Closure fasteners – Bolts – Swinging
Reexamination Certificate
2001-08-06
2002-10-29
Knight, Anthony (Department: 3676)
Closure fasteners
Bolts
Swinging
C292S143000, C292S342000, C070S208000, C070S472000
Reexamination Certificate
active
06471260
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to improvements in rotary latches of the general type that employ at least one rotary jaw that is releasably retained in a latched position by a rotary pawl, wherein the rotary jaw and the rotary pawl extend principally within what can be referred to as a “primary plane” and pivot about separate parallel-extending axes that are substantially perpendicular to the primary plane, and wherein one or more torsion springs 1) extend principally within what can be referred to as a “secondary plane” located beside and extending parallel to the primary plane, 2) bias the rotary jaw away from its latched position toward its unlatched position, and 3) bias the rotary pawl away from its jaw-releasing position toward its jaw-retaining position—with improvements residing in the manner in which one or more end regions of the torsion springs are coupled to one or both of the rotary jaw and the rotary pawl by connections located principally within the secondary plane. More particularly, the present invention relates to improvements that enhance the service longevity of rotary latches and locks of the general type disclosed in U.S. Pat. Nos. 5,884,948, 5,611,224, 5,595,076, 5,586,458, 5,564,295, 5,439,260, 5,117,665, 5,069,491, 4,917,412, 4,896,906, 4,320,642 and 4,312,203 (referred to hereinafter as the “Rotary Latch Patents,” the disclosures of which are incorporated herein by reference), by providing stress-diminished spring-to-rotary-jaw and spring-to-rotary-pawl connections that utilize C-shaped curve formations defined on end regions of the torsion spring or springs that open outwardly away from coils of the torsion spring or springs, wherein the C-shaped curve formations and peripheral portions of the spring coils are engaged by smoothly curved formations of the rotary jaw and/or the rotary pawl that extend from the primary plane into the secondary plane to establish the improved connections within the secondary plane in a manner that causes no twisting of the torsion springs when forces are transmitted between the torsion springs and the rotary jaw and/or rotary pawl to which the springs are coupled by the improved connections.
2. Prior Art
The Rotary Latch Patents referenced above disclose a variety of latch and lock products, each of which utilizes a rotary jaw that is biased by a torsion coil spring away from a latched position toward an unlatched position, and a rotary pawl that is biased by the same or a separate torsion coil spring away from a jaw-releasing position toward a jaw-retaining position. The rotary jaws and the rotary pawls of these units have engageable formations that cooperate to enable the rotary pawl to retain the rotary jaw in, and to release the rotary jaw from the latched position by pivoting the rotary pawl into and out of the jaw-retaining position.
Other features shared by rotary latch and lock units of general type disclosed in the Rotary Latch Patents include 1) the manner in which each of these units positions torsion coils of one or more torsion springs to extend in a secondary plane located beside and substantially paralleling a primary plane in which the rotary jaw and the rotary pawl extend, and 2) the manner in which connections are formed between end regions of the torsion springs and the rotary jaws and pawls—connections that utilize bent spring end formations that extend transversely out of the secondary plane and into the primary plane to hook across portions of the rotary jaws and pawls. To provide spring end formations that extend smartly across and that hook smartly onto portions of the rotary jaws and pawls, it has become quite customary to introduce relatively sharp bends into the spring end regions—essentially “right-angle bends” that are located at opposite ends of reaches of spring material that extend transversely across and hook onto the jaws and pawls.
While rotary latch and lock units of this type ordinarily offer lengthy service lives, it is important to work toward enhancing the service life longevity of these units by observing which components tend to fail the earliest, and by finding ways to improve the units to eliminate these early failures. Extensive testing has shown that, especially in the presence of excessive vibration, early failures can occur in the torsion springs of these units—failures that tend to be located within the vicinity of where a first right angle bend is used to connect a torsion spring coil to a reach of spring material that extends transversely out of the secondary plane into the primary plane to hook around rotary jaw or pawl portions located within the primary plane.
Most of these spring failures occur near right angle bends in torsion spring end regions that connect with rotary jaws, with a far fewer number of failures occurring near right angle bends in torsion spring end regions that connect with rotary bawls. The fact that more jaw-spring failures have been noted than pawl-spring failures makes sense inasmuch as the rotary jaws pivot through a much wider range of angular movement than do the rotary pawls (which puts more stress on torsion spring portions that connect to the rotary jaw than is experienced by torsion spring that connect with the rotary pawl), and inasmuch as the rotary jaws and the spring portions connected thereto often are subjected to sudden impact forces that come as the result of slamming a strike formation directly into engagement with a rotary jaw to pivot the jaw quickly from its unlatched position to its latched position (whereas rotary pawls and spring portions connected thereto are seldom subjected to sudden and severe impact forces of this type).
If one studies the region of the first right angle bend (where a torsion coil is connected by a right angle bend to a reach of spring material that extends transversely out of the secondary plane across the primary plane to hook around portions of a rotary jaw or pawl), what becomes apparent is that, in the vicinity of this bend, twisting forces are applied to the spring as the transversely extending reach is utilized to transmit forces between the torsion coil and the rotary jaw or pawl. This twisting of the spring in the vicinity of the first right angle bend causes greater stress to occur in the vicinity of the first right angle bend than occurs elsewhere in the spring—and the result, quite naturally, is that the spring tends to break in the vicinity of the first right angle bend after extensive cycles of use or in the presence of severe vibration.
Still another factor that may contribute to early spring breakage within the vicinity of right-angle bends has to do with stresses that may be introduced into a spring in the vicinities of its right angle bends when the spring is formed. The tighter the bend that is formed in a piece of spring wire, the greater is the tendency to introduce unwanted stresses in the vicinity of the bend.
It is well established that even small but cost effective improvements in rotary latch and lock units of the type disclosed in the referenced Rotary Latch Patents tend to gain quick acceptance in industry. There are millions of rotary latch and lock units of this general type presently in service, and the replacement of broken, damaged or disabled units with units that offer enhanced service longevity is a serious ongoing undertaking. In this vein, the improvement features offered by patents such as U.S. Pat. No. 5,884,948, for example, have gained rapid acceptance in industry by providing enhanced service longevity in rotary latch units of relatively low cost.
An important consideration to be taken into account when improvements are provided in rotary latch and lock units of the type disclosed in the referenced Rotary Latch Patents is the fact that the improved units need to offer interchangeability with units that are already in service—so that, when improved units are installed to replace broken, damaged or disabled units, the replacement units will offer size and configuration interchangeability with the units they r
Kuminski Arthur J.
Weinerman Lee S.
Burge David A.
Knight Anthony
The Eastern Company
Williams Mark
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