# US 9,434,251 B2 · All-wheel drive failsafe action axle torque calculation method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,434,251 B2 - Document ID: US9434251B2 - Status: Granted - Kind: B2 - Application number: 14/333,634 - Filed: 2014-07-17 - Published: 2016-01-21 - Granted: 2016-09-06 - Earliest claimed: 2014-07-17 - Assignees: Honda Motor Co., Ltd. - Applicants: Honda Motor Co., Ltd. - Inventors: Steve Turner - Web page: https://patentgrep.com/patent/US9434251B2 ## CPC - B60K 23/0808: {for varying torque distribution between driven axles, e.g. by transfer clutch} - B60W 10/06: including control of combustion engines - B60W 10/11: Stepped gearings - B60W 10/119: including control of all-wheel-driveline means, e.g. transfer gears or clutches for dividing torque between front and rear axle (B60W10/14 takes precedence) - B60W 50/035: Bringing the control units into a predefined state, e.g. giving priority to particular actuators - B60W 50/038: Limiting the input power, torque or speed - F02D 41/021: {Introducing corrections for particular conditions exterior to the engine (conjoint control of vehicle sub-units for propelling the vehicle B60W30/18)} - B60K 2023/085: {automatically actuated} - B60W 2510/0638: Engine speed - B60W 2510/1005: Transmission ratio engaged - B60W 2710/0644: Engine speed - B60W 2710/0666: Engine torque - B60W 2720/403: between front and rear axle - F02D 29/02: peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers - F02D 2250/26: by applying a torque limit - 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 - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) ## Abstract A method of controlling an all-wheel drive system of a vehicle includes supplying torque to front and rear wheels of the vehicle, sensing a failure of the all-wheel drive system, and adjusting a crankshaft torque of an engine of the vehicle so that the front wheel torque remains constant regardless of a failure of the all-wheel drive system. ## Claims ### Claim 1 A method of controlling an all-wheel drive system of a vehicle, comprising: supplying torque from an engine of the vehicle to front and rear wheels of the vehicle; sensing a failure of the all-wheel drive system with a sensor; adjusting a crankshaft torque of the engine with a controller so that the front wheel torque remains constant regardless of a failure of the all-wheel drive system; calculating a value of the torque that is supplied to the front wheels prior to a failure of the all-wheel drive system; and determining the adjusted crankshaft torque based upon the calculated front wheel torque. ### Claim 2 (depends on 1) The method of controlling an all-wheel drive system of a vehicle of claim 1, wherein the torque supplied to the front wheels subsequent to a failure of the all-wheel drive system is greater than the torque supplied to the rear wheels subsequent to a failure of the all-wheel drive system. ### Claim 3 (depends on 2) The method of controlling an all-wheel drive system of a vehicle of claim 2, further including adjusting the crankshaft torque so that a value of the torque supplied to the rear wheels subsequent to a failure of the all-wheel drive system is equal to zero. ### Claim 4 (depends on 1) The method of controlling an all-wheel drive system of a vehicle of claim 1, wherein the adjusted crankshaft torque is determined by the equation: ACT=CFWT/(GR×E)/TCG, and wherein ACT equals the adjusted crankshaft torque, CFWT equals a calculated front wheel torque, GR equals a transmission gear ratio, E equals a transmission efficiency, and TCG equals a torque converter gain. ### Claim 5 (depends on 4) The method of controlling an all-wheel drive system of a vehicle of claim 4, further including determining the transmission gear ratio, the transmission efficiency, and the torque converter gain from a look-up table, wherein the torque converter gain is based upon a rotational speed of a torque converter of the vehicle. ### Claim 6 (depends on 4) The method of controlling an all-wheel drive system of a vehicle of claim 4, wherein the calculated front wheel torque is based upon a crankshaft torque of the vehicle and a gear position of a transmission of the vehicle. ### Claim 7 A method of controlling a vehicle with an all-wheel drive system, comprising: sensing a gear position of a transmission of the vehicle; supplying torque of a crankshaft of an engine to front wheels and rear wheels of the vehicle; sensing a rotational speed of the crankshaft; detecting whether there is a failure of the all-wheel drive system with a sensor; and limiting the supplied torque to the front wheels for a predetermined time period after a failure of the all-wheel drive system is detected, wherein the limited torque supplied to the front wheels is based upon the gear position of the transmission and the rotational speed of the crankshaft, wherein the limited torque supplied to the rear wheels during the predetermined time period is equal to zero, and wherein subsequent to the predetermined time period, the crankshaft torque is increased at a predetermined rate until being equal to the crankshaft torque prior to the failure of the all-wheel drive system. ### Claim 8 (depends on 7) The method of controlling an all-wheel drive system of a vehicle of claim 7, wherein the predetermined time period is about three seconds. ### Claim 9 (depends on 7) The method of controlling an all-wheel drive system of a vehicle of claim 7, wherein the predetermined rate is about 1.5 Newton-meters per 10 milliseconds. ### Claim 10 (depends on 7) The method of controlling an all-wheel drive system of a vehicle of claim 7, wherein the limited torque supplied to the front wheels is controlled by reducing a rotational speed of an engine of the vehicle. ### Claim 11 A vehicle, comprising: an all-wheel drive system including an engine that outputs crankshaft torque through a crankshaft, a transmission that is coupled to the engine and supplies front wheel torque to front wheels of the vehicle, a propeller shaft rotated by the transmission, and a rear differential unit powered by the propeller shaft and supplies rear wheel torque to rear wheels of the vehicle; an oil pump motor associated with the rear differential unit; a temperature sensor that is configured to sense a temperature within the rear differential unit; and a controller that controls operation of the all-wheel drive system and is configured to receive signals indicative of a failure of the all-wheel drive system, wherein the controller is configured to adjust the crankshaft torque upon receiving a failure signal so that the front wheel torque remains constant during a predetermined time period in which the failure of the all-wheel drive system occurs, wherein the controller is configured to receive signals from the oil pump motor and the temperature sensor, and wherein the controller is configured to determine if a failure of the all-wheel drive system has occurred based upon the signals from the oil pump motor and the temperature sensor. ### Claim 12 (depends on 11) The vehicle of claim 11, wherein the controller adjusts the crankshaft torque upon receiving a failure signal so that the front wheel torque remains constant by determining the adjusted crankshaft torque with the equation: ACT=CFWT/(GR×E)/TCG, and wherein ACT equals the adjusted crankshaft torque, CFWT equals a calculated front wheel torque, GR equals a transmission gear ratio, E equals a transmission efficiency, and TCG equals a torque converter gain. ### Claim 13 (depends on 12) The vehicle of claim 12, further including a torque converter disposed in the transmission and a torque converter speed sensor configured to sense a rotational speed of the torque converter and send a signal indicative of the rotational speed of the torque converter to the controller. ### Claim 14 (depends on 13) The vehicle of claim 13, wherein the controller includes a lookup table including a transmission gear ratio, a transmission efficiency, and a torque converter gain, and wherein the torque converter gain is based upon the torque converter rotational speed signal. ### Claim 15 (depends on 12) The vehicle of claim 12, further including a gear position sensor configured to sense a gear position of the transmission and send a gear position signal to the controller, and a crankshaft sensor configured to sense a rotational speed of the crankshaft and send a crankshaft speed signal to the controller, wherein the controller is configured to calculate front wheel torque based upon the gear position signal and the crankshaft speed signal. ### Claim 16 (depends on 11) The vehicle of claim 11, wherein the controller controls the all-wheel drive system so that a value of the rear wheel torque equals zero subsequent to the controller receiving a signal indicative of a failure of the all-wheel drive system.