Patent GB-733544-A (GB)
Title: Device for increasing pressure or speed of a fluid flowing in a pipeline
IPC: F04D29/04
Filed: 1953-11-06
Abstract: 733,544. Centrifugal and axial-flow pumps. BARTELS, H. G. Nov. 6, 1953 [Nov. 10, 1952; Dec. 23, 1952; May 13, 1953], No. 30740/53. Class 110 (1). In a pump arranged to be inserted in a pipeline and comprising a casing enclosing the pump impeller and its electric driving motor and spaced therefrom to form a flow passage for the fluid, the impeller or the impeller vanes automatically move, when the motor is switched off, from the operative position into a position in which the resistance offered to the flow of fluid through the pipe-line is reduced to a minimum. Alternatively, a free-wheel or other coupling is provided to allow the impeller to run idly in the fluid flow when the motor is switched off. Fig. 1 shows a pump in which the impeller vanes 5 are pivoted on the impeller hub so that, when the driving motor 2 is switched off, they are automatically moved to a position in which they are parallel with the impeller axis, as shown dotted. The movement may be effected by the fluid flow, a spring, or electromechanical means. When the motor is switched on again, the vanes are returned to the operative position either by the action of the fluid or by an electromechanical device. Supporting webs 61, 6<SP>11</SP> for the motor are preferably of helicoidal form to act as guide vanes. In a modification, the impeller vanes are retracted into the impeller hub by means of a spring when the motor is switched off. They are returned to the operative position by centrifugal force when the motor is switched on again. Alternatively, the vanes may lie against the impeller hub when in the inoperative position. Preferably, the vanes are linked together so as to move in unison. The impeller may be connected to the motor through gearing. There may be two impellers, one at each end of the motor. Or, two adjacent but oppositely rotating impellers may be driven by separate motors. Only part of the vanes or, in the case of two impellers, only one of the impellers, may be put into action when the motor is switched on. The other part, or the other impeller, is put into action when required by an electromechanical device. Fig. 5 shows a centrifugal pump in which the impeller 48 has been moved into the inoperative position by the fluid flow, a spring, gravity, or other electrical or mechanical means. When the motor is switched on, the rotor 42<SP>11</SP> is thrust into alignment with the stator, 42<SP>1</SP>, thus carrying the impeller 48 into the operative position. A shroud ring 49 carried by the impeller then covers the space between the impeller and the motor. The cross-sectional area of the space between the motor and the casing 44 is greater than that of the pipe-line 41. The impeller may be attached to the shaft by a screw thread so that when the motor is switched on the inertia of the impeller initially prevents it from rotating, so that it moves axially relative to the impeller shaft until it reaches the end of the screw thread. When the motor is switched off, the impeller is returned to the inoperative position by the fluid flow, a spring, or other electrical or mechanical means. Alternatively, the motor may be reversed for this purpose.