WO2017030918A1 - Cold weather shift strategy for a dual range disconnect system - Google Patents

Cold weather shift strategy for a dual range disconnect system Download PDF

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Publication number
WO2017030918A1
WO2017030918A1 PCT/US2016/046656 US2016046656W WO2017030918A1 WO 2017030918 A1 WO2017030918 A1 WO 2017030918A1 US 2016046656 W US2016046656 W US 2016046656W WO 2017030918 A1 WO2017030918 A1 WO 2017030918A1
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WO
WIPO (PCT)
Prior art keywords
drive axle
axle
axle system
tandem drive
clutching device
Prior art date
Application number
PCT/US2016/046656
Other languages
French (fr)
Inventor
Stephen A. EDELEN
Original Assignee
Dana Heavy Vehicle Systems Group, Llc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dana Heavy Vehicle Systems Group, Llc filed Critical Dana Heavy Vehicle Systems Group, Llc
Publication of WO2017030918A1 publication Critical patent/WO2017030918A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • 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
    • B60K17/00—Arrangement or mounting of transmissions in vehicles
    • B60K17/36—Arrangement or mounting of transmissions in vehicles for driving tandem wheels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • 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
    • B60K23/00—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for
    • B60K23/08—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for for changing number of driven wheels, for switching from driving one axle to driving two or more axles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • 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
    • B60K23/00—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for
    • B60K23/08—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for for changing number of driven wheels, for switching from driving one axle to driving two or more axles
    • B60K2023/085—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for for changing number of driven wheels, for switching from driving one axle to driving two or more axles automatically actuated
    • B60K2023/0858—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for for changing number of driven wheels, for switching from driving one axle to driving two or more axles automatically actuated with electric means, e.g. electro-hydraulic means

Definitions

  • the present invention relates to tandem drive axle systems and more specifically to control systems and shifting strategies for tandem drive axle systems.
  • Vehicles incorporating tandem drive axles benefit in many ways over vehicles having a single driven axle.
  • Inter-axle differentials in such vehicles may be configured to distribute torque proportionately or disproportionately between the axles.
  • shift mechanisms may be provided to such vehicles to permit the disengagement of one of the driven axles or to transition from single axle operation to tandem axle operation, among other benefits.
  • the present invention is directed to a control system for a tandem drive axle system.
  • the control system comprises a first actuator, a second actuator, and a controller.
  • the first actuator is in driving engagement with a first clutching device of the tandem drive ⁇ axle system.
  • the first clutching device is for shifting operating modes of the tandem drive axle system.
  • the second actuator is in driving engagement with a second clutching device.
  • the second clutching device is for disengaging an axle of the tandem drive axle system.
  • the controller is in communication with the first actuator and the second actuator.
  • the controller In response to at least one of a temperature the tandem drive axle system is operated in and a temperature of an axle of the tandem drive axle system, the controller adjusts a manner of shifting the drive axle system from a single axle mode of operation to a multi-axle mode of operation.
  • the present invention is directed to a method of shifting a tandem drive axle-system ⁇
  • the method comprises the steps of providing a tandem drive axle system including a first clutching device, a second clutching, device; providing a controller in communication- with the first actuator and the second actuator; detecting at least one of a temperature the tandem drive axle system is operated in and a temperature of an axle of the tandem drive axle system; and adjusting a manner of shifting the drive axle system from a single axle mode of operation to a multi-axle mode of operation; wherein the manner of shifting the drive axle system is adjusted based on at least one of a temperature the tandem drive axle system is operated in and a temperature of an axle of the tandem drive axle system
  • FIG. 1 is a schematic diagram of a drive axle system including a control system according to an embodiment of the invention
  • FIG. 2 is a chart that illustrates a synchronization process between components of the drive axle system shown in FIG. 1 that typically occurs when the drive axle system is operated in a low temperature environment and is shifted from a high speed and low torque single axle manner of operation to a low speed and high torque multi-axle manner of operation;
  • FIG. 3 is a chart that illustrates a synchronization process between components of the drive axle system shown in FIG. 1 that occurs when the drive axle system is operated in a low temperature environment and is shifted from a high speed and low torque single axle manner of operation to a low speed and high torque multi-axle manner of operation according to a method of the invention.
  • FIG. 1 illustrates a drive axle system 100 for a vehicle incorporating an inter-axle differential assembly 102.
  • the drive axle system 100 preferably includes the inter-axle differential assembly 102, a first axle assembly 104, and a second axle assembly 106.
  • the drive axle system 100 includes the three assemblies 102, 104, and 106, but it is understood the drive axle system 100 may include fewer or more assemblies or components.
  • the inter-axle differential assembly 102 includes an input shaft 108, a plurality of driving pinions 1 10, a transfer shaft 1 12, a second output gear 1 14, a first output gear 1 16, and a shift collar 1 17.
  • the components 108, 1 10, 1 12, 1 14, 1 16, 1 17 are formed from a hardened steel, however the components 108, 110, 1 12, 1 14, 1 16, 117 may be formed from any other rigid material.
  • the drive axle system 100 includes the six components 108, 1 10, 1 12, 1 14, 1 16, 1 17 disposed in a housing 1 18 but it is understood the inter-axle differential assembly 102 may include fewer or more components.
  • an actuator 120 adjusts a position of the shift collar 1 17.
  • the controller 1 19 is in communication with at least one sensor 121.
  • the input shaft 108 is at least partially disposed in the housing 118.
  • the input shaft 108 is an elongate member, however the input shaft 108 may be any other shape.
  • Bearings 122 disposed between the input shaft 108 and the housing 1 18 permit the input shaft 108 to rotate about an axis of the input shaft 108.
  • the input shaft 108 has a first end portion 123, a middle portion 124, and a second end portion 125, having a pinion carrier 126, a first set of clutch gear teeth 27, and an engagement portion 128 formed thereon.
  • the first end portion 123 of the input shaft 108 is in driving engagement with a vehicle transmission (not shown), which is in driving engagement with a power source (not shown), such as, but not limited to, an internal combustion engine.
  • the second end portion 125 is a substantially hoHow body having a diameter greater than a diameter of the. first end portion 123 and-the middle portion 124.
  • the second end portion 125 is drivingly coupled to-the input shaft 108, Alternately, the second end portion 125 may be integrally formed with the input shaft 108.
  • the pinion carrier 12 ⁇ is a substantially disc shaped body drivingly coupled to the second end portion 125 of the input shaft 108.
  • the pinion carrier 126 includes a plurality of pinion supports 129 protruding from a first side of the pinion carrier 126 into the second end portion 125 of the input shaft 108.
  • the engagement portion 128 is formed on a second side of the pinion carrier 126.
  • the pinion carrier 126 is also known as a planet carrier.
  • the engagement portion 128 is a conical surface oblique to the input shaft 108, however, the engagement portion 128 may have any other shape.
  • the first set of clutch gear teeth 127 are formed on the pinion carrier 126 radially inward from the engagement portion 128.
  • the plurality of driving pinions 1 10 are rotatably coupled to the pinion supports 130.
  • Each of the driving pinions 1 10 have gear teeth formed on an outer surface thereof.
  • each of the driving pinions 1 10 is also known as a planet gear.
  • bearings are disposed between each of the driving pinions 1 10 and the pinion supports 129, however, the driving pinions 1 10 may be directly mounted on the pinion supports.
  • the transfer snaft 1 12 is a hollow shaft rotatably disposed in the housing 1 18 and having an axis of rotation concurrent with the axis of rotation of the input shaft 08.
  • the transfer shaft 1 12 is a hollow elongate cylindrical member, however the transfer shaft 1 12 may be any other shape.
  • Bearings (not shown) disposed between the transfer shaft 1 12 and pinion carrier 126 permit the transfer shaft 1 12 to rotate about an axis of the transfer shaft 1 12.
  • the transfer shaft 1 12 has a first end portion 130, having a first set of clutch gear teeth 31 formed on an outer surface thereof, and a second end portion 132, having a second set of gear teeth 133 formed on an outer surface Ihereof.
  • the first end portion 130 and the second end portion 132 are integrally formed with the transfer shaft 1 12 and may have a diameter substantially equal to the transfer shaft 1 12. Alternately, the first end portion 130 and the second end portion 132 may be substantially disc shaped bodies having an outer diameter greater than a diameter of the transfer shaft 1 12. The first end portion 130 and the second end portion 132 may be drivingly coupled to the transfer shaft 1 12. Similarly, the first set of clutch gear teeth 131 and the second set of gear teeth 133 may be formed directly in the transfer shaft 1 12. As is known in the art, the second end portion 132 having the gear teeth 133 is known as a sun gear. The second set of gear teeth 133 are engaged with the plurality of driving pinions 1 10 and the first set of clutch gear teeth 131 are disposed adjacent the first set of clutch gear teeth 127 of the pinion carrier 126.
  • the second output gear 1 14 is a gear concentrically disposed about a portion of the transfer shaft 1 12.
  • the second output gear 1 14 has a central perforation having a diameter greater than a diameter of the transfer shaft 1 12.
  • the second output gear 114 is a substantially disc shaped body having a first end portion 134, a second end portion 135 defining an outer diameter of the second output gear 1 14, and an engagement portion 136.
  • Bearings 122 disposed between the second output gear 1 4 and the housing 118 permit the second output gear 114 to rotate about an axis of the second output gear 1 14.
  • the axis of the second output gear 1 14 is concurrent with the axis of the input shaft 108.
  • a first set of clutch gear teeth 137 are formed on the first end portion 134 adjacent the first set of clutch gear teeth 131 of the transfer shaft 112.
  • a second set of gear teeth 138 are formed on the second end portion 135.
  • the engagement portion 136 is formed in the second output gear 1 14 intermediate the first end portion 134 and the second end portion 135. As shown, the engagement portion 136 is a conical surface oblique to the input shaft 108; however, the engagement portion 136 may have any other shape.
  • the shift collar 117 is concentrically disposed about the transfer shaft 1 12.
  • the shift collar 117 includes a set of inner clutch collar teeth 139 formed on an inner surface thereof, a first synchronizer ring 140, and a second synchronizer ring 141.
  • the set of inner clutch collar teeth 139 are engaged with the first set of clutch gear teeth 131 of the transfer shaft 1 12.
  • the shift collar 1 17 can be slidably moved along the axis of the input shaft 108 as directed by the controller 1 19 while maintaining engagement of the inner clutch collar teeth 139 and the first set of clutch gear teeth 131.
  • a shift forl 142 disposed in an annular recess formed in the shift collar 1 17 moves the shift collar 117 along the axis of the input shaft 108 into a first position, a second position, or a neutral position.
  • the actuator 120 which is drivingly engaged with the shift fork 142, is engaged to position the shift fork 142 as directed by the controller 119. Consequently, the shift fork 142 positions the shift collar 1 17 into the first position, the second position, or the neutral position.
  • the shift collar 17 is drivingly engaged with the first set of clutch gear teeth 131 of the transfer shaft 1 12 and the first set of clutch gear teeth 127 of the pinion carrier 126.
  • the shift collar 1 17 In the second position, the shift collar 1 17 is drivingly engaged with the first set of clutch gear teeth 131 of the transfer shaft 1 12 and the first set of clutch gear teeth 137 of the second output gear 1 14. In the neutral position, the inner clutch collar teeth 139 of the shift collar 1 17 are only drivingly engaged with the first set of clutch gear teeth 131 of the transfer shaft 1 12. It is understood the shift collar 1 17, the clutch gear teeth 127, 131 , 137, 139, the synchronizer rings 140, 141 , and the engagement portions 128, 136 may be substituted with any clutching device that permits selective
  • the first synchronizer ring 140 is an annular body coupled to the shift collar 1 17 adjacent the engagement portion 128 of the pinion carrier 126.
  • the first synchronizer ring 140 has a first conical engagement surface 143.
  • the first synchronizer ring 140 may have an engagement surface having any other shape.
  • a biasing member (hot shown) is disposed between the shift collar 1 17 and the first synchronizer ring 140 to urge the first synchronizer ring 140 away from the shift collar 1 17.
  • the first conical engagement surface 143 contacts the engagement portion 128 of the pinion carrier 126.
  • the biasing member is compressed while the shift collar 7 engages the first set of clutch gear teeth 131 of the transfer shaft 1 12 and before the shift collar 1 17 engages the first set of clutch gear teeth 127 of the pinion carrier 126.
  • the second synchronizer ring 141 is an annular body coupled to the shift collar 1 17 adjacent the first end portion 134 of the second output gear 1 4.
  • the second synchronizer ring 141 has a second conical engagement surface 144.
  • the second synchronizer ring 141 may have an engagement surface naving any other shape.
  • a biasing member (not shown) is disposed between the shift collar 1 17 and the second synchronizer ring 141 to urge the second synchronizer ring 141 away from the shift collar 1 17.
  • the second conical engagement surface 144 contacts the engagement portion 136 of the second output gear 114.
  • the biasing member is compressed while the shift collar 117 engages the first set of clutch gear teeth 131 of the transfer shaft 112 and before the shift collar 117 engages the first set of clutch gear teeth 137 of the second output gear 114.
  • Thefirst output gear 116 is a gear concentrically disposed within the second end portion 125 of the input shaft 108.
  • the first output gear 116 is a substantially cup shaped body having an inner surface having gear teeth 145 formed on.
  • the first output gear 116 is known as a ring gear.
  • the gear teeth 145 are engaged with the gear teeth formed on the outer surface of each of the driving pinions 110.
  • the first output gear 116 includes an output shaft 146 drivingly coupled thereto. Alternately, the first output gear 116 may be integrally formed with the output shaft 146.
  • the output shaft 146 is collinear with the input shaft 108. Bearings 122 disposed between the output shaft 146 and the housing 118 support the output shaft 146 and permit the output shaft 146 to rotate about an axis of the output shaft 146.
  • the controller 119 is in communication with the power source, the actuator 120, and the at least one sensor 121.
  • the controller 119 is in electrical communication with the power source, the actuator 120, and the at least one sensor 121.
  • the controller 119 may be in communication with the power source, the actuator 120, and the at least one sensor 121 using pneumatics, hydraulics, or a wireless communication medium.
  • the controller 119, in co-operation with the first actuator 120 and the at least one sensor 121 form a control system for the drive axle system 100.
  • the controller 119 implements a method of shifting the drive-axle system 100 that facilitates quick shifting between the 6x2 mode of operation and the 6x4 mode of operation in low temperature environments
  • the controller 119 is configured to accept an input containing
  • the controller 19 uses the input to adjust the at least one of the operating condition of the power source, the position of the shift collar 117, the position of the clutch associated with the second axle assembly 106, and a duration between successive positions of the shift collar 117.
  • the controller 119 performs the adjustment to the operating condition of the power source, the position of the shift collar 117, the position of the clutch associated with the second axle assembly 106 (described
  • the controller 119 references at least one of a series of instructions and conditions, an operator input, at least one data table, and at least one algorithm to determine the adjustment made to the operating condition of the power source, the position of the shift collar 117, the position of the clutch associated with the second axle assembly 106, and a duration between successive positions of the shift collar 117.
  • the actuator 120 is a linear actuator that upon actuation in response to a signal sent by the controller 119, adjusts a position of the shift collar 117 to change an operating mode of the drive axle system 100.
  • the actuator 120 is a double-acting pneumatic cylinder in fluid communication with a pair of solenoid valves (not shown), but it is understood that the actuator 120 may be an electromechanical actuator ora-hydraulic actuator.
  • the at least one sensor 121 may be disposed within the housing 118, the first axle housing 151 , and the second axle housing 158. Further, it is understood that thecal least one sensor 121 may be disposed on an outer surface of one of the housings 118, 151 , 158 or mounted elsewhere on the vehicle.
  • the at least one sensor 121 is configured as known in the art to monitor at least one of the operating condition of the power source, the temperature of the seGond axle assembly 106, the temperature of a lubricant used with the second axle assembly 106, the speed of a portion of the transfer shaft 1 12 the speed of the second output gear 1 14 the speed of a portion of the second axle assembly 106, the amount of torque transferred to the input shaft 08, the position of the shift collar 1 17, and the position of the clutch associated with the second axle assembly 106.
  • the operating condition of the power source may be at least one of an indication that the power source is operating, a rotational speed of the power source, a state of the vehicle transmission, and a speed of the vehicle. Further, it is understood that the at least one sensor 121 may be configured to indicate an engagement of the actuator 120.
  • the first axle assembly 104 includes a bevel gear pinion 147, a first driving gear 148, a first wheel differential 149, and a first pair of output axles 150.
  • the components 147, 148, 149, 150 are formed from a hardened steel, however the components 147, 148, 149, 150 may be formed from any other rigid material.
  • the first axle assembly 104 includes the four components 147, 148, 149, 150 disposed in a first axle housing 151 but it is understood t e first axle assembly 104 may include fewer or more components.
  • the first driving gear 148 is coupled to a housing of the first wheel differential 49 by a plurality of fasteners or a weld and is rotatable about an axis of the first pair of output axles 150 within the first axle housing 151.
  • the first driving gear 148 may be integrally formed with the first wheel differential 149.
  • the first driving gear 148 has gear teeth formed on an outer surface thereof.
  • the first driving gear 148 may be one of a hypoid gear, a spiral bevel gear, a straight bevel gear, or any other gear known to those ski lied in the art.
  • the first driving gear 148 is drivingly engaged -with the bevel gear pinion 147- and has a first gear ratio.
  • the first gear ratio may be a 2.42: 1 ratio, but it is understood that other ratios may be used.
  • the output shaft 146 is drivingly engaged with the first driving gear 148 of the first axle assembly 104 through a single gear mesh.
  • the first wheel differential 149 is a bevel gear style differential as is known in the art having a plurality of driving pinions and a pair of side gears drivingly engaged with the first pair of output axles 150.
  • the first wheel differential 149 is rotatably disposed within the first axle housing 151 about the axis of the first pair of output axles 150. Alternately, other styles of differentials may be used in place of the first wheel differential 149.
  • the first pair of output axles 150 are elongate cylindrical members having a common axis rotatably mounted within the first axle housing 151. Bearings 122 disposed between the first pair of output axles 150 and the first axle housing 151 permit the first pair of output axles 150 to rotate therein.
  • the side gears of the first wheel differential 149 are disposed on first ends of each of the first output axles 150 and wheels (not shown) are disposed on second ends of each of the first output axles 150.
  • the second axle assembly 106 includes an inter-axle shaft 152, a second driving gear 153, a second wheel differential 154, a pair of second output axles 156, and an-axle clutch 157.
  • the components 152, 153, 154, 1J56, 157 are formed from a hardened steel, however the components 152, 153, 154, 156, 157 may be formed from any other rigid material.
  • the second axle assembly 106 includes the five components 152, 153, 154, 156, 157 disposed in a second axle housing 158 but it is understood the second axle assembly 106 may include fewer or more components.
  • the inter-axle shaft 152 comprises at least one elongate cylindrical member drivingly engaged with the second output gear 1 4 through a driven gear 159 coupled to the inter-axle shaft 152.
  • the inter-axle shaft 152 comprises a plurality of elongate cylindrical members connected by joints. Bearings 122 disposed between the inter-axle shaft 152 and the housing 18 permit the inter-axle shaft 152 to rotate therein.
  • a bevel gear pinion 160 is drivingly coupled to the inter-axle shaft 152 opposite the driven gear 159.
  • the bevel gear pinion 159 has gear teeth formed on an outer surface thereof.
  • the bevel gear pinion 160 may be one of a hypoid gear, a spiral bevel gear, a straight bevel gear, or any other gear known to those skilled in the art.
  • the second driving gear 153 is a ring style bevel gear as is known in the art having a set of gear teeth engaged with the gear teeth formed on the bevel gear pinion 160.
  • the second driving gear 53 is coupled to a housing of the second wheel differential 154 by a plurality of fasteners or a weld and is rotatable about an axis of the pair of second output axles 156 within the second axle housing 158.
  • the second driving gear 153 may be integrally formed with the second wheel differential 154.
  • the second driving gear 153 is drivingly engaged with the bevel gear pinion 160 and has a second gear ratio.
  • the second gear ratio may be a 3.55: 1 ratio, but it is understood that other ratios may be used.
  • the second gear ratio is a lower gear ratio than the first gear ratio.
  • the second wheel differential 154 is a bevel gear style differential as is known in the art having a plurality of driving pinions and a pair of side gears drivingly engaged with the pair of second output-axles 156.
  • the second wheel differential 154 is rotatably disposed within the second axle housing 158 about the axis of the pair of second output axies 156.
  • other styles of differentials may be used in place of the second wheel differential 154.
  • the pair of second output axles 156 are elongate cylindrical members having a common axis rotatably mounted within the second axle housing 158. Bearings 122 disposed between the pair of second output axles 156 and the second axle housing 153 permit the first pair of second output axles 56 to rotate therein.
  • the side gears of the second wheel differential 154 are disposed on first ends of each of the second output axies 156 and wheels (not shown) are disposed on second ends of each of the second output axles 156.
  • the axle clutch 157 is a dog style clutch-that divides one of the second output axles 156 into first and second portions.
  • the axle clutch 157 may be a component of the second wheel differential 154 whic engages a side gear of the second wheel differential 154 and one of the second output axles 156.
  • the axle clutch 157 may also be a plate style clutch or any other style clutch.
  • a shift collar 162 slidingly disposed on a first component of the axle clutch 157 selectively engages a plurality of teeth formed thereon with corresponding teeth formed on a first component and a second component of the axle clutch 157.
  • the shift collar 162 is urged into an engaged position or a disengaged position by a shift fork 164 and a disconnect actuator 166.
  • the disconnect actuator 166 is a linear actuator that upon actuation in response to a signal sent by the controller 119, adjusts a position of the shift collar 162 to drivingly engage the first portion of one of the second output axles 156 with the second portion of one of the second output axles 156.
  • the disconnect actuator 166 is a double acting pneumatic cylinder in fluid communication with a pair of solenoid valves (not shown), but it is understood that the disconnect actuator 166 may be an electromechanical actuator or a hydraulic actuator.
  • the drive axle system 100 facilitates a low speed and high torque multi- axle manner of operation and a high speed and low torque single axle manner of operation.
  • the manner of operation of the drive axle system 100 is determined by a position of the shift collar 117.
  • the drive axle system 100 balances a rotational difference between the first output gear 116 and the second output gear 114 caused by a difference between the first gear ratio and the second gear ratio with the inter-axle differential assembly 102, wherein the balancing of the rotational difference between the first output gear 116 and the second output gear 114 provides a cumulative gear ratio for the first axle assembly 104 and the second axle assembly 106.
  • the cumulative gear ratio is intermediate the first gear ratio and the second gear ratio.
  • the controller 1 9 shifts the drive axle system 100 into the first position.
  • circumstances in which the controller 119 may recognize as being advantageous for the high speed and low torque single axle manner of operation are operation of the vehicle not burdened by a load and operation of the vehicle at highway speeds.
  • the controller 119 moves the shift collar 117 into the first position.
  • the controller 119 operates in an automated manner based on a series of instructions or conditions the controller 1 19 is programmed with. Further, the vehicle the drive axle system 100 is incorporated in may be configured to automatically recognize conditions suitable for the high speed and low torque single-axle manner of operation and automatically move the shift collar 117 into the first position using the actuator 120.
  • the first conical engagement surface 143 of the first synchronizer ring 140 contacts the engagement portion 128 of the pinion carrier 126. Contact of the first conical engagement surface 143 with the engagement portion 128 causes the shift collar 1 17 ( and thus the transfer shaft 112) to accelerate to approximately the same speed of the input shaft 108 and the biasing member disposed between the shift collar 17 and the first
  • the second output gear 114 sits idle as the shift collar 117 is not engaged with the first set of clutch gear teeth 137. Further, the axle clutch 57 is disengaged, allowing the plurality of driving pinions and the pair of side gears of the second wheel differential 154 to spin freely without need for the inter-axle shaft 152 to spin. In this manner, torque delivered through the input shaft 108 is transferred only to the first output axles 150 while reducing parasitic windage losses that may be caused by needless rotation of the inter- axle shaft 152 and the second output gear 114.
  • the controller 119 shifts the drive axle system 100 into the second position.
  • circumstances in which the controller 1 19 may recognize as being advantageous for the low speed and high torque multi-axle manner of operation are starting movement of the vehicle from a stopped position, operation of the vehicle along a surface having a positive gradient, operation of the vehicle in a loaded condition, and operation of the vehicle along a surface having a reduced coefficient of friction.
  • the shift collar 117 is moved into the second position, the shift collar 1 17 is drivingly engaged with the first set of clutch gear teeth 131 of the transfer shaft 112 and the first set of clutch gear teeth 137 of the second output gear 1 14.
  • the controller 119 moves the shift collar 117 into the second position.
  • the controller 1 19 operates a switching mechanism that causes the actuator 20 to electronically or pneumatically move the shift fork 142 and the associated shift collar 1 17 into the second position.
  • thB actuator 120 may engage a linkage component directly coupled to the shift fork 142 to move theshiftcollar 117 into the second position.
  • the axle clutch 157 is engaged to not allow each of the second output axles 156 to rotate with respect to one another without rotation of the inter-axle shaft 152.
  • the vehicle the drive axle system 100 is incorporated in may be configured to automatically recognize conditions suitable for the low speed and high torque multi-axle manner of operation and automatically move the shift collar 1 17 into the second position using the controller 1 9.
  • the second conical engagement surface 144 of the second synchronizer ring 141 contacts the engagement portion 136 of the second end portion 135 of the second output gear 1 14.
  • Contact of the second conical engagement surface 144 with the engagement portion 144 causes the second output gear 1 14 and the inter-axle shaft 152 to accelerate to- approximately the same speed of the second output gear 1 14 and the biasing member disposed between the shift collar 1 17 and the second synchronizer ring 141 to compress.
  • FIG. 2 is a chart that illustrates a synchronization process between the shift collar 1 17 and the second output gear 1 14 that typically occur when the second axle assembly 106 is operated in a low temperature environment and is shifted from the high speed and low torque single axle manner of operation to the low speed and high torque multi-axle manner of operation.
  • a lubricant used within the second axle assembly 106 will greatly increase in viscosity when the second axle assembly 106 is operated in a low temperature environment, significantly increasing a duration of the synchronization process between the shift collar 117 and the second output gear 114 when shifting occurs.
  • a speed of the power source is increased by about 250 revolutions per minute over a time period of about 300 ms.
  • a speed of the shift collar 1 17 increases to about 1800 revolutions per minute.
  • Point A on FIG. 2 indicates when the synchronization process is completed. As shown in FIG. 2, the synchronization process takes about 1800 ms to occur. Further, as shown in FIG. 2, the synchronization process consumes energy until the
  • axle clutch 157 can be engaged to complete the shift of the drive axle system 100 to the low speed and high torque single axle manner of operation.
  • the controller 119 implements a method of shifting the drive axle system 100 that facilitates quick shifting from the high speed and low torque single axle manner of operation to the low speed and high torque multi-axle manner of operation when the controller 119 detects the drive axle system 100 is being operated in a low temperature environment.
  • the controller 119 determines whether to implement the quick shifting method when shifting the drive axle system 100 from the high speed and low torque single axle manner of operation to the low speed and high torque multi-axle manner of operation. If the temperature of the second axle assembly 106 or the temperature of a lubricant used with the second axle assembly 106 is below a threshold value, the controller 1 9 will implement the quick shifting method when a shift request is received.
  • a temperature of an ambient environment the vehicle is operated in which may be available to the controller 1 19 through a vehicle communication bus (not shown), may also be used to determine if the quick shifting method is employed when a shift request is received.
  • the shift request may be initiated by an operator of the vehicle, a vehicle controller in communication with the controller 1 19, or by the controller 1 19.
  • FIG. 3 is a cfiart that illustrates a synchronization process between the shift collar 1 17 and the second output gear 1 4 that occurs when the second axle assembly 106 is operated in a low temperature environment and is shifted from the high speed and low torque single axle manner of operation to the low speed and high torque multi-axle manner of operation in accord with the method that facilitates quick shifting.
  • the controller 1 19 delays acceleration of the power source until synchronization of the shift collar 1 17 and the second output gear 1 14 occurs.
  • the controller 1 19 (or a controller in communication with the controller 1 19) maintains a speed of the power source in a substantially constant manner while the second output gear 1 14, the driven gear 159, the inter-axle shaft 152, the bevel gear pinion 160, the second driving gear 153, and portions of the second wheel differential 154 are accelerated by the synchronization between the shift collar 1 17 and the second output gear 1 14.
  • the controller 1 19 or a controller in communication with the controller 1 19 maintains a speed of the power source in a substantially constant manner while the second output gear 1 14, the driven gear 159, the inter-axle shaft 152, the bevel gear pinion 160, the second driving gear 153, and portions of the second wheel differential 154 are accelerated by the synchronization between the shift collar 1 17 and the second output gear 1 14.
  • the controller 1 19 maintains a speed of the power source in a substantially constant manner while the
  • synchronization process takes about 700 ms.
  • the shift collar 1 17 is drivingly engaged with the first set of clutch gear teeth 137 of the second output gear 1 14, and the synchronization process stops consuming energy.
  • Point A indicates when the synchronization process is completed.
  • a speed of the power source is increased by about 250 revolutions per minute over a time period of about 400 ms.
  • the above mentioned values are exemplary in nature and that the principles of the method that facilitates quick shifting may be adapted for use for other devices that require quick shifting.
  • the quick shifting method for the drive axle system 100 may be implemented by the controller 19 (or a controller in communication with the controller 1 19) at all times to simplify an operation of the drive axle system 100.
  • a hybrid shifting procedure is within the scope of the invention.
  • a speed of the power source is increased by a smaller amount of revolutions per minute over a time period of less than about 300 ms, compared to the synchronization process illustrated in FIG. 2.
  • a speed of the shift collar 117 increases.
  • the controller 119 (or a controller in communication with the controller 119) then maintains a speed of the power source in a substantially constant manner while the second output gear 114, the driven gear 159, the inter-axle shaft 152, the bevel gear pinion 160, the second driving gear 53, and portions of the second wheel differential 154 are accelerated by the synchronization between the shift collar 117 and the second output gear 114.
  • a speed of the power source is increased again to a desired level of revolutions per minute.
  • Such an increase in rotational speed results in the second output gear 114 being driven up to about 1800 revolutions per minute, which allows the driven gear 159, the inter-axle shaft 152, the bevel gear pinion 160, the second driving gear 153, and portions of the second wheel differential 154 to rotate at a speed which allows the axle clutch 157 to be engaged, completing the shift of the drive axle system 100.
  • a time required to shift the drive axle system from the high speed and low torque single axle manner of operation to the low speed and high torque multi- axle manner of operatbn in a low-temperature environment can be reduced by- about 42%. Further, the quick shifting method for the drive axle system 1 ⁇ decreases an amount of energy consumed by the synchronization process by about 20%.

Abstract

A control system and method of shifting a tandem drive axle system is provided. The control system comprises a first actuator, a second actuator, and a controller. The first actuator is in driving engagement with a first clutching device of the tandem drive axle system to shift operating modes of the tandem drive axle system. The second actuator is in driving engagement with a second clutching device for disengaging an axle of the tandem drive axle system. The controller is in communication with the actuators. In response to at least one of a temperature the tandem drive axle system is operated in and a temperature of an axle of the tandem drive axle system, the controller adjusts a manner of shifting the drive axle system from a single axle mode of operation to a multi-axle mode of operation.

Description

TITLE
COLD WEATHER SHIFT STRATEGY FOR A DUAL RANGE DISCONNECT SYSTEM
CLAIM OF PRIORITY
The present application claims the benefit of priority to U.S. Provisional Application No. 62/205,203 filed on August 14, 2015, which is incorporated herein in its entirety by reference.
FIELD OF THE INVENTION
The present invention relates to tandem drive axle systems and more specifically to control systems and shifting strategies for tandem drive axle systems.
BACKGROUND OF THE INVENTION
Vehicles incorporating tandem drive axles benefit in many ways over vehicles having a single driven axle. Inter-axle differentials in such vehicles may be configured to distribute torque proportionately or disproportionately between the axles. Additionally, shift mechanisms may be provided to such vehicles to permit the disengagement of one of the driven axles or to transition from single axle operation to tandem axle operation, among other benefits.
Operation of shifting mechanisms that permit the disengagement of one of the driven axles may be affected by temperature variations. When a portion of a tandem drive axle is disengaged, the disengaged portion quickly adjusts to a temperature of an environment the tandem drive axle is operated in. In low temperature-environments, lubricants used with the disengaged portion will greatly increase in viscosity. At higher operating speeds, when one of the driven axles is typically disengaged to increase driveline efficiency, such a condition can rapidly occur. The condition is a result of the higher operating speeds, which results in increased airflow around the tandem drive axle. In such a situation, the disengaged portion must be carefully "spooled" up to allow for reengagement of the shifting mechanism without causing damage thereto. Such a process may delay a down shift of the tandem drive axle to a point where the disengagement of a portion of a tandem drive axle has become counterproductive.
It would be advantageous to develop a control system and method of shifting a tandem drive axle system that facilitates quick shifting between operating modes in low temperature environments.
SUMMARY OF THE INVENTION
Presently provided by the invention, a control system and method of shifting a tandem drive axle system that facilitates quick shifting between operating modes in low temperature environments, has surprisingly been discovered.
In a first embodiment, the present invention is directed to a control system for a tandem drive axle system. The control system comprises a first actuator, a second actuator, and a controller. The first actuator is in driving engagement with a first clutching device of the tandem drive^axle system. The first clutching device is for shifting operating modes of the tandem drive axle system. The second actuator is in driving engagement with a second clutching device. The second clutching device is for disengaging an axle of the tandem drive axle system. The controller is in communication with the first actuator and the second actuator. In response to at least one of a temperature the tandem drive axle system is operated in and a temperature of an axle of the tandem drive axle system, the controller adjusts a manner of shifting the drive axle system from a single axle mode of operation to a multi-axle mode of operation.
In another embodiment, the present invention is directed to a method of shifting a tandem drive axle-system^ The method comprises the steps of providing a tandem drive axle system including a first clutching device, a second clutching, device; providing a controller in communication- with the first actuator and the second actuator; detecting at least one of a temperature the tandem drive axle system is operated in and a temperature of an axle of the tandem drive axle system; and adjusting a manner of shifting the drive axle system from a single axle mode of operation to a multi-axle mode of operation; wherein the manner of shifting the drive axle system is adjusted based on at least one of a temperature the tandem drive axle system is operated in and a temperature of an axle of the tandem drive axle system
Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a drive axle system including a control system according to an embodiment of the invention;
FIG. 2 is a chart that illustrates a synchronization process between components of the drive axle system shown in FIG. 1 that typically occurs when the drive axle system is operated in a low temperature environment and is shifted from a high speed and low torque single axle manner of operation to a low speed and high torque multi-axle manner of operation; and
FIG. 3 is a chart that illustrates a synchronization process between components of the drive axle system shown in FIG. 1 that occurs when the drive axle system is operated in a low temperature environment and is shifted from a high speed and low torque single axle manner of operation to a low speed and high torque multi-axle manner of operation according to a method of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
it is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is-also to be understood thatlhe specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts of the present invention. Hence, specific dimensions, directions, orientations or other physical characteristics relating to the embodiments disclosed are not to be considered as limiting, unless expressly stated otherwise.
FIG. 1 illustrates a drive axle system 100 for a vehicle incorporating an inter-axle differential assembly 102. The drive axle system 100 preferably includes the inter-axle differential assembly 102, a first axle assembly 104, and a second axle assembly 106. As shown, the drive axle system 100 includes the three assemblies 102, 104, and 106, but it is understood the drive axle system 100 may include fewer or more assemblies or components.
The inter-axle differential assembly 102 includes an input shaft 108, a plurality of driving pinions 1 10, a transfer shaft 1 12, a second output gear 1 14, a first output gear 1 16, and a shift collar 1 17. Preferably, the components 108, 1 10, 1 12, 1 14, 1 16, 1 17 are formed from a hardened steel, however the components 108, 110, 1 12, 1 14, 1 16, 117 may be formed from any other rigid material. As shown, the drive axle system 100 includes the six components 108, 1 10, 1 12, 1 14, 1 16, 1 17 disposed in a housing 1 18 but it is understood the inter-axle differential assembly 102 may include fewer or more components. In response to a signal sent by a controller 1 19, an actuator 120 adjusts a position of the shift collar 1 17. The controller 1 19 is in communication with at least one sensor 121.
The input shaft 108 is at least partially disposed in the housing 118.
Preferably, the input shaft 108 is an elongate member, however the input shaft 108 may be any other shape. Bearings 122 disposed between the input shaft 108 and the housing 1 18 permit the input shaft 108 to rotate about an axis of the input shaft 108. The input shaft 108 has a first end portion 123, a middle portion 124, and a second end portion 125, having a pinion carrier 126, a first set of clutch gear teeth 27, and an engagement portion 128 formed thereon. The first end portion 123 of the input shaft 108 is in driving engagement with a vehicle transmission (not shown), which is in driving engagement with a power source (not shown), such as, but not limited to, an internal combustion engine.
The second end portion 125 is a substantially hoHow body having a diameter greater than a diameter of the. first end portion 123 and-the middle portion 124. The second end portion 125 is drivingly coupled to-the input shaft 108, Alternately, the second end portion 125 may be integrally formed with the input shaft 108.
The pinion carrier 12ϋ is a substantially disc shaped body drivingly coupled to the second end portion 125 of the input shaft 108. The pinion carrier 126 includes a plurality of pinion supports 129 protruding from a first side of the pinion carrier 126 into the second end portion 125 of the input shaft 108. The engagement portion 128 is formed on a second side of the pinion carrier 126. As is known in the art, the pinion carrier 126 is also known as a planet carrier.
The engagement portion 128 is a conical surface oblique to the input shaft 108, however, the engagement portion 128 may have any other shape. The first set of clutch gear teeth 127 are formed on the pinion carrier 126 radially inward from the engagement portion 128.
The plurality of driving pinions 1 10 are rotatably coupled to the pinion supports 130. Each of the driving pinions 1 10 have gear teeth formed on an outer surface thereof. As is known in the art, each of the driving pinions 1 10 is also known as a planet gear. Preferably, bearings are disposed between each of the driving pinions 1 10 and the pinion supports 129, however, the driving pinions 1 10 may be directly mounted on the pinion supports.
The transfer snaft 1 12 is a hollow shaft rotatably disposed in the housing 1 18 and having an axis of rotation concurrent with the axis of rotation of the input shaft 08. Preferably, the transfer shaft 1 12 is a hollow elongate cylindrical member, however the transfer shaft 1 12 may be any other shape. Bearings (not shown) disposed between the transfer shaft 1 12 and pinion carrier 126 permit the transfer shaft 1 12 to rotate about an axis of the transfer shaft 1 12. The transfer shaft 1 12 has a first end portion 130, having a first set of clutch gear teeth 31 formed on an outer surface thereof, and a second end portion 132, having a second set of gear teeth 133 formed on an outer surface Ihereof.
The first end portion 130 and the second end portion 132 are integrally formed with the transfer shaft 1 12 and may have a diameter substantially equal to the transfer shaft 1 12. Alternately, the first end portion 130 and the second end portion 132 may be substantially disc shaped bodies having an outer diameter greater than a diameter of the transfer shaft 1 12. The first end portion 130 and the second end portion 132 may be drivingly coupled to the transfer shaft 1 12. Similarly, the first set of clutch gear teeth 131 and the second set of gear teeth 133 may be formed directly in the transfer shaft 1 12. As is known in the art, the second end portion 132 having the gear teeth 133 is known as a sun gear. The second set of gear teeth 133 are engaged with the plurality of driving pinions 1 10 and the first set of clutch gear teeth 131 are disposed adjacent the first set of clutch gear teeth 127 of the pinion carrier 126.
The second output gear 1 14 is a gear concentrically disposed about a portion of the transfer shaft 1 12. The second output gear 1 14 has a central perforation having a diameter greater than a diameter of the transfer shaft 1 12. The second output gear 114 is a substantially disc shaped body having a first end portion 134, a second end portion 135 defining an outer diameter of the second output gear 1 14, and an engagement portion 136. Bearings 122 disposed between the second output gear 1 4 and the housing 118 permit the second output gear 114 to rotate about an axis of the second output gear 1 14. The axis of the second output gear 1 14 is concurrent with the axis of the input shaft 108. A first set of clutch gear teeth 137 are formed on the first end portion 134 adjacent the first set of clutch gear teeth 131 of the transfer shaft 112. A second set of gear teeth 138 are formed on the second end portion 135.
The engagement portion 136 is formed in the second output gear 1 14 intermediate the first end portion 134 and the second end portion 135. As shown, the engagement portion 136 is a conical surface oblique to the input shaft 108; however, the engagement portion 136 may have any other shape.
The shift collar 117 is concentrically disposed about the transfer shaft 1 12. The shift collar 117 includes a set of inner clutch collar teeth 139 formed on an inner surface thereof, a first synchronizer ring 140, and a second synchronizer ring 141. The set of inner clutch collar teeth 139 are engaged with the first set of clutch gear teeth 131 of the transfer shaft 1 12. The shift collar 1 17 can be slidably moved along the axis of the input shaft 108 as directed by the controller 1 19 while maintaining engagement of the inner clutch collar teeth 139 and the first set of clutch gear teeth 131. A shift forl 142 disposed in an annular recess formed in the shift collar 1 17 moves the shift collar 117 along the axis of the input shaft 108 into a first position, a second position, or a neutral position. The actuator 120, which is drivingly engaged with the shift fork 142, is engaged to position the shift fork 142 as directed by the controller 119. Consequently, the shift fork 142 positions the shift collar 1 17 into the first position, the second position, or the neutral position. In the first position, the shift collar 17 is drivingly engaged with the first set of clutch gear teeth 131 of the transfer shaft 1 12 and the first set of clutch gear teeth 127 of the pinion carrier 126. In the second position, the shift collar 1 17 is drivingly engaged with the first set of clutch gear teeth 131 of the transfer shaft 1 12 and the first set of clutch gear teeth 137 of the second output gear 1 14. In the neutral position, the inner clutch collar teeth 139 of the shift collar 1 17 are only drivingly engaged with the first set of clutch gear teeth 131 of the transfer shaft 1 12. It is understood the shift collar 1 17, the clutch gear teeth 127, 131 , 137, 139, the synchronizer rings 140, 141 , and the engagement portions 128, 136 may be substituted with any clutching device that permits selective
engagement of a driving and a driven part.
The first synchronizer ring 140 is an annular body coupled to the shift collar 1 17 adjacent the engagement portion 128 of the pinion carrier 126. The first synchronizer ring 140 has a first conical engagement surface 143.
Alternately, the first synchronizer ring 140 may have an engagement surface having any other shape. A biasing member (hot shown) is disposed between the shift collar 1 17 and the first synchronizer ring 140 to urge the first synchronizer ring 140 away from the shift collar 1 17. When the shift collar 1 17 is moved from the second position into the first position, the first conical engagement surface 143 contacts the engagement portion 128 of the pinion carrier 126. As the shift collar 1 17 moves towards the first set of clutch gear teeth 127 of the input shaft 108, the biasing member is compressed while the shift collar 7 engages the first set of clutch gear teeth 131 of the transfer shaft 1 12 and before the shift collar 1 17 engages the first set of clutch gear teeth 127 of the pinion carrier 126.
The second synchronizer ring 141 is an annular body coupled to the shift collar 1 17 adjacent the first end portion 134 of the second output gear 1 4. The second synchronizer ring 141 has a second conical engagement surface 144. Alternately, the second synchronizer ring 141 may have an engagement surface naving any other shape. A biasing member (not shown) is disposed between the shift collar 1 17 and the second synchronizer ring 141 to urge the second synchronizer ring 141 away from the shift collar 1 17. When the shift collar 117 is moved from the first position into the second position, the second conical engagement surface 144 contacts the engagement portion 136 of the second output gear 114. As the shift collar 117 moves towards the first set of clutch gear teeth 137 of the second output gear 114, the biasing member is compressed while the shift collar 117 engages the first set of clutch gear teeth 131 of the transfer shaft 112 and before the shift collar 117 engages the first set of clutch gear teeth 137 of the second output gear 114.
Thefirst output gear 116 is a gear concentrically disposed within the second end portion 125 of the input shaft 108. The first output gear 116 is a substantially cup shaped body having an inner surface having gear teeth 145 formed on. As is known in the art, the first output gear 116 is known as a ring gear. The gear teeth 145 are engaged with the gear teeth formed on the outer surface of each of the driving pinions 110.
The first output gear 116 includes an output shaft 146 drivingly coupled thereto. Alternately, the first output gear 116 may be integrally formed with the output shaft 146. The output shaft 146 is collinear with the input shaft 108. Bearings 122 disposed between the output shaft 146 and the housing 118 support the output shaft 146 and permit the output shaft 146 to rotate about an axis of the output shaft 146.
The controller 119 is in communication with the power source, the actuator 120, and the at least one sensor 121. Preferably, the controller 119 is in electrical communication with the power source, the actuator 120, and the at least one sensor 121. Alternately, the controller 119 may be in communication with the power source, the actuator 120, and the at least one sensor 121 using pneumatics, hydraulics, or a wireless communication medium. The controller 119, in co-operation with the first actuator 120 and the at least one sensor 121 form a control system for the drive axle system 100. The controller 119 implements a method of shifting the drive-axle system 100 that facilitates quick shifting between the 6x2 mode of operation and the 6x4 mode of operation in low temperature environments
The controller 119 is configured to accept an input containing
information regarding at least one of an operating condition of the power source, a temperature of the second axle assembly 106, a speed of a portion of the transfer shaft 112, a speed of the second output gear 114, a speed of a portion of the second axle assembly 106, an amount of torque transferred to the input shaft 108, a position of the shift collar 117, and a position of a clutch associated with the second axle assembly 106. The controller 19 uses the input to adjust the at least one of the operating condition of the power source, the position of the shift collar 117, the position of the clutch associated with the second axle assembly 106, and a duration between successive positions of the shift collar 117. The controller 119 performs the adjustment to the operating condition of the power source, the position of the shift collar 117, the position of the clutch associated with the second axle assembly 106 (described
hereinbelow), and a duration between successive positions of the shift collar 1 7 based on at least one of the operating condition of the power source, the temperature of the second axle assembly 106, the speed of a portion of the transfer shaft 112, the speed of the second output gear 114, the speed of a portion of the second axle assembly 106, the amount of torque transferred to the input shaft 108, the position of the shift collar 117, and the position of the clutch associated with the second axle assembly 106. The controller 119 references at least one of a series of instructions and conditions, an operator input, at least one data table, and at least one algorithm to determine the adjustment made to the operating condition of the power source, the position of the shift collar 117, the position of the clutch associated with the second axle assembly 106, and a duration between successive positions of the shift collar 117.
The actuator 120 is a linear actuator that upon actuation in response to a signal sent by the controller 119, adjusts a position of the shift collar 117 to change an operating mode of the drive axle system 100. Preferably, the actuator 120 is a double-acting pneumatic cylinder in fluid communication with a pair of solenoid valves (not shown), but it is understood that the actuator 120 may be an electromechanical actuator ora-hydraulic actuator.
The at least one sensor 121 may be disposed within the housing 118, the first axle housing 151 , and the second axle housing 158. Further, it is understood that thecal least one sensor 121 may be disposed on an outer surface of one of the housings 118, 151 , 158 or mounted elsewhere on the vehicle. The at least one sensor 121 is configured as known in the art to monitor at least one of the operating condition of the power source, the temperature of the seGond axle assembly 106, the temperature of a lubricant used with the second axle assembly 106, the speed of a portion of the transfer shaft 1 12 the speed of the second output gear 1 14 the speed of a portion of the second axle assembly 106, the amount of torque transferred to the input shaft 08, the position of the shift collar 1 17, and the position of the clutch associated with the second axle assembly 106. The operating condition of the power source may be at least one of an indication that the power source is operating, a rotational speed of the power source, a state of the vehicle transmission, and a speed of the vehicle. Further, it is understood that the at least one sensor 121 may be configured to indicate an engagement of the actuator 120.
The first axle assembly 104 includes a bevel gear pinion 147, a first driving gear 148, a first wheel differential 149, and a first pair of output axles 150. Preferably, the components 147, 148, 149, 150 are formed from a hardened steel, however the components 147, 148, 149, 150 may be formed from any other rigid material. As shown, the first axle assembly 104 includes the four components 147, 148, 149, 150 disposed in a first axle housing 151 but it is understood t e first axle assembly 104 may include fewer or more components.
The first driving gear 148 is coupled to a housing of the first wheel differential 49 by a plurality of fasteners or a weld and is rotatable about an axis of the first pair of output axles 150 within the first axle housing 151.
Alternately, the first driving gear 148 may be integrally formed with the first wheel differential 149. As is known in the art, the first driving gear 148 has gear teeth formed on an outer surface thereof. The first driving gear 148 may be one of a hypoid gear, a spiral bevel gear, a straight bevel gear, or any other gear known to those ski lied in the art. The first driving gear 148 is drivingly engaged -with the bevel gear pinion 147- and has a first gear ratio. As a non- limiting example, the first gear ratio may be a 2.42: 1 ratio, but it is understood that other ratios may be used. The output shaft 146 is drivingly engaged with the first driving gear 148 of the first axle assembly 104 through a single gear mesh. The first wheel differential 149 is a bevel gear style differential as is known in the art having a plurality of driving pinions and a pair of side gears drivingly engaged with the first pair of output axles 150. The first wheel differential 149 is rotatably disposed within the first axle housing 151 about the axis of the first pair of output axles 150. Alternately, other styles of differentials may be used in place of the first wheel differential 149.
The first pair of output axles 150 are elongate cylindrical members having a common axis rotatably mounted within the first axle housing 151. Bearings 122 disposed between the first pair of output axles 150 and the first axle housing 151 permit the first pair of output axles 150 to rotate therein. The side gears of the first wheel differential 149 are disposed on first ends of each of the first output axles 150 and wheels (not shown) are disposed on second ends of each of the first output axles 150.
The second axle assembly 106 includes an inter-axle shaft 152, a second driving gear 153, a second wheel differential 154, a pair of second output axles 156, and an-axle clutch 157. Preferably, the components 152, 153, 154, 1J56, 157 are formed from a hardened steel, however the components 152, 153, 154, 156, 157 may be formed from any other rigid material. As shown, the second axle assembly 106 includes the five components 152, 153, 154, 156, 157 disposed in a second axle housing 158 but it is understood the second axle assembly 106 may include fewer or more components.
The inter-axle shaft 152 comprises at least one elongate cylindrical member drivingly engaged with the second output gear 1 4 through a driven gear 159 coupled to the inter-axle shaft 152. As illustrated, the inter-axle shaft 152 comprises a plurality of elongate cylindrical members connected by joints. Bearings 122 disposed between the inter-axle shaft 152 and the housing 18 permit the inter-axle shaft 152 to rotate therein.
A bevel gear pinion 160 is drivingly coupled to the inter-axle shaft 152 opposite the driven gear 159. As is known in the art, the bevel gear pinion 159 has gear teeth formed on an outer surface thereof. The bevel gear pinion 160 may be one of a hypoid gear, a spiral bevel gear, a straight bevel gear, or any other gear known to those skilled in the art. The second driving gear 153 is a ring style bevel gear as is known in the art having a set of gear teeth engaged with the gear teeth formed on the bevel gear pinion 160. The second driving gear 53 is coupled to a housing of the second wheel differential 154 by a plurality of fasteners or a weld and is rotatable about an axis of the pair of second output axles 156 within the second axle housing 158. Alternately, the second driving gear 153 may be integrally formed with the second wheel differential 154. The second driving gear 153 is drivingly engaged with the bevel gear pinion 160 and has a second gear ratio. As a non-limiting example, the second gear ratio may be a 3.55: 1 ratio, but it is understood that other ratios may be used. The second gear ratio is a lower gear ratio than the first gear ratio.
The second wheel differential 154 is a bevel gear style differential as is known in the art having a plurality of driving pinions and a pair of side gears drivingly engaged with the pair of second output-axles 156. The second wheel differential 154 is rotatably disposed within the second axle housing 158 about the axis of the pair of second output axies 156. Alternately, other styles of differentials may be used in place of the second wheel differential 154.
The pair of second output axles 156 are elongate cylindrical members having a common axis rotatably mounted within the second axle housing 158. Bearings 122 disposed between the pair of second output axles 156 and the second axle housing 153 permit the first pair of second output axles 56 to rotate therein. The side gears of the second wheel differential 154 are disposed on first ends of each of the second output axies 156 and wheels (not shown) are disposed on second ends of each of the second output axles 156.
The axle clutch 157 is a dog style clutch-that divides one of the second output axles 156 into first and second portions. Alternately, the axle clutch 157 may be a component of the second wheel differential 154 whic engages a side gear of the second wheel differential 154 and one of the second output axles 156. The axle clutch 157 may also be a plate style clutch or any other style clutch. A shift collar 162 slidingly disposed on a first component of the axle clutch 157 selectively engages a plurality of teeth formed thereon with corresponding teeth formed on a first component and a second component of the axle clutch 157. The shift collar 162 is urged into an engaged position or a disengaged position by a shift fork 164 and a disconnect actuator 166. When the axle clutch 157 is in the engaged position, the first portion of one of the second output axles 156 is drivingly engaged with the second portion of one of the second output axles 156.
The disconnect actuator 166 is a linear actuator that upon actuation in response to a signal sent by the controller 119, adjusts a position of the shift collar 162 to drivingly engage the first portion of one of the second output axles 156 with the second portion of one of the second output axles 156. Preferably, the disconnect actuator 166 is a double acting pneumatic cylinder in fluid communication with a pair of solenoid valves (not shown), but it is understood that the disconnect actuator 166 may be an electromechanical actuator or a hydraulic actuator.
The drive axle system 100 facilitates a low speed and high torque multi- axle manner of operation and a high speed and low torque single axle manner of operation. The manner of operation of the drive axle system 100 is determined by a position of the shift collar 117. The drive axle system 100 balances a rotational difference between the first output gear 116 and the second output gear 114 caused by a difference between the first gear ratio and the second gear ratio with the inter-axle differential assembly 102, wherein the balancing of the rotational difference between the first output gear 116 and the second output gear 114 provides a cumulative gear ratio for the first axle assembly 104 and the second axle assembly 106. The cumulative gear ratio is intermediate the first gear ratio and the second gear ratio.
Upon having recognized the circumstances that the high speed and low torque single axle manner of operation of the drive axle system 100 is advantageous in, the controller 1 9 shifts the drive axle system 100 into the first position. As a non-limiting example, circumstances in which the controller 119 may recognize as being advantageous for the high speed and low torque single axle manner of operation are operation of the vehicle not burdened by a load and operation of the vehicle at highway speeds. When t e shift collar 117 is moved into the first position, the shift collar 117 is drivingly engaged with the first set of clutch gear teeth 131 of the transfer shaft 112 and the first set of clutch gear teeth 127 of the pinion carrier 126. Upon having recognized one of the aforementioned conditions, the controller 119 moves the shift collar 117 into the first position. Typically, the controller 119 operates in an automated manner based on a series of instructions or conditions the controller 1 19 is programmed with. Further, the vehicle the drive axle system 100 is incorporated in may be configured to automatically recognize conditions suitable for the high speed and low torque single-axle manner of operation and automatically move the shift collar 117 into the first position using the actuator 120.
Prior to engagement of the first set of clutch gear teeth 131 of the transfer shaft 1 12 and the first set of clutch gear teeth 127 of the input shaft 108 with the shift collar 117, but after the shift collar 1 17 has begun to move towards the first position, the first conical engagement surface 143 of the first synchronizer ring 140 contacts the engagement portion 128 of the pinion carrier 126. Contact of the first conical engagement surface 143 with the engagement portion 128 causes the shift collar 1 17 ( and thus the transfer shaft 112) to accelerate to approximately the same speed of the input shaft 108 and the biasing member disposed between the shift collar 17 and the first
synchronizer ring 140 to compress. Once the shift collar 1 17 has been accelerated to approximately the same speed of the input shaft 108, movement of the shift collar 117 into the first position is completed, and the shift collar 1 7 is simultaneously engaged with the first set of clutch gear teeth 131 of the transfer shaft 1 12 and the first set of clutch gear teeth 127 of the pinion carrier 126.
After engagement of the first set of clutch gear teeth 131 of the transfer shaft 112 and the first set of clutch xjear teeth 127 of the pinion carrier 126 with the shift collar 1 17, the input shaft 108 and the transfer shaft 112 rotate concurrently. Similarly, the pinion carrier 126 and the second end portion 132 of the transfer shaft 1 12 rotate concurrently. As a result of the concurrent rotation, the gear teeth 133 and the driving pinions 1 10 are locked with respect to one another, and the first output gear 1 16 is driven by the driving pinions 110 at the same speed the input shaft 108 rotates at. Placing the shift collar 117 into the first position "locks out" the planetary arrangement comprising the gear teeth 33, the driving pinions 10, and the first output gear 16. Meanwhile, the second output gear 114 sits idle as the shift collar 117 is not engaged with the first set of clutch gear teeth 137. Further, the axle clutch 57 is disengaged, allowing the plurality of driving pinions and the pair of side gears of the second wheel differential 154 to spin freely without need for the inter-axle shaft 152 to spin. In this manner, torque delivered through the input shaft 108 is transferred only to the first output axles 150 while reducing parasitic windage losses that may be caused by needless rotation of the inter- axle shaft 152 and the second output gear 114.
Upon having recognized the circumstances that the low speed and high torque multi-axle manner of operation of the drive axle system 100 is advantageous In, the controller 119 shifts the drive axle system 100 into the second position. As a non-limiting example, circumstances in which the controller 1 19 may recognize as being advantageous for the low speed and high torque multi-axle manner of operation are starting movement of the vehicle from a stopped position, operation of the vehicle along a surface having a positive gradient, operation of the vehicle in a loaded condition, and operation of the vehicle along a surface having a reduced coefficient of friction. When the shift collar 117 is moved into the second position, the shift collar 1 17 is drivingly engaged with the first set of clutch gear teeth 131 of the transfer shaft 112 and the first set of clutch gear teeth 137 of the second output gear 1 14.
Upon having recognized one of the aforementioned conditions, the controller 119 moves the shift collar 117 into the second position. Typically, the controller 1 19 operates a switching mechanism that causes the actuator 20 to electronically or pneumatically move the shift fork 142 and the associated shift collar 1 17 into the second position. Alternately, thB actuator 120 may engage a linkage component directly coupled to the shift fork 142 to move theshiftcollar 117 into the second position. Following movement of the shift collar 1 17 into the second position^ the axle clutch 157 is engaged to not allow each of the second output axles 156 to rotate with respect to one another without rotation of the inter-axle shaft 152. Further, the vehicle the drive axle system 100 is incorporated in may be configured to automatically recognize conditions suitable for the low speed and high torque multi-axle manner of operation and automatically move the shift collar 1 17 into the second position using the controller 1 9.
Prior to engagement of the first set of clutch gear teeth 131 of the transfer shaft 1 12 and the first set of clutch gear teeth 137 of the second output gear 1 14 with the shift collar 1 17, but after the shift collar 1 17 has begun to move towards the second position, the second conical engagement surface 144 of the second synchronizer ring 141 contacts the engagement portion 136 of the second end portion 135 of the second output gear 1 14. Contact of the second conical engagement surface 144 with the engagement portion 144 causes the second output gear 1 14 and the inter-axle shaft 152 to accelerate to- approximately the same speed of the second output gear 1 14 and the biasing member disposed between the shift collar 1 17 and the second synchronizer ring 141 to compress. Once the second output gear 1 14 has been accelerated to approximately the same speed of the transfer shaft 1 12, movement of the shift collar 1 17 into the second position is completed, and the shift collar 1 17 is simultaneously engaged with the first set of clutch gear teeth 131 of the transfer shaft 1 12 and the first set of clutch gear teeth 137 of the second output gear 1 14.
After engagement of the first set of clutch gear teeth 131 of the transfer shaft 1 12 and the first set of clutch gear teeth 137 of the second output gear 1 14 with the shift collar 1 17, the second output gear 1 14 and the transfer shaft 1 12 rotate concurrently. Torque delivered to the input shaft 108 is transferred through the plurality of driving pinions 1 10 to rotate the second end portion 132 of the transfer shaft 1 12 and the first output gear 1 16. Subsequently, torque is transferred to the inter-axle shaft 152-through the second output gear 1 14 and the driven gear 159 and torque is transferred to the output shaft 146. Through the bevel gear pinions 147, 160, driving gears 148, 159, and wheel differentials 149, 154, torque delivered through the input shaft 108 is simultaneously transferred to the first output axles 150 and the second output axles 5&.
FIG. 2 is a chart that illustrates a synchronization process between the shift collar 1 17 and the second output gear 1 14 that typically occur when the second axle assembly 106 is operated in a low temperature environment and is shifted from the high speed and low torque single axle manner of operation to the low speed and high torque multi-axle manner of operation. A lubricant used within the second axle assembly 106 will greatly increase in viscosity when the second axle assembly 106 is operated in a low temperature environment, significantly increasing a duration of the synchronization process between the shift collar 117 and the second output gear 114 when shifting occurs. To facilitate the synchronization process, a speed of the power source is increased by about 250 revolutions per minute over a time period of about 300 ms. In response to the increase of the speed of the power source, a speed of the shift collar 1 17 increases to about 1800 revolutions per minute. Point A on FIG. 2 indicates when the synchronization process is completed. As shown in FIG. 2, the synchronization process takes about 1800 ms to occur. Further, as shown in FIG. 2, the synchronization process consumes energy until the
synchronization process is complete. Following synchronization, the axle clutch 157 can be engaged to complete the shift of the drive axle system 100 to the low speed and high torque single axle manner of operation.
In use, the controller 119 implements a method of shifting the drive axle system 100 that facilitates quick shifting from the high speed and low torque single axle manner of operation to the low speed and high torque multi-axle manner of operation when the controller 119 detects the drive axle system 100 is being operated in a low temperature environment.
By measuring a temperature of the second axle assembly 106 or the temperature of a lubricant used with the second axle assembly 106 using the at least one sensor 121 , the controller 119 determines whether to implement the quick shifting method when shifting the drive axle system 100 from the high speed and low torque single axle manner of operation to the low speed and high torque multi-axle manner of operation. If the temperature of the second axle assembly 106 or the temperature of a lubricant used with the second axle assembly 106 is below a threshold value, the controller 1 9 will implement the quick shifting method when a shift request is received. Further, it is understood that a temperature of an ambient environment the vehicle is operated in, which may be available to the controller 1 19 through a vehicle communication bus (not shown), may also be used to determine if the quick shifting method is employed when a shift request is received. The shift request may be initiated by an operator of the vehicle, a vehicle controller in communication with the controller 1 19, or by the controller 1 19.
FIG. 3 is a cfiart that illustrates a synchronization process between the shift collar 1 17 and the second output gear 1 4 that occurs when the second axle assembly 106 is operated in a low temperature environment and is shifted from the high speed and low torque single axle manner of operation to the low speed and high torque multi-axle manner of operation in accord with the method that facilitates quick shifting.
To facilitate quick shifting of the drive axle system 100, the controller 1 19 delays acceleration of the power source until synchronization of the shift collar 1 17 and the second output gear 1 14 occurs. Once the shift begins, the controller 1 19 (or a controller in communication with the controller 1 19) maintains a speed of the power source in a substantially constant manner while the second output gear 1 14, the driven gear 159, the inter-axle shaft 152, the bevel gear pinion 160, the second driving gear 153, and portions of the second wheel differential 154 are accelerated by the synchronization between the shift collar 1 17 and the second output gear 1 14. As shown on FIG. 3, the
synchronization process takes about 700 ms. Once synchronization is complete, the shift collar 1 17 is drivingly engaged with the first set of clutch gear teeth 137 of the second output gear 1 14, and the synchronization process stops consuming energy. As shown on FIG. 3, Point A indicates when the synchronization process is completed. Following the synchronization process, a speed of the power source is increased by about 250 revolutions per minute over a time period of about 400 ms. Such an increase in rotational speed results in the second output gear 1 14 being driven up to about 1800 revolutions per minute, which allows the driven gear 159, the inter-axle shaft 152, the bevel gear pinion 1=60, the second driving gear 153, and portions of the second wheel differential 154 to rotate at a speed which allows the axle clutch 157 to be engaged, completing the shift of the drive axle system 100 to the low speed and high torque single axle manner of operation. It is understood that the above mentioned values are exemplary in nature and that the principles of the method that facilitates quick shifting may be adapted for use for other devices that require quick shifting. Further, it is understood that the quick shifting method for the drive axle system 100 may be implemented by the controller 19 (or a controller in communication with the controller 1 19) at all times to simplify an operation of the drive axle system 100.
Additionally, it is understood that a hybrid shifting procedure is within the scope of the invention. To facilitate the synchronization process, in the hybrid shifting procedure, a speed of the power source is increased by a smaller amount of revolutions per minute over a time period of less than about 300 ms, compared to the synchronization process illustrated in FIG. 2. In response to the increase of the speed of the power source, a speed of the shift collar 117 increases. The controller 119 (or a controller in communication with the controller 119) then maintains a speed of the power source in a substantially constant manner while the second output gear 114, the driven gear 159, the inter-axle shaft 152, the bevel gear pinion 160, the second driving gear 53, and portions of the second wheel differential 154 are accelerated by the synchronization between the shift collar 117 and the second output gear 114. When the synchronization process is completed, a speed of the power source is increased again to a desired level of revolutions per minute. Such an increase in rotational speed results in the second output gear 114 being driven up to about 1800 revolutions per minute, which allows the driven gear 159, the inter-axle shaft 152, the bevel gear pinion 160, the second driving gear 153, and portions of the second wheel differential 154 to rotate at a speed which allows the axle clutch 157 to be engaged, completing the shift of the drive axle system 100.
Through the use of the quick shifting method for the drive axle system
100, a time required to shift the drive axle system from the high speed and low torque single axle manner of operation to the low speed and high torque multi- axle manner of operatbn in a low-temperature environment can be reduced by- about 42%. Further, the quick shifting method for the drive axle system 1ΌΟ decreases an amount of energy consumed by the synchronization process by about 20%. In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiments, however, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its scope or spirit.

Claims

What is claimed is:
1. A control system for a tandem drive axle system, the control system comprising:
a first actuator in driving engagement with a first clutching device of the tandem drive axle system, the first clutching device for shifting operating modes of the tandem drive axle system;
a second actuator in driving engagement with a second clutching device, the second clutching device for disengaging an axle of the tandem drive axle system; and
a controller in communication with the first actuator and the second actuator, wherein in response to at least one of a temperature the tandem drive axle system is operated in and a temperature of an axle of the tandem drive axle system, the controller adjusts a manner of shifting the drive axle system from a single axle mode of operation to a multi-axle mode of operation.
2. The control system of claim , further comprising a sensor in communication with the controller, the sensor at least one of disposed within and on a housing of the tandem drive axle system.
3. The control system of claim 2, wherein the sensor is configured to monitor at least one of a power source associated with the tandem drive axle system, a temperature of an axle of the tandem drive axle system, a speed of a component of the tandem drive axle system, an amount of rotational force transferred to the tandem drive axle system, a position of the first clutching device, and a position of the second clutching device.
4. The control system of claim 1 , wherein the controller is configured to accept an input containing information regarding at least one of an operating condition of a power source associated with the tandem drive axle system, a temperature of an axle of the tandem drive axle system, a speed of a
component of the tandem drive axle system, an amount of rotational force transferred to the tandem drive axle system, a position of the first clutching device, and a position of the second clutching device.
5. The control system of claim 4, wherein the controller uses the input to adjust 1he at least one of the operating condition of the power source, the position of the first clutching device, the position of the second clutching, and a duration between successive positions of the first clutching device.
6. The control system of claim 5, wherein the controller performs the adjustment to the operating; condition of the power source, the position of the first clutching device, the position of the second clutching device, and the duration between successive positions of the first clutching device based on at least one of the operating condition of the power source, the temperature of an axle of the tandem drive axle system, a speed of a component of the tandem drive axle system, an amount of rotational force transferred to the tandem drive axle system, a position of the first clutching device, and a position of the second clutching device.
7. The control system of claim , wherein the second clutching device is a dog style clutch that divides an axle of the tandem drive axle system into first and second portions.
8. A method of shifting a tandem drive axle system, the method comprising the steps of:
providing a tandem-drive axle system including a first clutching device, a second clutching device;
providing a controller in communication with the first actuator and the second actuator;
detecting at least one of a temperature the tandem drive axle system is operated in and a temperature of an axle of the tandem drive axle system; and adjusting a manner of shifting the drive axle system from a single axle mode of operation to a multi-axle mode of operation; wherein the manner of shifting the drive axle system is adjusted based on at least one of a
temperature the tandem drive axle system is operated in and a temperature of an axle of the tandem drive axle system.
9. The method of claim 8, wherein the controller is configured to accept an input containing information regarding at least one of an operating condition of a power source associated with the tandem drive axle system, a temperature of an axle of the tandem drive axle system, a speed of a component of the tandem drive axle system, an amount of rotational force transferred to the tandem drive axle system, a position of the first clutching device, and a position of the second clutching device.
10. The method of claim 9, wherein the controller uses the input to adjust the at least one of the operating condition of the power source, the position of the first clutching device, the position of the second clutching, and a duration between successive positions of the first clutching device.
11. The method of claim O, wherein the controller performs the adjustment to the operating condition of the power source, the position of the first clutching device, the position of the second clutching device, and the duration between successive positions of the first clutching device based on at least one of the operating condition of the power source, the temperature of an axle of the tandem drive axle system, a speed of a component of the tandem drive axle system, an amount of rotational forc& transferred to the tandem drive axle system, a position of the first clutching device, and a position of the^ second clutching device.
12. The method of claim 8, wherein the step of adjusting a manner of shifting the drive axle system from a single axle mode of operation to a multi- axle mode of operation includes delaying acceleration of the power source until synchronization between the first clutching device and components of a disengaged axle of the tandem drive axle system occurs.
13. The method of claim 12, wherein the step of adjusting a manner of shifting the drive axle system from a single axle mode of operation to a multi- axle mode of operation includes increasing a speed of the power source is by about 250 revolutions per minute over a time period of about 400 milHseconds to allow components of the disengaged axle of the tandem drive axle system to rotate at a speed which allows the second clutching device to be engaged.
14. The method of claim 8, wherein the step of adjusting a manner of shifting the drive axle system from a single axle mode of operation to a multi- axle mode of operation includes maintaining a speed of the power source in a substantially constant manner while components of a disengaged axle of the tandem drive axle system occurs are accelerated by synchronization between the first clutching device and components of the disengaged axle of the tandem drive axle system occurs.
15. The method of claim 14, wherein the step of adjusting a manner of shifting the drive axle system from a single axle mode of operation to a multi- axle mode of operation includes increasing a speed of the power source is by about 250 revolutions per minute over a time period of about 400 milliseconds to allow components of the disengaged axle of the tandem drive axle system to rotate at a speed which allows the second clutching device to be engaged.
16. The method of claim 8, wherein the step of adjusting a manner of shifting the drive axle system from a single axle mode of operation to a multi- axle mode of operation includes increasing a speed of the power source by less than 200 revolutions per minute-over a time period of less lhan about 300 ms to increase a speed of the first clutching device, then maintaining a speed of the power source in a substantially constant manner while components of the disengaged axle of the tandem drive axle system are accelerated by the synchronization between the first clutching device and components of the disengaged axle of the tandem drive axle system.
PCT/US2016/046656 2015-08-14 2016-08-12 Cold weather shift strategy for a dual range disconnect system WO2017030918A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130017927A1 (en) * 2011-01-21 2013-01-17 Dana Heavy Vehicle Systems Group, Llc Method of Shifting a Tandem Drive Axle Having an Inter-Axle Differential
US20130260959A1 (en) * 2008-10-13 2013-10-03 Magna Powertrain Ag & Co Kg Powertrain for a motor vehicle

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130260959A1 (en) * 2008-10-13 2013-10-03 Magna Powertrain Ag & Co Kg Powertrain for a motor vehicle
US20130017927A1 (en) * 2011-01-21 2013-01-17 Dana Heavy Vehicle Systems Group, Llc Method of Shifting a Tandem Drive Axle Having an Inter-Axle Differential

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