Payload retention device

• US 5,125,601 A
• Filed: 12/26/1991
• Issued: 06/30/1992
• Est. Priority Date: 12/26/1991
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: The United States of America As Represented By The Secretary of Agriculture
• Inventors: Monford, Leo G. Jr.
• Primary Examiner(s): Peters, Jr., Joseph F.
• Assistant Examiner(s): Ellis, Christopher P.
• Application Number:
  US07/813,558
• Time in Patent Office: 187 Days
• Field of Search: 244/161, 244/158 R, 244/157.1, 244/159, 244/118.1, 294/86.4, 294/65.5, 294/66.2, 414/29, 414/45, 901/30, 901/40, 901/46, 335/285-291
• US Class Current: 244/173.1
• CPC Class Codes: B64G 1/641 Interstage or payload connectors docking systems B64G1/646

Abstract

A payload retention device (10) for grappling and retaining a payload (14) in docked position on a supporting structure (18) in the cargo bay of a space vehicle. The device comprises a two-fault tolerant electromagnetic grappling system comprising electromagnets (30A,30B) for attracting and grappling a grapple strike plate (20) affixed to the payload when in proximity thereto and an electromechanical latching assembly comprising a pair of independent latching subassemblies. Each subassembly comprises a set of latching pawls (29) which are driven into latching and unlatching positions relative to a grappled payload by a pair of gearmotors (40), each equipped with a ratchet clutch drive mechanism (75, 76) which is two-fault tolerant with respect to latching such that only one gearmotor of the four needs to be operational to effect a latch of the payload but is single fault tolerant with respect to release of a latched payload. Sensors (72,92,96) are included for automatically sensing the magnetic grappling of a payload and for automatically de-energizing the gearmotors (40) of the latching subassemblies when a latch condition is achieved.

Claims

1. A payload retention device for grappling and retaining a payload in a docked position on a support structure mounted in the cargo bay of a space vehicle, and wherein said payload is provided with a grapple strike plate, said device comprising:

a base plate mounted on said support structure;

at least one electromagnet mounted to said base plate, said electromagnet comprising a U-shaped magnetic core with pole pieces at the ends thereof and a plurality of coils wound about said magnetic core between said pole pieces, said base plate having openings therethrough which receive and accommodate said pole pieces therein;

means for energizing said coils whereby said electromagnet exerts an attractive force on the grapple strike plate affixed to said payload when the payload is moved in proximity thereto and causes said pole pieces to contact and grapple said strike plate;

contact sensor means for detecting the contact of said pole pieces with said strike plate and the grappling of the payload to said base plate and generating an electrical output signal indicative thereof;

an electromechanical latching assembly comprising a pair of independent latching subsystems, each said latching subsystem comprising a cam ring gear mounted to said base plate and journalled for axial rotation thereon with said base plate being in substantially concentric parallel relation to both cam ring gears;

a plurality of camming surfaces provided on each said cam ring gear at equiangularly spaced locations about the periphery thereof;

a first set of latching pawls mounted to said base plate at equiangularly spaced locations relative to said base plate and cam ring gear of a first of said latching subsystems;

a second set of latching pawls mounted to said base plate at equiangularly spaced locations relative to said base plate and cam ring gear of a second of said latching subsystems with the latching pawls of each of said sets being mounted adjacent a peripheral edge of the base plate at locations intermediate the locations of the other set of latching pawls, each said pawl having a cam follower surface adapted to engage with a peripheral surface of the associated cam ring gear of its latching subsystem and each said pawl having a latch hook formed adjacent one end of the pawl;

means for mounting each said latching pawl for pivotal movement whereby the latch hook of each said pawl is movable towards and away from the center of its associated cam gear ring;

means for biasing each said latching pawl in pivotal movement towards the center of the associated cam ring gear of its latching subassembly such that the cam follower surface of the pawl is continually engaged with the peripheral surface of its associated cam gear ring and whereby the cam follower surface of each said latching pawl is engaged by a different one of said camming surfaces upon a predetermined amount of axial rotation of its associated cam ring gear to induce pivotal movement of the pawls to a latching position wherein the latch hook of each said pawl is at an innermost position relative to the center of its associated cam ring gear and is adapted to engage a latching surface provided on the strike plate of a target payload when the payload is seated on said base plate;

each said latching assembly including motor means which are selectively energizeable for driving the cam ring gear of the latching subassembly in unidirectional rotation about its central axis in concert with the axial rotation of the other of said cam gears and further including switch means responsive to the axial rotation of the cam ring gear to de-energize said motor means and halt the rotation of the cam ring gear when the latching pawls are in the latching position; and

spring means mounted on said base plate for biasing a grappled payload into firm latching engagement with the latch hooks of each said latching pawl when all the coils of the electromagnets are de-energized.

2. A payload retention device as set forth in claim 1 wherein said strike plate is provided with alignment pins which project outwardly of said strike plate and are adapted for interconnection with sockets provided in the base plate of said payload retention device when the payload is aligned for docking engagement with said base plate preparatory to effecting a grapple of the payload.

3. A payload retention device as set forth in claim 1 wherein said electromagnet coils comprise a pair of holding coils and a pull-in coil for generating an attractive force sufficient to cause said magnet pole pieces to attract the strike plate on said grapple fixture to said electromagnet to effect a grapple of said payload when in contact with said base plate;

and

means responsive to the signal from said contact sensor means for automatically de-energizing said pull-in coil whereby the grapple of the payload is maintained solely by the attractive force of said holding coils.

4. A payload retention device as set forth in claim 1 wherein the motor means in each said latching subassembly comprises a pair of gearmotors, each coupled by a ratchet clutch drive mechanism in driving connection with the associated cam ring gear of the latching subassembly for effecting the axial rotation thereof whereby in the event of failure of one of the gearmotors the other motor of said pair of gearmotors can effect the axial rotation of the associated cam ring gear and movement of its associated latching pawls to either their latched or unlatched positions.

5. A payload retention device for grappling and retaining a payload in a docked position on a support structure mounted in the cargo bay of a space vehicle, and wherein said payload is provided with a grapple strike plate, said device comprising:

a base plate mounted on said support structure and provided with a planar surface adapted to be contacted by said strike plate;

an electromagnetic grappling system for grappling the payload, said system comprising a pair of electromagnets mounted to said base plate, each said electromagnet comprising a U-shaped magnetic core with pole pieces at the ends thereof and a plurality of coils wound about said magnetic core between said pole pieces, said base plate having openings therethrough which are sized to receive and accommodate said pole pieces;

an annular spring washer mounted on said base plate such that the washer projects from the planar surface of the base plate with an annular edge of the washer disposed parallel to said planar surface and is adapted to be first contacted by the strike plate on a payload to be grappled by said electromagnetic grappling system;

an individual control circuit for each electromagnet;

first and second power sources connectable to said individual control circuits, respectively, for energizing said coils whereby said electromagnets exert an attractive force on the grapple strike plate when the payload is placed in proximity thereto to cause said pole pieces to overcome the spring washer and to contact and grapple said strike plate;

contact sensor means in each said individual control circuit for detecting the contact of the pole pieces of the electromagnets with said strike plate and generating an electrical output signal indicative thereof;

an electromechanical latching assembly comprising a cam gear ring mounted to said base plate and journalled for axial rotation with said base plate being in substantially concentric parallel relation to said cam ring gear;

a plurality of camming surfaces provided on said cam ring gear at equiangularly spaced locations about the periphery thereof;

a plurality of latching pawls mounted to said base plate at equiangularly spaced locations relative to said cam ring gear, each said pawl having a cam follower surface adapted to engage with a peripheral surface of the cam ring gear and a latch hook formed adjacent one end of the pawl;

means for mounting each said latching pawl for pivotal movement whereby the latch hook of each said pawl is movable towards and away from the center of its associated cam ring gear;

means for biasing each said latching pawl in pivotal movement toward said cam ring gear such that the cam follower surface of the pawl is continually engaged with the peripheral surface of the cam ring gear whereby the cam follower surface of each said latching pawl is engageable by a different one of said camming surfaces upon a predetermined amount of axial rotation of said cam ring gear to induce a pivotal movement of the pawl to a latching position wherein the latch hook of said pawl is at an innermost position relative to the center of the cam ring gear and is adapted to engage an annular latching surface provided on a target payload when the payload is seated on said base plate;

motor means which are selectively energizeable for driving said cam ring gear in unidirectional rotation about its central axis; and

switch means responsive to the axial rotation of said cam ring gear to de-energize said motor means and halt the rotation of the cam ring gear when the latching pawls are in the latching position, a spring washer mounted on said base plate biasing said payload into firm latching engagement with the latch hooks of the latching pawls when all the coils of the electromagnets are de-energized.

6. A payload retention device for grappling, securing and retaining a payload in a docked position on a support structure in the cargo bay of a space vehicle and wherein said payload is equipped with a grapple strike plate, said device comprising:

a base plate mounted on said support and provided with a support surface adapted to be engaged by said strike plate;

at least one electromagnet mounted to said base plate, said electromagnet comprising a U-shaped magnetic core with pole pieces at the ends thereof and a plurality of coils wound about said magnetic core between said pole pieces, said base plate having openings therethrough which are sized to receive and accommodate said pole pieces therein;

means for energizing said coils whereby said electromagnet exerts an attractive force on a grapple strike plate affixed to said payload when the payload is moved in proximity thereto and causes said pole pieces to attract and grapple said strike plate;

contact sensor means for detecting the contact to said pole pieces with the strike plate and generating an electrical output signal indicative thereof;

an electromechanical latching assembly comprising a plurality of latching pawls mounted to said base plate, each of said latching pawls being provided with a latch hook formed adjacent one end of the pawl;

means for mounting each said latching pawl for pivotal movement whereby the hook surface of said pawl is movable towards and away from the peripheral edge of said base plate;

means for biasing each said latching pawl in pivotal movement toward said base plate to a latching position wherein the latch hook of said pawl is at an innermost position relative to the center of the base plate and is adapted to engage an annular latching surface provided on a target payload when the payload is seated on said base plate; and

motor drive means which are energizeable for selectively driving said pawls to the latching position and also for driving said pawls to an unlatching position, said motor drive means comprising at least a pair of gearmotors, each equipped with a ratchet clutch drive mechanism whereby any one of said gearmotors can override the drive mechanisms of the other gearmotors in the event of their failure and thereby move said pawls to the latching position.