Shock mitigation seat and shock monitoring system

Abstract

A shock mitigation seat 10 includes a plurality of individual shock absorbing members 16 resilient to compression from a shock impact. The shock absorbing members 16 are positioned one adjacent another and such that at a certain stage of compression an individual shock absorbing member 16 resiliently deforms and comes into contact with one or more adjacent individual shock absorbing members 16 which thereby increases resistance to further compression. The seat may be incorporated in a shock mitigation system 50 which has at least one sensor operable to detect a force and to provide a feedback signal indicative of the nature of the force and a memory record the incidence and severity of these forces and provides an indication of cumulative forces absorbed.

Claims

1. A shock mitigation seat including a plurality of individual shock absorbing members resilient to compression from a shock impact, the shock absorbing members being positioned one adjacent another and such that at a certain stage of compression an individual shock absorbing member resiliently deforms sufficiently to come into contact with one or more laterally adjacent individual shock absorbing members which thereby increases its resistance to further compression, wherein the general configuration of at least one shock absorbing member is in the form of an annulus of resilient material.

2. The shock mitigation seat according to claim 1, wherein shock absorbing members are generally circular in cross-section.

3. The shock mitigation seat according to claim 1, wherein at least one of the shock absorbing members has at least one cross-sectional strengthening rib.

4. The shock mitigation seat according to claim 3, wherein the thickness of the cross-sectional strengthening ribs is between 1 mm thick and 5 mm thick.

5. The shock mitigation seat according to claim 1, wherein the shock absorbing members are supported on a foot.

6. The shock mitigation seat according to claim 5, wherein the foot comprises a planar sheet of a flexible material.

7. The shock mitigation seat according to claim 5, wherein the foot is rectangular and contacts an adjacent foot which supports an adjacent shock absorbing member.

8. The shock mitigation seat according to claim 7, wherein adjacent feet are offset or staggered with respect one to another.

9. The shock mitigation seat according to claim 7, wherein adjacent feet are interconnected.

10. The shock mitigation seat according to claim 9, wherein adjacent feet are interconnected by way of a hinge.

11. The shock mitigation seat according to claim 10, wherein the hinge comprises a length of wire or flexible line.

12. The shock mitigation seat according to claim 1, wherein a foam layer is placed thereon and/or thereunder.

13. The shock mitigation seat according to claim 12, wherein the, or each, foam layer is removable and replaceable.

14. The shock mitigation seat according to claim 1, which is shaped and dimensioned for use on a cycle or motorcycle or mountain bicycle.

15. The shock mitigation seat according to claim 1, which is shaped and dimensioned for use in an off-road vehicle.

16. The shock mitigation seat according to claim 12, wherein the thickness of each layer of foam is between 5 mm thick and 50 mm thick.

17. The shock mitigation seat according to claim 1, further comprising first and second layers of shock absorbing members, wherein the resilient material forming the first layer has a first shock absorbance characteristic and the resilient material forming the second layer has a second shock absorbance characteristic.

18. The shock mitigation seat according to claim 1, wherein the shock absorbing members are coated with a fire retardant.

19. The shock mitigation seat according to claim 1, wherein sections of resilient materials are extruded.

20. The shock mitigation seat according to claim 1, wherein the shock absorbing members are ellipsoid in cross section.

21. The shock mitigation seat according to claim 20, wherein major axes of adjacent ellipsoids are perpendicular one to another.

22. The shock mitigation seat according to claim 1, wherein a rheological fluid is included in a sealed container housed within at least one section of a shock absorbing member in order to provide an active force absorbing device.

23. The shock mitigation seat according to claim 22, wherein the rheological fluid includes a ferromagnetic material, such as iron filings.

24. The shock monitoring system includes the shock mitigation seat according to claim 1 and at least one sensor which is operable to detect a force, such as compressive force, a tensile force, a twisting or torsional force and an acceleration force, and to provide a feedback signal indicative of the nature of the force.

25. The shock monitoring system according to claim 24, further comprising a processor and a memory, the processor is operative to monitor the feedback signals and derive a value which is indicative of a maximum shock load (impulse) which exceeds a user defined threshold; and a cumulative load which is indicative of a total of shock loads (vibration forces), to which a seat occupant has been subjected in a predefined time, and the memory records the maximum shock load and the total shock load.

26. The shock monitoring system according to claim 25, further comprising a wireless transmitter which is operative to transmit signals from the memory which include maximum shock load data and total shock load data to a remote receiver for storage on a database, analysis by a computer or presentation on a display.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagrammatic cross-sectional view of an embodiment of a shock mitigation seat according to the present invention:

(2) FIG. 2 is a part cut-away perspective view of the seat illustrated in FIG. 1:

(3) FIG. 3 illustrates eight variations in the configuration of individual shock absorbing members;

(4) FIG. 4 illustrates the interaction between adjacent shock absorbing members as they are subject to compression;

(5) FIG. 5 illustrates an embodiment in which a spring is added to assist in a rapid return of a shock absorbing member to its initial configuration;

(6) FIGS. 6A and 6B show overall diagrammatic views of one example of a shock measurement and monitoring system may be employed with the shock mitigation seat; and

(7) FIG. 7 is a graph that depicts the compression of one embodiment under loading when compared to conventional foam material.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

(8) Referring to the diagrammatic view of FIG. 1, there is shown a cross-sectional view of an embodiment of a shock mitigation seat 10 according to the present invention. The seat 10 comprises a shaped block of conventional cushion foam 12 in the underside of which is a rectilinear recess 14 housing a plurality of shock absorbing members 16. In this embodiment the recess 14 is closed, and the shock absorbing members 16 rest upon, a solid base 18 which may be, for example formed of plywood or a resiliently deformable substrate formed from a synthetic plastics material

(9) The whole is encased in a conventional cloth material (not shown) and optionally covered with cushioning or foam. The base 18 is not an essential feature as the shock absorbing members 16 could be simply retained in position by the cloth material. In such a case, seat 10 is placed on a solid surface of the vehicle or craft in which it is to be used.

(10) FIG. 2 is a part cut-away perspective view of the seat 10 illustrated in FIG. 1. As illustrated in FIG. 2, there are a plurality of shock absorbing members 16 in both a longitudinal direction (a) and lateral direction (b). Five rows of shock absorbing members 16 extending in lateral direction (b) are illustrated. Instead of each row consisting of a plurality of shock absorbing members 16, each row could consist of a single elongate member. Alternatively, two or more shorter elongated members could be substituted in each row. Alternative combinations may enable two or more shorter members to form one row whilst an adjacent row is defined by a single member and this pattern is repeated. The particular combination of members being dictated by the nature of the loads, the type of vehicle in which shock mitigation seats are deployed and cost of materials.

(11) As illustrated in FIGS. 1 and 2, not all of the shock absorbing members 16 are of the same configuration. The arrangement shown is beneficial but not essential. Indeed, the configuration of any individual shock absorbing member 16 can take many different forms. FIG. 3 illustrates some of the different configurations which can be used. Although they are preferred forms, the shock absorbing members 16 illustrated in FIGS. 1, 2 and 3 are not of the most basic configuration which can be used.

(12) As shown, they all have integral upper and lower flat “platforms”. The underlying basic shape could, in most cases, be described in very simple terms as: having an “I” beam cross-section in which the central upright is replaced by an “O”. However, the “platforms” (or horizontals of the “I” beam shape) are beneficial but not essential. In a very basic form, the shock absorbing members 16 could be lengths of a circular or oval cross-section tube.

(13) Importantly shock absorbing members 16 are capable of resilient compression by a shock impact. The shock absorbing members 16 are positioned one adjacent another and are such that at a certain stage of compression an individual shock absorbing member 16 resiliently deforms and comes into contact with one or more adjacent individual shock absorbing members 16 which thereby increase its resistance to further compression.

(14) The material used to fabricate the shock absorbing members 16, as well as the relative dimensions of their structure, are chosen in accordance with the maximum “g” force (magnitude of shock impact) that the seat is designed to cope with an expected occupant mass In the art and industries, the most often quoted categories are: 3 g, 4 g, 5 g, 6 g, 8 g and 10 g—where “g” is sometimes referred to as “nominal peak acceleration” and the usual “nominal impact duration” is taken as 0.1 second. These are the standards often used in test rig apparatus. They are the half-sine pulse shapes in laboratory tests to simulate typical vertical wave impact severities observed in mono-hull planing craft during high speed operations in rough seas.

(15) For example, it is considered that commercial and leisure boats should be capable of withstanding 5 g shocks, search and rescue boats 6 g shocks and various classes of military boats 8 g or even 10 g.

(16) It has been found that synthetic plastics material, such as thermoplastic polyurethane (TPU) polymers, are suitable for manufacture of the illustrated shock absorbing members 16. Manufacture is typically by extrusion or injection moulding.

(17) Specific examples of thermoplastic polyurethane (TPU) polymers which have been specifically tested for manufacture of the illustrated shock absorbing members 16 are as follows. These tests were undertaken for construction of an embodiment of the invention, of the illustrated form, capable of withstanding category 6 g impacts. Such seats are considered suitable for inshore and coastal waters and a maximum speed, depending on hull type, of between 20 and 40 knots. The materials tested are: IROGRAN® A 85 P 4394 and Desmopan® 790. Both are of a similar Shore hardness. Further details of these two materials can be found on the respective manufacturer's website.

(18) Concerning typical dimensions for the illustrated shock absorbing members 16: the radius of the outer circle of the illustrated central “O” portion of the members is preferably of the order of 26 mm and the “at rest” separation between the outer circle of the illustrated central “O” portion of adjacent members is preferably of the order of mm (distance “d” in FIG. 1). The thickness of the central “O” portions and the depth, or height, of the “platforms” is preferably 4 mm. A typical width for the illustrated shock absorbing members 16 shown in FIG. 2 (i.e. in the “b” direction) is 25 mm.

(19) It will be noted that in the row of five illustrated shock absorbing members 16 shown in FIGS. 1 and 2, the central three are provided at the bottom, internally of the central “O” portions, with an integral upward projecting dome shaped bump or stop. The purpose of these bumps or stops is to reduce the effect should the shock absorbing members approach a bottoming-out compression—due to impacts beyond the anticipated maximum. Rather than the sudden limit to any further movement which occurs in the above described conventional long-travel seats (i.e. metal-to-metal contact); this variation of the shock absorbing members 16 provides a rapid increase in resistance to further compression but avoids a sudden stop. That is, the material/shape of the bump or stop is capable of compression (albeit relatively limited) and equally the then touching portion of the upper “platform” is capable of compression.

(20) One reason why the internal configuration of the two end shock absorbing members 16 shown in FIGS. 1 and 2 differs from the central three members 16 is that the compressive force likely to be experienced in those locations will differ from those experience in the central portion of the seat.

(21) It will be noted that all of the shock absorbing members 16 illustrated in the accompanying drawings have a high proportion of “open space” at the central part (or “O” portion) of their configuration. That is, the core configuration of at least one shock absorbing member is in the form of an annulus of resilient material. This is an important preferred feature of the invention. It provides a beneficial impact absorption compression of the members. In particular it enables the desired effect that, at a certain stage of compression, the individual shock absorbing member resiliently deforms and comes into contact with one or more adjacent individual shock absorbing members; which thereby increases resistance to further compression.

(22) This interaction may be more complex than might at first be imagined. FIG. 4 seeks to illustrate how the adjacent members 16 might start to interact. In FIG. 4, the notional compressive force is indicated by the curved line and arrow. The interaction is, of course, a dynamic process and as such cannot be fully illustrated by one or two drawings.

(23) Further variations and modifications are possible. Attention is here directed to example 7 shown in FIG. 3. As with examples 5 and 6, upper bumps or stops are provided. They essentially provide or duplicate the purpose and action of the lower bump or stop explained above with reference to FIGS. 1 and 2. However, in example 7 smaller bumps are provided on either side of both the upper and lower bumps or stops.

(24) The purpose of these is to assist in locating and retaining a, preferably, metal spring 20—as illustrated in FIG. 5. The purpose of introducing such a spring 20 is to enhance the return of the TPU member to its starting configuration in a timely manner. The significance of additional springs increases with the increase in impact shock frequency.

(25) Referring now to FIGS. 6A and 6B show overall diagrammatic views of one example of a shock measurement and monitoring system 50 which includes the aforementioned shock mitigation seat. By way of example reference is made to the embodiment of the shock mitigation seat 52 shown in FIG. 2. Twelve sensors S1, S2, S3 . . . S12 are distributed across the surface of the seat. The sensors are arranged in a grid of four rows of three sensors although it will be appreciated that other patterns may be used including circular patterns or different arrays of individual sensors.

(26) Sensors S1-S12 are ideally strain gauges or accelerometers and are operative to output a signal which is indicative of an applied force or load (as shown for example in the graph of FIG. 7). The signals are optionally stored in dynamic memory, such a random access memory (RAM) 54 or signals may be output directly to a microprocessor 56. The microprocessor 56 derives values from the signal, in accordance with software, and outputs signals which are indicative of individual forces experiences by one of the sensors S1 to S12, as well as an aggregate or total force to which the seat has been subjected. Optionally maximum and minimum forces which have been encountered may be provided by the microprocessor 56. Sensors include a displacement sensor and/or accelerometer.

(27) Transmitter 58 is operative to send signals to a portable electronic device 60, such as a smartphone, which is configured with application specific software (APP) in order to provide immediate feedback to a user or supervisor as to an amount of exposure to vibrational shocks, the total force endured as well as the maximum shocks measured.

(28) FIG. 7 is a graph that depicts the compression of a variant of the invention under load compared to conventional foam. FIG. 7 shows how non-linear properties are harnessed to the benefit of the seat occupant (not shown) through initial low stiffness followed by controlled increase in stiffness.

(29) It will be appreciated that the invention has been described by way of example only and variation may be made to the aforementioned embodiments without departing from the scope of the invention as defined by the claims.