WO2018136982A1 - Preload device pressure indicator with dye capsule - Google Patents

Abstract

The invention provides a preload device which includes a pressure vessel body which has a hole in the wall of the body, and a load indicator member engaged with the body over or through the hole, which has a housing which defines a cavity and which has an inlet to the cavity and an outlet from the cavity and a dye containing sealing capsule in the cavity, which seals the outlet from the inlet when fluid pressure in the pressure vessel body exceeds the pressure outside of the body; wherein the sealing capsule is adapted to break when fluid pressure in the pressure vessel reaches a predetermined level to release a dye through the outlet of the housing as an indicator that the preload device has been fully inflated.

Description

PRELOAD DEVICE PRESSURE INDICATOR WITH DYE CAPSULE

BACKGROUND OF THE INVENTION

[0001] This invention relates to a pressure indicating preload device which is adapted to provide a visual indication that the device has been fully inflated to provide optimal load support. The invention extends to a dye-filled capsule that is placed inside a preload device to aid in providing this visual indication

[0002] A preload device is generally inflated in an axial direction of an elongate mine support prop on which it is located to bear under a specific load pressure on either the hanging or the foot wall to preload the prop in position. It often happens, however, that although the preload device may have been inflated, it is sub-optimally pressurised. This can result in the device moving laterally off the prop when installed or providing inadequate load support.

[0003] South Africa patent no. 2003/09273 describes a preload device with a valve which includes an indicator for indicating that the device is filled with hydraulic fluid at or above a predetermined pressure i.e. full inflation for optimal load support of the prop.

[0004] Such a valve relies on a pin which projects from an inlet hole of the valve to indicate full inflation. This pin is often coloured to increase the visual impact. However, the pin remains a relatively small element which can be overlooked.

[0005] The invention aims to at least partially address the aforementioned problems. SUMMARY OF INVENTION

[0006] The invention provides a preload device which includes a pressure vessel body which has a hole in the wall of the body, and a load indicator member engaged with the body over or through the hole, which has a housing which defines a cavity and which has an inlet to the cavity and an outlet from the cavity and a dye containing sealing capsule in the cavity, which seals the outlet from the inlet when fluid pressure in the pressure vessel body exceeds the pressure outside of the body; wherein the sealing capsule is adapted to break when fluid pressure in the pressure vessel reaches a predetermined level to release a dye through the outlet of the housing as an indicator that the preload device has been fully inflated.

[0007] The dye containing sealing capsule may have a first end which is positioned adjacent the outlet and a linearly opposed second end which is adjacent the inlet.

[0008] The dye containing sealing capsule may have a zone or line of relative weakness on the first end about which the capsule breaks when fluid pressure in the pressure vessel reaches the predetermined level.

[0009] The dye containing sealing capsule may have a tubular interior which contains the dye and a pressing member sealing engaged with the tubular interior and which is positioned to advance through the tubular interior towards the first end, when the capsule breaks along the line or zone of relative weakness, to push the dye out of the tubular interior through the outlet. [0010] In another aspect of the inventioOn there is provided a preload device which includes a pressure vessel body, which has a hole in the wall of the body, and a valve assembly which has a sealing body inside the pressure vessel body which is biased towards the wall to seal the hole closed and which defines a cavity and which has, at least, an outlet from the cavity, a dye containing capsule within the cavity; wherein the capsule is adapted to break when the pressure differential across the wall reaches a predetermined level to release the dye through the outlet as an indicator of optimal inflation of the preload device.

[0011] The dye containing capsule may have a first end, with a zone or line of relative weakness about which the capsule breaks when the pressure differential across the wall reaches the predetermined level, adjacent the outlet and a linearly opposed second end.

[0012] The cavity may have an inlet opposed to the outlet and the inlet is adjacent the second end of the capsule. [0013] The dye containing capsule may be adapted to seal the outlet from the inlet when fluid pressure in the pressure vessel body exceeds the pressure outside of the body. The capsule may be adapted with a shoulder which abuts a sealing formation within the cavity.

[0014] The dye containing capsule may have a tubular interior which contains the dye and a pressing member sealing engaged with the tubular interior and which is positioned to advance through the tubular interior towards the first end, when the capsule breaks along the line or zone of relative weakness, to push the dye out of the tubular interior through the outlet.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention is further described by way of examples with reference to the accompanying drawings in which:

Figure 1 is a diagrammatic representation in cross section of a preload device with a discrete load indicator in accordance with the invention;

Figure 2A & 2B diagrammatically represent a cross section through the load indicator of the preload device of Figure 1 in cross section; Figure 3 is a diagrammatic representation in cross section of a preload device, with a valve in accordance with the invention; and

Figures 4A & 4B diagrammatically represent a cross section through a valve of a preload device of Figure 3.

DESCRIPTION OF PREFERRED EMBODIMENTS [0016] A typical preload device 10 is illustrated in Figure 1 which includes a pressure vessel body 12 comprised of a ductile metal wall 14, defining an interior 16, which is hydraulically inflated by the introduction into the interior, through a valve 18, of a hydraulic fluid.

[0017] To ensure that the preload device 10 is optimally pressurised, the device includes a load indicator 20 in accordance with the invention. [0018] The load indicator 20 is illustrated in greater detail in Figures 2A and 2B to show the constituent parts. The indicator includes an indicator body 22 which is externally fixed to an outer surface 24 of the wall 14 of the preload body 12, over a hole 26 which penetrates through the wall.

[0019] The indicator body is tubular, defining an enclosure 30, and attaches to the wall at one end 32, with an opposed outer end 34 being partially closed, penetrated by a bore 36. The outer end 34, being partially closed, defines an inner sealing surface 40. The indicator body thus provides a housing to a dye containing capsule 28.

[0020] The capsule 28 locates snugly within the enclosure 30. However, for ease of illustration, the Figures do not illustrate this snug fit. With the capsule 28 wider than the bore 36 and the hole 26, it is retained within enclosure 30, between the hole and the bore.

[0021] The capsule 28 has a complementary tubular body 42 comprised of a sidewall 44 and an end wall 46 in which is defined a tubular space 48 containing a dye 50. The sidewall 44 has a zone or line of weakness 52 which circumscribes a break out tab 54.

[0022] The side 56, opposed the sidewall 44, is open. It is at this side, within the space 48, that the capsule includes a pressing member 58. The pressing member is sealingly engaged with the inner surface of the sidewall 44.

[0023] When the preload device 10 is inflated, with input of a pressurised hydraulic fluid stream through valve 18, the pressure vessel body expands until the interior reaches a predetermined pressure, typically 12MPa. As the pressure increases, a corresponding force is exerted on the pressing member 54, pressurising the dye within the capsule 28 to the same pressure as the internal pressure of the preload device 12.

[0024] At the predetermined pressure, the sidewall 44 is adapted to break along the line of weakness 52, allowing advance of the pressing member 54 through the space 48 towards the end wall 44, thereby forcing the dye 50 from the capsule and through the bore 36. When the pressing member reaches the sidewall, it seals the bore.

[0025] The capsule 28 also acts as a seal, before the capsule breaks at the sidewall 44, by being forced against the sealing surface 40 of the indicator body 22 by the internal pressure of the pressure vessel body 12. The sidewall can be adapted to sealing engage with the sealing surface.

[0026] The dye, as it is ejected from the indicator body 22, through the bore 36, provides a visual indication that the pressure within the preload device has reached the pressure which is predetermined to provide optimal load support.

[0027] In describing the further embodiments that follow, like features bear like designations.

[0028] Figure 3 illustrates a typical preload device 10A, without a separate load indicator 20. In this embodiment of the invention, the load indicator is integral with the valve assembly 18. The valve assembly regulates fluid input through a fluid input hole 26 which penetrates through the wall of the body 12. [0029] The preload device 10A of this embodiment includes a valve assembly 18, of a typical configuration, which includes a hose connector 60 outwardly disposed of the hole 26 and a sealing member 62 inwardly disposed of the hole.

[0030] The connector button 60 is fixed to an outer surface 24 of the wall 14 and includes a cylindrical body 64 which terminates at a free end in a connector flange 64 and which defines a channel 68 which from an opening 36 to the hole 26. Internally, the sealing member 62 is biased towards the hole by a leaf spring 70.

[0031] The sealing member 62 extends between a distal end 72 to and an opposed sealing end 74. The sealing end has a sealing skirt 76 which resiliently deforms against an inner surface 78 of the wall 14 to seal the hole 26 due to rising internal pressure, as illustrated in Figure 4B.

[0032] As illustrated in Figure 4A, the sealing member 62 lifts from the inner surface, against the bias, when a hose is connected to the connector button 66 and a pressurised fluid stream is input through the channel 68 and the hole 26, into the interior 16.

[0033] The sealing member 62 has a stepped cavity 80 which traverses the members between the ends 72 and 74 and opens at each of these ends. The cavity is broader towards the distal end 72 than towards the sealing end 74. The change in this width occurs at a step 82.

[0034] A capsule 28A is frictionally engaged or adhered within the cavity 80. The outer surface of the capsule is similarly stepped in complementary configuration to the cavity to provide a shoulder 84 in its sidewall 44 which abuts the step 82 to prevent the capsule from being forced from the cavity through the hole 26 due to rising internal pressure.

[0035] Similarly to the capsule 28 of the earlier embodiment, this capsule has a tubular body 42 with a sidewall 44, stepped with the shoulder 80 as described, an end wall 46, a tubular space 48 through the capsule which contains the dye 50 and a pressing member 58 sealingly engaged within the space. The end wall 46 also is formed with a line of weakness 52 that is adapted to break when the pressure of the dye, corresponding with the internal pressure of the preload device 10A, reaches a predetermined pressure.

[0036] As the pressure rises within the interior 16 due to fluid input, the pressure of the dye 50 increases in a corresponding manner due to the action of the pressing member. When the pressure reaches the predetermined level, the end wall 46 breaks along the line of weakness 52, causing a plug 54 to break away. This allows the pressing member 58 to advance through the space 48 towards the end wall 46, extruding the dye from the capsule as it proceeds. This is illustrated in Figure 4B.

[0037] Another embodiment of the invention is illustrated in Figures 5A and 5B. The valve 18A of this embodiment has a capsule 28B which, again, is disposed in a cavity 80 of the sealing member 62.

[0038] The cavity 80 of this embodiment is only open at the sealing end 74 of the member, the member being closed at the distal end 72.

[0039] With the end wall 46 of the capsule 28B positioned adjacent the sealing end 74 to face the incoming pressurised fluid, the end wall will break along the line of weakness 52 when the input pressure of the fluid, which will equalise at the internal pressure, reaches a predetermined level. With the pressure of the dye, within the tubular space 48 of the capsule, remaining at atmospheric pressure, and the predetermined pressure typically reaching +/- 13MPa, the plug 54 will be forced into the space, opening the end wall to dye egress. This action is illustrated in Figure 5B.

Claims

1 . A preload device which includes a pressure vessel body which has a hole in the wall of the body, and a load indicator member engaged with the body over or through the hole, which has a housing which defines a cavity and which has an inlet to the cavity and an outlet from the cavity and a dye containing sealing capsule in the cavity, which seals the outlet from the inlet when fluid pressure in the pressure vessel body exceeds the pressure outside of the body; wherein the sealing capsule is adapted to break when fluid pressure in the pressure vessel reaches a predetermined level to release a dye through the outlet of the housing as an indicator that the preload device has been fully inflated.

2. A preload device according to claim 1 wherein the dye containing sealing capsule has a first end which is positioned adjacent the outlet and a linearly opposed second end which is adjacent the inlet.

3. A preload device according to claim 2 wherein the dye containing sealing capsule has a zone or line of relative weakness on the first end about which the capsule breaks when fluid pressure in the pressure vessel reaches the predetermined level.

4. A preload device according to claim 3 wherein the dye containing sealing capsule has a tubular interior which contains the dye and a pressing member sealing engaged with the tubular interior and which is positioned to advance through the tubular interior towards the first end, when the capsule breaks along the line or zone of relative weakness, to push the dye out of the tubular interior through the outlet.

A preload device which includes a pressure vessel body, which has a hole in the wall of the body, and a valve assembly which has a sealing body inside the pressure vessel body which is biased towards the wall to seal the hole closed and which defines a cavity and which has, at least, an outlet from the cavity, a dye containing capsule within the cavity; wherein the capsule is adapted to break when the pressure differential across the wall reaches a predetermined level to release the dye through the outlet as an indicator of optimal inflation of the preload device.

A preload device according to claim 5 wherein the dye containing capsule has a first end, with a zone or line of relative weakness about which the capsule breaks when the pressure differential across the wall reaches the predetermined level, adjacent the outlet and a linearly opposed second end.

A preload device according to claim 6 wherein the cavity has an inlet opposed to the outlet and the inlet is adjacent the second end of the capsule.

A preload device according to claim 7 wherein the dye containing capsule is adapted to seal the outlet from the inlet when fluid pressure in the pressure vessel body exceeds the pressure outside of the body.

A preload device according to claim 7 or 8 wherein the dye containing capsule has a tubular interior which contains the dye and a pressing member sealing engaged with the tubular interior and which is positioned to advance through the tubular interior towards the first end, when the capsule breaks along the line or zone of relative weakness, to push the dye out of the tubular interior through the outlet.