Abstract
A safety fastener and a safety system are provided. The safety fastener indicates when a fastener is damaged, and the safety system indicates when a safety critical component is damaged. The fastener includes a load bearing body that encloses an inner volume filled with fluid, and a fluid sensor that detects the presence of the fluid within the inner volume. When the fluid sensor detects the fluid, a fluid present state is activated. If the fastener is damaged, fluid may escape from the inner volume, such that the fluid sensor leaves the fluid present state, indicating damage has occurred.
Claims
1. A fastener comprising a load bearing body, wherein the load bearing body encloses an inner volume filled with fluid, and a fluid sensor configured to detect the presence of the fluid within the inner volume, the fluid sensor being further configured such that in the event of detecting the fluid, a fluid present state is activated.
2. A fastener according to claim 1, wherein the fluid sensor is wired to an external control unit.
3. A fastener according to claim 1, wherein the fluid sensor is wired to an external power supply.
4. A fastener according to claim 1, wherein the fluid sensor is wirelessly connected to an external control unit.
5. A fastener according to claim 1, wherein the fluid sensor is wirelessly connected to an external power supply.
6. A fastener according to claim 1, wherein the fastener comprises an internal power supply connected to the fluid sensor.
7. (canceled)
8. (canceled)
9. A fastener according to claim 1, wherein the fluid is held under higher than atmospheric pressure in the inner volume of the load bearing body.
10. A fastener according to claim 1, wherein the fluid is a liquid.
11. A fastener according to claim 1, wherein the fluid is a gas.
12. A fastener according to claim 1, comprising a first part and a second part, wherein the first part is mechanically joined to the second part.
13. (canceled)
14. A fastener according to claim 12, wherein the first part and second part comprise the load bearing body.
15. A fastener according to claim 14, wherein one or both of the first part and second part define the inner volume of the load bearing element.
16. A fastener according to claim 15, wherein one of the first part and second part comprise the fluid sensor.
17. A fastener as claimed in claim 1, comprising a plurality of inner volumes and at least one corresponding fluid sensors configured to detect the presence of the fluid within the inner volumes, the at least one fluid sensor being further configured such that in the event of detecting the fluid, a fluid present state is activated.
18. (canceled)
19. (canceled)
20. A fastener as claimed in claim 17, wherein the plurality of inner volumes are in fluid communication.
21. A fastener as claimed in claim 17, wherein the plurality of inner volumes are distinct inner volumes that do not connect with each other.
22. (canceled)
23. A method of detecting a crack in a load bearing body of a fastener according to claim 1, the method comprising the steps of observing the fastener, and in the event of observing the fastener is not in the fluid present state, activating an alarm signal.
24. A method as claimed in claim 23, wherein the alarm signal causes a visible or audible alarm to be triggered.
25. A method as claimed in claim 23, wherein the alarm signal causes a notification to be sent to a control unit or a smart device.
25. (canceled)
26. (canceled)
27. (canceled)
28. (canceled)
29. (canceled)
30. (canceled)
31. A method as claimed in claim 23, wherein the alarm signal causes a shutdown of a machine including the fastener.
Description
DESCRIPTION OF THE DRAWINGS
[0036] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:
[0037] FIG. 1 shows a side view of a shear bolt according to a first embodiment of the invention;
[0038] FIG. 2 shows a cross-sectional view of the shear bolt of FIG. 1;
[0039] FIG. 3 shows a side view of a threaded bolt according to a second embodiment of the invention;
[0040] FIG. 4 shows a cross-sectional view of the threaded bolt of FIG. 3;
[0041] FIG. 5 shows a side view of a threaded bolt according to a third embodiment of the invention;
[0042] FIG. 6 shows a cross-sectional view of the threaded bolt of FIG. 5; and
[0043] FIG. 7 shows a safety system according to a fourth embodiment of the invention;
[0044] FIG. 8 shows a cross-sectional view of a fastener comprising a deflector bar with multiple contact points and a plurality of inner volumes according to a fifth embodiment of the invention;
[0045] FIG. 9 shows a cross-sectional view of a fastener similar to that shown in FIG. 8, without the plurality of inner volumes; and
[0046] FIG. 10 shows a cross-sectional view of a fastener with multiple inner volumes according to a sixth embodiment of the invention.
DETAILED DESCRIPTION
[0047] FIGS. 1 and 2 show a shear bolt 10. The shear bolt 10 comprises a load bearing body 16 including an inner volume 12. The inner volume 12 is defined by an internal surface of the load bearing body 16, along with a sensor element 14 located such that the inner volume 12 is plugged so as to be fluid-tight. In this embodiment, the sensor element 14 is a pressure sensor threaded and screwed into position. In other embodiments, alternative fixing methods may be used, for example provision of an interference fit. The inner volume 12 is filled with a fluid, in this case carbon dioxide gas under pressure, and the sensor element 14 is arranged to detect the increased pressure compared to atmospheric pressure. When the increased pressure is detected, the sensor is in a fluid present state. If the load bearing body 16 cracks, such that the inner volume 12 defined by the inner surface of the load bearing body 16 is no longer fluid tight, the fluid will escape from the inner volume 12 and the sensor element 14 will no longer detect the increased pressure relative to atmospheric pressure, and will move out of the fluid present state. The sensor element 14 includes a power source and a light unit 18. When in the fluid present state, the light unit 18 is arranged to be activated to emit light. Therefore, the sensor element 14 provides a positive confirmation that the sensor is in the fluid present state. This indicates both that the sensor is working, and the shear bolt 10 is not cracked. When the light unit 18 is not illuminated, it is apparent that either the shear bolt 10 is cracked, or the sensor element 14 or light unit 18 is not functioning. In either case, the shear bolt 10 required closer inspection and possible replacement.
[0048] FIGS. 3 and 4 show a bolt 30 with a load bearing body 36, an inner volume 32 filled with fluid, and a sensor element 34. The arrangement is similar to that described with reference to FIGS. 1 and 2, though applied to a different type of fastener. The sensor element 34 includes a communications unit 38 which is arranged to send a fluid present signal when the sensor element 34 is in the fluid present state, and a fluid not present signal when the sensor element is not in the fluid present state. In this embodiment, the signal is actively sent at regular intervals. The signal is wirelessly sent via any suitable wireless communications protocol, as would be understood by a skilled person. The signal may be received by a smart device, for example a control panel or a phone or tablet device. Such an arrangement allows for remote monitoring of the integrity of a fastener where it may be difficult to visually observe the fastener. In an alternative arrangement, the communications unit 38 may be arranged to be in a passive state, where the state of the sensor element is detected by interrogation of the communications unit 38 by a suitable wireless communication device. A passive arrangement may require less power storage in the fastener than an active arrangement, which could be particularly advantageous if the fastener is not connected to a mains power supply, for example being provided with a battery.
[0049] FIGS. 5 and 6 show a bolt 50. The bolt 50 comprises a load bearing body 58 with an inner volume 52 defined by an internal surface of the load bearing body 58. A sensor element 54 is provided, which includes an elongate rod 60 which extends along the inner volume 52. When the bolt 50 is in a normal, undeformed state, the elongate rod does not contact the internal surface of the load bearing body 58. However, the spacing between the elongate rod 60 and the internal surface of the load bearing body 58 is small, such that deformation of the load bearing body 58 results in contact being made between the elongate rod 60 and the internal surface of the load bearing body 58. The internal surface of the load bearing body 58 and the elongate rod 60 are both made of conductive material, and the sensor element is arranged to run a current into the elongate rod 60 to detect contact between the elongate rod 60 and the internal surface of the load bearing body 58. In the present arrangement, when no contact is made between the elongate rod 60 and the internal surface of the load bearing body 54, the sensor element 54 is in a normal state. This normal state may result in a normal notification or signal such as a light activation as described above, being activated. As in the above embodiments, such an arrangement indicates that both the sensor element 54 is working, and the bolt 50 is undeformed. An insulating washer 56 is provided at an end of the elongate rod 60 to ensure that vibration of the bolt 50 does not cause the elongate rod 60 to touch the internal surface of the load bearing body 58, potentially causing a false indication of damage to the bolt 50.
[0050] FIG. 7 shows a safety system including a fastener 70, which may be as described with reference to any of FIGS. 1 to 6. The fastener 70 comprises a sensor element with a wireless communications unit, the wireless communications unit arranged to send an indication of the state of the fastener 70 to a receiving unit 72. The receiving unit 72 may be a control screen which forms part of a machine or structure of which the fastener 70 is a part. Alternatively, the receiving unit 72 may be a smart device, such as a phone or a tablet. In an alternative embodiment, the communications unit of the fastener 70 may be wired to the receiving unit 72.
[0051] FIG. 8 shows a fastener 80 extending between a first mounting point 82 and a second mounting point 84 of the same body. The fastener 80 is threaded (not shown) to allow engagement with complementary threads in the first mounting point 82 and second mounting point 84. The skilled person will appreciate that in alternative embodiments, the fastener may be secured by other fixing mechanism. An elongate rod 86 extends through a void 88 along the central longitudinal axis of the load bearing body 81 of the fastener 80, and forms part of a sensor assembly 90, with a detector unit 92 located at one end of the fastener 80. The elongate rod 86 is isolated from the main body of the fastener 80 by an insulated washer 94, which also acts to dampen any vibrations experienced by the fastener 80, which could potential trigger false readings. The insulated washer 94 is also configured to isolate the elongate rod 84 from deformation of the load bearing body 81 of the fastener. The elongate rod 86 further comprises a first contact portion 96, and a second contact portion 98. The first contact portion 96 is located approximately in the centre of the length of the fastener 80, and the second contact portion 98 is located closer to an end of the fastener 80. If the fastener 80 is deformed by a load placed upon the load bearing body 81, the first contact portion 96 will contact the main body of the fastener. If the fastener 80 is deformed further, the second contact portion 98 will contact the main body of the fastener. The first contact portion 96 and second contact portion 98 are electrically isolated from each other. By running a current along the elongate rod to each of the first contact portion 96 and second contact portion 98, it can be detected when the first contact portion 96 and/or second contact portion 98 touches the main body of the fastener. This may then trigger an alarm or alert as previously described, indicating the deformation of the fastener and allowing for closer inspection or replacement. By including a number of contact portions, the level of deformation may be indicated. For example, the first contact portion 96 may be configured to indicate an allowed level of deformation, whereas the second contact portion 9 may be configured to indicate the deformation has gone beyond the maximum limited and the fastener 80 needs replacement. The fastener 80 also comprises a first inner volume 100 and second inner volume 102 extending along the length of the fastener 80, towards the circumferential edge of the fastener 80 The first inner volume 100 and second inner volume 102 are in fluid communication with each other via a fluid reservoir 104. A fluid sensor 106 is associated with the fluid reservoir 104 and configured to detect a fluid present stage and a fluid not present state. When in the fluid present state, the fluid sensor 106 is configured to indicate such by activating a light, and/or transmitting a fluid present state to a remote device, for example a smart phone or computer. This provides confidence both that there is fluid present in the inner volumes 100 and 102, and the sensor 106 is operational. In the event of the fastener 80 being damaged, for example due to cracking, fluid will escape from the inner volumes 100 and 102, and the sensor will move into the fluid not present state. The fluid sensor 106 will then no longer activate a light, and/or will cease transmitting the fluid present state to a remote device, and the absence of the positive confirmation of fluid will indicate that the fastener may be damaged and requires inspection. In the event of the fluid sensor 106 failing, there will also be an absence of the positive confirmation of fluid present, which will lead to the fastener being examined and the malfunctioning sensor may be detected. As the skilled person will appreciate, the fluid may be a liquid or gas. Preferably, the fluid is present in the inner volumes 100 and 102 at a greater pressure than the ambient pressure. Therefore, if a fastener is cracked or worn such that an inner volume 100, 102, is compromised, the fluid will escape under pressure, therefore triggering a fluid not present state. By locating the first inner volume 100 and second inner volume 102 towards the circumferential edge of the fastener 80, excess wear of the fastener 80 may be detected.
[0052] FIG. 9 shows a fastener 980 extending between a first mounting point 982 and second mounting point 984 of the same body. The fastener 980 also extends through a bore 985 of a separate body 987, securing the two bodies together. The internal arrangements of the fastener 980 match those of the fastener 80 described with reference to FIG. 8, except that only the deflection bar is present, not the inner volumes filled with fluid.
[0053] FIG. 10 shows a cross-sectional view of a fastener 120 according to the present invention. The fastener 120 is a fifth wheel pin, as commonly used in the haulage industry. The fastener 120 comprises a main body 122 with a first inner volume 124 and second inner volume 126. The fastener 120 has a longitudinal axis X-X, and the first inner volume 124 and second inner volume 126 extend in the direction of the longitudinal axis X-X, towards the circumferential edge of the main body 122. The first inner volume 124 and second inner volume 126 are in fluid communication with a shared fluid reservoir 128, with fluid filling the inner volumes and fluid reservoir, and a fluid sensor 130 is positioned to plug the fluid reservoir 128. The fluid is present at a higher pressure than the ambient pressure, such that if the inner volumes are compromised, the fluid escapes. In such an arrangement, the fluid sensor 130 is a pressure sensor. The fluid sensor 130 is further configured to detect the presence of fluid within the fluid reservoir 128. When fluid is detected, the fluid sensor 130 enters a fluid present state, in which a fluid present signal is transmitted to an external monitoring device. When fluid is not detected, or when the fluid sensor 130 fails, the fluid present signal ceases transmission, thereby notifying a user of a potential problem with the fastener 120. The first inner volume 124 and second inner volume 126 are located towards the circumferential edge of the main body 122 at a position chosen to indicate a certain wear of the fastener 120. The inner volumes are small bores within the main body 122, and have little or no effect on the overall strength of the fastener 120. When the main body 122 has been worn to a set point, one or more of the inner volumes will be compromised, and the fluid present will escape pressure. This will result in the fluid sensor 130 moving to a fluid not present state, which is transmitted to a user as previously described. Therefore, excess wear of the fastener 120 is indicated without requiring constant checking of the fastener 120 during use.
[0054] Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.
[0055] A similar arrangement to that shown with respect to fasteners in FIGS. 1 to 6, may be applied to any load bearing component. For example, a similar arrangement may be applied to a wheel hub of an automotive vehicle, or any other vehicle or transportation machine. Alternatively, a similar arrangement may be applied to load bearing structures such as bridge or building components.
[0056] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.
