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1. (GB1031646) Improvements in or relating to air blowers
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DRAWINGS ATTACHED & Ik Date offiling Complete Specification: Sept 28, 1964.
Application Date: Sept 26, 1963.
Complete Specification Published: June 2, 1966.
g Crown Copyright 1966.
dox at acceptance:-F 1 C( 2 C, 2 N) Cl:-F 04 d COMPLETE SPECIFICATION
Improvements in or relating to Air Blowers We, WATKINS & WATSON LIMITED, a British Company, and FRANK EDWARD MAYHEW DUCKER, a British Subject, both of 17, White Lion Street, Islington, London, N 1, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: -
This invention comprises improvements in or relating to air blowers of the class driven by an electric motor.
According to this invention, the blower and its driving motor are mounted within a soundproofed box having an air inlet and an air delivery connection for the blower and the motor is also enclosed in an auxiliary casing having an air inlet thereto fed from the blower and an outlet to atmosphere, the air from the delivery connection by-passing the auxiliary casing In this way the motor is cooled and the heat so removed from the motor does not increase the temperature of the air flowing in the blower delivery.
Such a blower arrangement may for instance be used for supplying the wind system of a wind organ and in this use has an important advantage With modern compact electric motors the heat generated is higher and it has been found that if the motor is allowed to be cooled by air flowing to the blower delivery, the functioning of the organ is adversely affected This is particularly true with modem organs of compact form where the volume of air required is much smaller than with older organs and also the air leaks are substantially smaller, which factors make the air turn over considerably less.
Preferably the air for motor cooling is tapped from the blower casing and when the blower has a single sided impeller the air tappings are conveniently from the rear side of the impeller disc It is found that tapping of sufficient cooling air can be made from this point without any marked effect on the air flow lPric through the blower delivery In such an arrangement vanes, for instance fixed radial vanes, may be provided to regulate the natural vortex flow in the air at the rear side of the impeller disc and so regulate the flow of cooling air.
Noise may be created by the cooling air flow and this must be prevented from issuing from the outlet to atmosphere from the box.
At the same time the connection forming the outlet to atmosphere must be very flexible to avoid transmitting vibrations and mechanical or magnetic noises It is found that a thickwalled tube of flexible foam or sponge material of the kind in which the cells communicate fulfils both functions The outer skin of this tube should preferably be sealed to prevent percolation of a significant amount of the air back into the interior of the sound-proofed box, thereby to avoid re-circulation.
In one construction, illustrated in the accompanying diagrammatic sketch, a blower of the single entry centrifugal type with a fully shrouded impeller and the driving motor 11 for the blower are suspended on springs 12 in a wooden box 13 which is lined with sound absorbing material The box has a removable lid.
The box 13 has in one wall, for instance the bottom wall, a baffled air inlet 14 which leads into the box on the side of the blower 10 remote from its inlet eye 10 a.
The box 13 also has a delivery connection on another wall, for instance a top or a side wall, which connection is joined by a flexible connection 16 to the blower delivery.
The flow into the connection may be controlled by a slide valve mounted on the box wall.
In order to prevent heat generated by the motor 11 from heating the air flowing into the delivery connection 15, the motor 11 is enclosed in an auxiliary casing 17 which is attached to the blower casing, which is fed with air through ports 18 opening into the in103 1646 No 37998/63.
terior of the blower casing to the rear of the impeller disc 10 b and which has a flexible outlet connection 19 to atmosphere Radial vanes 20 on the blower casing lead to the ports 18.
When the blower unit is operating air flows down the rear of the impeller to the ports 18 and then flows through the casing 17 to cool the motor 11 and through the outlet 19 to atmosphere.
The connections 16, 19 are of thick-walled flexible foam or sponge material of the kind in which the cells communicate.