Belt tensioner with spring actuated band brake damping

In a belt tensioning device comprising

• a fixed structure,
• a pivoted structure mounted with respect to said fixed structure for pivotal movement above a first axis between first and second limiting positions,
• a belt engaging pulley rotatably carried by said pivoted structures for rotational movement about a second axis with said first axis,
• spring means acting between the fixed and pivoted structures for resiliently biasing said pivoted structure to move in a direction away from said first limiting position toward said second limiting position with a spring force which decreases as said pivoted structure is moved toward said second position, and
• curved surface means operatively associated with one of said structures,
• elongated means operatively associated with the other of said structure engageable with said curved surface means,
• means mounting said elongated means and said curved surface means on their respective structures and with respect to one another such that said elongated means engages said curved surface means with a gripping action sufficient to provide (1) a relatively high resistance to frictional sliding movement between said elongated means and curved surface means in one direction corresponding to the pivotal movement of said pivoted with respect to said fixed structure in a direction toward said first position which is greater than 70% of the instantaneous spring force and (2) a relatively low resistance to frictional sliding movement between said elongated means and said curved surface means in an opposite direction corresponding to the pivotal movement of said pivoted structure with respect to said fixed structure in a direction away from said first position,
• said mounting means including said spring means for enabling said relatively high resistance and said relatively low resistance to vary together (1) in proportion to changes in said spring force and (2) in response to the existence of predetermined vibrations such that said gripping action between said elongated means and said curved surface means is relieved sufficient to enable movement between said elongated means and said curved means in both directions to take place at substantially reduced resistance levels.

In a belt tensioning device comprising

• a fixed structure,
• a pivoted structure mounted with respect to said fixed structure for pivotal movement above a first axis between first and second limiting positions,
• a belt engaging pulley rotatably carried by said pivoted structure for rotational movement about a second axis parallel with said first axis,
• spring means acting between the fixed and pivoted structures for resiliently biasing said pivoted structure to move in a direction away from said first limiting position toward said second limiting position with a spring force which decreases as said pivoted structure is moved toward said second position, and
• curved surface means operatively associated with one of said structures,
• elongated means operatively associated with the other of said structures having a central extent engageable with said curved surface means and connecting means outwardly of the opposite ends of said central extent,
• means mounting said connecting means and said curved surface means on their respective structures and with respect to one another such that the central extent of said elongated means engages said curved surface means with a gripping action sufficient to provide (1) relatively high resistance to frictional sliding movement between the central extent of said elongated means and said curved surface means in one direction corresponding to the pivotal movement of said pivoted structure with respect to said fixed structure in a direction toward said first position and (2) a relatively low resistance to frictional sliding movement between the central extent of said elongated means and said curved surface means in an opposite direction corresponding to the pivotal movement of said pivoted structure with respect to said fixed structure in a direction away from said first position,
• said mounting means including second spring means for enabling said relatively high resistance and said relatively for enabling said resistance to vary together in response to the existence of predetermined vibrations such that said gripping action between the central extent of said elongated means and said curved surface means is relieved sufficient to enable movement between the central extent of said elongated means and said curved surface means in both directions to take place at substantially reduced resistance levels.

In a belt tensioning device comprising

• a fixed structure,
• a pivoted structure mounted with respect to said fixed structure for pivotal movement above a first axis between first and second limiting positions,
• a belt engaging pulley rotatably carried by said pivoted structure for rotational movement about a second axis parallel with said first axis,
• first spring means acting between the fixed and pivoted structures for resiliently biasing said pivoted structure to move in a direction away from said first limiting position toward said second limiting position with a spring force which decreases as said pivoted structure is moved toward said second position, and
• curved surface means operatively associated with one of said structures,
• elongated means operatively associated with the other of said structures engageable with said curved surface means,
• means mounting said elongated means and said curved surface means on their respective structures and with respect to one another such that said elongated means engages said curved surface means with a gripping action sufficient to provide (1) a relatively high to frictional sliding movement between said elongated means and said curved surface means in one direction corresponding to the pivotal movement of said pivoted structure with respect to said fixed structure in a direction toward said first position which is greater than 70% of the instantaneous spring force and (2) a relatively low resistance to frictional sliding movement between said elongated means and said curved surface means in an opposite direction corresponding to the pivotal movement of said pivoted structure with respect to said fixed structure in a direction away from said first position,
• said mounting means including second spring means for enabling said relatively high resistance and said relatively low resistance to vary together in response to the existence of predetermined vibrations such that said gripping action between said elongated means and said curved surface means is relieved sufficient to enable movement between said elongated means and said curved surface means in both directions to take place at substantially reduced resistance levels.

A belt tensioner comprising,

• a fixed structure,
• a pivoted structure,
• a belt tensioning pulley mounted on said pivoted structure for rotational movement about a rotational axis,
• said pivoted structure being mounted on said fixed structure for pivotal movement about a fixed pivotal axis parallel with said rotational axis between a first position wherein said belt tensioning pulley can be transversely aligned with a loosely trained belt and a second position,
• spring means for resiliently biasing said pivoted structure in a direction toward said second position with a spring torque which varies as the position of the pivotal structure approaches said second position permitting manual movement of said belt tensioning pulley into said first position against such resilient bias so that upon manual release the resilient bias moves said belt tensioning pulley into an intermediate operating static equilibrium position in tensioning engagement with the belt wherein the spring torque is equal and opposite to a belt load torque which varies with the variation in the spring torque as the intermediate operation position approaches said second position due to belt elongation by maintaining the belt load force generally constant and varying the lever arm to said pivotal axis through which the belt load force acts, the spring torque at any intermediate operating position being provided by the instantaneous spring force at the intermediate operating position and the lever arm to the pivotal axis through which the instantaneous spring force acts, means for damping the pivotal movements of said pivoted structure as a result of dynamic belt load forces varying from the generally constant belt load force when the belt is moving,
• said damping means including sliding friction surface means for establishing a damping torque resistance to pivotal movement of said pivoted structure in a direction toward said first position by virtue of the pressure of interengagement of said sliding friction surface means and the position of interengagement of said sliding friction surface means from said pivotal axis of a magnitude sufficient to prevent movement in said direction in response to dynamic increases in the constant belt load force within 70% of the instantaneous spring force , and
• means operable in response to the application of vibratory forces to said sliding friction surface means independent of the dynamic belt load forces for instantaneously releasing the damping torque resistance to pivotal movement in said direction established by said sliding friction surface means so that instantaneous movement in said direction can take place which would otherwise be prevented.

A belt tensioner comprising,

• a fixed structure,
• a pivoted structure,
• a belt tensioning pulley mounted on said pivoted structure for rotational movement about a rotational axis,
• said pivoted structure being mounted on said fixed structure for pivotal movement about a fixed pivotal axis parallel with said rotational axis between a first position wherein said belt tensioning pulley can be transversely aligned with a loosely trained belt and a second position,
• spring means for resiliently biasing said pivoted structure in a direction toward said second position with a spring torque which decreases as the position of the pivotal structure approaches said second position permitting manual movement of said belt tensioning pulley into said first position against such resilient bias so that upon manual release the resilient bias moves said belt tensioning pulley into an intermediate operating static equilibrium position in tensioning engagement with the belt wherein the spring torque is equal and opposite to a belt load torque which varies with the variation in the spring torque as the intermediate operation position approaches said second position due to belt elongation by maintaining the belt load force generally constant and varying the lever arm to said pivotal axis through which the belt load force acts,
• the spring torque at any intermediate operating position being provided by the instantaneous spring force at the intermediate operating position and the lever arm to the pivotal axis through which the instantaneous spring force acts,
• interengaging sliding friction damping surfaces operatively associated with said fixed structure and said pivoted structure for damping the pivotal movements of said pivoted structure as a result of dynamic belt load forces varying from the generally constant belt load force when the belt is moving,
• said interengaging damping surfaces presenting sliding friction therebetween sufficient to establish a damping torque resistance to pivotal movement of said pivoted structure in a direction toward said first position by virtue of the pressure of interengagement of said damping surfaces and the position of interengagement of said damping surfaces from said pivotal axis of a magnitude sufficient to prevent movement in said direction in response to dynamic increases in the constant belt load force within 78% of said instantaneous spring force,
• said interengaging damping surfaces and the operative association thereof respectively with said fixed structure and said pivoted structure being operable in response to the application of vibratory forces to said damping surfaces through said fixed structure independent of the dynamic belt load forces to instantaneously release the damping torque resistance to pivotal movement in said direction established by said damping surfaces so that instantaneous movement in said direction can take place which
• would otherwise be prevented.