PUMP
A pump.
This application is a continuation in part of, and claims the benefit of priority to, U.S. patent application Ser. No. 13/543,322 filed Jul. 6, 2012, which itself claims benefit of U.S. Provisional Application No. 61/505,991 filed Jul. 8, 2011, the entire disclosures of which are hereby incorporated herein by reference for all purposes.
BACKGROUND OF THE INVENTIONThe subject matter of this application relates to a pump.
For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:
Referring to
The gear housing 18 is formed on the opposite side from the bearing recesses with a gear recess 46 (
An electric motor (not shown) having a drive shaft 58 is attached to the end cap 26. A drive pinion 62 is attached to the drive shaft of the motor and is in meshing engagement with the spur gear 50. Accordingly, when the motor drives the pinion 62, the two spur gears 50, 54 are driven at equal speeds in opposite directions.
The work rotor 38 is generally cylindrical and has two diametrically opposed vanes 66, 68 extending parallel to the central axis of the work rotor and projecting radially therefrom. When the work rotor rotates within the cavity 36 of the interior space, a small clearance exists between the tip of the vanes and the surface bounding the cavity 36. Thus, as the work rotor rotates, the work rotor and the pump rotor housing are in an effective sealing relationship. The cylindrical surface of the lower cavity extends at least 180 degrees about the central axis of the work rotor so that there is always at least one vane between the inlet passage and the outlet passage.
The pump rotor housing 14 is formed with an inlet passage 69 and an outlet passage 70 that communicate with the cavity 36. The upper end of each passage is internally threaded to receive a suitable hose attachment fitting.
The sealing rotor 42 is generally cylindrical and is formed with two peripheral notches 73, 74 that extend longitudinally of the rotor parallel to the axis of rotation of the rotor.
It will be appreciated from examination of
The radius of curvature of the upper cavity 37 in the regions Y is slightly greater than the radius of the cylindrical surface of the sealing rotor. The peripheral surface of the upper cavity in each of the regions Y subtends an angle at least as great as the angle subtended by the peripheral notches 73, 74, so that during rotation of the sealing rotor the external surface of the sealing rotor remains in effective sealing relationship with the pump rotor housing with respect to flow of gas around the sealing rotor.
The radius of curvature of the cavity 37 between the regions Y is somewhat greater than in the regions Y, which facilitates manufacture of the pump rotor housing because the tolerance on the dimensions of the peripheral surface of the upper cavity between the regions Y may then be greater than in the regions Y.
As shown in
Depending on the angular position of the work rotor 38, the sealing rotor 42 and the two vanes 66, 68 define two or three chambers within the cavity 36. At the position shown in
Referring again to
When the vane 66 reaches the lower edge of the inlet passage, the inlet chamber 71 that was bounded by the trailing flank of the vane 68 becomes a transfer chamber and a new inlet chamber is created between the rotor seal and the trailing flank of the vane 66. The transfer chamber 71 between the leading flank of the vane 66 and the trailing flank of the vane 68 is isolated from the inlet passage. A quantity of gas is trapped in the transfer chamber, except for minor leakage between the tips of the vanes and the peripheral surface of the lower cavity 36. Advancing movement of the vane 66 pushes the trapped gas in the clockwise direction about the central axis of the working rotor.
As the work rotor continues to rotate, the tip of the vane 68 reaches the lower edge of the outlet passage 70. The outlet chamber and the transfer chamber are then in communication and a new outlet chamber is thereby created between the leading flank of the vane 66 and the rotor seal. The work rotor continues to rotate and the advancing of the vane 66 decreases the volume of the outlet chamber, tending to increase the pressure in the outlet chamber and expel gas from the outlet chamber through the outlet passage 40. The rotor seal and the narrow clearance between the peripheral surface of the upper cavity in the region Y and the cylindrical surface of the sealing rotor in the region Y provides a large resistance to leakage of gas from the outlet chamber. Accordingly, most gas is forced to leave the outlet chamber through the outlet passage.
The term effective sealing relationship used herein does not require a perfect seal, with the external surfaces of the work rotor and the sealing rotor, for example, continuously in sealing contact. An effective sealing relationship between two members requires that the rate at which fluid can leak between the members should be small relative to the rate at which fluid is delivered from the inlet passage to the outlet passage.
In a conventional external gear pump, the gear teeth divide the incoming flow of air into two streams, each of which is chopped by gear teeth into small volumes which are subsequently combined. This manner of operation consumes energy, resulting in heating of the gas. In the case of the pump illustrated in
In a modification of the pump shown in
One desirable advantage of the pumps disclosed herein is that several such pumps may be easily interconnected to provide a desired mass flow rate, a desired compression ratio, or both. Referring first to
The pump rotor housings 14, gear housing 18, and end caps 22, 26 of
As can be seen in
As another alternative embodiment,
Referring to
Referring to
As noted previously, a multi-stage pump 200 may be constructed from modular components to achieve a desired compression or pressure ratio. For example, such components could comprise end caps, a plurality of stages of different respective volumes, and a plurality of interfaces between stages where each interface comprises two walls together defining the opening 292. The plurality of stages could include intermediate stages that lack both an inlet 230 and an outlet 240, so that a three stage, four stage, or higher-stage pump could be assembled with intermediate stages simply receiving fluid from one stage having a higher volume flow and ejecting fluid into another stage with a lower volume flow. Furthermore, those of ordinary skill in the art will appreciate that such modularity may include the assembly depicted in
The multi-stage pump 200 shown in
Second, referring to
Third, referring to
Fourth, referring to
It will be appreciated that the invention is not restricted to the particular embodiment that has been described, and that variations may be made therein without departing from the scope of the invention as defined in the appended claims, as interpreted in accordance with principles of prevailing law, including the doctrine of equivalents or any other principle that enlarges the enforceable scope of a claim beyond its literal scope. For example, the invention is not restricted to the sealing rotor having the same number of notches as the number of vanes of the work rotor. With suitable adjustments in timing of rotation of the rotors, the sealing rotor may have only one notch. Moreover, the work rotor may have more than two vanes, although it will be appreciated that as the number of vanes increases, the volume of the pump available for pumping fluid will decrease. Unless the context indicates otherwise, a reference in a claim to the number of instances of an element, be it a reference to one instance or more than one instance, requires at least the stated number of instances of the element but is not intended to exclude from the scope of the claim a structure or method having more instances of that element than stated. The word “comprise” or a derivative thereof, when used in a claim, is used in a nonexclusive sense that is not intended to exclude the presence of other elements or steps in a claimed structure or method.
Claims
1. A pump comprising:
- a plurality of pump rotor housings, each having a work rotor and a sealing rotor that cooperate to compress fluid in the respective pump rotor housing between a first chamber and a second chamber;
- at least one inlet to the pump and at least one outlet to the pump; and
- at least one shaft that together drives the work rotor and sealing rotor.
2. The pump of claim 1 where each of the plurality of pump rotor housings are isolated from each other such that fluid that enters a first chamber of one of the plurality of pump rotor housings does not enter a first chamber of any other of the plurality of pump rotor housings.
3. The pump of claim 2 where each pump rotor housing has an inlet and an outlet different from those of any other pump rotor housing.
4. The pump of claim 1 where the second chamber of one of the plurality of pump rotor housings releases fluid into a first chamber of another one of the plurality of pump rotor housings.
5. The pump of claim 4 having a plurality of outlets that each exhaust compressed fluid that has not intermixed with compressed fluid exhausted from the other ones of the plurality of outlets.
6. The pump of claim 4 having a member interposed between the plurality of pump rotor housings that defines a path through which the fluid flows between the second chamber of one of the plurality of pump rotor housings and the first chamber of another one of the plurality of pump rotor housings, the path comprising an elongate portion and opposed first and second openings on either side of the elongate portion, the first opening receiving fluid from the second chamber and the second opening releasing fluid into the first chamber.
7. The pump of claim 1 where the work rotor includes a vane, and the sealing rotor includes a notch into which the vane engages during rotation of the sealing rotor and the work rotor, and where the vane is shaped to cause negative feedback on the entry of fluid into the notch as the vane released from the notch.
8. The pump of claim 1 including at least one seal, and where the pressure ratio of the pump seals improves the effectiveness of the at least one seal in containing pressurized fluid within the at least one pump rotor housing.
9. The pump of claim 1 includes a vane, and the sealing rotor includes a notch into which the vane engages during rotation of the sealing rotor and the work rotor, and where the vane and the notch have respective curved surfaces with the same radius of curvature.
10. The pump of claim 1 where the work rotor is housed in a cavity having generally cylindrical surface with a first radius of curvature and a second radius of curvature smaller than the first radius of curvature, and where the second radius of curvature of the cylindrical surface is limited to an area slightly offset from a centerline of the work rotor.
11. A method of assembling a pump, the method comprising:
- (a) attaching a first rotor housing to a second rotor housing, each having a work rotor and a sealing rotor that cooperate to compress fluid in the respective pump rotor housing between a first chamber and a second chamber, where at least one of the first and second rotor housings has an inlet and at least one of the first and second rotor housings has an outlet;
- (b) attaching end caps that surround the first rotor housing and the second rotor housing; and
- (c) providing a drive system for the work rotor and the sealing rotor of each of the first rotor housing and the second rotor housing.
12. The method of claim 11 where each of the plurality of pump rotor housings are isolated from each other such that fluid that enters a first chamber of one of the plurality of pump rotor housings does not enter a first chamber of any other of the plurality of pump rotor housings.
13. The method of claim 12 where each pump rotor housing has an inlet and an outlet different from those of any other pump rotor housing.
14. The method of claim 11 where the second chamber of one of the plurality of pump rotor housings releases fluid into a first chamber of another one of the plurality of pump rotor housings.
15. The method of claim 14 having a plurality of outlets that each exhaust compressed fluid that has not intermixed with compressed fluid exhausted from the other ones of the plurality of outlets.
16. The method of claim 14 including the step of attaching the first rotor housing and the second rotor housing to respective sides of a wall member, the wall defining a path through which the fluid flows between the second chamber of one of the plurality of pump rotor housings and the first chamber of another one of the plurality of pump rotor housings, the path comprising an elongate portion and opposed first and second openings on either side of the elongate portion, the first opening receiving fluid from the second chamber and the second opening releasing fluid into the first chamber.
17. A pump comprising:
- an inlet for providing fluid to the pump;
- a rotatable sealing rotor defining a cavity; and
- a rotatable work rotor defining a vane that engages with the cavity during rotation of the work rotor and the sealing rotor, the vane having a tip shaped to provide negative feedback on fluid entering the cavity as the vane clears the cavity.
18. The pump of claim 17 where the shape of the tip creates turbulence.
19. The pump of claim 17 where the tip is U-shaped.
20. The pump of claim 17 where the tip is V-shaped.
Type: Application
Filed: Feb 11, 2014
Publication Date: Jun 12, 2014
Inventor: Edward L. SIMONDS (Salem, OR)
Application Number: 14/178,033
International Classification: F04C 2/08 (20060101); F04C 15/00 (20060101);