WO2022117142A1 - Actuator for a steering device of a motor vehicle - Google Patents

Actuator for a steering device of a motor vehicle Download PDF

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Publication number
WO2022117142A1
WO2022117142A1 PCT/DE2021/100871 DE2021100871W WO2022117142A1 WO 2022117142 A1 WO2022117142 A1 WO 2022117142A1 DE 2021100871 W DE2021100871 W DE 2021100871W WO 2022117142 A1 WO2022117142 A1 WO 2022117142A1
Authority
WO
WIPO (PCT)
Prior art keywords
roller bearing
rollers
roller
axis
cage
Prior art date
Application number
PCT/DE2021/100871
Other languages
German (de)
French (fr)
Inventor
Mario Arnold
Andreas Kirschner
Original Assignee
Schaeffler Technologies AG & Co. KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Schaeffler Technologies AG & Co. KG filed Critical Schaeffler Technologies AG & Co. KG
Publication of WO2022117142A1 publication Critical patent/WO2022117142A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
    • F16H25/2247—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with rollers
    • F16H25/2252—Planetary rollers between nut and screw
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0442—Conversion of rotational into longitudinal movement
    • B62D5/0451—Roller spindle drives
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/30—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for axial load mainly
    • F16C19/305—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for axial load mainly consisting of rollers held in a cage
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/34—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load
    • F16C19/36—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with a single row of rollers
    • F16C19/361—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with a single row of rollers with cylindrical rollers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/588—Races of sheet metal
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D15/00—Clutches with wedging balls or rollers or with other wedgeable separate clutching members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D41/00—Freewheels or freewheel clutches
    • F16D41/06—Freewheels or freewheel clutches with intermediate wedging coupling members between an inner and an outer surface
    • F16D41/061—Freewheels or freewheel clutches with intermediate wedging coupling members between an inner and an outer surface the intermediate members wedging by movement having an axial component
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H25/24—Elements essential to such mechanisms, e.g. screws, nuts
    • F16H25/2454—Brakes; Rotational locks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D7/00—Steering linkage; Stub axles or their mountings
    • B62D7/06—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins
    • B62D7/14—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering
    • B62D7/146—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by comprising means for steering by acting on the suspension system, e.g. on the mountings of the suspension arms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2326/00—Articles relating to transporting
    • F16C2326/20—Land vehicles
    • F16C2326/24—Steering systems, e.g. steering rods or columns
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D41/00—Freewheels or freewheel clutches
    • F16D41/06—Freewheels or freewheel clutches with intermediate wedging coupling members between an inner and an outer surface
    • F16D41/08—Freewheels or freewheel clutches with intermediate wedging coupling members between an inner and an outer surface with provision for altering the freewheeling action
    • F16D41/082—Freewheels or freewheel clutches with intermediate wedging coupling members between an inner and an outer surface with provision for altering the freewheeling action the intermediate coupling members wedging by movement other than pivoting or rolling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H2025/2062—Arrangements for driving the actuator
    • F16H2025/2096—Arrangements for driving the actuator using endless flexible members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members

Definitions

  • the present invention relates to an actuator for a steering device of a motor vehicle.
  • the invention relates to an actuator of a rear-axle steering system of a motor vehicle.
  • DE102018115788 A1 discloses an actuator for a rear-axle steering system according to the features of the preamble of claim 1.
  • This actuator is provided with a housing and with a threaded drive which is arranged in the housing and has a threaded spindle and a nut, which is rotatably mounted in the housing in the axial direction by means of a roller bearing.
  • the rollers of the roller bearing designed as an axial roller bearing are distributed over the circumference around a roller bearing axis and roll on raceways of the roller bearing. These raceways are formed on thrust washers.
  • Some of these rollers are arranged in such a way that their axis of rotation is arranged at a radial distance from the axis of the roller bearing. With this so-called friction roller bearing, a friction torque is generated in the circumferential direction of the screw drive between the screw drive and the housing when an external axial force acts on the threaded spindle.
  • the screw drive is actuated by an electric motor and the threaded spindle of the screw drive, which is connected to the push rod of the actuator, is displaced axially in order to steer the rear wheels.
  • the screw drive should have the best possible efficiency in favor of the required drive power from the electric motor. If the actuator fails or external forces act on the vehicle wheels and act on the threaded spindle, an unwanted adjustment of the threaded spindle as part of the connecting rod should be avoided, depending on the application.
  • the friction roller bearing described is intended to help prevent these undesirable adjusting movements of the threaded spindle, ie to freeze the position of the threaded spindle.
  • the object of the present invention was to specify an actuator according to the preamble of claim 1, which enables improved freezing of the actuator. According to the invention, this object was achieved by the actuator according to claim 1.
  • This actuator is provided for a steering device of a motor vehicle, in particular for a rear-axle steering.
  • a screw drive which has a threaded spindle and a nut, is arranged in a housing. These screw drives are rotation-translation gears and convert a rotation into a translational movement.
  • the screw drive is preferably designed as a planetary roller screw drive. They enable a very economical drive with a large axial load carrying capacity due to the large number of rolling contacts; they can be preloaded without play, allow very small gradients, are very smooth-running, since no return of rolling elements is required.
  • the power is transmitted via the flanks of the rollers, spindle and nut.
  • the large number of contact points results in a very high axial load capacity.
  • An economical drive is possible due to the small incline. Comparatively low drive torques of a motor are required.
  • the lead screw design, lead size and internal friction determine its ability to hold the lead screw in an axial position under an axial load on the lead screw when the lead screw is not actively driven.
  • the nut can be driven in rotation.
  • its planetary roller cage is preferably driven in rotation, and planetary rollers are arranged in its cage pockets.
  • These planetary roller screw drives are pitch-true, a full revolution of the planetary roller cage corresponds to an axial displacement of the threaded spindle by the amount of the pitch of the thread of the threaded spindle.
  • an electric motor can be mounted on the housing, which drives the screw drive via a rotation-rotation gear.
  • a toothed belt transmission is preferably provided, the toothed belt of which has a motor pinion and a Wraps around the drive wheel, which is connected to the rotationally driven component of the screw drive.
  • the screw drive is rotatably mounted in the housing in the axial direction by means of a roller bearing.
  • Axial forces acting between the threaded spindle and the nut are introduced into the housing, which is mounted on the vehicle, via these roller bearings.
  • One of these roller bearings can be provided on the two axial sides of the screw drive between the housing and the screw drive in order to transmit axial forces in both axial directions.
  • rollers of this roller bearing are distributed over the circumference around a roller bearing axis and roll off on raceways of the roller bearing. At least one of the rollers is arranged with its axis of rotation radially spaced from the roller bearing axis. In other words, this roller is arranged off-axis because its axis of rotation touches a circle that is thought to be coaxial around the axis of the roller bearing and does not intersect the axis of the roller bearing.
  • At least one of these raceways has a convex shape as seen in the longitudinal section through the roller bearing and is formed on a resiliently deformable thrust washer.
  • the convex track itself is therefore elastically deformable.
  • an axial force acts on the screw drive, which is transmitted to the housing via this roller bearing.
  • elastic deformation of the thrust washer is so small that the rollers of this rolling bearing more or less only contact an apex line of the convex raceway, so that there is more of a punctiform contact between the roller and the raceway, meaning that this roller rolls off the raceways with very little friction .
  • the contact between the rollers of the rolling bearing and the crest line can be made with their middle roller portions of the rollers. All rollers of this roller bearing can be off-axis in the manner described, because due to the more point-like contact this roller bearing is under operating conditions - ie under the acting axial forces during active actuation of the actuator - very low friction.
  • increasing external axial loading of the threaded spindle increasing elastic deformation of the thrust washer sets in and the associated leveling of the convex raceway.
  • the initially point-like contact between the roller and the raceway becomes a roughly linear contact between the rollers and the raceway of the thrust washer.
  • the friction roller body Seen in the direction along the roller bearing axis, the friction roller body forms a first leg of an angle alpha with its axis of rotation, and a straight line which, starting from the roller bearing axis, intersects the axis of rotation of the friction roller body in its axial center forms a second leg of the angle alpha.
  • the angle alpha formed between the two legs is adjusted depending on the desired friction.
  • the invention has recognized that an angle alpha of approximately between 2 degrees and 10 degrees can be sufficient for inhibiting the actuator in connection with a planetary roller screw drive as a screw drive if all rollers of the roller bearing are arranged off-axis.
  • This angle alpha is, the higher the proportion of sliding friction in the frictional contact between the friction roller body and the raceway.
  • the frictional force depends on the axial load on the threaded spindle. The angle is adjusted in such a way that, with a certain number of friction rolling elements, the actuator is prevented from being blocked when external axial forces are introduced into the connecting rod.
  • a friction torque is generated in the roller bearing as a product of the friction force with its effective lever arm about the axis of rotation of the rotationally driven part of the screw drive. The frictional force acts between the raceways and the friction rolling elements.
  • a roller bearing set up in this way ensures the desired inhibition of the actuator when it is not being actively operated and axial forces are transferred, for example, via a push rod - i.e. also via the threaded spindle - into the nut and finally via the roller bearing into the housing are initiated.
  • a driving electric motor is switched off - and an external axial load acts on the screw spindle, this axial load is transferred to the roller bearing.
  • This frictional force acting between the nut and the housing inhibits undesired displacement of the connecting rod and prevents undesired rotation of the nut or a rotationally driven planetary roller cage.
  • Self-locking can be ensured with the actuator when external axial forces are introduced into the threaded spindle.
  • the roller bearing can be designed as an axial roller bearing.
  • a particularly advantageous development is given by an angular contact roller bearing, which transmits both the usually small radial forces and the larger axial forces.
  • a separate radial bearing can be omitted in this case.
  • Both thrust washers preferably have the convexly shaped raceway between their outer circumference and inner circumference on mutually facing end faces and a concavely shaped end face on their end faces facing away from one another.
  • both convex raceways are increasingly flattened with elastic deformation of the thrust washers, as has already been explained above.
  • rollers of this roller bearing are guided in cage pockets of a roller cage, preferably made of steel.
  • the roller cage can be designed to be so wear-resistant that it can reliably absorb the forces introduced into the cage by the off-axis rollers.
  • the de-axled rollers exert a tilting moment in the cage pockets.
  • the friction between the rollers and the roller cage increases the friction and promotes the desired self-locking when large axial forces act on the threaded spindle.
  • both thrust washers are provided on their end faces facing away from each other with a support surface for supporting the roller bearing, which is located radially outside of a crest line of the convex raceway.
  • the two thrust washers can have a concave end face on their end faces facing away from one another.
  • One thrust washer can be secured against rotation on the housing and the other washer can be supported in a torque-proof manner on the screw drive, preferably on the rotary-driven planetary roller cage of the planetary roller screw drive.
  • the concave faces provide sufficient space for elastic deformation of the thrust washers when large axial forces are transmitted through the rolling bearing.
  • the elastic deformation can only be in the tenths of a mm range.
  • the anti-friction bearing developed as an axial angular contact roller bearing can have two thrust washers arranged at an angle to the spindle axis of the screw drive, one of which is supported on the rotary-driven machine part of the screw drive and the other on the housing, with a circular roller cage being inserted between the two thrust washers, in which via the Circumferentially arranged cage pockets which are guided by rollers. All rollers of this axial angular contact roller bearing can be arranged with axes of rotation arranged radially spaced apart from the roller bearing axis and guided in the cage pockets, with a spindle axis of the screw drive coinciding with the roller bearing axis. Sufficiently large amounts of friction can be achieved with this tapered roller bearing in the case of undesirably large axial forces.
  • One thrust washer can be provided on its radially inner circumference with a sleeve-shaped attachment which is arranged coaxially to the roller bearing axis and on which the roller cage fitted with the rollers and the other thrust washer are arranged. This development allows for easy assembly of the individual parts of the rolling bearing and its easy installation in the actuator.
  • the screw drive is preferably formed by the above-mentioned planetary roller screw drive with axially prestressed planetary rollers, which are arranged distributed over the circumference between the nut and the threaded spindle, the nut having two nut parts divided transversely to the longitudinal axis, which can be screwed together and secured by a lock nut .
  • the screw connection keeps the two nut parts at a predetermined distance, in which a freedom from play of the planetary screw drive is guaranteed.
  • the planetary rollers are guided in cage pockets of a planetary roller cage, which is non-rotatably connected to a drive wheel for a rotary drive of this planetary roller screw drive, which operates with the same pitch.
  • the planetary rollers mesh with their planet-side grooved profile with a thread of the threaded spindle and with a nut-side grooved profile of the nut.
  • Planetary screw drives of this type which are known per se, are characterized by a high positioning accuracy.
  • Such planetary roller screw drives are smooth-running in operation, with the preferred axial angular contact roller bearing with the off-axis rollers inhibiting when external axial forces act on the threaded spindle.
  • Operational axial forces are sufficiently small that the rollers of the roller bearing are in more or less point-like contact with the convex-shaped raceways in the manner described and enable a smooth-running drive.
  • sufficiently high friction losses can be provided, so that at large axial loads, an unwanted axial displacement of the threaded spindle is excluded.
  • This actuator is preferably further developed for a rear-axle steering system of a motor vehicle, the connecting rod of which, penetrating the housing, articulates two wheels of an axle via connecting rods, the threaded spindle being part of the connecting rod.
  • FIG. 1 shows an actuator according to the invention in a perspective view
  • Figure 2 shows a longitudinal section through the actuator, only one section being shown
  • Figure 4 is an enlarged detail of Figure 3
  • FIG. 5 shows a further detail enlargement of FIG. 3,
  • Figure 6 is a roller and cage assembly of the axial angular contact roller bearing
  • FIG. 1 shows an actuator of a rear-axle steering system of a motor vehicle, the housing 1 of which is mounted on the vehicle.
  • a motor shaft of an electric motor 2 engages in the housing 1 and is provided with a motor pinion, not shown.
  • a connecting rod 3 penetrates the housing 1 with its axial ends, both of which are provided with clevises 4 which are connected to handlebars, not shown, in order to articulate the rear wheels.
  • the push rod 3 is displaced along its longitudinal axis when the actuator is actuated.
  • FIG. 2 shows a portion of this actuator in longitudinal section.
  • the electric motor 2 drives a screw drive 31 via a toothed belt 5 , which is formed by a planetary roller screw drive 6 in the exemplary embodiment.
  • the planetary screw drive 6 is rotatably mounted in the housing 1 by means of two roller bearings 32 which are formed by axial angular contact roller bearings 9 in the exemplary embodiment.
  • the toothed belt 5 wraps around the above-mentioned motor pinion of the electric motor 2 and a sleeve-shaped drive wheel 7 which is provided with a toothed profile 8 for the toothed belt 5 on its cylindrical surface.
  • the planetary roller screw drive 6 is formed by a threaded spindle 10 arranged in a rotationally fixed manner in the housing 1, which is part of the connecting rod 3, and by a nut 11 rotatably mounted on the threaded spindle 10 - in the exemplary embodiment formed from nut parts screwed together - and by distributed over the circumference arranged planetary rollers 12 which are rotatably mounted in cage pockets 13 of a planetary roller cage 14.
  • the nut 11 is rotatably mounted on the planetary roller cage 14 via axial roller bearings 33 .
  • the planetary rollers 12 engage with their groove profile 15 on the planet side both in a thread 16 of the threaded spindle 10 and in a groove profile 30 on the nut side.
  • the planetary roller cage 14 is non-rotatably connected to the sleeve-shaped drive wheel 7 which encloses the nut 11 .
  • the planetary roller cage 14 is designed in several parts in the exemplary embodiment and is provided with a system for the axial angular contact roller bearing 9 on its end face facing the axial angular contact roller bearing 9 .
  • Figures 3 to 7 show the axial angular contact roller bearing 9, the two formed from sheet metal
  • the cage pockets 21 distributed over the circumference can be clearly seen in FIGS.
  • the thrust washers 17, 18 each have a convex-shaped raceway 23, 24 between their outer circumference and inner circumference on mutually facing end faces and a concave-shaped end face 25, 26 on their end faces facing away from one another.
  • the convex shaped tracks 24, 25 are crowned in the embodiment.
  • the thrust washers 17, 18 each have a support surface 27, 28 for supporting the axial angular roller bearing 9 on the housing 1 and on the planetary roller cage 14 on their end faces facing away from one another. These support surfaces 27, 28 are radially offset - arranged to a crest line of the convex raceway 23, 24 - here outside and inside. This arrangement enables elastic deformation and leveling of the convex raceways 23, 24, since the thrust washers have sufficient space for elastic deflection on their end face facing the housing 1.
  • One thrust washer 17 has on its radially inner circumference a sleeve-shaped extension 29 which is arranged coaxially to the roller bearing axis and is integrally formed on the thrust washer 17 .
  • the roller and cage assembly 19 and the other thrust washer 18 are arranged on the sleeve-shaped extension 29 .
  • rollers 22 have their axes of rotation offset by an angle alpha.
  • the axis of rotation does not intersect the axis A of the roller bearing.
  • the angle alpha is enclosed by a leg which coincides with the axis of rotation of the roller 22 and a leg which intersects the axis of rotation in the middle of the roller and the axis A of the roller bearing.
  • the roller bearing axis A coincides with the spindle axis of the planetary screw drive 6 .

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Transmission Devices (AREA)
  • Power Steering Mechanism (AREA)

Abstract

The invention relates to an actuator for a steering device of a motor vehicle, having a housing (1) and a lead screw drive (31), which is arranged in the housing (1), has a lead screw (10) and a nut (11) and is mounted rotatably in the axial direction by means of a rolling bearing (32), the rolling elements (22) of which are distributed over the circumference around a rolling bearing axis (A) and roll on raceways (23, 24) of the rolling bearing (32), wherein at least one of the rolling elements (22) is arranged with its rotational axis spaced radially from the rolling bearing axis (A). At least one of the raceways (23, 24) is convex, as viewed in longitudinal section through the rolling bearing (32), and is formed on a resiliently deformable running disc (17, 18).

Description

Aktuator für eine Lenkeinrichtung eines Kraftfahrzeuges Actuator for a steering device of a motor vehicle
Die vorliegende Erfindung betrifft einen Aktuator für eine Lenkeinrichtung eines Kraftfahrzeuges. Insbesondere betrifft die Erfindung einen Aktuator einer Hinterachslenkung eines Kraftfahrzeuges. The present invention relates to an actuator for a steering device of a motor vehicle. In particular, the invention relates to an actuator of a rear-axle steering system of a motor vehicle.
Aus der DE102018115788 A1 ist ein Aktuator einer Hinterachslenkung nach den Merkmalen des Oberbegriffs des Anspruchs 1 bekannt geworden. Dieser Aktuator ist mit einem Gehäuse, und mit einem in dem Gehäuse angeordneten, eine Gewindespindel und eine Mutter aufweisenden Gewindetrieb versehen, der in axialer Richtung mittels eines Wälzlagers drehbar in dem Gehäuse gelagert ist. Die Rollen des als Axialwälzlager ausgebildeten Wälzlagers sind über den Umfang verteilt um eine Wälzlagerachse herum angeordnet und wälzen an Laufbahnen des Wälzlagers ab. Diese Laufbahnen sind an Anlaufscheiben ausgebildet. Einige dieser Rollen sind so angeordnet, dass ihre Rotationsachse radial beabstandet zur Wälzlagerachse angeordnet ist. Mit diesem sogenannten Reibwälzlager wird ein Reibmoment in Umfangsrichtung des Gewindetriebs zwischen Gewindetrieb und Gehäuse erzeugt, wenn von außen eine axiale Kraft auf die Gewindespindel einwirkt. DE102018115788 A1 discloses an actuator for a rear-axle steering system according to the features of the preamble of claim 1. This actuator is provided with a housing and with a threaded drive which is arranged in the housing and has a threaded spindle and a nut, which is rotatably mounted in the housing in the axial direction by means of a roller bearing. The rollers of the roller bearing designed as an axial roller bearing are distributed over the circumference around a roller bearing axis and roll on raceways of the roller bearing. These raceways are formed on thrust washers. Some of these rollers are arranged in such a way that their axis of rotation is arranged at a radial distance from the axis of the roller bearing. With this so-called friction roller bearing, a friction torque is generated in the circumferential direction of the screw drive between the screw drive and the housing when an external axial force acts on the threaded spindle.
Im Betrieb des Aktuators wird der Gewindetrieb elektromotorisch betätigt und die mit der Schubstange des Aktuators verbundene Gewindespindel des Gewindetriebs wird axial verschoben, um die Hinterräder an zu lenken. Der Gewindetrieb soll einen möglichst guten Wirkungsgrad aufweisen, zugunsten der erforderlichen Antriebsleistung durch den Elektromotor. Wenn der Aktuator ausfällt oder äußere Kräfte an den Fahrzeugrädern angreifen und auf die Gewindespindel wirken, soll je nach Anwendung eine unerwünschte Verstellung der Gewindespindel als Teil der Schubstange unterbleiben. Das beschriebene Reibwälzlager soll dazu beitragen, diese unerwünschten Stellbewegungen der Gewindespindel zu vermeiden, also die Lage der Gewindespindel einzufrieren. During operation of the actuator, the screw drive is actuated by an electric motor and the threaded spindle of the screw drive, which is connected to the push rod of the actuator, is displaced axially in order to steer the rear wheels. The screw drive should have the best possible efficiency in favor of the required drive power from the electric motor. If the actuator fails or external forces act on the vehicle wheels and act on the threaded spindle, an unwanted adjustment of the threaded spindle as part of the connecting rod should be avoided, depending on the application. The friction roller bearing described is intended to help prevent these undesirable adjusting movements of the threaded spindle, ie to freeze the position of the threaded spindle.
Aufgabe der vorliegenden Erfindung war es, einen Aktuator gemäß dem Oberbegriff des Anspruchs 1 anzugeben, der ein verbessertes Einfrieren des Aktuators ermöglicht. Erfindungsgemäß wurde diese Aufgabe durch den Aktuator gemäß Anspruch 1 gelöst.The object of the present invention was to specify an actuator according to the preamble of claim 1, which enables improved freezing of the actuator. According to the invention, this object was achieved by the actuator according to claim 1.
Dieser Aktuator ist für eine Lenkeinrichtung eines Kraftfahrzeuges, insbesondere für eine Hinterachslenkung vorgesehen. In einem Gehäuse ist ein Gewindetrieb angeordnet, der eine Gewindespindel und eine Mutter aufweist. Diese Gewindetriebe sind Rotation-Translation- Getriebe und wandeln eine Rotation in eine translatorische Bewegung um. This actuator is provided for a steering device of a motor vehicle, in particular for a rear-axle steering. A screw drive, which has a threaded spindle and a nut, is arranged in a housing. These screw drives are rotation-translation gears and convert a rotation into a translational movement.
Der Gewindetrieb ist vorzugsweise als Planetenwälzgewindetrieb ausgebildet. Sie ermöglichen einen sehr wirtschaftlichen Antrieb bei einer großen axialen Tragfähigkeit durch hohe Anzahl von Wälzkontakten; sie sind spielfrei vorspannbar, ermöglichen sehr kleine Steigungen, sind sehr laufruhig, da keine Rückführung von Wälzkörpern erforderlich ist.The screw drive is preferably designed as a planetary roller screw drive. They enable a very economical drive with a large axial load carrying capacity due to the large number of rolling contacts; they can be preloaded without play, allow very small gradients, are very smooth-running, since no return of rolling elements is required.
Die Kraftübertragung erfolgt über die Flanken der Rollen, Spindel und Mutter. Durch die große Anzahl an Kontaktstellen ergibt sich eine sehr hohe axiale Tragfähigkeit. Ein wirtschaftlicher Antrieb ist aufgrund der kleinen Steigung möglich. Es sind vergleichsweise geringe Antriebsmomenten eines Motors erforderlich. The power is transmitted via the flanks of the rollers, spindle and nut. The large number of contact points results in a very high axial load capacity. An economical drive is possible due to the small incline. Comparatively low drive torques of a motor are required.
Je nach Anwendung sind Weiterbildungen möglich, die einen Trapezgewindetrieb, Kugelgewindetrieb oder Rollengewindetrieb als Gewindetrieb einsetzen. Depending on the application, further developments are possible that use a trapezoidal screw drive, ball screw drive or roller screw drive as the screw drive.
Die Ausführungsart des Gewindetriebs, die Größe der Gewindesteigung und innere Reibung bestimmen dessen Fähigkeit, die Gewindespindel in einer axialen Position zu halten unter einer an der Gewindespindel angreifenden Axiallast, wenn der Gewindetrieb nicht aktiv angetrieben ist. Die Mutter kann drehangetrieben sein. Vorzugsweise ist im Fall des an sich bekannten Planetenwälzgewindetriebes dessen Planetenrollenkäfig drehangetrieben, in dessen Käfigtaschen Planetenrollen angeordnet sind. Diese Planetenwälzgewindetriebe sind steigungstreu, eine volle Umdrehung des Planetenrollenkäfigs entspricht einer axialen Verschiebung der Gewindespindel um den Betrag der Steigung des Gewindes der Gewindespindel. The lead screw design, lead size and internal friction determine its ability to hold the lead screw in an axial position under an axial load on the lead screw when the lead screw is not actively driven. The nut can be driven in rotation. In the case of the known planetary roller screw drive, its planetary roller cage is preferably driven in rotation, and planetary rollers are arranged in its cage pockets. These planetary roller screw drives are pitch-true, a full revolution of the planetary roller cage corresponds to an axial displacement of the threaded spindle by the amount of the pitch of the thread of the threaded spindle.
Für den Drehantrieb des Gewindetrieb kann ein Elektromotor an dem Gehäuse gehaltert sein, der über ein Rotation-Rotation-Getriebe den Gewindetrieb antreibt. Vorzugsweise ist ein Zahnriemengetriebe vorgesehen, dessen Zahnriemen ein Motorritzel sowie ein Antriebsrad umschlingt, das drehtest mit dem drehangetriebenen Bauteil des Gewindetriebs verbunden ist. For the rotary drive of the screw drive, an electric motor can be mounted on the housing, which drives the screw drive via a rotation-rotation gear. A toothed belt transmission is preferably provided, the toothed belt of which has a motor pinion and a Wraps around the drive wheel, which is connected to the rotationally driven component of the screw drive.
Der Gewindetrieb ist in dem Gehäuse in axialer Richtung mittels eines Wälzlagers drehbar gelagert. Zwischen der Gewindespindel und der Mutter wirkende axiale Kräfte werden über diese Wälzlager in das Gehäuse eingeleitet, das am Fahrzeug gehaltert ist. Jeweils eines dieser Wälzlager kann zu den beiden axialen Seiten des Gewindetriebes zwischen Gehäuse und Gewindetrieb vorgesehen sein, um axiale Kräfte in beiden axialen Richtungen zu übertragen. The screw drive is rotatably mounted in the housing in the axial direction by means of a roller bearing. Axial forces acting between the threaded spindle and the nut are introduced into the housing, which is mounted on the vehicle, via these roller bearings. One of these roller bearings can be provided on the two axial sides of the screw drive between the housing and the screw drive in order to transmit axial forces in both axial directions.
Die Rollen dieses Wälzlagers sind über den Umfang verteilt um eine Wälzlagerachse herum angeordnet und wälzen an Laufbahnen des Wälzlagers ab. Wenigstens eine der Rollen ist mit ihrer Rotationsachse radial beabstandet zur Wälzlagerachse angeordnet. In anderen Worten ausgedrückt, ist diese Rolle deachsiert angeordnet, denn ihre Rotationsachse tangiert einen Kreis, der koaxial um die Wälzlagerachse herum gedacht wird und schneidet nicht die Wälzlagerachse. The rollers of this roller bearing are distributed over the circumference around a roller bearing axis and roll off on raceways of the roller bearing. At least one of the rollers is arranged with its axis of rotation radially spaced from the roller bearing axis. In other words, this roller is arranged off-axis because its axis of rotation touches a circle that is thought to be coaxial around the axis of the roller bearing and does not intersect the axis of the roller bearing.
Wenigstens eine dieser Laufbahnen ist im Längsschnitt durch das Wälzlager gesehen konvex geformt und an einer federelastisch verformbaren Anlaufscheibe ausgebildet. Die konvexe Laufbahn an sich ist demzufolge elastisch verformbar. Im Betrieb des Aktuators wirkt eine axiale Stellkraft auf den Gewindetrieb, die über dieses Wälzlager in das Gehäuse übertragen wird. Unter dieser Stellkraft ist eine elastische Verformung der Anlaufscheibe so gering, das die Rollen dieses Wälzlagers mehr oder weniger lediglich eine Scheitellinie der konvexen Laufbahn kontaktieren, so dass ein eher punktförmiger Kontakt zwischen Rolle und Laufbahn eingerichtet ist, diese Rolle also sehr reibungsarm an den Laufbahnen abwälzt. At least one of these raceways has a convex shape as seen in the longitudinal section through the roller bearing and is formed on a resiliently deformable thrust washer. The convex track itself is therefore elastically deformable. During operation of the actuator, an axial force acts on the screw drive, which is transmitted to the housing via this roller bearing. Under this actuating force, elastic deformation of the thrust washer is so small that the rollers of this rolling bearing more or less only contact an apex line of the convex raceway, so that there is more of a punctiform contact between the roller and the raceway, meaning that this roller rolls off the raceways with very little friction .
Der Kontakt zwischen den Rollen des Wälzlagers und der Scheitellinie kann mit deren mittleren Rollenabschnitten der Rollen hergestellt werden. Es können sämtliche Rollen dieses Wälzlagers auf die beschriebene Weise deachsiert sein, denn aufgrund des eher punktförmigen Kontakts ist dieses Wälzlager unter Betriebsbedingungen - also unter den wirkenden axialen Kräften während einer aktiven Betätigung des Aktuators - sehr reibungsarm. llnter zunehmender äußerer axialer Belastung der Gewindespindel setzt eine zunehmende elastische Verformung der Anlaufscheibe ein und eine damit einhergehende Einebnung der konvexen Laufbahn. Der anfangs etwa punktförmige Kontakt zwischen Rolle und Laufbahn wird zu einem etwa linienförmigen Kontakt der Rollen mit den und der Laufbahn der Anlaufscheibe. The contact between the rollers of the rolling bearing and the crest line can be made with their middle roller portions of the rollers. All rollers of this roller bearing can be off-axis in the manner described, because due to the more point-like contact this roller bearing is under operating conditions - ie under the acting axial forces during active actuation of the actuator - very low friction. With increasing external axial loading of the threaded spindle, increasing elastic deformation of the thrust washer sets in and the associated leveling of the convex raceway. The initially point-like contact between the roller and the raceway becomes a roughly linear contact between the rollers and the raceway of the thrust washer.
Auf diese Weise wird eine Reibung erzeugt zwischen diesen deachsierten Rollen und den die Laufbahnen tragenden Anlaufscheiben, wenn diese Rollen als Reibwälzkörper an den Laufbahnen abwälzen und rutschen. In this way, friction is generated between these off-axis rollers and the thrust washers carrying the raceways when these rollers roll off and slip as friction rolling elements on the raceways.
In Richtung entlang der Wälzlagerachse gesehen bildet der Reibwälzkörper mit seiner Rotationsachse einen ersten Schenkel eines Winkels alpha und eine gerade Linie, die ausgehend von der Wälzlagerachse die Rotationsachse des Reibwälzkörpers in dessen axialer Mitte schneidet, bildet einen zweiten Schenkel des Winkels alpha. Der zwischen den beiden Schenkeln gebildete Winkel alpha wird abhängig von der gewünschten Reibung eingestellt. Seen in the direction along the roller bearing axis, the friction roller body forms a first leg of an angle alpha with its axis of rotation, and a straight line which, starting from the roller bearing axis, intersects the axis of rotation of the friction roller body in its axial center forms a second leg of the angle alpha. The angle alpha formed between the two legs is adjusted depending on the desired friction.
Die Erfindung hat erkannt, dass für eine Hemmung des Aktuators in Verbindung mit einem Planetenwälzgewindetrieb als Gewindetrieb ein Winkel alpha etwa zwischen 2 Grad und 10 Grad ausreichend sein kann, wenn sämtliche Rollen des Wälzlagers deachsiert angeordnet sind. The invention has recognized that an angle alpha of approximately between 2 degrees and 10 degrees can be sufficient for inhibiting the actuator in connection with a planetary roller screw drive as a screw drive if all rollers of the roller bearing are arranged off-axis.
Je größer dieser Winkel alpha ist, desto höher ist der Gleitreibungsanteil im Reibkontakt zwischen Reibwälzkörper und Laufbahn. Die Reibkraft ist abhängig von der axialen Belastung der Gewindespindel. Der Winkel wird so eingestellt, dass bei einer bestimmten Anzahl von Reibwälzkörpern eine Hemmung des Aktuators sichergestellt ist, wenn äußere axiale Kräfte in die Schubstange eingeleitet werden. ln dem Wälzlager wird ein Reibmoment erzeugt als Produkt der Reibkraft mit ihrem wirksamen Hebelarm um die Rotationsachse des drehangetriebenen Teils des Gewindetriebs. Die Reibkraft wirkt zwischen den Laufbahnen und den Reibwälzkörpern. The larger this angle alpha is, the higher the proportion of sliding friction in the frictional contact between the friction roller body and the raceway. The frictional force depends on the axial load on the threaded spindle. The angle is adjusted in such a way that, with a certain number of friction rolling elements, the actuator is prevented from being blocked when external axial forces are introduced into the connecting rod. A friction torque is generated in the roller bearing as a product of the friction force with its effective lever arm about the axis of rotation of the rotationally driven part of the screw drive. The frictional force acts between the raceways and the friction rolling elements.
Insbesondere im Zusammenhang mit einem steigungstreu angetriebenen Planetenwälzgewindetrieb sorgt ein derart eingerichtetes Wälzlager für eine gewünschte Hemmung des Aktuators, wenn dieser nicht aktiv betrieben wird und axiale Kräfte beispielsweise über eine Schubstange - also auch über die Gewindespindel - in die Mutter und schließlich über das Wälzlager in das Gehäuse eingeleitet werden. Wenn der Gewindetrieb nicht drehangetrieben - ein antreibender Elektromotor abgeschaltet - ist, und eine äußere Axiallast an der Gewindespindel angreift, wird diese Axiallast in das Wälzlager übertragen. Je größer diese Axiallast ist, desto größer ist die elastische Einebnung der konvexen Laufbahn und somit auch eine resultierende Reibkraft in dem Wälzlager. Diese zwischen der Mutter und dem Gehäuse wirkende Reibkraft hemmt eine unerwünschte Verstellung der Schubstange und verhindert eine unerwünschte Rotation der Mutter oder eines drehangetriebenen Planetenrollenkäfigs. Particularly in connection with a planetary screw drive driven with the same pitch, a roller bearing set up in this way ensures the desired inhibition of the actuator when it is not being actively operated and axial forces are transferred, for example, via a push rod - i.e. also via the threaded spindle - into the nut and finally via the roller bearing into the housing are initiated. If the screw drive is not driven in rotation - a driving electric motor is switched off - and an external axial load acts on the screw spindle, this axial load is transferred to the roller bearing. The greater this axial load, the greater the elastic leveling of the convex raceway and thus also the resulting frictional force in the roller bearing. This frictional force acting between the nut and the housing inhibits undesired displacement of the connecting rod and prevents undesired rotation of the nut or a rotationally driven planetary roller cage.
Mit dem Aktuator kann eine Selbsthemmung sichergestellt werden, wenn äußere axiale Kräfte in die Gewindespindel eingeleitet werden. Self-locking can be ensured with the actuator when external axial forces are introduced into the threaded spindle.
Das Wälzlager kann als Axialrollenlager ausgeführt sein. Eine besonders vorteilhafte Weiterbildung ist jedoch durch ein Axialschrägrollenlager angegeben, das sowohl die üblicherweise geringen radialen Kräfte als auch die größeren axialen Kräfte überträgt. Ein separates Radiallager kann in diesem Fall entfallen. The roller bearing can be designed as an axial roller bearing. However, a particularly advantageous development is given by an angular contact roller bearing, which transmits both the usually small radial forces and the larger axial forces. A separate radial bearing can be omitted in this case.
Vorzugsweise weisen beide Anlaufscheiben zwischen deren Außenumfang und Innenumfang an einander zugewandten Stirnseiten jeweils die konvex geformte Laufbahn und an ihren voneinander abgewandten Stirnseiten jeweils eine konkav geformte Stirnfläche auf. Unter angreifenden äußeren axialen Kräften werden beide konvexen Laufbahnen zunehmend eingeebnet unter elastischer Verformung der Anlaufscheiben, wie weiter oben bereits ausgeführt wurde. ln dieser zuletzt beschriebenen Weiterbildung kann es vorteilhaft sein, sämtliche Rollen zu deachsieren, also als Reibwälzkörper in der beschriebenen Weise einzusetzen, um die gewünschte Reibung einzustellen. Both thrust washers preferably have the convexly shaped raceway between their outer circumference and inner circumference on mutually facing end faces and a concavely shaped end face on their end faces facing away from one another. When external axial forces are applied, both convex raceways are increasingly flattened with elastic deformation of the thrust washers, as has already been explained above. In this last-described further development, it can be advantageous to de-axis all the rollers, ie to use them as friction rollers in the manner described, in order to set the desired friction.
Die Rollen dieses Wälzlagers sind in Käfigtaschen eines vorzugsweise aus Stahl gebildeten Rollenkäfigs geführt. Der Rollenkäfig kann so verschleißfest ausgeführt sein, dass er die von den deachsierten Rollen in den Käfig eingeleiteten Kräfte betriebssicher aufnehmen kann.The rollers of this roller bearing are guided in cage pockets of a roller cage, preferably made of steel. The roller cage can be designed to be so wear-resistant that it can reliably absorb the forces introduced into the cage by the off-axis rollers.
Die deachsierten Rollen üben ein Kippmoment in den Käfigtaschen aus. Die Reibung zwischen den Rollen und dem Rollenkäfig vergrößert die Reibleistung und fördert die gewünschte Selbsthemmung, wenn große axiale Kräfte auf die Gewindespindel einwirken. The de-axled rollers exert a tilting moment in the cage pockets. The friction between the rollers and the roller cage increases the friction and promotes the desired self-locking when large axial forces act on the threaded spindle.
Vorzugsweise sind beide Anlaufscheiben an ihren voneinander abgewandten Stirnseiten jeweils mit einer Stützfläche zur Abstützung des Wälzlagers versehen, die radial außerhalb einer Scheitellinie der konvex geformten Laufbahn liegen. Entsprechend der konvexen Formgebung können die beiden Anlaufscheiben an ihren voneinander abgewandten Stirnseiten eine konkav geformte Stirnfläche aufweisen. Preferably, both thrust washers are provided on their end faces facing away from each other with a support surface for supporting the roller bearing, which is located radially outside of a crest line of the convex raceway. Corresponding to the convex shape, the two thrust washers can have a concave end face on their end faces facing away from one another.
Die eine Anlaufscheibe kann verdrehsicher an dem Gehäuse und die andere Laufscheibe kann drehfest an dem Gewindetrieb abgestützt sein, vorzugsweise an dem drehangetriebenen Planetenrollenkäfig des Planetenwälzgewindetriebes. One thrust washer can be secured against rotation on the housing and the other washer can be supported in a torque-proof manner on the screw drive, preferably on the rotary-driven planetary roller cage of the planetary roller screw drive.
Die konkaven Stirnseiten bieten ausreichend Raum für eine elastische Verformung der Anlaufscheiben, wenn große axiale Kräfte über das Wälzlager übertragen werden. Die elastische Verformung kann lediglich im Zehntel mm Bereich liegen. The concave faces provide sufficient space for elastic deformation of the thrust washers when large axial forces are transmitted through the rolling bearing. The elastic deformation can only be in the tenths of a mm range.
Das als Axialschrägrollenlager weitergebildete Wälzlager kann zwei schräg zur Spindelachse des Gewindetriebs angeordnete Anlaufscheiben aufweisen, von denen die eine an dem drehangetriebenen Maschinenteil des Gewindetriebs und die andere an dem Gehäuse abgestützt ist, wobei ein kreisringförmiger Rollenkäfig zwischen die beiden Anlaufscheiben eingesetzt ist, in dessen über den Umfang verteilt angeordneten Käfigtaschen die Rollen geführt sind. Sämtliche Rollen dieses Axialschrägrollenlagers können mit zur Wälzlagerachse radial beabstandet angeordneten Rotationsachsen angeordnet und in den Käfigtaschen geführt sein, wobei eine Spindelachse des Gewindetriebs mit der Wälzlagerachse zusammenfällt. Mit diesem Schrägrollenlager sind ausreichend große Reibleistungen erzielbar, im Fall von unerwünscht großen axialen Kräften. The anti-friction bearing developed as an axial angular contact roller bearing can have two thrust washers arranged at an angle to the spindle axis of the screw drive, one of which is supported on the rotary-driven machine part of the screw drive and the other on the housing, with a circular roller cage being inserted between the two thrust washers, in which via the Circumferentially arranged cage pockets which are guided by rollers. All rollers of this axial angular contact roller bearing can be arranged with axes of rotation arranged radially spaced apart from the roller bearing axis and guided in the cage pockets, with a spindle axis of the screw drive coinciding with the roller bearing axis. Sufficiently large amounts of friction can be achieved with this tapered roller bearing in the case of undesirably large axial forces.
Die eine Anlaufscheibe kann an ihrem radial inneren Umfang mit einem koaxial zur Wälzlagerachse angeordneten hülsenförmigen Ansatz versehen sein, auf dem der mit den Rollen bestückte Rollenkäfig und die andere Anlaufscheibe angeordnet sind. Diese Weiterbildung ermöglicht einen einfachen Zusammenbau der einzelnen Teile des Wälzlagers und dessen einfache Montage in den Aktuator. One thrust washer can be provided on its radially inner circumference with a sleeve-shaped attachment which is arranged coaxially to the roller bearing axis and on which the roller cage fitted with the rollers and the other thrust washer are arranged. This development allows for easy assembly of the individual parts of the rolling bearing and its easy installation in the actuator.
Vorzugsweise ist der Gewindetrieb durch den oben erwähnten Planetenwälzgewindetrieb mit axial vorgespannten Planetenrollen gebildet, die zwischen der Mutter und der Gewindespindel über den Umfang verteilt angeordnet sind, wobei die Mutter zwei quer zur Längsachse geteilte Mutterteile aufweist, die miteinander verschraubt und durch eine Kontermutter gesichert sein können. Die Verschraubung hält die beiden Mutterteile auf eine vorbestimmte Distanz, in der eine Spielfreiheit des Planetenwälzgewindetriebes gewährleistet ist. Vorzugsweise sind die Planetenrollen in Käfigtaschen eines Planetenrollenkäfigs geführt, der drehfest mit einem Antriebsrad verbunden ist für einen Drehantrieb dieses steigungstreu arbeitenden Planetenwälzgewindetriebes. Die Planetenrollen stehen mit ihrem planetenseitigen Rillenprofil mit einem Gewinde der Gewindespindel und mit einem mutterseitigen Rillenprofil der Mutter in Eingriff. The screw drive is preferably formed by the above-mentioned planetary roller screw drive with axially prestressed planetary rollers, which are arranged distributed over the circumference between the nut and the threaded spindle, the nut having two nut parts divided transversely to the longitudinal axis, which can be screwed together and secured by a lock nut . The screw connection keeps the two nut parts at a predetermined distance, in which a freedom from play of the planetary screw drive is guaranteed. Preferably, the planetary rollers are guided in cage pockets of a planetary roller cage, which is non-rotatably connected to a drive wheel for a rotary drive of this planetary roller screw drive, which operates with the same pitch. The planetary rollers mesh with their planet-side grooved profile with a thread of the threaded spindle and with a nut-side grooved profile of the nut.
Derartige, an sich bekannte Planetenwälzgewindetriebe zeichnen sich durch eine hohe Stellgenauigkeit aus. Derartige Planetenwälzgewindetriebe sind im Betrieb leichtgängig, wobei mittels des bevorzugten Axialschrägrollenlagers mit den deachsierten Rollen eine Hemmung erreicht wird, wenn äußere axiale Kräfte an der Gewindespindel angreifen. Betriebsbedingte axiale Kräfte sind ausreichend klein, so dass die Rollen des Wälzlagers in der beschriebenen Weise mehr oder weniger in punktförmigen Kontakt mit den konvex geformten Laufbahnen stehen und einen leichtgängigen Antrieb ermöglichen. Jedenfalls können ausreichend hohe Reibungsverluste bereitgestellt werden, so dass bei großen axialen Lasten eine unerwünschte axiale Verstellung der Gewindespindel ausgeschlossen ist. Planetary screw drives of this type, which are known per se, are characterized by a high positioning accuracy. Such planetary roller screw drives are smooth-running in operation, with the preferred axial angular contact roller bearing with the off-axis rollers inhibiting when external axial forces act on the threaded spindle. Operational axial forces are sufficiently small that the rollers of the roller bearing are in more or less point-like contact with the convex-shaped raceways in the manner described and enable a smooth-running drive. In any case, sufficiently high friction losses can be provided, so that at large axial loads, an unwanted axial displacement of the threaded spindle is excluded.
Vorzugsweise ist dieser Aktuator für eine Hinterachslenkung eines Kraftfahrzeuges weitergebildet, dessen das Gehäuse durchdringende Schubstange über Lenker zwei Räder einer Achse anlenkt, wobei die Gewindespindel Teil der Schubstange ist. This actuator is preferably further developed for a rear-axle steering system of a motor vehicle, the connecting rod of which, penetrating the housing, articulates two wheels of an axle via connecting rods, the threaded spindle being part of the connecting rod.
Nachstehend wird die Erfindung eines in insgesamt sieben Figuren abgebildeten Ausführungsbeispieles näher erläutert. Es zeigen: The invention of an embodiment illustrated in a total of seven figures is explained in more detail below. Show it:
Figur 1 einen erfindungsgemäßen Aktuator in perspektivischer Darstellung, FIG. 1 shows an actuator according to the invention in a perspective view,
Figur 2 einen Längsschnitt durch den Aktuator, wobei lediglich ein Abschnitt dargestellt ist, Figure 2 shows a longitudinal section through the actuator, only one section being shown,
Figur 3 ein Axialschrägrollenlager dieses Aktuators, Figure 3 an axial angular roller bearing of this actuator,
Figur 4 eine Ausschnittvergrößerung der Figur 3 Figure 4 is an enlarged detail of Figure 3
Figur 5 eine weitere Ausschnittvergrößerung der Figur 3, FIG. 5 shows a further detail enlargement of FIG. 3,
Figur 6 ein Rollenkranz des Axialschrägrollenlagers und Figure 6 is a roller and cage assembly of the axial angular contact roller bearing
Figur 7 eine Ausschnittvergrößerung der Figur 6. Figur 1 zeigt einen Aktuator einer Hinterachslenkung eines Kraftfahrzeuges, dessen Gehäuse 1 am Fahrzeug gehaltert ist. Eine Motorwelle eines Elektromotors 2 greift in das Gehäuse 1 ein und ist mit einem nicht abgebildeten Motorritzel versehen. Eine Schubstange 3 durchdringt mit ihren axialen Enden das Gehäuse 1 , die beide mit Gabelköpfen 4 versehen sind, die an nicht abgebildete Lenker angeschlossen werden, um die Hinterräder anzulenken. Die Schubstange 3 wird entlang ihrer Längsachse verschoben, wenn der Aktuator betätigt wird. Figure 7 is an enlarged detail of Figure 6. FIG. 1 shows an actuator of a rear-axle steering system of a motor vehicle, the housing 1 of which is mounted on the vehicle. A motor shaft of an electric motor 2 engages in the housing 1 and is provided with a motor pinion, not shown. A connecting rod 3 penetrates the housing 1 with its axial ends, both of which are provided with clevises 4 which are connected to handlebars, not shown, in order to articulate the rear wheels. The push rod 3 is displaced along its longitudinal axis when the actuator is actuated.
Figur 2 zeigt einen Abschnitt dieses Aktuators im Längsschnitt. Der Elektromotor 2 treibt über einen Zahnriemen 5 einen Gewindetrieb 31 an, der im Ausführungsbeispiel durch einen Planetenwälzgewindetrieb 6 gebildet ist. Der Planetenwälzgewindetrieb 6 ist mittels zweier Wälzlager 32 drehbar in dem Gehäuse 1 gelagert, die im Ausführungsbeispiel durch Axialschrägrollenlager 9 gebildet sind ist. Der Zahnriemen 5 umschlingt das oben genannte Motorritzel des Elektromotors 2 und ein hülsenförmiges Antriebsrad 7, das an seinem zylindrischen Mantel mit einem Zahnprofil 8 für den Zahnriemen 5 versehen ist. Figure 2 shows a portion of this actuator in longitudinal section. The electric motor 2 drives a screw drive 31 via a toothed belt 5 , which is formed by a planetary roller screw drive 6 in the exemplary embodiment. The planetary screw drive 6 is rotatably mounted in the housing 1 by means of two roller bearings 32 which are formed by axial angular contact roller bearings 9 in the exemplary embodiment. The toothed belt 5 wraps around the above-mentioned motor pinion of the electric motor 2 and a sleeve-shaped drive wheel 7 which is provided with a toothed profile 8 for the toothed belt 5 on its cylindrical surface.
Der Planetenwälzgewindetrieb 6 ist gebildet durch eine in dem Gehäuse 1 drehfest angeordnete Gewindespindel 10, die Teil der Schubstange 3 ist, sowie durch eine auf der Gewindespindel 10 drehbar gelagerte - im Ausführungsbeispiel aus miteinander verschraubten Mutterteilen gebildete - Mutter 11, sowie durch über den Umfang verteilt angeordnete Planetenrollen 12, die in Käfigtaschen 13 eines Planetenrollenkäfigs 14 drehbar gelagert sind. Die Mutter 11 ist über Axialwälzlager 33 an dem Planetenrollenkäfig 14 drehbar gelagert. The planetary roller screw drive 6 is formed by a threaded spindle 10 arranged in a rotationally fixed manner in the housing 1, which is part of the connecting rod 3, and by a nut 11 rotatably mounted on the threaded spindle 10 - in the exemplary embodiment formed from nut parts screwed together - and by distributed over the circumference arranged planetary rollers 12 which are rotatably mounted in cage pockets 13 of a planetary roller cage 14. The nut 11 is rotatably mounted on the planetary roller cage 14 via axial roller bearings 33 .
Die Planetenrollen 12 greifen mit ihrem planetenseitigen Rillenprofil 15 sowohl in ein Gewinde 16 der Gewindespindel 10 als auch in ein mutterseitiges Rillenprofil 30 ein. Der Planetenrollenkäfig 14 ist drehfest mit dem hülsenförmigen Antriebsrad 7 verbunden, die die Mutter 11 umschließt. Der Planetenrollenkäfig 14 ist im Ausführungsbeispiel mehrteilig ausgeführt und an seiner dem Axialschrägrollenlager 9 zugewandten Stirnseite mit einer Anlage für das Axialschrägrollenlager 9 versehen. The planetary rollers 12 engage with their groove profile 15 on the planet side both in a thread 16 of the threaded spindle 10 and in a groove profile 30 on the nut side. The planetary roller cage 14 is non-rotatably connected to the sleeve-shaped drive wheel 7 which encloses the nut 11 . The planetary roller cage 14 is designed in several parts in the exemplary embodiment and is provided with a system for the axial angular contact roller bearing 9 on its end face facing the axial angular contact roller bearing 9 .
Die Figuren 3 bis 7 zeigen das Axialschrägrollenlager 9, das zwei aus Blech gebildeteFigures 3 to 7 show the axial angular contact roller bearing 9, the two formed from sheet metal
Anlaufscheiben 17, 18 sowie einen zwischen den beiden Anlaufscheiben 17, 18 angeordneten Rollenkranz 19 aufweist, der einen aus Stahl gebildeten, kreisringförmigen Rollenkäfig 20 und in Käfigtaschen 21 des Rollenkäfigs 20 drehbar geführte Rollen 22 aufweist. Die über den Umfang verteilt angeordneten Käfigtaschen 21 sind deutlich in den Figuren 6 und 7 erkennbar. Thrust washers 17, 18 and one between the two thrust washers 17, 18 arranged roller ring 19 having a formed of steel, circular ring-shaped roller cage 20 and in cage pockets 21 of the roller cage 20 rotatably guided rollers 22. The cage pockets 21 distributed over the circumference can be clearly seen in FIGS.
Die Anlaufscheiben 17, 18 weisen zwischen deren Außenumfang und Innenumfang an einander zugewandten Stirnseiten jeweils eine konvex geformte Laufbahn 23,24 und an ihren voneinander abgewandten Stirnseiten jeweils eine konkav geformte Stirnfläche 25, 26 auf. Die konvex geformten Laufbahnen 24, 25 sind im Ausführungsbeispiel ballig geformt. The thrust washers 17, 18 each have a convex-shaped raceway 23, 24 between their outer circumference and inner circumference on mutually facing end faces and a concave-shaped end face 25, 26 on their end faces facing away from one another. The convex shaped tracks 24, 25 are crowned in the embodiment.
Die Anlaufscheiben 17, 18 weisen an ihren voneinander abgewandten Stirnseiten jeweils eine Stützfläche 27, 28 zur Abstützung des Axialschrägrollenlager 9 an dem Gehäuse 1 und an dem Planetenrollenkäfig 14 auf. Diese Stützflächen 27, 28 sind radial versetzt - hier außerhalb und innerhalb - zu einer Scheitellinie der konvex geformten Laufbahn 23, 24 angeordnet. Diese Anordnung ermöglicht eine elastische Verformung und Einebnung der konvexen Laufbahnen 23, 24, denn die Anlaufscheiben haben an ihrer dem Gehäuse 1 zugewandten Stirnseite ausreichend Platz für eine elastische Auslenkung. The thrust washers 17, 18 each have a support surface 27, 28 for supporting the axial angular roller bearing 9 on the housing 1 and on the planetary roller cage 14 on their end faces facing away from one another. These support surfaces 27, 28 are radially offset - arranged to a crest line of the convex raceway 23, 24 - here outside and inside. This arrangement enables elastic deformation and leveling of the convex raceways 23, 24, since the thrust washers have sufficient space for elastic deflection on their end face facing the housing 1.
Die eine Anlaufscheibe 17 weist an ihrem radial inneren Umfang einen koaxial zur Wälzlagerachse angeordneten hülsenförmigen Ansatz 29 auf, der einstückig an die Anlaufscheibe 17 angeformt ist. Auf dem hülsenförmigen Ansatz 29 sind der Rollenkranz 19 und die andere Anlaufscheibe 18 angeordnet. One thrust washer 17 has on its radially inner circumference a sleeve-shaped extension 29 which is arranged coaxially to the roller bearing axis and is integrally formed on the thrust washer 17 . The roller and cage assembly 19 and the other thrust washer 18 are arranged on the sleeve-shaped extension 29 .
Den Figuren 6 und 7 kann entnommen werden, dass sämtliche Rollen 22 mit ihren Rotationsachsen deachsiert sind um einen Winkel alpha. Die Rotationsachse schneidet nicht die Wälzlagerachse A. Die Rotationsachse tangiert einen Kreis, der koaxial um die Wälzlagerachse A herum gedacht ist. Der Winkel alpha wird eingeschlossen von einem Schenkel, der zusammenfällt mit der Rotationsachse der Rolle 22, sowie einem Schenkel, der die Rotationsachse in Rollenmitte und die Wälzlagerachse A schneidet. Die Wälzlagerachse A fällt mit der Spindelachse des Planetenwälzgewindetriebs 6 zusammen. Im Betrieb des Aktuators sind die Stellkräfte in axialer Richtung ausreichend gering, so dass in den Axialschrägrollenlagern 9 ein mehr oder weniger punktförmiger Kontakt zwischen den Rollen 22 und den Scheitellinien der konvexen Laufbahnen 23, 24 der Anlaufscheiben 17, 18 besteht. (Figur 4). Wenn große äußere axiale Kräfte auf die Gewindespindel ausgeübt werden, verformen sich die Anlaufscheiben 17, 18 elastisch und die konvexen Laufbahnen 23, 24 werden zunehmend eingeebnet (Figur 5). Es stellt sich ein eher linienförmiger Kontakt zwischen den Rollen 22 und den Laufbahnen 23, 24 ein. Die deachsierten Rollen 22 rollen und gleiten über die Laufbahnen 23, 24 und erzeugen ein Reibmoment, das eine Rotation des Planetenrollenkäfigs 14, wenn dieser rückwärts über die Gewindespindel 10 und die Planetenrollen 12 belastet wird. Auf diese Weise ist sichergestellt, dass eine rückwärtige Betätigung des Planetenrollengewindetriebes 6 unterbleibt, der Aktuator also gehemmt ist. It can be seen from FIGS. 6 and 7 that all of the rollers 22 have their axes of rotation offset by an angle alpha. The axis of rotation does not intersect the axis A of the roller bearing. The angle alpha is enclosed by a leg which coincides with the axis of rotation of the roller 22 and a leg which intersects the axis of rotation in the middle of the roller and the axis A of the roller bearing. The roller bearing axis A coincides with the spindle axis of the planetary screw drive 6 . During operation of the actuator, the actuating forces in the axial direction are sufficiently low, so that there is more or less point-like contact between the rollers 22 and the crest lines of the convex raceways 23, 24 of the thrust washers 17, 18 in the axial angular roller bearings 9. (Figure 4). If large external axial forces are exerted on the threaded spindle, the thrust washers 17, 18 deform elastically and the convex raceways 23, 24 are increasingly flattened (Figure 5). A more linear contact between the rollers 22 and the raceways 23, 24 occurs. The de-axled rollers 22 roll and slide over the raceways 23, 24 and create a frictional torque which causes rotation of the planetary roller cage 14 when it is loaded backwards via the lead screw 10 and the planetary rollers 12. In this way, it is ensured that the planetary roller screw drive 6 is not actuated backwards, ie the actuator is inhibited.
Bezugszeichen Reference sign
Gehäuse Housing
Elektromotor electric motor
Schubstange push rod
Gabelkopf clevis
Zahnriemen timing belt
Planetenwälzgewindetrieb planetary screw drive
Antriebrad drive wheel
Zahnprofil tooth profile
Axialschrägrollenlager Axial angular contact roller bearings
Gewindespindel lead screw
Mutter mother
Planetenrolle planetary roll
Käfigtasche cage bag
Planetenrollenkäfig planetenseitiges Rillenprofil Planet roller cage planet side groove profile
Gewinde thread
Anlaufscheibe thrust washer
Anlaufscheibe thrust washer
Rollenkranz roller wreath
Rollenkäfig roller cage
Käfigtasche cage bag
Rolle konvexe Laufbahn konvexe Laufbahn konkave Laufbahn konkave Laufbahnroller convex raceway convex raceway concave raceway concave raceway
Stützfläche support surface
Stützfläche hülsenförmiger Ansatz mutterseitiges RillenprofilSupport surface, sleeve-shaped attachment, grooved profile on the nut side
Gewindetriebscrew drive
Wälzlager roller bearing
Axialwälzlager thrust roller bearing

Claims

Ansprüche Aktuator für eine Lenkeinrichtung eines Kraftfahrzeuges, mit einem Gehäuse (1), und mit einem in dem Gehäuse (1) angeordneten, eine Gewindespindel (10) und eine Mutter (11) aufweisenden Gewindetrieb (31) , der in axialer Richtung mittels eines Wälzlagers (32) drehbar gelagert ist, dessen Rollen (22) über den Umfang verteilt um eine Wälzlagerachse (A) herum angeordnet sind und an Laufbahnen (23, 24) des Wälzlagers (32) abwälzen, wobei wenigstens eine der Rollen (22) mit ihrer Rotationsachse radial beabstandet zur Wälzlagerachse (A) angeordnet ist, dadurch gekennzeichnet, dass wenigstens eine der Laufbahnen (23, 24) im Längsschnitt durch das Wälzlager (32) gesehen konvex geformt und an einer federelastisch verformbaren Anlaufscheibe (17, 18) ausgebildet ist. Aktuator nach Anspruch 1 , dessen Rollen (22) bei geringerer axialer Belastung der Gewindespindel (10) des Gewindetriebs (31) einen etwa punktförmigen Kontakt mit den Laufbahnen (23, 24) haben und bei größerer axialer Belastung der Gewindespindel (10) unter elastischer Verformung der Anlaufscheibe (17, 18) und Einebnung der Laufbahn (23, 24) einen etwa linienförmigen Kontakt mit den Anlaufscheiben (17, 18) haben. Aktuator nach Anspruch 1 oder 2, dessen Rollen (22) in Käfigtaschen (21) eines aus Stahl gebildeten Rollenkäfigs (20) geführt sind. Aktuator nach Anspruch 1 oder 2, dessen beide aus Blech gebildete Anlaufscheiben (17, 18) zwischen deren Außenumfang und Innenumfang an einander zugewandten Stirnseiten jeweils die konvex geformte Laufbahn (23, 24) und an ihren voneinander abgewandten Stirnseiten jeweils eine konkav geformte Stirnfläche (25, 26) aufweist. Aktuator nach Anspruch 4, dessen Anlaufscheiben (17, 18) an ihren voneinander abgewandten Stirnseiten jeweils mit einer Stützfläche (27, 28) zur Abstützung des Wälzlagers (32) versehen sind, die radial beabstandet zu einer Scheitellinie der konvex geformten Laufbahn (23, 24) liegen. Aktuator nach einem der Ansprüche 3 bis 5, dessen Wälzlager (32) als Axialschrägrollenlager (9) ausgebildet ist, das zwei schräg zur Spindelachse des Gewindetriebs angeordnete Anlaufscheiben (17, 18) aufweist, von denen die eine an dem Gewindetrieb (31) und die andere an dem Gehäuse (1) abgestützt ist, und das einen kreisringförmigen Rollenkäfig (20) aufweist, in dessen über den Umfang verteilt angeordneten Käfigtaschen (21) die Rollen (22) geführt sind. Aktuator nach Anspruch 5, dessen sämtliche Rollen (22) mit zur Wälzlagerachse (A) radial beabstandet angeordneten Rotationsachsen angeordnet und in den Käfigtaschen (21) geführt sind, und dessen Spindelachse des Gewindetriebs (31) mit der Wälzlagerachse (A) zusammenfällt. Aktuator nach Anspruch 6, dessen eine Anlaufscheibe (17) an ihrem radial inneren Umfang mit einem koaxial zur Wälzlagerachse (A) angeordneten hülsenförmigen Ansatz (29) versehen ist, auf dem der mit den Rollen (22) bestückte Rollenkäfig (20) und die andere Anlaufscheibe (18) angeordnet sind. Aktuator nach einem der Ansprüche 1 bis 8, dessen Gewindetrieb (31) als Planetenwälzgewindetrieb (6) ausgebildet ist, der einen drehangetriebenen Planetenrollenkäfig (14) aufweist, in dessen Käfigtaschen (13) angeordnete Planetenrollen (12) mit ihrem planetenseitigen Rillenprofil (15) mit einem Gewinde (16) der Gewindespindel (10) und mit einem mutterseitigen Rillenprofil (30) der Gewindemutter (11) in Eingriff sind. Aktuator einer Hinterachslenkung eines Kraftfahrzeuges nach Anspruch 9, dessen Elektromotor (2) über ein Rotation-Rotationgetriebe den Planetenrollenkäfig (14) antreibt, und dessen Gewindespindel (10) Teil einer Schubstange (3) ist, die mit ihren Enden das Gehäuse (1) durchdringt und an Lenker angeschlossen ist. Claims An actuator for a steering device of a motor vehicle, with a housing (1) and with a threaded drive (31) which is arranged in the housing (1) and has a threaded spindle (10) and a nut (11), which is supported in the axial direction by means of a roller bearing (32) is rotatably mounted, the rollers (22) of which are distributed over the circumference around a roller bearing axis (A) and roll on raceways (23, 24) of the roller bearing (32), with at least one of the rollers (22) with its axis of rotation is arranged at a radial distance from the roller bearing axis (A), characterized in that at least one of the raceways (23, 24) has a convex shape when viewed in longitudinal section through the roller bearing (32) and is formed on a resiliently deformable thrust washer (17, 18). Actuator according to Claim 1, the rollers (22) of which have approximately punctiform contact with the raceways (23, 24) when the threaded spindle (10) of the screw drive (31) is subjected to a lower axial load and are subject to elastic deformation when the threaded spindle (10) is subjected to a greater axial load of the thrust washer (17, 18) and leveling of the raceway (23, 24) have approximately linear contact with the thrust washers (17, 18). Actuator according to Claim 1 or 2, the rollers (22) of which are guided in cage pockets (21) of a roller cage (20) made of steel. Actuator according to Claim 1 or 2, the two thrust washers (17, 18) formed from sheet metal having the convexly shaped raceway (23, 24) between their outer circumference and inner circumference on mutually facing end faces and a concavely shaped end face (25 , 26). Actuator according to Claim 4, the thrust washers (17, 18) of which are each provided with a support surface (27, 28) for supporting the roller bearing (32) on their end faces which face away from one another, which surface is radially spaced from an apex line of the convexly shaped raceway (23, 24 ) lie. Actuator according to one of Claims 3 to 5, whose roller bearing (32) is designed as an axial angular roller bearing (9) which has two thrust washers (17, 18) arranged at an angle to the spindle axis of the screw drive, one of which is on the screw drive (31) and the the other is supported on the housing (1), and which has an annular roller cage (20) in whose cage pockets (21) distributed over the circumference the rollers (22) are guided. Actuator according to Claim 5, all of whose rollers (22) are arranged with axes of rotation which are arranged at a radial distance from the roller bearing axis (A) and are guided in the cage pockets (21), and whose spindle axis of the screw drive (31) coincides with the roller bearing axis (A). Actuator according to Claim 6, one thrust washer (17) of which is provided on its radially inner circumference with a sleeve-shaped projection (29) arranged coaxially with the roller bearing axis (A), on which the roller cage (20) fitted with the rollers (22) and the other Thrust washer (18) are arranged. Actuator according to one of Claims 1 to 8, whose screw drive (31) is designed as a planetary screw drive (6) which has a rotationally driven planetary roller cage (14), in whose cage pockets (13) planetary rollers (12) are arranged with their planet-side groove profile (15). a thread (16) of the threaded spindle (10) and with a nut-side groove profile (30) of the threaded nut (11) are engaged. Actuator of a rear-axle steering of a motor vehicle according to Claim 9, whose electric motor (2) drives the planetary roller cage (14) via a rotary/rotary gear, and whose threaded spindle (10) is part of a connecting rod (3), the ends of which penetrate the housing (1). and connected to handlebars.
PCT/DE2021/100871 2020-12-01 2021-11-03 Actuator for a steering device of a motor vehicle WO2022117142A1 (en)

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DE102020131828.6A DE102020131828B4 (en) 2020-12-01 2020-12-01 Actuator for a steering device of a motor vehicle

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