Patent ID: 7306538
Filing Date: 2007-12-11
Classification: F16H,Y10T

Abstract:
1. A hydraulic control apparatus for an automatic transmission, the automatic transmission being coupled to an engine and including a transmission mechanism, a first sprocket rotatably driven by the engine, a second sprocket coupled to the first sprocket via a chain therebetween, an oil pump disposed spaced from the transmission mechanism and connected with the second sprocket, the oil pump being driven by the engine via the first and second sprockets and the chain so as to produce an oil pressure, and a line pressure regulator valve operative to regulate the oil pressure produced by the oil pump and set a line pressure to be supplied to the transmission mechanism, the hydraulic control apparatus comprising: a control unit outputting a first command for controlling the line pressure regulator valve to set the line pressure to a minimum value immediately after start of the engine, and a second command for controlling the line pressure regulator valve to set the line pressure to a target value at which the transmission mechanism is operable in accordance with increase in engine speed after the start of the engine, the control unit being programmed to set the target value of the line pressure to a value smaller than a maximum value of the line pressure to thereby suppress an amount of oil discharged from the oil pump, upon start of the engine in a low temperature condition.