Torque limiting rotor coupling for electrically driven camshaft phasers

Abstract

An electrically actuated variable camshaft timing (VCT) assembly including an electric motor for controlling the VCT assembly, the electric motor having a rotor and an electric motor output shaft; a gearbox assembly having an input coupled to the electric motor output shaft and an output configured to be coupled to a camshaft of an internal combustion engine; and a torque limiting assembly coupled to the electric motor output shaft, the torque limiting assembly preventing angular displacement of the electric motor output shaft relative to the rotor and including a spring that releasably engages the rotor to the electric motor output shaft to prevent angular displacement of the rotor relative to the electric motor output shaft at or below a torque limit and to allow angular displacement of the rotor relative to the electric motor output shaft above the torque limit.

Description

Technical Field

[0001] This application relates to electric motors, and more specifically, to electric motors for electrically driven variable camshaft timing (VCT) devices (also known as electrically driven camshaft phasers). Background Technology

[0002] An internal combustion engine includes a camshaft that opens and closes valves that regulate the combustion of fuel and air within the engine's combustion chamber. The opening and closing of these valves are carefully timed relative to various events, such as fuel injection and combustion entering the combustion chamber, and the piston's position relative to top dead center (TDC). The camshaft is driven by the rotation of the crankshaft via drive components (such as belts or chains) connecting these elements. Historically, there was a fixed relationship between the rotation of the crankshaft and the rotation of the camshaft. However, internal combustion engines increasingly use camshaft phasers that alter the phase of the camshaft's rotation relative to the crankshaft's rotation. In some implementations, a variable camshaft timing (VCT) device—the camshaft phaser—can be actuated by an electric motor that advances or delays the opening / closing of the valves relative to the crankshaft's rotation.

[0003] An electrically actuated camshaft phaser may include an electric motor and a gearbox having an input and an output. The output of the gearbox may be connected to the camshaft, while the input may be connected to the output shaft of the electric motor. The electric motor may include an output shaft connected to the rotor of the electric motor and the input of the gearbox. During operation, the electrically actuated camshaft phaser may have an operating range or an angular displacement of the camshaft relative to the crankshaft. Summary of the Invention

[0004] In one implementation, the electrically actuated variable camshaft timing (VCT) assembly includes an electric motor for controlling the VCT assembly, the electric motor having a rotor and an electric motor output shaft; a gearbox assembly having an input end coupled to the electric motor output shaft and an output end configured to be coupled to a camshaft of an internal combustion engine; and a torque limiting assembly coupled to the electric motor output shaft, the torque limiting assembly preventing angular displacement of the electric motor output shaft relative to the rotor, and including a spring that releasably engages the rotor to the electric motor output shaft to prevent angular displacement of the rotor relative to the electric motor output shaft at or below a torque limit, and to allow angular displacement of the rotor relative to the electric motor output shaft above the torque limit.

[0005] In another implementation, the electrically actuated VCT assembly includes an electric motor for controlling the VCT assembly, the electric motor having a rotor and an output shaft; a gearbox assembly having an input end coupled to the output shaft of the electric motor and an output end configured to be coupled to a camshaft of an internal combustion engine; and a torque limiting assembly including a rotor plate having a radially outwardly extending flange having an axial surface axially biased to releasably engage with an axial face of the rotor, wherein the rotor plate is coupled to the output shaft of the electric motor such that the rotor plate is maintained in a fixed angular position relative to the output shaft of the electric motor.

[0006] In another implementation, an electrically actuated VCT assembly includes an electric motor for controlling the VCT assembly, the electric motor having a rotor and an output shaft; a gearbox assembly having an input terminal coupled to the output shaft of the electric motor and an output terminal configured to be coupled to a camshaft of an internal combustion engine; and a torque limiting assembly coupled to the output shaft of the electric motor, the torque limiting assembly preventing angular displacement of the output shaft of the electric motor relative to the rotor and including a rotor plate fixed to the rotor, wherein the rotor plate includes one or more friction surfaces that releasably engage the rotor to the output shaft of the electric motor to prevent angular displacement of the rotor relative to the output shaft of the electric motor from being at or below a torque limit and to allow angular displacement of the rotor relative to the output shaft of the electric motor to be above the torque limit. Attached Figure Description

[0007] Figure 1 This is an exploded diagram depicting the implementation of the electrically actuated VCT component;

[0008] Figure 2 This is an exploded view depicting a portion of the implementation of the electrically actuated VCT component;

[0009] Figure 3 This is a cross-sectional view depicting the implementation of the torque limiting component;

[0010] Figure 4 It is a outline diagram depicting a portion of the implementation of the torque limiting component;

[0011] Figure 5 This is a cross-sectional view depicting the implementation of the torque limiting component;

[0012] Figure 6 This is a cross-sectional view depicting the implementation of the torque limiting component;

[0013] Figure 7 It is a cross-sectional view depicting the implementation of the torque limiting component; and

[0014] Figure 8 This is a perspective view depicting the implementation of the torque limiting component. Detailed Implementation

[0015] An electrically actuated variable camshaft timing (VCT) assembly—sometimes called a camshaft phaser—uses an electric motor to control the angular position of the camshaft relative to the crankshaft. The motor typically drives a gearbox assembly that transmits the angular motion of the motor's output shaft through its input to the output of the gearbox assembly, which is ultimately coupled to the camshaft. The motor's output shaft can also be connected to a rotor, which is housed by a stator within the motor. When current is received by the motor, the rotor is induced to move angularly relative to the stator. During operation, the electrically actuated camshaft phaser can have an authorized range, or angular displacement range, of the camshaft relative to the crankshaft. When the electrically actuated camshaft phaser approaches one end of this range, mechanical stops included in the phaser prevent the camshaft's angular displacement relative to the crankshaft from exceeding this range. As the electrically actuated camshaft phaser reaches and engages these stops, a significant increase in torque can be transmitted through the gearbox assembly to the motor's output shaft and the motor. If the torque is sufficiently large, components of the electrically actuated camshaft phaser may be damaged. The feature of releasing and / or releasing these loads when the electrically actuated camshaft phaser reaches the limit of its authorized range and engages these stops can help maintain the phaser's functionality.

[0016] A torque limiting assembly between the rotor and the motor output shaft prevents angular displacement between the motor shaft and the rotor from falling below a defined torque limit and allows angular displacement between the motor shaft and the rotor to be at or above the defined torque limit, which can be reached or exceeded when the camshaft phaser reaches and engages a stop that limits the authorized range. In some implementations, the torque limiting assembly may include a rotor plate and an axial spring. The rotor plate may be fixed to the motor output shaft in a manner that prevents angular displacement of the plate relative to the shaft. The rotor plate may have a radially outwardly extending flange having an axial surface that releasably engages an axial face of the rotor. The axial surface of the rotor plate may include a plurality of surface features shaped to conform to other shaped features included on the axial face of the rotor. The axial spring may bias the rotor plate in the direction of the shaft rotation axis to engage with the axial face of the rotor. When the motor controls the electrically actuated camshaft phaser within the authorized range, the rotor plate, biased by the spring to engage with the rotor, maintains the angular position of the motor output shaft relative to the rotor. When the torque limit is reached, the axial surface of the rotor plate can be angularly displaced relative to the axial surface of the rotor to limit the amount of torque that can be transmitted from the gearbox assembly to the motor. Once the torque applied to the motor output shaft drops below the torque limit, the spring can again bias the rotor plate back into engagement with the rotor to prevent angular displacement of the rotor plate relative to the rotor, thereby preventing angular displacement of the motor output shaft relative to the rotor.

[0017] Figure 1-2An embodiment of an electrically actuated camshaft phaser 10 is shown. The phaser 10 is a multi-piece mechanism with multiple components that work together to transmit rotation from the engine crankshaft to the engine camshaft, and these components can work together to cause angular displacement of the camshaft relative to the crankshaft, thereby advancing and delaying the opening and closing of the engine valves. Among other possible factors, the phaser 10 can have different designs and constructions depending on the application of the phaser and the crankshaft and camshaft in which it operates. For example, in… Figure 1-2 In the embodiment shown, the phaser 10 includes a sprocket 12, a planetary gear assembly 14, an inner plate 16, and a motor 20.

[0018] Sprocket 12 receives a rotational drive input from the engine crankshaft and rotates about axis X1. A timing chain or timing belt may wrap around sprocket 12 and around the camshaft, such that rotation of the camshaft is converted into rotation of sprocket 12 via the chain or belt. Other techniques for transmitting rotation between sprocket 12 and the camshaft are possible, such as geared valve trains. Along its outer surface, sprocket 12 has a set of teeth 22 for engaging with a timing chain, timing belt, or another component. In various examples, this set of teeth 22 may include thirty-eight individual teeth, forty-two individual teeth, or some other number of teeth that continuously span the circumference of sprocket 12. As shown, sprocket 12 has a housing 24 that axially extends from this set of teeth 22. Housing 24 is a cylindrical wall surrounding a component of planetary gear assembly 14.

[0019] In the embodiment presented here, the planetary gear assembly 14 includes a sun gear 26, planet gears 28, a first ring gear 30, and a second ring gear 32. The sun gear 26 is driven by an electric motor 20 to rotate about an axis X1. The sun gear 26 meshes with the planet gears 28 and has a set of teeth 34 on its exterior for direct tooth-to-tooth meshing with the planet gears 28. In various examples, this set of teeth 34 may include twenty-six individual teeth, thirty-seven individual teeth, or some other number of teeth that continuously span the circumference of the sun gear 26. A cylindrical skirt 36 spans across this set of teeth 34. As described above, the sun gear 26 is an external spur gear, but it may also be other types of gears.

[0020] When the engine camshaft is positioned between an advance and a retardation angle, the planetary gears 28 rotate about their respective axes of rotation X2. When not advancing or decelerating, the planetary gears 28 rotate about axis X1 together with the sun gear 26 and the ring gears 30, 32. In the embodiment given herein, there are a total of three discrete planetary gears 28, which are designed and constructed similarly to each other, but other numbers of planetary gears, such as two, four, or six, are also possible. However, in many cases, each planetary gear 28 may mesh with both the first ring gear 30 and the second ring gear 32, and each planetary gear may have a set of teeth 38 along its outer side for direct tooth-to-tooth meshing with the ring gears. In different examples, the teeth 38 may include twenty-one individual teeth, or some other number of teeth that continuously span the circumference of each planetary gear 28. To hold the planetary gears 28 in place and support them, a support assembly 40 may be provided. The support assembly 40 may have different designs and constructions. In the embodiment shown in the accompanying drawings, the support assembly 40 includes a first support plate 42 at one end, a second support plate 44 at the other end, and a cylinder 46 that serves as the hub of the rotating planetary gear 28. Planetary pins or bolts 48 may be used with the support assembly 40.

[0021] The first ring gear 30 receives a rotational drive input from the sprocket 12, causing the first ring gear 30 and the sprocket 12 to rotate together about axis 1 during operation. The first ring gear 30 may be an integral extension of the sprocket 12, i.e., the first ring gear 30 and the sprocket 12 may form an integral structure together. The first ring gear 30 has a ring shape, meshes with the planetary gear 28, and has a set of teeth 50 inside for direct tooth-to-tooth meshing with the planetary gear 28. In different examples, these teeth 50 may include 80 individual teeth, or some other number of teeth that continuously span the circumference of the first ring gear 30. In the embodiment given herein, the first ring gear 30 is an internal spur gear, but it may also be other types of gears.

[0022] The second ring gear 32 transmits the rotational drive output about axis X1 to the engine camshaft. In this embodiment, the second ring gear 32 drives the rotation of the camshaft via plate 16. The second ring gear 32 and plate 16 can be joined together in various ways, including interconnection by cuts and tabs, press fit, welding, adhesion, bolting, riveting, or by another technique. In embodiments not shown here, the second ring gear 32 and plate 16 can be integral extensions of each other to form a monolithic structure. Similar to the first ring gear 30, the second ring gear 32 has an annular shape, meshes with planetary gears 28, and has a set of teeth 52 inside for direct tooth-to-tooth meshing with the planetary gears. In various examples, these teeth 52 may include seventy-seven individual teeth, or some other number of teeth that continuously span the circumference of the second ring gear 32. The number of teeth between the first ring gear 30 and the second ring gear 32 relative to each other may differ by a multiple of the number of planetary gears 28 provided. Therefore, for example, tooth 50 may include eighty individual teeth, while tooth 52 may include seventy-seven individual teeth—the difference between the three individual teeth of the three planetary gears 28 in this example. In another example with six planetary gears, tooth 50 may include 70 individual teeth, while tooth 52 may include 82 individual teeth. Satisfying this relationship provides forward and deceleration capabilities by imparting relative rotational motion and relative rotational speed between the first ring gear 30 and the second ring gear 32 during operation. In the embodiment given here, the second ring gear 32 is an internal spur gear, but it may also be other types of gears. Plate 16 includes a central hole 54 through which a central bolt 56 passes to securely attach plate 16 to the camshaft. Furthermore, plate 16 is also secured to sprocket 12 by a retaining ring 58, which axially restricts the planetary gear assembly 14 between sprocket 12 and plate 16. The assembly includes a mechanical stop 18 that can be used to limit the authorized range or angular displacement of the input end relative to the output end.

[0023] The two ring gears 30 and 32 together form a combined ring gear configuration for the planetary gear assembly 14. However, other implementations of the electronically controlled camshaft phaser can be used in conjunction with torque limiting components. For example, the planetary gear assembly 14 may include an eccentric shaft and a compound planetary gear used in conjunction with the first and second ring gears, or a harmonic drive system may be used.

[0024] Go to Figure 3An embodiment of torque limiting assembly 60a is shown. Assembly 60a includes a rotor plate 62a and an axial spring 64. The rotor plate 62a can be secured to the motor output shaft 66 using the splined outer surface of a shaft 66, which engages an inner diameter 68 of the rotor plate 62a. The inner diameter 68 may include radially inward teeth that conform to the splined outer surface of the shaft 66. The combination of the splined outer surface and the radially inward teeth prevents angular displacement of the motor output shaft 66 relative to the rotor plate 62a. The rotor 70 of the motor 20 may include an inner diameter 72 that closely conforms to the outer surface 74 of the motor output shaft 66. The inner diameter 72 and the outer surface 74 are freely movable relative to each other to allow angular displacement of the rotor 70 relative to the motor output shaft 66. The rotor plate 62a may have one or more flanges 76 extending radially outward away from the axis of rotation (x) of the shaft. The flanges 76 may have an axial surface 78 facing an axial surface 80 of the rotor 70, which releasably engages the axial surface 80. The axial surface 78 may include axially extending flange teeth 82 that mesh with corresponding axially extending rotor teeth 84 formed on the axial surface 80 of the rotor 70, such as... Figure 4 As shown. One or more flanges 76 of rotor plate 62a and axial surface 80 of rotor 70 can be configured to implement these teeth 82 as components for Hirth couplings or face-spline connections to provide torque pawls. However, it should be understood that other implementations of the surface features on rotor plate 62a and rotor 70 that achieve torque limits are possible. For example, laser-etched surfaces can be applied to the axial surfaces of the flanges and the axial surface of the rotor, such that when these surfaces are biased to mesh with each other, these surfaces can prevent angular displacement of the rotor plate relative to the motor output shaft, but allow angular displacement at or above the torque limits.

[0025] The motor output shaft 66 can be supported by a motor bearing 94, which can be axially spaced on opposite sides of the rotor plate 62a. An axial spring 64 can be positioned to engage the axial face of the motor bearing 94 and a portion of the rotor plate 62a. In this implementation, the axial spring 64 is a helical spring. However, the term "spring" should be interpreted broadly as a biasing member, and it should be understood that other types of biasing members can be used to implement the axial spring. For example, a leaf spring can be used alternatively to implement the axial spring. Alternatively, in another implementation, the bearing can be press-fitted to the motor output shaft to prevent angular displacement of the bearing relative to the shaft; in this embodiment, the rotor plate can be implemented as a Belleville washer, which can be fixed to the inner race of the bearing.

[0026] Figure 5Another implementation of the torque limiting assembly 60b is depicted. Assembly 60b includes a rotor plate 62b with an integral axial spring. A radially outwardly extending flange 76' may include a pre-bent portion that biases the flange 76' to engage with the axial face 80 of the rotor 70. The rotor plate 62b may be secured to the motor output shaft 66 to prevent angular displacement of the plate 62b relative to the shaft 66. In this implementation, the rotor plate 62b may be splined to the motor output shaft 66, or the two components may be press-fitted or welded together.

[0027] Figure 6 Another implementation of torque limiting assembly 60c is depicted. Assembly 60c may include an axial spring 64c, which is implemented as a Bainckite washer or a tapered spring washer. Rotor 70 may include a friction plate 106 fixed to an axial face 80 of rotor 70. Friction plate 106 may be made of a material having a higher coefficient of friction than rotor material. Spacer 108 may be axially positioned between rotor 70 and motor bearing 94 to aid in rotor 70 alignment with stator or to provide a friction surface for rotor 70 to engage. Axial spring 64c may engage friction plate 106 and axial face 110 of motor bearing 94. The axial force applied by spring 64c to friction plate 106 and motor bearing 94 may define a torque limit beyond which rotor 70 will angularly displace relative to motor output shaft 66. In some implementations, axial face 110 of motor bearing 94 may include a surface having an increased coefficient of friction relative to other outer surfaces of motor bearing 94. When the torque level applied to the motor output shaft 66 rises above a threshold, the spring 64c can move relative to the friction plate 106, and the rotor 70 can angularly displace relative to the shaft 66. Once the torque level applied to the motor output shaft 66 drops below the threshold, the spring 64c can again prevent the shaft 66 from angularly displacing relative to the rotor 70.

[0028] Figure 7Another embodiment of the torque limiting assembly 60d is depicted. Assembly 60d includes an axial spring 64d, a rotor 70d, and a tapered friction washer 112. The axial spring 64d may be implemented as a Bavarian washer or a tapered spring washer. The rotor 70d may include a friction plate 106 on an axial surface 80a of the rotor 70d. The axial spring 64d may engage the friction plate 106 and the axial surface 110 of the motor bearing 94. The axial force applied by the spring 64d to the friction plate 106 and the motor bearing 94 may partially define a torque threshold above which the rotor 70d will angularly displace relative to the motor output shaft 66. Another axial surface 80b of the rotor 70d may include a tapered feature 116. The tapered feature 116 may have a tapered or frustoconical surface with a coefficient of friction higher than other areas of the axial surface 80b. The tapered friction washer 112 may have a corresponding surface that fits tightly into and is received by the tapered feature 116. The surface of the tapered friction pad 112, which engages with the tapered feature 116, may also include an increased coefficient of friction and partially define a torque threshold. The tapered friction pad 112 may have an axial surface 118 that abuts and engages with the axial surface 110 of the motor bearing 94. The axial force applied by the spring 64d to the friction plate 106 and the tapered friction pad 112 can jointly define a torque limit, beyond which the rotor 70d will angularly displace relative to the motor output shaft 66. When the torque level applied to the motor output shaft 66 rises above the threshold, the spring 64c may move relative to the friction plate 106 and / or the rotor 70d may move relative to the tapered friction pad 112; the rotor 70d may angularly displace relative to the shaft 66. Once the torque level applied to the motor output shaft 66 drops below the threshold, the spring 64d can again prevent angular displacement of the shaft 66 relative to the rotor 70.

[0029] Go to Figure 8This illustrates another implementation of the torque limiting assembly 60e. Assembly 60e includes a rotor plate 62e and a rotor 70e. In this implementation, the rotor plate 62e may be shaped to engage a groove 114 formed in the rotor 70e to prevent angular displacement of the plate 62e relative to the rotor 70e. The rotor plate 62e may include an inner diameter having a surface with an increased coefficient of friction that engages with the motor output shaft 66. Additionally or alternatively, the axial surface 80 of the rotor 70e may engage an axial surface of a motor bearing 94, either of which may include a friction surface. The rotor 70e can rotate and transmit torque to the motor output shaft 66 via the rotor plate 62e. When the torque level applied to the motor output shaft 66 rises above a threshold, the friction surfaces of the inner diameter of the rotor plate 62e and / or the friction surfaces between the rotor 70e and the motor bearings 94 may move relative to each other, thereby allowing angular displacement of the motor shaft 66 relative to the rotor 70e. Once the torque level applied to the motor output shaft 66 drops below a threshold, the friction surfaces of the inner diameter and / or rotor 70e and motor bearing 94 can again prevent angular displacement of shaft 66 relative to rotor 70e.

[0030] It should be understood that the foregoing description describes one or more embodiments of the present invention. The invention is not limited to the specific embodiments disclosed herein, but is defined solely by the appended claims. Furthermore, the statements contained in the foregoing description relate to specific embodiments and should not be construed as limiting the scope of the invention or the definition of terms used in the claims, unless the terms or phrases are expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiments will be readily understood by those skilled in the art. All such other embodiments, changes, and modifications are intended to fall within the scope of the appended claims.

[0031] As used in this specification and claims, the terms “eg,” “for example,” “for instance,” “such as,” and “like,” as well as the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a list of one or more parts or other items, are each interpreted as open-ended, meaning that the list is not considered to exclude other additional parts or items. Other terms will be interpreted using their broadest reasonable meaning unless used in a context requiring a different interpretation.

Claims

1. An electrically actuated variable camshaft timing assembly, comprising: An electric motor is configured to control the variable camshaft timing assembly, the electric motor including a rotor and an electric motor output shaft; A gearbox assembly, including an input terminal coupled to the output shaft of the electric motor, and an output terminal configured to be coupled to the camshaft of an internal combustion engine; and A torque limiting assembly connected to the output shaft of the motor is configured to: The rotor is releasably coupled to the motor output shaft to prevent angular displacement of the rotor relative to the motor output shaft when the torque applied to the motor output shaft is less than or equal to the torque limit, and When the torque applied to the output shaft of the motor exceeds the torque limit, the rotor is separated from the output shaft of the motor to allow angular displacement of the rotor relative to the output shaft of the motor.

2. The electrically actuated variable camshaft timing assembly according to claim 1, wherein the torque limiting assembly includes a rotor plate.

3. The electrically actuated variable camshaft timing assembly of claim 2, wherein the rotor plate includes a toothed pawl.

4. The electrically actuated variable camshaft timing assembly of claim 1, wherein the torque limiting assembly includes an axial spring configured to bias the rotor plate toward the rotor so as to releasably connect the rotor to the motor output shaft.

5. The electrically actuated variable camshaft timing assembly of claim 1, wherein the torque limiting assembly includes a tapered friction pad configured to engage a tapered notch in the rotor.

6. The electrically actuated variable camshaft timing assembly according to claim 1, wherein the electrically actuated variable camshaft timing assembly further comprises: The torque limiting assembly includes a friction plate applied to the axial surface of the rotor.

7. The electrically actuated variable camshaft timing assembly of claim 1, wherein the torque limiting assembly includes a spring configured to engage the axial surface of an electric motor bearing.

8. An electrically actuated variable camshaft timing assembly, comprising: An electric motor is configured to control the variable camshaft timing assembly, the electric motor including a rotor and an electric motor output shaft; The gearbox assembly includes an input terminal connected to the output shaft of the electric motor and an output terminal configured to be connected to the camshaft of an internal combustion engine; as well as A torque limiting component, comprising: A rotor plate, connected to the output shaft of the motor such that the rotor plate maintains a fixed angular position relative to the output shaft of the motor, the rotor plate including a radially outwardly extending flange having an axial surface that is axially biased to releasably engage with the axial surface of the rotor.

9. The electrically actuated variable camshaft timing assembly of claim 8, wherein the torque limiting assembly further comprises an axial spring.

10. The electrically actuated variable camshaft timing assembly of claim 8, wherein the rotor plate further comprises an integral spring.

11. The electrically actuated variable camshaft timing assembly of claim 8, wherein the electrically actuated variable camshaft timing assembly further comprises a friction plate applied to the axial surface of the rotor.

12. An electrically actuated variable camshaft timing assembly, comprising: An electric motor is configured to control the variable camshaft timing assembly, the electric motor including a rotor and an electric motor output shaft; A gearbox assembly, including an input terminal coupled to the output shaft of the electric motor, and an output terminal configured to be coupled to the camshaft of an internal combustion engine; and Torque limiting assembly includes a rotor plate fixed to the rotor, the rotor plate including one or more friction surfaces configured to: The rotor is releasably coupled to the motor output shaft to prevent angular displacement of the rotor relative to the motor output shaft when the torque applied to the motor output shaft is less than or equal to the torque limit, and When the torque applied to the output shaft of the motor exceeds the torque limit, the rotor is separated from the output shaft of the motor to allow angular displacement of the rotor relative to the output shaft of the motor.

13. The electrically actuated variable camshaft timing assembly of claim 12, wherein the rotor includes one or more slots engaging with the rotor plate to prevent angular displacement of the rotor relative to the rotor plate.

14. The electrically actuated variable camshaft timing assembly of claim 12, wherein one or more friction surfaces are applied to the inner diameter of the rotor plate or the outer diameter of the motor output shaft.

15. The electrically actuated variable camshaft timing assembly of claim 12, wherein one or more friction surfaces are applied to the axial surface of the motor bearing or the axial surface of the rotor plate.

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