Abstract:
The atmospheric pressure of lubricant containing cavities, from which leakage occurs, is lowered to a point below atmospheric pressure such that air from the environment is drawn thereinto. Since the air being drawn in occupies the passages through which lubricant leakage occurs, such leakage is effectively retarded.

Description:
BACKGROUND OF THE INVENTION 
     This invention is related to the retardation of lubricant leaks in machinery and in particular to lubricant leaks in industrial sewing machines. 
     Oil leakage is a problem with machines which have inner oil containing cavities, and moving devices which extend from these cavities through the walls of the frame into the surrounding environment. Gasket junctures also present problems with lubricant leakage to various degrees. 
     To solve such problems, the prior art contains gaskets of many different shapes, forms, materials, etc. The same is true of seal devices. The problems are compounded by moving devices which extend through the walls of the frame, since very often because of unique configurations, specifically designed seals or gaskets are required. This being reflected back in the cost of the final product. 
     Accordingly, there is a need for a means which will effectively retard the leakage of lubricant to the exterior of the device regardless of its source. 
     SUMMARY OF THE INVENTION 
     The invention hereunder consideration involves machines that have a frame and at least one generally sealed inner cavity from which lubricant leakage occurs. The invention being: the lowering of the atmospheric pressure within the inner cavity below that of the atmosphere by any suitable means, such as a vacuum pump, until air from the environment is drawn into the cavity through the passages from which the lubricant is leaking. In so doing, the inflowing air, replaces the lubricant at all leakage points, thus retarding the outward passage thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of a sewing machine incorporating the present invention; 
     FIG. 2 is a front view of a sewing machine partially broken away showing a pump means located within an inner cavity of the sewing machine; 
     FIG. 3 is a partial sectional view of the left portion of upper arm showing a device which passes from an inner lubricant containing cavity through the wall of the frame. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First referring to FIG. 1 wherein is shown a sewing machine of the type manufactured by Union Special Corporation, 400 North Franklin Street, Chicago, Ill. and identified as Style XF511H100MF catalog no. 142M First Edition. It is understood that this is simply one embodiment of the invention which is applicable in general to machines having lubricant or oil containing inner cavities which suffer from leaks. Such leaks can take the form of any passage or permation through, around, across, etc. seals, bushings, gasket material, etc. 
     As stated, FIG. 1 shows the frame or body portion 1 of a sewing machine means 2 which includes: an upper arm means 4, a needle means 6 defining a sewing area or zone, a hand wheel 8, a frame wall means 10, a lower arm means 12, an oil sump means 14 containing oil and an inner cavity means 16. A drive shaft pulley means 18 cooperates with a belt and a motor (not shown) to transfer driving force to the sewing machine. In general, the inner cavity or cavities is/are sealed against lubricant leakage into the environment surrounding the machine. Referring to FIG. 3, such leakage can take place through or across gasket juncture means 20 which includes a gasket means 22 sandwiched between the removably arranged cover means 24 of the hollow or open front section 26 of the sewing machine frame 2. As is known in the prior art, the interior of a sewing machine frame may have a single inner cavity or may include a plurality of inner cavities such as 28, 30 and 32 in FIG. 3. These open cavities such as 28, 30 and 32 can contain various amounts of lubricant and are sealed against leakage of lubricant via cover means which cooperate with the machine frame to sandwich a gasket means. However, retarding the leakage of lubricant through said gasket junctures and around lubricated device means disposed substantially proximate the sewing zone, such as the needle bar 34 and bushing 36 which extend from the machine interior through and beyond the machine frame into the surrounding environment is not so simple. Gasket material is known to be semipermeable and lubricant leakage passages are known to exist around bushings, bearings, seals, etc. All of which leakage problems are evidenced by the presence of lubricant in the environment surrounding the machine frame. The various means or mode whereby the lubricant finds its way to the surrounding environment is beyond the scope of this invention and thus will only be speculated upon. 
     What we have discovered is that if the atmospheric pressure within the machine interior is reduced sufficiently below that of the surrounding environment, air will be inwardly drawn to the machine&#39;s interior through the means, mode, passages, etc. through which the lubricant was prior therefrom leaking to produce an air seal. 
     Any type of means for reducing the atmospheric pressure may be employed such as a vacuum pump 38 or a venturi means (not shown) etc. The means for reducing atmospheric pressure may be located exterior to the inner cavity such as pump 38 in FIG. 1 and FIG. 2 or it may be located within such as in cavity 30 in FIG. 3. The pump means 40 located in cavity 30 is sealed from the nonvented inner cavity (here cavity 28) in which the atmospheric pressure is being lowered. The pump means 40 may be a vacuum pump or a venturi means. Any suitable means is sufficient such as seal means 42 which is intimately arranged about the shaft. The atmospheric pressure in inner cavity 28 however must be reduced to the degree such that air flows in through any lubricant leakage means in the gasket means 22, between the vertically reciprocating needle bar 34 and bushing 36 or seal 42 etc. The air flow can be controlled, by controlling the pump means 40, to effectively block the desired amount of lubricant leakage from the machine&#39;s interior to the exterior of the frame. The more the atmospheric pressure is reduced, the greater will be air flow through whatever lubricant leakage means which may exist. A vent means 48 for cavity 30 allows air accumulating in the cavity 30 to return to the surrounding environment. 
     Thus, the method for reducing leakage of lubricant from a generally sealed machine which has at least one lubricant containing cavity includes the steps of: reducing the atmospheric pressure inside of said lubricant containing cavity sufficiently below that of the surrounding environment by removing therefrom lubricant, lubricant and air or generally just air; and drawing or flowing air from the environment into said lubricant containing cavities through the passages, holes, spaces, means in general through which lubricant leakage occurred thereby avoiding lubricant from being deposited on a workpiece passing through the sewing zone of the machine. 
     We have thus provided a method and apparatus for retarding the leakage of lubricant from a machine which includes a frame having an open lubricant containing cavity, a cover means removably secured to said frame such that it generally seals the cavity and a means for reducing the atmospheric pressure within the cavity to a degree such that air from the surrounding environment flows into the cavity through whatever means lubricant leakage was occurring. 
     Thus it is apparent that there has been provided in accordance with the invention, a Method and Apparatus For Retarding Lubricant Leakage In A Sewing Machine that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.