BACKGROUND OF THE INVENTION

[0001] The field of the invention relates generally to electric machines and, more particularly, to motor assemblies having drive components.

[0002] Many known electro-mechanical devices such as electric motors generate heat during operation. At least some known motors are provided with a cooling fan rotatably coupled thereto, and the fan rotates during operation of the motor to produce air flow over the motor housing to facilitate cooling the motor. In other known cases the electro-mechanical assembly is positioned in the inlet region of the fan as part of an air moving system. However, these systems typically restrict airflow from the desired cooling and system operation path.

BRIEF DESCRIPTION OF THE INVENTION

[0003] In one embodiment, a cover is described. The cover has a shape or geometry with its surface curvature aligned with the predominant flow direction having the apex oriented to the predominant flow direction near the natural stagnation region of the surface as it occurs while used in the air moving system. The cover is used with a fan in order to maintain attached airflow over a surface of the cover while minimizing impact to airflow.

[0004] In an aspect of this embodiment, the geometrical shape or form of the cover may be elliptical, hemispherical, ogive, or combination of these and other streamlined shapes. A line drawn from highest point of curvature on the surface through the midpoint of the geometrical volume may be aligned near the axis of the predominant airflow direction.

[0005] In another aspect of this embodiment, the geometrical shape or form of the cover may include a surface perturbation located upstream of at least one of turning angles, separation regions, and geometry transitions on surface of cover to create an energized or turbulent boundary layer and assist turning of airflow. [0006] In another embodiment, a cover is described. The cover has geometry to create forced airflow using a passive design, minimize external airflow disturbance and maximize forced convection cooling with fins aligned with the predominant flow direction on the surface.

[0007] In an aspect of this embodiment fins are place on the exterior surface or on the interior surface.

[0008] In an aspect of this embodiment, the fins are designed to either assist airflow or enhance heat exchange or both.

[0009] In an aspect of this embodiment routing vents maybe opened in the housing thus creating forced airflow inside of the cover.

[0010] In an aspect of this embodiment openings may be positioned at the stagnation region or at the region of highest curvature or highest velocity or at both regions.

[001 1] In an aspect of this embodiment, the cover may be designed to have highest point near natural stagnation region over desired operating range.

[0012] In an aspect of this embodiment the vent exits are designed for water and airflow management.

[0013] In an aspect of this embodiment the cover may be at least partially composed of an electrically conductive material for providing EMI shielding.

[0014] In an aspect of this embodiment, the cover geometry from the base of the enclosure is generally streamlined. The geometry may be any combination of ogive, elliptical, or hemispherical form.

[0015] In an aspect of this embodiment the enclosure may be either rotating with fan or may be fixed. [0016] In an aspect of this embodiment, for example for a cover geometry without vent holes, a combination of external fins or internal fins, or both may be used to enhance heat transfer.

[0017] In an aspect of this embodiment, a surface perturbation may be located upstream of the turning angles on the surface of the cover to create a turbulent or energized boundary layer and to assist in the turning of airflow on the surface of the cover.

[0018] In an aspect of this embodiment, additional cover(s) may be placed on multiple inlet airflow systems to balance airflow restriction. It may also provide additional necessary thermal or moisture management.

[0019] In another embodiment, a shield is described. The shield acts as a baffle to manage airflow or moisture on its surface.

[0020] In an aspect of this embodiment, a shield is used to create indirect paths for the flow of the water droplets to reduce the probability of the water to ingress into the enclosed components.

[0021] In an aspect of this embodiment, a shield may contain a conductive layer which may provide EMI shielding.

[0022] In an aspect of this embodiment, a shield may be composed of an electrically insulating material which will enable spacing reduction between the outer cover and the shield to comply with safety agency requirements.

[0023] In an aspect of this embodiment, a shield may have openings through the shield to allow air to pass through the shield to cool covered component(s) and to allow for optimized flow routing for the air.

[0024] In an aspect of this embodiment, a shield may have ridges on surface of the shield to channel moisture and to channel airflow along the ridges. [0025] In another embodiment, a system is described. The system uses an external cover and an inner shield to direct airflow, manage moisture ingress and enhance heat exchange. The system has a shield acting as a baffle surface to manage the airflow paths.

[0026] In an aspect of this embodiment, the geometrical shape or form of the cover may be elliptical, hemispherical, ogive, or combination of these and other streamlined shapes. A line drawn from highest point of curvature on the surface through the midpoint of the geometrical volume may be aligned near the axis of the predominant airflow direction.

[0027] In another aspect of this embodiment, the geometrical shape or form of the cover may include a surface perturbation located upstream of at least one of turning angles, separation regions, and geometry transitions on surface of cover to create turbulent or energized boundary layer and assist turning of airflow.

[0028] In an aspect of this embodiment fins are place on the exterior surface or on the interior surface.

[0029] In an aspect of this embodiment, the fins are designed to either assist airflow or enhance heat exchange or both.

[0030] In an aspect of this embodiment routing vents maybe opened in the housing thus creating forced airflow inside of the cover.

[0031] In an aspect of this embodiment openings may be positioned at the stagnation region or at the region of highest curvature or highest velocity or at both regions.

[0032] In an aspect of this embodiment, the cover may be designed to have highest point near natural stagnation region over desired operating range.

[0033] In an aspect of this embodiment the vent exits are designed for water and airflow management. [0034] In an aspect of this embodiment the cover may be composed of an electrically conductive material for providing EMI shielding.

[0035] In an aspect of this embodiment, the cover geometry from the base of the enclosure is generally streamlined. The geometry may be any combination of ogive, elliptical, or hemispherical form.

[0036] In an aspect of this embodiment the enclosure may be either rotating with fan or may be fixed.

[0037] In an aspect of this embodiment, for example for a cover geometry without vent holes, a combination of external fins or internal fins, or both may be used to enhance heat transfer.

[0038] In an aspect of this embodiment, a surface perturbation may be located upstream of the turning angles on the surface of the cover to create a turbulent boundary layer and to assist in the turning of airflow on the surface of the cover.

[0039] In an aspect of this embodiment, openings are positioned on the cover and/or the shield to maximize airflow and minimized moisture ingress.

[0040] In an aspect of this embodiment, the openings are staggered allowing larger openings while limiting access to electrically live parts.

[0041] In an aspect of this embodiment, a combination of ridges are placed on the inner shield and are positioned in proximity to outer shield to provide airflow direction and moisture management.

[0042] In an aspect of this embodiment, moisture ingress is managed by either channeling water or by a force mechanism acting on the flow being either centrifugal, gravitational or pressure driven, or combination. This phenomenon is more fully described in the detailed specification.

[0043] In another embodiment, an electronics enclosure for use with electric machine is provided. The enclosure may be used in an air moving application with the dual purpose of directing or rotating the flow before entering fan and providing additional heat transfer surface to enhance forced convection. Optimized placement of vents in electronics enclosure are provided such that the inlet vents are placed at the stagnation point or region of the cone and the exit vents are placed on a region of the enclosure with accelerating flow therefore creating a lower pressure gradient over the surface of the vents and pulling air out of the enclosure. This design assists in circulating the airflow effectively with minimal impact and resistance to the airflow entering the fan. In order to manage water ingress, a water shield may be inserted inside of the cover to direct any water that would pass into the cover and direct it away from the electronics or other motor components through exits placed at the bottom of cover or at other favorable location. Fins may be placed on the outer and inner surfaces to enhance heat exchange. The fins on the interior and exterior may be aligned to reduce the thermal resistance to the heat transfer through the cover. The highest density of the fins on internal surface and external surface may be located at the same location. The position of the fins assists in minimizing thermal resistance. Fins on outer surface may be placed on the regions of the cover where the highest flow velocity occurs to enhance forced convection heat transfer. These fins are may assist with directing the airflow and minimizing disturbance to the airflow.

[0044] The fins inside of the cover are positioned so that the thermal mass is concentrated at the location of the external fins therefore concentrating the heat exchange at the location where greatest heat dissipation occurs on the outer surface. The shield, whether it includes water management features to guide moisture from the sensitive drive or motor component or whether the shield does not have such features, can also be used to reduce EMI using a conductive layer. The shield can be made of an electrical insulating material to reduce the spacing required and allow a smaller overall cover volume.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a perspective view of the exterior of one embodiment of a cover according to the present invention; [0046] Figure 2 is a perspective view of the interior of another embodiment of a cover according to the present invention having fins on the interior of the cover;

[0047] Figure 3 is a perspective view of the exterior of another embodiment of a cover according to the present invention having air and water vents;

[0048] Figure 4 is a perspective view of the exterior of another embodiment of a cover according to the present invention having fins and air and water vents;

[0049] Figure 5 is a perspective view of the exterior of the cover of Figure 1 showing external airflow paths;

[0050] Figure 6 is a partially cut away plane view of another embodiment of a cover according to the present invention having an inner shield and an outer cover;

[0051] Figure 7 is a perspective view of the exterior of the shield of another embodiment of the present invention with holes through the shield showing external airflow paths;

[0052] Figure 8 is a perspective view of the exterior of an shield of another embodiment of the present invention showing ridges to channel water or airflow;

[0053] Figure 9 is a perspective view of the exterior of a shield of another embodiment of the present invention showing ridges to channel water or airflow and openings to channel airflow;

[0054] Figure 10 is a partially cut away perspective view of the exterior of an cover of another embodiment of the present invention showing the electronic controls housed therein;

[0055] Figure 11 is a partially cut away perspective view of the exterior of the electronics cover of Figure 10; [0056] Figure 12 is a partially cut away perspective view of the exterior of an electronics cover of another embodiment of the present invention showing the internal fin surface;

[0057] Figure 13 is a diagram of an elliptical geometry oriented to flow direction while forming the exterior surface of cover for use in another embodiment of the present invention; and

[0058] Figure 14 is a diagram showing the surface perturbation positioned prior to turning surface on cover to energize or create turbulent boundary layer.

DETAILED DESCRIPTION OF THE INVENTION

[0059] Referring first to Figure 1, an embodiment of the invention is shown as a cover 10. The cover 10 has a plurality of fins 12 on its convex periphery 14. The periphery 14 provides a streamlined enclosure geometry that is oriented with the predominant flow direction 16. The fins 12 are oriented in the predominant airflow direction 16. The invention addresses the challenge of effectively cooling motor components or electronics while creating minimal impact on airflow quality or disturbance to airflow when part or all parts of the electromechanical drive system are positioned inside airstream entering a fan (Figures 1 and 1 1). It should be appreciated that the fan may be an axial or centrifugal or any other known fan.

[0060] Figure 11 shows another embodiment of the invention is shown as an alternate cover 1010 with an alternate fin 1012.

[0061] Referring now to Figure 2, another embodiment of the invention is shown as a cover 1 10 having an example of ridges 1 18 (also known as fins) on interior 120 of the enclosure or cover 110. Fins 118 placed inside of the enclosure 110 will enhance the heat exchange through the enclosure.

[0062] Referring now to Figure 3, another embodiment of the invention is shown as a cover 210 having optional vent holes 222 placed for thermal and/or aerodynamic advantage. The cover 210 includes optimized vent positioning on drive enclosure to for air through enclosure using aerodynamic principles (Bernoulli's effect that air accelerating over a curved surface creates a low pressure gradient and Venturi effect where the velocity of a fluid changes as the cross sectional area it is passing through changes.). As air accelerates over a curved surface the local pressure over the surface becomes lower than the ambient or free stream pressure creating a favorable pressure gradient. When vents 222 are positioned in the vicinity of the favorable pressure gradient the air will be pulled through the vents. Entrance vents placed at the stagnation region 238 will create a higher pressure inflow and fewer disturbances downstream than vents positioned at other points on the body.

[0063] As shown in Figure 3, the cover 210 includes air entrance vents 236 located at the stagnation region 238 of the cover 210 and air exit vents 240 located at the region 242 of high velocity or high curvature over the surface. The cover also includes water exit vents 246 located on lower base rim 248 of the cover 210.

[0064] Referring now to Figure 4 another embodiment of the invention is shown as a cover 310 with the integration of ridges 312 (fins) and vent openings 322.

[0065] Referring now to Figure 5 the outside airflow path 16 over the cover or enclosure 10 of Figure 1 is shown.

[0066] Referring now to Figure 6 another embodiment of the invention is shown as a combined system 526 with cover 510 and shield 524 used to manage airflow and water ingress. This design may also include a water management system (not shown) to allow air into the cover but channel any water ingress away from the electronics. The design should take into account for electrical clearances as defined by UL or other safety agencies.

[0067] Vents 522 in cover 510 preferably comply with UL or other safety agencies in regard to regulations including the finger probe test. Vents need to be sufficient in size to allow airflow to effectively move through enclosure while accommodating safety requirements. The use of the shield 524 as an inner guard allows the outside holes to be made larger while meeting safety requirements. Having two protective covers over the electronics allows the vents holes in each cover may be larger or offset while still passing the required safety agency probe testing. Use of an electrical conductive material in the water management shield would provide improved EMI shielding for the case where the outer cone may be constructed using a non-electrically insulation material or where additional EMI shielding may be necessary. If the inner water management shield 524 is composed of an electrically insulating material then the spacing between the surfaces of the electronics and any conductive material may be reduced.

[0068] The cover 510 includes air entrance vents 536 located at the stagnation region 538 of the cover 510 and air exit vents 544 located at the region 542 of high velocity or curvature over the surface. The cover also includes water exit holes or vents 546 located on lower base rim 548 of the cover 510.

[0069] Referring now to Figure 7, another embodiment of the invention is shown as a shield 624 having an airflow path 616 over the shield 624. The air flow path 616 as shown includes an air flow path 652 outside shield and an air flow path 650 inside shield.

[0070] Referring now to Figure 8, another embodiment of the invention is shown as shield 724. The shield 724 includes a spiral ridge 718 on the shield 724 to channel water which is one of various methods to channel water including vertically oriented paths, multiple ridges forming paths or circumferential ridges. The water shield 724 may be placed inside of the cover to channel water away from the electronics and effectively manage it. This shield 724 would be composed of material that would also act as an electrical insulator when necessitated by design requirements.

[0071] Referring now to Figure 9, another embodiment of the invention is shown as shield 824. The shield 824 includes openings 822 in the shield 824 along with a spiral ridge 818 on the shield 824 to channel water and for air routing.

[0072] Referring now to Figure 10 another embodiment of the invention is shown as a cover 910 to house electronics 928. The electronics 928 are mounted onto motor mounting surface 954. [0073] Referring now to Figure 11 another embodiment of the invention is shown as a cover 1010 having the fins 1012 which form channels 1030 therebetween. The cover 1010 may be used on an inner cover or shield (not shown). Fins 1012 added to the surface of the cover will enhance the thermal exchange through the cover and can be used to direct the airflow favorably before entering the fan.

[0074] Referring now to Figure 12 another embodiment of the invention is shown as cover 11 10. The cover 1 1 10 is an example of a configuration with internal fins 1156 for use with the fully closed cover 11 10 and may be used with no vents. The cover may include external fins 1 112 as well.

[0075] Referring now to Figure 13 shows a diagram 1232 of how the ellipse can be used to form the enclosure oriented to match the predominant flow direction. The general shape of the cover is streamlined or more specifically at least one of a combination of ogive, hemispherical, elliptical, or other streamlined geometry (Figure 13).

[0076] Referring now to Figure 14 another embodiment of the invention is shown as depicts a cover 1310 based on an elliptical contour oriented such that the axis connecting it's foci are aligned with the predominant flow direction. If the surface of the cover 1310 is smooth, particularly prior to transitions in the surface that would cause the flow to turn, a surface perturbation 1334 may be created upstream of the turn in order to energize or make turbulent part of the flow to assist the flow in turning.