Abstract:
A fluid pressure responsive member is shifted in accordance with the pressure differential between two lines either one of which can be a suction line with the other line being a discharge line of a reversible compressor. The fluid pressure responsive member has a pair of arcuate recesses formed therein which serve as secondary suction ports which provide fluid communication to the elliptical chamber from suction lines in accordance with the position of the fluid pressure responsive member. Because the porting is responsive to the pressure differential between the two lines, the changeover of the porting is automatic upon the reversal of the operation of the compressor.

Description:
BACKGROUND OF THE INVENTION 
     In heat pump applications, the switchover from the heating to the cooling mode, and vice versa, reverses the direction of flow for the refrigerant such that the coils serving as the condenser and evaporator, respectively, reverse functions. Where the compressor operates in a single direction, the change in the direction of the flow is generally achieved through a valving arrangement located externally of the compressor. If the compressor itself is reversible, it can be selectively run in either direction to, thereby, achieve the desired direction of flow. The simple reversal of the motor and, thereby, the compressor is not, in and of itself, sufficient to produce a compressor with satisfactory performance in both directions. In a valveless compressor, this unequal performance in both directions is due to the switching between high and low side compressor operation, the changes in the cooling requirements and the cooling flow, the reversal of porting function and direction of opening/closing, etc. 
     SUMMARY OF THE INVENTION 
     In a rotary hermetic compressor of the valveless multi-vane type driven by a reversible motor, the reversing of the motor direction causes the shifting of the port controlling structure. Specifically, a port controlling member is responsive to the pressure differential between the two lines connected to the shell of the compressor and shifts in accordance with the direction of the pressure differential. Thus, the reversal of the motor reverses the compressor and, thereby, the direction of the pressure differential which, in turn, causes the shifting of the port controlling structure in order to permit the higher volumetric flows required at the suction side of the compressor. 
     It is an object of this invention to provide a mechanism to enable a reversible, valveless multi-vane rotary compressor to efficiently deliver reverse flow by reversing the direction of motor rotation. 
     It is a further object of this invention to provide a valveless, multi-vane rotary compressor having a symmetrical pressure loading. 
     It is another object of this invention to provide supplemental suction ports in both directions of operation for a reversible compressor. These objects, and others as will become apparent hereinafter, are accomplished by the present invention. 
     Basically, the reversal of the direction of rotation of a motor driving a compressor reverses the operation of the compressor and, thereby, the direction of the pressure differential across the compressor. The pressure differential acts on a fluid pressure responsive device which shifts in accordance with the direction of the pressure differential. The shifting of the fluid pressure responsive device causes a supplemental suction port to be connected with the suction side of the compressor, whereby, the greater suction volumetric flow can be accommodated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the present invention, reference should now be made to the following detailed description, thereof, taken in conjunction with the accompanying drawings wherein: 
     FIG. 1 is a partial view of the motor-compressor unit of the present invention with a portion of the shell removed; 
     FIG. 2 is a partial sectional view taken along line II--II of FIG. 5 showing the suction flow path during counterclockwise rotation of the motor; 
     FIG. 3 is a partial sectional view taken along line III--III of FIG. 5 showing the discharge flow path during counterclockwise rotation of the motor; 
     FIG. 4 is a sectional view taken along line IV--IV of FIG. 2; 
     FIG. 5 is a sectional view taken along line V--V of FIG. 2; and 
     FIG. 6 is a partially cut away sectional view showing the suction and discharge flow paths during clockwise rotation of the motor. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the figures, the numeral 10 generally designates a hermetic motor-compressor unit having a shell 12. Fluid communication with the compressor 14 is provided by lines 20 and 21. The compressor 14 is reversibly driven by reversible motor 16 which is connected to compressor 14 via shaft 18. Motor 16 can be any conventional reversible motor suitable for use in a hermetic compressor. Shaft 18 is connected to and rotatably drives cylindrical vane support 30 in elliptical chamber 34 in block 36. Vane support 30 contains a plurality of reciprocably moving, radially extending vanes 32 which are biased outwardly into contact with the wall defining elliptical chamber 34 by centrifugal force derived from the rotation of the shaft 18 to define a plurality of trapped volumes 34a between adjacent vanes 32. If necessary or desirable, springs may be used for biasing each vane 32 to get sufficient and balanced biasing forces. As is best shown in FIG. 5, block 36 is in touching contact with the interior of shell 12 at the portions labeled 36a-d. Additionally, block 36 has a number of cutouts labeled 36e-g which define plenums 136e-g, respectively, in combination with the interior of shell 12. Four horizontal bores 38a-d are located within block 36 with bore 38a being in direct fluid communication with line 20, and bores 38b and d being in direct fluid communication with plenums 136f and g, respectively. Bores 38a and d are coaxial as are bores 38b and c. As best shown in FIG. 5, there are six axially or vertically extending bores 39a-f with bores 39a and b being in direct fluid communication with bore 38a, bore 39c being in direct fluid communication with bore 38b, bores 39d and e being in direct fluid communication with bore 38c and bore 39f being in direct fluid communication with bore 38d. 
     Overlying and contacting block 36 are disk 40 and cover 42 with disk 40 being rotatably located within cover 42. Cover 42 is fixedly secured to block 36 by any suitable conventional means such as bolts (not illustrated). As best shown in FIG. 4, a first arcuate recess 42a is formed in cover 42 and serves as a plenum 142 fluidly connecting vertical bores 39a and e. A second arcuate recess 42c is formed in cover 42 and is fluidly connected to plenum 142 via passage or line 42b. Cover 42 has a cutout 42e which together with the interior of shell 12 forms a continuation of plenum 136e. Arcuate recess 42c is, additionally, in fluid communication with plenum 136e via passage or line 42d. Disk 40 has a pair of diametrically located arcuate recesses 40a and b which define supplemental suction ports and a tab 41 which is movable in arcuate recess 42c responsive to the differential in pressure between that supplied at face 41a by line 42b  and that supplied at face 41b by line 42d. Thus, tab 41 is effectively a piston and recess 42c a piston chamber. Line 20 is in communication with recess 42c and face 41a of tab 41 via bores 38a and 39a, plenum 142 and line 42b. Line 21 is in communication with recess 42c and face 41b of tab 41 via the plenum defined by shell 12, plenum 136e and line 42d. 
     Referring now to FIGS. 2-5 where shaft 18, cylindrical vane support 30 and vanes 32 are being rotated in a counterclockwise direction as illustrated, line 20 is the suction line and line 21 is the discharge line. Refrigerant at suction pressure is supplied to compressor 14 via line 20. Specifically, refrigerant at suction pressure is supplied directly from line 20 to elliptical chamber 34 via bore 38a. Additionally, refrigerant at suction pressure is supplied from bore 38a via bore 39b and the recess 40a to chamber 34 and via bore 39a to plenum 142. Refrigerant in plenum 142 is in fluid communication with tab face 41a and recess 42c and is supplied via bore 39e to bore 38c from which it is supplied directly to chamber 34 as well as being supplied via bore 39d and recess 40b to chamber 34. Thus, bores 38a and c are primary suction ports to chamber 34 and recesses 40a and b are secondary suction ports. Refrigerant gas supplied via bore 38 a and recess 40a is compressed and discharged from chamber 34 via bore 38d while the refrigerant gas supplied via bore 38c and recess 40b is compressed and discharged from chamber 34 via bore 38b. As is best shown in FIG. 3, bore 38b discharges into plenum 136f and bore 38d discharges into plenum 136g. Plenums 136f and g communicate with the discharge chamber defined by shell 12, when motor 16 is rotating counterclockwise, and thence to line 21 which is the discharge line. Additionally, the discharge pressure is supplied from the discharge chamber defined by shell 12 to plenum 136e from which it is supplied to recess 42c via line 42d where it acts upon face 41b of tab 41. Since the discharge pressure acting on face 41b is greater than the suction pressure acting on face 41a, disk 40 is shifted to the FIG. 4 position when the motor is rotated counterclockwise. It will be noted, that when disk 40 is in the FIG. 4 position, bores 39c and f are blocked and serve no purpose. 
     If the motor 16 is rotated clockwise, line 21 becomes the suction line, shell 12 defines a suction plenum and line 20 is the discharge line. Assuming that the motor 16 had been running in a counterclockwise direction so that disk 40 is in the FIG. 4 position, all of the porting will be the reverse of that previously described and recesses 40a and b will be initially acting as secondary discharge ports and will be in fluid communication with bores 39b and d, respectively. Since the volumetric flow is much greater on the suction side than on the discharge side, the operation will be inefficient until disk 40 shifts from the FIG. 4 to the FIG. 6 position. Refrigerant at discharge pressure which is supplied to plenum 142 via bore 38c and 39e and via bore 38a and line 39a is also supplied via line 42b to recess 42 where it acts on face 41a of tab 41. Refrigerant at suction pressure which is supplied via line 21 to the suction plenum defined by shell 12 is supplied via plenum 136e and line 42d to recess 42c where it acts on face 41b of tab 41. When the discharge pressure builds up sufficiently, disk 42 is shifted from the FIG. 4 to the FIG. 6 position due to the pressure differential across tab 41. In the FIG. 6 position, recesses 40a and b are in fluid communication with bores 39c and f, respectively, while bores 39b and d are now blocked and serve no purpose. With motor 16 running clockwise and disk 42 in the FIG. 6 position, refrigerant at suction pressure is supplied via line 21 to the suction plenum defined by shell 12. From the suction plenum defined by shell 12, the refrigerant passes between shell 12 and cover 42 and block 36 to plenums 136f and g where it passes via bores 38b and d into elliptical chamber 34. Additionally it passes from bores 38b and d via bores 39c and f, respectively, into recesses 40a  and b which act as secondary suction ports in fluid communication with chamber 34. Refrigerant at discharge pressure is discharged from chamber 34 via bores 38a and c. Bore 38a is in direct fluid communication with line 20 while bore 38c is in fluid communication with bore 38a and line 20 via bore 39e, plenum 142 and bore 39a. 
     From the foregoing, it should be clear that disk 40 is rotated and the porting changed in response to the pressure differential between lines 20 and 21 which acts on the faces 41a and b, respectively, of tab 41. This rotation of disk 40 is responsive to the changing of the direction of rotation of motor 16 which reverses the suction and discharge lines and takes place automatically upon the reversal of the motor. 
     Although a preferred embodiment of the present invention has been illustrated and described, other changes will occur to those skilled in the art. It is, therefore, intended that the present invention is to be limited only by the scope of the appended claims.