of insertion of the dipstick into the case is limited to a constant value established commonly by some form of stop on the dipstick which engages the terminal end of the tube to limit that distance by which the dipstick may be inserted into the case. Such extent of insertion distance is thus maintained constant over each and every time the dipstick is inserted into the case. By this means, upon withdrawal of the dipstick from the case, the level of fluid on that end of the dipstick which is inserted into the case is indicative of the level (quantity) of fluid within the case. Other than during the action of checking the level of fluid with the case, the dipstick is stored within its tubular housing. 
   As noted, commonly, such dipsticks are removably mounted within an elongated tubular housing which is itself anchored at one end thereof within the opening through the transmission case. Such tubular housing commonly extends from the transmission case upwardly to terminate at a location, commonly within the engine compartment of the vehicle, wherein the dipstick is readily grasped for insertion into and withdrawal from its tubular housing and the transmission case. For example, the outboard terminal end of the dipstick housing commonly may be anchored to a suitable location on the engine or on the fire wall or other element of the motor vehicle within the engine compartment of the vehicle to ensure rigidity of the tubular housing and its enclosed dipstick during operation of the motor vehicle. Dipsticks commonly are secured within their tubular housing employing some form of structure suitable for grasping with one&#39;s hand for removal and reinsertion of the dipstick relative to its housing. This structure may include an element which is frictionally slidably received within the outboard end of the tubular housing and serves in part to seal off the open outboard end of the housing. These devices are prone to leakage of transmission fluid from the tubular housing and fail to ensure the retention of the dipstick within the housing under certain vehicle operating conditions. 
   In certain motor vehicles, such as racing cars, the operation of the vehicle builds up substantially inordinate pressure within the transmission case. Such pressure levels may be sufficient to “blow out” a prior art dipstick from its elongated tubular housing with obvious disastrous results which may include starting a fire within the engine compartment of the vehicle. Also, there exist the problems associated with oil leaking onto a race track, resulting in slick tires, crashes and monetary penalties. 
   Further, in racing cars in particular, transmissions are not uncommonly subjected to forces sufficient to cause partial or complete operational failure of the transmission. Upon such failure of the transmission, it is common for the mechanic team for the racing car, in the course of a given race, to change out the entire nonfunctional transmission and replace it with an operational transmission. Obviously such transfer of transmissions must be completed within a minimum of time. In the prior art, precious seconds may be consumed in connection with the removal of a transmission dipstick and its housing from a “blown” transmission and replacement of the same with a new housing (and dipstick) while at the same time trying to minimize the time consumed in replacing the overall transmission. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  is a representation, part in section, of a dipstick module embodying various aspects of the present invention; 
       FIG. 2  is a representation, part in section, of one embodiment of an inboard quick release coupling of the present invention disposed intermediate a dipstick housing and an opening leading into the transmission case; 
       FIG. 3  is an exploded side elevation representation, part in section, of the inboard quick release coupling depicted in  FIG. 2 ; 
       FIG. 4  is a representation, part in section, of one embodiment of an outboard quick release coupling of the present invention as mountable on the outboard end of a dipstick housing; 
       FIG. 5  is an exploded side elevation representation, part in section, of the outboard coupling depicted in  FIG. 4 ; and, 
       FIG. 6  is a representation of the insertion of a plug into the inboard coupling of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In one embodiment of the present invention depicted in the several figures, there is provided a transmission dipstick module  10  which includes an elongated, hollow, flexible dipstick housing  12 . In a preferred embodiment this housing comprises braided metallic strands disposed about a fluid impervious flexible inner lining  14 , thereby rendering the housing flexible and resistant to rupture. A typical housing exhibits an internal diameter of between about ⅜″ and about ¾″ inch and is capable of withstanding fluid pressures in excess of several hundred lb/in 2 . 
   Again, preferably, the housing is provided with an internal lining suitable for accommodating the flexibility of the housing and enhancing the insertion and withdrawal of a flexible dipstick  16  along the length of the housing. One suitable lining material is a polymeric material such as Teflon which is resistant to the transmission fluid. Other liner materials may be employed. 
   In accordance with one aspect of the present invention, the inboard first end  18  of the dipstick housing is removably anchored to the transmission case  20  and the outboard second end  28  is secured, as by a bracket  24 , at a location within the engine compartment, for example, where the outboard second end  28  of the housing is readily accessible for the insertion and withdrawal of the dipstick in and out of the housing. 
   To this end, as depicted in  FIGS. 1-3 , the interconnection of the inboard end  18  of the housing to the transmission case is in the form of an inboard quick disconnect coupling  30  which includes a generally tubular first element  32  adapted to be fixed to the transmission case in the opening  33  through the wall  34  of the transmission case  20  and a second generally tubular element  36  which is fixed to the inboard end  18  of the housing. These two elements are adapted to be quickly and securely interconnected liquid-tight. For example, the interconnection of the first and second elements will remain liquid-tight if exposed to relatively high fluid pressure exceeding several hundred lbs/in 2 . As noted, this coupling is quickly and readily connected and/or disconnected. 
   As depicted in FIGS.  1  and  4 - 6 , the outboard terminal end  28  of the dipstick housing is provided with an outboard quick disconnect coupling  40 . This outboard coupling includes mating first and second elements  41  and  43 , respectively. The first element  41  of this outboard coupling  40  comprises an generally tubular body portion  42  having an inboard end  44  which is adapted to be affixed to the outboard end  28  of the dipstick housing  12 . 
   The second element  43  of the outboard coupling  40  comprises a knob  46  having a first end  48  which preferably is contoured in a manner to facilitate grasping of the knob in a user&#39;s hand. The opposite and second end  50  of the knob includes an elongated projection  52  extending linearly from the second end of the knob and is adapted to be interconnected with the outboard end  22  of the dipstick  16 , as by means of a set screw  38 , for example. This projection is further adapted to be sealingly and releasably received within the open end  54  of the first element  41  of the outboard coupling  40  opposite the dipstick housing. 
   The projection  52  which extends from the knob is in the form of a plug adapted to be received in liquid-tight sealing, but removable, relationship within the first element  41  of the outboard coupling  40  when the dipstick is inserted within its housing. Thus, the outboard coupling  40  functions first to seal liquid-tight the outboard coupling  40  to the outboard end  28  of the housing and to establish the extent to which the dipstick may enter the dipstick housing, hence the depth to which the inboard end  56  of the dipstick may become immersed in transmission fluid contained within the transmission case, and as an aid to preclude expulsion of the knob (i.e., the plug), hence the dipstick, in the event of a buildup of potentially damaging fluid pressure within the transmission case. 
   As depicted in  FIGS. 1 ,  3  and  6 , in one embodiment, the inboard quick disconnect coupling  30  associated with the transmission case and disposed intermediate the case and the inboard end  18  of the dipstick housing, comprises a first element  32  adapted to be mounted within the opening  33  in the transmission case and a second element  36  which is adapted to be quickly releasable from the first element. 
   In one embodiment, the first element  32  of the inboard quick disconnect coupling  30  includes a generally tubular body portion  58  having an externally threaded generally tubular extension  60  projecting therefrom and adapted to be threaded into the opening  33  in the transmission case  20 . It will be recognized that means, other than threads, may be employed for suitably interconnecting the tubular extension  60  with the opening in the transmission case. A lock nut  64  may be employed to secure this first element in the transmission case opening. Further, in one embodiment, the inboard portion of the extension may be provided with an encircling sleeve  66  of a material suitable for forming a liquid-tight seal between the body portion  58  of the first element  32  and the transmission case. In one embodiment, this sleeve may be of a polymeric material which is resistant to damage by transmission fluid and which is sufficiently resilient to define the desired seal against leakage of transmission fluid out of the transmission case. It will be recognized by one skilled in the art that other sealing means and/or seals of non-polymeric materials may be employed. As needed for differently designed transmissions, there may be provided a washer-type spacer  68  suitable to encircle the projection of the body portion into the transmission case and to be interposed between the lock nut  64  and the inner wall  70  of the transmission case. 
   The opposite (inboard) end  72  of the body portion  58  of the first element  32  of the inboard coupling  36  also is generally tubular, and houses internally thereof, an “O” ring, a coil spring  74 , a snap ring  73  and a plurality of ball bearings  76  which are partially embedded within appropriate throughholes  78  in the inner wall  80  of the body portion of the first element  32  of the inboard coupling at circumferentially spaced apart locations. In the depicted embodiment, the throughholes are contoured to permit each ball bearing to project outwardly from the outer circumference of the outboard end  72  of the first element proximate its outboard end  72 . 
   As depicted in  FIGS. 2 and 3 , the body portion  58  of the first element  32  of the inboard coupling  30  is provided with a circumferential open groove  82  in the inner wall  84  of the body portion at a location approximately half-way between the opposite ends of the body portion. This groove is sized to accept therein the outboard end  44  of the second element  36  of the inboard coupling  30  as will appear hereinafter. Immediately adjacent the open groove  82  and on the inboard side of the open groove  82 , there is provided a further circumferential groove  86  which is of a larger outer diameter than the open groove  82  and defines an annular receptacle for the ring seal  88  when the first and second elements  32  and  36 , respectively are coupled. 
   Externally of the inboard end  72  of the body portion  58  of the first element  32  of the inboard coupling  30  there is provided a circumferential collar  90  which is slideable along such inboard end  72  between an outer circumferential shoulder  92  defined on the outer circumference of the body portion  58  approximately half-way between the opposite ends of the body portion and a split ring retainer  73  disposed within a further circumferential groove  94  proximate the inboard end  72  of the outer wall  71  of the body portion  58 . This collar is of an inner diameter greater than the outer diameter of the inboard end of the body portion  58  so that there is defined between the collar and the outer surface  71  of the inboard end of the body portion an open annular space  96 . 
   Further, the collar  90  is provided with a circumferential flange  98  on the inboard end of the inner wall  91  of the collar. This flange serves, among other things, to establish concentricity between the collar and the underlying outer wall  71  of the inboard end  72  of the body portion  58 . 
   Within the annular space  96  between the collar and the inboard end of the body portion of the first element, there is provided a coil spring  74  which encircles the outer circumference of the inboard end of the body portion of the first element. This spring is captured in the open space  96  between the collar and the outer wall of the body portion of the first element, and between the circumferential flange on the outer wall of the body portion of the first element and the circumferential flange on the inboard end of the inner wall of the collar. The spring thus functions to bias the collar toward a position proximate the inboard end of the first element  32 . 
   As depicted, the split ring retainer  73  disposed in the further groove  94  within the outer wall  71  of the inboard end of the body portion  58  is adapted to halt the outward movement of the collar and prevent the collar from sliding off the inboard end of the body portion of the first element of the inboard coupling. 
   Within the inner wall  80  of the body portion  58  of the first element  32  of the inboard coupling  30  there is provided a plurality of ball bearings  76  which are partially embedded within respective throughholes  78  in the inner wall of the body portion of the outboard coupling proximate, but interiorly of, the retention ring  73 . The depth of embedment of each ball bearing provides for a relatively small portion of the outer surface of each ball bearing to project radially inwardly from the inner wall  84  of the inboard end of the body portion  58  of the inboard coupling into the hollow central space  100  of the inboard end of the body portion, thereby being in position to engage the second element  36  of the inboard coupling within the first element  32 . To this end, the circumferential flange  98  may be brought into circumferential register with the ball bearings thereby locking the ball bearings into their detents by the established maximum extent, hence releasably locking the first and second elements  32  and  36  in sealed liquid-tight relationship to one another. 
   The tubular dipstick housing  12  of the depicted embodiment of the present invention includes a first end, designated herein as the inboard end  18 , (i.e. nearest the transmission) which slidably passes through he inboard coupling  30  and into the transmission case. 
   For interconnection of the dipstick housing and the second element of the inboard coupling  30 , the second element  36  of the inboard quick disconnect coupling includes a first tubular end  102  which is sized and internally outwardly tapered to receive thereon the inboard end  18  of the dipstick housing. The outer circumference of this first end of the second element is provided with external threads  106  adapted to matingly receive the internal threads  110  of a truncated conical shroud  112  having an inwardly tapered throughbore  114  extending along at least a portion of the length of the shroud thereby providing an open inlet end  116 . When the inboard end  18  of the dipstick housing  12  is fitted onto the tapered end of the inboard second element  36 , the shroud is threaded onto such end of the second element, thereby capturing the inboard end  18  of the dipstick housing therebetween and anchoring the second element  36  to the dipstick housing. 
   As noted, the central hollow interiors of the first and second elements  32  and  36  of the inboard coupling  30  are in alignment with one another to permit the passage therethrough of the dipstick (or for the introduction of transmission fluid into the transmission case, if desired). 
   The second element  36  of the inboard coupling  30  is designed to be received in and releasably locked to the first element  32  of this inboard coupling. To this end, intermediate the opposite first  122  and second  124  ends of the second element  36  there is provided an external circumferential shoulder  118  defining a stop  120 . On the second end  124  of the second element  36 , there is provided a cylindrical projection  126  between the stop  120  and the inboard end of this second element  36 . On the outer diameter of this cylindrical portion of the second element there are defined first and second circumferential grooves  128  and  130 , respectively, the first of which is located proximate the stop  120  and the second of which is located proximate the inboard end  124  of this cylindrical projection  126 . 
   To permit insertion of the projection  126  on the inboard end  124  of the second element of the inboard coupling  30  into the open outboard end  72  of the first element  32  of the inboard coupling  30 , the circumferential groove  130  is cut sufficiently deep and wide as to reduce the outer diameter of this inboard end  124  to enter into the groove  82  defined internally of the first element  32  of this inboard coupling  30 , and further to permit the receipt therein of the ring seal  88 . When these first and second elements of the outboard coupling are fully engaged (including locking of the ball bearings in their respective throughbores), the foregoing described structure defines a liquid-tight seal at a location approximately halfway between the opposite ends of the inboard coupling  30 . Various of the outboard elements of the quick disconnect coupling are designated by primed numerals to indicate their like construction as the elements of the inboard coupling  30 . 
   The second circumferential groove  128  defined on the outboard end  44  of the second element  36  of the inboard coupling  30  is so positioned as to be in register with the ring of ball bearings  76  disposed within the outboard end  72  of the first element  32  of the inboard coupling when the first and second elements of this coupling are fully engaged. It is to be noted that full insertion of the end  44  of the second element  36  into the open end  72  of the first element  32  of the inboard coupling  30  can only be accomplished when the collar  90  encircling the first element  32  of the coupling is urged longitudinally inwardly of the first element  32  against the force of the coil spring  74 , thereby moving the internal shoulder  98  of the collar away from the ball bearings  76  in the wall of the first element  32 . Upon such retraction of the collar, full insertion of the end  44  of the second element  36  into the open end  72  of the first element  32  serves to position the circumferential groove  128  of the second element  36  into alignment with the ring of ball bearings disposed in the inboard end of the first element. Thereupon, the collar may be released resulting in movement of the shoulder thereof into register with the ball bearings, thereby locking the first and second elements of the inboard coupling together. Decoupling of the first and second elements of the inboard coupling is effected by again urging the collar inwardly of the first element, thereby releasing the ball bearings to the extent necessary for separation of the first and second elements. 
   As depicted in  FIGS. 4 and 5 , it will be recognized that the outboard end  28  of the dipstick housing  12  is attached to the outboard coupling  40  in substantially like manner as the connection of the inboard end  18  of the dipstick housing to the inboard coupling  30 . Further, the mechanism for coupling and decoupling of the first and second elements  41  and  43 , respectively, of the outboard coupling  40  are of construction and function which are substantially similar to the construction and functioning of the aforedescribed inboard coupling  30 . 
   Notably, the second element  43  of the outboard coupling  40  of the present invention comprises a knob  46  whose geometry defines a type of plug  45  which is contoured for ready grasping by a user&#39;s hand for effecting insertion and withdrawal of the second element from the mating first element  41 . As with the inboard coupling, coupling and uncoupling of the first and second elements  41 ,  43  of the outboard coupling requires linear movement of a collar  90 ′ disposed on the first element  41  of the outboard coupling  40 . More specifically, the first element  41  of the outboard coupling defines an open central space  100 ′ into which a projection  52  on the second element  43  is removeably received. As with the inboard coupling, locking and unlocking of the first and second elements  41 ,  43  of the outboard coupling includes sliding the collar  90 ′ against the retaining force of a coil spring  74 ′ away from its locking position relative to the ball bearings  76 ′ and either insertion or withdrawal of the projection  52 ′ into coupled or uncoupled engagement with the first element  41 . In the outboard coupling, the multiple grooves  82 ′,  86 ′,  94 ′,  130 ′ and  128 ′, as well as the seal ring  88 ′ and the split ring retainer  73 ′ are identical to and function like their counterparts in the inboard coupling. 
   As depicted in  FIG. 4 , attachment of the outboard end  28  of the dipstick housing  12  to the first element  42  of the outboard coupling  40  is accomplished by means of a shroud  112 ′ having an open end  116 ′ and a throughbore  114 ′, these elements also being structured and functioning as their counterparts as described in discussing the inboard coupling  30  hereinabove. 
   As depicted in  FIGS. 4 and 5 , the inboard end of the second element  43  of the outboard coupling  40  is provided with a blind bore  132  adapted to receive therein the outboard end  22  of the dipstick  16 . That portion of the dipstick which resides within such blind bore is anchored therein as by a set screw  38 , or other suitable connector, disposed within an internally threaded bore which extends from the external wall of the plug into the blind bore. Thus, withdrawal or insertion of the dipstick from its housing, hence from the interior of the transmission case, may be accomplished via the plug. Importantly, this plug is releasably locked against expulsion of such plug from the first element  41  upon substantial buildup of pressure within the transmission case and within the dipstick housing which is in fluid flow communication with the interior of the transmission case, by like elements as described in connection with the inboard coupling  30 , e.g. locked ball bearings, etc. 
   As seen in  FIG. 1  there may be provided a bracket  24  adapted to mount the outboard coupling to a location within the engine compartment. When the present invention is so mounted, the inboard coupling may be readily and quickly decoupled, thereby providing for quick disconnection of the dipstick housing from the transmission case to permit removal and replacement of the transmission without consuming valuable time in the dismounting and remounting of the dipstick housing within the engine compartment. 
   As depicted in  FIG. 6 , in those instances where it is desired to place a transmission fitted with the present invention into storage, either short term or extended storage, upon decoupling of the inboard coupling, the knob  46  of the outboard coupling  40  (with the dipstick and its housing removed) may be coupled with the first element  32  of the inboard coupling  30  to seal the throughbore in the transmission case against loss of fluid from, or undesirable entry of debris or other foreign matter into, the case of the stored transmission. 
   While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept.