Patent Description:
Due to several design constraints, a ram air turbine (RAT) in the stowed position can have a low resonance which would be excited by in flight vibratory loadings (e.g., windmilling loadings), resulting in very high loads experienced by the RAT and the RAT actuator. Low resonances can exist because as the angle of the actuator to the strut decreases, the fundamental mode of the RAT decreases resulting in very high loads. If this is in the windmilling test frequency range, it can result in a significant number of cycles at very high load.

Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved RAT actuators. The present disclosure provides a solution for this need. <CIT> describes an unlocking mechanism for a two-part strut. <CIT> describes an electromechanical actuator damping arrangement for a RAM air turbine.

A ram air turbine (RAT) actuator piston is defined in claim <NUM> and includes a body defining a piston structure having an inner cavity. The piston includes one or more damping holes axially defined through the body to the inner cavity and a lock rod hole defined axially through the body to the inner cavity. The lock rod hole has a larger flow area than one or more of the one or more damping holes. The lock rod hole is configured to receive a lock rod of a RAT actuator to at least partially block flow through the lock rod hole when the lock rod is in a locked position. The one or more damping holes are configured to allow flow through the damping holes in the locked position to allow the RAT actuator piston to move within the RAT actuator in the locked position to dissipate vibratory loads.

The piston can include one or more lock pawl windows radially defined through the body from a radially outer surface of the body to the inner cavity, the one or more lock pawl windows configured to receive one or more lock pawls of a RAT actuator. The lock rod hole can be configured to receive a lock rod of a RAT actuator to additionally support the lock pawls when the lock rod is in a locked position.

The one or more damping holes can be defined between an axially outer face of the body and the inner cavity. The lock rod hole can be defined between the axially outer face of the body and the inner cavity. The one or more damping holes can include a plurality of damping holes. The piston can include a piston rod extending from the body forming part of or configured to connect to a rod end.

A ram air turbine (RAT) actuator is also defined in claim <NUM> and includes an uplock mechanism defining a chamber and configured to be retained in an uplock axial position (e.g., by one or more lock pawls), and a RAT actuator piston disposed within the uplock mechanism chamber configured to dissipate vibrational energy applied to the piston in a locked position. In certain embodiments, the RAT actuator piston can be any suitable piston as disclosed herein (e.g., as described above). Any other suitable embodiment of a piston configured to dissipate vibrational energy is contemplated herein.

The RAT actuator include one or more lock pawls disposed in the lock pawl windows. The RAT actuator can include the lock rod disposed therein and configured to move axially through the lock rod hole and to support the one or more lock pawls in the locked position to maintain the stowed position of the RAT, and to allow radially inward movement of the one or more lock pawls in an unlocked position such that the lock pawls disengage the uplock mechanism to allow extension of the RAT actuator.

The RAT actuator can include a valve housing operatively connected to the lock rod to move the lock rod axially. The RAT actuator can include at least one actuator spring configured to extend the RAT actuator in the unlocked position. The RAT actuator can include any suitable components as appreciated by those having ordinary skill in the art in view of this disclosure.

In accordance with at least one aspect of this disclosure, a ram air turbine (RAT) can include any suitable embodiment of a RAT actuator disclosed herein (e.g., as described above). Any other suitable embodiment of a RAT actuator is contemplated herein. Certain embodiments of the RAT include any other suitable components for a RAT as appreciated by those having ordinary skill in the art in view of this disclosure.

Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, an illustrative view of an embodiment of a ram air turbine (RAT) actuator piston in accordance with the disclosure is shown in <FIG> and is designated generally by reference character <NUM>. Other embodiments and/or aspects of this disclosure are shown in <FIG>. Certain embodiments described herein can be used to dissipate vibratory loads in a RAT system in the stowed position, for example.

Referring to <FIG>, a ram air turbine (RAT) actuator piston <NUM> can include a body <NUM> defining a piston structure (e.g., a cylindrical shape as shown, or any other suitable shape). The body <NUM> can have an inner cavity <NUM>.

The piston <NUM> can include one or more damping holes <NUM> axially defined through the body <NUM> to the inner cavity <NUM> and a lock rod hole <NUM> defined axially through the body <NUM> to the inner cavity <NUM>. The lock rod hole <NUM> can have a larger flow area than one or more of the one or more damping holes <NUM>, for example. Referring additionally to <FIG>, the lock rod hole <NUM> can be configured to receive a lock rod <NUM> of a RAT actuator <NUM> to at least partially block flow through the lock rod hole <NUM>.

In certain embodiments, the piston <NUM> can include one or more lock pawl windows <NUM> configured to receive one or more lock pawls (e.g., one or more rollers, not shown) of a RAT actuator <NUM>. The one or more lock pawl windows <NUM> can be radially defined through the body <NUM> from a radially outer surface <NUM> of the body <NUM> to the inner cavity <NUM>. In certain embodiments, the lock rod hole <NUM> can be configured to receive the lock rod <NUM> to support the lock pawls when the lock rod <NUM> is in a locked position (e.g., as shown in <FIG>) in addition to at least partially blocking flow through the lock rod hole <NUM>.

To support the lock pawls, the lock rod <NUM> can extend into the cavity <NUM> in the locked position and contact the lock pawls to push the lock pawls radially outward to contact a surrounding uplock mechanism <NUM> to block the uplock mechanism <NUM> from moving relative to the piston <NUM>. One having ordinary skill in the art in view of this disclosure understands that any suitable construction for the uplock mechanism <NUM> and lock pawls are contemplated herein. Embodiments may include lock pawls and/or the uplock mechanism dimensioned to allow some motion of the piston <NUM> back and forth to allow the piston to displace or travel axially a small distance relative to the uplock mechanism such that damping flow can flow through the damping holes <NUM> back and forth. For example, the lock pawls and/or the uplock mechanism <NUM> may be dimensioned to include from about <NUM> thousands of an inch to about <NUM> thousands of an inch in axial play (e.g., which is about <NUM> times to about <NUM> times as much play in existing systems).

The one or more damping holes <NUM> can be configured to allow flow through (back and forth when vibrating) the damping holes <NUM> in the locked position to allow the RAT actuator piston <NUM> to move within the RAT actuator <NUM> in the locked position to dissipate vibratory loads. The one or more damping holes <NUM> can include any suitable size and shape (e.g., about <NUM>/10th the diameter of the lock rod hole <NUM> or any other suitable size).

As shown, the one or more damping holes <NUM> can be defined between an axially outer face <NUM> of the body <NUM> and the inner cavity <NUM>. The one or more damping holes <NUM> can be radially positioned between the outer radial surface <NUM> of body <NUM> and the lock rod hole <NUM> or in any other suitable position. Similarly, the lock rod hole <NUM> can be defined between the axially outer face <NUM> of the body <NUM> and the inner cavity <NUM>. Any other suitable location for the damping holes <NUM> and the lock rod hole <NUM> is contemplated herein.

The one or more damping holes <NUM> can include a plurality of damping holes <NUM> as shown (e.g., <NUM> or more). The piston <NUM> can include a piston rod <NUM> extending from the body <NUM> forming part of or configured to connect to a rod end <NUM>. The rod end <NUM> can be configured to connect to the RAT.

In accordance with at least one aspect of this disclosure, as shown in <FIG>, a ram air turbine (RAT) actuator <NUM> can include an uplock mechanism <NUM> defining a chamber <NUM> and configured to be retained in an uplock axial position by one or more lock pawls (not shown). The RAT actuator <NUM> can include a RAT actuator piston <NUM> disposed within the uplock mechanism chamber <NUM> configured to dissipate vibrational energy applied to the piston <NUM> in a locked position. In certain embodiments, the RAT actuator piston <NUM> can be any suitable piston as disclosed herein (e.g., as described above). Any other suitable embodiment of a piston configured to dissipate vibrational energy is contemplated herein.

The RAT actuator <NUM> can include one or more lock pawls (not shown) disposed in the lock pawl windows <NUM>. The RAT actuator <NUM> can include the lock rod <NUM> disposed therein and configured to move axially through the lock rod hole <NUM> and to support the one or more lock pawls in the locked position to maintain the uplock position of the RAT. The lock rod <NUM> is configured to move axially out of the lock rod hole <NUM> (e.g., in direction <NUM>) to allow radially inward movement of the one or more lock pawls in an unlocked position such that the lock pawls disengage the uplock mechanism <NUM> to allow extension of the RAT actuator <NUM>. While certain embodiments can utilize a lock pawl type mechanism for retaining the piston, any other suitable mechanism is contemplated herein. For example, any mechanism that prevents a spring preloaded actuator from deploying is contemplated herein.

The RAT actuator <NUM> can include a valve housing <NUM> operatively connected to the lock rod <NUM> to move the lock rod <NUM> axially. Any suitable construction of the valve housing <NUM> is contemplated herein. The RAT actuator <NUM> can include at least one actuator spring <NUM> configured to extend the RAT actuator <NUM> in the unlocked position of the lock rod <NUM> (e.g., to deploy the RAT as appreciated by those having ordinary skill in the art). The RAT actuator <NUM> can include any suitable components as appreciated by those having ordinary skill in the art in view of this disclosure.

In accordance with at least one aspect of this disclosure, a ram air turbine (RAT) can include any suitable embodiment of a RAT actuator disclosed herein (e.g., as described above). Any other suitable embodiment of a RAT actuator is contemplated herein. Certain embodiments of the RAT include any other suitable components (e.g., a turbine, a shaft, a generator, etc.) for a RAT as appreciated by those having ordinary skill in the art in view of this disclosure.

Traditional systems are not capable of dissipating vibration. In certain embodiments, the RAT can include lock pawls and/or an interface thereof (e.g., in the uplock mechanism) that is dimensioned to allow the piston to vibrate, and the piston can include damper holes that allow damping of vibration of the piston thereby dissipating the vibrational energy in the fluid (e.g., hydraulic fluid) within the uplock mechanism. During the deployment process, the embodiments allow opening of the larger lock rod hole by remove of the lock rod therefrom to allow fast deployment of the piston such that both dissipation and fast deployment can be achieved.

<FIG>, shows a stowed actuator, an actuator once a signal to deploy the actuator to deploy has been given and plunger moved to the right to open orifice and disengage locking mechanism and finally a deployed actuator.

As shown, embodiments can allow the lock rod to move (e.g., to the right as shown) to open the lock rod hole in piston to allow easy flow of fluid (e.g., oil) and to disengage lock pawls from the uplock mechanism housing to allow movement relative to the piston. The valve housing/chamber can pull the lock rod and facilitate restowing of the actuator after deployment.

Embodiments include a damper in the actuator which can damp out the low frequency response in the stowed position for HLSD (high-level-short-duration) and windmilling loading which are typically stowed only requirements. HLSD and windmilling are loadings due rotating imbalance due to loss of a fan blade on one of an aircraft's main engines. Embodiments provide play in the stowed position of the actuator such that enough damping can be provided for the specific design.

Claim 1:
A ram air turbine (RAT) actuator piston (<NUM>), comprising:
a body (<NUM>) defining a piston structure having an inner cavity (<NUM>);
the ram air turbine (RAT) actuator piston being characterized by further comprising
one or more damping holes (<NUM>) axially defined through the body (<NUM>) to the inner cavity (<NUM>); and
a lock rod hole (<NUM>) defined axially through the body (<NUM>) to the inner cavity (<NUM>), wherein the lock rod hole (<NUM>) has a larger flow area than one or more of the one or more damping holes (<NUM>), wherein the lock rod hole (<NUM>) is configured to receive a lock rod (<NUM>) of a RAT actuator (<NUM>) to at least partially block flow through the lock rod hole (<NUM>) when the lock rod (<NUM>) is in a locked position, wherein the one or more damping holes (<NUM>) are configured to allow flow through the one or more damping holes (<NUM>) in the locked position to allow the RAT actuator piston (<NUM>) to move within the RAT actuator (<NUM>) in the locked position to dissipate vibratory loads.