1. Field of the Invention
The present invention relates to air moving devices, and in particular, to blowers of the type which are used with high efficiency (e.g., 90% or higher efficiency) furnaces for drawing air from outside of a building into the furnace to support combustion and to expel combustion exhaust products outside of the building. More particularly, the present invention relates to a blower which provides more efficient air flow through the blower housing with decreased blower noise.
2. Description of the Related Art
In high efficiency furnaces, standard chimney air-draw effects are not sufficient to assure the required air flow through the furnace heat exchangers, and therefore, high efficiency furnaces utilize draft inducer blowers to provide sufficient air flow through the furnace. In particular, the blowers of high efficiency furnaces pull flue gases through the furnace heat exchangers and then push the flue gases out through exhaust piping to the exterior of the building. The length of the flue piping is limited by the static pressure induced on the flue gases by the draft inducer blower, and higher static pressures typically allow longer runs of flue piping. One measure of the efficiency of the draft inducer blower is the static pressure generated by the blower on the flue gases at a given air flow rate, wherein a blower is more efficient if it can generate higher pressures and air flows for a given power input to the electric motor which drives the blower impeller.
One known blower for a high efficiency furnace is shown in
In operation, rotation of impeller 46 by motor 32 draws exhaust gases through a centrally disposed circular inlet 50 (
First, during the molding of housing body 22, tubular exhaust transition 34 is formed by a cylindrical-shaped exhaust transition mold (not shown). After the plastic material of housing body 22 cures, the exhaust transition mold is pulled outwardly from housing body 22 in a tangential or radial direction with respect to housing body 22. At least one other larger inner mold (not shown), which is cylindrically-shaped, is used to form the interior of housing body 22 and, after the plastic material of housing body 22 cures, is pulled away from housing body 22 along the axial direction with respect to housing body 22. Notably, it is not practical to shape the inner end of the exhaust transition mold to fit perfectly tangentially along the cylindrical outer surface of the housing body interior mold. Therefore, the exhaust transition mold is shaped to project radially outwardly from the cylindrical outer surface of the housing body interior mold a short distance. Thus, when housing body 22 is molded, the exhaust transition mold forms a recessed area 52 in exhaust transition 34, best shown in
Additionally, as may be seen from
Known blower housings have included features for masking the foregoing blade pass noise. For example, a blower housing disclosed in U.S. Pat. No. 5,316,439 includes either a noise cancellation rod located within the outlet of the blower housing, or a nose-like projection projecting inwardly from the exhaust transition. Noise generated from one of the foregoing components interferes with, and substantially cancels out, the blade pass noise generated by the impeller blades passing the sharp cutoff. U.S. Pat. No. 5,484,259 to Ahmed et al. discloses a blower housing having a fin near the cutoff to provide a vortex in the air flow near the cutoff to reduce noise. However, these and similar methods only mask the blade pass noise, rather than eliminating such noise.
What is needed is a draft inducer blower housing for high efficiency furnaces which is an improvement over the foregoing.
The present invention provides a draft inducer blower for high efficiency furnaces, including a blower housing which facilitates maximum air flow efficiency through the blower housing while reducing air flow noises. The blower housing generally includes a housing body and housing cover which define an exhaust transition therebetween, which transitions the air flow from the circular main cavity of the blower housing to the blower housing outlet. The housing body and housing cover are attached to one another via a lobed joint along the exhaust transition, and each include complementary, smoothly contoured inner surfaces to facilitate smooth air flow through the exhaust transition toward the outlet. Additionally, the housing body and housing cover include cooperating cutoff surfaces which form a broadly radiused cutoff within the blower housing to reduce or eliminate the blade pass noise associated with contact of the air flow from the impeller with the cutoff.
In particular, the housing body and housing cover are attached to one another along a primary joint line which extends around the outer peripheries thereof, and are also attached to one another along a secondary, lobed joint line which extends along the exhaust transition and slopes upwardly in the axial direction toward the exhaust outlet. The foregoing construction allows the inner surfaces of the housing body and housing cover to be molded as smoothly contoured and complementary surfaces in the area of the exhaust transition to facilitate smooth air flow through the exhaust transition toward the outlet. In this manner, the air flow does not encounter obstructions in the exhaust transition which would induce turbulence in the air flow, generating noise and compromising the air flow efficiency of the blower housing.
The housing body and housing cover each include broadly radiused cutoff portions which, when the housing cover is joined to the housing body, cooperate with one another via a pin-and-hole joint to define a broadly radiused cutoff to reduce or eliminate blade pass noise associated with the cutoff. Additionally, the pin-and-hole joint between the cutoff portions of the housing body and housing cover aids in locating the housing body with respect to the housing cover, and also forces the mutually facing surfaces of the housing body and housing cover into tight engagement with one another to assure minimum edge mismatches due to part warpage, for example, such that no protruding edges cause turbulence in the air flow.
Advantageously, the internal and external features of the housing body are configured such that the housing body may be formed according to a molding process using a pair of molds which may be separated from the housing body along the Z-axis direction after the plastic material of the housing body cures. Only one additional mold is needed to form the circular outlet of the housing body, which mold may conveniently take the form of a short, cylindrical mold which is separated from the housing body in the radial or X- or Y-axis direction after the plastic material of the housing body cures. In a similar manner, the features of the housing cover are configured to allow the housing cover to be formed via a molding process including a pair of molds which may be separated from the housing cover in the axial direction after the plastic material of the housing cover cures. In this manner, manufacture of the blower housing from plastic material, via a molding process such as injection molding, is simplified.
In one form thereof, the present invention provides a blower housing defining perpendicular axial and radial directions, including a first housing member including a substantially cylindrical outer wall, and a circular outlet projecting in the radial direction from the outer wall; a second housing member including a substantially circular base wall; an exhaust transition defined by at least one of the first and second housing members; and a broadly radiused cutoff disposed within the blower housing adjacent the exhaust transition, the cutoff defined by at least one of the first and second housing members.
In another form thereof, the present invention provides a blower housing defining perpendicular axial and radial directions, including a first housing member including a substantially cylindrical outer wall and a circular outlet projecting in the radial direction from the outer wall; a second housing member including a substantially circular base wall; an exhaust transition extending toward the outlet, the exhaust transition defined by the first and second housing members; and a first joint line between the first and second housing members, the first joint line extending along the exhaust transition and sloping in the axial direction toward the outlet.
In further form thereof, the present invention provides a blower housing defining perpendicular axial and radial directions, including first and second housing members connected to one another to define a circular main cavity therebetween; a plurality of mounting lugs disposed in spaced relation around an outer periphery of the blower housing; a circular outlet projecting in the radial direction from the blower housing, the outlet formed by at least one of the first and second housing members; an exhaust transition extending from the main cavity toward the outlet, the exhaust transition defined by the first and second housing members; and each of the first and second housing members including smoothly contoured interior surfaces extending along the exhaust transition from the main cavity toward the outlet.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.
Referring first to
Housing body 68 additionally includes a plurality of mounting lugs 84 integrally formed therewith, which are disposed radially outwardly of sidewall 72 in spaced relationship around the outer periphery of blower housing 62. Alternatively, at least a portion of mounting lugs 84 may be formed with housing cover 70. Mounting lugs 84 include slot-like or oval openings 86 for receipt of bolts 88 to attach blower housing 62 to wall 38 (
Housing cover 70 cooperates with housing body 68 to define an enclosed, circular main cavity therebetween. Housing cover 70 includes a centrally disposed, inwardly-projecting, circular lip 96 defining a circular inlet opening 98. Housing cover 70 also includes a plurality of lug feet 100 having recesses 102 which align with the openings 86 of mounting lugs 84. As may be seen from
Referring to
As shown in
Referring to
Housing body 68 of blower housing 62 defines radial X- and Y- axis dimensions which correspond to the diameter of sidewall 72 of housing body 68, as well as an axial or Z-axis dimension which is co-axial with the rotation axis of impeller 114 and drive shaft 66 of motor 64, and which corresponds to the height of outer wall 72 of housing cover 70. Outer wall 72, top wall 74, and inner wall 76 of housing body 68 cooperate to define a volute 130 of housing body 68 which extends around the circumference and outer periphery of blower housing 62 and increases in cross-sectional area from cutoff 132 of blower housing 62 to exhaust transition 108 of housing body 68, as described in further detail in co-pending U.S. patent application Ser. No. 10/934,004, entitled DRAFT INDUCER BLOWER WITH Z-AXIS VOLUTE, filed on Sep. 3, 2004, assigned to the assignee of the present invention, the disclosure of which is expressly incorporated herein by reference. Volute 130 is curved around the outer periphery of blower housing 62 through an angle of at least 180° and, as shown in
According to the present invention, blower housing 62 includes a lobed joint between housing body 68 and housing cover 70 at exhaust transition 108, in addition to the planar, circular primary joint provided between tongue 104 of housing body 68 and groove 106 of housing cover 70. As shown by the air flow arrows in
Referring to
A recess 142 is defined in exhaust transition 108 of housing body 68 beneath lobed joint line 138, and a groove 144 is formed in housing body 68 along lobed joint line 138 above recess 142. As may be seen in
A recess 148 is defined within housing body 68 proximate wall 134 and outlet wall 136 at the beginning of outer wall 72 beneath a first cutoff portion or cutoff hub 150. Cutoff hub 150 is broadly radiused, wherein cutoff hub 150 does not include sharp edges. A pin 152 projects downwardly from cutoff hub 150 into recess 148 in the axial or Z-axis direction.
Referring to
Housing cover 70 additionally includes a lobe 156 having an upper edge which slopes upwardly in the axial or Z-axis direction along lobed joint line 138 from transition point 140 to wall 134 of housing body 68. The upper edge of lobe 156 includes a tongue 158 shaped to fit within groove 144 of housing body 68 to form lobed joint line 138 between housing body 68 and housing cover 70. Optionally, a gasket or other seal (not shown) formed of a suitable resilient material, such as rubber or EPDM foam cording, for example, may be fitted between groove 144 and tongue 158 to enhance the seal therebetween. As may be seen from
Housing cover 70 additionally includes a broadly-radiused second cutoff portion or cutoff projection 164 projecting from base wall 154 of housing cover 70 in the axial or Z-axis direction, which includes a hole 166 in the upper end thereof which is aligned in the axial or Z-axis direction. Also, the cutoff surface of cutoff projection 164 is sloped upwardly in the axial or Z-axis direction from base wall 154 to the upper end of cutoff projection 164. When housing cover 70 is joined to housing body 68, pin 152 of cutoff hub 150 of housing body 68 is fitted within hole 166 of cutoff projection 164 of housing cover 70 to locate housing cover 70 with respect to housing body 68 and to tightly engage the mating surfaces of housing cover 70 and housing body 68. Alternatively, cutoff hub 150 may include hole 166 and cutoff projection 164 may include pin 152, or cooperating structure other than a pin-and-hole fitting may be provided between cutoff hub 150 and cutoff projection 164. Also, when housing cover 70 is joined to housing body 68, the radially outer wall 168 of lobe 156 is received within recess 142 of housing body 68.
Advantageously, as shown in
Additionally, as shown in
As may be seen from
In a further embodiment, molded guide vanes and/or other air guiding devices (not shown) may be employed within exhaust transition 108 as a portion of one or both of housing body 68 and housing cover 70 to guide air flow between the circular main cavity of blower housing 62 and outlet 110 to efficiently direct air flow towards outlet 110 that might otherwise begin to spiral towards cutoff 132.
Finally, although blower housing 62 is shown in
While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
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Number | Date | Country |
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54021608 | Feb 1979 | JP |
Number | Date | Country | |
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20060051206 A1 | Mar 2006 | US |