Method and kit for improved distribution of cooling air in an electric machine

Abstract

Method and kit for retrofitting an electric machine to reduce temperature rise therein are provided. The method allows for removing an originally assembled coil support on a spider structure of the machine. The originally assembled coil support is configured to allow axial flow to cooling air from a plurality of cooling vents in the armature of the machine. The method further allows for mounting a new coil support on the spider structure. The new coil support is configured to provide axial and radial routing to cooling air passing from the plurality of cooling vents. The air routing provided by that new coil support enables reduction of temperature rise.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention is generally related to method and kit for ventilating electric machines, and, more particularly, to method and kit for improved distribution of cooling air to lower operating temperature of the machine.

[0002] Dynamo electric machines, such as motors, generators, etc., generate heat which must be removed efficiently to ensure long and economical operation of the machine. As shown in the exemplary prior art construction of FIG. 1, in an electric machine 10, such as a direct current (DC) traction motor, a suitable external blower 12 is commonly used to cool the machine by forcing cooling air from one end of the armature 14 of the machine through a plurality of venting passages therein, e.g., venting passage 16, to an opposite end where the coils (not shown) of the machine are mounted in a suitable coil support 18 mounted on a spider structure 20, which is in turn mounted on the shaft 22 of the machine. Unfortunately, there may be regions, e.g., the region proximate to flange 24, not well-exposed to the flow of cooling air, essentially isolating such regions from that cooling air. This causes undesirable temperature rise in the machine and can result in overheating, and/or shorter insulation life. Either of such results would add burdensome costs to the operation of the machine. For this reason, there is a need for method and kit for routing cooling air to otherwise isolated parts of the machine.

[0003] It would be further desirable to provide method and kit that may be inexpensively provided to retrofit machines already deployed in the field without compromising the structural integrity of the machines, and without having to use complicated tooling equipment or labor intensive assembly.

SUMMARY OF THE INVENTION

[0004] Generally speaking, the present invention fulfills the foregoing needs by providing in one aspect thereof a method for retrofitting an electric machine to reduce temperature rise therein. The method allows for removing an originally assembled coil support on a spider structure of the machine. The originally assembled coil support is configured to allow axial flow to cooling air from a plurality of cooling vents in the armature of the machine. The method further allows for mounting a new coil support on the spider structure. The new coil support is configured to provide axial and radial routing to cooling air passing from the plurality of cooling vents. The air routing provided by that new coil support enables reduction of temperature rise.

[0005] The present invention further fulfills the foregoing needs by providing in another aspect thereof, a kit for retrofitting an electric machine to reduce temperature rise therein. The kit includes a tool configured to remove an originally assembled coil support on a spider structure of the machine. The originally assembled coil support is configured to allow axial flow to cooling air from a plurality of cooling vents in the armature of the machine. A new coil support is mountable on the spider structure. The new coil support is configured to provide axial and radial routing to cooling air passing from the plurality of cooling vents. The air routing provided by that new coil support enables the temperature rise reduction.

DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a cross-sectional view of a prior art arrangement of an originally assembled coil support used in an exemplary dynamo electric machine and wherein that arrangement does not provide radial flow to cooling air passing therethrough;

[0007] FIG. 2 illustrates the arrangement of FIG. 1 with the originally assembled coil support removed in accordance with one embodiment of the present invention;

[0008] FIG. 3 illustrates an isometric view of the arrangement shown in FIG. 2;

[0009] FIG. 4 illustrates an isometric view of a new coil support in accordance with one aspect of the present invention;

[0010] FIG. 5 illustrates an isometric view of the new coil support assembled onto a spider structure of the machine;

[0011] FIGS. 6 and 7 illustrate further details regarding the new coil support shown in FIG. 4; and

[0012] FIG. 8 illustrates the arrangement of FIG. 1 with the originally assembled coil support being modified in accordance with another embodiment of the present invention.

[0013] Before any embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

DETAILED DESCRIPTION OF THE INVENTION

[0014] FIG. 2 is used for illustrating structure that results upon performing exemplary steps that, in accordance with one aspect of the present invention, allow for retrofitting a dynamo electric machine to reduce temperature rise in the machine. As shown in FIG. 2, a tool 50, such as a standard machining tool, is configured to remove the originally assembled coil support 18 (FIG. 1) on spider 20. As suggested above, the originally assembled coil support 18 is configured to allow only axial flow to the cooling air from the plurality of cooling vents, e.g., cooling vent 16, in the armature 14 of the machine. As further explained below, the removal of the originally assembled coil support allows for mounting a new coil support on the spider 20 that is configured to provide both axial and radial routing to cooling air passing from the plurality of cooling vents. The air routing provided by the new coil support is believed to enable temperature rise reduction in the machine by improved cooling of the outer ends of the armature and the coils.

[0015] FIG. 3 shows an isometric view of the dynamo electric machine subsequent to the removal of the originally assembled coil support 18. In one exemplary embodiment, the removal of coil support 18 is performed by machining off, e.g., by cutting or milling, coil support 18 from spider 20 to provide on spider 20 a cylindrical surface configured to receive a new coil support 100, as shown in various levels of details in FIGS. 4 through 7. As shown in FIG. 3, the plurality of cooling vents in the armature of the machine is arranged to provide respective inner and outer circles of cooling vents. For example, cooling vent 26 is part of the outer circle of cooling vents and cooling vent 28 is part of the inner circle of cooling vents. As described in greater detail below, the new coil support 100 is configured so that air flow from the outer circle of cooling vents is radially deflected by an annular chamber 104 (FIG. 7) in the new coil support.

[0016] Air flow from the inner circle of cooling vents is allowed to axially continue through corresponding openings, e.g., axial openings 102 (FIG. 4), provided in new coil support 100. The mounting of the new coil support onto the spider 20 may be accomplished by suitably heating the new coil support 100 in order to diametrically expand a hub 110 and provide sufficient clearance between a central bore 112 defined by hub 110 and the receiving surface on the spider structure. As show in FIGS. 3 and 5, alignment pins 114 may be used for appropriately aligning new coil support 100 relative to the armature slots. Once the new coil support 100 is mounted on spider 20, and upon cooling off of the new coil support, the diameter of the central bore 112 contracts to provide a sufficiently tight interference fit between the hub 110 and the receiving surface on the spider. The heating action may be performed with any standard heating tool.

[0017] FIG. 6 illustrates a top view of new coil support 100 and FIG. 7 illustrates a cross sectional view along a line 7-7 shown in FIG. 7. As suggested above, the annular chamber 104 allows to radially route the cooling air from the outer circle of cooling vents, and eventually that routed air exits from new coil support 100 through a plurality of radial openings 106 (FIG. 5) between the armature and the new coil support. For simplicity of illustration, not every radial or axial opening in new coil support 100, as illustrated in FIGS. 5 and 6, has been associated with a reference numeral.

[0018] FIG. 8 illustrates another embodiment of the present invention that uses a modifying tool 200 for modifying the originally assembled coil support 18 (FIG. 1) in lieu of completely removing such coil support from spider 20. As shown in FIG. 8, modifying tool 200 may include a standard cutting or machining tool that allows for removing outer flange 24 (FIG. 1) without affecting any other components of the dynamo electric machine. As suggested above, the modified coil support 201 provides axial and axial routing to cooling air that passes from the plurality of cooling vents in the armature of the machine. The new routing provided to the cooling air by the modified coil support enables temperature rise reduction in the electric machine. Modifying tool 200 may further include a standard affixing tool, such as welding tool, that allows for affixing a ring 202 positioned between the armature 14 and the modified coil support 201. In this embodiment, air flow from the outer circle of cooling vent is radially reflected by an outer wall 206 of ring 202 to the space previously closed by the outer flange 24 (FIG. 1). As shown in FIG. 8, the shape of outer wall 206 is concave relative to the air flow from the outer circle of vents and allows for imparting approximately a 90 degree deflection to that air flow. Conversely, air flow from the inner circle of cooling vent continues axially unimpeded by way of a cylindrical inner wall 204 in the ring 202. Experimentally derived data indicates that the kit and method of the present invention allow for reducing armature temperature rise by approximately 10% in one exemplary DC traction motor type.

[0019] It will be understood that the specific embodiment of the invention shown and described herein is exemplary only. Numerous variations, changes, substitutions and equivalents will now occur to those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, it is intended that all subject matter described herein and shown in the accompanying drawings be regarded as illustrative only and not in a limiting sense and that the scope of the invention be solely determined by the appended claims.

Claims

1. A method for retrofitting an electric machine to reduce temperature rise therein, said method comprising:

removing an originally assembled coil support on a spider structure of the machine, said originally assembled coil support configured to allow axial flow to cooling air from a plurality of cooling vents in the armature of the machine; and

mounting a new coil support on said spider structure, said new coil support configured to provide axial and radial routing to cooling air passing from said plurality of cooling vents, the air routing provided by said new coil support enabling said temperature rise reduction.

2. The retrofitting method of claim 1 wherein said removing step comprises machining the originally assembled coil support to provide on said spider structure a cylindrical surface configured to receive the new coil support.

3. The retrofitting method of claim 2 wherein the plurality of cooling vents is arranged on said armature to provide respective inner and outer circles of cooling vents and wherein air flow from said outer circle of cooling vents is radially deflected by an annular chamber in said new coil support.

4. The retrofitting method of claim 3 wherein air flow from said inner circle of cooling vents is allowed to axially continue through corresponding openings in said new coil support.

5. The retrofitting method of claim 4 further comprising heating said new coil support to provide sufficient clearance between a central bore in said new coil support and the receiving cylindrical surface on the spider structure.

6. The retrofitting method of claim 5 wherein upon cooling of said new coil support a sufficiently tight interference fit is provided between said bore and said receiving surface on the spider structure.

7. A method for retrofitting an electric machine to reduce temperature rise therein, said method comprising:

modifying an originally assembled coil support on a spider structure of the machine to provide axial and radial routing to cooling air passing from a plurality of cooling vents in the armature of the machine, the air routing provided by said modified coil support enabling said temperature rise reduction.

8. The retrofitting method of claim 7 wherein said modifying step comprises removing an outer flange of said coil support.

9. The retrofitting method of claim 8 wherein said modifying step further comprises providing a ring affixable between the armature and the coil support.

10. The retrofitting method of claim 9 wherein the plurality of cooling vents is arranged on said armature to provide respective inner and outer circles of cooling vents and wherein air flow from said outer circle of cooling vents is radially deflected by an outer wall of said ring to a space previously occupied by said outer flange.

11. The retrofitting method of claim 10 wherein air flow from said inner circle of cooling vents continues axially unimpeded by way of an inner wall of said ring.

12. A kit for retrofitting an electric machine to reduce temperature rise therein, said kit comprising:

a new coil support mountable on a receiving surface of a spider structure of the machine, said new coil support configured to provide axial and radial routing to cooling air passing from a plurality of cooling vents in the armature of the machine, said receiving surface having been cleared from an originally assembled coil support lacking said radial routing.

13. The retrofit kit of claim 12 wherein the plurality of cooling vents is arranged on said armature to provide an inner circle of cooling vents and an outer circle of cooling vents and wherein air flow from said outer circle of cooling vents is radially deflected by an annular chamber in said new coil support.

14. The retrofit kit of claim 13 wherein air flow from said inner circle of cooling vents is allowed to axially continue through corresponding openings in said new coil support.

15. The retrofit kit of claim 12 further comprising a tool configured to remove the originally assembled coil support on said spider structure.

16. The retrofit kit of claim 15 further comprising a heating tool configured to heat said new coil support to provide sufficient clearance between a central bore in said new coil support and the receiving cylindrical surface on the spider structure.

17. The retrofit kit of claim 16 wherein upon cooling of said new coil support a sufficiently tight interference fit is provided between said bore and said receiving surface on the spider structure.

18. A kit for retrofitting an electric machine to reduce temperature rise therein, said kit comprising:

a modified coil support mountable on a receiving surface of a spider structure of the machine, said modified coil support configured to provide axial and radial routing to cooling air passing from a plurality of cooling vents in the armature of the machine, said modified coil support produced from an originally assembled coil support lacking said radial routing.

19. The retrofit claim of claim 18 further comprising a modifying tool configured to modify said originally assembled coil support and wherein said modifying tool comprises a cutting tool configured to remove an outer flange of said coil support.

20. The retrofit kit of claim 19 wherein said modifying tool further comprises an affixing tool configured to affix a ring between the armature and the coil support.

21. The retrofit kit of claim 20 wherein the plurality of cooling vents is arranged on said armature to provide respective inner and outer circles of cooling vents and wherein air flow from said outer circle of cooling vents is radially deflected by an outer wall of said ring to a space previously occupied by said outer flange.

22. The retrofit kit of claim 21 wherein air flow from said inner circle of cooling vents continues axially unimpeded by way of an inner wall of said ring.