Vehicle driveline having a vehicle driveline component with a dual disconnecting differential

A vehicle driveline component having a differential input, which is rotatable about a differential axis, a differential gearset that is driven by the differential input, first and second differential outputs, which are rotatable about the differential axis, a first disconnect clutch and a second disconnect clutch. The differential gearset has a first gearset output and a second gearset output that are rotatable about the differential axis. The first disconnect clutch selectively couples the first differential output to the first gearset output, while the second disconnect clutch selectively couples the second differential output to the second gearset output.

FIELD

The present disclosure relates to vehicle driveline having a vehicle driveline component with a dual disconnecting differential.

BACKGROUND

Vehicles having a disconnecting driveline are increasingly common in modern vehicles. Disconnecting all-wheel drive drivelines, for example, provide all-wheel drive capabilities in some situations where additional traction needed, but may be disconnected to permit the driveline to be operated in a two-wheel drive mode for increased fuel economy. Disconnecting all-wheel drive drivelines typically include a primary axle, which is typically the front axle, a secondary axle, and a power take-off unit, which that can transmit power between the primary and secondary axle, a first disconnect clutch, which can selectively interrupt power transmission between the power take-off unit and the secondary axle, and one or more second disconnect clutches, which can selectively interrupt power transmission between the secondary axle and one or more of the vehicle wheels that are driven by the secondary axle.

Certain disconnecting driveline configurations, such as those having a secondary axle that selectively disconnects one wheel from one of the outputs of a differential assembly in the secondary axle, provide a torque transmission path between the non-disconnected wheel and the differential assembly that permits the gearing within the differential assembly to be “back driven” when the secondary axle is operated in the disconnected mode. Such configurations do not maximize the fuel efficiency that could be obtained through the disconnection of the secondary axle.

Other disconnecting driveline configurations that disconnect both of the wheels from the outputs of the differential assembly in the secondary axle, via multiple clutches or couplings, for example, are not entirely satisfactory in that they require multiple actuators and/or take up too much space. Consequently, there remains a need in the art for a disconnecting driveline having an improved disconnectable secondary axle in which both of the wheels driven by secondary axle can be disconnected from the differential assembly of the secondary axle.

SUMMARY

In one form, the present disclosure provides a vehicle driveline having a differential input, which is rotatable about a differential axis, a differential gearset that is driven by the differential input, first and second differential outputs, which are rotatable about the differential axis, a first disconnect clutch and a second disconnect clutch. The differential gearset has a first gearset output and a second gearset output that are rotatable about the differential axis. The first disconnect clutch selectively couples the first differential output to the first gearset output, while the second disconnect clutch selectively couples the second differential output to the second gearset output.

In another form, the present disclosure provides a vehicle driveline that includes a housing, an input pinion, a ring gear, a differential assembly and an actuator. The input pinion is received in the housing and is rotatable about a pinion axis. The ring gear is meshed with the input pinion and is rotatable about a differential axis that is transverse to the pinion axis. The differential assembly has a differential case, a plurality of differential pinions, first and second side gears, first and second output members, a first disconnect clutch and a second disconnect clutch. The differential case defines a cavity and is coupled to the ring gear for rotation therewith. The pinions are received in the cavity and are rotatably coupled to the differential case. The first and second side gears are received in the cavity and are meshingly engaged to the differential pinions. The first and second side gears are rotatable about the differential axis. The first output member is received in the chamber and disposed between a first axial end of the differential case and the first side gear. The second output member is received in the chamber and is disposed between a second, opposite axial end of the differential case and the second side gear. The first and second side gears are received between the first and second outputs. The first clutch has a first dog, which is fixedly coupled to the first side gear, a second dog, which is fixedly coupled to the first output, and a first biasing spring that biases the second dog along the differential axis away from the first dog. The second clutch has a third dog, which is non-rotatably but axially slidably coupled to the second side gear, a fourth dog, which is fixedly coupled to the second output, and a second biasing spring that biases the third dog along the differential axis away from the fourth dog. The actuator has an electromagnet, a plunger, a plurality of first pins, and a plurality of second pins. The electromagnet is rotatably disposed on an exterior surface of the differential case. The plunger is received on the exterior surface of the differential case and is disposed axially along the differential axis between the first axial end of the differential case and the electromagnet. The first pins extend through the first end of the differential case and are disposed in a first load transmission path between the plunger and the second dog. The second pins extend through the first end of the differential case radially outwardly of the first pins. The second pins are disposed in a second load transmission path between the plunger and the third dog. Operation of the electromagnet to move the plunger along the differential axis toward the first axial end of the differential case causes corresponding movement of the first and second pins to thereby engage the second dog to the first dog and to engage the third dog to the fourth dog.

DETAILED DESCRIPTION

With reference toFIG. 1, an exemplary vehicle driveline component constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral10. In the particular example provided, the vehicle driveline component10is an axle assembly, but it will be appreciated that the vehicle driveline component could be configured differently. For example, the vehicle driveline component10could comprise a transfer case, a power take-off unit, or a center differential.

The vehicle driveline component10can include a housing12, an input pinion14, a ring gear16, a (disconnecting) differential assembly18, a first and second output shafts20and22, respectively, and an actuator24(FIG. 2). The housing12defines a cavity28into which the input pinion14, the ring gear16and the second differential assembly18are received. The input pinion14is supported by the housing12for rotation about a pinion axis30. The ring gear16is meshed with the input pinion14and is rotatable about a differential axis32that is transverse to the pinion axis30. The vehicle driveline component10is operable in a connected mode, in which rotary power received from a propshaft36is transmitted through the differential assembly18to drive a pair of drive wheels (not shown), and a disconnected mode in which the drive wheels are rotationally de-coupled from respective outputs of the differential assembly18.

With reference toFIGS. 2 and 3, the differential assembly18can include a differential input40, a differential gearset42, first and second differential outputs44and46, a first disconnect clutch48and a second disconnect clutch50. The differential input40is coupled to the ring gear16for rotation about the differential axis32and is configured to input rotary power into the differential gearset42.

With reference toFIGS. 2 and 3, the differential input40can be variously configured depending on the particular configuration differential gearset42. For example, the differential input40could be an internal gear (not shown) formed into or coupled to the ring gear16(FIG. 1) if the differential gearset42were to have a spur planetary gear configuration. In the example provided, the differential input40is a differential case54that defines an internal case cavity56. The differential case54is shown to have a two-piece configuration with a case member60and a cap62that is fixedly coupled to the case member60. Construction in this manner can be advantageous for the assembly of the differential gearset42and the first and second disconnect clutches48and50into the case cavity56, but it will be appreciated that the differential case54could be constructed differently.

The differential gearset42has first and second gearset outputs70and72, respectively, that are rotatable about the differential axis32. The differential gearset42could have any desired configuration, such as a spur planetary configuration (not shown), in which the first and second gearset outputs70and72could be a sun gear and a planet carrier or could be a pair of sun gears, a configuration that employs helical pinions and side gears (not shown), in which the first and second gearset outputs70and72are the side gears, or the configuration shown in which the differential gearset42includes differential pinions76and first and second side gears78and80, respectively, having straight bevel gear teeth. The differential pinions76are coupled to the differential case54for rotation about respective pinion axes and are meshingly engaged with the first and second side gears78and80. In the example shown, a quantity of two of the differential pinions76are employed, with the differential pinions76being rotatably mounted on a cross-pin82that is fixedly coupled to the differential case54so as to be perpendicular to the differential axis32. Also in the example provided, the first side gear78is the first gearset output70, while the second side gear80is the second gearset output72.

The first and second differential outputs44and46can be sleeve-like structures having an internally splined aperture86into which a male splined segment88on an associated one of the first and second output shafts20and22, respectively, can be received to thereby non-rotatably couple the first differential output44to the first output shaft20and non-rotatably couple the second differential output46to the second output shaft22. The opposite ends of the first and second output shafts20and22can be drivingly coupled to respective ones of the drive wheels.

The first and second disconnect clutches48and50can be any type of clutch that can be received in the case cavity56to selectively couple the first and second gearset outputs70and72to the first and second differential outputs44and46, respectively. In the particular example provided, each of the first and second disconnect clutches48and50is a dog clutch.

With reference toFIG. 4, the first disconnect clutch48can comprise a first dog90, a second dog92and a first return spring94. The first dog90can be fixedly coupled to the first gearset output70and can include a plurality of first engagement features96, such as face teeth, that can project from the first gearset output70axially toward the second dog92. The second dog92can be fixedly coupled to the first differential output44and can include a plurality of second engagement features98that are configured to matingly engage with the first engagement features96on the first dog90. In the example provided, the second dog92is an annular flange that projects radially outwardly from the first differential output44and the second engagement features98comprise apertures in the annular flange. If desired, the first engagement features96could be formed with a predetermined amount of back-taper (e.g., 1.5 degrees per side), and/or the second engagement features98could be formed with a corresponding amount of positive taper (e.g., 1.5 degrees per side) to permit the first and second engagement features96and98to more readily engage one another. The first return spring94can be disposed between the first and second dogs90and92and can bias the second dog92(and the first differential output44) along the differential axis32in a direction toward an interior surface100(FIG. 2) of a first axial end102(FIG. 2) of the differential case54(FIG. 2).

Returning toFIG. 3, the second disconnect clutch50can comprise a third dog110, a fourth dog112and a second return spring114. The third dog110can include a dog ring120and a dog member122.

With reference toFIGS. 2, 5 and 6, the dog ring120can have an annular body126and a plurality of dog teeth128that are disposed about the circumference of the annular body126and which extend radially inwardly from the annular body126. The dog ring120can be received into a counterbore130formed in the differential case54and can be translated along the differential axis32relative to the differential case54.

With reference toFIGS. 7 and 8, the dog member122can include first teeth136that are formed about the circumference of the second gearset output72. With additional reference toFIGS. 2 and 5, the dog teeth128of the dog ring120can be meshed to and slidable on the first teeth136of the dog member122. As such, the dog ring120and the dog member122are coupled to one another for common rotation about the differential axis32.

With reference toFIGS. 2, 9 and 10, the fourth dog112can be fixedly coupled to the second differential output46and can include a plurality of second teeth140that are configured to matingly engage with the dog teeth128(FIG. 5) on the dog ring120. In the example provided, the fourth dog112is an annular flange142that projects radially outwardly from the second differential output46and the second teeth140project radially outwardly from the annular flange142. If desired, the dog teeth128(FIG. 5) and the second teeth140could be formed with a predetermined amount of back-taper (e.g., 1.5 degrees per side) to permit the dog teeth128(FIG. 5) and the second teeth140to more readily engage one another.

As shown inFIG. 2, the second return spring114can be disposed between the dog ring120and a second axial end150of the differential case54. In the example provided, the second return spring114is a wave spring that is received into an annular groove152formed into the differential case54. The second return spring114can bias the dog ring120away from the second differential output46.

The actuator24is configured to simultaneously control the operation of the first and second disconnect clutches48and50and can include a linear motor160, a set of first thrust elements162and a set of second thrust elements164. The linear motor160has a motor output170that is configured to move the set of first thrust elements162and the set of second thrust elements164. In the example provided, the linear motor160is a conventional solenoid having an electromagnet180, an armature182and a plunger184, but it will be appreciated that other types of linear motors, including hydraulic or pneumatic cylinder, and moreover that the solenoid could have a bi-stable configuration that permits the solenoid to be maintained a desired condition (i.e., extended or retracted) without the need for constant electrical power. The solenoid can be received on an external circumferentially extending surface190proximate the first axial end102of the differential case54. A bushing192can be disposed between the electromagnet180and the differential case54to permit relative rotation between the solenoid and the differential case54. An external snap ring196can be received into a groove198formed into the differential case54and can limit movement of the solenoid along the differential axis32in a direction away from the first axial end102of the differential case54. The armature182can be coupled to (e.g., unitarily and integrally formed with) the first axial end102of the differential case54. The plunger184, which is fixedly coupled to the electromagnet180in the example provided, is the motor output170of the linear motor160in the example provided. The plunger184can be disposed along the differential axis32between the first axial end102of the differential case54and the electromagnet180. It will be appreciated that operation of the electromagnet180will cause corresponding translation of the electromagnet180and the plunger184along the differential axis32. It will be appreciated, however, that the solenoid could be configured such that the armature182is formed separately from the differential case54and the plunger184and the armature182are coupled to one another for movement along the differential axis32relative to the electromagnet180.

With reference toFIGS. 2 and 3, the set of first thrust elements162can be disposed between the motor output170(i.e., the plunger184in the example provided) and the second dog92, while the set of second thrust elements164can be disposed between the motor output170and the dog ring120. The set of first thrust elements162can include a plurality of first pins that are received through the first axial end102of the differential case54. The first pins are disposed in a first load transmission path between the plunger184and the second dog92. The set of second thrust elements164can include a plurality of second pins that are received through the first axial end102of the differential case54radially outwardly of the first pins. The second pins are disposed in a second load transmission path between the plunger184and the dog ring120.

In operation of the vehicle driveline component10, the first return spring94biases the second dog92out of engagement with the first dog90(as shown inFIG. 2), and the second return spring114biases the dog ring120out of engagement with the fourth dog112(as shown inFIG. 2) to thereby decouple the first and second differential outputs44and46from the first and second gearset outputs70and72. In this condition, both of the drive wheels are rotationally decoupled from the differential gearset42and consequently, none of the components of the differential gearset42(i.e., the first and second side gears78and80and the differential pinions76) is back-driven by the drive wheels so that improved fuel economy can be provided. It will be appreciated that force exerted by the first and second return springs94and114urges the first and second thrust elements162and164along the differential axis32away from the first dog90such that the electromagnet180is abutted against the external snap ring196.

With reference toFIGS. 3 and 11, electrical energy can be provided to the electromagnet180to cause the electromagnet180(and the plunger184) to travel along the differential axis32toward the first axial end102of the differential case54. Movement of the plunger184in this manner causes corresponding movement of the first and second thrust elements162and164, which drive the second dog92and the dog ring120, respectively, into engagement with the first dog90and the fourth dog112, respectively, as is shown inFIG. 11. Engagement of the first and second dogs90and92with one another provides a power path between the first gearset output70(i.e., the first side gear78in the example provided) and the first differential output44through which rotary power can be transmitted. Similarly, engagement of the dog ring120with the fourth dog112provides a power path between the second gearset output72(i.e., the second side gear80in the example provided) and the second differential output46through which rotary power can be transmitted.

Accordingly, a vehicle driveline component for a disconnecting all-wheel drive driveline having a relatively compact and inexpensive differential assembly that is configured to disconnect both of the drive wheels from a differential gearset is provided.

With reference toFIG. 12, the vehicle driveline component10is illustrated as being a rear axle assembly in an all-wheel drive driveline AWDD. In this example, a powertrain PT, having an internal combustion engine ICE and a transmission T, provides rotary power to a front axle assembly FAA that is driven on a full-time basis. A power take-off unit PTU is employed to selectively transmit rotary power to the rear axle assembly via a rear propshaft RP.

With reference toFIG. 13, the vehicle driveline component10is illustrated as being a front axle assembly in a four-wheel drive driveline 4WDD. In this example, a powertrain PT, having an internal combustion engine ICE and a transmission T, provides rotary power to a transfer case TC. The transfer case TC provides rotary power to a rear axle assembly RAA via a rear propshaft RP to drive the rear axle assembly RAA on a full-time basis. The transfer case TC is also coupled the front axle assembly via a front propshaft FP. The transfer case TC includes a clutch (not specifically shown) that permits selective transmission of rotary power to the front axle assembly.