WO2004067879A1

WO2004067879A1 - Safety cushion apparatus

Info

Publication number: WO2004067879A1
Application number: PCT/GB2004/000370
Authority: WO
Inventors: Timothy John Friend; Matthew Sillifant
Original assignee: Safety Arrest Solutions Limited
Priority date: 2003-01-29
Filing date: 2004-01-29
Publication date: 2004-08-12
Also published as: GB0301974D0; GB0401915D0; GB2397847A; GB2397847B

Abstract

The present invention provides portable safety cushion apparatus for use below a workplace for arresting the fall of an object. It comprises a cushion having upper (11) and side faces (13) and a generally planar lower face (12) that is positioned on a surface. The upper, lower and side faces are formed from a lightweight flexible material and together define a single inflatable chamber (14). One or more face is provided with a plurality of apertures (18) that allow the controlled escape of air from the chamber. The apparatus also comprises an air pump (16) that continuously pumps air into the cushion to inflate it. In normal use when inflated the rate of air inflow from the pump is equal to the rate of outflow of air through the apertures, but when an object (20) falls upon the cushion the rate of air flow through the apertures increases such that the cushion deflates and slows the descent of the object to lower it to the surface without causing more than minimal rebound. The present invention also relates to a method of decelerating a falling object.

Description

Safety cushion apparatus

The present invention relates to safety cushion apparatus and in a particular embodiment to safety cushion apparatus for use when constructing buildings. It further relates to a method of safely decelerating a person or object falling from a raised platform or workplace.

In many fields there is a need for safety equipment to prevent personal injury caused by falling from heights. This need is particularly acute in the construction or fabrication industries where workers routinely work on scaffold constructions or at other exposed heights where the risk of falling and consequent injury is high. It is standard practice to provide the external face of a scaffold with netting and boards to prevent outward falls, with inward falls being prevented by the wall against which the scaffold is erected. Unfortunately, the fitting of a scaffold with suitable netting or other existing restraints may be a time consuming and/or labour intensive operation.

Furthermore a European Directive (2001/45/EC) sets out new guidelines relating to working at height, and states that the work equipment most suitable to ensure and maintain safe working conditions must be selected. Installation of safeguards to prevent or arrest falls must be of suitable configuration and sufficient strength to preclude injury to workers.

In many situations, especially the construction of new houses, external scaffolds may prevent the outward falls, however little or no protection is afforded for a worker from a fall into the confines of a building, either through apertures such as windows, down through roofs, or simply over the top of a wall that is being constructed. As such the safety of the workers is still at risk even if exterior scaffold netting is set up, because an internal scaffold and/or associated net are not provided either because they obstruct ongoing internal construction or because their erection would slow the building process and add considerably to the cost. In other circumstances workers may also be working at height and therefore will be at risk of injury from falls, and those situations may not even permit the use of existing restraints such as nets. In such situations, especially where the time that a worker is in any one position may be short, setting up complicated mechanisms for fall arrest may be totally impractical, which means the safety feature will either be omitted at the risk of injury to the worker, or that the time taken to complete a job will be increased uneconomically. Attempts have been made to overcome these problems by providing a multi-cellular air bag that can be arranged below a location at which a person will be working at height. Such an arrangement was described in EP 983,776 but this has significant drawbacks. Firstly such a design is complicated and time consuming to set up, as it requires complex interconnected valve arrangements between the cells. Secondly the internal cellular arrangement increases both the weight and volume of the deflated device making it cumbersome to handle. Thirdly and most importantly, the rate of deceleration is quite rapid and there exists a very real possibility that a person falling thereon will rebound and bounce off thereby still suffering injury; and fourthly a person falling between adjacent elements may not be properly decelerated due to the cells tending to move apart.

It is an aim of the present invention to provide an inflatable fall arrest apparatus that will by controlled deflation safely decelerate a person or object falling thereon without causing any more than minimal rebound or bounce. It is a further aim to provide such apparatus that is simple and quick to set-up, take down and transport.

Therefore according to the present invention there is provided safety cushion apparatus for temporary use on a surface below a workplace for arresting the fall of an object from that workplace, comprising a cushion having upper and side faces and a generally planar lower face that is positioned on the surface, the upper lower and side faces all being formed from a lightweight material and together defining a single inflatable chamber, one or more face being provided with a plurality of apertures therethrough that permit the controlled escape of air from the interior of the cushion; and an air pump adapted to continuously pump air into the cushion to inflate it, whereby in normal use when inflated the rate of air inflow from the pump is equal to the rate of outflow of air through the apertures, but when an object falls upon the cushion the rate of air flow through the apertures increases such that the cushion deflates and slows the descent of the object to lower it to the surface without causing more than minimal rebound.

Whilst a small degree of rebound does not detrimentally affect the present invention, it is highly preferred that the cushion is adapted such that when an object falls thereon substantially no rebound is caused.

The term object as used herein to describe what falls onto the cushion is intended to encompass anything that could benefit from deceleration by the present invention should it fall from a raised location or workplace. In practice the purpose of the present invention is predominantly to protect the health and safety of human workers in raised locations and the term object includes people. Furthermore any reference to a workplace being raised indicates that there is a height difference between that workplace and an adjacent surface. This usually means the workplace is raised from the ground, but can also mean that workplace is above a drop into for example a hole. The number, arrangement and positioning of the apertures on the cushion is important to ensure an appropriate rate of deflation to affect a safe capture and subsequent safe rescue when an object falls thereon, whilst maintaining normal air flow/leakage during the cushion's normal state. The apertures may be provided in a regular arrangement, and may be preferably provided on the upper and/or side faces. However, the position, number, shape and size of the apertures will vary according to the size and shape of the cushion and the kinetic energy that the cushion is designed to dissipate from the falling object

In some circumstances, the apertures may be round in shape and each from 5mm-15mm in diameter. Alternatively, fewer larger apertures may be provided, and these larger apertures may be best positioned on the side face of the cushion. The apertures can be covered in a mesh, to control the loss of air and prevent ingress of foreign matter. The apertures may be provided with flow regulator means that may be responsive to increase in internal pressure or air flow rates through the apertures such that the maximum flow through an aperture may increase as necessary upon impact of an object. Such flow regulator means may take several forms but it has been found convenient to provide one or more aperture with a pivoting (possibly weighted) cover that closes or restricts the aperture during normal use but opens upon impact to allow an increase in the rate of air outflow.

The material from which the cushion is formed may be gas porous or sufficiently gas permeable that it provides the outflow performance of one or more aperture. Indeed with an appropriate material the permeability of the material would obviate the need for specifically formed apertures. The material may also be flame retardant.

When inflating the cushion the rate of air inflow must exceed outflow, but when in a steady inflated state the rate of inflow must match the outflow. To help in achieving this, the air pump (or blower) may be controlled to vary the rate of air flow into the cushion.

The material from which the safety cushion is constructed must be lightweight but sufficiently durable to withstand the wear and tear that would normally be expected within the environments in which it is used. If the material is heavy the internal pressure required to cause normal inflation is higher, and the desired deflation profile is not achieved. Furthermore heavyweight material significantly reduces the ease of set up and disassembly as well as the effort of transporting the apparatus between different areas of use, especially as there is a safety Directive relating to the maximum weight a single person can carry. It is therefore highly preferred that the lightweight material that the cushion is formed from is airbag material. The term airbag material includes synthetic woven materials such as those well known in the appropriate field.

Dependant on its construction and location of use the cushion may be constrained laterally and/or vertically during use in order that it is not too distorted when an object falls thereon. It is preferable that internal tie members extending between opposite or adjacent faces, such as the upper and lower faces, are provided in the chamber. These help to ensure that when inflated the cushion maintains an appropriate form which is usually with a generally flat upper face. When an object falls onto the cushion, the natural tendency is for the cushion to either spread outwards, or for the outer edges of the cushion to lift into the air. Too much of this deformation would have a detrimental effect upon the function of the cushion. It is also possible to provide means by which the cushion may be anchored to the surface on which it rests.

The shape that the cushion adopts when inflated should be appropriate to the function that it is intended to perform and the location in which it is to be used. As such each cushion may be custom built for each specific application. As the primary, although not exclusive, intended use of the safety cushion is in the construction industry it is preferred that the cushion when inflated is shaped to fit within the walls of a building. This will both afford protection to all of the available floor space, and also ensure that the cushion is suitably constrained by the walls.

In situations where the cushion is to be erected outdoors, or where there are no walls to constrain the cushion, such as during boat construction the cushion may be constrained laterally by interconnecting opposite or adjacent side faces with lengths of a lightweight tensile material. Alternatively, the cushion may be laterally constrained by separate formations such as a surrounding scaffold box.

The dimensions of the cushion in the horizontal axes depend on the nature of the intended function, and to some degree so does the dimension in the vertical axis. However, it is preferably intended that the cushion be adapted to decelerate an adult person falling thereon from a height from their impact speed down to a speed at which it is safe to impact the surface. Of course, the cushion can be adapted for each specific use, depending upon the size and weight of the object and the height that the object will be from the surface. It is possible that two or more cushions may be stacked upon one another to catch objects that are of significant weight, or are falling from a great height, the deformation and deflation occurring in each cushion.

It is also possible to provide the device with suitable sensing or alarm means to monitor equipment status and indicate for example if the cushion is in a properly inflated state. The cushion may be provided with a visual inflation indicator that is adapted to adopt a certain configuration when the cushion is sufficiently inflated. This might take the form of an inflatable projection that will only inflate to a fully erect position when the cushion is inflated to its steady state condition. This provides a visual indication of inflation state.

The cushioning effect of the present invention may be improved by partially filling the chamber with an impact absorbent material. Also a layer of impact absorbent material such as foam may be arranged next to the lower face. These will help to further soften the contact of an object with the surface.

According to the present invention there is also provided a method of protecting a person working at height above a surface, comprising the steps of:

- providing on the surface an inflatable cushion having upper and side faces and a generally planar lower face that is positioned on the surface, the upper lower and side faces all being formed from a lightweight material and together defining an inflatable chamber, one or more of the faces being provided with a plurality of apertures therethrough that permit the controlled escape of air from the interior of the cushion;

- providing an air pump adapted to continuously pump air into the cushion to inflate it, the rate of air flow from the pump being adjustable such that it may be increased when initially inflating the cushion; and when the desired degree of inflation and internal pressure of the cushion are reached the rate of air inflow from the pump may be reduced such that the cushion remains inflated and adopts a steady state condition where air outflow and inflow are balanced and the desired internal pressure is maintained; and

- as required decelerating a person falling toward the surface from a falling speed down to a slower final impact speed at which it is safe for that person to impact the surface, by ensuring that the apertures permit and control the rate of deflation of the cushion when a person falls upon the cushion such that the rate of air flow through the apertures increases and the cushion deflates and slows the descent of the person without causing any more than minimal rebound.

The present invention provides a device that improves safety of a person working at height by providing a much improved device to arrest their fall. However, more than that, as compared to the prior art it also aids in the recovery of that person who may have suffered other injuries before or during their fall. Because the person is lowered to the floor they are made stable, and the cushion may be quickly (and if needed automatically) fully deflate to aid access to that person by rescuers. In order that it may be better understood, but by way of example only, the present invention will now be described in more detail with reference to the accompanying drawings in which:

Figure 1 is a schematic cross-section of an embodiment of the present invention in a normally inflated state; Figure 2 is a similar view to that of Figure 1 but with an object impacting the cushion;

Figure 3 is a cross-section through a building under construction with a second essentially identical embodiment of the present invention located on the ground floor; Figure 4 is a cross-section of the same embodiment but located on the first floor of the building;

Figure 5 is a plan view of a third embodiment of the present invention located within the external walls of a building under construction;

Figure 6 is a plan view of a fourth embodiment within a differently shaped house also under construction;

Figure 7 is a perspective view of a fourth embodiment of the present invention;

Figure 8 is an internal view of the embodiment of Figure 7; and

Figures 9A, 9B and 9C are various alternative embodiments of aperture.

In Figure 1 there is shown a first simplified embodiment of the present invention in a normal inflated state. The safety cushion apparatus shown comprises a cushion generally indicated 10 having an upper face 11 , a lower face 12 and side faces 13. The upper face, the lower face and the side faces together define a chamber 14 into which air is continuously delivered from a pump in the form of a blower 16 through a connecting tube 17.

Distributed over the upper face 11 of the cushion 10 there are a plurality of apertures 18 which allow air within the chamber 14 to escape. The rate at which air escapes (outflow) is dependent on the combined area of the apertures and the pressure within the chamber. During inflation of the cushion, once it has been unpacked and arranged within the appropriate working environment, the rate of inflow of air from the blower (as indicated by arrow A) exceeds the rate of outflow through the apertures 18 (indicated by the combined effect of arrows B). When a suitable degree of inflation has been achieved, the rate of inflow is adjusted to ensure that it is substantially the same as the rate of outflow, such that a steady state position can be reached. This steady state position is depicted in Figure 1 wherein A = B. The safety cushion apparatus is intended to arrest or decelerate the fall of an object such that when it impacts the ground, it does so at a speed that is not liable to cause injury. As depicted in Figure 2, when an object (schematically represented as sphere 20) falls onto the cushion 10 the downward force causes a distortion and volumetric reduction of the cushion. These increase the pressure within the cushion and hence the rate of outflow through the apertures 18 such that it is greater than the rate of inflow. Instantaneously on impact of an object with the cushion, the cushion distorts and the resultant volumetric reduction and pressure increase cause an up- thrust which slows the rate of descent of the object. It is this instantaneous distortion and pressure increase that slows the fall, and the outflow from the apertures that dampens any excessive rebound. The number and size of apertures are selected such that at steady state conditions the weight of the object will not be supported, therefore after all or most of the kinetic energy of the object has been dissipated the cushion will slowly deflate to lower the object to the floor.

After impact the rate of outflow will exceed inflow, but must not exceed it by too large a degree else the cushion 10 will deflate too fast. Between the periods of steady state activity as shown in Figure 1 and the time when an object falls onto the cushion in Figure 2 the rate of inflow (A) does not alter, therefore to achieve the appropriate relative flow rates the total outflow (B) must increase. Bearing in mind that the total area of the apertures does not alter the speed of air flow therethrough must increase. This increase is consequent upon the increase in pressure within the chamber 14 which results from its compression by the falling object 20. In the situation depicted in Figure 2 the balance of air flow can be depicted by the following equation

Air outflow (B) > Air inflow (A). Of paramount importance in the present invention, is its ability to reduce or prevent possibly harmful rebound of an object falling thereon. This is achieved in practice by having the cushion constructed from a relatively lightweight but strong material (in practice airbag material has proved particularly well suited) inflated by a constant inflow of air such that the internal pressure is not normally that high, but rises during object impact to slow that fall, then drops to lower the object to the ground. In comparison to the prior art the present invention ensures that the downward movement of an object is accommodated by essentially continual, but slowing, deformation of the cushion. In consequence little or no recoil or rebound is encountered.

Figure 3 shows a second embodiment of the present invention that is substantially the same as that shown in Figures 1 and 2, and therefore like reference numerals will be used to describe like parts. In this Figure the cushion 10 is arranged on the lower floor 25 of a building generally indicated 26. The blower 16 is located externally of the house, and is in gaseous communication with the cushion by the connecting tube 17. The tube 17 passes in through a convenient opening such as a window or a door. In such situations as depicted in Figure 3, and indeed Figures 4 and 5, scaffolding is likely to have been erected around the external walls of the building 26, but for convenience such scaffolding has been omitted from these drawings.

In Figure 4, the cushion 10 is located on the first floor 27 of the house 26 to prevent injury or damage from objects falling thereon. In this situation the blower 16 is located on the ground floor 25 and is connected to the cushion by a somewhat longer connecting tube 17.

As previously mentioned, it is desirable that the cushion 10 of any particular safety cushion apparatus be adapted to locate within the walls of a building under construction. In many circumstances, such a shape would be quite irregular both due to non-linear external walls and possible internal obstructions such as dividing walls. Figures 5 and 6 each show different possible embodiments of the present invention, which have each been adapted to locate within particular floor plans. In each case, being a plan view, the arrangement of apertures 18 over the upper surface 11 is visible. In each of these embodiments the arrangement is a generally regular grid formation, however it is not necessary for such an arrangement to be employed. The only requirement is that the apertures are sufficiently spaced to ensure correct deflation when an object falls on any part of the cushion, as well as ensuring that the formation of the apertures does not result in undue weakening of the material and the consequent risk of rupture.

Figures 7 and 8 show different views of a fourth embodiment of the present invention which is similar to the previous embodiments and, where possible, like numerals will be used to describe like parts. The cushion has an upper face 11 , lower face 12 and side faces 13 that are formed from a flexible lightweight material and together define a chamber 14. As seen in Figure 8 inside the chamber 14 tie straps 30 extend between the lower face 12 and the upper face 11 and limit their degree of separation. By providing multiple tie straps across the plan area of the cushion, the shape of the cushion when inflated is properly controlled and constrained. In this fourth embodiment generally rectangular apertures 31 are located on the side faces 13, and each is covered by a fine mesh that permit air flow. An enlarged view of the aperture 31 is shown in Figure 9A and the mesh 32 that covers it is also more clearly visible. In practice the mesh would be stitched or glued to the edges of the aperture. Figures 9B and 9C show alternative embodiments of aperture similar to that shown in Figure 9A, but these are additionally provided with two examples of flow control means. In Figure 9B a pivoting cover 33 is attached to the upper edge of the aperture and hangs under gravity over the mesh 32. This restricts air flow through the aperture, however when pressure within the cushion increases sufficiently (such as on impact of a falling object) the cover will pivot upwards and allow a greater rate of air flow through the aperture. In Figure 9C a similar pivoting cover 34 is employed, but the free ends of this are connected by a concertina side panel 35 to the short sides of the aperture. These side panels fold as appropriate as the cover 34 moves. The covers 33, 34 could also be provided with catch means to hold them fully closed for longer than they would under gravity. No catch mechanisms are shown in the drawings, but they might include two part hook and loop fasteners or compatible magnets attached to the free edges of the covers and the corresponding edges of the aperture.

In use, the simple formation of the present invention allows a fully deflated cushion to be easily and compactly stored and transported. Therefore, it is possible both to swiftly and reliably unfold and inflate a suitably configured cushion by one man in a short space of time.

Claims

1. Safety cushion apparatus for temporary use on a surface below a workplace for arresting the fall of an object from that workplace, comprising a cushion having upper and side faces and a generally planar lower face that is positioned on the surface, the upper lower and side faces all being formed from a lightweight material and together defining a single inflatable chamber, one or more face being provided with a plurality of apertures therethrough that permit the controlled escape of air from the interior of the cushion; and an air pump adapted to continuously pump air into the cushion to inflate it, whereby in normal use when inflated the rate of air inflow from the pump is equal to the rate of outflow of air through the apertures, but when an object falls upon the cushion the rate of air flow through the apertures increases such that the cushion deflates and slows the descent of the object to lower it to the surface without causing more than minimal rebound.

2. Safety cushion apparatus as claimed in claim 1 , wherein the cushion is adapted such that when an object falls thereon substantially no rebound is caused.

3. Safety cushion apparatus as claimed in claim 1 or claim 2, wherein the apertures are provided in a regular arrangement.

4. Safety cushion apparatus as claimed in any of the preceding claims, wherein the apertures are provided on both the upper and side faces.

5. Safety cushion apparatus as claimed in any of the preceding claims wherein one or more aperture is provided with flow regulator means that is adapted to open in response to a sufficient rise in internal pressure.

6. Safety cushion apparatus as claimed in claim 5, wherein the flow regulator means comprises a weighted pivoting cover on the outside of aperture.

7. Safety cushion apparatus as claimed in any of the preceding claims wherein the material forming the faces is porous.

8. Safety cushion apparatus as claimed in any of the preceding claims wherein the air pump may be controlled to vary the rate of air flow into the cushion.

9. Safety cushion apparatus as claimed in any of the preceding claims wherein the lightweight material that the cushion is formed from is a synthetic woven fabric such as airbag material.

10. Safety cushion apparatus as claimed in any of the preceding claims wherein the cushion when inflated is shaped to fit within the walls of a building under construction.

11. Safety cushion apparatus as claimed in any of the preceding claims wherein the cushion when inflated is laterally constrained.

12. Safety cushion apparatus as claimed in any of the preceding claims wherein flexible tie members extending between faces are provided internally to the chamber.

13. Safety cushion apparatus as claimed in any of the preceding claims wherein the cushion may be anchored to the surface on which it rests.

14. Safety cushion apparatus as claimed in any of the preceding claims wherein the cushion is partially filled with impact absorbent material.

15. Safety cushion apparatus as claimed in any of the preceding claims wherein a layer of impact absorbent material is arranged next to the lower face.

16. Safety cushion apparatus as claimed in any of the preceding claims wherein the cushion is adapted to decelerate an adult person falling from a height from their impact speed down to a speed at which it is safe to impact the ground.

17. Safety cushion apparatus as claimed in any of the preceding claims, which is further provided with sensing and/or alarm means to monitor equipment status and indicate excessive variation from the correct operational inflated state.

18. Safety cushion apparatus as claimed in any of the preceding claims wherein there is further provided a visual inflation indicator that is adapted to adopt a certain configuration when the cushion is sufficiently inflated.

19. A method of protecting a person working at height above a surface, comprising the steps of:

- providing on the surface an inflatable cushion having upper and side faces and a generally planar lower face that is positioned on the surface, the upper lower and side faces all being formed from a lightweight material and together defining an inflatable chamber, one or more of the faces being provided with a plurality of apertures therethrough that permit the controlled escape of air from the interior of the cushion; - providing an air pump adapted to continuously pump air into the cushion to inflate it, the rate of air flow from the pump being adjustable such that it may be increased when initially inflating the cushion; and when the desired degree of inflation and internal pressure of the cushion are reached the rate of air inflow from the pump may be reduced such that the cushion remains inflated and adopts a steady state condition where air outflow and inflow are balanced and the desired internal pressure is maintained; and