Abstract:
A foldable push chair having two side frames, each side frame having a forward strut and a rear strut attached at its uppermost end to the forward strut, and a base strut linking the rear and forward struts, wherein the forward strut has an upper section and a lower section, pivotally connected by a connection. The connection allows the upper section and lower section to pivot relative to each other, between a folded state and an unfolded state, the upper and lower sections being parallel and co-linear when the push chair is in the unfolded state.

Description:
FIELD OF THE INVENTION 
   The present invention relates to push chairs for children, and in particular push chairs which can be folded for storage. 
   BACKGROUND OF THE INVENTION 
   The conventional construction of a push chair consists of two A frames linked by cross struts and having a seat located between them. Each of the two feet of each A frame has a wheel attached; one of the sloping sides of each A frame is extended at its upper end to form handle means by which the push chair can be pushed; and one of the three sides of the A frame (usually the side which extends to the handle) is hinged so that the buggy can be folded up eg. for storage. In some designs of push chair, the two A frames can also be collapsed together—this is commonly termed an umbrella fold. 
   SUMMARY OF THE INVENTION 
   According to the invention, there is provided a foldable push chair having two side frames, each side frame having a forward strut means and a rear strut means attached at its uppermost end to the forward strut means, and base strut means linking the rear and forward strut means, wherein the forward strut means comprises an upper section and a lower section, pivotally connected by connection means, the connection means allowing the upper section and lower section to pivot relative to each other, between a folded state and an unfolded state, the upper and lower sections being parallel and co-linear when the push chair is in the unfolded state. 
   According to another aspect of the invention, there is provided a foldable push chair having two side frames, each side frame having a forward strut means and a rear strut means attached at its uppermost end to the forward strut means, and base strut means linking the rear and forward strut means, wherein the forward strut means comprises an upper section and a lower section, pivotally connected by connection means, the connection means allowing the upper section and lower section to pivot relative to each other, between a folded state and an unfolded state, the connection means including attachment means for attachment of a hood, shade, or other accessory. 
   According to another aspect of the invention, there is provided a connection member for a push chair comprising an upper section and a lower section, pivotally connected by connection means, the connection means allowing the upper section and the lower section to pivot relative to each other, between a folded and an unfolded state, the upper and lower sections being parallel and co-linear when the push chair is in the unfolded state. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A push chair embodying the invention will now be described, by way of example, without limitation to the scope of the invention, and with reference to the drawings, in which: 
       FIG. 1  is a diagrammatic side view of the main structural components of a push chair; 
       FIG. 2  shows a perspective view of the hinge assembly in the folded arrangement; 
       FIG. 3  shows a perspective view of the hinge assembly in the unfolded arrangement; 
       FIG. 4  shows an exploded view of the hinge assembly; 
       FIG. 5  shows a cross-sectional view of the hinge assembly in the unfolded arrangement; 
       FIG. 6  is a diagrammatic side view of the a push chair with a hood attached; 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  is a simplified side view of a basic umbrella push chair, showing the A frame. The push chair comprises two A frames, one on each side, linked by cross struts. The frame can be locked in the configuration shown in  FIG. 1  (the unfolded position) by means of a standard “music stand” arrangement at the rear of the push chair frame. 
   Each A frame consists of a front sloping bar  10 , a rear sloping bar  11 , and a bottom bar  12 . The front and rear bars  10  and  11  have wheels  13  and  14  attached to their lower ends, as shown. The front bar  10  is also extended and curved at its upper end to provide a handle  19 , which may consist of a suitable termination of the bar or of a cross-bar between the two A frames, which is able to collapse together as the push chair is folded. 
   The bars  10 - 12  are attached to each other by hinged pivots  15 - 17  as shown. In addition, the front bar  10  has a hinge  18  located roughly midway between the pivots  15  and  17 . The front bar  10  is made up of two separate bars, the upper front bar  10 A and the lower front bar  10 B, which are pivotally connected by the hinge  18 . When the frame is locked in the unfolded position, the hinge  18  is held in the position shown in  FIG. 1 , with the bar  10  straight. When the frame is folded, the upper front bar  10 A and lower front bar  10 B pivot about the hinge  18 , allowing the front bar  10  to fold inward as indicated by arrow  19 , to collapse the frame. This allows the push chair to be folded into a compact form for storage (the folded position). The cross-bars and other elements may be lockably hinged so that the push chair can be folded by having its two A frames pushed together as well as by the folding of the individual A frames. 
   In conventional push chairs, bars  10 A and  10 B are jointed in such a way that the ends of bars  10 A and  10 B are overlapping, resulting in the ends of the bars protruding from the frame. It is easy for clothes to become caught or snagged on the ends of the bars. 
     FIG. 2  shows the connection hinge  18  in the folded arrangement, for storage of the push chair. In this arrangement, the upper and lower bars,  10 A and  10 B, are arranged such that they are approximately at right angles to the long axis of the hinge AA and the bars are substantially parallel and adjacent to each other. In the folded arrangement, the push chair handles nestle in the push chair wheels, such that the upper and lower bars  10 A and  10 B are each at an angle to the axis of the hinge AA of just over 90°. In the folded arrangement, the folded seat is retained in the space between the bars  10 A and  10 B. The upper front bar  10 A and lower front bar  10 B are each pivotally connected to the hinge by pins  50 . 
     FIG. 3  shows the connection hinge  18  in the unfolded arrangement, for when the push chair is in use. In the unfolded arrangement the upper and lower bars,  10 A and  10 B, are lined up with each other, the angle between the two bars being 180°. 
     FIG. 4  shows an exploded view of the hinge assembly. The hinge body  18  comprises a central part  23  of roughly uniform circular or elliptical cross-section and two planar parts  22  extending away from the central part in opposite directions along the long axis of the hinge AA. The two planar parts  22  are of thickness t. The planar parts are arranged end to end and parallel to each other, with the central portion  23  between. The planar parts  22  extend away from the centre of each end face  26  of the central part  23 . There is a hole  24  extending through each of the planar parts  22 , transverse to the long axis of the hinge, through which a pin  50  is inserted to pivotally attach the bars,  10 A or  10 B. The end faces  26  of the central part are concavely curved surfaces, and correspond to the curved ends  32  of the bars  10 A and  10 B. 
   There is a notch  28  in the top corner of each of the planar parts  22 , leaving a flat face  27 , parallel with the top face of the hinge and a convexly curved portion  25 , perpendicular to the top face of the hinge. 
     FIG. 4  shows the upper and lower bars  10 A and  10 B, detached from the hinge  18 . There is a groove  30  in the hinge-engaging end of each bar. The width of the groove  30  is just greater than the thickness t of the planer extensions of the hinge  22 , so that the planar parts  22  can be inserted in the groove  30  of each bar. There is a hole  31  in each of the groove walls. Each bar is placed on the hinge, such that the planar part of the hinge  22  rests in the groove of the bar  30  and a pin  50  is inserted through the holes  31  and hole  24 , to pivotally attach each bar to the hinge, allowing each bar to pivot about its pin. Wear plates  33  are positioned between the planar parts of the hinge and the groove walls. The wear plates  33  are made of plastic and act to protect the hinge body  18  from being scratched by the groove walls, and to allow the bars to pivot more smoothly against the hinge body. Each plate is the same shape as the planar body  22  and has a hole  34 , which corresponds to the hole  24  in the hinge body. 
   The hinge-engaging end of the bar is rounded such that it has two convexly curved faces  32 , which correspond with the concavely curved end surfaces  26  of the central part of the hinge and therefore the bars fit flush with the concavely curved surfaces  26  when the hinge assembly is in the unfolded position (see  FIG. 5 ). When the hinge assembly is in the unfolded state, the gap between the convex faces  32  of the bars  10 A and  10 B and the corresponding concave surfaces  26  of the hinge is such that there is no finger trap between each bar and the hinge. The gap between the convex face  32  of bar  10 A or  10 B and the concave face  26  of the hinge should not be more than 5 mm, so that there is no finger trap between each bar and the hinge. 
   When the bars are attached to the hinge body, each bar can pivot about its pin in a single plane, thus acting like a knee joint. The bars can pivot between the folded arrangement, as shown in  FIG. 2 , for when the push chair is to be stored, and the unfolded arrangement, as shown in  FIG. 3 , for when the push chair is in use. 
   Referring to  FIG. 5 , showing the bars and hinge in the unfolded position, the bars  10 A and  10 B extend away from the hinge body end to end, with the central part of the hinge  23  in between. Each of the bars can pivot from the folded position, through approximately 90° to the unfolded position, but the bars are blocked from any further rotation by the notches  28  at each end of the hinge. The base of the groove  30  in the end of each bar is stepped, so that it fits flush against the notch in the end of the hinge. When the bar has been pivoted fully to the unfolded position, the stepped surface  40  of each bar engages with the flat surface of each notch  27 , blocking each bar from rotating any further than 90° from the folded position. The base of the groove has two curved surfaces  41  and  42 , which fit flush against the distal end of the hinge body and ensure that the bar can be pivoted smoothly from the unfolded position to the folded position and vice versa. 
   When the hinge is fully open, the bars  10 A and  10 B are aligned end to end, forming a straight line, with the hinge in between. Referring to  FIG. 3 , when the hinge assembly is in the unfolded position, the bars  10 A and  10 B each engage flush with the hinge, so that the hinge assembly has no extending open ends which clothes could get caught on and there are no finger traps between the ends of the bars and the hinge, for clothes or people&#39;s fingers to get trapped in. The hinge-engaging ends of the upper and lower front bars  10 A and  10 B are spaced apart from each other by the central part of the hinge  23 . When the push chair is in the folded state the folded seat fabric is retained in the space formed between the two bars  10 A and  10 B. 
   Referring to  FIG. 3 , the central part of the hinge  23  has a hole  60  which passes through the centre of the hinge body, perpendicular to the plane of rotation of the joint. This hole can be used to attach a push chair hood to the frame. Referring to  FIG. 6 , showing a hood  61  attached to a push chair frame, a pin can be inserted through the hood and holes  60 , to pivotally attach the bottom corners of the hood to the push chair frame. The top of the hood can be attached to the top of the seat. The hood can then be rotated between the in-use position as shown in  FIG. 6 , to a storage position, where it is pushed back against the seat, as shown by the arrow in  FIG. 6 . As the hood is pushed back against the seat, the material of the hood concertinas, so that the hood folds up and out of the way. 
   The foldable push chair may include a suitable locking means for locking the push chair in the unfolded state, and preventing it from collapsing when load is placed in the seat. 
   Although the disclosed joint has been described in relation to a push chair having an umbrella fold, it will be apparent that it can be applied to any type of push chair fold. 
   Alternative embodiments using the principles disclosed will suggest themselves to those skilled in the art upon studying the foregoing description and the drawings. It is intended that such alternatives are included within the scope of the invention, which is limited only by the claims.