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A latch assembly includes a chassis, a latch bolt moveably mounted on the chassis and having a closed position for retaining a striker and an open position for releasing the striker, a pawl having an engaged position at which the pawl is engaged with the latch bolt to hold the latch bolt in the clos

A latch assembly includes a chassis, a latch bolt moveably mounted on the chassis and having a closed position for retaining a striker and an open position for releasing the striker, a pawl having an engaged position at which the pawl is engaged with the latch bolt to hold the latch bolt in the closed position and a disengaged position at which the pawl is disengaged from the latch bolt, thereby allowing the latch bolt to move to the open position, an eccentric arrangement defining an eccentric axis and a pawl axis remote from the eccentric axis. The eccentric arrangement is rotatable about the eccentric axis, and the pawl is rotatable about the pawl axis. When the pawl moves from the engaged position to the disengaged position, the eccentric arrangement rotates in one of a clockwise and a counter-clockwise direction about the eccentric axis. With the pawl in the engaged position, a force applied to the pawl by the latch bolt creates a turning moment on the eccentric arrangement in the one of the clockwise and counter-clockwise direction, and the eccentric arrangement is prevented from rotating in said one of the clockwise and counter-clockwise direction by a moveable abutment.

대표청구항 ▼

1. A latch assembly comprising: a chassis;a latch bolt movably mounted on the chassis for movement between a closed position for retaining a striker and an open position for releasing the striker;a crank shaft assembly rotatably mounted to the chassis about a first axis, the first axis being fixed w

1. A latch assembly comprising: a chassis;a latch bolt movably mounted on the chassis for movement between a closed position for retaining a striker and an open position for releasing the striker;a crank shaft assembly rotatably mounted to the chassis about a first axis, the first axis being fixed with respect to the latch assembly;a pawl rotatably mounted to the crank shaft assembly about a second axis, the first axis being offset from the second axis, the second axis being movable with respect to the first axis between a first position and a second position and wherein the pawl moves between an engaged position wherein the pawl is positioned to hold the latch bolt in the closed position and a disengaged position wherein the pawl is positioned to allow the latch bolt to move from the closed position to the open position; wherein the latch bolt is configured to rotate the pawl and the crank shaft assembly about the first axis such that the second axis moves from the second position to the first position as the latch bolt moves from the closed position to the open position;wherein the second axis is in the first position when the latch bolt is in the closed position; andwherein the second axis does not move as the latch bolt is moved into the closed position from the open position. 2. The latch assembly as defined in claim 1 wherein the pawl is a tension pawl. 3. The latch assembly as defined in claim 1 wherein the pawl is a compression pawl. 4. The latch assembly as defined in claim 1 further comprising a moveable abutment for preventing the pawl from moving from the engaged position to the disengaged position, wherein the moveable abutment is actuable by a powered release actuator. 5. The latch assembly as defined in claim 4 wherein the powered release actuator is configured to return the crank shaft assembly to a closed position. 6. The latch assembly as defined in claim 1 further comprising a moveable abutment for preventing the pawl from moving from the engaged position to the disengaged position, wherein the moveable abutment is manually actuable. 7. The latch assembly as defined in claim 6 wherein with the latch in the closed position, a release abutment of the crank shaft assembly engages the moveable abutment to prevent the crank shaft assembly from moving and the release abutment is defined by a release arrangement having a first lever rotationally fast with the crank shaft assembly and a second lever pivotally mounted on the chassis, the second lever includes the release abutment, and the first lever and the second lever are operably coupled by a link pivotally mounted at one end to the first lever and pivotally mounted at another end to the second lever. 8. The latch assembly as defined in claim 1 wherein the crank shaft assembly comprises: a crank shaft having a crank pin in the form of a disc wherein the center of the disc defines the second axis and the disc is rotationally received within an opening in the pawl, the center of the opening of the pawl being coincident with the second axis. 9. The latch assembly as defined in claim 8 wherein the crank shaft assembly further comprises a cylindrical pin extending from one side of the disc and a square shaft extending from an opposite side of the disc, wherein the cylindrical pin and the square shaft define the first axis. 10. The latch assembly as defined in claim 8 wherein the crank shaft assembly further comprises a cylindrical pin extending from one side of the disc and rotationally supported by the latch assembly, wherein the disc has a crank shaft radius and the cylindrical pin has a pin radius, and the first axis is offset from the second axis by less than the pin radius plus the crank shaft radius. 11. The latch assembly as defined in claim 10 wherein the first axis is offset from the second axis by less than the pin radius. 12. The latch assembly as defined in claim 10 wherein the first axis is offset from the second axis by less than the pin radius minus the crank shaft radius. 13. The latch assembly as defined in claim 1 wherein the crank shaft assembly rotates about the first axis such that the second axis moves to the second position in order to allow the latch bolt to begin movement from the closed position to the open position, and as the latch bolt moves toward the open position it rotates the crank shaft assembly such that the second axis is returned to the first position when the latch bolt reaches the open position. 14. The latch assembly as defined in claim 1, wherein the latch assembly has a reset condition wherein the latch bolt is partially closed, the pawl is in the disengaged position, and the second axis is in the first position. 15. The latch assembly as defined in claim 14, wherein during movement of the latch bolt from the closed position to the open position, the crank shaft assembly rotates such that the second axis moves to the second position, and wherein during movement of the latch bolt from the open condition to the reset condition, the latch bolt rotates the crank shaft assembly such that the second axis is returned to the first position. 16. The latch assembly as defined in claim 14 wherein the latch bolt engages a reset abutment of the crank shaft assembly to move the second axis from the second position to the first position. 17. The latch assembly as defined in claim 16 wherein the reset abutment is defined on a reset lever of the crank shaft assembly. 18. The latch assembly as defined in claim 1 wherein the chassis includes a chassis control surface engageable by a pawl control surface of the pawl such that during movement of the pawl from the engaged position to the disengaged position, the crank shaft assembly rotates so that the second axis is constrained to move along an arc centered on the first axis, and an angular position of the pawl is controlled by engagement between the chassis control surface and the pawl control surface. 19. The latch assembly as defined in claim 18 wherein a resilient member biases the pawl in a first rotational direction about the second axis and biases the pawl in a second rotational axis about a point of contact between the chassis control surface and the pawl control surface. 20. A method of opening a latch, the method comprising the steps of: rotatably mounting a latch bolt to a chassis of the latch assembly for movement between a closed position for retaining a striker and an open position for releasing the striker;rotatably mounting a pawl to the latch assembly for movement between an engaged position at which the pawl is engaged with the latch bolt to hold the latch bolt in the closed position and a disengaged position at which the pawl is disengaged from the latch bolt, thereby allowing the latch bolt to move to the open position;rotatably mounting a crank shaft assembly to the latch assembly for movement about a first axis;rotatably mounting the pawl to the crank shaft assembly for movement about a second axis, the first axis being offset from the second axis and the first axis being fixed with respect to the latch assembly and the second axis being moveable with respect to the first axis;putting the latch bolt in the closed position, wherein the pawl is in the engaged position and the second axis is in a first position;causing the latch bolt to apply a force to the pawl to create a turning moment on the crank shaft assembly for movement about the first axis and reacting the turning moment at a moveable abutment to prevent movement of the crank shaft assembly;subsequently moving the moveable abutment so the turning moment is no longer reacted, thereby allowing the force to move the crank shaft assembly such that the second axis moves to a second position and the pawl moves to the disengaged position, allowing the latch bolt to move to the open position, thereby opening the latch; andmoving the second axis to the first position as the latch bolt is moved into the open position and wherein the second axis does not move as the latch bolt is moved into the closed position from the open position. 21. The method of opening the latch as defined in claim 20 including the further steps of: putting the latch bolt in the closed position and the pawl in the engaged position to retain the striker, causing the striker to apply a force to the latch bolt, thereby causing the latch bolt to apply the force to the pawl, and allowing the latch bolt to move to the open position, thereby releasing the striker and opening the latch. 22. The method of opening the latch as defined in claim 20, wherein the second axis is in the first position prior to the pawl being returned to the engaged position.