U.S. patent application number 12/643326 was filed with the patent office on 2010-08-26 for automatic shut-off valve for the oil circuit in an airplane engine.
This patent application is currently assigned to TECHSPACE AERO S.A.. Invention is credited to Albert Cornet, Oliver Descubes, Sebastien Detry, Marc Monfort.
Application Number | 20100213010 12/643326 |
Document ID | / |
Family ID | 40873230 |
Filed Date | 2010-08-26 |
United States Patent
Application |
20100213010 |
Kind Code |
A1 |
Cornet; Albert ; et
al. |
August 26, 2010 |
Automatic Shut-Off Valve For The Oil Circuit In An Airplane
Engine
Abstract
The present invention concerns a lubrication system in a closed
circuit provided with a valve comprising a first position and a
second position, as well as an IN inlet, a first BP outlet and a
second M outlet, said IN inlet being connected to the outlet of the
feed pump, the first BP outlet being connected to the bypass
circuit and the second M outlet being connected to the feed
circuit. In the first position of the valve, the flow entering via
the IN inlet is diverted to the first BP outlet and in the second
position, the incoming flow is diverted to the second M outlet,
said valve switching from the first position to the second position
and vice versa, when the incoming flow rate exceeds a predetermined
threshold upwards and downwards respectively.
Inventors: |
Cornet; Albert; (Verviers,
BE) ; Monfort; Marc; (Jalhay, BE) ; Descubes;
Oliver; (Pau, FR) ; Detry; Sebastien; (Pau,
FR) |
Correspondence
Address: |
REINHART BOERNER VAN DEUREN P.C.
2215 PERRYGREEN WAY
ROCKFORD
IL
61107
US
|
Assignee: |
TECHSPACE AERO S.A.
Milmort
BE
|
Family ID: |
40873230 |
Appl. No.: |
12/643326 |
Filed: |
December 21, 2009 |
Current U.S.
Class: |
184/6.11 |
Current CPC
Class: |
F02C 7/06 20130101; F16K
17/0473 20130101; Y02T 50/671 20130101; Y02T 50/60 20130101; F05D
2260/602 20130101; F01D 25/20 20130101 |
Class at
Publication: |
184/6.11 |
International
Class: |
F01D 25/20 20060101
F01D025/20 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 2008 |
EP |
08172853.7 |
Claims
1. A lubrication system in a closed circuit comprising: a feed pump
(17); an oil tank (16); a feed circuit (19) supplying the oil to
housings (20) containing parts to be lubricated; a collection
circuit (21) returning the oil from the housings (20) to the tank
(16); a bypass circuit (18) returning the oil from the outlet of
the feed pump (17) to the tank (16) or to the inlet of the feed
pump (17); a valve (22) comprising a first position and a second
position as well as an IN inlet (1), a first BP outlet (3) and a
second M outlet (2), said IN inlet (1) being connected to the
outlet from the feed pump (17), the first BP outlet (3) being
connected to the bypass circuit (18) and the second M outlet (2)
being connected to the feed circuit (19); characterized in that, in
the first position, the flow entering via the IN inlet (1) is
diverted to the first BP outlet (3) and, in the second position,
the incoming flow is diverted to the second M outlet (2), said
valve switching from the first position to the second position and
vice versa, when the incoming flow exceeds a predetermined
threshold upwards and downwards respectively.
2. Lubrication system as in claim 1, characterized in that said
valve (22) comprises a valve (4) which slides slightly loose in a
bore (7) machined into a valve body (6) between two opposite seats
(10, 11), a first seat (10) being connected to the IN inlet (1) and
a second seat (11) being connected to the BP outlet (3), the M
outlet (2) emerging in the bore (7) in a ring-shaped cavity (8)
surrounding the first seat (10), so that: a. for a flow rate in the
IN inlet (1) lower than the predetermined threshold, the valve (4)
is pushed by a spring (5) on the first seat (10) controlling the IN
inlet (1) and the connection from the IN inlet (1) to the
ring-shaped cavity (8) is blocked, the connection being opened
towards the BP outlet (3) via at least one calibrated opening (9)
passing through the valve (4) and emerging laterally in the bore
(7) upstream from the seat (11) of the BP outlet (3); b. for a flow
rate from the IN inlet (1) greater than or equal to the
predetermined threshold, the valve (4) moves to the second seat
(11) in a position where it rests against the second seat (11),
closing the BP outlet (3) and where the IN inlet (1) is connected
to the M outlet (2) via the ring-shaped cavity (8), the first seat
(10) being released by the movement of the valve (4).
3. Lubrication system as in claim 2, characterized in that the
valve (4) is made of at least two parts which push against each
other.
4. Lubrication system as in claim 2, characterized in that the seal
of any outlet or of the two outlets of the valve (22) is provided
by means of a cover principle of the "sliding type" (13) replacing
the seat-valve contact.
5. Lubrication system as in claim 1, characterized in that said
valve (22) comprises a valve (4) which slides in a bore (7) between
two opposite seats (23, 24), a first seat (23) being connected to
the M outlet (2) and a second seat (24) being connected to the BP
outlet (3), the IN inlet (1) emerging in the bore (7) in a
ring-shaped cavity surrounding the first seat (23) and the bore (7)
or the valve (4) comprising at least one calibrated channel (15)
between the two seats (23, 24), the parts of said valve (22) being
proportioned in such a way that: c. for a flow rate from the IN
inlet (1) lower than the predetermined threshold, a spring (5)
holds said valve (4) rested against the first seat (23), closing
the M outlet (2), the flow being diverted towards the BP outlet
(3); d. for a flow rate from the IN inlet (1) greater than or equal
to the predetermined threshold, said valve (4) moves to the second
seat (24), opening the M outlet (2) and closing the BP outlet
(3).
6. Lubrication system as in claim 5, characterized in that the
valve (4) is spherical.
7. Aircraft engine comprising a lubrication system as in claim
1.
8. Aircraft engine as in claim 7, characterized in that it is a
turbojet, a turboprop, a turboshaft or a helicopter engine.
9. Aircraft engine as in claim 7, characterized in that said
lubrication system and said valve (22) are located in one casing.
Description
SUBJECT OF THE INVENTION
[0001] The present invention concerns an automatic shut-off and
isolation valve for the oil circuit in an aircraft engine, in
particular in a turbojet or a turboprop.
STATE OF THE ART
[0002] With certain turbojets, when the aircraft is stopping, it is
interesting to stop or reduce the oil supply to the bearing
housings before the aircraft has completely stopped, so as to
permit a complete drainage of these housings, whilst the rotation
is ceasing. In fact, in these aircraft, the oil is supplied to the
housings by a pump, the feed pump, and collected at the bottom of
these housings by another pump, the collection pump. Both pumps
being of a volumetric type and driven by the main shaft of the
engine or HP shaft, they continue to work until this shaft comes to
a complete stop.
[0003] In certain cases, an imbalance may occur between the oil
supplied by the feed pump and the collection pump or pumps, which
may cause an excess of oil to appear in the housing and cause
leaks
[0004] This imbalance may also lead to the stagnation of oil in the
housings during stopping phases of the engine and may cause the
coking of the stagnant oil, especially in engines with one or
several housings which are particularly hot or particularly
sensitive to the phenomenon known as "soak back", of the temporary
heating of the mechanical parts when the engine is stopped.
[0005] Document U.S. Pat. No. 4,170,873 describes a system
comprising 2 valves, one for safety and the other for control,
allowing to control the oil flow fed to the bearing housings during
running phases at low speed. These valves are controlled by the
pressure in the various circuits.
[0006] Document U.S. Pat. No. 4,245,465 describes a 3-function
valve allowing for one thing to reduce the oil flow fed to the
bearing housings during running phases at low speed, to cut the
supply of oil to the housings at very low speed and to control the
oil flow at high running speed. This valve continuously lets oil
flow to the oil tank; it therefore never lets the full flow be fed
to the engine.
[0007] The so-called "anti-siphon" devices provided for blocking
any leak from the tank through the pump to the bottom areas of the
engine during periods of inactivity occurring during the last turns
of the engine may play a part in reducing the quantity of stagnant
oil. They act by shutting off either the connection from the oil
tank to the feed pump or the outlet of the pump under a certain
pressure.
[0008] Whatever the "anti-siphon" methods used, they have the
common characteristic of acting very late during the stopping
phase, even after the engine has completely stopped and if this is
not the case, of sometimes significantly slowing down the ignition
on restart. The resumption of the oil supply during restart thus
occurs systematically at a significantly higher speed than that at
which the flow was cut off during stopping. Moreover the control of
such devices to get a cut-off at a significant speed during
stopping, so as to ensure a good drainage, might lead to make the
re-ignition of the pump impossible on restart. Certain
"anti-siphon" devices do not show this disadvantage, but then they
are based on a more or less complex control system, which often
consumes oil, and which is useless in many engines.
[0009] None of these systems allows to efficiently prevent the
stagnation of oil in the housings during the stopping phases of the
engine. In particular, none of these systems describes a device
that would prevent the phenomenon of coking of the stagnant
oil.
AIMS OF THE INVENTION
[0010] The present invention aims to provide a solution to the
disadvantages of the state of the art.
[0011] In particular, the invention aims to provide a simpler and
lighter means than the devices known in the state of the art
("anti-siphon" devices, U.S. Pat. No. 4,245,465, U.S. Pat. No.
4,170,873, etc.), which can act at any moment during the stopping
phase of the engine and which allows on restart to resume the
supply at a speed equal or very close to that at which the flow was
cut off during stopping.
[0012] Moreover, the present invention aims to achieve this
objective with a simple and compact valve without complicated
control and scarcely sensitive to friction and pollution.
MAIN CHARACTERISTIC FEATURES OF THE INVENTION
[0013] A first aspect of the present invention concerns a
lubrication system in a closed circuit comprising: [0014] a feed
pump; [0015] an oil tank; [0016] a feed circuit supplying the oil
to housings (20) containing parts to be lubricated; [0017] a
collection circuit returning the oil from the housings to the tank;
[0018] a bypass circuit returning the oil from the outlet of the
feed pump to the tank or to the inlet of the feed pump; [0019] a
valve comprising a first position and a second position as well as
an IN inlet, a first BP outlet and a second M outlet, said IN inlet
being connected to the outlet from the feed pump, the first BP
outlet being connected to the bypass circuit and the second M
outlet being connected to the feed circuit; characterized in that,
in the first position, the flow entering via the IN inlet is
diverted to the first BP outlet and, in the second position, the
incoming flow is diverted to the second M outlet, said valve
switching from the first position to the second position and vice
versa, when the incoming flow exceeds a predetermined threshold
upwards and downwards respectively.
[0020] According to preferred embodiments of the invention, the
lubrication system comprises at least one or any suitable
combination of the following characteristics: [0021] said valve
comprises a valve which slides slightly loose in a bore machined
into a valve body between two opposite seats, a first seat being
connected to the IN inlet and a second seat being connected to the
BP outlet, the M outlet emerging in the bore in a ring-shaped
cavity surrounding the first seat, so that: [0022] for a flow rate
in the IN inlet lower than the predetermined threshold, the valve
is pushed by a spring (5) on the first seat controlling the IN
inlet (1) and the connection from the IN inlet (1) to the
ring-shaped cavity (8) is blocked, the connection being opened
towards the BP outlet via at least one calibrated opening passing
through the valve and emerging laterally in the bore upstream from
the seat of the BP outlet; [0023] for a flow rate from the IN inlet
greater than or equal to the predetermined threshold, the valve
moves to the second seat in a position where it rests against the
second seat, closing the BP outlet and where the IN inlet is
connected to the M outlet via the ring-shaped cavity, the first
seat being released by the movement of the valve [0024] the valve
is made of at least two parts which push against each other. [0025]
the seal of any outlet or of the two outlets of the valve is
provided by means of a cover principle of the "sliding type"
replacing the seat-valve contact. [0026] said valve comprises a
valve which slides in a bore between two opposite seats, a first
seat being connected to the M outlet and a second seat being
connected to the BP outlet the IN inlet (1) emerging in the bore in
a ring-shaped cavity surrounding the first seat and the bore or the
valve comprising at least one calibrated channel between the two
seats the parts of said valve being proportioned in such a way
that: [0027] for a flow rate from the IN inlet (1) lower than the
predetermined threshold, a spring (5) holds said valve (4) rested
against the first seat (23), closing the M outlet (2), the flow
being diverted towards the BP outlet (3); [0028] for a flow rate
from the IN inlet (1) greater than or equal to the predetermined
threshold, said valve (4) moves to the second seat (24), opening
the M outlet (2) and closing the BP outlet [0029] the valve (4) is
spherical.
[0030] A second aspect of the invention concerns an aircraft engine
comprising a lubrication system such as described above. This
engine is for example a turbojet, a turboprop, a turboshaft or a
helicopter engine.
[0031] As an advantage, in such an engine, the lubrication system
and said valve are located in one casing.
BRIEF DESCRIPTION OF THE DIAGRAMS
[0032] Diagrams 1A and 1B show a valve according to a first
particular embodiment of the invention.
[0033] Diagrams 2A and 2B show a valve according to a second
particular embodiment of the invention.
[0034] Diagrams 3A and 3B show a valve according to a third
particular embodiment of the invention.
[0035] Diagrams 4A and 4B show a valve according to a fourth
particular embodiment of the invention.
[0036] Diagrams 5A and 5B show a valve according to a fifth
particular embodiment of the invention.
[0037] Diagram 6 shows schematically a lubrication system according
to the present invention.
[0038] Diagram 7 shows a scheme of the principle of an aircraft
engine equipped with an automatic shut-off valve for the oil
circuit according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0039] According to the present invention, the flow from the feed
pump to the engine is cut off before the engine has completely
stopped, whilst letting the collection pumps operate normally. From
this moment onwards, the collection pumps will drain the housings
efficiently, since they continue to suck in the oil flowing from
the wet components and walls, without any new oil being fed in.
[0040] In the event of such an interruption in the flow supply
during stopping, it is nevertheless necessary to ensure that the
engine is resupplied early enough on restart.
[0041] This cutting off of the oil flow supply when the engine is
stopped thus permits to combat the coking in aircraft engines.
[0042] In the present invention, this function of stopping the flow
supply to the housings is achieved by means of a shut-off and
"bypass" valve. This valve comprises three ways and two positions.
It is placed at the outlet of the feed pump (IN way) and diverts
the flow from the pump to the tank or the inlet of the pump (BP
way, stands for "bypass") when this flow is weak, whilst closing
the connection to the engine (M way). When the flow from the pump
reaches a predetermined threshold, it diverts this flow to the
engine (M way) and closes the connection to the tank or the inlet
of the pump (BP way) again.
[0043] Particular embodiments of the valve according to the
invention are shown in Diagrams 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A
and 5B.
[0044] In a first particular embodiment of the invention shown in
Diagrams 1A and 1B, the valve is composed of a valve 4, which
slides slightly loose in a bore 7, between two opposite seats 10,
11. One is connected to the IN way, the other to the BP way. The M
way emerges in a ring-shaped cavity 8 surrounding the IN seat.
[0045] At rest or whilst the flow via the IN way is lower than a
predetermined threshold, the valve 4 is pushed by a spring 5
towards the seat 10 controlling the IN way and the connection from
the IN inlet to the ring-shaped outlet 8 emerging in the M way is
blocked (Diagram 1A). However, the connection is possible to the
BP, via the calibrated opening 9 emerging in the cavity 12 defined
by the bore 7 upstream from the seat 11 of the BP way.
[0046] The pressure of the IN way thus applies to the surface of
the valve resting on the seat 10. Since the BP way is connected to
the tank 16 or the inlet of the pump, it is considered to be at
zero pressure and the pressure of the IN way is controlled by the
flow of the IN way, controlled by the volumetric feed pump 17
(Diagrams 6 and 7) and passing through the connection channel 9,
whose hydraulic resistance is calibrated. When the force exerted by
this pressure on the valve 4 is less than the load of the spring 5,
the valve presses against the seat 10 of the IN way and closes the
M way (Diagram 1A).
[0047] When, as a result of an increase in the flow from the pump,
this pressure becomes greater than the load of the spring 5 in this
position, the valve moves to the other seat, creating additional
hydraulic resistance to the flow and increasing the pressure
differential applied to the valve 4. This functioning is verified
provided that the M way offers significant hydraulic resistance
(which is generally the case with aircraft engines) and that the
way from the connecting channel 9 between the two seats 10, 11 is
properly suited to it.
[0048] At higher flow rates, the valve 4 comes to rest against the
seat 11 emerging in the BP way, which is thus completely closed,
and the pressure of the engine circuit applies to the entire
surface of the valve 4 on the side of the M way, which is locked in
this position by the pressure (Diagram 1B). When the flow rate
drops, the resulting decreasing in pressure allows the spring to
push the valve back to its original position (Diagram 1A).
[0049] The fluctuation levels in one direction and the other, the
functional hysteresis and the stability are controlled by the
ratios of the surface areas of the seats, the preload, the
direction and stiffness of the spring 5 and the ratio of the
hydraulic resistance of the connecting channel 9 relative to that
of the M way.
[0050] In other particular embodiments of the invention: [0051] the
valve may be of any shape, provided that the hydraulic principles
mentioned above are observed; [0052] the valve might be made in two
or more parts that are more or less fixed and which push against
each other; [0053] the connecting channel may be made in various
ways (see an alternative in Diagrams 2A and 2B).
[0054] The seal of any outlet or of the two outlets of the valve
according to the invention could also be realized by means of the
cover principle of the "sliding type" 13, instead of a
seat-valve-valve piece contact. This principle is illustrated in
Diagrams 3A and 3B.
[0055] In another alternative embodiment shown in Diagrams 4A, 4B,
5A and 5B, the valve is composed of a valve 4, which slides in a
bore 7 between two seats 23, 24. Depending on its position and the
seat which it is resting on, it opens or closes the connection to
the BP or M ways. At rest (Diagrams 4A and 5A), the valve 4 is
pushed by a spring 5 to the seat 23 controlling the M way, which it
closes. The valve 4 or the bore 7 is also fitted with one or more
calibrated connections 15 allowing the connection between the
ring-shaped zones located around the seats 23, 24 on both sides of
the valve 4. The IN way emerges via the bore 7, in the ring-shaped
space surrounding the seat 23 of the M way. The pressure of the IN
way thus applies to the ring-shaped surface of the valve around the
seat 23. Since this zone is connected to the BP way, which is open
by means of the calibrated channel 15, the flow moves from the IN
way to the BP way, the M way being closed by the spring 5. Since
the BP way is connected to the tank 16 or the inlet of the pump 17
(Diagrams 6 and 7), it is considered to be at zero pressure and the
pressure of the ring-shaped zone of the valve 4 around the seat 23
of the M way is controlled by the flow passing through the
connecting channel 15. When the force exerted by this pressure on
the valve 4 is lower than the load of the spring 5, the valve 4
remains rested against the seat 23 of the M way and keeps it closed
(Diagram 4A). When, as a result of an increase in the flow from the
pump 17, this pressure becomes greater than the load of the spring
5 in this position, the valve moves to the other seat 24, creating
additional hydraulic resistance to the flow and increasing the
pressure differential applied to the valve 4. At the same time, the
flow begins to move towards the M way and the IN pressure spreads
progressively to a greater surface area of the valve, increasing
the imbalance. This functioning is verified, provided that the M
way offers significant hydraulic resistance (which is generally the
case with engines) and that the way of the connecting channel 15
between the two seats 23, 24 is properly suited to it. At higher
flow rates, the valve 4 is rested against the seat 24 of the BP
way, which is completely closed, and the pressure of the engine
circuit applies to the entire surface of the valve on the M side,
which is locked in this position by the pressure (Diagram 4B). When
the pressure drops, the decreasing in pressure allows the spring 5
to push the valve 4 back to its original position (Diagram 4A). The
fluctuation levels in one direction and the other, the functional
hysteresis and the stability are controlled by the ratios of the
surface of the seats, the preload, the direction and stiffness of
the spring 5 and the ratio of the hydraulic resistance of the
connecting channel 15 relative to that of the M way.
[0056] In one embodiment of the invention, the valve 4 is of a
spherical shape as shown in Diagrams 4A and 4B.
[0057] In particular embodiments of the present invention, the
calibrated connection between the two sides may advantageously be
realised in the valve itself as shown in Diagrams 5A and 5B, by
grooves in the bore or even via an external channel.
* * * * *