Piston pump and method of reducing vapor lock

Pumps – Processes

Reexamination Certificate

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

C417S313000, C417S420000, C092S079000

Reexamination Certificate

active

06179568

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to piston pumps and methods of reducing vapor lock during pumping. In particular, the present invention relates to magnetically driven piston pumps capable of being used with absorption heat-pump and air conditioning systems.
2. Description of the Related Art
Recent attention has been given to the commercial viability of absorption heat-pump and air conditioning systems, and, in particular, to their use in residential and commercial heating and cooling applications. This increased attention has prompted developments in reducing the physical size of such systems, increasing the heating or cooling efficiencies of such systems, and increasing the service life of such systems. As improvements are made to the overall system, individual components are also receiving increased attention and refinements as such contribute to achieving further gains associated with the heat-pump system.
One component of heat-pump systems, the absorption system solution pump, has such a large number of operating requirements and design constraints, especially in smaller tonnage systems using ammonia/water, that few improvements have been made to it by prior artisans. Such solution pumps must be relatively small in size; be corrosion resistant, particularly to a solution of ammonia and water; hermetic; be able to provide a pressure lift of at least 300 psi; be able to pump liquid, vapor or both (and thus have a net positive suction head (NPSH) of zero); be free from wear even if exposed to abrasive particles; and ideally have a relatively long service lifetime of approximately 60,000 to 80,000 hours, using no normal lubricants. Although pumping devices are known which may provide one or more of these features or abilities, none are known which provide the complete combination of these features.
Service lifetime is one factor contributing to the commercial success of a heat pump. Service lifetime means the time period a pump should operate without maintenance or failures. When pumping devices are incorporated into larger packaged systems, such as absorption heat-pump systems, the pumping device should have a service life at least as long as the packaged system, as replacement of the pumping device often requires disassembly of the system. Competitive heat-pump systems are often expected to operate up to 20 years or 60,000 hours of operation without significant maintenance. Thus, the need exists for a pumping device which has a service life of at least 60,000 to 80,000 hours.
In addition, fluid pumps used in absorption heat-pump systems employing an ammonia and water solution are particularly susceptible to interior corrosion (or other chemical reactions) from prolonged exposure to the solution. Further, corrosion problems may arise when certain salts or other additives are placed in the ammonia and water systems to increase or decrease the range of system operating temperatures, or to operate the pump s a t temperatures higher or lower than the normal 80°-130° F. range. Thus, the need exists for a pumping device which is relatively resistant to corrosion or other chemical reactions with the solutions of ammonia and water and potential additives.
In heat-pump systems utilizing an ammonia and water solution, the pumping device must have a net positive suction he ad (NPSH) equal to zero because the pump will commonly be exposed to an incoming solution at or near its boiling point. If the pressure of a liquid at the pump inlet is less than the NPSH of a normal pump, the solution will at least partially vaporize, causing destructive cavitation of the pump interior. Moreover, in the ammonia-water pumps, an NPSH of zero is necessary because the pump will be required to pump vapor along with the liquid during most of its operating lifetime. The pump must also be free from the possibility of leaks and must have high efficiency.
Piston pumps, such as the pump disclosed in U.S. Pat. No. 3,584,975, have been considered for use in absorption refrigeration systems, but most of these pumps have one or more drawbacks when they are used in heat pump systems. Many existing piston pumps are not durable enough to provide the continuous and frequent operation required in a heat pump system. For example, piston pumps are susceptible to wear and/or have parts that must be replaced or repaired periodically.
Complex manufacturing processes increase the cost of many piston pumps and make them too expensive to be used in affordable heat pump systems. In addition, many existing piston pumps undergo a condition known as vapor lock when they are used to pump liquids which are near boiling point during intake or which contain significant amounts of vapor.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to pumps and methods of pumping that substantially obviate one or more of the limitations of the related art. In particular, the present invention provides a substantially maintenance-free, corrosion resistant, relatively low cost, hermetic pump capable of being used in absorption heat pump systems. Preferably, the pump is small in size, provides a pressure lift of over 300 psi, pumps both liquid and vapor, and has a long service lifetime.
To achieve these and other advantages and in accordance with the purposes of the invention, as embodied and broadly described herein, the invention includes a pump comprising a crankshaft having opposite end portions and an eccentric portion between the end portions, and a housing defining a cavity, an outlet, at least one bore extending between the cavity and the outlet, and at least one inlet communicating with the bore. The eccentric portion of the crankshaft is in the cavity and the end portions of the crankshaft are rotatably coupled to the housing. The bore is offset such that the bore axis does not intersect with the axis of rotation of the crankshaft. The pump also includes a piston having a base disposed in the cavity and a head disposed in the bore. The base of the piston is coupled to the eccentric portion of the crankshaft such that rotation of the eccentric portion in the cavity reciprocates the piston head in the bore to provide discharge from the bore through the outlet and intake to the bore through the inlet. A valve structure is disposed to open and close the outlet in response to movement of the piston head during the discharge and the intake.
In another aspect, the invention includes a pump having a housing defining a cavity, an outlet, at least one bore extending between the cavity and the outlet, and at least one inlet communicating with the bore intermediate the cavity and the outlet. A first support is at one end portion of the housing, and a second support is at another end portion of the housing.
Additionally, the present invention includes a method of reducing vapor lock during pumping of a substance having a liquid phase and a vapor phase. The method includes introducing the substance into a chamber so that a liquid portion of the substance settles in the chamber below a vapor portion of the substance, allowing the vapor portion of the substance to pass into an intake tube through a first opening in the intake tube, introducing the liquid portion of the substance into the intake tube through a second opening in the intake tube so that the liquid portion of the substance mixes uniformly with the vapor portion of the substance, passing the mixture of the vapor portion and liquid portion from the intake tube to a bore, and reciprocating a piston in the bore to pump the mixture from the bore.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.


REFERENCES:
patent: 599487 (1898-02-01), Bailey
patent: 1870458 (1932-08-01), Kenney
patent: 1938451 (1933-12-01), Floyd et al.
patent: 2324291 (1943-07-01), Dodge
patent: 2345125 (1944-03-01), Huber
patent: 2399856 (1946-05-01), Coger
patent: 2429426 (1947-10-01), Phillips et al.
pat

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Piston pump and method of reducing vapor lock does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Piston pump and method of reducing vapor lock, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Piston pump and method of reducing vapor lock will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-2524279

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.