Abstract:
A scroll type device for operating on a fluid provided thereto that includes, as a unit, a housing with two interleaved scroll plates that are installed within such housing and that are operably movable relative to one another in an eccentric orbit, with such scroll plates including interleaved spiral projections, spiral projections include first and second portions, which portions will operate for expansion and the other of which portion will operate for compression as the unit operates in a given normal direction of movement.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This non-provisional patent application claims priority to the provisional patent application having Ser. No. 61/574,771, filed on Aug. 9, 2011. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to scroll type devices and to a novel design therefore that incorporates into a single scroll type unit both compressor and expander functions for use as the unit operates in a given normal direction of operation, with both the compressor and expander functions being effected by the eccentric orbiting of the same pair of scroll plates relative to one another. 
       BACKGROUND OF THE INVENTION 
       [0003]    Over the years compressors and expanders of many and various types have been found to have many uses, including for heat transfer purposes, and compressors and expanders of various types and designs have been developed for use therein or therewith. 
         [0004]    In more recent years, the use of scroll type compressors has become common. Such scroll type compressors typically employ two interleaving scrolls that often, but not exclusively, employ involute vane geometries to pump, compress, or pressurize the fluids, such as liquids or gases, with such liquids or gases typically being introduced into the scroll type device through an inlet or input port and discharged through a discharge port. 
         [0005]    Often, one of the scrolls is held fixed while the other scroll orbits eccentrically, without rotating, to trap and pump or compress pockets of fluid between the scrolls, although other techniques for effecting suitable relative motion between the scrolls for such result can also be utilized, including co-rotating the scrolls, in synchronous motion. 
         [0006]    Such scroll type devices generally tend to be compact and to operate more smoothly, quietly, and reliably than previous types of compressors. 
         [0007]    Typically, such scroll compressors are designed and intended to operate during normal operation in one direction, herein generally referred to as the normal or forward direction, in order to function properly within the systems where they are employed. With some of such scroll compressors, some limited reverse operation, although generally considered undesirable, may be permitted or tolerated, such as to mitigate flooded operation of the compressor at start up, but the overall operation is as a compressor operating in a forward direction. When so operated, such devices effect compression of the fluids introduced thereinto. One common use of such scroll compressors has been in air conditioning systems, whether for heating or cooling. 
         [0008]    Some other scroll type devices of a somewhat similar design, though with different connected porting, and with a differently configured involute or with a similar involute configured to eccentrically orbit differently than as a scroll compressor, have more recently been developed, with such devices intended, when properly configured and ported in a system, to serve an expansion function instead of a compression function. At least some of such scroll type devices typically employ scroll plates highly similar to the scroll plates of the previously referenced scroll compressors, with generally like interleaved involute wraps thereon, but such scroll type devices are designed to be normally operable in a direction that is the reverse direction from that of such previously referenced scroll compressors. Such scroll type devices are sometimes referred to as scroll expanders. One use of such scroll expanders has been for standby and Uninterruptible Power (UPS) applications wherein a compressed air battery uses air to drive a scroll expander which in turn drives a conventional generator to produce electricity. 
         [0009]    In the past, such single stage scroll type devices, with their single pair of scroll plates, whether intended to effect a compression or an expansion function, have generally been designed or intended to be normally operable in only one direction within the systems in which they are employed, and to function during their normal operation as either a scroll compressor or a scroll expander, and not as both a scroll compressor and scroll expander. 
         [0010]    In general, scroll type compressors have been limited to a single stage of compression due to the complexity and difficulties associated with two or more stages. However, some recent scroll type devices have been designed to include multiple stages, some with multiple pairs of interacting scroll plates, to achieve more desirable performance and results. Some more recent scroll type compressors, such as those disclosed in U.S. Pat. Nos. 6,050,792 and 6,439,864, include multiple stages, with appropriate associated fluid ports, within a single scroll type compressor. Such scroll type devices are not operable to effect both compression and expansion functions by the operation of a single pair of scroll plates in a normal direction, however, and some require multiple pairs of scroll plates to realize the multiple stages. 
         [0011]    Another recent scroll type device of interest is the invention, by the inventor of the present invention, disclosed in U.S. patent application Ser. No. 13/066,261. That invention is a scroll type construction that employs a plurality of fixed and orbiting scrolls arranged to operate as a three stage vacuum pump wherein the first stage acts upon working fluid provided at an inlet as a compressor, the second stage acts upon working fluid from the first stage as an expander, and the third stage acts upon working fluid from the second stage as a compressor, all as the scroll type device operates in a normal forward direction. While such scroll type device effects both compression and expansion within the single, multi-stage unit, wherein the compression and expansion operations are part of a single, desired operation, with the output of one stage feeding the input of the succeeding stage, the overall effect of such unit&#39;s operation is that of a vacuum pump. Moreover, such multi-stage operations require multiple fixed and orbiting scrolls in order to affect the staged, linear expansion and compression functions realizable therewith; both compression and expansion functions are not realizable in any single stage of the unit from the use of a single pair of scroll plates. 
         [0012]    Consequently, even though the construction of U.S. patent application Ser. No. 13/066,261 has been designed to incorporate within a single scroll type device both compression and expansion functions, such functions have formed constituent parts of an overall compression operation, and the compression and expansion functions have not been available for separate and/or independent use and, in any event, are not effected by the normal operation of a single pair of scroll plates in a forward direction. In order to realize the staged compression and expansion functions of such construction, multiple pairs of scroll plates are required to be configured in particular manners. Consequently, even with such construction, realization of both compression and expansion functions from a single pair of scroll plates in a single scroll type device has not been possible. 
         [0013]    Against such backdrop, it has also been recognized for many years that many waste heat energy sources, such as solar, engine exhaust, geothermal, and other sources that employ processes where the waste heat is exhausted to the atmosphere, currently exist, and that it would be advantageous and desirable if the energy in such waste heat sources could be recovered for beneficial uses, including for air conditioning purposes. Effective realization of such an objective has remained problematic, however. 
         [0014]    It has been recognized by the inventors of the invention hereinafter described that, in order to capture and advantageously make use of the waste heat of such previously noted energy sources, particularly for air conditioning purposes, an expander can be utilized in an Organic Rankine Cycle (ORC) to generate power, and that the power from the Organic Rankine Cycle expander can then be used to power a compressor for a traditional vapor compression cycle for air conditioning, either heating or cooling. It has been further observed, however, that it is inefficient and costly to have to utilize separate expanders and compressors for such purpose. 
         [0015]    To address such desires and the shortcomings and limitations associated with having to employ separate expanders and compressors, a novel scroll type device including compressor and expander functions through the use of a single pair of scroll plates in a single unit has therefore been developed. 
       SUMMARY OF THE INVENTION 
       [0016]    The present invention offers a significant advance over prior art constructions in that it is a scroll type construction or unit of a unique design that realizes both compression and expansion functions from the operation of a single pair of scroll plates as the unit normally operates in a single, normal direction. Such design eliminates any gearing or shafting between the compressor and expander, and, at the same time, reduces cost and increases efficiency. 
         [0017]    Such construction includes a housing with two interleaved scroll plates that form a scroll plate pair and which are installed within such housing to be operably movable relative to one another, such as in an eccentric orbit relative to one another. Preferably, one of such scroll plates is fixed and the other scroll plate is movable, and such scroll plates include interleaved spiral projections on facing sides thereof, each of which spiral projections includes first and second portions, with the first spiral portion forming an inner involute spiral or wrap that spirals outwardly from the center in one spiral direction to an intermediate spiral point located intermediately between the center and the outer limit of the scroll plate and a second spiral portion forming an outer involute spiral or wrap that spirals outwardly from the intermediate spiral point in the opposite, or counter, direction from that of the inner involute spiral to an outer spiral point near the outer limit of the scroll plate. 
         [0018]    Preferably, the inner portions of the scroll plates will operate for expansion and the outer portions will operate for compression, but such portions and functions may be reversed if desirable for certain conditions or circumstances. 
         [0019]    For such noted, preferred operation of the inner and outer portions of the scroll plates, an expander inlet is provided at the center, a compressor inlet is provided at the outer spiral point, and a compressor discharge and expander discharge is provided at the intermediate spiral point. 
         [0020]    As the device operates in its normal, forward direction, the inner portion operates as an expander to expand the working fluid provided thereto at the expander inlet port associated with the center of the involute scrolls and to discharge the expanded fluid at the discharge port at the intermediate spiral point, and the outer portion operates as a compressor to compress the working fluid provided thereto at the compressor inlet port at the outer spiral point and to discharge the compresses fluid at the discharge port at the intermediate spiral point. 
         [0021]    As preferably used for air conditioning purposes as part of a waste heat air conditioning system, the expander portion is thus operable to generate power that can be used to drive the compressor portion. Heated high pressure refrigerant will enter the expander portion and, during the expansion process, will produce power to drive the compressor, which will then compress refrigerant for a traditional air conditioning cycle. 
         [0022]    Typically, the expander inlet port will be connected to the outlet from the evaporator of an ORC, the compressor inlet port will be connected to the outlet from the evaporator of the traditional air conditioning cycle, and the discharge port will be at an intermediate pressure, with part of the flow therefrom going to the condenser for the ORC and part going to the condenser of the air conditioning system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is a cross section of a single scroll type unit constructed according to the present invention and in which idler shafts are shown employed for taking the axial loads and for controlling the motion and clearance between the scrolls of such unit. 
           [0024]      FIG. 2  is a cross section of an alternative single scroll type unit similar to  FIG. 1 , but which also includes an optional auxiliary motor for driving the unit as it is operating as a compressor when waste heat is not available. 
           [0025]      FIG. 3  is a cross section of another alternative single scroll type unit similar to  FIG. 1 , but which employs a flat plate thrust bearing for taking the axial loads, which reduces the loads on the idler shaft bearings allowing them to be smaller and making the unit smaller and lower cost. 
           [0026]      FIG. 4  is a cross section of another alternative single scroll type unit constructed according to present invention that, instead of idler shafts, employs an Oldham ring for aligning the scrolls and a flat plate thrust bearing for taking the axial loads. 
           [0027]      FIG. 5  is a partial sectional view of the scrolls looking in one direction along cut A-A of  FIGS. 1 through 4  showing a preferred involute wrapping for achieving both compression and expansion on the same scroll. 
           [0028]      FIG. 6  is a view somewhat similar to  FIG. 5 , but looking in the opposite direction from  FIG. 5  at cut A-A of  FIGS. 1 through 4  and providing an expanded view of a portion of the inner scroll set of the scroll plate pair, which view illustrates an alternate porting configuration, locatable at the ports B and/or C depicted in  FIG. 5 , that may be employed to delay the porting so that higher compression/expansion ratios can be achieved with fewer spiral wraps of the scroll. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0029]    Referring now to the drawings where like numbers refer to generally like items,  FIG. 1  depicts a preferred scroll type device  100  constructed according the present invention and including a housing  102 , which seals the unit from the atmosphere, with a fixed scroll plate  104  and an orbiting scroll plate  106  mounted therein on three generally equilaterally spaced idler shafts  108  rotatable within associated bearings  110 . Counterweights  112  and  114  are shown disposed about and fastened to the idler shafts  108  so that the eccentric weight of the orbiting scroll plate  106  remains balanced o and to reduce vibration during operation. Such support constructions are designed to take the axial loads and to control the motion of and clearance between scroll plates  104  and  106  as they move relative to one another. 
         [0030]    A typical design and description of operation of idler shafts such as idler shafts  108  is provided in U.S. Pat. No. 6,129,530, which is incorporated herein by reference thereto. Other idler shafts of known or similar or other constructions that can also act to take the axial loads and to control the motion of and clearance between scroll plates  104  and  106  could be equally as well employed. 
         [0031]    Such idler shafts  108  are preferably spaced approximately 120° from each other around the outside of the scroll plates  104  and  106 . Although such idler shafts  108  are shown located between fixed scroll plate  104  and orbiting scroll plate  106 , they could just as easily be located between the orbiting scroll plate  106  and the housing  102 . 
         [0032]      FIGS. 2-3  depict alternative embodiments of scroll type units that employ like support constructions but which also include other optional elements, such as the flat thrust bearing  116  of  FIG. 3  that is provided in order to reduce and to effect minimal loading on the idler shaft bearings  110 . With the use of such flat thrust bearing  116 , the idler shaft bearings  110  are more lightly loaded. Such lighter loading permits the use of smaller idler shaft bearings  110 , thereby saving space and weight, and thus also allows the overall scroll type unit to be smaller and less costly. 
         [0033]    Those skilled in the art will recognize and understand that alternatives other than idler shafts and associated bearing constructions can also be effectively utilized to properly align and control the scroll plates during their movement relative to one another.  FIG. 4  depicts one suitable alternative construction for accomplishing such alignment and control, and shows a scroll type unit  100  in which the positioning and alignment of the fixed scroll plate  104  and the orbiting scroll plate  106  are maintained through the use of an Oldham ring construction  118  instead of the idler shafts and associated bearing constructions of  FIGS. 1-3 . 
         [0034]    As will thus be further recognized and understood by those skilled in the art, the particular manner of effecting such alignment and positioning of the scroll plates during operation of the scroll type unit is not considered critical to the present invention and may take any suitable form sufficient to accomplish the desired result. 
         [0035]    As best shown in  FIGS. 5 and 6 , scroll plates  104  and  106 , which together form a scroll set or scroll plate pair, include on facing sides  130  and  132  thereof interleaved involute scrolls  134  and  136 , each of which scrolls  134  and  136  spirals outwardly in one clock direction from central portion  140  of the scroll set to an intermediate spiral point  142  spaced radially intermediately between central portion  140  and the outer periphery  143  of the scroll set, and then spirals outwardly in the opposite clock direction from intermediate spiral point  142  to an outer spiral point  144  near the outer periphery  143  of the scroll set. In the view of  FIG. 5 , the involute spirals  134  and  136  are shown spiraling outward counter-clockwise from the center portion  140  of the scroll set from point C to point B, and then continuing to spiral outwardly, but in a reverse clockwise direction, from point B to point A. 
         [0036]    Such reversal of direction of the spirals  134  and  136  results in two separate sections of the scrolls, one for effecting compression of fluids properly introduced thereinto and one for effecting expansion of fluids properly introduced thereinto. In the construction of  FIG. 5  the inner section  154  is designed and intended for effecting expansion and the outer section  156  is designed and intended for effecting compression. For certain conditions, however, the functions could be reversed if it were so desired. 
         [0037]    For constructions in which the inner portion is designed to function as an expander and the outer portion is designed to function as a compressor, points A, B, and C have associated therewith a compressor inlet port A, an expander inlet port C, and a discharge port B, all of which ports typically extend to the left face of the construction shown in  FIG. 1 , although only expander inlet port C is seen in the cross-sectional view of  FIG. 1  at location  157 . Typically, in use, expander inlet port C will be connected to the outlet from the evaporator of an ORC, compressor inlet port A will be connected to the outlet from the evaporator of the traditional air conditioning cycle, and discharge port B will be at an intermediate pressure, with part of the flow therefrom going to the condenser for the ORC and part going to the condenser of the air conditioning system. 
         [0038]    U.S. Pat. No. 6,050,792, incorporated herein by reference thereto, has previously described how a scroll type device may be constructed to include a scroll set in which the scroll plates have scrolls of two different involute heights in two sections of the same scroll. Such sectional technique can also be utilized in this invention for adjusting the displacement of the expander and compressor sections. 
         [0039]    As may be seen from  FIG. 6 , when the outer section  156  of the scroll is designed to function as a compressor and the inner section  154  is designed to function as an expander, compressor inlet port A is provided at outer spiral point  144  and a compressor outlet or port B is provided at intermediate spiral point  142 . Similarly, an expander inlet or port C is provided at center  140  and the outlet or port B at intermediate spiral point  142  is also the expander discharge outlet or port. 
         [0040]    Depending upon the uses desired for the single scroll unit  100  and the systems in which it might be employed, ports A, B, and C may be suitably connected to appropriate sources, vents, or other system connections. In most systems with which such scroll unit is employed, the expander discharge and compressor discharge will typically be at the same pressure, but the scroll unit may be configured to include a seal between the expander and compressor discharges in instances and/or for systems where they may differ. While there is generally no need for any associated switching related to such discharges, the ports could also be suitably controllably switched, if so desired, in order to affect the desired functions of such scroll unit  100 . 
         [0041]    In such constructions, it is preferable that the spiral involutes have a generally uniform wall thickness t, with the distance between wall mid-points of one wrap of the involute and a succeeding wrap of such involute being considered to be the Involute_Pitch of such involute. 
         [0042]    With reference now to  FIG. 6 , it may be observed that, for involutes having such characteristics, it is possible to delay the porting of the scroll toward the center end of the spiral wraps by rounding the centrally positioned ends of the involutes to form rounded inner ends  160  that have outer radii r c  equal to ½ of the wall thickness t, i.e., r c =t/2. 
         [0043]    As the inner sections  154  spiral outwardly towards the intermediate spiral point, when the positions along the spiral sections are displaced 180° about the center, there are formed along the inner sides of each of the spiral wraps a flared mating portion  162  that has an upstream flare portion  164  and a downstream concavity  166  with a mating surface  168  that has a radius r M  of ½[(Involute_Pitch)−t], i.e., r M =[(Involute_Pitch)−t]/2. 
         [0044]    As may be observed, such mating surface radius r Mm  of the spiral of plate  104  will match perfectly with the rounded end  160  on the spiral of spiral plate  106  as the scroll plates  104  and  106  move relative to one another, and such interaction will delay the porting of the scrolls. 
         [0045]    Oftentimes it is important to delay the porting of the scrolls so that a higher compression ratio for a compressor, or expansion ration for an expander, can be achieved in a smaller number of spiral wraps. This will allow the unit to be smaller and less costly. 
         [0046]    It should be further appreciated that it is possible to delay the porting even more by placing relief areas  170  just outward from the rounded ends  160  on the inner sides of the spirals and by providing complementary fingers  180  at the outer termini of the flare portions  162  so that the fingers  180  can complementarily engage the inner sides of the rounded ends  160  and relief areas  170 . 
         [0047]    Alternative porting of this or similar design can be provided at either or both of points B and C of  FIG. 6 . 
         [0048]    Those skilled in the art will also appreciate and understand that the involute spirals can be readily sealed with tip seals at locations  190  and  192 , as noted in  FIG. 1 , in acceptable conventional manners and using acceptable conventional materials, including elastomeric sealing materials. U.S. Pat. No. 6,511,308 and U.S. patent applications Ser. Nos. 11/703,585 and 12/930,140, incorporated herein by reference thereto, disclose several examples of acceptable manners and materials, which manners and materials should not be considered or treated as being limiting or exhaustive, however. 
         [0049]    With further reference now to  FIG. 2 , which depicts one preferred alternative embodiment of a scroll type unit  100  according to the present invention, such embodiment includes therewith an optional generator or motor  202  with an associated shaft  204  that extends to be rotatable within bearings  206  within housing  102 , and with counterweights  208  disposed along shaft  204 . Dependent upon the uses of the unit  100 , element  202  may be selected to be either a generator or a motor or a combination motor/generator. When the condition exists where waste heat is available, but air conditioning is not needed, the motor can also act as a generator for production of electricity. 
         [0050]    If the unit  100  is to be employed in a system where an excess of waste heat is produced, element  202  may be an auxiliary generator that can be driven from the expander of the unit  100  to generate electricity. Alternatively, element  202  may be a motor that is employed to drive the compressor of the unit  100 , such as to provide air conditioning. If so desired, element  202  could a combination motor/generator. 
         [0051]    In addition, the embodiment of  FIG. 2  includes an auxiliary device  210 , which may take many forms, including as an oil pump, fan, turbine, or other desired device, disposed to be driven by an idler shaft  108  of unit  100 . 
         [0052]    It should also be understood and appreciated that, by closing a valve to the inlet to the expander or inner scroll section of the scroll set, the expander portion can be isolated and will then draw a vacuum and require very little parasitic power. The motor  202  can then be used to power the compressor or outer scroll section of the scroll set independently for cooling or heating (heat pump mode) during times when there is not waste heat available to the ORC. 
         [0053]    Likewise, the compressor inlet can be closed off when air conditioning is not needed, but waste heat is available for the ORC. That would draw a vacuum on the compressor or outer scroll section of the scroll set and greatly reduce the, power that it would then draw. In such mode the element  202  would act as a generator and produce electricity. 
         [0054]    From the foregoing description and discussion it should be apparent that the invention and the preferred embodiments thereof that have been addressed provide a scroll type device that includes a single pair of scroll plates that are so configured and so interact to provide both compression and expansion functions as the plates eccentrically orbit one another in a given, normal direction, which functions advantageously permit waste heat energy to be used for air conditioning purposes. 
         [0055]    While it is generally most beneficial to be able to make use of both the compression and expansion functions, the use of such constructions need not be limited to joint or dual use environments. With appropriate porting, the constructions can also be employed for either compression or expansion purposes without necessarily requiring the use of both. 
         [0056]    Additionally, it should be understood and appreciated that reference herein to the invention as forming or being a single unit construction is not intended to limit the use of the invention or embodiments thereof to devices that are totally or physically separate from other elements or components, but, rather is intended to indicate that the invention does not require additional scroll plate pairs beyond the single scroll plate pair whose operation effects both the compression and expansion functions of the invention and to indicate that the invention is considered complete in its single stage form. In such regard, the invention could be readily employed as part of larger or more complex configurations or constructions, such as in multi-staged constructions, which include additional elements or components. 
         [0057]    In light of all the foregoing, it should thus be apparent to those skilled in the art that there has been shown and described a scroll type construction of a unique design that incorporates compression and expansion functions into a single unit as the unit normally operates in a single direction. However, it should also be apparent that, within the principles and scope of the invention, many changes are possible and contemplated, including in the details, materials, and arrangements of parts which have been described and illustrated to explain the nature of the invention. Thus, while the foregoing description and discussion addresses certain preferred embodiments or elements of the invention, it should further be understood that concepts of the invention, as based upon the foregoing description and discussion, may be readily incorporated into or employed in other embodiments and constructions without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown, and all changes, modifications, variations, and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention, which is limited only by the claims which follow.