Two-piece spring push with stress distribution features

A two-piece spring push includes a main body portion and a cap. The cap is attached to the main body portion through a locking member that is disposed within a slot in the main body. The main body also includes alignment features that are received by the cap. The cap may have a bump that extends into an opening of the main body to limit the movement of optical fibers inserted therein. A front face of the cap engages a portion of a housing of a fiber optic connector when assembled.

BACKGROUND OF THE INVENTION

Conventional MPO connectors have a two-piece spring push that includes a base piece or main body and a cap. SeeFIGS.1A and1B. Optical fibers are placed in a channel in the main body. A pair of posts in the front of the cap are slipped into horizontal receivers in the main body and the cap is rotated downward with the downward facing posts on the cap entering the upward facing receivers in the main body. Due to the tolerance of the posts relative to the receivers, this results in a marginal snap fit, which holds but could easily be pried apart, as shown inFIG.2. When connectorization is completed, the cap and the main body piece are covered by a crimp band as shown inFIG.3A. Typically, when proof load testing for this conventional MPO connector is conducted per Telcordia GR-1435 standard testing, there is a bending moment on the posts due to the 33 N proof load. This force pulls the posts from their receivers. The load then transfers to the crimp body portion of the main body, and since the stress is greater than the yield, causing the crimp body to be torn off. SeeFIG.3B.

Accordingly, there could be scenarios where an MPO connector with a conventional two-piece spring push in which the connector may malfunction, and/or may fail proof load testing. Thus, a more robust two-piece spring push has been designed that manages the stress on the two-piece spring push.

SUMMARY OF THE INVENTION

According to one aspect, the present invention is directed to a two-piece spring push for use with a fiber optic connector that includes a main body, the main body having a front end, a back end, and a middle portion disposed therebetween, the front end comprising two generally parallel extensions extending from the middle portion and having an opening therebetween, the back end forming at least a portion of a cylinder and a cap configured to mate with the main body, the cap having a front face and a locking member, the locking member disposed forward of the front face and forming a gap between the locking member and the cap, the locking member engaging at least a portion of the middle portion of the main body, the cap and the main body forming an opening through at least a portion of the spring push.

In some embodiments, the locking member is attached to a forward facing surface of the front face, the main body has at least two alignment features to align the cap with the main body.

In some embodiments, the forward facing surface of the front face is a first forward facing surface and the cap has a second forward facing surface defining at least a portion of the gap.

In some embodiments, the locking member only extends across a portion of the front face of the cap.

In some embodiments, the at least two alignment features include two posts, the two posts being disposed in the gap between the second forward facing surface and the locking member when the cap and the main body are mated to one another.

In some embodiments, at least a portion of the locking member is disposed within an opening in a housing of a fiber optic connector when the fiber optic connector is fully assembled.

In yet another aspect, there is a fiber optic connector that includes a connector housing having a back end, a front end, and an opening extending therebetween, a ferrule disposed within the opening at the front end and configured to support at least two optical fibers of the fiber optic connector, and a spring push, the spring push disposed within a portion of the opening at the back end of the connector housing and engaging a spring positioned between the ferrule and the spring push, the spring push having a main body and a cap in a mated position, wherein at least a portion of the cap is within the opening of the connector housing in the mated position.

In some embodiments, the main body has a front end, a back end, and a middle portion disposed therebetween, and the cap has a front face and a locking member, the locking member disposed forward of the front face and forming a gap between the locking member and the cap to engage at least a portion of the middle portion of the main body.

In yet another aspect, there is a spring push for use with a fiber optic connector that includes a main body, the main body having a front end, a back end, and a middle portion disposed therebetween, the front end comprising two generally parallel extensions extending from the middle portion and having an opening therebetween, the back end forming at least a portion of a cylinder, and a cap configured to mate with the main body, the cap having a front face and a locking member, the locking member disposed forward of the front face, the locking member engaging at least a portion of the middle portion of the main body, wherein the cap and the main body form an opening through at least a portion of the spring push.

In some embodiments, the locking member is a forward-most component of the cap.

In some embodiments, the locking member further comprises a bridge portion joining two separate extensions and forming a gap between the cap and the locking member.

DETAILED DESCRIPTION OF THE INVENTION

Illustrated inFIGS.1A and1Bis a prior art spring push. It is similar to the one that is the subject of U.S. Pat. No. 8,684,611 assigned to the same Assignee as the present application, and the contents thereof are incorporated by reference herein. The spring push100has a main body102with a front end104, a back end106, and a middle portion108. The front end104has two parallel extensions110extending from the middle portion108. The two parallel extensions110define an opening112therebetween. The back end106forms at least a portion of a cylinder. The spring push100also has a cap120that is configured to mate with the main body102, the cap120has two projections122that engage two receptacles124in the middle portion108of the main body102. The cap120also has two projections126that engage two openings128in the back end106of the main body102. The main body102has a shoulder130and, together with a forward facing surface132on the cap120, forms a surface that surrounds the spring push100and prevents the spring push100from entering into a fiber optic connector300and the connector housing302in particular. As illustrated inFIG.2, the spring push100is being inserted into the connector housing302and will be inserted until the shoulder130and the forward facing surface132engage a rear facing surface304of the connector housing302as shown inFIG.3A. It should be noted that the cap120does not enter into the connector housing302, and is thus outside the connector housing302.

FIG.3Billustrates the prior art spring push100with a crimp band306that engages both the main body102and the cap120. If a sufficient force is applied to the crimp band306or the back end of the spring push100(in this example, from the top), the spring push100may deform and the cap120can separate from the main body102amounting to a failure of the spring push100. InFIG.3B, the cap120can be seen detaching from the main body102under vertical forces F.

Applicant notes that the term “front” or “forward” means that direction where the fiber optic ferrule or the optical connector would meet with another fiber optic ferrule or device (such as another connector having another spring push), while the term “rear” or “rearward” is used to mean the direction from which the optical fibers enter into the fiber-optic ferrule or fiber optic connector. In the present application, the spring push100will therefore have a front and a rear, the front will be inserted into the connector housing302first. Thus, inFIG.2, the “front” of the spring push100is on the right side the figure and pointing into the figure. The “rear” or “back” is that part of the spring push100is on the left side of the page and “rearward” and “backward” is toward the left and out of the page. The same is true of spring push200with respect toFIGS.4and5.

Turning now to one embodiment of the claimed spring push200, the spring push200has a main body202with a front end204, a back end206, and a middle portion208. The front end204has two parallel extensions210extending from the middle portion208. The two parallel extensions210define an opening212therebetween. The back end206forms at least a portion of a cylinder that is in communication through the middle portion208with the opening212. The main body202includes a slot214that extends across the main body202, and is located between the middle portion208and the front end204—and between the two parallel extensions210in particular. Extending upward from the main body202and adjacent the slot214within the middle portion208are two alignment features216, the features and functions of which are discussed below. Preferably, the alignment features216are two posts. The posts216have a space218between them to allow for optical fibers (not shown) to be inserted from the top of the main body202, through the space218and into the opening212and the portion of the cylinder at the back end206. The posts216are illustrated as rectangular projections but could take other shapes as desired.

The spring push200also has a cap220that is configured to mate with the main body202. The cap220is shown as a separate piece from the main body202. However, in some alternative aspects of this disclosure, the cap220may be rotatably attached to the main body permanently, for example, at the portion of the cylinder. In that case, the cap220can move between mated and unmated conditions with the main body202by rotating between the two positions. Yet alternatively, instead of rotation, a translational or sliding motion may open or close the part of the opening212that is formed within the portion of the cylinder at the back end206. The cap220has a front face222and locking member224that extends forward of the front face222—and preferably beyond all other portions of the cap220. The locking member224extends away from the front face222by way of two extensions226. The extensions226could be located in other positions on the cap220and there may also be fewer or more extensions for the locking member224. It is also noted that the front face222has a first forward facing surface228. There is a second forward facing surface230on the cap220—seeFIGS.6and7. There is a gap232that is formed between the locking member224and the rest of the cap220. The gap232is a result of space between the locking member224and the second forward facing surface230. However, there may also be another smaller space or gap234between the locking member224and the cap220at the top of the locking member224. SeeFIGS.4,6,7, and13.

While the locking member224is illustrated as extending from one side of the cap220to the other, the locking member224does not need to extend all the way across the cap220. See, e.g.,FIG.15and the discussion below. There could, for example, be a portion of the locking member224on each of the extensions226and they could extend toward one another. Alternatively, the locking member may only extend from one side of the cap220.

When the main body202and the cap220are mated to one another, there is an enclosed opening218athrough the spring push200to allow the optical fibers to pass therethrough. Looking atFIG.5in particular, one can see that the optical fibers could pass through the opening212and the space218and out the cylindrical back end206. See alsoFIG.14. There may also be a bump or extension240that extends downward from the cap220into the gap232to help limit the movement of the optical fibers. There is still sufficient area in the space218for the optical fibers to be positioned without crushing, pinching, or otherwise affecting them once inserted into the spring push100and the cap installed on the main body202.

The cap220has two projections242that engage two recesses244in the back end206of the main body202. The cooperation of the recesses244and the projections242keep the back end206of the main body202with the back end246of the cap220. The two back ends of the main body and the cap220combine to form a cylindrical structure that accepts a crimp band, such as the crimp band248as illustrated inFIG.9. The back ends206,248may have a configuration other than cylindrical, such as polygonal, oval, etc.

When the cap220is attached to the main body202, there are three main areas of engagement between and the alignment of the cap220and the main body202. The first area is the locking member224being inserted into the slot214. SeeFIG.7. The second area is where the posts216are received into the gap232and possibly into space or gap234that is located between the locking member224and the cap220. The bump or extension240extends into the space218fixing the location of the cap220on the main body202. Finally, the two projections242engage two recesses244in the back end206of the main body102.

The main body202has a shoulder250and, together with a forward facing surface228on the cap220, forms a surface that surrounds the spring push200that prevents the spring push200from being inserted into the connector housing too far. As noted above and in more detail below, some of the strength of the spring push200is that a portion of the cap220is inserted into the connector housing302of a fiber optic connector300. InFIG.8, there is illustrated a fiber optic connector300that has a connector housing302and a fiber optic ferrule or fiber support structure308. There may also be other components within the fiber optic connector300that are not visible. For example, there may be a pin-keeper; springs, etc. The fiber optic ferrule308is illustrated as an MTP® brand connector fiber optic ferrule, but it could take other forms that cooperate with the spring push200. The fiber optic ferrule308supports the optical fibers that are passed through the spring push200.

FIGS.8-11illustrate the spring push200with respect to the fiber optic connector300. InFIG.8, the spring push200is being inserted into the connector housing302. InFIG.9, the spring push200has been inserted into the back end of the connector housing302, such that the shoulder250of the spring push200is engaging the rear facing surface304of the connector housing302. The fiber optic ferrule308has been removed from the figure.FIG.10is a cross-section of the fiber optic connector300inFIG.9. In this figure, the locking member224(and a portion of one of the extensions226) within the connector housing302. The first forward facing surface228and the shoulder250are engaging the rear facing surface304.FIG.11is of the same configuration, but the section is closer to the center of the spring push220and shows the posts216having been received within the gap232. The locking member224is also shown within the connector housing302. The locking member224engages the inside surface of the connector housing302, thereby the main body202and the cap220are trapped together inside the connector housing unlike in the prior art. When a force is applied to the back end of the spring push200, the load is transferred to the alignment posts216by the locking member224rather than creating a bending moment on the crimp body206. This is illustrated inFIG.14by the presence of stress in the locking member224as it is stretched against the alignment posts206—This prevents the main body202and the cap220from separating like in the prior art (see,FIG.3B). At least a portion of the stress that is applied to the spring push200is transferred to the connector housing302.

As noted above, the locking member need not traverse the width of the cap220in a transverse direction. It will be appreciated by one of ordinary skill in view of this disclosure that the first forward facing surface228and the second forward facing surface230may be merged such that only the second forward facing surface230exists, from which the locking member224extends forwardly.

As illustrated inFIG.15, there is an alternative embodiment of a cap220′. The cap220′ has a front face222′ and two portions of a locking member224′ that extend forward of the front face222′—and preferably beyond all other portions of the cap220′ in a forward direction. The locking member224′ extends away from the front face222′ by way of two extensions226′. The extensions226′ could be located in other positions on the cap220′ and there may also be fewer or more extensions for the locking member224′. There is a second forward facing surface230′ on the cap220′. The second forward facing surface230′ is located where the portion of the cylinder ends in a forward direction, behind a bump240′. There is a gap232′ that is formed between the locking member224′ and the cap220′. The bump or extension240′ that extends downward from the cap220′ into the gap232′ to help limit the movement of the optical fibers. The cap220′ has two projections242′ that engage two recesses244in the back end206of the main body202. It will be appreciated by one of ordinary skill in view of this disclosure that the front face222′ and the second forward facing surface230′ may be merged such that only the second forward facing surface230′ exists, from which the locking member224′ extends forwardly.