DE2509663A1 - Centrifugal pump directly coupled to electric motor - has pilot impeller coupled to shaft with main impeller loose - Google Patents

Abstract

The pump has a motor with a stator and a permanent magnet rotor on a shaft. The shaft extends into the pump casing and carries a pilot impeller rigidly fixed to it. The back of the pilot impeller forms one face of a clutch. The main impeller is loose on the shaft of the side of the pilot impeller opposite the suction inlet and has blades surrounding the pilot impeller. It carries the other face of the clutch. When the motor starts the pilot impeller produces a hydraulic force which moves the main impeller axially into contact to be driven through the clutch. If the pump is overloaded the clutch slips, the main impeller loses speed and the motor is not overloaded.

Description

Radial centrifugal pump

The invention "relates to a radial centrifugal pump for liquids, with an electric motor drive and with an impeller _{or the like attached to the motor shaft for inevitable rotary driving}

The pump according to the invention is intended for wide range of applications, and should preferably be used as a filter pump in aquarium _o

With centrifugal pumps with an electric motor drive, critical problems arise from their load dependency. »When using an asynchronous motor, the motor speed decreases with higher loads and the current consumption of the motor increases, which results in the risk of overloading the motor.

ORIGINAL INSPECTED

609838/0091

When using synchronous motors, e.g. magnetic rotor motors, If the load is too high, problems arise with regard to the moment of entry and the moment of exiting. In many applications, however, load fluctuations are unavoidable; if the centrifugal pump for example is used in connection with a filter system, load fluctuations due to increasing Constipated

The invention is based on the object of creating a radial centrifugal pump in which the motor can run at its rated speed regardless of the load _{or the like}

Based on a radial centrifugal pump of the type mentioned at the outset, this object is achieved according to the invention achieved that the impeller directly connected to the motor shaft is designed as a small pilot impeller that on the the side of the pilot impeller facing away from the suction side is a second impeller, the delivery rate of which is several times greater than that of the pilot impeller, is mounted axially displaceably and loosely rotatable on the motor shaft and that the two impellers have coupling surfaces that are assigned to one another and lie in radial planes o

SO 9838/0091

When switching on the radial centrifugal pump designed in this way initially only the small pilot impeller is set in rotation, which means that the motor is only exposed to such a small load is that the occurrence of a synchronous motor is certain guarantees or “overloads an asynchronous motor is safely excluded · The pilot impeller causes a relatively weak pumping of liquid, but with that the formation of a suction in the liquid space on the rear side of the pilot impeller is associated · The in Larger impeller, which is axially displaceably mounted in this space, is pulled against the pilot impeller by this suction it touches itself so that the larger impeller is then carried along by the pilot impeller by frictional forces · The two The impellers and the motor are advantageously matched to one another in such a way that, when the load is set, the Both impellers are frictionally engaged so that the larger impeller is taken along without slipping On the other hand, the load is absorbed by the larger impeller, which is arranged as a load buffer such a case with a more or less large slip is taken by the pilot wheel, while the pilot wheel and the motor can continue to run at the nominal speed

In a further development of the invention it can be provided that the larger impeller consists of a disc which is attached to the Suction side bears a wreath of peripheral wings, which -

6 09838/0091

seen in the axial projection - enclose the smaller impeller. According to a further feature of the invention, the two running wheels can have wear-resistant surfaces on their coupling surfaces Be provided with clutch linings.

The subject matter of the invention is explained in more detail below with reference to an exemplary embodiment shown in the drawing described.

The drawing shows a motor housing 1 with a base 2 and a side wall 3 »which approximately in its center has an integrally molded tube 4 directed parallel to the wall 3, the interior of which is open towards the base 2 _e into the closed end wall 5 of the In the tube, a bearing axle 6 is embedded, on which a motor and rotor shaft 7 is rotatably mounted, which in turn carries a cylindrical, diametrically permanently magnetized rotor 8 in a rotationally fixed manner. On the outside of the tube 4- two diametrically opposite semicylindrical stator pole shoes 9 »10 are arranged, which are periodically magnetized via a magnet yoke and a coil 11 _e

A pump housing 12 is connected to the base 2 of the motor housing 1, and a spoked wheel 14 in its suction opening 13 is rigidly inserted, which sits on the axis 6. With the free end of the motor shaft 7 is a relatively small one

809838/0091

Is a pilot wheel 15 non-rotatably connected, which consists of a hub 16, a rear end plate 17 and of radial vanes 18 and is provided on its rear side as a coupling surface 19 formed or _e with a clutch facing.

On the side of the pilot impeller 15 opposite the suction side of the pump is a second, substantially larger one The impeller 20 is axially displaceable and loosely rotatable on the motor shaft 7. The impeller 20 also consists of a Guide hub 21, which points towards the engine, consists of a disk and a ring of peripheral rotating vanes 23, which are shown in FIG enclose the pilot impeller 15 in the position shown.

When the motor is switched on, only the pilot impeller 15 is initially set in rotation, which creates a suction in the liquid space behind the disk 17 which is essentially axial and opposite to the suction direction (arrows 24) of the pump. As a result of this suction is likely that also with a coupling face 25 'or ₀ a clutch facing provided disc 22 of the larger wheel 20 to the rear of the pilot impeller and is carried along by this by friction, after which the pump then runs at full power. If the load is higher, there is a slip between the two impellers 15, 20, which prevents the motor from being overloaded «

609838/0091

Claims (1)

Patent attorney 9 C Π Q R Dipl.-Phys. Rudolf Peerbooms / DUy0 Wuppertal-Barmen - 6 - Friedrich-Engels-Allee 349/351 Call 55 61 47 Expectations 1 _{0 /} / radial centrifugal pump for liquids, with an electric motor drive and with one on the motor shaft for an inevitable? Rotary drive attached impeller, characterized in that the impeller is designed as a small pilot impeller (15), that on the side of the pilot impeller facing away from the suction side a second impeller (20), the delivery rate of which is several times greater than that of the pilot impeller (15) »axially displaceable and is loosely rotatably mounted on the motor shaft (7), and that the two running wheels have coupling surfaces (19 »25) assigned to one another and lying in radial planes Radial centrifugal pump according to claim 1, characterized in that the larger impeller (20) consists of a disc (22) consists, which on the suction side carries a ring of peripheral flights (23), which - in the axial Seen projection - enclose the pilot impeller (15). » 609838/0091 Radial centrifugal pump according to Claims 1 and 2, characterized marked that the two wheels (15 * 20) on their coupling surfaces (19, 25) are provided with wear-resistant clutch linings, 609838/0091