| 摘要 |
PURPOSE:To achieve an even distribution of flow into a burner and reduce the space occupied by a fan by disposing the fan in a fan case whose front guide is longer than the rear guide, said guides being in a certain angular relation. CONSTITUTION:The length of a front guide 26 is larger than that of a rear guide 27, and, when the respective angles between a line perpendicular to a line connecting an imaginary winding start point 22 and the center of an impeller 21, and the front guide 26 and the rear guide 27 are designated by thetaf and thetar, there is a relationship of thetaf<0 deg.<thetar. Since the center of an air outlet 25 and the center of the impeller 21 can be made closer, the maximum length lx in the X-direction and the maximum length ly in the Y-direction which are the two-dimensional plane occupied by a fan 19 can be made smaller without reducing the angle of diffusion alpha and the outer diameter D2 of the impeller 21, i.e. without reducing the performance of the fan 19. Further, the flow blown from the air outlet 25 into an air chamber 4 tends to be drawn to the front guide 26 and so, the air can be supplied to a burner 8 opposite to the position of the fan 19 without providing the chamber 4 with a guide plate.
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