Baby-carriage with steerable wheels

A hand-propelled vehicle for passenger transport, in particular a pushchair, includes a chassis with at least three wheels, at least two of which are pivotally connected to the chassis, wherein the pivotable wheels are connected by at least one shaft which is pivotally connected to a fixed part of the chassis. The pivotable wheels are further situated behind the at least one fixed wheel as seen in the direction of travel of the vehicle, and the pivot connection of the shaft to the fixed part of the chassis is situated in front of the shaft as seen in the direction of travel. It is thus possible to arrange a steering function in frame constructions where there is no room for pivotable front wheels.

BACKGROUND OF THE INVENTION

The invention relates to a hand-propelled vehicle for passenger transport, in particular a pushchair, or perambulator comprising a chassis with at least three wheels, at least two of which are pivotally connected to the chassis.

Such a vehicle is generally known in the form of a pushchair, a buggy, a stroller or a wheelchair.

There are two types of pushchair, i.e. with relatively small solid wheels such as buggies, and with relatively large wheels with pneumatic tires such as strollers The latter type, which is marketed by applicant under the name Freerider, is becoming increasingly popular.

Pushchairs with small wheels are often provided is with steerable, or in fact co-steering wheels. These wheels are then embodied as castors and are generally arranged at the front of the pushchair.

The large wheels with pneumatic tires are generally not steerable since pivot-mounting of large wheels is more difficult, and a conventional pivot construction would be voluminous and expensive. A pivotally mounted wheel is furthermore not very stable during reverse movement of the vehicle.

SUMMARY OF THE INVENTION

The object of the invention is to provide a vehicle of the above described type which can be manufactured relatively simply and at low cost, and which in particular takes up little space in the folded-down position and which moreover has an excellent forward movement stability.

This object is achieved by such a vehicle wherein the pivotable wheels are connected by at least one shaft which is pivotally connected to the fixed part of the chassis.

Although the invention is intended in the first instance for pushchairs, it can also be applied to other hand-propelled vehicles, such as wheelchairs.

A better forward movement stability is obtained by placing the pivotable wheels together on a shaft.

According to another preferred embodiment the pivotable wheels are situated behind the at least one fixed wheel in the direction of travel of the vehicle, and the pivot connection of the shaft to the fixed part of the chassis is situated in front of the shaft as seen in the direction of travel.

This measure also results in an improved stability, especially during reverse travel.

According to a further preferred embodiment the distance between the pivot point and the shaft is in the order of magnitude of half the distance between the pivotable wheels.

Unexpectedly, this dimensioning measure also results in an increase in stability.

A specific preferred embodiment provides for the arranging of a rolling bearing in the pivot point.

The pivot point is after all heavily loaded. By providing a rolling bearing these loading forces can be absorbed well without this resulting in excessive wear.

Yet another preferred embodiment provides a slidable support bearing between the pivotable shaft and the pivot connection.

This support bearing also serves to absorb the great forces and moments which act on the pivot connection. By placing the support bearing at a considerable distance from the pivot point large moments can be absorbed with relatively small forces and pressures, thereby reducing wear.

An even more specific embodiment provides for the arranging of a rolling bearing in the support bearing, which support bearing is adapted to absorb at least a part of the normal force between the pivotable shaft and the pivot connection.

Tests have taught that the load on the support bearing proved to be greater than supposed. Pivoting can take place more easily through the arranging of rolling bearings, so that travel comfort is improved.

In order to further improve comfort and to increase the rigidity of the frame, the support bearing is provided with two rolling bearings, the axis of which encloses an angle which is greater than 30°.

According to yet another preferred embodiment the vehicle comprises friction-increasing means which comprise at least one friction member connected to the pivotable shaft or the fixed part of the chassis and engaging on the fixed part or the shaft.

The pivoting of the pivotable wheels hereby becomes subject to friction, so that with careful adjustment this measure also increases the stability. This would seem to conflict with the arrangement of rolling bearings in the support bearing, but the rolling bearings serve to absorb normal forces and to reduce wear, while the friction-increasing means serve to form a defined friction force during pivoting.

According to yet another preferred embodiment the vehicle comprises means for fixing the pivot connection in a determined position between the shaft and the fixed part of the chassis.

The pivoting of the wheels is blocked with these measures, so that a carriage is obtained with the travel performance of a classic pushchair. It is self-evident however that for this purpose the pivoting means must be fixed in the pivot position.

According to yet another preferred embodiment the fixation means comprise at least one movable blocking member connected to the pivotable shaft or the fixed part of the chassis and co-acting with the fixed part or the pivotable shaft, which member is biased to its blocking position.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a pushchair1. Pushchair1comprises a frame2which is formed by a V-shaped tube part3to which is fastened a substantially U-shaped, obliquely extending push bracket4. Push bracket4is connected to V-shaped tube part3by means of a folding mechanism not shown in the drawing. It is possible by means of the folding mechanism to carry the push bracket4to the practically horizontal position so as to reduce the volume of the pushchair. Push bracket4can moreover be pressed in by means of telescopic tubular parts accommodated therein.

For the further components of the frame and their functions, further reference is made to Netherlands patent application number 9400645. The components in question will not be described in full since they do not form part of the present invention.

A carrier element5for a child to be transported in the pushchair is further fixed to push bracket4. The carrier element shown inFIG. 1is formed by a seat manufactured from soft material which is suitable for transporting children from the age at which they can sit. For transport of smaller children use can be made of a different type of child carrier fastened to the V-shaped tube part, for instance a carrycot.

Wheels provided with pneumatic tires6are further mounted rotatably on the V-shaped tube part.

The top of V-shaped tube part3is embodied in the form of a bend, the central line of which extends in a circular arc. A bearing bush9is arranged fixedly with the V-shaped tube part in the centre of said circular arc. Bearing bush9is connected to V-shaped tube part3by means of two connecting rods10,11. End part13of connecting rod11connects to curved part8.

A shaft14extends through bearing bush9. On both sides of bearing bush9the shaft14is connected to an ear-shaped part15which is thus rotatable around shaft14. The ear-shaped part15is connected to a rear shaft18by means of two brackets16,17. Two wheels19,20are mounted on rear shaft18. By means of the construction described up to this point a rear shaft is obtained which is pivotable relative to the whole carriage.

As a result of the fact that the rear shaft is situated a considerable distance from bearing bush9as seen in the direction of movement of the carriage, the bearing present in bearing bush9is subjected to a considerable moment. This results in an excessive load on this bearing bush9.

In order to reduce this load a pressure part21is arranged between brackets16,17. On its upper side the pressure part21is provided with a clamping part22which is in contact with the part8curved in circular form of V-shaped tube part3. The combination of V-shaped tube part3and pressure part21thus acts as an additional support for the bearing. This relieves the load on the bearing.

So as to likewise not load the bearing excessively in the situation where the carriage is for instance lifted, a clamping part22which can slide over the upper side of V-shaped tube part3is connected to pressure part21.

A pushchair is thus obtained which has good travel characteristics owing to its co-steered rear shaft. It is important here that the rotation point, formed in this case by bearing9, is situated a considerable distance in front of rear shaft18. In the present embodiment this distance herein amounts to about half the width of rear shaft18. A certain measure of freedom is of course possible within this dimensioning; it is thus possible to place the bearing further to the front or further to the rear.

In some situations the steerability of rear shaft18is less desirable, for instance when the pushchair must be moved over an obstacle such as a curb. It is therefore possible to lock the pivoting function of the rear shaft. A locking pin23is arranged for this purpose in pressure part21. Locking pin23is movable in substantially vertical direction. When rear shaft18is parallel to the front shaft, locking pin23is situated under a hole24arranged in V-shaped tube part3. A helical spring25is arranged to push the pin23into hole24. The above described locking device has the function that locking is obtained automatically in the right-hand position of rear shaft18.

This locking function can be released by means of a transverse pin26which is connected rigidly to locking pin23and which extends through a hole in the locking pin. Moving this pin downward prevents locking pin23moving into the hole and there performing the locking function. For downward movement of transverse pin26a lever27is connected rotatably to pressure part21, wherein lever27is provided with two contoured edges28for moving transverse pin26upward or downward. Lever27is formed such that it can be operated by foot.

For rotatable mounting and easy fitting thereof, the lever27is provided with two snap connections29which engage on shaft ends which are not shown in the drawing but which extend on either side of locking pin23, and which are fixedly connected to pressure part21.

It is further pointed out that, likewise for the purpose of facilitating assembly, pressure part21is constructed from two components21aand21bmanufactured from plastic. These components are mutually connected by means of screws30. The screws further extend through clamping part22, which is thereby also connected in one operation to the pressure part. Screws30also serve to connect pressure part21to bracket16or bracket17, which connect bearing9to rear shaft18.

Rear shaft18is otherwise provided with a per se known braking device. The braking device is provided with a rod31which is rotatably connected to rear shaft18by means of two levers32, each placed in the vicinity of one of the rear wheels. The geometry of lever32is formed such that shaft31is movable between two positions, wherein in a first position shaft31is situated a short distance from rear shaft18and engages on a braking element arranged in the rear wheels, and a second position wherein rod31is clear of the relevant braking element.

Lever32is herein provided with two operating elements33with which the lever can be moved between the two positions. A spring (not shown in the drawing) is further arranged for holding the rod31in the relevant positions.

FIG. 4finally shows how two rolling bearings35,36of small dimensions are accommodated in pressure part21. Bearings35,36with their respective shafts37,38are herein embedded in the pressure part21which is provided for this purpose with a recess. The recess is so large that the ring of the bearing does not come into contact with the pressure part, but only with the arcuate part8.

InFIG. 1, angle40is the angle between the brackets16and17and angle41is the angle between the two rolling bearings.