Torsional force linear tensioner

1 . A tensioner for tensioning a power transmitting element, the tensioner comprising:

a rotatable element; and

a translating element operatively engaged with the rotatable element so that rotation of the rotatable element in a first rotational direction causes translation of the translating element in a first linear direction to tension the power transmitting element and so that translation of the translating element in a second linear direction causes rotation of the rotatable element in a second rotational direction.

2 . A tensioner as claimed in claim 1 , wherein the rotatable element is a pinion and the translating element is a rack.

3 . A tensioner as claimed in claim 1 , wherein the rotatable element is a friction wheel in frictional contact with the translating element.

4 . A tensioner as claimed in claim 1 , further comprising a rotary actuator for applying a rotational force to the rotatable element.

5 . A tensioner as claimed in claim 1 , further comprising a means for applying a rotational force to the rotatable element.

6 . A tensioner as claimed in claim 5 , wherein the means for applying a rotational force to the rotatable element is a torsion spring.

7 . A tensioner as claimed in claim 5 , wherein the means for applying a rotational force to the rotating member is a servo motor.

8 . A tensioner as claimed in claim 5 , wherein the means for applying a rotational force to the rotating member is a hydraulic pump.

9 . A tensioner as claimed in claim 2 , further comprising an intermediate gear operatively engaged with the rack and the pinion so that the pinion indirectly engages the rack through the intermediate gear.

10 . A tensioner as claimed in claim 4 , further comprising a pulley rotatably coupled to the translating element for movement therewith, the pulley being operable to engage and tension the associated power transmitting element.

11 . A tensioner for tensioning a power transmitting element, the tensioner comprising:

a rotatable element; and

a translating element operatively engaged with the rotatable element so that rotation of the rotatable element in a first rotational direction causes translation of the translating element in a first linear direction;

wherein the translating element is capable of translating in a second linear direction opposite the first linear direction in response to force exerted by the associated power transmitting element.

12 . A tensioner as claimed in claim 11 , further comprising a cable having a first end coupled to the translating element and a second end coupled the rotatable element, wherein the rotatable element is a spool.

13 . A tensioner as claimed in claim 11 , wherein the rotatable element is a friction wheel in frictional contact with the translating element.

14 . A tensioner as claimed in claim 11 , wherein translation of the translating element in the second linear direction causes the rotatable element to rotate in a second rotational direction.

15 . A tensioner as claimed in claim 14 , wherein the rotatable element is a pinion and the translating element is a rack.

16 . A tensioner as claimed in claim 11 , further comprising a rotary actuator for biasing the rotatable element to rotate in the first rotational direction.

17 . A tensioner as claimed in claim 11 , further comprising a means for biasing the rotatable element to rotate in the first rotational direction.

18 . A tensioner as claimed in claim 17 , wherein the means for biasing is a torsion spring.

19 . A tensioner as claimed in claim 17 , wherein the means for biasing is a servo motor.

20 . A tensioner as claimed in claim 17 , wherein the means for biasing is a hydraulic pump.

21 . A tensioner as claimed in claim 16 , further comprising a pulley rotatably coupled to the translating element for movement therewith, the pulley being operable to engage and tension the associated power transmitting element.

22 . A tensioner for tensioning a power transmitting element, the tensioner comprising:

a base;

a pinion rotatably mounted on the base;

a means for applying a rotational force to the pinion;

a rack operatively engaged with the pinion;

an arm slideably mounted on the base and coupled to the rack for linear movement therewith; and

a pulley rotatably mounted on the arm to engage and tension the associated power transmitting element.

23 . A tensioner as claimed in claim 22 , wherein the means for applying a rotational force is a torsion spring.

24 . A tensioner as claimed in claim 22 , wherein the means for applying a rotational force is a servo motor.

25 . A tensioner as claimed in claim 22 , wherein the means for applying a rotational force is a hydraulic pump.

26 . A tensioner as claimed in claim 22 , further comprising an intermediate gear rotatably mounted on the base and operatively engaged with both the rack and the pinion.

27 . A tensioner as claimed in claim 22 , further comprising:

a second rack operatively engaged with the pinion;

a second arm slideably mounted on the base and coupled to the second rack for linear movement therewith; and

a second pulley rotatably mounted on the second arm to engage and tension an associated power transmitting element.

28 . A tensioner for tensioning a power transmitting element, the tensioner comprising:

a base;

a pinion rotatably mounted on the base;

a spring operatively coupled to the base and the pinion;

a rack operatively engaged with the pinion; and

a pulley rotatably mounted on the rack to engage and tension the associated power transmitting element.

29 . A tensioner as claimed in claim 28 , further comprising an intermediate gear rotatably mounted on the base and operatively engaged with both the rack and the pinion.

30 . A tensioner as claimed in claim 28 , further comprising:

a second rack operatively engaged with the pinion; and

a second pulley rotatably mounted on the second rack to engage and tension the associated power transmitting element.

31 . A tensioner for tensioning a power transmitting element, the tensioner comprising:

a base;

a pinion rotatably mounted on the base;

a means for applying a rotational force to the pinion;

a rack operatively engaged with pinion such that rotation of the pinion causes linear translation of the rack;

a pulley rotatably coupled to the rack for linear movement therewith, the pulley being operable to engage and tension the associated power transmitting element; and

a planetary gear set operatively coupling the pinion and the means for applying a rotational force to the pinion.

32 . A tensioner for tensioning a power transmitting element, the tensioner comprising:

a base;

a sun gear rotatably mounted on the base;

a means for applying a rotational force to the sun gear;

a ring gear concentric with the sun gear and non-rotatably mounted on the base;

a planetary gear operatively engaged with the sun gear and the ring gear such that rotation of the sun gear causes orbital movement of the planetary gear about the sun gear;

a pinion co-axially mounted with respect the sun gear for independent rotation, the pinion coupled to the planetary gear such that orbital movement of the planetary gear causes rotation of the pinion;

a rack operatively engaged with the pinion such that rotation of the pinion causes linear translation of the rack; and

a pulley rotatably coupled to the rack for linear movement therewith, the pulley being operable to engage and tension the associated power transmitting element.

33 . A tensioner as claimed in claim 32 , wherein the means for applying a rotational force is a torsion spring.

34 . A tensioner as claimed in claim 32 , wherein the means for applying a rotational force is a servo motor.

35 . A tensioner as claimed in claim 32 , wherein the means for applying a rotational force is a hydraulic pump.

36 . A tensioner for tensioning a power transmitting element, the tensioner comprising

a base;

a friction wheel rotatably mounted on the base;

a rotary actuator for applying a rotational force to the friction wheel;

an arm slideably mounted on the base and frictionally engaged with the friction wheel; and

a pulley rotatably coupled to the arm for movement therewith, the pulley operable to engage and tension the associated power transmitting element.

37 . A tensioner as claimed in claim 36 , wherein the rotary actuator is a torsion spring operatively coupled at a first end to the base and at a second end to the friction wheel.

38 . A tensioner for tensioning a power transmitting element, the tensioner comprising:

a base;

a spool rotatably mounted on the base;

a rotary actuator for applying a rotational force to the spool;

an arm slideably mounted on the base;

a cable coupled at a first end to the arm and coupled at a second end to the spool so as to be in winding engagement with the spool; and

a pulley rotatably coupled to the arm for movement therewith, the pulley operable to engage and tension the associated power transmitting element.

39 . A tensioner for tensioning a power transmitting element, the tensioner comprising:

a rotatable element; and

a translating element operatively engaged with the rotatable element so that rotation of the rotatable element causes translation of the translating element;

wherein the tensioner is operable in a first condition and a second condition, the first condition characterized by the rotatable element rotating in a first rotational direction and the translating element translating in a first linear direction, and the second condition characterized by the translating element translating in a second linear direction opposite the first linear direction and the rotatable element rotating in a second rotational direction.

40 . A tensioner as claimed in claim 39 , further comprising a rotary actuator for biasing the rotatable element to rotate in the first rotational direction.

41 . A tensioner as claimed in claim 40 , wherein the rotary actuator resists rotation of the rotatable member in the second rotational direction.