Pumps – One fluid pumped by contact or entrainment with another – Liquid pumped by supplying or exhausting gaseous motive...
Reexamination Certificate
2000-08-17
2001-05-01
Walberg, Teresa (Department: 3742)
Pumps
One fluid pumped by contact or entrainment with another
Liquid pumped by supplying or exhausting gaseous motive...
Reexamination Certificate
active
06224344
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates to the transfer of fluid by pumping action. In particular, the present invention relates to a pumping system wherein fluid is cyclically moved under the influence of a vacuum-generated pressure differential.
2. Background of the Invention
Several types of mechanical pumps for transferring fluid are known and in wide use. The two most basic classifications are positive displacement pumps and dynamic or momentum-change pumps. Dynamic pumps add momentum to a fluid by means of rapidly moving blades, fans or the like. As the fluid moves through open passages and discharges into a diffuser section, its momentum is increased and its velocity converted into an increased pressure. Dynamic pumps include rotary or rotodynamic types, such as centrifugal or radial exit flow, axial flow, and mixed flow pumps. Also included are jet or ejector pumps, electromagnetic, and fluid actuated types such as gas-lift and hydraulic-ram pumps.
The centrifugal pump is a popular type of dynamic pump that consists mainly of a rotating vane-type impeller that is enclosed in a stationary casing. The liquid being pumped is drawn in through the “eye” of the impeller and is thrown to the outer edge or periphery of the impeller by centrifugal force. Considerable velocity and pressure are imparted to the liquid in the process. The liquid leaving the periphery of the impeller is collected in the casing and directed through the discharge opening. Frequently, the impeller of the pump is mounted directly on the shaft of the pump-driving motor so that the pump and motor are an integral unit. In other cases, the pump and motor are separate units and are connected together by a flexible coupling.
Positive displacement pumps all generally have some type of a moving boundary that forces fluid to move by volume changes. The fluid is admitted through an inlet into a cavity, which then closes, and the fluid is squeezed through an outlet. Classifications include reciprocating and rotary types. Reciprocating types utilize a piston, plunger or diaphragm as the moving boundary. Rotary types utilize one or more sliding vanes, flexible tubes or linings, helical screws, gears, lobes, circumferential pistons, or peristaltic contraction. In a reciprocating pump, for example, a moving boundary may be a piston. The piston is driven by a connecting rod that reciprocates off of a rotating crankshaft enclosed in a crankcase. In a rotary pump, a moving boundary may be a rolling piston revolving on an eccentric shaft mounted concentrically in a cylinder; a series of rotating vanes or blades mounted about the periphery of a slotted rotor shaft mounted eccentrically in a cylinder; or a pair of mated, enmeshed helically grooved rotors lobes (screw) housed in a cylinder, wherein the male rotor contains a series of lobes that mesh with corresponding flutes on the driven female rotor.
From the above discussion, it is clear that known pumps require several moving components having a large mass or density. These components are subject to large accelerations and friction, are prone to wear and vibration, and require costly and time-consuming maintenance. Depending on the particular design, prior art pumps require for their operation compression and oil rings, oil grooves, packings, seals, bushings, bearings, valves, cams, springs, liners, sleeves or jackets, and other machined components. They also require elaborate lubrication, cooling and control systems involving additional components, such as servos, equalizing and bypass lines, bleed holes, filters, desiccant dryers, reservoirs, and even additional pumps. They incur high design, manufacturing and operating costs, which are by necessity allocated to the consumer or end user. Finally, they usually require some means for priming the system prior to effective operation, and are subject to damage due to neglect by the operator.
The present invention is provided to solve these and other problems associated with known pumps.
SUMMARY OF THE INVENTION
The present invention is provided to emulate the pumping action of conventional pumps, and achieve or surpass the transfer efficiency and capacity of such pumps. The present invention realizes high pumping performance, while at the same time eliminates structural and operational complexity and reduces the significance of cost and maintenance issues. In particular, the present invention relies on no components to move or transfer fluid within its associated system. Importantly, there is no moving boundary or rotating device. The only moving parts subject to wear are minor control devices such as a level sensor and one or more check valves, regulators and solenoid valves. These parts are relatively inexpensive and easily replaceable.
The present invention is operable over a wide range of temperatures, pressures and flow rates. The flow may be pulsed or kept uniform. The operating pressure on the system may be adjusted to deliver a strong turbulent flow or a low-energy laminar flow. Foaming maybe controlled. In addition, a wide range of fluids of varying viscosities and compositions may be pumped. For instance, an ink having a viscosity measured at 1.5 min. #2 Zahn cup has been successfully tested. Liquids may be mixed and kept homogenous without the use of mechanical agitators or paddles.
As will also become evident from the balance of the disclosure, the present invention does not require lubrication and cooling systems. Hence, there is no danger of contamination of the fluid to be pumped such as by oil, grease, silicone and the like, and no attraction of dust or dirt. Potable water, intravenous solutions, blood, or sensitive chemicals could be pumped, for instance. Furthermore, the costs of maintaining lubrication and cooling systems are eliminated. As there are no moving parts coming into contact with the fluid, suspensions containing flock or solids are not subject to shear and do not clog the system. Many types of abrasive solutions are compatible. Neither is the present invention subject to deleterious conditions such as stalling, mechanical binding, locked-rotor, vapor lock, or cavitation. For example, in the operation of the present invention it has been observed that, where a pipe or conduit becomes blocked, the system will remain stable without incurring damage. The system can be left activated and run dry with no fluid being pumped, without adverse effect; the system will simply continue to circulate air. Thus, many of the elaborate safety and motor control circuits needed for prior art systems are eliminated.
Moreover, because there are no moving parts of significant mass, the only parasitic friction loss generated is that caused by the fluid pumped through the various conduits chosen for the system. In terms of wear, maintenance and transfer efficiency, this friction energy is negligible. Virtually all of the energy harnessed for use in the system is transferred directly for use in moving the fluid. The elimination of friction also makes the present invention highly suitable for pumping fluids which are sensitive to positive heat transfer. Thus, the present invention ensures that the viscosities and other properties of fluids such as oils and polymers are not compromised. Finally, the embodiments disclosed may be assembled and disassembled in a matter of seconds.
Accordingly, in one embodiment of the present invention, a pumping system comprises a pumping chamber having a liquid inlet and a liquid outlet. The liquid inlet communicates with a liquid supply source. Means are provided for sensing high and low liquid volume levels in the pumping chamber. Means for cycling the chamber between fill and empty states operably communicates with the sensing means and includes means for decreasing a level of pressure within the pumping chamber below a level of pressure within the liquid supply source in response to a sensed low liquid volume level, and means for increasing the level of pressure within the pumping chamber in response to a sensed high liquid volume level. The pumping system ma
Patel Vinod D
Walberg Teresa
Wallenstein and Wagner, Ltd.
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