Sealed magnetic drive sealless pump

A magnetic drive sealless pump. The pump includes a casing having a fluid suction opening and fluid discharge opening. A shell is combined to the rear part of the casing, and the exterior of the shell is combined with a bracket having a motor for impelling and rotating a drive magnet. At the center of the shell is provided with a shaft enveloped with a bearing having a spiral fluid passage at the interior thereof. A capsule is provided between the bearing and the shell and at the interior of the capsule is provided with a driven magnet situated between the bearing and the drive magnet. The capsule is also extended into the casing and at the front of the capsule is provided with impeller. The impeller, capsule and bearing are integrated into one body for forming a rotating member having a thrust ring at the front and rear parts thereof, respectively, for preventing axial movements of the rotating member. Between the bearing and the capsule is an auxiliary circulating channel for cooling that has a convection effect for cooling at both the interior and exterior of the bearing without increasing the fluid leakage thereof, thereby preventing high temperatures from dry running of the pump.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The invention relates to a magnetic drive sealless plump having an auxiliary circulating channel for cooling between the bearing and the capsule thereof, such that cooling effect by convection exists at both the interior and exterior of the bearing thereof, thereby ensuring that excessive heat is not produced.

(b) Background of the Invention

FIG. 1shows a prior magnetic drive centrifugal pump, which includes a casing100combined with a shell200. At the front part of the casing100is a suction opening101and at the top thereof is a discharge opening102. At the center of the shell200is a shaft201enveloped with a bearing202further enveloped with a capsule203. In the capsule203is a driven magnet204and the capsule203is extended forward into the casing100. At the front of the capsule203is positioned an impeller205. During the rotation of the impeller205, the fluid thereof is lifted from the suction opening101to the discharge opening102through the impeller205. The driven magnet204is driven by the drive magnet206which is attached to a motor. And between these two magnets is a shell200to prevent entry of liquid from the outside. In a normal operation of the pump, the pressure difference between the input and output of the impeller205is employed to have a small amount of fluid thereof flow to the rear part of the impeller205through the passage between the outer side of the capsule203and the inner side of the shell200, and heat produced is taken away through a groove between the bearing202and the shaft201. Among the circulation route thereof (gaps A, B, C, D, and E), only gaps D and E have a convection effect for cooling. Thrust rings207are positioned adjacent the impeller205and the capsule203.

However, in an abnormal operation of the pump caused by malfunctions of control instruments, mishandling during operation, congestion caused by waste fluid, or insufficient suction liquid level for instance, may cause the pump to perform dry running. Since the medium of convection for cooling is air, which can only carry away a limited amount of heat, and therefore the temperature of the bearing202and the shaft201is rapidly elevated, thus resulting in serious damage of the pump. Once dry running takes place, the bearing202and the shaft201are abraded, and the capsule203is also deformed from the heat produced. More particularly, the capsule203is generally made of plastic that deforms easily from heat, further increasing the abrasion due to the dry running, and therefore the pump becomes unfit for its application.

In order to prevent deformation of the capsule203from heat, provision of additional heat resistant materials to the inner periphery of the capsule203has been attempted. However, the addition of the heat resistant materials thereof not only complicates the manufacturing process and increases the production cost, but also has unsatisfactory effects due to long-term dry running of the pump that causes the temperature of the bearing202and the shaft201to rise up to 220° C. Therefore, if heat produced is held within the pump in a contained manner, the result is unsatisfactory.

SUMMARY OF THE INVENTION

An object of the invention is to provide cooling effect by convection at both the interior and exterior of a bearing by disposing an auxiliary circulating channel for cooling purposes without increasing the amount of fluid leakage, thus achieving an optimal cooling effect and preventing damage of the pump from heat when dry running occurs.

The other object of the invention is to strengthen the bearing and keep it structurally unaffected from the additional channel using an external groove between the capsule and the bearing by paring the outer periphery of the bearing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 2, in accordance with the invention, the pump1comprises a casing11having a fluid suction opening111and a fluid discharge opening112, and a shell12combined to the rear of the casing11. The exterior of the shell12is combined with a bracket13having a drive motor14behind it. The center of the shell12receives a shaft121enveloped with a bearing122that is further enveloped with a capsule123. In the interior of the capsule123receives a driven magnet124and the capsule123is extended forward into the casing11. The impeller125is disposed at the front of the capsule123and a drive magnet126is disposed in a yoke15covering the rear part of the shell12such that drive magnet126is situated at the exterior of the driven magnet124. The drive magnet126is impelled and rotated by the rotation of the motor14, such that the driven magnet124is also rotated along with the capsule123, the bearing122and the impeller125. The fluid therein is then forwarded to the discharge opening112from the suction opening111through the impeller125. The front part of the capsule123is provided with the impeller125, and the impeller125, the capsule123and the bearing122are integrated into one body as a rotating member of the pump. At the front and rear parts of the rotating member are positioned with respective thrust rings127, for preventing axial movements of the rotating member. In the meantime, a gap is formed from the rear part of the impeller125to the outer periphery of the capsule123and along the rear part of the bearing122. The gap is further extended through a screw groove1221provided in advance (as shown inFIG. 3) to the interior of the impeller125, thus forming a channel for fluid circulation (as indicated by the arrow) to achieve a cooling effect.

The characteristics of the invention are that the between the bearing122and the capsule123there is provided with a circulating channel for cooling of the bearing, and convection effect for cooling exists at both the interior and exterior of the bearing122. The bearing122, apart from the screw groove1221(i.e. spiral groove) disposed at the interior thereof, at the outer periphery thereof is also configured with symmetrical ramps1222(as shown inFIG. 3) for forming channels128(shown inFIG. 2) between the capsule123and the bearing122. That is, the outer periphery of the bearing is configured to form chord-wise planar ramps1222. In the embodiment illustrated inFIG. 3, three (3) planar ramps1222are formed such that the cross-section of the bearing122is roughly triangular. Each of the planar ramps1222terminates near a forward end of the bearing122at an end wall1223. At a rear end of the bearing122, a perimeter flange is formed and separated by the planar ramps1222into plural flange segments1224. The channels128are in fluid communication with the screw groove1221through a rear gap130between the rear end of the bearing122and the thrust bearing127, forming a convective cooling passage inclusive of the channels128, the gap, and the screw groove1221. The channels128allow for convection (as indicated by the arrow), along with the screw groove1221, whereby an optimal cooling effect is provided at both the interior and exterior of the bearing122. Therefore, when the pump1runs dry, sufficient ventilation is still provided for cooling in order to keep the bearing122at low temperatures.

With reference toFIG. 2, it can be seen that a fluid passage129is formed in the capsule123in communication with each channel128near the forward (impellor) end of the bearing122, immediately behind the end wall1223. It can be seen that the fluid passage129brings channels128into fluid communication with the interior of the casing11surrounding the impellor125. As indicated by the directional flow arrow F, at least some fluid pumped by the impellor125is circulated behind the impellor125and toward the fluid passage129.

Conclusive from the above, in accordance wit the present invention, an auxiliary circulating channel for cooling is provided between the bearing and the capsule, and an external groove is formed along with the capsule. The external groove having a relatively simple structure does not affect the structural strength of the bearing, but also ensures that the bearing maintains low temperatures by providing the pump with an optimal cooling effect when the pump is under dry running conditions, thereby reducing the effects of wear and lengthening the life cycle of the pump. And while this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and adaptions may be made therein without departing from the true spirit and scope of the invention as defined by the appended claims.