PATENT DOCUMENT

Publication Number: US-11953080-B1
Application Number: US-202217879160-A
Country: US
Kind Code: B1

Title: Shaft with surface finished ridges

Abstract:
A ball screw spline actuator includes a shaft, a ball nut, and a ball spline. The shaft includes a helical groove and a spline groove intersecting the helical groove forming intersections having a least one ridge including a first surface finish formed by a first manufacturing operation. The ridge is subsequently reformed through a second manufacturing operation to include a second surface finish to reduce stress concentrations in the ridge from cyclical loading from at least one of the ball nut or the ball spline. In one example, the second manufacturing operation reforms the ridge to include a surface finished edge.

Claims:
What is claimed is: 
     
       1. A ball screw spline actuator, comprising:
 a shaft having a longitudinal axis, the shaft defining a helical groove extending along the shaft and a spline groove extending along the shaft, each of the helical groove and the spline groove having a first surface finish, the spline groove intersecting the helical groove at a plurality of intersections each defining a ridge having a second surface finish different than the first surface finish; 
 a ball nut engaged with the helical groove configured to apply a first torque to the shaft about the longitudinal axis; and 
 a ball spline engaged with the spline groove configured to apply a second torque to the shaft about the longitudinal axis to counteract the first torque to the shaft preventing a rotation of the shaft about the longitudinal axis and allowing the shaft to linearly translate along the longitudinal axis relative to the ball nut and the ball spline, 
 wherein the helical groove or the spline groove comprise an arcuate cross-section, 
 wherein the ridge further comprises:
 curved sidewalls formed by the helical groove and the spline groove adjacently positioned to the helical groove, and 
 an edge formed by a convergence of the curved sidewalls, 
 
 wherein the edge is reformed to include the second surface finish defining a surface finished edge configured to reduce a stress concentration in the ridge as a result of a cyclical load applied by the ball nut or the ball spline, and 
 wherein the surface finished edge comprises a radius formed between the curved sidewalls. 
 
     
     
       2. The ball screw spline actuator of  claim 1  wherein the arcuate cross-section comprises a semi-circular arc. 
     
     
       3. The ball screw spline actuator of  claim 1  wherein the edge and the first surface finish are formed by a first manufacturing operation and the radius is formed by removal of at least a portion of the edge in a second manufacturing operation subsequent to the first manufacturing operation to form the radius. 
     
     
       4. The ball screw spline actuator of  claim 1  wherein the surface finished edge comprises a tumbled edge. 
     
     
       5. The ball screw spline actuator of  claim 4  wherein the tumbled edge is formed through vibratory tumbling of the shaft with a deburring media. 
     
     
       6. The ball screw spline actuator of  claim 1 , wherein the ball screw spline actuator is configured as a suspension actuator having a housing connected to a vehicle body of a vehicle, the ball nut is rotatably connected to the housing and the ball spline is connected to the housing, the suspension actuator is configured to form a load path between the vehicle body of the vehicle and an unsprung mass component of the vehicle, wherein the shaft is configured to linearly translate along the longitudinal axis relative to the vehicle body allowing a relative movement between the vehicle body and the unsprung mass component of the vehicle. 
     
     
       7. The ball screw spline actuator of  claim 6 , wherein the suspension actuator further comprises:
 a ball screw actuator including a motor connected to the housing configured to rotate the ball nut about the longitudinal axis to linearly translate the shaft along the longitudinal axis. 
 
     
     
       8. The ball screw spline actuator of  claim 7 , wherein the motor further comprises:
 a stator connected to the housing; and 
 a rotor configured to rotate about the longitudinal axis relative to the stator, the rotor is connected to the ball nut to rotate in unison about the longitudinal axis; and wherein the ball screw actuator further comprises: 
 a thrust bearing connected to the housing and engaged with the ball nut, the thrust bearing configured to allow the ball nut to rotate about the longitudinal axis and remain axially stationary along the longitudinal axis relative to the housing. 
 
     
     
       9. The ball screw spline actuator of  claim 1 , wherein the surface finished edge is formed by abrasive blasting. 
     
     
       10. The ball screw spline actuator of  claim 1 , wherein the surface finished edge is formed by polishing. 
     
     
       11. The ball screw spline actuator of  claim 1 , wherein the surface finished edge is formed by sanding. 
     
     
       12. A ball screw spline actuator, comprising:
 a shaft having a longitudinal axis, the shaft defining a helical groove and a spline groove each having an arcuate cross-section and extending along the shaft, the spline groove intersecting the helical groove at a plurality of intersections forming four ridges each having a surface finished edge extending into each intersection configured to reduce a stress concentration in the ridges when placed under a cyclical load; 
 a ball nut engaged with the helical groove configured to apply a first torque to the shaft about the longitudinal axis; and 
 a ball spline engaged with the spline groove configured to apply a second torque to the shaft about the longitudinal axis configured to linearly translate the shaft along the longitudinal axis relative to the ball nut and the ball spline and preventing rotation of the shaft about the longitudinal axis, 
 wherein each of the surface finished edges comprises curved sidewalls formed at a first time by the helical groove and the spline groove adjacently positioned to the helical groove, the curved sidewalls converging to define an edge, the surface finished edge formed at the edge at a second time subsequent to the first time, and 
 wherein the surface finished edge comprises a radius between the curved sidewalls. 
 
     
     
       13. The ball screw spline actuator of  claim 12  wherein the radius is formed by a polishing operation at the second time. 
     
     
       14. The ball screw spline actuator of  claim 12  wherein the surface finished edge comprises a tumbled edge. 
     
     
       15. The ball screw spline actuator of  claim 14  wherein the tumbled edge is formed through vibratory tumbling of the shaft with a deburring media at the second time. 
     
     
       16. The ball screw spline actuator of  claim 12 , wherein the ball screw spline actuator is configured as a suspension actuator having a housing connected to a vehicle body of a vehicle, the ball nut is rotatably connected to the housing and the ball spline is connected to the housing, the suspension actuator is configured to form a load path between the vehicle body and an unsprung mass component of the vehicle, wherein the shaft is configured to linearly translate along the longitudinal axis relative to the vehicle body allowing a relative movement between the vehicle body and the unsprung mass component of the vehicle. 
     
     
       17. The ball screw spline actuator of  claim 16 , wherein the suspension actuator further comprises a ball screw actuator comprising:
 a motor comprising:
 a stator connected to the housing; and 
 a rotor configured to rotate about the longitudinal axis relative to the stator, the rotor is connected to the ball nut to rotate in unison about the longitudinal axis; and 
 
 a thrust bearing connected to the housing and engaged with the ball nut, the thrust bearing configured to allow the ball nut to rotate about the longitudinal axis and remain axially stationary along the longitudinal axis relative to the housing. 
 
     
     
       18. The ball screw spline actuator of  claim 12 , wherein the surface finished edge is formed by abrasive blasting. 
     
     
       19. The ball screw spline actuator of  claim 12 , wherein the surface finished edge is formed by polishing. 
     
     
       20. The ball screw spline actuator of  claim 12 , wherein the surface finished edge is formed by sanding.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims the benefit of U.S. Provisional Application No. 63/247,816, filed Sep. 24, 2021, the contents of which are hereby incorporated by reference herein for all purposes. 
    
    
     TECHNICAL FIELD 
     This application generally relates to ball screw spline actuators. 
     BACKGROUND 
     Ball screw spline actuators serve to provide flexibility to impart linear translation, rotation, or linear translation and rotation of a shaft engaged with a ball nut and a ball spline. 
     Actuators may serve to absorb forces received from surfaces through an unsprung mass. Active actuators may further serve to apply forces between the unsprung mass and a sprung mass to actively reduce vibrations. The actuators may experience a high number of cyclical movements and the internal components are subject to relatively high cyclical loads in operation. 
     SUMMARY 
     Disclosed is a ball screw spline actuator. In one example, the ball screw spline actuator includes a ball nut, a ball spline, and a shaft having a longitudinal axis. The shaft includes a helical groove engaged by the ball nut and a spline groove engaged by the ball spline allowing linear translational movement of the shaft and preventing rotation. The shaft helical groove and spline groove intersect at a plurality of intersections that each define at least one ridge. In one example, the helical groove and the spline groove have a first surface finish and the at least one ridge is configured to have a second surface finish that is different from the first surface finish. 
     In one example, the helical groove and the spline groove include arcuate cross-sections and the at least one ridge includes curved sidewalls defining an edge formed by the convergence of the curved sidewalls. The ridge and the edge are initially formed with the first surface finish. The edge is subsequently reformed to include the second surface finish defining a surface finished edge that is configured to reduce a stress concentration in the ridge as a result of a cyclical load applied by at least one of the ball nut or the ball spline. 
     In another example, the helical groove and the spline groove intersect at a plurality of intersections forming four ridges each having a surface finished edge formed at a first time. The surface finished edge is configured to reduce a stress concentration in the ridge when placed under a cyclical load applied by at least one of the ball nut or the ball spline. In one example, each ridge includes curved sidewalls converging at an edge that are formed at a first time. The surface finished edge is formed at the edge at a second time subsequent to the first time. 
     In one example, the surface finished edge includes a radius formed at the second time. In another example, the surface finished edge includes a tumbled edge formed at the second time. 
     In one example, the ball screw spline actuator is configured as a suspension actuator having a housing connected to a vehicle body of a vehicle. The ball nut is rotatably connected to the housing and the ball spline is connected to the housing. The suspension actuator is configured to form a load path between a vehicle body of a vehicle and an unsprung mass component of the vehicle. The shaft linearly translates along the longitudinal axis relative to the vehicle body allowing relative movement between the vehicle body and the unsprung mass component of the vehicle. 
     Also disclosed is a method for manufacturing a ball screw spline actuator. In one example, a shaft is provided including a longitudinal axis. A helical groove and a spline groove are formed in the shaft by a first manufacturing operation. The spline groove intersects the helical groove at a plurality of intersections each forming at least one ridge having an edge in the first manufacturing operation. In one example, each ridge is reformed in a second manufacturing operation to include a surface finished edge configured to reduce a stress concentration in the at least one ridge when the ridge is placed under a cyclical load. 
     In one example of the method, a ball nut is engaged with the helical groove and a ball spline is engaged with the spline groove. In one example, the ball screw spline actuator is configured as a suspension actuator for a vehicle operable to linearly translate the shaft relative to a sprung mass component of the vehicle without rotation of the shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic block diagram of a vehicle and example vehicle systems. 
         FIG.  2    is a cross-sectional view of one example of a suspension actuator including an air spring. 
         FIG.  3    is a cross-sectional view of another example of a suspension actuator including a coil spring. 
         FIG.  4 A  is a schematic front view of an example of a ball screw spline actuator. 
         FIG.  4 B  is an enlarged partial cross-sectional view taken along line  4 B- 4 B in  FIG.  4 A . 
         FIG.  4 C  is an enlarged partial cross-sectional view taken along line  4 C- 4 C in  FIG.  4 A . 
         FIG.  5    is an enlarged view of the intersection area A in  FIG.  4 A  including a first surface finish or following a first manufacturing operation. 
         FIG.  6    is a cross-sectional view taken along line  6 - 6  in  FIG.  5   . 
         FIG.  7    is an enlarged view of the intersection area A in  FIG.  4 A  including a second surface finish or following a second manufacturing operation. 
         FIG.  8    is a cross-sectional view taken along line  8 - 8  in  FIG.  7   . 
         FIG.  9    is a schematic block diagram of an example of a method for manufacturing a ball screw spline actuator. 
     
    
    
     DETAILED DESCRIPTION 
     Actuators are used in applications to impart relative motion between two components. Ball screw spline actuators may be used to impart either relative linear translation, rotation, or linear translation and rotation of a shaft relative to another component. 
     Suspension actuators used in vehicles form a load path between an unsprung mass, for example the vehicle wheel assemblies, and a sprung mass, for example the vehicle body. In one example of a suspension actuator, the load path includes a first load path provided by an air spring or a coil spring that absorbs some loads or vibrations and serves to set the riding height of the vehicle. The load path includes a second load path provided by a ball screw spline actuator that serves to absorb high-frequency vibrations or loads received by the suspension actuator from, for example, the road surface while the vehicle is in motion. 
     One example of a ball screw spline actuator configured as a suspension actuator for a vehicle includes an electric motor used to rotate a ball nut (or ball screw nut), which causes linear motion of a shaft that is engaged with the ball nut. Linear motion of the shaft occurs because the ball nut is restrained from linear motion and the shaft is restrained from rotating. As an example, a ball spline (or ball spline nut) can engage one or more linear grooves that are formed in the shaft that applies a reaction torque that restrains rotation of the shaft. This restraint from rotation causes linear translation of the shaft relative to the ball nut, the ball spline, and the vehicle body. The linear translation of the shaft relative to the vehicle body serves to absorb or dampen vibrations or energy between the vehicle wheels and the vehicle body resulting in less movement felt by occupants of the vehicle. 
     Due to the high mass of the vehicle and imperfections in the surface of roadways, the suspension actuators undergo high duty cycles imparting significant cyclical loads (i.e., forces) on the internal components of the ball screw spline actuator. Over the life cycle of the suspension actuator, the frequent and large cyclical loads on the suspension actuator can cause wear and damage to even hardened metal components reducing the optimal performance of the internal components and overall performance and effectiveness of the suspension actuator. 
       FIG.  1    is a block diagram that shows a vehicle  100  and example vehicle systems. As an example, the vehicle  100  may be a conventional road-going vehicle that is supported by wheels and tires (e.g., four wheels and tires). As an example, the vehicle  100  may be a passenger vehicle. As another example, the vehicle  100  may be a vehicle used to primarily carry and transport cargo. As another example, the vehicle may be a two-wheeled or three-wheeled vehicle. 
     In the illustrated example, the vehicle  100  includes several systems including a vehicle body  101 , a suspension system  102  including suspension actuators (discussed further below) and wheels, a propulsion system  103 , a braking system  104 , a steering system  105 , a sensing system  106 , and a control system  107 . Additional or alternate systems may be included in the vehicle  100 . 
     The vehicle body  101  is a structural component of the vehicle  100  through which other components are interconnected and supported. The vehicle body  101  may, for example, include or define a passenger compartment for carrying passengers. The vehicle body  101  may include structural components (e.g., a frame, subframe, unibody, monocoque, etc.) and aesthetic components (e.g., exterior door and body panels). 
     The suspension system  102  supports a sprung mass of the vehicle  100 , for example the vehicle body  101 , with respect to an unsprung mass of the vehicle  100 , for example the wheels. In one example, the suspension system  102  is an active suspension system that is configured to control generally vertical motion of the wheels. Broadly speaking, the suspension system  102  controls vertical motion of the wheels of the vehicle  100  relative to the vehicle body  101 , for example, to ensure contact between the wheels (e.g., tires) and a surface of the roadway and to reduce or absorb undesirable movements of the vehicle body  101 . 
     The suspension system  102  may be active through user settings and/or sensing system  106 . In one example, the suspension system  102 , in part through the ball screw spline actuators described below, is able to be set to certain conditions or preferences by a user. In one example, a user may select a suspension sport or performance mode where the vehicle ride handling is firmer and more responsive, or a comfort mode where the ride handling of the suspension system  102  absorbs more vibrations from the unsprung mass for a smoother ride by occupants positioned in the vehicle body  101 . In alternate or additive features of an active suspension system, the suspension system  102  through suspension actuators  212  may be predictive and/or reactive to vehicle body conditions or roadway conditions detected by the sensing system  106 . 
     The suspension system  102  includes suspension actuators  212  that are configured to transfer energy into and absorb energy from the wheels, such as by applying upward and downward forces to introduce energy into and absorb energy from the wheels. The components of the suspension system  102  may be operated in accordance with signals from sensors in the sensing system  106  and under control from the control system  107 , for example, in the form of commands transmitted from the control system  107  to the suspension system  102  and suspension actuators  212 . 
     The propulsion system  103  includes propulsion components that are configured to cause motion of the vehicle  100  (e.g., accelerating the vehicle  100 ). The propulsion system  103  may include motors and associated propulsion components such that are operable to generate torque and deliver that torque to the wheel that are in contact with the roadway. Motors included in the propulsion system  103  may be, as examples, an internal combustion engine powered by a combustible fuel, or one or more electric motors that are powered by electricity (e.g., from a battery). 
     The braking system  104  provides deceleration torque for decelerating the vehicle  100 . The braking system  104  may include friction braking components such as disk brakes or drum brakes. The braking system  104  may use an electric motor of the propulsion system  103  to decelerate the vehicle by electromagnetic resistance, which may be part of battery charging in a regenerative braking configuration. 
     The steering system  105  is operable to cause the vehicle to turn by changing a steering angle of one or more of the wheels of the vehicle  100 . 
     The sensing system  106  includes sensors for observing external conditions of the environment around the vehicle  100  (e.g., location of the roadway and other objects) and conditions of the vehicle  100  (e.g., acceleration and conditions of the various systems and their components). The sensing system  106  may include sensors for detecting conditions inside the vehicle, for example the position or distribution of the occupants of the vehicle body. The sensing system  106  may include sensors of various types for various vehicle functions. For example, the suspension system  102  and the suspension actuators may include sensors, or portions of the suspension actuators may function as sensors by measuring current draw of an electric motor in the actuator. Other sensors, and sensors for other functions, may be used. 
     The control system  107  includes communication components (i.e., for receiving sensor signals and sending control signals) and processing components (i.e., for processing the sensor signals and determining control operations), such as a controller. The control system  107  may be a single system or multiple related systems. For example, the control system  107  may be a distributed system including components that are included in other systems of the vehicle  100 , such as the suspension system  102  including the suspension actuators, the propulsion system  103 , the braking system  104 , the steering system  105 , the sensing system  106 , and/or vehicle other systems. Other control systems, control system components, and control system functions may be used or included. 
     Referring generally to the  FIGS.  2 ,  3 , and  4 A  examples, a ball screw spline actuator  216  is shown in one application configured as a suspension actuator  212  of a vehicle  100  ( FIGS.  2  and  3   ). The suspension system  102  includes the suspension actuator  212  that controls the motion (e.g., translation in the generally vertical direction) of the wheels. In the example of the ball screw spline actuator  216  configured as a suspension actuator  212 , each suspension actuator  212  is an active suspension component that is operable to actively apply forces to a wheels (or components connected to the wheels) as previously described. The suspension actuator  212  may be connected so that it is able to apply forces between the wheel and the vehicle body  101 , whether connected directly or indirectly to the wheel assembly and/or the vehicle body  101 . In one example, an upper end of the suspension actuator  212  is connected to the vehicle body  101  and a lower end of the suspension actuator  212  is connected to a control arm of the suspension system  102  or other components, for example a wheel hub or other component that is connected to the wheel hub, for example a steering knuckle. Other suspension system  102  and/or suspension actuator  212  configurations, components and connections may be used. 
       FIG.  2    is a schematic cross-section view of the suspension actuator  212 , in an example configuration including an air spring  214 . The air spring  214  provides a first load path for the suspension actuator  212  between the vehicle body  101  and the vehicle unsprung mass, for example including a vehicle wheel. The suspension actuator  212  also defines a second load path between the vehicle body  101  and the unsprung mass through a ball screw spline actuator  216 . The first load path is configured to carry a gravity preload of the vehicle  100  (i.e., load due to gravity irrespective of any dynamic loading) along with a portion of a dynamic load between the vehicle body  101  and the unsprung mass. The second load path is configured to carry another portion of the dynamic load between the vehicle body  101  and the unsprung mass and, as compared to the first load path, provides primary damping functions of the suspension system  102 . 
     As further described below, the suspension actuator  212  is able to axially extend (e.g., lengthen) and retract (e.g., shorten) along a longitudinal axis  218  in response to loads or vibrations received through the unsprung mass and/or as applied by the suspension actuator  212  to the unsprung mass. 
     In one example, suspension actuator  212  includes a housing for positioning and connecting of internal components of the suspension actuator  212 . Referring to the  FIG.  2    example, the suspension actuator  212  includes a first housing part  219  and a second housing part  220 . The first housing part  219  and the second housing part  220  are generally cylindrical structures that extend along the longitudinal axis  218  of the suspension actuator  212 . The first housing part  219  extends from the upper end of the suspension actuator  212  along the longitudinal axis  218  toward the second housing part  220 . The second housing part  220  extends upward from the lower end of the suspension actuator  212  along the longitudinal axis  218  of the suspension actuator  212  toward the first housing part  219 . 
     A top mount  222  is connected to the upper end of the first housing part  219 . The top mount  222  is configured so that it is connectable (e.g., by fasteners, by a clamping structure, by a pin, by a ball joint, or by another fastening structure) to part of the sprung mass of the vehicle  100 , such as the vehicle body  101 , to transfer forces between the sprung mass of the vehicle  100  and the suspension actuator  212 . A bottom mount  223  is connected to the lower end of the second housing part  220 . The bottom mount  223  is configured so that it is connectable (e.g., by fasteners, by a clamping structure, by a pin, by a ball joint, or by another fastening structure) to part of the unsprung mass of the vehicle  100 , such as a control arm or a wheel hub, to transfer forces between the unsprung mass of the vehicle  100  (e.g., including the wheels) and the suspension actuator  212 . 
     In the  FIG.  2    example including an air spring  214 , the first housing part  219  and the second housing part  220  are telescopically related so that they can move longitudinally with respect to each other along the longitudinal axis  218 . Thus, the first housing part  219  and the second housing part  220  define an overlapping section in the longitudinal direction, wherein the overlapping section has a variable length according to extension and retraction of the suspension actuator  212 . In the overlapping region, the first housing part  219  is spaced from the second housing part  220  in a radial direction (e.g., outward relative to a radial center of the suspension actuator  212 , for example the longitudinal axis  218 ) by a radial gap  224 . 
     In the  FIG.  2    example, an inner diameter of the second housing part  220  is larger than an outer diameter of the first housing part  219  in the overlapping region so that a portion of the first housing part  219  is located inside the second housing part  220  within the overlapping region to define the telescopic relationship of the first housing part  219  and the second housing part  220 . Alternatively, the first housing part  219  and the second housing part  220  may be configured so that an inner diameter of the first housing part  219  is larger than an outer diameter of the second housing part  220  in the overlapping region so that a portion of the second housing part  220  is located inside the first housing part  219  within the overlapping region to define the telescopic relationship as generally described. 
     In the  FIG.  2    example, the first load path is defined between the top mount  222  and the bottom mount  223  of the suspension actuator  212  by the air spring  214 . The air spring  214  is defined by an internal chamber  225  that is defined inside the suspension actuator  212 , including by the first housing part  219  and the second housing part  220 . The volume (e.g., the amount of space enclosed within the internal chamber  225  measured, for example, in cubic centimeters or other units) of the internal chamber  225  varies in accordance with relative movement of the first housing part  219  and the second housing part  220 . A working gas (e.g., air) is contained within the internal chamber  225  and increases and decreases in pressure in correspondence to relative movement of the first housing part  219  and the second housing part  220  and the accompanying change in volume of the internal chamber  225 . 
     The internal chamber  225  is sealed to contain the working gas within the internal chamber  225 , for example, by inclusion of sealing structures included in the suspension actuator  212  that are, for example, connected to the first housing part  219  and the second housing part  220 . The internal chamber  225  may include connections, for example, by valves, gas lines, and/or other structures, that allow supply of part of the working gas to the internal chamber  225  and allow discharge of part of the working gas from the internal chamber  225 . This allows, for example, changes in the ride height of the vehicle  100 . 
     To contain the working gas within the internal chamber  225  while allowing relative motion of the first housing part  219  and the second housing part  220  at the radial gap  224 , the air spring  214  may include an air spring membrane  226 . The air spring membrane  226  is a thin sheet of flexible material having an annular, tube-like configuration (e.g., a flexible sleeve). The air spring membrane  226  is connected to the first housing part  219  and the second housing part  220  at the radial gap  224  to prevent the working gas from escaping the internal chamber  225  at the radial gap  224  while allowing relative motion of first housing part  219  and the second housing part  220 . The air spring membrane  226  may also be referred to as an air spring sleeve, an air sleeve, a diaphragm, or an air sprint diaphragm. 
       FIG.  3    shows an alternate example of the suspension actuator  312  that replaces the air spring  214  with a coil spring  327  to provide the first load path for the suspension actuator  312 . The coil spring  327  is connected and is operable to provide the first load path in a similar manner as described for air spring  214 . In the  FIG.  3    example, the coil spring  327  includes an internal diameter larger than the outer diameter of a portion of an alternately configured first housing part  319  to receive the coil spring  327  in a coaxial orientation. Coil spring  327  is engaged to the first housing part  319  by a connector, for example through fasteners described above. An alternate implementation of the bottom mount  323  is used to connect the suspension actuator  312  to the unsprung mass of the vehicle as generally described for  FIG.  2   . In the example, the bottom mount  323  also serves to engage the coil spring  327 . Other components and configurations for positioning the coil spring  327  relative to the first housing part  319 , and engaging the coil spring  327  to the first housing part  319  and the unsprung mass, may be used. In another example, a second housing part (not shown) may be used in coordination with the coil spring  327  (e.g., to protect or shield the coil spring  327  from environmental elements) in a telescopic manner relative to the first housing part  319 . Other components, devices and configurations may be used to provide the first load path for suspension actuator  312 . 
     Referring to the schematic  FIGS.  2  and  3    suspension actuator  212 ,  312  examples (collectively referred to as suspension actuator  212  unless specifically noted), the ball screw spline actuator  216  in one example configured as the suspension actuator  212  is a type of linear actuator that is utilized in the suspension actuator  212  as an active suspension component that is operable to apply forces between the top mount  222  and the bottom mount  223  of the suspension actuator  212 . The ball screw spline actuator  216  is an example of a screw actuator, in which rotation of a screw or nut is used to cause linear motion of the other one of the screw or the nut, which translates with respect to the rotating component because it is restrained from rotating. The ball screw spline actuator  216  may be backdrivable so that it can allow extension and retraction of the suspension actuator  212  in response to external forces with minimal contrary force or assisting force applied by the ball screw spline actuator  216 . Although the description herein is made with respect to the ball screw spline actuator  216 , the suspension actuator  212  could be implemented using a screw actuator of another type, such as a lead screw actuator or other form of a linear motor device. Equally, the ball screw spline actuator  216  may be used in other applications other than in the suspension actuator  212 . 
     Referring to the  FIGS.  2 ,  3  and  4 A  examples, the illustrated ball screw spline actuator  216  includes a shaft  228 , a ball nut  230 , and a ball spline  236 . In the example of the ball screw spline actuator  216  configured as a suspension actuator  212 , the suspension actuator  212  further includes a ball screw actuator  231  including a motor having a rotor  232  and a stator  233 , and a thrust bearing (discussed further below). The suspension actuator  212  further includes a housing, and a shaft coupler  235  (discussed further below). 
     In one example, the shaft  228  is a round, hollow shaft or rod. In an alternate example, the shaft  228  is a round, solid shaft. Other shaft  228  shapes and configurations may be used. The shaft  228  includes a helical groove  238  formed radially inward toward the longitudinal axis  218  from an outer surface  240  of the shaft  228 . The helical groove  238  extends along the shaft  228  in the direction of the longitudinal axis  218  over the length of the shaft  228  (as illustrated). In an alternate example, the helical groove  238  extends over only a portion of the length of the shaft  228 . 
     The shaft  228  also includes a spline groove  242  formed radially inward toward the longitudinal axis  218  from the outer surface  240  of the shaft  228 . The spline groove  242  extends along the shaft in the direction of the longitudinal axis  218  over at least a portion of the length of the shaft  228  (as illustrated in  FIG.  4 A ). In an alternate example, the spline groove  242  extends along the entire length of the shaft  228 . In an alternate example, the spline groove  242  may include one or more spline grooves  242 , for example two of the spline grooves  242  configured parallel to one another in the direction of the longitudinal axis  218 . 
     Referring to the  FIGS.  4 B and  4 C  examples, the helical groove  238  and the spline groove  242  are each defined by a race (discussed further below) having a profile designed to provide conformal contact with a bearing  443 A, and a bearing  443 B (shown in phantom line), respectively, in a direction transverse to the groove axis (i.e., in a direction transverse to the rolling direction of the bearing, discussed further below). In one example, the helical groove  238  and the spline groove  242  include an arcuate cross-section (e.g., curved). In one example as best seen in  FIGS.  4 B and  4 C , the arcuate cross-section is a semi-circular arc or half circle (space between the bearing  443 A and the helical groove  238 , and the bearing  443 B and the spline groove  242  shown for ease of illustration only). The spline groove  242  is configured to intersect the helical groove  238  at a plurality of intersections  244  discussed further below. 
     In the  FIG.  2    example wherein the ball screw spline actuator  216  is configured as a suspension actuator  212 , the ball screw spline actuator  216  is at least partially disposed within a housing. In the  FIG.  2    example, the housing includes the first housing part  219  and the second housing part  220 . In one example, the suspension actuator  212  includes a ball screw actuator  231  having a motor including the rotor  232  and the stator  233 . The rotor  232  is a rotatable component in the form of a hollow, tubular structure that extends along the longitudinal axis  218  of the suspension actuator  212 . The stator  233  is arranged around and radially outward from the rotor  232 . Using any suitable motor-generator configuration, the rotor  232  and the stator  233  are configured such that electromagnetic interaction of the rotor  232  and the stator  233  causes rotation of the rotor  232  about the longitudinal axis  218  when the stator  233  is energized (e.g., by selective energization of stator coils that are included in the stator  233 ). Thus, the stator  233  is operable to rotate the rotor  232  as a result of electromagnetic interaction between the stator  233  and the rotor  232 . In one example, the motor having the rotor  232  and the stator  233  are components of the suspension actuator  212  but are not part of, or components of, the ball screw spline actuator  216 . 
     The stator  233  may be disposed in a stator housing. In addition to providing structural support for the stator  233 , the stator housing absorbs heat generated by the stator  233  when it is energized. Cooling features may be included in the ball screw actuator  231 , for example, adjacent to the stator housing. As one example, liquid channels may be defined around the stator housing that are defined on an outside periphery of the stator housing for circulating a liquid coolant that is able to absorb heat from the stator housing. 
     Referring to the  FIGS.  2  and  3    examples, the ball nut  230  is rotatably connected to the first housing part  219 , for example by connection to the rotor  232 , allowing rotation of the ball nut  230  relative to the first housing part  219 . Referring to the  FIG.  4 A  example of the ball screw spline actuator  216 , the ball nut  230  is connected to the rotor  232  and is rotated in unison with the rotor  232 . The ball screw actuator  231  further includes a thrust bearing  446  ( FIG.  4 A ) that is connected to the first housing part  219  and is engaged with the ball nut  230 . The thrust bearing  446  is configured to allow the ball nut  230  to rotate about the longitudinal axis  218  and remain axially stationary along the longitudinal axis  218  relative to the first housing part  219 . The ball spline  236  is connected to the first housing part  219 , does not axially move along the longitudinal axis  218 , and does not rotate about the longitudinal axis  218 . 
     Referring to the example of the ball screw spline actuator  216  shown in the  FIGS.  2 ,  3  and  4 A  examples, the ball nut  230  includes a plurality of the ball bearings  443 A configured in a recirculating path or groove within the ball nut  230 . The ball nut  230  is configured to engage the shaft  228  through positioning and engagement of the ball bearings  443 A in the helical groove  238 . The ball spline  236  includes a plurality of the ball bearings  443 B configured in a recirculating path or groove within the ball spline  236 . The ball spline  236  is configured to engage the shaft  228  through positioning and engagement of the ball bearings  443 B in the spline groove  242 . Although the ball spline  236  is illustrated as positioned directly adjacent to and below the ball nut  230 , other configurations, positions, and orientations of the ball nut  230  and the ball spline  236  relative to each other, and relative to the shaft  228 , and the first housing part  219 , may be used. 
     In the  FIGS.  2 - 4 A  examples and as described above, the ball nut  230  is prevented from axial translation along the longitudinal axis  218 . As the ball nut  230  is rotated by the rotor  232  about the longitudinal axis  218 , the ball nut  230  through engagement of the shaft  228  through ball bearings  443 A in the helical groove  238 , applies a first torque on the shaft  228  about the longitudinal axis  218 . As the ball spline  236  is fixed in position axially and rotationally, the ball spline  236  through engagement of the shaft  228  through ball bearings  443 B in the spline groove  242  applies a second torque to the shaft  228 , counteracting the first torque applied by the ball nut  230 , preventing rotation of the shaft  228  about the longitudinal axis  218  allowing shaft  228  to linearly translate along the longitudinal axis  218  relative to the ball nut  230  and the ball spline  236 . 
     Thus, the shaft  228  is a linearly translatable shaft since it is able to translate linearly along longitudinal axis  218  relative to the ball nut  230  and the ball spline  236 . In the example of the ball screw spline actuator  216  configured as a suspension actuator  212 , the shaft  228  translates linearly relative to portions of the suspension actuator  212 , including the first housing part  219 . In the suspension actuator  212  example, the shaft  228  extends downward from the first housing part  219  to the shaft coupler  235 . The shaft coupler  235  connects the shaft  228  to the second housing part  220  near the lower end of the suspension actuator  212 . The shaft coupler  235  may connect the shaft  228  to the second housing part  220  so that the shaft  228  is not able to rotate or translate relative to the second housing part  220 , for example, using conventional fasteners, coupling structures, welds, or other means. Thus, the shaft  228  is connected to the second housing part  220 , or in the  FIG.  3    example, the alternate implementation of the bottom mount  323 , by a fixed connecting structure. 
     In one example configured as the suspension actuator  212 , the ball screw spline actuator  216  is configured to rotate the ball nut  230  and linearly translate the shaft  228  downward toward the unsprung component in response to control signals received from the control system  107  based on signals received from the sensing system  106 . In this example, the ball screw spline actuator  216  is configured to be backdrivable so external forces, for example upward forces from the unsprung component, for example the vehicle wheels, may linearly translate the shaft  228  upward toward the first housing part  219  without forced rotation of the ball nut  230  by the rotor  232  and the stator  233 . In another example, the ball screw spline actuator  216  is configured to alternately rotate the ball nut  230  in both directions about longitudinal axis  218  to linearly translate the shaft  228  downward or upward in response to control signals from control system  107  based on signals received from the sensing system  106 . Other configurations and functions of ball screw spline actuator  216  to translate the shaft  228  along longitudinal axis  218  may be used. 
     Referring to  FIGS.  4 A- 6   , an example of the ball screw spline actuator  216  is shown. As described above, the shaft  228  includes the helical groove  238  and the spline groove  242  which intersect forming the plurality of intersections  244 . As best seen in  FIGS.  5  and  6   , forming of the helical groove  238  and spline groove  242  may be made through machining operations or techniques (described further below). In one example for forming the helical groove  238 , a CNC milling machine having a cutter translates along an axis parallel to the longitudinal axis  218  of the shaft  228  and removes material from the shaft  228  while a lathe or turning device turns the shaft  228  along the longitudinal axis  218 . Alternately, a CNC lathe and a stationary cutter may be used in a similar manner. Similarly, forming of the spline groove  242  may be achieved using a CNC milling machine wherein the cutter is moved along the longitudinal axis  218  of the shaft  228  to form a straight groove. In one example, one or more spline grooves  242  may be formed in the shaft  228 . Other forms of machining devices and material removal operations or techniques may be used to form the helical groove  238  and the spline groove  242 . 
     In one example of ball screw spline actuator  216  including the shaft  228 , each of the helical groove  238  and the spline groove  242  may include an arcuate cross-section (e.g., curved) transverse to a groove axis  552  suitable for receipt and support of the ball bearings  443 A of the ball nut  230  and the ball bearings  443 B of the ball spline  236  as described above. In one example, the helical groove  238  and the spline groove  242  include an arcuate cross-section. Other configurations and cross-section shapes for the helical groove  238  and the spline groove  242  may be used. 
     As best seen in  FIGS.  5  and  6   , on forming of the helical groove  238  and the spline groove  242  having the arcuate cross-sections, at least one ridge (four shown as ridges  554  in  FIG.  5   ) forms extending into each of the plurality of intersections  244 , for example toward a center  556 . In an exemplary application where the ball screw spline actuator  216  is used in, or is configured as, a suspension actuator  212  in a vehicle  100 , significant and cyclical loads are applied to the ridges  554  by at least one of the ball bearings  443 A of the ball nut  230  traveling along the helical groove  238  or the ball bearings  443 B of the ball spline  236  traveling along the spline groove  242  as the shaft  228  linearly translates upward and downward along the longitudinal axis  218 . 
     Over hundreds of thousands, possibly millions, of suspension actuator  212  cycles (e.g., extension and retraction in length), wherein shaft  228  linearly moves relative to the first housing part  219  along the longitudinal axis  218 , and relative to the sprung component of the vehicle (e.g., the vehicle body  101 ), wear and damage can occur near or in the ridges  554  due to high stress concentrations formed near or in the ridges  554  due to the cyclical loads. Due to the high stress concentrations, or through fatigue of the shaft  228  material, portions of the ridges  554  can gradually wear, or fracture and separate from the ridges  554  and enter the helical groove  238  and the spline groove  242 . These fractured and separated fragments of the ridges  554  can cause wear or damage to the helical groove  238 , the spline groove  242 , the ball bearings  443 A, and the ball bearings  443 B. Premature wear in the helical groove  238 , the spline groove  242 , the ball bearings  443 A, or the ball bearings  443 B can reduce the performance and/or cause premature wear, spalling, or pitting of the ball screw spline actuator  216 , and thereby requiring repair or replacement of the suspension actuator  212 . Reductions in performance of the suspension actuator  212  may be felt by, for example, passengers seated in the vehicle body  101 . 
     Referring to the  FIGS.  4 B,  4 C,  5  and  6    example of the ball screw spline actuator  216 , each of the intersections  244  forms an intersection opening  558  and each of the helical groove  238  and the spline groove  242  form a groove opening  560  transverse to a groove axis  552 . The helical groove  238  includes a helical race  562  (i.e., the helical groove  238  contact surface) and the spline groove  242  includes a spline race  564  (i.e., the spline groove  242  contact surface). The ball bearings  443 A of the ball nut  230  engage and travel along the helical race  562  and the ball bearings  443 B engage and travel along the spline race  564  on rotation of the rotor  232  (or when backdriven) as described above. In one example wherein the helical groove  238  and the spline groove  242  cross-sections are semi-circle in form, the helical race  562  and the spline race  564  are semi-circular. Other arcuate or cross-section configurations for the helical groove  238  and the spline groove  242  may be used. In each intersection  244 , the intersecting helical race  562  and the spline race  564  define corners  566 . 
     As best seen in the  FIG.  6    example cross-section, each of the ridges  554  (four shown in  FIG.  5   ) includes curved sidewalls  668  formed by the helical groove  238  and the spline groove  242  adjacently positioned to the helical groove  238 . The curved sidewalls  668  converge to form an edge  670  having a first edge height  671 . In the  FIGS.  5  and  6    example, the shaft  228 , the helical groove  238 , the spline groove  242 , the ridge  554 , and the edge  670  are formed during a first manufacturing operation. In one example, the first manufacturing operation is commonly referred to as rough machining and may include one or more manufacturing and/or material removal devices, operations, and processes described above and/or suitable for the material of the shaft  228 . Alternate first manufacturing or machining operations may be used to remove material from the shaft  228  to form the helical groove  238  and the spline groove  242 , for example cutting, drilling, grinding, broaching, boring, and/or turning. Although described that the helical groove  238  may be formed in the shaft  228  prior to forming the spline groove  242 , the spline groove  242  may be formed in the shaft  228  prior to forming the helical groove  238 . It is also understood that although one of the grooves may be formed before the other, forming of the helical groove  238  and the spline groove  242  are considered to be formed in the first manufacturing operation as described. 
     In the  FIGS.  5  and  6    example, a first surface finish is imparted on the helical groove  238  (or helical race  562 ) and the spline groove  360  (or spline race  564 ), the ridge  554  (and curved sidewalls  668 ) and the edge  670 , by, or as a result of, the first manufacturing operation. In one example, the first surface finish is imparted at a first time during the first manufacturing operation. In the example best seen in  FIG.  6   , the edge  670  having the first surface finish is configured as pointed or relatively sharp as best seen in  FIG.  6   . In the example of the first manufacturing operation generating the first surface finish, the ridge  554 , and more acutely the edge  670 , when placed under the cyclical loads from at least one of the ball nut  230  (i.e., ball bearings  443 A, shown spaced from helical race  562  for ease of illustration only) or the ball spline  236  (i.e., ball bearings  443 B, shown spaced from spline race  564  for ease of illustration only), may develop high stress concentrations near or in the ridge  554  and is susceptible to wear and damage from the cyclical loads applied by the ball bearings  443 A and the ball bearings  443 B as described above. 
     Referring to the  FIGS.  7  and  8    example, at least a portion of each of the ridges  554  of the ball screw spline actuator  216  initially imparted with the first surface finish is subsequently configured to have a second surface finish (illustrated in darker line in  FIG.  7    than illustrated in  FIG.  5   ) that is different than the first surface finish. In one example, the ridge  554  is subject to forming (or reforming) the edge  670  to include the second surface finish defining a surface finished edge  774 . The surface finished edge  774  is configured to reduce a stress concentration in the ridge  554  caused by at least one of the ball nut  230  or the ball spline  236  as described above. In one example, the second surface finish is imparted or created at the edge  670  at a second time subsequent to the first time through a second manufacturing operation described further below. In an alternate example, the second surface finish and/or the surface finished edge  774  may be formed during the first manufacturing operation (e.g., either the ridge  554  is reformed to form the surface finished edge  774  during rough machining in the first manufacturing operation, or the first manufacturing operation includes both rough machining and precision machining steps or operations to form the second surface finish and/or the surface finished edge  774 ). 
     In an alternate example, at a second time subsequent to the first time described above, the surface finished edge  774  is formed at the edge  670  and is configured to reduce the stress concentration in the ridge  554  as described. In one example, the surface finished edge  774  is formed by a second manufacturing operation at the second time subsequent to the first manufacturing operation at the first time (i.e., the helical groove  238 , the spline groove  242 , the ridges  554 , the curved sidewalls  668 , and the edges  670  are formed at the first time by the first manufacturing operation). As described further below, the second manufacturing operation may include precision machining, grinding, deburring, sanding, polishing, lapping, and/or other precision manufacturing, material removal, or surface finishing operations or processes. In one example, the second manufacturing operation at the second time is performed sequentially subsequent to the first manufacturing operation at the first time in manufacturing of the shaft  228 . 
     In the example cross-section shown in  FIG.  8   , the surface finished edge  774  includes a radius  875  formed between the curved sidewalls  668 . In one example, a portion of the edge  670  is removed (or reformed) by the second manufacturing operation to form the radius  875  having a second edge height  876  ( FIG.  8   ) which is less than the first edge height  671  ( FIG.  6   , and shown in dashed line in  FIG.  8   ). In one example, the radius  875  is formed at the second time subsequent to the first time. In one example, the second manufacturing operation forming the radius  875  may include any one of, or a combination of, the second manufacturing operations or techniques described above. In one example, polishing (e.g., removal of a small amount of the shaft  228  material just at the edge  670  using a fine abrasive) may be used to form the radius  875 . In another example, machining or sanding (e.g., using a cutting tool or a coarse abrasive tool or media) at the edge  670  may be used to form the radius  875 . Thus, the radius  875  may be formed by removal of at least a portion of the edge  670  in a second manufacturing operation subsequent to the first manufacturing operation to form the radius  875 . 
     In an alternate example of the surface finished edge  774 , removal (or reforming) of a portion of the edge  670  may include or result in a flat or planar portion (not shown), or other geometric shape or configuration, to remove or reform the edge  670  from a pointed or relatively sharp configuration ( FIG.  6   ) to a different configuration or form to reduce the stress concentration on the ridge  554  as described above. Although described as removal or reforming the edge  670  to form the surface finished edge  774 , the second surface finish and/or the surface finished edge  774  are not limited specifically to the edge  670  of the ridge  554 , but may also include the curved sidewalls  668  as well (not shown). In another example, the corners  566  may also be partially removed or reformed to include the second surface finish or be subjected to the second manufacturing operation. In other words, for example, the second surface finish, for example through the second manufacturing operation, can be used on other portions of the ridge  554  including the curved sidewalls  668 , and the portions of the helical race  562 , the spline race  564 , and/or the corners  566  positioned in the intersection  244 . 
     In another example, the surface finished edge  774  may be a tumbled edge. In one example, following forming of the helical groove  238  and the spline groove  242  (and therefore the intersections  244 ), the shaft  228  and the intersections  244  may be subject to the second manufacturing operation in the exemplary form of vibratory tumbling using a vibratory tumbler. In one example, the vibratory tumbling is conducted at a second time subsequent to the first time. In one example, the vibratory tumbler includes deburring media which contacts the ridges  554  to generate the second surface finish and/or form or reform the edge  670  to the surface finished edge  774  (e.g.,  FIG.  8   ) to reduce the stress concentration in the ridge  554  when the shaft  228  is subject to the cyclical loads from at least one of the ball nut  230  or the ball spline  236  as described above. Thus, the tumbled edge is formed through vibratory tumbling of the shaft  228  with a deburring media in the second manufacturing operation. 
     Referring to the  FIG.  7    example, in one example of the surface finished edge  774  in the form of the tumbled edge, the vibratory tumbler media is sized such that the tumbler media is small enough to enter the intersection  244  (i.e., the space or area defined by or in-between the four intersection openings  558 ) to contact and form or reform the portion of the ridges  554  to achieve the tumbled edge (i.e., the surface finished edge  774 ), but the tumbler media is too large to enter the groove opening  560  of the helical groove  238  and the spline groove  242  in areas of the grooves positioned outside of the intersection  244 . In this example, only the ridges  554 , or more locally only the edges  670 , are placed in contact with the tumbler media resulting in only the ridges  554 , or the edges  670 , including the second surface finish or reforming by the second manufacturing operation resulting in the surface finished edge  774 . 
     In another example, the tumbler media may be sized to also contact the helical groove  238  (e.g., the helical race  562 ) and the spline groove (e.g., the spline race  564 ) portions positioned in the intersections  244  to achieve the second surface finish or reforming due to the second manufacturing operation on these surfaces as well. In another example, the tumbler media may be sized to also contact the corners  566  to achieve the second surface finish or reforming through the second manufacturing operation resulting in the surface finished edge  774  on the corners  566 . Generating the second surface finish and/or reforming through the second manufacturing operation of these additional surfaces or structures in the intersection  244  may form a surface finished intersection  778  which reduces stress concentrations near or in the ridges  554  as described above. 
     In alternate examples, other second manufacturing operations generally described above can be used on the entirety of the shaft  228  (including the entirety of the helical groove  238  and spline groove  242 ), or more locally in the intersections  244 , or even more locally on the ridges  554  or the edges  670 , to achieve the second surface finish and/or the surface finished edge  774 . In one example, the second manufacturing operations are performed at the second time subsequent to the first time as described above. In one example, the entirety of the shaft  228  may be subject to an alternate second manufacturing operation, for example and alternate machining, deburring, sanding, and/or polishing process as described above. In another example, the ridges  554  or the edges  670  may be subject to an alternate second manufacturing operation through automated devices (for example the vibratory tumbler) or manual processes to achieve the second surface finish and/or the surface finished edge  774 . In one example, an automated CNC milling process may be used to reform the ridges  554  or the edges  670 . In another example, the intersections  244 , the ridges  554 , and/or the edges  670  may be subject to an alternate deburring or surface finishing process, for example localized bead blasting or sand blasting. In another example, the ridges  554  or the edges  670  may be hand sanded or polished to form or reform the edges  670  to achieve the second surface finish and/or the surface finished edge  774 . Other processes, techniques, or second manufacturing operations may be used to form the second surface finish and/or the surface finished edge  774  to reduce the stress concentrations near or in the ridges  554  as described above. 
     In another example of the ball screw spline actuator  216 , the ridges  554  are substantially or completely removed using one or more of the second manufacturing operations described. In the example, the second manufacturing operation is employed to substantially remove, or completely remove, the ridges  554 . In one example, the second manufacturing operation is a CNC milling operation using a cutter to remove shaft  228  material to remove the ridges  554 . Other of the second manufacturing operations described above may be used. In one example, removal of the ridges  554  configures the helical groove  238  (i.e., the helical race  562 ) and the spline groove  242  (i.e., the spline race  564 ) to be continuous and uninterrupted through the intersections  244 . Removal of the ridges  554  serves to eliminate any stress concentrations formed in the ridges or in the intersections  244  caused by the cyclical loads as described above. 
     Referring to  FIG.  9   , an example of a method  984  for manufacturing a ball screw spline actuator  216  is shown. As described above, one example of the ball screw spline actuator  216  includes the shaft  228 , ball nut  230 , and the ball spline  236  ( FIG.  4 A ). In the  FIG.  9    example, in step  986  the shaft  228  is provided. As described above, in one example the shaft  228  is a round, hollow shaft. 
     In step  988 , the helical groove  238  and the spline groove  242  are formed in the shaft  228  as described above. In the step  988 , the helical groove  238  and the spline groove  242  are formed in the first manufacturing operation. In one example, the helical groove  238  and the spline groove  242  are each configured to have an arcuate cross-section. In one example the helical groove  238  and the spline groove  242  are formed at a first time. The first manufacturing operation may include one or more of the manufacturing operations or processes described above. As described above, the spline groove  242  is configured to intersect the helical groove  238  at a plurality of intersections  244 . In one example, the formation of the helical groove  238  and the spline groove  242  form at least one of the ridges  554  each having an edge  670  in each intersection  244 . In the examples illustrated, each intersection  244  includes four ridges  554 . In one example described above, the helical groove  238 , the spline groove  242 , the ridges  554 , and the edges  670  include a first surface finish generated by the first manufacturing operation. 
     In example step  990 , the edges  670  of the ridges  554  are formed or reformed to include or achieve a surface finished edge  774  configured to reduce a stress concentration on the ridges  554 . In one example described above, the edge  670  is formed or reformed to the surface finished edge  774  through a second manufacturing operation subsequent to the first manufacturing operation. In another example, the edge  670  is formed or reformed to include the surface finished edge  774  at a second time subsequent to the first time. The second manufacturing operation may include one or more of the second manufacturing operations or processes described above. 
     As described above, the second manufacturing operation may be used on the shaft  228  in areas other than locally on the edge  670  of the ridge  554 . For example, the second manufacturing operation may be used, and the second surface finish formed, on the curved sidewalls  668  of the ridge  554 , as well as the helical groove  238  (i.e., the helical race  562 ), the spline groove  242  (i.e., the spline race  564 ), and/or corners  566  in the areas of the intersections  244 . Where the second manufacturing operation is used on the surfaces of the intersection  244  (i.e., the ridges  554 , the helical race  562  and the spline race  564 , a surface finished intersection  778  is formed). 
     In example step  992 , the ball nut  230  and ball spline  236  are engaged with the shaft  228 . As described above, the ball bearings  443 A of the ball nut  230  are engaged with the helical groove  238  and the ball bearings  443 B of the ball spline  236  are engaged with the spline groove  242  forming the ball screw spline actuator  216  ( FIG.  4 A ). As described above and illustrated in  FIG.  4 A , a thrust bearing  446 , or other bearing, may be engaged with the ball nut  230 . In one example of the ball screw spline actuator  216  configured as a suspension actuator  212 , the ball screw spline actuator  216  is then mounted to the housing, for example the first housing part  219  and the second housing part  220  ( FIGS.  2 ,  3   ), to form the suspension actuator  212  described and illustrated above. 
     In the method  984  for manufacturing the ball screw spline actuator  216 , the first manufacturing operation and the second manufacturing operation are completed on the shaft  228  prior to final material processing or finishing of the shaft  228 . In one example, the second manufacturing operation occurs during a final material machining operation, for example finish machining or grinding of the shaft  228  prior to material or surface hardening operations or process on the shaft  228 . In one example step (not shown), the shaft  228  is subject to one or more final finishing or manufacturing operations to complete the shaft  228 . 
     In an alternate example, the shaft  228 , the helical groove  238 , the spline groove  242 , the ridges  554 , and the edges  670  may be formed during the first manufacturing operation (i.e., rough machining as described above). The shaft  228  is then induction hardened, stresses relieved or reduced, and straightened. The outer surface of the shaft  228 , the ridges  554 , and/or the edges  670  are then subject to the second manufacturing operation as described above. In one example described, the edges  670  are reformed to form the surface finished edge  774  in the second manufacturing operation as described. 
     In one example step (not illustrated), subsequent to the second manufacturing operation, the shaft  228  is subject to a final finishing operation. In one example of the final finishing operation, the shaft  228  may undergo a heat treatment process to surface harden at least portions of the shaft  228 , for example surface harden the helical race  562  and the spline race  564  to reduce wear due to the cyclical loads applied by the ball bearings  443 A of the ball nut  230  and the ball bearings  443 B of the ball spline  236 . In alternate or additive final finishing operations, the helical race  562  and the spline race  564  may undergo a polishing operation to remove minor imperfections or further smooth the race surfaces to reduce wear and increase the life of the ball screw spline actuator  216 . Other final finishing or manufacturing operations may be used on shaft  228  subsequent to the second manufacturing operation. It is understood that alternate, or additional, steps for the method  984  may be used, and the steps may occur in a different order than as described and illustrated. It is also understood that one or more described steps may be removed from the method  984 . 
     As used in the claims, phrases in the form of “at least one of A, B, or C” should be interpreted to encompass only A, or only B, or only C, or any combination of A, B and C. 
     As described above, one aspect of the present technology is an active suspension system or active suspension actuator, which may be incorporated in or used in conjunction with a device that includes the gathering and use of data available from various sources. As an example, such data may identify a user and/or include user-specific settings or preferences for the vehicle suspension. The present disclosure contemplates that in some instances, this gathered data may include personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, twitter ID&#39;s, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, or any other identifying or personal information. 
     The present disclosure recognizes that the use of such personal information data, in the present technology, can be used to the benefit of users. For example, a user profile may be established that stores user preferences so that user settings can be applied automatically. Accordingly, use of such personal information data enhances the user&#39;s experience. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should occur after receiving the informed consent of the users. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations. For instance, in the US, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA); whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. Hence, different privacy practices should be maintained for different personal data types in each country. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data during registration for services or anytime thereafter. In another example, users can select not to provide data regarding usage of specific applications. In yet another example, users can select to limit the length of time that application usage data is maintained or entirely prohibit the development of an application usage profile. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an app that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing such personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, information needed to configure a device according to user preferences may be obtained each time the system is used and without subsequently storing the information or associating the information with the particular user.

Metadata:
Filing Date: 20220802
Publication Date: 20240409
Grant Date: 20240409
Priority Date: 20210924
Inventors: MOGHADDAM, SINA MOBASHER
CARTER, TROY A.
HALL, JONATHAN L.
Assignee: APPLE INC
CPC Classifications: [{"code": "F16H25/2214", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G17/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/44", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2204/62", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2206/80", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2800/162", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H2025/204", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H25/2214", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G17/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2206/80", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H2025/204", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2204/62", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2800/162", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/44", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/44", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/42", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2204/419", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2206/8111", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2206/80", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2600/182", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H25/2204", "inventive": true, "first": true, "tree": "[]"}, {"code": "F16H2025/2075", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H2025/2481", "inventive": false, "first": false, "tree": "[]"}, {"code": "F16H25/24", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 90575695