Electric drive with disconnect

Abstract

An electric drive for a vehicle implements a disconnect feature to reduce parasitic losses when the electric drive is not required for propulsion. The disconnect feature utilizes a slip clutch that is disengaged by using a set of pins that move radially to hold a slip ring in a predefined circumferential position relative to an outer ring. A rod spring biases the pins to a radially outward position. A solenoid axially moves a plunger that pushes the pins radially inward.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. non-provisional application 17 / 506,855, filed October 21, 2021, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to an electric drive for a vehicle. More specifically, this disclosure relates to an electric drive having a disconnectable feature that utilizes a slip clutch and an actuator, as well as a radial pin. Background Technology

[0004] A slipper clutch is known, for example, from U.S. Patent 6,409,001. A slipper clutch includes an inner ring and an outer ring, and a set of rollers radially positioned between the inner and outer rings. The inner surface of the outer ring and the outer surface of the inner ring have complementary inclined surfaces. Relative circumferential displacement between the inner and outer rings causes the rollers to roll upwards on the inclined portion and apply a radial force tending to separate the rings. One of the two rings, called the slip ring, has an axial slot that allows the slip ring to change its diameter in response to the radial force. When the slip ring is the inner ring, it contracts in response to the radial force to grip the shaft, thereby engaging the outer ring to the shaft. When the slip ring is the outer ring, it expands in response to the radial force to grip a cylindrical component, thereby engaging the inner ring to the cylindrical component. When the inner and outer rings are held in a predetermined circumferential position relative to each other, the slip ring slides relative to the shaft or cylindrical component with minimal resistance. Summary of the Invention

[0005] A disconnectable unit includes a first shaft and a second shaft, a slip clutch, at least one pin, a plunger, and a rod spring. The slip clutch has an outer ring, an inner ring, and a plurality of rollers. The outer ring is radially adjacent to a concave surface of the first shaft and can be fixed to the first shaft. The inner ring, which may have an axial groove, is radially adjacent to a convex surface of the second shaft. The rollers are radially positioned between the inner and outer rings and configured to radially separate the inner and outer rings to rotatably engage the first shaft to the second shaft in response to rotational displacement of the inner ring relative to the outer ring. At least one pin is supported for radial movement between a disconnected engagement position and an engaged position. In the disconnected engagement position, at least one pin fixes the rotational position of the inner ring relative to the outer ring. In the engaged position, at least one pin allows relative rotation between the inner and outer rings. The plunger is supported for axial movement between a first position and a second position. In the first position, the rod spring biases at least one pin toward the engaged position. In the second position, the rod spring is compressed, and at least one pin remains in the disconnected engagement position. The solenoid can be configured to force the plunger from a first position to a second position. The rod spring may include a ring and at least one rod arm, the ring being fixed to one of a first shaft and a second shaft, and the at least one rod arm connecting the ring to at least one pin.

[0006] An electric actuator includes an electric motor, a gearbox, an output shaft, a slip clutch, at least one pin, a plunger, and a rod spring. The electric motor has a stator and a rotor. The gearbox has an input member fixed to the rotor and a gearbox output member. The slip clutch has an outer ring, an inner ring, and a set of rollers. The outer ring is radially adjacent to a concave surface of the gearbox output member and can be fixed to the gearbox output member. The inner ring is radially adjacent to a convex surface of the output shaft and may have an axial groove. The rollers are radially located between the inner and outer rings and configured to radially separate the inner and outer rings to rotatably engage the gearbox output member to the output shaft in response to rotational displacement of the inner ring relative to the outer ring. At least one pin is supported for radial movement between a disengaged position and an engaged position. In the disengaged position, at least one pin fixes the rotational position of the inner ring relative to the outer ring. In the engaged position, at least one pin allows relative rotation between the inner and outer rings. The plunger is supported for axial movement between a first position and a second position. In the first position, the rod spring biases at least one pin toward the engaged position. In the second position, the rod spring is compressed, and at least one pin remains in the disengaged position. The solenoid may be configured to force the plunger from the first position to the second position. The rod spring may include a ring and at least one lever arm, the ring being secured to the gearbox output member, and the at least one lever arm connecting the ring to at least one pin. The electric actuator may also include a first housing and a second housing bolted together. The gearbox output member is supported relative to the first housing by a first bearing. The output shaft is supported relative to the second housing by a second bearing. Attached Figure Description

[0007] Figure 1 This is a side cross-sectional view of an electric drive with a disconnectable clutch.

[0008] Figure 2 yes Figure 1 Cross-sectional view of the end of the electric drive.

[0009] Figure 3 It is in a joined state. Figure 1 Detailed cross-sectional view of the disconnect clutch and actuator of the electric drive.

[0010] Figure 4 It is in a disconnected state. Figure 1 Detailed cross-sectional view of the disconnect clutch and actuator of the electric drive.

[0011] Figure 5 yes Figure 1 The first exploded view of the electric actuator.

[0012] Figure 6 yes Figure 1 The second exploded view of the electric driver. Detailed Implementation

[0013] Embodiments of this disclosure are described herein. It should be understood that the same reference numerals appearing in different views of the accompanying drawings identify the same or functionally similar structural elements. Furthermore, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various forms and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to utilize the embodiments in various ways. As will be understood by those skilled in the art, various features illustrated and described with reference to any of the accompanying drawings may be combined with features illustrated in one or more other drawings to produce embodiments not explicitly illustrated or described. The combinations of illustrated features provide representative embodiments for typical applications. However, for a particular application or implementation, various combinations and modifications of features consistent with the teachings of this disclosure may be required.

[0014] The terminology used herein is for descriptive purposes only and is not intended to limit the scope of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Although any methods, apparatus, or materials similar to or equivalent to those described herein may be used in practice or testing of this disclosure, the following example methods, apparatus, and materials will now be described.

[0015] Figure 1 The diagram illustrates an electric actuator 10 with a disconnected connection. In the connected mode, an electric motor drives an output shaft 12. The speed of the electric motor's rotor 14 is proportional to the speed of the output shaft 12. Power flows between the electric motor and the output shaft (primarily, but not exclusively, from the electric motor to the output shaft). Even when the motor is not required to provide or receive power, the rotor continues to rotate, resulting in significant parasitic resistance. In the disconnected mode, the speed of the rotor is not directly related to the speed of the output shaft. Typically, the rotor is stationary. Only a small amount of parasitic resistance acts on the output shaft.

[0016] The electric motor includes a rotor 14 supported for rotation relative to a housing 16 and a stator 18 fixed to the housing. The rotor 14 is fixed to a gearbox input shaft 20. Power flows from the gearbox input shaft 20 through a planetary gearbox 24 to a gearbox output shaft 22. The output shaft 12 is selectively connected to the gearbox output shaft 22 via a disconnect clutch 26. A separate housing 28 supports the output shaft 12 and the disconnect clutch 26.

[0017] Figures 2 to 4 A portion of the slip clutch 26 is shown in more detail. A slip ring (inner ring) 30 radially surrounds the output shaft 12. An outer ring 32 is fixed to the gearbox output shaft 22. A set of rollers 34 is radially positioned between the slip ring 30 and the outer ring 32. The inner surface of the outer ring 32 and the outer surface of the slip ring 30 have circumferentially inclined portions in alternating directions. When the slip ring 30 and the outer ring 32 are circumferentially aligned, the inclined portions are arranged in a loosely fitted manner with the rollers. Relative rotation causes the rollers to be compressed between the inclined portions, resulting in the rollers exerting a radially inward force on the slip ring.

[0018] Figure 3 The diagram illustrates a slipper clutch 26 and an actuator in the engaged state. A set of pins 36 are positioned at various circumferential locations relative to the gearbox output shaft 22 and are radially movable. Figure 3As shown, in the engaged position, the rod spring 38 pulls the pin radially outward away from the sliding ring 30. This outward movement of the rod spring also pushes the inclined surface of the solenoid plunger 40, causing the solenoid plunger to move to the left. When the pin 36 is disengaged from the sliding ring 30, a slight resistive torque between the sliding ring 30 and the output shaft 12 causes the sliding ring to rotate slightly relative to the outer ring 32. This slight rotation generates a radial force that increases the resistive torque between the sliding ring 30 and the output shaft 12. This enhanced circulation causes the sliding ring 30 to clamp the output shaft 12 tightly, thus connecting the two components. The inclined portion restricts the relative rotation between the sliding ring 30 and the outer ring 32, so that the output shaft is also connected to the outer ring 32 and the gearbox output shaft 22. Therefore, power is transmitted from the electric motor to the output shaft 12.

[0019] Figure 4 The diagram illustrates a slip clutch 26 and actuator in the disengaged state. This state is achieved by energizing a solenoid 42. The solenoid applies an axial force to the solenoid plunger 40, pulling the plunger to the right. The inclined surface of the solenoid plunger compresses a rod spring 38, which pushes a pin 36 radially inward. The pin 36 engages with a groove in the slip ring 30, holding the slip ring in the aligned position. With the slip ring in circumferential alignment relative to the outer ring, the roller 34 is positioned away from the inclined portion and does not apply radial force. The slip ring 30 rotates freely relative to the output shaft 12 with only a small degree of parasitic resistance. In the disengaged position, the rotor can stop while the output shaft 12 rotates with the wheel, thus eliminating the main source of parasitic resistance.

[0020] Refer again Figure 3 Note that the gearbox output shaft 22 is supported relative to housing 16 by bearing 44. The output shaft 12 is supported relative to housing 28 by bearing 46. This allows for a modular assembly in which the electric axle without disconnected connecting features utilizes many common components with the illustrated design. In an alternative, housing 28 is omitted along with the clutch and actuation components. The output shaft is then slightly modified and fixed to the gearbox output shaft.

[0021] Figure 5 and Figure 6 This is an exploded view of the electric actuator viewed from two different perspectives. This view illustrates the three-dimensional shape of some components that may not be apparent from a two-dimensional view. In particular, the rod spring 38 includes a ring 50 that holds in place relative to the gearbox output shaft 22 and a plurality of lever arms 52 connecting the ring 50 to the radial pin 36.

[0022] like Figure 5 As shown, the gearbox output shaft 22 is the carrier of the planetary gearbox 24, and the gearbox input shaft 20 is connected to the sun gear of the planetary gearbox 24.

[0023] like Figure 6 As shown, note that the inner ring 30 includes an axial groove 54. This groove allows the inner ring to change its diameter in response to the radial force applied by the roller 34, so as to clamp onto the output shaft 12.

[0024] Although exemplary embodiments have been described above, it is not intended that these embodiments describe all possible forms covered by the claims. The language used in this specification is descriptive rather than restrictive, and it should be understood that various modifications can be made without departing from the spirit and scope of this disclosure. As previously described, features of various embodiments can be combined to form other embodiments that may not be explicitly described or illustrated in this disclosure. While various embodiments may have been described as providing advantages or superiority over other embodiments or prior art implementations in one or more desired features, it will be recognized by those skilled in the art that one or more features or characteristics can be compromised to achieve desired overall system properties, depending on the specific application and implementation. Therefore, if any embodiment is described to some extent as less desirable than other embodiments or prior art implementations in one or more features, such embodiments are not beyond the scope of this disclosure and may be desirable for a particular application.

Claims

1. A disconnectable unit, comprising: A first shaft, the first shaft being supported to rotate about an axis; A second shaft, which is supported to rotate about the axis; A slip clutch having an outer ring, an inner ring, and a plurality of rollers, the outer ring being radially adjacent to a concave surface of a first shaft, the inner ring being radially adjacent to a convex surface of a second shaft, the plurality of rollers being radially located between the inner ring and the outer ring and configured to radially separate the inner ring and the outer ring, thereby rotatably connecting the first shaft to the second shaft in response to rotational displacement of the inner ring relative to the outer ring; At least one pin is supported to move radially between a disengaged position and an engaged position, wherein in the disengaged position the at least one pin fixes the rotational position of the inner ring relative to the outer ring, and in the engaged position the at least one pin allows relative rotation between the inner ring and the outer ring; as well as A plunger is supported for axial movement from a first position and a second position, in which a rod spring biases the at least one pin toward the engaged position, and in the second position, the rod spring is compressed and the at least one pin is held in the disengaged position.

2. The disconnectable unit of claim 1 further includes a solenoid configured to force the plunger from the first position to the second position.

3. The disconnectable unit according to claim 1, wherein, The rod spring includes: A ring, the ring being fixed to one of the first shaft and the second shaft; and At least one lever arm connects the ring to the at least one pin.

4. The disconnectable unit according to claim 1, wherein, The outer ring is fixed to the first shaft, and the inner ring has an axial groove.

5. An electric actuator, comprising: An electric motor having a stator and a rotor; A gearbox having an input component fixed to the rotor and a gearbox output component; Output shaft; A slip clutch having an outer ring, an inner ring, and a plurality of rollers, the outer ring being radially adjacent to a concave surface of a gearbox output member, the inner ring being radially adjacent to a convex surface of an output shaft, the plurality of rollers being radially located between the inner ring and the outer ring and configured to radially separate the inner ring and the outer ring, thereby rotatably engaging the gearbox output member to the output shaft in response to rotational displacement of the inner ring relative to the outer ring; At least one pin is supported to move radially between a disengaged position and an engaged position, wherein in the disengaged position the at least one pin fixes the rotational position of the inner ring relative to the outer ring, and in the engaged position the at least one pin allows relative rotation between the inner ring and the outer ring; as well as A plunger is supported for axial movement from a first position and a second position, in which a rod spring biases the at least one pin toward the engaged position, and in the second position, the rod spring is compressed and the at least one pin is held in the disengaged position.

6. The electric actuator of claim 5, further comprising a solenoid configured to force the plunger from the first position to the second position.

7. The electric actuator according to claim 5, wherein, The rod spring includes: A ring, the ring being fixed to the gearbox output component; and At least one lever arm connects the ring to the at least one pin.

8. The electric actuator according to claim 5, wherein, The outer ring is fixed to the gearbox output component, and the inner ring has an axial groove.

9. The electric drive according to claim 5, further comprising: A first housing supporting the stator, wherein the gearbox output member is supported relative to the first housing by a first bearing; and A second housing is bolted to the first housing, wherein the output shaft is supported relative to the second housing by a second bearing.

10. An electric actuator, comprising: An electric motor having a stator and a rotor; A gearbox having an input component fixed to the rotor and a gearbox output component; Output shaft; A slip clutch having an outer ring, an inner ring, and a plurality of rollers, the outer ring being fixed to the gearbox output member, the inner ring being radially adjacent to a convex surface of the output shaft, the plurality of rollers being radially located between the inner ring and the outer ring and configured to radially separate the inner ring and the outer ring, so as to rotatably engage the gearbox output member to the output shaft in response to rotational displacement of the inner ring relative to the outer ring; At least one pin is supported to move radially between a disengaged position and an engaged position, wherein in the disengaged position the at least one pin fixes the rotational position of the inner ring relative to the outer ring, and in the engaged position the at least one pin allows relative rotation between the inner ring and the outer ring; as well as A plunger is supported for axial movement from a first position and a second position, in which a rod spring biases the at least one pin toward the engaged position, and in the second position, the rod spring is compressed and the at least one pin is held in the disengaged position.

11. The electric actuator of claim 10, further comprising a solenoid configured to force the plunger from the first position to the second position.

12. The electric actuator according to claim 10, wherein, The rod spring includes: A ring, the ring being fixed to the gearbox output component; and At least one lever arm connects the ring to the at least one pin.

13. The electric actuator of claim 10, wherein, The inner ring has an axial groove.

14. The electric drive of claim 10, further comprising: A first housing supporting the stator, wherein the gearbox output member is supported relative to the first housing by a first bearing; and A second housing is bolted to the first housing, wherein the output shaft is supported relative to the second housing by a second bearing.

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