GB2324131A - Joint construction for U-shaped members of a bed grab rail. - Google Patents

Abstract

A bed grab rail of L-shape comprises a base section 14 and a grab rail section 15 disposed at 90 to one another, and connected together through a straight circular section tube 16 into which ends of the base section and grab rail section extend diametrically, the sections being connected to the tube 16 by respective welds (18,21 see Figs 4 and 5). The grab rail section is formed by a U-shaped handle frictionally fitted onto a pair of spigots welded to the straight tube 16, the spigots carrying respective buffers 22 at the underside of the tube 16. In one variation, the handle can be adjustable for height.

Description

IMPROVED JOINT CONSTRUCTION This invention relates to an improved joint construction, particularly in a tubular structure, so that stiffness at the joint is increased, as compared to similar prior art structures, by controlling forces applied to the structure, in use, so that deflection of the structure is reduced.

The main intention of the present invention is to produce an improved bed grab rail device. This is a support device which is widely used in hospitals, nursing homes and residential homes to assist the occupant of a bed adjust from a lying position and/or from a sitting position to a standing position ready to leave the bed. The device, in one known embodiment, has a rectangular wooden base, from the upper surface of which, at a position at one of the shorter sides of the base, extends, at 90" to the base, an upstanding grab rail. The rail is formed by bending circular section steel tube into an inverted U-shape to form a pair of parallel straight sides with a generally semi-circular integral connecting portion at the upper end of the rail. The respective lower, free ends of the straight sides are anchored through the flat base into a wooden extension part at the underside of the base at said shorter side thereof.

In use, the device is gripped with the base disposed horizontally, and the base slipped between the mattress and the base/frame of the bed at a point which lines up with the pelvis of a prone occupant. Fixing straps around the base/frame can be used to secure the device in position.

Alternatively the device can be positioned/secured on the base/frame with the mattress removed, and the mattress thereafter replaced so as to bear on the base of the device.

A person lying in the bed can then grip one or other side of the rail and pull themselves into a seated position. Thereafter the person can manoeuvre into a seated position. Thereafter the person can manoeuvre their legs sideways, with the assistance of the device for support, to a position ready to leave the bed.

A further known form of this type of support device is shown schematically in Figures 1 and 2. The device 10 is of circular section steel tube with its ends joined together to form a continuous tubular structure bent to form a U-shaped base part 11 and an inverted U-shaped grab rail part 12 at 900 to the base part. Each integral joint/change of section between the base and the rail parts respectively is formed as a radiussed bend 13 formed, for example, by cold forming. The bend 13 is thus necessarily formed with a radius of curvature which is large compared to the tube diameter, for example 3 or 4 times larger.

Normal use of this type of support device, where the load W is applied at the top of the grab rail part 12, as shown in Figure 1, results in a torque effect (i.e. twisting and rolling) by loading the area of the bend 13, which is not stress relieved. The maximum deflection is proportional to 13, where, as shown in Figure 1, I is the distance from the position of applied load to substantially the start of the base part 12, and since this distance includes substantially all of the bend 13, such deflection is relatively large, as Figure 6 schematically illustrates. Failure of the device is thus possible.

This construction also allows for possible misuse of the device, as its permitted deflection enables it to be rocked back and forth laterally of the bed, together with a corresponding lifting of the mattress, in the manner of an exercise rocker. Such misuse could lead to 'capsizing' of the device. Moreover if an excessive load is applied to the part 12 when the bed is unoccupied, e.g. by someone standing and leaning onto the rail part, displacement of the mattress (mattress roll) can occur. A further disadvantage is limited spread of load on the base part.

An object of the invention is to provide an improved joint construction.

A particular object is to provide a bed grab rail device which reduces or overcomes the disadvantages of the prior art devices referred to.

According to the present invention there is provided a joint construction between first and second sections in a structure, the sections being at an angle to one another, and the joint construction comprising a joint member to which the sections are rigidly connected.

Preferably the sections are at 900 or substantially 90" to one another and conveniently the joint member is a straight tube of circular section.

Desirably the sections are of circular tube, extending into said joint member, and being welded thereto to provide said rigid connection.

Advantageously one of the sections is in the form of a U-shaped or generally U-shaped member, and more preferably the other section comprises a pair of spaced parallel spigots rigidly connected to the straight tube which are received in the respective open ends of a Ushaped tubular member.

The invention, in a preferred embodiment, relates to such an above defined joint construction in a (bed) grab rail device. Instead of as with the prior art devices, where tube is effectively merely bent into an Lshape, with a radius at the bend between the base and hand-grip sections, a device of said preferred embodiments incorporates a joint of the invention at the junction between the sections, the tube forming the joint functioning, in use, as a torque-tube which receives the torque produced by a loading on the hand-grip section, thereby reducing deformation through the structure, and reducing stress, so as to create a device with an improved performance load.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figures 1 and 2 are schematic side and plan views respectively of a prior art bed grab rail device in its position of use at a bed, Figure 3 is an exploded perspective view of a bed grab rail device incorporating a joint of the invention, Figures 4 and 5 are respective fragmentary sectional views showing how different parts of the Figure 3 device are connected to a tube of the joint, Figures 6 and 7 are respective diagrammatic views showing how deflection loads affect the prior art device of Figure 1 and 2, and the device of Figures 3 to 5, and Figures 8 and 9 are respective views corresponding to Figures 1 and 2, showing the device of Figures 3 to 5.

Although the present invention relates generally to an improved joint construction between first and second sections in a structure, it was developed specifically for, and has specific application to, a bed grab rail device and the invention will thus be particularly described in relation thereto.

A bed rail grab device incorporating a joint construction of the invention is shown in Figure 3. As previously mentioned, this device enables, for example patients, to pull themselves from a lying position to a sitting position, and then from a sitting position to a standing position, ready to leave the bed area. The device of Figure 3 has a basic L-shaped configuration of the same form as the prior art device referred to, namely a base section 14 and a grab rail section 15, each of the sections lying generally in a respective single plane, with the two planes being at 900 to one another. However instead of the two sections being formed integrally with a 900 curved bend between them, the device shown in Figure 3 incorporates a joint construction of the invention between the two sections, this being in the form of a straight circular section metal tube 16 of constant wall thickness, with its opposite open ends having respective closure plugs, (not shown) therein.

The base section 14 is formed of at least one, and in the illustrated embodiment, a pair of elongated generally U-shaped members 17 lying side-by-side, but spaced apart, in a common plane, the members being parallel to one another and extending at 90" relative to the axis of the tube 16. Each member 17 is formed from bending a piece of straight circular section metallic tube and for each member 17 its free end portions are received through respective correspondingly shaped circular holes in the tube 16, as shown for one free end in Figure 5, a weld 18 being provided on the exterior of the tube 16 around the free end of the member 1 7 where it passes into the interior of tube 16 so as to secure the member 17 to the tube 16 in a rigid connection.

At respective axial positions along the tube 16, two short lengths of circular section metallic tubes 19, 20, of the same form as that used for the member 17, extend through the tube 16, as shown in Figure 4, the tubes 19, 20, lying in a common plane at 900 to that containing the members 1 7. As can be seen from Figures 4 and 5, the tubes passing into/through the tube 16 are arranged radially relative thereto. As with the tube forming the members 17, Figure 4 shows that at each point of entry for either the tube 19 or the tube 20, there is an exterior weld connection, as indicated at 21, so as rigidly to secure the tubes 19, 20 to the joint construction tube 16. Each of the tubes 19, 20, is, as stated, of only very short length and in effect provide upper and lower spigots. On each lower spigot there is a secured a cylindrical rubber buffer 22, whilst the upper spigots provide fixing points for the respective open ends of a handle 23 which is of generally inverted U-shape, shorter but wider than members 17, and which is formed by bending circular-section tube. It will be appreciated that the inner diameter of the tube used for the handle 23 will be slightly greater than the exterior diameter of that used for the tubes 19, 20, but the difference will be relatively small so that when the handle is pushed down onto the upper spigots formed by the metallic tubes 19, 20, respectively, there will be a fairly tight friction fit of the handle on the spigots so that inadvertent upwards release of the handle from the spigots cannot take place. As can be seen from Figure 3, the tubes 19, 20 are axially disposed along the tube 16 so as to lie centrally between the spaced positions where the ends of a member 1 7 are connected to the tube 16. With this arrangement, therefore, the device is symmetrical about a vertical plane extending at right angles to the tube 16 and being disposed centrally between the two members 1 7.

The use of a joint construction of the invention in the bed grab rail device of Figures 3 to 5 results in an improved device which at least reduces many of the disadvantages of the prior art device referred to.

Generally, the design of this improved device resists the effect of torque, namely twisting and rolling, when a load is applied to the handle 23, by transferring the 'local' force into the tube 16 which thus acts as a torque receiving tube. As a result maximum stiffness is formed at the joint (change of section), in contrast to the prior art arrangement which has a conventional bend radius without change of section. Accordingly with the improved device, deflection may be controlled locally and progressively throughout the structure as shown in Figure 7, in contrast to the arrangement with the prior art device where deflection takes place throughout the structure.

Moreover from Figures 8 and 9, which show the device of Figure 3 fitted in position at a bed, it can be seen that the length I, for a grab handle length equivalent to that shown in Figure 1, will be smaller so that the maximum deflection will be reduced proportionately. Typically a traditional grab handle length is approximately 20% longer than the improved device shown in Figure 8. The maximum deflection for an applied load W at the handle acting over a distance 1, as shown in both Figures 1 and 8, is A1l, where E is the Modulus of Elasticity of the 3EI material and 1 is the Moment of Inertia of the cross-section considered.

Accordingly it can be seen that with a 20% reduction in the length I, there is a vastly reduced deflection, namely of the order of 50%. The joint construction thus allows critical loads to be accommodated by the 'torque' tube 16, whereas the construction of the prior art device employing purely a bend in the tube does not relieve such stress as the force is not spread in the same way as with the 'torque' tube. In particular it will be appreciated that there is no connection equivalent to that provided by the axial extent of the tube 16 which is, in effect, a lateral connection of the joint. A further advantage of the improved device shown in Figure 3 is the fact that it spreads the weight of a person lying in the bed more effectively. This contrast with the prior art arrangement can be appreciated by comparing Figures 2 and 9, in addition to Figures 1 and 8, where the distribution of the weight of the patient lying in the bed is indicated The twin base members 17 create a more even spread of load (i.e. a zone-lattice effect) and this results in a person lying in the bed feeling less of the base section of the device through the mattress. As well as the advantage of this uniform distribution of the load on the base, there is also a reduction in the maximum deflection for the base section given that this is again proportional to 13.

At a distance upwards along the handle 23 from the centre of the tube 16 substantially at the top of each metallic tube 19, 20, is a position of maximum stress, this being proportional to the length I and inversely proportional to the section modulus of the cross-section of the tube. It will thus be appreciated that as I is reduced for the improved device, the stress force will be less than with the prior art device. Moreover since at this position there is in fact the combined cross-sectional thickness of both the spigot tube and also the handle tube, the stress will be further reduced due to this increase in cross-section. Similarly at approximately the same distance from the centre of the tube 16 along each member 1 7 there is again a position of maximum stress, which stress is proportional to the length I, so that the reduction in this length will again result in a reduction in the stress force, so that in effect, the device is reinforced against breakage at either of these points of maximum stress. Since the device has three specific distinct functions, in use, all of which involve loading of the handle 23, it is clearly advantageous that the risk of failure due to application of excessive load thereon, is reduced. Firstly the device enables a person to pull themselves from a lying position to a sitting position, and then from a sitting position to a standing position, ready to leave the bed area. Secondly the device acts as a very firm and stable 'high-rail' for steadying themselves when standing by the bedside, and thirdly the device uses the persons own body weight to hold the device ' in-situ' when manoeuvring themselves around or on/off the bed.

In addition to the torque resistance/transference referred to in relation to the joint, the improved device is advantageous as follows.

The device has no sharp/protruding edges, corners and thus reduces the risk to a patient when using or lying near the device, and reduces damage to bed sheeting and the bed itself. As previously described, 'mattress-roll' i.e. displacement of the mattress, is reduced or eliminated.

Moreover the provision of the buffers and associated lower spigot tubes running parallel to and against the bed frame creates a 'square-corner' effect, as shown best in Figure 8 where the buffers engage the side of the bed frame. This is clearly in contrast to the arrangement shown in Figure 1 where there is no such 'square-corner' effect. These vertical spigots and rubber buffers act as brakes against the side of the bed frame.

In addition to the more even spreading of the load on the base, as described, the improved device also makes it extremely difficult for a patient to capsize the device even if the handrail is subjected to intensive shock loads.

Finally, in the embodiment described, the improved device is portable and removable quickly, thus allowing easy access to patients in emergencies, and for treating the patients in daily duties. With the removable handle version 23, the device can be folded flat for easy transportation and storage, and the overall tubular design allows for improved cleaning facilities and thus improved hygiene. Thus as well as the joint construction creating a higher performance load than other types of equivalent devices, the device of Figure 3 also has other practical advantages.

It will be appreciated that instead of providing a releasable handle 23 which frictionally fits onto the upper ends of the metallic tubes 19, 20, the handle could itself be directly welded or otherwise secured to the tube 16, with or without the lower spigots and buffers being provided.

The spigots/buffers could of course instead be provided separately from the handle if this were to be welded directly to the tube 16. Similarly instead of the members 17 being directly welded to the tube 16, they could, like the handle 23 be fitted at their respective open ends onto or into stub spigot shafts/tubes or the like which are themselves welded or otherwise secured to the tube 16. Apart from the buffers, all the parts are of metallic tube, such as steel, and although the construction is thus robust, it is still lightweight and aesthetically acceptable with the tubes being coated with a tough nylon finish.

Instead of the torque tube 16 being of circular cross-section, its section could be of any other suitable geometric shape, i.e. of three sides upwards. However square or rectangular cross-section is the most likely alternative to circular. Instead of being a tube, i.e. hollow, the joint member 16 could be of solid rod/bar, as could the sections 14 and 15.

The angle between the sections at the torque tube need not be 900, or substantially 90 , but can be any angle greater than zero, up to and including 1800 where the sections extend away from one another in opposite directions at opposite sides of the tube. The cross-sectional size of the component of one section need not be the same as that of the other section. The tubes 17 can be of greater diameter than the tubes 23, or vice versa.

The invention has particular application in the Medical, Homecare, Consumer, Health, and Disability fields, covering commode & toilet products, bed related products, bath products, mobility products from wheelchairs to powered scooters, tables and furniture etc.

Instead of being fixed, the handle could be adjustable. In one form, each spigot has at its upper end a hole therethrough, and the free end of each limb of the U-shaped handle has a series of longitudinally spaced holes therein, so that the height of the handle can be step-adjusted by aligning a selected hole thereof with the hole in the spigot, and then inserting a locking pin. In another form, the spigots are hollow and the free ends of the handle, with the series of holes therein, are received therewith in.

Again, a locking pin is inserted through aligned holes of the spigot and the handle when a selected hole of the handle is aligned with the hole of the spigot. In this form, the handle ends can extend through the tube 16 and out at its opposite side, at least in the lower positions of the handle, and a locking pin/clip can be engaged at the upper of said series of holes in the projecting free end so as further to fix the adjusted handle. In another embodiment, a board or like member could be provided laterally of the members 1 7 at the outer end of the base section to spread load.

The member is preferably clipped onto the members 1 7 to fix it thereto.

Claims (22)

1. A joint construction between first and second sections in a structure, the sections being at an angle to one another, and the joint construction comprising a joint member to which the sections are rigidly connected.

2. A joint construction as claimed in Claim 1, wherein the sections are at 900 or substantially 90" to one another.

3. A joint construction as claimed in Claim 2, wherein a first one of the sections comprises a U-shaped or generally U-shaped member.

4. A joint construction as claimed in Claim 3, wherein said first section comprises a pair of spaced apart, parallel U-shaped or generally U-shaped members.

5. A joint construction as claimed in Claim 3 or Claim 4, wherein each U-shaped or generally U-shaped member extends normally from said joint member.

6. A joint construction as claimed in any one of Claims 3 to 5, wherein each U-shaped or generally U-shaped member is formed of circular section tube.

7. A joint construction as claimed in any one of Claims 2 to 6, wherein a second one of the sections comprises a U-shaped or generally U-shaped handle.

8. A joint construction as claimed in Claim 7, wherein respective free ends of the handle are frictionally fitted to stub spigots extending normally from said joint member.

9. A joint construction as claimed in Claim 7 or Claim 8, wherein the handle is formed of circular section tube.

10. A joint construction as claimed in any one of Claims 3 to 6, wherein the joint member is a straight tube, and each U-shaped or generally U-shaped member has its arms extending into said straight tube and secured thereto by weld means.

11. A joint construction as claimed in Claim 7, wherein the joint member is a straight tube, and the handle has its free ends extending into said straight tube and secured thereto by weld means.

12. A joint construction as claimed in Claim 8, wherein the joint member is a straight tube, and said stub spigots extend into said straight tube, being secured thereto by weld means.

13. A joint construction as claimed in Claim 12, wherein the stub spigots extend through the straight tube, being provided with respective buffers on their free ends at the opposite side of the straight tube from said handle.

14. A joint construction as claimed in any one of Claims 8, 12 and 13, wherein the stub spigots are tubular.

15. A joint construction as claimed in either of Claims 11 and 12, wherein the handle is formed of circular section tube.

16. A joint construction as claimed in any one of Claims 10 to 13, wherein the straight tube has closure plugs in its respective ends.

1 7. A joint construction as claimed in any one of Claims 2 to 16, wherein the sections and the joint member are metallic.

18. A joint construction as claimed in any one of claims 1 to 7, wherein the second section is a handle which is height adjustable relative to the joint member.

19. A grab rail device principally for use at a bed, the device including a joint construction as claimed in any one of the preceding claims.

20. A grab rail device as claimed in Claim 19, which is symmetrical about a central longitudinal plane normal to said joint member.

21. A joint construction substantially as hereinbefore described, with reference to, and as shown in Figures 3 to 5, and 7 to 9 of the accompanying drawings.

22. A grab rail device substantially as hereinbefore described, with reference to, and as shown in Figures 3 to 5, and 7 to 9 of the accompanying drawings.