MOTOR CENTRIFUGAL PUMP

Description

The invention relates to a motor centrifugal pump having a plastic extrusion-coated stator core for the electric motor.

Extrusion coating of the stator core of an electric motor with plastic is known. One drawback of such extrusion coating is that the plastic used represents a good thermal insulator. The embedded stator is subjected to high thermal stress, and it is difficult to release large amount of high heat to the surroundings or to the coolant. Furthermore, the known wet rotor pumps for heating water and service water are composed of numerous parts that must be assembled. A large number of installation steps is necessary in particular for assembly of the encapsulated electric motor.

The object of the invention is to reduce the temperature of the stator and in particular also of the motor electronics system for motor centrifugal pumps of the above-described type, by use of a simple design.

This object is achieved according to the invention by forming the plastic with cooling passages through which the pumping medium flows.

In this manner the high temperatures at the stator and the electronics system needed for regulating and controlling the pump are reduced by use of medium-filled cooling passages or chambers. Extrusion coating of the electric stator greatly reduces the number of individual parts, and thus minimizes manufacturing and installation effort. Several functions are provided by the extrusion coating.

Advantageous embodiments of the invention are given in the dependent claims.

Four illustrated embodiments of the invention are illustrated in the drawing and described in greater detail below.

In the drawing:

FIG. 1 is an axial section of a first illustrated embodiment of an electric motor with a pump impeller;

FIG. 2 is an axial section of a second illustrated embodiment of an electric motor with a pump impeller;

FIG. 3 is an axial section of a third illustrated embodiment of an electric motor with a pump impeller; and

FIG. 4 is a cross section of a fourth illustrated embodiment of an electric motor.

The motor centrifugal pump has a motor shaft 1 having a motor axis 2. The motor shaft 1 is supported in two radial bearings 3 and 4 and one axial bearing 5 inside the rotor compartment 6. On the hydraulic side the motor shaft 1 projects from the electric motor, and at this end carries the pump impeller 7 that is inside the pump housing (not illustrated).

The rotor 8 is fixed to the shaft 1 in the rotor compartment 6, which in turn is surrounded by windings 9 and a stator core 10.

The rotor compartment 6, windings 9, and stator core 10 are imbedded in a plastic mass 11 that is introduced, in particular injected, between these parts in the form of a filling compound, and that preferably forms the inner wall of the rotor compartment 6, so that an additional split case is not necessary since the plastic forms the split case. In addition, it is not necessary for the plastic mass to be surrounded by an external motor housing; instead, the plastic itself may form the exterior of the motor.

Formed in the plastic mass 11, outside of and next to the rotor compartment 6 and parallel to the motor axis 2, are cooling passages or cooling chambers 12 that are preferably situated between the windings 9 and connected to the pump chamber on the hydraulic side via openings (not illustrated), so that the pumping medium moved by the pump impeller 7 for cooling the motor flows through the cooling passages 12.

As shown in the embodiment of FIG. 2, it is not absolutely necessary for the cooling passages 12 to be connected to one another; instead, sufficient medium exchange with the pump chamber may occur within the cooling passage through the connecting opening or openings in the cooling passage. In the illustrated embodiment according to FIG. 1, however, the cooling passages 12 are connected to one another via transverse passages or a transverse chamber 13 situated on the end of the motor facing away from the pump impeller 7, outside the rotor compartment 6. The transverse chamber 13 is sealed off by a lid-shaped element 14, in particular made of plastic, which separates the interior of an electronics housing 15 from the motor interior. The board 16 of the motor electronics system lies against the outer side of this circular part 14 from which the motor axis 2 extends perpendicularly, so that the electronic parts are cooled by the liquid in the transverse chamber 13.

The electronics housing 15 is preferably fastened to the plastic mass 11 by means of screws 17 extending parallel to the motor axis 2. The electronics housing 15 is thus fastened on the end of the motor facing away from the hydraulic area.

The transverse chamber 14 is connected to the rotor compartment 6 via an opening, in particular a coaxial passage 18, so that the pumped liquid flows through the cooling passages 12, the transverse chamber 13, the passage 18, and the rotor compartment 6, and back to the pump chamber via openings (not illustrated). The illustrated embodiment according to FIG. 3 shows that a design is also possible in which there is no connection between the transverse chamber 13 and the rotor compartment 6. Inside the rotor compartment 6, on the side facing away from the pump impeller 7 and thus close to the transverse chamber 13, coaxially molded onto the plastic mass 11 is a plastic collar 19 in which the radial bearing 4 rests, so that the collar 19 forms a secure seat for this bearing. In addition, the other bearings may optionally or additionally be held by projecting parts of the plastic mass 11.

FIG. 4 illustrates sections of the illustrated embodiments according to FIGS. 1 through 3, and shows a triangular cross-sectional shape of the cooling passages. In other designs not illustrated, the cooling passages may have other cross-sectional shapes, and may also be connected to one another via other connecting passages (not illustrated) to form one, two, or more circuits.