Collapsible stroller

A collapsible child's stroller with a handle frame (30), a front wheel frame (10) and a rear wheel frame (20), mutually connected at a hinge joint (12, 22, 42) for mutual angular displacement between folded and unfolded configurations. The hinge joint has two spaced apart, parallel hinge axes, about which the frames (10, 20, 30) mutually rotate. The stroller is further provided with a locking element (43, 44) moveable between a locked position in which the frames (10, 20, 30) are locked in the unfolded configuration, and an unlocked position allowing the frames (10, 20, 30) to rotate to the folded configuration. The locking element (43, 44) moves in a direction traverse to the parallel hinge axes to better transfer loads between the frames.

FIELD OF THE INVENTION

The present invention relates to strollers for babies, toddlers and young children. In particular, the invention relates to strollers with collapsible frames that fold into a compact configuration for storage and portability.

BACKGROUND OF THE INVENTION

Strollers are a well known and common way of transporting babies or young children. However, due to their size, strollers typically have collapsible frames that fold into a more compact configuration for storage or to be stowed in a vehicle.

In an effort to achieve a more compact folded configuration, some collapsible strollers have particularly complex hinged and telescopic frame structures. While this may provide a compact folded form, the complexity of the frame increases the production costs. Furthermore, added complexity of the frame tends to weigh against a smooth and reliable folding mechanism. For parents of young children, this operation needs to occur as quickly and simply as possible.

Many countries have official design standards and regulations that apply to strollers. These require the frame to meet certain strength and rigidity thresholds while avoiding hazards such as finger traps and so on. The strength requirement specified by the official standards mean that steel or aluminium alloy are the traditional choices for frame material. However, from the perspective of material costs and high-volume production, polymer frames would be more desirable. Polymers have the added advantage of being lightweight, easily moulded into ergonomic shapes and coloured for greater aesthetic appeal. However, to meet the required strength and structural standards, the polymer would need to be an exotic composite and prohibitively expensive. Alternatively, a cheaper (and weaker) polymer would need to be formed in large cross sections which defeats the purpose of a compact collapsible stroller.

With these issues in mind, there is a need for a collapsible stroller with a predominantly polymer frame that meets the high strength and structural requirements of the official standards, while smoothly, simply and reliably collapsing into a compact folded form.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a collapsible stroller comprising:a handle frame;a front wheel frame;a rear wheel frame; anda hinge joint connecting the handle frame, the front wheel frame and rear wheel frame for mutual angular displacement relative to each other about two spaced parallel hinge axes, the hinge joint having a locking element moveable between an unlocked position allowing the handle, front wheel and rear wheel frames to mutually rotate into a folded configuration, and a locked position in which the handle, front wheel and rear wheel frames are fixed in an unfolded configuration; wherein,the locking element moves in a direction transverse to the two parallel hinge axes.

Preferably, the handle, front wheel and rear wheel frames are predominantly polymer.

The Applicant has found that configuring the locking element such that its movement is transverse to the hinge axes allows the locking element itself to be a significant structural element of the stroller and in particular the main folding hinge. This allows the stroller to be predominantly polymer with reinforcement at a structurally crucial part.

The locking element can take a variety of forms, but is conveniently provided as a locking pin for ease of production and incorporation into the hinge joint. Traditionally, the main hinge mechanisms in collapsible strollers use a locking pin or equivalent structure which moves parallel to the hinge axis to lock two hinged frame members together. This is adequate for preventing relative rotation of two frame elements but does very little to transfer bending or axial loads between these elements. By configuring the locking pin such that it extends in a direction transverse to the hinge axis, it essentially becomes a significant load bearing element in its own right. In particular, it provides a load bearing element at the connection between two frame elements to transfer substantial loads therebetween. As the locking pin is transverse to the hinge axis, it can also be made physically larger and stronger without any impact on the overall size of the frame elements as it still comfortably fits within the frame element cross-sections.

Preferably, the locking pin is metallic and in a particularly preferred form the locking pin is steel. Preferably the locking pin has a minimum cross sectional dimension of 5 mm. Preferably, the locking pin is solid, as tubular locking pins would risk being crushed. Preferably the locking pin is at least 40 mm long and more preferably at least 55 mm long.

Preferably, the hinge joint has at least two reinforced bearing surfaces adjacent the locking pin when in the locked position, such that structural loads are transferrable between the reinforced bearing surfaces via the locking pin. In some options, the hinge joint has metal axles such that at least one of the reinforced bearing surfaces is provided by one of the metal axles.

In another option, the reinforced bearing surface is provided by a movable element that moves into a load bearing position as the locking pin moves to the locked position and moves away from the load bearing position when the locking pin retracts from the locked position.

Preferably, the hinge joint has a hinge housing of polymer material integrally formed with the polymer rear wheel frame, and the polymer handle frame has an integrally formed spur-gear formation for rotation about one of the hinge axles within the hinge joint, while the front wheel frame has an integrally formed polymer spur-gear formation rotatably mounted at the other of the hinge axles for meshing inter-engagement with the spur-gear formation of the handle frame. Preferably, the locking pin slides within a groove partially defined by the handle frame and partially defined by the front wheel frame. Preferably, the groove is partially defined within the spur-gear formation of the handle frame and partially defined within the spur-gear formation of the front wheel frame such that the section of the groove in the front wheel frame aligns with the section of the groove in the handle frame when in the locked position. Preferably the locking pin is biased into the locked position, by a spring within the section of groove defined by the handle frame.

Preferably the hinge joint has a pin guide surface for sliding engagement with a distal end of the locking pin as the stroller folds and unfolds such that the pin guide surface limits movement of the locking pin when moving from the folded to the unfolded configuration. In a particularly preferred form, the front-wheel frame has a slide surface for receiving the end of the locking pin from the pin guide surface, and smoothly directing the locking pin to the section of the groove in the front-wheel frame that partially defines the locked position. Preferably, the pin guide surface and the slide surface have a common tangent at the point of transition where the pin guide surface hands-off the end of the locking pin to the slide surface. In a particularly preferred form, the locking pin is chamfered or rounded.

Preferably, the handle frame has a grip section and an unlocking actuator connected to the biased locking pin for retracting the locking pin into the unlocked position. Preferably, the direction of movement of the locking pin and the longitudinal extent of the handle frame are angled relative to each other by less than 45 degrees such that actuation of the unlocking actuator is a manual displacement in a direction broadly similar to the direction of movement of the locking pin.

In a particularly preferred form, the longitudinal extent of the handle frame, the rear-wheel frame and the front-wheel frame are substantially parallel in the folded configuration.

Preferably, the front-wheel frame has a front-wheel assembly and the rear-wheel frame has a rear-wheel assembly, the front-wheel assembly having a narrower wheel base than the rear-wheel assembly such that in the folded configuration, the front wheel assembly nests within the rear-wheel assembly.

In a related aspect, the handle frame, the rear-wheel frame and the front-wheel frame are formed from a glass fibre reinforced nylon material. Preferably, the glass fibre reinforced nylon material is a composite with 25% to 35% by weight of glass fibre.

In some embodiments, the rear wheel frame includes a braking mechanism to prevent rotation of the rear wheels, the rear wheel frame further comprising a brake actuator pedal configured for foot actuation of the brake mechanism such that the pedal can be moved between an engaged and dis-engaged position using the sole of the foot only. It will be appreciated that this prevents scuffing to the upper parts of any footwear or injury and discomfort to those with open toed footwear.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring toFIG. 1, the collapsible stroller is shown (without child seat, harness and hood fabric) in its unfolded configuration, a front wheel frame10, rear wheel frame20and handle frame30connect at a pair of hinge joints40. The complete stroller with child seat80, fabric-covered retractable hood82, and cup holder84is shown in the unfolded and folded configurations inFIGS. 14 and 15respectively. A fabric seat80with restraint harness86suspends from the handle frame30and the front wheel frame10. Retractable hood32,82provides shade when necessary. The front wheel frame10has a front wheel assembly11with two castors113and114mounted for rotation about vertical axes for steering and manoeuvrability. The rear wheel frame20has a rear wheel assembly21with larger diameter wheels211for ride comfort and a brake assembly (described below with reference toFIGS. 6 and 7).FIG. 2separates the frames and reveals the internal elements of the hinge joints40. It will be appreciated the left and right hinge joints are mirror images so the description of the left hinge joint (seeFIGS. 3, 4 and 5) applies equally to both.

The rear wheel frame20has two integrally formed hinge housings22. Each hinge housing has a pair of spaced metal axles41and42. As best shown inFIG. 4, the front wheel frame10is mounted for rotation about one of the axles42while the handle frame30is rotatably mounted to the metal axle41. The handle frame30and the front wheel frame10each have integrally formed spur gear formations121and311respectively. The teeth of the gear formations121and311mesh to control the rotation of the handle frame30and the front wheel frame10relative to the rear wheel frame20.

As best shown inFIG. 5, the handle frame30and the front wheel frame10combine to make groove313and122in which a locking pin43slides between an unlocking and locking position. The locking pin43is in the unlocking position when it is within the groove section313defined by the handle frame30. In the locking position, the locking pin43is partially in the groove section122defined by the front wheel frame10and partially in the groove section313in the handle frame30as shown inFIG. 5. Spring44biases the locking pin43into the locking position.

In the locking position, the frames are secured in the unfolded configuration. However, the locking pin43not only prevents relative rotation of the handle, front wheel and rear wheel frames, it provides a high strength structural element for transferring loads between each of the frames. To enhance this, metal pin221and metal axle42provide re-enforced bearing surfaces positioned so that bending and axial loads transfer between them via the locking pin43.

As a load bearing element within the frame, the locking pin43is an 8 mm square stainless steel rod. The pin length extends between the two axles or re-enforced bearing surfaces. It will be appreciated that the locking pin can be different materials and adopt a variety of configurations, but for practical purposes, the locking pin is conveniently metallic and has a minimum cross-sectional dimension of 4 mm and a minimum length of 40 mm.

Referring toFIGS. 3, 4 and 5, the metal pin221is closely adjacent the metal axle41such that loads from both the front and rear wheel frames (10and20) transfer to each other, and the metal axle42of the handle frame30through the locking pin43. The added strength and rigidity provided by the locking pin43allows the polymer parts of the hinge joint40to be smaller and more compact.

Smooth and reliable folding and unfolding of the stroller is important to users. To facilitate this, the hinge joints have a pin guide surface312on the hinge housing22which co-operates with slide surface12on the front wheel frame10. In the folded configuration, the end of the locking pin43is pressed against the pin guide surface312by the compressed spring44. As the stroller is unfolded, the end of the locking pin43slides along the pin guide surface312toward the spur gear formation121of the front wheel frame10.

As the end of the locking pin43meets the spur gear formation121, the slide surface12comes into alignment with the pin guide surface312because the relative rotation of each frame is precisely controlled by the meshed teeth of the spur gear formations311and121. By careful configuration of the locking pin43, the pin guide surface312and the slide surface, both curved surfaces have a common tangent at the transition point between the two as the pin guide surface ‘hands-off’ the end of the locking pin43to the slide surface12or vice versa.

Once on the slide surface12, the locking pin43continues towards the groove section122in the front wheel frame10. When the groove sections313and112align, the spring44biases the locking pin43into the locked position with its rounded end against the metal pin221. The arcuate opening123accommodates the metal pin221as the front wheel frame10rotates relative to the hinge housing22.

To collapse the stroller into its configuration, the handle frame30is provided with an unlocking actuator33with a pair of manually actuated triggers32connected by cable to the locking pins43. The manual triggers32are proximate the grip section of the handle frame30for retraction by the user which in turn retracts the locking pins43into the unlocked position (seeFIG. 5). The angle between the longitudinal extent of the handle frame30and the direction of movement of the locking pins43is kept small and preferably less than 45 degrees. Keeping this angle shallow means the manual force used to retract the triggers32is more directly and efficiently applied to the locking pin43.

With the locking pin in the unlocked position, the stroller can collapse into the folded configuration in which the front wheel frame10, the rear wheel frame20, and the handle frame30are substantially parallel to each other.

Referring toFIGS. 6, 7 and 8, the braking mechanism of the rear wheel frame20is shown in detail. The brake actuator pedal212is mounted to the lower end of the rear wheel frame20via pivot axis214. The spring217and wedge-shaped end cup218act on the brake pedal212to provide an over-centre mechanism whereby the pedal212is biased into an engaged position or a dis-engaged position. In the engaged position, the right side locking spigot215and the left side locking spigot213engage with the rear wheel hub spline formation216to prevent the wheels211from rotating.

Foot actuation of the brake pedal past the balance point of the over-centre mechanism (217and218) biases the left and right locking spigots (213and215) out of engagement with the rear hub spline such that wheels211rotate freely. Brake cable24extend between the brake pedal212and corresponding pivot mount for the left locking spigot to synchronise braking of both wheels211.

The brake pedal212is positioned such that it is foot actuated using the sole of the foot or shoe only. This avoids any scuffing to the upper surfaces of any footwear or potential injury for those with open toed footwear.

Referring toFIGS. 10, 11, 12 and 13, the front wheel assembly11of the front wheel frame10is shown in detail. The front wheels114are castors mounted for rotation about vertical axles116for steering and manoeuvrability of the stroller. A vertical axle mount is inserted into the lower end of the front wheel frame10and held by interference fit. The vertical axles of the rotatable hinge mount112are retained in the bore of the vertical axle mount via a cir-clip. The sprung wheel mounts113pivotally attach to the rotatable hinge mounts via hinge axles117. Suspension spring115acts between the rotatable hinge mount112and the sprung wheel mount113to provide the front wheels114with suspension. It will be appreciated that sprung suspension on the front wheels improve the ride quality for the child or toddler and dampen impact loads on the collapsible frame caused by ground irregularities.

Comprises/comprising and grammatical variations thereof when used in this specification are to be taken to specify the presence of stated features, integers, steps or components or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

The present invention has been defined herein by way of example only. The skilled workers in this field will readily recognise many variations and modifications which do not depart from the spirit and scope of the broad inventive concept.