Motor driven centrifugal blowers for air handling equipment, such as heating, ventilating and air conditioning (HVAC) systems are well known. A typical air handling blower includes a scroll-like housing within which is mounted a centrifugal blower wheel or impeller of a selected diameter and axial length and wherein the housing is adapted or “sized” to operate efficiently with a particular blower wheel or impeller.
However, there are many applications of air handling equipment wherein it is desirable to select the impeller size to accommodate a particular airflow requirement, impeller rotational speed and static or blower discharge pressure requirement, or a change in such requirements. Such performance requirements or desiderata in the equipment market may dictate that many different size blower wheels and associated blower housings be designed and fabricated to meet particular performance requirements of the blower application. Of course, such a situation increases the costs associated with providing products to suit each blower application.
Accordingly, there has been a continuing need and desire to reduce the costs and product complexity associated with providing various blower wheel sizes and associated blower housings which will accommodate the various specific wheel or impeller sizes while meeting the performance requirements of a blower, without adverse effects of increased noise produced by the blower, as well as other parameters of blower performance and operation known to those skilled in the art. In accordance with the present invention, it has been discovered that a particular configuration of blower housing in combination with a particular range of centrifugal impeller sizes provides for operation without sacrificing blower performance and while maintaining reduced noise levels.
The present invention provides an improved air handling blower for use, in particular, with heating, ventilating and air conditioning (HVAC) equipment wherein a blower housing accommodates blower wheels or impellers of selected different sizes and performance capability while maintaining desirable performance parameters and acoustic emission or “noise” levels.
In accordance with one aspect of the present invention, a combination of a centrifugal blower scroll type housing and a centrifugal blower wheel or impeller is provided wherein an impeller providing for high airflow and/or static pressure, in combination with the blower housing is such that the housing air inlet port or orifice has a diameter that is no smaller than the inner diameter of the blades of the largest impeller that the housing will accommodate while the blower housing inlet port or orifice diameter is also no larger than the outer diameter of the smallest impeller or wheel that the housing will accommodate.
Accordingly, the invention contemplates the provision of an air handling blower having a scroll-like housing with an air inlet port or orifice which will accommodate centrifugal blower wheels or impellers of various sizes wherein the outer diameter of the smallest wheel is generally no less than the inner diameter of the largest wheel.
Still further, in accordance with the invention, a centrifugal air handling blower is provided wherein a blower housing having a somewhat spiral or scroll-like air flowpath configuration includes an improved blower wheel cutoff edge configuration having first and second ends and a midsection operable to accommodate a blower wheel or impeller of a selected range of outside diameters wherein the efficiency of the blower is improved, as compared with conventional centrifugal air handling blowers, and blower acoustic emissions are reduced for the same range of blower wheel diameters.
Accordingly, an improved blower configuration is provided by the invention wherein, for a particular size of scroll-like blower housing, a range of blower impeller sizes may be provided wherein such impellers have a particular range of diameters which may be used with the blower housing without reduction in efficiency or increase in noise generated through the use of impellers of various sizes. Still further, the combination of a scroll-like blower housing and range of blower impeller sizes in accordance with the invention provides for obtaining a predetermined air flow rate and discharge pressure required for a blower application at a rotational speed that corresponds to an efficient operating point for the blower drive motor. This flexibility is particularly advantageous for applications utilizing so-called PSC (permanent split capacitor) motors which have an efficiency peak at about ninety percent of synchronous speed. The efficiency of such motors tends to deteriorate at rotational speeds which deviate from the ninety percent of synchronous speed value.
Those skilled in the art will further appreciate the above-mentioned advantages and superior features of the invention, together with other important aspects thereof upon reading the detailed description which follows in conjunction with the drawings.
In the description which follows, like parts are marked throughout the specification and drawing with the same reference numerals, respectively. The drawing figures are not necessarily to scale and certain features may be shown exaggerated in scale or in somewhat generalized form in the interest of clarity and conciseness.
Referring to
Referring further to
Blower housing 28 is provided with opposed air inlet ports or orifices 40 and 40a,
As shown in
Referring now to
still further, a first clearance distance 39e between the outside diameter D30 of the impeller 30 and the cutoff edge 39 at cutoff edge locations 39c and 39d ranges, preferably, from a minimum of 0.5% of the impeller outside diameter to a maximum of 5.0% of the impeller outside diameter while a second distance, measured generally at the midpoint of the elliptical cutoff edge 39, indicated by 39a, is greater than the first distance. In one preferred embodiment, the first distance 39e is approximately 2.0% of the impeller diameter D30 while the second distance 39a is approximately 6.0% of the impeller diameter D30. Of course, in accordance with the teaching of the above-identified published patent application, the edge 39 is symmetrical and continuous about mid point 39a, forming, preferably, an elliptical shape. The cutoff portion of the blower housing 28 is further defined by face 46 which is formed as an area between cutoff edge 39 and a so-called discharge side edge 47,
Referring now to
Accordingly, as shown and described, the diameters of the blower inlet ports or orifices 40 and 40a are generally no smaller than the inside diameter d30 of the largest diameter impeller or wheel 30 and generally no smaller than the outside diameter D50 of the smallest diameter wheel or impeller 50. In order to meet these conditions, the outside diameter D50 of the impeller 50 is no smaller than the inside diameter d30 of the impeller 30. Still further, the cutoff edge 39 is configured such that the radial clearance provided for the largest diameter impeller to be provided is the smallest and typically is about 1.0% to 2.0% of the impeller outside diameter. With these relationships the improved cutoff provided by the curved edge 39 still performs its intended purpose when the blower 24 is operating with the smallest diameter wheel or impeller, such as the impeller 50.
The construction and operation of a blower assembly, such as described herein is believed to be within the purview of one skilled in the art of air handling blowers for HVAC equipment and the like. Conventional engineering materials, including those described in the above-mentioned published patent applications, may be used to fabricate the blower housing 28 as well as the impellers 30 and 50. Moreover, those skilled in the art will also appreciate that impellers of respective inside and outside diameters in a range between the corresponding diameters of the impellers 30 and 50 may be utilized in conjunction with a housing such as the housing 28 without loss of blower performance and while enjoying the benefits of the invention. Thus, by providing a blower having the combination of a housing constructed in accordance with the invention as described herein and a range of impeller sizes from the diameters of the impeller 30 to the diameters of the impeller 50, various blowers may be constructed having airflow, discharge pressure and acoustic emission characteristics which may suit particular applications without requiring that blower housings of different sizes be furnished. In this way manufacturing complexity is reduced without sacrificing product performance or operating efficiency.
The edge 1048 has a first end 1054, a midsection 1056 and a second end 1058. The area around the midsection 1056 forms an acoustical reduction portion 1061 promoting quieter airflow, whereas the areas around the first and second ends 1054, 1058 form efficiency enhancing portions 1063 inhibiting recirculation and promoting stability. A radial distance from the periphery 1052 of the blower is a first distance 1060 at the first and second ends 1054, 1058 and a second distance 1062 at the midsection 1056. In the preferred embodiment, the second distance 1062 is greater than the first distance 1060. Thus, the midsection 1056 is farther from the periphery 1052 than the first and second ends 1054, 1058, and distance between the cutoff edge 1050 and the periphery 1052 varies continuously therebetween.
The edge 1050 can be described as being symmetrical and continuous about a midpoint 1064 with the result that the edge 1050 forms an elliptical shape. In the acoustical reduction portion 1061, this elliptical shape has a first flattened arc relative to the axis 1012. In the efficiency enhancement portion 1063, the elliptical shape has a second sharper arc relative to the axis 1012.
Although a preferred embodiment of the invention has been described in detail herein those skilled in the art will recognize that various substitutions and modifications may be made without departing from the scope and spirit of the appended claims.
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52046503 | Apr 1977 | JP |
Number | Date | Country | |
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20070059167 A1 | Mar 2007 | US |