Hydraulic coupling having supplemental actuation

A hydraulic coupling for use with a vehicle drivetrain within a housing thereof containing hydraulic fluid to rotatively couple a pair of rotary members about a rotational axis, the hydraulic coupling comprising:

• a casing of a hollow construction that is rotatable within the housing about the rotational axis;
• a hydraulic pump located within the casing along the rotational axis and including a toothed impeller rotatively connected to one of the rotary members and having external teeth;
• the hydraulic pump also including an internal ring gear mounted by the casing for rotation eccentrically with respect to the toothed impeller and including internal teeth of a number one more than the impeller teeth and in a meshing relationship therewith to provide a pumping action upon relative rotation between the casing and the toothed impeller as the pair of rotary members rotate relative to each other;
• an inlet port through which hydraulic fluid is pumped from the housing into the casing by the hydraulic pump;
• a clutch including a piston chamber located within the casing and having an actuating piston that is received within the piston chamber and actuatable by pressurized hydraulic fluid to engage the clutch and couple the two rotary members to each other;
• the casing including a transfer port through which the pressurized hydraulic fluid is pumped from the hydraulic pump to the piston chamber;
• the casing also including an outlet port through the piston to permit pressurized hydraulic fluid to flow from the piston chamber;
• a control valve including a valve element mounted on the piston for movement between an open position spaced from the outlet port and a closed position that generally closes the outlet port when the pumped fluid reaches a predetermined pressure to thereby further increase the pressure of the pressurized hydraulic fluid and actuate the piston and engage the clutch to thereby rotatively couple the pair of rotary members to each other;
• a supplemental pressurized hydraulic fluid supply including a rotary seal assembly that is fixedly mounted within the housing and has seals that seal with the casing to define an inlet chamber that communicates with the inlet port;
• a first passage for feeding hydraulic fluid from the housing to the inlet chamber for flow through the inlet port upon pumping action of the hydraulic pump;
• the first passage having a check valve for preventing flow therethrough from the inlet chamber to the housing;
• a second passage for feeding pressurized hydraulic fluid to the inlet chamber;
• and a source of pressurized hydraulic fluid for selectively providing pressurized hydraulic fluid through the second passage to the inlet chamber independent of pumping action of the pump.

A hydraulic coupling for use with a vehicle drivetrain within a housing thereof containing hydraulic fluid to rotatively couple a pair of rotary members about a rotational axis, the hydraulic coupling comprising:

• a casing of a hollow construction that is rotatable within the housing about the rotational axis;
• a hydraulic pump located within the casing along the rotational axis and including a toothed impeller rotatively connected to one of the rotary members and having external teeth;
• the hydraulic pump also including an internal ring gear mounted by the casing for rotation eccentrically with respect to the toothed impeller and including internal teeth of a number one more than the impeller teeth and in a meshing relationship therewith to provide a pumping action upon relative rotation between the casing and the toothed impeller as the pair of rotary members rotate relative to each other;
• an inlet port through which hydraulic fluid is pumped from the housing into the casing by the hydraulic pump;
• a clutch including a piston chamber located within the casing and having an actuating piston that is received within the piston chamber and actuatable by pressurized hydraulic fluid to engage the clutch and couple the two rotary members to each other;
• the casing including a wall having a transfer port through which the pressurized hydraulic fluid is pumped from a high pressure side of the hydraulic pump to the piston chamber;
• said casing wall also including an outlet port through which pressurized hydraulic fluid flows from the piston chamber to a low pressure side of the pump;
• a control valve including a valve element movable between an open position spaced from the outlet port and a closed position that generally closes the outlet port when the pumped fluid reaches a predetermined pressure to thereby further increase the pressure of the pressurized hydraulic fluid and actuate the piston and engage the clutch to thereby rotatively couple the pair of rotary members to each other;
• a supplemental pressurized hydraulic fluid supply including a rotary seal assembly that is fixedly mounted within the housing and has seals that seal with the casing to define an inlet chamber that communicates with the inlet port;
• a first passage for feeding hydraulic fluid from the housing to the inlet chamber for flow through the inlet port upon pumping action of the hydraulic pump, the first passage having a check valve for preventing flow therethrough from the inlet chamber to the housing;
• a second passage for feeding pressurized hydraulic fluid to the inlet chamber;
• and a source of pressurized hydraulic fluid for selectively providing pressurized hydraulic fluid through the second passage to the inlet chamber independent of the pumping action of the pump.