# US 7,611,441 B2 · Torque transfer control system for power transmission device in a motor vehicle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,611,441 B2 - Document ID: US7611441B2 - Status: Granted - Kind: B2 - Application number: 12/263,824 - Filed: 2008-11-03 - Published: 2009-03-05 - Granted: 2009-11-03 - Earliest claimed: 2003-11-07 - Assignees: Magna Powertrain USA, Inc. - Inventors: Brent A. Cring - Web page: https://patentgrep.com/patent/US7611441B2 ## CPC - B60K 23/0808: {for varying torque distribution between driven axles, e.g. by transfer clutch} - B60W 2510/0657: Engine torque - B60W 2710/027: Clutch torque - B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES - B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT ## Abstract A torque transfer mechanism includes a multi-plate clutch assembly that is operably disposed between a first rotary and a second rotary member. A control system determines a desired quantity of torque to deliver to the second rotary member and controls the clutch to produce the desired torque. ## Claims ### Claim 1 A power transmission device for use in a motor vehicle having a powertrain and first and second drivelines for transferring torque to vehicle wheels, comprising: a first rotary member operable for transferring drive torque from the powertrain to the first driveline; a second rotary member driving the second driveline; a multi-plate friction clutch operably disposed between said first and second rotary members; a clutch operator for applying a clutch engagement force on said friction clutch so as to transfer drive torque from said first rotary member to said second rotary member; a clutch actuator operable to control movement of said clutch operator relative to said friction clutch in response to a control signal; and a control system for generating said control signal and causing said clutch actuator to move said clutch operator to a predetermined position corresponding to a desired torque value that is transferred across said friction clutch prior to wheel slip, said desired torque value being a function of an input torque value applied to said first rotary member, and wherein said input torque value is determined as a function of a torque converter torque ratio, an engine torque value and a transmission gear ratio. ### Claim 2 (depends on 1) The power transmission device of claim 1 wherein said torque converter torque ratio is a function of a torque converter speed ratio determined by said control system. ### Claim 3 (depends on 2) The power transmission device of claim 2 wherein said torque converter speed ratio is a function of an engine speed value, said transmission gear ratio and rotary speed value of said second rotary member. ### Claim 4 A method of controlling torque transfer between first and second rotary members across a friction clutch within a torque transfer coupling of a motor vehicle, the method comprising the steps of: determining a torque converter speed ratio; determining a torque converter torque ratio based on said torque converter speed ratio; determining an input torque value transmitted to the first rotary member; determining a desired output torque value to be transmitted across the friction clutch from the first rotary member to the second rotary member based on said torque converter torque ratio and said input torque value; and selectively actuating the friction clutch in one of at least two modes without regard to a relative speed difference between the first and second rotary members, wherein a two-wheel drive mode maintains the friction clutch in a non-engaged condition and a four-wheel drive mode regulates engagement of the friction clutch for transferring said desired output torque value to the second rotary member. ### Claim 5 (depends on 4) The method of claim 4 wherein the step of determining said torque converter speed ratio includes: determining an engine speed value of an engine; determining a current transmission gear ratio of a transmission disposed between said engine and the first rotary member; and determining a rotary speed value of the second rotary member. ### Claim 6 (depends on 5) The method of claim 5 wherein said step of determining said input torque includes determining an engine torque value of said engine. ### Claim 7 (depends on 1) The power transmission device of claim 1 further including a sensor operable to provide said control system a signal indicative of the position of said clutch operator. ### Claim 8 (depends on 7) The power transmission of claim 7 wherein said control system modifies a correlation between said clutch operator position and said torque transferred by said friction clutch to account for clutch wear. ### Claim 9 (depends on 1) The power transmission of claim 1 wherein said control system is operable to generate said control signal and said friction clutch transfers said desired torque value irrespective of the magnitude of relative rotation between the first and second rotary members. ### Claim 10 A method of controlling torque transfer between first and second rotary members across a friction clutch within a torque transfer coupling of a motor vehicle, the method comprising the steps of: determining a vehicle speed; determining a steering angle; determining a torque converter speed ratio; determining a desired output torque to be transmitted across the friction clutch from the first rotary member to the second rotary member based on said vehicle speed, said torque converter speed ratio and said steering angle, wherein said desired output torque is decreased as said steering angle increases; and selectively actuating the friction clutch, prior to a vehicle wheel slip, in one of at least two modes wherein a two-wheel drive mode maintains the friction clutch in a non-engaged condition and a four-wheel drive mode regulates engagement of the friction clutch for transferring said desired output torque value to the second rotary member.