# US 11,305,748 B2 · System and method for activating a secondary axle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,305,748 B2 - Document ID: US11305748B2 - Status: Granted - Kind: B2 - Application number: 16/698,006 - Filed: 2019-11-27 - Published: 2021-05-27 - Granted: 2022-04-19 - Earliest claimed: 2019-11-27 - Assignees: Ford Global Technologies, LLC - Applicants: Ford Global Technologies, LLC - Inventors: Jose Velazquez Alcantar; Joseph Jay Torres; Matthew John Shelton - Web page: https://patentgrep.com/patent/US11305748B2 ## CPC - B60K 1/00: Arrangement or mounting of electrical propulsion units (B60K7/00 takes precedence; arrangement or mounting of plural diverse prime-movers for mutual or common propulsion B60K6/00) - 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) - B60K 1/02: comprising more than one electric motor - B60K 17/02: characterised by arrangement, location, or kind of clutch - B60K 17/165: {provided between independent half axles (B60K17/18, B60K17/20 take precedence)} - B60K 17/354: having separate mechanical assemblies for transmitting drive to the front or to the rear wheels or set of wheels - B60K 17/356: having fluid or electric motor, for driving one or more wheels - B60K 23/08: for changing number of driven wheels {, for switching from driving one axle to driving two or more axles (B60K17/3515 takes precedence)} - B60K 23/0808: {for varying torque distribution between driven axles, e.g. by transfer clutch} - B60W 10/02: including control of driveline clutches - B60W 10/08: including control of electric propulsion units, e.g. motors or generators - F16D 28/00: Electrically-actuated clutches (arrangements for synchronisation F16D23/02; clutches actuated directly by means of an electromagnet F16D27/00; automatic clutches F16D43/00 - F16D45/00; external control F16D48/00) - B60K 2023/0858: {with electric means, e.g. electro-hydraulic means} - F16D 27/118: with interengaging jaws or gear teeth - 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 - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES ## Abstract A vehicle includes a primary axle powered by an actuator and a secondary axle powered by a motor. The secondary axle includes a differential, first and second halfshafts, first and second wheels, a first electric clutch selectively coupling the first wheel to the first halfshaft, and a second electric clutch selectively coupling the second wheel to the second halfshaft. A vehicle controller is programmed to: responsive to a request to activate the secondary axle and a first speed difference between the first and second wheels being less than a first threshold, engage the first and second clutches at a same time, and, in response to the request to activate the secondary axle and the first speed difference between the first and second wheels exceeding the first threshold, engage one of the clutches and then subsequently engage the other of the clutches once the one of the clutches is fully engaged. ## Claims ### Claim 1 A vehicle comprising: a primary axle powered by an actuator; a secondary axle powered by a motor, the secondary axle including a differential, first and second halfshafts connected to the differential, first and second wheels, a first electric clutch selectively coupling the first wheel to the first halfshaft, and a second electric clutch selectively coupling the second wheel to the second halfshaft; and a controller electrically connected to the first and second clutches and programmed to: in response to (i) a request to activate the secondary axle, (ii) a first speed difference between the first and second wheels being less than a first threshold, and (iii) an average speed of the first and second halfshafts being within a second threshold of the speed difference between the first and second wheels, engage the first and second clutches at a same time, and in response to (i) the request to activate the secondary axle and (ii) the first speed difference between the first and second wheels exceeding the first threshold, engage one of the clutches and then subsequently engage the other of the clutches once the one of the clutches is fully engaged. ### Claim 2 (depends on 1) The vehicle of claim 1, wherein the one of the clutches is the first clutch when (i) the vehicle is accelerating and (ii) a speed of the first wheel is less than a speed of the second wheel. ### Claim 3 (depends on 2) The vehicle of claim 2, wherein the one of the clutches is the first clutch when (i) the vehicle is slowing down and (ii) the speed of the first wheel is greater than the speed of the second wheel. ### Claim 4 (depends on 1) The vehicle of claim 1, wherein the controller is further programmed to, in response to (i) the request to activate the secondary axle and (ii) the first speed difference being less than the first threshold, command the motor to speed control in which a second speed difference between an average speed of the halfshafts and an average speed of the wheels is reduced. ### Claim 5 (depends on 4) The vehicle of claim 4, wherein the controller is further programmed to, in response to (i) the request to activate the secondary axle and (ii) the first speed difference exceeding the first threshold, command the motor to the speed control in which the motor is controlled to reduce a third speed difference between the one of the wheels and the one of the halfshafts associated with the one of the clutches, and command the secondary motor to torque control until the one of the clutches is engaged in response to the third speed difference being less than a second threshold. ### Claim 6 (depends on 4) The vehicle of claim 4, wherein the controller is further programmed to, in response to (i) the request to activate the secondary axle and (ii) the first speed difference exceeding the threshold, command the motor to the speed control in which the motor is controlled to reduce a third speed difference between the one of the wheels and the one of the halfshafts associated with the one of the clutches, in response to the third speed difference being less than a second threshold, command the motor to torque control, in response to the one of the clutches being engaged, command the motor to the speed control in which the motor is controlled to reduce a fourth speed difference between the other of the wheels and the other of the halfshafts associated with the other of the clutches, and in response to the fourth speed difference being less than a third threshold, command the motor to torque control. ### Claim 7 (depends on 1) The vehicle of claim 1, wherein the differential includes a carrier driveably connected to the secondary motor, first and second side gears supported by the carrier and connected to the first and second halfshafts, respectively, and a torque-transfer mechanism acting between the first and second side gears and configured to synchronize rotation therebetween. ### Claim 8 (depends on 7) The vehicle of claim 7, wherein the torque-transfer mechanism is a spring having a first end connected to the first side gear and a second end connected to the second side gear. ### Claim 9 (depends on 7) The vehicle of claim 7, wherein the differential is an open differential. ### Claim 10 (depends on 1) The vehicle of claim 1, wherein the one of the clutches is the first clutch when (i) the vehicle is slowing down and (ii) the speed of the first wheel is greater than the speed of the second wheel. ### Claim 11 A vehicle comprising: a primary axle powered by a primary actuator; a secondary axle powered by a secondary actuator, the secondary axle including a differential, left and right halfshafts connected to the differential, left and right wheels, a left electric clutch selectively coupling the left wheel to the left halfshaft, and a right electric clutch selectively coupling the right wheel to the right halfshaft; and a controller programmed to, in response to a request to activate the secondary axle and a first speed difference between the left and right wheels exceeding a first threshold, engage the right clutch and subsequently engage the left clutch when the vehicle is accelerating and turning right, and engage the left clutch and subsequently engage the right clutch when the vehicle is accelerating and turning left. ### Claim 12 (depends on 11) The vehicle of claim 11, wherein the controller is further programmed to, in response to a request to activate the secondary axle and the first speed difference exceeding the first threshold: engage the left clutch and subsequently engage the right clutch when the vehicle is slowing down and turning right, and engage the right clutch and subsequently engage the left clutch when the vehicle is slowing down and turning left. ### Claim 13 (depends on 11) The vehicle of claim 11, wherein the controller is further programmed to, in response to the request to activate the secondary axle and the first speed difference between the left and right wheels being less than the first threshold, engage the left and right clutches at a same time when a difference between an average speed of the left and right wheels and an average speed of the left and right halfshafts is less than a second threshold. ### Claim 14 (depends on 11) The vehicle of claim 11, wherein the engage the right clutch further includes: command the secondary actuator to speed control in which the secondary actuator is controlled to reduce a second speed difference between the right wheel and the right halfshaft, and in response to the second speed difference being less than a second threshold, command the secondary actuator to torque control and engage the right clutch. ### Claim 15 (depends on 14) The vehicle of claim 14, wherein the subsequently engage the left clutch further includes: in response to the right clutch being engaged, command the secondary actuator to the speed control in which the secondary actuator is controlled to reduce a third speed difference between the left wheel and the left halfshaft, and in response to the third speed difference being less than a third threshold, command the secondary actuator to torque control and engage the left clutch. ### Claim 16 (depends on 11) The vehicle of claim 11, wherein the primary and secondary actuators are electric motors. ### Claim 17 (depends on 11) The vehicle of claim 11, wherein the differential includes a carrier driveably connected to the secondary actuator, left and right side gears supported by the carrier and connected to the left and right halfshafts, respectively, and a resilient member acting between the left and right side gears and configured to synchronize rotation therebetween. ### Claim 18 A vehicle comprising: a primary axle powered by a primary actuator; a secondary axle powered by a secondary actuator, the secondary axle including a differential, left and right halfshafts connected to the differential, left and right wheels, a left electric clutch selectively coupling the left wheel to the left halfshaft, and a right electric clutch selectively coupling the right wheel to the right halfshaft; and a controller programmed to, in response to (i) a request to activate the secondary axle, (ii) a first speed difference between the left and right wheels exceeding a first threshold, (iii) the vehicle accelerating, and (iv) the vehicle turning right, command the secondary actuator to speed control in which the secondary actuator is controlled to reduce a second speed difference between the right wheel and the right halfshaft, command the secondary actuator to torque control and engage the right clutch once the second speed difference is less than a second threshold, command, once the right clutch is engaged, the secondary actuator to speed control in which the secondary actuator is controlled to reduce a third speed difference between the left wheel and the left halfshaft, and command the secondary actuator to torque control and engage the left clutch once the third speed difference is less than a third threshold. ### Claim 19 (depends on 18) The vehicle of claim 18, wherein the controller is further programmed to, in response to (i) the request to activate the secondary axle, (ii) the first speed difference exceeding the first threshold, (iii) the vehicle accelerating, and (iv) the vehicle turning left, command the secondary actuator to speed control in which the secondary actuator is controlled to reduce the third speed difference between the left wheel and the left halfshaft, command the secondary actuator to torque control and engage the left clutch once the third speed difference is less than the third threshold, command, once the left clutch is engaged, the secondary actuator to speed control in which the secondary actuator is controlled to reduce the second speed difference between the right wheel and the right halfshaft, and command the secondary actuator to torque control and engage the right clutch once the second speed difference is less than the second threshold. ### Claim 20 (depends on 19) The vehicle of claim 19, wherein the controller is further programmed to, in response to (i) the request to activate the secondary axle and (ii) the first speed difference between the left and right wheels being less than the first threshold, engage the left and right clutches at a same time when a difference between an average speed of the left and right wheels and an average speed of the left and right halfshafts is less than a fourth threshold.