Drive train components with lightweight ball ramp mechanisms

Abstract

A vehicle powertrain component having a ball ramp mechanism, the ball ramp mechanism comprising a first ball ramp ring, a second ball ramp ring, and a plurality of balls. Each of the first ball ramp ring and the second ball ramp ring has a plurality of ball supports, the plurality of ball supports defining a ball track for receiving the balls. Each of the ball supports has a first radial width at a first position and a second radial width at a second position. The first width and the second width are different to minimize the amount of material forming the first ball ramp ring and the second ball ramp ring.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 912,714, filed on October 9, 2019. Technical Field

[0003] The present disclosure relates to a drive train component having a lightweight ball ramp mechanism. Background Art

[0004] This section provides background information related to the present disclosure which is not necessarily prior art.

[0005] Ball ramp mechanisms are commonly used in various driveline components, such as differentials, axle assemblies, power take-off units, and transfer cases, to generate thrust in response to relative rotational motion between a pair of ball ramp rings. The ball ramp rings of a ball ramp mechanism are typically disposed about an axis of rotation and have a diameter size related to the amount of thrust required. Conventional ball ramp mechanisms do not have ball ramp rings that are optimized to reduce their mass. This additional mass in the ball ramp rings of conventional ball ramp mechanisms is associated with additional cost and weight, which may be significant in situations where the diameter of the ball ramp rings is relatively large so that the ball ramp mechanism can provide a relatively large thrust. Summary of the invention

[0006] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0007] In one form, the present disclosure provides a vehicle powertrain component having a ball ramp mechanism including a first ball ramp ring, a second ball ramp ring, and a plurality of balls. The first ball ramp ring and the second ball ramp are concentrically disposed around an actuation axis. Each of the first ball ramp ring and the second ball ramp ring has a backing structure and a plurality of ball supports fixedly coupled to the backing structure. The backing structure defines a rear surface. The ball supports are circumferentially spaced around the actuation axis and extend forward of the backing structure. The ball supports cooperate to define a front face. Each of the ball supports defines a ball track. Each ball track has a first circumferential end disposed at a first dimension below the front face and a second circumferential end disposed at a second dimension below the front face that is smaller than the first dimension. Each of the ball tracks has a radial width that gradually decreases between the first circumferential end and the second circumferential end. Each of the balls is received in an associated one of the ball tracks and is movable between the first circumferential end and the second circumferential end of the associated one of the ball tracks. Each of the ball supports has a first radial width at a first location where the first circumferential end intersects the front face, and a second radial width at a second location where the second circumferential end intersects the front face. The first radial width is taken along a first line that passes through the actuation axis and through the center of an associated one of the balls located in the first circumferential end. The second radial width is taken along a second line that passes through the actuation axis and through the center of an associated one of the balls located in the second circumferential end.

[0008] In another form, the present disclosure provides a vehicle powertrain component having a ball ramp mechanism having a first ball ramp ring, a second ball ramp ring, and a plurality of balls. The first ball ramp ring and the second ball ramp are concentrically arranged around an actuation axis. Each of the first ball ramp ring and the second ball ramp ring defines a plurality of ball tracks. Each of the ball tracks has a middle track portion and a first track portion and a second track portion arranged on opposite sides of the middle track portion. The first ramp portion is configured to have a first ramp rate, and the second ramp portion is configured to have a second ramp rate different from the first ramp rate. Each of the balls is accommodated in an associated ball track in the first ball ramp ring and the second ball ramp ring. When the balls are arranged in the middle track portion, the first ball ramp ring relative to the second ball ramp ring in a first rotational direction drives the balls into the first track portion, thereby driving the first ball ramp ring and the second ball ramp ring to separate from each other at the first ramp rate. When the balls are disposed in the middle track portion, rotation of the first ball ramp ring relative to the second ball ramp ring in a second rotational direction opposite to the first rotational direction drives the balls into the second track portion, thereby driving the first ball ramp ring and the second ball ramp ring apart from each other at a second ramp rate.

[0009] In yet another form, the present disclosure provides a vehicle powertrain component including a ball ramp mechanism having a first ball ramp ring, a second ball ramp ring, and a plurality of balls. The first ball ramp ring and the second ball ramp ring are disposed about an actuation axis. Each of the first ball ramp ring and the second ball ramp ring defines a plurality of ball tracks. Each of the balls is received in an associated set of ball tracks in the first ball ramp ring and the second ball ramp ring. Each set of ball tracks is nested with at least one other set of ball tracks such that each set of ball tracks extends circumferentially around the first ball ramp ring and the second ball ramp ring on a sector of the first ball ramp ring and the second ball ramp ring, the central angle of the sector being greater than or equal to 360 degrees divided by the total number of sets of ball tracks.

[0010] In yet another form, the present disclosure provides a vehicle powertrain component including a ball ramp mechanism having a first ball ramp ring, a second ball ramp ring, and a plurality of balls. The first ball ramp ring and the second ball ramp ring are disposed about an actuation axis. Each of the first ball ramp ring and the second ball ramp ring defines a plurality of ball tracks disposed eccentrically about the actuation axis. Each of the balls is received in an associated set of ball tracks in the first ball ramp ring and the second ball ramp ring.

[0011] Further areas of applicability will become apparent from the description provided herein.The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0013] Figure 1 is a cross-sectional view of a first vehicle driveline component having a ball ramp mechanism constructed in accordance with the teachings of the present disclosure;

[0014] Figure 2 is a cross-sectional view of a portion of a second vehicle driveline component having a ball ramp mechanism constructed in accordance with the teachings of the present disclosure;

[0015] Figure 3 yes Figure 2 an exploded perspective view of a portion of a ball ramp mechanism;

[0016] Figure 4 yes Figure 2 A front view of a portion of a ball ramp mechanism;

[0017] Figure 5 is along Figure 4 a cross-sectional view taken along line 5-5 of ;

[0018] Figure 6 is along Figure 4 a cross-sectional view taken along line 6-6 of ;

[0019] Figure 7 yes Figure 2 A front view of a portion of a ball ramp mechanism illustrating a first ball ramp ring in greater detail;

[0020] Figure 8 is along Figure 4 a cross-sectional view taken along line 8-8 of ;

[0021] Fig. 9 is along Figure 4 a cross-sectional view taken along line 9-9 of ;

[0022] Fig.10 is along Figure 4 a cross-sectional view taken along line 10-10;

[0023] Fig.11 is along Figure 4 a cross-sectional view taken along line 11-11 of ;

[0024] Fig.12 is along Figure 4 a cross-sectional view taken along line 12-12 of ;

[0025] Fig.13 is along Figure 4 a cross-sectional view taken along line 13-13 of ;

[0026] Fig.14 is along Figure 4 a cross-sectional view taken along line 14-14 of ;

[0027] Fig.15 is along Figure 4 a cross-sectional view taken along line 15-15 of ;

[0028] Fig.16 is along Figure 4 a cross-sectional view taken along line 16-16 of ;

[0029] Fig.17A is a schematic diagram of an exemplary ball ramp mechanism having a bidirectional ball track with an asymmetric track portion;

[0030] Fig. 17B is with Fig.17A a similar schematic diagram but depicting a ball ramp mechanism operating on a first track section;

[0031] Fig. 17C is with Fig.17A a similar schematic diagram but depicting a ball ramp mechanism operating on a second track section;

[0032] Fig.18 and Fig.19 is a schematic diagram of an exemplary ball ramp mechanism having nested ball tracks configured in a nested eccentric manner and a concentric manner, respectively; and

[0033] Fig. 20 is a schematic diagram of an exemplary ball ramp mechanism having an eccentric ball track causing at least one ball ramp ring to move in an eccentric manner about an actuation axis.

[0034] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0035] refer to Figure 1 , an exemplary ball ramp mechanism constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral 10. The ball ramp mechanism 10 is shown in an exemplary vehicle powertrain component, which is illustrated as a rear axle assembly 12 having a housing 14, a ring gear 16, a differential assembly 18, a first output shaft 20 and a second output shaft 22, a first clutch assembly 24 and a second clutch assembly 26. Conventionally, the housing 14 defines a cavity 30 and a differential axis 32. The ring gear 16 is received in the cavity 30 and supported by the housing 14 for rotation about the differential axis 32. The ring gear 16 meshingly engages with an input pinion (not shown) that is received in the cavity 30 and supported by the housing 14 for rotation about a pinion axis (not shown) that is transverse to the differential axis 32.

[0036] The differential assembly 18 is disposed in the cavity 30 and includes a differential input 38 and a differential gear set 40. The differential input 38 is rotatable relative to the ring gear 16 about the differential axis 32 and provides rotational power to the differential gear set 40. The differential gear set 40 includes a pair of side gears 42 and 44 rotatable relative to the differential input 38 about the differential axis 32. The side gears 42 and 44 are the outputs of the differential assembly 18. The first output shaft 20 is rotationally coupled to the side gears 42, while the second output shaft 22 is rotationally coupled to the side gears 44. The first clutch assembly 24 is configured to selectively couple the differential input 38 to the ring gear 16 for rotation therewith.

[0037] The first clutch assembly 24 is configured to selectively disconnect the ring gear 16 from the differential assembly 18. The first clutch assembly 24 may include a first clutch 52 and a first actuator 52. The first clutch 50 may be any type of clutch, such as a friction clutch having an external clutch basket 54, a clutch hub 56, and a clutch pack 58. In the example provided, the external clutch basket 54 is a clutch input member and is coupled to the ring gear 16 for rotation therewith about the differential axis 32, the clutch hub 56 is coupled to the differential input 38 for common rotation about the differential axis 32, and the clutch pack 58 has two sets of clutch plates, each set of clutch plates being non-rotatably but axially slidably coupled to an associated one of the external clutch basket 54 and the clutch hub 56. The first actuator 52 may be any mechanism that can be configured to operate the first clutch 50, such as a hydraulic cylinder including a piston 64 movably mounted in a bore 66 of the housing 14. Pressurized hydraulic fluid may be employed to translate piston 64 in bore 66 to compress clutch pack 58 to drivingly couple clutch hub 56 to outer clutch basket 54 , thereby transferring rotational power from ring gear 16 to differential input 38 .

[0038] The second clutch assembly 26 is configured to limit the speed difference between the first output shaft 20 and the second output shaft 22. In the example provided, the second clutch assembly 26 includes a friction clutch 70 and a second actuator 72. The friction clutch 70 includes an external clutch basket 80, a clutch hub 82, and a clutch pack 84. The external clutch basket 60 is the input of the friction clutch 70 and is rotatably coupled to the differential input 38, while the clutch hub 82 is the output of the friction clutch 70 and is rotatably coupled to the second output shaft 22. The clutch pack 84 includes a plurality of first clutch plates 90 rotationally coupled to the external clutch basket 80 and a plurality of second clutch plates 92 interleaved with the first clutch plates 90 and rotatably coupled to the clutch hub 82.

[0039] The second actuator 72 includes a ball ramp mechanism 10, an auxiliary clutch pack 100, a pair of application plates 102, and an auxiliary actuator 104. The ball ramp mechanism 10 will be discussed in more detail below, but generally includes a first ball ramp ring 110, a second ball ramp ring 112, and a plurality of balls 114 disposed between the first ball ramp ring 110 and the second ball ramp ring 112 in a ball track or groove 116 formed in each of the first ball ramp ring 110 and the second ball ramp ring 112. The first ball ramp ring 110 and the second ball ramp ring 112 are concentrically arranged about an actuation axis (i.e., the differential axis 32 in the example provided) and are rotatable relative to each other about the actuation axis. The first ball ramp ring 110 and the second ball ramp ring 112 may be disposed radially between the outer clutch basket 82 and the clutch hub 84. The first ball ramp ring 110 may abut one of the second clutch plates 92 and may be rotatably coupled to the clutch hub 84. The auxiliary clutch pack 100 has a plurality of first friction plates non-rotatably coupled to the outer clutch basket 80 and a plurality of second friction plates interleaved with the first friction plates and non-rotatably coupled to the second ball ramp 112. The application plates 102 may be disposed on opposite axial ends of the auxiliary clutch pack 100 and may be coupled to the outer clutch basket 80 for rotation therewith. The auxiliary actuator 104 may be any type of actuator that causes relative axial movement between the application plates 102 to selectively squeeze the auxiliary clutch pack 100 therebetween. For example, the auxiliary actuator 104 may be configured as a hydraulic cylinder. However, in the example provided, the auxiliary actuator includes an annular electromagnet 120. The electromagnet 120 is fixedly coupled to the housing 14 and is configured to selectively generate a magnetic field that may pull the distal application plate 102 toward the auxiliary clutch pack 100 and the other (proximal) application plate 102 along the differential axis 32. When power is applied to the electromagnet 120 so that the electromagnet 120 generates a magnetic field, the distal application plate 102 responsively moves toward the electromagnet 120 and squeezes the auxiliary clutch pack 100 between itself (i.e., the distal application plate 120) and the proximal application plate 102 fixedly coupled to the outer clutch basket 80 to transfer the rotational power from the outer clutch basket 80 to the second ball ramp ring 112 through the auxiliary clutch pack 100. The magnitude of the torque transmitted through the auxiliary clutch pack 100 depends on the strength of the magnetic field. Therefore, the relative rotation amount between the first ball ramp ring 110 and the second ball ramp ring 112 can be controlled by changing the strength of the magnetic field generated by the electromagnet 120, and the relative rotation amount controls the axial distance that the ball ramp mechanism 10 can compress the clutch pack 84 of the friction clutch 70, thereby controlling the amount of torque passing through the friction clutch 70 between the differential input 38 and the second output shaft 22.

[0040] While the ball ramp mechanism 10 has been illustrated and described in conjunction with a rear axle assembly and operates in response to the application of a magnetic field, it should be understood that a ball ramp mechanism constructed in accordance with the teachings of the present disclosure may be incorporated into various other types of vehicle driveline components, such as transfer cases, transmissions, transaxles, and power take-off units (PTU's), and / or the ball ramp mechanism may operate in a variety of other ways, including via a rotary motor driving the first ball ramp ring and the second ball ramp ring relative to one of the other, either directly or through differential rotational motion imparted by meshing engagement of gears with one or both of the first ball ramp ring and the second ball ramp ring, or through magnetic fields or eddy currents applied to one or both of the first ball ramp ring and the second ball ramp ring.

[0041] exist Figure 2 In the example of FIG. 1 , a ball ramp mechanism 10a is shown in a PTU 200 and is configured to control the engagement of a friction clutch 202 disposed between a PTU input member 204 and a differential input member 206 of a front differential (not fully shown). The ball ramp mechanism 10a may be the same as the ball ramp mechanism 10 described above, except as described below.

[0042] Additional references Figure 3, a gear element such as a sector gear 210 is fixedly coupled to the first ball ramp ring 110a and includes a plurality of sector gear teeth 210a. In the example provided, the sector gear 210 is integrally formed with the first ball ramp ring 110a, but it should be understood that the sector gear 210 can be formed as a separate component and assembled to the first ball ramp ring 110a, or can be formed on the first ball ramp ring 110a (e.g., formed from plastic that is overmolded onto the first ball ramp ring 110a). The first ball ramp ring 110a is supported by the housing 14a of the PTU 200 for rotation about an actuation axis, which in the example provided happens to be the front differential axis 32a. The second ball ramp ring 112a is non-rotatably but axially slidably coupled to the housing 14a for movement along the actuation axis. In the particular example provided, the second ball ramp ring 112a includes an L-shaped lug 218 configured to be received in an axially extending groove 220 formed in the housing 14a. Each of the balls 114 is received in a set of associated ball tracks 116 in the first ball ramp ring 110a and the second ball ramp ring 112a. If desired, the balls 114 can be received in an annular retainer 224 that maintains the circumferential spacing of the balls 114 in a desired manner. The sector gear teeth 210a can mesh with an input gear 230 driven by a motor 232. In the example provided, the sector gear 210 is part of a spur gear, and the input gear 230 is another spur gear meshingly engaged with a worm gear. However, it should be understood that the sector gear 210 and the input gear 230 can be configured differently (e.g., as a helical gear or a worm gear and a worm, respectively), and a gear reduction can be used between the motor 232 and the input gear 230.

[0043] refer to Figure 3 , Figure 5 and Figure 7, each of the first ball ramp ring 110a and the second ball ramp ring 112a can be constructed in a mass-saving manner to have a backing structure 300, a plurality of ball supports 302, and an optional plurality of transition structures 304. The backing structure 300 defines an annular rear surface 310 configured to transmit thrust therethrough. If a gear element (e.g., a sector gear 210) is used, the gear element can be fixedly coupled to the backing structure 300. The ball supports 302 are circumferentially spaced about the actuation axis 32a and are fixedly coupled to the backing structure 300 to extend forwardly therefrom. The ball supports 302 on the first ball ramp ring 110 and the ball supports 302 on the second ball ramp ring 112 each cooperate to define an associated annular front face 330. Each of the ball supports 302 can define an associated one of the ball tracks 116. Each ball track 116 may have a first circumferential end 334 disposed at a first dimension below the front face 330 and a second circumferential end 336 disposed at a second dimension less than the first dimension below the front face 330. As shown in the example provided, the ball track 116 may continuously taper in the axial and radial directions between the first circumferential end 334 and the second circumferential end 336. Alternatively, the ball track 116 may be configured with a flat terrace (not shown) at one or both of the first circumferential end 334 and the second circumferential end 336. If included, each of the transition structures 304 may be fixedly coupled to the backing structure 300 and disposed circumferentially between and connecting a pair of ball supports 302.

[0044] refer to Figures 4 to 6 , each of the balls 114 is received in an associated one of the ball tracks 116 and is movable between a first circumferential end 334 and a second circumferential end 336 of the associated one of the ball tracks 116 .

[0045] refer to Figure 7 , each of the ball supports 302 has a first radial width at a first position where the first circumferential end 334 intersects the front face 330, and has a second radial width at a second position where the second circumferential end 336 intersects the front face 330. The first radial width is taken along a first line L1 passing through the actuation axis 32a and passing through the center of an associated one of the balls 114 in the first circumferential end 334. The second width is taken along a second line L2 passing through the actuation axis 32a and passing through the center of an associated one of the balls 114 located in the second circumferential end 336.

[0046] refer to Figures 8 to 16The outer radial surface 350 of each of the ball supports 302 may taper radially outward from the front face 330 toward the backing structure 300 . Also optionally, the inner radial surface 360 ​​of each of the ball supports 302 may taper radially inward from the front face 330 toward the backing structure 300 .

[0047] Back to Figure 7 Each transition structure 304 has a first transition portion 362 fixedly coupled to a first circumferential end 334 of a first one of a pair of ball supports 302, a second transition portion 364 fixedly coupled to a second circumferential end 364 of a second one of a pair of ball supports 302, and an intermediate transition portion 366 fixedly coupling the first transition portion 362 and the second transition portion 364 to each other. The radial width of the first transition portion 362 narrows as the circumferential distance from the second transition portion 364 decreases, wherein the radial width of the second transition portion 364 narrows as the circumferential distance from the first transition portion 362 decreases. The outer radial surface 370 of the first transition portion 362 and / or the outer radial surface 372 of the second transition portion 364 and / or the outer radial surface 376 of the intermediate transition portion 366 on each of the transition structures 304 may taper radially outward from the front face 330 toward the backing structure 300. Similarly, the inner radial surface 380 of the first transition portion 362 and / or the inner radial surface 382 of the second transition portion 364 and / or the inner radial surface 386 of the intermediate transition portion 366 on each of the transition structures 304 may taper radially inward from the front face 330 toward the backing structure 300 .

[0048] Compared to conventional ball ramp mechanisms having side walls perpendicular to the front and rear faces and the front face arranged in a uniform annular manner, the present arrangement not only significantly reduces the mass of the ball ramp ring, but also maintains the strength of the ball ramp ring where strength is required.

[0049] Although the ball ramp mechanism of the present disclosure has been illustrated and described as having a conventionally shaped ball track, it should be understood that the shape of the ball track may vary. FIG. 17A to FIG. 17C , the ball tracks 116 in the first ball ramp ring 110 and the second ball ramp ring 112 are schematically illustrated as having a middle track portion 500 that establishes a "low point" in the ball track 116 and a first track portion 502 and a second track portion 504 that extend from opposite sides of the middle track portion 500, respectively. The first track portion 502 is configured to have a first slope rate, and the second track portion 504 is configured to have a second slope rate that is different from the first slope rate. As used herein, the term "slope rate" refers to the change in axial width (in degrees) across the first ball ramp ring 110 and the second ball ramp ring 112. FIG. 17A to FIG. 17C=The distance that one of the balls 114 has traveled in its ball track 116 in the circumferential direction (in FIG. 17A to FIG. 17C is specified as movement in the X direction).

[0050] When the balls 114 are disposed in the intermediate track portion 500, the rotation of the first ball ramp ring 110 relative to the second ball ramp ring 112 in the first rotational direction drives the balls 114 into the first track portion 502, as shown in FIG. Fig. 17B As shown, the first ball ramp ring 110 and the second ball ramp ring 112 are driven to separate from each other at a first ramp rate. Similarly, when the balls 114 are disposed in the intermediate track portion 500, the first ball ramp ring 110 rotates relative to the second ball ramp ring 112 in a second rotational direction opposite to the first rotational direction to drive the balls 114 into the second track portion 504, as shown. Fig. 17C As shown, to drive the first ball ramp ring 110 and the second ball ramp ring 112 to separate from each other at a second ramp rate. The configuration performed in this manner allows one ramp rate to be used when the first ball ramp ring rotates relative to the second ball ramp ring in a first rotational direction away from the low point, and allows a different second ramp rate to be used when the first ball ramp ring rotates relative to the second ball ramp ring in an opposite second rotational direction away from the low point. In the example shown, the first ramp rate is higher than the second ramp rate, so that a given displacement between the first ball ramp ring 110 and the second ball ramp ring 112 can be achieved with a relatively small amount of rotation of the first ball ramp ring 110. This configuration may be beneficial in certain vehicle powertrain configurations where a clutch is operated to alternately enhance vehicle dynamics or provide enhanced propulsion. When a clutch is used to enhance vehicle dynamics, the power transmitted through the clutch may be relatively low in magnitude, but it is desired that the clutch can be actuated relatively quickly, and therefore, the first track portion 502 of the ball ramp mechanism can be used to operate the clutch. When a clutch is used to provide enhanced propulsion, the power transmitted through the clutch may be relatively high in magnitude. Longer actuation times are generally not a problem, so the second track portion 504 of the ball ramp mechanism may be used to operate the clutch. Because the second ramp rate is relatively less than the first ramp rate, a higher force output is possible for a given motor used to drive the first ball ramp ring 110.

[0051] Fig.18 and Fig.19 A ball ramp mechanism is described having a plurality of sets of ball tracks 116 that are relatively longer than the ball tracks of a conventional ball ramp mechanism. More specifically, Fig.18 and Fig.19Each set of ball tracks 116 in the example is nested with at least one other set of ball tracks 116 such that each set of ball tracks 116 extends circumferentially around the first ball ramp ring 110 and the second ball ramp ring 112 on a sector of the first ball ramp ring 110 and the second ball ramp ring 112, with the central angle 510 of the sector being greater than or equal to 360 degrees divided by the number of sets of ball tracks 116 used in the ball ramp mechanism.

[0052] exist Fig.18 In the example of FIG. 5 , each set of ball tracks 116 follows a spiral track rather than a semicircular track, such that one end of a given ball track 116 is disposed radially inward of a first one of the other sets of ball tracks 116, and an opposite end of the given ball track 116 is disposed radially outward of a second one of the other sets of ball tracks 116. Configuration in this manner (i.e., each set of ball tracks 116 is disposed eccentrically about the actuation axis 32) allows each set of ball tracks 116 to extend over a sector of the first ball ramp 110 and the second ball ramp 112 at a center angle 510 greater than 180 degrees, which is much greater than 120 degrees or greater than 360 degrees divided by the number of sets of ball tracks 116 used in the ball ramp mechanism (i.e., 360 degrees divided by 3).

[0053] refer to Fig.19 , the groups of ball tracks 116 are concentrically arranged around the actuation axis 32, but one or more groups of ball tracks 116 may be radially offset relative to one or more other ball tracks 116. In the example provided, each group of ball tracks 116 is radially offset from all other groups of ball tracks 116, and therefore, the central angle of the sector may be close to 360 degrees.

[0054] refer to Fig. 20 , the ball track 116 is eccentrically configured about the actuation axis 32 so that at least one of the first ball track ring 110 and the second ball track ring 112 can be moved in an eccentric manner about the actuation axis 32. This configuration can allow the eccentrically movable ball track ring to be used with an operator 520 to operate the operator 520. The operator 520 can be selected from a group of operators including sensors, switches, valves, pumps, and combinations of two or more thereof. It should be understood that "operation" of a sensor, switch, or valve is a change in the state of the sensor, switch, or valve, while "operation" of a pump may require movement of an element of the pump, such as discharging fluid from the pump. It should be understood that the eccentrically movable ball ramp ring can be used to rotate into proximity with the operator and / or to drive a portion of the operator using a radially directed actuation force, such as for causing a piston or rod associated with a sensor, switch, valve element, or pump (e.g., an axial piston pump) to translate the piston or rod in a direction transverse to the actuation axis 32.

[0055] For the purpose of illustration and description, the above description of the embodiment is provided. It is not intended to be exhaustive or limit the present disclosure. The individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable when applicable and can be used in selected embodiments, even if not specifically shown or described. The same situation can also be different in many aspects. Such variations should not be considered as departing from the present disclosure, and all such modifications are intended to be included in the scope of the present disclosure.

Claims

1. A vehicle powertrain component, comprising: A ball ramp mechanism having a first ball ramp ring, a second ball ramp ring and a plurality of balls, the first ball ramp ring and the second ball ramp ring being concentrically disposed about an actuation axis, each of the first ball ramp ring and the second ball ramp ring having a backing structure and a plurality of ball supports fixedly coupled to the backing structure, the backing structure defining a rear surface, the ball supports being circumferentially spaced about the actuation axis and extending forwardly from the backing structure, the ball supports cooperating to define a front face, each of the ball supports defining a ball track, each ball track having a first circumferential end disposed at a first dimension below the front face and a second circumferential end disposed at a second dimension below the front face, the second dimension being smaller than the first dimension, each of the ball tracks having a radial width tapering between the first circumferential end and the second circumferential end, each of the balls being received in an associated one of the ball tracks and being movable between the first circumferential end and the second circumferential end of the associated one of the ball tracks, wherein each of the ball supports has a first radial width at a first location where the first circumferential end intersects the front face, and has a second radial width at a second location where the second circumferential end intersects the front face, the first radial width being taken along a first line passing through the actuation axis and through a center of an associated one of the balls located in the first circumferential end, the second radial width being taken along a second line passing through the actuation axis and through a center of an associated one of the balls located in the second circumferential end, and each of the first ball ramp ring and the second ball ramp ring further comprises a plurality of transition structures, each of the transition structures being fixedly coupled to the backing structure and circumferentially disposed between a pair of ball supports in the ball supports, and Each transition structure has a first transition portion fixedly connected to the first circumferential end of the first one of the pair of ball supports, a second transition portion fixedly connected to the second circumferential end of the second one of the pair of ball supports, and an intermediate transition portion fixedly connecting the first transition portion and the second transition portion to each other, wherein the radial width of the first transition portion narrows as the distance from the second transition portion decreases, and wherein the radial width of the second transition portion narrows as the distance from the first transition portion decreases. 2 . The vehicle driveline component of claim 1 , wherein an outer radial surface of each of the ball supports tapers radially outwardly from the front face toward the backing structure. 3 . The vehicle powertrain component of claim 1 , wherein an inner radial surface of each of the ball supports tapers radially inwardly from the front face toward the backing structure.

4. The vehicle powertrain component of claim 1, wherein an outer radial surface of at least one of the first transition portion and the second transition portion on each of the transition structures tapers radially outward from the front face toward the backing structure.

5. The vehicle powertrain component of claim 1, wherein an inner radial surface of at least one of the first transition portion and the second transition portion on each of the transition structures tapers radially inwardly from the front face toward the backing structure.

6. The vehicle powertrain component of claim 1, wherein an outer radial surface of the intermediate transition portion of each of the transition structures tapers radially outward from the front face toward the backing structure.

7. The vehicle powertrain component of claim 1, wherein an inner radial surface of the intermediate transition portion of each of the transition structures tapers radially inwardly from the front face toward the backing structure. 8 . The vehicle powertrain component of claim 1 , wherein the first ball ramp ring further comprises a gear element fixedly coupled to the backing structure of the first ball ramp ring.

9. The vehicle driveline component of claim 8, wherein the gear element is a sector gear.

10. The vehicle powertrain component of claim 1 , further comprising a clutch having a clutch input member, a clutch output member, and wherein the clutch is selectively operable in a first mode in which the clutch input member is rotationally disconnected from the clutch output member and in a second mode in which the clutch output member is coupled to the clutch input member for rotation therewith, and wherein the operating mode of the clutch changes between the first mode and the second mode in response to relative rotational movement between the first ball ramp ring and the second ball ramp ring.

11. The vehicle driveline component of claim 10, wherein the clutch is a friction clutch.

12. The vehicle powertrain component of claim 11, further comprising a differential assembly and an output shaft, wherein the differential assembly includes a differential input and a first differential output and a second differential output, wherein the output shaft is coupled to one of the first differential output and the second differential output for rotation therewith, wherein the clutch input member is coupled to the differential input for rotation therewith, and wherein the clutch output member is coupled to the output shaft for rotation therewith.

13. The vehicle powertrain component of claim 11, further comprising a PTU input member and a PTU output member, wherein the PTU input member is configured to rotate about the actuation axis, the PTU output member is configured to rotate about a PTU output axis transverse to the actuation axis, and wherein the clutch is disposed in a torque transmission path between the PTU input member and the PTU output member.

14. A vehicle powertrain component, comprising: A ball ramp mechanism having a first ball ramp ring, a second ball ramp ring and a plurality of balls, the first ball ramp ring and the second ball ramp ring being concentrically arranged around an actuation axis, each of the first ball ramp ring and the second ball ramp ring defining a plurality of ball tracks, each of the ball tracks having a middle track portion and a first track portion and a second track portion arranged on opposite sides of the middle track portion, the first track portion being configured to have a first slope rate, the second track portion being configured to have a second slope rate different from the first slope rate, each of the balls being received in an associated ball track in the first ball ramp ring and the second ball ramp ring, and at least one of the first ball ramp ring and the second ball ramp ring further comprising a plurality of transition structures arranged circumferentially; wherein rotation of the first ball ramp ring relative to the second ball ramp ring in a first rotational direction when the balls are disposed in the intermediate track portion drives the balls into the first track portion to drive the first ball ramp ring and the second ball ramp ring apart from each other at the first ramp rate, and wherein rotation of the first ball ramp ring relative to the second ball ramp ring in a second rotational direction opposite to the first rotational direction when the balls are disposed in the intermediate portion drives the balls into the second track portion to drive the first ball ramp ring and the second ball ramp ring apart from each other at the second ramp rate, wherein each of the transition structures is circumferentially disposed between a pair of ball tracks in the pair of ball tracks and has a first transition portion fixedly coupled to a first circumferential end of a first one of the pair of ball tracks, a second transition portion fixedly coupled to a second circumferential end of a second one of the pair of ball tracks, and an intermediate transition portion fixedly coupling the first transition portion and the second transition portion to each other, and Wherein a radial width of the first transition portion narrows as a distance from the second transition portion decreases, and wherein a radial width of the second transition portion narrows as a distance from the first transition portion decreases.

15. A vehicle powertrain component, comprising: a ball ramp mechanism having a first ball ramp ring, a second ball ramp ring, and a plurality of balls, the first ball ramp ring and the second ball ramp ring being disposed about an actuation axis, each of the first ball ramp ring and the second ball ramp ring defining a plurality of ball tracks, each of the balls being received in an associated set of ball tracks in the first ball ramp ring and the second ball ramp ring; wherein each set of ball tracks is nested with at least one other set of ball tracks, so that each set of ball tracks extends circumferentially around the first ball ramp ring and the second ball ramp ring on a sector of the first ball ramp ring and the second ball ramp ring, and the central angle of the sector is greater than or equal to 360 degrees divided by the total number of sets of ball tracks, and Each set of ball tracks is concentric with but radially offset from at least one other set of ball tracks.

16. The vehicle powertrain component of claim 15, wherein each set of ball tracks is radially offset from each of the other sets of ball tracks.

17. A vehicle powertrain component, comprising: A ball ramp mechanism having a first ball ramp ring, a second ball ramp ring and a plurality of balls, wherein the first ball ramp ring and the second ball ramp ring are arranged around an actuation axis, each of the first ball ramp ring and the second ball ramp ring defines a plurality of ball tracks, the plurality of ball tracks are eccentrically arranged around the actuation axis so that a portion of one ball track is located radially inward of another ball track, each of the balls is received in an associated set of ball tracks in the first ball ramp ring and the second ball ramp ring, Wherein the vehicle powertrain component further comprises an operator selected from the group consisting of a sensor, a switch, a valve, a pump, and a combination of two or more thereof, and wherein the operator is operated by eccentric movement of the second ball ramp ring about the actuation axis.

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