Method and apparatus for applying and releasing a clutch
View Patent ↗An apparatus for applying and releasing a clutch piston in a clutch cylinder against a return spring includes a fill oil chamber having first and second portions separated by a fill piston. The first portion is in fluid communication with the clutch cylinder through a first passage, and the second portion is in fluid communication with a second passage. A third passage is in fluid communication with the first passage. A fill control valve is operative to alternately communicate the second passage to a transmission line pressure passage or an exhaust passage. The fill control valve is further operative to alternately communicate the third passage to a controllable source of pressurized oil having a signal pressure, or to close the third passage.
1. An apparatus for applying and releasing a clutch piston in a clutch cylinder, the apparatus comprising:
a fill oil chamber having first and second portions separated by a fill piston, said first portion being a fluid communication with the clutch cylinder through a first passage, and said second portion being in fluid communication with a second passage; wherein said fill oil chamber is positioned below the lowest sump level of a transmission in which the apparatus is positioned;
a third passage in fluid communication with the first passage; and
a fill control valve operative to alternately communicate the second passage to a transmission line pressure passage or an exhaust passage, and further operative to alternately communicate the third passage to a controllable source of pressurized oil having a signal pressure separate from said transmission line pressure or to close the third passage.
2. The apparatus of claim 1 , wherein said fill control valve comprises a double spool valve biased by a spring.
3. The apparatus of claim 1 , wherein said third passage is connected to the first passage through an orifice.
4. The apparatus of claim 1 , further comprising a snubber formed in the fill oil chamber to cushion movement of the clutch piston when applying the clutch piston.
5. The apparatus of claim 1 , wherein the apparatus is operative to switch between application of line pressure or signal pressure to the clutch piston to cause a rapid, controlled application and release of the clutch piston.
6. A method for applying and releasing a clutch piston in a clutch cylinder, the method comprising:
providing a source of transmission line pressure;
providing a controllable source of pressurized oil having a signal pressure separate from said transmission line pressure; and
alternately communicating the clutch cylinder with the source of transmission line pressure and the controllable source of pressurized oil to control application and release of the clutch piston; wherein said step of alternately communicating comprises, when applying the clutch piston, communicating said source of transmission line pressure with the clutch cylinder via a fill piston until the fill piston bottoms out, and then communicating said controllable source of pressurized oil to the clutch cylinder to cause a smooth, controlled clutch application.
7. The method of claim 6 , further comprising controlling said controllable source of pressurized oil to control the normal force on a clutch pack applied by the clutch piston during applying, holding and releasing of a clutch.
8. A method for applying and releasing a clutch piston in a clutch cylinder, the method comprising:
providing a source of transmission line pressure;
providing a controllable source of pressurized oil having a signal pressure; alternately communicating the clutch cylinder with the source of transmission line pressure and the controllable source of pressurized oil to control application and release of the clutch piston; wherein said step of alternately communicating comprises, when applying the clutch piston, communicating said source of transmission line pressure with the clutch cylinder via a fill piston until the till piston bottoms out, and then communicating said controllable source of pressurized oil to the clutch cylinder to cause a smooth, controlled clutch application;
controlling said controllable source of pressurized oil to control the normal force on a clutch pack applied by the clutch piston during applying, holding and releasing of a clutch; and
reducing pressure of said controllable source of pressurized oil to enable a spool valve spring to move a spool valve to exhaust pressure from the clutch cylinder and allow a clutch return spring to move oil from the clutch cylinder to a fill oil chamber to be available for the next apply stroke.
9. A method for applying and releasing a clutch piston in a clutch cylinder, the method comprising:
providing a source of transmission line pressure;
providing a controllable source of pressurized oil having a signal pressure separate from said transmission line pressure;
communicating said source of transmission line pressure with the clutch cylinder via a fill piston until the fill piston bottoms out;
thereafter communicating said controllable source of pressurized oil to the clutch cylinder to cause a smooth, controlled clutch application; and
controlling said controllable source of pressurized oil to control the normal force on a clutch pack applied by the clutch piston during applying, holding and releasing of the clutch pack.