Abstract:
A multiple impeller flow inducing device in which driver coils are intermittently energized in timed relation to rotation of the impellers to interact with permanently magnetized portions of the impeller to rotate the same. The impellers can be rotated in opposite directions or in the same direction. A two section impeller construction allows each section to be magnetized in opposite pole orientation and when assembled creating alternate pole orientations of successive portions, arcuate segments forming a shroud or the type of blades can be magnetized to provide the impeller magnetized portions. Stator guide vanes can be interposed between successive impellers.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of U.S. Ser. No. 09/303,334, filed on Apr. 30, 1999, which is a continuation-in-part of U.S. Ser. No. 09/172,524, filed on Oct. 14, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention concerns axial fluid flow inducing devices such as fans, which use a set of rotating blades reacting with the fluid to cause axial fluid flow. 
     In the above-referenced copending application there is described a unique direct magnetic drive in which impeller blades are permanently magnetized to establish a magnetic pole at each blade tip, which interacts with pulsed magnetic fields set up by one or more electromagnets located around the perimeter of the impeller or rotor in such a way that magnetic repulsion and attraction forces acting on the blades cause the impeller to rotate. 
     In the past, in order to increase the static pressure generated by an axial flow impeller, it has been the practice to provide fixed stator blades providing fluid reaction surfaces increasing the static pressure generated downstream of the impeller. The presence of the stator blades creates flow resistance, reducing flow. To avoid this disadvantage, it is known that counter-rotating impellers increase the static pressure without increasing flow losses in the system. However, complex mechanical drives are necessary in order to drive two or more closely positioned coaxial impellers in opposite directions. 
     It is one object of the present invention to provide a drive for multi counter rotating impellers not requiring a complex mechanical drive means. 
     Another known flow device has multiple impellers connected together and rotating in the same direction in order to provide a multiple stage pumping action. However, in order to enable proper multistage operation of synchronously rotating impellers, reduced blade areas must be established that increased the cost. In this application blade area remains the same while rotation speed is changed. 
     It is thus another object of the present invention to provide a multistage impeller in which the material and labor costs are reduced. 
     SUMMARY OF THE INVENTION 
     The above objects as well as others that will become apparent upon reading of the following specification and claims are achieved by an arrangement of a plurality of impellers that are coaxially mounted in a shroud and independently rotated with respect to each other. In a first application of the invention, the impellers are driven by forces created by intermittently generated magnetic fields acting on magnetized portions of each of the impellers so as to rotate the impellers. By causing rotation of two impellers in opposite directions a much-simplified means is provided for obtaining increased static pressure of the fluid flow induced by rotation of the impeller blades. Preferably, the magnetic field is generated by a pulsed generating means including one or more driver coils each having an U-shaped core with opposite core legs extending generally radially and with their ends located adjacent the outer perimeter of the associated impeller. 
     Preferably, a pair of electromagnetic driver coils is provided which are arranged at an angle to each other and spaced apart so that when one pair of core legs straddles one blade, the other pair has sequential blades aligned with each leg. A pair of sensors, such as Hall effect sensors, are arranged to detect the passage of the leading edge of each successive impeller blade and to control the energization and magnetic polarity of the driver coils such as to induce rotation in opposite directions of each impeller by magnetic interaction between the field of the respective coils and the magnetic field of the permanently magnetized portions of the impeller blades. 
     For the embodiment of the invention having two counter rotating impellers, each electromagnetic coil is preferably skewed such that respective legs of the coil core are located at the outer perimeter of a respective impeller so that both impellers are energized and driven by the same pair of electromagnetic coils making synchronization of the rotation of the two impellers much simpler. However, using more than one pair of electromagnetic coils is also possible, each disposed around the perimeter of a respective impeller. 
     Driving the impellers by a single driver coil is also possible. In this case, a simple electromagnet may be utilized in order to locate each impeller in a proper start up position with respect to the driving electromagnetic coil in which the spaced core legs straddle a blade tip. 
     The impellers preferably have blades of a type of plastic material that is permanently magnetizable and the magnetized tips comprise the outer portions of the impeller blades that are magnetized to interact with the pulsed magnetic fields. 
     The impellers may be constructed in two sections, each having an alternate set of impeller blades with the tips magnetized with the same polarity, and each impeller section having its tips magnetized with opposite poles to the other section. The impeller sections are interfit at assembly to produce an impeller in which successive blades are magnetized with opposite polarities. 
     Alternatively, instead of a stationary shroud, the fluid flow passage can be formed by an outer ring that concludes, which is formed by a series of arcuate segments attached to the tip of each rotor blade, each segment interfit to the next adjacent segment on either side. Again, a two-section impeller construction may be advantageously employed. 
     An intermediate ring fixed to one impeller may also be employed with a labyrinth seal formed between the ring and adjacent end of the corresponding impeller. 
     The impeller ring segments adjacent the housing end wall may be provided with projecting portions that are received within the housing to form a labyrinth seal, such that while each ring rotates independently of the other, a sealed confinement of the fluid flow is assured. 
     In another version, the outer ring can be attached to the tips of blades and magnetized by segments with opposite polarities. 
     The impellers may also have magnetized outer portions which are driven by pairs of driver coils in such a manner as to be driven in the same direction at controllably different rates of rotation such as to produce a multistage pumping action which does not require differing impeller blade areas. A set of stator blades is required to be placed between impellers. 
     In another version, connected impellers can be disposed on either side of a set of stator blades. 
    
    
     DESCRIPTION OF THE DRAWING FIGS. 
     FIG. 1 is an end view of a fluid flow inducing device according to the invention utilizing a plurality of independently rotated impellers. 
     FIG. 1A is a fragmentary sectional view of the device shown in FIG. 1, showing an alternate shroud construction with the driver coils in which the driver coil core legs are inserted in holes in the shroud. 
     FIG. 1B is a fragmentary sectional view of the device shown in FIG. 1 in which the core legs are inserted in recesses in the shroud. 
     FIG. 1C is a fragmentary sectional view of the device shown in FIG. 1 in which formula parameters for calculating the angle between the driver coils are indicated. 
     FIG. 2 is a longitudinal sectional view of the device shown in FIG.  1 . 
     FIG. 3 is an end view of an alternate embodiment of the device utilizing a single driver coil and a simple start up positioning coil. 
     FIG. 4 is an end view of another alternative embodiment of the device in which a pair of driver coils having an U-shaped core is utilized which are skewed axially in order to enable a single pair of driver coils to drive both of the impellers. 
     FIG. 5 is a side view of the device shown in FIG. 4 illustrating the orientation of the single pair of driver coils. 
     FIG. 6 is an end view of yet another alternative of the device according to the invention utilizing magnetized ring segments attached to each set of impeller blade tips forming labyrinth seals with the adjacent impeller and the adjacent housing structure. 
     FIG. 7 is a partially sectional longitudinal view of the device shown in FIG.  6 . 
     FIGS. 8 and 9 are end views of impeller sections which are interfit together at assembly to form a complete impeller. 
     FIG. 10 is an end view of another variation of the device according to the invention utilizing a sectional impeller. 
     FIG. 11 is a transverse longitudinal partially sectional view of the device shown in FIG.  10 . 
     FIGS. 12 and 13 are end views of respective impeller sections separately manufactured and permanently magnetized, then assembled together to form a complete impeller. 
     FIGS. 14A-14D are end view diagrams of the axial fluid flow inducing device, indicating the magnetic drive of the impellers by identically controlled energization of respective pairs of electromagnetic driver coils. 
     FIGS. 15A-15D are end view diagrams of a first impeller of a multistage device indicating energization of a pair of driver coils and the relationship of the magnetized tip impeller blades to achieve rotation of a first stage impeller in one direction. 
     FIGS. 16A-16D are end view diagrams of a second impeller of a multistage device indicating energization of a pair of driver coils and the relationship with the magnetized tip of impeller blades to achieve rotation in an opposite direction to the first stage of FIGS. 15A-15D. 
     FIGS. 17A and B are diagrams representing the initial and subsequent manner of energization of the skewed single pair of electromagnetic drive coils shown in FIGS. 4 and 5 to cause opposite or counter rotation of the adjacent impellers. 
     FIG. 17C is a diagram representation as in FIGS. 17A,  17 B indicating the formula parameters for calculating the angles between core leg sets associated with each impeller. 
     FIG. 18 is an end view of another form of the device according to the invention in which a ring is attached to the impeller blade tips. The ring is magnetized with adjacent segments having opposite polarities. 
     FIG. 18A is a lengthwise sectional view of the form of the device shown in FIG.  18 . 
     FIG. 19 is a partial longitudinal sectional view of another form of the device utilizing independently rotatable impellers and a set of intermediate stator blades. 
     FIG. 20 is a partial longitudinal sectional view of the form of the type of device shown in FIG. 19 but with the impellers fixed to a support shaft to rotate together. 
     FIGS. 21-23 are schematic circuit diagrams of respective parts of the control circuit used to energize the electromagnetic driver coils. 
     FIGS. 24 and 25 are block diagrams of a speed control circuit for each driver coil incorporated in the device according to the invention. 
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, certain specific terminology will be employed for the sake of clarity and a particular embodiment described in accordance with the requirements of 35 USC 112, but it is to be understood that the same is not intended to be limiting and should not be so construed in as much as the invention is capable of taking many forms and variations within the scope of the appended claims. 
     Referring to the drawings and particularly FIGS. 1 and 2, FIG. 1 shows basic arrangement of components of a fluid flow inducing device  10  which are similar to the device described in the aforementioned copending patent application cross referenced above. The device  10  includes a housing  12  having a fixed cylindrical shroud  14  defining an impeller enclosing structure providing a flow passage directing and receiving fluid flow to and from upstream and downstream conduits  18 . The shroud  14  fully isolates the electrical components described herein from the fluid flowing therein. Rotatably supported within the shroud  14  is a pair of axially aligned impellers  20 A and  20 B instead of the single rotor described in the cross referenced copending patent application. 
     Each impeller  20 A and  20 B is supported by a corresponding central hub  22 A,  22 B, respectively, of magnetically conducting material which is rotatably supported on an axial shaft  24  and bearing sets  26  and  28 . The axial shaft  24  in turn is supported by radial struts  30  of housing  12 . 
     Each impeller  20 A and  20 B includes sets of radial blades  42 A and  42 B and  44 A and  44 B, respectively, angled to induce fluid flow when the impellers are rotated. The impeller blades  42 A,  42 B and  44 A,  44 B are integrally formed with the respective hubs  22 A and  22 B in the construction shown in FIG.  2 . The material of these blades is selected so as to be magnetically conducting and also to be able to be permanently magnetized, preferably of a magnetic plastic material which is well known in the art. The permanent magnetization is such as to establish opposite magnetic poles as indicated at the radially inward most and the radially outermost end of each blade. The shroud  14  should be constructed of a nonmagnetic but magnetically permeable material such as a nonmagnetic plastic or stainless steel, although shroud holes  15  may alternatively be used (FIG.  1 A), or recesses  17  (FIG.  1 B). 
     Associated with each impeller  20 A and  20 B is a pair of electromagnetic driver coils  46 A and  46 B acting as a motor stator element. A respective pair of electromagnetic driver coils may be provided for each impeller, however, as shown in FIG. 4, a single pair of driver coils may be used to drive two impellers as will be described herein. Each driver coil  46 A and  46 B includes a horseshoe-shaped core  48 A and  48 B with coil windings  50 A and  50 B encircling the connecting segment joining ends of each of a pair of generally radial legs  52 A and  52 B. 
     The ends of the leg&#39;s  52 A,  52 B are closely spaced to the magnetized blade ends, i.e., {fraction (1/16)} to ¼ inches to provide a magnetic flux path through the blades and driver coil cores. 
     The circuitry (FIGS. 21-25) has generally similar components as the circuit described in the above cross-referenced copending patent application. As will be described hereinafter, these components include all sensors which establish trigger points  56  and  58  detecting when the edge of a respective impeller blade  42 A and  42 B rotates past that respective sensor point  56  and  58 . The drive circuitry A and B (see FIGS. 21-22) causes momentarily or pulsed energization of each electromagnetic drive coil  46 A and  46 B to alternately generate opposite magnetic field polarities when the windings  50 A or  50 B are energized with the electrical circuit  54  such as to provide driving impulses on the blades  42 A,  42 B,  44 A,  44 B tending to produce sustained rotation of the respective impellers  20 A and  20 B. This will be described below in further detail. 
     The impellers  20 A and  20 B are preferably independently rotatable and the control circuitry associated with each of the impellers  20 A or  20 B, according to one embodiment, is designed to produce an opposite rotation of each such that driving impellers  20 A or  20 B generates an increased static pressure. Each impeller  20 A,  20 B has its own associated circuit to cause the respective impellers  20 A,  20 B to rotate in opposite directions as will described hereinafter in further detail. 
     As mentioned in the above cross referenced copending patent application, each horseshoe-shaped core  48 A,  48 B of the driver coils  46 A,  46 B produces sufficient magnetic forces such that only a single coil  46  can be relied on if the flow requirements for the particular application can be produced adequately by the drive force of a single driver coil  46  (see FIG.  3 ). It is still necessary to orient the blades of the impeller  20  during a start up position to ensure that rotation in the proper direction will begin and will proceed. 
     To initiate operation, one impeller blade must be positioned between the core legs  52 . To do this, another blade is attracted to a start up coil  60  and aligned with the magnetic pole of that coil. 
     In FIG. 1, which represents a start up position, each of two blades  42 A,  42 B are naturally attracted to the respective core legs  52 B. The angle between the core legs  52 A,  52 B is set to be the same as the angle between successive blades to produce this condition. The spacing of the blades  42 A,  42 B and the angle between the coils  46 A,  46 B causes a blade  42 A to be positioned between the legs  52 A in the start up position. 
     FIG. 1C shows a 90° angle spacing C between the driver coils  46 A,  46 B. The angle C in degrees can be calculated using the formula: 
     
       
           C =180(2 k +1)/ N +360 f/N   
       
     
     where N is equal to the number of permanently magnetized blades, and k and f are any whole numbers. 
     Instead of two respective sets of driver coils  46 A,  46 B (FIG. 1) for each impeller  20 A,  20 B (FIG. 2) it may be advantageous to provide a single pair of electromagnetic driver coils  62 A,  62 B as shown in FIGS. 4,  5 ,  17 A,  17 B with cores  64 A,  64 B lying in planes, which are axially skewed to position each leg  66 A,  668 ,  68 A,  68 B, associated with respective impeller planes  70 A,  70 B, as indicated in FIG.  5 . The skewing of the driver coils  62 A,  62 B is required for producing reverse rotation as explained below. Thus, each electromagnetic driver coil  62 A,  62 B interacts with the magnetic fields produced by magnetized impeller blades  72 A,  72 B. This has an advantage, over the use of two separate pairs of driver coils, by rendering synchronization between the relative rotational rates of the impellers  70 A,  70 B much easier. A drive circuit is provided for each respective driver coil  62 A,  62 B. 
     One core leg from each driver coil  62 A,  62 B forms a respective set of core legs  66 A,  66 B and  68 A,  68 B each set associated with a respective impeller  70 A,  70 B. 
     FIGS. 4 and 17C show that the set  66 A,  66 B form an angle A in the impeller plane  70 A, while set  68 A,  68 B form an angle B in the impeller plane  70 B. These angles may be calculated with the formulas: 
     
       
           A =180/ N   
       
     
     
       
           B =3×180/ N   
       
     
     where N is the number of magnetized impeller blades. 
     FIGS. 6-9 show an alternative construction; in which instead of the impeller blade tips defining one pole of a permanent magnetic field there is an arcuate ring segment integral with each impeller blade. Blades  80 A,  80 B with the ring segments  78 A,  78 B defining one of the radially spaced magnetic poles created by magnetization of the blades and segment pieces together. 
     In order to simplify the magnetization process for permanently magnetizing the blade ring segment sections, the impellers  84  and  86  are preferably constructed in two different sections  109  and  110  as shown in FIGS. 8 and 9, respectively. The hub sections  112 ,  114  are notched to be able to be interleaved when assembling the sections  109 ,  110  together to form the complete impeller. It is easier to magnetize all portions of one section to be the same polarity, and accordingly the two-section construction is easier to manufacture. 
     The ring segments  78 A and  78 B are interfit after assembly such as to define a sealed cylindrical fluid containment passage  82 . A second impeller  86  axially spaced from the first impeller  84  also has arcuate ring&#39;s segments  90  integrally formed with each blade  92  which are magnetized with successively opposite polarities as in the first impeller  84 . At axially projecting edge portions  94  are attached nonmagnetic ring  96  such as to create a labyrinth seal to confine the fluid flow within the interior of the ring segments  78  and  90 . Likewise, an end lip  98  on each of the segments  90  closest to a housing sidewall  100  fits into a recess therein to create a labyrinth seal. 
     Thus, there is no stationary shroud as such in this form of construction. Pairs of mounting posts  102  and  104 , project axially from the end plate  100  to support the respective sets of driver coils  106  and  108 . 
     FIGS. 10-13 show an alternate construction in which impellers  116 ,  118  do not have the arcuate segments and are formed into sections shown in FIGS. 12 and 13 in which each of the fan blades  120  in one piece  122  are all polarized in the same orientation, i.e., the south poles at the blade tips and the north poles at the blade roots adjacent a tooth hub  124 . The blades  128  of another piece  126  are all of the opposite polarity with the north pole at the outer tip and the south pole at the root adjacent the tooth hub  130 , each hub segment  124 ,  130  are interfit to allow the blades  120  and  128  to be alternately disposed. 
     The bearings  132  and  134  are received within the composite hub formed by the segments  124 ,  130 , and disposed on the stepped support shaft  138  supported by struts  140  included in the housing  142 . 
     FIGS. 14A-14D show each stage of a basic operation of the device having a magnetic drive according to the present invention for impellers  20 A,  20 B rotating in the same direction. At start up, the driver coil  46 A has one of the impeller blades  42 A positioned between its core legs  52 A, B by a previous energization of the other coil  46 B causing successive blades  42 A,  42 B to line up with each core leg as shown. Sensor location  58  has been reached by an impeller blade  42 B having an opposite magnetic polarity to the blades  42 A. The components within the drive circuit, in response thereto, causes the driver coil  46 A to be momentarily energized with the circuit, establishing the magnetic polarity indicated, which causes the blade  42 A positioned between the legs of the coil  46 A to be attracted to the south pole and to be repelled by the north pole, both effects inducing a counterclockwise rotation of the impeller  20 A,  20 B. Coil  46 A is turned off immediately after the blade edge passes the sensor location. 
     After turnoff of coil  46 A, the impellers  20 A,  20 B coasts in the counter clockwise direction until, the second sensor, location  56  is reached by a leading edge of an impeller blade  42 A (FIG. 14B The control circuitry then causes the other driver coil  46 B to be energized in such a way as to establish the polarity indicated. At this point, a north impeller blade  42 A is positioned between the legs of the core and coil  46 B, and this again causes attraction with impeller blade  42 A, tending to continue the counterclockwise rotation of the impeller  20 A,  20 B. 
     The coil  46 B is deenergized and the impeller  20 A,  20 B continues to coast forward until the impeller blade  42 A reaches the second sensor location  58  (FIG.  14 C), which again triggers energization of the driver coil  46 A but with an opposite polarity. At this point, one of the south oriented blades  42 B is positioned between the legs of the driver coil  46 A causing attraction propulsion forces to be exerted on the impeller  20 A,  20 B, continuing a counterclockwise rotation of the impeller  20 A,  20 B. The coil  46 A is again deenergized (after the interval described), and the impeller  20 A,  20 B continues rotation until the blade,  42 B reaches the second sensor location  56  (FIG. 14D) which triggers reenergization of the other driver coil  46 B. At this point, another south orientated impeller blade  42 B is positioned between the legs of the driver coil  46 B, again setting up attraction repulsion magnetic forces tending to continue rotation of impellers  20 A, B in a counter clockwise direction. This is similar to the arrangement described in the copending application cross-referenced above, except that two impellers  20 A,  20 B are involved, and the circuit may be designed to produce different rates of rotation. 
     The frequency with which the blades  42 A,  42 B sweep past the sensor locations  56 ,  58  maybe monitored to measure rotational speed and to control the speed of each impeller  20 A,  20 B with appropriate additional circuitry. 
     FIGS. 15A-15D and  16 A- 16 D show the operating cycle for the respective impellers  20 A and  20 B for a counter rotating drive of each. FIGS. 15A,  15 D show an arrangement that is the same as that shown in FIGS. 14A-14D, thus producing counterclockwise rotation of impeller  20 A. 
     In FIGS. 16A-16D, the start up condition of the impeller  20 B has a south blade  42 B positioned between the legs of the driver coil  46 A and a north blade  42 A at a point triggering sensor  56  rather than the sensor  58 . The circuitry causes the driver coil  46 A to be energized with the polarity indicated upon a blade  42 A reaching the sensor location  56 . This causes initiation of a clockwise rotation of impeller  20 B by attraction-repulsion of the magnetic fields. 
     In FIG. 16B, the sensor location  58  is reached by the leading edge of an impeller blade  4213 , triggering energization of the driver coil  46 B with the magnetic polarity indicated, which is opposite the magnetic polarity of coil  46 A in FIG.  16 A. This acts on the magnetic field of the impeller blade  42 A positioned between the legs of the driver coil  46 B to continue to force the impeller  20 B to rotate clockwise, in the opposite direction from that of the other impeller  20 A. 
     FIG. 16C shows blade  42 B reaching the detector location  56  (coasting thereto after the prior turn off of the driver coil  46 B), the driver coil  46 A is then activated with an opposite polarity from when first activated, with a “north” blade  42 A positioned between the legs of the core. Attraction repulsion forces generated by the interacting magnetic fields continues to force the impeller  20 B in the clockwise rotation. The driver coil  46 A is then turned off (FIG. 16D) and the impeller  20 B continues to coast forward until an impeller blade  42 A reaches the first sensor location  58 . This causes the circuitry to energize the second driver coil  46 B with the magnetic fields indicated, which interacts with the magnetic field of the impeller blade  42 B to create repulsion attraction forces that continue clockwise rotation of the impeller  20 B. 
     Thus, the two impellers  20 A,  20 B rotate in opposite directions and enable the development of a desired static pressure without requiring complex mechanical drives. 
     FIGS. 17A and 17B illustrate the functioning of the skewed coil drivers  62 A,  62 B shown in FIGS. 4 and 5. One sensor A is located in the phase of impeller  70 A and a second sensor B in the plane of impeller  70 B. As one of the south oriented impeller blades  72 B reaches an “on” trigger point  120  of sensor A, the driver coil  62 A is energized with the polarity indicated. Simultaneously, a south impeller blade  72 B- 1  reaches a trigger sensor point  124  of sensor B, causing the driver coil  62 B to be energized. At this point, a south oriented impeller blade  72 B is between the legs of the drivers coil  62 A and  62 B attracted the north pole of the driver coil  62 A and repulsed by south pole of the driver coil  62 B urge to rotate in a left hand or counter clockwise direction of the impeller  70 A. At the same time, a south oriented blade  72 B- 1  of the impeller  70 B is between the legs of driver coils  62 A and  62 B repulsed the south pole of the driver coil  62 A and attracted by the north pole of the driver coil  62 , thereby being forced to rotate in a righthand direction or clockwise rotation of the impeller  70 B. 
     As the impeller blade  72 B reaches an “off’ sensor location  122  of sensor A, the driver coil  62 A is turned off. Similarly, as the impeller blade  72 B- 1  of the impeller  70 B reaches the second off location of sensor B simultaneously, the driver coil  62 B is de-energized. The impellers  70 A,  70 B continue to coast until the blades reach the location in FIG. 17B whereat the next trailing impeller blade  72 A- 1  reaches “on” location  124  of sensor B, causing energizing of the driver coil  62 B and an impeller blade  72 A of the impeller  70 A reaches the “on” location  120  of the sensor A which causes the energization driver coil  62 A in a reversed polarity from the previous cycle. 
     At this point, (see FIG. 17B) a north oriented impeller blade  72 A is between the legs of the drivers coil  62 A and  62 B. The impeller  70 A is attracted to the south pole of the driver coil  62 A and repulsed by the north pole of the driver coil  62 B, which forces impeller  70 A to rotate in a left hand or counter clockwise direction. At the same time, a north oriented blade  72 A- 1  of the impeller  70 B is between the legs of driver coils  62 A and  62 B. This impeller  70 B is repulsed by the north pole of the driver coil  62 A and attracted by the south pole of the driver coil  62 B, thereby being forced to rotate in a righthand direction or clockwise rotation. 
     FIGS. 18 and 18A show another form of an axial flow inducing magnetically driven device  130  according to the present invention in which a solid impeller  132  includes a hub  133 , blades  134  and ring  135 . Ring  135  is permanently magnetized in segments with alternating opposite polarities as shown. 
     An axial sealing labyrinth is established between ring  138  and ring  135 A. A similar sealing labyrinth is established between ring  135 A and housing  140 .The angulary spaced driver coils  142 A,  142 B, operated as in the first embodiment described above, are mounted to a housing  140  to be positioned radially outside the rings  135 ,  135 A. 
     FIG. 19 shows a device  144  which has two independently rotatable impellers  146 A,  146 B straddling a stator blade set  148  fixed in a housing  150 . FIG. 20 shows a device  152  which has two impellers  154 A,  154 B having hubs  158 A,  158 B fixed to shaft  156  to rotate together. A set of stator blades  160  is mounted between impellers  154 A,  154 B. 
     The electrical control, is shown in FIGS. 21-23 showing drive circuit A for one driver coil, drive circuit B for the second driver coil, and a power supply circuit, respectively. 
     The power supply circuit receives 115 volts ac from a standard grounded electrical power cord. This voltage is rectified by D 11  and filtered by C 1 , C 2  and C 3 . The current is limited by R 27  to approximately 8 amperes and protected by F 1 , a 1.5 amp slow blow fuse. This rectified voltage, measured from V+ to V−, is applied to the drive cards and measures approximately 160 volts do under nominal load. R 28  and R 29  in conjunction with D 12  provide 20 volts do used to power the Hall Effect IC&#39;s on both drive circuits. C 4  and C 5  provide filtering for this 20 volt @ 20 milliamp power source. 
     Drive circuits A and B are identical and electrically function the same with the exception of the location of their respective sensors and driver coils. Drive circuit A will be used to describe the operation of the drive electronics. 
     As can be determined by reviewing drive circuit A, the components in each circuit includes a pair of uni-polar Hall effect IC&#39;s, U 5  and U 6 , of a commercially available type. The IC&#39;s are mounted in close proximity to one another, and comprise a sensor assembly. Each sensor is placed at a precise position and is energized by the leading edge of each blade. The duration of how long the sensor stays energized is determined by the rotor speed and blade tip exposure. When one of the impeller blades having an outer south pole aligns with the sensor, U 5  conducts supplying a ground to pin #3. This in turn causes U 2  and U 3  to energize allowing their outputs to conduct. U 2  applies a voltage potential to the gate of Q 1  through the voltage divider formed by R 3  and R 4 . This applied voltage potential-is approximately 140 volts do referenced to V−. At the same time U 3  applies a voltage potential to the gate of Q 4  through the voltage divider formed by R 11  and R 12 . 
     This applied voltage potential is approximately 20 volts do referenced to V−. Q 1  and Q 4  are powered on and a high current conduction path is established from the V+ supply through Q 1 , L 1 , L 2  and Q 4  to ground. L 1  and L 2  are now energized to create a magnetic field causing the rotor to rotate. 
     When one of the impeller blades having an outer north pole aligns with the sensor, U 6  conducts supplying a ground to pin #3. This in turn causes U 1  and U 4  to energize and allowing their outputs to conduct. U 1  applies a voltage potential to the gate of Q 2  through the voltage divider formed by R 5  and R 6 . This applied voltage potential is approximately 20 volts do referenced to V−. At the same time U 4  applies a voltage potential to the gate of Q 3  through the voltage divider formed by R 9  and R 10 . This applied voltage potential is approximately 140 volts do referenced to V−. Q 2  and Q 3  are powered on, and a high current conduction path is established, from the V+ supply through Q 3 , L 2 , L 1  and Q 2  to ground. L 1  and L 2  are now energized and create a magnetic field of opposite polarity as when U 5  conducted. 
     Resistors R 2 , R 7 , R 8  and R 13  are used only for biasing off the transistor outputs on U 1  through U 4 . The fast recovery rectifiers D 2  through D 5  clamp the transient voltages generated by L 1  and L 2  and prevent the reverse conduction of Mosfets Q 1  trough Q 4 . 
     The following table lists details of the electrical components used in these circuits: 
     
       
         
               
             
               
               
               
               
             
           
               
                   
               
               
                 Electrical Component List 
               
               
                 Multi-Stage axial Bladed Machine 
               
             
          
           
               
                   
                   
                   
                 Component 
               
               
                 Component 
                   
                 Component 
                 Part 
               
               
                 Designator 
                 Component Type 
                 Manufacturer 
                 Number 
               
               
                   
               
               
                 D1 
                 Zener Diodes 
                 Liteon Power 
                 1N4727 
               
               
                   
                   
                 Semiconductor 
               
               
                 D2-D5 
                 Fast Recovery Rectifiers 
                 Liteon Power 
                 1N4936 
               
               
                   
                   
                 Semiconductor 
               
               
                 U1-U4 
                 Optoisolators 
                 QT 
                 H11D2Z 
               
               
                   
                   
                 Optoelectronics 
               
               
                 U5, U6 
                 Hall Effect Sensor IC&#39;s 
                 Micronas 
                 HAL508UA 
               
               
                 Q1, Q3 
                 P-Channel Mosfets 
                 International 
                 IRF9640 
               
               
                   
                   
                 Rectifier Corp. 
               
               
                 Q2, Q4 
                 N-Channel Mosfets 
                 International 
                 IRF640 
               
               
                   
                   
                 Rectifier Corp. 
               
               
                 R1 
                 15 K, 3 Watt Power 
                 NTE Elec- 
                 N/A 
               
               
                   
                 Resistor 
                 tronics, Inc. 
               
               
                 R2, R7, 
                 470 K, ½ Watt Resistor 
                 N/A 
                 N/A 
               
               
                 R8, R13 
                   
               
               
                 R3, R6, 
                 15 K, ½ Watt Resistor 
                 N/A 
                 N/A 
               
               
                 R9, R12 
                   
               
               
                 R4, R5, 
                 100 K, ½ Watt Resistor 
                 N/A 
                 N/A 
               
               
                 R10, R11 
                   
               
               
                 L1, L2 
                 Field Coils Air Concepts, 
                 N/A 
                 N/A 
               
               
                   
                 Inc. 
               
               
                 D6 
                 Zener Diodes 
                 Liteon Power 
                 1N4747 
               
               
                   
                   
                 Semiconductor 
               
               
                 D7-D10 
                 Fast Recovery Rectifiers 
                 Liteon Power 
                 1N4936 
               
               
                   
                   
                 Semiconductor 
               
               
                 U7-U10 
                 Optoisolators 
                 QT 
                 H11D2Z 
               
               
                   
                   
                 Optoelectronics 
               
               
                 U11, U12 
                 Hall Effect Sensor IC&#39;s 
                 Micronas 
                 HAL508UA 
               
               
                 Q5, Q7 
                 P-Channel Mosfets 
                 International 
                 IRF9640 
               
               
                   
                   
                 Rectifier Corp. 
               
               
                 Q6, Q8 
                 N-Channel Mosfets 
                 International 
                 IRF640 
               
               
                   
                   
                 Rectifier Corp. 
               
               
                 R14 
                 15 K 3 Watt Power Resistor 
                 NTE Elec- 
                 N/A 
               
               
                   
                   
                 tronics, Inc. 
               
               
                 R15, R20, 
                 470 K, ½ 2-Watt Resistor 
                 N/A 
                 N/A 
               
               
                 R21, R26 
                   
               
               
                 R16, R19, 
                 15 K, ½ Z Watt Resistor 
                 N/A 
                 N/A 
               
               
                 R22, R25 
                   
               
               
                 R17, R18, 
                 100 K, ½ Watt Resistor 
                 N/A 
                 N/A 
               
               
                 R23, R24 
                   
               
               
                 L3, L4 
                 Field Coils 
                 Air Concepts, 
                 N/A 
               
               
                   
                   
                 Inc. 
               
               
                 R27 
                 15 Ohm, 10 Watt Resistor 
                 Xicon/Arcol 
                 N/A 
               
               
                 R28, R29 
                 15 K 3 Watt Power Resistor 
                 NTE Elec- 
                 N/A 
               
               
                   
                   
                 tronics, Inc. 
               
               
                 F1 
                 1% 2 Amp Slow Blow 
                 Littlefuse 
                 313 Series 
               
               
                   
                   
                   
                 1.5 Amps 
               
               
                 D11 
                 6 Amp, Bridge Rectifier 
                 Liteon Power 
                 PB64 
               
               
                   
                   
                 Semiconductor 
               
               
                 D12 
                 Zener Diode 
                 Liteon Power 
                 1N4747 
               
               
                   
                   
                 Semiconductor 
               
               
                 C1-C3 
                 68 UF, 200 Volt Capacitors 
                 Panasonic 
                 E E U- 
               
               
                   
                   
                   
                 EB2D680S 
               
               
                 C4 
                 .047 UF, 100 Volt 
                 Panasonic 
                 E Q U- 
               
               
                   
                 Capacitor 
                   
                 V 1473JM 
               
               
                 C5 
                 50 UF, 50 Volt Capacitor 
               
               
                   
               
             
          
         
       
     
     In the above-described circuits, the Hall effect sensors are energized only while the blades are passing by each sensor. 
     Also, a speed control circuit could utilize the sensor signals to maintain a desired rate of rotation of the impellers. Such speed control circuits are shown in the block diagrams of FIGS. 24 and 25 for the respective circuits A and B of FIGS. 21 and 22. 
     This speed control operates directly from the power supplied to sensors U 5 , U 6  and U 11 , U 12  from drive circuits A and B, respectively. The speed control is spliced in the line going to the sensors. The only item common to the two speed controls is the RPM command signal. This command signal is a voltage generated by a potentiometer, which represents a motor speed setting. FIG. 24 shows the RPM command signal originating in control circuit A and feeding to control circuit B. It may also be located in control circuit B and feed to control circuit A. 
     The speed control diagrams of FIGS. 24 and 25 are identical and electrically function the same with the exception that they each are associated with their respecting sensors and drive circuits. FIG. 24 will be used to describe the operation of the speed control. During start up or loading, sensor assembly U 5 , U 6  operates switch #1 and #2 directly without modulation. This is done via a high state control signal in conjunction with the U 5 , and U 6  sensor signal to switch #1 and #2, respectively. As the motor rotates, the U 5 , and U 6  sensor signals are combined with a two input OR gate. This is done so both polarity blades are generating pulses to the FN converter (frequency X 2 ) which will allow for tighter speed control. The FN converter processes the U 5 , and U 6  sensor signal to a DC voltage representative of the frequency. As the frequency increases (motor RPM increases) the DC voltage increases in a linear fashion. This voltage is the speed signal, which will be filtered and used to control the motor speed. The speed signal is filtered by RC networks in the Filter and Processor block. After filtering, this signal is processed by a differential, integral, and proportional gain amplifier to monitor and control its rate of change. The signal is then summed with the RPM command signal in this amplifier to generate an error signal. This error signal is approximately 2.5 volts when the RPM command signal and RPM of the motor are the same. If the motor speed increases above the RPM command signal the error signal voltage decreases and increases if the motor speed decreases. This error signal is used to control the pulse width modulator, which modulates switch #1, or #2 if its sensor signal is a low state. The processed sensor signal, that is generated, is sent to drive circuit A (FIG.  21 ).