Abstract: An active noise control system for a three-dimensional space, including noise detecting means, sound generating means, noise control effect detecting means and a control device consisting of a phase of a wave signal fed from the noise detecting means wherein a plurality of noise control effect detecting means and sound generating means are disposed at a distance shorter than a wavelength of the noise to be controlled, and input signals of the respective sound generating means and output signals of the respective noise control effect detecting means are fed through filters, separately, to control the sound for active noise control. In case of an air conditioner, the noise control effect detecting means are disposed at positions where an air stream flowing through the air conditioner is not obstructed thereby.

Abstract: An air conditioner mounted on a vertical wall and an method, with the air conditioner including air intake ports and air exhaust ports provided on each side of and air conditioner body which contains heat exchangers, fans and motors. The air is drawn in from the sides of the air conditioner where it is heat-exchanged and then discharged from sides thereof.

Abstract: An impeller of a centrifugal blower includes a hub, a hub plate, a plurality of blades and a shroud. The hub plate has an outer diameter which is smaller than an inner diameter of the shroud and a portion of the blades existing in the difference between the diameters is provided with a parting plane of molds, whereby the impeller can be integrally molded by the injection molding.

Abstract: An air conditioning system including at least one water-cooling type air conditioning unit, a heat pump chilling unit, an ancillary heat exchanger in said water-cooling type air conditioning unit, and a cold and heat accumulating tank divided into two tank sections differing from each other in volume and the temperature of water contained therein. In a cooling mode, cold water of relatively high temperature and cold water of relatively low temperature are accumulated by operating the heat pump chilling unit at night, and when a normal heating operation is performed, the cold water of relatively high temperature is used as cooling water for a condenser of the water-cooling type air conditioning unit and when the water-cooling type air conditioning unit is inoperable as when power failure occurs at peak load, the cold water of relatively low temperature is supplied to the ancillary heat exchanger to carry out cooling.

Abstract: A centrifugal blower including a casing formed with a discharge port and a suction port, and an impeller mounted in the casing and having a plurality of backwardly curved vanes arranged circumferentially of the impeller. The suction port has a semicircular suction member located in spaced juxtaposed relation to a semicircular curled portion formed at the forward end of a shroud of the impeller. An annular guide plate may be attached to the inner side of the suction member and formed at its open end with a wall portion disposed along the shroud which is formed at its forward end with an annular wall extending into a space defined between the suction member and the guide plate. Hair may be provided on one of opposed wall surfaces of the suction member and the annular wall of the shroud.