Electronic locking differential with direct locking state detection system

(54) Title: LOCK DIFFERENTIAL (57) Summary:

ELECTRONIC WITH DIRECT LOCKING STATE DETECTION SYSTEM (30) Unionist Priority: 31/01/2007 us 11 / 700,564 (73) Owner (s): American Axle & Manufacturing, Inc.

(72) Inventor (s): GREGORYM. DONOFRIO, JeffreyA. Goolsby (74) Attorney (s): DANNEMANN, SIEMSEN,

BIGLER & IPANEMA MOREIRA (86) International Order: pct US2008001210 from

01/30/2008 (87) International Publication: wo 2008 / 094586de

07/08/2008

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38Inventive Patent Descriptive Report for ELECTRONIC LOCKING DIFFERENTIAL WITH DIRECT LOCKING STATE DETECTION SYSTEM.

Introduction

The present invention relates generally to shaft assemblies and more particularly to a shaft assembly having an electronic locking differential.

US patent belonging to the same holder No. 6,958,030 describes an electromagnetic locking differential assembly that employs an electromagnetic drive to selectively couple a side gear to a differential case to make the differential assembly operate in a completely locked condition . More specifically, the electromagnetic drive is driven to axially translate a drive ring (which is coupled to the differential case non-rotatorily) so that the claws on the drive ring correspondingly engage the claws that are formed on one side of the side gear opposite the gear teeth. Although such electronic locking differentials are adjusted for their intended purposes, they are nevertheless susceptible to improvement.

summary

In one form, the present teachings provide an axle assembly that includes an axle housing, a pair of axes and a differential assembly. The differential assembly includes a differential case, ring gear, input pinion, gear set and locking device. The differential box is rotatorily mounted inside the axle housing. The differential box includes a mounting hub and an annular bag. The ring gear is coupled to the differential case for rotation on it. The input pinion is rotatably mounted in the shaft housing and interlocked with the ring gear. The gear set includes first and second side gears and a plurality of pinion gears. The first side gear is close to the first end of the differential case and is coupled by rotation with a first of the axles. The second side gear is close to a second end of the differential housing opposite the first end and coupled by rotation to a second one of the axles. The pinion gears interlocked engage the first and second side gears. The locking device includes a first jaw, a second jaw, a return spring, a thrust member, and a driver. The first jaw includes a plurality of teeth and is not rotatorily coupled to the second side gear. The second jaw includes a plurality of corresponding teeth and is not rotationally, but axially, slidably engaged with the differential case. The return spring tends at least one of the first and second jaws in one direction so that the teeth and the corresponding teeth are not engaged with each other. The driver is mounted on the mounting hub and has a plunger. The actuator is operable in a returned position, which allows the return spring to keep the teeth and the corresponding teeth in an uncoupled condition, and an extended position in which the actuator moves the plunger to push the thrust member and the second claw towards to the first claw so that the teeth and the corresponding teeth engage with each other to thereby inhibit relative rotation between the second side gear and the differential case. The plunger, thrust member and second claw are fixedly coupled to each other.

In another form, the present teachings provide a method for mounting the locking differential. The method includes: providing a differential case; mount a first claw ring in the differential box for rotation about an axis; fixedly engage a spacer to a second claw ring; mount the second claw ring and the spacer in the differential case, the second claw ring being non-rotating and axially suitable with respect to the differential case; mounting a thrust plate to the differential case, the thrust plate having a leg member; fixedly engage the thrust plate at least one between the spacer and the second claw; and mount a driver in the differential case, the driver being extendable to push the thrust plate to drive the second claw ring in engagement with the first claw ring to thereby inhibit relative rotation between the first and second clamping rings claw.

In addition, areas of applicability will become apparent from the description provided here. It should be understood that the specific description and examples are intended for purposes of illustration only and are not intended to limit the scope of this description.

Brief Description of Drawings

The drawings described here are for illustration purposes only and are not intended to limit the scope of the present description in any way.

Figure 1 is a schematic illustration of a vehicle that has a propulsion system built in accordance with the teachings of the present description;

Figure 2 is a partially broken perspective view of a portion of the vehicle of Figure 1, illustrating the rear axle assembly in more detail;

Figure 3 is an exploded perspective view of a portion of the rear axle assembly, illustrating the differential assembly in more detail;

Figure 4 is a partially interrupted perspective view of the differential assembly;

Figure 5 is an exploded perspective view of a portion of the rear axle assembly, illustrating the differential assembly in more detail;

Figure 6 is a perspective view of a portion of the rear axle assembly, illustrating a portion of the locking mechanism in more detail; and

Figure 7 is a perspective view of a portion of the rear axle assembly, illustrating a portion of the locking mechanism in more detail.

Detailed Description Of The Various Modalities

With reference to figure 1 of the drawings, an exemplary vehicle 10 is shown schematically and may include a transmission system 12 and a steering system 14. The transmission system 12 may include a power source, such as an internal combustion engine 16 and a transmission 18 that can receive rotational energy from the engine 16 and produce power for the steering system 14. The steering system 14 can include a transfer case 20, a rear drive axle 22, a rear axle assembly 24, a front drive axle 26 and a front axle assembly 28. The transfer case 20 can be used for transmit drive torque from transmission 18 to rear and front assemblies 24 and 28. The transfer case 20 can include an input shaft (not shown specifically), which can be coupled to the transmission 18 to receive rotary energy from there, a rear output shaft 30, which can be coupled to the rear drive shaft 22, and a front output shaft 32 which can be coupled to the front drive shaft 26. The rear drive shaft 22 can transmit rotational energy from the rear output shaft 30 to an input pinion 34 of the rear axle assembly 24. The front drive shaft 26 can transmit rotational energy from the front output shaft 32 to an input pinion 36 of the front axle assembly

28. The rear axle assembly 24 can include a differential assembly 38 that can be driven by the input pinion 34 and can produce rotary energy to drive a pair of vehicle rear wheels 40. Similarly, the front axle assembly 28 can include an assembly the differential 42 which can be driven by the input pinion 36 and can produce rotary energy to drive a pair of vehicle front wheels 42.

Front and rear axle assemblies 24 and 28 may be similar in construction and operation and as such, only rear axle assembly 24 will be discussed in detail here. With further reference to figure 2, the rear axle assembly 24 may include an axle housing 50, a differential assembly 38 and a pair of axles 54 (only one of which is shown specifically). The shaft housing 50 can be conventionally configured and may include a housing structure 60 and

With reference to figure 1 of the drawings, an exemplary vehicle 10 is shown schematically and may include a transmission system 12 and a steering system 14. The transmission system 12 may include a power source, such as an internal combustion engine 16 and a transmission 18 that can receive rotational energy from the engine 16 and produce power for the steering system 14. The steering system 14 can include a transfer case 20, a rear drive axle 22, a rear axle assembly 24, a front drive axle 26 and a front axle assembly 28. The transfer case 20 can be used for transmit drive torque from transmission 18 to rear and front assemblies 24 and 28. The transfer case 20 can include an input shaft (not shown specifically), which can be coupled to the transmission 18 to receive rotational energy from there, a rear output shaft 30, which can be coupled to the rear drive shaft 22, and a front output shaft 32 which can be coupled to the front drive shaft 26. The rear drive shaft 22 can transmit rotational energy from the rear output shaft 30 to an input pinion 34 of the rear axle assembly 24. The front drive shaft 26 can transmit rotational energy from the front output shaft 32 to an input pinion 36 of the front axle assembly 28. The rear axle assembly 24 can include a differential assembly 38 that can be driven by the input pinion 34 and can produce rotational energy to drive a pair of vehicle rear wheels 40. Similarly, the front axle assembly 28 may include a differential assembly 42 that can be driven by the input pinion 36 and can produce rotational energy to drive a pair of vehicle front wheels 44.

Front and rear axle assemblies 24 and 28 may be similar in construction and operation and as such, only rear axle assembly 24 will be discussed in detail here. With further reference to figure 2, the rear axle assembly 24 may include an axle housing 50, the differential assembly 38 and a pair of axles 54 (only one of which is shown specifically). The shaft housing 50 can be conventionally configured and may include a housing structure 60 and a pair of bearing caps 62 that can be fixedly, but removably coupled to the housing structure 60. The housing structure 60 can define a differential cavity 64 that houses the differential assembly 38. The bearing covers 62 can be detached from the housing structure 60 to allow the differential assembly 38 to be received inside the differential cavity 64. The axles 54 can be coupled to opposite sides of the differential assembly 38 and the respective wheels. rear of vehicle 40 (figure 1) in any appropriate manner.

With additional reference to figures 3 and 4, the differential assembly 38 may include a differential housing 70, a ring gear 72 (figure 2), a gear assembly 74, a locking system 76 and the input pinion 34 ( figure 2). Inlet pinion 34 and ring gear 72 can be conventionally constructed and assembled in shaft housing 50 and as such, need not be discussed in significant detail here. Briefly, the input pinion 34 can be coupled to the shaft housing 50 through a set of bearings (not specifically shown) and arranged around a rotating axis that is generally perpendicular to the rotating axis of the differential case 70. The Inlet 34 may include a plurality of pinion teeth (not shown) which can be interlocked with a plurality of ring gear teeth (not shown specifically) formed in ring gear 72.

The differential housing 70 may include a body portion 80 and a circumferentially extending flange 82 that is coupled to (e.g. integrally formed with) body portion 80. Flange 82 may include a plurality of openings 84 which can facilitate the removable coupling for ring gear 72 via a plurality of threaded fasteners 86.

The body portion 80 can define a gear assembly cavity 90 and one or more mounting windows 92, which can be used to install gear assembly 74 in the gear assembly cavity 90. In the example provided, the body portion 80 includes mounting of the driver 150 which can generally be concentric with the trunnion 120. A circumferentially extending groove 152 can be formed on the mounting surface of the driver 150. A plurality of openings 154 can be formed axially through the second end segment 106 and can intersect the second annular pocket 142. The second annular pocket 142 can include a portion of pocket 160, a plurality of locking features 162 and a ring ring pocket. buoyancy 164. In the example provided, the pocket portion 160 is generally circular in conformation and the locking features 162 can be recesses that can intersect the pocket portion 160. The locking features 162 can be shaped in any appropriate manner and in the example provided, have a half circle shape that extends from the pocket portion 160. The thrust ring pocket 164 can be circular in shape and concentric with the portion bag 160.

The gear assembly 74 may include first and second side gears 170 and 172, respectively, first and second pinion gears 174 and 175, respectively, a transverse axis 178 and a retaining screw 180. The first side gear 170 may include an annular gear portion 190, which may have a plurality of gear teeth, an annular hub portion 192, which may intersect gear portion 190 on a flange face 194, and a grooved opening 196 which can engage a corresponding grooved segment (not shown) formed in a corresponding one of the axes 54. The hub portion 192 can be sized to be received in the second orifice portion 134 in the first end segment 104, while a portion of the gear portion 190 can be received in the first orifice portion 132. In the particular example provided, a lock washer thrust 200 is arranged on the hub portion 192 and rests on the flange face 194.

The second side gear 172 may include a gear portion 210, which may have a plurality of gear teeth, a tubular hub portion 212 and a grooved opening 216. The tubular hub portion 212 may axially extend from the second late gear 172 in a direction opposite to the gear portion 210. The grooved opening 216 can be formed through the tubular hub portion 212 and can engage a corresponding grooved segment (not shown) formed in a corresponding one of the axes 54. The second side gear 172 can be received in the first pocket portion 160 of the second end segment 106. A thrust washer 220 can be arranged in the thrust ring pocket 164 between the inner surface 222 of the second end segment 106 and an axial end face 224 of the tubular hub portion 212. It will be appreciated that the thickness of the thrust washer 220 can be selected to control the clearance between the teeth of the second side gear 172 and the teeth of the first and second pinion gears 174 and 176.

The first and second pinion gears 174 and 176 can be rotatorily mounted on the transverse axis 178 and interlocked with the teeth of the first and second side gears 170 and 172. The transverse axis 178 can extend through the continuous holes 108 in the first and second side segments 100 and 102. Washer-type spacers 230 can be used to control the clearance between the first and second pinion gears 174 and 176, and the first and second side gears 170 and 172. Retaining screw 180 can be inserted into retaining hole 128 and threadedly engaged with a corresponding threaded opening 232 formed on the transverse axis 178 to thereby securely hold the transverse axis 178 to the differential housing 70.

The locking system 76 may include a first claw ring 240, a second claw ring 242, a return spring 244, a spacer ring 246, a thrust plate 248, a driver assembly 250, a first retaining ring 252 and a second retaining ring 260.

With reference to figures 3 to 5, the first claw ring 240 can be coupled (for example, integrally formed) with the second side gear 172 in a portion opposite the gear portion 210. The first claw ring 240 can include a a plurality of radially extending, circumferentially spaced teeth 270 and a circular groove 272 that can be arranged between the tubular hub portion 212 and the teeth 270. In the example provided, teeth 270 are relatively numerous and shallow in order to provide increased strength and load sharing between teeth 270 as well as to decrease tooth contact stresses.

The second claw ring 242 can include a portion of the annular body 280, a plurality of corresponding locking features 282, a circular groove 284 and a pilot portion 286. The portion of the annular body 280 can be received in the pocket portion 160 of the second annular pocket 142 and can include a plurality of teeth 290 which are configured to correspondingly engage teeth 270 of the first jaw ring 240. Circular groove 284 can be arranged radially inwardly of teeth 290 and can generally correspond to circular groove 272 formed in the first jaw ring 240. Pilot portion 286 can be an axially projecting annular ring that can help retain the return spring 244 to the second claw ring 242. Additionally or alternatively, the pilot portion 286 can engage a corresponding feature formed on the first claw ring 240 or the second side gear 172 which can guide or assist in guiding the teeth 290 of the second claw ring 242 in engagement with the teeth 270 of the first claw ring 240. The corresponding locking features 282 can be coupled to the annular body portion 280 and in the example provided, comprise tabs that are semicircular in conformation. The corresponding locking features 282 are configured to engage the locking features 162 in the second annular pocket 142 to allow the second claw ring 242 to be not rotatorily coupled to the differential case 70, but axially movable with respect to the differential case 70 to the along the rotary axis of the differential box 70.

The spacer ring 246 can be unitarily formed from a suitable material, such as a polymer, which can be non-magnetic. The spacer ring 246 can include a spacer body 300 and devices 302 for attaching the spacer body 300 to the second claw ring 242 and thrust plate 248. The spacer body 300 can include a generally flat body portion 304 and a plurality of gloves leg 306 that can be disposed around body portion 304. The leg sleeves 306 can be formed as a portion of a hollow cylinder and can define a retaining opening 308. The coupling devices 302 can be any devices suitable for fixedly or fixedly, but removably coupling the spacer body 300 to the second ring jaw 242. For example, coupling devices 302 may comprise adhesives, welds, rivets, threaded fasteners, pins, wrenches, etc. In the particular example provided, the coupling devices 302 include a plurality of fastening members 310 that extend from the body portion 304. Each fastening member 310 can include a leg portion 312, which can extend radially inwardly. body portion 304, and an arm portion 314 which may be generally perpendicular to the leg portion 312. The arm portion 314 can include a hook structure 316 that can be configured to engage the second claw ring 242. In the particular example provided, the hook structure 316 includes a pair of tapered leading edges 318, a pair of boundary walls 320 and a central slot 322. When the body portion 304 of the spacer ring 246 is supported on the second claw ring 242, the tapered lead edges 318 of the hook structures 316 contact the surfaces of the locking openings 326 that are formed in the second claw ring 242, causing that the hook structures 316 fold inwardly. It will be appreciated that the locking openings 326 can be chamfered to facilitate the deflection of the hook structures 316 as the hook structures 316 are being inserted into the locking openings 326. When the hook structures 316 have passed through the second claw ring 242, the hook structures 316 can return to their normal conformation to keep the boundary walls 320 and the body portion 304 locked against the opposite sides of the second claw ring 242 in a pressure-fixed manner as shown in figure 6. In the particular example shown, the boundary walls 320 of the hook structures 316 are tapered in order to pull the spacer ring 246 to rest on the second claw ring 242 when the two are coupled together. The construction in this way allows the two components to be supported against each other despite the dimensional variation in the manufacture of the second claw ring 242 and the spacer ring 246 to thereby minimize or eliminate the final fatigue between the two components. The spacer ring 246 can be arranged within the pocket portion 160 around the locking features 162 and can be positioned axially between the second claw ring 242 and the surface 160a of the pocket portion 160.

The return spring 244 can be any suitable spring and can tend the first and second claw rings 240 and 242 apart from each other. In the example provided, return spring 244 is a double wave spring that can be arranged in circular grooves 272 and 284. It will be appreciated that return spring 244 can tend the second claw ring 242 to rest on spacer ring 246 and the spacer ring 246 rests on the second end segment 106.

The thrust plate 248 can be unitarily formed from a suitable material, such as a polymer. Thrust plate 248 can include a plate portion 350, a plurality of leg members 352, a device 354 for coupling leg members 352 for both the second claw ring 242 and the spacer ring 246, and a device 356 to couple the thrust plate 248 to the driver 250. The plate portion 350 can have an annular conformation and can be dimensioned to be slidably received on the mounting surface of the driver 150. Leg members 352 can be coupled to the plate portion 350 and can extend axially through the openings of the actuator 154 formed on the second end segment 106. The end of the leg members 352 opposite the plate portion 350 can engage the second claw ring 242 in an appropriate area. In the example provided, buoyancy plate 248 includes four leg members 352 each of which limits a corresponding one of the corresponding locking features 282. Coupling device 354 can include any device 12 suitable for fixedly or fixedly, but removably coupling to thrust plate 248 to spacer ring 246 or second claw ring 242, including pins, rivets, threaded fasteners, adhesives, etc. In the particular example provided, the coupling device 354 includes locking tabs 358 that can be formed on the leg members 352 and configured to engage the retaining openings 308 that are formed on the leg sleeves 306. In this example, the leg sleeves 306 extend through the openings of the driver 154 and rest on the plate portion 350 when the locking tabs 358 are received in the retaining openings 308 to thereby lock the second claw ring 242, the spacer ring 246 and the thrust plate 248 to each other as shown in figure 7.

The assembly of the actuator 250 can generally be similar to that described in the co-pending patent application US 11 / 507,311, filed on August 21, 2006 entitled Electronically Powered Apparatus Using Solenoid Actuator With Integrated Sensor, the description of which is incorporated herein as title reference, in its entirety. Briefly, the assembly of the actuator 250 can be a linear actuator having a plunger 380, a solenoid 382 that can be selectively activated to move the plunger 380, one or more sensors 384 that can be employed to detect a position of the plunger 380 and, responsively generate a sensor position signal, a sleeve 390 and an anti-rotation clamp 392.

Bushing 390 may be formed from a suitable material, such as a sintered bronze impregnated with oil conforming to ASTM B438. Bushing 390 can have an outside diameter, which can be dimensioned to engage solenoid 382, ​​via an interference fit. The sleeve 390 can define an internal diameter that is dimensioned to be articulated supported on the mounting surface of the driver 150 (figure 4) of the mounting hub 140 (figure 4) of the differential housing 70 (figure 4). The anti-rotating clamp 392 can be formed of a suitable material, such as a material that has a low magnetic susceptibility (for example, 316 stainless steel), and can be coupled to solenoid 382 through an appropriate coupling device, such as fasteners ( for example, threaded fasteners, rivets), welds or adhesives. The anti-rotation clamp 392 can be configured to engage the opposite side surfaces of an associated one of the bearing covers 62 (figure 2) in order to inhibit a relative rotation between the shaft housing 50 (figure 2) and the mounting of the driver 250.

Returning to figures 3 to 5, the plunger 380 can be slidably received in the mounting hub 140 and coupled to the thrust plate 248 through the coupling device 356. The coupling device 356 can comprise any one suitable for fixedly or fixedly, but removably couple the plunger 380 to the thrust plate 248. In the particular example provided, coupling device 356 includes a hub portion 400, which extends from plate portion 350 on a side opposite leg members 352, and a retaining ring groove 402 that extends circumferentially around the hub portion 400. Hub portion 400 may be on its side to be received into a central hole 404 that is formed in plunger 380. The retaining ring groove 402 can be positioned on one side of the plunger 380 opposite its front face 406 and the first retaining ring 252 can be received in the retaining ring groove 402 to thereby couple the plunger 380 to the plate thrust 248. It will be appreciated that the plunger 380 is efficiently coupled to the second claw ring 242 in the example provided so that the movement of one of the plunger 380 and the second claw ring 242 will cause corresponding movement of the other one of the plunger 380 and the second ring of claw 242.

The solenoid 382 can be slidably received in the mounting hub 140 and supported against the plunger 380. The second retaining ring 260 can be received in the groove that extends circumferentially 152 in the mounting surface of the driver 150 and can inhibit axial removal of the mounting of the driver 250 of mounting hub 140.

When the actuator assembly 250 is actuated, the plunger 380 will move the thrust plate 248 so that the leg members 352 propel the second claw ring 242 towards the first claw ring 240 so that the teeth 270 and 290 the first and second claw rings 240 and 242 engage each other. As the second claw ring 242 is coupled non-rotatorily to the differential case 70 and as the first claw ring 240 is coupled non-rotatorily to the second side gear 172, the engagement of teeth 270 and 290 inhibits rotation of the second side gear 172 with respect to to the differential box 70, thereby locking the differential assembly 38 (figure 2) to inhibit the speed difference between axles 54 (figure 2). It will be appreciated that the anti-rotating clamp 392 can contact the sides of the adjacent bearing cover 62 (figure 2) to thereby inhibit or limit the rotation of the driver assembly 250 with respect to the shaft housing 50 (figure 2). It will be appreciated that driver 250 is immersed in a fluid (i.e., a lubricating and cooling oil), the openings 444 in the plunger 380 can be sized and shaped to reduce surface tension and friction.

With specific reference to figure 5, the plunger 380 may include a pair of flange members 450a and 450b. A sensor target 452, which can be formed from a magnetic iron material, can be overmolded over the flap member 450a. Flap member 450b can be received in a corresponding slot (not shown) in solenoid 382; the slot and the flap member 450b can cooperate to inhibit relative rotation between the plunger 380 and the solenoid 382.

In the example provided, sensor 384 includes a pair of digital Hall effect sensors. A first one of the digital Hall effect sensors can be programmed to produce a first signal when plunger 380 (and thus the second claw ring 242) is in a position further from the first claw ring 240, and a second signal when the plunger 380 (and thus the second claw ring 242) is in a position closer to the first claw ring 240. Similarly, the second one of the digital Hall effect sensors can be programmed to produce a third signal when the plunger 380 (and thus the second claw ring 242) is in a position further from the first claw ring 240, and a fourth signal when plunger 380 (and thus the second claw ring

242) is in a position closer to the first claw ring 240. The first and fourth signals may have a first voltage and the second and third signals may have a different, second voltage. The construction in this way provides a level of redundancy that provides a robust design and the ability to more readily identify faults in the operation of the 384 sensor.

Although specific examples have been described in the specification and illustrated in the drawings, it will be understood by those skilled in the art that various changes can be made and equivalences can be replaced by their elements without departing from the scope of the present description as defined in the claims. Furthermore, the mixture and combination of resources, elements and / or functions among several examples are expressly contemplated here so that the person skilled in the art would appreciate from that description what characteristics, elements and / or functions of an example can be incorporated in another example as appropriate, unless otherwise described above. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present description without departing from its essential scope. Thus, it is intended that the present description should not be limited to the particular examples illustrated by the drawings and described in the specification as the best way presently contemplated for carrying out that invention, but that the scope of the present description will include any modalities that are within the aforementioned description and the appended claims.