GB2607027A

GB2607027A - Adjustable retaining ring for bore

Info

Publication number: GB2607027A
Application number: GB2107349.9A
Authority: GB
Inventors: Montgomery Conor
Original assignee: Urban Cottage Ind Ltd
Current assignee: Urban Cottage Ind Ltd
Priority date: 2021-05-24
Filing date: 2021-05-24
Publication date: 2022-11-30
Also published as: GB2607027A9; GB202107349D0

Abstract

An adjustable retaining ring for locating within a bore comprises a open ring 100 having two ends 125,130 with a gap (145, Fig. 2) between them. A screw threaded channel 155 passes through the ring from a first end 125 to an outer perimeter of the ring 100. A screw (200, Fig. 4) is screwable into the channel 155 and has a polygonal portion (215, Fig. 4) adjacent one end that is accessible by a spanner within the gap 145. After the ring 100 is positioned within a bore, turning the screw 200 with a spanner causes the end of the screw to engage with a second end 130 of the ring, applying pressure to the second end and causing the ring to expand. Friction then retains the ring 100 in position within the bore.

Description

ADJUSTABLE RETAINING RING FOR BORE BACKGROUND OF THE INVENTION

[0001] This invention relates to an adjustable retaining ring for placing within a bore to create an internal shoulder. The invention also relates to the use of retaining rings to manufacture light fittings.

[0002] Retaining rings are common devices for preventing the movement of components within a cylindrical bore. Retaining rings for use within bores are also referred to as "internal" retaining rings to differentiate them from "external" retaining rings for use on the outside of a cylindrical shaft. They are also referred to as snap rings or circlips.

[0003] Many different designs exist but a typical internal retaining ring comprises a flat, circular, split hoop having two ends with a small gap between them. The ends of the hoop are pulled together so that the ring can be positioned within a groove in the bore and, when the ends are released, the ring snaps back into shape to lock it in position. The flat surfaces of the ring provide a shoulder for retaining components in position within the bore.

[0004] One type of locking retaining ring is described in US3446522A.

Here, an internal retaining ring is formed from a split hoop of inelastic material.

One end of the split hoop terminates in a flexible tab that extends along an internal circumference of the ring and engages with the opposite end to lock the ring into a fully expanded position within a mating groove inside a bore. The tab may be bent clear of said opposite end to permit contraction of the ring for insertion into or removal from the groove.

[0005] A problem with retaining rings is that it is only the structural elasticity of the ring that provides outward pressure. Consequently, there is only a small amount of frictional force between the outside of the ring and the interior surface of the bore. Retaining rings must therefore usually be seated within a groove to prevent longitudinal movement along the bore. Even then, the ring may be largely free to rotate axially within the bore. One solution to this problem is proposed in US7364395B2. Here, an anti-rotation feature for a gapped snap ring comprises a plurality of ridged locking crests positioned on the outer surface of the ring to increase friction. Better or alternative solutions to this problem with retaining rings would be desirable.

[0006] Some designs of spotlight for commercial or domestic lighting require multiple components to be located within a cylindrical metal tube and secured without externally visible fixings. This has historically required the use of epoxy resins which are messy to use in construction and make disassembly for repair or end-of-life disposal difficult or impossible. Alternative manufacturing approaches which provide a secure but removable internal fixing with no impact on the external aesthetic appearance are desirable.

SUMMARY OF THE INVENTION

[0007] According to a first aspect of the invention, there is provided a retaining ring securable by friction within a bore, comprising an open ring and a screw; the open ring having an outer perimeter defining an outer diameter of the open ring, a first end and a second end, the first end having a first end face, the second end having a second end face, the two end faces facing each other and having a gap between them; the open ring further having a screw-threaded channel extending from the first end face; the screw having a first end and a second end, the first end having a polygonal portion adjacent to it for engaging with a spanner for rotating the screw, the second end having a screw-threaded portion adjacent to it; wherein the screw is locatable within the screw-threaded channel such that the polygonal portion of the screw protrudes from the first end face and is accessible within the gap for rotation by a spanner, and the second end of the screw is located within the channel and does not protrude beyond the outer perimeter, and wherein rotation of the screw causes linear movement of the screw relative to the first end face; and wherein the screw is screwable using a spanner engaging with the polygonal portion so that the first end of the screw engages with the second end face of the open ring and continued screwing pushes the first and second end faces away from each other, causing the outer diameter of the open ring to increase.

[0008] A retaining ring embodying the present invention has many advantages over traditional spring circlips or snap rings. In particular, the retaining ring is adjustable to ensure a tight fit within a bore even with some variation in the internal diameter of the bore. The retaining ring is securable in place by friction alone without the need for additional internal grooves of slots to seat the ring. Consequently, without the need for precise machining, the retaining ring is secured in place ensuring no movement either laterally along the bore or rotationally.

[0009] In one embodiment, the screw-threaded channel passes through the open ring from the first end face to the outer perimeter of the open ring and wherein the second end of the screw has a recess for receiving a tool for rotating the screw, the screw being screwable into the screw-threaded channel from the outer perimeter until the polygonal portion protrudes from the second end face of the open ring and the second end does not protrude beyond the outer perimeter. This enables the retaining ring (comprising the open ring and screw) to be easily assembled ready for locating within a bore simply by screwing the screw fully into the hole on the outer perimeter of the open ring.

[0010] In one embodiment, the first end of the screw has a flat end surface for engaging with the second end of the open ring. Providing a flat end surface rather than, say, a pointed tip to the first end of the screw ensures that the screw does not sink into the second end of the open ring under pressure when the ring is expanded. Over time, this would lead to a relaxation of the ring, reducing the frictional forces keeping the ring in place. This is of particular concern since the open ring may be advantageously made from aluminium for reduced weight and improved recycling, whereas the screw is typically made from harder materials, such as steel or anodised aluminium. Providing a flat end surface to the first end of the screw also helps ensure that the end surface of the screw can slide across the surface of the second end of the open ring as the ring expands, ensuring uniform expansion.

[0011] In one embodiment, the open ring has an upper surface and a lower surface, and the outer perimeter comprises a cylindrical surface extending between the upper and lower surface. The outer perimeter of the ring having a cylindrical surface with a distinct height defined by the distance between the upper and lower surfaces ensures that the outside of the ring presents a suitable surface area for creating friction against a tubular bore. Other components can then be aligned with the upper and lower surfaces. The upper surface and lower surface are, in some embodiments, substantially flat and meet the outer perimeter at right angles to present simple flat, perpendicular surface for aligning other components. Optionally, an inner perimeter of the open ring comprises a cylindrical surface that is substantially concentric with the outer perimeter, but other shapes for the inner perimeter are also possible.

[0012] In one embodiment, at least one hole passes through the open ring from the upper surface to the lower surface. Such holes, preferably screw-threaded holes, enable other components to be attached or secured to the ring.

[0013] According to a second aspect of the invention, there is provided a light fixture comprising a tubular housing, a heatsink, a lighting module and a retaining ring, the retaining ring secured within the housing and the heatsink and lighting module located within the housing and connected to the housing via the retaining ring. By assembling a light fixture with the internal components attached to a tubular housing via a retaining ring, messy adhesives such as epoxy are not required, simplifying end of life disassembly, and no externally visible fixings are required that would impair the aesthetic appearance of the light fixture.

[0014] According to a third aspect of the invention, there is provided a method of assembling a light fixture, the light fixture comprising a tubular housing, a heatsink and a lighting module, the method comprising: securing a retaining ring within the housing; and locating the heatsink and the lighting module within the housing and connecting them to the housing via the retaining ring.

[0015] Preferably, the step of securing the retaining ring within the tube comprises: locating the heatsink within a jig; placing the housing over the heatsink and onto the jig such that the relative position of the heatsink and the housing correspond with their position in the finished assembly; placing the retaining ring within the housing and onto the jig such that the relative position of the housing and the retaining ring correspond with their position in the final assembly; securing the retaining rink in position within the housing; and removing the heatsink and jig from the housing. A jig provides a simple mechanism for ensuring that the retaining ring is correctly located within the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Embodiments of the invention as well as optional features and examples to aid understanding of different implementations and uses of the invention will now be described with reference to the accompanying drawings, in which: [0017] Figure 1 illustrates a retaining ring, where dotted lines show hidden details such as internal structures; [0018] Figure 2 is a detail view of a gap in the retaining ring of Figure 1; [0019] Figure 3 is a top view of the retaining ring of Figure 1; [0020] Figure 4 illustrates an adjustment screw for an adjustable retaining ring; [0021] Figure 5 illustrates a spanner for adjusting the screw of Figure 4; [0022] Figure 6 shows a retaining ring within a cylindrical tube; [0023] Figure 7 is a cutaway view of a light fixture; [0024] Figure 8 is an exploded view of the light fixture of Figure 7; [0025] Figure 9 is a cross-sectional view through a partially assembled light fixture.

DETAILED DESCRIPTION OF THE INVENTION

[0026] As shown in Figures 1 to 3, an internal retaining ring comprises an open or gapped ring 100, preferably in the shape of a hollow cylinder having a gap extending the cylinder's full height. The ring has an inner perimeter 105 and an outer perimeter 110, each perimeter being substantially concentric right circular cylindrical surfaces (apart from the gap in the ring 100). The ring also has an upper surface 115 and a lower surface 120, each surface being substantially flat and parallel to the other and meeting the adjoining inner perimeter 105 and outer perimeter 110 at right angles. This is the simplest, general purpose shape for the ring 100, which provides an effective shoulder for securing other components within a bore, but the upper 115 and lower 120 surfaces need not be flat or parallel if the other components are unusually shaped or require a particular alignment. Also, the inner perimeter 110 need not have a cylindrical surface and may have any desired outline, such as a regular or irregular polygon, depending on requirements. Regular shapes are preferable for even weight and stress distribution around the ring 100, however.

[0027] The ring 100 has first and second ends 125,130, each end having a respective first and second end face 135,140 (see details in Figure 2). The end faces 135,140 oppose each other and are spaced apart to form a gap 145 between the two ends 125,130 of the ring 100. The first end face 135 of the first end 125 has a first circular opening 150 into a screw threaded channel 155 extending substantially at right angles to the first end face 135. The channel 155 extends in a straight line through the first end 125 and emerges at the outer perimeter 110 of the ring 100 at a second circular opening 160. The second end face 140 of the second end 130 is substantially flat.

[0028] One or more holes 165 pass through the ring 100 between the upper surface 115 and lower surface 120. The holes 165 are preferably screw-threaded and other components can be attached to the ring 100 using these holes 165. The figures show three equally spaced apart holes 165, but the number, size and spacing of the holes 165 can be changed depending upon the components intended for attachment. The upper surface 115 and lower surface 120 present flat fixing surfaces for securely attaching components and the thickness of the ring 100 defined by the distance between the inner perimeter 105 and outer perimeter 110 ensures structural strength as well as a large surface area for creating friction against the interior wall of a bore.

[0029] The ring 100 is made from a resilient and substantially stiff material, enabling slight flexing of the ring under pressure and springing back into shape when the pressure is released. The ring 100 must also be strong enough to support attached components. Suitable materials include metals such as steel or aluminium. Aluminium has the advantages that it is lighter, cheaper, more easily recycled, and does not require anti-corrosive coatings or plating. Steel is stronger and may be necessary for large rings or when a large amount of weight needs to be supported.

[0030] Figure 4 illustrates a screw 200 for use with the ring 100. The screw 200 is substantially a right circular cylinder having a first end 205 and a second end 210. The first end 205 of the screw has a substantially flat end surface. The second end 210 has a slot, socket or other recess for receiving a tool such as a screwdriver or hex key for driving the screw 200. Between the two ends 205,210, the screw comprises a polygonal portion 215 adjacent the first end 205 and a screw-threaded portion 220 adjacent the second end 210. The polygonal portion 215 has a polygonal cross section, typically a square cross-section (as illustrated in Figure 4) or a hexagonal cross-section. The polygonal portion 215 provides an external drive for engaging with a tool such as a spanner or other lever for rotating the screw 200. The maximum diameter of the polygonal portion 215 is less than the minimum diameter of the screw-threaded portion 220, and the second end 210 also does not project outside the diameter of the screw-threaded portion 220 so that the whole screw 200 can be screwed into and through a suitable screw-threaded channel.

[0031] Figure 5 illustrates a spanner 300 suitable for use with the ring 100 and screw 200. The spanner is thin and flat to enable the head of the spanner to fit within the gap 145 in the ring and is open-ended to engage with the polygonal portion 215 of the screw 200.

[0032] The screw 200 has an appropriate diameter to fit and be screwed into the screw-threaded channel 155 in the ring 100. The first end 205 of the screw 200 (adjacent the polygonal portion 215) is inserted into the second opening 160 of the channel 155 on the ring's outer perimeter 110. The screw 200 is screwed into the channel 155 by using a screwdriver or other suitable tool engaged with the recess in the second end 210. As the screw 200 is screwed further into the channel 155, the first end 205 and at least some of the polygonal portion 215 emerges from the first opening 150 in the first end face of the ring 100 and is therefore accessible via the gap 145 in the ring 100. The screw 200 can then be screwed further along the channel 155 either by continuing to drive the screw 200 from the second end 210 or by rotating the screw using a spanner inserted within the gap 145 and engaged with the polygonal portion 215.

[0033] As the screw 200 is further screwed down the channel 155, the flat first end 205 reaches the second end face 130 of the ring 100. Continued screwing applies pressure to the second end face. This pressure causes the gap in the ring to widen, thereby expanding the ring 100. The length of the screw 200 is such that the second end 210 of the screw 200 is within the channel 155 when enough of the polygonal portion 215 has emerged from the first opening 150 that it is possible to engage a spanner with the polygonal portion 215. Typically, this will be when the first end 205 of the screw 200 has reached or nearly reached the second end face 130 of the ring 100. The second end 210 therefore does not protrude from the second end 160 of the channel 155 and does not interrupt or protrude beyond the circular outer perimeter 110 of the ring 100 when the first end 205 is in position to expand the ring 100.

[0034] Figure 6 illustrates the ring 100 in use within a cylindrical tube 400.

The cylindrical tube 400 has an internal diameter slightly greater than the diameter of the ring 100 when the ring is unexpanded. The ring 100 can therefore be located within the tube 400 with the screw 200 in place within the channel 155 of the ring 100. The polygonal portion 215 of the screw 200 is accessible within the gap 145 and the flat first end 205 of the screw 200 is touching or almost touching the second end face 130 of the ring.

[0035] Once in place, the screw 200 is turned with a spanner 300 to expand the ring 100 as described above. Expansion of the ring 100 causes the outer perimeter 110 of the ring to press against the internal bore of the tube 400. The screw 200 is turned until there is sufficient pressure that the ring 100 is secured within the tube 400 due to friction between the surface of the outer perimeter 110 and the internal bore. Consequently, it is not necessary for the internal bore of the tube 400 to be provided with a groove for receiving and seating the ring 100 as with most retaining rings. An internal groove may of course be provided to make the ring 100 even more secure, if desired.

[0036] When the ring 100 is secured in place within the tube 400 it provides a shoulder for locating or securing other components, optionally by attaching the other components to the ring 100 via the one or more holes 165.

[0037] If desired, the ring 100 can subsequently be removed from the tube 400 simply by unscrewing the screw 200 using a spanner 300 to release the pressure.

[0038] Retaining rings have many uses and the retaining ring described above may be sized to fit within any required diameter of bore. One particular non-limiting use for the retaining ring 100 described above is in the assembly of light fixtures or spotlights.

[0039] A simple spotlight comprises a tubular housing containing electrical lighting elements and a heatsink to prevent the lighting elements from overheating. For aesthetic reasons the lighting elements and heatsink are preferably secured within the tubular housing (or, alternatively, the housing is secured around the lighting elements and heatsink) without using fixings that are visible from outside the tube. For example, a simple but non-preferred fixing would be to insert one or more screws through the outside of the tube and into the heatsink and/or lighting elements.

[0040] A known, more aesthetically pleasing solution is to use an adhesive such as an epoxy to secure the heatsink within the tube, and the lighting elements are secured to the heatsink using screws, clips or other mechanical fixings. This solution has many disadvantages that are overcome by using a retaining ring. Adhesives are messy to use, imprecise, and errors cannot easily be corrected. A retaining ring requires only mechanical fixings, can be adjusted more accurately and moved or removed as desired. To be able to use adhesive to fix the heatsink, the heatsink must have almost the same diameter as the internal diameter of the tube, limiting the selection of components. A retaining ring can be selected to fit any desired tube size, and any required size and shape of heatsink (provided it fits within the tube) can then be secured to the retaining ring with suitable fixings. Adhesives can crack and separate from the tube over time or if subjected to an impact. A retaining ring ensures a more resilient connection. Finally, if adhesives are used, disassembly of the light fixture for recycling at the end of its working life is difficult or even impossible. The retaining ring, having only mechanical fixings, enables simpler recycling and circular economy benefits.

[0041] Figure 7 illustrates a light fixture 500 utilising a retaining ring 100 in a side cut-away view. Figure 8 illustrates the light fixture 500 in an exploded view.

[0042] The light fixture 500 has an outer housing 505 comprising an aluminium tube, illustrated in cross-section in Figure 7. The interior surface of the tube has a groove or lip 510 near one end to receive an optional protective mesh cover secured by a conventional circlip (not illustrated), but otherwise has a smooth interior to minimise complex machining. A retaining ring 100 is secured within the housing 505 by friction with the substantially smooth internal bore of the housing 505. Other components of the light fixture 500 are attached to the retaining ring 100 with no connection to the housing 505. This enables the manufacture of a light fixture 500 with no fixings visible from the outside of the housing 505.

[0043] A back spill disc 515 is secured to the retaining ring 100 with a plurality of short screws 520 (e.g. three 8mm screws) screwed into the holes 165 in the retaining ring 100. A lens clip 525 is screwed to the back spill disc 515 with a plurality of long screws 530 (e.g. three 35mm screws) with associated washers 532. The long screws 530 also extend through an LED lighting module 535 (such as a Xicato XIM Module (RTM)), a spacer 540 coated with a layer of thermal paste, and into a heatsink 545. A lens 550 is clipped onto the lens clip 525 near a front end of the housing 505.

[0044] A knuckle swivel joint 555 is screwed into the heatsink 545 at the rear end of the housing 505. A cord grip 560 having a grub screw 565 for gripping an electrical cord (not illustrated) is screwed into the knuckle swivel joint 555. A mounting plate 570 for mounting the light fixture 500 is attached to the cord grip 560 using a nut 575 and associated washer 580. When the light fixture 500 is mounted to a wall, ceiling or other surface via the mounting plate 570, the [0045] Wiring (not illustrated) to supply electrical power to the LED lighting module 535 passes through the mounting plate 570, cord grip 560, knuckle swivel joint 555, heatsink 545 and spacer 540.

[0046] Figure 9 is a cross-sectional view illustrating how the retaining ring is secured in the correct position within the housing 505 of the light fixture 500.

[0047] During assembly of the light fixture 500, the knuckle swivel joint 555 (not shown in Figure 9 for simplicity) is screwed into the heatsink 545.

Wiring is passed through the knuckle swivel joint 555 and through a conduit 585 through the centre of heatsink 545. The knuckle swivel joint 555 is swiveled to 900 to the conduit 585. The assembly is then placed into a lower jig 600 having a channel 605 for receiving the knuckle swivel joint 555 with the base of the heatsink 545 resting flat on the lower jig 600.

[0048] An upper jig 610 having a channel 615 for the wiring to pass through is placed on top of the heatsink 545. The upper jig 610 is aligned with and temporarily held in position on the heatsink 545 by passing a plurality of rods 620 (preferably three rods) through a corresponding plurality of holes 625 in the upper jig 610 and into corresponding screw holes 630 in the heatsink 545.

[0049] The retaining ring 100 is placed onto and lies flat on top of the upper jig 610. The housing 505 is placed over the heatsink 545, upper jig 610 and retaining ring 100 and rests flat on the lower jig 600. The upper jig 610 is sized so that the retaining ring 100 is located at the correct position within the housing 505. The retaining ring is rotated so that the gap 145 in the ring 100 is aligned with the channel 615 in the upper jig 610. The channel 615 in the upper jig 610 provides a space for the spanner 300 to be able to reach and adjust the screw 200 of the retaining ring 100. The screw 200 of the retaining ring 100 is then adjusted to secure the retaining ring 100 within the housing 500. The housing 505 with the attached retaining ring 100 is then removed from the lower jig 600, and the upper jig 610 is removed from the heatsink 545 so that the light fixture 500 can be assembled as discussed above.

Claims

CLAIMS: 1. A retaining ring securable by friction within a bore, comprising an open ring and a screw; the open ring having an outer perimeter defining an outer diameter of the open ring, a first end and a second end, the first end having a first end face, the second end having a second end face, the two end faces facing each other and having a gap between them; the open ring further having a screw-threaded channel extending from the first end face; the screw having a first end and a second end, the first end having a polygonal portion adjacent to it for engaging with a spanner for rotating the screw, the second end having a screw-threaded portion adjacent to it; wherein the screw is locatable within the screw-threaded channel such that the polygonal portion of the screw protrudes from the first end face and is accessible within the gap for rotation by a spanner, and the second end of the screw is located within the channel and does not protrude beyond the outer perimeter, and wherein rotation of the screw causes linear movement of the screw relative to the first end face; and wherein the screw is screwable using a spanner engaging with the polygonal portion so that the first end of the screw engages with the second end face of the open ring and continued screwing pushes the first and second end faces away from each other, causing the outer diameter of the open ring to increase.
2. The retaining ring of claim 1 wherein the screw-threaded channel passes through the open ring from the first end face to the outer perimeter of the open ring and wherein the second end of the screw has a recess for receiving a tool for rotating the screw, the screw being screwable into the screw-threaded channel from the outer perimeter until the polygonal portion protrudes from the second end face of the open ring and the second end does not protrude beyond the outer perimeter.
3. The retaining ring of claim 1 or claim 2 wherein the first end of the screw has a flat end surface for engaging with the second end of the open ring.
4. The retaining ring of any preceding claim wherein the open ring has an upper surface and a lower surface and the outer perimeter comprises a cylindrical surface extending between the upper surface and lower surface.
5. The retaining ring of any preceding claim wherein the upper surface and lower surface are substantially flat and meet the outer perimeter at right 15 angles.
6. The retaining ring of claim 4 or 5 wherein at least one hole passes through the open ring from the upper surface to the lower surface.
7. The retaining ring of claim 6 wherein the or each hole is screw-threaded.
8. The retaining ring of claim 6 or claim 7 wherein there are a plurality of equally spaced apart holes around the open ring.
9. A light fixture comprising a tubular housing, a heatsink, a lighting module and a retaining ring, the retaining ring secured within the housing and the heatsink and lighting module located within the housing and connected to the housing via the retaining ring.
10. The light fixture of claim 9 wherein the retaining ring is the retaining ring of any of claims 1 to 8.
11. A method of assembling a light fixture, the light fixture comprising a tubular housing, a heatsink and a lighting module, the method comprising: securing a retaining ring within the housing; and locating the heatsink and the lighting module within the housing and connecting them to the housing via the retaining ring.
12. The method of claim 11 wherein the step of securing the retaining ring within the housing comprises: locating the heatsink within a jig; placing the housing over the heatsink and onto the jig such that the relative position of the heatsink and the housing correspond with their position in the finished assembly; placing the retaining ring within the housing and onto the jig such that the relative position of the housing and the retaining ring correspond with their position in the final assembly; securing the retaining rink in position within the housing; and removing the heatsink and jig from the housing.
13. The method of claim 11 or claim 12 wherein the retaining ring is the retaining ring of any of claims 1 to 8.