GB1036092A - Improvements in or relating to centrifugal blowers - Google Patents

Abstract

1,036,092. Centrifugal blowers. SMITHS INDUSTRIES Ltd. April 8, 1963, No. 13974/63. Heading F1C. [Also in Division F4] In a centrifugal blower wherein an impeller 18 co-operates with two similar volute casings 20, 21, Fig. 1, the effective shape of each of which is variable so as to control the direction of outflow in relation to two outlet ports 33, 34 or 27, 28, Fig. 4, the two volute casings 20, 21 are disposed apart axially and each encircles the impeller 18 for substantially more than 180 degrees. The casings 20, 21 are separated by a transverse wall 14. The blower is applied to a vehicle heater and receives its air through louvres (not shown) in the vehicle, one or more openings 43, a heat exchanger 38 connected to the cooling system of the vehicle, and an opening 56 in a transverse wall 15. The casings 20, 21 have sheet-metal volute walls 29, 22 associated with an adjustable blade 31, 25 respectively. The blade spindles 32, 26 are connected by cranks (not shown) to a common operating lever (not shown) for conjoint adjustment of the blades to positions at which the air flow can only pass through the outlet ports 28, 34, leading to the windscreen for de-misting and de-frosting purposes, or through the ports 28, 34 and outlet ports 27, 33 leading to the vehicle interior. A spring (not shown) is associated with the operating lever to retain it in each position. The operating lever also controls a resistor in circuit with the electric driving motor 55 to increase the motor speed when the air is flowing only to the windscreen. A casting 50 secured to each end wall of the heater unit, has two openings located side by side below the transverse wall 14 and a third opening above the wall 14; one end wall has a port communicating with the former openings and the other end wall has a port communicating with the latter opening.