Hydraulic system for a CVT-transmission of a vehicle
AssigneeZF Friedrichshafen AG
InventorsStefan Sommer, Andreas Piepenbrink
Life of this patent
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Abstract
A hydraulic system of a CVT transmission of a motor vehicle is proposed, which has an oil pump for conveying oil from an oil sump to a variator comprising a first pulley set and a second pulley set. In each case, a valve mechanism is provided for controlling a pressure acting on the pulley set concerned. Between the valve mechanisms associated with the respective pulley sets is arranged a pressure selector valve, whose position determines which of the the valve mechanisms controls a main pressure to be delivered by the oil pump.
Claims12
A hydraulic system of a CVT transmission for a motor vehicle comprising a variator having a first pulley set (8) and a second pulley set (9), the hydraulic system comprising:
- an oil pump (1) to convey oil from an oil slump (3) through a main supply line (5) at a main hydraulic supply pressure (pHD) to a first valve supply line (18) and a second valve supply line (23);
- a first valve mechanism (6) is supplied with oil via the first valve supply line (18) to effect a respective first pressure (pS1) acting on the first pulley set (8), and a second valve mechanism (7) is supplied with oil via the second valve supply line (23) to effect a respective second pressure (pS2) acting on the second pulley set (9);
- and
- wherein a pressure selector valve (20) is connected between the main supply line (5) and the second valve mechanism (7) to regulate the main hydraulic supply pressure (pHD) between the first valve mechanism (6) and the second valve mechanism (7).
A hydraulic system of a CVT transmission for a motor vehicle comprising a variator having a first pulley set (8) and a second pulley set (9), the hydraulic system comprising:
- an oil pump (1) to convey oil from an oil sump (3) through a main supply line (5) at a main hydraulic supply pressure (pHD) to a first valve supply line (18) and a second valve supply line (23);
- a first valve mechanism (6) is supplied with oil via the first valve supply line (18) to effect a respective first pressure (pS1) acting on the first pulley set (8), and a second valve mechanism (7) is supplied with oil vial the second valve supply line (23) to effect a respective second pressure (pS2) acting on the second pulley set (9);
- a pressure selector valve (20) is connected between the main supply line (5) and the second valve mechanism (7) to regulate the main hydraulic supply pressure (pHD) between the first valve mechanism (6) and the second valve mechanism (7);
- and
- wherein the pressure selector valve (2)) has an open position when the second pressure (pS2) is equal to or higher than the first pressure (pS1) plus an offset value to allow the second valve mechanism (7) to control the main supply pressure (pHD), and a substantially closed position when the second pressure (pS2) is lower than the first pressure (pS1) plus the offset value to allow the first valve mechanism (6) to control the main supply pressure (pHD).
Dependencies are inferred from the claim text.