CN113007305A

CN113007305A - Axle assembly with torque sensor

Info

Publication number: CN113007305A
Application number: CN202011468431.2A
Authority: CN
Inventors: 史蒂文·R·怀特曼; 迪恩·H·乐赫克
Original assignee: Deere and Co
Current assignee: Deere and Co
Priority date: 2019-12-20
Filing date: 2020-12-14
Publication date: 2021-06-22
Also published as: DE102020216198A1

Abstract

A torque sensing assembly for a differential of an axle assembly is shown in the present disclosure. The differential may include a differential housing portion, a drive gear shaft positioned within the differential housing portion, a ring gear, a carrier, a differential pinion, a first side gear, a second side gear, a first bearing support, and the torque sensing assembly. The first bearing is coupled to the differential case portion and is rotatable with the carrier. The first bearing support is coupled to the differential case portion and is used to support the first bearing. The torque sensing assembly is coupled to the first bearing support and is operable to measure a strain thereof resulting from a separation force generated between the drive gear shaft and ring gear.

Description

Axle assembly with torque sensor

Technical Field

The present disclosure relates generally to an axle assembly and a torque sensing assembly applied to the axle assembly.

Background

For mechanical drivelines, measurement of axle torque applied to an axle assembly, such as a front axle assembly, is desirable because it can affect the efficiency and longevity of individual driveline components, and can provide information related to the operation of the vehicle and any attached implements or accessories for further use or processing.

Disclosure of Invention

An axle assembly coupled to a driveshaft is provided. The axle assembly may include a first axle unit, a second axle unit, a differential coupled to the first and second axle units, an axle housing, a drive gear shaft (drive in) positioned within the axle housing, a ring gear, a carrier, a differential pinion, first and second side gears, a first axle, a second axle, a first bearing support, and a torque sensing assembly. The ring gear is engaged with the drive gear shaft and is driven in rotation by the drive gear shaft. The carrier is attached to the ring gear and rotates with the ring gear. The differential pinion is coupled to the carrier and is operable to rotate with the ring gear and self-rotate about a differential pinion axis. The first and second side gears are respectively engaged with and driven by the differential pinion. The first axle is coupled to the first axle gear and rotates with the first axle gear. The second axle is coupled to the second side gear and rotates with the second side gear. The first bearing is coupled to the axle housing and is rotatable with the carrier. The first bearing support is coupled to the axle housing and is used to support the first bearing. The torque sensing assembly is coupled to at least one of the axle housing and the first bearing support and is operable to measure a strain thereof resulting from a separation force generated between the drive gear shaft and the ring gear.

In one aspect of the present disclosure, the torque sensing assembly includes a first strain gauge and a second strain gauge positioned on the first bearing support.

In one aspect of the disclosure, a first radial direction from a center of the first bearing support toward the first strain gauge and a second radial direction from the center of the first bearing support toward the second strain gauge form an angle of less than 60 degrees.

In one aspect of the present disclosure, the axle assembly further includes a fastener positioned on the first bearing support. The first strain gauge, the fastener, and the second strain gauge are on an arc, and the first strain gauge and the second strain gauge are at ends of the arc.

In one aspect of the disclosure, the fastener is positioned in the middle of the arc.

In one aspect of the present disclosure, the distance between the first side gear and the ring gear is closer than the distance between the second side gear and the ring gear.

In one aspect of the present disclosure, the torque sensing assembly includes a third strain gauge coupled to the first housing portion of the first axle unit and operable to measure strain of the first housing portion when the first axle unit is in operation.

In one aspect of the disclosure, the first bearing support protrudes with a first outer ring portion coupled to a first outer ring of the first bearing.

In one aspect of the present disclosure, the axle housing includes a differential housing portion of the differential. The differential housing portion includes a first differential side plate, the first bearing support being coupled to the first differential side plate.

In one aspect of the present disclosure, the first differential side plate includes a receiving hole extending in a direction from a surface of the differential case portion toward the first bearing. The receiving hole is for receiving a fourth strain gauge comprising a strain gauge pin operable to measure strain in the receiving hole.

In one aspect of the present disclosure, the fourth strain gauge includes a strain gauge fastener coupling a body of the fourth strain gauge to the differential case portion to provide an axial preload relative to the body of the fourth strain gauge.

In one aspect of the disclosure, a sensing portion of the body of the fourth strain gauge engages the bottom of the receiving hole to measure its strain and cooperates with the strain gauge fastener to provide the axial preload.

In one aspect of the present disclosure, the fourth strain gauge and the receiving hole are press-fitted.

In one aspect of the disclosure, the fourth strain gauge includes an upper portion and a lower portion coupled to the upper portion. The lower portion has a smaller diameter than the upper portion and is operable to measure the strain in the receiving hole.

A differential for an axle assembly is provided. The differential may include a differential housing portion, a drive gear shaft positioned within the differential housing portion, a ring gear, a carrier, a differential pinion, a first side gear, a second side gear, a first bearing support, and a torque sensing assembly. The ring gear is engaged with the drive gear shaft and is driven to rotate by the drive gear shaft. The carrier is attached to the ring gear and is adapted to rotate with the ring gear. The differential pinion is coupled to the carrier and is operable to rotate with the ring gear and self-rotate about a differential pinion axis. The first and second side gears are respectively engaged with and driven by the differential pinion. The first bearing is coupled to the differential case portion and is rotatable with the carrier. The first bearing support is coupled to the differential case portion and is used to support the first bearing. The torque sensing assembly is coupled to the first bearing support and is operable to measure a strain thereof resulting from a separation force generated between the drive gear shaft and the ring gear.

A differential for an axle assembly is provided. The differential may include a differential housing portion, a drive gear shaft positioned within the differential housing portion, a ring gear, a carrier, a differential pinion, a first side gear, a second side gear, a first bearing support, and a torque sensing assembly. The ring gear is engaged with the drive gear shaft and is driven in rotation by the drive gear shaft. The carrier is attached to the ring gear and is adapted to rotate with the ring gear. The differential pinion is coupled to the carrier and is operable to rotate with the ring gear and self-rotate about a differential pinion axis. The first and second side gears are respectively engaged with and driven by the differential pinion. The first bearing is coupled to the differential case portion and is rotatable with the carrier. The first bearing support is coupled to the differential case portion and is used to support the first bearing. The torque sensing assembly is coupled to the differential housing portion and is operable to measure a strain thereof resulting from a separation force generated between the drive gear shaft and the ring gear.

In one aspect of the present disclosure, the differential case portion includes a first differential side plate to which the first bearing support is coupled, the first differential side plate including a receiving hole extending in a direction from a surface of the differential case portion toward the first bearing. The receiving hole is for receiving the torque sensing assembly, which includes a strain gauge pin operable to measure strain in the receiving hole.

Other features and aspects will become apparent by consideration of the detailed description and accompanying drawings.

Drawings

FIG. 1 is a schematic perspective view of an axle assembly.

FIG. 2 is a side view of the differential with the axle assembly of the first axle unit removed.

FIG. 3 is an exploded cross-sectional perspective view of the axle assembly of FIG. 1.

FIG. 4 is an exploded cross-sectional view of the axle assembly of FIG. 1.

Fig. 5 is a front view of a first bearing support with the first and second strain gauges shown in fig. 3 and 4.

Fig. 6 is a partial cross-sectional view of the axle assembly of fig. 1 showing two of the third strain gauges.

Fig. 7A is a cross-sectional view of a fourth strain gauge having a strain gauge pin in one embodiment.

Fig. 7B is an enlarged cross-sectional view of the fourth strain gauge of fig. 7A.

Fig. 8 is a cross-sectional view of a fourth strain gauge having a strain gauge pin in another embodiment.

FIG. 9 is a schematic diagram illustrating a controller connecting first, second, third and fourth strain gauges located in different portions of an axle assembly.

Detailed Description

The present disclosure includes a torque sensing assembly having one or more strain gauges applied to a bearing support of a driveline component (e.g., differential). The differential may be an open (standard) differential or a limited slip differential. Strain gauges detect strain on the bearing support and/or other portions of the drivetrain, and such values may be used by the controller to calculate the torque of the driveshaft (e.g., the front axle driveshaft) or another component, as strain values detected from a particular location of the bearing support or other location of the axle housing may have a positive correlation with the torque of the driveshaft (axle input torque). In particular, the strain and torque may be substantially linear.

Due to the geometry of the front axle drive shaft with drive gear shaft and ring gear, carrier, differential pinion gear(s) (planet gears) attached to the carrier (two in this embodiment), differential side gear(s) (two in this embodiment), first bearing, bearing support, etc., the strain gauge(s) of the torque sensing assembly detect the strain caused by the separation load/force. The separation load is caused by the engagement (or reaction force) between the drive gear shaft and the ring gear. The detailed structure is described below.

As shown in fig. 1-3 and 9, work vehicle 99 includes an axle assembly 10. Work vehicle 99 may include, but is not limited to, agricultural equipment (e.g., combine, tractor, harvester, loader), or construction equipment (e.g., backhoe, dump truck, dozer, excavator, motor grader, scraper), or forestry equipment (e.g., feller stacker and skidder). Work vehicle 99 may include any other vehicle having one or more of the powertrain components described herein. In the present disclosure, the axle assembly 10 as shown in fig. 1-4 is a front axle assembly 10, but in another embodiment it may be a rear axle assembly or other axle assembly. In another embodiment, the axle assembly 10 may be mounted in a forward and rearward position, i.e., four-wheel drive. The (front) axle assembly 10 includes an axle housing 12. The front axle assembly 10 may include a first axle unit 16, a second axle unit 18, and a differential 20 coupled between the first and

second axle units

16, 18 via bolts 19. The first axle unit 16 has a first axle 162 and the second axle unit 18 has a second axle 182. The first axle 162 and the second axle 182 are each coupled to a portion of a ground engaging unit, such as a wheel rim (not shown). The axle housing 12 of the axle assembly 10 includes a differential housing portion 122 of the differential 20, a first housing portion 124 of the first axle unit 16, and a second housing portion 126 of the second axle unit 18. The axle housing 12 is operable to receive variable driveline components, such as differential case, gears, axles, as will be described later.

As shown in fig. 3 and 4, the differential 20 coupled to a drive shaft (not shown) may include, but is not limited to, an axle housing 12, a drive gear shaft 24, a ring gear 26, a differential case (carrier) 28, a differential pinion gear 30, a first side gear 32, a second side gear 34, a first bearing 36, a first bearing support 38, a second bearing 40, and a second bearing support 42. The number of the foregoing elements is illustrated in the embodiments for illustrative purposes only. The drive gear shaft 24 is typically coupled to a (front axle) drive shaft (not shown) via a universal joint 44 (shown in FIG. 1). As shown in fig. 3, the drive gear shaft 24 is positioned within the axle housing 12. The ring gear 26 is engaged with the drive gear shaft (pinion gear) 24, and is driven to rotate by the drive gear shaft 24. The ring gear 26 is a spiral bevel ring gear. A carrier 28 is attached to the ring gear 26 for rotation with the ring gear 26. In this embodiment, the carrier 28 is fixed to the ring gear 26 via bolts 46. Within the carrier 28, two differential pins 31, each of which holds a pair of differential pinions 30 (only one differential pinion 30 of each pair of differential pinions 30 is shown in fig. 3), so that the differential pinions 30 can rotate with the ring gear 26. Additionally, the differential pinion 30 may be self-rotating about its own differential pinion axis. When the differential pinions 30 rotate and/or spin, they engage or creep over the first side gear 32 and/or the second side gear 34, and thus the first side gear 32 and the second side gear 34 (differential side gears) may rotate independently of the carrier 28. In this regard, when the work vehicle 99 having the differential 20 is turning left or right, one of the first side gear 32 or the second side gear 34 may ensure that the outer wheel or other external ground engaging unit rotates faster than the inner wheel or other internal ground engaging unit. Power (or torque from the front axle drive shaft) may be transferred through the drive gear shaft 24, the ring gear 26, the carrier 28 (and clutch plates 48 inside the carrier 28), the differential pinion gear 30, the first side gear 32, and/or the second side gear 34, and ultimately to the first axle unit 16 coupled to the first side gear 32 and/or the second axle unit 18 coupled to the second side gear 34. In this embodiment, the distance in the lateral direction between the first side gear 32 and the ring gear 26 is shorter than the distance in the lateral direction between the second side gear 34 and the ring gear 26.

As shown in fig. 3 and 4, the first bearing 36 and the second bearing 40 are applied on different sides of the carrier 28. The distance between the first bearing 36 and the ring gear 26 in the lateral direction is shorter than the distance between the second bearing 40 and the ring gear 26 in the lateral direction. A first inner ring portion 282 protrudes from a first side 281 of the carrier 28 (toward a first wheel, not shown) and a second inner ring portion 286 protrudes from a second side 285 of the carrier (toward a second wheel, not shown). As for the first bearing 36, as shown in fig. 4, it has a first inner race 362, a first outer race 364 (first bearing cup), and rolling elements 366 (e.g., rollers) between the first inner race 362 and the first outer race 364. The first inner race 362 is coupled to the first inner ring portion 282 and is configured to rotate with the carrier 28. The rolling elements 366 are coupled to the first inner race 362 and configured to roll in response to rotation of the first inner race 362. The first outer race 364 with respect to which the rolling elements 366 roll is fixed to the first bearing support 38 (sleeve). The first bearing support 38 (sleeve) is coupled to the differential housing portion 122 of the axle housing 12 and is configured to support the first bearing 36. As shown in fig. 4, the body of the first bearing support 38 is positioned on the left portion of the first bearing 36 to prevent the first bearing 36 from moving out of the differential 20. The differential case portion 122 includes a first differential side plate 121 and a second differential side plate 129, and the carrier 28 is positioned therebetween. The first bearing support 38 is coupled to the first differential side plate 121 by fasteners 382, which in this embodiment are bolts. In this embodiment, the first bearing support 38 projects with a first outer ring portion 384 that is coupled to the first outer ring 364 and is parallel to the first inner ring portion 282 of the carrier 28. The first bearing 36 is sandwiched by a first inner ring portion 282 of the carrier 28 and a first outer ring portion 384 of the first bearing support 38. The first differential side plate 121 includes an aperture 123. The first outer ring portion 384 of the first bearing support 38 and the aperture 123 are press fit.

In this embodiment, the torque sensing assembly 60 is applied to the first bearing support 38. However, in another embodiment, a torque sensing assembly (not shown) may be applied on the second bearing support 42. In another variation, both the first bearing support 38 and the second bearing support 42 may be mounted with one or more torque sensing assemblies 60. As shown in the embodiments below, the strain gauges of the torque sensing assembly 60 may be located at or in a bearing receiving element, such as a bearing support member(s) that deflect under strain when loaded. Thus, these strain gauges produce a strain signal caused by the gear separation force that is proportional to the driveline torque. Because the strain gauges may be positioned on or near the bearings and bearing supports (the gear separation forces of interest may be at the bearings and bearing supports), the strain measurements are less affected by vehicle structural loads.

Referring to fig. 4 and 5, in this embodiment, the torque sensing assembly 60 includes a first strain gauge 62 and a second strain gauge 64 positioned on the first bearing support 38. For example, a first radial direction from the center of the first bearing support 38 toward the first strain gauge 62 and a second radial direction from the center of the first bearing support 38 toward the second strain gauge 64 form an angle θ that is less than or equal to 60 degrees. In another embodiment, the angles may be different angles. As shown in fig. 5, in this embodiment, the first bearing support 38 has an axle hole 381, and the first axle 162 passes through the axle hole 381. The first bearing support 38 may have an inner support portion 385 adjacent the axle bore 381, and may have an outer support portion 387, the outer support portion 387 being a flange or platform of the inner support portion 385. The inner support portion 385 and the outer support portion 387 form a step therebetween. In this embodiment, the outer support portion 387 of the first bearing support 38 includes a plurality of apertures 386. As previously mentioned, there are a plurality of fasteners 382 coupling the first bearing support 38 to the first differential side plate 121 of the differential case portion 122 through the apertures 386 of the outer support portion 387. In this embodiment, the first and second strain gauges 62, 64 are positioned on the outer support portion 387 of the first bearing support 38. One of the fasteners 382 is positioned between the first and second strain gauges 62, 64. The first strain gauge 62, fastener 382 and second strain gauge 64 are on an arc. The first and second strain gauges 62, 64 are at the ends of the arc. The fastener is positioned in the middle of the arc, but in another embodiment it need not be in the middle.

In a variation, there are more than one fastener aligned in the same arc between the first and second strain gauges 62, 64.

In a variant, only one strain gauge or more than two strain gauges are applied on the outer and/or inner support part. In a variant, it is not necessary or necessary that all the strain gauges are positioned on the same arc.

In this embodiment, the apertures 386 on the outer support portion 387 of the first bearing support 38 are equally spaced. For purposes of strain measurement, in another embodiment, the distance of the holes 386 may be different. For example, the hole between the first strain gauge 62 and the second strain gauge 64 (if there is only one) is defined as the only hole. The distance between adjacent regular holes is longer than the distance between two adjacent regular holes (not shown). For another embodiment, there is no hole between the first strain gauge 62 and the second strain gauge 64, but the distance between a hole adjacent to the first strain gauge 62 and another hole adjacent to the second strain gauge 64 is longer than the distance between two other adjacent regular holes. In variations, the fastener (if only one) between the first and second strain gauges 62, 64 may be different from other fasteners, which may be smaller or more flexible; the hole corresponding to the fastener may correspond to the size of the fastener.

In another embodiment, the first bearing support 38 is coupled to the first differential side plate 121 of the differential case portion 122 by other means.

In another embodiment, the first bearing support 38 may additionally include different type(s) of holes/apertures for receiving the torque sensor assembly 60, such as the first and second strain gauges 62, 64. Such hole(s) may be blind hole(s) or through holes. The torque sensor assembly 60 (first strain gauge 62 or second strain gauge 64) may include a retainer attached to the wall of the bore. The retainer may be press fit into the bore. The torque sensor assembly may also include a sleeve corresponding to and attached to the inner surface of the retainer. One or more strain sensors are attached to the sleeve and configured to detect strain of the first bearing support caused by a separation force between the drive gear shaft and the ring gear. Optionally, the sleeve is a flexible printed circuit board electrically coupled to the plurality of strain gauges via traces.

As shown in fig. 3 and 4, when drive gear shaft 24 rotates, a separation force F1 is generated resulting from the rotation of (helical cone) drive gear shaft 24 and ring gear 26. The resulting gear separation force Fr, which may be proportional in magnitude to the separation force F1 between the drive gear shaft 24 and the ring gear 26, is transmitted to the first bearing support 38. The torque sensor assembly 60 (e.g., the first strain gauge 62 and/or the second strain gauge 64) thus detects the strain caused by the resulting gear force Fr. As shown in fig. 9, the controller 90 of a work vehicle 99 having an axial assembly 10 may receive strain signals from the torque sensor assembly 60 (e.g., the first, second, third, and/or fourth strain gauges 62, 64, 66, 68) to calculate the axle input torque due to geometry-based correlations. The third and fourth strain gauges 66 and 68 will be described later in the description.

The number of the third strain gauges 66 may be one or more. Fig. 1 and 4 illustrate a third strain gauge 66; fig. 6 shows two third strain gauges 66. The third strain gauge(s) 66 are coupled to the first housing portion 124 of the first axle unit 16 and are operable to measure the strain of the first housing portion 124 when the first axle unit 16 is in operation. As shown in fig. 6, the deflection in the first housing portion 124 may be proportional to the axle input torque due to the reaction of the traction force F2 from the tire/wheel and, thus, the compressive force exerted on the axle unit 16. This deflection DL can be monitored with a third strain gauge 66. The resulting output of the third strain gauge 66 may be proportional to the axle input torque.

Referring to fig. 7A, 7B and 8, a fourth strain gauge 68 of the torque sensing assembly 60 is introduced. The first differential side plate 121 of the differential case portion 122 includes a receiving hole 1212 (in fig. 8, a receiving hole 1214) extending in the radial direction from the surface of the differential case portion 122 toward the first bearing 36. The bottom 1213 of the receiving hole 1212 is adjacent to the aperture 123 of the first differential side plate 121. The receiving hole (1212 or 1214) is configured to receive a fourth strain gage 68, the fourth strain gage 68 including a strain gage pin (682 or 686) operable to measure the strain in the receiving hole (1212 or 1214) of the first differential side plate 121 caused by the separation force F1. Because the first outer ring portion 384 of the first bearing support 38 abuts the aperture 123 (press fit), and the outer support portion 387 of the first bearing support 38 overlaps a lower portion of the receiving bore (1212, 1214) in a radial direction relative to the center of the axle bore 381 of the first bearing support 38, the resulting force can be readily transmitted to the receiving bore (1212, 1214), causing deflection thereof, and facilitating measurement of the strain detected by the fourth strain gauge 68.

In one embodiment, as shown in fig. 2, 7A, and 7B, the fourth strain gage 68 includes a strain gage pin 682. The strain gage pin 682 includes a strain gage fastener 683 that couples the body of the strain gage pin 682 to the differential case portion 122. The strain gauge fastener 683 can include a threaded feature coupled to the threaded upper portion of the receiving bore 1212 and a nut 684 coupled to the threaded feature. The sensing portion 685 of the strain gage pin 682, which in this embodiment is the bottom of the body of the strain gage pin 682, engages the bottom 1213 of the receiving hole 1212 to measure its strain. The sensing portion 685 cooperates with the strain gage fastener 683 to provide an axial preload against the main body of the strain gage pin 682. The axial preload may be uniform and may be adjusted by the nut 684 of the strain gage fastener 683. A consistent axial preload on the strain gage pin 682 may ensure that the strain gage pin 682 accurately measures strain.

Referring to fig. 8, the fourth strain gauge 68 includes a strain gauge pin 686. The strain gage pins 686 and receiving holes 1214 are press fit, which may also provide axial preload. The configuration of the receiving holes 1214 corresponds to the configuration of the strain gage pins 686. Strain gauge pin 686 includes an upper portion 687 and a lower portion 688 coupled to upper portion 687. The lower portion 688 has a smaller diameter than the upper portion 687 and is operable to measure strain in the receiving hole 1212. Note that the lower portion 688 of strain gage pin 686 is press fit into the lower portion of the receiving hole 1212, which is the active area of the differential case portion 122 for strain measurement.

As shown in fig. 9, the first, second, third and fourth strain gauges 62, 64, 66, 68 measure the strain on the first bearing support 38, the first housing portion, and/or the first differential side plate 121 and transmit a signal(s) indicative of the strain resulting from the separation force F1 or operation of the first axle unit 16 to the controller 90 of the work vehicle 99 to calculate the torque. The relationship between axle input torque, first bearing support deflection and strain thereof, and axle housing deflection may be mathematically defined based on the size of the gears, the size of the tires, and the stiffness of the axle components. The controller(s) 90 may include, but are not limited to, an Engine Control Unit (ECU), a Transmission Control Unit (TCU), a Chassis Control Unit (CCU), and signal controllers (analyzers) coupled to the strain gauges 62, 64, 66, 68. The signal controller communicates with the ECU, TCU, CCU via a controller area network (not shown). The CAN chassis is typically placed on a CAN bus that includes a first signal carrying line and a second signal carrying line. The controller(s) 90 are connected to the first and second signal carrying lines. The controller(s) 90 may be coupled to or include memory operable to store data.

The measurement of torque can be used for different purposes. For example, torque information may be received by the controller 90, and if there is an excessive torque load, the controller 90 may reduce the engine speed to ensure efficiency and longevity of the power transmission unit. Direct driveline torque measurements may be used for engine control. By sensing driveline torque more directly, the expected engine load can be transferred electronically to the ECU so the engine can be properly fueled (power management) before mechanical loads are transmitted through driveline components and pull down the engine. The direct driveline torque measurements may be used for Adaptive Shift Control (ASC) in a driveline control unit to shift in an appropriate manner for different grades of the ground surface. Direct driveline strain measurements may also be used for driveline predictions. The driveline strain signal may be monitored and compared to a normal driveline signal. Deviations from this normal signal may indicate damage sustained by the gears and bearings. Continued deviation from normal values may be used to alert an operator or dealer that a powertrain is about to fail.

Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example embodiments disclosed herein is to measure strain from the bearing support or axle housing, where other loads (e.g., vehicle structural loads) do not interfere with the measurements.

While the foregoing describes example embodiments of the present disclosure, these descriptions should not be viewed in a limiting sense. Rather, other changes and modifications may be made without departing from the scope and spirit of the disclosure as defined in the appended claims.

Claims

1. An axle assembly (10) coupled to a driveshaft, said axle assembly comprising:

a first axle unit (16);

a second axle unit (18);

a differential (20) between the first and second axle units (16, 18) and coupled to the first and second axle units (16, 18);

an axle housing (12);

a drive gear shaft (24) positioned within the axle housing (12);

a ring gear (26) engaged with the drive gear shaft (24) and driven for rotation by the drive gear shaft (24);

a carrier (28) attached to the ring gear (26) and configured to rotate with the ring gear (26);

a differential pinion (30), said differential pinion (30) coupled to said carrier (28), operable to rotate with said ring gear (26) and to self-rotate about a differential pinion axis;

first and second side gears (32, 34) respectively engaged with the differential pinion (30) and driven by the differential pinion (30);

a first axle (162) coupled to the first axle gear (32) and rotating with the first axle gear (32);

a second axle (182) coupled to the second side gear (34) and rotating with the second side gear (34);

a first bearing (36) coupled to the axle housing (12) and rotatable with the carrier (28);

a first bearing support (38) coupled to the axle housing (12) and configured to support the first bearing (36);

a torque sensing assembly (60) coupled to at least one of the axle housing (12) and the first bearing support (38) operable to measure a strain of the at least one of the axle housing (12) and the first bearing support (38) resulting from a separation force generated between the drive gear shaft (24) and the ring gear (26).

2. The axle assembly (10) of claim 1 wherein the torque sensing assembly (60) includes a first strain gauge (62) and a second strain gauge (64) positioned on the first bearing support (38).

3. The axle assembly (10) of claim 2 wherein a first radial direction from a center of the first bearing support (38) toward the first strain gauge (62) and a second radial direction from the center of the first bearing support (38) toward the second strain gauge (64) form an angle of less than 60 degrees.

4. The axle assembly (10) of claim 2, further comprising a fastener (382) positioned on the first bearing support (38), and wherein the first strain gauge (62), the fastener (382), and the second strain gauge (64) are on an arc and the first strain gauge (62) and the second strain gauge (64) are at ends of the arc.

5. The axle assembly (10) of claim 1, wherein a distance between the first side gear (32) and the ring gear (26) is closer than a distance between the second side gear (34) and the ring gear (26).

6. The axle assembly (10) of claim 1, wherein the torque sensing assembly (60) includes a third strain gauge (66) coupled to a first housing portion (124) of the first axle unit (16) and operable to measure strain of the first housing portion (124) when the first axle unit (16) is in operation.

7. The axle assembly (10) of claim 1, wherein the axle housing (12) includes a differential housing portion (122) of the differential (20), and the differential housing portion (122) includes a first differential side plate (121) to which the first bearing support (38) is coupled.

8. The axle assembly (10) of claim 7 wherein the first differential side plate (121) includes a receiving hole (1212, 1214) extending in a direction from a surface of the differential housing portion (122) toward the first bearing (36), and the receiving hole (1212, 1214) is configured to receive a fourth strain gauge (68) including a strain gauge pin (682, 686) operable to measure strain in the receiving hole (1212, 1214).

9. The axle assembly (10) of claim 8 wherein the fourth strain gauge (68) includes a strain gauge fastener (683) that couples a body of the fourth strain gauge (68) to the differential housing portion (122) to provide an axial preload relative to the body of the fourth strain gauge (68).

10. The axle assembly (10) of claim 9 wherein the sensing portion (685) of the main body of the fourth strain gauge (68) engages the bottom (1213) of the receiving bore (1212) to measure strain at the bottom (1213) of the receiving bore (1212) and cooperate with the strain gauge fastener (683) to provide the axial preload.

11. The axle assembly (10) of claim 8 wherein the fourth strain gauge (68) and the receiving hole (1214) are press fit.

12. The axle assembly (10) of claim 11, wherein the fourth strain gauge (68) includes an upper portion (687) and a lower portion (688) coupled to the upper portion (687), and the lower portion (688) has a smaller diameter than the upper portion (687) and is operable to measure the strain in the receiving hole (1214).

13. A differential (20) of an axle assembly (10), comprising:

a differential case portion (122);

a drive gear shaft (24) positioned within the differential housing portion (122);

a differential pinion (30) coupled to the carrier (28), operable to rotate with the ring gear (26) and to self-rotate about a differential pinion axis;

a first bearing (36) coupled to the differential housing portion (122) and rotatable with the carrier (28);

a first bearing support (38) coupled to the differential case portion (122) and configured to support the first bearing (36);

a torque sensing assembly (60) coupled to the first bearing support (38) and operable to measure a strain of the first bearing support (38) resulting from a separation force generated between the drive gear shaft (24) and the ring gear (26).

14. The differential of the axle assembly (10) of claim 13, wherein a distance between the first side gear (32) and the ring gear (26) is closer than a distance between the second side gear (34) and the ring gear (26).

15. A differential (20) of an axle assembly (10), comprising:

a differential case portion (122);

a torque sensing assembly (60) coupled to the differential case portion (122) and operable to measure a strain of the differential case portion (122) resulting from a separation force generated between the drive gear shaft (24) and the ring gear (26).