Patent GB-459644-A (GB)
Title: Arrangements for reducing noise in vacuum cleaners
IPC: A47L9/00
Filed: 1936-06-02
Abstract: 459,644. Silencing vacuum cleaners. LINKE, P., 53, Ringbahnstrasse, Tempelhof, Berlin. June 2, 1936, Nos. 15448 and 15449. Convention dates, June 13, 1935 and Nov. 19, 1935. [Class 8 (i)] [See also Group XXVII] In a vacuum cleaner having an arrangement for deadening the sound by leading the air leaving the blower through relatively offset openings provided in a number of walls spaced from one another and disposed substantially at right angles to the axis of the vacuum cleaner, the annular space between the electromotor and the cylindrical outer casing of the cleaner is used to accommodate the sound deadening arrangement, so that the spaced walls surround the electromotor. In the construction shown in the top half of Fig. 2, the cap 5 closing off the electromotor 3 from the blowing branch 4 is connected by a flange 6 with a cylindrical casing 7 extending partly over the stator 8 of the motor and supported on the casing wall 11 by a flange 9 provided with openings 10. A number of rings 1 are pushed over the casing 7, each ring being of U-section and having an end face provided with a number of equally spaced rectangular slits 2. The slits 2 of the first ring 1 register with the openings 10 in the flange 9 ; the slits 2 of successive rings are out of register. The rings 1 are forced against the flange 9 by a ring 13. Part of the air from the blower 12 flows directly to the inlet of the rings 1 and the remainder flows through the stator 8 of the motor 3 and is deflected by the cap 5 through the gap 14 between the stator 8 and casing 7 into the space 15 between the stator 8 and the cleaner casing and thence through the rings 1 and between the cap 5 and end cap 16 into the blowing branch 4. In the modification shown in the lower half of Fig. 2, the rings are disposed within the casing 71. The air passing through the stator 8 is deflected through the gap 14<1> and space 15<1> into the rings, the slits in the last ring registering with openings 10<1> in the flange 6<1>. In the above forms the flange 9, 9<1> is gripped by a rubber ring 30 of U-section clamped between the edge of the casing 11 and the edge of the cylindrical part 20 of the end cap 16. Alternatively the casing 7 may be supported on the motor, e.g. on the stator 8, instead of on the cleaner casing, its flange having openings for the passage of air from the gap 14 into the space 15, and a rubber ring being interposed between the stator 8 and casing 7 to prevent the mechanical transmission of sound. In a further modification, Fig. 3, the blower 12 with flangedon motor 3 is mounted in the casing 11 by a rubber ring 24 axially compressed by a pressure ring 26 drawn by screws 25 against the blower 12. The ring 26 is formed integrally with a cylindrical casing 27 which surrounds the motor 3 being spaced from the stator and provided near the brush caps 18 with recesses 21. The rings 1 fit over the casing 27 and within the casing 7<11> of a cap 6<11> secured by a screw 28 to the bearing plate 17 of the motor frame, the rings being held between shoulders 6<11> and 19 of the casing 7<11>. The air flows through the stator and through the space 14<11> between the stator and casing 27, passes through the gap 29 between the casing 27 and cap 5<11>, through the rings 1, and thence through the space 22 between the casing 7<11> and the cleaner casing to the blowing branch 4. The pressure ring 26, casing 27 and parts 5<11>, 7<11> may be made of sheet metal or of bad sound conducting material or may be covered with such material. The rings and cover cap may be made of bad sound conducting material, e.g. artificial resin pressed material, wood, hard pulp, ebonite, &c. Various arrangements of rings are described, and one of the rings may be of I-section.