FIELD OF THE TECHNOLOGY
The present utility model relates to ventilation products, and particularly to a drum fan.
BACKGROUND
FIG. 1 is a prior art drum fan with a cylindrical housing for protection purpose, wherein blades are all disposed in the interior of the cylindrical housing 1. Such drum fans can be classified into blade-front-mounted drum fans (see FIG. 2), blade-rear-mounted drum fans (see FIG. 3) and blade-middle-mounted drum fans according to positions of the blades.
In a blade-front-mounted drum fan as shown in FIG. 2, blades 2 are mounted in the interior of the cylindrical housing 1 adjacent to a front end face of the cylindrical housing 1, i.e., an outlet end of high-speed air flow. An air flow entering the drum fan is first guided and adjusted by the cylindrical housing into an air flow in an axial direction, and then accelerated by the blades 2 rotating at a high speed into a high-speed air flow directly out of the cylindrical housing 1. It is known from FIG. 2 that the high-speed air flow, after rushing out of the cylindrical housing, immediately spreads around at large angles and does not advance in the axial direction any longer so that the high-speed air flow cannot reach a long distance, and wind is supplied to a short distance. Hence, such drum fan cannot satisfy a long distance-wind-supply requirement, which is a drawback of the blade-front-mounted drum fan.
In a blade-rear-mounted drum fan as shown in FIG. 3, blades 2 are mounted in the interior of the cylindrical housing 1 adjacent to a rear end face of the cylindrical housing 1, i.e., an inlet end of air flow. An air flow entering the drum fan is first accelerated by the blades 2 rotating at a high speed, and then guided and adjusted by the cylindrical housing into an air flow that is in an axial direction and rushes out of the cylindrical housing. It is known from FIG. 3 that the air flow rushing out at a high speed still keeps advancing the in axial direction in a longer distance without spreading at large angles so that the high-speed air flow can reach a long distance and achieve a long-distance wind supply. However, the blade-rear-mounted drum fan is disadvantageous in an especially large noise, so the occasions of use thereof are limited.
As for a blade-middle-mounted drum fan, its blades are adjacent to a middle portion of the cylindrical housing. Although the drum fan has a noise not much different from the blade-front-mounted drum fan and supplies wind to a distance longer than the blade-front-mounted drum fan but by far shorter than the blade-rear-mounted drum fan, it is unlikely to satisfy a long distance-wind-supply requirement.
SUMMARY
An object of the present utility model is to overcome drawbacks in the prior art by providing a drum fan which supplies a large quantity of wind to a longer distance with a low noise.
In order to achieve the above object, the present utility model is implemented by the following technical solution:
The drum fan according to the present utility model comprises a cylindrical housing, a front grid guard at a front end face of the cylindrical housing, a rear grid guard at a rear end face of the cylindrical housing and fan blades for wind supply, wherein the fan blades are totally or partially disposed outside the rear end face of the cylindrical housing. Since the fan blades are totally or partially disposed outside the rear end face of the cylindrical housing rather than being totally disposed in the interior of the cylindrical housing as in prior-art drum fans, thereby avoiding turbulence generated by a prior-art impeller-rear-mounted drum fan when air flow enters the cylindrical housing, and reducing resistance of air flow into the cylindrical housing. Meanwhile, since impellers are rear mounted, air flow is sufficiently accelerated by fan blades rotating at a high speed inside the cylindrical housing 1 and adjusted into a high-speed converged air flow in an axial direction. As such, as compared with the prior-art drum fans, the drum fan according to the present utility model can provide a larger wind supply, supply wind to a longer distance and produce less noise.
As a further modification of the above technology, the rear grid guard is protrudingly provided at a location of the rear end face of the cylindrical housing, the fan blades are disposed in the interior of the rear grid guard, and the protruding rear grid guard protects the fan blades better.
As a further modification of the above technology, a rim of the rear end face of the cylindrical housing is flared into a horn shape in order to reduce resistance of air flow into the cylindrical housing.
A rim of the front end face of the cylindrical housing is flared into a horn shape in order to avoid the high-speed air flow from generating a turbulence at the outlet and reduce resistance of the high-speed air flow rushing out of the cylindrical housing.
Certainly, both of the rim of the front end face and the rim of rear end face of the cylindrical housing are produced into a flared horn shape such that the high-speed air flow is prevented from generating a turbulence at the outlet whilst resistance of air flow into the cylindrical housing is reduced, and the resistance of the high-speed air flow rushing out of the cylindrical housing is reduced so that a large quantity of wind is provided to a long distance with a low noise.
As compared with the prior art, the drum fan according to the present utility model has the following advantageous effects:
The drum fan according to the present utility model is a modification to a blade-rear-mounted drum fan. Since the fan blades are rear mounted, the advantage of the blade-rear-mounted drum fan supplying wind to a long distance is retained. Meanwhile, since the fan blades are partially or totally disposed outside the rear end face of the cylindrical housing, a turbulence generated when the air flow enters the cylindrical housing is avoid, and the resistance of the air flow into the cylindrical housing is substantially reduced so that the drum fan according to the present utility model is more advantageous than the prior art drum fans in performance and indexes such as amount of wind supply, wind supply distance and noise.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a drum fan in the prior art;
FIG. 2 is a schematic view of a blade-front-mounted drum fan in the prior art;
FIG. 3 is a schematic view of a blade-rear-mounted drum fan in the prior art;
FIG. 4 is an exploded schematic view of a drum fan according to a first embodiment of the present utility model (blades are all mounted outside a rear end face of the cylindrical housing);
FIG. 5 is an exploded schematic view of a drum fan according to a second embodiment of the present utility model (blades are partially mounted outside the rear end face of the cylindrical housing);
FIG. 6 is a schematic view of a drum fan according to the present utility model (a rear grid guard protrudes);
FIG. 7 is a schematic view of a drum fan when a rim of a front end face of the cylindrical housing is flared;
FIG. 8 is a schematic view of a drum fan when a rim of a rear end face of the cylindrical housing is flared; and
FIG. 9 is a schematic view of a drum fan when both a rim of a front end face and a rim of a rear end face of the cylindrical housing are flared.
DETAILED DESCRIPTION
Embodiment 1
As shown in FIG. 3 and FIG. 5, a drum fan according to the present utility model comprise a cylindrical housing 1, a front grid guard 3 at a front end face of the cylindrical housing 1, a rear grid guard 4 at a rear end face of the cylindrical housing 1 and fan blades 2 for wind supply, wherein the fan blades 2 are totally disposed outside the rear end face of the cylindrical housing 1. Since the fan blades 2 are totally disposed outside the rear end face of the cylindrical housing 1 rather than being totally disposed in the interior of the cylindrical housing 1 as in prior-art drum fans, thereby avoiding turbulence generated by a prior-art impeller-rear-mounted drum fan when air flow enters the cylindrical housing 1, and reducing resistance of air flow into the cylindrical housing 1. Meanwhile, since impellers are rear mounted, air flow is sufficiently accelerated by fan blades 2 rotating at a high speed inside the cylindrical housing 1 and adjusted into a high-speed converged air flow in an axial direction. As such, as compared with the prior-art drum fans, the drum fan according to the present utility model can provide a larger wind supply, supply wind to a longer distance and produce less noise.
As shown in FIG. 5, the rear grid guard 4 is protrudingly provided at a location of the rear end face of the cylindrical housing 1, the fan blades 2 are disposed in the interior of the rear grid guard 4, and the protruding rear grid guard 4 protects the fan blades 2 better.
In the present utility mode, in order to reduce resistance of air flow into the cylindrical housing 1, as shown in FIG. 7, a rim of the rear end face of the cylindrical housing 1 is flared into a horn shape. Besides, a rim of the front end face of the cylindrical housing 1 is flared into a horn shape in order to avoid the high-speed air flow from generating a turbulence at the outlet and reduce resistance of the high-speed air flow rushing out of the cylindrical housing 1, as shown in FIG. 8.
Certainly, as shown in FIG. 9, both of the rim of the front end face and the rim of rear end face of the cylindrical housing 1 are produced into a flared horn shape such that the high-speed air flow is prevented from generating a turbulence at the outlet whilst resistance of air flow into the cylindrical housing 1 is reduced, and the resistance of the high-speed air flow rushing out of the cylindrical housing 1 is reduced so that a large quantity of wind is provided to a long distance with a low noise.
Embodiment 2
Embodiment 2 is substantially identical with Embodiment 1. The difference therebetween is as follows: as shown in FIG. 4, the fan blades 2 are partially disposed at a location outside the rear end face of the cylindrical housing 1. Since the fan blades 2 are partially disposed outside the rear end face of the cylindrical housing 1 rather than being totally disposed in the interior of the cylindrical housing 1 as in prior-art drum fans, thereby avoiding turbulence generated by a prior-art impeller-rear-mounted drum fan when air flow enters the cylindrical housing 1, and reducing resistance of air flow into the cylindrical housing 1. Meanwhile, since impellers are rear mounted, air flow is sufficiently accelerated by fan blades 2 rotating at a high speed inside the cylindrical housing 1 and adjusted into a high-speed converged air flow in an axial direction. As such, as compared with the prior-art drum fans, the drum fan according to the present utility model can provide a larger wind supply, supply wind to a longer distance and produce less noise.
The present utility model is not limited to the above embodiments. If various modification or variations to the present utility model do not depart from the spirit and scope of the present utility model, the present utility model also intends to contain the various modifications and variations if they fall within the scope of claims of the present utility model and equivalent technologies.
Patent Application
20110293415
