Patent Abstract:
A light-weight vacuum pump has a multi-wiper member circular wiper member support and impeller which is eccentrically mounted within a pump housing. The multi wiper member circular support carries from about five to nine wiper members each mounted within a slot extending substantially the length of the support, with each wiper member being centrifically urged outwardly to wipingly engage an inner surface of a round or elliptical walled pump housing. Eccentric action enables the wiper members to be extended to create a large space between adjacent wiper members as an inlet is passed. As the wiper members pass by the inlet, the acentric cylindrical wall of the pump housing begins to compress the wiper members into the support, thereby reducing the space between adjacent wiper members in a compressive manner. The wiper member support further carries an added volume pocket between adjacent pairs of wiper members in order to (1) take in more air volume, and (2) create a less severe compression per inter wiper member volume compressed. This configuration can deliver high volumes of evacuated dump air and yet create significantly high vacuum at higher speeds of operation.

Full Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of high performance automotive equipment and more specifically to an automotive vacuum pump having significant volume elimination and pressure reduction capability and which is used to increase horsepower, and in which is overcome the lubrication problems caused from operating a continuous vacuum chamber. 
     BACKGROUND OF THE INVENTION 
     High performance combustion engines attempt to utilize every reasonable advantage in extracting more utilizable horsepower and torque from the engine so long as the compromise in power or weight to achieve that horsepower is not excessive. Techniques to increase horsepower, for example, include reducing the exhaust pressure drop by either eliminating the muffler or tuning the exhaust port so that the pulsating exit of the exhaust gasses do not work to build the pressure drop. Superchargers and turbo chargers are another method of increasing horsepower by increasing the pressure into the combustion chambers, to add more fuel per stroke, and to extract more power upon each ignitive explosion. 
     In internal combustion engines, the piston downstroke transfers power from the ignitive explosion. The pressure of the explosion acts against the piston rod to turn the crank shaft, but also acts against the atmospheric or higher pressure in the crank case. Atmospheric pressure is normally expected to exist in the crank case, but slightly higher pressures can and do exist because the wiping sealing between the piston rings and combustion chamber are not perfect. 
     Elimination of even the atmospheric pressure in the crank case would eliminate by at least 14.696 pounds per square inch, the force opposing the power stroke of the piston. In addition, it would assist the piston&#39;s travel toward the crank shaft during the intake stroke when combustion air and fuel are being drawn into the combustion chamber. Admittedly, the piston would be working to compress the combustion chamber during the compression stroke and working to expel the exhaust gasses on the exhaust stroke against the reverse pull of a vacuum, but the greater criticality in withdrawing maximum power during the brief power stroke, as well as the advantage in drawing in combustants, significantly overcomes any compensation in either of the other two strokes where the piston would act against a vacuum developed in the crank case. 
     A vacuum in the crankcase can add, on average about 15% to the horsepower rating of the engine, depending upon the level of vacuum attainable. However, because the engine is not a perfectly sealed environment, a vacuum in the crank case is not maintainable as a static, pre-set condition. A vacuum draws in gasses from around the piston rings, as well as through the crank shaft and other imperfectly sealed surfaces between the crank case and available gasses which would defeat a pre-set vacuum. 
     In addition, the use of a conventional vacuum pump to try to achieve high vacuum is unworkable for several reasons. First, most of the positive displacement high vacuum pumps cannot provide a sufficient level expelled volume to be of sufficient use in keeping up with the crank case pressure or volume requirements. Second, the typical piston vacuum pump consumes significant energy since it too has a piston which is withdrawn against atmospheric pressure, only to compressively eliminate only a small amount of waste air at high vacuum for each stroke. Thirdly, the size and weight of a conventional vacuum unit is also prohibitive. One of the contributing factors to weight is the need to provide both sealing and lubricative bearing support of the shaft of the vacuum pump. Where a vacuum is had on one side of a shaft, the vacuum tends to draw lubricant and surrounding air and moisture into the vacuum pump. Repeated lubrication only results in lubricant contaminating the internals of the pump. Repeated lubrication in the high performance automotive environment is simply not a reasonable option. 
     What is therefore needed is a very light weight source of vacuum, which can move relatively high volumes of air from an evacuated crank shaft, but without loss of efficiency. The needed source of vacuum should also be relatively free of lubrication troubles, especially the problem of sucking the lubricant into the pump to leave the moving parts un-lubricated. 
     SUMMARY OF THE INVENTION 
     The light-weight vacuum pump of the present invention includes a multi-wiper member circular wiper member support and impeller which is eccentrically mounted within a pump housing, preferably by displacement of the impeller along a line at right angles to the flow of air in order to make the vacuum pump bi-directional, such that it can be mounted on either side of an engine by simply turning the pump about a line extending between the inlet and the outlet. The multi wiper member circular support carries from about five wiper members to about nine wiper members each mounted within a slot extending substantially the length of the support, with each wiper member being centrifically urged outwardly to wipingly engage an inner cylindrical surface of a pump housing. The acentric mounting of the circular support enables the wiper members to be extended to create a large space between adjacent wiper members as the inlet is passed. In the alternative, the inner cylindrical surface can be modified to be an ellipse. As the wiper members pass by the inlet, the acentric cylindrical wall of the pump housing begins to compress the wiper members into the support, thereby reducing the space between adjacent wiper members in a compressive manner. The inner support further carries an added volume pocket between adjacent pairs of wiper members in order to (1) take in more air volume, and (2) create a less severe compression per inter wiper member volume compressed. The added volume pocket eases the energy required per volume of compression by providing a space to limit the rise in pressure. This configuration can deliver high volumes of evacuated dump air and yet create significantly high vacuum at higher speeds of operation. The support rotates on a shaft deriving mechanical energy by drive belt from the engine. The support and shaft are isolated by use of a ball bearing, “U” cross sectionally shaped seal outwardly disposed, followed by a main shaft seal. A shallow pocket having a depth of between five and fifty thousandths of an inch, and having a width of about one centimeter, formed on the inside of the housing about the main shaft seal to reduce frictional resistance to centrifical movement of the vanes, as well as to reduce the frictional area of the vanes pressure against the vane slots in the main body in which they reside. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, its configuration, and its construction will be further depicted in the following detailed description, taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is an exploded view of the vacuum pump of the invention illustrating the components, bearing and seals and drive wheel; 
     FIG. 2 is a perspective view of the vacuum pump of FIG. 1 in assembled view; 
     FIG. 3 is a rear view of the support cover seen in FIG.  1  and illustrating the flat surface which lies adjacent the main body which supports the wiper members; 
     FIG. 4 is a plan view of the main body within the pump housing and illustrating the radially outward movement of the wipers against the cylindrical surface of the inside of the pump housing; 
     FIG. 5 is sectional exploded view illustrating the component parts seen in FIGS. 1-4; 
     FIG. 6 is a sectional view of the assembled vacuum pump seen in FIG.  5  and illustrating the close fitting relationship of the component parts thereof; 
     FIG. 7 is a plan view of the main body of a pump having nine wipers and illustrating the radially outward movement of the wipers against the cylindrical surface of the inside of the pump housing; 
     FIG. 8 is a plan view of the main body of a pump having six wipers and illustrating the radially outward movement of the wipers against the cylindrical surface of the inside of the pump housing; and 
     FIG. 9 is a plan view of an end cover without a support portion. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention will be best described with reference to FIG. 1 which illustrates an exploded perspective view of a vacuum pump  11 . At the upper right of the FIG. 1 is an integrated mounting bracket and end plate drive support  13 , hereinafter referred to as a support cover. A non supporting cover will also be illustrated. The support cover contains a bore  15  for mounting on a vehicle, and a radius slot  17  for use in conjunction with the bore  15  for using bore  15  to pivot around a bolt (not shown) and to lock the plate drive support  13  in a position to derive adequate mechanical drive force. 
     To the right of the plate drive support  13  is a drive wheel  21 . The drive wheel  21  shown has rectangular ribs  23  for a positive grip on a drive belt, and includes a hexagonal screw  25  for positive registration within a first slot  27  on a drive shaft  29 . An main shaft seal  31  is located adjacent the drive wheel  21 , and a closely fitting roller bearing  33  is located next to the main shaft seal  31 . Adjacent the roller bearing  33 , a polymer sealing ring  35  fits within a chamfer  37  adjacent a closely fitting shaft aperture  39 . 
     Polymer sealing ring  35  has a continuous circular shape, each portion of the circle having a cross sectional “U” shape with the shape of the “U” disposed toward the drive wheel  21 . Force developed on the vacuum side of the support cover  13  pulls the polymer sealing ring  35  inward, but the inner wall of the ring simply seals tighter against the shaft  29 . One polymer sealing ring  35  includes an outer wall and bottom of the “U” shape made of relatively hardened material, even where the inner wall of polymer sealing ring  35  adjacent the shaft  29  is of relatively soft material. The chamfer  37  helps stabilize the polymer sealing ring and provide sufficient support so that the inner wall of the polymer sealing ring  35  will maintain its shape and area coverage against the shaft  29 . 
     In the line of connection, the shaft  29  is shown with a second, longer slot  39  on which to register a support  41 . Support  41  includes a central bore  43 . The support has a main body  45  having a series of radially disposed slots  47  each supporting a wiper member  49 . Within each of the slots  47 , which can be seen to the extent that each slot&#39;s  47  a wiper member  49  is preferably urged radially outwardly by centrifical force from the rotational motion of the main body  45 , no spring member may be necessary. In the case where centrifical force is used, the mass of the wiper members  49  will have to be sufficient to extend the wiper members  49  and apply enough wiping pressure to perform the pumping action and the contact of the side edges of the wiper members  49  will be sufficiently minimized to enable rapid deployment. The support  41  is mounted to one side of center within a cylindrical surface  51  within a pump housing  53 . Cylindrical surface  51  lies adjacent to a rear smooth wall  52 . An elliptical surface can be used in place of a cylindrical surface, particularly where the characteristics of the vacuum pump II are to be modified for particular characteristics of different engines with which it is used. In the case of a cylindrical surface with a completely circular side wall, as is shown in FIG. 1, an off center mounting of the main body  45  causes each of the wiper members  49  to expand to form a larger opening between adjacent wiper members  49  adjacent an opening  55 , (assuming a that the movement of the main body  45  past the opening is such that the spaces between the wiper members is expanding), and to retract as the wiper members pass by a closer section of the cylindrical surface  51 . With an elliptical shaped surface  51 , the main body  45  would still be relatively cylindrical, having a circular radial sweep, and its mounting would not be as precisely describable as position relative to a radial center, but the position would likely be on a chord between the two foci of the ellipse. 
     As the support  41  turns, each of the wiper members moves into and out of its slot  47  as the end edges of the wiper members  49  follow the cylindrical surface  51 . In addition, in the main body  45 , between adjacent the radially disposed slots  47  are a series of capacity pockets  57 . These capacity pockets  57  reduce the compression ratio and increase the volume flow rate. This provides a flow rate and pressure which is both more appropriate to the amount of volume to be removed from an internal combustion engine, as well as to form a vacuum pump  11  which is more responsive to speed. 
     For a given vacuum within an internal combustion engine, the volume of gasses which need to be evacuated is proportional to the speed of the engine. The vacuum pump  11  of the invention operates faster as the engine speed increases since the drive wheel  21  turns in response to engine speed. 
     At the rear of the pump housing a second polymer sealing ring  61  is seen, but its cross sectional cup shaped opening is not seen as it faces away from the pump housing  53 . Also seen is a second closely fitting roller bearing  63 . An end cap  65  contains a series of apertures  67  for attachment to the pump housing  53 . The pump housing  51  has a lower opening  69 . Both the lower opening  69  and the upper opening  55  have internal threads  71  for attachment to flow conduit or tubing for both connection to an internal combustion engine and for providing a dump away from the vacuum pump  11  where desired. By offsetting the main body  45  along a line generally between the upper opening  55  and the lower opening  69 , the vacuum pump  11  becomes reversible such that it can be mounted on either side of the engine and still perform its function. 
     Also seen on the pump housing  53  are a series of threaded bores  73  which align with a series of open bores  75  to affix the support cover  13  to the pump housing  53 . In addition, both the support cover  13  and the pump housing  53  contain a series of aligning pin registry bores  77  which are utilizable with a series of registry pins  79  to make certain that the support cover  13  to the pump housing  53  are aligned. An outwardly extending boss  80  is also seen which lends further stability to the support cover  13 . 
     Referring to FIG. 2, the assembled vacuum pump is shown. The hexagonal screw  25  is engaging the first slot  27  to register the drive wheel  21 . In the configuration of FIG. 2, the vacuum pump  11  need only be mounted via the bore  15  and radius slot  17 , and engaged within a loop of a drive belt to be operational. Depending on the direction of turn, either the opening  55  or the opening  69  is connected in communication with the crank case of an internal combustion engine. Running the engine lowers the internal pressure and in increases the efficiency. It has been found that the vacuum pump  11  yields from 12-15% efficiency increase, depending upon the internal combustion engine to which the vacuum pump  11  is operably attached. A vacuum of twenty six inches of water can be maintained at a static, non flowing condition while vacuum pump  11  consumes four horsepower. When engaged with an internal combustion engine, and as flow ensues from the static vacuum condition, a typical racing engine experiences an additional net 31 horsepower (after subtraction of the operating horsepower) when a vacuum of nineteen inches of water is maintained, and net 63 horsepower when a vacuum of twenty two inches is maintained. 
     Referring to FIG. 3, a view of the rear side of the support cover  13  illustrates a circular flat area  81  into which the shaft aperture  39  is formed. Also seen is a shallow clearance pocket  83  having a depth of between five and fifty thousandths of an inch, and having a width of about one centimeter, formed on the inside of the housing about the main shaft seal to reduce frictional resistance to centrifical movement of the vanes or wiper members  49 , as well as to reduce the frictional area of the wiper members  49  against the vane slots  47  in the main body  45  in which they reside. Referring to FIG. 4, a plan view of the pump housing  53  is seen with the support  41  in rotational position. As can be seen, the wiper members  49  extend from the main body  45  and are urged out by each one by its own centrifical force when the main body  45  is spinning. Since the sides of the wiper members  49  and the sides of the main body are flat and close fitting, no further sealing is needed, and the shallow clearance pocket  83  which provides a reduction in friction does not provide a break in the vacuum pressure or vane  49  flowing pressure because a more severe seal is had between the circular flat area  81  and both of the flat end wall of the main body  45  and side edges of the wiper members  49 . The displacement of the shaft  29  from center of the cylindrical surface  51  is to one side of a line extending between the opening  55  and  69 . As such, the direction of rotation will determine whether opening  55  is intake or exhaust, with opening  69  being exhaust or intake, respectively. Where the displacement of the shaft  29  from center of the cylindrical surface  51  is to one side of a line extending between the opening  55  and  69 , and brought toward one of the openings  55  and  69 , the compression and evacuation efficiency will change and forward and reverse completely equivalent action will not be present. Where the shaft  29  is brought closer to opening,  69  for example, the compression ratio for pumping is increased, and for evacuating is decreased. If the other opening  55  is used, the evacuation ratio is increased, but the pumping ratio is decreased, again assuming shaft  29  is brought closer to opening  69 . In any event, the needs of a specific  5  engine, in terms of a composite profile of its exhaust volume and achievable minimum pressure can be more closely approached or met by selecting the position of the shaft  29  with respect to the cylindrical surface  51  in terms of how far off center it is, as well as how close it is to one of the openings  55  or  69 . 
     In addition, the pump housing  53  is shown with the openings  55  and  69  oppositely oriented, in other words 180° apart with respect to the cylindrical center of the cylindrical surface  51 . This need not necessarily be the case. With regard to the cylindrical center of the cylindrical surface  51 , both the shape of the openings and their center positions can be changed or differed with respect to each other. In addition, other changes to the shape and volume of the pockets  57  can also be made. Changes to the volume and shape of the pockets  57  can be done in conjunction with other changes to the vacuum pump  11  previously mentioned. Thus for different applications, different physical configurations of the vacuum pump  11  can be had to maximize utility for a given application. 
     FIG. 5 is a sectional exploded view illustrating the component parts seen in FIGS. 1-4. At the left of the FIG. 5, bolts  91  are used to secure a sealing end cap  65  to the pump housing  53 . The end cap  65 , as can be seen, provides a covering and further sealing to help further block air and dirt from being drawn into the housing  53 , and to help buttress the end of the shaft  29  so that a limit is had should a force act to move the shaft toward end cap  65 . It is expected that on normal operation of the vacuum pump  11  that no friction between the end of the shaft  29  and inside of the end cap  65  will be had. 
     Features not seen in the other Figures are now seen in FIG.  5 . An aperture  93  closely surrounds and admits the shaft  29 . A small chamfer  95  facilitates the fit of second polymer sealing ring  61 . A large groove  97  facilitates the fit of the second closely fitting roller bearing  63 . To the right of the main body  45 , the support cover  13  is shown with a large circular depression  101 , which is adjacent to the chamfer  37 . To the right is shown the polymer sealing ring  35  which fits into the chamfer  37 , as well as the closely fitting roller bearing  33  which fits over the polymer sealing ring  35 , and the main shaft seal  31  which fits adjacent the closely fitting roller bearing  33 . Other features of FIG. 5 were generally seen in the other Figures, but FIG. 5 better illustrates how the bearing and sealing structures fit closely together. FIG. 6 illustrates a sectional view of the assembled pump  11  from a same perspective as that of FIG. 5, but with the interfitting of the related structures clearly shown. 
     FIG. 7 is a plan view of the main body of a pump  11  having nine wipers  49  and illustrating the radially outward movement of the wipers against the cylindrical surface of the inside of the pump housing  53 . 
     FIG. 8 is a plan view of the main body of a pump  113  having six wipers and illustrating the radially outward movement of the wipers against the cylindrical surface of the inside of the pump housing  53 . 
     Referring to FIG. 9, a perspective view of a cover  15  having all of the features of the cover support  13  of FIG. 1, but which does not include material beyond that which is needed to engage and cover the pump housing  53 , is shown. The use of the cover  115  will probably be accompanied by other attachement and support structure for the housing  53 , such as by bolting or the use of a bracket. Such a bracket may engaged the fittings adjacent the upper and lower openings  55  and  69 . 
     The present invention may be used in any setting in which a volume and pressure matched vacuum pump is to be utilized, and especially where the amount of expelled gasses and magnitude of vacuum is to be matched with rotational speed. Multiple variations on this invention are certainly possible, since variations can occur with any one or any combination of the components of several of the integrated structures, over various engine types, various magnitudes of air volume to be moved, and various magnitudes of vacuum to be achieved. 
     Modifications to all parts of the invention may occur to those skilled in the art, and those modifications may be produced without departing from the spirit and scope of the invention. Therefore, included within the patent warranted hereon are all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art.

Technology Classification (CPC): 5