Bearings – Rotary bearing – Roller drill bit
Reexamination Certificate
1999-05-20
2001-01-30
Footland, Lenard A. (Department: 3682)
Bearings
Rotary bearing
Roller drill bit
C415S160000
Reexamination Certificate
active
06179469
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns a rotation mechanism which provides a couple for, and thus rotates, an annular ring such as that used to drive the fins in a rotation mechanism for rotating the adjustable fins of a gas turbine.
2. Description of the Invention
A rotation apparatus for varying the angle of and rotating the static fins in a gas turbine is shown in FIG.
1
. (This figure is a preferred embodiment of the present invention and not an example of the prior art.) Rotary shafts
2
a
of (static) fins
2
, which are rotatably mounted in compartment
1
, are connected to rotation ring
4
through levers
3
. When the rotation ring
4
is rotated, the fins
2
rotate as indicated by the arrows in FIG.
1
.
The rotation ring
4
has a number of supports
6
on it which are supported by washers
5
on the surface of compartment
1
when the ring rotates.
Although only a single fin
2
is shown in
FIG. 1
, the relevant gas turbine in fact has a number of such fins at regular intervals around the periphery of compartment
1
. When the rotation ring
4
rotates, all the fins
2
rotate simultaneously.
An example of a rotation mechanism for rotating the ring which drives the fins in a gas turbine is a single link
10
which rotates rotation ring
4
, as provided in Japanese Patent Publication (Kokai) Showa 59-7708. With this design, the force which rotates rotation ring
4
is balanced with the opposing force to supports
6
on rotation ring
4
. However, in this rotation mechanism, the radius of rotary shaft
2
a
of fin
2
, which is supported in the compartment
1
, and the point of action of the force are in a ratio of nearly 1:1. Thus the drag torque due to friction will be considerable.
Further, the radius of the rotation ring
4
is greater than that of compartment
1
, and consequently the ring is more prone to warping. All of the above-mentioned factors have an adverse effect on the smooth operation of the rotation mechanism which rotates rotation ring
4
.
The rotation devices which the prior art provides to solve the problems discussed above are the rotation mechanisms pictured in
FIGS. 9
,
10
and
11
, which rotate rotation ring
4
through a couple.
FIGS. 9 and 10
show a prior art rotation mechanism for rotating the ring which drives the rotation of the fins.
In
FIGS. 9 and 10
,
4
is the rotation ring which rotates fins
2
as shown in FIG.
1
.
Pins
51
and
52
are inserted through holes on opposite sides of the outer edge of the rotation ring
4
. One end of each of the follower links
10
and
11
is rotatably mounted to the pins
51
and
52
, respectively.
Operating lever
17
is rotatably mounted through operating shaft
18
to bracket
43
, which is fixed to the top of stage
40
(See FIG.
1
).
Pin
200
is inserted through one end of the lever
17
. One end of each of links
14
and
15
is rotatably mounted in the pin
200
, as is shown in FIG.
10
.
To the left and right of the bracket
43
are brackets
41
and
42
, both of which are also fixed to the stage
40
. L-shaped levers
12
and
13
, which face in opposite directions, are rotatably mounted to brackets
41
and
42
, respectively, through lever shafts
56
and
55
.
The other end of link
14
is connected through pin
58
, in such a way that the link is free to rotate, to one end of L-shaped lever
12
, the lever on the right side of the rotation mechanism. The other end of link
15
is connected through pin
57
, in such a way that the link is free to rotate, to one end of lever
13
, the lever on the left side of the rotation mechanism.
The other end of the L-shaped lever
12
is connected through pin
53
to the free end of follower link
10
. The other end of the L-shaped lever
13
is connected through pin
54
to the free end of follower link
11
.
With this sort of rotation mechanism for the rotation ring, a drive means, such as a servo hydraulic cylinder (not shown), rotates operating lever
17
, through the mediation of the operating shaft
18
, in the direction shown by arrow Z
1
in FIG.
9
. When this happens, links
14
and
15
move horizontally to the right, as indicated by arrow Z
2
. L-shaped lever
12
rotates counterclockwise on shaft
56
, as shown by arrow Z
3
. L-shaped lever
13
also rotates counterclockwise on its lever shaft
55
, as shown by arrow Z
4
. Link
10
on the right side moves upward as shown by arrow Z
5
; link
11
on the left side moves downward as shown by arrow Z
6
.
Thus the links
10
and
11
provide a couple to rotation ring
4
, which rotates counterclockwise as shown by arrow Z
7
. As the rotation ring
4
rotates, fins
2
are rotated in the specified direction.
In the prior art design shown in
FIGS. 9 and 10
, links
10
and
11
, which drive rotation ring
4
, are connected to opposite sides of the rotation ring. The forces which operate on rotation ring
4
are coupled. Because the load which is concentrated at a single point diminishes, the resultant force which acts on support
6
approaches zero. There is less warping and friction, the rotation mechanism operates smoothly, and the operating force itself decreases.
In the prior art design shown in
FIGS. 9 and 10
, however, links
14
and
15
are directly attached to a single pin
200
, which is mounted to one end of operating lever
17
, and so they move left and right. Thus links
14
and
15
have very little freedom and must move at an excessive speed, which may result in increased frictional drag. Also, a large operating force is needed to drive rotation ring
4
through the links
14
and
15
. The configuration makes it difficult to eliminate the effects of warping due to the load on links
14
and
15
and the levers connected to them or due to the thermal expansion of these components, which in turn may result in excessive operating force or defective operation.
The prior art device shown in
FIG. 11
is a rotation mechanism for driving the rotation of the rotation ring
4
using a driving means such as a servo hydraulic cylinder.
In this design, two cylinders, namely servo oil hydraulic cylinder
60
and slave cylinder
61
, are arranged symmetrically 180° apart and connected by pipes
64
and
65
. The free end of piston rod
66
of servo oil hydraulic cylinder
60
is connected to pin
51
on the outer edge of rotation ring
4
. The free end of piston rod
67
of slave cylinder
61
is connected to pin
52
, which is 180- opposite pin
51
on the outer edge of rotation ring
4
.
When piston
62
of cylinder
60
is hydraulically driven, piston rod
66
moves in the direction indicated by arrow Y
1
and piston rod
67
of slave cylinder
61
moves in the direction indicated by arrow Y
2
. The couple generated in this way rotates rotation ring
4
in the direction indicated by arrow Y
3
.
If a turbine has multiple rows of fins to be driven, a rotation mechanism using a servo hydraulic cylinder as in the prior art device pictured in
FIG. 11
will require a set of hydraulic drive components including a servo hydraulic cylinder
60
and a slave cylinder
61
for each row. This drives up the parts count and increases the cost of the device. Furthermore, the relative forces between the cylinder equipped with a pilot relay (servo hydraulic cylinder
60
) and slave cylinder
61
may be unbalanced so that it becomes impossible to achieve the required operating force.
SUMMARY OF THE INVENTION
In view of the shortcomings inherent in the prior art, the object of the present invention is to provide a rotation mechanism for rotating a rotary ring which has the following features: the number of parts it requires will be reduced as much as possible; its configuration will be simple and economical to build; the operating drag of the ring will be low; any distortion resulting from the load or thermal expansion will be reliably absorbed; and the ring will be rotated reliably with a small operating force.
The first embodiment of this invention developed to solve these problems is a rotation mechanism for rotating an annular rotation ring in w
Ichiryu Taku
Yashiki Tadao
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Footland Lenard A.
Mitsubishi Heavy Industries Ltd.
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