U.S. patent application number 10/592693 was filed with the patent office on 2008-10-23 for variable capacity oil pump.
Invention is credited to Jens Demtroder, Poul Spaerhage Frokjaer.
Application Number | 20080260545 10/592693 |
Document ID | / |
Family ID | 32241216 |
Filed Date | 2008-10-23 |
United States Patent
Application |
20080260545 |
Kind Code |
A1 |
Frokjaer; Poul Spaerhage ;
et al. |
October 23, 2008 |
Variable Capacity Oil Pump
Abstract
The invention relates to a wind turbine being provided with a
fluid displacement means for ensuring a certain increased pumping
capacity at a certain reduced rotational speed of the main shaft of
the rotor and thus of a drive shaft from a gear box of the wind
turbine. The invention also relates to a wind turbine being
provided with fluid displacement means for ensuring a certain
increased pumping capacity at a certain increased rotational speed
of the main shaft of the rotor and thus of a drive shaft from a
gear box of the wind turbine. The means may be mechanical,
hydraulic, pneumatic or electrical. Additionally, the invention
relates to a method for operating a wind turbine being provided
with such fluid displacement means.
Inventors: |
Frokjaer; Poul Spaerhage;
(Gistrup, DK) ; Demtroder; Jens; (Ronde,
DK) |
Correspondence
Address: |
CANTOR COLBURN, LLP
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Family ID: |
32241216 |
Appl. No.: |
10/592693 |
Filed: |
December 23, 2004 |
PCT Filed: |
December 23, 2004 |
PCT NO: |
PCT/DK2004/000916 |
371 Date: |
September 26, 2007 |
Current U.S.
Class: |
417/212 ;
417/405; 417/410.1 |
Current CPC
Class: |
F03D 80/70 20160501;
F05B 2270/327 20130101; F04B 17/02 20130101; F04B 49/20 20130101;
F05B 2260/98 20130101; Y02E 10/72 20130101; F04B 41/06
20130101 |
Class at
Publication: |
417/212 ;
417/405; 417/410.1 |
International
Class: |
F04B 49/20 20060101
F04B049/20; F04B 17/02 20060101 F04B017/02; F04B 17/03 20060101
F04B017/03 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 12, 2004 |
DK |
PA 2004 00409 |
Claims
1. A wind turbine with a fluid supply system comprising a fluid
displacement pump, said fluid displacement pump having a drive
shaft and a coupling arrangement between at least a first
individual pumping member and at least a second individual pumping
member, where at least one of said pumping members is individually
controllable, said fluid supply system being capable of exhibiting
a certain increased pumping capacity at a certain reduced or
increased rotational speed of the drive shaft, said increased
pumping capacity being obtained by controlling a pumping capacity
of at least one of said pumping member.
2. A wind turbine according to claim 1, where the fluid supply
system comprises a fluid inlet and a fluid outlet of the first
pumping member and a fluid inlet and a fluid outlet of the second
pumping member, the fluid inlet of the first pumping member leading
from a fluid vessel and the fluid outlet of the first pumping
member leading only to a main fluid conduit, and the fluid inlet of
the second pumping member leading from a fluid vessel and the fluid
outlet of the second pumping member leading both to the main fluid
conduit and to a branch fluid conduit of the fluid system, said
branch fluid conduit being provided with a control valve for
controlling a flow of fluid to the branch fluid conduit in relation
to a flow of fluid to the main fluid conduit.
3. A wind turbine according to claim 2, said branch fluid conduit
leading to one of the following fluid elements: the inlet of the
first pump, a fluid reservoir and the inlet of the second pump.
4. A wind turbine according to claim 1, where the fluid supply
system comprises a fluid inlet and a fluid outlet of the first
pumping member and a fluid inlet and a fluid outlet of the second
pumping member, the fluid inlet of the first pumping member leading
from a fluid outlet of a hydraulic motor, and the fluid outlet of
the first pumping member leading to a fluid inlet of the hydraulic
motor, and the fluid inlet of the second pumping member leading
from a fluid vessel and the fluid outlet of the second pumping
member leading to a main fluid conduit, and said hydraulic motor
being provided with a control valve for controlling a flow of fluid
to the hydraulic motor in relation to a flow of fluid to the main
fluid conduit.
5. A wind turbine according to claim 1, where the fluid supply
system comprises a fluid inlet and a fluid outlet of the first
pumping member and a fluid inlet and a fluid outlet of the second
pumping member, the fluid inlet of the first pumping member leading
from a fluid outlet of an auxiliary hydraulic motor, and the fluid
outlet of the first pumping member leading to a fluid inlet of the
auxiliary hydraulic motor, and the fluid inlet of the second
pumping member leading from a fluid vessel and the fluid outlet of
the second pumping member leading to a main fluid conduit, said
auxiliary hydraulic motor intended for driving at least one of the
following speed variable motors: an electrical motor, a pneumatic
motor and another hydraulic motor, and said motor being provided
with control means for controlling the rotational speed of an
output shaft in relation to a flow of fluid to the main fluid
conduit.
6. A wind turbine with a fluid supply system comprising a fluid
displacement pump, said pump being provided with a coupling
arrangement between at least a first pumping member and at least an
electric energy generating element providing electrical energy for
an electric motor intended for driving the first pumping member,
said at least first pumping member exhibiting a certain reduced or
increased pumping capacity at a certain reduced or increased
rotational speed of the drive shaft.
7. A wind turbine according to claim 1, where said drive shaft
comprises a common drive shaft intended for driving at least the
first pumping member and at least a second pumping member by a
driving means driving the drive shaft, and said pump further being
provided with a mechanical coupling arrangement between the at
least first pumping member and the at least second pumping
member.
8. A wind turbine according to claim 7, where the mechanical
coupling arrangement is provided by means of a single shaft
constituting an output shaft of the first pumping member and an
input shaft of the second pumping member, said single shaft thereby
being common to the two pumping members.
9. A wind turbine according to claim 1, where said drive shaft
comprises a drive shaft intended for driving at least the second
pumping member by a primary driving means driving the drive shaft,
said pump having an output shaft intended for driving at least the
first pumping member by a secondary driving means driving the
output shaft, said pump further being provided with a hydraulic
coupling arrangement between the second pumping member and the
driving means driving the output shaft.
10. A wind turbine according to claim 9, wherein the hydraulic
coupling arrangement is provided by means of a hydraulics outlet
constituting an output from the second pumping member, and a
hydraulics inlet constituting an input to a hydraulic motor being
the secondary driving means and intended for driving the first
pumping member, and the hydraulic motor comprising the output shaft
intended for driving an input shaft of the at least first pumping
member, said output shaft and said input shaft thereby being common
to the hydraulic motor and the at least first pumping member.
11. A wind turbine according to claim 1, where said drive shaft
comprises a drive shaft intended for driving at least the second
pumping member by a primary driving means driving the drive shaft,
said pump having an output shaft intended for driving at least the
first pumping member by a secondary driving means driving the
output shaft, said pump further being provided with a pneumatic
coupling arrangement between the at least second pumping member and
the driving means driving the output shaft.
12. A wind turbine according to claim 11, where the pneumatic
coupling arrangement is provided by means of a pneumatics outlet
constituting an output from a second pumping member, and a
pneumatics inlet constituting an input to a pneumatic motor being
the secondary driving means and intended for driving the first
pumping member, and the pneumatic motor comprising the output shaft
intended for driving an input shaft of the at least first pumping
member, said output shaft and said input shaft thereby being common
to the pneumatic motor and the at least first pumping member.
13. A wind turbine according to claim 1, where said drive shaft
comprises a drive shaft intended for driving at least the second
pumping member by a primary driving means driving the drive shaft,
and said pump having an output shaft intended for driving at least
the first pumping member by a secondary driving means driving the
output shaft, said pump further being provided with a electrical
coupling arrangement between the at least second pumping member and
the driving means driving the output shaft.
14. A wind turbine according to claim 13, wherein the electrical
coupling arrangement is provided by means of an electric outlet
constituting an output from the second pumping member, and an
electric inlet constituting an input to an electrical motor being
the secondary driving means and intended for driving the first
pumping member, and the electrical motor comprising the output
shaft intended for driving an input shaft of the at least first
pumping member, said output shaft and said input shaft thereby
being common to the electrical motor and the at least first pumping
member.
15. A wind turbine according to claim 1, where the coupling
arrangement is a coupling capable of infinitely variably adjusting
rotational speed of the second pumping member independently on any
change in rotational speed of the drive shaft.
16. A wind turbine according to claim 1, where the coupling
arrangement is a coupling capable of stepwise adjusting rotational
speed of the second pumping member independently on any change in
rotational speed of the drive shaft.
17. A wind turbine according to claim 1, where a driving means of
said fluid displacement pump is an electrical driving means such as
an electrical motor.
18. A wind turbine according to claim 1, where a driving means of
said fluid displacement pump is a mechanical driving means such as
a gearbox.
19. A wind turbine according to claim 1, where a driving means of
said fluid displacement pump is a hydraulic driving means such as a
hydraulic motor.
20. A wind turbine according to claim 1, where a driving means of
said fluid displacement pump is a main shaft of a rotor of a wind
turbine.
21. A wind turbine according to claim 1, where the at least first
pumping member and the at least second pumping member are capable
of pumping the fluid independently on a rotational direction of the
first and second pumping member.
22. A wind turbine according to claim 1, where said coupling
arrangement comprises an epicyclic 3-way differential with one
shaft connected to an output drive shaft of the first pumping
member, one shaft connected to an input drive shaft of the second
pumping member, and the third shaft connected to a speed-variable
motor.
23. A wind turbine according to claim 22, where said coupling
arrangement is a hydrostatic transmission from the output drive
shaft of the first pumping member to the input drive shaft of the
second pumping member.
24. A wind turbine according to any of claim 22, where said
mechanical coupling arrangement is a hydrodynamic transmission from
the output drive shaft of the first pumping member to the input
drive shaft of the second pumping member.
25. A wind turbine according to claim 1, where said coupling
arrangement is any one of the following coupling arrangements; a
mechanical coupling, a viscous coupling, an electric coupling, an
electro-mechanical coupling, and where said coupling arrangement is
established between an output drive shaft of the first pumping
member and an input drive shaft of the second pumping member.
26. A wind turbine according to claim 1, where said coupling
arrangement is based on electro-technical principles comprising
electromagnetic transmission or Eddie-current.
27. A wind turbine according to claim 1, where at least an inlet of
said first pumping member is submerged in fluid of a fluid
reservoir for supplying lubrication fluid at least to the first
pumping member.
28. A wind turbine according to claim 10, where at least the
hydraulics inlet constituting an input to a hydraulic motor being a
secondary driving means and intended for driving the first pumping
member, is positioned at a horizontal level below a horizontal
level of an outlet of a fluid reservoir for supplying pump fluid at
least to the hydraulic motor.
29. A method of controlling a fluid pressure in a fluid supply
system of a wind turbine according to claim 1, the method
comprising: monitoring at least one parameter influencing a fluid
pressure in the fluid supply system of the wind turbine,
controlling a coupling arrangement between at least a first pumping
member and at least a second pumping member thereby obtaining a
certain increased pumping capacity at a certain value of the at
least one parameter being monitored.
30. A method according to claim 29, further comprising: monitoring
rotational speed of a drive shaft of at least one of the first
pumping member and the second pumping member, controlling the
coupling arrangement between the at least first pumping member and
the at least second pumping member, thereby obtaining a certain
increased pumping capacity at a certain value of the rotational
speed of the drive shaft.
31. A method according to claim 29, further comprising monitoring
an increment of rotational speed of a drive shaft of at least one
of the first pumping member and the second pumping member,
controlling the coupling arrangement between the at least first
pumping member and the at least second pumping member, thereby
obtaining a certain increased pumping capacity at a certain reduced
increment of the rotational speed of the drive shaft.
32. A method according to claim 29, further comprising monitoring
wind speed at a site of the wind turbine as a parameter influencing
rotational speed of a main shaft of the wind turbine, controlling
the coupling arrangement between the at least first pumping member
and the at least second pumping member, when the wind speed
exhibits a value below 100 m/s during a continuous period of time
of at least 10 seconds, thereby obtaining a certain increased
pumping capacity at a certain low value of the wind speed at the
site of the wind turbine.
33. A method according to claim 29, further comprising monitoring
wind speed at a site of the wind turbine as a parameter influencing
rotational speed of a main shaft of the wind turbine, controlling
the coupling arrangement between the at least first pumping member
and the at least second pumping member, when the wind speed
exhibits a value above 1 m/s during a continuous period of time of
at least 10 seconds, thereby obtaining a certain increased pumping
capacity at a certain high value of the wind speed at the site of
the wind turbine.
34. A method according to claim 29, further comprising monitoring
rotational speed of a main shaft of the wind turbine influencing
rotational speed of the drive shaft from a gearbox of the wind
turbine, controlling the coupling arrangement between the at least
first pumping member and the at least second pumping member, when
the rotational speed of the main shaft exhibits a value below 100
rpm during a continuous period of time of at least 10 seconds
thereby obtaining a certain increased pumping capacity at a certain
low value of the rotational speed of the main shaft.
35. A method according to claim 29, further comprising monitoring
rotational speed of a main shaft of the wind turbine influencing
rotational speed of the drive shaft from a gearbox of the wind
turbine, controlling the coupling arrangement between the at least
first pumping member and the at least second pumping member, when
the rotational speed of the main shaft exhibits a value above 0.01
rpm during a continuous period of time of at least 10 seconds
thereby obtaining a certain increased pumping capacity at a certain
high value of the rotational speed of the main shaft.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a fluid displacement pump having a
drive shaft, and where said pump is provided with a coupling
arrangement between at least a first pumping member and at least a
second pumping member. The invention also relates to a fluid supply
system comprising a fluid inlet and a fluid outlet of the first
pump and a fluid inlet and a fluid outlet of the second pump.
Furthermore, the invention relates to a wind turbine with a fluid
supply system comprising a fluid displacement pump. The invention
also relates to a method of controlling a fluid pressure in a fluid
supply system of a wind turbine.
BACKGROUND OF THE INVENTION
[0002] Lubrication and cooling of mechanical equipment such as
gearboxes, bearings or combustion engines is typically obtained by
either of the following principles:
[0003] An oil pump with constant geometric volume is driven by a
constant or variable speed electric motor, more recently also by
frequency controlled motors allowing a continuous variation of the
pump speed and thereby the oil flow. This arrangement allows
continuous adjustment of the flow to the momentary needs by an
external controller as long as electrical power is available. In
case of loss of this external source of energy, the oil flow
ceases, and a safe run-down of the equipment cannot be granted.
[0004] An oil pump with constant geometric volume is driven by a
shaft of the equipment, for example a power-take-off (PTO) from a
gearbox. The oil flow is hence directly dependent on the speed of
the drive shaft, and cannot be adjusted to the momentary needs.
This becomes a particular disadvantage in applications where the
speed of the PTO-shaft varies. Obtaining sufficient oil supply at
the lowest operating speeds may require selection of quite large
pumps, which will then supply too much oil in the upper speed
range. The surplus oil needs to be wasted through bypasses, which
increases the system's complexity.
[0005] Additionally, excessive circulation deteriorates the oil,
causes premature ageing, and will typically require increased oil
volumes. Compared to electrical driven pumps, such shaft driven
pumps allow a safe run-down also in case the external power supply
collapses. The efficiency will typically be higher, as no
additional power transformation is required.
[0006] A common solution combining the advantages of shaft-driven
and electrical pumps is installing two independent systems where
the shaft-driven pump cares for sufficient supply when no external
power is available, and where the electrical pump or both. i.e.,
also the shaft-driven pumps in parallel provide the oil supply in
regular operation. Two independent systems are more costly and more
complex systems
[0007] Shaft driven pumps, where the geometric volume of the oil
pump is varied, is a third possibility of obtaining variable oil
flow independent of the speed of the equipment. This technology is
typically used in automotive systems and hydraulic applications,
but has technical limitations for large oil flow, or for fluids
with high viscosity as typically used in industrial applications,
due to the limited suction capacity of those pump designs.
SUMMARY OF THE INVENTION
[0008] It is one object according to one aspect of the present
invention to combine the advantages of a shaft driven fluid pump
such as an oil pump in respect to safe run-down with the variable
flow characteristics of electrically driven pumps for lubrication
systems for large fluid flow and high viscosity.
[0009] It is another object according to a second aspect of the
present invention to combine the advantages of a shaft driven fuel
pump such as an oil pump in respect to safe run-up with the
variable flow characteristics of electrically driven pumps for
lubrication systems for large fluid flow and high viscosity.
[0010] The object of the invention according to the first aspect of
the invention may be obtained by a pump being provided with a
coupling arrangement between at least a first pumping member and at
least a second pumping member, said at least first and second
pumping members in total exhibiting a certain increased pumping
capacity at a certain reduced rotational speed of the drive
shaft.
[0011] By providing an increased pumping capacity at a certain
reduced rotational speed of the drive shaft, chosen mechanical
parts such as the gearbox of a wind turbine, said parts still being
in limited motion during idling of the wind turbine, will be
provided a much better lubrication despite the often very limited
rotational speed of the rotor.
[0012] The object of the invention according to the second aspect
of the invention may be obtained by a pump having a drive shaft,
said pump being provided with a coupling arrangement between at
least a first pumping member and at least a second pumping member,
said at least first and second pumping members in total exhibiting
a certain increased pumping capacity at a certain increased
rotational speed of the drive shaft.
[0013] By providing an increased pumping capacity at a certain
increased rotational speed of the drive shaft, a wind turbine, when
in an emergency situation, will be provided a much better
lubrication of the different mechanical parts, such as gears of a
gear box, being in very fast motion during an emergency
situation.
[0014] According to a possible embodiment of the invention, said
drive shaft constitutes [0015] a common drive shaft intended for
driving at least a first rotating pumping member and at least a
second rotating pumping member by a driving means driving the drive
shaft, and [0016] said pump further being provided with a
mechanical coupling arrangement between the at least first pumping
member and the at least second pumping member.
[0017] By having the drive shaft driving at least two pumping
members, and by providing a mechanical coupling arrangement, one of
the pumping members may be coupled out and in as necessary.
Alternatively, or additionally, the pumping capacity of one of the
pumping members may be adjusted infinitely or stepwise by means of
adjusting a transfer ratio of the mechanical coupling arrangement
between the two pumping members.
[0018] The system exhibits a plurality of individual pumps arranged
on the same drive shaft and coupled together by a coupling
arrangement transmitting all the torque of the drive shaft or only
a limited amount of the torque of the drive shaft to one or more of
the pumps. In the case all the torque is transmitted to all of the
pumps, the device is incorporated in a system capable of
distributing the hydraulic fluid in a selected and controlled
manner.
[0019] In an alternative embodiment, the mechanical coupling
arrangement is provided by means of a single shaft constituting an
output shaft of the first pumping member and an input shaft of the
second pumping member, said single shaft thereby being common to
the two pumping members. This embodiment establishes no means for
coupling the one pumping member out and in and no means for
infinitely or stepwise adjustment of transfer ratio. However, the
object of the invention may still be obtained by selecting
different pumping members having different fluid capacities and
having differing incremental change of flow, when the rotational
speed of the drive shaft decreases or increases.
[0020] According to a possible embodiment of the invention said
drive shaft comprises [0021] a drive shaft intended for driving at
least a second rotating pumping member (2) by a primary driving
means driving the drive shaft, and said pump having [0022] an
output shaft intended for driving at least a first rotating pumping
member by a secondary driving means driving the output shaft,
[0023] said pump further being provided with a hydraulic coupling
arrangement between the at least second pumping member and the
driving means driving the output shaft.
[0024] By providing a hydraulic coupling arrangement, the
possibilities are enhanced of adjusting the fluid flow capacity of
the fluid supply system. Also, the possible disadvantages of
mechanical coupling arrangements such as wear and slow change of
torque ratio may be avoided. Also the advantages of a mechanical
pumping member and an electrically controlled pump is obtained by
employing a hydraulic coupling arrangement.
[0025] In a preferred embodiment of a hydraulic coupling
arrangement, [0026] the hydraulic coupling arrangement is provided
by means of a hydraulics outlet constituting an output from a
second pumping member, and [0027] a hydraulics inlet constituting
an input to a hydraulic motor intended for driving the first
pumping member, and [0028] the hydraulic motor comprising the
output shaft intended for driving an input shaft of the at least
first rotating pumping member, said output shaft and said input
shaft thereby being common to the hydraulic motor and the at least
first pumping member.
[0029] An arrangement with a common output shaft from the hydraulic
motor and input shaft of the first pumping member result in no
mechanical coupling arrangements at all being employed, and thus
all torque transfer takes place by means of hydraulics.
[0030] In alternative embodiments along the inventive concept of a
hydraulic coupling arrangement, said pump is in stead provided with
a pneumatic coupling arrangement between the at least first pumping
member and the secondary driving means driving the output shaft, or
even in the alternative, said pump is in stead being provided with
an electric coupling arrangement between the at least first pumping
member and the secondary driving means driving the output
shaft.
[0031] Pneumatic and electric coupling arrangements has a limited
capability of transferring torque from the pneumatic motor and
electric motor, respectively, to the first pumping member, but
pneumatic and electric coupling arrangements have the advantage of
being more "clean" transfer means than hydraulics, if leakage of
torque transfer "medium" should occur. In the event of an
electrical coupling arrangement, also the speed of adjustment is
often faster than hydraulic and pneumatic coupling
arrangements.
[0032] The coupling arrangement, independently on whether the
coupling arrangement is mechanical, hydraulic, pneumatic, electric
or a combination of two or more of such coupling arrangements, is
all the time a coupling either capable of infinitely variably
adjusting the rotational speed of the second pumping member
independently on any change in the rotational speed of the drive
shaft, or capable of stepwise adjusting the rotational speed of the
second pumping member independently on any change in the rotational
speed of the drive shaft.
[0033] A combination of an infinite adjustment and a stepwise
adjustment may be envisaged, perhaps with an infinite adjustment,
when the rotational speed of the drive shaft is at a certain
decreased level such as during idling of the wind turbine, and a
stepwise adjustment, when the rotational speed of the drive shaft
is at a certain increased level such as during a possible emergency
situation during the operation of the wind turbine.
[0034] Preferably, the driving means for driving the drive shaft is
a mechanical driving means such as an output shaft of a gearbox.
Alternative driving means for driving the drive shaft may however
be utilised, e.g. an electrical driving means such as an electrical
motor, or e.g. a hydraulic driving means such as a hydraulic motor,
or e.g. a main shaft of a rotor of a wind turbine. During idling of
a wind turbine, both electrical energy from the grid and mechanical
energy from the rotor of the wind turbine are available. During an
emergency situation, often the electrical energy from the grid is
not available. Therefore, electrical driving means is not the best
means during an emergency situation. It necessitates either a
battery back-up or the possibility of extracting electrical energy
from the generator.
[0035] In a possible embodiment, the at least first pumping member
and the at least second pumping member are capable of pumping the
fluid independently on the rotational direction of the first and
second pumping member. If possible, a preferred one-way rotational
direction of the pumping members will enable use of pumping
impellers being dedicated to one way of rotation, and thus possibly
exhibiting a higher pumping efficiency.
[0036] Mechanical coupling arrangement are possibly an epicyclic
3-way differential with one shaft connected to an output drive
shaft of the first pumping member, one shaft connected to an input
drive shaft of the second pumping member, and the third shaft
connected to a speed-variable motor, e.g. an electrical motor or a
hydraulic motor. Such an epicyclic 3-way differential is a good and
reliable mechanical means for obtaining infinite adjustment of the
coupling arrangement. Mechanical coupling arrangements may also
encompass a hydrostatic transmission from the output drive shaft of
the first pumping member to the input drive shaft of the second
pumping member. Hydrostatic coupling arrangements has the advantage
of providing possibilities of reducing or even eliminating
operating problems also at different than normal operating
conditions such as maintaining sufficient lubrication of bearings
etc. during very light wind conditions or during electrical power
failure.
[0037] The object may also be obtained by a fluid outlet of the
first pump leading only to a main fluid conduit, and the fluid
outlet of the second pump leading both to the main fluid conduit
and leading to a branch fluid conduit of the fluid system, said
branch fluid conduit being provided with a control valve for
controlling the flow of fluid through the branch fluid conduit in
relation to the flow fluid to the main fluid conduit. Such a branch
fluid conduit being provided with a control valve is a good and
reliable hydraulic or pneumatic means. for obtaining infinite
adjustment of the coupling arrangement. The branch fluid conduit
will be leading to one of the following fluid elements: The inlet
of the first pump, a fluid reservoir, and the inlet of the second
pump.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] The invention will be hereafter be described with reference
to the drawings, where
[0039] FIG. 1 shows a first possible embodiment of a fluid
displacement pump according to the invention and of a fluid supply
system according to the invention,
[0040] FIG. 2 shows a second possible embodiment of a fluid
displacement pump according to the invention and of a fluid supply
system according to the invention,
[0041] FIG. 3-12 show diagrams of various control methods for
controlling the fluid displacement pump according to the invention,
and.
[0042] FIG. 13 shows a diagram of a possible relation between the
rotational speed of a drive shaft for the fluid displacement pump
and the capacity of fluid from the fluid displacement pump.
DETAILED DESCRIPTION OF THE INVENTION
[0043] FIG. 1 shows a fluid displacement pump comprising a drive
shaft 3, possibly a power take-out from the drive train of a energy
converting plant such as a wind turbine. The drive shaft is
intended for driving at first pump 1 and a second pump 2.
[0044] In the embodiment shown, the first pump is a separate
pumping member and the second pump is also a separate pumping
member. In an alternative embodiment, the first pumping member and
the second pumping member could be part of a common fluid
displacement pump, perhaps contained in one housing or at least
forming one unit.
[0045] The drive shaft 3 is intended for driving the first pump 1
and the second pump 2 simultaneously. An output shaft 4 of the
first pump is coupled by a purely mechanical or a hydromechanical
or perhaps a pneumo-mechanical coupling arrangement 5 to an input
shaft 6 of the second pump. The coupling arrangement 5 may transfer
all the torque from the output shaft 4 of the first pump to the
input shaft 6 of the second pump, or the coupling arrangement 5 may
transfer only part of the torque. The coupling arrangement 5 may be
set to a fixed ratio of torque transfer, or the coupling
arrangement 5 may be adjustable for selecting and controlling the
ratio of torque transferred. In an alternative embodiment, the
coupling arrangement 5 is fixed, and the coupling arrangement 5 is
provided by the output shaft 4 of the first pump 1 being the same
as the input shaft 6 of the second pump 2, i.e. a single shaft
thereby being common to the two pumps 1,2.
[0046] The fluid supply system comprises a fluid reservoir 7
supplying fluid to an individual first inlet 8 and an individual
second inlet 9 of the first pump 1 and the second pump 2,
respectively. In the embodiment shown, the fluid reservoir 7 is a
reservoir common to both the first pump 1 and the second pump 2.
Alternatively, more fluid reservoirs may be provided, one for each
of the pumps 1,2 of the fluid displacement system. Also, in the
embodiment shown, each of the pumps 1,2 has an individual inlet 8,9
leading directly from the fluid reservoir 7 to the pumps 1,2.
Alternatively, each of the pumps 1,2 may have individual inlets 8,9
provided as parallel inlets, but being branched off a single common
conduit (not shown), said single common inlet leading from the
fluid reservoir 7 to each of the branched off individual inlets
8,9.
[0047] The first pump 1 and the second pump 2 are provided with an
individual first outlet 10 and an individual second outlet 11,
respectively. The first outlet 10 of the first pump 1 leads
directly, via a first fluid conduit 12, to a main fluid conduit 13
and further to a gear mechanism (not shown) or other mechanical
mechanism intended for being lubricated. The first fluid conduit 12
may be provided with a parallel fluid conduit (not shown) equipped
with a cooling unit (not shown) for cooling all or part of the
fluid of the first outlet 10. Also, the first outlet 10 is provided
with a non-return valve 14 opening at a certain high pressure of
the fluid in the first fluid conduit 12. The second outlet 11 of
the second pump 2 leads to the main fluid conduit 13 and further to
the gear mechanism (not shown) or other mechanical mechanism via a
second fluid conduit 15. The second fluid conduit 15 may be
provided with a parallel fluid conduit (not shown) equipped with a
cooling unit (not shown) for cooling all or part of the fluid of
the second outlet 11. The second fluid conduit 15 is provided with
a non-return valve 16 opening at a certain high pressure of the
fluid in the second fluid conduit 15.
[0048] The second outlet 11 of the second pump also leads to a
branch fluid conduit 17, said branch fluid conduit 17 leading to
the first inlet 8 of the first pump 1. The branch fluid conduit 17
is provided with a control valve 18. The control valve is
adjustable and may be controlled automatically or manually to open
at a certain low pressure of the fluid in the main fluid conduit
13. The certain low pressure in the main conduit 13 may be
monitored directly by monitoring the fluid pressure in the main
fluid conduit 13. Alternatively, the certain low pressure in the
main fluid conduit 13 may be monitored indirectly by monitoring the
fluid pressure in the first fluid conduit 12 and in the second
fluid conduit 15, and adding the pressure in each of these conduits
12,15 for establishing the pressure in the main fluid conduit
13.
[0049] The second pump 2 is intended for increasing the amount of
fluid being led to the gear mechanism or other mechanical mechanism
in such situations, where the rotational speed of the drive shaft 3
is reduced to a certain low level or is increased to a certain high
level. Such situation may be where the rotational speed of the
drive shaft 3 is reduced or increased in relation to a regular
rotational speed of the drive shaft during regular operating
conditions of the gear mechanism or other mechanical mechanism.
During a regular rotational speed, the fluid pressure in the main
fluid conduit 13 is adequate for providing a lubrication ensuring
that the gear mechanism (not shown) or other mechanical equipment
being lubricated is not subjected to excessive wear due to a
non-adequate lubrication of the mechanism.
[0050] During regular operating conditions, the fluid from the
outlet 11 of the second pump 2 is directed into the branch fluid
conduit 17, through the control valve 18 and to the inlet 8 of the
first pump 1. The control valve allows the fluid in the branch
conduit 17 to pass the control valve 18 due to the fact that the
fluid pressure in main fluid conduit 13 is monitored and
established as being adequately high for lubrication of the
mechanism. Thus, the fluid from the second pump 2 is added to the
fluid leading to the first pump 1.
[0051] Alternatively to, or in addition to, providing a control
valve 18, the coupling arrangement 5 between the output shaft 4 of
the first pump and the input shaft 6 of the second pump may be
adjustable in order to adjust the torque transferred from the
output shaft of the first pump to the input shaft of the second
pump. Thereby, the amount of fluid pumped from the second pump to
the inlet of the first pump along the branch fluid conduit 17 is
adjusted. Thus, the control valve may be omitted, but the control
valve may also be maintained for obtaining enhanced possibilities
of controlling the pumping system.
[0052] During reduced or increased rotational speed of the drive
shaft 3, the control valve 18 is closed or the fluid is passed
through the control valve 18 at only a decreased flow. Thereby, the
pressure of the fluid from the outlet 11 of the second pump 2 is
increased and is passed through the second fluid conduit 15 through
the non-return valve 16 and to the main fluid conduit 13.
[0053] During reduced rotational speed of the drive shaft 3, the
first pump is still pumping fluid from the first outlet 8 to the
main fluid conduit 13, but due to the reduced rotational speed of
the drive shaft 3, only a limited amount of fluid is pumped to the
main fluid conduit 13 by the first pump, i.e. the fluid capacity is
reduced. However, because of the second pump also pumping fluid to
the main fluid conduit 13, the total amount of fluid, i.e. the
total fluid capacity, pumped to the main fluid conduit 13 is
sufficient to lubricate the gear mechanism, also during reduced
rotational speed of the drive shaft.
[0054] During increased rotational speed of the drive shaft 3, the
first pump is pumping fluid from the first outlet 8 to the main
fluid conduit 13, but despite the increased rotational speed of the
drive shaft 3, still a limited, non-sufficient amount of fluid is
pumped to the main fluid conduit 13 by the first pump, i.e. the
fluid capacity is too low. However, because of the second pump also
pumping fluid to the main fluid conduit 13, the total amount of
fluid, i.e. the total fluid capacity, pumped to the main fluid
conduit 13 is sufficient to lubricate the gear mechanism, also
during increased, but still limited, rotational speed of the drive
shaft.
[0055] As a supplement or as an alternative, the pumping capacity
of second pump 2 may be controlled by the coupling arrangement 5
between the output shaft 4 of the first pump 1 and the input shaft
6 of the second pump 2. Thus, controlling of the pumping capacity
of the second pump 2 by means of the coupling arrangement 5 may be
employed together with the fluid system described above and shown
in the figure.
[0056] Alternatively, controlling of the pumping capacity of the
second pump 2 by means of the coupling arrangement 5 may be
employed with a fluid system described above and shown in the
figure, however, without the branch fluid conduit 17 and without
the control valve 18 described and shown, and perhaps also without
the non-return valve 16 of the second fluid conduit.
[0057] In case the pumping capacity of the second pump 2 is
controlled also, or only, by means of the coupling arrangement 5,
different types of coupling arrangements 5 may be employed. The
coupling arrangement 5 may be a coupling capable of infinitely
variably adjusting the rotational speed of the input shaft 6 second
pump 2 independently on any change in the rotational speed of the
drive shaft 3. The coupling arrangement 5 may also be a coupling
capable of stepwise adjusting the rotational speed of the input
shaft 6 of second pump 2 independently on any change in the
rotational speed of the drive shaft 3.
[0058] The driving means (not shown) driving the drive shaft 3 may
be an electrical driving means such as an electrical motor, or a
mechanical driving means such as an output shaft from a gearbox, or
a hydraulic driving means such as a hydraulic motor.
[0059] The coupling arrangement 5 shown in FIG. 1 may comprise an
epicyclic 3-way differential with one shaft connected to an output
drive shaft of the first pumping member, one shaft connected to an
input drive shaft of the second pumping member, and the third shaft
connected to a speed-variable motor, for example an electrical
motor or a hydraulic motor.
[0060] The coupling may comprise a hydrostatic transmission from
the output drive shaft of the first pump to the input drive shaft
of the second pump, or a hydrodynamic transmission from the output
drive shaft of the first pump to the input drive shaft of the
second pump, or a mechanical coupling, a viscous coupling or
electric coupling or a electro-mechanical coupling from the output
drive shaft of the first pump to the input drive shaft of the
second pump. Furthermore, the coupling may be based on
electro-technical principles such as electromagnetic transmission
or Eddie-current.
[0061] FIG. 2 shows a fluid displacement pump also comprising a
drive shaft 3, possibly a power take-out from the drive train of a
energy converting plant such as a wind turbine. The drive shaft 3
is intended for driving a pump 2. A purely hydraulic coupling
arrangement 5 is constituted by a closed-loop fluid conduit leading
from a fluid outlet 11 of the pump 2 to a fluid inlet 21 of a
hydraulic motor 20 and from a fluid outlet 22 of the hydraulic
motor 20 and to a fluid inlet 9 of the pump 2.
[0062] The closed-loop hydraulic coupling arrangement 5 is provided
with a control valve 23. The control valve 23 is adjustable and may
be controlled automatically or manually to adjust the pressure of
the fluid in the closed-loop hydraulic coupling arrangement at a
position in advance of the fluid inlet 21 of the hydraulic motor
20. The pressure in the closed-loop hydraulic coupling arrangement
5 may be monitored anywhere along the closed-loop hydraulic
coupling arrangement 5. Alternatively, adjustment of the control
valve 23 may be effected by monitoring the pressure in a main fluid
conduit 13 of the fluid supply system for establishing the pressure
in the closed-loop hydraulic coupling arrangement 20.
[0063] An output shaft 24 of the hydraulic motor 20 is coupled by a
purely mechanical or a hydromechanical or perhaps a
pneumo-mechanical coupling arrangement 25 to an input shaft 26 of a
first pump 1. The coupling arrangement 25 may transfer all the
torque from the output shaft 24 of the hydraulic motor 20 to the
input shaft 26 of the first pump 1, or the coupling arrangement 25
may transfer only part of the torque. The coupling may be set to a
fixed ratio of torque transfer, or the coupling may be adjustable
for selecting and controlling the ratio of torque transferred. In
an alternative embodiment, the coupling arrangement 25 is fixed,
and the coupling arrangement is provided by the output shaft 24 of
the hydraulic motor 20 being the same as the input shaft 26 of the
first pump 1, i.e. a single shaft thereby being common to the
hydraulic motor 20 and the first pump 1.
[0064] In the embodiment shown, the first pump is a separate
pumping member and the second pump is also a separate pumping
member. In an alternative embodiment, the first pumping member and
the second pumping member could be part of a common fluid
displacement pump, perhaps contained in one housing or at least
forming one unit.
[0065] The fluid supply system comprises a fluid reservoir 7
supplying fluid to an individual first inlet 8 of the first pump 1.
In the embodiment shown, the first pump 2 is submerged in the fluid
in the fluid reservoir 7, thereby ensuring that the first pump in
all situations is always supplied with hydraulic lubrication fluid.
This placement of the first pump 1 necessitates a fluid tight
sealing of the coupling arrangement 25 at a position between the
hydraulic motor 20 and the first pump 1, when the coupling
arrangement 25 passes trough the boundaries of the reservoir 7.
[0066] Alternatively, the hydraulic motor 20 may also be submerged
in the fluid in the fluid reservoir 7, thus eliminating the need
for a fluid tight sealing of the coupling arrangement 25 between
the hydraulic motor 20 and the first pump 1. Even alternatively,
the first pump 1 may be placed outside the fluid in the fluid
reservoir, such as shown in FIG. 1, together with the hydraulic
motor 20 also being placed outside the fluid in the fluid reservoir
7, such as shown in FIG. 2.
[0067] The first pump is provided with an individual first outlet
10. The first outlet of the first pump 1 leads directly, via a
first fluid conduit 12, to the main fluid supply 13 and further to
a gear mechanism (not shown) or other mechanical mechanism intended
for being lubricated. In the embodiment shown, the first supply
conduit 12 and the main fluid supply 13 are not actually divided
into to conduits, but are one and the same conduit.
[0068] During reduced rotational speed of the drive shaft 3, the
first pump is still pumping fluid from the first outlet 8 to the
main fluid conduit 13, but due to the reduced rotational speed of
the drive shaft 3, only a limited amount of fluid is pumped to the
main fluid conduit 13 by the first pump, i.e. the fluid capacity is
reduced. However, because of the pump 2 still operating and because
of hydraulic motor being adjustable, the pumping capacity of the
first pump may be increased in order to pump more fluid to the main
fluid conduit 13. Thus, the total amount of fluid, i.e. the total
fluid capacity, pumped to the main fluid conduit 13 may be
maintained to be sufficient to lubricate the gear mechanism, also
during reduced rotational speed of the drive shaft.
[0069] During increased rotational speed of the drive shaft 3, the
first pump is pumping fluid from the first outlet 8 to the main
fluid conduit 13, but despite the increased rotational speed of the
drive shaft 3, still a limited, non-sufficient amount of fluid is
pumped to the main fluid conduit 13 by the first pump, i.e. the
fluid capacity is too low. However, because of the pump 2 operating
and because of hydraulic motor being adjustable, the pumping
capacity of the first pump 1 may be increased in order to pump more
fluid to the main fluid conduit 13. Thus, the total amount of
fluid, i.e. the total fluid capacity, pumped to the main fluid
conduit 13 may be increased to be sufficient to lubricate the gear
mechanism, also during increased, but still limited, rotational
speed of the drive shaft.
[0070] In the embodiment shown, between the first outlet 10 and the
fluid conduit 12 parallel fluid conduits are provided. Four of the
parallel conduits are equipped with filters 27, and one of the
parallel conduits is equipped with a non-return valve 14. Other
numbers than four conduits with filters, such as more or less
numbers, may be provided and more numbers than one conduit with a
non-return valve may be provided.
[0071] During regular operating conditions, the fluid from the
first pump 1 is directed trough the all the filters 27. If one,
more or all of the filters 27 for some reason are blocking the
direction of fluid from the outlet 10 to the first fluid conduit
12, the non-return valve 14 will open, ensuring adequate
lubrication of the gear mechanism or other mechanism to be
lubricated, although by non-filtered fluid from the fluid reservoir
7.
[0072] In the embodiment shown, between the first outlet 10 and the
fluid conduit 12 a cooling unit 28 is provided for cooling all or
part of the fluid of the first outlet 10. Alternatively to
providing the cooling unit 28 in the fluid conduit 12, one or more
cooling units may be provided in the parallel conduits, where also
the filters 27 are provided. Thereby, both filtering and cooling
may be accomplished in more than one conduit. If one cooling unit
in one of the parallel conduits fails, other cooling units provided
in the other parallel conduits may still be available for cooling
the fluid.
[0073] The fluid displacement pump according to the invention may
comprise an automatic actuator for varying the torque ratio of said
coupling arrangement 5. The automatic actuator may be a mechanical,
electrical, or hydraulic device connected to a control system. The
automatic actuator may be closed-loop controlled on base of any
parameter from the oil supply system, for example based on pressure
in at least one of the outlets 10,11 of the at least two pumps 1,2.
The automatic actuator may be regulated by an external control
system based on one or more parameters describing the performance
of the fluid supply system, or the performance of the gear
mechanism or other mechanism to be lubricated, or even the
performance of the entire equipment which the fluid supply system
and the mechanism are part of. The automatic actuator may be
controlled in a fail-safe mode such that a defined flow is obtained
at system failure, for example to secure a safe run-down of the
equipment in case of loss of external power.
[0074] In the embodiment shown in FIG. 2, the second pumping member
2 is described as being a hydraulic pump supplying hydraulic
pressure to the hydraulic motor 20. However, the second pumping
member 2 may also be a pneumatic pump supplying pneumatic pressure
to a pneumatic motor. The fundamental principle is the same as when
employing a hydraulic pump and a hydraulic motor, however, the
coupling arrangement is of pneumatic nature rather than of
hydraulic nature. When the second pumping member is a hydraulic
pump, an outlet of a fluid reservoir for supplying hydraulic fluid
to the hydraulic is preferably provided at a horizontal level above
the inlet of the hydraulic pump, thereby ensuring that the
hydraulic pump is all situations is supplied with hydraulic pump
fluid.
[0075] Even alternatively, the second pumping member 2 may be
substituted by an electric energy generating element, such as a
generator, positioned at the same location of the fluid supply
system as the second pump 2 shown in FIG. 2, and intended for
supplying electrical energy to an electric motor 20, positioned at
the same location of the fluid supply system as the hydraulic motor
shown in FIG. 2. The fundamental principle is the same as when
employing a hydraulic pump and a hydraulic motor, however, the
coupling arrangement is of electrical nature rather than of
hydraulic nature.
[0076] FIG. 3-12 are diagrams of various modes of controlling the
fluid displacement pump. The various modes shown in FIGS. 3-12 all
take the basis in the coupling being hydraulic between a
gear-driven pump, i.e. the first pumping member, and the fluid pump
for lubricating bearing and the like, i.e. the second pumping
member.
[0077] In all diagrams at least one hydraulic pump 30 is shown in
the top of the figures, said pump being driven through an input
shaft 31 of the hydraulic pump, said input shaft being driven by a
gear shaft from the gear box, and also at least one hydraulic motor
32 is shown in the bottom of the figures, said pump intended for
driving an input shaft of the gear pump (not shown) through an
output shaft 33 of the hydraulic motor.
[0078] FIG. 3 shows the hydraulic pump 30 being uni-directional,
i.e. being capable of pumping fluid in-dependently of the
rotational direction of the input shaft, and thus being capable of
pumping fluid both "from the left side" and "from the right side"
of the hydraulic pump as seen in the figure. The corresponding
hydraulic motor 32 is however a one-directional motor, i.e. being
capable of operating only when fluid is pumped to an inlet at the
right side of the hydraulic motor as seen in the figure. The
hydraulic motor is provided with a variable control means 34, said
means enabling varying the rotational speed of the output shaft of
the hydraulic motor. In the embodiment shown, the variable control
means is intended for being controlled by an electrically operating
adjustment means 35, but hydraulic or mechanical control means
and/or adjustment means is also possible.
[0079] If fluid is pumped by the hydraulic pump from the left side
as seen in the figure, the fluid is pumped to a one-way valve 36
having a reduced opening pressure compared to other valves 38,39 of
the system. The fluid is then pumped to the right side of the
hydraulic motor, said right side having an inlet, and thus fluid
pumped to the right side of the hydraulic motor enabling operation
of the hydraulic motor. From the hydraulic motor, the fluid is
passed to a return valve 37 also having a decreased opening
pressure compared to other valves 38,39. Thus, if fluid is pumped
from the left side of the hydraulic pump, a driving torque will be
transmitted from the output shaft of the hydraulic motor to the
gear pump (not shown).
[0080] If fluid is pumped by the hydraulic pump from the right side
as seen in the figure, the fluid is pumped to a one-way valve 38
having an increased opening pressure compared to other valves 36,37
of the system. The fluid is then pumped also to the right side of
the hydraulic motor, said right side having an inlet, and thus
fluid pumped to the right side of the hydraulic motor also enabling
operation of the hydraulic motor. From the hydraulic motor, the
fluid is passed to a return valve 39 also having an increased
opening pressure compared to other valves 36,37. Thus, if fluid is
pumped from the right side of the hydraulic pump, a driving torque
will also be transmitted from the output shaft of the hydraulic
motor to the gear pump (not shown).
[0081] The reason for having return valves with increased and
decreased opening pressure, respectively, is based on the
rotational direction of the input shaft of hydraulic pump. The
rotational direction of the input shaft of the hydraulic pump is
dependent on the rotational direction of the rotor (not shown) of
the wind turbine. The possible feature of return valves in a
hydraulic rectifier having both return valves with increased
opening pressure and return valves with decreased opening pressure,
applies to all embodiments as described below incorporating
hydraulic rectifiers. The hydraulic rectifier is explained
below.
[0082] If the hydraulic pump is pumping fluid from the left side of
the hydraulic pump, the rotational direction of the input shaft
corresponds to a reversed rotational direction of the rotor of the
wind turbine. A reversed rotational direction of the rotor may be
the case in light wind conditions, where sudden wind gusts may
cause the rotor to rotate reversed compared to the intended
rotational direction of the rotor. In light wind conditions, the
fluid capacity of the hydraulic pump will be reduced, thus the need
for return valves with decreased opening pressure for passing fluid
to the hydraulic motor. Contrary to light wind conditions, i.e. In
normal wind conditions or strong wind conditions, the rotational
direction of the rotor will always be the intended rotational
direction of the rotor, and the fluid will always be supplied from
the right side of the hydraulic pump. In normal and strong wind
conditions, the fluid capacity of the hydraulic pump will be
increased and sufficient, thus the possibility of return valves
with increased opening pressure for passing fluid to the hydraulic
motor. However, in an alternative embodiment, the opening pressure
of all return valves 36-39 may be identical.
[0083] FIG. 4 shows the hydraulic pump 30 being uni-directional,
i.e. being capable of pumping fluid in-dependently of the
rotational direction of the input shaft, and thus being capable of
pumping fluid both "from the left side" and "from the right side"
of the hydraulic pump as seen in the figure. The hydraulic pump is
provided with a variable control means 34, said means enabling
varying the fluid capacity of the hydraulic pump. In the embodiment
shown, the variable control means is intended for being controlled
by an electrically operating adjustment means 35, but hydraulic or
mechanical control means and/or adjustment means is also possible.
The corresponding hydraulic motor 32 is however a one-directional
motor, i.e. being capable of operating only when fluid is pumped to
an inlet at the right side of the hydraulic motor as seen in the
figure.
[0084] If fluid is pumped by the hydraulic pump from the left side
as seen in the figure, the fluid is pumped to a one-way valve 36
having a reduced opening pressure compared to other valves 38,39 of
the system. The fluid is then pumped to the right side of the
hydraulic motor, said right side having an inlet, and thus fluid
pumped to the right side of the hydraulic motor enabling operation
of the hydraulic motor. From the hydraulic motor, the fluid is
passed to a return valve 37 also having a decreased opening
pressure compared to other valves 38,39. Thus, if fluid is pumped
from the left side of the hydraulic pump, a driving torque will be
transmitted from the output shaft of the hydraulic motor to the
gear pump (not shown).
[0085] If fluid is pumped by the hydraulic pump from the right side
as seen in the figure, the fluid is pumped to a one-way valve 38
having an increased opening pressure compared to other valves 36,37
of the system. The fluid is then pumped also to the right side of
the hydraulic motor, said right side having an inlet, and thus
fluid pumped to the right side of the hydraulic motor also enabling
operation of the hydraulic motor. From the hydraulic motor, the
fluid is passed to a return valve 39 also having an increased
opening pressure compared to other valves 36,37. Thus, if fluid is
pumped from the right side of the hydraulic pump, a driving torque
will also be transmitted from the output shaft of the hydraulic
motor to the gear pump (not shown).
[0086] FIG. 5 shows the hydraulic pump being uni-directional, i.e.
being capable of pumping fluid in-dependently of the rotational
direction of the input shaft, thus being capable of pumping fluid
both "from the left side" and "from the right side" of the
hydraulic pump as seen in the figure. The hydraulic pump is
provided with a variable control means 34, said means enabling
varying the fluid capacity of the hydraulic pump. In the embodiment
shown, the variable control means is intended for being controlled
by an electrically operating adjustment means 35, but hydraulic or
mechanical control means and/or adjustment means is also possible.
The corresponding hydraulic motor is also uni-directional, i.e.
capable of exerting a driving torque to the output shaft
in-dependently of whether fluid is provided at an inlet "at the
left side" or at an inlet "at the right side" of the hydraulic
motor as seen in the figure.
[0087] If fluid is pumped by the hydraulic pump either from the
left side or from the right side as seen in the figure, the fluid
is pumped directly either to the left side or to the right side of
the hydraulic motor, both the left side and the right side of the
hydraulic motor having an inlet. Thus, fluid being pumped either to
the left side or to the right side of the hydraulic motor enables
operation of the hydraulic motor and a driving torque being
transmitted from the output shaft of the hydraulic motor to the
gear pump (not shown).
[0088] FIG. 6 shows the hydraulic pump being uni-directional, i.e.
being capable of pumping fluid in-dependently of the rotational
direction of the input shaft, thus being capable of pumping fluid
both "from the left side" and "from the right side" of the
hydraulic pump as seen in the figure. The corresponding hydraulic
motor is also uni-directional, i.e. capable of exerting a driving
torque to the output shaft in-dependently of whether fluid is
provided at an inlet "at the left side" or at an inlet "at the
right side" of the hydraulic motor as seen in the figure. The
hydraulic motor is provided with a variable control means 34, said
means enabling varying the rotational speed of the output shaft of
the hydraulic motor. In the embodiment shown, the variable control
means is intended for being controlled by an electrically operating
adjustment means 35, but hydraulic or mechanical control means
and/or adjustment means is also possible.
[0089] If fluid is pumped by the hydraulic pump either from the
left side or from the right side as seen in the figure, the fluid
is pumped directly either to the left side or to the right side of
the hydraulic motor, both the left side and the right side of the
hydraulic motor having an inlet. Thus, fluid being pumped either to
the left side or to the right side of the hydraulic motor enables
operation of the hydraulic motor and a driving torque being
transmitted from the output shaft of the hydraulic motor to the
gear pump (not shown).
[0090] FIG. 7 shows the hydraulic pump being uni-directional, i.e.
being capable of pumping fluid in-dependently of the rotational
direction of the input shaft, thus being capable of pumping fluid
both "from the left side" and "from the right side" of the
hydraulic pump as seen in the figure. The corresponding hydraulic
motor is also uni-directional, i.e. capable of exerting a driving
torque to the output shaft in-dependently of whether fluid is
provided at an inlet "at the left side" or at an inlet "at the
right side" of the hydraulic motor as seen in the figure.
[0091] If fluid is pumped by the hydraulic pump either from the
left side or from the right side as seen in the figure, the fluid
is pumped directly either to the left side or to the right side of
the hydraulic motor, both the left side and the right side of the
hydraulic motor having an inlet. Thus, fluid being pumped either to
the left side or to the right side of the hydraulic motor enables
operation of the hydraulic motor and a driving torque being
transmitted from the output shaft of the hydraulic motor to the
gear pump (not shown).
[0092] FIG. 8 shows the hydraulic pump being a one-directional
pump, i.e. being capable of operating only when the input shaft is
rotated in one direction and fluid is pumped from an inlet at the
left side of the hydraulic pump as seen in the figure. The
hydraulic pump is provided with a variable control means 34, said
means enabling varying the fluid capacity of the hydraulic pump. In
the embodiment shown, the variable control means is intended for
being controlled by an electrically operating adjustment means 35,
but hydraulic or mechanical control means and/or adjustment means
is also possible. The corresponding hydraulic motor is also
one-directional, i.e. being capable of operating only when fluid is
pumped to an inlet at the left side of the hydraulic motor as seen
in the figure.
[0093] If fluid is pumped by the hydraulic pump from the left side
as seen in the figure, the fluid is pumped directly to the left
side of the hydraulic motor. Thus, fluid being pumped to the left
side of the hydraulic motor enables operation of the hydraulic
motor and a driving torque being transmitted from the output shaft
of the hydraulic motor to the gear pump (not shown).
[0094] FIG. 9 shows the hydraulic pump being a one-directional
pump, i.e. being capable of operating only when the input shaft is
rotated in one direction and fluid is pumped from an inlet at the
left side of the hydraulic pump as seen in the figure. The
corresponding hydraulic motor is also one-directional, i.e. being
capable of operating only when fluid is pumped to an inlet at the
left side of the hydraulic motor as seen in the figure. The
hydraulic motor is provided with a variable control means 34, said
means enabling varying the rotational speed of the output shaft of
the hydraulic motor. In the embodiment shown, the variable control
means is intended for being controlled by an electrically operating
adjustment means 35, but hydraulic or mechanical control means
and/or adjustment means is also possible. FIG. 9 constitutes a best
mode of operation.
[0095] If fluid is pumped by the hydraulic pump from the left side
as seen in the figure, the fluid is pumped directly to the left
side of the hydraulic motor. Thus, fluid being pumped to the left
side of the hydraulic motor enables operation of the hydraulic
motor and a driving torque being transmitted from the output shaft
of the hydraulic motor to the gear pump (not shown).
[0096] FIG. 10 shows the hydraulic pump being uni-directional, i.e.
being capable of pumping fluid in-dependently of the rotational
direction of the input shaft, thus being capable of pumping fluid
both "from the left side" and "from the right side" of the
hydraulic pump as seen in the figure. The corresponding hydraulic
motor is however a one-directional motor, i.e. being capable of
operating only when fluid is pumped to an inlet at the left side of
the hydraulic motor as seen in the figure. A by-pass conduit 40 is
provided between the inlet of the hydraulic motor and an outlet of
the hydraulic motor. Said by-pass conduit is provided with a
variable valve 41 and a variable control means 42 for controlling
the variable valve, said valve and said means enabling varying the
capacity of fluid being passed to the inlet of the hydraulic motor,
independently of the capacity being provided from the either one of
the outlets of the hydraulic pump. In the embodiment shown, the
variable control means is intended for being controlled by an
electrically operating adjustment means 35, but hydraulic or
mechanical control means and/or adjustment means is also
possible.
[0097] If fluid is pumped by the hydraulic pump from the left side
as seen in the figure, the fluid is pumped to a one-way valve 36
having a reduced opening pressure compared to other valves 38,39 of
the system. The fluid is then pumped to the right side of the
hydraulic motor, said right side having an inlet, and thus fluid
pumped to the right side of the hydraulic motor enabling operation
of the hydraulic motor. From the hydraulic motor, the fluid is
passed to a return valve 37 also having a decreased opening
pressure compared to other valves 38,39. Thus, if fluid is pumped
from the left side of the hydraulic pump, a driving torque will be
transmitted from the output shaft of the hydraulic motor to the
gear pump (not shown).
[0098] If fluid is pumped by the hydraulic pump from the right side
as seen in the figure, the fluid is pumped to a one-way valve 38
having an increased opening pressure compared to other valves 36,37
of the system. The fluid is then pumped also to the right side of
the hydraulic motor, said right side having an inlet, and thus
fluid pumped to the right side of the hydraulic motor also enabling
operation of the hydraulic motor. From the hydraulic motor, the
fluid is passed to a return valve 39 also having an increased
opening pressure compared to other valves 36,37. Thus, if fluid is
pumped from the right side of the hydraulic pump, a driving torque
will also be transmitted from the output shaft of the hydraulic
motor to the gear pump (not shown).
[0099] FIG. 11 shows the hydraulic pump being uni-directional, i.e.
being capable of pumping fluid in-dependently of the rotational
direction of the input shaft, thus being capable of pumping fluid
both "from the left side" and "from the right side" of the
hydraulic pump as seen in the figure. The corresponding hydraulic
motor is however a one-directional motor, i.e. being capable of
operating only when fluid is pumped to an inlet at the left side of
the hydraulic motor as seen in the figure. A by-pass conduit 40 is
provided between the one outlet and the other outlet of the
hydraulic pump. Said by-pass conduit is provided with a variable
valve 41 and a variable control means 42 for controlling the
variable valve valve, said valve and said means enabling varying
the capacity of fluid being passed to the inlet of the hydraulic
motor, independently of the capacity being provided from the either
one of the outlets of the hydraulic pump. In the embodiment shown,
the variable control means is intended for being controlled by an
electrically operating adjustment means 35, but hydraulic or
mechanical control means and/or adjustment means is also
possible.
[0100] If fluid is pumped by the hydraulic pump from the left side
as seen in the figure, the fluid is pumped to a one-way valve 36
having a reduced opening pressure compared to other valves 38,39 of
the system. The fluid is then pumped to the right side of the
hydraulic motor, said right side having an inlet, and thus fluid
pumped to the right side of the hydraulic motor enabling operation
of the hydraulic motor. From the hydraulic motor, the fluid is
passed to a return valve 37 also having a decreased opening
pressure compared to other valves 38,39. Thus, if fluid is pumped
from the left side of the hydraulic pump, a driving torque will be
transmitted from the output shaft of the hydraulic motor to the
gear pump (not shown).
[0101] If fluid is pumped by the hydraulic pump from the right side
as seen in the figure, the fluid is pumped to a one-way valve 38
having an increased opening pressure compared to other valves 36,37
of the system. The fluid is then pumped also to the right side of
the hydraulic motor, said right side having an inlet, and thus
fluid pumped to the right side of the hydraulic motor also enabling
operation of the hydraulic motor. From the hydraulic motor, the
fluid is passed to a return valve 39 also having an increased
opening pressure compared to other valves 36,37. Thus, if fluid is
pumped from the right side of the hydraulic pump, a driving torque
will also be transmitted from the output shaft of the hydraulic
motor to the gear pump (not shown).
[0102] FIG. 12 shows the hydraulic pump being uni-directional, i.e.
being capable of pumping fluid in-dependently of the rotational
direction of the input shaft, thus being capable of pumping fluid
both "from the left side" and "from the right side" of the
hydraulic pump as seen in the figure. The corresponding hydraulic
motor is also uni-directional, i.e. capable of exerting a driving
torque to the output shaft in-dependently of whether fluid is
provided at an inlet "at the left side" or at an inlet "at the
right side" of the hydraulic motor as seen in the figure. A by-pass
conduit 40 is provided between the one outlet and the other outlet
of the hydraulic pump. Said by-pass conduit is provided with a
variable valve 41 and a variable control means 42 for controlling
the variable valve, said valve and said means enabling varying the
capacity of fluid being passed to the inlet of the hydraulic motor,
independently of the capacity being provided from the either one of
the outlets of the hydraulic pump. In the embodiment shown, the
variable control means is intended for being controlled by an
electrically operating adjustment means 35, but hydraulic or
mechanical control means and/or adjustment means is also
possible.
[0103] If fluid is pumped by the hydraulic pump either from the
left side or from the right side as seen in the figure, the fluid
is pumped directly either to the left side or to the right side of
the hydraulic motor, both the left side and the right side of the
hydraulic motor having an inlet. Thus, fluid being pumped either to
the left side or to the right side of the hydraulic motor enables
operation of the hydraulic motor and a driving torque being
transmitted from the output shaft of the hydraulic motor to the
gear pump (not shown).
[0104] FIG. 13 is a diagram showing a possible relationship between
the rotational speed of the drive shaft 3 (see FIG. 1 and FIG. 2)
and the fluid flow to the gear mechanism or other mechanical
mechanism to be lubricated. The fluid flow is established as the
amount of fluid per time unit, but may also be established by
monitoring the pressure in the main fluid supply 13 (see FIG. 1 and
FIG. 2). The diagram shown is established based on the embodiment
shown in FIG. 2. Similar relationship between the rotational speed
of the drive shaft and the fluid flow will be the case for
embodiments like the one shown in FIG. 1.
[0105] The diagram shows two curves, a first continuous curve with
a linearly proportional extension with the one and same
proportional ratio along the entire extension of the curve, and a
second non-continuous curve with a proportional extension with
different proportional ratios along different extensions of the
curve. The first curve shows the relationship between rotational
speed of drive shaft and fluid flow of a known system employing a
mechanically driven fluid pump. The second curve shows the
relationship between rotational speed of drive shaft and fluid flow
of a system according to the invention, and employing a fluid pump
according to FIG. 2 as described above.
[0106] As can be seen, when employing the known system with a
mechanically driven fluid pump, the fluid flow and thus the
possible lubricating capacity is decreased, whenever the rotational
speed of the drive shaft is decreased, and vice versa. However,
when employing a system according to the present invention, the
fluid flow and thus the possible lubricating capacity is maintained
along long intervals, when the rotational speed of the drive shaft
is decreased, and vice versa. Along an initial interval, the fluid
flow is increasing together with the rotational speed of the drive
shaft. This is also the case, when employing known systems, but
with a much smaller ratio. Thus, by employing the present invention
compared to the known system, a high level of fluid flow, and
thereby a high lubrication capacity, is obtained at a much lower
rotational speed of the drive shaft.
[0107] Along and intermediate interval, when employing the known
system, the fluid flow is still increasing towards the high level
already obtained by the system according to the invention. The high
level of fluid flow, when employing the known system, is obtained
at a certain rotational speed of the drive shaft, marked with a
vertical dotted line in the diagram. The certain rotational speed
of the drive shaft may be as example 1.680 rpm of a drive shaft
from a gearbox of a wind turbine. Subsequent to the certain
rotational speed, along a final interval of the rotational speed of
the drive shaft, the level of fluid flow continues to increase with
a linear proportionality having the same proportional ratio as the
rest of the first curve, i.e. the linear proportionality having the
same ratio as along the initial interval and as along the
intermediate interval.
[0108] When employing the system according to the present
invention, the fluid flow is maintained substantially constant at
the high level of fluid flow during the entire intermediate
interval, when the rotational speed of the drive shaft is
increasing. When reaching the certain rotational speed of the drive
shaft as shown by the vertical dotted line, the system according to
the invention is adjusted for further increasing the fluid flow by
a ratio higher than the ratio of the known system. Thereby, when
exceeding the certain rotational speed of the drive shaft, an even
increased lubrication capacity is obtained along a final interval
of the rotational speed of the drive shaft.
[0109] The course of the second curve may differ depending on the
lubricating capacity necessary at the different rotational speeds
of the drive shaft. Due to the possibility of adjusting the torque
transferred along the coupling arrangement 5 between the first pump
1 and the second pump 2 (see FIG. 1) or between the hydraulic motor
10 and the first pump 1 (see FIG. 2), the fluid flow and thus the
lubricating capacity may be adjusted in response to a certain need
for lubrication at a certain rotational speed of the drive
shaft.
[0110] Adjustment may be accomplished depending on different
parameters such as the size and the type of gear mechanism of the
wind turbine, or the size and type of wind turbine, if perhaps
other mechanical means are to be lubricated. Adjustment may also be
accomplished depending on the present operating conditions of the
wind turbine such as the temperature, the wind speed and the wind
stability or even other parameters, which may influence the
mechanical parts of a wind turbine and thus may influence different
needs for lubrication during operation of the wind turbine.
[0111] Methods for controlling the fluid pressure and/or of
controlling the fluid capacity, and thus the lubricating capacity
of the fluid supply system, in the fluid supply system of a wind
turbine may be accomplished on the basis of different control
scenarios:
[0112] One method comprises monitoring at least one parameter
influencing a fluid pressure in the fluid supply system of the wind
turbine, controlling a coupling arrangement between at least a
first pumping member and at least a second pumping member, thereby
obtaining a certain increased pumping capacity at a certain value
of the at least one parameter being monitored. The parameters
influencing the fluid pressure depends on the kind of coupling
arrangement employed and also depends on which driving means is
driving the drive shaft.
[0113] Another method comprises monitoring the rotational speed of
the drive shaft of at least one of a first pumping member and a
second pumping member, controlling the coupling arrangement between
the at least first pumping member and the at least second pumping
member, thereby obtaining a certain increased pumping capacity at a
certain value of the rotational speed of the drive shaft. The
rotational speed of the drive shaft is an important parameter as it
is the drive shaft, which is the primary source for establishing
the fluid pressure of the fluid supply system. Therefore,
monitoring the rotational speed of the drive shaft is a good means
of finding a basis for controlling the fluid pressure.
[0114] Even another method comprises monitoring an increment of the
rotational speed of the drive shaft of at least one of a first
pumping member and a second pumping member, controlling the
coupling arrangement between the at least first pumping member and
the at least second pumping member, thereby obtaining a certain
increased pumping capacity at a certain reduced increment of the
rotational speed of the drive shaft. As can be deducted from FIG. 1
and the description thereto, knowledge of the fluid flow in
relation to the increase or decrease of the rotational speed of the
drive shaft is a good tool for ensuring adequate lubrication at all
levels of the rotational speed of the drive shaft.
[0115] Still even another method comprises monitoring the wind
speed at the site of the wind turbine as a parameter influencing
the rotational speed of a main shaft of the wind turbine, [0116]
controlling the coupling arrangement between the at least first
pumping member and the at least second pumping member, when the
wind speed exhibits a value below 100 m/s or exhibits a value above
1 m/s, respectively, during a continuous period of time of at least
10 seconds, thereby obtaining a certain increased pumping capacity
at a certain low value or at a certain high value, respectively, of
the wind speed at the site of the wind turbine.
[0117] The rotational speed of the drive shaft may be related
directly to the rotational speed of the main shaft of the wind
turbine, and the rotational speed of the main shaft of the wind
turbine may be related directly to the wind speed prevailing at any
time at the site of the wind turbine. Thus, monitoring the wind
speed at the site of the wind turbine may be a means for
establishing an adequate fluid pressure at all levels or at
selected levels of the rotational speed of the drive shaft.
[0118] Another method comprises monitoring an the rotational speed
of a main shaft of the wind turbine influencing the rotational
speed of the drive shaft from a gearbox of the wind turbine,
controlling the coupling arrangement between the at least first
pumping member and the at least second pumping member, when the
rotational speed of the main shaft exhibits a value below 100 rpm
or exhibits a value above 0.01 rpm, respectively, during a
continuous period of time of at least 10 seconds, thereby obtaining
a certain increased pumping capacity at a certain low value or at a
certain high value, respectively, of the rotational speed of the
main shaft.
[0119] If the drive shaft is an output shaft from the gearbox, and
if the rotational speed of the drive shaft is directly related to
the rotational speed of the main shaft of the wind turbine, it is
possible to monitor the rotational speed of the main shaft in order
to establish the rotational speed of the drive shaft. Often, the
rotational speed of the main shaft is monitored due to other
reasons, and this already existing monitoring of the main shaft may
then be used also for establishing the rotational speed of the
drive shaft.
[0120] Especially during idling of the wind turbine, where the wind
turbine for some reason is out of operation, and where the drive
shaft exhibits a certain low rotational speed, and/or during an
emergency, where the transmission to the grid is cut off, and where
the drive shaft therefore may exhibit a sudden high rotational
speed, the invention will show major advantages compared to known
systems. The embodiments shown, and the methods described must not
be viewed upon as limiting the scope of the present invention. Any
modifications apparent to the person skilled in the art and falling
within the scope of the claims must be viewed upon as falling
within the scope of the present invention.
* * * * *