Technical field

The invention relates to a guiding wheel which makes it easier for personnel using a hospital bed to guide it during transport through a hospital. These guiding wheels are known as additional wheels or also fifth wheels. As part of its chassis they influence the hospital bed's manipulation.

Background art

In the field of hospital beds, fifth wheels represent the common state of the art. By virtue of their functionality they influence handling of the entire hospital bed during its transport through a hospital and, in this way, make the work of the hospital personnel easier. The matter of transport of hospital beds is associated with the behaviour of a shifting load mounted on four wheels which have two free axes of rotation. The first free axis of rotation causes the actual rotation of the wheels, which allows movement of the load forwards or backwards in respect to the surface. The second axis of rotation of the wheels runs through the fixing of the wheel to the chassis of the load, it is perpendicular to the surface and allows the sideward rotation of the wheel. In this configuration of wheels it is very complicated for one person to handle the bed and when going around corners the personnel must go on ahead to make it possible to turn a bed with a heavy load. One can see the same problem, for example, with regular shopping trolleys.

This problem can be dealt with in two ways. The first possibility is to block the second axis of rotation for the two end wheels on the side where there is transferred the pushing force from the personnel. The methods for this side blocking of two wheels are known from the state of the art. A bed with wheels blocked in this way is easier to handle.

The other way of resolving this technical problem is to add a fifth wheel to the chassis located approximately in the middle of this chassis between the two pairs of basic wheels. The fifth wheel is then located in the centre of the chassis and forms an axis of rotation. In certain solutions these wheels also comprise a powered drive to spare the work of the personnel.

In practice both methods are usually designed so that the temporarily created axis of rotation can be eliminated easily. This is necessary in practice if we do not want to transport a bed a great distance but just handle it in a small area. From this issue it is clearly evident that the foregoing examples of technical solutions must include two states: where a temporary axis of rotation for the bed is created and where the bed does not have this axis.

In the case of a fifth wheel there are several different technical solutions which describe its control from the upper position, where the wheel is in the storage position, to the lower use position, where the wheel is in contact with the surface. The movement of the wheel can be attained electronically via an additional drive to make it go down, or manually, where usually there is a suitable transfer of force from a pedal to the sliding mechanism of the fifth wheel. One method is shown by patent US 5,987,671. This document describes the mechanical means of shifting the fifth wheel to the lower position using a pedal assembly where, using a longitudinal rod, levers and drawbars, the rotational force from the pedal is transferred to the shift of the wheel.

Utility model CZ17216 shows another fifth wheel. In this case a pedal, arm, pressure member and appropriately located spring constitute the fifth wheel assembly. The document US 6,772,850 shows a version where the movement of the fifth wheel is controlled electronically.

These technical solutions, along with the further state of art, show fifth wheels which have several disadvantages. The electronically controlled versions make the entire function more expensive, and so they are used only in combination with such hospital beds which are wholly electronically controlled. Another disadvantage in the case of the known technical solutions is the independence from the main bed pedals which standardly brake the bed. Moreover, in the case of solutions which comply with this condition, they are designed in such a way that their price is still high as a result of the complexity of the solution.

Summary of the invention

The above mentioned problems are to a significant extent eliminated by a pedal- controlled guiding wheel for the hospital bed embedded in the bed chassis. The pedal is connected to the guiding wheel via a drawbar and other linked members, including a lever, cam and guiding member. The cam is linked to the drawbar, and the guiding member is linked to the lever. In an alternative embodiment the cam may be linked with the lever, and the guiding member with the drawbar.

The lever is also linked with a profile which is connected to the guiding wheel.

The invention may also be augmented with a flexible member that provides the better contact of the guiding wheel with the surface. The flexible member may be a shaped rod, spring or torsion spring.

Brief description of the drawings

The hospital bed with a chassis and a fifth wheel is displayed in fig. 1. A cross- section of the hospital bed braking assembly is shown in fig. 2. Fig. 3 shows the fifth wheel with a lever, guiding member and a cam. Fig. 4 shows a detailed view of the left fixing of the fifth wheel to the chassis. Fig. 5 shows a detailed view of the right fixing of the fifth wheel to the chassis. Fig. 6 shows a detail of the members with the cam connected to the drawbar. Fig. 7 shows a detail of the members with the guiding member connected to the drawbar. Detailed description of the drawings

Fig. 1 displays the hospital bed 1 with a fifth wheel 2 according to the invention where the fifth wheel 2 is connected to the chassis 3 of the hospital bed 1 One part of the chassis 3 is also a pedal 4 for the controlling the brakes. The chassis 3 of the hospital bed 1 is braked using brakes integrated into the wheels assembly. The actual braking of the chassis 3 of the hospital bed 1 is known from the state of the art. The brakes of the head part of the chassis 3 are connected by a hexagon, in the same way as the brakes of the leg part of the chassis 3. The brakes of the head part and leg part are linked together by the drawbar 5 running across the chassis 3. This arrangement can be seen in fig. 2. So the entire braking assembly of the hospital bed 1 works in a connected manner, i.e., after the application of one brake of the chassis 3 the remaining brakes of the hospital bed 1 are automatically applied. The rotational movement of the hexagon, which is caused by the movement of the pedal 4, is converted into the linear movement of the drawbar 5. At the other end of the chassis 3 this causes the rotation of the second hexagon and the application of the remaining two brakes via this hexagon.

Fig. 3 displays the the fifth wheel 2 assembly and its connection to the frame of the hospital bed 1 approximately in the middle of chassis 3. The holders 6 and 7 serve to fix the fifth wheel 2 assembly to the frame. Holders 6 and 7 are firmly fixed to the chassis 3 by screws and serve as supports for the other parts of the fifth wheel 2. The precise form of the holders 6 and 7 differs, i.e., holder 6 which is located on one side of the hospital bed is different in terms of its function from holder 7. The precise function of both holders 6 and 7 and their linkage to other parts of the mechanism is evident from the description below. The actual fifth wheel 2 is firmly fixed with a hollow profile 8 _± which creates a link across the frame of the chassis 3 in which the holders 6 and 7 are fixed with the chassis 3 in such a way that it can rotate freely in holders 6 and 7. Using the fixed connection of the profile 8 with the fifth wheel 2, the rotation of the profile 8 causes the movement of the wheel in respect to the surface. Profile 8 can be formed by a tube, box section or other suitable shape. The fifth wheel 2 can thus move between two positions. In the first position, which can be called the storage position, the fifth wheel 2 is located away from the surface so there is no contact between the fifth wheel 2 and the surface. If the fifth wheel 2 is in this storage position, the hospital bed does not have an ancillary rotational point in the centre of the chassis 3, but it moves freely. This storage position is advantageous if, for example, the personnel need to move the hospital bed 1 to the side.

The lowering of the fifth wheel 2 to the lower use position is caused by the rotation of the profile 8, to which the fifth wheel 2 is firmly fixed. After the rotation of the profile 8 the fifth wheel 2 is forced against the surface and an ancillary axis of rotation for the hospital bed 1. is created. In this position the fifth wheel 2 is forced against the surface by a force transferred via the mechanism described below.

On the side of the hospital bed where drawbar 5 runs through the chassis 3, there is a holder 6 which constitutes the first point of support for the profile 8, which is located here in the first check ring 1_1. The first check ring 1 is fitted firmly to the holder 6 and constitutes a support for the profile 8. The support member 9 is then inserted into holder 6, as is evident in fig. 4. Support member 9 is fixed in relation to holder 6 firmly and comprises an opening for the insertion of a flexible member 10.

Fig. 5 shows a second holder 7 connected to the other side of the frame of the chassis 3. The second holder 7 comprises a second check ring .12. The profile 8 is connected on this side with the flexible member 10 via the connecting segment 13. The connecting segment 13 is made in such a way that its prongs fit into the notches of profile 8, and the connecting segment 13 also comprises two notches into which the flexible members 10 fits.

On the first end of the fifth wheel 2 assembly shown in fig. 4 the flexible member 10 is fixed in respect to the frame of the chassis 3 of the hospital bed 1 via the holder 6. On the other end of the fifth wheel 2 assembly, which is shown in fig. 5, the flexible member 10 is fixed in in respect to profile 8 via the connecting segment 13. The flexible member 10 is configured in such a way that it creates a moment of force which causes the rotation of profile 8 and thus forcing the fifth wheel 2 towards the surface.

The flexible member 10 consists of a shaped solid bar which is rotated inside profile 8 in such a way that it creates a moment of force for the rotation of profile 8 and the forcing of the wheel 2 onto the surface. It is retained in this rotated state using its firm fixing to the support member 9 and on the other side to the connecting segment 13. So this shaped rotated rod has the function of a torsion spring. In an alternative embodiment it is possible to use a torsion spring instead of a shaped rod. It is evident to person having ordinary skill in the art how to set such a torsion spring so that it fulfils the function of forcing the fifth wheel 2 in the direction of the surface. In an another alternative embodiment it is possible to use a regular spring attached at one end to a suitable place on the frame of the chassis 3 and to the profile 8 at the other end.

Fig. 3 shows the means of putting the fifth wheel 2 into motion and the transfer of force to the rotation of profile 8. According to the invention the fifth wheel 2 can be controlled directly by any brake pedal 4. This is accomplished by the connection of the fifth wheel 2 system to the drawbar 5 running along one side of the chassis 3. The connection can be realized via several means, shown in fig. 3. These connection means comprise the cam 14, first guiding member 15, second guiding member 16 and lever 17. The cam 14 is firmly fixed to the drawbar 5, so after the activation of any pedal in the direction of brake blocking, the drawbar 5 and consequently the cam 14 both shift in relation to the first guiding member 15. The first guiding member 15 is firmly attached to profile 8 via the lever 7. The guiding member is connected to lever 17 via a free axis of rotation so it can rotate. In a preferred embodiment the pedal 4 can have three positions, in which the first position is configured for braking, the second for brake release, and the third for activation of the fifth wheel 2.

As you can see in fig. 6, the cam 14 is shaped in such a way that when the lever 17 and cam 14 move towards each other, the first guiding member 15 is raised in relation to the drawbar 5 because it goes upwards along the groove in the cam 14 due to the free rotation of the first guiding member 15. The precise groove in the cam 14 can be adapted to three-position control of the pedal 4 so the movement of the fifth wheel 2 towards the surface occurs only in the required mode of the pedal 4. From the bottom of the cam 14 a second guiding member 16 is located which prevents the drawbar 5 with the cam 14 from dropping in relation to the resistance which is generated by the system of the lever 17, profile 8 and flexible member 10. The second guiding member 16 is connected with the holder 6 via a free axis which allows the second guiding member 16 to rotate while supporting the cam 14. which slides along it and also constitutes a firm support for the cam 14. In general the guiding member can be formed by a roller, roller with groove or gear wheel. A person having ordinary skill in the art may use any shape manufactured from a material with good low-friction properties as the guiding member 16. The surface and shape of the cam 14 may be adapted to these individual variants.

From the description of the invention above it is evident that when the pedal 4 is moved, the profile 8 rotates and so the fifth wheel 2 moves between the use and storage position. Moreover in the lower use position the fifth wheel 2 is forced down onto the surface by the flexible member 10 so that contact with the surface is always achieved even under adverse conditions, such as an uneven or slippery surface.

As you can see in fig. 7, in an alternative embodiment the position of the cam 14 and the first guiding member 15 can be the other way round. The first guiding member 15 with the free axis of rotation can be connected to the drawbar 5, and the cam 14 can be firmly fixed to the lever 17.

In a preferred embodiment the entire mechanism, including the drawbar 5, can be integrated into the frame of the chassis 3, and in this case it is not necessary to have a second guiding member 16 because the drawbar 5 can have support in the actual frame of the chassis 3.