Patent Publication Number: US-2019178255-A1

Title: Vapor cycle compressor with variable inlet/outlet geometry

Description:
BACKGROUND OF THE INVENTION 
     The present invention generally relates to vapor cycle compressors and, more particularly, to apparatus and methods of widening the operational envelope of flows in centrifugal compressors. 
     In a centrifugal refrigerant compressor, gas enters the compressor through a fixed inlet nozzle that directs the flow into a centrifugal impeller in such a way that the flow is uniformly distributed at a desired velocity. The flow then travels through stationary components adjacent to the impeller inlet designed to deliver the flow to the impeller with minimal pressure drop. The impellers force the gas refrigerant to spin faster and faster. The flow then leaves the impeller and typically flows through a stationary diffuser causing it to decelerate. These stationary diffusers are actually static guide vanes where energy transformation takes place, where part of velocity head turns to a pressure head. This reduction in velocity causes the pressure to rise leading to a compressed fluid. 
     Typical centrifugal vapor cycle compressors have a narrow operational envelope due to fixed vanes within the inlet and the diffuser. These vanes define the operational envelope of the compressor which includes the pressure ratio and the mass flow rates that are achievable. This narrow envelope provides challenges and limitations when designing an aircraft vapor cycle refrigerant system because the compressor must operate at both design and off-design conditions. 
     As can be seen, there is a need for improved apparatus and methods to increase the operational envelope in a centrifugal compressor. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention, a vapor cycle compressor comprises a controller section; a drive section in communication with the controller section; and a compression section operatively engaged with the drive section, wherein the compression section includes: an inlet guide vane assembly; wherein the inlet guide vane assembly includes inlet vanes that are configured to adjust their angle of orientation; a first stage diffuser assembly downstream of the inlet guide vane assembly; wherein the first stage diffuser assembly includes first diffuser vanes that are configured to adjust their angle of orientation; a return channel assembly downstream of the first stage diffuser assembly; wherein the return channel assembly includes return channel vanes that are configured to adjust their angle of orientation; a second stage diffuser assembly downstream of the return channel assembly; wherein the second stage diffuser assembly includes second diffuser vanes that are configured to adjust their angle of orientation. 
     In another aspect of the present invention, a vapor cycle compressor comprises a controller section; a drive section in communication with the controller section; wherein the drive section includes a plurality of stepper motors; and a compression section operatively engaged with the drive section, wherein the compression section includes: an inlet guide vane assembly operatively engaged with a first stepper motor; a first stage diffuser assembly downstream of the inlet guide vane assembly and operatively engaged with a second stepper motor; a return channel assembly downstream of the first stage diffuser assembly and operatively engaged with a third stepper motor; a second stage diffuser assembly downstream of the return channel assembly and operatively engaged with a fourth stepper motor. 
     In a further aspect of the present invention, a vapor cycle compressor comprises a controller section; a drive section in communication with the controller section; and a hermetically sealed compression section operatively engaged with the drive section, wherein the compression section includes: an inlet guide vane assembly; a first stage diffuser assembly downstream of the inlet guide vane assembly; a return channel assembly downstream of the first stage diffuser assembly; a second stage diffuser assembly downstream of the return channel assembly; wherein the inlet guide vane assembly, the first stage diffuser assembly, the return channel assembly, and the second stage diffuser assembly each have a respective set of vanes; wherein each respective set of vanes is configured with a respective orientation angle that can be varied independently of one another. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of an exterior of a vapor cycle compressor according to an embodiment of the present invention. 
         FIG. 1B  is a perspective view of an interior of the vapor cycle compressor of  FIG. 1A . 
         FIG. 2  is a partial, cross-sectional schematic view of a vapor cycle compressor according to an embodiment of the present invention. 
         FIG. 3A  is a perspective view of a compression section of a vapor cycle compressor according to an embodiment of the present invention. 
         FIG. 3B  is a cross sectional view of the compression section of  FIG. 3A . 
         FIGS. 4A-4B  are perspective views of an inlet guide vane assembly of a vapor cycle compressor according to an embodiment of the present invention. 
         FIGS. 5A-5B  are perspective view of a variable vane assembly of a vapor cycle compressor according to an embodiment of the present invention. 
         FIG. 6  is a cross sectional view of a variable vane assembly operatively engaged with a stepper motor assembly according to an embodiment of the present invention. 
         FIG. 7  is a perspective view of a first stage impeller assembly of a vapor cycle compressor according to an embodiment of the present invention. 
         FIG. 8  is a perspective view of a second stage impeller assembly of a vapor cycle compressor according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
     Various inventive features are described below that can each be used independently of one another or in combination with other features. However, any single inventive feature may not address any of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below. 
     Broadly, the present invention provides a vapor cycle compressor that allows angle variation of one or more of inlet guide vanes, return channel vanes, and diffuser vanes. That can provide a wider operational envelope, an improvement in the coefficient of performance, and the ability to use different refrigerants in the compressor without changing the design. This invention allows independent variability of the inlet and outlet geometries within a centrifugal refrigerant compressor, a hermetically sealed drive mechanism, redundancy for the drive mechanism, control logic that adjusts the vanes based on performance requirements, and a compact light weight mechanism. 
     Generally, in the present invention, a compression section is arranged with the impellers front-to-back, with an internal crossover between stages to minimize overall compressor size and weight. Variable inlet guide vanes in conjunction with variable diffuser vanes are utilized in both the first and second stages. Each variable vane mechanism is driven by redundant stepper motors connected to a common shaft. The common shaft contains a worm that drives a geared section of a unison ring. The unison ring, in turn, rotates the vanes in one direction or an opposite direction. 
     Although described in the exemplary context of an aircraft, the present invention can be used in other environments. 
     In  FIG. 1A , an exemplary vapor cycle compressor  100  can be affixed to a support via mountings  107 . The compressor  100  may include a drive section  101 , a compression section  102  operatively engaged with the drive section  101 , a controller section  120  in communication with the drive section  101 , and a motor section  121  operatively engaged with the compressor section  102 . The controller section  120  and the motor section  121  may be hermetically sealed in a cover/housing  103 . 
     In embodiments, the drive section  101  may include a stepper motor assembly  105  that can be hermetically sealed. The stepper motor assembly  105  may include a plurality of stepper motor subassemblies  105   a . One or more of the subassemblies  105   a  may include a stepper motor connector  105   b  and a stepper motor housing  105   c . The stepper motor connector  105   b  may connect to power from a separate or internally derived source. One or more of the stepper motor subassemblies  105   a  may further include a stepper motor, a worm, a worm shaft, and a worm gear, as described below. 
     The compression section  102 , according to embodiments, may include an inlet subsection  102   a  and an impeller/diffuser subsection  102   b . The inlet subsection  102   a  may include a compressor inlet  104  configured to receive a vapor refrigerant. The inlet subsection  102   a  may further include an inlet guide vane assembly described below. 
     The impeller/diffuser subsection  102   b , in embodiments, may include an upstream first stage impeller assembly, a downstream first stage diffuser assembly, a downstream return channel assembly, a downstream second stage impeller assembly, and a downstream second stage diffuser assembly described below. The impeller/diffuser subsection  102   b  may also include a sub-cooling inlet  106  that is configured to increase cooling performance and extend compressor flow range. 
     In  FIG. 1B , according to embodiments, the controller section  120  of the compressor  100  may include a digital signal processor  113  that is configured to provide localized compressor torque and speed control which includes stepper motor function, and a high power switch module  116  that is configured to provide control of the main electric motor  121 . A current sensor transducer  112  can be configured to measure power into the motor section  121 , a motor bus bar  114  can be configured to distribute current, and a stud seal terminal  115  can be configured to pass electric current from the exterior of the compressor to the interior of the compressor. A capacitor  118  can be configured to maintain constant controller DC link voltage, capacitor bus bar  117  can be configured to supply or distribute link voltage, and a power input terminal  119  can be configured to receive power to the compressor. 
     In  FIG. 2 , according to embodiments, a vapor cycle compressor  200  may include a drive section  201 , a compression section  202 , a motor section  221 , and a controller section (not shown), all of which can be similar to that described in relation to  FIGS. 1A-1B . Accordingly, reference numbers in  FIG. 2  correspond to like reference numbers in  FIGS. 1A-1B . 
     The drive section  201  may, in embodiments, include a stepper motor assembly  205  which may be operatively engaged with an inlet guide vane assembly  225 , a first stage impeller assembly  226 , a first stage diffuser assembly  228 , a return channel assembly  229 , and a second stage diffuser assembly  232 , all of which can be part of the compression section  202 . 
     The stepper motor assembly  205  may include a plurality of stepper motors  205   e . Each stepper motor  205   e  may be paired with and be operatively engaged to each of the inlet guide vane assembly  225 , the first stage diffuser assembly  228 , the second stage diffuser assembly  232 , and the return channel assembly  229 . 
     Still referring to  FIG. 2 , the motor section  201  may, in embodiments, include a motor  221   a  that can have a stator  221   b  and a rotor  221   c . A tie rod  224  may extend from within the motor  221   a , through a thrust bearing disk  230 , and into the compression section  202 . Thereby, the motor section  201  may drive the first stage and second stage impeller assemblies  226 ,  227  of the compression section  202 . In so doing, a vapor refrigerant may be compressed while flowing in a vapor refrigerant path  231  through the inlet guide vane assembly  225 , then through the first stage impeller assembly  226 , then through the first stage diffuser assembly  228 , then through the return channel assembly  229 , then through the second stage impeller assembly  227 , and then through the second stage diffuser assembly  232 . 
     In  FIGS. 3A-3B , a compression section  302  and a stepper motor assembly  305 , according to embodiments, are shown. The compression section  302  may be similar to that described in relation to  FIGS. 1A-1B and 2 . Accordingly, reference numbers in  FIGS. 3A-3B  correspond to like reference numbers in  FIGS. 1A-1B and 2 . 
     The compression section  302  may include a compressor inlet  304  that can direct a vapor refrigerant into an inlet guide vane assembly  325 . From there, vapor refrigerant may be compressed in two stages. A first compression stage may include a first stage impeller assembly  326  directly downstream of the inlet guide vane assembly  325 . A first stage diffuser assembly  328  may be directly downstream of the first stage impeller assembly  326 . 
     The first compression stage and the inlet guide vane assembly  325  may be within a housing  338 . The housing  338  may further enclose the stepper motor assembly  305  to provide hermetic sealing of the compression section  302  and the stepper motor assembly  305 . 
     In embodiments, the compression section  302  may include a return channel assembly  329  (having a return channel guide vane  329   a ), directly downstream of the first stage diffuser assembly  328 , and that may direct vapor refrigerant from the first compression stage and into the second compression stage. The second compression stage may include a second stage impeller assembly  327  directly downstream of the return channel assembly  329 . A second stage diffuser assembly  332  may be directly downstream of the second stage impeller assembly  327 . The second stage compression may be within a housing  337  for hermetic sealing. 
     In the compression section  302 , according to embodiments, an inlet  306  may provide vapor refrigerant to an inlet scroll  333  that can be configured to provide additional flow to the second stage, while an outlet scroll  334  may be configured to direct vapor refrigerant out of the second compression stage, via an outlet  336 . The inlet and outlet scrolls  333 ,  334  may be within the housing  337 . A housing  335  may enclose a thrust disk  330 . 
     Still referring to  FIGS. 3A-3B , the stepper motor assembly  305  may be similar to that described in relation to  FIGS. 1A-1B and 2 . Accordingly, reference numbers in  FIGS. 3A-3B  correspond to like reference numbers in  FIGS. 1A-1B and 2 . 
     According to embodiments, the stepper motor assembly  305  may include a plurality of stepper motor subassemblies, each of which may include a stepper motor  305   e  that can each drive a worm shaft  305   f . In turn, the worm shaft  305   f  may rotate a worm  305   d  which, in turn, can rotate a worm gear  305   g . A respective stepper motor subassembly, and specifically a respective worm gear  305   g , may be operatively engaged to the inlet guide vane assembly  325 , the first stage diffuser assembly  328 , the return channel assembly  329 , and the second stage diffuser assembly  332  as described below. 
       FIGS. 4A-4B  depict an exemplary inlet guide vane assembly  425 . The inlet guide vane assembly  425  may be similar to that described in relation to  FIGS. 2 and 3A-3B . Accordingly, reference numbers in  FIGS. 4A-4B  correspond to like reference numbers in  FIGS. 2 and 3A-3B . 
     According to embodiments, the inlet guide vane assembly  425  may be configured to receive a vapor refrigerant flow  431  which can pass through a plurality of upstream, non-variable inlet support struts  425   e . The refrigerant flow  431  may then move to and through a plurality or set of downstream variable inlet vanes  425   a.    
     The set of inlet vanes  425   a , and each individual inlet vane  425   a  in such set, can be characterized by an angle of orientation. The angle of orientation may be measured by an angle about which each inlet vane may rotate around an axis of rotation. The axis of rotation may be substantially perpendicular to a longitudinally extending sleeve  425   f  that may receive a tie rod, such as tie rod  224 . As described below, the angle of orientation may be adjusted clockwise and counterclockwise. 
     In embodiments, the inlet guide vane assembly  425  may include an inlet housing  425   d  that can enclose the inlet vanes  425   a  and the inlet support struts  425   e . A face gear  425   b  may extend around the entire circumference of the inlet housing  425   d . The face gear  425   b  may support one or more worm gears  405   g . One or more sector gears  425   c  may be spaced around the entire circumference of the inlet housing  425   d . Also, one or more of the sector gears  425   c  may be operatively engaged to the face gear  425   b . As further described below, movement of the worm gear  405   g  can cause a variation of the angle of rotation of the inlet vanes  425   a.    
       FIGS. 5A-5B  depict an exemplary first stage diffuser assembly  528 . The first stage diffuser assembly  528  may be similar to that described in relation to  FIGS. 2 and 3A-3B . Accordingly, reference numbers in  FIGS. 5A-5B  correspond to like reference numbers in  FIGS. 2 and 3A-3B . 
     According to embodiments, the first stage diffuser assembly  528  may be configured to receive a vapor refrigerant flow  531 , which can be, for example, from a first stage impeller assembly (not shown). The first stage diffuser assembly  528  may include a plurality or set of downstream variable diffuser vanes  528   a  that receives the refrigerant flow  531 . 
     The set of diffuser vanes  528   a , and each individual diffuser vane  528   a  in such set, can be characterized by an angle of orientation. The angle of orientation may be measured by an angle about which each diffuser vane may rotate around an axis of rotation. The axis of rotation may be substantially parallel to a longitudinally extending tie rod, such as tie rod  224 , which can extend through an aperture  528   g . As described below, the angle of orientation may be adjusted or varied. 
     In embodiments, the first stage diffuser assembly  528  may further include a diffuser plate  528   b  that can support on one planar side thereof, via connectors  528   c , the diffuser vanes  528   a . On an opposed planar side of the diffuser assembly  528 , a unison ring  528   d  may be operatively engaged to one or more driver arms  528   e . The unison ring  528   d  may also be operatively engaged to one or more worm gears  505   g . One or more rollers  528   f  may rotatably support the unison ring  528   d  at an inner circumference thereof. 
     Although  FIGS. 5A-5B  depict an exemplary first stage diffuser assembly, it should be understood that similar components and the assembly thereof can also be used for one or both of the return channel assembly and the second stage diffuser assembly, such as that depicted in  FIGS. 2 and 3A-3B . 
       FIG. 6  depicts an exemplary stepper motor assembly  605  operatively engaged to a plurality or set of variable vanes, such as those that may be included in one or more of the first stage diffuser assembly, the second stage diffuser assembly, and the return channel assembly, as described above with regard to  FIGS. 2, 3A-3B, and 5A-5B . 
     The stepper motor assembly  605  may include one or more stepper motor subassemblies  605   a . One or more of the stepper motor subassemblies  605   a  may include one or a pair of redundant stepper motors  605   d  connected by a worm shaft  605   f  there between. Accordingly, if one of the paired stepper motors  605   d  fails, the other of the paired motors may be used. A stepper motor connector  605   b  may be provided at each stepper motor  605   d  to provide power. 
     In embodiments, one or more of the stepper motor subassemblies  605   a  may include at least one worm  605   e  that is operatively engaged to at least one worm gear  605   g  which, in turn, can be operatively engaged to the set of variable vanes (not shown). 
     The variable vanes can be supported by a plate  628   b . The plate  628   b  may support one or more driver arms  628   e  that can be operatively engaged, via one or more connectors  628   c , to one or more of the variable vanes. Also, one or more of the driver arms  628   e  may be operatively engaged to a unison ring  628   d . One or more rollers  628   f  may support the ring  628   d.    
     In operation, a single stepper motor  605   d , or one of the paired stepper motors  605   d , may rotate the worm shaft  605   f . In turn, the worm  605   e  may rotate, which can cause the worm gear  605   g  to rotate. The rotation of the worm gear  605   g  causes the unison ring  628   d  to rotate. In turn, one or more of the driver arms  628   e  can rotate. Via the connector  628   c  associated with the rotating arms  628   e , one or more of the vanes rotate about a longitudinal axis of the connector  628   c.    
     The use of paired stepper motors can also be employed in rotating inlet vanes of an inlet guide vane assembly, such as that depicted in  FIGS. 4A-4B . One of the paired stepper motors can—via a worm shaft, worm, and worm gear  405   g —rotate the face gear  425   b . In turn, one or more sector gears  425   c  can rotate. Via one or more connectors  425   g , which are operatively engaged to one or more inlet vanes  425   a , one or more of the inlet vanes  425   a  can rotate about a longitudinal axis of the connector  425   g.    
     It can be appreciated that the stepper motor assembly, upon control from the controller section, can rotate one or more of the sets of variable vanes of the inlet guide vane assembly, the first stage diffuser assembly, the return channel assembly, and the second stage diffuser assembly. 
       FIG. 7  depicts an exemplary first stage impeller assembly  726  which may contain a plurality of blades  726   a  enclosed in a housing  726   c . In this exemplary embodiment, the blades cannot be varied in their angle of orientation. 
       FIG. 8  depicts an exemplary second stage impeller assembly  827  which may contain a plurality of blades  827   a  enclosed in a housing  827   c . A cooling inlet  827   d  and a cooling outlet  827   e  may be provided. In this exemplary embodiment, the blades cannot be varied in their angle of orientation. 
     It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.