Pumps – Expansible chamber type – Mechanically actuated distributor
Reexamination Certificate
1999-07-14
2001-07-24
Tyler, Cheryl J. (Department: 3746)
Pumps
Expansible chamber type
Mechanically actuated distributor
C417S531000, C417S539000
Reexamination Certificate
active
06264442
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to positive displacement pumps for gases and more specifically to a positive displacement pump having a pair of pistons operating out of phase and specially configured rotary inlet and outlet valves.
Positive displacement pumps for liquids and gases typically include one or more piston and cylinder assemblies and associated inlet and outlet valves which control the flow of pumped fluid into and out of the cylinders. Such pumps are typically capable of relatively high pressure rise operation. A drawback of such positive displacement pumps is that both the inflow and outflow are distinctly pulsatile in character and, especially with high pressure pumps, the flow rates are generally relatively small.
Furthermore, the ability to adjust pressure and flow rates with such pumps can be problematic. Typically, of course, flow rates may be adjusted simply by reducing the speed of the pump. However, such a speed reduction to reduce output flow rate is typically accompanied by a reduction in the output pressure as well.
It is apparent from the foregoing that a positive displacement pump which addresses the problems of output pulsation and controllable flow characteristics would represent an improvement over currently available devices.
SUMMARY OF THE INVENTION
The present invention is directed to a high volume, positive displacement pump which provides a flow rate having temporal fluctuations which are a smaller fraction of the time mean value than those of conventional positive displacement pumps and is a higher flow rate, smaller pressure rise device than conventional positive displacement pumps.
A positive displacement pump for heating, cooling and ventilating applications includes a pair of pistons operating out of phase which provide pumped fluid to a common output. Each of the pistons is associated with an inlet valve array which includes a plurality of rotary inlet valves arranged along opposed, preferably vertical, sidewalls of the cylinders to control the influx of fluid. A rotary outlet valve is also associated with each piston and includes a rotating valve body disposed transversely across the cylinder head which rotates in synchronism to open a through, radial port in the valve body in timed relationship to the piston travel. A drive motor rotates a crankshaft and cams which control actuation of the inlet and outlet valves. The phase relationship between the operation of the inlet and outlet valves and the respective pistons is fixed. The positive displacement pump finds particular application in heating, ventilating and air conditioning (HVAC) apparatus and applications.
Thus it is an object of the present invention to provide a high volume, positive displacement pump.
It is a further object of the present invention to provide a positive displacement pump suitable for applications in HVAC apparatus.
It is a still further object of the present invention to provide a positive displacement pump wherein rotary inlet and outlet valves operate in synchronism with reciprocating pistons.
It is a still further object of the present invention to provide a positive displacement pump wherein the phase relationships of the inlet and outlet valves are fixed relative to the reciprocating pistons.
Further objects and advantages of the present invention will become apparent by reference to the following description of the preferred and alternate embodiments and appended drawings wherein like reference numbers refer to the same component, element or feature.
REFERENCES:
patent: 3875810 (1975-04-01), Paramonoff
patent: 3981620 (1976-09-01), Abrahams et al.
patent: 4007725 (1977-02-01), Weaver
patent: 4244338 (1981-01-01), Rassey
patent: 4773364 (1988-09-01), Hansen et al.
patent: 5410996 (1995-05-01), Baird
patent: 5706775 (1998-01-01), Schweter et al.
patent: 5720241 (1998-02-01), Gail
patent: 5993654 (1999-11-01), Black
Board of Trustees operating Michigan State University
Brinks Hofer Gilson & Lione
Tyler Cheryl J.
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