Patent Publication Number: US-4547135-A

Title: Motor-pump unit

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a motor-pump unit consisting of a screw-spindle pump and having located, on the pump&#39;s pressure side, a slot-barrel motor with a rigid, preferably one-piece, motor pump shaft. In a known motor-pump unit of this type, the slot-barrel motor is connected, to the drive spindle of the screw-spindle pump with a pressure side throttle interval interposed. The shaft end of the slot-barrel motor lying spaced from the screw-spindle pump is supported within the envelope of the slot-barrel motor. Furthermore, the common drive shaft of the slot-barrel motor and screw-spindle pump is longitudinally bored through in order to relieve the interior of the slot-barrel motor from the delivery pressure of the pump. This design is highly practical for relatively large motor-pump units, but it is very expensive in the case of smaller dimensions, where the delivery pressure and also the axial thrust at the screw-spindle pump are better controllable by the structure. 
     SUMMARY OF THE INVENTION 
     Underlying the present invention, therefore, is the problem of reducing the construction expenditure for the foregoing motor-pump unit shaft arrangement mentioned at the outset, especially in the case of relatively small dimensions. 
     For the solution of this problem it is proposed according to the invention that the slot-barrel motor be connected to the pressure chamber of the pump and surround a part of the pressure chamber, the motor pump shaft being supported between the pump part and the motor part, the rotor of the slot-barrel motor being cantilevered on the free shaft end outside of the bearing and the stator part of the slot-barrel motor being placed in the manner of a pot over the rotor and being fastened to the pump. 
     Advantageous developments of the invention follow from the description and claims below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 illustrates an example of a design of a motor-pump unit according to the present invention. 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     A motor-pump unit is formed essentially by the screw-spindle pump 1 and the slot-barrel motor 2. In the screw-spindle pump the spindle package formed of drive shaft 3 and running spindles 4 and 5 is surrounded by a flow housing 6. The flow housing 6 is secured in the pump casing 7 proper, which has a connection for the suction line 8 and a connection for the pressure line 9 and is closed with a closure cover 10 on the suction side. On the pressure side the pump casing is provided with a neck 11, which centers on its inside diameter the bearing--a ball bearing 12 is represented--of the drive shaft as well as a spacer disk 13. The bearing and the spacer disk are fixed axially, on the one hand, by a ring collar on the pump casing, and on the other hand, by the tensioning sleeve 14 mounted in the pump casing. The spacing sleeve 13 limits the axial movability of the running spindles 4 and 5 toward the pressure side 15. The drive shaft 3 is extended beyond the ball bearing 12 and forms here the motor shaft 16 in which it holds cantilevered the rotor 17 of the slot-barrel motor 2. Through the fact that the drive shaft 3 is already twice supported in the flow housing 6 and in the ball bearing 12, a further bearing in the slot-barrel motor is no longer needed. The stator part 18 of the slot-barrel motor is, in the manner of a pot, telescoped over the rotor 17 and fastened to the screw-spindle pump 1 by means of the screws 19. The stator part 18 is centered with the barrel slot 20 on the outer diameter of the neck 11 of the pump casing. For reasons of stability, the hollow spaces in the stator part 18 between the barrel slot 20, the windings 21, and iron core 22 and the casing wall 23 are filled with a suitable casting resin. The stator thereby becomes very stable, so that it can be arranged without more ado, as here represented, on the pressure side of the pump. By filling with resin, further, the heat conductivity is increased, whereby the heat created in the windings is safely conducted away. The longitudinal bore 24 in the motor shaft part brings about prompt ventilation of the slot-barrel motor; furthermore, in consequence of the longitudinal bore a lubricating circulation can be developed in the slot-barrel motor. 
     The ball bearing 12 has a relatively large outside diameter. This is greater than the maximum radial interior dimension of the spindle package of the screw-spindle pump, which results from the external spacing of the running spindles 4 and 5. As a result of this step, or feature, and of the pot-type form of the stator part of the slot-barrel motor, a very simple construction and an orderly set-up, or assembly, from a single side results. After removal of the stator part 18 of the slot-barrel motor, the essential parts of the screw-spindle pump can be removed, without it being necessary to remove the pump casing 7 from the tube line.