Resumen
Simple and compact mechanism which allows tightening belts which transmit power from a drive shaft (11) to a follow-up shaft (12). This mechanism provides means for varying and fixing the distance between the drive shaft (11) and the follow-up shaft (12) maintaining them substantially parallel. The use of the proposed mechanism does not have losses due to the contact with an additional tightening element and a similar traction torque is obtained in two rotation directions which make it possible to accurately graduate the tension.
Reivindicaciones
1. Adjustment mechanism of the pretensioning force for power transmission systems between pulleys using a belt, wherein the transmission system comprises: - a belt; - a drive shaft (11) which comprises a first pulley; and - a follow-up shaft (12) which comprises a second pulley; wherein the drive shaft (11) and the follow-up shaft (12) are substantially parallel, said mechanism being characterized in that it comprises means of regulation of the distance between these two shafts. 2. Mechanism according to the preceding claim, wherein the means of regulation of the distance between the drive shaft (11) and the follow-up shaft (12) comprises: - constraining or guiding means of the position of at least one of the shafts; and - fixing means which maintains the distance between the drive shaft (11) and the follow-up shaft (12) fixed. 3. Mechanism according to the preceding claim, wherein the guiding means comprises a fixed part (15, 15') and a moving part (16, 16') integral with either to the follow-up shaft (12) or to the drive shaft (11). 4. Mechanism according to the preceding claim, wherein the moving part (16') moves along a fixed part (15') giving a curved or straight trajectory. 5. Mechanism according to the preceding claim, wherein the guiding means constrains the movement of the moving part (16, 16') at a rotation around a third spin axis (17, 17'), parallel to the drive shaft (11) and to the follow-up shaft, wherein the spin axis (17, 17') does not coincide with the drive shaft (11) or with the follow-up shaft (12). 6. Mechanism according to any of claims 3-5, wherein the fixed part (15, 15') comprises fixing means to fix the moving part (16, 16') in at least two different positions. 7. Mechanism according to the preceding claim, wherein the distance between the positions to fix the distance between the moving part (16, 16') and the fixed part (15, 15') is substantially regular. 8. Mechanism according to claim 6, wherein the fixed part (15') is a substantially circular groove whose centre corresponds to the spin axis and the moving part (16') moves along said groove. 9. Mechanism according to the preceding claim, wherein - The fixed part (15') comprisesN holes situated in an arc of circumference centred in the spin axis spaced at substantially regular distancex on said arc of circumference (18'), and - the moving part (16') comprisesn holes situated in an arc of circumference centred in the spin axis spaced at substantially regular distanceX on said arc of circumference, the distance between holes of the fixed part (15') being substantially different to the distance between holes of the moving part (16'). 10. Regulation mechanism according to claim 6, wherein - the fixed part (15) comprisesn holes (20) situated in a circumference centred in the spin axis with a substantially regular angular spacing, and - the moving part (16) comprisesN holes (21) situated in a circumference centred in the spin axis with a substantially regular angular spacing, the number of holes of the fixed part (15) being different from that of the moving part (16). 11. Regulation mechanism according to the preceding claim, wherein the number of holes of the fixed part (15, 15') and of the moving part (16, 16') differ by one unit. 12. Regulation mechanism according to claim 6, wherein the fixing means is a pin or a screw which is introduced through the coincident hole (14, 14'). 13. Power transmission system between pulleys using a belt which comprises: - a belt; - a drive shaft (11) which comprises a first pulley; - a follow-up shaft (12) which comprises a second pulley parallel to the drive shaft (11); and - an adjustment mechanism of the pretensioning force according to any of the preceding claims. 14. Method to adjust the pretensioning force of a transmission system between pulleys using a belt which comprises the steps of: - Providing a belt between the pulleys of the drive shaft (11) and follow-up shaft (12) in a state wherein no pretensioning forces act. - Varying the distance between the drive shaft (11) and the follow-up shaft (12) until obtaining a desired pretensioning force via an adjustment mechanism according to any of claims 1-12. - Fixing the distance between the drive shaft (11) and the follow-up shaft (12). 15. Method to adjust the pretensioning force of a transmission system between pulleys according to the preceding claim, wherein the variation in the distance between the drive shaft (11) and the follow-up shaft (12) is constrained to a rotation movement of the drive shaft (11) around a third spin axis (17, 17'), parallel to the drive shaft (11) and to the follow-up shaft, wherein the spin axis (17, 17') does not coincide with the drive shaft (11) or with the follow-up shaft (12).
