Ring fastener with locking feature

Abstract

A ring fastener comprising a discontinuous band having overlapped first and second end portions. The thickness of the band at each of the end portions is reduced relative to the rest of the band. The first end portion has an elongate closed-end slot that extends at least part way along the length of the first end portion, and the second end portion has a lug projecting in an axial direction into the slot in the first end portion. A method of installing the ring fastener into a circumferential groove in a bore comprises: compressing the ring fastener to an outer circumference that is less than the inner circumference of the bore; locating the compressed ring fastener in the groove; and releasing the right fastener to expand into the groove to an outer circumference greater than the inner circumference of the bore.

Description

RING FASTENER WITH LOCKING FEATUREFIELD OF THE INVENTION

[0001] This invention relates to a ring fastener, such as a retaining ring, and methods of assembling the ring fastener into a groove of a component.BACKGROUND TO THE INVENTION

[0002] Retaining rings can have many different applications, but are often used to secure components together, such as to secure two rotating parts together. For example, a retaining ring can be fitted into a groove on an internal surface of a bore to act as a shoulder to mount or secure a component in the bore.

[0003] One example of a retaining ring is a spiral retaining ring, which comprises a single turn band with a gap in the circumference of the ring. When installed, the ends of the ring are brought together and can be in contact. However, during use, any thermal expansion of the ring can cause the ends of the ring to move apart, thus opening up the gap. This type of retaining ring therefore does not provide reliable full circumference support for the components during use.

[0004] Some retaining rings overcome this problem by providing a retaining ring with two or more turns. However, the material used to produce such a ring is much thinner than a single turn ring, and as such each ring does not provide sufficient torsional stiffness. This can result in the ring twisting during use, which can reduce the stability of the ring and its ability to effectively secure components together.

[0005] WO2020 / 234572 describes a ring fastener comprising a discontinuous band having a first end and a second end. The first end comprises a pair of spaced-apart elongate finger members (having a first finger member and a second finger member), and the second end comprises an elongate tongue member. The finger members and the tongue member are interlockable, such that when interlocked, the band comprises a continuous circumference. Thering fastener further comprises a closed configuration wherein the finger members and the tongue member are substantially aligned with a circumferential surface of the band; and an open configuration wherein the first finger member is radially and / or axially deflected from its substantially aligned position, so that it is angled with respect to the circumferential surface of the band.

[0006] UK Patent Application GB2210635.5 describes a ring fastener comprising a discontinuous band having first and second axial faces on opposite sides, a first end with a first end face and a groove extending from the first end face and opening to the first axial face; a second end with a second end face and a tongue projecting from the second end face; wherein the groove is u-shaped and the second axial face defines the base of the groove, and the tongue is dimensioned to fit in the groove; such that, when the tongue is received in the groove, the first end is located relative to the second end and a continuous ring is formed. A method of assembling the ring fastener into a circumferential groove in a component comprises the steps of feeding the ring fastener into the groove so that the ends are adjacent to each other; distorting the second end axially out of the plane of the groove; bringing the ends towards each other until the tongue overlies the groove; and inserting the tongue into the groove so that the ends are within groove.

[0007] One problem with known ring fasteners is that the ends can become disengaged due to forces and vibrations in use.SUMMARY OF THE INVENTION

[0008] One aspect of this invention comprises a ring fastener, comprising: a discontinuous band having overlapped first and second end portions, wherein: the thickness of the band at each of the first and second end portions is reduced relative to the rest of the band; andthe first end portion has an elongate closed-end slot that extends at least part way along the length of the first end portion, and the second end portion has a lug projecting in an axial direction into the slot in the first end portion.

[0009] The lug and slot prevent the overlapped end portions from becoming disengaged due to distortion when the ring is in use.

[0010] The lengths of the first and second end portions can be substantially the same.

[0011] Each first and second end portion can have a free end and a step where it joins the rest of the band, and the free end of one end portion can be spaced from the step of the other end portion. The space allows the ring to expand and contract due to thermal changes without compressing the ring.

[0012] The combined thickness of the overlapped first and second end portions is substantially the same as the thickness of the rest of the band. The length of the lug can be less than the thickness of the first end portion. In this way, the width of the groove in which the ring is installed can be constant and does not need to be excessively wide to accommodate the end portions.

[0013] The lug can be located in the slot such that there is space in the slot on either side of the lug. This allows the outer circumference of the ring to change in use, such as when a ring is compressed for installation or expanded into a groove.

[0014] Another aspect of the invention comprises a method of installing a ring fastener according to any preceding claim into a circumferential groove in a bore, the method comprising: compressing the ring fastener to an outer circumference that is less than the inner circumference of the bore; locating the compressed ring fastener in the groove; and releasing the right fastener to expand into the groove to an outer circumference greater than the inner circumference of the bore.

[0015] Further aspects of the invention are described below in relation to the drawings.DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 shows a partial view of a ring fastener according to one aspect of the invention.

[0017] Figure 2 shows the end portions of the ring fastener of Figure 1 separated for clarity.

[0018] Figure 3 shows the ring fastener of Figure 1 in an assembly state.

[0019] Figure 4 shows the ring fastener of Figure 1 in a working position.DESCRIPTION OF EMBODIMENTS

[0020] The embodiment shown in Figure 1 is a ring fastener for holding a component in a bore. The fastener comprises a discontinuous ring 10 (shown in part) formed from a metal strip having a substantially rectangular cross section with rounded edges. First and second end portions 12, 14 are formed at the end of the strip. The end portions 12, 14 are of reduced thickness compared to the rest of the ring 10 and are partially overlapped such that the face 16 of the first end portion 12 contacts the corresponding face 18 of the second end portion 14. The first and second end portions 12, 14 are approximately half the thickness of the rest of the band 10 such that when the end portions 12, 14 are overlapped, and their faces 16, 18 in contact, the combined thickness of the end portions is substantially the same as the thickness of the rest of the ring 10.

[0021] Figure 2 shows the first and second end portions 12, 14 separated for clarity. Each end portion 12, 14 has a free end 20, 22, and a step 24, 26 where it joins the rest of the ring 10 and the thickness increases. Holes 28, 30 are formed in the axial face of the ring 10 for use with an assembly tool (not shown) to hold the two end portions 12, 14 together during assembly.

[0022] The first end portion 12 has a closed-end slot 32 that extends along its length between the free end 20 and the step 24. The length and width of the slot can be selected according to specific requirements. In this embodiment, the slot 32 extends completely through the first end portion 12. In an alternativeembodiment, the slot 32 can be in the form of a groove that is open to the face 16.

[0023] The second end portion 14 has a lug 34 extending in an axial direction from its face 18 between the free end 22 and the step 26. The lug 18 has dimensions that allow it to fit in the slot 32. The length of the lug 34 is less than the thickness of the first end portion 12 so that it does not project out of the slot 32. The position of the lug 34 on the second end portion can be selected according to specific requirements.

[0024] With the lug 34 located in the slot 32, the length of the slot 32 will limit the amount that the end portions 12, 14 can be separated or brought together circumferentially. The free end of each end portion 20, 22 is spaced from the respective step 24, 26 of the other end portion 20, 22.

[0025] Figures 3 and 4 illustrate the assembly of the ring fastener of Figures 1 and 2 into a circumferential groove 36 in an inner wall of a bore 38 (shown in part viewed along the bore). The fastener is being used to locate a component 40 in the bore. In Figure 3, the first and second end portions 12, 14 have been brought together to reduce the outer diameter of the fastener 10 to be no more than the inner diameter of the bore 38. An assembly tool can be engaged in the holes 28, 30 to do that and a thin shim material can be used to ensure that the slot 32 and lug 34 are engaged properly (not shown). The component is 40 is located in the bore 38 below the groove 36 and the fastener positioned adjacent the groove 36.

[0026] The end portions 12, 14 are then allowed to separate due to the resilience of the fastener 10, with the lug 34 moving along the slot 32, such that the outer diameter increases and the fastener 10 projects part way into the groove 36 (Figure 4), leaving part 42 of the fastener 10 projecting into the bore 38 and holding the component 40 in place.

[0027] The location of the lug 34 in the slot 32 means that the two end portions 12, 14 cannot be accidentally disengaged, such as by radial distortion of one relative to the other, or by circumferential separation that might be cause during operation. The space between the free ends 20, 22 and the steps 24, 26 allow circumferential variation due to thermal changes to be accommodated without distorting the fastener 10.

[0028] Various changes can be made within the scope of the invention

Claims

Claims1. A ring fastener, comprising: a discontinuous band having overlapped first and second end portions, wherein: the thickness of the band at each of the first and second end portions is reduced relative to the rest of the band; and the first end portion has an elongate closed-end slot that extends at least part way along the length of the first end portion, and the second end portion has a lug projecting in an axial direction into the slot in the first end portion.

2. A ring fastener as claimed in claim 1 , wherein the lengths of the first and second end portions are substantially the same.

3. A ring fastener as claimed in claim 1 or 2, wherein each first and second end portion has a free end and a step where it joins the rest of the band, and wherein the free end of one end portion is spaced from the step of the other end portion.

4. A ring fastener as claimed in any of claims 1 - 3, wherein the combined thickness of the overlapped first and second end portions is substantially the same as the thickness of the rest of the band.

5. A ring fastener as claimed in any preceding claim, wherein the length of the lug is less than the thickness of the first end portion.

6. A ring fastener as claimed in any preceding claim, wherein the lug is located in the slot such that there is space in the slot on either side of the lug.

7. A method of installing a ring fastener according to any preceding claim into a circumferential groove in a bore, the method comprising: compressing the ring fastener to an outer circumference that is less than the inner circumference of the bore; locating the compressed ring fastener in the groove; and releasing the right fastener to expand into the groove to an outer circumference greater than the inner circumference of the bore.

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