DE102012007329B4 - Shaft-hub-connection - Google Patents

Abstract

A shaft-hub connection comprising: a first component having an axial abutment shoulder (110) and a circumferential annular groove (103), a second component having a rolling body raceway (116) disposed on the first component and secured to the axial abutment shoulder (103) is supported, and a fastening ring (104) which is supported with a first contact surface (114) on a flank (107) of the first component and with a second abutment surface (115) on the second component to the second component with the axial abutment shoulder (110) of the first component, wherein either the first component is a shaft (101) and the second component is a hub (102) or the first component is a hub and the second component is a shaft, characterized in that the first and second abutment surface (114, 115) of the mounting ring (104) enclose an angle in the range of 5 ° to 50 ° with each other, characterized in that the fastening ring (104), which a rolling bearing as the second s defines a component on a ball screw nut as a first component, has a cylindrical section (118) which adjoins a radial flange (117) having the second contact surface (115), wherein the rolling element track (116) extends radially a distance h0 from the seat (106) of the second component on the first component and the wall thickness h3 of the cylindrical portion (118) is less than or equal to h0.

Description

The invention relates to a shaft-hub connection according to the preamble of claim 1. Furthermore, the invention relates to a ball screw nut with a rolling bearing, which are connected by means of such a shaft-hub connection, and finally to an electromechanical steering with ball screw ,

The person skilled in the art is generally aware of fixing rolling bearings axially by means of retaining rings, nuts or the like on shafts or hubs. Furthermore, it is known to perform a fixation and centering by means of a press fit.

In certain installation situations, such as the attachment of a main bearing on a ball screw nut in an electromechanical vehicle steering (see, for. DE 10 2009 004 438 A1 . DE 10 2007 024 328 A1 or EP 1 237 776 B2 ), a high axial preload of the bearing ring of the main bearing is required due to the axial forces occurring. In view of a precise steering behavior and a long service life of the steering, however, deformations of the rolling element raceways of the main bearing must nevertheless be avoided, since such would impair the running of the rolling elements.

Conventional shaft retaining rings are unsuitable because they are unable to support large axial forces. In addition, such retaining rings on the shelf axial play on.

Out DE 2 204 831 A a shaft-hub connection is known, which comprises in the following: a shaft with an axial abutment shoulder and a circumferential annular groove, a shaft arranged on the hub, which is supported on the axial abutment shoulder, and a fastening ring which is connected to a first abutment surface supported on the hub and with a second abutment surface on an edge of the annular groove to clamp the hub with the axial abutment shoulder of the shaft. With such a shaft-hub connection let a hub set free of play on a shaft, since any play in the axial direction is repealed by the deformation of the mounting ring. In the known shaft-hub connection, however, there is the problem that at high axial forces of the fastening ring can be blown up.

Although shaft nuts allow a more stable backlash-free axial attachment, but require a relatively large amount of space and lead to a tension of the bearing ring, which causes a certain deformation of the rolling body raceway when the bearing ring is not made very solid. In addition, the production is very complicated, since a thread must be cut on the shaft. This applies in particular when the shaft is a ball screw nut made of bearing steel.

It has therefore already been attempted to integrate the bearing inner ring of a main bearing of a ball screw nut directly into the ball screw nut (cf. DE 10 2009 008 591 A1 or DE 10 2009 037 872 A1 ), which, however, compared to the use of separate standard bearings a significant additional manufacturing effort.

A shaft-hub connection according to the preamble of claim 1 is made DE 31 32 443 A1 known. Another shaft-hub connection is off JP2007182989 A1 known.

The invention has for its object to provide alternatives to conventional main bearing attachment. In particular, the invention aims to provide a shaft-hub connection, which has a high axial load capacity, has a low space requirement, is free of radial and axial clearance and avoids deformations hub side Wälzkörperlaufbahnen.

This object is achieved by a shaft-hub connection according to claim 1.

The inventive solution allows for backlash-free axial clamping of the two components high axial load capacity of the compound. Preferably, the mounting ring is pressed by an axially and radially acting on the same tool between the annular groove and the hub. Due to the deformation of the mounting ring any manufacturing tolerances can be easily compensated. As a result, the interface between shaft and hub with low accuracy and thus can manufacture cost. The fastening ring is a simple and inexpensive to produce in its form component.

Due to the special design of the contact surfaces, a good support in the annular groove is made possible on the one hand. On the other hand results in a favorable force on the part of the second component. The force flow in the second component can thus be guided substantially parallel to the longitudinal axis of the second component and thus past a rolling body raceway present thereon.

Compared to DE 2 204 831 A can support significantly larger axial forces.

Advantageous embodiments of the invention are specified in further claims.

Preferably, the attachment ring has an angled profile cross-section, whereby the angle of attack between the first and second contact surface can be realized particularly easily. In principle, however, the configuration of the fastening ring between the contact surfaces can be adapted as desired to the respective installation situation. Thus, for example, instead of a bend and a curved transition possible.

According to a further advantageous embodiment, the fastening ring has a section with a constant inner diameter and an axially adjoining section with a tapering inner diameter. At this time, the first abutment surface engaging with the flank of the annular groove is disposed at the tapered inner diameter portion, and the second abutment surface engaging with the hub is disposed at the constant inner diameter portion. This allows in a simple manner a particularly favorable introduction of force into the hub with a substantially axis-parallel force flow both in the section with a constant inner diameter and in the adjacent hub.

In the event that the first component is a hub and the second component is a shaft, this applies analogously. The fastening ring in this case has a section with a constant outer diameter and an axially adjoining section with an enlarging outer diameter, wherein the flank of the annular groove engaging first contact surface is arranged on the section with increasing outer diameter and the shaft with in Engaging second abutment surface is disposed on the portion of constant outer diameter.

Preferably, the fastening ring is pressed with the annular groove, whereby a play-free determination can be realized without much effort.

Preferably, the fastening ring fills out the annular groove in the deformed state. This promotes a high axial load capacity of the connection.

According to a further advantageous embodiment, the second contact surface of the fastening ring in a plane is flat against the second component. This allows a good reproducibility of the introduction of force into the second component and of the force flow in the same.

According to a further preferred embodiment, the flank of the annular groove, which supports the first abutment surface of the fastening ring, is angled relative to the radial direction of the first component with an angle of attack in the range of 5 ° to 50 °. Furthermore, the second component has a support surface for supporting the second contact surface of the fastening ring, wherein this support surface extends in the radial direction of the first component.

The fastening ring can be designed in the simplest case as a cylindrical sleeve, which is partially pushed into the annular groove. Preferably, however, forms the portion with a constant inner or outer diameter at its end facing the hub a radially projecting flange, whose end face is the second bearing surface. As a result, a further increased load capacity is achieved since a break-off of the mounting ring is prevented. The mounting ring can be made in this case with an L-shaped profile cross-section, the sleeve-shaped portion beyond the flange is in turn at least partially urged into the annular groove.

Further, the maximum radial height h _{2 of} the contact of the axial abutment shoulder with the second component can be adjusted with h ₀ +/- 10% in order to further improve the force flow, namely to forward it substantially to the rolling element raceway and deformations of the rolling element track to keep the axial setting of the second component low. From the axial fixing remain at most low, purely axial deformations, which are reflected in a controllable reduction of the axial play of the bearing. Since the clamping conditions are very well reproducible, the reduction of the axial play of the rolling bearing can be compensated by designing the bearing.

In a preferred embodiment variant, the above-described shaft-hub connection serves to axially fix a roller bearing on a ball screw nut. In this case, the shaft is the ball screw nut and the hub is an inner ring of the rolling bearing. However, other purposes are possible in which high axial forces occur. For example, a pinion can be secured to a shaft in the same way.

The above-described invention has arisen in the context of the particular requirements of electromechanical steering systems which comprise in the transmission path between a motor shaft of an electric motor and a spindle portion of a rack of the steering a ball screw nut supported in a steering gear housing.

In particular, the invention provides an electromechanical steering having a ball screw whose ball screw nut is rotatably supported and axially fixed to a steering gear housing via a rolling bearing, an inner ring of the rolling bearing being fixed to an outer peripheral portion of the ball screw nut by means of a shaft-hub connection of the kind described above. such that the ball screw nut is the shaft and the inner ring is the hub of the shaft-hub connection.

As a result, with little effort, an axially play-free attachment of the rolling bearing is achieved on the ball screw nut, which is characterized by a high load capacity and a very small influence on the bearing clearance of the bearing. Up to now, this has only been possible to a great extent with conventional solutions. However, such a backlash-free attachment is for the life and performance of an electromechanical steering of great importance, so that a significant progress is achieved by the inventive solution.

The invention will be explained in more detail with reference to an embodiment shown in the drawing. The drawing shows in:

1 a schematic representation of an electromechanical steering with ball screw,

2 a detailed view of the ball screw including storage,

3 a view of the ball screw nut with mounted rolling bearing and mounting ring,

4 Ball screw nut, roller bearing and mounting ring before assembly

5 a detailed view of the mounting ring in the pressed state,

6 a detailed view of the mounting ring before pressing, and in

7 a detailed view illustrating the position of the rolling body raceway.

The invention is in the context of an in 1 schematically illustrated electromechanical vehicle steering 1 without, however, being limited to such.

The steering 1 has a steering gear housing 2 on, through which a handlebar 3 extends. At the handlebar 3 engages a steering pinion 4 to a by the driver at a steering handle 5 applied steering command to the vehicle wheels 6 transferred to. Furthermore, the steering has an electric motor 7 for generating a steering assist torque. The electric motor 7 can, as shown, axially parallel to the handlebar 3 be arranged. However, it is also possible to use the electric motor 7 coaxial with the handlebar 3 or possibly also elsewhere, for example on a steering column.

In the illustrated embodiment, the drive torque of the electric motor 7 via a gear stage 8th and a ball screw 9 as axial force on the handlebar 3 brought to action. The gear stage 8th is here exemplified as a belt drive, wherein a first pulley on an output shaft of the electric motor 7 and a second pulley on a ball screw nut 10 of the ball screw 9 is arranged. About the ball screw 9 becomes a rotary drive torque of the electric motor 7 in a translational motion component on the rack 3 translated to assist the driver in steering.

For controlling the electric motor 7 serves a steering controller 11 , which is a control signal for the electric motor 7 generated and, among other things, taken into account by the driver applied steering torque. This steering torque, for example, with a torque measuring unit 12 on a steering column 13 be measured, which the steering handle 5 mechanically with the handlebar 3 coupled.

2 shows the gear stage 8th and the support of the ball screw 9 within a steering gear housing only partially shown 2 , As already mentioned, the gear stage 8th be executed for example as a belt drive. In the illustrated embodiment, the belt drive comprises a belt 17 , a driving pulley 18 that is fixed to an output shaft 19 of the motor 7 coupled, and a driven pulley 20 firmly with the ball screw nut 10 of the ball screw 9 is coupled.

The ball screw nut 10 , the thread-like ball grooves on its inner circumference 21 training, stands with the handlebar 3 via balls, not shown in threaded engagement and is in the steering gear housing 2 via a rolling bearing 22 rotatably mounted and fixed axially.

The rolling bearing 22 has an inner ring 23 and an outer ring 24 on.

For fixing the outer ring 24 of the rolling bearing 22 serves as an example a Lagerklemmscheibe 25 , which by means of clamping bolts 26 with the steering gear housing 2 is tense. The bearing clamping disc 25 is a simple ring that is punched out of sheet metal, for example. It points for clamping bolts 17 corresponding through holes, which with mounting holes 27 of the steering gear housing 2 correspond. The outer ring 24 of the rolling bearing 22 but it can work too other way in the steering box 2 be determined.

The backlash-free attachment of the inner ring 23 of the rolling bearing 22 on the ball bearing nut made of bearing steel 10 will be explained below on the basis of 3 to 7 will be explained in more detail, which relate to a first embodiment of a shaft-hub connection with high axial load capacity.

In the illustrated embodiment, the ball screw nut 10 the wave 101 and the inner ring 23 of the rolling bearing 22 the hub 102 the shaft-hub connection explained in more detail below.

The wave 101 has a circumferential annular groove 103 on, with a fixing ring 104 is compressed. The fastening ring 104 is thus in the annular groove 103 sets and supports those on the shaft 101 arranged hub 102 axially.

The hub 102 forms at her to the mounting ring 104 pointing end face a flat axial support surface 105 out, extending in the radial direction of the shaft 101 and the hub 102 extends and a flat attachment of the mounting ring 104 allowed. The axial support surface 105 thus closes with the radial direction an angle of 0 °. A conventional standard rolling bearing 22 can without further processing on the inner ring 23 be used.

The ring groove 103 the wave 101 has one of the hub 102 axially opposite first flank 107 on, with an angle of attack α in the range of 5 ° to 50 ° to the radial direction of the hub 102 is arranged. With regard to the support particularly preferred angles are in the range of 15 ° to 35 °. Smaller angles require a relatively large axial length of the groove and the ring in order to achieve a sufficient load capacity. Larger angles are at short axial length with respect to any ring breakage under load, as well as the generation of radial force components at the hub 102 less favorable. The axial length of the undeformed mounting ring 104 is preferably about 15 to 30% of the inner diameter thereof. For ripples in the range of 30 to 50 mm, fixing rings can be used 104 be used with an axial length of about 7 to 11 mm.

The first flank 107 the ring groove 103 goes in the groove base over a curvature 108 into a second flank 109 the ring groove 103 above.

The second flank 109 runs to the seat 106 for the hub 102 on the shaft 101 wherein the Nutauslauf axially spaced in front of the hub 102 ends, ie the seat 106 axially over the hub 102 extends The angle of attack of the second edge 109 to the radial direction is denoted by β and is in the range of 45 ° to 85 ° degrees, preferably in the range of 60 ° to 80 ° degrees. Preferably, the angle of attack β of the second flank 109 the amount greater than the angle of attack α of the first edge 107 ,

The between the support surface 105 the hub 102 and the first edge flanked for this purpose 107 the ring groove 103 pressed-in fixing ring 104 braces the support surface 105 the hub 102 and the first flank 107 the ring groove 103 axially against each other, wherein the deformed mounting ring 104 , as in 5 shown the ring groove 103 completely filled out.

6 shows the still undeformed mounting ring 104 before pressing. This is after pushing the hub 102 on the seat 106 the wave 101 until it stops against the axial abutment shoulder 110 the wave 101 also deferred. Subsequently, a pressing tool P moves axially against one in the region of the annular groove 103 lying edge 111 of the fastening ring 104 , At the edge 111 If appropriate, a chamfer can be provided, wherein wedge angle of 15 to 35 ° with respect to the pushing into the annular groove 103 are particularly advantageous. At the same time, the pressing tool P and the workpiece, namely the components 101 . 102 and 104 , rotated relative to each other. As a result, the fastening ring 104 deformed radially and axially by the contour of the pressing tool P and partially in the annular groove 103 crowded. This results in an axial bias of the mounting ring 104 and thus the axial securing of the hub 102 on the shaft 101 through the positive-locking ring 104 ,

As a result of the compression results at the mounting ring 104 an angled profile cross-section. The fastening ring 104 has a section when installed 112 with a constant inner diameter and an axially adjoining section 113 with tapered inner diameter. There is one with the first flank 107 the annular groove engaging first contact surface 114 at the section 113 arranged with a tapered inner diameter and with the hub 102 engaging second abutment surface 115 at the section 112 is arranged with a constant inner diameter. The first and second contact surface 114 . 115 of the fastening ring 104 include an angle in the range of 5 ° to 50 ° with each other. An angle in the range of 15 ° to 35 ° and particularly preferably in the range of 20 ° to 30 ° is particularly favorable.

For an optimal effect in the axial direction, it is also recommended, the dimensions of the annular groove 103 not only in terms of the angles described above, but also in terms of curvature 108 in the groove bottom and the groove depth T on each other This is also dependent on the shaft diameter. For shaft diameters in the order of 20 to 60 mm is recommended for the curvature 108 in the groove base a radius of curvature R in the range of 0.8 mm to 1.5 mm at a groove depth T of 1.2 to 2.0 mm.

In the illustrated embodiment, the shaft forms 101 a contact shoulder 110 as axial stop for the hub 102 out, so that's the hub 102 in a first axial direction against the abutment shoulder 110 and in an opposite second axial direction against the mounting ring 104 supported. This is the hub 102 between the contact shoulder 110 and the mounting ring 104 held free of play, as by the deformation of the mounting ring 104 during assembly any axial play is canceled.

The force introduction into the hub 102 takes place essentially up to the height of one at the hub 102 trained rolling body career 116 , The support on the contact shoulder 110 takes place below the rolling body raceway 116 , As a result, the axial force flow at the rolling body raceway 116 essentially bypassed, so that the running behavior is not or at most slightly influenced and manageable.

In 7 is the radial distance of the rolling body raceway 116 to the seat 106 the hub 102 on the shaft 101 denoted by h ₀ . The maximum radial height h _{1 of} the second contact surface 115 of the fastening ring 104 over the seat 106 on the shaft 101 component h is ₀ +/- 25%.

Further, the maximum radial height h _{2 of} the contact of the axial abutment shoulder 110 with the hub 102 Component h ₀ +/- 25%.

The fastening ring of the first embodiment forms at its portion 112 with constant inside diameter at its hub 102 pointing end a radially projecting flange 117 from whose front side the second contact surface 115 is. The radial height h ₁ corresponds to the height of the flange 117 , The flange 117 stiffens the fastening ring 104 and prevents it from breaking off. Through the flange 117 Thus, the axial load capacity of the shaft-hub connection is additionally increased.

To the flange 117 closes at the back in the area of the section 112 with constant inside diameter a cylindrical section 118 on, which significantly influences the power flow, since the axial thickness of the flange 117 the radial wall thickness at the cylindrical portion 118 corresponds and accordingly is low. The flange 117 goes in a curve 119 in the outer periphery of the cylindrical portion 118 over, where the radius of curvature of the curvature 119 maximum 1 to 1.5 mm. The radial wall thickness of the cylindrical section 118 , in the 7 H ₃ is designated smaller or at most equal to the seat height h _{0 of} the rolling body raceway 116 , Preferably, h _{3 is} in the range of 35 to 75% of h ₀ . In the illustrated embodiment, h _{3 is} 50 to 60% of h ₀ .

The fastening ring 104 is in the undeformed state, that is before its installation in the annular groove 103 designed as a simple rotationally symmetrical body, which may have an L-shaped or rectangular profile cross-section, but also other profile cross-sectional shapes. When not assembled, the mounting ring points 104 a through hole whose inner diameter to the outer diameter of the shaft 101 in the area of the annular groove 103 is preferably tolerated with a clearance fit. The fastening ring 104 consists of a deformable material, preferably of unhardened steel. It can be produced as a turned part or particularly cost-effective as a stamped and bent part.

The illustrated shaft-hub connection, as shown in the 3 to 7 is shown, not only for fixing an inner ring 23 on a ball screw nut 10 use. Rather, in a corresponding manner, for example, the outer ring 24 of the rolling bearing 22 in the steering gearbox 2 axially fixed or generally a shaft are fixed axially on a provided with an annular groove hub.

The invention has been explained above with reference to an embodiment and further modifications. However, it is not limited thereto, but includes all the embodiments defined by the claims.

LIST OF REFERENCE NUMBERS

1

steering

2

Steering gear housing

3

handlebars

4

steering gear

5

Steering handle

6

vehicle

7

electric motor

8th

gear stage

9

Ball Screw

10

Ball screw nut

11

Steering control unit

12

torque sensor

13

steering column

17

belt

18

driving pulley

19

drive shaft

20

driven pulley

21

Ball tracks

22

roller bearing

23

inner ring

24

outer ring

25

Bearing clamping disc

26

clamping bolt

27

fastening opening

28

Outer peripheral portion

101

wave

102

hub

103

ring groove

104

fixing ring

105

support surface

106

Seat

107

first flank

108

curvature

109

second flank

110

contact shoulder

111

edge

112

Section with axially constant internal diameter

113

Section with axially tapering inner diameter

114

first contact surface

115

second contact surface

116

rolling body

117

flange

118

cylindrical section

119

curvature

h ₀

Height (radial) rolling element raceway 116 over seat 106

h ₁

Max. Height (radial) flange 117 over seat 106

h ₂

Max. Height (radial) contact surface of the abutment shoulder 110 over seat 106

h ₃

Wall thickness of the cylindrical section

P

press tool

α

Angle of attack of the first flank 107 to the radial direction

β

Incident angle of the second flank 109 to the radial direction

Claims (10)

A shaft-hub connection comprising: a first component having an axial abutment shoulder ( 110 ) and a circumferential annular groove ( 103 ), a second component having a rolling body raceway ( 116 ) disposed on the first component and on the axial abutment shoulder ( 103 ) is supported, and a fastening ring ( 104 ), which is connected to a first contact surface ( 114 ) on a flank ( 107 ) of the first component and with a second contact surface ( 115 ) is supported on the second component to the second component with the axial abutment shoulder ( 110 ) of the first component, wherein either the first component is a shaft ( 101 ) and the second component a hub ( 102 ) or the first component is a hub and the second component is a shaft, characterized in that the first and second contact surfaces ( 114 . 115 ) of the fastening ring ( 104 ) enclose an angle in the range of 5 ° to 50 ° with each other, characterized in that the fixing ring ( 104 ), which defines a rolling bearing as a second component on a ball screw nut as a first component, a cylindrical portion ( 118 ), which at a second contact surface ( 115 ) having radial flange ( 117 ), wherein the rolling body track ( 116 ) radially a distance h ₀ to the seat ( 106 ) of the second component to the first component and the wall thickness h _{3 of} the cylindrical portion ( 118 ), less than or equal to h ₀ . Shaft-hub connection according to claim 1, characterized in that the fastening ring ( 104 ) has an angled profile cross-section. Shaft-hub connection according to claim 1 or 2, characterized in that in the event that the first component is a shaft ( 101 ) and the second component a hub ( 102 ), the fastening ring ( 104 ) a section ( 112 ) with a constant inner diameter and an axially adjoining section ( 113 ) having a tapered inner diameter, wherein the flank ( 107 ) of the annular groove ( 103 ) engaging first abutment surface ( 114 ) on the section ( 113 ) is arranged with a tapering inner diameter and with the hub ( 102 ) engaging second abutment surface ( 115 ) on the section ( 112 ) is arranged with a constant inner diameter, and in the case that the first component is a hub and the second component is a shaft, the mounting ring has a portion with constant outer diameter and an axially adjoining portion with increasing outer diameter, wherein the flank the annular groove engaging first abutment surface is disposed on the enlarging outer diameter portion, and the second abutment surface engaging with the shaft is disposed on the constant outer diameter portion. Shaft-hub connection according to one of claims 1 to 3, characterized in that the fastening ring ( 104 ) with the annular groove ( 103 ) is compressed. Shaft-hub connection according to one of claims 1 to 4, characterized in that the second bearing surface ( 115 ) of the fastening ring ( 104 ) lies flat against the second component in a plane. Shaft-hub connection according to one of claims 1 to 5, characterized in that the flank ( 107 ) of the annular groove ( 103 ), which the first contact surface ( 114 ) of the fastening ring ( 104 ) supported, is angled to the radial direction of the first component with an angle of attack in the range of 5 ° to 50 °, and the second component has a support surface ( 105 ) for supporting the second contact surface ( 115 ) of the fastening ring ( 104 ), and this support surface ( 105 ) extends in the radial direction of the first component. Shaft-hub connection according to one of claims 1 to 6, characterized in that the section ( 112 ) with constant inside. or outer diameter at its end pointing to the second component a radially projecting flange ( 117 ), whose end face the second contact surface ( 115 ). Shaft-hub connection according to one of claims 1 to 7, characterized in that the maximum radial height h _{2 of} the contact of the axial abutment shoulder ( 110 ) with the second component h is ₀ +/- 10%. Ball screw nut with rolling bearing, wherein an inner ring ( 23 ) of the rolling bearing ( 22 ) by means of a shaft-hub connection according to one of the preceding claims on an outer peripheral portion ( 28 ) of the ball screw nut ( 10 ), such that the ball screw nut ( 10 ) the wave ( 101 ) and the inner ring ( 23 ) the hub ( 102 ) represents the shaft-hub connection. Electromechanical steering with ball screw ( 9 ) whose ball screw nut ( 10 ) via a rolling bearing ( 22 ) on a steering gear housing ( 2 ) is rotatably mounted and axially fixed, wherein an inner ring ( 23 ) of the rolling bearing ( 22 ) by means of a shaft-hub connection according to one of claims 1 to 8 at an outer peripheral portion ( 28 ) of the ball screw nut ( 10 ), such that the ball screw nut ( 10 ) the wave ( 101 ) and the inner ring ( 23 ) the hub ( 102 ) represents the shaft-hub connection.

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