RELATED APPLICATION

This application claims priority to GB application 0912515.4, which was filed Jul. 17, 2009.

BACKGROUND OF THE INVENTION

This application relates to the use of a vapor detector for detecting gas in a liquid flow in a magnetic drive pump.

Magnetic drive pumps are known, and typically include a magnetic coupling that drives a centrifugal pump impeller. A motor drive is connected to the outer magnetic rotor of the magnetic coupling. The inner magnetic rotor of the magnetic coupling is connected to the pump impeller. A sealing wall is positioned between the outer magnetic and inner magnetic rotors, and provides a complete fluid seal, ensuring that the outer magnetic rotor is maintained in a â€œdryâ€ side. Liquid circulates within a â€œwetâ€ side in the interior of the wall. The centrifugal pump impeller moves liquid from an inlet to an outlet.

Prior art has comprised a bubble detector for detecting bubbles, or other gas within the liquid that has been positioned in the wet side of the pump.

SUMMARY OF THE INVENTION

A magnetic drive pump includes a magnetic coupling that drives a centrifugal pump. A motor drives the outer magnetic rotor of the magnetic coupling. The outer magnetic rotor is positioned radially outward of a sealing wall. The inner magnetic rotor is positioned radially within the sealing wall. Rotation of the outer magnetic rotor causes the inner magnet rotor to rotate. The inner magnet rotor drives a centrifugal pump impeller to move a liquid. A bubble detector is positioned outward of the wall such that it is in a dry side of the pump. The bubble detector sends a signal into the wet side of the pump to identify the existence of a gas within a pump liquid.

These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view through the inventive pump.

FIG. 2 is a detail of the mounting of a bubble detector probe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A magnetic drive pump is illustrated in FIG. 1 having a sealing wall 22 separating a dry side 23 from a wet side 40 for a fluid pump. A separate motor drives a shaft 28, through a bearing housing 24. Shaft 28 drives an outer magnet rotor 30, which is positioned outward of the wall 22. Magnetic flux passes through the wall 22 and drives an inner magnet rotor 32. A centrifugal pump impeller 34 is connected to the inner magnet rotor 32. Fluid passes from an inlet 35 to the impeller 34, and is driven to an outlet 37.

A bubble detector probe 36 is positioned outward of the wall 22 and communicates with a control 38. The probe may be an ultrasonic probe that will transmit and receive an ultrasonic signal. The signal transmission through liquid, is different to the signal transmission through gas. Therefore, the probe can determine whether the fluid inside the wet chamber is liquid, gas or a mixture of liquid and gas.

The magnetic drive pump includes a â€œwetâ€ side 40, which receives some of the liquid being pumped by the impeller 34, such that the liquid can circulate around the components radially within the sealing wall 22. In addition, a â€œdryâ€ side 23 is positioned radially outward of the wall and does not receive the liquid. Probe 36 is positioned in the dry side 23.

As can be appreciated, the probe 36 faces a portion of the wet side 40 spaced away from the impeller 34. This positioning aligns the probe 36 with a portion of the chamber that is separated from the impeller by a housing wall 100.

As can be appreciated from FIG. 2, and with reference to FIG. 1, the probe 36 is positioned to be opposite a bushing holder 100. An outer housing wall 101 receives an olive/nut arrangement 110 to clamp and hold the probe into the housing.

The sealing wall 22 is formed of non-magnetic material. The technology for forming an appropriate ultrasonic transmitter to send a signal through the wall 22, and against the opposed surface, is known. Essentially, the controller 38 will be able to determine if bubbles of vapor or gas are within the pump fluid by analyzing the returned signal. While the technology for providing such a probe is known, such a probe has not been utilized in this non-invasive manner.

Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.