FIXED COAXIAL SHAFT FOR A HYDRAULIC UNIT
A fixed coaxial shaft of a hydraulic unit is provided including a body having a first end and a second opposite end. A plurality of first splines is formed in an exterior surface of the body adjacent the first end and a plurality of second splines is formed in the exterior surface of the body adjacent the second end. The plurality of first splines and the plurality of second splines are substantially identical. The body of the shaft has an outer diameter of about 0.640±0.0005 inches (1.626±0.0013 centimeters), an inner diameter of about 0.517±0.010 inches (1.313±0.0254 centimeters), and an overall length of about 2.678±0.005 inches (6.802±0.0127 centimeters).
Exemplary embodiments of this invention generally relate to an integrated drive generator, and more particularly, to a fixed shaft of a hydraulic unit of an integrated drive generator.
Aircrafts currently rely on electrical, pneumatic, and hydraulic systems for secondary power. A typical electrical system utilizes an integrated drive generator (IDG) coupled to each engine to provide a fixed frequency power to the distribution system and loads. One type of IDG includes a generator, a hydraulic unit, and a differential assembly arranged in a common housing. The differential assembly is operably coupled to a gas turbine engine via an input shaft. The rotational speed of the input shaft varies during the operation of the gas turbine engine. The hydraulic unit cooperates with the differential assembly to provide a constant speed to the generator throughout engine operation.
Due to packaging constraints, components of the hydraulic unit, such as nested, coaxial, variable and fixed shafts must be redesigned.
BRIEF DESCRIPTION OF THE INVENTIONAccording to one embodiment of the invention, a fixed coaxial shaft of a hydraulic unit is provided including a body having a first end and a second opposite end. A plurality of first splines is formed in an exterior surface of the body adjacent the first end and a plurality of second splines is formed in the exterior surface of the body adjacent the second end. The plurality of first splines and the plurality of second splines are substantially identical. The body of the shaft has an outer diameter of about 0.640±0.0005 inches (1.626±0.0013 centimeters), an inner diameter of about 0.517±0.010 inches (1.313±0.0254 centimeters), and an overall length of about 2.678±0.005 inches (6.802±0.0127 centimeters).
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTIONReferring now to
An example of an IDG 16 including a housing 18 is shown in
Referring now to
The operation of the hydraulic unit 32 in an IDG 16 of an aircraft involves transmission of torque from an engine of the airplane to an input, which rotates the input shaft 50 of the hydraulic unit 32 about axis A. The cylinder block 38 of the pump 34 is connected to the input shaft 50 for rotation therewith. Pistons 52 within the cylinder block 38 of the pump 34 are displaced during this rotation an amount which is a function of the setting of a variable swash plate 54 of the pump 34.
Hydraulic fluid under pressure from the pump 34 is delivered to the hydraulic motor 36 through the port plate 44 for rotating the cylinder block 40 and an output shaft 56 to which it is fixedly connected. A fixed coaxial shaft 60 is arranged coaxially with and is coupled to the output shaft 56 to impart the rotation of the output shaft to an adjacent component, such as a differential (not shown) for example. The swash plate 58 of the motor 36 is fixed so that the operating speed of the motor 36 is a function of the displacement of the pump 34. The rotary output from output shaft 56 is added to or subtracted from the rotary motion from the engine through the conventional differential gearing of an IDG 16 for operating an electrical generator at a substantially constant rotational speed. That is, since the speed of the rotation from the airplane engine to the input 50 of the hydraulic unit 32 will vary, the position of the variable swash plate 54 is adjusted in response to these detected speed variations for providing the necessary reduction or increase in this speed for obtaining the desired constant output speed to the generator. During normal operation, there is a hydrostatic balance of the cylinder blocks and port plate. Although the hydraulic unit illustrated and described herein refers to the variable unit as a pump and the fixed unit as a motor, hydraulic units having other configurations, such as where the variable unit functions as a motor and the hydraulic unit operates as a pump for example, are within the scope of the invention.
Referring now to
A plurality of first splines 76 is formed in an exterior surface 74 of the body 62 adjacent the first end 64, and a plurality of second splines 78 is formed in the exterior surface 74 of the body 62 adjacent the second end 66 thereof. In one embodiment, the plurality of first splines 76 and the plurality of second splines 78 are substantially identical. The plurality of first splines and second splines 76, 78 may be constructed as detailed in Table 1.
As shown, a first end 80 of the plurality of first splines 76 and a first end 82 of the plurality of second splines 78 are spaced from the adjacent first and second ends 64, 66 of the body 62, respectively, by a distance of about 0.145±0.005 inches (0.368±0.0013 centimeters). In one embodiment, the distance from the first and second ends 64, 66 to an opposite end 84, 86 of each of the plurality of first and second splines 76, 78 is about 0.575±0.010 inches (1.46±0.0254 centimeters). In addition, a distance from each of the first and second ends 64, 66 to a midpoint M of the adjacent first and second splines 76, 78 may be 0.360±0.030 inches (0.914±0.076 centimeters).
A radius, best illustrated in
Referring now to
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
Claims
1. A fixed coaxial shaft of a hydraulic unit, comprising:
- a body having a first end and a second opposite end and a plurality of first splines formed in an exterior surface of the body adjacent the first end and a plurality of second splines formed in the exterior surface of the body adjacent the second end, the plurality of first splines and the plurality of second splines being substantially identical, wherein the body has an outer diameter of about 0.640±0.0005 inches (1.626±0.0013 centimeters), and inner diameter of about 0.517±0.010 inches (1.313±0.0254 centimeters), and an overall length between the first end and the second end of about 2.678±0.005 inches (6.802±0.0127 centimeters).
2. The fixed coaxial shaft according to claim 1, wherein an interface between the plurality of first splines and the exterior surface of the body and an the interface between the plurality of second splines and the exterior surface of the body has a radius of about 0.030±0.010 inches (0.076±0.0254 centimeters).
3. The fixed coaxial shaft according to claim 1, wherein a first end of the plurality of first splines and a first end of the plurality of second splines are spaced away from the first end and the second end of the body, respectively, by a distance of about 0.145±0.005 inches (0.368±0.0013 centimeters).
4. The fixed coaxial shaft according to claim 2, wherein a chamfer is formed in the first end of the plurality of first splines and the first end of the plurality of second splines, the chamfer having a width parallel to a longitudinal axis of the shaft or about 0.018±0.010 inches (0.046±0.0254 centimeters) and extends at an angle of about 45°±5°.
5. The fixed coaxial shaft according to claim 2, wherein a second end of the plurality of first splines and a second end of the plurality of second splines are spaced away from the first end and the second end of the body, respectively, by a distance of about 0.575±0.010 inches (1.46±0.0254 centimeters).
6. The fixed coaxial shaft according to claim 1, wherein a midpoint of the plurality of first splines and a midpoint of the plurality of second splines are spaced away from the first end and the second end of the body, respectively, by a distance of about 0.360±0.030 inches (0.914±0.076 centimeters).
7. The fixed coaxial shaft according to claim 1, wherein the plurality of first splines and the plurality of second splines are constructed in accordance with Table 1.
8. The fixed coaxial shaft according to claim 1, wherein a periphery of the first splines and the second splines includes a radius, such that a horizontal distance between a midpoint and a first point on the periphery is about 0.200 inches (0.508 centimeters) and a vertical distance between the midpoint and the first point is about 0.0020±0.0005 inches (0.005±0.001 centimeters).
9. The fixed coaxial shaft according to claim 8, wherein a second point is arranged on the periphery of the first splines and second splines between the midpoint and the first point, wherein a horizontal distance between a midpoint and a second point is about 0.100 inches (0.0254 centimeters) and a vertical distance between the midpoint and the first point is about 0.0005±0.0003 inches (0.001±0.00076 centimeters).
10. The fixed coaxial shaft according to claim 1, wherein a chamfer is formed in the first end of the body, the chamfer extending outwardly at about 60° such that an inner diameter at the first end of the body is about 0.580±0.010 inches (1.473±0.0254 centimeters).
11. The fixed coaxial shaft according to claim 1, wherein a substantially identical chamfer is formed at the second end of the body.
Type: Application
Filed: Dec 19, 2014
Publication Date: Jun 23, 2016
Inventors: Kris H. Campbell (Poplar Grove, IL), Glenn C. Lemmers, JR. (Loves Park, IL), Doren C. Smith (Rockford, IL)
Application Number: 14/576,292