Patent Application
20160281730
The present disclosure relates to a fan assembly for a heating, ventilation and air conditioning (HVAC) system for a vehicle cab.
Operator stations or cabs of most agricultural vehicles are surrounded by large areas of glass so that the operator can see the area being worked or the product being produced or harvested. These large glass surface areas transmit a lot of light and result in a significant solar heat load being applied through the glass surfaces into the cab. This solar heat load along with engine cooling heat and exhaust heat in proximity to the operator station must be overcome by the cab HVAC system.
Such an HVAC system is described in U.S. Pat. No. 7,726,142, issued on 1 Jun. 2010 and assigned to the assignee of the present application. This system includes a centrifugal fan with backward curved blades which propel air through a series of heat exchangers in order to condition the air. It is desired to provide a fan for such a system which is quieter.
According to an aspect of the present disclosure, an impeller includes a base plate, a hub connected to the base plate and having a rotation axis, a plurality of first blades disposed on the base plate, and a plurality of second blades disposed on the base plate. The base plate has a circular outer peripheral edge. The base plate has a curved first plate surface which is joined to the surface of the hub, and a flat second plate surface opposite the first plate surface. The first and second blades project from the first surface.
Each of the first blades is spaced apart and positioned between a corresponding pair of second blades. Each first bade has an inner end connected to the hub and having a first inner axial length. Each first bade has an outer end spaced apart from the hub and having a first outer axial length which is less than the first inner axial length. Each second blade has an inner end which is spaced apart from the hub. Each second bade also has an outer end spaced apart from the hub. The second bade outer end and has a second outer axial length which is greater than the first outer axial length.
Each second blade has an inner end which tapers to a tip connected to the base plate. The outer ends of the first and second blades are aligned with the outer peripheral edge. Each second blade has a mid location which is between the inner and outer ends thereof. The inner end of each first blade has an upstream corner which is spaced apart axially from the second plate surface by a first inner length. Each second blade has a mid location which is between the inner end and outer ends thereof. Each mid location forms an apex which is spaced apart axially from the second plate surface by an apex axial length. The first inner axial length is greater than said apex axial length.
At least one example embodiment of the subject matter of this disclosure is understood by referring to
Referring to
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Preferably, the number of first blades 36 is the same as the number of second blades 38 so that the fan remains axially balanced. This helps to preserve bearing life and reduce noise. For example, the impeller unit 18 may include 9 first blades 36 and 9 second blades 38 interspersed between them. As best seen in
As best seen in
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The result is a fan or impeller assembly which is quieter. In this design, the height of the fan blades is varied so that a stall condition can be avoided due to the air inlet not being crowded with as many blades, and yet the shorter blades still contribute to the overall flow volume produced. This fan assembly generates an improved vertical air distribution on the outlet. For the air traveling through the heat exchangers surrounding the fan, better heat transfer is achieved with consistent airflow across the whole face of each heater exchanger. Airflow distribution is more even.
While the above describes example embodiments of the present disclosure, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.
While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character, it being understood that illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. It will be noted that alternative embodiments of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the present invention as defined by the appended claims.
