Planetary roller screw drive with pulley-mounted support bearing inner raceways

Abstract

A planetary roller screw drive for a steering actuator includes a screw spindle and a planetary roller assembly disposed on the screw spindle. The planetary roller assembly comprises a roller body and a planetary roller, wherein the planetary roller is arranged between the screw spindle and the roller body, and the planetary roller is meshed with the screw spindle and the roller body. A planetary roller carrier holds the planetary rollers. A drive pulley is connected for common rotation with the planetary roller carrier and is rotatably mountable on the housing via a first radial bearing and a second radial bearing. These radial bearings include respective inner raceway rings located on the drive pulley. A first panel and a second panel are positioned at an axial end region of the drive pulley, and the panels are rotationally fixed to respective inner raceway rings. The panel is also rotationally fixed to the planetary roller carrier. An assembly method is also provided.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. non-provisional application No. 17 / 882,690, filed on August 8, 2022, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a planetary roller screw drive which converts a rotational motion into a translational motion. The present disclosure also relates to a steering actuator having such a planetary roller screw drive, in particular a steering actuator for a rear axle steering system of a motor vehicle. Background Art

[0004] A planetary roller screw drive is known from DE 10 2015 206 735 B3. The planetary roller screw drive is provided with a nut arranged on a screw spindle and planetary rollers arranged between the screw spindle and the nut, and the planetary rollers mesh with the nut side groove profile on the radial outside and with the thread profile of the screw spindle on the radial inside via their planetary groove profile. The planetary roller screw drive also has a planetary roller support with pockets, the pockets are arranged to be distributed on the circumference and the planetary rollers are rotatably mounted in the pockets around their planetary roller axes. The planetary roller support is connected for co-rotation with a drive sleeve, which is driven rotatably around the spindle axis of the screw spindle. The drive sleeve is rotatably mounted on the machine part via a bearing called a main bearing.

[0005] Similar arrangements are also known in which a belt drive is connected to a pulley for driving a planetary roller bearing. In some applications, in order to reduce weight and cost, certain parts including the pulley are made of plastic.

[0006] Providing adequate rotational support for the main shaft as well as the planetary roller bearings and pulleys for reliable function while maintaining reduced weight is a challenge. Summary of the invention

[0007] In one aspect, a planetary roller screw drive having a screw spindle and a planetary roller assembly arranged on the screw spindle is provided. The planetary roller assembly includes a roller body and a planetary roller having a planetary groove profile and a roller body side groove profile, the planetary roller is arranged between the screw spindle and the roller body, and the planetary roller is meshed with the thread profile of the screw spindle via the planetary groove profile and meshed with the roller body groove profile of the roller body via the roller body side groove profile. A planetary roller carrier is provided, in which the planetary roller is rotatably mounted around its corresponding planetary roller axis. A drive pulley suitable for being rotatably driven around the spindle axis of the screw spindle is connected to rotate with the planetary roller carrier, and the drive pulley is configured to be rotatably mounted on a housing via a first radial bearing located at a first axial end region of the drive pulley and a second radial bearing located at a second axial end region of the drive pulley. The first radial bearing and the second radial bearing include corresponding first inner raceway rings and second inner raceway rings located on the radial outer surface of the drive pulley. A first panel and a second panel are positioned at the first axial end region and the second axial end region of the drive pulley, respectively, wherein the first panel is rotationally fixed to the first inner raceway ring and the second panel is rotationally fixed to the second inner raceway ring. The first panel and the second panel are also rotationally fixed to the planetary roller carrier.

[0008] With this arrangement, when the pulley is made of a lightweight material such as a plastic or composite material - the properties of which would be insufficient to support and / or retain the bearing that would typically be pressed against the outer surface of the pulley - the use of a first inner race ring and a second inner race ring that are separately engaged with the face plate while still bearing on the radial outer surface of the pulley allows proper support of the pulley when the planetary roller assembly is installed in the housing.

[0009] The additional features described below provide enhanced functionality and performance, and also facilitate assembly.

[0010] In one embodiment, the drive pulley includes radially inwardly directed teeth located at the first axial end region and the second axial end region, and the first panel and the second panel include corresponding radially outwardly directed teeth, which engage with the inwardly directed teeth to fix the drive pulley to the first panel and the second panel in terms of rotation.

[0011] In one embodiment, the first and second panels are rotationally fixed to the planetary roller carrier via radially inwardly directed teeth on the first and second panels engaging complementary protrusions of the planetary roller carrier.

[0012] In one embodiment, the first panel is rotationally fixed to the first inner raceway ring via radially inwardly directed protrusions on the first inner raceway ring engaging with at least some of the corresponding radially outwardly directed teeth of the first panel, and the second panel is rotationally fixed to the second inner raceway ring via radially inwardly directed protrusions on the second inner raceway ring engaging with at least some of the corresponding radially outwardly directed teeth of the second panel.

[0013] In one embodiment, the drive pulley comprises an axially extending first pulley finger and an axially extending second pulley finger extending from a first axial end region and a second axial end region, respectively, and the first pulley finger and the second pulley finger are resiliently deflectable radially inwardly and outwardly. The first pulley finger each comprises a radially outwardly directed protrusion configured to axially retain the first inner race ring on the drive pulley, and the second pulley finger each comprises a radially outwardly directed protrusion configured to axially retain the second inner race ring on the drive pulley.

[0014] In one embodiment, the first pulley fingers each include a radially inwardly directed protrusion configured to axially retain the first panel in place, and the second pulley fingers each include a radially inwardly directed protrusion configured to axially retain the second panel in place.

[0015] In one embodiment, the planetary roller assembly further comprises a first axial bearing and a second axial bearing respectively located between the first panel and the housing and between the second panel and the housing. Here, the radially inwardly directed protrusions of the first pulley finger and the second pulley finger engage on the panel-side raceway rings of the first axial bearing and the second axial bearing respectively. This also holds the axial bearings in place before assembling the planetary roller assembly in the housing.

[0016] The first and second pulley fingers may be resiliently deflected radially outward for mounting respective first and second panels and other internal components of the planetary roller assembly.

[0017] In addition, the first pulley finger and the second pulley finger can also be elastically deflected radially inwardly for installing the first inner raceway ring and the second inner raceway ring. Once assembled, the first pulley finger and the second pulley finger return to their neutral (undeflected) position, and the radially inwardly directed protrusions and the radially outwardly directed protrusions hold the components axially together.

[0018] In another aspect, a third axial bearing and a fourth axial bearing are positioned between the first face plate and the first axial end of the roller body and between the second face plate and the second axial end of the roller body, respectively.

[0019] In another aspect, an actuator for a rear axle steering system of a motor vehicle is provided, the actuator having a planetary roller screw drive with one or more of the features described herein and a push rod having ends facing away from each other and configured for articulating a rear wheel of the motor vehicle. The screw spindle is part of or connected to the push rod.

[0020] The actuator may have an electric motor and a belt drive having a toothed belt which passes around a motor pinion of the electric motor and drives a pulley.

[0021] In one embodiment of the actuator, the housing houses the motor pinion and the planetary roller screw drive within the housing.

[0022] On the other hand, a method for assembling a planetary roller assembly for a planetary roller screw drive is provided, and the method includes the following steps: (a) assembling a roller body onto a planetary roller having a planetary groove profile and a roller body side groove profile, the planetary roller being suitable for being arranged between a screw spindle and the roller body and the planetary roller engaging with the roller body groove profile of the roller body via the roller body side groove profile, (b) rotatably mounting the planetary roller in a planetary roller carrier so that the planetary roller is rotatably mounted around its corresponding planetary roller axis, (c) mounting a drive pulley around the roller body, (d) mounting a first panel and a second panel respectively on the first and second surfaces of the drive pulley. (e) then mounting the first inner race ring of the first radial bearing and the second inner race ring of the second radial bearing to the respective first axial end region and the second axial end region of the drive pulley, wherein the first inner race ring and the second inner race ring are also rotationally fixed to the first and second panels. This rotationally fixed connection can be achieved as discussed above.

[0023] The method preferably further comprises installing an inner axial bearing at the axial end of the roller body before installing the first and second panels in step (d). The method may further comprise installing an outer axial bearing on the first and second panels before installing the first inner raceway ring of the first radial bearing and the second inner raceway ring of the second radial bearing in step (e).

[0024] In one embodiment, the drive pulley comprises an axially extending first pulley finger and an axially extending second pulley finger extending from a first axial end region and a second axial end region, respectively, wherein the first pulley finger and the second pulley finger are resiliently deflectable radially inward and outward, and the first pulley finger each comprises a radially outwardly directed protrusion, and the second pulley finger each comprises a radially outwardly directed protrusion. Here, the method further comprises: (f) axially retaining the first inner raceway ring on the drive pulley with the radially outwardly directed protrusion on the first pulley finger; and (g) axially retaining the second inner raceway ring on the drive pulley with the radially outwardly directed protrusion on the second pulley finger.

[0025] In one embodiment, the first pulley fingers each include a radially inwardly directed protrusion, and the second pulley fingers each include a radially inwardly directed protrusion. Here, the method further includes: (h) axially holding the first panel in place with the radially inwardly directed protrusions of the first pulley fingers; and (i) axially holding the second panel in place with the radially inwardly directed protrusions of the second pulley fingers.

[0026] In one embodiment, the planetary roller assembly also includes a first axial bearing and a second axial bearing respectively located between the first panel and the housing and between the second panel and the housing, and the radially inwardly directed protrusions of the first pulley finger and the second pulley finger are respectively engaged on the panel side raceway rings of the first axial bearing and the second axial bearing.

[0027] In one embodiment, the method further comprises: (j) resiliently deflecting the first and second pulley fingers radially outward for mounting the respective first and second panels in step (d).

[0028] The method may further include: (k) resiliently deflecting the first pulley finger and the second pulley finger radially inwardly for mounting the first inner race ring and the second inner race ring on the drive pulley in step (e).

[0029] The various features of the invention may be used alone or in combination to achieve one or more of the benefits described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The foregoing summary and the following detailed description will be better understood when read in conjunction with the accompanying drawings which illustrate preferred embodiments according to the present disclosure. In the drawings:

[0031] Figure 1 is a cross-sectional view through a planetary roller assembly of a planetary roller screw drive according to the present disclosure.

[0032] Figure 2 yes Figure 1 An end view of the planetary roller assembly of a planetary roller screw drive device shown in the figure shows that the inner race ring of the radial support bearing is interlocked with the drive pulley and the face plate so as to radially lock the drive pulley and the inner race ring of the support bearing to the face plate, and the face plate is also shown as having a rotational locking feature for the planetary roller carrier.

[0033] Figure 3 is an enlarged cross-sectional view showing the interlocking of the inner race ring, drive pulley and face plate labeled for each of the axial end regions of the planetary roller assembly.

[0034] Figure 4 is a cross-sectional view through a steering actuator that may be used with a steering actuator including Figures 1 to 3 The planetary roller screw drive shown in FIG. 1 is used in conjunction with a rear axle steering system.

[0035] Figure 5 is a perspective view showing an integral actuator for a rear axle steering system including a push rod which is connected to or is part of a lead screw spindle. DETAILED DESCRIPTION

[0036] Certain terms are used in the following description only for convenience and are not restrictive. The words "inwardly" and "outwardly" refer to the direction toward and away from the part referenced in the accompanying drawings. "Axial" refers to the direction along the axis of the shaft. "Radial" refers to the direction roughly perpendicular to the axis. For example, a reference to a list of items cited as "at least one of a or b" (wherein a and b represent the listed items) means any single one of the items a or b, or a combination of a and b. This will also apply in a similar manner to a list of three or more items, so that a single item or a combination of items is included. Unless otherwise indicated, the terms "about" and "approximately" cover +10% or -10% of the indicated value. The terms include the words specifically specified above, their derivatives, and words of similar meaning.

[0037] Reference Figure 1 , a planetary roller screw drive 10 is shown in cross section. The planetary roller screw drive 10 comprises a screw spindle 12 and a planetary roller assembly 14 arranged on the screw spindle 12.

[0038] like Figures 1 to 3As shown in the figure, the planetary roller assembly 14 includes a roller body 20 and planetary rollers 22, each of which has a planetary groove profile 23 and a roller body side groove profile 24, and the planetary rollers are arranged between the screw spindle 12 and the roller body 20. The planetary rollers 22 are engaged with the thread profile 13 of the screw spindle via the planetary groove profile 23, and are engaged with the roller body groove profile 21 of the roller body 20 via the roller body side groove profile 24.

[0039] The planetary rollers 22 are supported in the planetary roller carrier 28, in which the planetary rollers 22 are rotatably mounted about their respective planetary roller axes. The planetary roller carrier 28 includes pockets 28a distributed on its circumference, and the planetary rollers 22 are rotatably mounted in the pockets. Figure 1 A journal end 25 formed at an axial end of the planetary roller 22 is shown, which journal end engages in a bearing pocket 28 a of the planetary roller carrier 28 .

[0040] A drive pulley 30 is provided which may be made of a lightweight material such as plastic or a composite material and is adapted to be rotatably driven about the spindle axis X of the spindle 12. The drive pulley 30 is connected for common rotation with the planetary roller carrier 28 and is configured to be rotatably mounted on the housing 40 ( Figure 4 ), and the drive pulley is supported via a first radial bearing 42 at a first axial end region 30a of the drive pulley 30 and a second radial bearing 46 at a second axial end region 30b of the drive pulley. The first radial bearing 42 and the second radial bearing 46 include respective first inner raceway rings 43 and second inner raceway rings 47 and outer raceway rings 44, 48 on the radial outer surface 30c of the drive pulley 30 and respective rollers 45, 49 between the inner raceway rings and the outer raceway rings.

[0041] These first radial bearings 42 and second radial bearings 46 support the pulley 30 in use. However, a problem arises in that, since the pulley 30 is made of plastic or composite lightweight material, the bearings 42, 46 require inner raceway rings 43, 47 made of a bearing material such as steel. In addition, the inner raceway rings 43, 47 must move with the pulley 30, which in this case cannot be ensured by a press fit between the inner raceway rings 43, 47 and the pulley 30 due to the material properties of the pulley 30.

[0042] In order to solve this problem, a first panel 50 and a second panel 54 are respectively positioned at the first axial end region 30a and the second axial end region 30b of the pulley 30. And the first panel 50 is rotationally fixed to the first inner raceway ring 43, while the second panel 54 is rotationally fixed to the second inner raceway ring 47. In addition, the first panel 50 and the second panel 54 are rotationally fixed to the planetary roller carrier 28.

[0043] Still refer to Figures 1 to 3 In order to achieve these rotationally fixed connections, the drive pulley 30 comprises radially inwardly directed teeth 32 at a first axial end region 30a and a second axial end region 30b (at Figure 2 ), and the first panel 50 and the second panel 54 include corresponding radially outwardly directed teeth 51, 55, which engage the inwardly directed teeth 32 of the drive pulley 30 to rotationally fix the drive pulley to the first panel 50 and the second panel 54.

[0044] The first panel 50 is also rotationally fixed to the inner race ring 43 via the radially inwardly directed protrusions 43a on the first inner race ring 43 engaging at least some of the radially outwardly directed teeth 51 of the corresponding radially outwardly directed teeth of the first panel 50, and the second panel 54 is rotationally fixed to the second inner race ring 47 via the radially inwardly directed protrusions 47a on the second inner race ring 47 engaging at least some of the radially outwardly directed teeth 55 of the corresponding radially outwardly directed teeth of the second panel 54. This results in both the first inner race ring 43 and the second inner race ring 47 and the drive pulley 30 being rotationally fixed to the first panel 50 and the second panel 54.

[0045] like Figure 2 As shown in detail in the figure, the connection between the first panel 50 and the second panel 54 and the planetary roller carrier 28 is achieved via a meshing joint, which in this case includes radially inwardly pointing teeth 52, 56 located on the corresponding first panel 50 and the second panel 54, and the radially inwardly pointing teeth engage with complementary protrusions 29 at each axial end of the planetary roller carrier 28.

[0046] To ensure that the first inner race ring 43 and the second inner race ring 47 are axially held in place on the drive pulley 30, the drive pulley 30 includes an axially extending first pulley finger 34 and an axially extending second pulley finger 36 extending in opposite axial directions from a first axial end region 30a and a second axial end region 30b of the drive pulley 30, respectively. The first pulley finger 34 and the second pulley finger 36 are resiliently deflectable radially inwardly and outwardly, and the first pulley finger 34 each includes a radially outwardly directed protrusion 34a configured to axially hold the first inner race ring 43 preferably against an axially inwardly spaced annular protrusion 38a of the drive pulley 30, and the second pulley finger 36 each includes a radially outwardly directed protrusion 36a configured to axially hold the second inner race ring 47 preferably against an axially inwardly spaced annular protrusion 38b on the drive pulley 30.

[0047] In addition, still refer to Figures 1 to 3 , the first pulley fingers 34 each include a radially inwardly directed protrusion 34b configured to axially retain the first panel 50 in place, and the second pulley fingers 36 each include a radially inwardly directed protrusion 36b configured to axially retain the second panel 54 in place. Figure 2 As shown in detail in FIG. 1 , there are preferably three first pulley fingers 34 and correspondingly three second pulley fingers 36. However, this number may vary. In addition, still referring to Figure 2 The radially inwardly directed protrusions 43a of the first inner raceway ring 43 and the radially inwardly directed protrusions 47a of the second inner raceway ring 47 may be grooved so that they have portions located on each side of the corresponding first pulley finger 34 and second pulley finger 36, so that the radially outwardly directed protrusions 34a, 36a may engage the corresponding first inner raceway ring 43 and second inner raceway ring 47 in the region of the radially inwardly directed protrusions 43a, 47a.

[0048] Refer again Figure 1 , the planetary roller assembly 14 also includes a first outer axial bearing 60 and a second outer axial bearing 62, which are respectively located between the facing portions of the first and second panels 50, 54 and the housing 40 when assembled. The radially inwardly directed protrusions 34b of the first pulley finger 34 and the radially inwardly directed protrusions 36b of the second pulley finger 36 are respectively engaged on the panel side raceway ring 61 of the first axial bearing 60 and the panel side raceway ring 63 of the second axial bearing 62. This holds these first axial bearings 60 and the second axial bearings 62 against the first and second panels 50, 54, thereby holding these first and second axial bearings in place on the planetary roller assembly 14 before assembly in the housing 40.

[0049] Reference Figure 1 and Figure 3 , the first pulley finger 34 and the second pulley finger 36 are adapted to be elastically deflected radially outward for installation of the corresponding first and second panels 50, 54 and other internal components of the planetary roller assembly 14 and the raceway ring 61 of the first axial bearing 60 and the raceway ring 63 of the second axial bearing 62. In addition, the first pulley finger 34 and the second pulley finger 36 are adapted to be elastically deflected radially inward for installation of the first and second inner raceway rings 43, 47. Once the first and second inner raceway rings 43, 47 are installed, the first pulley finger 34 and the second pulley finger 36 return to a neutral position in which the radially outwardly directed protrusions 34a, 36a and the radially inwardly directed protrusions 34b, 36b hold the engaged components axially together.

[0050] Refer again Figure 1 , the planetary roller assembly 14 further includes a third inner axial bearing 64 and a fourth inner axial bearing 66 respectively located between the first face plate 50 and the first axial end 20a of the roller body 20 and between the second face plate 54 and the second axial end 20b of the roller body 20. This allows axial loads to be transmitted by the planetary roller assembly 14 from the main shaft 12 through the planetary rollers 22 and the roller body 20 via the first axial bearing 60 and the third axial bearing 64 in one axial direction and via the second axial bearing 62 and the fourth axial bearing 66 in a second axial direction, so that the axial loads can be transmitted to the housing 40 once the planetary roller screw drive 10 is assembled in the housing.

[0051] Now refer to Figure 4 and Figure 5 , an actuator 70 that can be used for a rear axle steering system of a motor vehicle is shown. The actuator 70 includes a planetary roller screw drive 10 as discussed above and a push rod 72 having ends that are separated from each other, and the ends are configured to articulate the wheels to be steered on the motor vehicle. In an exemplary embodiment, the end of the push rod 72 is provided with a fork-shaped joint 73. The end of the push rod 72 protruding from the housing 40 is preferably wrapped by a bellows collar and covered as shown. The screw spindle 12 of the planetary roller screw drive 10 arranged in the housing 40 forms the central part of the push rod 72. The push rod 72 can have two push rod parts arranged to be located behind each other in the axial direction, and the screw spindle 12 is arranged between the two push rod parts and is firmly connected to the two push rod parts. Alternatively, the push rod part and the screw spindle 12 can be connected to each other as one piece.

[0052] like Figure 4 and Figure 5As shown in detail in FIG, the actuator 70 also includes an electric motor 74 and a belt drive comprising a toothed belt 76 that surrounds a motor pinion 78 of the electric motor 74 on one side and a drive pulley 30 on the other side. In this arrangement, the drive pulley 30 includes corresponding teeth 39 for the toothed belt 76 to engage.

[0053] like Figure 4 and Figure 5 As shown in FIG. 4 , the housing 40 houses the motor pinion 78 and the planetary roller screw drive 10 therein, and the belt is also captured within the housing 40 .

[0054] In another aspect, a method of assembling a planetary roller drive assembly 14 for a planetary roller screw drive 10 is provided. The method comprises:

[0055] (a) Assembling the roller body 20 onto the planetary roller 22 having the planetary groove profile, the planetary roller engaging with the roller body groove profile 21 of the roller body via the roller body side groove profile 24;

[0056] (b) rotatably mounting the planetary rollers 20 in the planetary roller carrier 28 so that the planetary rollers 22 are rotatably mounted about their respective planetary roller axes;

[0057] (c) installing the drive pulley 30 around the roller body 20;

[0058] (d) mounting the first panel 50 and the second panel 54 at the first axial end region 30a and the second axial end region 30b of the drive pulley 30, respectively, wherein the first panel 50 and the second panel 54 are rotationally fixed to the planetary roller carrier 28a via meshing features, preferably the inwardly directed teeth 52 of the first panel 50 and the inwardly directed teeth 56 of the second panel 54, engaging with the complementary protrusions 29 of the planetary roller carrier 28, and the first panel 50 and the second panel 54 are rotationally fixed to the drive pulley 30 via the radially inwardly directed teeth 32 at the first axial end region 30a and the second axial end region 30b of the drive pulley 30 engaging with the radially outwardly directed teeth 51 of the first panel 50 and the radially outwardly directed teeth 55 of the second panel 54; and

[0059] (e) The first inner raceway ring 43 of the corresponding first radial bearing 42 and the second inner raceway ring 47 of the second radial bearing 46 are then mounted onto the corresponding first axial end region 30a and second axial end region 30b of the drive pulley 30, wherein the first inner raceway ring 43 and the second inner raceway ring 47 are also rotationally fixed to the first panel 50 and the second panel 54.

[0060] The method preferably also includes installing inner axial bearings 64, 66 at the axial ends of the roller body 20 before installing the first panel 50 and the second panel 54 in step (d). The method may also include installing outer axial bearings 60, 62 on the first panel 50 and the second panel 54 before installing the first inner raceway ring of the first radial bearing and the second inner raceway ring of the second radial bearing in step (e). The method may also include providing the drive pulley 30 with an axially extending first pulley finger 34 and an axially extending second pulley finger 36 as discussed above, wherein further method steps include:

[0061] (f) axially retaining the first inner race ring 43 on the drive pulley 30 using the radially outwardly directed projections 34a on the first pulley fingers 34; and

[0062] (g) The second inner race ring 47 is axially retained on the drive pulley 30 by means of the radially outwardly directed projections 36 a on the second pulley fingers 36 .

[0063] The method may further comprise the steps of:

[0064] (h) holding the first panel 50 axially in place using the radially inwardly directed projections 34b of the first pulley fingers 34; and

[0065] (i) The second panel 54 is held axially in place using the radially inwardly directed projections 36b of the second pulley fingers 36.

[0066] Further method steps may include:

[0067] (j) resiliently deflecting the first and second pulley fingers 34, 36 radially outward for mounting the respective first and second panels 50, 54 and possibly other internal components of the planetary roller assembly 14 in step (d); and

[0068] (k) elastically deflecting the first pulley finger 34 and the second pulley finger 36 radially inward for mounting the first inner race ring 43 and the second inner race ring 47 on the drive pulley 30 in step (e).

[0069] Assembling in this manner provides advantages over previously known assembly techniques and allows the components of the planetary roller assembly 14 to be held together in a simple manner.

[0070] Thus, having described the present preferred embodiment in detail, it will be understood and apparent to those skilled in the art that many physical changes can be made without changing the inventive concepts and principles embodied herein, only some of which are exemplified in the detailed description. It should also be understood that multiple embodiments that only incorporate a portion of the preferred embodiment are possible, and the multiple embodiments do not change the inventive concepts and principles embodied herein relative to those portions. Therefore, the present embodiment and optional configurations are considered in all respects to be exemplary and / or illustrative rather than restrictive, the scope is indicated by the appended claims rather than by the foregoing description, and therefore, all alternative embodiments and variations of the embodiment that fall within the equivalent meaning and scope of the claims will be included herein.

[0071] Reference numerals list

[0072] 10 Planetary roller screw drive

[0073] 12 Screw spindle

[0074] 13 Thread profile

[0075] 14 Planetary roller assembly

[0076] 20 roller body

[0077] 21 Roller body groove profile

[0078] 22 Planetary rollers

[0079] 23 Planetary groove profile

[0080] 24 Roller body side groove profile

[0081] 28 Planetary roller bearings

[0082] 28a Recess

[0083] 29 complementary protrusion

[0084] 30 Drive pulley

[0085] 30a First axial end region

[0086] 30b Second axial end region

[0087] 30c Radial outer surface

[0088] 32 Radially inward pointing teeth

[0089] 34 First pulley finger

[0090] 34a Radially outwardly directed projection

[0091] 34b Radially inwardly directed projection

[0092] 36 Second pulley finger

[0093] 36a Radially outwardly directed projection

[0094] 36b Radially inwardly directed projection

[0095] 38a, 38b annular projections spaced axially inwardly

[0096] 39 teeth

[0097] 40 Shell

[0098] 42 First radial bearing

[0099] 43 First inner race ring

[0100] 43a Radially inwardly directed projection

[0101] 44 Outer raceway ring

[0102] 45 Roller

[0103] 46 Second radial bearing

[0104] 47 Second inner race ring

[0105] 47a Radially inwardly directed projection

[0106] 48 Outer raceway ring

[0107] 49 Roller

[0108] 50 First Panel

[0109] 51 Teeth pointing radially outwards

[0110] 52 Radially inward pointing teeth

[0111] 54 Second Panel

[0112] 55 Teeth pointing radially outwards

[0113] 56 Teeth pointing radially inwards

[0114] 60 First outer axial bearing

[0115] 61 Panel side raceway ring

[0116] 62 Second outer axial bearing

[0117] 63 Panel side raceway ring

[0118] 64 Third inner axial bearing

[0119] 66 Fourth inner axial bearing

[0120] 70 Actuator

[0121] 72 Putter

[0122] 73 Fork connector

[0123] 74 Electric Motor

[0124] 76 Toothed belt

[0125] X axis

Claims

1. A planetary roller screw drive device, comprising: Screw spindle; A planetary roller assembly, the planetary roller assembly is arranged on the lead screw spindle, and the planetary roller assembly comprises: roller body, a planetary roller having a planetary groove profile and a roller body side groove profile, the planetary roller being arranged between the screw spindle and the roller body, and the planetary roller being meshed with the thread profile of the screw spindle via the planetary groove profile and with the roller body groove profile of the roller body via the roller body side groove profile, a planetary roller carrier in which the planetary rollers are rotatably mounted about their respective planetary roller axes, a drive pulley adapted to be rotatably driven about the spindle axis of the lead screw spindle and connected for co-rotation with the planetary roller carrier, and configured to be rotatably mounted on a housing via a first radial bearing at a first axial end region of the drive pulley and a second radial bearing at a second axial end region of the drive pulley, the first radial bearing and the second radial bearing comprising respective first and second inner raceway rings on a radial outer surface of the drive pulley, a first panel and a second panel, the first panel and the second panel being located at the first axial end region and the second axial end region of the drive pulley, respectively, the first panel being rotationally fixed to the first inner race ring, and the second panel being rotationally fixed to the second inner race ring, and The first and second panels are rotationally fixed to the planetary roller carrier.

2. The planetary roller screw drive according to claim 1, wherein: The drive pulley includes radially inwardly directed teeth at the first and second axial end regions, and the first and second panels include corresponding radially outwardly directed teeth that engage with the inwardly directed teeth to rotationally secure the drive pulley to the first and second panels.

3. The planetary roller screw drive according to claim 2, wherein: The first and second panels are rotationally fixed to the planetary roller carrier via radially inwardly directed teeth on the first and second panels engaging complementary protrusions of the planetary roller carrier.

4. The planetary roller screw drive according to claim 3, wherein: The first panel is rotationally fixed to the first inner raceway ring via radially inwardly directed protrusions on the first inner raceway ring engaging with at least some of the corresponding radially outwardly directed teeth of the first panel, and the second panel is rotationally fixed to the second inner raceway ring via radially inwardly directed protrusions on the second inner raceway ring engaging with at least some of the corresponding radially outwardly directed teeth of the second panel.

5. The planetary roller screw drive according to claim 4, wherein: The drive pulley includes an axially extending first pulley finger and an axially extending second pulley finger extending from the first axial end region and the second axial end region, respectively, the first pulley finger and the second pulley finger being elastically deflectable radially inward and outward, the first pulley finger each including a radially outwardly directed protrusion configured to axially retain the first inner race ring on the drive pulley, and the second pulley finger each including a radially outwardly directed protrusion configured to axially retain the second inner race ring on the drive pulley.

6. The planetary roller screw drive according to claim 5, wherein: The first pulley fingers each include a radially inwardly directed protrusion configured to axially retain the first panel in position, and the second pulley fingers each include a radially inwardly directed protrusion configured to axially retain the second panel in position.

7. The planetary roller screw drive according to claim 6, wherein: The planetary roller assembly also includes a first axial bearing and a second axial bearing configured to be located between the first panel and the housing and between the second panel and the housing, respectively, and the radially inwardly directed protrusions of the first pulley finger and the second pulley finger are respectively engaged on the panel side raceway rings of the first axial bearing and the second axial bearing.

8. The planetary roller screw drive according to claim 6, wherein: The first and second pulley fingers are adapted to resiliently deflect radially outward for mounting the respective first and second panels.

9. The planetary roller screw drive according to claim 8, wherein: The first pulley finger and the second pulley finger are adapted to be resiliently deflected radially inwardly for mounting the first inner race ring and the second inner race ring.

10. The planetary roller screw drive according to claim 1, wherein: The planetary roller assembly also includes a third axial bearing and a fourth axial bearing located between the first face plate and the first axial end of the roller body and between the second face plate and the second axial end of the roller body, respectively.

11. An actuator for a rear axle steering system of a motor vehicle, comprising a planetary roller screw drive according to claim 1, a push rod having ends which face away from each other and are configured to articulate the rear wheels of the motor vehicle, and the screw spindle being part of or connected to the push rod.

12. The actuator of claim 11 further comprising an electric motor and a belt drive having a toothed belt encircling a motor pinion of the electric motor and the drive pulley.

13. The actuator of claim 12, further comprising the housing, the housing housing the motor pinion and the planetary roller screw drive therein.

14. A method of assembling a planetary roller assembly for a planetary roller screw drive, the method comprising: Assembling a roller body onto a planetary roller having a planetary groove profile and a roller body side groove profile, the planetary roller being configured to be arranged between the screw spindle and the roller body and the planetary roller being engaged with the roller body groove profile of the roller body via the roller body side groove profile; rotatably mounting the planetary rollers in a planetary roller carrier such that the planetary rollers are rotatably mounted about their respective planetary roller axes; installing a drive pulley around the roller body; mounting a first panel and a second panel at a first axial end region and a second axial end region of the drive pulley, respectively, the first panel and the second panel being rotationally fixed to the planetary roller carrier via meshing features, and the first panel and the second panel being rotationally fixed to the drive pulley via radially inwardly directed teeth at the first axial end region and the second axial end region of the drive pulley engaging radially outwardly directed teeth of the first panel and the second panel; and A first inner race ring of a respective first radial bearing and a second inner race ring of a respective second radial bearing are then mounted to the respective first and second axial end regions of the drive pulley, wherein the first and second inner race rings are also rotationally fixed to the first and second panels.

15. The method according to claim 14, further comprising: installing an inner axial bearing at an axial end of the roller body before installing the first panel and the second panel; and External axial bearings are installed on the first face plate and the second face plate before installing the first inner race ring of the first radial bearing and the second inner race ring of the second radial bearing.

16. The method according to claim 14, wherein: The drive pulley comprises an axially extending first pulley finger and an axially extending second pulley finger extending from the first axial end region and the second axial end region, respectively, the first pulley finger and the second pulley finger being resiliently deflectable radially inwardly and outwardly, the first pulley finger each comprising a radially outwardly directed protrusion, and the second pulley finger each comprising a radially outwardly directed protrusion, and the method further comprises: axially retaining the first inner race ring on the drive pulley using the radially outwardly directed projections on the first pulley fingers; and The second inner race ring is axially retained on the drive pulley by the radially outwardly directed projections on the second pulley fingers.

17. The method according to claim 16, wherein: The first pulley fingers each include a radially inwardly directed protrusion, and the second pulley fingers each include a radially inwardly directed protrusion, and the method further includes: retaining the first panel axially in position using the radially inwardly directed projections of the first pulley fingers; and The second panel is held axially in place by the radially inwardly directed projections of the second pulley fingers.

18. The method according to claim 17, wherein: The planetary roller assembly also includes a first axial bearing and a second axial bearing adapted to be located between the first panel and the housing and between the second panel and the housing, respectively, and the radially inwardly directed protrusions of the first pulley finger and the second pulley finger are respectively engaged on the panel side raceway rings of the first axial bearing and the second axial bearing.

19. The method of claim 17, further comprising resiliently deflecting the first and second pulley fingers radially outward for mounting the respective first and second panels.

20. The method of claim 19, further comprising resiliently deflecting the first and second pulley fingers radially inward for mounting the first and second inner race rings on the drive pulley.

Images