Abstract:
A child push chair frame, such as a child push chair sports frame, buggy frame or similar vehicle frame for children, includes two rear wheels, at least one front wheel, and a pusher for pushing the child push chair frame. The child push chair frame may also include stabilizing struts that are foldable from a spread-apart travelling position into a fully folded-together transportation position and vice versa, and are latchable between these two positions and at least one further position, such as a parking position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of German Patent Application Nos. 10 2014 108 428.4 filed Jun. 16, 2014 and 10 2014 110 215.0 filed Jul. 21, 2014, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Disclosed herein are a child push chair frame, in particular a child push chair sports frame, buggy frame or similar vehicle frame for children, and a child push chair. 
     BACKGROUND 
     Child push chair frames of the type addressed herein, particularly child push chair sports frames, buggies or similar vehicles for children have long been known and serve for the practical transport of babies and small children. A frequent problem with the known child push chair frames is the space requirement in the non-operational state. In particular for transportation, child push chair frames must be folded to be as small as possible and the conversion of the child push chair frame is to be as easy for a user as possible. Many known child push chair frames are difficult to manipulate with regard to the conversion from a travelling position into a transportation position and enable conversion of the child push chair frame only into a single non-operational state. 
     SUMMARY 
     Embodiments disclosed herein provide an improved child push chair frame which can be manipulated and converted particularly easily and flexibly by a user. 
     The child push chair frame disclosed herein comprises two rear wheels and at least one front wheel and a pusher to push the child push chair frame and fastening means for fastening a child push chair upper part. It is significant that the rear wheels and the at least one front wheel and/or the rotary axles thereof are each connected to one another by means of one or more rear and front stabilizing struts in articulated manner about a central axis which extends approximately parallel to the common rotary axle of the rear wheels such that said stabilizing struts are foldable from a spread-apart travelling position into a fully folded-together transportation position and vice versa, and are latchable between these two positions in at least one further position, in particular a parking position. 
     An essential feature is that the child push chair frame can be converted from a travelling position into a transportation position. In the transportation position, the child push chair frame has an end stop which, if desired, can be combined with a further locked and/or arrested state. Alternatively, the transportation position is not arrested, which advantageously enables rapid unfolding of the child push chair frame into the travelling position. In the parking position, which is situated, with regard to the folding position thereof, between the folding position of the child push chair frame in the travelling position and the folding position of the child push chair frame in the transportation position, the child push chair frame is lockable, wherein the child push chair frame in the parking position has a locking and/or arresting mechanism which is actuatable as desired on folding the child push chair frame. 
     In this way, the child push chair frame can be displaced from a travelling position into a fully folded-together state suitable for transport. It is additionally possible to convert the child push chair frame into a parking position capable of standing up in which the child push chair frame has a small size and therefore has a small space requirement, but in which the child push chair frame can nevertheless stand independently. 
     Provided that the transport position is combined with a locking and/or arresting mechanism, as an optional embodiment provides, it is possible in the completely folded-together state of the child push chair frame to extend the pusher in order to pull or push the child push chair together with the child push chair upper part on the two rear wheels. According to this embodiment, the stabilizing struts are latchable, aside from the travelling position, also in the fully folded-together transportation position. This option comes into consideration particularly if the child push chair is to be used on difficult, particularly uneven, surfaces. 
     According to another embodiment, the child push chair frame has a locking position or a locked and/or arrested state in the travelling position, wherein the spread-apart travelling position of the stabilizing struts can be fixed by means of an articulated connection between the rear and the front stabilizing struts. It is ensured with this advantageous embodiment that the spread-apart travelling position is maintained not only due to gravity when the stabilizing struts and the rear wheels and the at least one front wheel slide or roll, under the effect of gravity, into the fully spread-apart travelling position, but also when the child push chair frame is, for example, lifted up in order to lift it, for example, over a stair tread. 
     Embodiments also provide that the stabilizing struts can also be fixed in the fully folded-together transportation position and/or in the at least one further position, in particular parking position, by means of the articulated connection between the rear and the front stabilizing struts and, if necessary, unlatched. 
     Advantageously, the articulated connection therefore serves as a multifunctional latching and unlatching unit with which the folding functionality of the child push chair frame can be actuated. 
     Furthermore, the conversion of the child push chair frame can be carried out particularly simply by means of an advantageous switching unit and a displacement of the pusher. 
     For the aforementioned purpose, it is advantageous if, firstly, the spread-apart travelling position of the stabilizing struts and, secondly, the at least two locking positions thereof can be fixed by means of the articulated connection between the rear and the front stabilizing struts. This takes place preferably by means of the aforementioned switching unit by means of which the articulated connection is switchable, in particular unlockable, from a fixing position into a releasing position and vice versa. 
     In one embodiment of the child push chair frame, each of the two rear wheels is connected to the at least one front wheel via a connecting piece. The connecting pieces are configured foldable such that they enable without restraint, or do not hinder, the folding together or folding apart of the rear and front stabilizing struts about the aforementioned articulated connection or the central axis defined thereby. 
     Advantageously, the connecting pieces have a joint at approximately half the distance between a rear wheel and a front wheel. By means of the joint, the folding ability of a connecting piece can be ensured. A foot actuating mechanism for initiating the folding process of the stabilizing struts and possibly also of the connecting pieces is preferably provided at a proximal end of a connecting piece. As soon as a user actuates the foot actuating mechanism and previously a latching mechanism of the switching unit has been released, the folding process of the connecting pieces can be initiated and the space requirement of the child push chair frame can consequently be significantly reduced. As an alternative to the foot actuating mechanism, a hand-operated initiation of the folding process can be provided by means of a cable pull or similar mechanism. The connecting pieces preferably form part of a basket receiving frame of the child push chair frame. Advantageously, the fastening means for fastening a child push chair upper part is arranged in the region of a central axle of the child push chair frame. 
     Advantageously, one or more rear stabilizing struts are provided between each rear wheel and the central axle of the child push chair frame and one or more front stabilizing struts are provided between each front wheel and the central axle. The stabilizing struts can serve to latch the folding mechanism of the connecting pieces or to release it. In the latched position, the stabilizing struts serve to provide the child push chair frame with a high degree of stability in the normal operational state. At the same time, the stabilizing struts serve as blocking elements which prevent folding-together of the child push chair frame by folding of the connecting pieces. Together with the connecting pieces, the front and rear stabilizing struts form an essentially triangular arrangement. 
     Preferably, the front and rear stabilizing struts each open into a switching unit in the region of the distal ends of the pusher. The switching unit comprises an actuating portion and a front and a rear bearing portion, wherein the actuating portion serves to accommodate a distal end of the pusher, the rear bearing portion serves to accommodate the proximal end of the rear stabilizing strut(s) and the front bearing portion serves to accommodate the proximal end of the front stabilizing strut(s). The front and rear bearing portion are advantageously arranged along the central axle directly adjoining one another. Therein, the central axle preferably connects the two switching units, each of which cooperates with a distal end of the U-shaped pusher. 
     Advantageously, in a normal operational state of the child push chair frame, the rear and the front bearing portion are non-rotatably connectable to one another. In order to initiate a folding process of the connecting pieces, however, the rear and the front bearing portion are rotatably connectable to one another. Switching over between a rotatable and a non-rotatable connection between the rear and the front bearing portion of a switching unit is advantageously achieved by means of a displacement of the pusher in the actuating portion of the respective switching unit. In this way, the non-rotatable connection between the rear and the front bearing portion can be released by a single one-handed operation of the pusher so that both the stabilizing struts can be rotated relative to one another about the central axle. In this operating state of the child push chair frame, folding of the connecting pieces between a front wheel and a rear wheel is also possible. A displacement of the pusher in the actuating portion preferably causes a displacement of an unlatching bolt along the central axle. Consequently, through the displacement of the unlatching bolt, the non-rotatable connection between the rear and the front bearing portion can be released. 
     The switching section is rigidly connected to the central axle and so is arranged non-rotatably. 
     According to one embodiment, the fastening means firmly connected to the front bearing portion for fastening a child push chair upper part comprise an elastically pre-tensioned locking bolt which corresponds with a locking recess arranged on the outer periphery of the rear bearing portion and, together with this locking recess, forms a “soft lock”. This locking mechanism defines the parking position of the child push chair frame in which the front and rear stabilizing struts are not fully folded together. 
     The switching unit also comprises a locking device, for example a locking pin which, in the spread-apart travelling position of the stabilizing struts, is situated within a locking recess. By means of an actuating pusher which is mounted longitudinally displaceable within the pusher receptacle, the locking pin can be moved out of the locking recess, specifically in a circular arc-shaped guide section and together with the pusher into an end position in which the front and rear stabilizing struts are fully folded together. Together with the pusher, the rear stabilizing struts are foldable in the direction toward the front stabilizing struts. The circular arc-shaped guide section is situated within the rear bearing portion connected to the rear stabilizing strut. 
     With the pusher fully driven in, the aforementioned actuating pushers can be moved by switching projections mounted thereon into the aforementioned unlatching or unlocking position. In this way, the switching unit can be unlatched by the pusher. 
     The circular arc-shaped guide section can have a locking recess shortly before the end stop in which the locking bolt can be introduced if needed, specifically by means of a spring force acting on the locking bolt. In this way, the parking position of the child push chair frame can be fixed. The unlatching is then carried out in the same way as the unlatching in the spread-apart travelling position of the child push chair frame. 
     According to an alternative embodiment of the switching unit, said switching unit comprises a displacement plate which has at one end one, preferably two, locking projections and/or at the opposite end, a further locking projection. These locking projections correspond with associated locking recesses on a switching disk of the switching unit. By means of the pusher, the aforementioned projections can be brought into an unlatching position. In this position, the switching disk can be rotated relative to the displacement plate until the one locking projection engages in a recess of a spring-loaded hook. In this position, the front and rear stabilizing struts are fully folded together and locked in the transportation position. For unlocking, the displacement plate is moved by means of the pusher into an unlatching position. The small latching projection then moves out of the associated recess on the locking hook, so that the switching disk can be turned back into the original position, specifically into a position in which the front and rear stabilizing struts are again fully spread apart. The displacement plate is movable against an elastic pre-tension out of the locking position. If desired, the switching unit according to the invention can also have one or more intermediate locking positions. 
     Another embodiment differentiates between a locking projection connected to the displacement plate and a pin-like projection guided within a circular arc-shaped guide section. This pin-like projection is configured to serve as a rotation stop and to bear transverse loads. In the end positions of the stop pin, the latching projection is transverse load-free. The latching projection therefore serves only to define the latching position in the fully spread-apart position of the stabilizing struts and does not bear any transverse loads, so that latching and particularly also unlatching can easily be carried out, and essentially without friction. 
     The switching unit is preferably actuatable by means of a displacement, in particular a sliding and/or rotary movement of the pusher. Advantageously, the actuating portion is mounted rotatable relative to the front and rear bearing portion of a switching unit. In this way, a rotary movement and blocking of the rotary position of the pusher is possible. 
     In order to achieve the aforementioned object, a child push chair having the features of claim  21  is also proposed. The child push chair comprises a child push chair frame and a child push chair upper part which can be, for example, a carrying shell, a high chair frame, a child car seat, a carry cot or other type of child push chair upper part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Following is a detailed description with reference to the drawings, in which: 
         FIG. 1  shows a perspective view of a child push chair frame according to the disclosure; 
         FIGS. 2 a -2 d    show a variety of operating states of the child push chair frame; 
         FIG. 3  shows a perspective view of a portion of the child push chair frame of  FIG. 1 ; 
         FIG. 4  shows an end face view of a partly opened switching unit of the child push chair frame; 
         FIG. 5  shows a perspective view of a partly opened switching unit of the child push chair frame; 
         FIG. 6  shows an end face view of a partly opened switching unit of the child push chair frame; 
         FIG. 7  shows a perspective view of a partly opened switching unit of the child push chair frame; 
         FIG. 8  shows an end face view of a partly opened switching unit of the child push chair frame; 
         FIG. 9  shows a perspective view of a partly opened switching unit of the child push chair frame; 
         FIG. 10  shows a perspective view of a partly opened switching unit of the child push chair frame; 
         FIG. 11  shows a perspective view of a foot actuating mechanism of the child push chair frame; 
         FIG. 12  shows a schematic representation of the switching unit; 
         FIG. 13  shows a schematic representation of the function/actuation of the switching unit; 
         FIGS. 14 a -14 e    show a schematic representation of an alternative switching unit in functional views, and 
         FIGS. 15 a -15 b    show a schematic representation of a partly opened alternative switching unit of a child push chair frame according to the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a perspective view of a child push chair frame  1  according to the disclosure. In the present embodiment, the child push chair frame  1  comprises two rear wheels  3  and  3 ′ which are rotatably connected to one another via a common rear axle  5 . The child push chair frame  1  further comprises two front wheels  7  and  7 ′ which, like the rear wheels  3 ,  3 ′ are also rotatably connected to one another via a common front axle  9 . Each rear wheel  3 ,  3 ′ is at least indirectly connected to an associated front wheel  7 ,  7 ′ by means of a connecting piece  11  or  11 ′. The connecting pieces  11  and  11 ′ can also be configured integrally in the form of a U-shaped, bow-shaped or rectangular strut design. 
     Thus, one connecting piece  11 ,  11 ′ is associated with each wheel pair. Relative to an imaginary central plane M of the child push chair frame  1 , the child push chair frame thus has a total of two connecting pieces  11 ,  11 ′, each of which connects a rear wheel  3  to a front wheel  7  or the front axle  9  and the rear axle  5 . In the event that only one front wheel is provided, two connecting pieces  11 ,  11 ′ connect the two rear wheels  3 ,  3 ′ to one and the same front wheel. 
     Each of the connecting pieces  11 ,  11 ′ comprises a joint  13  which is arranged essentially half way between the rear wheels  3 ,  3 ′ and the front wheels  7 ,  7 ′ and therefore effectively in the middle of the connecting pieces  11 ,  11 ′. A connecting piece  11 ,  11 ′ is thus preferably configured in two parts, both the parts being pivotably connected to one another via the joint  13 . 
     In order to bring about a pivot movement of the connecting piece  11 ,  11 ′ about a rotary axis D of the joint  13 , in the present embodiment of the invention, a foot actuating mechanism  15  is provided. With the help thereof, a user of the child push chair frame can effect a folding movement of the connecting piece  11 ,  11 ′ with a foot while initiating a rotary movement of the sections of the connecting piece  11 ,  11 ′ about the rotary axis D. The folding movement of the connecting piece  11 ,  11 ′ and, in particular, a displacement of the joint  13  takes place in the direction of the arrow R, so that the separation a between the front wheels  7 ,  7 ′ and the rear wheels  3 ,  3 ′ is reduced. The direction R in which the joint  13  moves during the folding process of the connecting piece  11 ,  11 ′ corresponds to a direction pointing away from the ground. 
     The child push chair frame  1  also comprises an essentially U-shaped pusher  17 , which is provided for pushing the child push chair frame  1  by a user. For this purpose, the pusher comprises a handle region  19  which has a height adjustment device  21 . The height adjustment device  21  can cooperate, for example, by means of a Bowden cable or similar mechanism. In particular, the height adjustment device  21  is actuated by means of a spring-mounted push button or similar mechanism. By means of the height adjustment device  21 , the pusher  17  can be displaced in the direction of the limb  23  of the U-shaped pusher  17  (see arrow with the reference sign  25 ). For this purpose, the distal ends  27  of the pusher  17  are guided in a pusher receptacle  29 , wherein the dimension of the height adjustment overall is delimited by clamping means  31  which are provided on the pusher receptacle  29 . Thus if the clamping means  31  are closed, the pusher  17  can only be displaced within certain limits in the direction of the arrow  25  in the pusher receptacle  29 . 
     The child push chair frame  1  further comprises a central axle  33  which essentially extends in the axial direction of the rear axle  5  or in the direction of the front axle  9  and thus essentially parallel to the rear axle and the front axle  9 . The length of the central axle  33  essentially matches the length of the rear and/or front axle.  FIG. 1  also makes clear that the central axle is arranged essentially half way between the rear axle  9  and the front axle  5  and thus essentially at the height of the joint  13 . In the height direction, however, there is a separation between the joint  13  and the central axis M. 
     The child push chair frame  1  also comprises fastening means  35 ,  35 ′ which are configured herein in the form of holding arms which extend essentially perpendicularly to the central axle  33  and are arranged at opposite ends of the central axle  33 . The fastening means  35 ,  35 ′ serve for receiving a child push chair upper part, in particular a carrying shell, a child pocket, a high chair frame, a child car seat or the like. Depending on the child push chair upper part that is to be mounted, the fastening means  35 ,  35 ′ can be differently designed or, particularly, exchangeable in the form of adapter elements on the child push chair frame  1 , for example by means of a dovetail guide. 
     The child push chair frame  1  also comprises stabilizing struts arranged between the axles, wherein between each front wheel  7 ,  7 ′ and the central axle  33  at least one, in the present case two, front stabilizing struts  37  are provided, whereas between the rear wheels  3 ,  3 ′ and the central axle  33 , in the present case two rear stabilizing struts  39  are provided on each side of the central plane M. On both sides of the central plane M, in the operational state of the child push chair frame  1  shown in  FIG. 1 , the stabilizing struts  37 ,  39  form an essentially triangular arrangement together with the connecting pieces  11 ,  11 ′. 
     In the region of the central axle  33 , the front stabilizing struts  37  open into a front bearing portion  41 , whereas the rear stabilizing struts open into a rear bearing portion  43 . In the present embodiment, the bearing portions  41 ,  43  are configured to be essentially cylindrical, each being arranged concentrically relative to the central axle  33 . Two bearing portions  41 ,  43  are arranged on each side of the central plane M of the child push chair frame  1 . The stabilizing struts can be, in particular, injection moulded, screwed, pushed or similar, into the bearing portions  41 ,  43 . The front and rear bearing portions  41 ,  43  are each arranged at the ends of the central axle  33 , wherein on each side of the central axle  33 , a rear bearing portion  43  is arranged, in the axial direction of the central axle  33 , directly adjoining a front bearing portion  41 , and the bearing portions  41 ,  43  consequently adjoin one another. The bearing portions  41 ,  43  therefore serve to accommodate the proximal ends of the stabilizing struts  37 ,  39 . The opposite distal ends of the stabilizing struts  37 ,  39 , however, are connected to the wheels or the associated axles, wherein the connection between the front stabilizing struts  37  and the front wheels  7 ,  7 ′ or the front axle  5  can be fixed, particularly immovably, whereas the connection between the rear stabilizing struts  39  and the rear wheels  3 ,  3 ′ or the rear axle  5  is preferably (rotatingly) movable. 
     The front and rear bearing portions  41 ,  43  are part of a switching unit  45  which is configured as a compact multi-part unit, wherein a switching unit  45  is arranged at each end of the central axle  33 . Apart from the bearing portions  41 ,  43 , each switching unit  45  comprises an actuating portion  47  which is arranged directly adjoining a bearing portion, in the present case, adjoining the rear bearing portion  43  along or on the central axle  33 . 
     The housing of the actuating portion  47  is connected to the pusher receptacle  29 . It is also conceivable for an integral connection to be provided between the pusher receptacle and the housing of the actuating portion  47 . The actuating portion  47  comprises a through opening (not shown in  FIG. 1 ), which is configured such that the limbs  23  and, in particular, the distal ends  27  of the pusher  17  can be displaced through the actuating portion  47  and can emerge at the opposite side of the actuating portion  47 , i.e. the side facing the ground. A displacement of the pusher  17  of this type in the direction of the arrow  25  is only possible, however, if the clamping means  31  are open and consequently, the restriction of the height adjustability of the pusher  17  is cancelled. In particular, the through opening can be configured integrally in the pusher receptacle  29 . 
     In a normal operational state of the child push chair frame  1  shown in  FIG. 1 , the rear bearing portion  43  and front bearing portion  41  are non-rotatably connected to one another. A corresponding non-rotatable connection is achieved by means of an associated operating state of the switching unit  45 , for example, by means of a locking or blocking connection between the two bearing portions  41 ,  43 . By means of a displacement of the pusher  17  in the actuating portion  47 , the non-rotatable connection between the bearing portions  41 ,  43  can be released. The fixed angular position of the stabilizing struts  37  and  39  relative to one another shown in  FIG. 1  has been released in this operating state of the switching unit  45 , so that a displacement of the joint  13  of the connecting pieces  11 ,  11 ′ in the direction R is also possible. During a corresponding movement of the joint  13 , the separation a between the front wheels  7 ,  7 ′ and the rear wheels  3 ,  3 ′ is simultaneously reduced, such that the child push chair frame  1  can be converted into a compact transportation state or a “stand-alone” state in which the child push chair frame  1  is capable of standing independently. 
       FIG. 1  also makes clear that the fastening means  35 ,  35 ′ are connected to the rear bearing portion  43 . As aforementioned, the connection can be made by means of a dovetail guide or a similar form-fitting connection, so that the fastening means are interchangeably mounted on the child push chair frame. Suitable means configured as a dovetail guide can be connected, particularly integrally, to the rear bearing portion  43 . Naturally, a corresponding connection to the front bearing portion  41  or another element of the child push chair frame  1  is also possible. 
     Once the limbs  23  of the pusher  17  have been introduced sufficiently far into the actuating portion  47 , not only is the non-rotatable connection between the rear and front bearing portion  41 ,  43  released, but the pusher  17  can then also be pivoted about the central axle  33  in the direction of the front wheels  7 ,  7 ′ and can latch in there in a suitable locking position. 
     In order to re-create the non-rotatable connection between the front bearing portion  41  and the rear bearing portion  43 , firstly, the pusher  17  must subsequently be displaced back into an original use position shown in  FIG. 1 . In order to enable a rotary movement of the pusher  17  about the central axle  33 , the actuating portion  47  is rotatably mounted relative to the bearing portions  41 ,  45  and relative to the central axle  33  at or on the central axle  33 . 
     The switching unit  45  consists overall of a compact unit which comprises three mutually separate elements, specifically the front bearing portion  41 , the rear bearing portion  43  and the actuating portion  47 , in order to ensure easy conversion of the child push chair frame  1 , for example, for transportation. The switching unit  45  can have at least two operating states between which switching is possible by a hand-operated displacement of the pusher  17 . In a first operating state of the switching unit  45 , a non-rotatable connection exists between the front and the rear bearing portion  41 ,  43 , whilst in the second operating state, a rotatable connection exists between the front and the rear bearing portion  41 ,  43 . 
       FIGS. 2 a -2 d    show the child push chair frame  1  in different operating states.  FIG. 2 a    shows the conventional operational state of the child push chair frame  1  shown in  FIG. 1  for conveying a baby or child with the aid of a child push chair upper part (not shown). 
       FIG. 2 b    shows the child push chair frame  1  in an operational state in which the limbs  23  of the pusher  17  in the released state of the clamping means  31  are guided through the actuating portion  47  and thus a non-rotatable connection between the front bearing portion  41  and the rear bearing portion  43  has been released. In this operating state, the stabilizing struts  37  and  39  are consequently mounted rotatable relative to one another about the central axle  33 . 
       FIG. 2 c    shows the child push chair frame  1  in a storage state capable of standing, in which, although the size of the child push chair frame  1  is significantly reduced, the child push chair frame  1  can still stand independently in that a small separation a is maintained between the rear wheels  3 ,  3 ′ and the front wheels  7 ,  7 ′. 
       FIG. 2 d    shows a further operating state of the child push chair frame  1  in which the connecting pieces  11 ,  11 ′ have been folded together to the maximum extent with the aid of the joint  13  so that the separation between the front wheels  7 ,  7 ′ and the rear wheels  3 ,  3 ′ is reduced to the maximum extent. In this position, the child push chair frame  1  cannot stand independently. However, it has an even smaller space requirement than the operating state shown in  FIG. 2 c   . In the operating state of  FIG. 2 d   , the pusher  17  must not necessarily be pushed through the actuating portion  47 . Rather, it is also conceivable to extend the pusher  17 , following folding together of the child push chair frame  1 , back to the normal operational state so that, as in the state shown in  FIG. 2 d   , a child push chair upper part (not shown) can be connected to the child push chair frame  1  and a user can push or pull the child push chair frame  1  on two wheels. This operational state is particularly advantageous if the child push chair is to be conveyed over rough terrain. Reduction of the child push chair frame  1  to two wheels is advantageous in this case and facilitates movement overall. 
       FIGS. 2 a -2 d    make clear that the present disclosure enables the production of a plurality of operational states of a single child push chair frame  1 . It is therefore also possible, aside from the operational state shown in  FIG. 2 c   , to achieve a minimum space requirement for the transportation of the child push chair frame  1 . At the same time, in the state shown in  FIG. 2 d   , by pulling or pushing on two wheels, the child push chair frame  1  can be used on difficult terrain. For each operating state, for simplified use, corresponding locking or arresting positions are provided. 
     The switching unit  45  which enables simple and flexible conversion of the child push chair frame  1  into the states shown in  FIGS. 2 a -2 d   , is described in greater detail below by reference to  FIGS. 3 to 10 . 
       FIG. 3  shows a perspective view of a portion of the child push chair frame  1  of  FIG. 1 . It is readily recognisable in  FIG. 3  that the fastening means  35 ,  35 ′ are connected to the switching unit  45 . Also indicated in  FIG. 3  is a child push chair upper part  49 , which is connected to the fastening means  35 ,  35 ′. Also recognisable is a through opening  51  which is arranged in the actuating portion  47 . In the event that a non-rotatable connection between the front bearing portion  41  and the rear bearing portion  43  is to be released, the pusher  17  (not shown in  FIG. 3 ) or the distal ends  27  thereof must be pushed through the through openings  51 . 
       FIG. 4  shows an end face view of the actuating portion  47 , wherein the cover  53  of the housing of the actuating portion  47  shown in  FIG. 3  has been removed. The figure makes clear that the pusher receptacle  29  extends into the actuating portion  47  and is held there with the aid of guide elements  55 . The guide elements  55  are preferably connected integrally with the pusher receptacle  29  and are held locally fixed in the actuating portion  47  by blocking elements  56 . 
       FIG. 5  shows a corresponding perspective representation without the housing of the actuating portion  47 . On the side facing toward the rear bearing portion  43 , the pusher receptacle  29  is at least partially open so that the (actuating) bolt  57  visible in  FIG. 6  can project into the interior of the pusher receptacle  29 . It is also clear that the through opening  51  is configured in the pusher receptacle  29 . 
       FIGS. 6 and 7  show an end face view and a perspective representation of the switching unit  45 , wherein for better clarity, the pusher receptacle  29  is not shown in the actuating portion  47 . The bolt  57  is essentially arranged centrally in the actuating portion  47  along the central axle  33  and is spring mounted therein. The distal end  59  of the bolt  57  is configured conically and extends, by means of a corresponding cut-out, into the pusher receptacle  29  (not shown in  FIGS. 6 and 7 ). 
     Due to the conical configuration of the distal end  59  of the bolt  57 , on displacement of the limb  23  of the pusher  17  sufficiently far into the pusher receptacle  29 , a displacement of the bolt  57  against the spring force can be brought about. Furthermore, the pusher  17  and, in particular, the limb  23  thereof cooperates with an elongate actuating element  61  which, on extension of the pusher  17  in the direction of the arrow  63 , also cooperates with a displacement plate  65 , the displacement of which is determined by guide elements  67 . The guide elements  67  are firmly installed in the actuating portion  47 . On displacement of the actuating element  61  in the direction of the arrow  63 , a displacement of the displacement plate  65  also takes place in the direction of the arrow  63 , wherein the displacement is carried out against a spring force of two spring elements  69 . 
     The bolt  57  extends through an elongate or oval through bore in the displacement plate  65  so that the bolt  57  extending through the displacement plate  65  does not block a movement of the displacement plate  65  in the direction of the arrow  63 . A displacement of the actuating element  61  in the direction of the arrow  63  takes place first on displacement of the pusher  17  sufficiently far in the pusher receptacle  29  with a clamping means  31  opened. 
       FIG. 8  shows another end face view of the switching unit  45 , wherein for reasons of clarity, the pusher receptacle  29  and the displacement plate  65  and further elements of the actuating portion  47  are not shown.  FIGS. 8 and 9  make clear that a circular disk element  71  is in contact with the rear bearing portion  43  and has two point-symmetrically arranged, circular sector-shaped grooves  73 ,  73 ′ at each end of which, in each case, a locking cut-out  75 ,  75 ′ is arranged. Furthermore, the circular disk element  71  is penetrated by the bolt  57 . 
     The actuating element  61  is connected to the bolt  77  which penetrates the circular disk element  71  and latches in a locking cut-out  75  through the force of the spring elements  69  which act on the displacement plate  65  (not shown in  FIGS. 8 and 9 ). On displacement of the actuating element  61  and a resulting displacement of the displacement plate  65  against the force of the spring elements  69 , the bolt  77  is introduced into the groove  73  or  73 ′. In this operating state, the pusher  17  can rotate along the groove  73  or  73 ′ about the bolt  57  until the opposite end of the groove  73 ,  73 ′ is reached. The bolt  77  then latches into the opposite locking cut-out  75 . In this operating state, the pusher  17  is latched such that the bolt  57  remains in its pushed-in position until the pusher  17  is rotated back into its original position. 
     The displacement of the bolt  47  along the central axle  33  causes, by means of a suitable mechanical apparatus, the release of a non-rotatable connection between the front bearing portion  41  and the rear bearing portion  43 . 
     An exemplary representation of a mechanism of this type is shown in  FIG. 10 . The drawing makes clear that on displacement of the bolt  57  against a spring (not shown in  FIG. 10 ), a driver element  79  is displaced in the direction of the central axle  33 , and said driver element acts against a blocking insert  81 . The blocking insert  81  is configured anchor-shaped so that it can engage in form-fitting manner in a complementary-shaped opening of the front bearing portion  41  and is displaceably mounted on the central axle  33 . 
     The blocking insert  81  comprises a plurality of bolts  83  which can engage in corresponding recesses of the rear bearing portion  43  to block a rotary connection between the rear and the front bearing portion when the bolt  57  is not displaced by the pusher  17  against the spring force in the central axle  33 . A displacement of the blocking insert  81  is brought about by the driver element  79  when the pusher  17  is introduced into the actuating portion  47  and the spring-mounted bolt  57  is thereby displaced along the central axle  33 . 
     Preferably, the blocking insert  81  is thereby also displaced against a spring force so that on release of the bolt  57 , the blocking insert  81  is displaced again in the direction of the rear bearing portion  43  in order thus to re-establish the non-rotatable connection between the two bearing portions (first operating state of the switching unit  45 ). As soon as the blockage between the bearing portions  41  and  43  is released (second operating state of the switching unit  45 ), both the bearing portions  41 ,  43  are mounted on the central axle  33  rotatable relative to one another, so that the angle between the rear and the front stabilizing struts  37 ,  39  is changeable. In this operating state, the connecting piece  11 ,  11 ′ can be folded between the front wheels and the rear wheels by means of the joint  13  such that the separation a between the front wheels  7 ,  7 ′ and the rear wheels  3 ,  3 ′ is reduced in order to create either a transportation state of the child push chair frame  1  or an operating state of the child push chair frame  1 . 
       FIG. 10  clearly shows that the blocking insert  81  can be introduced in form-fitting manner into a correspondingly configured cut-out in the front bearing portion  41 . In the present exemplary embodiment, the switching unit  45  is configured essentially substantially cylindrical like its component elements (front bearing portion  41 , rear bearing portion  43  and actuating portion  47 ). Fundamentally, however, another form is also conceivable. 
       FIG. 11  shows a detailed representation of the foot actuating mechanism  15 . The foot actuating mechanism  15  is fastened to the rear axle  5  and is, in particular, mounted rotatably thereon. The foot actuating mechanism  15  herein also has an opening into which one end of the connecting piece  11 ′ projects. If a shoe is placed on the stepping surface  85  of the foot actuating mechanism  15 , the foot actuating mechanism  15  rotates about the rear axle  5 , so that two partial portions  87  and  87 ′ of the connecting piece  11 ′ are no longer arranged at an angle of 180° to one another. In this way, the joint  13  is displaced in the direction of the arrow R against the force of a spring element  89  which is arranged spirally in the joint  13  and ensures that the child push chair frame  1  can unfold from a folded-together state shown in  FIG. 2 c    or  2   d  semi-automatically through the force of the spring element  89  back into the operational state. As indicated in the introductory part, in place of the foot actuating element  15 , an apparatus actuated by hand for actuating the joint  13  can be provided. A corresponding mechanism could be carried out, for example, by actuating the bolt  57  by means of the pusher  17 . 
     Overall, embodiments provide an advantageous child push chair frame  1  which can be converted into various advantageous operational states. The respective state of the child push chair frame can be fixed by means of suitable locking positions of the two bearing portions  41 ,  43  relative to one another. For this purpose, for example, the bearing portions  41 ,  43  can have corresponding arresting means in suitable angular positions to one another. 
     By means of the central switching units  45 , one of which is arranged at either end of a central axle  33 , by a simple actuation through displacement of the pusher  17 , the non-rotatable connection between the bearing portions  41 ,  43  of the switching units  45  can be released, in order thus to instigate a folding procedure of the child push chair frame  1 . 
     Preferably, the two bearing portions  41  and  43  are rotatable relative to one another such that they are arrestable in at least two different angular positions and thus in different positions. In this way, not only can a standing-capable operating state of the child push chair frame  1  be achieved, but it is also possible, by means of a further arresting position, to achieve complete folding-together and therefore a conversion of the child push chair frame  1  to a minimal size. In the respective positions, the pusher  17  can either be pushed in or pulled out, so that essentially, use of the child push chair is possible in both the operational states, provided a child push chair upper part  49  is connected to the child push chair frame  1 . 
       FIG. 12  shows an embodiment wherein the fastening means  35  firmly connected to the front bearing portion  41  for fastening a child push chair upper part  49  comprise an elastically pre-tensioned locking bolt  90  which corresponds with a locking recess  91  arranged on the outer periphery of the rear bearing portion  43  and, together with this locking recess  91 , forms a “soft lock”. This locking mechanism defines the “parking position” of the child push chair frame in which the front  37  and rear  39  stabilizing struts are not fully folded together. 
     According to  FIG. 13 , the switching unit  45  comprises a locking pin  92  which, in the spread-apart travelling position of the stabilizing struts, is situated within a locking recess  93 . By means of an actuating pusher  94  which is mounted longitudinally displaceable within the pusher receptacle  29 , the locking pin  92  can be moved out of the locking recess  93 , specifically in a circular arc-shaped guide section  95  and, together with the pusher  17 , into an end position  96  in which the front  37  and rear  39  stabilizing struts are fully folded together. Together with the pusher  17 , the rear stabilizing struts  39  are foldable in the direction of the front stabilizing struts  37 . The circular arc-shaped guide section  95  is arranged within the rear bearing portion  43  which is connected to the rear stabilizing struts  39 . 
     With the pusher  17  fully driven in, the aforementioned actuating pushers  94  can be moved by switching projections  197  mounted thereon into the aforementioned unlocking position. In this way, the switching unit  45  can be unlatched by the pusher  17 . 
     The circular arc-shaped guide section  95  can have another locking recess  97  shortly before the end stop  96  in which the locking bolt  92  can be introduced if needed, specifically by means of a spring force (spring  98 ) acting on the locking bolt  92 . In this way, the parking position of the child push chair frame can be fixed. The unlatching is then carried out in the same way as the unlatching in the spread-apart travelling position of the child push chair frame. 
     According to another alternative embodiment shown in  FIGS. 14 a  to 14 e   , this comprises a switching unit  45  wherein a displacement plate  65  which has at one end one, preferably two, locking projections  99  or at the opposite end, a further locking projection  100 . These locking projections  99 ,  100  correspond with associated locking recesses  101 ,  102  on a switching disk  103  of the switching unit  45 . By means of the pusher  17 , the aforementioned projections  99 ,  100  are brought into an unlatching position ( FIG. 14 b   , arrow  108  in  FIG. 14 a   ). Thereafter, the switching disk  103  can be rotated relative to the displacement plate  65  (arrow  104  in  FIG. 14 c   ) until the one locking projection  100  engages in a recess  106  of a spring-loaded hook  105 . In this position, the front and rear stabilizing struts  37 ,  39  are fully folded together and locked in the transportation position ( FIG. 14 d   ). For unlocking, the displacement plate  65  is moved by means of the pusher  17  into an unlatching position. The small latching projection  100  then moves out of the associated recess  106  on the locking hook  105  (arrow  107  in  FIG. 14 d   ), so that the switching disk  103  can be turned back into the original position, specifically into a position in which the front and rear stabilizing struts  37 ,  39  are again fully spread apart ( FIG. 14 a   ). The displacement plate ( 65 ) is movable against an elastic pre-tension out of the locking position. 
     Another embodiment, shown in  FIGS. 15 a  and 15 b   , further differentiates between a locking projection  109  connected to the displacement plate ( 65 ) and a pin-like projection  111  guided within a circular arc-shaped guide section  110 . This pin-like projection  111  is configured to serve as a rotation stop and to bear transverse loads. In the end positions of the stop pin  111 , the locking projection  109  is transverse load-free. The locking projection  109  therefore serves only to define the latching position in the fully spread-apart position of the stabilizing struts  37 ,  39  and does not bear any transverse loads. 
     LIST OF REFERENCE NUMBERS 
     
         
           1  Child push chair frame 
           3 ,  3 ′ Rear wheels 
           5  Rear axle 
           7 ,  7 ′ Front wheels 
           9  Front axle 
           11 ,  11 ′ Connecting piece 
           13  Joint 
           15  Foot actuating mechanism 
           17  Pusher 
           19  Handle region 
           21  Height adjustment device 
           23  Limb 
           25  Arrow 
           27  Distal end 
           29  Pusher receptacle 
           31  Clamping means 
           33  Central axle 
           35 ,  35 ′ Fastening means 
           37  Front stabilizing struts 
           39  Rear stabilizing struts 
           41  Front bearing portion 
           43  Rear bearing portion 
           45  Switching unit 
           47  Actuating portion 
           49  Child push chair upper part 
           51  Through opening 
           53  Cover 
           55  Guide elements 
           56  Blocking elements 
           57  Bolt 
           59  Distal end 
           61  Actuating element 
           63  Arrow 
           65  Displacement plate 
           67  Guide elements 
           69  Spring elements 
           71  Circular disk element 
           73 ,  73 ′ Grooves 
           75 ,  75 ′ Locking cut-outs 
           77  Bolt 
           79  Driver element 
           81  Blocking insert 
           83  Bolt 
           85  Stepping surface 
           87 ,  87 ′ Partial portions 
           89  Spring element 
           90  Locking bolt 
           91  Locking recess (for locking bolt) 
           92  Locking pin 
           93  Locking recess (for locking pin) 
           94  Actuating pusher 
           95  Guide section 
           96  End position/end stop 
           97  Locking recess (before end stop) 
           98  Spring 
           99  Locking projection 
           100  Further locking projection 
           101  Locking recess 
           102  Locking recess 
           103  Switching disk 
           104  Arrow 
           105  Hook 
           106  Recess 
           107  Arrow 
           108  Arrow 
           109  Locking projection 
           110  Guide section 
           111  Projection 
           197  Switching projections 
         M Central plane 
         D Rotary axis 
         R Direction 
         a Separation