Closure with obliquely angled cam surfaces on inner and outer parts

1. A closure for a bottle containing carbonated beverages, the closure comprising:

an inner part adapted to receive a portion of a finish of the bottle, the inner part including a plurality of outwardly extending first cam surfaces that are obliquely angled to a longitudinal axis of the closure; and

an outer part adapted to fit substantially over the inner part, the outer part including a plurality of inwardly extending second cam surfaces that are obliquely angled to the longitudinal axis of the closure, the outer part being movable relative to the inner part between a closed position in which at least a portion of the outer part urges at least a portion of the inner part against a neck of the bottle to resist disengagement of the inner part from the finish and an open position in which the inner part allows disengagement of the inner part from the finish,

wherein, when the outer part is in the closed position: applying a longitudinally directed force to the outer part, relatively away from the inner part, causes the outer part to move longitudinally relative to the inner part towards the open position as the second cam surfaces travel relatively longitudinally away from the first cam surfaces; and twisting the outer part in a first direction about the longitudinal axis relative to the inner part drives the outer part longitudinally relatively away from the inner part towards the open position as the second cam surfaces travel relatively along the first cam surfaces.

2. The closure as claimed in claim 1 , wherein, when the outer part is in the open position: applying a longitudinally directed force to the outer part, relatively towards the inner part, causes the outer part to move longitudinally relatively towards the closed position as the second cam surfaces travel relatively longitudinally toward the first cam surfaces whilst simultaneously causing the outer part to twist in a second direction, opposite to the first direction, about the longitudinal axis relative to the inner part as the second cam surfaces travel relatively along the first cam surfaces.

3. The closure as claimed in claim 1 , wherein the first cam surfaces are peripherally spaced apart.

4. The closure as claimed in claim 3 , wherein the first cam surfaces are equally peripherally spaced apart.

5. The closure as claimed in claim 3 , wherein the second cam surfaces are peripherally spaced apart.

6. The closure as claimed in claim 3 , wherein the second cam surfaces are equally peripherally spaced apart.

7. The closure as claimed in claim 1 , wherein the inner part includes a plurality of outwardly extending third cam surfaces respectively between the first cam surfaces.

8. The closure as claimed in claim 7 , wherein the outer part includes a plurality of inwardly extending fourth cam surfaces respectively between the second cam surfaces.

9. The closure as claimed in claim 7 , wherein the third cam surfaces are peripherally spaced apart.

10. The closure as claimed in claim 9 , wherein the third cam surfaces are equally peripherally spaced apart.

11. The closure as claimed in claim 8 , wherein the fourth cam surfaces are peripherally spaced apart.

12. The closure as claimed in claim 11 , wherein the fourth cam surfaces are equally peripherally spaced apart.

13. The closure as claimed in claim 1 , wherein the number of first and second cam surfaces are equal.

14. The closure as claimed in claim 8 , wherein the number of third and fourth cam surfaces are equal.

15. The closure as claimed in claim 14 , wherein the number of first, second, third and fourth cam surfaces are equal.

16. The closure as claimed in claim 8 , wherein the first, second, third and fourth cam surfaces are straight.

17. The closure as claimed in claim 16 , wherein the third and fourth cam surfaces are parallel to the longitudinal axis.

18. The closure as claimed in claim 16 , wherein the third cam surfaces are obliquely angled to the longitudinal axis, in a direction opposition to that of the first and second cam surfaces respectively.

19. The closure as claimed in claim 1 , wherein the first direction is counter-clockwise, when viewed from above the bottle and towards the neck of the bottle.

20. The closure as claimed in claim 2 , wherein the second direction is clockwise.

21. The closure as claimed in claim 8 , wherein the first and third cam surfaces are joined end to end around an outer surface on the inner part.

22. The closure as claimed in claim 21 , wherein the first and third cam surfaces are joined end to end around an outer surface on the inner part in a substantially continuous saw-tooth configuration.

23. The closure as claimed in claim 1 , wherein there are 9 equi-angularly spaced first cam surfaces and 9 equi-angularly spaced second cam surfaces.

24. The closure as claimed in claim 8 , wherein the second and fourth cam surfaces are positioned around an inner surface on the outer part.

25. The closure as claimed in claim 24 , wherein the second and fourth cam surfaces are positioned around an inner surface on the outer part in a substantially spaced apart saw-tooth configuration.

26. The closure as claimed in claim 24 , wherein there are 9 equi-angularly spaced third cam surfaces and 9 equi-angularly spaced fourth cam surfaces.

27. The closure as claimed in claim 8 , wherein the first and third surfaces are angled at about 45 degrees to the longitudinal axis.

28. The closure as claimed in claim 8 , wherein the first and third cam surfaces are formed on an inwardly facing ridge.

29. The closure as claimed in claim 28 , wherein the ridge also includes longitudinally extending stiffening parts.

30. The closure as claimed in claim 2 , wherein the closure includes an outer surround having a first end connected to the outer part and a second end releasably connected to the neck of the bottle, whereby the connection between the surround and the bottle must be released to allow the outer member to move from the closed position to the open position.

31. The closure as claimed in claim 30 , wherein the surround is a tear strip.

32. The closure as claimed in claim 31 , wherein the tear strip is a manually tearable tear strip.

33. The closure as claimed in claim 31 , wherein the tear strip is spirally wound around the neck of the bottle.

34. The closure as claimed in claim 33 , wherein the tear strip releases in the second direction.