Patent Publication Number: US-9885358-B2

Title: Three stage scroll vacuum pump

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This non-provisional patent application is a continuation of the application having U.S. Ser. No. 13/987,486, which was filed on Jul. 30, 2013, which non-provisional patent application is a divisional of U.S. Ser. No. 13/066,261, now Publication No. US 2011-0256007 A1, which claims priority to the provisional patent application having Ser. No. 61/342,690, which was filed on Apr. 16, 2010, which claims priority to the provisional application having Ser. No. 61/336,035, which filed on Jan. 16, 2010, which claims priority to the non-provisional patent application having Ser. No. 11/703,585, which was filed on Feb. 6, 2007, now U.S. Pat. No. 7,942,655, which claims priority to the provisional patent application having Ser. No. 60/773,274, which was filed on Feb. 14, 2006, which was filed during the pendency of PCT application Serial No. PCT/US01/50377, which was filed on Dec. 31, 2001, designating the U.S. and during the pendency of PCT application Serial No. PCT/US01/43523, which was filed on Nov. 16, 2001, designating the U.S., and which claimed priority to the non-provisional application having Ser. No. 09/751,057, which was filed on Jan. 2, 2001, now U.S. Pat. No. 6,511,308, and which claimed priority to the continuation-in-part application having Ser. No. 09/715,726 which was filed on Nov. 20, 2000, now U.S. Pat. No. 6,439,864. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     The three stage vacuum pump, and alternatively expander, relate generally to devices that alter or reduce the pressure of gases within a container, typically to very low vacuums or alternatively produce power as a gas expands. More specifically, these devices refer to multiple stages of scrolls that greatly increase the vacuums obtained during usage. 
     A unique aspect of the present disclosure is a three stage pump using various arrangements of scrolls that achieves vacuums of approximately 2 mt, that is, two millitorr (mTorr). These high vacuums apply to compact equipment such as portable mass spectrometers. 
     Scroll devices have been used as compressors and vacuum pumps for many years. In general, they have been limited to a single stage of compression due to the complexity of two or more stages. In a single stage, a spiral involute or scroll upon a rotating plate orbits within a fixed spiral or scroll upon a stationery plate. A motor shaft turns a shaft that orbits a scroll eccentrically within a fixed scroll. The eccentric orbit forces a gas through and out of the fixed scroll thus creating a vacuum in a container in communication with the fixed scroll. An expander operates with the same principle only turning the scrolls in reverse. When referring to compressors, it is understood that a vacuum pump can be substituted for compressor and that an expander can be an alternate usage when the scrolls operate in reverse from an expanding gas. 
     Often oil is used during manufacture and operation of compressors. Oil free or oil less scroll type compressors and vacuum pumps have difficult and expensive manufacturing, due to the high precision of the scroll in each compressor and pump. For oil lubricated equipment, swing links often minimize the leakage from gaps in the scrolls by allowing the scrolls to contact the plate of the scroll. Such links cannot be used in an oil free piece of equipment because of the friction and wear upon the scrolls. If the fixed and orbiting scrolls in oil free equipment lack precision, leakage will occur and the equipment performance will decline as vacuums take longer to induce or do not arise at all. 
     Prior art designs have previously improved vacuum pumps, particularly the tips of the scrolls. In the preceding work of this inventor, U.S. Pat. No. 6,511,308, a sealant is applied to the two stage scrolls during manufacturing. The pump with the sealant upon the scrolls is then operated which distributes the sealant between the scrolls. The pump is then disassembled to let the sealant cure. After curing the sealant, the pump is reassembled for use. During use, this patented pump only achieves a vacuum on the order of 100 mt. 
     U.S. Pat. No. 3,802,809, which issued to Vulliez, disclosed a pump having a scroll orbiting within a fixed scroll. Beneath the fixed disk, a bellows guides the gases evacuated from a container. The bellows spans between the involute and the housing, nearly the height of the pump. This pump and many others are cooled by ambient air in the vicinity of the pump. 
     In some applications, scroll type vacuum pumps have notoriety for achieving high vacuums. A few large scroll vacuum pumps can achieve vacuums as high as 50 mt. However, industry, science, and research still demand compact vacuum pumps that can achieve higher vacuums. 
     The present disclosure overcomes the limitations of the prior art where a need exists for higher vacuums in equipment of compact form. That is, the art of the present disclosure, a three stage scroll vacuum pump utilizes a magnetic coupling for power transfer and fins upon the orbiting scroll and inside the housing for heat transfer, both without leakage of the working fluid. 
     SUMMARY OF THE DISCLOSURE 
     Accordingly, the present disclosure improves a three stage vacuum pump and other related equipment with three stages of fixed scrolls and orbiting scrolls and each stage operates simultaneously. Motor drives the second orbiting scrolls within the third fixed scroll as the third stage upon three equally spaced idlers. One idler then transmits rotation and torque into the second stage, that is, the second orbiting scroll. The second orbiting scroll has involutes upon both surfaces. The second orbiting scroll engages the second fixed scroll. In the first stage, the second orbiting scroll engages a first fixed scroll outwardly from the center. The first fixed scroll of the first stage has fins upon its back surface that extend outwardly into the atmosphere for heat transfer as the pump is strictly air cooled. The present disclosure also includes a fan outside the housing to accelerate heat transfer. The scrolls receive torque and rotation directly from a motor or alternatively from a motor and a magnetic coupling or magnetic face seal so that the atmosphere does not infiltrate the housing of the three stages of scrolls. The present disclosure also has an enclosed inlet plenum to prevent mixture or infiltration of the working fluid into the heated fluid inside the housing. 
     Therefore, the present disclosure provides a new and improved three stage vacuum from the machine class of compressors, vacuum pumps, and expanders for gases. 
     The present disclosure provides an enclosed housing for the orbiting and fixed scrolls. 
     The present disclosure also provides air cooling of the vacuum pump thus increasing the efficiency of the vacuum pump. 
     The present disclosure provides aligned fins on the back of the first fixed scroll, on the back of the second fixed scroll, and on the back of the third fixed scroll along with the back of the housing to transfer heat from the orbiting scrolls outwardly to the ambient atmosphere. 
     The present disclosure further provides a fan to move ambient air over the pump to accelerate heat transfer. 
     The present disclosure provides fins upon the scrolls that pump working fluid within the housing to increase heat transfer. 
     The present disclosure also provides a magnetic coupling or magnetic face seal that separates the working fluid from the ambient atmosphere. 
     Also, the present disclosure provides an enclosed inlet plenum that prevents mixing or infiltration of the working fluid into the heated fluid inside the housing. 
     These and other advantages may become more apparent to those skilled in the art upon review of the disclosure as described herein, and upon undertaking a study of the description of its preferred embodiment, when viewed in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In referring to the drawings, 
         FIG. 1  shows a sectional view through both scrolls of a scroll compressor using an alternate embodiment of the present three stage scroll vacuum pump; 
         FIG. 2  shows a sectional view through a scroll compressor on a plane through the axis of rotation of the scrolls; 
         FIG. 3  describes a sectional view through a scroll compressor having liquid cooling; 
         FIG. 4  describes a planar view of the cooling plate and its connection to the bellows of the alternate embodiment of the three stage scroll vacuum pump; 
         FIG. 5  illustrates a sectional view through the bellows and fittings for liquid cooling of a scroll compressor of the alternate embodiment of the three stage scroll vacuum pump; 
         FIG. 6  shows a sectional view through one tip of a scroll having an improved seal of the alternate embodiment of the three stage scroll vacuum pump; 
         FIG. 7  shows a sectional view lengthwise through the housing of the present three stage scroll vacuum pump; 
         FIG. 8  provides a sectional view of the interior of the housing towards the motor; 
         FIG. 9  provides a section view of the back surface of the orbiting scroll where the fins on this back surface engage the fins of the housing as in  FIG. 8 ; 
         FIG. 10  illustrates a sectional view of the front surface of the orbiting scroll generally opposite that of  FIG. 9  and the orbiting scroll has an enclosed plenum there through; 
         FIG. 11  describes an end view of the housing adjacent to the motor; 
         FIG. 12  describes an end view of the housing away from the motor, generally opposite that of  FIG. 11 ; 
         FIG. 13  shows a detailed sectional view of the magnetic coupling between the motor and the orbiting scroll within the housing; 
         FIG. 14  shows a sectional view lengthwise through the three stage vacuum pump; 
         FIG. 15  provides an end view of the three stage vacuum pump; 
         FIG. 16  describes a side view of the three stage vacuum pump; 
         FIG. 17  illustrates a sectional view lengthwise of the three stage vacuum pump utilizing a magnetic coupling; and 
         FIG. 18  provides a detailed sectional view of the magnetic coupling between the third stage and the second stage of this pump. 
     
    
    
     The same reference numerals refer to the same parts throughout the various figures. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An alternate embodiment of the three stage scroll vacuum pump which overcomes the prior art limitations by modifying scroll compressors and other pumps with bellows, liquid cooling using bellows, and tip seals is discussed as follows. Turning to  FIG. 1 , a scroll compressor  1  appears in a sectional view through the scrolls. The scroll compressor  1  has a case  2  to contain the compressor  1  and scrolls. Within the case  2 , the alternate embodiment has at least three equally spaced idlers  5   a . The idlers  5   a  rotate eccentrically in cooperation with the scrolls as the scrolls compress or evacuate a gas from a container, not shown. The scrolls are located within the idlers and inter mesh. The scrolls have a fixed scroll  3  of a generally spiral shape fixed to the compressor  1  and an orbiting scroll  4  also of a generally spiral shape. The orbiting scroll  4  fits within the fixed scroll  3  and as the orbiting scroll  4  turns, gas is drawn into the scrolls and evacuated from the compressor  1 . A bellows  8  surrounds and seals the scrolls  3  and  4  while remaining flexible. The bellows  8  has two mutually parallel flanges  9 , each flange  9  joined to a scroll. The bellows  8  has a hollow round cylindrical shape that extends around the circumference of the scrolls  3  and  4 . The bellows  8  can be made of metal, plastic, polymer, or an elastomer among other things. Electro forming, hydro forming, welding, and casting among other mean form and shape the bellows  8 . 
     Turning the compressor  1  upon its side,  FIG. 2  shows the workings of the compressor  1  in conjunction with the bellows  8 . A motor  7  turns an axial shaft which connects with an eccentric shaft  5  that passes through a bearing. The eccentric shaft  5  connects with the orbiting scroll  4 . The fixed scroll  3  is opposite the orbiting scroll  4  with an axis coaxial to the eccentric shaft  5 . Operation of the motor  7  orbits the orbiting scroll  4  eccentrically which rotates the idlers  5   a  and their attached counterweights. The idlers  5   a  have an offset shaft to guide the orbiting motion of the orbiting scroll  4 . The idlers  5   a  and counterweights permit eccentric rotation of the orbiting scroll  4  while preventing destruction of the scrolls  3  and  4  and the compressors  1  due to centrifugal forces. 
     Outwards of the scrolls  3  and  4  upon the perimeter, annular well forms within the compressor  1 . The well generally extends around the circumference of the scrolls  3  and  4  and at least the height of the scrolls  3  and  4  outwards from the center line of the scrolls  3  and  4 . Within the annular well, the bellows  8  seals the scrolls  3  and  4 . The bellows  8  as before has a generally hollow cylindrical shape with a round flange  9  upon each end. Here in section, the bellows  8  appears on edge as two equally spaced bands. The bellows  8  has a slight inclination to accommodate the eccentric shaft  5 . Flanges  9  appear upon each end of the bands and connect the bellows  8  by bolting, such as by bolts  9   a , or other means to the scrolls  3  and  4 . The flanges  9  have an annular shape with an inner diameter similar to the inner diameter of the bellows  8 . In the preferred embodiment, the flanges  9  bolt to the scrolls  3  and  4 . In alternate embodiments, the flanges  9  join the scrolls  3  and  4  by welding or brazing. To fully seal the scrolls, the flanges  9  have a sealing ring  10 . Here in section, the sealing ring  10  appears as four portions located at the ends of each band. The sealing rings  10  take up any gap between the flanges  9  and the scrolls  3  and  4  thus sealing the bellows  8 . O-rings or metal seals may serve as the sealing rings  10 . 
     Liquid cooling of the compressor  1  becomes possible for selected equipment and applications. Liquid cooling proves useful for compressors  1  in confined locations with limited access to air, such as boats or spacecraft.  FIG. 3  shows the beginning of the liquid cooled compressor  1 . As before, a motor  7  turns a shaft  5  eccentrically connected to the scrolls  3  and  4 . This alternate embodiment joins an orbiting cooling plate  18  to the orbiting scroll  4  and a fixed cooling plate  11  to the fixed scroll  3 . The cooling plates  11  and  18  join outwards from the scrolls  3  and  4  so evacuation of gases continues unimpeded. The cooling plates  11  and  18  have grooves  13  and  20 , respectively, upon their surfaces that form passages when joined against the scrolls  3  and  4 . Liquid coolant then circulates through the passages and removes built up heat. 
     The grooves  13  and  20  form a generally annular shape as shown in the sectional view of  FIG. 4 . The groove  13  shown is in the fixed cooling plate  11  however the orbiting plate  18  has the similar groove  20 . The annular shape of the groove  13  extends partially around the circumference and partially across the diameter of the fixed cooling plate  11 . A wall  16  upon the fixed cooling plate  11  blocks the groove  13  from completely encircling the compressor  1 . Proximate to the wall  16 , the groove  13  has an aperture  14  in communication with an inlet for liquid coolant and on the other side of the wall  16 , an aperture  15  in communication with an outlet to return the coolant for heat exchanging. O-rings  10  seal the inner and outer circumferences of the groove  13  and the apertures  14 . 
     Referencing the inlet and the outlet of  FIG. 4 ,  FIG. 5  shows a pair of bellows  22  and  23  for conducting liquid coolant into and out of the cooling plates  11  and  18  for cooling the compressor  1  during operation. The cooling liquid is pumped into the inlet upon the fixed cooling plate  11 , enters the aperture  14   a , and then travels through the passage  13  to cool the fixed cooling plate  11 . A portion of the cooling liquid travels through the first bellows  22  into the inlet aperture  14   a  upon the orbiting cooling plate  18 . The portion of the cooling liquid then enters the passage  20  to cool the orbiting cooling plate  18 . The cooling liquid portion then exits the outlet aperture  15   a  into the second bellows  23 . The second bellows  23  also collects cooling liquid from the outlet aperture  14   a  of the fixed cooling plate  11 . The second bellows  23  returns the generally heated cooling liquid from both cooling plates  11  and  13  to the outlet for communication to a heat exchanger. The bellows  22  and  23  have a hollow cylindrical shape with a flange upon each end sealed to the respective scrolls  3  and  4  with sealing rings  10 . The flanges are connected to the bellows  22  and  23  by bolting preferably by bolts  9   a  or alternatively by brazing or welding. 
     Upon the fixed scroll  3 , the first bellows  22  and the second bellows  23  join to a first end plate  17 . The first end plate  17  has a generally rectangular shape incorporated into the fixed scroll  3  and an upper surface and an opposite lower surface. The first end plate  17  bolts to the fixed scroll  3  in the preferred embodiment with the upper surface towards the orbiting scroll  4 . Here the bolts  9   a  are located upon a line through the centers of the first bellows  22  and the second bellows  23 . The first bellows  22  and the second bellows  23  are joined to the upper surface of the first end plate  17 . Upon the lower surface, O-rings  10  seal fittings for the inlet and outlet of liquid coolant for the compressor  1 . The O-rings  10  and fittings have a generally hollow round shape to ease connection of lines carrying the liquid coolant to and from the compressor  1 . 
     Then upon the orbiting scroll  4 , the first bellows  22  and the second bellows  23  join a second end plate  21 . The second end plate  21  is fastened into the orbiting cooling plate  18 , generally perpendicular to the first end plate  17 . The second end plate  21  bolts to the orbiting cooling plate  18  with the bolts  9   a  upon the lateral axis of the second end plate  21 , generally between the first bellows  22  and the second bellows  23 . O-rings  10  seal the first bellows  22  and the second bellows  23  to the second end plate  21 . 
     Turning now to  FIG. 6 , the alternate embodiment 1 is shown to have an exposed tip  24  of the fixed scroll  3  and the orbiting scroll  4 . Each scroll joins perpendicular to a plate. Opposite the plate, each scroll has the exposed tip  24  in a general spiral pattern. The tip  24  then has a groove  25  open away from the base. The groove  25  extends for the length of the scroll. A plurality of holes  26  is spaced along the length of the spiral. The diameter of each whole  26  is approximately the width of the groove  25 . Into each whole  26  a spring  27  upon a plunger  28  is positioned, where the spring  27  biases against the plunger  28  outwardly. The plunger  28  has a diameter and shape slightly less than the whole  26 . Upon the plunger  28  opposite the spring  27  and towards the tip  24  itself, a seal  29  abuts the opposing scroll. The seal  29  has a complementary shape to the whole  26 . In an alternate embodiment, the seal  29  has a secondary O ring seal. The secondary O ring  10  extends in a groove  30  around the circumference of the seal  29 . The spring  27  and the secondary O ring  10  prevent leakage between the scrolls  3  and  4  as the seals  29  wear during use. 
     The modifications of this alternate embodiment also include a method of sealing the scrolls  3  and  4  of the compressor  1 . To attain high vacuums and maximum efficiency, imperfections and deviations in the scrolls  3  and  4  must be sealed. Previously, epoxy was applied to the surfaces of the scrolls  3  and  4 , and the compressor  1  was assembled and operated for a time, then the scrolls  3  and  4  were disassembled and the tip seal grooves  25  cleaned, and then the epoxied scrolls  3  and  4  were reassembled into the compressor  1 . The alternate embodiment applies a mold release or other material upon the tips  24  of the scrolls  3  and  4  for filling the tip seal groove  25 , assembles the scrolls  3  and  4  together, injects epoxy into the scrolls  3  and  4 , and then operates the compressor  1  for a time to disperse the epoxy. The mold release inhibits the adhesion and accumulation of epoxy upon the tips  24  thus reducing the need to disassemble, to clean, and then to reassemble the compressor  1 . In the alternate embodiment, the epoxy occupies any gaps between the adjacent scroll&#39;s plates. The method of the alternate embodiment may eliminate the need for a tip seal  29  as previously described. In the preferred embodiment of this method, the mold release is a lubricating fluid. In an alternate embodiment, this method uses a mold release selected from elastomers, gels, greases, low hardness plastics, and pliable sealants. This method also applies to scroll compressors, vacuum pumps, and expanders alike. 
     Now  FIG. 7  shows a scroll type fluid displacement device that compresses or expands gases other than air. This device can operate as hydrogen recirculation pumps used in fuel cells, natural gas compressors used in micro-turbines, tritium vacuum pumps, Rankin cycle expanders, and the like. These applications require a completely enclosed housing so that the fluid undergoing compression or expansion does not leak from the housing into the nearby atmosphere or that the nearby atmosphere does not leak through the housing into the fluid undergoing compression or expansion. The fluid undergoing compression or expansion for application outside the pump is called the working fluid. The housing includes cooling fluid contained within the housing. The working fluid and the cooling fluid are the same material in case of leakage within the housing. When compressing or expanding these working fluids, heat arises in the various components of the present pump. The present pump though transfers heat from its fixed scroll and its orbiting scroll to the nearby atmosphere without leakage into the housing. Movement of the scrolls calls for transmission of power to the components of the pump also without leakage of the fluid undergoing compression or expansion. 
       FIG. 7  shows a cross section of the scroll device  30   a  where a fixed scroll  31  is bolted to a housing  32 . An O-ring  33  is positioned around the outside of the fixed scroll  31  and the housing  32  to seal the working fluid within the housing. The housing  32  and the fixed scroll  31  and an orbiting scroll  35  inside are coupled to a motor  34  here shown adjacent to the housing  32 . The fixed scroll  31  and the orbiting scroll  35  constitute the basic compressing, or alternatively expanding elements. An eccentric shaft  36  drives the orbiting scroll  35  during usage. Additionally, the eccentric shaft  36  has a magnetic coupling  37 , or alternatively a shaft seal, for transmitting the torque from the motor  34  into the orbiting scroll  35  for appropriate rotation without leakage of the working fluid to the atmosphere. Generally, the motor  34  supplies rotation to the magnetic coupling  37  which then imparts rotation and torque to the orbiting scroll  35  for usage as a compressor or vacuum pump while a generator supplies rotation to the orbiting scroll  35  when the device  30   a  is used as an expander. The fixed scroll  31 , the orbiting scroll  35 , and the housing  32  each have fins thereon, as later shown and described, for transferring heat primarily from the fixed scroll  31  and orbiting scroll  35  to the housing  32  for evacuation by conduction or a fan  38  integrated into the housing  32 . 
       FIG. 8  shows a sectional view of the interior of the housing  32  where the housing  32  has internal fins  39  and external fins  40 . The housing  32  has a flat bottom  32   a , two mutually parallel and spaced apart lower sides  32   b , two inwardly canted middle sides  32   c , two mutually parallel and spaced apart upper sides  32   d , and an open top  32   e  generally spanning between the upper sides  32   d  and mutually parallel to and spaced apart from the bottom  32   a . Upon each upper side  32   d , the housing  32  has a tapped and threaded fitting  32   f  for receiving bolted devices, not shown. The internal fins  39  have a generally spiral arrangement however, the internal fins  39  may have alternate shapes of cylindrical or flat plate. The internal fins  39  extend from near the perimeter of the housing  32  inwardly towards an opening  37   a  for the magnetic coupling  37  ( FIG. 7 ). The internal fins  39  have a generally arcuate shape where the end of the fin  39  proximate the opening  37   a  is generally ahead of the opposite end of the fin  39  proximate the housing  32 . This arcuate shape forms a generally clockwise spiral. The internal fins  39  are generally narrow in cross section and have a length of at least five times the cross section. The internal fins  39  have a regular spacing between adjacent fins  39  so that no internal fins  39  intersect each other and the internal fins  39  curve towards an imaginary center point at the center of the opening  37   a  for the magnetic coupling  37 . 
     The housing  32  has a generally gambrel like shape with the flat bottom  32   a , lower side&#39;s  32   b  perpendicular to the bottom  32   a , and inwardly canted middle sides  32   c . The middle sides  32   c  continue upwardly within the upper sides  32   d  and have a section at a second cant  32   g  flatter than the remainder of the middle sides  32   c . The second cants  32   g  of the middle sides  32   c  join upon the center line of the housing  32  above an idler  5 A. Proximate one side, shown as the right in this figure, the middle side  32   c  extends inwardly and perpendicular to the upper side  32   d  as at  32   h  and there the second cant  32   g  of the middle side  32   c  extends towards the uppermost idler  5 A. Within the upper sides  32   d , the upper middle sides  32   c , the second cants  32   g , and the top  32   e  and below the fan  38 , the housing  32  has the external fins  40 . The external fins  40  extend upwardly from the gambrel like portion of the housing  32 , particularly from the upper middle sides  32   c  and the second cants  32   g . The external fins  40  are generally spaced apart and mutually parallel and the external fins  40  are generally perpendicular to the bottom  32   a  and parallel to the upper sides  32   d . Each external fin  40  has a narrow cross section and an elongated form with a length in excess of twice the width of the fin  40 . 
     As described above, the housing  32  has internal fins  39  arrayed in a spiral pattern. The internal fins  39  of the housing  32  mesh with fins  41  extending from the back of the orbiting scroll  35  as shown in  FIG. 9 .  FIG. 9  shows a back face  35   a  of the orbiting scroll  35  that engages the housing  32 . The orbiting scroll  35  has a generally triangular shape defined by the three idlers  5 A installed at the vertices of the triangular shape. The orbiting scroll  35  has a bottom  35   c  having a generally horizontal orientation, that is parallel to a supporting surface when the scroll  35  is installed as in  FIG. 7 . In the preferred embodiment, the bottom  35   c  has a slight convex bulge  35   d  outwardly from the center of orbiting scroll  35 . Proceeding clockwise, the orbiting scroll  35  has a first leg  35   e  extending from above the idler  5 A and inwardly from the left of the bottom  35   c  as shown in this figure. The first leg  35   e  proceeds upwardly and towards a center line drawn perpendicular to the center of the bottom  35   c . The first leg  35   e  has an extension  35   f  outwardly from the orbiting scroll  35 . The extension  35   f  has a rounded over corner defined by two edges mutually perpendicular with one edge perpendicular to the bottom  35   c  and the other edge parallel to the bottom  35   c . The extension  35   f  mates with the upper side  32   c  in a similar right angle shape as at  32   d  of the housing  32  shown in  FIG. 8 . Above the extension  35   f  and away from the bottom  35   c , the first leg  35   e  continues to a vertex  35   i  generally centered above the bottom  35   c . Continuing clockwise, at the vertex  35   i , the first leg  35   e  wraps around the idler  5 A into a second leg  35   g . The second leg  35   g  extends from the vertex  35   i  downwardly and outwardly towards the end of the bottom  35   c  here shown to the right of the figure. Approximately centered along the length of the second leg  35   g , another slight convex bulge extends outwardly as at  35   h . The first leg  35   e  attains an approximately 60° angle to the bottom  35   c , the second leg  35   g  attains an approximately 60° angle to the first leg  35   e , and the bottom  35   c  attains approximately 60° angle to the second leg  35   g.    
     Upon the back face  35   a , the orbiting scroll  35  has a plurality of fins  41  arrayed thereon. The fins  41  extend outwardly from an imaginary center of the orbiting scroll  35  towards the bottom  35   c , the first leg  35   e , and the second leg  35   g . Each fin  41  has a narrow cross section and an elongated shape with a length of at least three times the width of the fin  41 . In the preferred embodiment, the fins  41  have a generally spiral arrangement however, the fins  41  may have alternate shapes of cylindrical or flat plate. These fins  41  extend from near the perimeter, that is the bottom  35   c , first leg  35   e , and second leg  35   g , of the orbiting scroll  35  inwardly towards a circular ring  42  that has an inside diameter proportional to that of the magnetic coupling  37  ( FIG. 7 ). The circular ring  42  has at least three holes for securing the orbiting scroll  35  to the magnetic coupling  37 . These fins  41  have a generally arcuate shape where the end of each of the fins  41  proximate the circular ring  42  is generally ahead of the opposite end of the fin  41  proximate the perimeter of the orbiting scroll  35 . Proximate the ring  42 , each fin  41  approaches the imaginary center of the orbiting scroll  35  upon a radial line. This overall arcuate shape of each fin  41  forms a generally counter-clockwise spiral in this view. These fins  41  have a regular radial spacing between adjacent fins  41  so that the fins  41  do not intersect each other. These fins  41  and the internal fins  39  of the housing  32  have sufficient spacing between them to permit motion of the orbiting scroll  35  during usage but without contact between these fins  41  and the internal fins  39 . Generally in the center of the ring  42 , the orbiting scroll  35  has a plenum  43  here shown on end. The plenum  43  admits working fluid as an internal coolant into the gaps between the orbiting scroll fins  41  and the internal fins  39  of the housing  32 . The plenum  43  provides fluid communication between the back face  35   a  and a front face  35   b  of the orbiting scroll  35 , as will be explained. 
       FIG. 10  then shows the front face  35   b  of the orbiting scroll  35  with the plenum  43  that prevents the working fluid from mixing with the cooling fluid in the housing  32 . This embodiment generally operates where the working fluid and the cooling fluid are the same. Usage of similar fluids accommodates any leakage across the seal of the enclosed plenum  43 . Alternatively, the enclosed plenum  43  can be incorporated with the fixed scroll  31 , similar to the bellows  22  and  23  as previously shown in  FIGS. 4 and 5 . As before, the orbiting scroll  35  has a generally triangular shape defined by the three idlers  5 A installed at the vertices of the triangular shape. The orbiting scroll  35  has the bottom  35   c  having a generally horizontal orientation, that is parallel to a supporting surface when installed. In the preferred embodiment, the bottom  35   c  has the slight convex bulge  35   d  outwardly from the center of orbiting scroll  35 . Proceeding clockwise which is generally opposite that of  FIG. 9 , the orbiting scroll  35  has the second leg  35   g  that proceeds upwardly and towards a centerline drawn perpendicular to the center of the bottom  35   c . Approximately centered along the length of the second leg  35   g , another slight convex bulge extends outwardly as at  35   h . The second leg  35   g  extends inwardly from the left of the bottom  35   c  as shown in this figure. The second leg  35   g  continues to the vertex  35   i  of the triangular shape generally above the center of the bottom  35   c . Continuing clockwise, at the vertex  35   i , the second leg  35   g  wraps around the idler  5 A into the first leg  35   e . The first leg  35   e  extends from above the idler  5 A, downwardly and outwardly towards the right end of the bottom  35   c  in this figure. The first leg  35   e  has its extension  35   f  outwardly from the orbiting scroll  35 . The extension  35   f  has a rounded over corner defined by two edges mutually perpendicular with one edge perpendicular to the bottom  35   c  and the other edge parallel to the bottom  35   c . The extension  35   f  mates with the upper side  32   c  in a similar right angle shape as at  32   h  of the housing  32  previously shown in  FIG. 8 . The first leg  35   e , the second leg  35   g , and the bottom  35   c  each attain approximately 60° angles relative to each other at each vertex of the orbiting scroll  35 . The front face  35   b  of the orbiting scroll  35  also includes a spiral involute  44 . The involute  44  has a generally narrow cross section, an elongated length, and spacing away from the surface of the front face  35   b , generally opposite the internal fins  41  of the back face  35   a . The involute  44  begins tangent to the plenum opening  43 , as at  44   a , generally parallel to the bottom  35   c . The involute  44  then curves at a constantly increasing radius as it wraps around the front face  35   b . Here the involute  44  completes more than four wraps,  44   b ,  44   c ,  44   d , and  44   e , around the plenum  43  where each successive wrap has a greater diameter. The involute  44 , in the fourth wrap  44   e , then extends perpendicular to the bottom  35   c  as at  44   f . This extension  44   f  of the involute  44  fits within the right angle shape  35   f  of the housing  32  upon the first leg  35   e  as previously described. The radius of the fourth wrap  44   e  also exceeds the distance from the center of the plenum  43  to the nearest side. Thus, the fourth wrap  44   e  of the involute  44  extends slightly from the orbiting scroll and occupies the convex bulge  35   d  of the bottom  35   c  and the convex bulge  35   h  of the second leg  35   g.    
       FIG. 11  shows the housing  32  upon an end  32   i  that faces the motor  34 . The housing  32  has its bottom  32   a , lower sides  32   b , middle sides  32   c , upper sides  32   d , and top  32   e  as previously described. The fan  38  rests upon the top  32   e  and draws air up, through, and around the housing  32  for air cooling. The end  32   i  has a generally smooth face. Generally centered between the middle sides  32   c , the housing  32  receives an inner rotor  45  concealed within a stationary can  46  of the magnetic coupling  37  as later shown in  FIG. 13 . The inner rotor  45  then transmits rotation to a compressor shaft  48  that joins to the back surface of the orbiting scroll  4 . Here in  FIG. 11 , the magnetic coupling  37  has a sealed shroud  47  that has a generally gambrel shape similar to that of the housing  32  but of a lesser scale. The shroud  47  bolts to the exterior surface of the housing  32 , generally opposite the back surface  35   a  of the orbiting scroll  35  as in  FIG. 7 . The shroud  47  has approximately five bolted connections, as at  47   a , which secure the shroud  47  to the housing  32 . Within the shroud  47 , the stationary can  46  secures to the housing  32  using approximately six bolted connections as at  46   a . Both the bolted connections  47   a  of the shroud  47  and the bolted connections  46   a  of the can  46  are mutually parallel and generally parallel to the axis of rotation of the inner rotor  45 . The motor  34  generates rotation and torque from its shaft as at  34   a  ( FIG. 13 ). The motor shaft  34   a  then drives the magnetic coupling  37  to rotate. The coupling  37  rotates thus transmitting the rotation and torque from the motor shaft  34   a  into the compressor shaft  48  without a physical connection between the motor shaft  34   a  and the compressor shaft  48 , as will be described in more detail further herein. 
     With reference now to  FIG. 12 , an end  49  of the housing  32 , which is opposite to the end  32   i , is illustrated. The end  49  is also opposite from the motor  34 . As previously described, the housing  32  has its bottom  32   a , lower sides  32   b , middle sides  32   c , upper sides  32   d , and top  32   e  generally in a mirror image as that of  FIG. 11 . The fan  38  rests upon the top  32   e  and draws air to cool the housing  32 . This end  49  also has a generally smooth face. The end  49  secures to the remainder of the housing  32  use bolted connections as at  49   a  in at least four locations, approximately as shown. Somewhat centered on this end  49 , the end  49  has a bearing  50  that receives a shaft from the fixed scroll  3 . 
     As mentioned briefly in  FIG. 11 , the motor  34  delivers rotation and torque to the orbiting scroll  4  through a magnetic coupling  37  shown with reference now to the section view in  FIG. 13 . The coupling  37  transmits rotation and torque from the motor shaft  34   a  to the compressor shaft  48  without a physical connection between the two shafts. Rather, the coupling  37  uses a magnetic field put into rotation to transmit rotation and torque from one shaft to another. Because the magnetic field penetrates steel and plastic, the coupling  37  transmits rotation and torque between the shafts while the compressor shaft remains sealed within the stationary can  46 . Sealing the compressor shaft  48  retains the cooling fluid and the working fluid within the housing  32  and prevents intrusion of the atmosphere along the compressor shaft  48  into the housing  32 . As before, the magnetic coupling  37  has the shroud  47  that extends between the motor  34  and the housing  32  and encloses the coupling  37 . The shroud  47  bolts on its own opposite ends to both the motor  34  and the housing  32  as shown and described. Inside the shroud  47 , the motor  34  extends its shaft  34   a  within the shroud  47  towards the adjacent housing  32 . 
     The shaft  34   a  has secured to it an outer rotor  51  here shown as a generally U shape in section view. The outer rotor  51  has a generally round cylindrical shape with a closed end  51   a  adjacent to the shaft  34   a  and an opposite open end as at  51   b  proximate the housing  32 . The outer rotor  51  has a generally curved wall  51   c  extending perpendicular to the perimeter of the closed end  51   a . The outer rotor  51  has its own magnetic polarity and its own inside diameter. 
     Inside of the outer rotor  51 , the magnetic coupling  37  has the stationary can  46  that secures to the housing  32  through its bolts as at  46   a . The stationary can  46  is also a generally round cylinder, shown here as a U shape in section view, with a closed end  46   b , an opposite open end  46   c , and a thin wall  46   d  that expands outwardly into a flange  46   e  for receiving the bolts  46   a  adjacent to the housing  32 . The stationary can  46  also includes an O-ring or gasket as at  46   f  upon its circumference upon the interior of the flange  46   e  that seals the stationary can  46  upon the housing  32  and prevents intrusion of the atmosphere into the housing  32 . The stationary can  46  has an outside diameter less than the inside diameter of the outer rotor  51  and limited effect on the magnetic field of the outer rotor  51 . 
     Then inside of the stationary can  46 , the magnetic coupling  37  has its inner rotor  45  generally coaxial with the compressor shaft  48  and mechanically secured to the compressor shaft  48 . The inner rotor  45  is a somewhat round cylinder with a recess at its base, here shown as a thickened U shape with an extension at the base of the U shape. The inner rotor  45  has an open end  45   b  and an opposite closed end  45   a  with an extension  45   c  recessed in from a wall  45   d  forming the inner rotor  45 . The wall  45   d  is generally thick, much thicker in comparison to the walls  46   b  and  46   d  of the stationary can  46  and the outer rotor  51 . In the alternate embodiment, the entire inner rotor  45  has a magnetic polarity opposite that of the outer rotor  51 . The opposite polarities attract the inner rotor  45  to rotate in the direction of the outer rotor  51 . Alternatively, the inner rotor  45  is magnetically neutral and includes a magnetic band  45   e  around the perimeter of the inner rotor  45  and extends for substantially the length of the wall  45   d . The magnetic band  45   e  has an opposite magnetic polarity to the outer rotor  51 . The inner rotor  45  has an outer diameter less than the inside diameter of the stationary can  46 . So, turning of the outer rotor  51  by the motor  34  causes the inner rotor  45  to turn in the same direction through magnetic attraction without a physical connection of the motor shaft  34   a  to the compressor shaft  48 . Additionally because the motor  34  turns magnetized parts within the magnetic coupling  37 , the housing  32 , the motor  34 , and the coupling  37  are grounded to dissipate any electrical charge created by the rotating magnetic parts. 
     With reference now to  FIG. 14 , a three stage vacuum pump  100  is depicted in a sectional view lengthwise. The pump  100  begins with its first fixed scroll  3  having a plurality of fins  52  extending outwardly and generally opposite the scroll  3  itself. Generally centered within the fins  52 , the first fixed scroll  3  has a vacuum fitting  53  for connection to a space, hose, or device that is to be evacuated. The vacuum fitting  53  leads to a passage  54  extending into the first fixed scroll  3  that admits any gas molecules into the center of the scroll  3 . The first fixed scroll  3  has an expanding spiral shape, here shown on edge, that directs any gas molecules outwardly. The first fixed scroll  3  allows a first orbiting scroll  4  to inter mesh with it. The first orbiting scroll  4  rotates within the first fixed scroll  3  directing any gas molecules outwardly from the center of both scrolls  3  and  4  towards an edge of the scrolls  3  and  4 . The first orbiting scroll  4  operates upon three idlers  5   a  generally arranged in an equiangular manner. This figure shows one idler  5   a  proximate the top of the fixed scroll  3 . The idler  5   a  operates upon a first eccentric shaft  5   b  supported upon bearings  57  as shown. A bearing nut  56  secures the bearings  57  upon the eccentric shaft  5   b  while permitting the shaft  5   b  to rotate axially. As described, the first fixed scroll  3  and the first orbiting scroll  4  define the first stage of this three stage vacuum pump  100 . 
     The orbiting scroll  4  also has a second scroll  4   a  upon its inward surface, that is, opposite the first fixed scroll  3 . Inwardly from the first orbiting scroll  4 , a second fixed scroll  59  inters meshes with the scroll  4   a . The second fixed scroll  59  cooperates with the second scroll  4   a  of the first orbiting scroll  4  to compress any gas molecules beginning at the periphery of the second scroll  4   a  and directly them inwardly towards the center of the second fixed scroll  59 . The second scroll  4   a  and the second fixed scroll  59  form the second stage of this three stage vacuum pump  100 . 
     The first fixed scroll  3 , the first orbiting scroll  4 , the second scroll  4   a , and the second fixed scroll  59  each have tip seals  24  along the entire lengths of each scroll respectively. The tip seals  24  prevent escape of any gas molecules between adjacent scrolls as the orbiting scroll and second scroll inter mesh with their respective fixed scrolls. One version of the tip seal  24  has been previously shown in  FIG. 6 . 
     The idlers, as at  5   a , also pass through the second fixed scroll  59 . In doing so, the eccentric shaft  5   b  has a center line off center from its center line passing through the first fixed scroll  3 . Where the eccentric shaft  5   b  fits into the first orbiting scroll  4 , a shim  58  occupies any gap between the nearest bearing  57  in the first orbiting scroll  4  and the eccentric shaft  5   b . Opposite the shim  58  as shown, a screw  68  compresses the bearings  57  into the second fixed scroll  59 . The first fixed scroll  3  seals to the second fixed scroll  59  proximate its exterior perimeter using an O-ring as at  55 . 
     Opposite its involute, the second fixed scroll  59  has a plurality of fins  62  generally parallel to exterior fins  52  located on the housing  32 . These fins  62  have a depth greater than the depth of the involute of the fixed scroll  59  and approximately the same depth as the exterior fins  52 . Generally centered upon the fixed scroll  59 , the involute opens at the center of the second fixed scroll  59  to a center passage  63  within a hollow stub  59   a . The hollow stub  59   a  has a thickness generally greater than the fins  62 . Outwardly from the stub  59   a , the second fixed scroll  59  has three sockets  59   b  spaced equiangular that receive the idlers  5   a . As later shown, the three stage vacuum pump  100  has a generally triangular shape when viewed from its end. The idlers  5   a  locate proximate the vertices of the triangular shape. 
     Slightly outward from the socket  59   b , the first fixed scroll  3  abuts the second fixed scroll  59 . An O-ring, as at  60 , seals these two scrolls upon their mutual perimeter. Then proximate the base of the sockets  59   b , opposite the orbiting scroll  4 , each idler  5   a  has an O-ring  60  that seals it to a third fixed scroll  64 . The stub  59   a  also has an O-ring  61  that seals it to the third fixed scroll  64  so that the center passage  63  continues and does not leak any gas molecules into the center passage. 
     The third fixed scroll  64  generally aligns with the second fixed scroll  59  as shown, in the center of  FIG. 14 . The third fixed scroll  64  has a plurality of fins  65  that align to the fins  62  of the second fix scroll  59 . The fins  65  generally have a butt to butt facing with the fins  62 . The third fixed scroll  64  has a tube  64   a , generally hollow, that abuts the stub  59   a  of the second scroll  59  and the center passage  63  continues through the tube  64   a . Outwardly from the tube  64   a , the third fixed scroll  64  has sockets  64   b  that receive the idlers  5   a . The idlers  5   a  in the third fixed scroll  64  have an eccentric shaft  67  having a socket  67   a  that receives an end of the eccentric shaft  67  from the first and second stages of the pump  100 . The eccentric shaft  67  of the third fixed scroll  64  has seals  66  that partially fill each socket  67   a  away from the second stage. Upon the seals  66 , each idler  5   a  has a bearing  57 , generally opposite the fins  65  and proximate the scroll work of the third fixed scroll  64 . Opposite the fins  65 , the third fixed scroll  64  has its involute. The involute begins where the center passage  63  opens through the third fixed scroll  64 . The involute then expands outwardly in a spiral like pattern. 
     The involute of the third fixed scroll  64  then inter meshes with involute from a second orbiting scroll  70 . The scroll work of the second orbiting scroll  70  generally aligns with the scrolls of the first orbiting scroll  4  and its second scroll  4   a . The second orbiting scroll  70  rotates within the third fixed scroll  64  so that any gas molecules entering the second orbiting scroll  4   a  from the center passage  63  migrate outwardly along the inter meshed scroll which then exhausts the molecules from the pump  100 . Outwardly from the center passage  63 , the second orbiting scroll  70  has a socket  70   a  that receives the bearings  57  of the eccentric shaft  67  of the idler  5   a . A bearing nut  56  outwardly from the bearings  57 , that is, opposite the third fixed scroll  64 , secures the bearings  57  and the shaft  67  within the socket  70   a . Opposite the bearing nut  56 , a shim  69  fits the bearings  57  against the eccentric shaft  67 . The second orbiting scroll  70  and the third fixed scroll  64  form the third stage of this three stage vacuum pump  100 . As with the first and second stages, the third fixed scroll  64  and the second orbiting scroll  70  each have tip seals  24  along the entire lengths of each scroll  64  and  70  respectively, as previously shown in  FIG. 6 . The tip seals  24  form a gas tight chamber as the scrolls  64  and  70  inter mesh. 
     Proximate the center passage  63  and off center from the center passage  63 , here shown downwardly in  FIG. 14 , the second orbiting scroll  70  includes an inner bearing race  76  that admits an eccentric driving pin  5 . The eccentric driving pin  5  extends outwardly from the second orbiting scroll  70  through a sealing disc  77  placed upon the bearing race  76  opposite the center passage  63 . The eccentric driving pin  5  is generally round and extends outwardly from the second orbiting scroll  70  to a round shaft  5   d . Though the shaft  5   d  is round, the eccentric driving pin  5  joins to the shaft  5   d  off center. The off center arrangement of the eccentric driving pin  5  allows the shaft  5   d  to rotate about an axis coaxial with the center passage  63  while inducing an orbital rotation to the second orbiting plate  70  which induces rotation of the idlers  5   a  in the third stage transmitted through the shaft  67  to the idlers  5   a  in the second and first stages. The shaft  5   d  in its rotation induces both orbiting scrolls to orbit at the same time. Downwardly and outwardly from the driving pin  5  and the round shaft  5   d , a crankshaft  74  extends towards the bottom of the pump  100 , generally towards a foot  78 . The crankshaft  74  has an inverted L shape as shown where the flange of the L shape adjoins the driving pin  5  and the round shaft  5   d  and web of the L shape extends outwardly from the driving pin  5 . The web is generally thin and of a length so that the crankshaft  74  avoids colliding with the idler  5   a  towards the top of this figure and the housing  32  towards the bottom of this figure. The crankshaft  74  includes its setscrew  75  that secures it to the round shaft  5   d.    
     Outwardly from the shaft  5   d , a housing  71  encloses the second orbiting scroll  70 , the driving pin  5  and the round shaft  5   d . The housing  71  cooperates with the fins  65  of the third fixed scroll  64 , the fins  62  of the second fixed scroll  59 , and the first scroll  3  to enclose the pump  100 . Bolts  47   a  secure the housing  71  and the first scroll  3  together with the second fixed scroll  59  and third fixed  64  scrolls between them. Feet  78  extend downwardly from the housing  71  and the first scroll  3 . 
     Having described the round shaft  5   d  as rotating, the round shaft  5   d  extends from a motor  7  joined to the housing  71 . The round shaft  5   d  and the remainder of the motor  7  have an axis of rotation R-R centered upon the center passage  63  as shown. The motor  7  has sufficient horsepower and torque to rotate the first orbiting scroll  4  and the second orbiting  70  and suitable revolutions per minute to evacuate any gas molecules that enter the vacuum fitting  53 . The motor  7  moving the three stages of scrolls produce vacuums of approximately 2 millitorr (mTorr). Because the motor  7  turns the eccentric driving pin  5 , the motor  7  includes a counterweight  72  connected to the round shaft  5   d  opposite the housing  71 . The counterweight  72  is generally linear and placed at an angle opposite the driving pin  5  and the crankshaft  74 . The counterweight  72  counteracts the angular momentum of the driving pin  5  and the two orbiting scrolls thus minimizing vibrations generated by the pump  100 . A set screw  73  allows for adjusting the position of the counterweight  72  relative to the axis R-R of rotation of the motor  7 . 
     Having described the pump  100  from its vacuum fitting  53  along the flow path of the center passage  63  back to the motor  7  driving the orbiting scrolls  4  and  70  through the idlers  5   a  reference is now made to  FIG. 15  which shows an exterior end view of the pump  100 . The pump  100  has a somewhat triangular shaped end upon two feet  78  with the vacuum fitting  53  shown generally centered and the passage  54  centered inside of the fitting  53 . Outwardly from the vacuum fitting  53 , this end view shows the exterior of the first fixed scroll  3  that has a plurality of horizontal fins  52  generally parallel to a plane defined by the feet  78 . The fixed scroll  3  connects to the remainder of the pump  100  upon a plurality of bolts  47   a  here shown as two proximate the feet  78 , two outwardly from the vacuum fitting  53 , and two more bolts  47   a  proximate the top of the fixed scroll  3  outwardly and beneath the curved top. Behind the curved top as shown, the top of the second fixed scroll  64  appears. Towards the right of the pump  100  in this figure, that is, opposite the view of  FIG. 14 , the pump  100  has the fan  38  encased within a guard  38   a . The fan  38  generally extends for the length of the three stages of scrolls as later shown. The fan  38  draws air around the scrolls and through the fins  62  and  65  where the second and third fixed scrolls  59  and  64  join. This air flow provides cooling as the various scrolls extract heat during their formation of higher order vacuums. 
       FIG. 16  shows the pump  100  opposite that of  FIG. 14  from the exterior. The pump  100  has the vacuum fitting  53  upon the left, here shown as a flange connecting through a narrower tube to the first fixed scroll  3 . The fixed scroll  3  has its fins  52 , here shown on end, and extending perpendicular to the center passage  54 . The first fixed scroll  3  adjoins the second fixed scroll  59  which adjoins the third fixed scroll  64  and which adjoins the housing  71  as shown across the top of the fan  38  from left to right. The scrolls  3 ,  59 , and  64  and the housing  71  are secured upon each other using the bolts  47   a  that extend through each of the scrolls  3 ,  59 , and  64  and the housing  71 . Beneath the fan  38 , feet  78  support the first fixed scroll  3  and the housing  71  respectively. The fan  38  extends along the three fixed scrolls  3 ,  59 , and  64  and draws air across and through them for cooling. Opposite the vacuum fitting  53 , the motor  7 , with its counterweight  72 , provides balance rotational power through its driving pin to the orbiting scrolls and idlers as previously described. 
     Referring now to  FIG. 17 , an alternate embodiment of the present three stage vacuum pump  102  is depicted in a sectional view lengthwise. The pump  102  begins with a first fixed scroll  3  having a smooth exterior face outwardly from the pump  102 . Generally centered within the fixed scroll  3 , a vacuum fitting  53  provides a connection to a space, hose, or device that is to be evacuated. The vacuum fitting  53  leads to a passage  54  extending into the first fixed scroll  3  that admits any gas molecules into the center of the fixed scroll  3  away from the space to be evacuated. The first fixed scroll  3  has an expanding spiral shape, here shown on edge, that directs any gas molecules outwardly. The first fixed scroll  3  allows a first orbiting scroll  4  to inter mesh with it. The first orbiting scroll  4  rotates within the first fixed scroll  3  directing any gas molecules outwardly from the center of both scrolls  3  and  4  towards an edge of the scrolls  3  and  4 . The first orbiting scroll  4  operates upon three idlers  5   a  generally arranged in an equiangular manner. This figure shows at least one idler  5   a  proximate the top of the fixed scroll  3 . The idler  5   a  operates upon a first eccentric shaft  5   b  supported upon bearings  57  as shown. A bearing nut  56  secures the bearings  57  upon the eccentric shaft  5   b  while permitting the shaft  5   b  to rotate axially. As described, the first fixed scroll  3  and the first orbiting scroll  4  define the first stage of this three stage vacuum pump  102 . 
     The orbiting scroll  4  also has a second scroll  4   a  upon its inward surface, that is, opposite the first fixed scroll  3 . Inwardly from the first orbiting scroll  4 , a second fixed scroll  59  inters meshes with the scroll  4   a . The second fixed scroll  59  cooperates with the second scroll  4   a  of the first orbiting scroll  4  to compress any gas molecules beginning at the periphery of the second scroll  4   a  and directing them inwardly towards the center of the second fixed scroll  59 . The second scroll  4   a  and the second fixed scroll  59  form the second stage of this three stage vacuum pump  102 . As before, the first fixed scroll  3 , the first orbiting scroll  4 , the second scroll  4   a , and the second fixed scroll  59  each have tip seals  24  along the entire lengths of each scroll respectively. 
     The idlers, as at  5   a , also pass through the second fixed scroll  59 . In doing so, the eccentric shaft  5   b  has an offset center line from a center line passing through the first fixed scroll  3 . The first fixed scroll  3  seals to the second fixed scroll  59  proximate its exterior perimeter using an O-ring as at  55 . 
     Opposite its involute, the second fixed scroll  59  adjoins to chambers  88  forming a generally annular volume within this embodiment suitable for cooling the three stages. Generally centered upon the fixed scroll  59  and within the chambers  88 , the involute opens at the center of the second fixed scroll  59  to a center passage  63  within an elongated stub  54   a , which is longer than the stub  59   a  shown in  FIG. 14 . This elongated stub  54   a  has a thickness slightly more than that of the second fixed scroll  59 . Outwardly from the stub  54   a , the second fixed scroll  59  has three sockets  59   b  spaced equiangular that receive the idlers  5   a . As previously shown, this alternate embodiment of the three stage vacuum pump  102  also has a generally triangular shape when viewed on end. The idlers  5   a  locate proximate the vertices of the triangular shape. 
     Towards the interior of this embodiment, the second fixed scroll  59  abuts a third fixed scroll  64 . The third fixed scroll  64  has an elongated stub  64   a  that aligns with the elongated stub  54   a  of the second fixed scroll  59  forming a continuous center passage from the second stage into the third stage of this embodiment of the pump  102 . The stub  54   a  also has an O-ring  61  that seals it to the third fixed scroll  64  so that the center passage  63  continues and does not leak any gas molecules into the center passage. As previously discussed, the O-ring  55  seals the first fixed scroll  3  to the second fixed scroll  59  upon their mutual perimeter. The third fixed scroll  64  generally aligns with the second fixed scroll  59  as shown upon a common axis defined by the center passage  63 , in the center of  FIG. 17 . The third fixed scroll  64  locates away from the joint of the elongated stubs  54   a  and  64   a  so that the chambers  88  have a generally rectangular shape in section view as here shown. 
     As shown in  FIG. 17  and above the center passage  63 , outwardly from the stub  64   a , the third fixed scroll  64  has sockets that receive the idlers  5   a . The idlers  5   a  in the third fixed scroll  64  have an eccentric shaft  67  that extends into a magnetic coupling  37 . Generally centered between the second stage and the third stage, a housing  71  receives an inner rotor  45  concealed within a stationary can  46  of the magnetic coupling  37  as later shown in  FIG. 18 . The inner rotor  45  then transmits rotation to eccentric shaft  5   b  that rotates the first orbiting scroll  4 . In usage, the magnetic coupling  37  receives rotation and torque through the eccentric shaft  67 . The coupling  37  rotates thus transmitting the rotation and torque from the shaft  67  into the eccentric shaft  5   b  through the first and second stages of this pump  102  without a mechanical connection as in the preferred embodiment of the three stages pump  100 . 
     The eccentric shaft  67  of the third fixed scroll  64  has seals that partially fill each socket away from the second stage. Upon the seals, each idler  5   a  has a bearing  57 , generally opposite the chambers  88  and proximate the scroll work of the third fixed scroll  64 . Opposite the chambers  88  and the magnetic coupling  37 , the third fixed scroll  64  has its involute. The involute begins where the center passage  63  opens through the third fixed scroll  64 . The involute then expands outwardly in a spiral like pattern. 
     The involute of the third fixed scroll  64  then inter meshes with involute from a second orbiting scroll  70 . The scroll work of the second orbiting scroll  70  generally aligns with the scrolls of the first orbiting scroll  4  and its second scroll  4   a . The second orbiting scroll  70  rotates within the third fixed scroll  64  so that any gas molecules entering the second orbiting scroll  70  from the center passage  63  migrate outwardly along the inter meshed scroll which then exhausts the molecules from the pump  102  through an outlet  81 . Outwardly from the center passage  63 , the second orbiting scroll  70  has a socket  70   a  that receives the bearings  57  of the eccentric shaft  67  of the idler  5   a . A bearing nut  56  positioned outwardly from the bearings  57 , that is opposite the third fixed scroll  64 , secures the bearings  57  and the shaft  67  within the socket  70   a . Opposite the bearing nut  56 , a shim fits the bearings  57  against the eccentric shaft  67 , if needed. The second orbiting scroll  70  and the third fixed scroll  64  form the third stage of this three stage vacuum pump  102 . As with the first and second stages, the third fixed scroll  64  and the second orbiting scroll  70  each have tip seals  24  along the entire lengths of each scroll respectively, as previously shown in  FIG. 6 . The tip seals  24  form a gas tight chamber as the scrolls  64  and  70  inter mesh. 
     Aligned with the center passage  63 , the second orbiting scroll  70  includes a bearing  14  that admits a drive pin  8 , generally round and cylindrical. The drive pin  8  extends outwardly from the second orbiting scroll  70  through a sealing disc, if needed. The drive pin  8  extends outwardly and to a flywheel  79  generally centered upon the center passage  63 . The flywheel  79  has its diameter generally perpendicular to the center passage  63  and a thickness slightly less than the length of the drive pin  8 . The flywheel  79  provides for steady rotation of the second orbiting scroll  70  once operating revolutions have been reached. The flywheel  79  has its central hub that connects with the round shaft  5   d  that rotates about an axis coaxial with the center passage  63  while inducing an orbital rotation to the second orbiting plate  70  which induces rotation of the idlers  5   a  in the third stage transmitted through the shaft  67  to the magnetic coupling  37  and then the idlers  5   a  in the second and first stages. The shaft  5   d  in its rotation induces both orbiting scrolls  4  and  70  to orbit at the same time. 
     Outwardly from the shaft  5   d , the housing  71  encloses the second orbiting scroll  70 , driving pin  8 , flywheel  79 , and round shaft  5   d . The housing  71  cooperates with the elongated stubs  54   a ,  64   a , chambers  88 , and the first fixed scroll  3  to enclose the pump  102 . Bolts  47   a  secure the housing  71  and the first scroll  3  together with the second fixed scroll  59  and third fixed scroll  64  between them. Feet  78  extend downwardly from the housing  71  and the first scroll  3 . 
     Having described the round shaft  5   d  as rotating, the round shaft  5   d  extends from a motor  7  joined to the housing  71  outwardly from the remainder of the pump  102 . The round shaft  5   d  and the remainder of the motor  7  have an axis of rotation centered upon the center passage  63  as shown. The motor  7  has sufficient horsepower and torque to rotate the first orbiting scroll  4  and the second orbiting  70  at suitable revolutions per minute through the magnetic coupling  37  to evacuate any gas molecules that enter the vacuum fitting  53 . The motor  7  moving the three stages of scrolls produce vacuums of approximately 2 millitorr but without mechanical connection between the second stage and the third stage. The motor  7  generates rotation and torque from its shaft as at  5   d  that turns the flywheel  79  that turns the drive pin  8  into the second orbiting scroll  70  which turns the shaft  67  that rotates an outer rotor  51  that induces rotation of the inner rotor  45  that then turns the idler shaft  5   a  in the second and first stages. 
     As mentioned briefly in  FIG. 17 , the motor  7  delivers rotation and torque to the second orbiting scroll  70  then into the eccentric shaft  67  of the idler  5   a  connected to the magnetic coupling  37  shown in a section view in  FIG. 18 .  FIG. 18  is somewhat of a mirror image from  FIG. 13 . The coupling transmits rotation and torque from the round shaft  5   d  through the flywheel  79 , second orbiting scroll  70 , into the eccentric shaft  67  to the idler shaft  5   b  proximate the second fixed scroll  59  without a physical connection between the two shafts. Rather the coupling uses a magnetic field put into rotation to transmit the rotation and torque from one shaft to another. Because the magnetic field penetrates steel and plastic, the coupling transmits rotation and torque between the shafts while the idler shaft  5   b  of the second fixed scroll  59  remains sealed within the stationary can  46 . Sealing the idler shaft  5   b  retains the partial vacuum created in the first and second stages and allows any remaining molecules to solely exit through the center passage  63 . Sealing the idler shaft  5   b  also prevents intrusion of the atmosphere into the first and second stages. The magnetic coupling  37  in this embodiment is located within the housing  71 , above the center passage  63 , and inside of the second fixed scroll  59 . 
     The eccentric shaft  67  has secured to it the outer rotor  51  here shown as a generally U shape, rotated clockwise, in section view. The outer rotor  51  has a generally round cylindrical shape with a closed end  51   a  adjacent to the eccentric shaft  67  and an opposite open end as at  51   b  proximate the second fixed scroll  59 . The outer rotor  51  has a generally curved wall  51   c  extending perpendicular to the perimeter of the closed end  51   a . The outer rotor  51  has its own magnetic polarity and its own inside diameter. 
     Inside of the outer rotor  51 , the magnetic coupling  37  has the stationary can  46  that secures to the first fixed scroll  3 , generally towards the top of this figure, and the second fixed scroll  59  generally in the direction of the center passage  63  through its bolts as at  46   a . The stationary can  46  is also a generally round cylinder, shown here as a U shape rotated ninety degrees clockwise in section view, with a closed end  46   b , an opposite open end proximate  46   d , and a thin wall  46   c  that expands outwardly into a flange  46   f  for receiving bolts  46   a  adjacent to the housing  71 . The stationary can  46  also includes an O-ring or gasket as at  46   e  upon its circumference upon the interior of the flange  46   f  that seals the stationary can  46  upon the second fixed scroll  59  and prevents intrusion of the atmosphere into the second and first stages. The stationary can  46  has an outside diameter less than the inside diameter of the outer rotor  51  and limited effect on the magnetic field of the outer rotor  51 . 
     Then inside of the stationary can  46 , the magnetic coupling  37  has its inner rotor  45  generally coaxial with the idler shaft  5   b  extending from the second stage and mechanically secured to it as at  48   a . The inner rotor  45  is a somewhat round cylinder with a recess at its base, here shown as a thickened U shape with an extension at the base of the U shape. The inner rotor  45  has an open end  45   b  and an opposite closed end  45   a  with an extension  45   c  recessed in from a wall  45   d  forming the inner rotor  45 . The wall  45   d  is generally thick, much thicker in comparison to the walls of the stationary can  46  and the outer rotor  51 . In this alternate embodiment, the entire inner rotor  45  has a magnetic polarity opposite that of the outer rotor  51 . The opposite polarities attract the inner rotor  45  to rotate in the direction of the outer rotor  51 . Alternatively, the inner rotor  45  has magnetic neutrality and includes a magnetic band  45   e  around the perimeter of the inner rotor  45  that extends for substantially the length of the wall  45   d . The magnetic band  45   e  has an opposite magnetic polarity to the outer rotor  51 . The inner rotor  45  has an outer diameter less than the inside diameter of the stationary can  46 . So, turning of the outer rotor  51  by the eccentric shaft  67  causes the inner rotor  45  to turn in the same direction through magnetic attraction without a physical connection of the eccentric shaft  67  to the idler shaft  5   b  between the third stage and the second stage. Additionally because the eccentric shaft  67  turns magnetized parts within the magnetic coupling  37 , the first fixed scroll  3 , the second fixed scroll  59 , the eccentric shaft  67 , the motor  7 , and the coupling  37  are grounded to dissipate any electrical charge created by the rotating magnetic parts. 
     From the aforementioned description, a three stage vacuum pump from the machine class of scroll compressors, pumps, and expanders has been described. This three stage vacuum pump is uniquely capable of expanding and compressing a fluid cyclically to evacuate a line, device, or space connected to the pump without intrusion of the nearby atmosphere. During operation, this pump generates heat within its fixed and orbiting scrolls which is dissipated through cooperating fins upon the surrounding housing or through chambers in an alternate embodiment. This pump receives its motive power directly from a motor or alternatively from a motor connected to a magnetic coupling, further minimizing the incidence of atmospheric intrusion within the housing and the working fluid. The present disclosure and its various components may adapt existing equipment and may be manufactured from many materials including but not limited to metal sheets and foils, elastomers, steel plates, polymers, high density polyethylene, polypropylene, polyvinyl chloride, nylon, ferrous and non-ferrous metals, their alloys, and composites.