Clamping rings

Abstract: A clamping ring (24), for clamping an end collar of a protective bellows to one end of a universal joint in a vehicle transmission, is made of resilient material having two overlapping end portions (30,32). One end portion (32) has a tongue (36) extending through a slot (34) defined in the other end portion (34). In its relaxed state, the material of the ring holds the tongue (36) midway of the slot (34). When the ring is placed over the end collar of the bellows, the ring expands slightly to permit this, the tongue (36) moving towards a "high" stop (40) at one end of the slot (34) . The ring then resiles slightly so as to hold itself on the bellows. When the bellows, with the ring in position, is placed over the end of the universal joint, the ring once more expands slightly to permit this. The ring is then tightened by moving the end portion (30) until a hook (42) engages a shoulder (44) on the other end portion (32), the tongue (36) moving towards a "low" stop (38) at the other end of the slot (34).

Description: The invention relates to a flexible article having a separate clamping ring for clamping the periphery of the flexible article to a rigid circumferential surface, the clamping ring comprising: resilient strip-shaped material arranged with its two end portions overlapping so as to define the ring, and such that the extent of the overlap can be varied to increase and decrease the internal diameter of the ring; holding means acting between the overlapping end portions to define a predetermined initial relative position for the end portions before the ring is placed over the periphery of the flexible article from which initial relative position the inherent resilience of the material resists relative movement of the end portions; the holding means enabling the end portions to move relatively from the initial position to a second relative position in which the ring has an increased internal diameter to permit the ring to be placed around the periphery of the flexible article, the ring thereafter being held on the flexible article by the resilience of the ring; and locking means operable after the flexible article with the ring thereon has been placed over the circumferential surface to lock the end portions in a third relative position in which the end portions have moved relatively to reduce the internal diameter of the ring so as to clamp the article to the circumferential surface. Such an article and clamping ring are known from EP-A1-0 236 217. The clamping ring is used in association with a separate elastic member for holding the two end portions of the clamping ring in the initial position. This complicates the design, and the elastic member is liable to loss of resilience during storage or by damage, or may be displaced and lost altogether. According to the invention, the flexible article and clamping ring as first set forth above is characterised in that the holding means comprises two substantially rigid members respectively carried by the overlapping end portions and in contact with each other in the initial relative position, one of the rigid members being capable of being over-ridden to enable the end portions to move either into the second or into the third relative position. In embodiments of the invention to be described in more detail below, the articles are protective bellows for universal joints in motor vehicle transmissions such as front wheel drive transmissions, and the clamping rings are for clamping the opposite ends of the bellows to the universal joints. Such protective bellows and clamping rings will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 illustrates a protective bellows mounted in position around the universal joint in a motor vehicle front wheel drive transmission arrangement; Figure 2A is a diagrammatic partial cross-section, taken on the line IIA-IIA of Fig. 5, through one of the clamping rings before it is fitted onto the protective bellows; Figure 2B is a diagrammatic partial cross-section through an end collar of the bellows before it is fitted in position; Figure 3A is a diagrammatic side view of one end of the universal joint of the transmission shown in Fig. 1 and onto which an end of the bellows is to be clamped; Figure 3B is a diagrammatic partial cross-section through one of the clamping rings installed on the bellows of Fig. 2B before the bellows is placed in position universal joint of Figure 3A; Figure 4 is a diagrammatic partial cross-section showing the bellows and clamping ring of Figure 3B fitted in position on the universal joint of Figure 3A; Figure 5 is a view of one of the clamping rings, taken in section along the line V-V of Figure 6 but before the ring is placed on the bellows shown in that Figure; Figure 6 is a partial cross-section on the line VI-VI of Figure 5, and also illustrating part of the bellows; Figure 7 is a view corresponding to Figure 5 of part of another form of the clamping ring, shown in the configuration which it has before it is fitted onto the bellows; Figure 8 is a sectional view corresponding to Figure 7 taken on the line VII-VII of Figure 9 and showing the clamping ring of Figure 7 fitted onto a bellows; Figure 9 is a diagrammatic partial cross-section on the line XI-XI of Figure 8; Figure 10 is a sectional view taken on the line X-X of Fig. 11 and corresponding to Figures 8 and 9, showing the clamping ring in position on a bellows and with the bellows in position on the transmission drive arrangement; Figure 11 is a cross-section on the line XI-XI of Figure 10; and Figures 12 and 13 correspond to Figures 10 and 11 but show the clamping ring in its locked configuration. In the embodiments to be described, items in each embodiment corresponding to items in any other embodiment have the same reference numerals. Figure 1 shows part of the front wheel drive transmission of a motor vehicle. The driven shaft 10 from the gear box 12 drives a front wheel of the vehicle via a universal joint 16. In order to protect the mechanism of the universal joint 16, it is encased in a bellows 18 made, for example, of thermoplastics material. The bellows has collars 20 and 21 at each of its opposite ends which are respectively positioned around an end 22 of the universal joint and the shaft 10 and are clamped thereto by clamping rings (not shown in Figure 1). Figure 2A shows, in diagrammatic form only, part of one of the clamping rings 24 which is shown to have an inside diameter A. Figure 2B shows, again in diagrammatic form only, part of one end of the bellows 18 and the corresponding collar 20 which has an outside diameter B. Figure 3A shows part of the end 22 of the universal joint 16, and Figure 3B shows the clamping rings 24 in position around the collar 20 of the bellows. In this position, the outer diameter of the collar 20 is C. The end 22 of the universal joint has a locating groove 27. Figure 4 shows the bellows placed on to the end 22 of the universal joint 16 by means of the clamping ring shown diagrammatically in Figure 3B, the outer diameter of the collar 22 being D in this situation. The clamping rings now to be described are arranged so that diameter A (Figure 2A) is substantially equal to or slightly less than diameter B (Figure 2B). When the clamping ring is placed onto the collar 20, the clamping ring is able to expand slightly to ease its fitting onto the collar, but then resiles slightly so as to be retained on the collar 20. The situation shown in Figure 3B is thus produced, with the diameter C being slightly less than or possibly equal to diameter B and slightly greater than or possibly equal to diameter A. The bellows, with the clamping ring in position, is then placed onto the end 22 of the joint 16, to produce the situation shown in Figure 4 in which a shoulder 28 of the bellows locates itself in the groove 27 (Fig. 3A). During this assembly operation, the clamping ring 24 expands to aid the assembly, and diameter D (Fig. 4) is greater than diameter C. The clamping ring is then tightened (as will be explained) to secure the bellows end on the universal joint. The collar 20 of the bellows has a slot 29 which becomes partially closed during this tightening operation. Figure 5 shows one of the clamping rings 24. It is made of flexible material (preferably metal) and is generally circular in end view, but with overlapping portions 30 and 32. Portion 30 is formed with a slot 34 into which a tongue 36, bent out of portion 32, extends. The slot 34 defines a "low" stop 38 and a "high" stop 40 at opposite ends of the groove 34. The outer overlapping portion 30 has a hooked end 42 for engaging a shoulder 44 as will be explained. The clamping ring shown in Figure 5 is arranged so that, before it is placed in position on the bellows, the tongue 36 is held midway between the low and high stops 38,40. This is achieved by a keeper 46 which extends across the slot 34, as illustrated most clearly in Figure 6. The keeper 46 may be made of metal or plastics and may be glued or similarly fixed in position and holds the tongue 36 against the inherent resilience of the material of the clamping ring. In this position, the internal diameter of the clamping ring has the value A (see Fig. 2A). When the clamping ring is placed onto the collar 20 at the end of the bellows, as shown in Figure 3B, the clamping ring is expanded to aid this assembly; the tongue 34 either breaks the keeper 46 or ejects it from its glued position on the clamping ring the tongue 36 then moves freely towards the high stop 40. Once the clamping ring is in position on the collar 22 (Fig. 3B), it resiles slightly and the tongue 36 moves back towards the position midway between the stops 38 and 40. The clamping ring is thus held adequately in position by its own resilience on the collar 20. The bellows, with the clamping ring 24 in position, can then be easily located on the end 24 of the universal joint 16, as shown in Figure 4, the clamping ring expanding slightly to aid this assembly process and the tongue 36 moving towards the high stop 40. Assembly is then completed by tightening the clip until the hook 42 (Fig. 5) engages over the shoulder 44. Figure 6 shows the tongue 36 of Figure 5 slidably arranged in the groove 34. In the clamping ring shown in Figure 7, the arrangement is such that the tongue 36, instead of being situated midway between the high and low stop 38 and 40 when the clamping ring is in its relaxed state before fitment onto the bellows, is in engagement with the low stop 38. When the clamping ring is placed onto the collar 20 of the bellows (as shown in Figure 3B), the clamping ring is expanded so that the tongue 36 moves approximately to the position midway between the stops 38 and 40 as shown in Figures 8 and 9. When the bellows, with the clamping ring in position on it, is placed over the end of the universal joint 16, as shown in Figure 4, the tongue 36 now moves towards the high stop 40 as the clamping ring expands - as shown in Figures 8 and 10. The clamping ring is then tightened. This process brings the tongue 36 once more into contact with the low stop 38. The tongue 36 is either deformed by this contact, as shown in Figure 12, or is completely broken off; in either case, continued overlapping movement of the portions 30 and 32 takes place until the hook 42 engages over the shoulder 44.

Claims: A flexible article (18) having a separate clamping ring (24) for clamping the periphery (20) of the flexible article (18) to a rigid circumferential surface (22), the clamping ring (24) comprising: resilient strip-shaped material arranged with its two end portions (30,32) overlapping so as to define the ring, and such that the extent of the overlap can be varied to increase and decrease the internal diameter of the ring; holding means (36,46;36,38) acting between the overlapping end portions (30,32) to define a predetermined initial relative position for the end portions (30,32) before the ring is placed over the periphery (20) of the flexible article (18) from which initial relative position the inherent resilience of the material resists relative movement of the end portions (30,32); the holding means (36,46;36,38) enabling the end portions (30,32) to move relatively from the initial position to a second relative position in which the ring has an increased internal diameter to permit the ring to be placed around the periphery (20) of the flexible article (18), the ring thereafter being held on the flexible article (18) by the resilience of the ring; and locking means (42,44) operable after the flexible article (18) with the ring thereon has been placed over the circumferential surface (22) to lock the end portions(30,32) in a third relative position in which the end portions (30,32) have moved relatively to reduce the internal diameter of the ring so as to clamp the article (18) to the circumferential surface (22); characterised in that the holding means comprises two substantially rigid members (36,46;36,38) respectively carried by the overlapping end portions (30,32) and in contact with each other in the initial relative position, one (36;46) of the rigid members (36,46;36,38) being capable of being over-ridden to enable the end portions (30,32) to move either into the second or into the third relative position. An article according to claim 1, characterised in that the substantially rigid member (36) carried by one (32) of the end portions (30,32) interacts with first and second spaced stop members (38,40) which are carried by the other end portion (30) and which together define first and second limits to the relative movement of the end portions (30,32) and thus to their overlap, whereby the first stop member (40) defines the first limit which corresponds to an internal diameter of the ring greater than that corresponding to the second relative position and the second stop member (38) defines the second limit which corresponds to an internal diameter for the ring less than that corresponding to the second relative position. An article according to claim 2, characterised in that the second stop member (38) corresponds to an internal diameter of the ring slightly less than that corresponding to the third relative position, and in that the substantially rigid member (46) carried by the other (30) of the end portions is positioned on that portion (30) between the two stop members (38,40). An article according to claim 3, characterised in that the substantially rigid member (46) carried by the other (30) of the end portions is over-ridden by being displaced or broken. An article according to claim 2, characterised in that the second stop member (38) constitutes the substantially rigid member (38) carried by the other end portion (30), the substantially rigid member (36) carried by the said one end portion (32) being over-ridden by being bent or broken. An article according to any one of claims 2 to 5, characterised in that the substantially rigid member (36) carried by the one end portion (32) comprises a tongue (36) extending in a generally radially outward direction with respect to the ring and the first and second stop members (38,40) comprise opposite ends of a slot (34) in the other end portion (30) through which slot the tongue (36) extends. An article according to any preceding claim, characterised in that the locking means comprises hook means (42) carried by one end portion (30) for locking engagement with shoulder means (44) carried by the other end portion (32). An article according to any preceding claim, characterised in that the resilient material is metal. An article according to any preceding claim, characterised in that it is a flexible bellows for protecting a universal joint (16) in a motor vehicle transmission, in that the periphery of the flexible article is an end collar (20) of the bellows, and the rigid surface is the surface (22) in the transmission and to which the end collar (20) is to be clamped by the clamping ring (24).

Inventors: BREHERET JOEL, RENZO BERNARD, BREHERET, JOEL, RENZO, BERNARD
Applicants: DRAFTEX IND LTD, DRAFTEX INDUSTRIES LIMITED
Application year: 1992
Main classification: F16L33
IPC codes: F16D3, F16J3, F16B2, F16L33