Centrifugal pump, particularly for fountains

Pumps – Including disengageable rotary or frangible drive connection

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Details

415141, 4174237, F04D 2924, F04D 1302

Patent

active

057116571

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a centrifugal pump, particularly for fountains and aquariums.
Known pumps of this type are equipped with a single-phase synchronous electric motor with a synchro-generator winding in the stator, which sees to it that the motor starts in the specified direction of rotation. Since the specified direction of rotation of the motor is ensured, it is also possible to use an impeller, which depends on the direction of rotation. A higher degree of hydraulic efficiency can be achieved with spiral-shaped impeller blades than with a rotation-dependent impeller with radially-extending impeller blades. However, the impeller-related advantages achieved, which are reflected in the motor power required, the manufacturing costs and the overall size, are partly offset by the costs of the auxiliary winding circuit in the stator. Especially in the area of smaller pumps for use within the home and garden, not only the possibility for connecting to a single-phase power supply, but also the need for an extremely inexpensive and compact construction should be taken into consideration.


SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a centrifugal pump, which is distinguished because it can be produced simply and inexpensively and is compact and robust without a significant loss in overall efficiency.
The inventive solution provides for the use of a single-phase synchronous motor with a permanent magnet rotor without any additional auxiliary winding as the driving mechanism. The direction, in which such a motor starts, is fixed by the reaction of the impeller. This is made possible by means of constructing the spiral-shaped impeller blades flexibly in such a way that, when the single-phase synchronous motor starts in the direction opposite to the specified direction of rotation of the spiral-shaped impeller, the impeller blades prop open in the radial length. Since, on the one hand, the direction of rotation of the impeller is "open" depending on the starting direction of such a single-phase, synchronous motor and, on the other, a useful hydraulic efficiency can be achieved by a spirally-shaped impeller only if the "correct" direction of the impeller is maintained, the invention provides that the impeller itself selects the "correct" direction of rotation. If the motor initially starts counter to the correct direction of rotation or hunts against the correct direction of rotation when starting up, the impeller blades stand up, as a result of which the water resistance is increased significantly and the motor is decelerated. With the tendency of the single-phase synchronous motor to hunt when starting up and with the preferred direction of rotation determined by the impeller, the motor is fore, ed to start in the correct direction of rotation.
Further details and advantages of the invention arise out of the following description and the accompanying drawings.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal section through a centrifugal pump,
FIG. 2 shows a plan view of the motor and pump impeller of the centrifugal pump of FIG. 1 without motor and pump housing,
FIG. 3 shows a sectional view along the line III--III of FIG. 2,
FIG. 4 shows a side view of the rotor and impeller of the centrifugal pump of FIGS. 1 to 3, axially pulled apart,
FIG. 5A shows a section along the line V--V of FIG. 4,
FIG. 5B shows a section taken along the line 5B--5B of FIG. 5A.
FIG. 6 shows a further embodiment of an impeller in a sectional view corresponding to that of FIG. 5, and
FIG. 7A shows a sectional view of a third embodiment of an impeller in sectional view, similar to that of FIGS. 5 and 6, together with an associated pump housing, and
FIGS. 7B and 7C are partial sectional views similar to FIG. 7A showing other relative positions of the impeller.


BRIEF DESCRIPTION OF THE DRAWINGS

The centrifugal pump, shown as a whole in longitudinal section in FIG. 1 and labeled 1, comprises a single-phase induction motor 2 with an external stator 3 and an

REFERENCES:
patent: 2684035 (1954-07-01), Kemp
patent: 2899902 (1959-08-01), Bandli et al.
patent: 2986095 (1961-05-01), Namar
patent: 3510229 (1970-05-01), Smith
patent: 4008985 (1977-02-01), Schemmann et al.
patent: 4755105 (1988-07-01), Blakeslee et al.
patent: 4861468 (1989-08-01), Willinger et al.

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