Patent Grant
7144219
The present invention is directed to improved blower housings of the type used to surround fans. More specifically, the present invention contemplates a blower housing with a cutoff having a radial dimension relative to the fan axis where the radial dimension varies from a greater distance at a cutoff midsection to a lesser distance at the cutoff ends. Moreover, the thickness of the cutoff face varies from narrower ends to a wider midsection, the cutoff angle varies from end to midsection, and the slope of the cutoff face may vary.
Previous blowers, such as that shown in U.S. Pat. No. 5,279,515 to Moore et al., include a scroll housing which expands from a cutoff in a continuous and smoothly increasing radial dimension from that cutoff to a discharge outlet. The scroll housing is enclosed by a pair of side walls to enclose a blower and to form a discharge plenum. The discharge plenum is outside of the blower's periphery and inside of the scroll housing and sidewalls. The plenum is characterized by a continuously increasing cross-sectional area basically formed by the radial expansion of the scroll housing away from the periphery. This discharge plenum is defined by a rectangular footprint in a plane perpendicular to the axis of the blower and having edges tangent to the scroll housing at locations spaced approximately 90° from each other. The cutoff is linear and parallel to the axis of the rotation of the fan.
U.S. Pat. No. 5,570,996 to Smiley, III shows a scroll housing having a conformal portion of constant radius preceding the expansion portion of the scroll housing.
U.S. Pat. No. 5,868,551 to Smiley III et al. shows a cutoff for a tangential fan. The fan cutoff 120 has an edge 122 proximal the tangential fan where the edge is not parallel to the fan axis but instead is skewed relative to the axis 14 so that the edge spirals around the periphery of the tangential fan preferably while maintaining a constant gap G between the fan 12 and the edge 122. Effectively, the cutoff angle changes but the gap does not.
U.S. Pat. No. 5,772,399 to Mehta et al. shows a centrifugal fan 10 using a cutoff faring 32. Being of slideable construction, the cutoff faring 32 may be extended a greater or lesser distance into the exit port 15. This is illustrated by a comparison of FIGS. 5 and 6 where the cutoff faring is extended the fullest possible distance H1 in FIG. 5 as opposed to the lowest distance H2 in FIG. 6. The cutoff is linear and parallel to the axis of rotation of the fan.
U.S. Pat. No. 6,677,564 to Shon et al. shows a microwave oven having a blower apparatus with a cutoff portion. The shape of the cutoff portion forms a ‘V’ shape or a ‘U’ shape, and a first inclined surface 471 and a second inclined surface 472 can be formed as a straight or curved line.
Cutoffs are a tradeoff between efficiency preventing recirculation of air from the discharge path, stability of fan operation, and quietness of the fan. Previous cutoffs such as described above are usually a compromise between efficiency, stability, and sound levels but not all three. It would be desirous to provide a cutoff for a fan or blower which is both highly stable and efficient in its operation and having an optimum sound level.
It is an object, feature and advantage of the present invention to improve previous blowers.
It is a further object, feature and advantage of the present invention to provide a blower housing which has an improved cutoff.
It is an object, feature and advantage of the present invention to provide a blower housing having a cutoff having end portions closer to an axis of blower rotation than a cutoff mid-section. It is a further object, feature and advantage of the present invention that the cutoff have a smooth continuous edge. It is a still further feature and advantage of the present invention that the edge arc symmetrically from its ends to that midsection.
It is an object, feature and advantage of the present invention to provide a cutoff for a fan where the cutoff has an edge which is not parallel to the fan's axis of rotation. It is a further object, feature and advantage of the present invention that the cutoff edge be non-linear. It is a still further object, feature and advantage of the present invention that an angle between a cutoff end differ from a related angle through the cutoff midsection. It is another object, feature and advantage of the present invention that the cutoff have a face with a thickness that varies. It is preferable that the face thickness be greater at the midsection than at the ends.
It is an object, feature and advantage of the present invention to provide a blower housing having a cutoff which balances performance stability and improved efficiency with improved sound levels. It is a further object, feature and advantage of the present invention to reduce material, cost and drag in comparison to previous housings.
The present invention provides a cutoff for a blower housing. The cutoff has an edge including a first end having a first radial dimension relative to the axis, a second end having a second radial dimension relative to an axis, and a midsection having a third radial dimension relative to the axis. The third radial dimension is greater than either of the first or second radial dimensions. Preferably the edge transitions from the midsection to the first end by a continuously varying dimension always greater than the first dimension.
The present invention additionally provides a blower arrangement. The arrangement comprises a fan having an outer periphery of blades arranged about an axis; and a housing arranged about the fan. The housing has an inlet and an outlet and forms a first airflow path from the housing inlet to the fan and forming a second airflow path from the fan to the housing outlet. The arrangement also comprises a cutoff longitudinally aligned between the cutoff and the outer periphery and separating the first and second airflow path. The cutoff includes a first longitudinal end radially spaced from the axis a first distance, a second longitudinal end radially spaced from the axis by a second distance, and a cutoff midsection located between the first and second longitudinal ends and radially spaced from the axis by a third continuously varying distance where the third continuously varying distance has a magnitude greater than the first distance.
The present invention yet further provides a cutoff arrangement. The arrangement includes a blower having an axis and a plurality of blades equidistantly spaced about the axis in a radial direction. The arrangement also includes a blower housing having first and second housing inlets and a housing outlet arranged about the blower and forming an airflow path from the first and second housing inlets through the first and second blower inlets, through the blades and to the housing outlet. The blower has first and second blower inlets and a blower outlet. The housing further includes a cutoff arranged near and parallel to the blades to prevent cross circulation from the blower outlet to the blower inlet. The cutoff has an edge radially spaced from the blades in a direction away from the axis. The cutoff edge is generally aligned relative to the axis. The cutoff edge has a first end, a cutoff middle section and a cutoff end where the first and second cutoff ends are radially closer to the axis than the cutoff middle section.
The present invention still further provides a method comprising the steps of: providing a fan cutoff with an edge having a first end, a midsection, and a second end; aligning the cutoff edge parallel to an axis of a fan; spacing the cutoff edge radially from the axis and from the fan; and continuously curving the cutoff edge such that the midsection is radially farther from the axis than the first or second cutoff ends.
The present invention moreover provides a blower comprising apparatus providing a fan cutoff with an edge having a first end, a midsection, and a second end; apparatus aligning the cutoff edge parallel to an axis of a fan; apparatus spacing the cutoff edge radially from the axis and from the fan; and apparatus continuously curving the cutoff edge such that the midsection is radially farther from the axis than the first or second cutoff ends.
The present invention also provides a cutoff for an air moving device such as a fan or blower. The cutoff includes an axis for the air moving device; a first end; a second end; a mid-area; a point in the mid-area; an arbitrary reference line; a first angle formed between the reference line and a line from the first end and a point on the reference line; and a second angle formed between the reference line and a line from the mid-area point and the point on the reference line. The second angle is less than the first angle.
The present invention additionally provides a cutoff for an air moving device. The cutoff includes a first end; a second end; and a cutoff edge extending from the first end to the second end. The cutoff edge has a thickness forming a face on the edge between the first and second ends. The cutoff also includes a point located on the edge approximately equidistant from the first end and from the second end wherein the thickness of the face decreases as a distance from the point on the edge increases.
The present invention further provides a cutoff for an air moving device such as a fan or blower. The cutoff includes an edge with a first end, a second end, and a midsection with a midpoint. The edge has a non-linear shape which is arced from the midpoint to the first end and arced from the midpoint to the second edge. This nonlinear shape is symmetrical about the midpoint.
The present invention still further provides a cutoff for an air moving device such as a blower or a fan. The cutoff includes a first end; a second end; a mid-area; and an edge extending from the first end through the mid-are to the second end. The edge has a first thickness at the first end, a second thickness at the mid-area, and a third thickness at the second end. The second thickness does not equal the first thickness.
The present invention yet further provides an air moving device such as a fan or blower. The device includes an axis; a housing arranged about the axis and forming an air pathway; and a cutoff in the housing forming a starting line for the path. The cutoff includes a first end area, a second end area, a midsection area and an edge extending from the first end area to the mid-section area to the second end area. A distance from the midsection area to the axis is greater than a distance from the first end area to the axis. The cutoff includes a face having a width where the face width is greater at the midsection area than at the first end area. The device includes an arbitrary reference line intersecting the axis at a first point and perpendicular to the axis; a first cutoff angle defined by a first line from a second point on the midsection area to the first point and the arbitrary reference line, and a second cutoff angle defined by a second line from a third point in the first end area to the first point and the arbitrary reference line. The first cutoff angle is greater than the second cutoff angle.
The present invention more further provides an air moving device such as a fan or blower. The device includes an axis; a housing arranged about the axis and forming an air pathway; and a cutoff in the housing forming a starting line for the path. The cutoff includes a first end area, a second end area, a midsection area, an edge extending from the first end area to the mid-section area to the second end area and a face having a width. The face width is greater at the midsection area than at the first end area. The device also includes an arbitrary reference line intersecting the axis at a first point and perpendicular to the axis; a first cutoff angle defined by a second line from a second point on the midsection area to the first point and the arbitrary reference line; and a second cutoff angle defined by a second line from a third point in the first end area to the first point and the arbitrary reference line. The first cutoff angle is greater than the second cutoff angle.
The present invention moreover provides an air moving device such as a fan or blower. The device includes an axis; a housing arranged about the axis and forming an air pathway; and a cutoff in the housing forming a starting line for the path. The cutoff includes a first end area, a second end area, a midsection area and an edge extending from the first end area to the mid-section area to the second end area. A distance from the midsection area to the axis is greater than a distance from the first end area to the axis. The device also includes an arbitrary reference line intersecting the axis at a first point and perpendicular to the axis; a first cutoff angle defined by a first line from a second point on the midsection area to the first point and the arbitrary reference line; and a second cutoff angle defined by a second line from a third point in the first end area to the first point and the arbitrary reference line. The first cutoff is greater than the second cutoff angle.
The present invention also provides an air moving device such as a fan or blower. The device includes an axis; a housing arranged about the axis and forming an air pathway; and a cutoff in the housing forming a starting line for the path. The cutoff includes a first end area, a second end area, a midsection area and an edge extending from the first end area to the mid-section area to the second end area. A distance from the midsection area to an air moving device axis is greater than a distance from the first end area to the axis. The cutoff also includes a face having a width where the face width is greater at the midsection area than at the first end area.
The present invention additionally provides an air moving device such as a fan or blower. The device includes an axis; a housing arranged about the axis and forming an air pathway; and a cutoff in the housing forming a starting line for the path. The cutoff includes a first end area, a second end area, a midsection area and an edge extending from the first end area to the mid-section area to the second end area. A first distance from the midsection area to the axis is greater than a second distance from the first end area to the axis.
The present invention yet also provides an air moving device such as a fan or blower. The device includes an axis; a housing arranged about the axis and forming an air pathway; and a cutoff in the housing forming a starting line for the path. The cutoff includes a first end area, a second end area, a midsection area, an edge extending from the first end area to the mid-section area to the second end area and a face having a width. The face width is greater at the midsection area than at the first end area.
The present invention yet additionally provides an air moving device such as a fan or blower. The device includes an axis; a housing arranged about the axis and forming an air pathway; and a cutoff in the housing forming a starting line for the path. The cutoff includes a first end area, a second end area, a midsection area and an edge extending from the first end area to the mid-section area to the second end area. The device also includes an arbitrary reference line intersecting the axis at a second point and perpendicular to the axis; a first cutoff angle defined by a first line from a second point on the midsection area to the first point and the arbitrary reference line, and a second cutoff angle defined by a second line from a third point in the first end area to the first point and the arbitrary reference line. The first cutoff angle is greater than the second cutoff angle.
The present invention is directed to an improved cutoff for a blower housing. In the context of this application, the term ‘blower’ include blowers, fans, centrifugal blowers, cross-flow blowers, impellers and other fluid moving devices and includes a blade set arranged in a cylindrical shape and rotating about a longitudinal axis. Exemplary blowers are shown in U.S. Pat. No. 5,279,515 to Moore et al., U.S. Pat. No. 5,570,996 to Smiley III, U.S. Pat. No. 5,772,399 to Mehta et al. and U.S. Pat. No. 5,868,551 to Smiley III et al. Each of these patents is commonly assigned with the present invention and each of these patents is hereby incorporated by reference.
In this application, like reference numerals are used to indicate like or similar elements.
The blower 20 is rotated about the axis 12 by a motor (not shown) and draws air through the inlet 14 in an axial direction (a radial direction if a cross-flow or similar blower is implemented) and then turns the air into a radial direction perpendicular to the axis 12 so that the air is moved through the blower 20 into a discharge plenum 42. The discharge airflow path 24 commences at the cutoff 26 and travels around the blower 20 to the discharge outlet 40, passing through the scroll housing section 32 and the discharge plenum 42.
The edge 48 has a first end 54, a midsection 56 and a second end 58. The area around the midsection 56 forms an acoustical reduction portion 61 promoting quieter airflow, whereas the areas around the first and second ends 54, 58 form efficiency enhancing portions 63 inhibiting recirculation and promoting stability. A radial distance from the periphery 52 of the blower is a first distance 60 at the first and second ends 54, 58 and a second distance 62 at the midsection 56. In the preferred embodiment, the second distance 62 is greater than the first distance 60. Thus, the midsection 56 is farther from the periphery 52 than the first and second ends 54, 58, and distance between the cutoff edge 50 and the periphery 52 varies continuously therebetween.
The distances 60 and 62 vary depending upon the cutoff design 26 and blower dimensions, but in the preferred embodiment the first distance 60 ranges from a minimum of 0.5% of the blower diameter to a maximum of 5% of the blower diameter while the second distance 62 varies continuously over a range from a minimum of 2.5% of the blower diameter to a maximum of 15% of the blower diameter. Although these ranges overlap, the first and second distances 60, 62 are selected so that the second distance 62 is greater than the first distance 60. In the preferred embodiment, the first distance 60 is approximately 2% of the blower diameter and the maximum second distance is approximately 6% of the blower diameter.
The edge 50 can be described as being symmetrical and continuous about a midpoint 64 with the result that the edge 50 forms an elliptical shape. In the acoustical reduction portion 61, this elliptical shape has a first flattened arc relative to the axis 12. In the efficiency enhancement portion 63, the elliptical shape has a second sharper arc relative to the axis 12.
The scroll portion 32 expands in a radial direction relative to the axis 12 such that a radial dimension 34 in the discharge airflow path 24 near the cutoff 26 is less than a radial dimension 35 in the discharge airflow path 24 nearer the outlet 40 of the housing 10. The cutoff edge 50 is also not parallel to the axis 12 such that a cutoff angle θ1 between an arbitrary plane P intersecting the axis 12 and a line intersecting the axis and a point on a cutoff end 54, 58 is different than a cutoff angle θ2 between the arbitrary plane P and a line through the axis 12 and a point on the midsection 56.
The cutoff edge 50 has a cutoff angle θ from any particular point on the edge 50 when a reference line RL through a point on that edge and the axis 12 is compared to the arbitrary reference plane P. In the case of
In the preferred embodiment of the present invention, the edge 50 does not have a common cutoff angle θ through its length from the first end 54 to the second end 58. Rather, the cutoff angle θ1 at an end point 54, 58 is greater than the cutoff angle θ2 at the midpoint 64. Since the cutoff edge 50 preferably, but not necessarily, has a smooth continuous curve, the cutoff angle θ will vary over the length of the cutoff edge 50. In the preferred embodiment, the cutoff angles θ1 at the end points 54, 58 differ from the cutoff angle θ2 at the midpoint 64 by 11 degrees. The difference between the cutoff angle θ1 at the end points 54, 58 may differ from the cutoff angle at the midpoint 64 over a range of 1 to 30 degrees. Preferably, the cutoff angle θ1 at the end point 56 is the same as that of the end point 54, but these cutoff angles θ1 may vary such that the cutoff angle θ1 at the end point 54 does not equal the cutoff angle θ1 at the end point 54 where particular acoustical or efficiency enhancements are desired. In such case, the cutoff angle θ1 at the end point 54 may be greater than the cutoff angle θ2 at the midpoint 64, which in turn may be greater than the cutoff angle θ1 at the end point 58. Otherwise, the cutoff angle θ2 at the midpoint 64 may be greater than the cutoff angle θ1 at the end point 58, which in turn may be greater than the cutoff angle θ1 at the end point 56. This is further illustrated with regard to
The embodiment of
The non-linear cutoff edge 50 is preferably but not necessarily symmetrical about the midpoint 64. The symmetricality of the edge 50 is such that a series of points equally spaced on either side of the midpoint 64 are equal in their magnitude of their distance while point of unequal spacing have different magnitudes. For example, a distance between point 66 on the periphery 52 and point 68 on the edge 50 has a magnitude 70. Due to the symmetry about the point 64 and the corresponding point 72 on the periphery 52, a distance between a point 74 spaced the same distance 76 will have the same magnitude 70 from a point corresponding on the edge 50. A similar dimension 80 respectively taken between points 82 and 84 on the periphery 52 and between points 86 and 88 on the edge 52 will have the same dimension 80 if spaced a corresponding distance 90 from the midpoint 64.
Essentially, it can be seen that the distance between the cutoff edge 50 and the periphery 52 is smaller at the ends 54 and 58 as exemplified by the distance 60 and increases progressively and continuously through distances 80 and 70 to a maximum 62 at the midpoint 64 of the midsection 56.
The cutoff edge 50, although described as an edge, has a face 48 with width. Preferably this width varies such that the width of the face 48 is narrower proximal the cutoff ends 54, 58 and wider proximal the midsection 56. The increased width results in a blunt face 48 generally facing and generally perpendicular to the direction of discharge airflow.
As perhaps best illustrated with regard to
What has been described in this application is an improved blower housing cutoff for a centrifugal fan or the like which provides better efficiency and stability with reduced sound levels. It will be apparent to a person of ordinary skill in the art that many improvements and modifications are possible to this blower including varying the shape, arc and curvature of the cutoff. Such modifications include the use of various materials in forming the blower. Additionally, although the invention is described in terms of a cutoff edge which is symmetrical about a midpoint, non-linear asymmetrical cutoffs are also contemplated. All such modifications and improvements are contemplated to full within the spirit and scope of the claimed invention.
What is desired to be secured for letters patent of the United States is set forth in the following claims.
This application is a Continuation-in-Part of co-pending U.S. Patent Ser. No. 10/461,042, filed Jun. 13, 2003.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5279515 | Moore et al. | Jan 1994 | A |
| 5449271 | Bushnell et al. | Sep 1995 | A |
| 5570996 | Smiley, III | Nov 1996 | A |
| 5772399 | Mehta et al. | Jun 1998 | A |
| 5868551 | Smiley, III et al. | Feb 1999 | A |
| 6200093 | Lee et al. | Mar 2001 | B1 |
| 6677564 | Sohn et al. | Jan 2004 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 20040253099 A1 | Dec 2004 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10461042 | Jun 2003 | US |
| Child | 10835376 | US |
