# US 2013/0158824 A1 · Limiting branch pressure to a solenoid valve in a fluid circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0158824 A1 - Document ID: US20130158824A1 - Status: Published application - Kind: A1 - Application number: 13/328,537 - Filed: 2011-12-16 - Published: 2013-06-20 - Earliest claimed: 2011-12-16 - Assignees: GM Global Technology Operations LLC - Inventors: Crystal Nassouri; Steven P. Moorman - Web page: https://patentgrep.com/patent/US20130158824A1 ## CPC - F16H 61/061: {using electric control means} - F16D 48/0206: {in a system with a plurality of fluid-actuated clutches} - F16D 48/066: {Control of fluid pressure, e.g. using an accumulator (F16D48/062, F16D48/068 take precedence)} - F16H 61/688: with two inputs, e.g. selection of one of two torque-flow paths by clutches - F16D 2048/0233: {by rotary pump actuation} - F16D 2048/0278: {Two valves in series arrangement for controlling supply to actuation cylinder} - F16D 2500/30803: Oil temperature - F16D 2500/30805: Oil pressure - F16D 2500/50684: Torque resume after shifting - F16D 2500/70406: Pressure - F16D 2500/70414: Quick displacement to clutch touch point - F16H 59/72: dependent on oil characteristics, e.g. temperature, viscosity - F16H 61/0021: {Generation or control of line pressure} - F16H: GEARING - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES ## Abstract A vehicle includes a clutch, pump, pressure control variable force solenoid (PVFS) valve in a branch supplying oil from the pump to the clutch through a flow control VFS (QVFS), and a controller. The controller calculates an area of a variable orifice of the QVFS valve at the start of a clutch shift, records the area as a maximum area, and calculates a maximum branch pressure as a function of the area. The controller limits pressure in the branch during the shift event to the calculated maximum branch pressure. The transmission may be a dual-clutch transmission (DCT) with the clutch being a DCT input clutch. A control system includes a host machine, temperature and pressure sensors, a computer-readable medium with instructions for limiting branch pressure as a function of the maximum area noted above and using sensor values from the sensors. A method of limiting branch pressure is also disclosed. ## Claims ### Claim 1 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. ### Claim 2 (depends on 1) The vehicle of claim 1, wherein the transmission is a dual-clutch transmission (DCT) and the clutch is one of a pair of input clutches to the DCT. ### Claim 3 (depends on 1) The vehicle of claim 1, wherein the controller calculates the maximum area of the orifice as a function of a commanded branch pressure. ### Claim 4 (depends on 1) The vehicle of claim 1, further comprising a temperature sensor positioned in the fluid circuit in electrical communication with the controller, wherein the temperature sensor measures a temperature of the oil, and wherein the controller calculates the maximum area of the orifice as a function of the measured oil temperature. ### Claim 5 (depends on 4) The vehicle of claim 4, further comprising a lookup table containing a modeled clutch pressure, wherein the controller extracts the modeled clutch pressure from the lookup table and calculates the maximum area of the orifice as a function of the modeled clutch pressure. ### Claim 6 (depends on 1) The vehicle of claim 1, wherein the clutch is an oncoming clutch, further comprising an offgoing clutch in another branch of the fluid circuit, wherein the controller limits pressure to the offgoing clutch by selecting a pressure value from a clutch torque-based lookup table. ### Claim 7 (depends on 1) The vehicle of claim 1, wherein the controller filters the maximum branch pressure using one of a Kalman filter, a weighted average, a rolling average, and a lag filter. ### Claim 8 A control system for a transmission having a clutch, a pump in fluid communication with the clutch through a branch of a fluid circuit, a pressure control variable force solenoid (PVFS), and a flow control variable force solenoid (QVFS) valve, wherein the PVFS and QVFS valves are positioned in the branch upstream of the clutch, the system comprising: a host machine in electrical communication with the clutch, the pump, and the PVFS and QVFS valves; a temperature sensor positioned in the fluid circuit in electrical communication with the host machine, wherein the temperature sensor measures a temperature of the oil; and a tangible, non-transitory computer-readable medium on which is recorded instructions for limiting branch pressure, wherein the host machine executes the instructions from the computer-readable medium to thereby: calculate an area of a variable orifice of the QVFS valve at the start of a clutch shift event as a function of a commanded branch pressure and a measured oil temperature; record the calculated area as a maximum area; calculate, in a calibrated loop during the shift event, a maximum branch pressure in the branch as a function of the calculated maximum area; and limit actual branch pressure in the branch during the shift event to the calculated maximum branch pressure. ### Claim 9 (depends on 8) The control system of claim 8, wherein the controller is configured to limit the branch pressure by transmitting a current command to the PVFS valve. ### Claim 10 (depends on 8) The control system of claim 8, further comprising a lookup table containing a modeled clutch pressure, wherein the host machine extracts the modeled clutch pressure from the lookup table and calculates the maximum area of the orifice as a function of the modeled clutch pressure. ### Claim 11 (depends on 8) The control system of claim 8, wherein the host machine is configured to filter the maximum branch pressure using one of a Kalman filter, a weighted average, a rolling average, and a lag filter. ### Claim 12 A method comprising: calculating an area of a variable orifice of a flow control variable force solenoid (QVFS) valve at the start of a clutch shift event in a vehicle, wherein the vehicle includes a pump that is in fluid communication with a clutch through a pressure control variable force solenoid (PVFS) valve and the QVFS valve in a branch of a fluid circuit; recording the calculated area as a maximum area; calculating, in a calibrated loop during the shift event, a maximum branch pressure in the branch as a function of the calculated maximum area; and limiting, via a controller, fluid pressure in the branch during the shift event to the calculated maximum branch pressure. ### Claim 13 (depends on 12) The method of claim 12, further comprising: measuring a temperature of the oil; and calculating the maximum area of the orifice as a function of the oil temperature. ### Claim 14 (depends on 12) The method of claim 12, further comprising: extracting a modeled clutch pressure from a lookup table using the controller; and calculating the maximum area of the orifice as a function of the modeled clutch pressure. ### Claim 15 (depends on 12) The method of claim 12, wherein the clutch is an oncoming clutch in the shift event, further comprising: limiting pressure to an off-going clutch to a pressure value selected from a clutch torque-based lookup table. ### Claim 16 (depends on 12) The method of claim 12, further comprising filtering the calculated maximum branch pressure using one of a Kalman filter, a weighted average, a rolling average, and a lag filter.