Clutch apparatus for a hydrostatic continuously variable transmission and transmission incorporating same

A hydrostatic continuously variable transmission and clutch assembly, comprising:

• a support shaft having a hollow internal bore extending axially therein;
• a hydraulic pump and a hydraulic motor respectively mounted on the support shaft, connected to each other through a hydraulic closed circuit, and wherein the capacity of said hydraulic motor or of said hydraulic pump is variably controlled to modify a rotary input fed into said hydraulic pump and to transmit the modified input as a rotary output of said hydraulic motor, wherein said hydraulic pump comprises a pump casing;
• and
• a clutch apparatus integrated into said transmission, said clutch apparatus comprising:
• a valve spool which is movably disposed in said internal bore of said support shaft, and which operates to allow or to interrupt fluid communication between a high pressure side oil passage and a low pressure side oil passage of said hydraulic closed circuit, according to the position thereof;
• a rotatable clutch cap operatively attached to said hydraulic pump;
• and
• a governor mechanism which is operatively associated with said clutch cap, and which operates to generate a governor force corresponding to a rotating speed of said clutch cap by use of a centrifugal force generated by rotation of said clutch cap;
• wherein
• said valve spool moves in said internal bore in response to said governor force generated by said governor mechanism.

A hydrostatic continuously variable transmission and clutch assembly, comprising:

• a support shaft having a hollow internal bore extending axially therein;
• a hydraulic pump and a hydraulic motor respectively mounted on the support shaft, connected to each other through a hydraulic circuit, and configured so that the capacity of said hydraulic motor or of said hydraulic pump is variably controlled to modify a rotary input fed into said hydraulic pump and to transmit the modified input as a rotary output of said hydraulic motor, wherein said hydraulic pump comprises a pump casing;
• and
• a clutch apparatus integrated with said transmission, said clutch apparatus comprising:
• a valve spool which is slidably disposed in said internal bore of said support shaft, and which operates to allow or to interrupt fluid communication between a high pressure side oil passage and a low pressure side oil passage of said hydraulic closed circuit, according to the position thereof;
• a rotatable clutch cap operatively connected to an end portion of said pump casing and having a plurality of guide grooves formed in an interior surface thereof, said clutch cap having a through hole formed substantially centrally therein;
• a plurality of weights disposed in said clutch cap, one of said weights provided for each of the respective guide grooves of said clutch cap;
• a clutch member disposed inside of the clutch cap and comprising a plurality of arm portions, with a respective arm portion extending radially outwardly proximate each of said guide grooves, an inner end of said clutch member being operatively attached to an end of said valve spool, and an outer end of said clutch member comprising a cylindrical end portion which fits slidably in the through hole of said clutch cap;
• and
• a spring disposed between said clutch member and said pump casing urging said clutch member outwardly;
• wherein the spring urges the arm portions of the clutch member outwardly and to thereby pushes the weights radially inwardly in the guide grooves, maintaining the valve spool in a first orientation thereof, when the rotary speed of the pump casing is below a threshold speed.