JP7476303B2 - Electric drive module with a transmission having parallel twin gear pairs with load sharing to a final drive gear - Google Patents

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62/942,496, filed December 2, 2019, the disclosure of which is incorporated by reference as if fully set forth herein.

[0002] The present disclosure relates to an electric drive module with a transmission having parallel gear pairs that share the load with a final drive gear.

[0003] This section provides background information related to the present disclosure, but which is not necessarily prior art.

[0004] It is known in the art to provide an electric drive module having an electric motor that drives a differential assembly through a transmission. Known electric drive module configurations can have a coaxial configuration in which the output shaft of the electric motor, the differential assembly, and the input and output of the transmission are disposed about a common axis of rotation, or a configuration in which the output shaft of the electric motor, the differential assembly, and the input and output of the transmission are disposed about two or more axes of rotation that are parallel to one another. While such configurations are well suited for their intended purposes, they can be somewhat difficult to fit or fit into some vehicles, as there may not be enough space laterally or radially. Thus, there is a need in the art for an electric drive module with a relatively compact design.

[0005] This section provides a general summary of the disclosure and is not an exhaustive disclosure of its complete scope or all of its features.

[0006] In one form, the present disclosure provides an electric drive module including an electric motor, a differential assembly, and a transmission that transfers rotational power between the electric motor and the differential assembly. The transmission has a first reduction gear and a second reduction gear. The first reduction gear has a drive gear rotatable about a first axis and a pair of first reduction gears meshingly engaged to the drive gear and rotatable about respective second axes. The second axes are spaced apart from one another and parallel to the first axis. The second reduction gear has a driven gear and a pair of second reduction gears. The driven gears are rotatable about a third axis parallel to the first axis. Each of the second reduction gears is meshingly engaged to the driven gear and non-rotatably coupled to an associated one of the first reduction gears.

[0007] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0008] The drawings described herein are only for purposes of illustrating selected embodiments, rather than all possible implementations, and are not intended to limit the scope of the disclosure.

[0009] FIG. 1 is a schematic diagram of an exemplary vehicle having an electric drive module constructed in accordance with the teachings of the present disclosure. FIG. 2 is a partially exploded perspective view of the electric drive module of FIG. 1 showing the electric motor and transmission in greater detail. FIG. 2 is a cross-sectional view of a portion of the electric drive module of FIG. 1 showing the final drive gear and differential assembly of the transmission. FIG. 2 is a schematic diagram of a portion of the electric drive module of FIG. 1 showing the relative positions of the electric motor, the transmission, and the differential assembly. FIG. 2 is a perspective view of a portion of the electric drive module of FIG. 1 showing an optional parking lock mechanism. FIG. 1 is a top view of a portion of a parking lock mechanism showing a pawl disposed in engagement with a pair of parking gears to secure a middle shaft of an electric drive module. FIG. 1 is a cross-sectional view through a portion of the parking lock mechanism showing the cam plate oriented in a first rotational position and the pair of plungers disposed in an extended position. FIG. 1 is a perspective view of a portion of a parking lock mechanism showing a pawl disengaged from a pair of parking gears to allow rotation of the electric drive module's intermediate shaft. FIG. 1 is a cross-sectional view through a portion of the parking lock mechanism showing the cam plate oriented in a second rotational position and the pair of plungers disposed in a reverse position; FIG. 1 is a perspective view, partially in section, of a parking lock mechanism; FIG. 2 is a perspective view of a portion of the parking lock mechanism showing a first face of the cam plate in greater detail; FIG. 2 is a cross-sectional view of a portion of the parking lock mechanism showing the lock actuator in greater detail. FIG. 4 is a perspective view of a portion of the cam plate showing locking openings formed in a second face of the cam plate; FIG. 2 is a perspective view of a portion of a parking lock mechanism showing the plunger in an extended position and the pawl in an engaged position;

[0023] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

[0024] Referring to FIG. 1 of the drawings, an exemplary vehicle having a drive module constructed in accordance with the teachings of the present disclosure is generally designated by reference numeral 10. Vehicle 10 may include a front or first drivetrain 14 and a rear or second drivetrain 16. Front drivetrain 14 may include an engine 18 and a transmission 20 and may be configured to drive a front or first set of drive wheels 22. Rear drivetrain 16 may include an electric drive module 24 that may be configured to drive a rear or second set of drive wheels 26 as needed or "on demand." While front wheels 22 are associated with first drivetrain 14 and rear wheels 26 are associated with second drivetrain 16 in this example, it will be understood that in the alternative, the rear wheels may be driven by the first drivetrain and the front wheels may be driven by the second drivetrain. Additionally, although the electric drive module 24 is shown in this example as being configured to drive a second set of drive wheels part of the time, it will be understood that a drive module configured in accordance with the present teachings may also be used to drive one set (front, rear, or other) of drive wheels (e.g., the front wheels or a set of wheels) full time, either as the sole means for propelling the vehicle or in conjunction with another means for propulsion. The electric drive module 24 may include a drive unit 30 and a pair of axle shafts 32.

2 and 3, the drive unit 30 may include a housing 40, an electric motor 42, a transmission 44, and a differential assembly 46. The housing 40 may define a structure to which the other components of the drive unit 30 are attached. The housing 40 may be formed of two or more housing elements that may be fixedly coupled together, such as by a plurality of threaded fasteners. The electric motor 42 may be any type of electric motor, such as a permanent magnet motor. The electric motor 42 may be mounted to a flange (not specifically shown) on the housing 40 and may have an output shaft 56 that may be disposed along a first axis of rotation 58 (FIG. 4) and received within the housing 40.

2 and 4, the transmission 44 may include one or more transmission stages or reduction gears that provide a transmission input driven by the output shaft of the electric motor 42 and a transmission output that drives the differential assembly 46. The transmission 44 may include one or more transmission stages or reduction gears that provide multiple levels of gear reduction, and may optionally include one or more multi-speed transmission stages. Further optionally, a clutch (not shown) may be used between the transmission output and the differential assembly 46 to selectively decouple the differential assembly 46 from the electric motor 42. In the example provided, the transmission 44 includes a drive gear or input pinion 60, a plurality of first reduction gears 62, a plurality of second reduction gears 64, and a driven gear or final drive gear 66. The input pinion 60 may be coupled to the output shaft of the electric motor assembly for rotation therewith. The first reduction gears 62 are meshingly engaged with the input pinion 60 and have more teeth than the input pinion 60 and a pitch diameter relatively larger than the pitch diameter of the input pinion 60. Each of the first reduction gears 62 may be fixedly coupled to an associated one of the second reduction gears 64 to form a compound reduction gear 70. The second reduction gears 64 have a larger pitch diameter and more teeth than the first reduction gear 62. Each of the compound reduction gears 70 may be disposed on an intermediate shaft or axle 72 mounted to the housing 40 for rotation about an offset second axis of rotation 74 parallel to the first axis of rotation 58. Each of the intermediate shafts 72 may be supported by a pair of bearings that may be mounted to the housing 40. It will also be appreciated that each of the intermediate shafts 72 may be formed as a separate component that may be assembled to a corresponding one of the compound reduction gears 70 or may be formed as a unitary, integral piece with a corresponding one of the compound reduction gears 70. The final drive gear 66 may be supported by the housing 40 for rotation about an output shaft 76 that is parallel and offset to the second axis of rotation 74 and the first axis of rotation 58. In the example provided, the input pinion 60, the first reduction gear 62, the second reduction gear 64, and the final drive gear 66 are helical gears, and the first reduction gear 62 and the second reduction gear 64 are counter-rotating to counter the axial forces on the compound reduction gear 70 associated with the transfer of rotational power between the input pinion 60 and the first reduction gear 62, and between the second reduction gear 64 and the final drive gear 66. Although the transmission 44 is described as using helical gears, it will be understood that some or all of these gears may also be configured as spur gears.

3, the differential assembly 46 can include a differential input member and a pair of differential output members. The differential input members can be coupled to the final drive gear 66 for rotation together about the output shaft 76, while each of the differential output members can be coupled for rotation with a corresponding one of the axle shafts 32. In the particular example provided, the differential assembly 46 includes a differential case 80 and a differential gear set 82. The differential case 80 can function as a differential input member and can be supported for rotation on the housing 40 about the output shaft 76 by a pair of bearings 84. The bearings 84 are shown as tapered rolling bearings in the example provided, but it will be understood that the bearings 84 can be configured as angular ball bearings or ball bearings in the alternative. The differential gear set 82 can include a pair of differential pinions 90 and a pair of side gears 92. The differential pinions 90 can be received in the differential case 80 and rotatably disposed on a cross pin 94 attached to the differential case 80. The cross pin 94 can extend at least partially through the differential case 80 and is oriented perpendicular to the output shaft 76. The side gears 92 are the differential output members in the example provided. The side gears 92 are received within the differential case 80 and can rotate relative to the differential case 80 about the output shaft 76. Each of the side gears 92 is meshingly engaged with a differential pinion 90.

[0028] Each of the axle shafts 32 may be non-rotatably but axially slidably engaged to a corresponding one of the side gears 92. In the example provided, each of the axle shafts 32 has a male splined segment 100 that matingly engages an internally splined opening 102 in a corresponding one of the side gears 92. Each of the axle shafts 32 is configured to transmit rotational power between one of the side gears 92 and an associated one of the vehicle wheels.

[0029] The configuration of the transmission 44 is advantageous in several aspects. For example, the compound reduction gear 70 allows the use of a relatively high-speed electric motor and a relatively small input pinion, which reduces the pitch line velocity and therefore has a positive effect on the bending stress, load capacity, and service life of the input pinion 60 and the first reduction gear 62. As another example, the load on the final drive gear 66 can be shared across the second reduction gear 64, reducing the size of the second reduction gear 64 (as opposed to a configuration in which the entire load is transmitted to the final drive gear 66 by a single gear). As a result, the gear mounting configuration between the electric motor 42 and the final drive gear 66 reduces the package size of the drive unit 30, and further, the gears can be formed from relatively smaller and/or less expensive materials than known electric drive unit components, thereby reducing the cost and mass of the electric drive module 24.

[0030] If desired, a parking lock mechanism (not shown) may be incorporated into the electric drive module 24. With reference to Figures 2 and 4, the parking lock mechanism may be configured in a conventional manner with a pawl pivotally coupled to the housing 40 and a toothed locking wheel rotatably coupled to the final drive gear 66 or to a component of the differential assembly 46 that is rotatable about the output shaft 76. The pawl may pivot to engage or disengage teeth on the toothed locking wheel to prevent rotation of the final drive gear 66 relative to the housing 40. Alternatively, the parking lock mechanism may be configured to selectively lock the intermediate shaft 72 to the housing 40. A scissors mechanism, or a see-saw lever mechanism may be used to simultaneously lock the intermediate shaft 72 to the housing 40.

[0031] With reference to Figures 5 through 7, an optional parking lock mechanism 200 may be incorporated into the drive unit 30. The parking lock mechanism 200 may include a pair of parking gears 202, a pawl 204, a pair of plungers 206, a pair of plunger biasing springs 208, and an actuator 210.

[0032] Each of the parking gears 202 may be non-rotatably coupled to an associated one of the intermediate shafts 72 and may define a number of teeth 216 and a number of valleys 218. Each of the valleys 218 is disposed between each pair of the teeth 216.

[0033] The pawl 204 includes a pawl body 220 and a pair of engagement teeth 222 disposed on opposite ends of the pawl body 220. The pawl body 220 is pivotally coupled to the housing 40 of the drive unit 30 such that the pawl 204 may be moved between an engaged position (FIG. 6) in which each of the engagement teeth 222 engages with an associated one of the parking gears 202 (i.e., each engagement tooth 222 is received within a valley 218 of an associated one of the parking gears 202), thereby rotationally locking the parking gears 202 and the intermediate shaft 72 to the housing 40, and a disengaged position (FIG. 8) in which each engagement tooth 222 clears a tooth 216 of an associated one of the parking gears 202 such that the pawl 204 does not prevent rotation of the parking gears 202 or the intermediate shaft 72 relative to the housing 40. In the example provided, a pivot shaft 226 is attached to the housing 40 and extends through the pawl 204 and into the actuator 210. The pawl 204 is somewhat loosely received on the pivot shaft 226 to ensure that loads transmitted through the parking lock mechanism 200 are shared equally by the parking gear 202 as well as by the engagement teeth 222. The pawl 204 can be biased about the pivot shaft 226 toward a desired rotational position, such as a disengaged position. In the example provided, a helical torsion spring 258 is disposed about the pivot shaft 226 and engaged with the housing 40 and the pawl body 220.

[0034] Referring to FIG. 7, each of the plungers 206 can have a plunger body including a guide portion 230, a first body portion 232, a transition portion 234, and a second body portion 236. The guide portion 230 is disposed at a first axial end of the plunger 206 and can be cylindrical in shape with a first diameter. The first body portion 232 is disposed between the guide portion 230 and the transition portion 234 and can be dimensioned as desired. For example, the first body portion 232 can be generally cylindrical in shape with a desired diameter, such as the first diameter. In the example provided, the first body portion 232 is frusto-conical in shape, has a base (where the first body portion 232 intersects with the guide portion 230), has a diameter equal to the first diameter, and has a relatively shallow cone angle that causes the outer surface of the first body portion 232 to taper inwardly toward the central axis of the plunger 206 between the guide portion 230 and the transition portion 234 by a desired amount, such as 2 to 30 degrees, preferably 5 to 15 degrees.

[0035] The second body portion 236 may also be cylindrical in shape, but with a second diameter smaller than the first diameter. The transition portion 234 may be frusto-conical in shape to taper between the first body portion 232 and the second body portion 236. A spring opening 240 is formed in the first axial end of the plunger 206 and is dimensioned to receive a corresponding one of the plunger biasing springs 208 therein. In the example provided, each of the plunger biasing springs 208 is a helical coil compression spring, although it will be understood that other types of springs may be used in place of or in addition to the helical coil compression springs.

[0036] Each plunger 206 and plunger biasing spring 208 is received within a plunger opening 244 in the housing 40. In the illustrated example, the housing 40 includes a pair of optional plunger bushings 246, which may be formed from a suitable material, such as hardened steel. Each of the plunger bushings 246 defines a plunger opening 244 that is dimensioned to receive the first body portion 232 of a corresponding one of the plungers 206 and a corresponding one of the plunger biasing springs 208. The plunger openings 244 may be blind holes, such that the plunger bushings 246 define an inner wall 248 against which an end of the corresponding one of the plunger biasing springs 208 may abut.

[0037] Each of the plungers 206 is movable along its length relative to the housing 40 between an extended position (shown in Figs. 6 and 7) in which the first body portion 232 of each of the plungers 206 is disposed in the rotational path of the pawl body 220, and a retracted position (shown in Figs. 8 and 9). To place the plunger 206 in the extended position, the engagement teeth 222 must be engaged with the parking gear 202. If the outer surface of the first body portion 232 is tapered (frustoconical), the plunger biasing spring 208 urges the plunger 206 outwardly from the plunger opening 244 so that the outer surface of the first body portion 232 of each plunger 206 contacts the pawl body 220. When the plunger 206 is disposed in its retracted position, the pawl 204 can be rotated to a disengaged position by the torsion spring 258. The pawl 204 can contact one or both second body portions 236 of the plunger 206 when the pawl 204 is in the disengaged position.

7 and 10, the actuator 210 is configured to control the movement of the plunger 206 between an extended position and a retracted position. The actuator 210 may include a pair of cam followers 250, an actuator hub 252, a cam plate 254, a bearing 256, a torsion spring 258, a rotation actuator 260, and a lock actuator 262.

7 and 9, each of the cam followers 250 may be disposed in-line with an associated one of the plungers 206. In the example provided, each of the cam followers 250 is unitarily and integrally formed with an associated one of the plungers 206. More specifically, the cam followers 250 may be a spherical radius on a second axial end of the plunger 206 opposite the first axial end.

[0040] The actuator hub 252 may be fixedly coupled to the housing 40 concentrically with the axis about which the pawl 204 pivots. In the example provided, the actuator hub 252 is press-fit to the pivot axle 226. The actuator hub 252 may include a central portion 270, a bearing mount 272, and a lock actuator mount 274. The central portion 270 may define a pivot axle opening 280 aligned along a common axis and a threaded opening 282. The pivot axle opening 280 is formed through a first axial side of the central portion 270 and is dimensioned to engage the pivot axle 226 with a press-fit. The threaded opening 282 is formed through a second, axially opposite side of the central portion 270. The bearing mount 272 may be concentrically disposed about the central portion 270 and coupled to the central portion 270 via a flange member 284 or, alternatively, via a plurality of spokes or webs. The bearing mount 272 has an outer circumferential surface 286, a shoulder 288 extending radially outward from the outer circumferential surface, and a retaining ring groove 290 formed in the outer circumferential surface 286. The lock actuator mount 274, best seen in FIG. 5, may have a kidney (i.e., kidney bean) shape and may be fixedly coupled to (e.g., integrally formed with) the bearing mount 272 such that it is radially offset from the central portion 270.

5, 7, and 11, the cam plate 254 can include an annular plate 300, a gear portion 302, a torsion spring mount 304, and a pair of sensor targets 306a, 306b. The annular plate 300 can be formed from a suitable material. The annular plate 300 can have an inner circumferential surface 310 and can define a pair of cams 312. Each of the cams 312 can be formed into a first face of the annular plate 300 that faces the cam follower 250 and the plunger 206. Each of the cams 312 can be a groove extending circumferentially in the first face of the annular plate 300. Each of the cams 312 can be tapered between a first circumferential end 320 (FIG. 11) of the groove, where the groove is deepest, and a second opposite circumferential end 322 (FIG. 11) of the groove, where the groove is shallowest. Each of the cam followers 250 is received in a corresponding one of the cams 312 (i.e., grooves) and thus produces a corresponding linear motion of the plunger 206 as the cam plate 254 rotates about the axis about which the pawl 204 pivots. More specifically, as shown in FIGURE 7, disposing a cam follower 250 in the deepest portion of the associated one of the cams 312 (i.e., the first circumferential end 320 of the groove forming the associated one of the cams 312) allows the associated one of the plunger biasing springs 208 to urge the associated one of the plungers 206 towards its extended position, whereas, as shown in FIGURE 9, disposing a cam follower 250 in the shallowest portion of the associated one of the cams 312 (i.e., the second circumferential end of the groove forming the associated one of the cams 312) places the associated one of the plungers 206 in its retracted position against the bias of the associated one of the plunger biasing springs 208. The gear portion 302 can include a plurality of gear teeth that can be fixedly coupled to the annular plate 300 such that the gear teeth are concentric with the inner circumferential surface 310. In the example provided, the gear teeth are integrally formed as a single unit with the annular plate 300. The gear teeth can be disposed around the entire circumference of the annular plate 300 as shown in the example provided, or can be formed around a sector of the annular plate 300. The torsion spring mount 304 can be a cylindrical post or protrusion that can extend from a second side of the annular plate 300 opposite the first side. Each of the sensor targets 306a, 306b can be attached to the annular plate 300 and configured to be sensed by a sensor 328 (FIG. 10) when the cam plate 254 is in a predetermined rotational position relative to the housing 40. In the example provided, each of the sensor targets 306a, 306b is a magnet, and the sensor 328 is a Hall effect sensor coupled to the housing 40.

[0042] Referring to FIG. 7, the bearing 256 is configured to support the cam plate 254 for rotation relative to the actuator hub 252. The bearing 256 may include an inner bearing race 330, an outer bearing race 332, and a plurality of bearing elements 334 received between the inner bearing race 330 and the outer bearing race 332. The inner bearing race 330 may be received on the outer circumferential surface 286 of the bearing mount 272 and abut against the shoulder 288. If desired, the inner bearing race 330 may be press fit onto the outer circumferential surface 286 of the bearing mount 272. An outer retaining ring 336 may be received in the retaining ring groove 290 to prevent axial movement of the inner bearing race 330 on the actuator hub 252 away from the shoulder 288. The outer bearing race 332 may be coupled to the cam plate 254 in any desired manner. For example, the outer bearing race 332 may be press-fit or adhesively bonded to the inner circumferential surface 310 of the annular plate 300. Alternatively, in examples where the annular plate is formed from a plastic material, the annular plate 300 may be overmolded with the outer bearing race 332 such that the outer bearing race 332 is cohesively bonded to the annular plate 300.

5 and 7, the torsion spring 258 can have a first tang 340 wound around the central portion 270 and capable of acting against the actuator hub 252 and a second tang 342 capable of acting against a torsion spring mount 304 on the cam plate 254. In the example provided, the first tang 340 is received in a hole formed in the flange member 284. The torsion spring 258 can be secured to the central portion 270 by a washer 346 and by a threaded fastener 348 that threads into a threaded opening 282 in the central portion 270. The torsion spring 258 is configured to rotationally bias the cam plate 254 about its axis of rotation toward a first rotational position, which can be a position that faces the deepest portion of the cam 312 toward the cam follower 250. Alternatively, the torsion spring 258 may be configured to rotationally bias the cam plate 254 about its axis of rotation to a position in which the shallowest portion of the cam 312 is directed toward the cam follower 250.

10, a rotary actuator 260 is configured to control rotation of the cam plate 254 about its axis of rotation between a first rotational position and a second rotational position. The rotary actuator 260 can include a rotary electric motor (not specifically shown) and an output pinion (not specifically shown) that is meshingly engaged with gear teeth of the gear portion 302 of the cam plate 254. The electric motor can be coupled (e.g., mounted) to the housing 40. The output pinion can be driven by the electric motor either directly (e.g., the output pinion is mounted on an output shaft of the electric motor) or through a transmission (not shown) having one or more gears (not shown) disposed in a power transmission path between the electric motor and the output pinion.

[0045] The electric motor may be operated to drive the cam plate 254 to a second rotational position, which may be a position that is directed toward the opposite circumferential end of the cam 312, such as the shallowest portion of the cam 312, relative to the cam follower 250. In some forms, the electric motor may be used to drive the cam plate 254 to a desired rotational position and then hold the cam plate 254 in this rotational position. Optionally, the cam plate 254 may be configured with a stop member (not shown) that abuts a mating stop member (not shown) coupled to the housing 40 when the electric motor rotates or drives the cam plate 254 to the desired rotational position. However, in the example provided, the sensor target 306b, the sensor 328, and the lock actuator 262 are used to maintain the cam plate 254 in the desired rotational position, such that power to the electric motor does not need to be maintained.

[0046] Placement of the cam plate 254 in each of the first and second rotational positions can be sensed by a sensor 328, which can generate a corresponding sensor signal in response. For example, placing the cam plate 254 in the first rotational position orients the sensor target 306a toward the sensor 328, which in response generates a first sensor signal, while placing the cam plate 254 in the second rotational position orients the sensor target 306b toward the sensor 328, which in response generates a second sensor signal. In response to receiving the second sensor signal, a controller (not shown) can control the lock actuator 262 to engage the lock actuator 262 with the cam plate 254 to prevent rotation of the cam plate 254 out of the second rotational position (i.e., due to a moment applied to the cam plate 254 by the torsion spring 258).

10 and 12, the lock actuator 262 may include any means for preventing rotation of the cam plate 254 relative to the housing 40. In the example provided, the lock actuator 262 includes a solenoid assembly 400 and a lock opening 402. The solenoid assembly 400 may be coupled to the housing 40 and may include a solenoid 410, a solenoid plunger 412, and a solenoid spring 414. The solenoid plunger 412 is movable within the solenoid 410 between an extended or latched position and a retracted or unlatched position. The solenoid spring 414 biases the solenoid plunger 412 to the extended or latched position. The lock opening 402 is formed in a second surface of the annular plate 300 and is configured to receive the solenoid plunger 412 therein when the cam plate 254 is in the second rotational position. In the illustrated example, the solenoid plunger 412 has a tip 420 defined by a spherical radius, and the lock opening 402 has a frusto-conical sidewall 422. The contours of the tip 420 of the solenoid plunger 412 and the contours of the sidewall 422 of the lock opening 402 cause the solenoid plunger 412 to be driven toward a retracted or unlatched position by the torsion spring 258 when power is not provided to the solenoid 410 or electric motor.

5, 7, and 12, during operation of the drive unit 30, when power is not provided to the electric motor or solenoid 410, the torsion spring 258 biases the cam plate 254 to a first rotational position in which the deepest portion of the cam 312 is aligned with the cam follower 250, as shown in FIG. 7, and thus the plunger 206 is positioned in its extended position with the first body portion 232 contacting the pawl body 220 and the pawl 204 positioned about the pivot axis 226 with the engagement teeth 222 engaging the parking gear 202, as shown in FIG. 6. In this state, the intermediate shaft 72 is effectively non-rotatably locked relative to the housing 40, and due to the configuration of the parking lock mechanism 200, the loads transmitted by each engagement tooth 222 and each parking gear 202 are equal. In this state, the sensor target 306a is aligned with the sensor 328, which in response generates a first sensor signal. The first sensor signal can be received by a control device (not shown) and used to determine that the cam plate 254 is in a rotational position, which causes the parking lock mechanism 200 to lock the intermediate shaft 72 relative to the housing 40. The solenoid spring 414 of the lock actuator 262 biases the tip 420 of the solenoid plunger 412 against the second surface of the annular plate 300.

[0049] To unlock the intermediate shaft 72 from the housing 40 so that the intermediate shaft 72 can rotate relative to the housing 40, power can be applied to the electric motor to drive the output pinion to rotate the cam plate 254 in a corresponding first rotational direction about its axis of rotation. As shown in FIG. 9, rotation of the cam plate 254 in a second rotational direction moves the plunger 206 from its extended position to its retracted position, gradually aligning the cam follower 250 with the shallower portion of the groove or cam 312. Due to the tapered configuration of the first body portion 232 and the transition portion 234 of the plunger 206, and the moment applied to the pawl 204 by the torsion spring 258, the engagement teeth 222 are gradually moved away from the teeth 216 of the parking gear 202 as the plunger 206 gradually moves toward its retracted position. 8 and 9, placement of the pawl 204 in contact with the second body portion 236 of the plunger 206 positions the engagement tooth 222 away from the parking gear 202 in a position that allows the parking gear 202, and therefore the intermediate shaft 72, to freely rotate relative to the housing 40. Further rotation of the cam plate 254 in the first rotational direction positions the cam plate 254 in a second rotational position that orients the sensor target 306b toward the sensor 328, which in response generates a second sensor signal. In response to receiving the second sensor signal, the controller can provide power to the solenoid 410 to drive the solenoid plunger 412 into the lock opening 402 and hold the solenoid plunger 412 in this position. Optionally, the controller can also terminate the supply of power to the motor. The moment exerted on the cam plate 254 by the torsion spring 258 to urge the cam plate 254 toward the first rotational position is insufficient to urge the solenoid plunger 412 out of the lock opening 402 when power is supplied to the solenoid 410.

[0050] Power is terminated to relock the intermediate shaft 72 relative to the housing 40 and prevent rotation of the intermediate shaft 72 relative to the housing 40. The moment exerted on the cam plate 254 by the torsion spring 258 is sufficient to overcome the force exerted on the solenoid plunger 412 by the solenoid spring 414 to urge the cam plate 254 toward the first rotational position, forcing the solenoid plunger 412 out of the locking opening 402. The moment exerted on the cam plate 254 by the torsion spring 258 rotates the cam plate 254 in a second rotational direction opposite the first rotational direction. Once the cam plate 254 has rotated toward and into the first rotational position, the rotation of the cam plate 254 in the second rotational direction can cause the gear teeth of the gear portion 302 to back drive the output pinion. Rotation of the cam plate 254 in the second rotational direction also gradually aligns the deeper portion of the groove or cam 312 relative to the cam follower 250, moving the plunger 206 from its retracted position to its extended position. Due to the tapered configuration of the transition portion 234 and the first body portion 232 of each of the plungers 206, when the cam plate 254 is rotated in the second rotational direction, contact between the pawl body 220 and the plunger 206 drives the pawl 204 about the pivot axis 226, thus causing the engagement tooth 222 to rotate towards its respective parking gear 202. The engagement tooth 222 can move directly into the valley 218 of the parking gear 202 in situations where the parking gear 202 is oriented in the receiving position. In other situations, movement of the engagement tooth 222 into the valley 218 can be blocked because the parking gear 202 is oriented in a position where each engagement tooth 222 contacts a tooth of an associated one of the parking gears 202. However, the plunger biasing spring 208 provides compliance to drive the plunger 206 to its extended position when the intermediate shaft 72 is rotated slightly (the outer surface of the first body portion 232 engages the pawl 204, thereby driving the engagement tooth 222 into engagement with the parking gear 202).

[0051] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, and where applicable, even if not specifically shown or mentioned, can be interchangeable and used in selected embodiments. The present disclosure can also be modified in many ways. Such modifications should not be considered as a departure from the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.
The invention as originally claimed in the present application is set forth below.
[1] An electric drive module (24), comprising:
An electric motor (42);
A differential assembly (46);
a transmission (44) for transmitting rotational power between the electric motor (42) and the differential assembly (46); the transmission (44) including a first reduction gear and a second reduction gear, the first reduction gear having a drive gear (60) and a pair of first reduction gears (62), the drive gear (60) rotatable about a first shaft (58), each of the first reduction gears (62) being meshingly engaged with the drive gear (60) and rotatable about a respective second shaft (74); wherein the second shafts (74) are spaced apart from one another and parallel to the first shaft (58), the second reducer has a driven gear (66) and a pair of second reduction gears (64), the driven gears (66) are rotatable about a third shaft (76) parallel to the first shaft (58), and each of the second reduction gears (64) is meshingly engaged with the driven gear (66) and non-rotatably coupled to an associated one of the first reduction gears (62).
an electric drive module (24).
[2] The electric drive module (24) of [1], wherein the electric motor (42) includes an output shaft (56), and the drive gear (60) is coupled to the output shaft (56) for rotation therewith about the first axis (58).
[3] The electric drive module (24) of [2], wherein the differential assembly (46) includes a differential input member (80), and the driven gears (66) are coupled to the differential input member (80) for common rotation about the third axis (76).
The electric drive module (24) of any one of claims 1 to 4, wherein the differential assembly (46) includes a differential gear set (82).
The electric drive module (24) of any one of claims 1 to 4, wherein the differential gear set (82) comprises a plurality of differential pinions (90) meshingly engaged with a pair of side gears (92).
[6] The electric drive module (24) of [5], wherein a pair of the differential pinions (90) are attached to a cross pin (94) attached to the differential input member (80).
[7] The electric drive module (24) of [1], wherein the differential assembly (46) includes a differential input member (80), and the driven gears (66) are coupled to the differential input member (80) for common rotation about the third axis (76).
The electric drive module (24) of any one of claims 1 to 7, wherein the differential assembly (46) includes a differential gear set (82).
The electric drive module (24) of any one of claims 1 to 5, wherein the differential gear set (82) comprises a plurality of differential pinions (90) meshingly engaged with a pair of side gears (92).
[10] The electric drive module (24) of [9], wherein a pair of the differential pinions (90) are attached to a cross pin (94) attached to the differential input member (80).
[11] a housing (40) in which the transmission (44) and the differential assembly (46) are received;
a pair of parking gears (202), each of said parking gears (202) being non-rotatably coupled to an associated one of said second reduction gears (64);
a pawl (204) having a pair of engagement teeth (222), said pawl (204) coupled to said housing (40) and pivotable between an engagement position in which each of said engagement teeth (222) engages a corresponding one of said parking gear (202) and a disengagement position in which said engagement teeth (222) are disengaged from said parking gear (202);
a pair of plungers (206) movable between a first position and a second position, each of said plungers (206) having a first body portion (232) and a second body portion (236) having a smaller diameter than said first body portion (232), wherein contact between said first body portion (232) of said plunger (206) and said pawl (204) positions said pawl (204) in said engaged position, and wherein when said second body portion (236) of said plunger (206) contacts said pawl (204), said pawl (204) is disposed in said disengaged position;
The electric drive module (24) of [1] further comprises:
[12] The electric drive module (24) of [11], wherein when the pawl (204) is in the engaged position, a first load transferred between a first one of the engagement teeth (222) and a first one of the parking gears (202) is equal to a second load transferred between a second one of the engagement teeth (222) and a second one of the parking gears (202).
[13] The electric drive module (24) of [11], wherein the pawl (204) is pivotally disposed on a pivot shaft (226), and an engagement between the pawl (204) and the pivot shaft (226) allows non-rotational movement of the pawl (204) relative to the pivot shaft (226) such that loads transmitted between the engagement teeth (222) and the parking gear (202) are equal.
[14] The electric drive module (24) of [11], wherein the first body portion (232) of the plunger (206) is frustoconical in shape.
[15] The electric drive module (24) of [14], wherein each plunger (206) further comprises a transition portion (234) disposed between the first body portion (232) and the second body portion (236), the transition portion (234) having a frusto-conical shape, and a cone angle of the first body portion (232) being smaller than a cone angle of the transition portion (234).
[16] The electric drive module (24) of [11], further comprising an actuator (210) for controlling movement of the plunger (206) between the first position and the second position, the actuator (210) comprising an actuator hub (252), a cam plate (254) and a plurality of cam followers (250), the actuator hub (252) coupled to the housing (40), the cam plate (254) rotatable about the actuator hub (252) and defining a pair of cams (312), each of the cams (312) being a circumferentially extending groove having a tapered depth between a first circumferential end (320) and a second circumferential end (322), each of the cam followers (250) being received in a corresponding one of the cams (312) and aligned with an associated one of the plunger (206).
[17] The electric drive module (24) of [16], wherein each of the cam followers (250) is fixedly engaged to the associated one of the plungers (206).
[18] The electric drive module (24) of [16], wherein the actuator (210) further includes a torsion spring (258) disposed between the actuator hub (252) and the cam plate (254), the torsion spring (258) biasing the cam plate (254) toward a first rotational position relative to the actuator hub (252).
[19] The electric drive module (24) of [16], wherein the actuator (210) further includes a lock actuator (262), the lock actuator (262) having a solenoid assembly (400) and a lock opening (402), the solenoid assembly (400) having a solenoid plunger (412), the lock opening (402) formed in the cam plate (254), the solenoid assembly (400) being biased to receive the solenoid plunger (412) into the lock opening (402) and engage the cam plate (254) when the cam plate (254) is rotated to a rotational position that aligns the second circumferential end (322) of the cam (312) with the cam follower (250).
[20] The electric drive module (24) of [16], wherein a bearing (256) is radially disposed between the actuator hub (252) and the cam plate (254).

Claims (16)

An electric drive module (24),
an electric motor (42) having a motor output shaft (56);
A driven gear (66);
a differential assembly (46) driven by said driven gear (66);
a transmission (44) for transmitting rotational power between the electric motor (42) and the driven gear (66) ;
The transmission (44) includes a drive gear (60), a pair of first reduction gears (62), and a pair of second reduction gears (64), the drive gear (60) coupled to the motor output shaft (56) for rotation therewith about a first axis (58), each of the first reduction gears (62) meshingly engaged with the drive gear (60) and rotatable about a respective second axis (74), wherein the respective second axes (74) are spaced apart from one another and parallel to the first axis (58), each of the second reduction gears (64) meshingly engaged with the driven gear (66) and non-rotatably coupled to a corresponding one of the first reduction gears (62),
An electric drive module (24), wherein the driven gear (66) is rotatable about a third axis (76) that is not coaxial with the motor output shaft (56). The electric drive module (24) of claim 1, wherein the differential assembly (46) includes a differential input member (80) and the driven gears (66) are coupled to the differential input member (80) for common rotation about the third axis (76). The electric drive module (24) of claim 2, wherein the differential assembly (46) includes a differential gear set (82). The electric drive module (24) of claim 3, wherein the differential gear set (82) comprises a plurality of differential pinions (90) meshingly engaged with a pair of side gears (92). The electric drive module (24) of claim 4, wherein a pair of the differential pinions (90) are attached to a cross pin (94) attached to the differential input member (80). a housing (40) in which the transmission (44) and the differential assembly (46) are received;
a pair of parking gears (202), a pawl (204) having a pair of engagement teeth (222), and a pair of plungers (206) movable between a first position and a second position;
Each of the parking gears (202) is non-rotatably coupled to a corresponding one of the second reduction gears (64);
the pawl (204) is coupled to the housing (40) and is pivotable between an engaged position in which each of the engagement teeth (222) engages a corresponding one of the parking gear (202) and a disengaged position in which the engagement teeth (222) disengage from the parking gear (202) ;
2. The electric drive module of claim 1, wherein each of the plungers has a first body portion and a second body portion having a smaller diameter than the first body portion, wherein contact between the first body portion of the plunger and the pawl positions the pawl in the engaged position, and wherein when the second body portion of the plunger contacts the pawl, the pawl is disposed in the disengaged position . The electric drive module (24) of claim 6, wherein when the pawl (204) is in the engaged position, a first load transferred between a first one of the engagement teeth (222) and a first one of the parking gears (202) is equal to a second load transferred between a second one of the engagement teeth (222) and a second one of the parking gears (202). The electric drive module (24) of claim 6, wherein the pawl (204) is pivotally disposed on a pivot shaft (226), and the engagement between the pawl (204) and the pivot shaft (226) allows non-rotational movement of the pawl (204) relative to the pivot shaft (226) such that the loads transmitted between the engagement teeth (222) and the parking gear (202) are equal. The electric drive module (24) of claim 6, wherein the first body portion (232) of the plunger (206) is frustoconical in shape. The electric drive module (24) of claim 9, wherein each plunger (206) further comprises a transition portion (234) disposed between the first body portion (232) and the second body portion (236), the transition portion (234) being frustoconical in shape, and the cone angle of the first body portion (232) being smaller than the cone angle of the transition portion (234). The electric drive module (24) of claim 6, further comprising an actuator (210) for controlling movement of the plunger (206) between the first position and the second position, the actuator (210) comprising an actuator hub (252), a cam plate (254), and a plurality of cam followers (250), the actuator hub (252) coupled to the housing (40), the cam plate (254) rotatable about the actuator hub (252), and defining a pair of cams (312), each of the cams (312) being a circumferentially extending groove having a tapered depth between a first circumferential end (320) and a second circumferential end (322), each of the cam followers (250) being received in a corresponding one of the cams (312) and aligned with a corresponding one of the plunger (206). The electric drive module (24) of claim 11, wherein each of the cam followers (250) is fixedly engaged with the corresponding one of the plungers (206). The electric drive module (24) of claim 11, wherein the actuator (210) further includes a torsion spring (258) disposed between the actuator hub (252) and the cam plate (254), the torsion spring (258) biasing the cam plate (254) toward a first rotational position relative to the actuator hub (252). 12. The electric drive module (24) of claim 11, further comprising a lock actuator (262), the lock actuator (262) having a solenoid assembly (400) and a lock opening (402), the solenoid assembly (400) having a solenoid plunger (412), the lock opening (402) formed in the cam plate (254), the solenoid assembly (400) being biased to receive the solenoid plunger (412) into the lock opening (402) and engage the cam plate (254) when the cam plate (254) is rotated to a rotational position that aligns the second circumferential end (322) of the cam (312) with the cam follower (250). The electric drive module (24) of claim 11, wherein a bearing (256) is disposed radially between the actuator hub (252) and the cam plate (254). The electric drive module (24) of claim 1, wherein the third axis (76) is parallel to the first axis (58).

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