Patent Description:
Most aircraft have a spoiler that operates using a positive stroke of an actuator rod - i.e. for extension of the rod to lift the spoiler. The stroke of the actuator is between a 'zero' position in the housing and an extended position and the control system is biased to return the rod to the zero position.

In this way, a spoiler is typically used only in extension, and a mechanical stop inside the housing stops the piston rod actuating the spoiler at the zero position. More recently some aircraft have incorporated a 'droop' function in the spoiler, which utilises a negative stroke of the piston rod - i.e. further back into the housing than the zero position or, put another way, a stroke moving from the zero position in the opposite direction to the direction moved in the positive stroke for extending the rod.

The droop function is used to lower the spoiler relative to the wing e.g. for high lift manoeuvers. In addition, due to the relative movement between the flap and the wing, an air gap may open between the wing and the flap. The droop function may therefore also be used to actuate the spoiler in a negative close the large air gap between the wing flap and the spoiler if the wing flap is extended.

<CIT> relates to a hydraulic actuator which drives a spoiler on an aircraft wing. <CIT> also relates to a hydraulic actuator which drives a spoiler of an aircraft with a feedback device.

A system is described herein for detecting and controlling the position of a spoiler of an aircraft wing in the event of electrical failure. The system is defined as claimed in claim <NUM>.

The power supplied to the hydraulic actuator may be electrical or hydraulic.

In any of the examples described herein, when said piston rod is in said retracted position and said pressure relief valve is in said second position, upon loss of said power, said pressure relief valve may reduce or limit said load applied to said piston rod.

In any of the examples described herein, the system may further comprise an anti-extension valve that is operably connected to said hydraulic actuator and configured to prevent the piston rod from moving into the extended position upon loss of said power.

In any of the examples described herein, the hydraulic actuator may comprise a retraction chamber and an extension chamber, and wherein if the hydraulic pressure in the retraction chamber is greater than the pressure in the extension chamber, the piston rod may move into the retracted position; and if the pressure in the extension chamber is greater than the pressure in the retraction chamber, the piston rod may move into the extended position. The anti-extension valve may be movable from a first position to a second position upon loss of said power, and wherein, in said second position said piston rod may be prevented from moving to said extended position unless a threshold pressure is reached in said extension chamber.

Preferred examples will now be described by way of example only and with reference to the drawings.

There are two main failure modes of spoiler control: <NUM>) electrical failure, i.e. wherein electrical control to the spoiler is lost, and <NUM>) hydraulic failure, i.e. wherein the servovalves are no longer able to be properly operated.

In the event of a failure in spoiler control, whether electrical failure or hydraulic failure, a problem can occur in the area of overlap of the spoiler and the wing flap ranges of motion, which may damage either the spoiler and/or the wing flap. The examples described herein therefore deal with this by providing a mechanical device that ensures that, in the event of failure when the spoiler is operating in the droop function, the spoiler is able to move backwards in order to permit free flap retraction.

For example, in electrical failure, electrical power driving the spoiler is lost and the spoiler will, under its own weight or under pressure from the associated electrohydraulic servovalve (EHSV) bias, press against the wing flap when not driven by the actuator, thus interfering with movement of the wing flap. The examples described herein therefore deal with this by limiting the load applied to the spoiler so as to avoid panel damage to both the spoiler and the flap.

In addition, during electrical failure, all position measurements of the spoiler may be lost, as the position is typically provided by electrical means such as a linear variable differential transformer (LVDT). With known systems, when such a position measurement is lost, it is impossible to determine whether the spoiler is in an extension position or a droop position. The examples described herein therefore deal with this by providing a way in which the spoiler position can still be detected, even when electrical failure has occurred.

Problems can also occur in spoiler control if there is a loss of hydraulic power. Here a solution to prevent extension of the actuator, is an anti-extension valve between the EHSV and the actuator that is switched to a pressure relief position when the hydraulic pressure falls below a predetermined pressure (usually <NUM> times a given 'stall' pressure). If the spoiler is extended, and pressure is lost, the spoiler will be retracted by aerodynamic load, and will gradually drop to become aligned with the wing surface until the zero hinge position is reached. It is important to keep the spoiler at this position and prevent a spurious extension.

During hydraulic failure, when the spoiler is in the non-overlapped region, the system should have an anti-extension set higher than the stall load e.g. <NUM> times the stall load Fstall. In practice, this means that the anti-extension mechanism kicks in when the pressure acting on the side opposite the spring is less than <NUM> times Fstall (or other set anti-extension force). However, in the overlapped region, this force can be too high and cause damage to the wing flap. It is therefore desirable that the flap can drive the spoiler with a reduced anti-extension threshold to avoid damage to the wing flap - i.e. the anti-extension mechanism is triggered at a lower force.

In view of the above, the new examples described herein provide a mechanical device that is able to measure the position of the spoiler and make a distinction between the extension position and a droop position (when the spoiler might interfere with the wing flap). Such a mechanical device may be used to drive a hydraulic valve. The mechanical system may be installed in the extension chamber of an actuator configured to actuate the spoiler across the length of its stroke. With such a mechanical feedback, it is then possible to develop various architectures to change the load limitation of the spoiler depending on its position, and therefore permits the flap to push on the spoiler with limited loads in the event of a failure of spoiler control.

Referring to <FIG>, an actuator control valve arrangement <NUM> in a positive stroke operation, in a normal, active mode will first be described. The actuator control valve arrangement <NUM> comprises a three way electrohydraulic servovalve (ESHV) <NUM> that is fluidly connected to both a receiving, or low pressure (LP) fluid reservoir via fluid line <NUM> and a supply, or high pressure (HP) fluid reservoir via supply line <NUM>. The ESVH <NUM> is also connected to a mode valve <NUM>, which in turn is connected to an anti-extension valve <NUM>.

A maintenance valve <NUM> is connected to and in communication with all three of the ESHV <NUM>, the mode valve <NUM> and the anti-extension valve <NUM>, as shown in <FIG>. The anti-extension valve <NUM> is also connected to a spoiler actuator <NUM> which comprises a mechanical device <NUM> which is configured to detect droop stroke. The spoiler actuator <NUM> is connected to a pressure relief valve <NUM>.

In operation, the actuator control valve arrangement <NUM> is fluidly connected to and receives fluid from the supply reservoir (i.e. the high pressure reservoir) via fluid supply line <NUM>, and is also fluidly connected to and delivers fluid back to the receiving reservoir (i.e. containing the low pressure (LP) fluid) via line <NUM>. The high pressure reservoir has a first pressure that is greater than the pressure in the low pressure reservoir. The spoiler actuator comprises a retraction chamber <NUM>, at a side closest to the spoiler <NUM> and an extension chamber <NUM> provided at the opposite side, i.e. further away from the spoiler <NUM>. A piston rod <NUM> is provided within the actuator which is operatively connected to, in use, spoiler <NUM> and the piston rod moves within the actuator towards and away from the spoiler depending on the relative pressures of fluid in the retraction chamber <NUM> and the extension chamber <NUM>. Normal operation of the actuator control valve arrangement <NUM> to control movement of the spoiler <NUM> so as to provide an extension or a droop stroke may be seen in <FIG>.

If the spoiler is to be moved to an extension position, piston rod <NUM> is to be extended out of the actuator <NUM>, HP fluid is moved into the extension chamber <NUM> of the actuator <NUM> from the supply reservoir, which causes the piston rod to extend from the actuator <NUM>. Fluid present in the retraction chamber <NUM> is thus forced from the actuator <NUM>, as the piston head moves through the actuator <NUM>, on the other side of the piston head, to the LP fluid source. Similarly, if the spoiler is to be retracted towards a droop position, piston rod <NUM> is to be retracted from the extended position, the HP fluid is provided from the supply chamber to retraction chamber <NUM>, thereby causing the piston rod <NUM> to retract and eject fluid from extension chamber <NUM> to the receiving, or LP reservoir.

As shown in <FIG>, the direction of fluid is controlled by the EHSV valve <NUM> which takes up different valve positions 10X, 10Y and 10Z in response to the electric control signal (not shown). The EHSV <NUM> may reverse the flow of fluid between the retraction and the extension chambers <NUM>, <NUM> by switching between valve positions 10X and 10Z, or the EHSV <NUM> may provide no flow of fluid therethrough when in position 10Y. That is, the EHSV is configured to direct fluid into and out of the retraction and extension chambers accordingly, based on whether the spoiler is to be retracted or extended.

In normal operation, when ESHV <NUM> is in valve position 10X to provide an extension of the spoiler, fluid is provided through fluid line <NUM>, through position 10X of the ESHV <NUM>, through line <NUM>, through Mode valve <NUM> to fluid line <NUM> and <NUM> to extension chamber <NUM>. Due to the increased pressure in the extension chamber <NUM>, fluid is then forced out of the retraction chamber <NUM> through line <NUM>, through the pressure relief valve <NUM> along line <NUM>, through position 30Y of anti-extension valve <NUM>, through line <NUM>, through mode valve <NUM>, through line <NUM> to line <NUM>, and to the LP fluid source through return line <NUM>.

When ESHV <NUM> is in valve position 10Z to provide a retraction of the spoiler, the flows are reversed through the ESHV <NUM>, such that the HP fluid is provided to the retraction chamber <NUM>. Due to the relative increase of pressure in the retraction chamber <NUM> compared to the extension chamber <NUM>, the spoiler <NUM> is retracted.

Mode valve <NUM> provides first and second positions 20X and 20Y depending on which mode the actuator control valve arrangement is to operate in. When high pressure (from the HP fluid source/reservoir) is detected at port <NUM> of the mode valve <NUM> through sense lines <NUM> and <NUM> connected to the fluid supply line <NUM>, mode valve <NUM> is provided in position 20Y, wherein the flow from the EHSV <NUM> is passed through to the remainder of the actuator control valve arrangement. When no high pressure is detected at port <NUM>, the valve is moved to position 20X and all flow from the EHSV <NUM> is blocked. Rather, when the mode valve <NUM> is provided in position 20X, the low pressure fluid source is connected via lines <NUM>, <NUM> and <NUM> to the remainder of the actuator control valve arrangement <NUM>, via line <NUM> to the anti-extension valve <NUM> and line <NUM> to the extension chamber <NUM> and pressure relief valve <NUM>.

Anti-extension valve <NUM> is configured to prevent the spoiler <NUM> from extending during electrical or hydraulic failure. In doing so, it has two positions, 30X preventing reverse flow from the retraction chamber <NUM> of the actuator <NUM>, and position 30Y allowing for unimpeded flow in both directions. In selecting the position of anti-extension valve <NUM>, anti-extension valve <NUM> is provided with two ports <NUM>, <NUM>. Port <NUM> senses pressure from the HP fluid source (and thereby HP fluid supply line <NUM>) via sense line <NUM>, and port <NUM> senses pressure from the retraction chamber <NUM> via sense line <NUM>. If pressure is lost from the HP fluid source, then anti-extension valve <NUM> is moved from position 30Y to 30X. In position 30X, the anti-extension valve is provided with a pressure valve that prevents return flow from lines <NUM> and <NUM> from the retraction chamber <NUM>. In such a case, if an external tensile load is applied to the spoiler, the pressure in the retract chamber will increase. Due to the position 30X of the anti-extension valve, the spoiler will not be able to extend until the pressure increases to a pre-determined pressure, for example <NUM> times the stall force, preventing an erroneous extension of the spoiler.

As can be seen, pressure relief valve <NUM> has two positions, 60X and 60Y. Position 60Y allows for normal operation of the valve control arrangement, and position 60X provides pressure relief in the event of failure when the spoiler <NUM> is in the droop position. Pressure relief valve is operatively connected to mechanical device <NUM> to detect droop stroke. Mechanical device <NUM> is, in turn, operatively connected to actuator <NUM> in order to detect the position of the actuator <NUM>, and thereby the position of the spoiler <NUM> and whether it is in a neutral, extended or droop position.

When the mechanical device <NUM> measures that the spoiler <NUM> is in a droop position, pressure relief valve <NUM> is moved from position 60Y to position 60X. Due to the position 60X, if pressure or electrical failure occurs while the spoiler is in the droop position, the pressure relief valve will limit the load that is required to be applied by the flap in order to manually move the spoiler into a non-overlapped position, such that the flap can retract.

Such an effect is achieved in position 60X by a pressure valve that prevents return flow from retraction chamber <NUM>, through line <NUM> to the remainder of the control arrangement through line <NUM>. Instead, when an increased force is provided in the retraction chamber <NUM>, the flow through is partially provided through the pressure relief valve at a reduced pressure through line <NUM>, which is fluidly connected to extension chamber <NUM> via line <NUM>. As a result, when the spoiler is in a retracted position, the pressure in the retraction chamber <NUM> is reduced, thereby reducing the force that needs to be applied to the spoiler in order to achieve extension.

As would be appreciated, any kind of mechanical device <NUM> capable of detecting whether the spoiler is in a droop condition is envisaged. For example, a piston with a roller at its end may be used. One specific example is illustrated in the figures, and described herein by way of a non-limiting example. Spoiler actuator <NUM> comprises a biasing member <NUM> operatively connected to piston rod <NUM> via a tracking portion comprising a linearly spaced first portion <NUM>, second portion <NUM>, and sloped portion <NUM> positioned there between. In this regard, the tracking portion comprises a variable diameter over its length. Mechanical device <NUM> is configured to contact the tracking portion.

When the spoiler <NUM> is in the extended portion, the mechanical device <NUM> is in contact with first portion <NUM> of the tracking portion. As the spoiler <NUM> retracts, the tracking portion will move linearly with respect to the mechanical device <NUM> such that when the spoiler <NUM> is in the retracted position, the mechanical device <NUM> will be in contact with the second portion <NUM> of the actuator <NUM>. The variance in radius between the first portion <NUM> and the second portion <NUM> will therefore result in a changed position of the mechanical device <NUM>, which in turn will provide the pressure relief valve <NUM> in position 60X. As outlined above, other mechanical methods for measuring the position of the spoiler are contemplated.

<FIG> displays the operation of the actuator control valve arrangement <NUM> when the spoiler <NUM> is in the extended position, in the case of an electrical failure. In case of electrical failure, EHSV <NUM> is biased to provide HP fluid to the retraction chamber <NUM>. As a result, the spoiler <NUM> will retract until the spoiler is brought into contact with the flap with reduced pressure.

<FIG> displays the operation of the actuator control valve arrangement <NUM> when the spoiler <NUM> is in the droop position, in the case of an electrical failure. Again, due to the electrical failure, EHSV <NUM> is biased to provide HP fluid to the retraction chamber <NUM>. However, as can be seen, when the spoiler <NUM> is in the droop position, as detected by the mechanical device <NUM> (for example, where the mechanical device is in contact with the second portion <NUM> of the tracking portion of the actuator <NUM>). As a result, pressure relief valve <NUM> has been moved to position 60X, thereby providing reduced pressure to retraction chamber <NUM>, as described above. Whilst this still provides retraction of the spoiler <NUM>, it reduces the amount of retraction force on the spoiler, thereby preventing unnecessary damage to the flap.

In this way, the flap may be brought into physical contact with the spoiler in order to move the spoiler into a non-overlapped position.

<FIG> displays the operation of the actuator control valve arrangement <NUM> when the spoiler <NUM> is in the extended position, in the case of a hydraulic failure. When hydraulic failure occurs, no HP fluid is provided to the actuator control valve arrangement <NUM>. As the spoiler <NUM>, and therefore the piston rod <NUM> are in the extension position, the mechanical device is positioned such that the pressure relief valve lies in position 60Y, thereby providing a fluid connection between the pressure relief valve <NUM> and the anti-extension valve <NUM>. In case of such a pressure loss, anti-extension valve <NUM> is configured to move to position 30X, and the only high pressure fluid source is the retraction chamber <NUM>, due to external loads on the spoiler. The retraction chamber is therefore fluidly isolated from the rest of the actuator control valve arrangement <NUM> by the anti-extension valve <NUM>, and thereby the increased pressure in the retraction chamber <NUM> of the spoiler actuator <NUM> retracts the spoiler <NUM>. Due to the position of 30X the anti-extension valve, extension of the spoiler <NUM> is prevented, in the presence of an extension force.

<FIG> shows the operation of the actuator control valve arrangement <NUM> when the spoiler <NUM> is in the droop position in the event of hydraulic failure, and therefore the spoiler may overlap with the flap. In this case, again, no HP fluid is provided to the actuator control valve arrangement <NUM>, and the only high pressure source is the retraction chamber <NUM>. However, as the spoiler <NUM> is in the droop position, pressure relief valve <NUM> is provided in position 60X, which relieves pressure from the retraction chamber to the rest of the valve arrangement, including extension chamber <NUM> until the spoiler reaches a neutral position. As a result, less force from the flap is required to move the spoiler <NUM>, reducing the likelihood of damage to either the spoiler <NUM> or the flap.

Claim 1:
A system for detecting and controlling the position of a spoiler (<NUM>) of an aircraft wing in the event of electrical failure, comprising:
a spoiler (<NUM>);
a hydraulic actuator (<NUM>) having a piston rod (<NUM>) operably connected to the spoiler (<NUM>), the piston rod (<NUM>) being moveable between a retracted position, a neutral position and an extended position; and
means for providing power to said hydraulic actuator (<NUM>); and
a mechanical device (<NUM>) operatively connected to the hydraulic actuator (<NUM>) to detect whether the piston rod (<NUM>) is in the retracted position, the neutral position or the extended position; and
a pressure relief valve (<NUM>), operatively connected to the mechanical device (<NUM>), that is configured to provide a change in a load applied to said hydraulic actuator (<NUM>),
wherein said pressure relief valve (<NUM>) is movable between a first position (60Y) to a second position (60X), thereby changing said load based on whether said piston rod (<NUM>) is detected by the mechanical device as being in said retracted position or said extended position,
characterised in that
the actuator (<NUM>) comprises a biasing member (<NUM>) operatively connected to the piston rod (<NUM>) via a tracking portion, the tracking portion comprising a linearly spaced first portion (<NUM>) and second portion (<NUM>), the first and second portions having a sloped portion (<NUM>) positioned there between, such that the tracking portion comprises a variable diameter over its length,
wherein, when the piston rod (<NUM>) is in the extended portion, the mechanical device (<NUM>) is in contact with the first portion (<NUM>) of the tracking portion, and as the piston rod (<NUM>) retracts, the tracking portion is configured to move linearly with respect to the mechanical device (<NUM>) such that, when the piston rod (<NUM>) is in the retracted position, the mechanical device (<NUM>) is
in contact with the second portion (<NUM>) of the hydraulic actuator (<NUM>), and
wherein the difference in diameter of the first and second portions results in a changed position of mechanical device (<NUM>), thereby moving the pressure relief valve from the first position (60Y) to the second position (60X).