Belt tensioner with releasable belt load damping
DC
First Claim
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1. The combination comprisingan internal combustion engine including an engine frame subject to vibrational forces resulting from the operation of said internal combustion engine,a plurality of shafts mounted for rotational movement about parallel axes fixed with respect to said engine frame,a plurality of pulleys fixed to said plurality of shafts,one of said plurality of shafts constituting an output shaft of said internal combustion engine,an endless flexible belt of a size capable of being loosely trained about said plurality of pulleys, anda belt tensioner comprisinga fixed structure fixed with respect to said engine frame,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 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 said pivoted structure approaches said second position so that said belt tensioning pulley is biased into an intermediate operating static equilibrium position in tensioning engagement with said 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 a lever arm distance to said pivotal axis through which the belt load 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 sufficient to restrict the pivotal movements of said pivoted structure 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 to an extent such that movements in response to dynamic changes in the belt load force within a range of changes are prevented,said damping means being operable in response to the vibrational forces to which said engine frame is subject to instantaneously release the damping torque resistance to a level permitting instantaneous pivotal movements in response to dynamic changes in the belt load force which would otherwise be prevented by said sliding friction surface means as being within said range of changes.[...]. .Iadd.said range of belt load force changes varying from the generally constant belt load force to a positive extent wherein the belt load force increases and to a negative extent wherein the belt load force decreases, the range being such that the positive extent exceeds the negative extent sufficiently to provide within the excess extent positive changes in the resistance to movement which exceed the negative change in the resistance to movement heretofore considered the limit necessary to prevent hang-up. .Iaddend.
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Abstract
A belt tensioner having a sleeve bearing pivotally mounting a pivoted structure on a fixed structure for spring pressed movement between first and second positions. The sleeve bearing is larger than and surrounds a ball bearing assembly rotatably mounting a pulley on the pivoted structure. The pulley has a cantilevered rim which axially overlaps and annularly surrounds the sleeve bearing. One of the structures and the sleeve bearing have slidably interengaging surfaces which are compressed together by the belt load force in the pivoted structure and the reactionary force acting in the fixed structure so as to provide a damping torque resistance to the pivotal movement of the pivoted structure which prevents movements resulting from dynamic changes in the belt load force within a range. The arrangement is such that independent vibrational forces instantaneously release the damping torque resistance to permit instantaneous movements otherwise prevented.
30 Citations
44 Claims
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1. The combination comprising
an internal combustion engine including an engine frame subject to vibrational forces resulting from the operation of said internal combustion engine, a plurality of shafts mounted for rotational movement about parallel axes fixed with respect to said engine frame, a plurality of pulleys fixed to said plurality of shafts, one of said plurality of shafts constituting an output shaft of said internal combustion engine, an endless flexible belt of a size capable of being loosely trained about said plurality of pulleys, and a belt tensioner comprising a fixed structure fixed with respect to said engine frame, 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 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 said pivoted structure approaches said second position so that said belt tensioning pulley is biased into an intermediate operating static equilibrium position in tensioning engagement with said 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 a lever arm distance to said pivotal axis through which the belt load 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 sufficient to restrict the pivotal movements of said pivoted structure 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 to an extent such that movements in response to dynamic changes in the belt load force within a range of changes are prevented, said damping means being operable in response to the vibrational forces to which said engine frame is subject to instantaneously release the damping torque resistance to a level permitting instantaneous pivotal movements in response to dynamic changes in the belt load force which would otherwise be prevented by said sliding friction surface means as being within said range of changes.[...]. .Iadd.said range of belt load force changes varying from the generally constant belt load force to a positive extent wherein the belt load force increases and to a negative extent wherein the belt load force decreases, the range being such that the positive extent exceeds the negative extent sufficiently to provide within the excess extent positive changes in the resistance to movement which exceed the negative change in the resistance to movement heretofore considered the limit necessary to prevent hang-up. .Iaddend.
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17. A belt tensioner comprising
a fixed structure, a pivoted structure, a pulley mounted on said pivoted structure for rotational movement about a rotational axis, means defining interengaging surfaces operatively associated with said structures arcuate about a fixed pivotal axis parallel with said rotational axis so as to slide relative to one another and define pivotal movements of said pivoted structure with respect to said fixed structure between a first position wherein said 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 said pivoted structure approaches said second position permitting manual movement of said pulley into said first position against such resilient bias so that upon manual release the resilient bias moves said pulley into an intermediate operating static equilibrium position 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 operating position approaches said second position due to belt elongation by maintaining the belt load force acting on said pulley generally constant and varying a lever arm distance to said pivotal axis through which the belt load force acts, said spring means being mounted with respect to said pivoted structure such that the resultant spring torque is balanced in a radial direction with respect to the pivotal axis, the position of said pivotal axis and said rotational axis being so related to the position of engagement of said pulley with the belt when said tensioner is in operation that the belt load force transmitted to said pivoted structure is resisted by a reactionary force created in said fixed structure thereby compressing said interengaging surfaces together so as to establish a damping torque resistance which is a function of the fixed distance between said arcuate interengaging surfaces and said pivotal axis, the coefficient of friction with respect to the means defining said interengaging surfaces and the magnitude of said belt load and reactionary forces, the means defining said interengaging surfaces having a design static coefficient of friction such that pivotal movements of said pivoted structure (1) in a direction toward said first position by the belt load torque as a result of dynamic increases in the belt load forces and (2) in a direction toward said second position by said spring torque as a result of dynamic decreases in said belt load force are prevented so long as the surfaces remain immobile with respect to one another and the reactionary force is of a magnitude above a predetermined percentage of said constant belt load force, the arrangement being such that vibratory forces independent of said dynamic belt load forces instantaneously release the damping torque resistance either by mobilizing the surfaces so as to reduce the coefficient of friction function from static to dynamic or reducing the reactionary force or both so as to enable instantaneous pivotal movements to take place which would otherwise be prevented.
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25. 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 pulley can be transversely aligned with a loosely trained belt, 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 said pivoted structure approaches said second position permitting manual movement of said pulley into said first position so that upon manual release the resilient bias moves said belt tensioning pulley into an intermediate operating static equilibrium position 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 operating position approaches said second position due to belt elongation by maintaining the belt load force generally constant and varying a lever arm distance to said pivotal axis through which the belt load 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 sufficient to restrict the pivotal movements of said pivoted structure by virtue of the pressure of interengagement of said sliding friction surface means from said pivotal axis to an extent such that movements in response to dynamic changes in the belt load force about -50% of the constant belt load force are prevented, and means operable in response to vibrational forces independent of the dynamic belt load forces for instantaneously releasing the damping torque resistance to a level permitting instantaneous pivotal movements in response to dynamic changes in the belt load force which would otherwise be prevented by said sliding friction surface means as being within said range of changes.
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28. A belt tensioner comprising
a fixed structure including a fixed pivotal bearing portion defining a fixed pivotal bearing surface arcuate about a fixed pivotal axis, said fixed pivotal bearing portion extending in cantilevered fashion in one axial direction, a pivoted structure including a movable pivotal bearing portion having a movable pivotal bearing surface disposed in axially lapped opposed relation with respect to said fixed pivotal bearing surface and a pivoted annular bearing portion defining a rotational axis parallel with said pivotal axis, a pulley including a radially extending wall, an annular belt engaging wall concentric with said rotational axis and extending axially from an outer portion of said radially extending wall in cantilevered fashion in an axial direction opposed to said one axial direction and a rotational annular bearing portion concentric with said rotational axis extending axially from an inner portion of said radially extending wall in cantilevered fashion in said opposed axial direction and in axially lapped opposed relation with respect to said pivoted annular bearing portion, rotational bearing means between said annular bearing portions mounting said pulley on said pivoted structure for rotational movement about said rotational axis, pivotal bearing means between said fixed and movable pivotal bearing surfaces mounting said pivoted structure on said fixed structure for pivotal movement about said fixed pivotal axis between a first position wherein said 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 said pivoted structure approaches said second position permitting manual movement of said pulley onto said first position against such resilient bias so that upon manual release the resilient bias moves said pulley into an intermediate operating static equilibrium position 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 operating position approaches said second position due to belt elongation by maintaining the belt load force acting on said pulley generally constant and varying a lever arm distance to said pivotal axis through which the belt load force acts, said pivotal bearing means having exterior and interior bearing surfaces engaging said fixed and movable pivotal bearing surfaces, said exterior and interior bearing surfaces being disposed in an annular plane surrounding said rotational bearing means and said annular bearing portions, said belt engaging annular wall extending in axially lapped surrounding relation with respect to said pivotal bearing means and said rotational bearing means such that the belt load force acting on said pulley is transmitted to said pivoted structure through said rotational bearing means so as to establish a belt load force in said pivoted structure opposed by an equal and opposite reactionary force in said fixed structure transmitted to said pivotal bearing means in an axially balanced fashion.
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35. A belt tensioner comprising
a fixed structure including a fixed annular bearing portion defining a fixed annular bearing surface arcuate about a fixed pivotal axis, a pivoted structure including a movable pivotal bearing portion having a movable annular bearing surface disposed in axially lapped opposed relation with respect to said fixed annular bearing surface, a pulley rotational bearing means mounting said pulley on said pivoted structure for rotational movement about a rotational axis parallel with said fixed pivotal axis, an annular sleeve bearing between said fixed and movable annular bearing surfaces mounting said pivoted structure on said fixed structure for pivotal movement about said fixed pivotal axis between a first position wherein said 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 said pivoted structure approaches said second position permitting manual movement of said pulley into said first position against such resilient bias so that upon manual release the resilient bias moves said pulley into an intermediate operating static equilibrium position 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 operating position approaches said second position due to belt elongation by maintaining the belt load force acting on said pulley generally constant and varying a lever arm distance to said pivotal axis through which the belt load force acts, said sleeve bearing having exterior and interior annular bearing surfaces engaging said fixed and movable annular bearing surfaces, all of said bearing surfaces encircling said rotational axis and having a radius dimension greater than the radius dimension of said rotational bearing means.
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40. The combination comprising
an internal combustion engine including an engine frame subject to vibrational forces resulting from the operation of said internal combustion engine, a plurality of shafts mounted for rotational movement about parallel axes fixed with respect to said engine frame, a plurality of pulleys fixed to said plurality of shafts, one of said plurality of shafts constituting an output shaft of said internal combustion engine, an endless flexible belt of a size capable of being loosely trained about said plurality of pulleys, and a belt tensioner comprising a fixed structure fixed with respect to said engine frame, 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 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 said pivoted structure approaches said second position so that said belt tensioning pulley is biased into an intermediate operating static equilibrium position in tensioning engagement with said 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 a lever arm distance to said pivotal axis through which the belt load 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 restricting the pivotal movements of said pivoted structure by virtue of the pressure of interengagement of said damping surfaces and the position of interengagement of said damping surfaces from said pivotal axis to an extent such that movements in response to dynamic changes in the belt load force within a range of changes are prevented, said interengaging damping surfaces and the operative association thereof respectively with said fixed structure and said pivoted structure being operable in response to the vibrational forces to which said engine frame is subject to instantaneously release the damping torque resistance to a level permitting instantaneous pivotal movements in response to dynamic changes in the belt load force which would otherwise be prevented by said interengaging damping surfaces as being within said range of changes, said range of belt load force changes varying from the generally constant belt load force to a positive extent wherein the belt load force increases and to a negative extent wherein the belt load force decreases, the range being such that the positive extent exceeds the negative extent sufficiently to provide within the excess extent positive changes in the resistance to movement which exceed the negative change in the resistance to movement heretofore considered the limit necessary to prevent hang-up. .Iaddend. .Iadd.
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44. Iadd.0. The combination as defined in claim 49 wherein said belt tensioning pulley is rotationally mounted on said pivoted structure by a ball bearing assembly axially overlapped and annularly surrounded by said cantilevered belt engaging wall and said sleeve bearing. .Iaddend.
Specification
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Litigation Data
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Current AssigneeLitens Automotive Partnership
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Original AssigneeLitens Automotive Partnership
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InventorsKomorowski, Jacek S.
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Primary Examiner(s)BUIZ, MIKADO RYAN
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Application NumberUS07/994,495Time in Patent Office421 DaysField of Search474/101, 474/111, 474/112, 474/133, 474/135, 474/109, 384/125, 384/129, 384/192, 384/194, 384/205, 384/275US Class Current474/135CPC Class CodesF02B 2275/06 Endless member is a beltF16H 2007/081 Torsion springsF16H 2007/084 having vibration damping ch...F16H 7/1218 of the dry friction type
