# US 2015/0105992 A1 · Vehicle drive train control method and system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0105992 A1 - Document ID: US20150105992A1 - Status: Published application - Kind: A1 - Application number: 14/382,376 - Filed: 2012-03-09 - Published: 2015-04-16 - Earliest claimed: 2012-03-09 - Assignees: Volvo Lastvagnar AB - Inventors: Lena Larsson; Jan Öberg; Filip Alm - Web page: https://patentgrep.com/patent/US20150105992A1 ## CPC - B60W 20/19: for achieving enhanced acceleration - B60K 6/12: by means of a chargeable fluidic accumulator - B60K 23/0808: {for varying torque distribution between driven axles, e.g. by transfer clutch} - B60K 28/16: responsive to, or preventing, spinning or skidding of wheels - B60W 30/18027: {Drive off, accelerating from standstill} - B60W 2520/26: Wheel slip - B60W 2540/18: Steering angle - B60W 2552/40: Coefficient of friction - B60W 2710/083: Torque - B60W 2710/207: Steering angle of wheels - 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 - 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 ## Abstract A vehicle traction system includes a first traction wheel forming part of a first propulsion system including a mechanical drive train, a second traction wheel forming part of a second propulsion system including a hydraulic pump for powering a hydraulic motor, one sensor indicating a take-off condition, and a control unit for controlling the second propulsion unit. The control unit is programmed to automatically detect a take-off condition by the sensor and send an input to the control unit that a take-off condition is fulfilled, automatically provide a traction force from the second propulsion system in response to the indication that there is a take-off condition of the vehicle present and an indication that a traction is or will be provided by the first traction system, and automatically control the second propulsion unit by the control unit in dependence of the manually controlled torque from the first propulsion unit. ## Claims ### Claim 1 A method for controlling a traction system (1) of a vehicle, said system comprising a first traction wheel (2a) forming part of a first propulsion system (12) comprising a mechanical drive train including an internal combustion engine (4) which provides a traction force to said first traction wheel (2a) via a gearbox (5), a second traction wheel (6a) forming part of a second propulsion system (13) comprising a hydraulic pump (7) for powering a hydraulic motor (8a) in order to provide a traction force to said second traction wheel (6a), at least one sensor (10a, 10b, 10c, 14) indicating a take-off condition, a control unit (9) for controlling said second propulsion unit (13), wherein said method comprises the steps of automatically detecting a take-off condition by said sensor (10a, 10b, 10c, 14) and sending an input to the control unit (9) that a take-off condition is fulfilled automatically provide a traction force from said second propulsion system (13) in response to the indication that there is a take-off condition of the vehicle present and/or an indication that a traction is or will be provided by the first traction system, manually controlling the torque from the first propulsion unit (12), automatically controlling said second propulsion unit (13) by the control unit (9). ### Claim 2 (depends on 1) A method according to claim 1, characterized in that the torque from the second propulsion unit (13) is controlled in dependence of the torque from the first propulsion unit (12) during a take-off. ### Claim 3 A method according to any previous claim, characterized in that the torque from the second propulsion unit (13) during take-off is controlled in dependence of at least one of load on the second traction wheel (6a), a friction coefficient between ground and the second traction wheel (6a), a maximum allowable slip of the second traction wheel (6a) or a steering angle of the second traction wheel (6a). ### Claim 4 A method according to any previous claim, characterized in that said indication that a traction is or will be provided by the first traction system comprises the engagement of a clutch arranged to transmit torque between the internal combustion engine (4) and the gearbox (5). ### Claim 5 A method according to any previous claim, characterized in that said indication that a traction is or will be provided by the first traction system comprises a gear shift of the gearbox (5) from neutral to a forward or reverse gear at standstill. ### Claim 6 A method according to any previous claim, characterized in that said indication that a traction is or will be provided by the first traction system is the acceleration from standstill. ### Claim 7 A method according to any previous claim, characterized in that there is a fixed minimum torque provided by the second propulsion system when the automatic take-off aid control system is activated and provide this torque until the torque from the mechanically driven wheels is above a certain limit where after the torque from the second propulsion system will increase and be proportional to the torque from the first propulsion system. ### Claim 8 A method according to any previous claim, characterized in that the torque from second propulsion system will only continue until the speed of the vehicle is above a certain limit. ### Claim 9 A method according to any previous claim, characterized in that the drive train control system comprises sensors concerning traction of one or several wheels, e.g speed sensors for the individual wheels and a vehicle speed sensor, such that traction from the wheels are sensed and slip may be detected such that the control is programmed to reduce the torque onto the surface from the wheel(s) connected to the second, hydraulic traction system if there is a slip detected on the hydraulically driven wheels. ### Claim 10 A method according to any previous claim characterized in that said hydraulic pump (7) in the hydraulic propulsion system (13) is a reversible variable displacement pump. ### Claim 11 (depends on 6) A method according to claim 6 characterized in that said hydraulic propulsion system (13) comprises a pair of hydraulic wheel motors (8a, 8b) connected in parallel and located at a respective steerable front wheel (6a, 6b). ### Claim 12 A traction system (1) of a vehicle, said system comprising a first traction wheel (2a) forming part of a first propulsion system (12) comprising a mechanical drive train including an internal combustion engine (4) which provides a traction force to said first traction wheel (2a) via a gearbox (5), a second traction wheel (6a) forming part of a second propulsion system (13) comprising a hydraulic pump (7) for powering a hydraulic motor (8a) in order to provide a traction force to said second traction wheel (6a), at least one sensor (10a, 10b, 10c, 14) indicating a take-off condition, a control unit (9) for controlling said second propulsion unit (13), wherein said control unit is programmed to automatically detecting a take-off condition by said sensor (10a, 10b, 10c, 14) and sending an input to the control unit (9) that a take-off condition is fulfilled automatically provide a traction force from said second propulsion system (13) in response to the indication that there is a take-off condition of the vehicle present and an indication that a traction is or will be provided by the first traction system, automatically controlling said second propulsion unit (13) by the control unit (9) in dependence of the manually controlled torque from the first propulsion unit (12). ### Claim 13 A traction system (1) for a vehicle according to claim characterized in that said hydraulic pump (7) is connected to an output shaft of said internal combustion engine (4). ### Claim 14 (depends on 12, 13) A traction system (1) for a vehicle according to claim 12 or 13 characterized in that said hydraulic pump (7) is connected to a pair of hydraulic motors (8a, 8b), each one located at each one of a pair of traction wheels (6a, 6b), said pair of hydraulic motors (8a, 8b) arranged in parallel. ### Claim 15 (depends on 12, 13, 14) A heavy vehicle such as a truck or bus characterized in that it comprises a traction system (1) according to any of claims 12-14.