Abstract: In an aspect, a tensioner is provided for tensioning a belt and includes first and second tensioner arms having first and second pulleys respectively. The first and second pulleys are configured for engagement with first and second belt spans, and are biased in first and second free arm directions respectively. A second tensioner arm stop is positioned to limit the movement of the second tensioner arm in a direction opposite the second free arm direction. The second tensioner arm stop is positioned such that, in use, the second pulley is engaged with the endless drive member while the second tensioner arm is engaged with the second tensioner arm stop throughout a first selected range of operating conditions.

Abstract: In an aspect, a clutch assembly is provided that uses an electromagnet to generate a magnetic circuit which drives an armature to a position whereat it engages the clutch to operatively connect a rotating member to a stationary member. In embodiments wherein the armature initially rotates with the rotating member, the magnetic circuit passes through the stationary member. In embodiments wherein the armature is initially stationary, the magnetic circuit extends through the rotating member.

Abstract: In an aspect, an endless drive arrangement for an engine is provided and includes a crankshaft pulley that is drivable by a crankshaft of the engine, a secondary motive device that is operable to drive a secondary motive device pulley; an endless drive member that is engaged with the crankshaft pulley and the secondary motive device pulley, wherein the endless drive arrangement is operable in a first mode in which tension in a first span of the endless drive member is lower tension than a second span of the endless drive member and in a second mode in which tension in the second span of the endless drive member is lower than tension in the first span of the endless drive member; first and second tensioners may move as needed to maintain tension in first and second spans of the belt.

Abstract: In an aspect, a tensioner is provided for tensioning a belt and includes first and second tensioner arms having first and second pulleys respectively. The first and second pulleys are configured for engagement with first and second belt spans, and are biased in first and second free arm directions respectively. A second tensioner arm stop is positioned to limit the movement of the second tensioner arm in a direction opposite the second free arm direction. The second tensioner arm stop is positioned such that, in use, the second pulley is engaged with the endless drive member while the second tensioner arm is engaged with the second tensioner arm stop throughout a first selected range of operating conditions.

Abstract: In an aspect, a clutched device is provided, including a hub, a pulley and a hub drive clutch. The hub defines an axis and is connectable to a rotatable shaft of a rotary device. The pulley is rotatable relative to the hub and is engageable with an endless drive member. The hub drive clutch is a wrap spring clutch and is controllable to operatively connect the pulley to the hub for driving the hub in a first rotational direction. An isolation spring is provided and operatively connects the hub to the pulley when the hub drives the pulley in the first rotational direction. Optionally, a pulley overrun clutch is provided and permits the pulley to overrun the hub in the first rotational direction.

Abstract: In the one aspect, a tensioner that incorporates a fluid actuated cylinder and that is capable of precognitively anticipating when is desirable to increase the tension in a belt or other endless drive element so as to prevent belt slip prior to events that would raise the risk of it.

Abstract: In an non-limiting embodiment, an isolator is provided for isolating a device driven by an engine via an endless drive member. The isolator includes a shaft adapter that is connectable with a shaft of the device, a rotary drive member that is engageable with the endless drive member, a torsion spring that is positioned to transfer torque between the shaft adapter and the rotary drive member, and a torque limiting surface. The torsion spring has a first helical end, a second helical end and a plurality of coils between the first and second helical ends. The torque limiting surface has a selected non-zero spacing from the coils.

Abstract: A tensioner for an engine accessory drive system includes a tensioner arm pivotally mounted for movement between a free arm position and a load stop position. The tensioner arm includes a pulley which engages a belt. A piston, disposed in a cylinder, is pivotally linked to the tensioner arm. A spring urges the tensioner arm towards the free arm position. A moveable load stop member, controlled by an actuator, projects into the cylinder. The load stop member abuts the piston to thereby arrest movement of the tensioner arm and define the load stop position. The actuator may drive the load stop member against the piston to move the tensioner arm towards the free arm position so as to increase belt tension.

Abstract: A driven accessory comprising a first rotary clutch portion, a second rotary clutch portion, a wrap spring and an actuator. The actuator is selectively operable for generating a force that is applied to a second end of the wrap spring. The actuator includes an actuator input member that is rotatable about a rotary axis relative to the first rotary clutch portion. The actuator input member is axially movable along the rotary axis between a first position, in which the actuator input member is drivingly engaged to the first rotary clutch portion to cause the wrap spring to uncoil against a clutch surface on the first rotary clutch portion such that rotary power is transmitted between the first rotary clutch portion and the second rotary clutch portion, and a second position in which the actuator input member is disengaged from first rotary clutch portion.

Abstract: In one aspect the invention relates to a tensioner that is capable of precognitively anticipating when it is desirable to increase the tension in a belt or other endless drive element so as to prevent belt slip prior to events that would raise the risk of it.

Abstract: In an aspect, an isolator is provided for isolating a device driven by an engine via an endless drive member. The isolator includes a shaft adapter that is connectable with a shaft of the device, a rotary drive member that is engageable with the endless drive member, a first isolation spring arrangement that is positioned to transfer torque between the shaft adapter and the rotary drive member, and a position-based damping structure. The damping structure is positioned to transfer torque via a frictional damping force between the rotary drive member and the shaft adapter at a selected amount of relative movement therebetween. The selected amount of relative movement is selected to be less than a maximum permitted amount of flexure of the first isolation spring arrangement.

Abstract: In one aspect, a tensioner is provided, comprising, a first tensioner arm and a second tensioner arm, a first wheel and a second wheel. The first tensioner arm is pivotable about a first pivot axis. The second tensioner arm is pivotally connected to the first arm so as to be pivotable about a second pivot axis located at a selected distance from the first pivot axis. The first wheel is rotationally connected to the first tensioner arm about a first rotation axis. The second wheel is rotationally connected to the second tensioner arm about a second rotation axis. The first and second wheels are configured to engage an endless drive member. The first and second wheels are biased in respective first and second free arm directions.

Abstract: An isolator is provided for use with an engine and in particular an engine that is assisted or started by MGU (Motor-Generator Unit) or a motor through an endless drive member. It comprises a double acting spring system for isolating crankshaft pulley from torsion vibration at the crankshaft, and in extreme conditions, such as during engine startup and accelerations or decelerations of the engine crankshaft relative to the pulley and when isolator operates in an “engine-driven” mode with the engine crank shaft is driven by the belt.

Abstract: An isolator for isolating a device driven by an engine via an endless drive member is described. The isolator comprises a shaft adapter that is connectable with a shaft of the device, defining a shaft adapter axis, a rotary drive member that is rotatable relative to the shaft adapter and has an endless drive member engagement surface that is engageable with the endless drive member, and an isolation spring arrangement positioned to transfer torque between the shaft adapter and the rotary drive member. The isolation spring arrangement has at least one isolation spring that is axially offset from the endless drive member engagement surface. The at least one isolation spring has an outer edge that is radially outside the endless drive member engagement surface.

Abstract: A driven accessory (10) is provided that includes a first rotary clutch portion (50), a second rotary clutch portion (52), a wrap spring (56) and an actuator (60). The wrap spring (56) is configured to transmit rotary power between the first and second rotary clutch portions (50, 52). The actuator (60) is selectively operable for generating a drag force that is applied to the wrap spring (56) to control torque transmission through the wrap spring (56). The actuator (60) includes an actuator input member (140), a brake shoe (144) and a motor (142) that is configured to translate the brake shoe (144) axially along the rotary axis (70). The drag force is generated when the motor (142) is operated in a first mode so that transmission of rotary power between the first rotary clutch portion (50) and the second rotary clutch portion (52) is interrupted.

Abstract: In an aspect the invention is directed to an isolator comprising a shaft connector that is connectable with a shaft of a motive device, a first rotary drive member that is operatively engageable with at least one second rotary drive member, a first isolation spring and a second isolation spring. The first rotary drive member and the shaft connector are rotatable about an isolator axis. The motive device may be an engine (and thus the shaft may be a crankshaft), or a motor for assisting an engine, for example. Examples of motors for assisting engines include motor/generator units (MGU's) that can operate as a generator when driven to rotate mechanically, and can operate as a motor when driven to rotate electrically. The first isolation spring is positioned to transfer a torque from the first rotary drive member to the shaft connector. The second isolation spring is positioned to transfer a torque from the shaft connector to the first rotary drive member.

Abstract: In one aspect, the invention relates to a tensioner that is capable of precognitively anticipating when it is desirable to increase the tension in a belt or other endless drive element so as to prevent belt slip prior to events that would raise the risk of it.

Abstract: In an aspect the invention is directed to an isolator comprising a driver that is connectable with a shaft of a device, a rotary drive member that is engageable with an endless drive member; and a first isolation spring and a second isolation spring. The first and second isolation springs are positioned such that during rotation of the driver in a first direction torque is transferred from the driver to the first rotary drive member through the first isolation spring and not through the second isolation spring, and such that during rotation of the first rotary drive member in the first direction torque is transferred from the first rotary drive member to the driver through the second isolation spring and not through the first isolation spring.

Abstract: A tensioner for an engine accessory drive system includes a tensioner arm pivotally mounted for movement between a free arm position and a load stop position. The tensioner arm includes a pulley which engages a belt. A piston, disposed in a cylinder, is pivotally linked to the tensioner arm. A spring urges the tensioner arm towards the free arm position. A moveable load stop member, controlled by an actuator, projects into the cylinder. The load stop member abuts the piston to thereby arrest movement of the tensioner arm and define the load stop position. The actuator may drive the load stop member against the piston to move the tensioner arm towards the free arm position so as to increase belt tension.

Abstract: In an aspect, an isolator is provided for isolating a device driven by an engine via an endless drive member. The isolator includes a shaft adapter that is connectable with a shaft of the device, a rotary drive member that is engageable with the endless drive member, a torsion spring that is positioned to transfer torque between the shaft adapter and the rotary drive member, and a torque limiting surface. The torsion spring has a first helical end, a second helical end and a plurality of coils between the first and second helical ends. The torque limiting surface has a selected non-zero spacing from the coils.