Pumps – Motor driven – Fluid motor
Reexamination Certificate
1999-08-12
2001-08-21
Thorpe, Timothy S. (Department: 3746)
Pumps
Motor driven
Fluid motor
C417S386000, C417S385000, C417S388000, C092S09800R, C092S096000
Reexamination Certificate
active
06276907
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to diaphragm pumps with increased efficiency due to improvements in the diaphragm and drive fluid systems. Such diaphragm pumps typically have an oil section driving a load fluid section, to pump paint for example.
BACKGROUND OF THE INVENTION
Diaphragm pumps for pumping paint and other fluids have been available for years for both industrial and commercial applications. Although these pumps have been meeting consumer and professional requirements, changes in the market and economy, including increased market competition and decreased profit margins, have increased the need for more cost effective production, cost reductions and improved pump efficiencies. In addition, the expansion of the consumer market has increased the need for varying pump configurations at a range of price levels.
A drawback of the current pump that becomes evident when the pump is used in varying configurations, is a loss of prime. Pooling of hydraulic fluid away from the fluid inlet of the pump can occur in different pump orientations, especially when the fluid inlet is located at an outer limit position within the pump. In these orientations, the hydraulic fluid portion of the pump takes in air or possibly runs dry causing numerous mechanical problems that usually must be repaired by a service representative, thereby causing time delays, extra costs and loss of productivity.
In view of the deficiencies of currently available pumps and the ever changing needs of consumers, a need exists for a diaphragm pump that doesn't lose prime no matter what its orientation and has improved efficiency without increasing manufacturing costs.
SUMMARY OF THE INVENTION
A diaphragm pump with improved efficiency and substantial elimination of priming problems at all orientations of the pump is provided in the present invention. The diaphragm pump includes a first chamber for accommodating and dispensing a fluid to be pumped, such as paint, and a second chamber for accommodating a drive fluid. A diaphragm separates the first chamber from the second chamber and has a first chamber side and a second chamber side. The diaphragm includes an outer perimeter mounting region, a thin inner perimeter flexible region, and a contoured central drive region having a stem on the second chamber side and a central pumping surface on the first chamber side. The diaphragm is movable from a first limit farthest away from the first chamber to a second limit closest to the first chamber. A motor mounted eccentric causes reciprocating movement of a piston located at least partially within the second chamber. The piston movement results in corresponding drive fluid movement within the second chamber, flexing the diaphragm to provide a pumping action within the first chamber for dispensing the fluid to be pumped.
The diaphragm pump also includes a drive fluid inlet for supplying drive fluid to the second chamber. The drive fluid inlet has a drive fluid supply passage formed axially within the piston having a first end and a second end, the first end of the supply passage open to the second chamber, and an input port formed within the piston transverse to the supply passage. One end of the input port intersects the supply passage near the second end of the supply passage, and the other end of the input port is at least partially open to a drive fluid supply at a predetermined position of the piston within the second chamber. As the piston reciprocates, the input port is closed to the drive fluid in the drive fluid supply during a portion of the reciprocating movement of the piston and the input port is open to the drive fluid in the drive fluid supply at another portion of the reciprocating movement of the piston. This results in an inflow of drive fluid through the input port into the supply passage and second chamber. When the input port is open it is continuously submerged in the drive fluid at all orientations of the pump, thereby substantially eliminating the introduction of air into the drive fluid system, and thus reducing priming problems in the drive fluid section.
The diaphragm pump of the present invention also includes a backing ring mounted within the second chamber adjacent to the diaphragm defining a central opening through which the stem of central drive region of the diaphragm passes. The backing ring has a plurality of holes configured to distribute the drive fluid across the diaphragm after the drive fluid is driven by the drive fluid movement within the second chamber through the plurality of holes. It also has a diaphragm mating surface contoured to mate with the second chamber side of the diaphragm As the drive fluid passes through the plurality of holes into a drive fluid volume defined between the diaphragm mating surface of the backing ring and the second chamber side of the diaphragm, it forces the diaphragm membrane from the first limit toward the first chamber while flexing the flexible region of the diaphragm toward the first chamber from the outer perimeter inward toward the central pumping surface in a rolling manner. Through this action, the diaphragm moves substantially all of the fluid to be pumped adjacent the diaphragm within the first chamber inward toward the central pumping surface and then out of the first chamber when the diaphragm reaches the second limit. Therefore, the efficiency of the diaphragm pump increases as more fluid is pumped with every stroke of the piston.
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Bekius Wayne M.
Cooper Robert D.
Johnson Shawn C.
Kruzel Thomas F.
Faegre & Benson LLP
Solak Timothy P.
Thorpe Timothy S.
Wagner Spray Tech Corporation
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