Patent Publication Number: US-7217090-B1

Title: Seals

Description:
This application claims the benefits under 35 U.S.C. § 119(e) of the U.S. provisional patent application 60/567,188 filed and 60/567,189 on Apr. 30, 2004 
   RELATED APPLICATIONS 
   This invention relates to the pneumatic motor entitled SURGICAL PNEUMATIC MOTOR and was invented by myself and co-inventor Douglas Perry and identified as Provisional Application No. 60/567,188 recently filed as a non-provisional application and is incorporated herein by reference and is commonly assigned to The Anspach Effort, Inc. 

   FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable 
   TECHNICAL FIELD 
   This invention relates to seals and particularly to seals that are made operative in situ and to seals that serve to separate the air/oil mist used in lubrication of high speed rotary machines and to both of these seals that operate in conjunction with each other to prevent lubricant leakage. 
   BACKGROUND OF THE INVENTION 
   As is well known by those skilled in the sealing technology leakage of the oil intended to lubricate the components of a motor in a high speed rotating machine is and continues to be a serious concern not only because of the inefficient use of the lubricant but because the escaped lubricant can be a hazard to the environment as well as being a serious problem in the operation of the rotary machine in application where the high speed machine is being utilized. The latter is a real concern in the medical environment where it is abundantly important to prevent contamination of the patient and the operating equipment that is used in surgery. 
   This invention has solved this problem by the use of two inventive seals that independently are unique and when placed in tandem in a lubricated ball bearing environment have proven to be 100% leak proof. According to this invention, the seals are a disk shaped made from a thermal setting material such as Teflon® and are fixedly mounted around the rotating shaft such that they are static, and one of the seals is disk shaped and mounted adjacent to a judiciously spaced seal retainer that serves to angle that seal relative to the shaft for defining a lip. The other seal is also disk shaped, and is judiciously mounted relative to the inner race of the ball bearing in the rotating machine so that the oil of an air/oil mist is slung toward the direction of the centrifugal force and the air is allowed to flow in a direction opposite to the direction of the centrifugal force so that the delta pressure across the seal will dictate the leakage of air. Both seals are made operative in situ by rotating the machine to generate sufficient heat to deform the seals and cause them to set so that it virtually allows only the air to escape while trapping the oil. These seals when mounted in tandem serve to maintain a leak proof sealing device. 
   An example where this invention is efficacious is where a vane motor in a pneumatic surgical motor powers a surgical drill or other medical instruments and the vane motor is supported by ball bearings. This invention locates the tandem seals downstream of the ball bearings where one of the seals is adjacent to the inner race of the ball bearing and the other is spaced axially downstream thereof. An oil/mist is utilized to flow into the vane motor to lubricate the vanes and the seals prevent the oil to leak in the mechanism that supports the drill or other surgical instruments to assure that these parts as well as the patient and the ambient do not become contaminated by leakage oil. 
   SUMMARY OF THE INVENTION 
   The foregoing and other features of the present invention will become more apparent from the following description and accompanying drawings. 
   An object of this invention is to provide a seal system that improves the sealing characteristics of an instrument that operates at a high rotational speed. 
   A further object of this invention is to provide in a high speed rotating machine a seal set and cured in situ is mounted adjacent to the inner race of a ball bearing used in the machine such that the oil in an oil/air mist lubrication system is slung upwardly in the direction of the centrifugal force and the air is directed along the rotating shaft and outwardly of the seal and the air is directed to flow along the shaft of the rotating machine. 
   Another object of this invention is to provide a seal made from a thermal setting material that is rendered operative in situ. One of the seals is contoured in the shape of a disk and is mounted to be angularly disposed relative to the adjacent rotating shaft by subjecting the seal to the high speed operation of the machine so that the heat generated by the friction deforms the seal in the operative mode. 
   Another object of this invention is to provide a seal system for a high speed rotational machine powered by a vane motor that is lubricated by an oil/mist including the first seal described in the above paragraph and the second seal described in the above paragraph mounted in tandem such that the first seal directs the oil of the oil mist in the direction of the centrifugal force and the air is passed to the second seal where the air is allowed to leak as a function of the Δ pressure across the seal. 
   A feature of this invention is to provide seals as described above made from a Teflon® material and set and cured in situ. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a partial view partly in full and partly in section of a pneumatic drill powered by a vane motor illustrating the seals of this invention; 
       FIG. 2  is a sectional view illustrating the seal/bearing housing of this invention; 
       FIG. 3  is a sectional view illustrating the seal support washer of this invention; 
       FIG. 4  is a view in section of the seal retaining nut of this invention; 
       FIG. 5  is a plan view illustrating the seals of this invention; 
       FIG. 5A  is a side view of the seal depicted in  FIG. 5 ; and 
       FIG. 6  is a view in section and schematic illustrating an example of the seals of this invention mounted in tandem used in a surgical drill powered by a vane motor. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While this invention is being described in its preferred embodiment as seals that are utilized in a surgical pneumatic drill powered by a vane motor  11  utilizing the two tandem mounted unique seals of this invention, as one skilled in the art will appreciate one of the seals of the two seals can equally be employed in a surgical drill and one or both seals can be employed in other rotary machines used in the medical field or in rotary machines used for other applications. 
   Referring to all of the Figs. and as best seen in  FIGS. 1 and 6 , the inventive seals generally illustrated by reference numerals  10  and  12  are mounted in tandem in a rotary machine generally illustrated by reference numeral  14  which in this instance is a surgical pneumatic drill powered by vane motor  11 . For the sake of convenience and simplicity the details of the surgical pneumatic motor are eliminated hear from and reference can be made to the description in the Provisional patent No. 60/567,188 filed on Apr. 30, 2004 and U.S. Pat. No. 6,329,778 granted to Culp et al on Dec. 11, 2001. Suffice it to say that a typical surgical pneumatic motor includes a vane motor for driving an output shaft and chuck means for attaching the drill bits or other surgical instruments thereto. The seals, obviously, serve to prevent oil from escaping from the motor into the ambient. It goes without saying that some seals and/or seal systems are more effective than others. This invention has proven to be leak free so that no oil escapes into the environment. 
   The seals  10  and  12  are shown mounted in tandem downstream from the ball bearing  16  and are preferably made from a synthetic material such as Teflon® which is a thermosetting material. First consider the seal  10  which are preferably two identical disc seals illustrated in  FIGS. 5 and 5A  which is a plan view and a side view. As noted the seals  10  and  12  are configured in the shape of a washer and include a circular shaped main body  13  and the central opening  18  that fits over the shaft  20  ( FIG. 1 ). 
   Considering the seal  12  which is fitted into the seal/bearing housing  22  shown in  FIGS. 1 ,  3  and  6  and when assembled is press fitted therein. Seal  12  in this instance is made from two identical main bodies  13  and are disposed into the seal/bearing housing  22  between the seal retaining nut  24  and seal support washer  26  as will described immediately below. The seal  12  is press fitted against the inner and outer races  30  and  32 , respectively of ball bearing  16  as will be described in further detail herein below. 
   Referring again to seal  12 , during assembly, the seal support washer  26  is first inserted into the seal/bearing housing  22  with the beveled face  46  located to receive the seal  10 . The two main bodies  13  of the seal  12  are inserted into the seal/bearing housing  22  in the shape depicted in  FIGS. 5 and 5A . Then the seal retaining nut  24  is threadably fitted into the end  34  of the seal/bearing housing  22  via the internal threads  36  of the seal/bearing housing  22  and the external threads  38  formed on the outer periphery  40  to the seal retaining nut  24 . Seal  12  is wedged between the beveled face  44  of the seal retaining nut  24  and the beveled face  46  of the seal support washer  26 . This action forces the seal  12  to assume the angled position relative to the shaft  52 . The bearing, seal support housing  22  define a rigid solid connection between the seal retaining nut  24  and the vane motor  11 , only partially shown. 
   It is apparent from the foregoing, that when the fixed double seal  12  is assembled and the seal retaining nut is torqued down the seals  12  will be disposed angularly relative to the center line of the shaft  52  and the bottom  54  of the pair of seals  12  will be inclined relative to shaft  52  with the edges thereof define lips  56  bearing against the shaft  52 . After assembly, the machine is operated with the seals in situ so that the shaft  52  rotates at sufficient rpm to cause the seals  12  to heat and become set to define a minuscule opening between the edge  56  of the seal  12  and the rotating shaft  52 . This opening is sufficient to allow the air to escape and prevent the oil from leaking. 
   Seal  10  is identical in material and size to the main body  13  of the seal  12  and is wedged between the outer face  60  of the seal support washer  26  and the outer surfaces of the inner race  30  and outer race  32  of bearing  16 . According to this invention the seal  10  is urged against the inner race  30  and is spaced from the outer race  32  and the inner end of seal  10  is spaced from the shaft  52 . As noted the seals  10  and  12  are in fixed relationship to the rotating shaft  52  and the inner race  30  rotates with shaft  52 . This seal  10  is also set and cured in situ as was described in connection with seal  12 . As best seen in  FIG. 6  the rotary machine  14  is lubricated by flowing an air/oil mist into the machine as shown and toward the bearing  16 . The whirling action of the inner race  30  with respect to seal  10  causes the oil of the oil/mist to be slung and flow in the direction of the centrifugal force as shown by the arrow labeled oil and the air flows through the minuscule opening defined by the edges  56  of seal  12  and the surface of the shaft  52 . 
   What has been shown by this invention are two seals that are individually unique and define face seals that when employed as a sealing system for a rotary machine that is lubricated by an oil/air mist, the seals serve to reduce heat generation and provide a sling action to the oil. The seals are deformed and cured in situ and the seal adjacent the bearing bears against the inner race thereof and when operative serves to prevent oil from escaping into the ambient and into the component parts downstream of the seals. 
   Although this invention has been shown and described with respect to detailed embodiments thereof, it will be appreciated and understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the disclosed invention.