HANDWHEEL ACTUATOR FOR STEERING SYSTEM

A handwheel actuator for a steering system includes a stator, a shaft, and a rotor. The shaft is disposed within the stator and configured to be rotatably driven by a handwheel. The rotor is rotatably driven by the shaft. The rotor and the stator form a first fluid chamber and a second fluid chamber. Rotation of the rotor is configured to displace from the first chamber to the second chamber so as to apply a rotational resistance to the shaft.

TECHNICAL FIELD

This disclosure is generally related to a handwheel actuator for a drive-by-wire steering system.

BACKGROUND

In a drive-by-wire application, a handwheel has no natural force feedback for a driver, and so without an additional mechanism or software, the driver input may feel unnatural depending on the driving condition compared to a convention steering system.

SUMMARY

An example embodiment of a handwheel actuator for a steering system is provided that includes a housing, a shaft disposed within the housing, and a rotary damper rotatably driven by the shaft about a rotational axis. The shaft is rotatably driven by the handwheel. The rotary damper and the housing form a first fluid chamber and a second fluid chamber. Rotation of the rotary damper in a first direction is configured to displace a fluid from the first fluid chamber to the second fluid chamber so as to apply a rotational resistance to the shaft. Rotation of the rotary damper in a second direction is configured to displace a fluid from the second fluid chamber to the first fluid chamber so as to apply a rotational resistance to the shaft.

In an example embodiment, the handwheel actuator further comprises a metered fluid passage arranged in the housing. In a further aspect, the metered fluid passage is electronically metered.

In an example embodiment, a fluid flow resistance of the metered fluid passage is controlled via an electronic fluid control valve.

In an example embodiment, the rotational resistance can be varied based on vehicle speed.

In an example embodiment, the first and second fluid chambers are ring-shaped.

In an example embodiment, rotary movement of the rotary damper is configured to move the fluid about the rotational axis.

In an example embodiment, the shaft is configured to be rotatably driven by the handwheel about the rotational axis of the rotary damper.

In an example embodiment, the first fluid chamber is sealingly separated from the second fluid chamber via the rotary damper.

In an example embodiment, a rotational range of the shaft is greater than a rotational range of the rotary damper.

In an example embodiment, the steering system includes a reduction arranged within the housing. The reduction can be a planetary gearset. The reduction can also be arranged between the shaft and the rotary damper such that the shaft drives the reduction and the reduction drives the rotary damper.

An example embodiment of a handwheel actuator for a steering system is provided that includes a housing, a rotary damper driven by a handwheel, and a metered fluid passage. The rotary damper and the housing define a first fluid chamber and a second fluid chamber which are fluidly connected to each other via the metered fluid passage. The first fluid chamber, the second fluid chamber, and the metered fluid passage define a variable resistance closed fluid system arranged within the housing. Rotation of the rotary damper causes displacement of a fluid within the variable resistance closed fluid system, that, in effect, applies a rotational resistance to the rotary damper.

In an example embodiment, the first fluid chamber is defined by a first side of the rotary damper and the housing, and the second fluid chamber is defined by a second side of the rotary damper and the housing.

In an example embodiment, the handwheel actuator includes a shaft disposed within the housing, and the shaft is drivably connected to the rotary damper.

An example embodiment of a handwheel actuator for a steering system is provided that includes a housing and a rotary damper driven by a handwheel. Rotation of the rotary damper causes an exchange of fluid between the first fluid chamber and the second fluid chamber, which, in effect, applies a rotational resistance to the rotary damper.

In an example embodiment, the handwheel actuator includes a metered fluid passage arranged between the first fluid chamber and the second fluid chamber, and a flow area of the metered fluid passage is electronically variable so as to vary the rotational resistance.

In an example embodiment, the handwheel actuator includes at least one spring that is disposed within the housing that returns the handwheel to a non-turning position.

DETAILED DESCRIPTION

FIG.1shows a perspective view of an example embodiment of a handwheel actuator100together with a handwheel10, often referred to as a steering wheel.FIG.2shows a perspective view of the handwheel actuator100.

FIG.3shows a cross-sectional view of the handwheel actuator100and the handwheel10taken fromFIG.1.FIG.4shows an exploded perspective view of the handwheel actuator100.FIG.5shows an exploded perspective view of a portion of the handwheel actuator100.FIGS.6A and6Bshow perspective views of the portion of the handwheel actuator100shown inFIG.5.FIG.7shows an exploded perspective view of an example embodiment of a rotary damper19and corresponding seals.FIG.8shows an exploded perspective view of an example embodiment of a housing24and sealing components of the housing.FIGS.9A and9Bshow perspective views of the housing24and sealing components.FIG.10Ashows an exploded perspective view of an example embodiment of a rear cover34and a rolling element bearing35.FIG.10Bshows a perspective view of the rolling element bearing35installed within the rear cover34.FIG.11shows a perspective view of an example embodiment of an electronic fluid control valve (EFCV)17for the handwheel actuator100.FIG.12Ashows a cross-sectional view of the EFCV17taken fromFIG.11with the EFCV17in a first flow state.FIG.12Bshows a cross-sectional view of the EFCV17taken fromFIG.11with the EFCV17in a second flow state.FIG.12Cshows a cross-sectional view of the EFCV17taken fromFIG.11with the EFCV17in a third flow state.FIG.13shows a perspective view of an example embodiment of a planetary carrier30of the handwheel actuator100.FIG.14shows an exploded perspective view of the planetary carrier30.FIG.15shows an exploded perspective view of an example embodiment of an input shaft44and first and second driver pins43A,43B for the handwheel actuator100.FIG.16shows an exploded perspective view of an example embodiment of a front cover46together with a rolling element bearing47.FIG.17shows an end view of the handwheel actuator100without the front cover46installed.FIGS.18A-18Cshow cross-sectional views of the handwheel actuator100taken fromFIG.1with the rotary damper19in three different rotational positions.FIG.19shows a schematic representation of a drive-by-wire steering system300of a vehicle400. The following should be read in light ofFIGS.1-19.

Turning toFIG.19, the drive-by-wire steering system300includes the handwheel10, the handwheel actuator100, a handwheel sensor16, an electronic control unit (ECU)95, a steering actuator90, and wheels98. The ECU95communicates electronically with the handwheel actuator100, the handwheel sensor16, and the steering actuator90. That is, the ECU95is configured to either receive an electronic signal or provide an electronic signal to any of these components. Furthermore, the ECU95, as known within vehicle applications, can control the drive-by-wire steering system300so that an operator or driver input to the handwheel10is translated to a steering action of the wheels98via the electronically controlled steering actuator90. Given that there is no mechanical connection between the handwheel10and the wheels98, the handwheel actuator100is configured to provide force feedback to the driver or operator during a steering process of the vehicle400.

The handwheel actuator100uses the rotary damper19to provide a selectively variable torque characteristic at the handwheel10. This characteristic may be tuned using the EFCV17, which can be commanded to various positions depending on an amount of torque resistance required or selected for a particular driving condition. A reduction in the form of a planetary gearset82is used to reduce the required rotary travel of the rotary damper19, allowing the handwheel actuator100to fit in a small package space. Return springs6are utilized to return the handwheel10to a neutral position when the driver input is removed.

The handwheel10, which can also be referred to as a steering wheel or a driver interface, is attached to an input shaft44which transmits an input torque applied to the handwheel10to a sun gear45of the input shaft44. The sun gear45can be integral with the input shaft44or a separate component that is fixed to the input shaft44. Torque is transmitted from the sun gear45to the planetary carrier30, which rotates at a slower speed than the input shaft44. Any suitable speed ratio between the input shaft44and the planetary carrier30can be utilized. Larger speed ratios equate to a smaller angular displacement of the rotary damper19which can be useful for reducing packaging space. Planet gears38arranged within the planetary carrier30engage a grounded ring gear25integrated within the housing24. The term “grounded” is meant to indicate that that the housing24is attached to the vehicle400and is therefore held in a stationary position. The ring gear25could also be a separate component that is fixed to the housing24. A rear carrier37of the planetary carrier30is attached to the rotary damper19via a torsional interface54which facilitates rotation of the rotary damper19within the housing24. Measurables of the input rotation of the input shaft44, such as angular position and speed, are captured by the handwheel sensor16that includes a rotary position target9and a sensor board11. This information can be sent to the ECU95to adjust rotational resistance (or a resistant torque) applied to the input shaft44via the rotary damper19and the EFCV17.

Any suitable reduction can be utilized other than the planetary gearset that is described and shown in the figures. For example, a parallel axis gear pair could also be utilized.

Turning toFIGS.1and15, when an input torque Tl is applied to the handwheel10to rotate it in a first rotational direction R1about a rotational axis AX1, a first resistant torque TRes1can be applied to the input shaft44via the rotary damper19. Likewise, when an input torque T2is applied to the handwheel10to rotate it in a second rotational direction R2, a second resistant torque TRes2can be applied to the input shaft44via the rotary damper19. The attainment of the first and second resistant torques TRes1, TRes2will now be described.

Turning toFIG.7, the rotary damper19includes a hub55and vane56that extends radially outwardly from the hub55. The hub55includes a through-bore57formed with a hub spline58. Turning toFIGS.13and14, the rear carrier37of the planetary carrier30includes a plate portion66and an axial protrusion48that extends from the plate portion66. A carrier spline49is formed on a radial outer surface of the axial protrusion48. The carrier spline49is fixed to the hub spline58of the rotary damper19and together form the torsional interface54so that the planetary carrier30(or rear carrier37thereof) and the rotary damper19rotate in unison. The axial protrusion48of the rear carrier37includes a bore59through which the input shaft44extends. Furthermore, the input shaft44extends entirely through the planetary carrier30.

The rotary damper includes three seals. A radial seal20is springably disposed (by a spring22) within a groove78arranged at a radial outer extent of the vane56; and, axial seals21are springably disposed (by springs23) within axial face grooves79of the hub55. The springs22,23could also be eliminated from the respective radial and axial seals.

Turning toFIGS.7-9A and18A-18C, the rotary damper19is sealingly disposed within a fluid well70formed within a rear portion71of the housing24. The fluid well70is defined by a radial outer wall72, an axial surface73, and an arc-shaped boss74that extends axially outward (rearward) from the axial surface73. The radial seal20of the rotary damper19slidably engages the radial outer wall72of the fluid well70as the rotary damper19rotates. The axial seals21of the rotary damper19also slidably engage the axial surface73of the fluid well70and an inner axial surface65of the rear cover34. Furthermore, the axial seals21are axially compressed via attachment of the rear cover34to the rear portion71of the housing24via fasteners16. An additional radial seal26that is disposed (via optional spring27) within an axial groove75of an inner radial wall of the arc-shaped boss74provides sealing of the hub55as it rotates within the fluid well70of the housing24. The arc-shaped boss74, which could be described as a curved boss, extends around the rotational axis AX1.

The front cover46and rear cover34can be considered as components of the housing24of the handwheel actuator100. The rear cover34is sealably attached to the rear portion71of the housing24via an O-ring28. The rotary damper19forms a first fluid chamber84A and a second fluid chamber84B with the housing24. It could also be stated that the rotary damper19forms the first fluid chamber84A and the second fluid chamber84B with the fluid well70. In particular, a first side68of the vane56of the rotary damper19forms the first fluid chamber84A, and a second side69of the vane56of the rotary damper19forms the second fluid chamber84B. The first and second fluid chambers84A,84B could be described as being curved, annular, ring-shaped or arc shaped.

In an example embodiment, when the input torque T1is applied to the handwheel10to rotate it in the first rotational direction R1, the first fluid chamber84A is compressed and the second fluid chamber84B is expanded. When this occurs, compression of the first fluid chamber84A increases a fluid pressure P1within the first fluid chamber84A, and expansion of the second fluid chamber84B decreases a fluid pressure P2within the second fluid chamber84B. The resultant pressure differential (P1-P2) between the two chambers can cause the fluid to flow from the first fluid chamber84A to the second fluid chamber84B via the metered fluid passage50. Similarly, when the input torque T2is applied to the handwheel10to rotate it in the second rotational direction R2, the second fluid chamber84B is compressed and the first fluid chamber84A is expanded. When this occurs, compression of the second fluid chamber84B increases the fluid pressure P2within the second fluid chamber84B, and expansion of the first fluid chamber84A decreases the fluid pressure P2within the first fluid chamber84A. The resultant pressure differential (P2-P1) between the two chambers can cause the fluid to flow from the second fluid chamber84B to the first fluid chamber84A.

Three of many possible angular positions of the rotary damper19are shown inFIGS.18A-18C. In a first angular position shown inFIG.18A, the first side68of the vane56of the rotary damper19abuts or engages with a first end76A of the arc-shaped boss74, defining a first rotational limit of the rotary damper19in the first rotational direction R1. In a second angular position shown inFIG.18B, the rotary damper19resides in a middle position of the fluid well70such that a first volume VI of the first fluid chamber84A is equal to a second volume V2of the second fluid chamber84B. In an example embodiment, the second angular position corresponds to a non-turning position of the handwheel10and/or the wheels98. In a third angular position shown inFIG.18C, the second side69of the vane56of the rotary damper19abuts or engages with a second end76B of the arc-shaped boss74, defining a second rotational limit of the rotary damper19in the second rotational direction R2. The first and second ends76A,76B of the arc-shaped boss define respective first and second rotational end stops86A,86B for the rotary damper19.

The first and second fluid chambers84A,84B can be filled with any suitable fluid. Fluid99is exchanged between the first and second fluid chambers84A,84B via a metered fluid passage50that extends from the first end76A of the arc-shaped boss74to the second end76B of the arc-shaped boss74. Thus, the metered fluid passage50fluidly connects the first fluid chamber84A to the second fluid chamber84B. The metered fluid passage50is defined by a curved or arc-shaped groove51arranged on an annular top surface83of the arc-shaped boss74(seeFIG.8). Rotation of the handwheel10displaces fluid from one fluid chamber to the other fluid chamber via an open state of the metered fluid passage50. Therefore, fluid that is exchanged between the first and second fluid chambers84A,84B moves about the rotational axis AX1via the arc-shaped groove51.

When the input torque Tl is applied to the handwheel10to rotate it in the first rotational direction R1, the rotary damper19displaces fluid from the first fluid chamber84A to the second fluid chamber84B during an open state of the metered fluid passage50. Likewise, when the input torque T2is applied to the handwheel10to rotate it in the second rotational direction R2, the rotary damper19displaces fluid from the second fluid chamber84B to the first fluid chamber84A during an open state of the metered fluid passage50. In an example embodiment, when the rotary damper19rotates in the first rotational direction R1, the volume V1of the first fluid chamber84A decreases and the volume V2in the second fluid chamber increases; and when the rotary rotates in the second direction, the volume V1of the first fluid chamber84A increases and the volume V2in the second fluid chamber decreases. When the rotary damper19is engaged with the first rotational end stop86A as shown inFIG.18A, the volume V1of the first fluid chamber84A is zero and a volume V2of the second fluid chamber84B is at a maximum. When the rotary damper19is engaged with the second rotational end stop86B as shown inFIG.18C, the volume V2of the second fluid chamber84B is zero and the volume V1of the first fluid chamber84A is at a maximum.

A variable or selective rotational resistance can be provided to the handwheel10via the rotary damper19as it pushes fluid out of one fluid chamber and into another fluid chamber via the metered fluid passage50. This variable rotational resistance occurs due to a controlled variability of a flow area of the metered fluid passage50, accomplished via the EFCV17.

The EFCV17is mounted to the rear cover34via a fastener18. In an example embodiment, the EFCV17can be a proportional solenoid valve, as known in the field of electronic valves. The EFCV17includes an electric coil60that, when energized via an electrical plug63, actuates an armature62. The armature62is integrally formed with a gate64so that the armature62and gate64move together within a housing67. A nose87of the housing67extends through an opening85of the rear cover34. The nose87is inserted within a blind bore52of the arc-shaped boss74such that the blind bore52intersects or interrupts the arc-shaped groove51, defining a first channel53A or passage, and a second channel53B or passage. The nose87includes circumferential through-openings13that fluidly connect the arc-shaped groove51to the gate64. The gate64and its longitudinal position, as controlled by the electric coil60and armature62, define a variable flow area of the metered fluid passage50.

Turning toFIGS.12A-12C, three longitudinal positions of the gate64are shown that define three flow areas of the metered fluid passage50. InFIG.12A, the electric coil60is de-energized and a spring61moves the armature62and gate64to a closed position such that no fluid can pass through EFCV17, defining a “normally closed” characteristic of the EFCV17. No fluid can be exchanged between the first and second fluid chambers84A,84B when the gate is closed, defining a “zero” flow area. In an example embodiment, the closed position EFCV17can be utilized to lock the handwheel10in any rotational position so that it cannot be rotated.

Turning toFIG.12B, the electric coil60is energized so that the armature62and gate64are moved slightly to the right, resulting in a flow gap G1which defines a flow area FAI through which the fluid of the metered fluid passage50can flow and pass through the EFCV17. Therefore, when the rotary damper19is rotated in the first rotational direction R1, fluid is displaced from (or exits from) the first fluid chamber84A and flows, in succession: through the first channel53A, through the EFCV17in a first direction DI via the flow gap G1, through the second channel53B, and to the second fluid chamber84B. Furthermore, when the rotary damper19is rotated in the second rotational direction R2, fluid is displaced from (or exits from) the second fluid chamber84B and flows, in succession: through the second channel53B, through the EFCV17in a second direction D2via the flow gap G1, through the first channel53A, and to the first fluid chamber84A.

Turning toFIG.12C, the electric coil60is energized so that the armature62and gate64are moved further to the right, resulting in a flow gap G2which defines a flow area FA2through which the fluid of the metered fluid passage50can flow and pass through the EFCV17. Therefore, when the rotary damper19is rotated in the first rotational direction R1, fluid is displaced from (or exits from) the first fluid chamber84A and flows, in succession: through the first channel53A, through the EFCV17via the flow gap G2, through the second channel53B, and to the second fluid chamber84B. Furthermore, when the rotary damper19is rotated in the second rotational direction R2, fluid is displaced from (or exits from) the second fluid chamber84B and flows, in succession: through the second channel53B, through the EFCV17via the flow gap G2, through the first channel53A, and to the first fluid chamber84A. Given that the flow gap G2and the corresponding flow area FA2ofFIG.12Cis greater than the flow gap G1and corresponding flow area FAI ofFIG.12B, a fluid flow resistance provided by the EFCV17ofFIG.12Cis less than a fluid flow resistance provided by the EFCV17ofFIG.12B. A lower flow resistance translates to a lower resistant torque provided by the rotary damper19to the input shaft44, and thus, to the handwheel10. Therefore, a flow gap of the EFCV17can be varied to achieve a desired resistant torque that is applied to the handwheel10.

The previously described longitudinal positions of the EFCV17were described for a “normally closed” valve configuration. In an example embodiment, the EFCV17is configured to be “normally open”, meaning that when the electric coil is de-energized, the armature is springably moved to an open gate position. The longitudinal positions shown inFIGS.12A-12Ccould be accommodated with such a normally open valve configuration.

A variable and selective resistant torque can be applied to the input shaft44when the rotary damper19rotates about the rotational axis AX1. The variability and selectiveness are accomplished via the metered fluid passage50, or more specifically, the EFCV17that controls a fluid flow resistance or fluid flow rate through the metered fluid passage50. The resistant torque is a product of a fluid pressure that acts on the vane56of the rotary damper19. For example, when the handwheel10is rotated in the first rotational direction R1via the input torque T1, the first fluid chamber84A decreases in volume and compresses the fluid contained within the first fluid chamber84A. This rotary motion can generate a pressure P1within the first fluid chamber84A that acts on the first side68of the vane56(seeFIG.18B). This pressure P1, or the magnitude thereof, can be controlled by the EFCV17. A decreasing opening magnitude of the gate64of the EFCV17will yield: i) a decreasing fluid flow rate through the metered fluid passage50, and ii) an increasing flow resistance of the metered fluid passage50. For a constant input torque T1, a small opening magnitude of the gate64will generate a larger pressure in the first fluid chamber84A than a pressure that results from large opening magnitude of the gate64. The pressure P1acts on an area A1of the first side68of the vane56to produce a force FP1on the vane56. The force FP1equates to the first resistant torque TRes1that is applied to the rotary damper19and input shaft44, which translates back to the handwheel10. Similarly, when the handwheel10is rotated in the second rotational direction R2via the input torque T2, a pressure P2generated within the second fluid chamber84B acts on the second side69of the vane56to produce a force FP2on the vane56. The force FP2equates to the second resistant torque TRes2that is applied to the rotary damper19and input shaft44, which translates back to the handwheel10.

In an example embodiment, a resistant torque provided to the handwheel10by the rotary damper19and the metered fluid passage50can be adjusted with software of the ECU95. In a further aspect, the software can vary the resistant torque based on handwheel speed and/or vehicle speed or any other suitable parameter or variable.

The EFCV17can be that of any suitable electronically controlled valve. In an example embodiment, the EFCV17is an on/off type of solenoid valve that opens the gate64to a given longitudinal position each time it is energized. In a further aspect, the EFCV17can be configured to receive a pulse-width modulated (PWM) digital signal, known in the field of electronically controlled valves, from the ECU95. A frequency and duration of opening and closing of the gate64can be varied to control a fluid flow resistance or fluid flow rate of the metered fluid passage50. This variation is accomplished by energization or de-energization of the electric coil60, as controlled by the ECU95.

Regardless of the valve type or control method, the EFCV17selectively varies the fluid flow resistance of the metered fluid passage50. The smaller the commanded opening magnitude of the EFCV17, the higher the fluid flow resistance.

The metered fluid passage50could be described as a “flow path” that extends between the first and second fluid chambers84A,84B, and the EFCV17selectively controls: i) a size of the flow path (or size of an opening thereof), or ii) a magnitude of obstructing or blocking of the flow path via the gate64.

In an example embodiment, a total volume of the fluid contained within the first and second fluid chambers84A,84B is held constant through various rotational positions of the rotary damper19. Therefore, when the rotary damper19is angularly displaced within the housing24, a volume of fluid that is removed from the reduced-volume fluid chamber is equal to a volume of fluid that is added to the increased-volume fluid chamber, assuming that the metered fluid passage50is in an open state and the first and second fluid chambers and metered fluid passage50are full of fluid.

In addition to the active control provided by the EFCV17, the metered fluid passage50can inherently produce a velocity-dependent flow resistance due to an orifice-like flow condition of the EFCV17. Therefore, for any commanded longitudinal position of the gate64, a faster rotation of the handwheel10will result in a greater resistant torque provided by the metered fluid passage50.

Turning toFIGS.3,4, and17, the handwheel actuator100includes first and second springs6A,6B acting as return springs for the handwheel10. In a drive-by-wire steering system, since there is no mechanical connection between the wheels98and the handwheel10, there is no inherent tendency of the wheels98to move to a straight or non-turning position when an input torque is removed from the handwheel10. The springs6A are configured to return the handwheel10to a home position, which can be defined by either: i) a straight or non-turning position of the handwheel10and wheels98, or ii) a position in which the net spring force acting on the input shaft44is zero. In an example embodiment, the rotary vane (middle) position shown inFIG.18Bcan correspond to the home position of the handwheel10and wheels98. Thus, the first and second springs6A,6B respectively apply opposing return torques TR1, TR2that can overcome at least a fluid flow resistance of the metered fluid passage50(EFCV17is open) and an inherent friction of the planetary carrier30to move the input shaft44to an angular position at which the opposing return torques TR1, TR2are equal. In an alternative embodiment, a detent feature arranged within the handwheel actuator100is utilized to position the input shaft44or rotary damper19at the home position.

Turning toFIG.17, the first and second springs6A,6B are shown with respective first and second legs7A,7B that engage respective first and second spring openings88A,88B arranged on an axial face81of the front portion80of the housing24. The first and second springs6A,6B include respective first and second hooks89A,89B that wrap around respective first and second driver pins43A,43B attached to the sun gear45of the input shaft44.

In an example embodiment, when the input shaft44is rotated in the first rotational direction R1via an input torque Tl applied to the handwheel10: i) the first spring6A is wound via a rotation of the sun gear45and corresponding first driver pin43A, inducing a return torque TRI on the input shaft44; and ii) the second spring6B is not wound (and thus no return torque is induced) and the second driver pin43B slidably moves along an arc-shaped path within a curved portion91B of the second hook89B. Upon removal of the input torque T1from the handwheel10, the return torque TR1can return (rotate) the input shaft44and handwheel10to a rotational position that corresponds with a non-turning position at which a zero net return torque is acting on the input shaft44. Once in the non-turning position, the second driver pin43B will re-engage the second hook of the second spring6B. Similarly, when the input shaft44is rotated in the second rotational direction R2via a torque T2applied to the handwheel10: i) the second spring6B is wound via a rotation of the sun gear45and corresponding second driver pin43B, inducing a return torque TR2on the input shaft44; and ii) the first spring6A is not wound (and thus no return torque is induced) and the first driver pin43A slidably moves along an arc-shaped path within a curved portion91A the first hook89A. Upon removal of the torque T2from the handwheel10, the return torque TR2can return (rotate) the input shaft44and handwheel10to a rotational position that corresponds with a non-turning position at which a zero net return torque is acting on the input shaft44. Once in the non-turning position, the first driver pin43A will re-engage the first hook89A of the first spring6A. Any suitable force generators can be used in place of the first and second springs6A,6B shown and described herein. In an example embodiment, the first and second springs6A,6B can be torsion springs. In a further aspect, the torsion springs can provide a constant torque (or nearly so) or a variable torque throughout their winding and unwinding motions.

In an example embodiment, the first and second fluid chambers84A,84B and the metered fluid passage50define a variable resistance closed fluid system. The term “closed fluid system” is meant so signify that, during operation of the handwheel actuator100: i) fluid is not supplied to the closed fluid system from a source outside of the handwheel actuator100(such as, but not limited to, a pump), and ii) fluid is not exited from the closed fluid system to a reservoir or component outside of the handwheel actuator100. Stated otherwise, the closed fluid system is self-contained such that all of its fluid, and the exchange thereof, remains within the handwheel actuator100. In addition, the first and second fluid chambers84A,84B and the metered fluid passage50are all completely enclosed within the housing24.

Turning toFIGS.13and14, the planetary carrier30, which together with the sun gear45form the planetary gearset82, includes a front carrier36that is joined together with a rear carrier37. Various methods such as laser welding could be utilized for joining or attaching the front carrier36to the rear carrier37. The front and rear carriers36,37can be manufactured via a stamping process or any other suitable manufacturing means. The front and rear carriers36,37house the planet gears38, planet pins39, bearings40, and washers41. A thrust washer42may be added to help axially retain the planetary carrier30within the handwheel actuator100. The gears are depicted within the figures as straight cut, but can be helical for noise reduction purposes.

The following describes an example embodiment of an assembly of the handwheel actuator100. Turning toFIG.4, a washer2and the planetary carrier30are installed into the housing24. The input shaft44, assembled with the first and second driver pins43A,43B is inserted through the planetary carrier30and the housing24, and the springs6A,6B are installed on the respective first and second driver pins43A,43B and within the respective first and second spring openings88A,88B of the housing24. The front cover46, assembled with the rolling element bearing47, is attached via fasteners8to the housing24.

Turning toFIGS.5-6B, the rotary damper19is pressed onto the carrier spline49of the planetary carrier30, and the housing24is closed by attaching the rear cover34(assembled with the rolling element bearing35) to the housing24via fasteners5. The EFCV17is fixed to the rear cover34with the fastener18. The rolling element bearings47,35housed within the respective front and rear covers46,34, are configured to rotatably support the input shaft44. Any suitable fit can be applied between the rolling element bearings47,35, and: i) the input shaft44, and ii) the respective front and rear covers46,34including, but not limited to, a press-fit (interference fit), a transition fit, and a slip fit, as known in the field of rolling element bearings. Different fits may affect an assembly sequence of the rolling element bearings47,35; for example, the rolling element bearings47,35could be installed on input shaft44before the front and rear covers46,34are fastened to the housing24.

Turning toFIGS.3and4, the target9of the handwheel sensor16is secured to the input shaft44with a fastener33. The sensor board11of the handwheel sensor16is secured to the rear cover34with fasteners12.