Power system coupling of a multi-speed transmission to a prime mover

A clutch assembly for modulating a power extraction from a constant speed engine during a coupling event in which the constant speed engine is coupled to and in power communication with a multi-speed transmission, the constant speed engine configured to produce an operating speed within an operating performance speed range by varying fuel flow in response to the power extraction, the multi-speed transmission having a plurality of planetary gear sets configured to produce a plurality of speed ratios when in power communication with the constant speed engine, the clutch assembly comprising:

• an outer housing;
• a clutch input configured to be in rotationally driven communication with a prime mover, the clutch input supported by the outer housing;
• a clutch output configured to be in rotationally driving communication with a multi-speed transmission, the clutch output supported by the outer housing;
• a disk pack configured to selectively couple the clutch input to the clutch output, the disk pack including at least one first friction surface capable of being selectively engaged with at least one second friction surface, the disk pack having an engaged condition to couple the clutch input to the clutch output characterized in that the at least one first friction surface is in contact with the at least one second friction surface and a disengaged condition to uncouple the clutch input to the clutch output in which the at least one first friction surface is not in contact with the at least one second friction surface;
• an apply piston configured to urge the at least one first friction surface into contact with the at least one second friction surface in the engaged condition when a hydraulic apply pressure is generated in an input hydraulic line, wherein a total pressure at a piston head of the apply piston is a sum of the hydraulic apply pressure and a rotational hydraulic pressure as a result of rotational motion of the apply piston about a rotational axis;
• a balance cavity having a balance cavity bleed configured to feed a hydraulic fluid to the balance cavity, the balance cavity structured to generate a balance cavity hydraulic pressure as a result of rotational motion of the balance cavity about the rotational axis, the balance cavity hydraulic pressure offsetting the rotational hydraulic pressure of the apply piston;
• and
• a working fluid path configured to flow a hydraulic fluid radially outward from the rotational axis through an interior of the outer housing, the working fluid path configured to flow radially inward through the disk pack and to the balance cavity bleed.

A power transfer system useful to transfer power between a prime mover and a power consuming device, the power transfer system comprising:

• a multi-speed transmission having a plurality of selective couplers operable to selectively change from an engaged condition to a disengaged condition, the multi-speed transmission including a transmission input configured to receive mechanical power;
• a pump configured to provide pressure and motive force to a hydraulic fluid consumed in the multi-speed transmission;
• an input coupler having a mechanical input clutch in power communication with the multi-speed transmission and in fluid communication with the pump, the input coupler having a mechanical clutch, the input coupler including a clutch input configured to receive mechanical power and a clutch output configured to be coupled to the transmission input of the multi-speed transmission and transfer power from the clutch input to the transmission input of the multi-speed transmission;
• a first working fluid path is defined to convey the hydraulic fluid from the multi-speed transmission to the input coupler, the first working fluid path routed through a first port defined between the multi-speed transmission and the input coupler;
• and
• a second working fluid path is defined to convey the hydraulic fluid from the input coupler to the multi-speed transmission, the second working fluid path routed through a second port defined between the multi-speed transmission and the input coupler.

A clutch balance assembly for an input clutch to provide an offset hydraulic pressure as a result of rotation of the clutch balance assembly, the clutch balance assembly comprising:

• a clutch input configured to receive rotational power from a prime mover;
• a clutch output configured to deliver rotational power to a multi-speed transmission;
• a disc pack configured to selectively couple the clutch input to the clutch output;
• an apply piston having a piston head on a first axial side of the apply piston, the apply piston configured to receive a hydraulic fluid in contact with the piston head, the piston head extending a radial distance offset from a rotational axis of the apply piston, a pressure at the piston head in part driven by rotational motion of the apply piston about the rotational axis, the rotational motion forming a rotation induced pressure, the rotation induced pressure a component of the pressure at the piston head;
• a balance flange connected to the apply piston and configured to move with the apply piston, the balance flange extending radially inward relative to the piston head and having a first axial side and a second axial side, the first axial side of the balance flange opposite the second axial side of the balance flange;
• and
• a balance cavity defined by the balance flange, the balance cavity extending on the first axial side of the balance flange and the second axial side of the balance flange.

A method of operating a power system, the power system having a constant speed engine coupled to a multi-speed transmission through an input clutch, the method comprising:

• fueling the constant speed engine at a first steady state fuel flow to maintain a speed of the constant speed engine within an operating performance speed range and provide a first power output, the first power output providing a power extraction from the constant speed engine to the multi-speed transmission;
• changing a gear ratio of the multi-speed transmission and thereby vary the power extraction from the constant speed engine to the multi-speed transmission;
• modulating the power extraction from the constant speed engine to the multi-speed transmission through a pressure applied between a first friction surface of the input clutch and a second friction surface of the input clutch;
• and
• during the modulating, altering fueling of the constant speed engine to maintain an operating speed of the constant speed engine in an operating performance speed range.