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AssigneeTorotrak (Development) Limited
InventorJohn William Edward Fuller
Estimating the term…
A hydraulic control circuit is disclosed for a continuously variable transmission comprising a continuously variable ratio transmission unit (“variator”) 10, the circuit comprising a supply line 106 and means (which may take the form of a pump 110) for providing a flow of pressurised fluid in the supply line, means (which may comprise a pressure control valve 116) for generating a back pressure in the supply line, and at least one connection for feeding fluid from the supply line to a hydraulic actuator 100 acting on a movable torque transmission 23-37 element (which may comprise a roller 28) of the variator 10. The valve means 152 connected to the supply line allows pressure in the supply line to be selectively modified in response to rate of flow in the supply line.
A hydraulic circuit for a continuously variable transmission comprising a continuously variable ratio transmission unit (“variator”) which is controllable by application of fluid pressure to at least one hydraulic actuator acting on a movable torque transmission element of the variator, the circuit comprising a fluid supply line connected to the hydraulic actuator for feeding fluid to and from the hydraulic actuator, means for providing a flow of fluid through the fluid supply line, variable control valve means in the fluid supply line downstream of the connection to the hydraulic actuator for generating an adjustable back pressure therein, and further valve means connected to the fluid supply line to selectively modify pressure in the supply line in response to rate of fluid flow in the supply line.
A hydraulic control circuit as claimed in any of claims 2 to 5 wherein the valve has a variable opening controlled as a function of supply line flow rate.
A hydraulic control circuit as claimed in any preceding claim, further comprising a flow restrictor in the flow line.
A hydraulic control circuit as claimed in any preceding claim, wherein the further valve means controls a path to a low pressure area in order to vent excess flow from the flow line.
A hydraulic control circuit as claimed in any preceding claim, wherein the further valve means controls a path connected to a pressurized accumulator in order to selectively supplement fluid flow in the flow line.
A hydraulic control circuit as claimed in any preceding claim, wherein the further valve means controls respective paths to a low pressure area and to a pressurized accumulator.
A hydraulic control circuit as claimed in any of the preceding claims, comprising a pair of fluid supply lines, the hydraulic actuator being double acting and receiving opposed fluid pressures from the two supply lines, each supply line having a said variable control valve means and a said further valve means.
Dependencies are inferred from the claim text.