EP3475147A1 - Ball screw of an electromechanical power steering system having an integrated angular-contact ball bearing - Google Patents
Ball screw of an electromechanical power steering system having an integrated angular-contact ball bearingInfo
- Publication number
- EP3475147A1 EP3475147A1 EP17731905.0A EP17731905A EP3475147A1 EP 3475147 A1 EP3475147 A1 EP 3475147A1 EP 17731905 A EP17731905 A EP 17731905A EP 3475147 A1 EP3475147 A1 EP 3475147A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- bearing
- ball
- power steering
- electromechanical power
- ball nut
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
Links
Classifications
-
- 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
- B62D5/0445—Screw drives
- B62D5/0448—Ball nuts
-
- 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
- F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
- F16C19/14—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load
- F16C19/18—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls
- F16C19/181—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact
- F16C19/183—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles
-
- 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
- F16H25/2204—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls
- F16H25/2214—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls with elements for guiding the circulating balls
-
- 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
Definitions
- the present invention relates to an electromechanical power steering system having the features of the preamble of claim 1.
- a torque is generated via an electric motor which is transmitted to a transmission and there superimposed on the steering torque introduced by the driver.
- a generic electromechanical power steering has a servomotor which acts on a ball nut of a ball screw.
- the ball nut is over revolving balls with a ball screw in
- Engaging which is arranged on the outer circumference of a rack, which is part of a rack and pinion steering.
- a rotation of the ball nut causes an axial displacement of the rack, whereby a steering movement of the driver is supported.
- the ball screw is coupled via a toothed belt with the electric motor.
- the ball nut is rotatably mounted in a ball bearing in the steering housing. Forces acting on the off-axis rack create rack tilting torques that must be absorbed by the bearing.
- the bearing is also subject to temperature influences, which result in the operation due to the different thermal expansion coefficients of the bearing shells and the steering housing, for example, to a formation of gaps in the bearing seat or damage to the components, if they are not compensated.
- angular contact ball bearings for mounting the ball nut.
- Angular contact ball bearings can absorb high axial and tilting forces without being damaged. However, they can only be produced at great expense and therefore cost-intensive.
- the publication US 2015/0183455 AI discloses two angular contact ball bearings for supporting a ball nut of a ball screw. The bearings each have a bearing inner and outer bearing ring, between which balls are arranged. The two bearing outer rings are spring-supported on one side of the housing. It is disadvantageous that a large number of components is necessary, which require space and cause costs.
- an electromechanical power steering system for a motor vehicle is provided with a servomotor which drives an axially displaceable member via a ball nut rotatably supported in a bearing in a bearing, the ball nut being engaged with a threaded spindle formed on the member, and the bearing is a double-row angular contact ball bearing with a one-piece bearing inner ring.
- the arrangement of an angular ball bearing, the storage is particularly tipping.
- the one-piece bearing inner ring allows a compact design, which is inexpensive to manufacture by a reduced number of components.
- the contact angle of the double-row angular contact ball bearing are selected so that forms a non-zero support distance.
- the bisecting line of the two contact connecting lines is defined as the connecting line.
- this support distance is in a range of minimum the simple diameter of the balls of the angular contact ball bearing and three times the diameter of the balls of the angular contact ball bearing.
- this support distance it is preferable to form this support distance in a range of 1, 5 times to 2.5 times, and more preferably, 2 times the diameter of the balls of the angular contact ball bearing.
- the smaller ball diameter is to be regarded as a standard.
- the contact angles of both rows of the double-row angular contact ball bearing are the same, which simplifies the production.
- the bearing outer ring is designed in two parts.
- the ball guide can thus be arranged between the bearing outer rings, whereby the bearing is as compact as possible.
- a pulley is connected directly and rotationally fixed, which is also disposed between the bearing outer rings.
- the one-piece bearing inner ring is formed by the ball nut.
- the distance along the bearing axis between the ball centers of the angular contact bearing in a range of at least three times and five times the ball diameter is formed. It is preferable to have this distance in a range of 4.5 times the ball diameter. Trains of the angular bearing.
- the ball nut has at its ends on its outer circumferential surface in each case a circumferential recess which forms a ball raceway of a row of the double-row angular contact ball bearing.
- the component is a rack of a rack and pinion steering gear.
- Figure 1 a schematic representation of an electromechanical power steering with ball screw
- FIG. 2 shows a three-dimensional view of a ball screw according to the invention without the enclosing housing
- FIG. 3 shows a longitudinal section through an angular contact ball bearing of a power steering according to the invention
- Figure 4 a partially exploded view of the angular contact ball bearing
- Figure 5 a partially exploded view of the ball screw with
- FIG. 6 a three-dimensional view of the ball nut
- Figure 7 a spatial representation of the ball return in top view, as well
- FIG. 8 a spatial representation of the ball return in a view from below.
- FIG. 1 shows an electromechanical motor vehicle steering system 1 with a steering wheel 2, which is provided with an upper steering shaft 3 and a lower steering shaft 4 rotatably coupled, shown schematically.
- the upper steering shaft 3 is connected via a torsion bar in functional connection with the lower steering shaft 4.
- the lower steering shaft 4 is rotatably connected to a pinion 5.
- the pinion 5 meshes in a known manner with a toothed segment 6 'of a rack 6.
- the rack 6 is slidably mounted in a steering housing in the direction of its longitudinal axis. At its free ends, the rack 6 is connected via ball joints, not shown, with tie rods 7.
- the tie rods 7 themselves are connected in a known manner via steering knuckles, each with a steered wheel 8 of the motor vehicle.
- a rotation of the steering wheel 2 leads via the connection with the steering shaft 3, 4 and the pinion 5 to a longitudinal displacement of the rack 6 and thus to a pivoting of the steered wheels 8.
- the steered wheels 8 learn about a roadway 80 a reaction, the steering movement counteracts. For pivoting the wheels 8 consequently a force is required which makes a corresponding torque on the steering wheel 2 required.
- An electric motor 9 of a servo unit 10 is provided to assist the driver in this steering movement.
- the electric motor 9 drives a ball nut 11 of a ball screw 12 via a belt drive 11.
- a rotation of the nut causes the threaded spindle of the ball screw 12, which is part of the rack 6, in an axial movement, which ultimately causes a steering movement for the motor vehicle.
- electromechanical power steering with mechanical coupling between steering wheel 2 and steering pinion 5 is shown here in the example, the invention can also be used for motor vehicle steering systems in which no mechanical coupling is present. Such steering systems are known by the term steer-by-wire.
- the ball screw is shown spatially.
- the threaded spindle 6 " is part of the toothed rack 6 and is arranged at a distance from the toothed segment 6 '.
- the ball nut 13 has a pulley 14 on its outer peripheral surface.
- the ball nut 13 is in a double row Angular contact ball bearings 15 rotatably mounted.
- the bearing 15 has a single common inner ring 16 which is formed by the ball nut 13.
- the ball nut 13 at its ends 13 'on its Wennishs- surface 16 each have a circumferential recess 17 for a ball raceway.
- the recess 17 and the raceway profile is designed according to an angular contact ball bearing 15.
- the raceway profile 17 and / or the sleeve of the angular ball bearing may be formed as a Gothic profile, so that a point contact between the raceway and balls 100 is formed. This allows a uniform load distribution, high rigidity and better running characteristics with more accurate guidance.
- the balls have a two-point contact between the recess 17 and the sleeve 19th
- the end 13 'of the ball nut 13 may be a four-point contact between the ends 13 'of the ball nut 13 and the sleeve.
- the end 13 'of the ball nut 13 may be a four-point contact between the ends 13 'of the ball nut 13 and the sleeve.
- Ball nut be designed as a funnel shape.
- the bearing 15 further includes an outer ring 18, respectively.
- the outer rings 18 are each received in a separate sleeve 19, which in a
- the sleeve 19 is preferably formed of a material having a greater thermal expansion than aluminum and steel.
- the sleeve 19 is preferably made of a plastic, particularly preferably PA66GF30
- the sleeve 19 is preferably made of plastic and compensates thermal expansions between the gear housing 21 and the Kugelmuttertrieb 12th
- the sleeve comprises a circular cylindrical peripheral wall 191, which encloses the bearing 15 and the bearing shaft 24, and a circular cylindrical bottom portion 192 which extends radially inwardly in the direction of the bearing axis 24 and has a circular cylindrical opening 193 which surrounds the bearing axis 24.
- the two separate sleeves 19 are preferably arranged such that the two bearings 15 are arranged between the two bottom portions 192.
- the bottom portions 192 are formed flat with preferably constant thickness. But it is also conceivable and possible to To provide targeted areas with grooves, engravings or ribs or a waveform, for example, to influence the lubrication and / or the heat properties targeted.
- the sleeve in its peripheral wall 191 recesses, preferably in the direction of the bearing axis 24 extending slots 194 have. These slots preferably extend to the open end of the peripheral wall 191, which is directed away from the bottom portion 192. In other words, the slots 194 are opened in the direction of the pulley 14.
- the sleeve 19 is preferably made in one piece from a single component, preferably integrally formed from a single material, particularly preferably in an injection molding process.
- a corrugated spring 22 is disposed in the sleeve 19 in the preferred embodiment, which biases the bearing 15 in the axial direction.
- the corrugated spring 22 is located between sleeve 19 and bearing outer ring 18.
- the combination of sleeve 19 and wave spring 22 can be
- this wave spring 22 can be replaced by a plate spring or by a combination of plate spring and wave spring.
- the balls 100 of the angular contact ball bearing 15 are guided in a ball cage 101.
- the raceways of the double-row angular contact ball bearing 15 are designed so that the connecting lines 23, 23 ', 23 ", 23"' of the contact points between ball and raceways intersect the bearing axis 24 lying between the outer rings 18. Between the two points of intersection with the bearing axis 24, a predefined support distance X is formed. Due to the large support distance X, the bearing 15 is particularly tipping. For a particularly high Tilting stiffness is the support distance X preferably in an interval between the single and three times the diameter of the balls 100 of
- Angular bearing Particularly preferable is a support distance of the
- double diameter of the balls 100 corresponds to the angular contact ball bearing.
- the bearing surface of the ball 100 on the raceway surface 17 and an inner surface of the sleeve preferably corresponds to a quarter ball peripheral surface. It remains preferable on both the raceway surface and on the inner surface of the sleeve, an undercut, which is not touched by the ball.
- a contact angle ⁇ the angle is denoted by a line connecting the two points of contact between ball 100 and raceways with the
- Radial level includes and under which the load is transmitted from one career to the other.
- the contact angle for both rows of the bearing 15 is equal.
- the optimum tilting rigidity of the bearing 15 can be set at a specific contact angle ⁇ .
- the ball nut 13 is shown with attached deflecting body 26.
- the ball nut 13 carries on its inside a ball screw in which roll in a conventional manner balls.
- the ball nut 13 has two penetrating recesses 27. In each case a recess 27 is provided for the entry or exit of balls 28 for the external ball return to the opposite end of the ball screw.
- the ball return 25, which connects the two recesses 27 with each other, is at least partially formed by the deflection body 26.
- the ball return 25 is U-shaped.
- the return channel is at least partially formed by a recess 29 in the deflecting body 26 and two adjoining pin 30.
- the recess 29 is arranged diagonally over the deflection body 26, which is adapted as an attachment on its inside to the curvature of the top of the ball nut 13 and in
- Circumferential direction extends over a limited sector of the ball nut 13.
- the deflecting body 26 is inserted by means of the pins 30 in the two recesses 27 of the ball nut 13, so that the
- Ball return 25 is connected to both ends of the ball screw.
- the bearing 15 of the ball nut 13 is designed so that the ball return 25 and the deflecting 26 can be arranged between the ball nut and pulley.
- the ball return or the deflecting thus finds space within the double row bearing, whereby the arrangement is particularly compact.
- the power steering system according to the invention thus has a bearing which has an improved tilting rigidity compared to conventional bearings. It can transmit high axial forces and has a reduced number of components due to the integrated inner ring in the ball nut, which has a positive effect on the costs.
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Power Steering Mechanism (AREA)
- Transmission Devices (AREA)
- Rolling Contact Bearings (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102016007541.4A DE102016007541A1 (en) | 2016-06-22 | 2016-06-22 | Ball screw drive of an electromechanical power steering with integrated angular contact ball bearing |
PCT/EP2017/065361 WO2017220715A1 (en) | 2016-06-22 | 2017-06-22 | Ball screw of an electromechanical power steering system having an integrated angular-contact ball bearing |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3475147A1 true EP3475147A1 (en) | 2019-05-01 |
Family
ID=59093580
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP17731905.0A Withdrawn EP3475147A1 (en) | 2016-06-22 | 2017-06-22 | Ball screw of an electromechanical power steering system having an integrated angular-contact ball bearing |
Country Status (5)
Country | Link |
---|---|
US (1) | US20190263443A1 (en) |
EP (1) | EP3475147A1 (en) |
CN (1) | CN109311507B (en) |
DE (1) | DE102016007541A1 (en) |
WO (1) | WO2017220715A1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102016223610A1 (en) * | 2016-11-29 | 2018-05-30 | Schaeffler Technologies AG & Co. KG | Threaded nut for a ball screw drive |
JP2021076178A (en) * | 2019-11-07 | 2021-05-20 | 日本精工株式会社 | Power transmission device |
CN113074227A (en) * | 2020-01-06 | 2021-07-06 | 陈鹏任 | Bearing screw device |
DE102020208584A1 (en) * | 2020-07-08 | 2022-01-13 | Thyssenkrupp Ag | Power steering for a motor vehicle |
CN112032191A (en) * | 2020-08-26 | 2020-12-04 | 人本股份有限公司 | Thrust angular contact ball bearing for steering gear |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL1015601C2 (en) * | 2000-07-04 | 2002-01-08 | Skf Eng & Res Centre Bv | Bearing unit with integrated nut, and actuator with such a unit. |
DE112005001870T5 (en) * | 2004-08-06 | 2007-07-05 | Nsk Ltd. | Electric power steering device |
CN201021709Y (en) * | 2006-11-29 | 2008-02-13 | 李敬宇 | Ball bearing bolt device and rolling spiral drive device |
JP2013103696A (en) * | 2011-11-16 | 2013-05-30 | Jtekt Corp | Electric power steering system |
US9550518B2 (en) | 2013-12-31 | 2017-01-24 | Trw Automotive U.S. Llc | Electric power steering assembly |
CN203793407U (en) * | 2014-01-28 | 2014-08-27 | 株式会社捷太格特 | Rotary device |
CN203770410U (en) * | 2014-03-09 | 2014-08-13 | 宁波慈兴轴承有限公司 | Double-outer-ring angular contact ball nut bearing component |
CN204452566U (en) * | 2014-12-31 | 2015-07-08 | 天合汽车零部件(上海)有限公司 | The integrated bearing-type ball-screw nut structure of automobile electric booster steering system |
-
2016
- 2016-06-22 DE DE102016007541.4A patent/DE102016007541A1/en not_active Withdrawn
-
2017
- 2017-06-22 CN CN201780038408.XA patent/CN109311507B/en active Active
- 2017-06-22 WO PCT/EP2017/065361 patent/WO2017220715A1/en unknown
- 2017-06-22 EP EP17731905.0A patent/EP3475147A1/en not_active Withdrawn
- 2017-06-22 US US16/309,543 patent/US20190263443A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
CN109311507A (en) | 2019-02-05 |
US20190263443A1 (en) | 2019-08-29 |
WO2017220715A1 (en) | 2017-12-28 |
DE102016007541A1 (en) | 2017-12-28 |
CN109311507B (en) | 2022-03-29 |
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