Spring assemblies for use in gas turbine engines and methods for their manufacture

A spring assembly, comprising:

• a first end portion;
• a second end portion;
• and
• a spring portion disposed between the first end portion and the second end portion such that the first end portion is physically connected to a first end of the spring portion and the second end portion is physically connected to a second end of the spring portion,
• wherein the spring portion comprises a helical coil having at least one spring pitch, wherein the spring portion comprises both of a variable pitch and a variable cross-sectional area, wherein the helical coil rotates about a central axis of the spring portion, and wherein the helical coil terminates at the first end portion and the second end portion;
• wherein the first end portion and the second end portion each comprise a spring-facing surface that extends substantially perpendicular to the central axis of the spring portion, wherein the first end of the spring portion is connected to the first end portion at the spring-facing surface of the first end portion and wherein the second end of the spring portion is connected to the second end portion at the spring-facing surface of the second end portion, wherein the first and second ends of the spring portion have zero pitch such that they are oriented parallel to the respective spring facing surfaces of the first and second ends portions,
• wherein the first end portion and the second end portion are physically connected to the spring portion without any weld or braze joints between the first or second end portions and the spring portion such that the spring assembly is manufactured as an integral unit without any welding or brazing of the first end portion, the second end portion, or the spring portion, and
• the variable cross-sectional area being defined as a cross-section taken through the helical coil in a plane that also includes the central axis being different in shape at at least two different points along the helical coil, the at least two points being between the first and second ends of the spring portion, wherein the cross-section at each of the at least two different points is independently selected from the following group of two-dimensional shapes consisting of:
• 1) a first shape defined as having an enclosed perimeter with two sets of parallel, planar opposing sides, connected by curved edges, 2) a second shape defined as having an enclosed perimeter with one set of parallel, planar opposing sides, connected by curved edges, and 3) a third shape defined as having one set of planar opposing sides, wherein one of the planar sides is inclined at an angle and the other one of the planar sides is declined at the angle, the one set of planar opposing sides being connected by both a planar end and a curved end.

A bypass valve assembly for use in an engine control system of a gas turbine engine, the bypass valve assembly comprising:

• a proportional valve assembly comprising a proportional spring;
• and
• an integrator valve assembly comprising an integrator spring assembly, wherein the integrator spring assembly comprises:
• a first end portion;
• a second end portion;
• and
• a spring portion disposed between the first end portion and the second end portion such that the first end portion is physically connected to a first end of the spring portion and the second end portion is physically connected to a second end of the spring portion,
• wherein the spring portion comprises a helical coil having at least one spring pitch, wherein the spring portion comprises both of a variable pitch and a variable cross-sectional area, wherein the helical coil rotates about a central axis of the spring portion, and wherein the helical coil terminates at the first end portion and the second end portion;
• wherein the first end portion and the second end portion each comprise a spring-facing surface that extends substantially perpendicular to the central axis of the spring portion, wherein the first end of the spring portion is connected to the first end portion at the spring-facing surface of the first end portion and wherein the second end of the spring portion is connected to the second end portion at the spring-facing surface of the second end portion, wherein the first and second ends of the spring portion have zero pitch such that they are oriented parallel to the respective spring facing surfaces of the first and second ends portions,
• wherein the first end portion and the second end portion are physically connected to the spring portion without any weld or braze joints between the first or second end portions and the spring portion such that the integrator spring assembly is manufactured as an integral unit without any welding or brazing of the first end portion, the second end portion, or the spring portion, and
• the variable cross-sectional area being defined as a cross-section taken through the helical coil in a plane that also includes the central axis being different in shape at at least two different points along the helical coil, the at least two points being between the first and second ends of the spring portion, wherein the cross-section at each of the at least two different points is independently selected from the following group of two-dimensional shapes consisting of:
• 1) a first shape defined as having an enclosed perimeter with two sets of parallel, planar opposing sides, connected by curved edges, 2) a second shape defined as having an enclosed perimeter with one set of parallel, planar opposing sides, connected by curved edges, and 3) a third shape defined as having one set of planar opposing sides, wherein one of the planar sides is inclined at an angle and the other one of the planar sides is declined at the angle, the one set of planar opposing sides being connected by both a planar end and a curved end.