Double piston and belt type continuously variable transmission
AssigneeJATCO Ltd
InventorsTakeo Hiramatsu, Yoshihiro Kono, Seiichiro Takahashi, Jonggap Kim, Yasushi Yabe
Life of this patent
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Abstract
A double piston and belt type continuously variable transmission comprises a primary pulley provided with a primary piston chamber and a primary clamp chamber; a secondary pulley provided with a secondary piston chamber and a secondary clamp chamber; and an endless belt operatively put around the primary and secondary pulleys. A switching circuit is arranged to connect both the primary and secondary clamp chambers to either one of the primary and secondary piston chambers, which shows a higher hydraulic pressure than the other.
Claims14
A double piston and belt type continuously variable transmission comprising:
- a primary pulley provided with a primary piston chamber and a primary clamp chamber;
- a secondary pulley provided with a secondary piston chamber and a secondary clamp chamber;
- an endless belt operatively put around the primary and secondary pulleys;
- and
- a switching circuit that includes a switching valve that selectively connects both the primary and secondary clamp chambers to either one of the primary and secondary piston chambers, the selected piston chamber being higher in hydraulic pressure than the other piston chamber, so that the higher hydraulic pressure in the selected piston chamber is led into both the primary and secondary clamp chambers,
- wherein the switching circuit comprises a hydraulic passage that connects the primary and secondary clamp chambers, and
- wherein the switching valve is arranged in the hydraulic passage to connect the hydraulic passage to the selected piston chamber.
A double piston and belt type continuously variable transmission comprising:
- a primary pulley provided with a primary piston chamber and a primary clamp chamber;
- a secondary pulley provided with a secondary piston chamber and a secondary clamp chamber;
- an endless belt operatively put around the primary and secondary pulleys;
- a hydraulic passage that connects the primary and secondary clamp chambers;
- a pressure control circuit that connects the primary and secondary piston chambers and the primary and secondary clamp chambers by hydraulic passages, wherein the pressure control circuit includes a switching valve that selectively connects both the primary and secondary clamp chambers to either one of the primary and secondary piston chambers;
- and
- a control unit that is connected to the control circuit, the control unit being configured to carry out:
- detecting pressures of the primary and secondary piston chambers;
- deriving an actual clamp pressure that is actually exerted in the primary and secondary clamp chambers;
- calculating a difference between the actual clamp pressure and a target clamp pressure when the actual clamp pressure is lower than the target clamp pressure;
- calculating a thrust that corresponds to the calculated difference;
- calculating a hydraulic pressure that is needed for producing the calculated thrust;
- and
- adding the calculated hydraulic pressure to the pressure of either one of the primary piston chamber and the secondary piston chamber that has a pressure lower than that of the other of the primary piston chamber and the secondary piston chamber.
Dependencies are inferred from the claim text.