DE3123275C2 - Centrifugal pump for dishwashers - Google Patents

Abstract

This centrifugal pump has an overhung impeller (3), the inlet opening (2) of the pump being arranged on the front (10) of the impeller and the drive shaft (5) on the rear of the impeller (11) via a mechanical seal (7) through the pump housing ( 1) is performed. To prevent the mechanical seal from overheating, openings (8) are provided between two blades in the impeller, the blades (16) of which are positioned forward from the inlet to the outlet of the blade channels in the impeller rotation direction (9). The leading edges of the openings in the direction of rotation have a rounded (12) that is favorable for flow from the front (10) to the rear (11) and have storage ribs (13, 14, 15) on the lateral and trailing edges on the front of the impeller.

Description

The invention relates to a centrifugal pump with a cantilevered impeller for the transport of washing liquid from the sump of the washing container of a dishwasher into the spray arms, the suction nozzle of the pump being arranged on the front of the impeller and its drive shaft sealing on the back of the impeller through the housing wall is passed through, the impeller has one or more axial openings as well as blade channels widening from the inlet to the outlet, the blades of which are set forward in the direction of rotation of the impeller from the inlet to the outlet, the blade angle /? ₂ between 45 and 90 ° and the inlet angle / ?, up to 45 °.

It is known (DE-OS 17 03 530, DE-OS 15 03 763), the spray pressure of the circulation pump in dishwashers by venting the suction port of the pump to belittle. Under these conditions, the pump works at a lower pressure, i.e. also with a lower delivery rate and poorer efficiency. This underperformance of the pump will, however only consciously accepted for certain, optionally switchable, gentle wash programs in order to avoid the possibility to be able to work with a lower spray pressure. Disadvantage of this working method is that on the one hand the known cavitation phenomena occur to a greater extent, and on the other hand the There is a risk that an air bubble will form behind the impeller of the pump, which will cause it to overheat in a short time the existing mechanical seal

chen can.

In order to be sufficient for centrifugal pumps of the type described for the specified purpose It is also known to provide lubrication of the bearings and thus to prevent these bearings from overheating (DE-AS 22 39 124) that the impeller of the pump with regard to the air supply through the ventilation line a or has several axial openings. The rinsing liquid can reach the Get mechanical seal on the back of the impeller. In the case of the well-known impeller, its blades are curved backwards (Fig. 1), depending on the operating conditions and the design of the pump, an overpressure or underpressure occurs in the area of the mechanical seal, which can be compensated for by the known openings.

Furthermore, centrifugal pumps with impellers according to FIG. 2 are known ("The pumps" by Dr. Ing. Hellmuth Schulz, Springer-Verlag 1955, page 10), the forward curved Have blades and in which the pressure equalization to the mechanical seal is also still through the known breakthroughs can be controlled.

The centrifugal pumps with impellers that carry backwards or forwards curved blades and the familiar ones Have perforations, are relatively demanding when used in dishwashers large enclosed spaces, which has an unfavorable effect on the water consumption due to large collecting pans. at Smaller design of these pumps, the desired delivery rate is not achieved.

The invention is based on the object of creating a centrifugal pump that is small in size and a high delivery rate is suitable for use as a circulation pump in dishwashers and Has means for sufficient pressure equalization on the axial seal.

According to the invention, this object is achieved by the features of claim 1. Advantageous configurations are specified in claims 2 and 3.

The invention is described below with reference to the drawing. It shows

F i g. 1 is a view of the bladed side of the known Impeller of a centrifugal pump, with the blades curved backwards against the direction of rotation are,

F i g. 2 a known impeller, the blades of which are curved forward in the direction of rotation,

F i g. 3 the blade arrangement of the impeller used in the centrifugal pump according to the invention, wherein the blades are bent forward in the direction of rotation,

F i g. 4 shows a section of the impeller according to the invention,

F i g. 5 shows a section A-B according to FIG. 4,

F i g. 6 shows a section CD according to FIG. 4,

F i g. 7 shows an axial section through the centrifugal pump.

The centrifugal pump has a pump housing 1 with an inlet opening 2, which is connected to the sump is connected to a dishwasher, not shown. An impeller 3 is arranged in the pump housing, which is cantilevered on the shaft 5 connected to a motor 4. Sealing the passage of the Shaft 5 through the rear housing wall 6 takes place by means of an axial or mechanical seal 7. The disc of the impeller is provided with openings 8 to seal side between the impeller disc and the Housing wall of pent-up air, the outflow to

allow suction side of the pump, so that flushing liquid to cool the mechanical seal on the back of the impeller.

With the blade arrangement 16 of the impeller according to FIG. 3 can be used with the same high delivery rate as with the known impellers according to FIGS. 1 and 2 a build a smaller pump. The known openings are no longer sufficient to attach to the mechanical seal to maintain a minimum pressure.

To this.'. Purpose the openings 8 are formed in the impeller according to the invention so that the in Direction of rotation 9 leading edge of the opening one from the bladed front 10 to the rear 11 of the impeller aerodynamically shaped rounding 12 has. There are storage ribs on the sides and on the trailing edge of the opening 8 13, 14, 15, the increased flow from the bladed impeller face when the impeller rotates Steer into the gap between the rear of the impeller and the housing in the area of the mechanical seal.

For this purpose 3 sheets of drawings

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30th

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Claims (3)

Patent claims: 1. Centrifugal pump with cantilevered impeller for the transport of washing liquid from the sump of the washing container of a dishwasher into the spray arms, the suction port of the pump being arranged on the front of the impeller and the drive shaft of which is passed through the housing wall in a sealing manner on the back of the impeller, which The impeller has one or more axial openings as well as vane channels widening from the inlet to the outlet, the blades of which are set forward in the direction of rotation of the impeller from the inlet to the outlet, the blade angle ßi is between 45 and 90 ° and the inlet angle ß \ up to 45 °, thereby characterized in that one or more openings (8) are each arranged between two blades (16), that the edges of the openings (8) leading in the direction of rotation (9) one from the front (10) to the rear (11) of the impeller (3 ) have streamlined rounding (12) and that on the side and on the trailing edge (s) de s breakthrough on the front of the impeller storage ribs (13,14,15) or the like. Are provided. 2. Centrifugal pump according to claim 1, characterized in that the storage ribs (13,14,15) are U-shaped arranged and in the direction of rotation (9) without cover by the leading blade to round off (12) and the breakthrough (8) are open. 3. Centrifugal pump according to claim 1 and 2, characterized in that the storage rib (15) on the trailing Edge of the opening (8) is made approximately tangential to the trailing blade (16).