Pumps – Motor driven – Electric or magnetic motor
Patent
1998-01-13
1999-10-26
Thorpe, Timothy S.
Pumps
Motor driven
Electric or magnetic motor
417 63, 137854, 137856, F04B 1703
Patent
active
059717238
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a diaphragm dosing pump with a rotary driving motor for the working diaphragm and a pump head with an inlet valve and an outlet valve.
Dosing pumps are already known which operate with a lifting magnet drive and accordingly perform very rapid working strokes, so that a correspondingly high dosing speed is obtained. The product to be dosed is then ejected with high speed. In many instances of use, however, slow delivery of the medium is desired. If a dosing pump is used which is capable of delivering continuously at very slow speeds, such impulsive delivery is indeed avoided, but sealing problems are encountered at the inlet valve and outlet valve, as arise in slow-running dosing pumps as a result of the small pressure differences.
SUMMARY OF THE INVENTION
The object underlying the present invention is to provide a diaphragm dosing pump operating with a rotary driving motor, with which only small pressure peaks occur during operation and which permits exact dosages even at low operating speed and with small dosing quantities. In addition, the design should permit dosing pumps of very small size.
To accomplish this object it is proposed according to the invention particularly that the rotary driving motor is electrically connected to control electronics, that the latter and the motor are designed for operation with a predeterminable starting position of the driven working diaphragm at the beginning and end of each dosing operation, that the inlet and outlet valves are designed with elastic valve disks which in the closed position have one face lying upon the opening edge which forms a valve seat and belongs to an inflow passage, that on the valve disc-side facing away from the inflow passage, within the projected extension of the inflow passage, there is a rib-like stop provided supporting the valve disc in the open position of the valve, and that the valves in each case compose complete, interchangeable units and take the form of valve inserts including a stop plate presenting the stop and an outflow passage and further including a valve mounting plate and the valve disc.
To be sure, a diaphragm pump is known from DE-A-41 18 652, which has inlet and outlet valves with elastic valve disks. However, this publication does not disclose control electronics for a dosing operation of the pump. What is more, the valves do not take the form of interchangeable units. A dosing pump is known from FR-A-2 588 319 with which partial quantities can be dosed within a total working stroke. Finally, a dosing pump is known from EP-A-0 321 339 which is equipped with a control for changing the number of strokes and speed. None of these publications shows the combination of features of the dosing pump according to the present invention, which thereby operates to especial advantage with respect particularly to the vacuum characteristics and to the accuracy of dose even with low operating speeds.
By means of the controlled driving motor, low operating speeds, and in conjunction with the predeterminable starting position, also high repeat accuracy of dose can be realized, without high pressure peaks and pulsations occurring during the dosing operation. Small pressure peaks result in advantages, among others in the blending, and furthermore by this means lesser demands are made on the sealing of the pump. The envisaged design of the valves in conjunction with the operational characteristics of the pump results in a practically non-overlapping interplay of the suction valve and pressure valve and good sealing even with the only small pressure differences occurring during operation. By this means the pump has good vacuum characteristics even at low operating speed.
As a result of the complete valve inserts provided, the parts for them can be manufactured independently of the pump head in which the valve inserts are positioned. Particularly in plastics manufacture, this presents considerable advantages with respect to accuracy in terms of injection molding. Were the valve parts to
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patent: 3807445 (1974-04-01), McPhee
patent: 4550749 (1985-11-01), Krikorian
patent: 4762149 (1988-08-01), Picki, Jr.
patent: 4838262 (1989-06-01), Katz
patent: 4925371 (1990-05-01), Griesmar
patent: 5676531 (1997-10-01), Muscarella et al.
Bolt Erwin
Durrer Traugott
Gartenberg Ehud
KNF Flodos AG
Thorpe Timothy S.
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