Door latch with worm gear
Door latching systems, apparatus, articles of manufacture, and methods are disclosed. An example door latch includes a worm gear including a worm wheel and a worm screw, the worm wheel rotatable upon rotation of the worm screw; a lever operatively coupled to the worm wheel, the lever to rotate based on rotation of the worm wheel; a cam surface, the lever to contact the cam surface between a first rotational position and a second rotational position, the second rotational position different from the first rotational position; and a pin to enable rotation of the worm gear.
1 . A door latch comprising:
a worm gear including a worm wheel and a worm screw, the worm wheel rotatable upon rotation of the worm screw;
a lever operatively coupled to the worm wheel, the lever to rotate based on rotation of the worm wheel;
a cam surface, the lever to contact the cam surface between a first rotational position and a second rotational position, the second rotational position different from the first rotational position; and
a pin operable to enable rotation of the worm gear, wherein the pin is movable between an extended position and a retracted position, in the extended position, the pin is to prevent rotation of the worm wheel.
2 . The door latch of claim 1 , wherein the pin is spring loaded and biased to the extended position.
3 . The door latch of claim 1 , further including a housing adjacent the worm gear, the housing including a first aperture,
the worm screw including a second aperture,
the pin including a key pin and a lock pin, and
the worm screw being rotatable when the lock pin is retracted into the first aperture and the key pin is in the second aperture.
4 . The door latch of claim 3 , wherein the worm gear is rotationally fixed when at least a portion of the lock pin is in the second aperture.
5 . The door latch of claim 1 , further including a flexible retaining ring to bias the pin to the extended position.
6 . The door latch of claim 1 , wherein the worm gear is a double enveloping worm gear.
7 . An aircraft comprising:
a door covering a chamber of the aircraft, the door rotatably coupled to the aircraft about a first axis of rotation, the door to rotate between an open position and a closed position, the door including a seal around a perimeter of the door, the seal to deform when the door is in the closed position;
the door latch of claim 1 , the door latch coupled to the door in the chamber, the door latch operable to prevent rotation of the door, and
an opening in a skin of the aircraft, the opening to receive a tool to move the pin and rotate the worm screw.
8 . The aircraft of claim 7 , wherein the lever includes a roller rotatably coupled to an end of the lever, the roller and the cam surface to engage during movement of the door between the open position and the closed position.
9 . The aircraft of claim 7 , wherein the latch includes a torque tube coupling the worm gear and the lever, and the torque tube includes a universal joint between a first end of the torque tube and a second end of the torque tube, the first end and second end having different axes of rotation.
10 . The aircraft of claim 7 , wherein the lever has a second axis of rotation different than the first axis of rotation, and the latch includes a bracket rotatably coupled to the lever, the bracket including a stop to contact the lever at an end of the lever opposite the second axis of rotation about which the lever rotates.
11 . The aircraft of claim 7 , wherein the lever is a first lever and the cam surface is a first cam surface, and the latch includes:
a second lever that is rotatable in response to the rotation of the worm wheel; and
a second cam surface to contact the second lever to prevent the door from moving towards the open position.
12 . The aircraft of claim 11 , wherein the worm gear is between the first lever and the second lever.
13 . The aircraft of claim 7 , wherein the latch includes a housing, the worm gear in the housing, the housing including a first aperture,
the worm screw including a second aperture,
the pin including a key pin and a lock pin, and
the worm screw being rotatable when the lock pin is retracted into the first aperture and the key pin is in the second aperture.
14 . The aircraft of claim 13 , wherein the worm wheel is rotationally fixed when at least a portion of the lock pin is in the second aperture, the latch further including a spring to bias the pin toward the second aperture.
15 . The aircraft of claim 14 , wherein the spring includes a flexible retaining ring adjacent or in the first aperture.
16 . The aircraft of claim 13 , wherein the second aperture is radially displaceable from the first aperture during rotation of the worm screw.
17 . A door latch comprising:
a worm gear including a worm wheel and a worm screw, the worm wheel rotatable upon rotation of the worm screw;
a lever operatively coupled to the worm wheel, the lever to rotate based on rotation of the worm wheel;
a cam surface, the lever to contact the cam surface between a first rotational position and a second rotational position, the second rotational position different from the first rotational position; and
a pin operable to enable rotation of the worm gear, wherein the worm screw includes an interface to receive a key to move the pin and to transfer a torque from the key to the worm screw.