Patent Grant
7121857
The invention relates generally to interconnect systems. More particularly, the invention relates to spring-loaded electrical connectors for absorbing physical design tolerances.
In the design and manufacture of electronic systems, physical tolerances define the acceptable maximum deviation from the specified norm for a dimension of a component part or assembly. In some electronic systems, it is difficult to satisfy these tolerances and still produce good interconnectivity among the various components within the system. For example, consider an electronic system having a chassis and an electronic subassembly that enters into and couples to the chassis. This subassembly has an electrical connector configured to mate with an electrical connector of the chassis. For the electronic system to operate properly, the mating electrical connectors need to make minimal contact engagement and remain fully mated throughout the operation of the electronic system. Accordingly, tolerances affecting these connectors are determined such that the mating connectors are “bottomed out,” that is, fully engaged—one connector has penetrated the other connector as far as possible. This fully engaged condition presents the best opportunity for electrical contact between the electrical connectors.
To keep such connectors fully engaged, usually the subassembly is latched or locked within the chassis. Tolerances apply also to the placement of the latch mechanism on the subassembly and of any corresponding latch receptacle on the chassis. Considered in the determination of these latching mechanism tolerances are those of the connectors. For instance, there can be specified tolerances from the latch mechanism on the subassembly to the connector on the subassembly, from the connector on the subassembly to the connector on the chassis, and from the connector on the chassis to the internal latch receptacle on the chassis. Thus, proper latching between the subassembly and chassis involves complex, simultaneous satisfaction of numerous physical tolerances. If, for example, these tolerances indicate that the placement of the latch mechanism on the subassembly has a tolerance window of plus or minus 80 thousandths of an inch, then the chassis needs a latch receiving region measuring 160 thousandths of an inch wide gap to accommodate the various potential placements of the latch mechanism. Thus, a worst-case compliant system design can have almost 160 thousandths of an inch movement of the subassembly within the chassis. Movement of this magnitude can allow the latch mechanism to move during vibration and shock of the electronic system. Such movement can disengage the mating connectors and cause the electronic system to fail.
Further, mating electrical connectors have a preferred measure of “wipe”, that is, a minimum overlap between the mating connectors so that the act of joining the connectors operates to remove oxidants from the conductive elements, referred to as contacts, and thus improve electrical conductivity. The various tolerances can reduce this overlap to an unsatisfactory length. Thus, there is a need for a system capable of accommodating the various physical tolerances in an electronic system while providing robust mechanical connectivity and electrical conductivity between mating connectors.
In one aspect, the invention features a tolerance absorbing interconnect system for use in an electronics enclosure. A first connector assembly is mounted to a first enclosure portion. A second connector assembly is movably mounted to a structural member of a second enclosure portion. The second connector assembly is configured for mating with the first connector assembly. The second connector assembly has a connector body, a shoulder screw, and a spring. The connector body has a flange with a hole therein. The shoulder screw has a barrel portion that passes through the hole in the flange and a threaded portion that enters a hole in the structural member. Coiled around the barrel portion of the shoulder screw between the flange and the structural member is a spring. The interconnect system also includes a securing mechanism for coupling the first enclosure portion to the second enclosure portion when the first connector assembly mates with and pushes against the second connector assembly, causing the spring to compress. Whereupon, when the securing mechanism couples the first enclosure portion to the second enclosure portion, the spring remains compressed and urges the second connector assembly against the first connector assembly to maintain an interconnection therebetween.
In another aspect, the invention features a connector assembly comprising an electrical connector having a connector body and a standoff having a first end and an opposite end. The standoff is movably coupled at the first end to the connector body of the electrical connector and fixedly coupled at the other end to a structural member. The electrical connector is able to move toward the structural member while remaining coupled to the standoff. A spring member is disposed between the connector body of the electrical connector and the structural member. One end of the spring member opposes the connector body and the other end of the spring member opposes the structural member. The spring member compresses when the electrical connector is urged towards the structural member.
In still another aspect, the invention features a tolerance-absorbing interconnect system, comprising a chassis having an open end and a first securing mechanism. The interconnect system also has a structural member, a first connector having a connector body with a flange having a hole therein, a fastener having an elongated barrel portion passing through the hole in the flange, and means for coupling the fastener to the structural member. A spring member is coiled around the barrel portion of the fastener between the flange and the structural member. In addition, the interconnect system includes an assembly having a second connector and a second securing mechanism for coupling to the first securing mechanism when the assembly slides a predetermined distance into the chassis through the open end. The distance is such that, in order for the securing mechanisms to couple, the first and second connectors mate and push against each other to compress the spring member. Whereupon when the securing mechanisms couple, the spring member remains compressed and urges one of the connectors against the other connector.
The above and further advantages of this invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
The invention features an interconnect system for absorbing various physical tolerances associated with the placement of mechanical securing mechanisms and mating electrical connectors in a chassis and subassembly of an electronics system. One of the mating electrical connectors is mounted to a structural member of the chassis, and the other extends from a rear side of the subassembly; one of these electrical connectors is spring-loaded, that is, one or more springs are disposed between the body of the electrical connector and the chassis structural member (or subassembly rear side) to which the electrical connector is attached. When the subassembly is inserted into the chassis, the electrical connectors approach, meet, and join each other. After the mating connectors “bottom out,” i.e., fully engage, additional force on the subassembly operates to push back on the spring-loaded connector, compressing its spring(s), until the securing mechanisms of the chassis and subassembly engage. Once engaged the subassembly remains secure within the chassis, and the compressed spring(s) of the spring-loaded connector exert a force urging the chassis and subassembly apart. Releasing the securing mechanisms causes the subassembly to pop partially out of the chassis.
In general, one of the mating connectors 20, 22, is spring-loaded as described in more detail below, and the other is directly attached (i.e., to the subassembly or to the chassis). In a preferred embodiment, shown in
In an alternative embodiment, the subassembly 18 has the spring-loaded panel connector and the chassis has the edge connector. Other embodiments can have a spring-loaded edge connector (whether attached to the subassembly or to the chassis), while the panel connector is immovable attached (to the other enclosure portion). In general, either mating connector can be of any type, e.g., male, female, right-angle, straight, edge, panel, etc., provided such the connectors can mate with each other in the course of inserting the subassembly into the chassis.
The subassembly 18 also includes a latch mechanism 26-1, 26-2 attached to each sidewall. Each latch mechanism 26-1, 26-2 projects through an opening 30-1, 30-2 in the respective sidewall. Coupled to each latch mechanism 26-1, 26-2 is a handle 32-1, 32-2, respectively, to enable a technician to unlock that latch mechanism and to pull the subassembly 18 from the chassis 14. The chassis 14 has a corresponding latch receiver region 34-1, 34-2 on each chassis sidewall for receiving a corresponding one of the latch mechanisms 26-1, 26-2 when the subassembly 18 is inserted into the chassis 14 as described herein.
The spring-loaded panel connector 20 also has a pair of shoulder screws 64-1, 64-2 (generally, 64). Each shoulder screw 64, also referred to as a standoff, has a head 66, a barrel portion 68, and a threaded portion 70. Each shoulder screw 64 enters one of the flange holes 62 from the front side 52 of the connector 20. Each hole 62 has a diameter for closely, but not snugly, receiving the barrel portion 68 of the shoulder screw 64: with the screw 64 passing through the hole 62, the connector body 50 can slide along a length the barrel portion 68. The size of the head 66 of the shoulder screw 64 is greater than the diameter of the hole 62 to restrain the connector body 50. The threaded portion 70 of each shoulder screw 64 enters and projects through a hole 72 in the structural member 25 mounted in the chassis 14. The holes 72 can be threaded for tightly receiving the threaded portions 70, or nuts (not shown) can be used on the opposite side of the structural member 25 to attach to the threaded portions of the screws. The diameter of the barrel portion 68 is greater than the diameter of the hole 72. Accordingly, the length of the barrel portion determines the approximate maximum distance of the connector body 50 from the structural member 25.
Each shoulder screw 64 passes through the center of a spring 74-1, 74-2 (generally, spring 74). The coils of the each spring 74 wrap around a section of the barrel portion 68 between the rear side 54 of the flange 60 and the structural member 25. One end of each spring 74 makes contact with the rear side of a flange and the other end of the spring makes contact with the front surface of the structural member 25.
For one embodiment of the tolerance-absorbing interconnect system, FIG. 5–
An advantage provided by the spring-loaded panel connector 20, movably anchored rather than rigidly mounted to the structural member 25′ by the shoulder screws, is that the panel connector 20 has some inherent “float” or relative movement. This relative movement allows for the connectors 20, 22 to mate easily without putting undo stress on either connector. For instance, the ability of the panel connector to move horizontally or vertically (in addition to back and forth along the direction of the shoulder screws) enables the panel connector 20 to adapt to any minor misalignment between the connectors 20, 22.
Preferably, the force needed to compress the springs is greater than the force needed to slide the edge connector 22 into the cavity 94 of the spring-loaded panel connector 20 so that the springs 74 can remain uncompressed as the edge connector 22 slides into the spring-loaded panel connector 20. In one embodiment, the force for mating the connectors 20, 22 is approximately 3 pounds of load, while the insertion force to start compressing the springs 74 is in a range of approximately 4 to 4½ pounds of load. Other spring rates can be used to practice the invention, although springs requiring too great a compression force can make manual insertion of the subassembly 18 into the chassis 14 difficult for a technician.
In
As shown in
When the subassembly 18 and chassis 14 are latched, the springs 74 are in a compressed state and, thus, urge the spring-loaded panel connector 20 against the edge connector 22. The shape of the latch mechanisms 26′ and manner of engagement with the latch-receiver regions 34′ prevent the force of the springs from pushing the subassembly 18 back out of the chassis 14. By urging each latch mechanism 26′ towards one end of the respective latch-receiver region 34′, the physical tolerances designed into the size of the latch receiving regions 34′ are absorbed. Further, the electrical contact between the mating connectors 20, 22 is improved and capable of withstanding vibration and shock to the electronic system 10 because the springs 74 urge the spring-loaded connector 20 against the edge connector 22 while the latch receiving regions 34 restrict the subassembly 18 and, thus, the edge connector 22 from moving.
When a technician disengages the latch mechanisms 26′, the force exerted by the springs 74 operates to pop the subassembly 18 partially from the chassis 14. This partial ejection of the subassembly 18 gives the technician a tactile indication that the subassembly 18 has become unlatched.
While the invention has been shown and described with reference to specific preferred embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the following claims. For example, in an embodiment described above, shoulder screws are movably coupled to the connector body and fixedly coupled to the structural member. An alternative embodiment can have the shoulder screws fixedly coupled to the connector body and movably coupled to the structural member. As another example, in an embodiment described above, the spring-loaded connector is embodied in the chassis and the mating connector in the sliding assembly. An alternative embodiment can have the spring-loaded connector in the sliding assembly and the mating connector fixed inside the chassis. As still another example, the principles of the invention may be applied to different types of connectors other than the electrical connectors described herein.
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