FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. Title of the Invention
GEARBOX ASSEMBLY AND METHOD FOR MAINTAINING AN GEARBOX ASSEMBLY
2. Applicant(s)
Name Nationality Address
ROMAX TECHNOLOGY LIMITED British Romax Technology Centre University
of Nottingham Innovation Park
Triumph Road Nottingham
Nottinghamshire NG7 2TU
Great Britain
3. Preamble to the description
The following specification particularly describes the invention and the manner in which it is to be performed
2
TECHNICAL FIELD
The present invention relates to planetary gearboxes having a high
speed output. In particular it relates to an assembly for the high speed
components of a planetary gearbox having a cover facilitating access to
5 these components for maintenance. The components include a high
speed shaft and a high speed intermediate shaft assembly.
BACKGROUND ART
Wind turbine drivetrains commonly consist of an aerodynamic rotor,
which is supported on a rotor shaft, itself supported on one or more
10 bearings, which support the shaft relative to the turbine structure while
permitting rotation around the rotor axis. The rotor shaft is connected to a
speed increasing gearbox, commonly comprising a number of planetary
and/or parallel gear stages. The output of this gearbox is then connected
by a further shaft to a generator which produces the electrical output.
15 Figure 1 is a perspective view of a non-limiting example of a wind
turbine. Although an offshore wind turbine is shown, it should be noted
that the description below may be applicable to other types of wind
turbines. The wind turbine 102 includes rotor blades 104 mounted to a hub
100, which is supported by a nacelle 108 on a tower 114. Wind causes the
20 rotor blades 104 and hub 106 to rotate about a main axis. This rotational
energy is delivered to a power transmission system housed within the
nacelle 108.
3
Figure 2 illustrates a non-limiting example a schematic cross
sectional diagram of a prior art wind turbine gear box 18. The gear box 18
includes a first stage, a second stage and a third stage. The first stage of
the gear box 18 includes an input shaft 24 (comprising a planet carrier 26),
5 a ring gear 28, a plurality of planet gears 30, a sun gear 32 and a bearing
arrangement 34. The second stage of the gear box 18 includes a ring
gear 36, a plurality of planet gears 38, a sun gear 40 and a planet carrier
42 including a non-rotating support component torsionally connected to a
fixed or ground point on the wind turbine, such as nacelle 108. The third,
10 or final, stage of the gear box 18 includes a first output gear 44, also
known as the high speed wheel, a second output gear 48 and an output
shaft 50, also known as the high speed shaft. The third stage first output
gear 44 is connected to the first stage sun gear 32 and is driven by the
first stage sun gear 32.
15 The power transmission system housed within nacelle 108 of the
wind turbine 102 includes a main rotor shaft (also known and referred to
as a low-speed shaft) which is connected to the hub 100 via a main
bearing. The input shaft 24 is connected to hub 100 and is arranged to
rotate about the longitudinal axis 60. One end of gearbox 18 is connected
20 to the low speed shaft and output shaft 50 is, or is connected to the highspeed
shaft. The high speed intermediate assembly includes sun gear 30
and output gear 44. The output shaft 50 provides an input to the
generator.
4
WO2011/0757737 discloses an arrangement for replacing or
maintaining a high speed shaft in the tower/nacelle in which a detachable
module includes second output gear 48 and output shaft 50.
Maintenance or replacement of the high speed wheel (output gear 44)
5 on tower poses a number of problems as it requires removal of the high
speed intermediate assembly. Figure 3 shows a prior art design having a
rear cover 310 of similar diameter to the gear box housing, which makes it
difficult to be detached from the gearbox housing. It also means that the
lubricant has to be drained from the gearbox before the rear cover is
10 removed.
One approach has been to have a top cover on the gearbox, which
can be removed without draining the lubricant from the gearbox. However,
the high speed shaft and the high speed intermediate shaft have to be
removed before the high speed intermediate gear can be hoisted out.
15 DISCLOSURE OF INVENTION
The present invention provides a solution to these problems by
removing the need to drain all the lubricant from the gear box and allowing
the high speed intermediate shaft assembly to be accessed or removed
from the gearbox.
20 According to a one aspect of the present invention, an assembly for a
horizontally mounted planetary gearbox comprises high speed
components of the gearbox; a housing for the high speed components;
5
and a collar located at the output end of the housing and extending radially
inward from an outer surface of the housing. This arrangement means that
the collar retains lubricant in the gearbox when the gearbox is stationary.
Preferably, the collar includes a gap, which means that one or more
5 of the high speed components pass through the gap in the collar. It also
means that components offset from the central axis of the gearbox are not
impeded by the collar. Preferably, the high speed components include a
high speed shaft and a mechanical pump, both of which are offset from
the central axis of the gearbox.
10 Preferably, the housing comprises a cover comprising one or more
holes. This means that one or more of the high speed components can
pass through the holes in the collar. The high speed components include a
high speed shaft, a mechanical pump, and a high speed intermediate shaft.
The first two of these are offset with respect to the central axis of the
15 gearbox, and the third is coaxial. Preferably, the cover comprises means
for reversible connection to the collar. This means that the cover has a
diameter which is smaller than the diameter of the housing, which
facilitates its removal from the housing.
Preferably, the assembly also comprises a bearing housing, the
20 bearing housing including engagement means for one or more guide bars,
and a high speed intermediate shaft assembly comprising a gear, the gear
including one or more holes through which one or more guide bars can
pass for engagement with the bearing housing. This means that the high
6
speed intermediate shaft assembly can be moved along the guide bars
and out of the housing. Preferably, the high speed intermediate shaft
assembly can be supported by an external hoist prior to disengagement of
the guide bars.
5 According to another aspect, the present invention includes a method
for maintaining an assembly for a horizontally mounted planetary gearbox
of the type disclosed above, the method comprising the steps of:
(a) removing the high speed shaft assembly;
(b) checking a level of lubricant within the gearbox and if the level
10 of lubricant is above a height of the collar draining sufficient
lubricant by means of a mechanical pump so that the level of
lubricant is below a height of the collar;
(c) removing the mechanical pump;
(d) engaging the guide bars with the bearing housing;
15 (e) moving the high speed intermediate shaft assembly along the
guide bars and out of the housing;
(d) supporting the high speed intermediate shaft assembly by the
external hoist;
(g) disengaging the guide bars; and
20 (h) lowering the assembly onto a support platform for servicing.
7
BRIEF DESCRIPTION OF DRAWINGS
The invention will now be described with reference to Figures 1-4:
Figure 1 shows an external view of an offshore wind turbine;
Figure 2 shows a schematic diagram of a wind turbine gear box;
5 Figure 3 shows a prior art cover for a gearbox;
Figure 4 shows a schematic of an assembly of the present invention;
Figure 5 shows a schematic of a method for maintaining a high
speed intermediate assembly;
Figure 6 shows a view of an assembly of the present invention;
10 Figure 7 shows a schematic view illustrating a method for
maintaining an assembly of the present invention; and
Figure 8 shows a view of an assembly of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to Figures 4 and 5, an assembly 400 for a horizontally
15 mounted planetary gearbox comprises high speed components of the
gearbox; a housing 402 for the high speed components; and a collar 404
located at the output end of the housing and extending radially inward
from an outer surface of the housing 402. This arrangement means that
the collar retains lubricant 406 in the gearbox when the gearbox is
20 stationary.
8
The collar includes a gap 502, which means that one or more of the
high speed components pass through the gap in the collar. It also means
that components offset from the central axis of the gearbox are not
impeded by the collar. The high speed components include a high speed
5 shaft 408 and a mechanical pump 410, both of which are offset from the
central axis of the gearbox.
The housing comprises a cover 410 comprising one or more holes
510. This means that one or more of the high speed components can pass
through the holes in the collar. The high speed components include a high
10 speed shaft 414, a mechanical pump 412, and a high speed intermediate
shaft 408. The first two of these are offset with respect to the central axis
of the gearbox, and the third is coaxial. The cover comprises means for
reversible connection to the collar. This means that the cover has a
diameter which is smaller than the diameter of the housing, which
15 facilitates its removal from the housing.
The assembly also includes engagement means for one or more
guide bars, and a high speed intermediate shaft assembly comprising a
gear 420, the gear including one or more holes 422 through which one or
more guide bars 520 can pass for engagement. Referring to Figure 6, this
20 means that the high speed intermediate shaft assembly can be moved
along the guide bars and out of the housing. Preferably, the high speed
intermediate shaft assembly can be supported by an external hoist prior
602 to disengagement of the guide bars.
9
According to another aspect, the present invention includes a method
for maintaining an assembly for a horizontally mounted planetary gearbox
of the type disclosed above, the method comprising the steps of:
(a) removing the high speed shaft assembly;
5 (b) checking a level of lubricant within the gearbox and if the level
of lubricant is above a height of the collar draining sufficient
lubricant by means of a mechanical pump so that the level of
lubricant is below a height of the collar;
(c) removing the mechanical pump;
10 (d) engaging the guide bars with the bearing housing;
(e) moving the high speed intermediate shaft assembly along the
guide bars and out of the housing;
(d) supporting the high speed intermediate shaft assembly by the
external hoist;
15 (g) disengaging the guide bars; and
(h) lowering the assembly onto a support platform for servicing.
The assembly of the present invention is suitable for any gear box,
which when mounted and stationery is a substantially horizontal plane so
that oil is retained by the collar.
20 The present invention also includes a gearbox comprising the
assembly disclosed above, and a wind turbine comprising such a gearbox.
10
WE CLAIM:
1. An assembly for a horizontally mounted planetary gearbox, the
assembly comprising:
high speed components of the gearbox;
5 a housing for the high speed components; and
a collar located at the output end of the housing and extending
radially inward from an outer surface of the housing;
wherein the collar retains lubricant in the gearbox when the gearbox
is stationary.
10
2. The assembly according to claim 1, in which the collar includes a gap.
3. The assembly according to claim 2, in which one or more of the high
speed components pass through the gap in the collar.
15
4. The assembly according to claim 3, in which the high speed
component includes a high speed shaft.
5. The assembly according to claim 3 or claim 4, in which the high
20 speed component includes a mechanical pump.
6. The assembly according to claim 1 or claim 2, in which the housing
comprises a cover.
11
7. The assembly according to claim 6, in which the cover comprises
one or more holes.
5 8. The assembly according to claim 7, in which one or more of the high
speed components pass through the holes in the collar.
9. The assembly according to claim 8, in which the high speed
component includes a high speed shaft.
10
10. The assembly according to claim 8 or claim 9, in which the high
speed component includes a mechanical pump.
11. The assembly according to any of claims 8 to 10, in which the high
15 speed component includes a high speed intermediate shaft.
12. The assembly according to any of claims 6 to 11, in which the cover
comprises means for reversible connection to the collar.
20 13. The assembly according to claim 12, in which a diameter of the cover
is less than a diameter of the housing.
12
14. The assembly according to claim 1, in which the high speed
component includes a bearing housing, the bearing housing
including engagement means for one or more guide bars.
5 15. The assembly according to claim 14, in which the high speed
component includes a high speed intermediate shaft assembly
comprising a gear, the gear including one or more holes through
which one or more guide bars can pass for engagement with the
bearing housing, wherein the high speed intermediate shaft
10 assembly can be moved along the guide bars and out of the housing.
16. The assembly according to claim 15, in which the high speed
intermediate shaft assembly can be supported by an external hoist
prior to disengagement of the guide bars.
15
17. A gearbox comprising the assembly according to any preceding
claim.
18. A wind turbine comprising the gearbox according to claim 17.
20
19. A method for maintaining an assembly for a horizontally mounted
planetary gearbox according to claim 15 or claim 16, the method
comprising the steps of:
13
(a) removing the high speed shaft assembly;
(b) checking a level of lubricant within the gearbox and if the level
of lubricant is above a height of the collar draining sufficient
lubricant by means of a mechanical pump so that the level of
5 lubricant is below a height of the collar;
(c) removing the mechanical pump;
(d) engaging the guide bars with the bearing housing;
(e) moving the high speed intermediate shaft assembly along the
guide bars and out of the housing;
10 (d) supporting the high speed intermediate shaft assembly by the
external hoist;
(g) disengaging the guide bars; and
(h) lowering the assembly onto a support platform for servicing.