Patent Application
20140205450
The field of the disclosure relates generally to motors and, more specifically, to fan motor assemblies for use in forced air or air circulating systems.
Many known residential and commercial forced air, heating and air conditioning systems require air propulsion units. In addition to providing movement of air for heating and cooling systems, air propulsion units are often used in combination with condenser units or to supplement other heat transfer operations. Some known air propulsion units are motor driven fans. These fans may be, for example, a blower wheel type or a multi-bladed type. However, some known motors and/or their mounting components restrict entering and exiting air and produce aerodynamic losses that negatively affect the overall performance of the fan.
In one aspect, a motor assembly is provided. The motor assembly includes a fan housing having an air inlet and an air outlet, and a motor coupled to the fan housing and positioned within the air inlet. The motor includes a first end, a second end, and a shaft. The motor assembly further includes a fan coupled to the shaft proximate the motor second end. The motor first end includes a contoured surface having a stagnation point and a plurality of points along the contoured surface downstream of the stagnation point. Each point of the plurality of points has a coefficient of pressure less than 1, and the contoured surface is configured to direct air around the motor and to reduce airflow restriction and flow disturbance within the fan housing.
In another aspect, a motor assembly is provided. The motor assembly includes a fan housing having an air inlet and an air outlet, and a motor positioned within the air inlet. The motor includes a first end, a second end, and a shaft. The motor assembly further includes a fan coupled to the shaft, and at least one mounting arm coupled to the motor and the fan housing. The at least one mounting arm includes a streamlined body having a first end having a stagnation point, a second end, and a plurality of points along a surface of the streamlined body downstream of the stagnation point. Each point of the plurality of points has a coefficient of pressure less than 1, and the streamlined body is configured to direct air around the at least one mounting arm and to reduce airflow restriction and flow disturbance within the fan housing.
In yet another aspect, a motor assembly is provided. The motor assembly includes a fan housing having an air inlet and an air outlet, and a motor positioned within the air inlet. The motor includes a first end, a second end, and a shaft. The motor assembly further includes a fan coupled to the shaft proximate the motor second end, and at least one mounting arm coupled to the motor and the fan housing. The at least one mounting arm includes a streamlined body having a first end having a first stagnation point, a second end, and a first plurality of points along a surface of the streamlined body downstream of the first stagnation point. Each point of the first plurality of points has a coefficient of pressure less than 1, and the streamlined body is configured to direct air around the at least one mounting arm. The motor first end includes a contoured surface having a second stagnation point and a second plurality of points along the contoured surface downstream of the second stagnation point. Each point of the second plurality of points has a coefficient of pressure less than 1, and the contoured surface is configured to direct air around the motor. The streamlined body and the contoured surface are configured to reduce airflow restriction and flow disturbance within the fan housing.
In yet another aspect, a method of assembling a motor assembly is provided. The method includes providing a fan housing having an air inlet and an air outlet, and positioning a motor within the air inlet, the motor having a first end, a second end, a shaft, and at least one mounting arm. The method further includes coupling the at least one mounting arm to the fan housing, coupling a fan to the shaft proximate the motor second end, and providing a streamlined body on the mounting arm. The streamlined body includes a first end having a first stagnation point, a second end, and a first plurality of points along a surface of the streamlined body downstream of the first stagnation point. Each point of the first plurality of points has a coefficient of pressure less than 1, and the streamlined body is configured to direct air around the at least one mounting arm and to reduce airflow restriction and flow disturbance within the fan housing. The method further includes providing a contoured surface on the motor first end, the contoured surface having a second stagnation point and a second plurality of points along the contoured surface downstream of the second stagnation point. Each point of the second plurality of points has a coefficient of pressure less than 1, and the contoured surface is configured to direct air around the motor to reduce airflow restriction and flow disturbance within the fan housing.
The present disclosure provides an exemplary fan and motor assembly with an aerodynamic structural design that improves air flow over the assembly, air flow entering the fan, and downstream of the fan. More specifically, the exemplary fan and motor assembly includes a contoured motor housing, contoured mounting brackets, and an inlet guide vane that each reduce airflow restriction and downstream disturbances in the airflow, which results in increased efficiency and a more favorable and laminar airflow into the fan, thereby improving fan and system efficiency.
In the exemplary embodiment, motor 14 is coupled to fan housing 12 by mounting arms 40, which extend across air inlet 22 between motor housing 28 and fan housing 12. Mounting arms 40 each include a leading first end 42 and a second end 44. While three mounting arms 40 are depicted in the drawings, assembly 10 may have any number of mounting arms 40 (e.g. four, five, etc.). In an alternative embodiment, mounting arms 40 may be angled relative to fan housing 12 and/or motor 14. In some known system, mounting arms have shapes or surfaces with geometries having high fluid flow restriction (e.g. flat surfaces), which may cause undue airflow restriction and downstream airflow disturbances. As such, the associated drag from the separation of flow as it moves around an object creates a low pressure gradient or low pressure section behind the object that causes a flow disturbance. This produces turbulence and airflow restriction at the inlet of the fan and/or downstream of the fan and causes the blades to be less efficient, which reduces fan efficiency and therefore system performance.
In the exemplary embodiment, however, mounting arm first end 42 includes a streamlined body 46 facing oncoming airflow within air inlet 22. In the exemplary embodiment, streamlined body 46 is integral with mounting arm 40. Alternatively, streamlined body 46 may be a separate component or cap coupled to mounting arm 38. In the exemplary embodiment, streamlined body 46 has a surface shape with a low coefficient of pressure (e.g. airfoil, elliptical shape, hemispherical shape). The coefficient of pressure is a dimensionless number which describes relative pressures relating the pressure at the surface of a body to the freestream pressure.
As shown in
In the exemplary embodiment, motor 14 is positioned within fan housing 12 upstream of fan 16 such that motor first end 30 is positioned within the path of air flowing through air inlet 22. In some known systems, motors within housing inlets have end surfaces with high drag coefficients (e.g. flat surfaces), which may cause airflow restriction and flow disturbance. In the exemplary embodiment, however, motor first end 30 includes a contoured surface 48 that has a surface shape with a low coefficient of pressure (e.g. hemispherical, elliptical or ogival).
As shown in
In the exemplary embodiment, fan housing 12 includes an inlet guide vane 50 that includes curved inner and outer surfaces 52 and 54, respectively. Inlet guide vane 50 is coupled to mounting arms 40 and is positioned concentrically within air inlet 22 between fan housing 12 and motor 14. In some known systems, air surrounding the fan housing is pulled into the air inlet at different angles, particularly at the edges of the air inlet (e.g. air being pulled into the inlet perpendicularly to the axis of the rotating shaft). The differently angled airflows entering the inlet cause disturbances in the airflow, which reduces fan efficiency. In the exemplary embodiment, however, inlet guide vane 50 is contoured such that air entering inlet 22 at different angles is re-directed in an axial direction along motor 14, reducing flow disturbance and improving fan efficiency. The curvature of inlet guide vane 50 also increases airflow attachment along surfaces 52 and 54, which accelerates and directs airflow into fan 16 and improves fan efficiency. Although a single inlet guide vane 50 is described, any number of concentric inlet guide vanes 50 may be used in assembly 10.
An exemplary method of assembly of fan and motor assemblies 10 and 11 is provided herein. The method includes providing a fan housing 12 having an air inlet 22 and an air outlet 26. A motor 14 is positioned within the air inlet 22. Motor 14 includes a motor housing 28 having a first end 30, a second end 32 and a sidewall 34 extending therebetween. Motor 14 also includes one or more mounting arms 40 and/or 56, and a shaft 36 is rotatably coupled to motor 14. The method includes coupling mounting arms 40 and/or 56 to fan housing 12 and coupling a fan 16 to shaft 36 proximate fan housing second end 24. A contoured surface 48 is provided on motor housing first end 30. Contoured surface 48 is configured to direct air around motor 14 and to reduce airflow restriction and flow disturbance within fan housing 12. A streamlined body 46 is provided on mounting arms 40 and/or 56, and streamlined body 46 directs air around mounting arm 40, 56 and reduces airflow restriction and flow disturbance within fan housing 12. The method includes coupling an inlet guide vane 50 to mounting arm 40 and/or 56 between fan housing 12 and motor 14. Guide vane 50 is curved and configured to create a low pressure gradient to pull airflow around guide vane 50 and to keep airflow attached along guide vane surfaces 52 and 54 to direct airflow into fan 16.
The methods and systems described herein provide a fan and motor assembly with surfaces acting as directional airflow vanes to improve overflow over the assembly and into the fan. The exemplary fan and motor assembly includes a contoured motor housing, contoured mounting brackets, and an inlet guide vane that each reduce drag and downstream disturbances in the airflow, which results in a more favorable and laminar airflow into the fan, thereby improving fan efficiency. Moreover, the benefits derived from the contoured surfaces are not additive and, as such, the combination of the contoured surfaces provides significantly greater air flow improvement over any single contoured surface alone. The exemplary embodiments described herein provide systems particularly well-suited for commercial and residential HVAC applications, with significantly improved airflow and efficiency.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
