U.S. patent application number 14/576292 was filed with the patent office on 2016-06-23 for fixed coaxial shaft for a hydraulic unit.
The applicant listed for this patent is Hamilton Sundstrand Corporation. Invention is credited to Kris H. Campbell, Glenn C. Lemmers, JR., Doren C. Smith.
Application Number | 20160177725 14/576292 |
Document ID | / |
Family ID | 54979431 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160177725 |
Kind Code |
A1 |
Campbell; Kris H. ; et
al. |
June 23, 2016 |
FIXED COAXIAL SHAFT FOR A HYDRAULIC UNIT
Abstract
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).
Inventors: |
Campbell; Kris H.; (Poplar
Grove, IL) ; Lemmers, JR.; Glenn C.; (Loves Park,
IL) ; Smith; Doren C.; (Rockford, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hamilton Sundstrand Corporation |
Charlotte |
NC |
US |
|
|
Family ID: |
54979431 |
Appl. No.: |
14/576292 |
Filed: |
December 19, 2014 |
Current U.S.
Class: |
415/69 |
Current CPC
Class: |
F16C 2326/43 20130101;
F16D 2001/103 20130101; F16C 3/02 20130101; F16D 31/02 20130101;
F16D 1/101 20130101; F01D 1/20 20130101; F16C 2380/26 20130101 |
International
Class: |
F01D 1/20 20060101
F01D001/20 |
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.degree..+-.5.degree..
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.degree. 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.
Description
BACKGROUND OF THE INVENTION
[0001] 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.
[0002] 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.
[0003] Due to packaging constraints, components of the hydraulic
unit, such as nested, coaxial, variable and fixed shafts must be
redesigned.
BRIEF DESCRIPTION OF THE INVENTION
[0004] According 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).
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] 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:
[0006] FIG. 1 is a schematic diagram of a generator system of an
aircraft;
[0007] FIG. 2 is a cross-sectional schematic view of an example of
an integrated drive generator (IDG);
[0008] FIG. 3 is a cross-sectional view of an example of a
hydraulic unit of an integrated drive generator;
[0009] FIG. 4 is a perspective view of a fixed coaxial shaft
configured for use in a hydraulic unit according to an embodiment
of the invention;
[0010] FIG. 5 is a top view of the fixed coaxial shaft of FIG. 4
according to an embodiment of the invention;
[0011] FIG. 6 is a cross-sectional view of the fixed coaxial shaft
taken along line A-A of FIG. 5 according to an embodiment of the
invention;
[0012] FIG. 7 is a detail view of section B of the fixed coaxial
shaft of FIG. 6 according to an embodiment of the invention;
and
[0013] FIG. 8 is a cross-sectional view of one of the plurality of
splines taken along line C-C of FIG. 6 according to an embodiment
of the invention.
[0014] 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 INVENTION
[0015] Referring now to FIG. 1, an example of a generator system 10
is schematically illustrated. The system 10 includes a gas turbine
engine 12 that provides rotational drive to an integrated drive
generator (IDG) 16 through an accessory drive gearbox 14 mounted on
the gas turbine engine 12. The accessory drive gearbox is coupled
to a spool of the engine 12, and the speed of the spool varies
throughout the entire engine operation.
[0016] An example of an IDG 16 including a housing 18 is shown in
FIG. 2. In the illustrated embodiment, the IDG 16 includes an input
shaft configured to receive rotational drive from the accessory
drive gearbox 14. The rotational speed of the input shaft varies
depending upon the operation of the engine. To this end, a
hydraulic unit 32 cooperates with the differential assembly 28 to
convert the variable rotational speed from the input shaft to a
fixed rotational output speed to the generator 24.
[0017] Referring now to FIG. 3, an example of a hydraulic unit 32
of the IDG 16 is illustrated in more detail. The hydraulic unit 32
includes a variable displacement hydraulic pump 34 and a fixed
displacement hydraulic motor 36. The pump 34 and motor 36 have
respective cylinder blocks 38 and 40 which are arranged for
rotation about a common axis A within a housing 42 on opposite
sides of a stationary port plate 44 of the hydraulic unit 32. The
port plate 44 is formed with apertures 46 through which hydraulic
fluid communication between the pump 34 and the motor 36 is
established during normal operation of the hydraulic unit 32. A
biasing mechanism 48 resiliently biases the cylinder blocks 38, 40
in the direction of the port plate 44.
[0018] 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.
[0019] 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.
[0020] Referring now to FIGS. 4-8, a fixed coaxial shaft 60 of the
hydraulic unit 32 according to an embodiment of the invention is
illustrated in more detail. The shaft 60 includes a substantially
elongated non-uniform body 62 having a first end 64, a second,
opposite end 66, and a substantially hollow interior 68 that
extends between the first and second ends 64, 66. The overall
length of the body 62 is about 2.678.+-.0.005 inches
(6.802.+-.0.0127 centimeters). In one embodiment, the outer
diameter of the body is about 0.640.+-.0.0005 inches
(1.626.+-.0.0013 centimeters). In addition, the inner diameter of
the body may be about 0.517.+-.0.010 inches (1.313.+-.0.0254
centimeters). The first end 64 of the shaft 60 may include a
chamfer 70 extending outwardly at about a 60.degree. angle such
that the inner diameter at the first end 64 of the body 62 is about
0.580.+-.0.010 inches (1.473.+-.0.0254 cm). Similarly, a chamfer 72
may be formed in the second, opposite end 66 of the body 62. In one
embodiment, the chamfer 72 at the second end 66 is substantially
identical to the chamfer 70 arranged at the first end 64.
[0021] 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.
TABLE-US-00001 TABLE 1 External Spline Dimensions Data for External
Involute Splines Type Fillet Root Side Fit Class D Pitch Diameter
.7500 in No. of Teeth 18 Pitch Fraction 24/48 Base Circle Diameter
.6495 in Pressure Angle 30.degree. Max Form Diameter .708 in Min
Dim. Over Two Wires .8600 in Wire Size 0.08 Major Diam .792 + .000
- .005 in Minor Diam .667 + .000 - .014 in Additional Reqs when Max
effective size is not gaged Max Profile Variation .0010 in Max Lead
Variation .0003 in Circular Tooth Thickness Max Actual .0583 in
Circular Tooth Thickness Min Actual .0568 in Max Diam Over Two
Wires .8623 in Max Index Variation .0015 in
[0022] 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).
[0023] A radius, best illustrated in FIG. 7, may be formed at the
interface of the exterior 74 of the body 62 and the ends 80, 84,
82, 86 of the plurality of first and second splines 76, 78. In one
embodiment, the radius is about 0.030.+-.0.010 inches
(0.076.+-.0.0254 centimeters). In addition, a chamfer 90 may be
formed at the first ends 80, 82 of the plurality of first and
second splines 76, 78. The chamfer 90 may have a width, parallel to
a longitudinal axis X of the shaft 60, of about 0.018.+-.0.010
inches (0.046.+-.0.0254 centimeters), and may extend at
45.degree..+-.5.degree..
[0024] Referring now to FIG. 8, a cross-section of one of the
plurality of first and second splines 76, 78 is illustrated in more
detail. In the illustrated, non-limiting embodiment, the distance
between the midpoint M and an end 80, 84, 82, 86 of each of the
first and second splines 76, 78 is about 0.215 inches (0.546
centimeters). The periphery of each of the splines 76, 78 extending
between the midpoint M and the ends 80, 84, 82, 86 thereof includes
a radius of about 10 inches. A first point P on the periphery of
the first and second splines 76, 78 is located at a distance
parallel to the longitudinal axis X of about 0.200 inches (0.508
centimeters) from the midpoint M and at a vertical distance from
the midpoint M of about 0.0020.+-.0.0005 inches (0.005.+-.0.001
centimeters). A second point R on the periphery of the first and
second splines 76, 78 is located at a distance from the midpoint M,
parallel to the longitudinal axis, of about 0.100 inches (0.0254
centimeters) and at a vertical distance of about 0.0005.+-.0.0003
inches (0.001.+-.0.00076 centimeters) from the midpoint M.
[0025] 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.
* * * * *