Apparatus and Method for Coupling Support Members

The present invention relates to connectors for tubular structural members.

Swings, other juvenile products such as playpens and strollers, and other products that use metal tubes as structural elements are commonly packaged with some or all of the tubes separated to minimize the size of the package, and are assembled by the end user. A common technique for joining two tubes end-to-end (along a common longitudinal axis) is to swage the end of one of the tubes (to reduce its diameter) and to sleeve the swaged end into the end of the other tube. The tubes are prevented from separating longitudinally by fixing a mechanical fastener to the mating ends of both tubes, typically by one of two techniques. The first technique involves drilling mating holes though one or both walls of both tubes and placing a fastener such as a screw (if holes are drilled through one wall) or a nut and bolt (if both walls are drilled) through the holes. This technique produces a connection that is generally highly resistant to relative axial and angular movement of the tubes. However, it requires the end user to use tools (screwdriver and/or wrenches) to fasten the tubes and makes it relatively inconvenient to disassemble and reassemble the tubes. The second technique again involves drilling mating holes through one wall of the tubes, and placing a spring-loaded button inside the swaged tube and protruding through the hole in the swaged tube. When the other tube is sleeved onto the swaged tube and the hole in that tube aligned with the button, the button springs into the hole, fastening the tubes. Although this allows assembly without tools and permits ready disassembly and reassembly (by pressing the button radially inwardly into the swaged tube to clear the hole in the other tube and pulling the tube free), the connection is not as resistant to relative movement of the tubes as is the first technique. This is because the holes must be formed slightly larger than the outside diameter of the button to ensure that the button can freely move through the holes. The slight relative axial movement allowed by this connection technique is usually not problematic. However, the relative angular movement is problematic in situations where either or both tubes are connected to structure that is substantially spaced from the tubes' common longitudinal axis and that relies on angular registry of the tubes for proper relative positioning. In such situations, a slight relative angular movement at the joint can translate to substantial mispositioning of the related structures. A joint that is easily assembled and disassembled without tools yet which provides good resistance to relative angular movement of the connected tubes would therefore be desirable.

The drawbacks of the connection devices that are known are overcome by the present invention which provides for ease in joining two tubes together without requiring tools and which is highly resistant to relative rotational movement of the two tubes. Through the use of the present invention, structure supported by the connected tubes is rigidly positioned and will not be subject to mispositioning due to relative rotational movement of the tubes.

In accordance with the present invention, a tube with a swaged end of smaller diameter that is to be joined to a second tube with a larger diameter contains an interconnection member disposed within the swaged end of the tube for connecting the two tubes. The interconnection member is a button that is spring-biased to extend through a hole in the swaged tube. The end of the swaged tube also includes two slots, disposed on opposing sides of the tube, that receive within them the shaft of a rivet that extends transversely through the larger diameter tube. As the swaged tube is inserted into the larger diameter tube, the button in the swaged tube springs into a corresponding hole in the larger diameter tube when the holes in the swaged tube and the large diameter tube are in alignment. The two tubes are thus coupled to prevent axial separation. Since the button loosely engages the holes in the two tubes, the tubes can rotate slightly relative to each other. To reduce the amount of possible relative rotational movement of the two tubes, the slots of the swaged tube receive the transversely extending rivet in the larger diameter tube. Because the slots and the rivet are sized for a tight fit, the possible relative rotational movement is very small, since, any rotational force that is applied to either tube will be resisted by the engagement of the rivet with the sides of the slots that are disposed on opposing sides of the swaged tube. Thus, relative rotational movement of the two tubes is closely controlled.

The present invention provides for both connection of two tubes to prevent axial disengagement and close control of relative rotational movement of the two tubes. This stable positioning of the two tubes is achieved by a relatively simple joint that provides for easy assembly and disassembly of the tubes without tools.

FIG. 1 is a perspective view of the joint as used in the context of a leg of an infant swing.

FIG. 2 is an exploded perspective view of the joint of FIG. 1.

FIG. 3 is a side elevational view of the two support members of FIG. 1.

FIG. 4 is a side elevational view of the joint of FIG. 1

FIG. 5 is a cross-sectional view of the joint of FIG. 1 taken along line 5--5 of FIG. 4.

A joint embodying the principles of the present invention is illustrated in FIG. 1 in the context of an infant swing. The swing has angled, C-shaped legs that are subjected to torque about the axis of the vertical portion of the leg. In the swing shown, the legs are constructed with lower and upper tubular leg sections 100, 200 joined at a joint 10. Since the swing is shown only to illustrate an application for the joint of the invention, in the remainder of the application, the leg sections are referred to as first and second support members 100, 200.

As shown in FIG. 2, joint 10 includes a first support member 100, second support member 200, connecting member 170, and rivet 240.

As best seen in FIGS. 2 and 3, the first support member 100 is an elongated, hollow bore, tube with a swaged joint end that has a large diameter first portion 160, a transitional second portion 140 of decreasing diameter, and a smaller diameter third portion 110. First portion 160 has an axially inner end 162 from which second portion 140 extends axially and radially inwardly to axially outer end 112 of third portion 110. (For definitional purposes herein, axial inner and outer directions are defined as toward and away from the joint ends of the support members, while radially inner and outer directions are defined as toward and away from the longitudinal axes of the support members individually or collectively when joined on a common axis.) Third portion 110 extends from axially outer end 112 to an axially inner edge 111A of support member 100.

The transition point between first portion 160 and second portion 140 defines shoulder 163. Second portion 140 and third portion 110, together extending a distance X.sub.1 from shoulder 163 comprise the swaged joint end 101 of support member 100.

Inner end 111 of third portion 110 includes radially opposed first and second elongated rivet slots 144 and 147. Rivet slots 144, 147 are cut into the wall of third portion 110 from inner edge 111A and extend longitudinally a distance X.sub.2 toward shoulder 163 to their axially outer ends 144C, 147C, respectively, which have a radius of curvature R.sub.1. Slots 144, 147 have a width W.sub.1 (twice R.sub.1). The slot outer ends 144C, 147C are positioned a distance X.sub.4 from shoulder 163.

Inner end 111 of third portion 110 further includes circular button aperture 142, which is a circular opening in the wall of third portion 110 disposed axially outwardly of, and aligned axially with, slot 144, and has a diameter D.sub.3. The axially outer end of button aperture 142 is positioned a distance X.sub.3 from shoulder 163.

First portion 160 has an outside diameter OD.sub.1, while third portion 110 has an outside diameter OD.sub.2 and an inside diameter ID.sub.1.

As seen in FIG. 2, connecting member 170 includes V-shaped flat spring 174 and button 176 fixed at its radially inner end 178 to a first end 174A of spring 174. Button 176 has a cylindrical body portion 177 with diameter D.sub.4 and a radially outer end 179. Connecting member 170 is disposed within third portion 110 of support member 100 with second end 174B of spring 174 engaging the interior wall of third portion 110 and with spring 174 biasing outer end 179 of button 176 through button aperture 142. Diameter D.sub.4 of cylindrical body portion 177 is slightly smaller than diameter D.sub.3 of aperture 142 so that button 176 can extend through aperture 142.

Second support member 200 is a cylindrical tube that has a joint end 205 of uniform outside diameter OD.sub.3 and inside diameter ID.sub.2 and terminates at an axially inner end 202. Outside diameter OD.sub.3 of support member 200 and OD.sub.1 of first portion 160 of support member 100 are substantially the same, whereas inside diameter ID.sub.2 of inner end 202 is slightly greater than outside diameter OD.sub.2 of third portion 110, so that third portion 110 is slidably receivable in the inner bore of inner end 202.

Joint end 205 includes a button receiving aperture 210, which is an elongated hole that extends through the wall of joint end 205 and has a width W.sub.2 that is approximately equal to diameter D3 of button hole 142 (and thus slightly greater than the outside diameter D.sub.4 of button 176), and a length L.sub.1 substantially greater than width W.sub.2. The axially inner end 210C of aperture 210 is positioned a distance X.sub.3 from inner end 202 of joint end 205.

Joint end 205 also contains first and second radially opposed rivet receiving apertures 220, 221 axially aligned with aperture 210. A rivet 240 is positioned in apertures 220, 221. Rivet 240 has an elongated, cylindrical shaft 242 of diameter D.sub.5, that extends through joint end 205, transverse to its longitudinal axis, and into and through apertures 220, 221. Diameter D.sub.5 of shaft 242 is slightly smaller than width W.sub.1 of slots 144, 147 and the inside diameter of apertures 220, 221 so that shaft 242 can be securely received within slots 144, 147 and through apertures 220, 221. Each end 244, 246 of rivet 240 has a head 244A, 246A disposed on it that is positioned external of, and in firm engagement with, the outer surface of joint end 205 when rivet 240 is positioned through member 200. Rivet 240 is positioned with its axially inner edge spaced a distance X.sub.5 from inner end 202.

Aperture 210 of member 200 and slots 144, 147 of member 100 are elongated so that sufficient margin is provided for positioning button 176 within aperture 210 and rivet shaft 242 in slots 144, 147. This margin is required due to the swaging of member 100, which results in a relatively high degree of axial dimensional inaccuracy.

Joint 10 is shown in its engaged condition in FIGS. 4 and 5. When the joint is engaged, swaged joint end 101 of support member 100 is disposed inside joint end 205 of support member 200, and axially inner end 202 of member 200 is positioned adjacent to shoulder 163 of member 100. Button 176 is disposed in button apertures 142 and 210, and rivet shaft 242 is disposed in slots 144, 147.

Joint ends 101 and 205 are joined in the engaged state by axially aligning the joint ends so that the longitudinal centerlines of button 176 and button aperture 210 are in alignment. When button 176 and button aperture 210 are in alignment, slots 144, 147 are also properly oriented to receive rivet 240 within them. Button 176 is depressed into member 100 by applying a force to the button's outer end 179 sufficient to overcome the biasing force of spring 174 and is maintained in the depressed position while third portion 110 of member 100, with smaller outside diameter OD.sub.2, is inserted into joint end 205 of member 200, with larger inside diameter ID.sub.2. Joint end 101 is inserted into joint end 205 a distance X.sub.1 until end 202 of member 200 rests on shoulder 163.

When joint end 101 is inserted into joint end 205 in proper axial alignment and to distance X.sub.1, button aperture 142 will align with button receiving aperture 210, and spring 174 will urge button 176 radially outwardly to extend through aperture 210. Thus, connecting member 170 connects joint end 101 within joint end 205 to prevent axial separation.

As joint end 101 is inserted into joint end 205, in addition to connecting member 170 engaging joint end 205, first and second ends 244, 246 of rivet shaft 242 will enter and slide inside first and second rivet slots 144, 147, respectively.

Since button aperture 210 is substantially larger than button body portion 177, button 176 can move axially in button aperture 210. Similarly, rivet shaft 242 can move axially in slots 144, 147. Thus, joint ends 101 and 205 can move axially with respect to each other. However, relative rotational movement of the two joint ends is limited by the engagement of rivet shaft 242 with the sides of slots 144, 147. If a rotational force is applied to member 100 as shown in FIG. 4, left side 144B of slot 144, in fixed engagement with rivet 240, and left side 147B of slot 147 (not shown) in fixed engagement with rivet 240, will limit the relative rotational movement of support members 100 and 200. If a force is applied in the opposite direction, the right sides 144A, 147A of slots 144, 147, respectively, will interact with rivet 240 to prevent relative rotational movement. Since shaft 242 diameter D.sub.5 and slot width W.sub.1 can be adjusted to be very nearly the same (just sufficiently different to permit rivet shaft 242 to slide through slots 144,147), and their dimensions controlled to fairly close tolerances, close control over relative rotation can be achieved.

To disengage joint 10, button 176 is depressed radially inwardly until it withdraws from button aperture 210, and joint end 101 is then withdrawn axially from joint end 205.

In this manner, a joint is provided that allows for ease in connecting two support members without requiring the use of tools and that also prevents relative rotational movement of the support members.

Several variations on the disclosed embodiment are contemplated. Although rivet 240, disposed within second support member 200, and slots 144, 147 in first support member 100, are positioned in the same angular orientation as button apertures 142 and 210, they are not required to be. Rivet 240 and slots 144, 147 can be positioned in any angular orientation relative to apertures 142, 210. Additionally, rivet 240 is not required to extend completely through support member 200. Posts internal to support member 200, disposed on opposing internal sidewalls and positioned to be received within slots 144, 147, could also be utilized.

Connection member 170 is disclosed as spring 174 and button 176 disposed within support member 100, however, the connection member can be any number of different structures and can be positioned externally to the support members. For example, the connection member can be a cylindrical pin that is mounted on the outside of the larger diameter support member such that as the swaged member is inserted into the larger diameter member, the pin is inserted through corresponding holes in the two support members. The pin can be biased into an engagement position or can be secured in position through other structural means, namely, a cotter pin inserted through the end of a pin that would extend entirely through both support members.

Cylindrical tubes are disclosed as comprising support members 100 and 200 in the disclosed embodiment, however, the invention is not limited to cylindrical tubes. The joint is equally capable of being applied in the context where two rectangular, or other geometrically shaped, support members are required to be joined and securely positioned to prevent relative rotational movement.