Elastomeric seal

• US 4,404,055 A
• Filed: 04/30/1981
• Issued: 09/13/1983
• Est. Priority Date: 04/30/1981
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Gibson, Christopher M., McCarty, Fred B.
• Primary Examiner(s): Powell, William A.
• Assistant Examiner(s): FALASCO, LOUIS V
• Application Number:
  US06/259,761
• Time in Patent Office: 866 Days
• Field of Search: 427/340, 427/412.5, 427/443, 427/443.2, 427/444, 427/430.1, 427/104, 427/346, 156/156, 156/245, 156/231, 156/215, 156/239, 156/287, 156/165, 156/242, 156/249, 156/289, 156/294, 156/293, 156/307.3, 156/344, 156/213, 310/259, 310/258, 310/45, 310/43, 310/42, 310/156, 264/516, 264/573, 264/269, 264/271.1, 264/DIG. 50
• US Class Current: 156/156
• CPC Class Codes: H02K 15/12 Impregnating, heating or drying of windings, stators, rotors or machines
• CPC Class Codes: H02K 5/128 using air-gap sleeves or air-gap discs
• CPC Class Codes: Y10T 156/1033 Flexible sheet to cylinder lamina

Abstract

An elastomeric bore seal, and a method of making and installing it. The seal is a fluid-impervious, thin-walled (0.025 inch), open-ended, cylinder-like member which is made of an expansible material that can withstand a wide range of temperatures (-65° F. to +400° F.) and that is to be bonded and thereby installed. The use of the seal is as a bore seal in an electrical machine not only provides an economical, reliable, leak-proof way of excluding stator cooling fluid from the rotor cavity, but also permits a significant reduction (26%) in the weight of the electrical machine and a correspondingly substantial reduction in the size of the machine itself.

Claims

1. The method of making and installing an elastomeric stator bore seal for electrical machines having a rotor, a rotor cavity, and a stator assembly which includes a stator and a stator bore, said method comprising the steps of:

a. obtaining a rigid mold tool similar to said rotor in dimensions and longer in length than said rotor, wherein said rigid mold tool has an opening therin for use in permitting entry of a pressurized gas;

b. coating said rigid mold tool with a release agent;

c. dipping, withdrawing and inverting, and dipping, withdrawing and inverting said rigid mold tool, in repeated cycles, into and out of a solution of an elastomer dissolved in a solvent, until a thickness of approximately 0.025 of an inch of an elastomeric coating is obtained on said rigid mold tool and the solvent remaining in said coating has evaporated, wherein said elastomer used, and said elastomeric coating obtained, are capable of withstanding exposure to temperatures in the range of from approximately -65 degrees Fahrenheit to approximately +400 degrees Fahrenheit;

d. curing said elastomeric coating on said rigid mold tool, thereby attaining a final outer surface on said elastomeric coating;

e. applying an adhesive to said stator bore;

f. applying glass cloth to said adhesive stator bore, thereby adhering said glass cloth to said adhesive and to said stator bore;

g. applying an adhesive to said final outer surface of said cured elastomeric coating;

h. placing the adhesive-covered elastomeric coating, with said rigid mold tool therein, into said stator bore;

i. inflating with a pressurized gas introduced through said opening in said rigid mold tool, and thereby expanding, said adhesive-coated elastomeric coating until said coating is lifted from said mold rigid tool and said coating is in uniform pressure contact with said glass cloth covering said stator bore, with said coating thereby covering said glass cloth and said stator bore;

j. heating in a heating oven, and thereby curing, said adhesive on said stator bore and said adhesive on said outer surface of said elastomeric seal, thereby bonding said glass cloth to said stator bore and bonding said elastomeric seal to said glass cloth;

k. removing said pressurized gas and saaid rigid mold tool from within said elastomeric seal;

l. inserting said rotor into said elastomeric seal-covered stator bore;

m. assemblying said rotor and said elastomeric seal-covered stator bore, such that an electrical machine is formed; and

n. cooling said stator by circulating, with a sucking action, a dielectric fluid through said stator assembly, thereby said elastomeric seal excludes said dielectric fluid from said rotor cavity, and said cooling effected by said circulating dielectric fluid reduces loads on said adhesive bonds.