Pumps – Expansible chamber type – Mechanically actuated distributor
Reexamination Certificate
1999-01-28
2001-03-13
Thorpe, Timothy S. (Department: 3746)
Pumps
Expansible chamber type
Mechanically actuated distributor
C137S050000, C137S628000, C251S215000
Reexamination Certificate
active
06200111
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to positive displacement pumps for liquids and gases and more specifically to a controllable positive displacement pump having a pair of pistons operating out of phase and specially configured and controllable inlet 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 pump 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 controllable, 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, is characterized as a higher flow rate, smaller pressure rise device in comparison to conventional positive displacement pumps and readily permits independent control of the intake and exhaust valve phasing and cycle times.
A controllable positive displacement pump for liquids and gases which may contain dispersed phase particles 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 which includes a fixed grating defining slots which extend parallel to piston travel and a complementarily configured grating which reciprocates transversely in timed relationship with the piston to control the influx of fluid. A rotary outlet valve is also associated with each piston and includes a rotating member disposed transversely across the cylinder head which rotates in synchronism to open a through, radial port in the member in timed relationship to the piston travel. The phase relationship between the operation of the inlet and outlet valves and the respective pistons may be adjusted by using either independent drive mechanisms to these components or incorporating mechanical phase adjusting devices in the unitary drive mechanism. The positive displacement pump finds particular application to transport powder paint and in heating, ventilating and air conditioning (HVAC) apparatus.
Thus it is an object of the present invention to provide a controllable, positive displacement pump.
It is a further object of the present invention to provide a controllable, positive displacement pump suitable for applications such as transport of powder paint and in HVAC apparatus.
It is a still further object of the present invention to provide a controllable, positive displacement pump wherein inlet and outlet valves operate in synchronism with reciprocating pistons.
It is a still further object of the present invention to provide a controllable, positive displacement pump wherein the phase relationships of the inlet and outlet valves may be adjusted 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: 1060803 (1913-05-01), Welch
patent: 2889783 (1959-06-01), Woydt
patent: 3266435 (1966-08-01), Smith
patent: 4787822 (1988-11-01), Bennett
patent: 5375625 (1994-12-01), Reynolds
patent: 5690567 (1997-11-01), DeNijs
Brinks Hofer Gilson & Lione
Gartenberg Ehud
Thorpe Timothy S.
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