Patent Application
20120183425
This application relates to vane compressors, and more particularly to a valveless vane compressor.
Vane compressors compress fluids, such as gas, and are well known in the art. A vane compressor may have internal disk in which a plurality of vanes are free to move in and out of the disk. The vanes follow an outer circumference and take in fluid when the vanes are extended from the disk, and compress the fluid as the vanes follow the circumference and contract thereby lessening the area in which the fluid is entrapped. The compressed fluid is pushed out of a fluid outlet. To prevent the fluid from back flowing into a vane compressor, valves are typically disposed within the fluid outlet to prevent such back flow. As the compressor drive shaft rotates, the vanes slide in and out to make contact with the compressor wall. Fluid enters at the largest opening and the compressed fluid discharges from the smallest opening. Vane compressors may utilize a centered drive shaft and a shaped outer surface or an offset drive shaft and a circular outer surface.
According to an example disclosed herein, a vane compressor has a plurality of vanes that are radially translatable and have outer ends. The vanes create zones between each pair of adjacent vanes, each zone having a given area. The vane compressor also has an axis about which the vanes rotate and an outlet for expelling compressed fluid. A first zone immediately following a second zone that is in register with the outlet has the same area as the second zone.
According to a further example disclosed herein, a method of compressing fluid is provided. The method includes the steps of inletting a fluid having a first area; compressing the fluid by decreasing the first area to a smaller second area; rotating the second area to a first zone immediately leading a second zone having an outlet; rotating the second area to the second zone; and outletting the fluid from the second zone to reduce backflow from the outlet.
The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
The FIGURE shows a schematic view, partially in phantom, of a vane compressor as described herein.
Referring to the FIGURE, a vane compressor 10 is shown. The vane compressor 10 is of the balance type, however, one of ordinary skill would recognize that this teachings may be usable in other types of vane compressors, balanced or non-balanced, and with central off center drives or centered drives, etc. The vane compressor 10 has a disk 15 that rotates about axis 20, a cam surface 25, slots 30, vanes 35, inlets 40 and outlets 45. The dimensions shown in the FIGURE are exaggerated for ease of observation. As shown herein, the vane compressor 10 rotates in a clockwise direction.
Within the disk 15, the vanes 35 translate during rotation of the disk 15 within the slots 30 so that there is contact between the cam surface 25 and the vanes 35. The vane compressor 10 is a balanced vane compressor and has two inlets 40 and two outlets 45 distributed around and through the cam surface 25. Though fourteen vanes 35 are shown herein, one of ordinary skill will recognize that other numbers of vanes 35 are utilizable herein.
As the disk 15 and the vanes 35 rotate, areas of variable size are created between the vanes 35. As shown in the FIGURE, there are 14 zones designated from A to N as will be discussed herein.
Zones A, B and C, which all have the same or similar area, form an outlet zone O. Zone B is in register with an outlet 45 of outlet zone O. Similarly, zones H, I and J, which all have the same or similar area, form a similar outlet zone P where zone I is in register with outlet 45 of outlet zone P. In outlet zone O and outlet zone P, the vanes 35 in register therewith are in a stowed position within the relevant slots 30 as they follow first contour 50 in the cam surface 25. The first contour 50 of the cam surface 25 in outlet zone P has a constant length radius 55 emanating from axis 20. The area of zones A, B, and C, and the area of zones H, I, J, is minimized and carry compressed fluid, such as air, therein.
Zones D and K form compression zones as the variable vanes 35 move from an extended position relative to the slots 30 to a stowed position while following a diminishing second contour 60 thereby limiting (e.g., diminishing) the area of zones D and K to the same area shown in zones A, B and C forming outlet zone O and zones H, I and J forming outlet zone P respectively. The diminishing second contour 60 has a radius 65 emanating from axis 20 that diminishes from a length of a radius 70 in zone E to the same length of radius 55 as in outlet zones O and P.
Zones F and E and Zones M and L all have the same or similar area and a constant radius 70 following third contour 75 of the cam surface 25.
Zones F and G, and N and M are each in register with a fluid inlet 40. Zones N and G represent expansion areas where the vanes 35 move from a stowed position to an extended position to allow fluid to move therein and the fourth contour 80 which attaches the first contour 50 to the third contour 75. Zones E and L each have the same area as the preceding zones M and F to prevent back flow of fluid from zones E and L to the zones M and F respectively because the pressure in those zones are the same. Zones N and G have an extending arc 85.
As previously mentioned, zones K and D compress in area, thereby compressing the fluid therein, so that the zone C and the corresponding zone J have fluid at the proper pressure to export the pressurized fluid through the outlets even though zones C and J do not align with an outlet 45. If the zones C and J are not fully compressed until they reach zones I and B, then as the vane between B and C or I and J passes the outlet 45 there may be back flow into zones C or J. As zone C moves to zone B and zone J moves to zone I though it is clear that the pressure of the fluid is proper to outlet through the outlets 45 without significant backflow into the zones I or B. By waiting another zone to expel the fluid compressed in zones C or J, the two aft vanes in zones O and P, in essence form a seal to reduce back flow.
Waiting a zone to export the fluid through an outlet 45 after the fluid is compressed, allows a vane compressor 10 to be built without valves for preventing back flow. Similarly, zones A and H are also maintained at the same area as zones B and I, respectively. If zones A and H were allowed to expand in area by allowing the vanes 35 to move outwardly along the cam surface 25 in zones A and H, the drop in pressure in those zones may pull fluid from an outlet 45 through zones I and B respectively causing undesirable back flow from an outlet 45. By waiting a zone, the two forward vanes and the two aft vanes in zones O and P, in essence form a seal to reduce back flow. As a result, by extending the vanes in zones N and M a full zone past an outlet 45, a backflow prevention valve at an outlet 45 is unnecessary.
Functionally, by keeping the area of zones A, B and C substantially constant as they create outlet zone O can prevent the need for back flow valves (not shown). The area in those zones is kept substantially constant herein by maintaining the substantially constant arc in the first contour 50 of the cam surface 25 in those zones. This is also true in outlet zone P which includes zones H, I and J.
Similarly, vanes surrounding zones L and E are kept at a substantially constant distance from the axis 20 to the cam surface 25 as the immediately preceding zones M and F which are in register with the inlets 40. This prevents back flow of fluid as it is compressed in zones K and D to reduce back flowing through the inlet 40 and wasting energy of compressing the fluid.
Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in the FIGURE or all of the portions schematically shown in the FIGURE. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.
