DRIVETRAIN DISCONNECT ASSEMBLY WITH INTERNAL PUSHROD ACTIVATION

PRIORITY CLAIM

[0001] This application is based upon and claims priority to U.S. provisional application serial no. 63/347212, filed May 31, 2022, incorporated herein by reference in its entirety 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 in which multiple drive axles are utilized in a drivetrain on a continuous, or full-time, basis are known. For various reasons, however, 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 manually engage a vehicle’s drivetrain to the wheels, which typically require that the user exits the vehicle to manually engage the wheels. As well, prior art automated systems, as shown in Figure 5, utilize a vehicle’s control system to automatically engage and disengage the drivetrain from the wheels dependent upon the driving conditions. However, such mechanisms 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 for transferring torque comprising an elongated shaft defining an elongated central bore extending axially therethrough. An elongated pushrod is disposed within the central bore of the shaft and is axially movable with respect to the elongated shaft. In addition, a gear (e.g., an input gear) is rotatably supported with respect to the shaft. An annular coupler defining a central bore is also provided, the shaft passing through the central bore of the coupler and the coupler being fixed to the pushrod so that the coupler rotates with the shaft but is axially movable with respect to the shaft along with the pushrod between a disconnected state in which the coupler is not in engagement with the gear and a connected state in which the coupler is in engagement with the gear. The coupler and the gear have engaging features so that the shaft and the gear rotate as a unit when the coupler is in the connected state. The gear rotates freely with respect to the shaft when the coupler is in the disconnected state.

[0006] According to some exemplary embodiments, a plurality of coupler splines depend inwardly from a central bore of the coupler, the coupler splines alternating with shaft splines on an outer surface of the shaft such that the coupler can slide with respect to the shaft. According to some exemplary embodiments, the engaging features may comprise a plurality of face splines of the coupler that are selectively engageable with gear splines of the gear. For example, the gear splines may be located on an inner circumferential surface of the gear. [0007] According to some exemplary embodiments, first and second bearings are provided to rotatably support the gear with respect to the shaft. For example, the coupler may be located axially between the first and second bearings.

[0008] Some exemplary embodiments further comprise a mounting pin extending transversely through the pushrod. A pair of opposed slots may be defined in the shaft to define an extent to which the coupler can move axially between the disconnected and connected states. For example, respective ends of the pushrod may extend through the slots into engagement with the coupler so as to fix the coupler to the pushrod.

[0009] In embodiments where the gear comprises an input gear, an output gear may also be fixed with respect to the shaft and axially spaced apart from the input gear.

[00010] Another aspect of the present invention provides a disconnect assembly for transferring torque comprising an elongated shaft and an elongated pushrod axially movable with respect to the elongated shaft. A gear is rotatably supported with respect to the shaft. A coupler is fixed to the pushrod and connected to the shaft for slidable movement with respect to the shaft so that so that the coupler rotates with the shaft but is axially movable with respect to the shaft along with the pushrod between a disconnected state in which the coupler is not in engagement with the gear and a connected state in which the coupler is in engagement with the gear. The coupler and the gear have engaging features so that the shaft and the gear rotate as a unit when the coupler is in the connected state. An actuator is operative to effect movement of the coupler between the disconnected state and the connected state. The gear rotates freely with respect to the shaft when the coupler is in the disconnected state. [00011] According to some exemplary embodiments, the actuator may comprise an electromagnetic actuator. The electromagnetic actuator may include a rod that connects to the pushrod.

[00012] 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

[00013] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended drawings, in which;

[00014] Figure 1 is a perspective cutaway view of a drivetrain gearbox including a disconnect assembly with pushrod activation in accordance with an embodiment of the present invention;

[00015] Figure 2 is a partially exploded cutaway view of the disconnect assembly shown in Figure 1 with the input gear separated from the shaft for purposes of illustration;

[00016] Figures 3A and 3B are cutaway plan views of the disconnect assembly shown in Figure 1 in the disconnected and connected states, respectively;

[00017] Figure 4 is a diagrammatic illustration of a disconnect assembly in accordance with an embodiment of the present invention; and

[0010] Figure 5 is a partial cross-sectional view of a drivetrain including a prior art disconnect assembly. [0011] 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 OF THE PREFERRED EMBODIMENTS

[0012] 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.

[0013] 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 disconnect assembly that may be disposed in a different orientation.

[0014] Further, the term “or” as used in this disclosure and 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. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from the context to be directed to a singular form. Throughout the specification and claims, the following terms take at least the meanings explicitly associated herein, unless the context dictates otherwise. The meanings identified below do not necessarily limit the terms, but merely provided illustrative examples for the terms. 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.

[0015] Referring now to Figures 1 and 2, a gearbox 10 of an electric drivetrain for a vehicle is shown. A disconnect assembly 12 in accordance with an embodiment of the present disclosure is disposed within the housing 11 of the gearbox 10 and configured to selectively connect a source of motive power (e.g., an electric motor) of the vehicle to a corresponding wheel (not shown). As such, the disconnect assembly 12 allows for the selective transmission of torque to the wheel by the source. In the embodiment shown, the disconnect assembly 12 includes an input gear 14, an elongated shaft 20, an annular coupler 34 secured to a pushrod 30, and an output gear 44. (One skilled in the art will appreciate that the gears 14 and 44 would typically have gear teeth on their outer circumferential surface.)

[0016] As best seen in Figure 2, the shaft 20 defines an elongated central bore 22 that is configured to slidably receive the pushrod 30 therein. Additionally, an outer surface of the shaft 20 defines an annular set of axial splines 26 that is disposed between a pair of annular bearing surfaces 28. Each bearing surface 28 of the shaft 20 is engaged by a corresponding radial bearing

50 so that the input gear 14 is rotatable with respect to the shaft 20 when the disconnect assembly 12 is in the disconnected state as discussed in greater detail below. Of course, the shaft 20 is also suitably supported for rotation within the housing of the gear box 10. An opposed pair of elongated slots 24 is also defined in the sidewall of the shaft 20 between the bearing surfaces 28. The elongated slots 24 allow a mounting pin 32 of the pushrod 30 to pass therethrough, as discussed in greater detail below.

[0017] The annular coupler 34 defines a central bore 36 that is configured to slidably receive the shaft 20 therethrough. In this embodiment, the central bore 36 of the coupler 34 defines a plurality of axial splines 38 that alternate with and are correspondingly- shaped to the axial splines 26 formed on the outer surface of the shaft 20. The axial splines 38 and 26 non- rotatably fix the coupler 34 to the shaft 20, yet allow the coupler 34 to move axially with respect to the shaft 20. Each end of the mounting pin 32 of the pushrod 30 extends outwardly through a corresponding elongated slot 24 of the shaft 20 and is received in a corresponding mounting hole 42 that is defined by the coupler 34, thereby both axially and non-rotatably fixing the coupler 34 to the pushrod 30. As such, pushrod 30, pin 32, and coupler 30 rotate with the shaft 20, but can slide axially with respect to shaft 20 limited by the axial extent of slots 24 (see Figures 3A and 3B). While the mounting pin 32 is used to interconnect pushrod 30 and coupler 34 in this embodiment, one skilled in the art will appreciate that any suitable means of making this interconnection can be used.

[0018] As best seen in Figure 2, a face of the annular coupler 34 in this embodiment defines a plurality of face splines (dogs) 40 that are selectively engageable with a corresponding set of splines 18 which extend radially-inwardly from an inner diameter of the input gear 14. . Additionally, while the disconnect assembly 12 utilizes a dog clutch arrangement in the illustrated embodiment, one skilled in the art will appreciate that any suitable clutching arrangement such as a friction clutch could also be used as necessary or desired so long as engaging features allow connection and disconnection substantially in the manner described herein.

[0019] Figures 3A and 3B show the disconnect assembly 12 in disconnected and connected states, respectively. In the disconnected state, as shown in Figure 3A, the pushrod 30 and, therefore, the annular coupler 34 are located in a first (retracted) position in which the face splines 40 of the coupler 34 are disengaged from the splines 18 of the input gear 14. In the first position, the input gear 14 is free to rotate with respect to the elongated shaft 20 so that torque is not transmitted from the motive source that rotates the input gear 14, to the corresponding wheel. Preferably, the park path remains connected in the disconnected state.

[0020] In the connected state, as shown in Figure 3B, the pushrod 30 and the coupler 34 are in a second (engaged) position in which the face splines 40 are engaged with the splines 18 of the input gear 14. When the pushrod 30 and annular coupler 34 are in the second position, the annular coupler 34 is non-rotatably fixed to the input gear by the face splines 40 and splines 18. As a result, torque is transmitted from the input gear 14 to the elongated shaft 20 and, thereby, to an output gear 44 that is non-rotatably fixed to the opposite end of the elongated shaft.

[0021] Referring now to Figure 4, a suitable actuator 50 is preferably used to move the pushrod 30 axially with respect to the shaft 20. For example, actuator 50 may be any suitable electromagnetic actuator mounted to the housing 11 of the gear box 10 adjacent the end of the pushrod 30 that is opposite the end on which the coupler 34 is mounted, such as a solenoid, motor-rack-and-pinion, etc. The actuator body may be mounted on the cover of gearbox 10 and a through hole could be provided to allow the movable portion 51 of actuator 50 (e.g., rod, rackbar, or other) to pass into the gearbox 10 and fasten to the pushrod 30 via a circlip or other method. Additionally, the disconnect assembly 12 may include bi-stability features that hold the coupler 34 in either the connected or disconnected state without the need for electrical power being applied to the assembly. These features can be incorporated into the elongated shaft 20 and pushrod 30, or the electromechanical actuator, as necessary or desired. A position sensor (e.g., sensor 52) may be used to sense the position of the pushrod 30 and, therefore, coupler 34. The position sensor can be mounted to either look radially at the pushrod 30 and coupler 34 or axially at the assembly.

[0022] 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.