Start-up clutch assembly

A start-up clutch assembly (10) for translating torque between a prime mover and a transmission having an input shaft, said clutch assembly comprising:

• a drive member (16) operatively connected to the output of the prime mover;
• a driven member (24) operatively connected to the input shaft of the transmission, said drive and driven members (16, 24) rotatable about a common axis and defining a clutch housing (28) therebetween;
• a clutch pack (30) supported in said clutch housing (28), interposed between said drive and driven members (16, 24) and operable to move between a closed pack mode wherein torque is translated across said clutch pack (30) and an open pack mode wherein torque is interrupted across said clutch pack (30) to connect and disconnect said drive and driven members (16, 24) to selectively transfer and interrupt torque translation therebetween;
• a torque apply piston assembly (54) supported in said clutch housing (28), said torque apply piston assembly (54) including a piston (56) that is rotatably supported by said drive member (16) about said common axis of rotation and includes an annular flange (60) extending in the direction of said common axis of rotation, a piston head (62) operable to engage said annular clutch pack (30) and an annular seat (64) formed between said piston head (62) and said axially extending flange (60) and a torque piston biasing member (58) that acts on said seat (64) to bias said piston head (62) toward said clutch pack (30), said torque apply piston (56) operable to move between a disengaged position wherein said clutch pack (30) operates in open pack mode and an engaged position wherein said torque apply piston (56) moves said clutch pack (30) to said closed pack mode to connect and disconnect said drive and driven members (16, 24), said torque apply piston assembly (54) operable to provide a constant biasing force so that said clutch pack (30) normally operates in said closed pack mode to translate torque between said drive and driven members (16, 24);
• a torque interrupt actuator assembly (68) operatively connected to said annular flange (60) on said torque apply piston (56), said torque interrupt actuator assembly (68) including a throw-out bearing (70) operatively supported for rectilinear movement on said drive member (16) and an actuator (72) that selectively moves said throw-out bearing (70) in a direction opposite to the constant biasing force generate by said torque apply piston assembly (54), said torque interrupt actuator assembly (68) operable to selectively move said torque apply piston assembly (54) from said engaged position to said disengaged position thereby interrupting torque translation between said drive and driven members (16, 24) through said clutch pack (30);
• and
• a return piston assembly (84) supported by said clutch housing (28) and connected to said clutch pack (30), said piston return assembly (84) including a piston (86) supported by said drive member (16) and operatively connected to said clutch pack (30) and a return biasing member (90) that provides a constant biasing force in a direction opposite to the constant biasing force generated by said torque apply piston assembly (54) to move said clutch pack (30) from said closed pack mode to said open pack mode when said torque interrupt actuator assembly (68) moves said torque apply piston assembly (54) from said engaged position to said disengaged position.

A automotive transmission (12) comprising:

• a transmission housing (14), a transmission input shaft (26), and a start-up clutch assembly (10) operatively supported in said transmission housing (14) for translating torque between a prime mover and the input shaft (26) of the transmission (19), said start-up clutch assembly (10) including:
• a drive member (16) operatively connected to the output of the prime mover;
• a driven member (24) operatively connected to the input shaft (26) of the transmission (12), said drive and driven members (16,24) rotatable about a common axis and defining a clutch housing (28) therebetween;
• a clutch pack (30) supported in said clutch housing (28), interposed between said drive and driven members (16,24) and operable to move between a closed pack mode wherein torque is translated across said clutch pack (30) and an open pack mode wherein torque is interrupted across said clutch pack (30) to connect and disconnect said drive and driven members (16, 24) to selectively transfer and interrupt torque translation therebetween;
• a torque apply piston assembly (54) supported in said clutch housing (28), said torque apply piston assembly (54) including a piston (56) that is rotatably supported by said drive member (16) about said common axis of rotation and includes an annular flange (60) extending in the direction of said common axis of rotation, a piston head (62) operable to engage said annular clutch pack (30) and an annular seat (64) formed between said piston head (62) and said axially extending flange (60) and a torque piston biasing member (58) that acts on said seat (64) to bias said piston head (62) toward said clutch pack (30), said torque apply piston assembly (54) operable to move between a disengaged position wherein said clutch pack (30) operates in open pack mode and an engaged position wherein said torque apply piston assembly (54) moves said clutch pack (30) to said closed pack mode to connect and disconnect said drive and driven members (16,24), said torque apply piston assembly (54) operable to provide a constant biasing force so that said clutch pack (30) normally operates in said closed pack mode to translate torque between said drive and driven members (16,24);
• a torque interrupt actuator assembly (68) operatively connected to said torque apply piston assembly (54), said torque interrupt actuator assembly (68) operable to selectively move said torque apply piston assembly (54) from said engaged position to said disengaged position thereby interrupting torque translation between said drive and driven members (16,24) through said clutch pack (30);
• and
• a return piston assembly (84) supported by said clutch housing (28) and connected to said clutch pack (30), said return piston assembly (84) operable to provide a constant biasing force in a direction opposite to the constant biasing force generated by said torque apply piston assembly (54) to move said clutch pack (30) from said closed pack mode to said open pack mode when said torque interrupt actuator assembly (68) moves said torque apply piston assembly (54) from said engaged position to said disengaged position.