# US 8,739,915 B2 · Drivetrain and method for controlling a drivetrain > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,739,915 B2 - Document ID: US8739915B2 - Status: Granted - Kind: B2 - Application number: 11/715,127 - Filed: 2007-03-07 - Published: 2008-02-07 - Granted: 2014-06-03 - Earliest claimed: 2004-09-16 - Assignees: GETRAG Driveline Systems GmbH - Applicants: Michael Hoeck; Hans-Peter Nett; Michael Auweiler - Inventors: Michael Hoeck; Hans-Peter Nett; Michael Auweiler - Web page: https://patentgrep.com/patent/US8739915B2 ## CPC - B60K 23/0808: {for varying torque distribution between driven axles, e.g. by transfer clutch} - B60K 17/35: including arrangements for suppressing or influencing the power transfer, e.g. viscous clutches - B60K 17/344: having a transfer gear - B60W 2520/125: Lateral acceleration - B60W 2540/18: Steering angle - B60W 2720/14: Yaw - 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 drivetrain for a motor vehicle, which has a permanently driven rear axle and a front axle which is driven on demand. The drivetrain comprises a drive unit whose output is connected to an input member of a differential of the rear axle and to a clutch arrangement for driving the front axle. The clutch arrangement has a first and a second friction clutch which can be controlled substantially independently of one another. The input members of said friction clutches are connected to the output of the drive unit. The output members of said friction clutches being connected respectively to a left and to a right driveshaft of the front axle. ## Claims ### Claim 1 A drivetrain for a motor vehicle, which has a permanently driven rear axle and a front axle which is driven on demand, having a drive unit whose output is connected to an input member of a differential of the rear axle and to a clutch arrangement for driving the front axle, with the clutch arrangement having a first and a second friction clutch which can be controlled substantially independently of one another, with the input members of said friction clutches being connected to the output of the drive unit, and with the output members of said friction clutches being connected respectively to a left and to a right driveshaft of the front axle, wherein the friction clutches directly connect the respective input members of the left and right driveshafts of the front axle, wherein the output of the drive unit is connected to a gear wheel which is connected to an intermediate shaft which is concentric with respect to the front axle, and wherein the intermediate shaft drives a cardan shaft via angular gearing, which cardan shaft is connected to the input member of the differential of the rear axle, wherein a transmission ratio difference is set up between the rear and the front axle such that, when the first and second friction clutches are fully closed, the front axle is driven with a higher rotational speed than the rear axle, wherein said transmission ratio difference is set up to be permanent, and wherein the first and second friction clutches are independently controlled. ### Claim 2 (depends on 1) The drivetrain as claimed in claim 1, wherein the drive unit is arranged in the region of the front axle. ### Claim 3 (depends on 2) The drivetrain as claimed in claim 2, wherein the drive unit is arranged in the region of the front axle, transversely with respect to the longitudinal direction of the motor vehicle. ### Claim 4 (depends on 1) The drivetrain as claimed in claim 1, wherein a ring gear is fastened to the intermediate shaft, which ring gear drives the cardan shaft. ### Claim 5 (depends on 1) The drivetrain as claimed in claim 1, wherein the intermediate shaft is connected to the input of the clutch arrangement. ### Claim 6 (depends on 1) The drivetrain as claimed in claim 1, wherein the friction clutches are arranged concentrically with respect to the front axle. ### Claim 7 (depends on 1) The drivetrain as claimed in claim 1, wherein the friction clutches have a common input member. ### Claim 8 (depends on 1) The drivetrain as claimed in claim 1, wherein the transmission ratio difference is in the range between 0.1 and 20%. ### Claim 9 (depends on 8) The drivetrain as claimed in claim 8, wherein the transmission ratio difference is in the range between 0.5 and 3%. ### Claim 10 (depends on 1) The drivetrain as claimed in claim 1, wherein the transmission ratio difference is selected such that the rotational speed of the front axle is higher than the rotational speed of the rear axle. ### Claim 11 A drivetrain for a motor vehicle, which has a permanently driven rear axle and a front axle which is driven on demand, having a drive unit whose output is connected to an input member of a differential of the rear axle and to a clutch arrangement for driving the front axle, with the clutch arrangement having a first and a second friction clutch which can be controlled substantially independently of one another, with the input members of said friction clutches being connected to the output of the drive unit, and with the output members of said friction clutches being connected respectively to a left and to a right driveshaft of the front axle, wherein a transmission ratio difference is set up between the rear and the front axle, and wherein the transmission ratio difference is selected such that the rotational speed of the front axle is higher than the rotational speed of the rear axle, such that when the independently-controlled first and second friction clutches are fully closed the front axle is driven with a higher rotational speed than the rear axle, wherein said transmission ratio difference is set up to be permanent, and wherein a positive yaw moment is able to be generated in the direction of a corner by individually or independently actuating the first and second friction clutches. ### Claim 12 (depends on 11) The drivetrain as claimed in claim 11, wherein the friction clutches are arranged concentrically with respect to the front axle. ### Claim 13 (depends on 11) The drivetrain as claimed in claim 11, wherein the friction clutches have a common input member. ### Claim 14 (depends on 11) The drivetrain as claimed in claim 11, wherein the transmission ratio difference is in the range between 0.1 and 20%. ### Claim 15 (depends on 11) The drivetrain as claimed in claim 11, wherein the transmission ratio difference is in the range between 0.5 and 3%. ### Claim 16 A drivetrain for a motor vehicle, which has a permanently driven rear axle and a front axle which is driven on demand, having a drive unit whose output is connected to an input member of a differential of the rear axle and to a clutch arrangement for driving the front axle, wherein a transmission ratio difference is set up between the rear and the front axle such that, when the clutch arrangement is fully closed, the front axle is driven with a higher rotational speed than the rear axle, wherein said transmission ratio difference is set up to be permanent, and wherein left and right front wheels of the front axle are driven substantially independently of one another on demand so as to influence the yaw moment while cornering. ### Claim 17 (depends on 16) The drivetrain as claimed in claim 16, wherein the transmission ratio difference is in the range between 0.1 and 20%. ### Claim 18 (depends on 16) The drivetrain as claimed in claim 16, wherein the transmission ratio difference is in the range between 0.5 and 3%. ### Claim 19 (depends on 16) The drivetrain as claimed in claim 16, wherein the transmission ratio difference is selected such that the rotational speed of the front axle is higher than the rotational speed of the rear axle.