Patent Description:
Exemplary embodiments pertain to the art of aircraft and, more particularly, to a one-way speed limiter for a power door opening system (PDOS) for an aircraft.

Outward opening doors, such as may be found on an aircraft engine nacelle typically employ a hydraulic or an electric power door opening system (PDOS). The electric PDOS employs an actuator which generally includes a screw shaft and nut-based mechanism in which screw is rotating member while nut is translating member. The screw is driven by an electric motor via gear and clutch arrangement. Generally, the PDOS includes a no-back unit, which acts as one way clutch and allows free rotation of screw in extension direction and imposes a resistive torque which is directly proportional to axial load, in retraction direction. As such, the actuator can be retracted only by the motor. That is, if power to the motor is lost, the PDOS does not allow retraction of actuator. The no-back unit prevents the free rotation of the actuator needed to lower or close the door. Without the no-back unit, the actuator/door will retract at an uncontrolled rate. <CIT> describes a nacelle with hinged cowl doors enabling access to the engine. <CIT> describes an enhanced lubrication skewed roller clutch assembly.

A one-way speed limiter for a power door opening system mounted in an aircraft is defined in claim <NUM>. The one-way speed limiter includes a first housing including a first wall including an outer surface and an inner surface. The inner surface defines a speed limiter receiving zone. A second housing extends into the first housing. The second housing includes a flange having an inner surface section and a second wall extending outwardly from the flange the second wall including an outer surface portion that engages with the inner surface of the first housing and an inner surface portion that includes a stop feature. A ball housing including a ball member is rotatably supported in the speed limiter receiving zone. The ball member selectively engages the stop feature to generate an axial force on the ball housing. A friction clutch is disposed between the ball housing and the first housing. The friction clutch selectively retards rotation of the ball housing. A motor shaft is selectively rotatably connected to the ball housing. The motor shaft including a first end supported at the ball housing and a second end. The motor shaft is rotatable relative to the ball housing in a first direction and selectively rotatably constrained relative to the ball housing in a second direction to selectively engage the friction clutch.

The ball housing includes a central hub supporting a bearing and a one-way clutch axially spaced from the bearing, the motor shaft being operatively connected to the one-way clutch with the first end of the motor shaft being supported by the bearing.

Additionally, or alternatively, in this or other non-limiting examples, the one-way clutch comprises a sprag clutch.

Additionally, or alternatively, in this or other non-limiting examples, the ball housing includes a plurality of cups extending about and arranged radially outwardly of the central hub.

Additionally, or alternatively, in this or other non-limiting examples, the ball member comprises a ball arranged in one of the plurality of cups.

Additionally, or alternatively, in this or other non-limiting examples, the ball member includes a plurality of balls arranged in corresponding ones of the plurality of cups.

Additionally, or alternatively, in this or other non-limiting examples, the stop feature comprises an angled surface extending between an inner surface section of the flange and the inner surface portion of the second wall.

Additionally, or alternatively, in this or other non-limiting examples, the friction clutch comprises a friction plate supporting a plurality of skewed bearings.

Additionally, or alternatively, in this or other non-limiting examples, the one-way speed limiter is employed in combination with a motor connected to the motor shaft. The motor selectively rotates the motor shaft in the first direction and in the second direction. A door operatively connected to the motor shaft.

Additionally, or alternatively, in this or other non-limiting examples, the door is mounted on a door shaft that is operatively connected to the motor shaft through a gear system.

An aircraft is described herein and defined in claim <NUM> and includes a fuselage including a tail, a wing projecting outwardly from the fuselage, an engine including a cowl supported by one of the fuselage, and the wing, a door provided on one of the fuselage and the cowl. The door includes a power door opening system (PDOS) including a one-way speed limiter.

Additionally, or alternatively, in this or other non-limiting examples, a motor connected to the motor shaft, the motor selectively rotating the motor shaft in the first direction and in the second direction, wherein the door is operatively connected to the motor shaft.

Additionally, or alternatively, in this or other non-limiting examples, the door is pivotally mounted to the cowl.

An aircraft, in accordance with a non-limiting example, is indicated generally at <NUM> in <FIG>. Aircraft <NUM> includes a fuselage <NUM> including a tail <NUM> and a wing <NUM>. Tail <NUM> supports a horizontal stabilizer <NUM>. Wing <NUM> supports an engine nacelle <NUM>. It should be understood that aircraft <NUM> includes a second wing (not shown) that supports a second engine nacelle (also not shown). The number and mounting locations of the engine nacelles may vary.

As shown in <FIG>, engine nacelle <NUM> houses an engine <NUM>. In a non-limiting example, engine nacelle <NUM> includes a frame <NUM> that supports cowl <NUM>. Cowl <NUM> protects engine <NUM> from environmental effects. Cowl <NUM> includes a first door <NUM> and a second door <NUM> that are pivotally mounted to frame <NUM>. First door <NUM> and second door <NUM> may be selectively opened to provide access to engine <NUM> for maintenance and the like. In a non-limiting example, first door <NUM> is connected to a power door opening system (PDOS) <NUM>. Second door <NUM> may also be connected to PDOS <NUM>. PDOS <NUM> selectively opens and closes first door <NUM> and/or second door <NUM> to provide access to engine <NUM>. Further, in an absence of power, PDOS <NUM> allows first door <NUM> and/or second door <NUM> to be moved to a closed configuration in a controlled manner.

Referring to <FIG>, PDOS <NUM> includes a motor <NUM> connected to a motor shaft <NUM>. Motor shaft <NUM> is connected to a door shaft <NUM> through a gear system <NUM>. In accordance with a non-limiting example, door shaft <NUM> extends substantially parallel to motor shaft <NUM> and is operatively connected to first door <NUM> and/or second door <NUM>. Of course, it should be understood that other arrangements of motor shaft <NUM> and door shaft <NUM> are also contemplated.

Motor shaft <NUM> includes a first end <NUM>, a second end <NUM> connected to motor <NUM> and an intermediate portion <NUM> that is connected to gear system <NUM>. That is, a first gear <NUM> of gear system <NUM> is mounted to intermediate portion <NUM> of motor shaft <NUM> and a second gear <NUM> is connected to door shaft <NUM>. Operation of motor <NUM> causes first gear <NUM> to rotate second gear <NUM> which in turn rotates door shaft <NUM> to shift first door <NUM> and/or second door <NUM>.

In a non-limiting example, a one-way speed limiter <NUM> is connected to first end <NUM> of motor shaft <NUM>. One-way speed limiter <NUM> allows motor shaft <NUM> to freely move first door <NUM> and/or second door <NUM> to an open configuration as shown in <FIG> and mandates a controlled movement of motor shaft <NUM> to close first door <NUM>. One-way speed limiter <NUM> includes a first housing <NUM>, a second housing <NUM>, and a ball housing <NUM> that is disposed between and encapsulated by, first housing <NUM> and second housing <NUM>.

First housing <NUM> includes a first wall <NUM> that defines an outer surface <NUM> and an inner surface <NUM>. Inner surface <NUM> defines, in part, a speed limiter receiving zone <NUM> within which is arranged ball housing <NUM>. First wall <NUM> includes a first annular segment <NUM> connected to a second annular segment <NUM> by a first base wall <NUM>. Second annular segment <NUM> extends outwardly from first base wall <NUM>. A second base wall <NUM> is axially spaced from first base wall <NUM> and is connected to second annular segment <NUM>. First annular segment <NUM> includes a first circumference and second annular segment <NUM> includes a second circumference that, in the non-limiting example shown, is smaller than the first circumference. Second annular segment <NUM> and second base wall <NUM> define a stopper housing support <NUM>.

Second housing <NUM> includes a flange <NUM> through which passes motor shaft <NUM>. A second wall <NUM> is connected to flange <NUM>. Flange <NUM> includes an inner surface section <NUM> and an outer surface section <NUM>. Second wall <NUM> extends substantially perpendicularly from inner surface section <NUM>. Second wall <NUM> includes an outer surface portion <NUM> and an inner surface portion <NUM>. Outer surface portion <NUM> and inner surface portion <NUM> are, in a non-limiting example, annular surfaces. Outer surface portion <NUM> abuts inner surface <NUM> of first wall <NUM>. A shim <NUM> is disposed between second wall <NUM> and an inner surface (not separately labeled) of first base wall <NUM>. Second housing <NUM> includes a stop feature <NUM> which, as will be detailed herein, that prevents uncontrolled rotation of motor shaft <NUM> in a door closing direction. Stop feature <NUM> is shown in the form of an angular surface <NUM> that extends between inner surface section <NUM> and inner surface portion <NUM>.

In a non-limiting example, ball housing <NUM> includes a central hub <NUM> that includes a bearing portion <NUM> and a clutch portion <NUM>. A bearing <NUM> is arranged in bearing portion <NUM>. Bearing <NUM> supports first end <NUM> of motor shaft <NUM>. Clutch portion <NUM> supports a one-way clutch <NUM> that is operatively connected with intermediate portion <NUM> of motor shaft <NUM>. One-way clutch <NUM> may take the form of a sprag clutch <NUM> that allows motor shaft <NUM> to rotate in first direction to open first door <NUM> and or second door <NUM> and prevents uncontrolled rotation of motor shaft <NUM> in a second direction, that is opposite the first direction. That is, motor shaft <NUM> in the second direction allows first door <NUM> to close below a designed limiting speed. In second direction, motor shaft <NUM> and ball housing <NUM> rotate together due to one-way clutch <NUM>.

In a non-limiting example shown in <FIG>, ball housing <NUM> includes a cup support <NUM> that extends radially outwardly of central hub <NUM>. Cup support <NUM> includes an outwardly facing circumferential edge <NUM> that is radially spaced from central hub <NUM>. A plurality of cups <NUM> are formed in cup support <NUM>. The plurality of cups <NUM> extend circumferentially about cup support <NUM> between central hub <NUM> and outwardly facing circumferential edge <NUM>. In a non-limiting example, each of the plurality of cups <NUM> includes an opening <NUM> positioned at outwardly facing circumferential edge <NUM>.

In a non-limiting example, a ball member <NUM> is provided in each of the plurality of cups <NUM>. Ball member <NUM> is shown in the form of a spherical ball <NUM>. Of course, it should be understood that the particular shape of ball member <NUM> may vary. Ball members <NUM> rest freely in each of the plurality of cups <NUM>. In the event that motor <NUM> loses power, motor shaft <NUM> will not spin out of control allowing first door <NUM> to fall closed.

Instead, rotation of motor shaft <NUM> will lock one-way clutch <NUM> to ball housing <NUM>. Further rotation of motor shaft <NUM> will cause ball housing <NUM> to rotate causing ball members <NUM> to move outwardly into contact with angular surface <NUM>. Contact between the ball members <NUM> and angular surface <NUM> generates an axial force that acts upon ball housing <NUM>. As shown in <FIG> a friction clutch <NUM> is disposed between cup support <NUM> and an inner surface (not separately labeled) of first base wall <NUM>. In a non-limiting example, friction clutch <NUM> takes the form of a friction plate <NUM> supporting a plurality of skewed roller bearings <NUM>. The term "skewed roller bearings" should be understood to describe a roller bearing having an axis of rotation that is skewed relative to a radius extending from an axis of rotation "A" of motor shaft <NUM>. Of course, it should be understood that friction clutch <NUM> could take on a variety of forms.

Loss of electrical power to motor <NUM> could cause first door <NUM> and or second door <NUM> to back drive motor shaft <NUM>. Gravity, acting on first door <NUM> and/or second door <NUM>, could cause a reverse rotation of motor shaft <NUM> and ball housing <NUM>. due to back drive torque from door shaft <NUM>. The reverse rotation of ball housing <NUM> will generate a force that urges ball members <NUM> radially outwardly and project through corresponding ones of openings <NUM>.

At this point, ball members <NUM> will engage with and exert a force on stop feature <NUM>. A reaction force on ball members <NUM> will urge ball housing <NUM> into contact with friction clutch <NUM>. If rotational speed of the motor shaft <NUM> due to back drive forces reaches a designed limit, resistive torque from friction clutch <NUM> tends to exceed the back drive torque to retard rotation of motor shaft <NUM>. However, motor shaft <NUM> rotates within a designed speed limit, friction clutch <NUM> will slip allowing first door <NUM> and or second door <NUM> to close. Thus, one-way speed limiter <NUM> will prevent first door <NUM> and/or second door <NUM> from falling closed in an uncontrolled manner if power to motor <NUM> is lost. However, one-way speed limiter <NUM> still allows a controlled closing of first door <NUM>. That is, first door <NUM> may be slowly lowered, such as by a forklift, and closed without causing friction clutch <NUM> to fully engage.

Claim 1:
A one-way speed limiter for a power door opening system mounted in an aircraft, the one-way speed limiter comprising:
a first housing (<NUM>) including a first wall including an outer surface and an inner surface, the inner surface defining a speed limiter receiving zone;
a second housing (<NUM>) extending into the first housing (<NUM>), the second housing (<NUM>) including a flange having an inner surface section and a second wall extending outwardly from the flange the second wall including an outer surface portion that engages with the inner surface of the first housing (<NUM>) and an inner surface portion that includes a stop feature;
a ball housing (<NUM>) including a ball member is rotatably supported in the speed limiter receiving zone, the ball member selectively engaging the stop feature to generate an axial force on the ball housing (<NUM>);
a friction clutch disposed between the ball housing (<NUM>) and the first housing (<NUM>), the friction clutch selectively retarding rotation of the ball housing (<NUM>); and
a motor shaft (<NUM>) selectively rotatably connected to the ball housing (<NUM>), the motor shaft (<NUM>) including a first end supported at the ball housing (<NUM>) and a second end, the motor shaft (<NUM>) being rotatable relative to the ball housing (<NUM>) in a first direction and selectively rotatably constrained relative to the ball housing (<NUM>) in a second direction to selectively engage the friction clutch, and characterized in that the ball housing (<NUM>) includes a central hub supporting a bearing and a one-way clutch axially spaced from the bearing, the motor shaft (<NUM>) being operatively connected to the one-way clutch with the first end of the ,motor shaft (<NUM>) being supported by the bearing.