Seat belt retractor mechanism
First Claim
1. In a seat belt retractor mechanism having a seat belt reel rotatably mounted in a support frame adapted to be assembled on a movable door of a vehicle, said mechanism including a reel having at least at one of its ends a generally circular ratchet plate, a locking element mounted on said support frame and movable between a first rest position allowing said reel to rotate and a second lock position engaging said ratchet plate to hold said reel against rotation in a seat belt protraction direction, an inertia sensor element carried by said support frame and having a normal rest position and forceable into an activated position in response to acceleration of said support frame whereat contact occurs within said locking member, an electromagnet having a coil and mounted on said support frame and having a deenergized first condition without current flowing through said coil and an energized second condition with current flowing through said coil, means for preventing movement of said inertia sensor element into said activated position only when said electromagnet is in said energized second condition and only until forces acting on said inertia element exceed a selected magnitude above the inertia forces resulting from normal movement of said vehicle door, and means for moving said locking element into said lock position when said inertia element is forced into said activated position, means for providing a source of current for energizing said electromagnet, and switch means responsive to said door being open for connecting said current source with said electromagnet coil, the improvement comprising:
- said electromagnet having a fixed central core with an exposed, generally flat pole surface, said movement preventing means including a generally flat keeper surface associated with said inertia sensor element formed from a magnetically permeable material and engaging said pole surface in a co-planar relationship when said inertia sensor element is in said normal, rest position and magnetically attracted to said pole surface only while said electromagnet is in said energized second condition, and said means for providing a current source insuring a current having a field strength at least equal to a value which maintains said core in a saturated condition when said door switch means is activated whereby a constant magnetic force is exerted on said keeper surface.
2 Assignments
0 Petitions
Accused Products
Abstract
There is provided an improvement in a seat belt retractor mechanism of the type having a seat belt reel rotatably mounted in a support frame adapted to be assembled on a movable door of a vehicle, wherein the reel has at least on one end a generally circular ratchet plate for engaging a locking element movably mounted on the support frame between a first position allowing the reel to payout the belt freely and a second position engaging the ratchet plate to hold the reel against rotation to payout the seat belt. An inertia sensing element carried by the support frame shifts this locking element into the locked position upon being moved by inertia forces caused by rapid acceleration or deceleration of the vehicle to which the mechanism is mounted. In addition, an electromagnet is employed for increasing the amount of inertia force needed to move the inertia sensor element during such rapid changes in speed of the vehicle. This electromagnet is energized when the door is opened so that movement of the door itself by the occupant in entering or leaving the vehicle will not trip the sensor element. The improvement is the provision of a generally flat pole surface for the electromagnet and a generally flat keeper surface which are engaged in a generally coplanar relationship to cause the increased inertia force by magnetic attraction between the engaged surfaces upon energizing the electromagnet when the door is open. When the door is closed, there is no magnetic force between the engaging surfaces so that the inertia sensor element is moved by normal inertia forces.
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Citations
39 Claims
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1. In a seat belt retractor mechanism having a seat belt reel rotatably mounted in a support frame adapted to be assembled on a movable door of a vehicle, said mechanism including a reel having at least at one of its ends a generally circular ratchet plate, a locking element mounted on said support frame and movable between a first rest position allowing said reel to rotate and a second lock position engaging said ratchet plate to hold said reel against rotation in a seat belt protraction direction, an inertia sensor element carried by said support frame and having a normal rest position and forceable into an activated position in response to acceleration of said support frame whereat contact occurs within said locking member, an electromagnet having a coil and mounted on said support frame and having a deenergized first condition without current flowing through said coil and an energized second condition with current flowing through said coil, means for preventing movement of said inertia sensor element into said activated position only when said electromagnet is in said energized second condition and only until forces acting on said inertia element exceed a selected magnitude above the inertia forces resulting from normal movement of said vehicle door, and means for moving said locking element into said lock position when said inertia element is forced into said activated position, means for providing a source of current for energizing said electromagnet, and switch means responsive to said door being open for connecting said current source with said electromagnet coil, the improvement comprising:
- said electromagnet having a fixed central core with an exposed, generally flat pole surface, said movement preventing means including a generally flat keeper surface associated with said inertia sensor element formed from a magnetically permeable material and engaging said pole surface in a co-planar relationship when said inertia sensor element is in said normal, rest position and magnetically attracted to said pole surface only while said electromagnet is in said energized second condition, and said means for providing a current source insuring a current having a field strength at least equal to a value which maintains said core in a saturated condition when said door switch means is activated whereby a constant magnetic force is exerted on said keeper surface.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A device for locking the payout of a seat belt from a seat belt retractor mechanism in response to a sudden acceleration or deceleration of a vehicle on which said device is mounted, said device comprising an electromagnet with an operating coil and a fixed core with a pole piece having a flat metal plated surface of predetermined thickness, an element with a flat keeper surface formed from magnetically permeable material, an inertia sensing member moved by external forces exerted on said vehicle, means for allowing relative movement between said pole pieces and element from a first position with said pole piece and keeper surface engaging each other in a coplanar relationship into a second position with said keeper surface pulled away from said engaging coplanar relationship when said inertia sensing member is moved, means for mechanically locking said retractor by movement of said inertia sensing member when said pole piece and element are in said second position;
- and means for selectively causing said electromagnet to exert a substantially constant attraction force between said pole piece and keeper surface tending to resist initial movement of said inertia sensing member.
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32. In a seat belt retractor mechanism having a seat belt reel rotatably mounted in a support frame adapted to be assembled on a movable door of a vehicle, said mechanism including a reel having at least at one of its ends a generally circular ratchet plate, a locking element mounted on said support frame and movable between a first rest position allowing said reel to rotate and a second lock position engaging said ratchet plate to hold said reel against rotation in a seat belt protraction direction, an inertia sensor element carried by said support frame and having a normal rest position and forceable into an activated position in response to rapid movement of said support frame whereat contact occurs with said locking member, an electromagnet having a coil mounted on said support frame and having a deenergized first condition and an energized second condition, means for preventing movement of said inertia sensor element into said actuated position only when said electromagnet is in said energized second condition and only until forces acting on said inertia element exceed a selected magnitude above the inertia forces resulting from normal movement of said vehicle door, and means for moving said locking element into said lock position when said inertia element is forced into said activated position, means for providing a source of current for energizing said electromagnet, and switch means responsive to said door being open for connecting said current source with said electromagnet, the improvement comprising:
- said electromagnet having a fixed central core with an exposed, generally flat pole surface plated with non-magnetic material of predetermined thickness, said movement preventing means including a generally flat keeper surface formed from a magnetically permeable material engaging said pole surface in a co-planar relationship when said inertia sensor element is in said normal rest position and magnetically attracted to said pole surface only while said electromagnet is in said energized second condition and means for maintaining a substantially constant attractive force between said keeper surface and said pole piece when current is applied to said electromagnet.
- View Dependent Claims (33, 34, 36, 37, 38, 39)
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35. The improvement as defined in cliam 32 wherein said current source includes a D.C. voltage supply with an output that can vary in operation and wherein said switch means connects said voltage supply across said electromagnet when said door is opened and means for maintaining a constant current through said electromagnet coil as said output varies.
Specification