WO2024102470A1 - Drivetrain disconnect assembly utilizing screw-type actuator - Google Patents

Abstract

A disconnect assembly is operative alternatively to connect and disconnect a first rotating element (e.g., shaft) and a second rotating element (e.g., shaft). The disconnect assembly comprises a coupler slidably mounted with respect to the first rotating element so as to rotate with the first rotating element. The second rotating element has a clutch feature adjacent to the first rotating element that can be engaged by the coupler. The coupler is slidably movable between a disconnected position in which the coupler is rotatable only with the first rotating element and a connected position in which the coupler connects the first rotating element and the second rotating element for rotation together. A screw-type actuator is connected to the coupler to move the coupler between the disconnected position and the connected position.

Description

TITLE

DRIVETRAIN DISCONNECT ASSEMBLY UTILIZING SCREW-TYPE ACTUATOR

PRIORITY CLAIM

[0001] This application is based upon and claims priority to U.S. provisional patent application no. 63/424711, filed November 11, 2022 and titled “Drivetrain Disconnect Assembly with a Lead Screw Driver Collar.” The aforementioned application is incorporated fully herein by reference for all purposes.

FIELD OF THE INVENTION

[0002] The present invention relates generally to drivetrains of vehicles and, more particularly, to disconnect assemblies for engaging and disengaging the wheels thereof.

BACKGROUND OF THE INVENTION

[0003] Mechanisms for selectively engaging and disengaging drive axles from the wheels of the corresponding vehicles are known in the art. For example, basic concepts may include mechanisms in which multiple drive axles are utilized in the drivetrain on a continuous, or full- time, basis. For various reasons, drivetrains in which additional drive axles may be engaged and disengaged as necessary, or as desired, have grown in popularity in recent years. For example, known mechanisms allow a user to engage manually a vehicle’s drivetrain to the wheels, which typically require the user to exit to accomplish the manual engagement. In addition, automated systems are known in which a vehicle’s control system automatically engages and disengages the drivetrain from wheels dependent upon the driving conditions. Such mechanisms, however, often include numerous, intricate components and may, therefore, be complicated and costly to manufacture, as well as maintain.

[0004] The present invention recognizes and addresses considerations of prior art constructions and methods.

SUMMARY OF THE INVENTION

[0005] One aspect of the present invention provides a disconnect assembly operative alternatively to connect and disconnect a first rotating element (e.g., shaft) and a second rotating element (e.g., shaft). The disconnect assembly comprises a coupler slidably mounted with respect to the first rotating element so as to rotate with the first rotating element. The second rotating element has a clutch feature adjacent to the first rotating element that can be engaged by the coupler. The coupler is slidably movable between a disconnected position in which the coupler is rotatable only with the first rotating element and a connected position in which the coupler connects the first rotating element and the second rotating element for rotation together. A screwtype actuator is connected to the coupler to move the coupler between the disconnected position and the connected position.

[0006] In some exemplary embodiments, a linkage connects the screw-type actuator to the coupler, the linkage being configured to translate rotational motion of the screw-type actuator to axial motion of the coupler between the disconnected position and the connected position. For example, the screw-type actuator may comprise a nonrotatable nut mounted on a threaded portion of a rotatable spindle, the nut moving axially in first and second directions depending on a rotational direction of the rotatable spindle. In some exemplary embodiments, the linkage may include an arm member that is moved axially by rotation of the nut, the arm member being connected to the coupler. The arm member in such embodiments may comprise a fork element having an arcuate portion at a distal end thereof, the arcuate portion engaging the coupler. The coupler may define an annular- groove about an outer circumferential surface thereof, the arcuate portion of the fork element being seated in the annular groove.

[0007] In some exemplary embodiments, the coupler may have an annular configuration defining axial coupler splines on an inner circumferential surface thereof. The first rotating element may define axial first element splines on an outer circumferential surface thereof, the coupler splines and the first element splines being in engagement in both the disconnected position and the connected position. In addition, the second rotating element may define axial second element splines on an outer circumferential surface thereof forming the clutch feature, the coupler splines and the second element splines being in engagement in the connected position. [0008] In some exemplary embodiments, the screw type actuator comprises a rotatable spindle having a threaded portion. A nonrotatable nut may be mounted on the threaded portion, the nut moving axially in first and second directions depending on a rotational direction of the rotatable spindle. A motor, operative to rotate the spindle in a first direction and an opposite second direction, may also be provided.

[0009] In some exemplary embodiments, a position sensing arrangement may be provided to determine an axial position of the coupler. For example, the position sensing arrangement may be operative to detect an axial position of the nut such that the axial position of the coupler can be determined. The position sensing arrangement in some embodiments may comprise at least one magnetic sensor device.

[0010] In some exemplary embodiments, the disconnect assembly may further comprise a transition element connected to a distal side of the nut and a fork element connected to the transition element, the fork element being connected to the coupler to axially move the coupler. The transition element extender may define an axial bore aligned with the threaded portion of the spindle to accommodate the threaded portion of the spindle during axial movement of the nut. [0011] Another aspect of the present invention provides a disconnect assembly operative alternatively to connect and disconnect a first rotating element and a second rotating element. The disconnect assembly according to this aspect comprises a coupler having an annular configuration defining axial coupler splines on an inner circumferential surface thereof. The first rotating element defines axial first element splines on an outer circumferential surface thereof. The second rotating element defines axial second element splines on an outer circumferential surface thereof. The coupler is slidably movable between a disconnected position in which the coupler splines and the first element splines are in engagement such that the coupler rotates only with the first element and a connected position in which the coupler splines are in engagement with both the first element splines and the second element splines. A lead- screw actuator has a nonrotatable nut mounted on a threaded portion of a rotatable spindle, the nut moving axially in first and second directions depending on a rotational direction of the rotatable spindle. A linkage connects the nut to the coupler such that the coupler moves between the disconnected position and the connected position.

[0012] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the disclosure and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the ail, is set forth in the specification, which makes reference to the appended drawings, in which; [0014] Figure 1 is a diagrammatic partial cross-sectional view of a drivetrain assembly including a disconnect in accordance with an embodiment of the present invention;

[0015] Figure 2 is an elevational view of an exemplary fork element (shift fork) that may be used in the embodiment of Figure 1 ; and

[0016] Figures 3 and 4 are side cross-sectional views showing aspects of an exemplary disconnect assembly in accordance with the present invention in the disconnected position and connected position, respectively.

[0017] Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention according to the disclosure.

DETAILED DESCRIPTION

[0018] Reference will now be made in detail to presently preferred embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation, not limitation, of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope and spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0019] As used herein, terms referring to a direction or a position relative to the orientation of the drivetrain disconnect assembly, such as but not limited to “vertical,” “horizontal,” “top,” “bottom,” “above,” or “below,” refer to directions and relative positions with respect to the drivetrain disconnect assembly’s orientation shown in Figure 1. Thus, for instance. the terms “vertical” and “top” refer to the vertical orientation and relative upper position in the perspective of Figure 1 , and should be understood in that context, even with respect to a drivetrain wheel-end disconnect assembly that may be disposed in a different orientation.

[0020] Further, the term “or” as used in this disclosure and/or the appended claims is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise, or clear from the context, the phrase “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, the phrase “X employs A or B” is satisfied by any of the following instances: X employs A; X employs B; or X employs both A and B. The meaning of “a,” “an,” and “the” may include plural references, and the meaning of “in” may include “in” and “on.” The phrase “in one embodiment,” as used herein does not necessarily refer to the same embodiment, although it may.

[0021] Figure 1 is a diagrammatic illustration of a partial drivetrain 10 including a disconnect assembly 12 in accordance with aspects of the invention. The disconnect assembly 12 is utilized to selectively connect a source of motive power (e.g., an internal combustion engine or electric motor) to a wheel. Specifically, drivetrain 10 includes an input shaft 14 which is rotationally driven by the source of motive power, e.g., through a transmission, differential gear set, etc. An output shaft 16 is connected to the wheel such that the output shaft 16 and the wheel rotate together. Disconnect assembly 12 functions to rotationally connect shafts 14 and 16 so that they rotate together when the disconnect assembly 12 is in a connected (engaged) position to allow the transmission of torque to the wheel (or to allow regenerative braking in the case of an electric vehicle). When the disconnect assembly 12 is in a disconnected (disengaged) position, the shafts 14 and 16 are able to rotate independently. Typically, output shaft 16 will thus rotate at wheel speed. [0022] Shafts 14 and 16 may be rotatably supported by one or more bearings such as those illustrated at 18a-b and 20a-b. In some embodiments, a first one of the shafts may be directly rotatably supported by stationary structure, such as a gearbox housing, while the second shaft may be rotatably supported by the first shaft or a third shaft. In other embodiments, both of the shafts 14 and 16 may be directly rotatably supported by stationary structure.

[0023] In this simplified illustration, shafts 14 and 16 are shown as basic straight shafts, although one skilled in the art will appreciate that one or both of the shafts may take a variety of different configurations depending on the specific application. For example, one or both of the shafts may be configured as hubs and/or may have various configurations of flanges to allow connection of other components. Moreover, in some embodiments, it is contemplated that the “shaft” may comprise a ring gear, e.g., a ring gear in a differential, etc., that can be selectively connected and disconnected from one or more output shafts according to aspects of the present invention. The term “shaft” as used herein thus includes various rotatable elements such as hubs as well as gears that are connected to a shaft via intermediate gears.

[0024] As shown, the disconnect assembly 12 includes an input shaft gear 22 that is non- rotatably fixed to a distal end of the input shaft 14. An output shaft gear 24 is non-rotatably fixed to the proximal end of the output shaft 16. As can be seen, shaft gears 22 and 24 are located adjacent to one another and will rotate with their associated shaft about a common axis A.

[0025] Disconnect assembly 12 utilizes an axially movable coupler 26 that selectively connects shafts 14 and 16 together. Specifically, coupler 26 can be shifted to the connected position when it is desired for shafts 14 and 16 to be rotated together and shifted to the disconnected position when it is desired for shafts 14 and 16 to rotate independently. As one skilled in the art will appreciate, coupler 26 can take a variety of forms depending on the exigencies of a particular application. For example, in some embodiments, coupler 26 may be configured as a friction clutch. In this case, however, coupler 26 is configured as a form of dog clutch.

[0026] Referring now also to Figures 3 and 4, coupler 26 is configured in this embodiment as an annular structure having a series of axial splines 28 on its inner circumferential surface. As shown in Figure 1, both the input shaft gear 22 and the output shaft gear 24 respectively include pluralities of external axial splines 30 and 32 about their outer circumferential surfaces. In this embodiment, splines 28, 30, and 32 are configured as straight splines extending parallel to each other and to axis A. Coupler 26 is axially movable (as shown by arrow B) between a disconnected position (Figure 3) in which splines 26 engage only splines 30 and a connected position (Figures 1 and 4) in which splines 26 simultaneously engage splines 30 and 32.

[0027] A suitable linkage 34 and actuator 36 is provided to move collar 26 between the disconnected and connected positions. In this embodiment, linkage 34 includes an arm member 38 that pushes and pulls coupler 26 so as to move coupler 26 between the connected and disconnected positions. Referring now to Figure 2, arm member 38 is configured as a fork element having intermediate elongate portion 40 with a connection structure 42 at its proximal end. Connection structure 42 is configured to facilitate connection of arm member 38 to the actuator 36. In this case, for example, connection structure 42 has a ring-like configuration. An arcuate portion 44, which is in this case approximately semicircular, is located at the distal end of the elongate portion 40.

[0028] As is apparent from Figures 1, 3, and 4, arcuate portion 44 is received in an annular channel 46 defined in the outer circumferential surface of coupler 26. It will be appreciated that the centerline of channel 46 lies in a plane that is perpendicular to axis A. Because of this configuration, coupler 26 is allowed to rotate with one or both of shafts 14 and 16 but arm member 38 remains rotatably fixed. However, movement of arm member 38 back and forth by actuator 36 causes coupler 26 to shift between connected and disconnected positions. Note, in alternate embodiments, the outer perimeter of the coupler 26 may be received in an annular groove formed on an inside surface of the arcuate portion 44.

[0029] Referring now to Figures 1, 3, and 4, actuator 36 is operative to cause the reciprocating movement of arm member 38, and thus coupler 26. In this case, actuator 36 is a configured as a screw-type actuator in which rotational but axially stationary movement of one element causes axial movement of another element that is rotationally stationary. For example, actuator 36 may comprise a ball screw actuator. In this embodiment, however, actuator 36 comprises a lead screw actuator in which an electric motor 48 (e.g., a DC motor) is operative to rotate an axially stationary spindle 50 that extends beyond the motor 48. Spindle 50 has a threaded portion 52 extending along a portion of its length that is outside of the motor 48. (As shown in Figures 3 and 4, the threaded portion 52 may be formed by a separate element attached to the remainder of spindle 50 in some exemplary embodiments.)

[0030] A nut 54 having a threaded inner circumferential surface is received on the threaded portion 52 of spindle 50. The distal side of nut 54 is connected to a transition element 56 such that nut 54 will not rotate as spindle 50 is rotated by the motor 48. As a result, rotation of spindle 50 (as indicated by arrow C) causes axial movement of nut 54 and transition clement 56. The direction of rotation determines the axial direction in which nut 54 and transition element 56 reciprocate. [0031] As shown, transition element 56 defines a blind bore 58 in which the distal end of threaded portion 52 is located. The degree to which threaded portion 52 extends into blind bore 58 depends on the axial position of nut 54. Blind bore 58 thus provides clearance for the end of threaded portion 52 so that nut 54 can move axially, as desired.

[0032] The distal end of transition element 56 is fixedly connected to connection structure of arm member 38. As can be seen, transition element 56 may have a nub 60 that is received in a hole defined in connection structure 42. Connection structure 42 may itself have a boss 62 circumscribing the hole to provide enhanced strength and/or rigidity at this location. Arm member 38 and transition element 56 may be secured together by any suitable means, such as press fit, adhesive, welding, etc.

[0033] A screw-type actuator advantageously provides an arrangement in which the position of the nut 54, and thus the coupler 26, may inherently remain in a stable position when power to the motor 48 is not present. As a result, it is not necessary in such embodiments to continuously power the actuator in order to maintain the connected and disconnected positions. In addition, a position sensing arrangement (“PS”) 64 can be provided to detect the axial position of the coupler 26. For example, position sensing arrangement 64 may be configured to detect the axial position of nut 54, thus giving an indication of whether coupler 26 is in a fully disconnected position, a fully connected position, or a position in between.

[0034] Position sensing arrangement 64 may utilize any suitable sensing arrangement (i.c. , combination of one or more sensor devices and appropriate circuitry) operative to determine the position of coupler 26. For example, the one or more sensor devices may include one or more magnetic sensor devices (e.g., linear or triaxial hall effect), inductive/eddy-current based, or other, one or more optical sensors, etc. In one preferred embodiment, position sensing arrangement 64 may include one or more hall effect devices that detect proximity of one or more permanent magnets fixed to the exterior of nut 54. Position sensing arrangement 64 may provide its signal output to a control system 66, which may be integrated into or separate from the vehicle’s control system. In any event, position sensing arrangement 64 provides feedback for the application of power (amount and/or polarity) to the motor 48. One skilled in the art will appreciate that control system 66 may include one or more electronic processors (whether referred to as a processor, controller, logic unit, or other similar terms) and memory programmed to execute instructions to perform the desired functions. A suitable electrical connector 68 for providing signal and power connections is shown in Figures 3 and 4.

[0035] Operation of the disconnect assembly 12 will now be described. When viewing spindle 50 on-end from the wheel side of the drivetrain assembly 10, rotation of the lead screw 50 in the counter-clockwise (CCW) direction causes the nut 54 and, therefore, arm member 38 to move inwardly away from the wheel end. As a result, coupler 26 will be in the disconnected position. In the disconnected position, coupler 26 will rotate with input shaft 14 but output shaft 16 is free to rotate independently (e.g., at wheel speed).

[0036] Conversely, rotation of the spindle 50 in the clockwise (CW) direction when viewed from the wheel end causes the nut 54 and, therefore, the arm member 38 to move outwardly toward the wheel end. As a result, coupler 26 will be in the connected position. In the connected state, shafts 14 and 16 rotate together due to the engagement of splines 28 with both of splines 30 and 32.

[0037] Thus, when the disconnected state is required, control system 66 activates motor 48 to rotate spindle 50 in the CCW direction. Preferably, the motor current is proportional to the required force and allows “shaping” of the motion profile. This may advantageously minimize power consumption, mitigate noise, vibration and harshness, etc. As the spindle 50 rotates in the CCW direction, the nut 54 and, therefore, arm member 38 and attached coupler 26, move axially inwardly until the coupler 26 is disengaged from the output shaft gear 24. Once the move is completed, the output shaft 16 is fully decoupled from the input shaft 14 and is free to rotate with the wheel. The input shaft 14 can be turned off to save power for the system, which ultimately leads to battery savings and increased vehicle range.

[0038] In the disconnected state, the coupler 26 is held in an inboard position by the arm member 38. In the inboard position, the internal splines 28 of the coupler 26 engage only the external splines 30 of the input shaft gear- 22. In this position, the coupler 26 rotates in unison with the input shaft gear 22, both of which rotate independently of the output shaft gear 24 and corresponding output shaft 16. In short, the input shaft 14 and the output shaft 16 are free to rotate independently of each other as there is no torque applied from the source of motive power to the wheel.

[0039] To reconnect the output shaft 16 to the input shaft 14, the input shaft 14 is preferably spun to match the speed of the output shaft 16 as closely as possible. Then, the control system 66 activates the motor 48 to rotate the spindle 50 in the CW direction. (For example, the polarity of the current to the motor may be reversed to produce rotation in the opposite direction.) As such, the nut 54 moves axially-outwardly along the threaded portion 52 until the coupler 26 engages the output shaft gear 24 while still engaging the input shaft gear 22. With the splines 28 in engagement with both splines 30 of input shaft gear 22 and splines 32 of output shaft gear 24, torque may be transferred from the source of motive power to the wheel (and torque for regenerative braking may be transmitted back toward input shaft 14). [0040] It can thus be seen that the present invention provides a novel disconnect assembly for use in a vehicle drivetrain. While one or more preferred embodiments of the invention are described above, it should be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit thereof.

Claims

CLAIMS What is claimed is;

1. A disconnect assembly operative alternatively to connect and disconnect a first rotating element and a second rotating element, the disconnect assembly comprising: a coupler slidably mounted with respect to the first rotating element so as to rotate with the first rotating element; the second rotating element having a clutch feature adjacent to the first rotating element that can be engaged by the coupler; the coupler slidably movable between a disconnected position in which the coupler is rotatable only with the first rotating element and a connected position in which the coupler connects the first rotating element and the second rotating element for rotation together; and a screw-type actuator connected to the coupler to move the coupler between the disconnected position and the connected position.

2. The disconnect assembly of claim 1, further comprising a linkage connecting the screwtype actuator to the coupler, the linkage being configured to translate rotational motion of the screw-type actuator to axial motion of the coupler between the disconnected position and the connected position.

3. The disconnect assembly of claim 2, wherein the screw-type actuator comprises a nonrotatable nut mounted on a threaded portion of a rotatable spindle, the nut moving axially in first and second directions depending on a rotational direction of the rotatable spindle.

4. The disconnect assembly of claim 3, wherein the linkage includes an arm member that is moved axially by rotation of the nut, the arm member being connected to the coupler.

5. The disconnect assembly of claim 4, wherein the arm member comprises a fork element having an arcuate portion at a distal end thereof, the arcuate portion engaging the coupler.

6. The disconnect assembly of claim 5, wherein the coupler defines an annular groove about an outer circumferential surface thereof, the arcuate portion of the fork element being seated in the annular groove.

7. The disconnect assembly of claim 1, wherein: the coupler has an annular configuration defining axial coupler splines on an inner circumferential surface thereof; the first rotating element defines axial first element splines on an outer circumferential surface thereof, the coupler splines and the first element splines being in engagement in both the disconnected position and the connected position; and the second rotating element defines axial second element splines on an outer circumferential surface thereof forming the clutch feature, the coupler splines and the second element splines being in engagement in the connected position.

8. The disconnect assembly of claim 1, wherein the screw type actuator comprises: a rotatable spindle having a threaded portion; a nonrotatable nut mounted on the threaded portion, the nut moving axially in first and second directions depending on a rotational direction of the rotatable spindle; and a motor operative to rotate the spindle in a first direction and an opposite second direction.

9. The disconnect assembly of claim 8, further comprising a position sensing arrangement to determine an axial position of the coupler.

10. The disconnect assembly of claim 9, wherein the position sensing arrangement is operative to detect an axial position of the nut such that the axial position of the coupler can be determined.

11. The disconnect assembly of claim 10, wherein the position sensing arrangement comprises at least one magnetic sensor device.

12. The disconnect assembly of claim 8, further comprising: a transition element connected to a distal side of the nut; and a fork element connected to the transition element, the fork element being connected to the coupler to axially move the coupler.

13. The disconnect assembly of claim 12, wherein the transition element defines an axial bore aligned with the threaded portion of the spindle to accommodate the threaded portion of the spindle during axial movement of the nut.

14. The disconnect assembly of claim 1, wherein the first rotating element and the second rotating element comprise shafts.

15. A disconnect assembly operative alternatively to connect and disconnect a first rotating element and a second rotating element, the disconnect assembly comprising: a coupler having an annular configuration defining axial coupler splines on an inner circumferential surface thereof; the first rotating element defining axial first element splines on an outer circumferential surface thereof; the second rotating element defining axial second element splines on an outer circumferential surface thereof; the coupler being slidably movable between a disconnected position in which the coupler splines and the first element splines are in engagement such that the coupler rotates only with the first element and a connected position in which the coupler splines are in engagement with both the first element splines and the second element splines; a lead screw actuator having a nonrotatable nut mounted on a threaded portion of a rotatable spindle, the nut moving axially in first and second directions depending on a rotational direction of the rotatable spindle; and a linkage connecting the nut to the coupler such that the coupler moves between the disconnected position and the connected position.

16. The disconnect assembly of claim 15, further comprising a position sensing arrangement to determine an axial position of the coupler.

17. The disconnect assembly of claim 16, wherein the position sensing arrangement is operative to detect an axial position of the nut such that the axial position of the coupler can be determined.

18. The disconnect assembly of claim 17, wherein the position sensing arrangement comprises at least one magnetic sensor device.

19. The disconnect assembly of claim 16, wherein the linkage includes an arm member that is moved axially by rotation of the nut, the arm being connected to the coupler.

20. The disconnect assembly of claim 19, wherein the arm member comprises a fork element having an arcuate portion at a distal end thereof, the arcuate portion engaging the coupler.

21. The disconnect assembly of claim 19, further comprising a transition element connected to a distal side of the nut, the fork element being connected to the coupler to axially move the coupler.

22. The disconnect assembly of claim 21, wherein the transition element defines an axial bore aligned with the threaded portion of the spindle to accommodate the threaded portion of the spindle during axial movement of the nut.