Patent ID: 8577565

Claim:
A vehicle comprising: a transmission having a clutch; a pump in fluid communication with the clutch through a branch of a fluid circuit; a flow control variable force solenoid (QFVS) positioned in the branch; a pressure control variable force solenoid (PVFS) valve positioned in the branch upstream of the QVFS, wherein the PVFS valve supplies oil from the pump to the QVFS valve; and a controller in electrical communication with the clutch, the pump, the PVFS valve; wherein the controller: calculates an area of a variable orifice of the QVFS valve at the start of a clutch shift event; records the calculated area as a maximum area; calculates, in a calibrated loop during the shift event, a maximum allowable branch pressure in the branch as a function of the calculated maximum area; and limits actual branch pressure in the branch during the shift event to the calculated maximum allowable branch pressure.