DE102018221000A1 - Electromechanical motor vehicle steering and motor vehicle with such a motor vehicle steering - Google Patents

Abstract

Among other things, it is proposed An electromechanical motor vehicle steering system (2), with a steering shaft (3), with a steering pinion (5) which couples the steering shaft (3) with a rack (6), and with one at a free end section (10) of the steering pinion (5) attached worm wheel (11), wherein the steering pinion (5) is rotatably supported at each end via a bearing (17, 18) in the steering housing (4), and wherein a bearing (18) of said bearings (17, 18) arranged on the worm wheel side by means of a Securing element is axially secured and fixed on the steering pinion (5). It is advantageously provided that the securing element is formed by a bearing nut (22), which is screwed onto an external thread section (23, 37) of the free end section (10) of the steering pinion (5) with prestress against the bearing (18) arranged on the worm wheel side.

Description

The invention relates to an electromechanical motor vehicle steering system according to the preamble of patent claim 1 of the invention. According to claim 10 of the invention, the same further relates to a motor vehicle with such motor vehicle steering.

An electromechanical motor vehicle steering system of the generic type is known from a previously unpublished German patent application by the applicant ( DE 10 2017 208 248.8 ) known. This describes an electromechanical motor vehicle steering system with a steering shaft, with a steering pinion mounted in a steering housing, which couples the steering shaft to a rack, with a worm wheel attached to a free end portion of the steering pinion, and with a worm shaft of an electric drive device that is operatively connected to the worm wheel by worm teeth which worm wheel according to a so-called "single-pinion version" is placed directly on the steering pinion of the steering shaft and in which the assist torque is initiated via the same steering pinion, as is the manual steering torque which is initiated via a steering wheel. The steering pinion is rotatably supported at both ends via a bearing in the steering housing. Furthermore, the worm wheel-side bearing of said bearings is axially fixed to the steering pinion by means of a securing element. The securing element is formed by a fastening screw which is screwed into an axial threaded bore of the front end of the free end portion of the steering pinion and thus fixes the worm wheel against the bearing inner ring of said worm wheel side bearing with preload on the steering pinion. This embodiment of an electromechanical motor vehicle steering system requires a certain increased diameter of the free end section of the steering pinion in order to be able to provide the threaded bore for said fastening screw and a sufficiently firm joint connection. This is where the invention described below comes into play.

The object of the invention is to provide an electromechanical motor vehicle steering system which is alternative with respect to the prior art and which, with minimized material and cost expenditure, ensures a secure, high steering performance-transmitting joint assembly of the components of the motor vehicle steering system involved. Furthermore, it is an object of the invention to provide a motor vehicle with such a motor vehicle steering system.

Starting from an electromechanical motor vehicle steering system, with a steering shaft, with a steering pinion mounted in a steering housing, which couples the steering shaft with a toothed rack, and with a worm wheel attached to a free end section of the steering pinion, the steering pinion being rotatably supported at both ends via a bearing in the steering housing , and wherein a worm wheel-side bearing of said bearings is secured and fixed axially on the steering pinion by means of a securing element, the object is achieved in that the securing element is formed by a bearing nut which is preloaded against an externally threaded portion of the free end portion of the steering pinion the bearing on the worm wheel side is screwed.

This measure, while ensuring a secure, high steering performance-transmitting assembly of the components of the motor vehicle steering involved, advantageously enables a particularly slim design of the steering shaft, in particular in the region of the free end section of the steering pinion, which slim design is associated with material and weight savings.

The subclaims describe preferred developments or refinements of the invention.

In order to create a particularly secure joining of the components involved, the bearing nut is axially secured by means of the worm wheel attached to the free end section of the steering pinion. The worm wheel therefore functions as a counter element, so to speak, which secures or counteracts the preloaded bearing nut in its functional position. Any other known non-positive and / or positive lock element, such as an additional lock nut, is advantageously unnecessary, since the safety function is performed by the worm wheel, which is present anyway.

A particularly simple and functionally reliable embodiment of the invention is achieved in that the worm wheel is attached to the free end section of the steering pinion by a form and / or material connection. As a result, a joint can be achieved between the worm wheel and the free end section of the steering pinion, which takes into account the high steering torques acting on the steering shaft and the worm wheel, such as the manual steering torque applied by means of the steering wheel and the support torque applied by means of the electric drive device, when the worm wheel is axially secured.

According to a first advantageous embodiment of the invention, the worm wheel has a hub made of a plastic, preferably a thermoplastic, and the free end section of the steering pinion has a fastening section which corresponds to the hub, the Hub is further preferably rigidly connected by hot embedding with said fastening section. Warm embedding is understood to mean a joining measure in which at least the free end section of the steering pinion is, for example, inductively heated to approximately 160 ° C. and subsequently the worm wheel, which is provided with a cylindrical axial bore in the area of the hub, is pushed onto said free end section, so that the plastic in the contact area with said end section is heated and liquefied and, after cooling to room temperature, with the aid of, for example, an air shower, at least one material bond is established with the end section.

However, the fastening section preferably forms a form-locking contour, such as a toothing formed on the lateral surface, a knurling in the form of a cross or other knurling, one or more grooves running in the circumferential direction, and / or an out-of-round or polygonal cross section, which is advantageous according to this embodiment variant Form and material connection are combined. With regard to the toothing, knurling and grooves, this creates recesses in the fastening section, into which liquefied plastic penetrates through heating and thus ensures a secure hold of the worm wheel at the end section of the steering pinion both in the axial and in the circumferential direction. Likewise, said non-circular or polygonal cross section has an advantageous effect with regard to a secure hold of the worm wheel at the free end section of the steering pinion by positive locking, in particular in the circumferential direction.

According to a second advantageous embodiment of the invention, the worm wheel has a hub made of a metal, preferably made of steel, which is preferably rigidly connected by welding to the free end section of the steering pinion, which is also made of a metal, preferably made of steel. The metallic joining partners make it possible to achieve a particularly firm joining bond between them. Alternatively, the metallic joining partners can also be bonded to one another by adhesive bonding.

In this case, the joining seam (welded or glued seam) is preferably, in terms of process technology, advantageously attached to the free end portion of the steering pinion on the same and the hub. The seam can be ring-shaped or formed by ring sections.

According to a third advantageous embodiment of the invention, the bearing nut is formed in one piece by a hub made of a metal, preferably of a steel, of the worm wheel attached to the free end section of the steering pinion, which is also made of a metal, preferably made of steel. This advantageously minimizes the number of components.

In order to create a particularly firm joint between the hub of the worm wheel forming the bearing nut and the free end section of the steering pinion, the hub is additionally rigidly connected to the free end section by welding or gluing.

According to a preferred embodiment of this third embodiment of the invention, the hub has an internal thread section forming the bearing nut, which corresponds in the assembled state of the worm wheel to an external thread section of the free end section of the steering pinion, a first fitting section of the hub adjoining said internal thread section on the bearing side, which assembled state of the worm wheel contacted on the face side an inner ring of the worm wheel-side bearing and corresponds to a second fitting section of the free end section of the steering pinion. This enables a safe and comfortable mounting of the worm wheel on the steering pinion.

Alternatively, the hub can have a first fitting section, which corresponds in the assembled state of the worm wheel to a second fitting section of the free end section of the steering pinion, an internally threaded section of the hub adjoining the first fitting section of the hub on the bearing side, which in the assembled state of the worm wheel has an inner bearing ring on the end face contacted the worm wheel side bearing and corresponds to an external thread portion of the free end portion of the steering pinion.

However, the invention is not limited to the two embodiments of the third embodiment variant of the invention described above, but also covers an embodiment in which the design of the fitting sections is dispensed with and only said threads are available for biasing the worm wheel against the worm wheel side Screw bearing.

In this case, too, the joining seam (welded or glued seam) is preferably, in terms of process technology, advantageously attached to the free end portion of the steering pinion on the same and the hub. The joining seam can also be ring-shaped or formed by ring sections.

The invention also relates to a motor vehicle with an electromechanical motor vehicle steering system of the type described above.

• 1 äußerst schematisch ein Kraftfahrzeug, welches eine erfindungsgemäß ausgebildete elektromechanische Kraftfahrzeuglenkung aufweist,
• 2 äußerst schematisch eine Einzeldarstellung einer elektromechanischen Kraftfahrzeuglenkung nach dem Stand der Technik in einer Ansicht von Fahrzeug-vorn,
• 3 eine Schnittdarstellung eines erfindungswesentlichen Bereiches der Kraftfahrzeuglenkung nach 2 nach dem Stand der Technik,
• 4 eine teilweise geschnittene Darstellung des erfindungswesentlichen Bereiches der Kraftfahrzeuglenkung nach 2 gemäß einer ersten bevorzugten Ausführungsvariante der Erfindung,
• 5 eine teilweise geschnittene Darstellung des erfindungswesentlichen Bereiches der Kraftfahrzeuglenkung nach 2 gemäß einer zweiten bevorzugten Ausführungsvariante der Erfindung,
• 6 eine äußerst schematische Schnittdarstellung des erfindungswesentlichen Bereiches der Kraftfahrzeuglenkung nach 2 gemäß einer dritten bevorzugten Ausführungsvariante der Erfindung, und
• 7 eine perspektivische Einzeldarstellung einer Nabe eines Schneckenrades der Kraftfahrzeuglenkung nach 6.

The invention is explained in more detail below on the basis of the exemplary embodiments schematically illustrated in the drawings. However, it is not limited to these, but covers all the configurations defined by the claims. For the purposes of the present description, the usual direction of travel of a motor vehicle should be “-x” (“minus x”), the direction opposite to its usual direction of travel with “+ x” (“plus x”), based on the usual direction of travel (-x ) the direction in the horizontal seen perpendicular to the x-direction with "+ y", starting from the usual direction of travel (-x) the direction in the horizontal seen perpendicular to the x-direction with "-y", the direction seen vertically transversely to the x direction with "+ z", and the direction vertically transversely to the x direction seen with "-z". This designation of the spatial directions in Cartesian coordinates corresponds to the coordinate system generally used in the motor vehicle industry. In addition, terms such as "front", "rear", "top""bottom" as well as terms with a similar meaning including the terms "right" and "left" are used in the way they are usually used to indicate the direction on a motor vehicle. Show it:

• 1 extremely schematically a motor vehicle which has an electromechanical motor vehicle steering system designed according to the invention,
• 2nd extremely schematically an individual representation of an electromechanical motor vehicle steering system according to the prior art in a view from the front of the vehicle,
• 3rd a sectional view of an area of the motor vehicle steering essential to the invention 2nd According to the state of the art,
• 4th a partially sectioned representation of the essential area of the motor vehicle steering according to the invention 2nd according to a first preferred embodiment of the invention,
• 5 a partially sectioned representation of the essential area of the motor vehicle steering according to the invention 2nd according to a second preferred embodiment of the invention,
• 6 an extremely schematic sectional view of the area of motor vehicle steering essential to the invention 2nd according to a third preferred embodiment of the invention, and
• 7 an individual perspective view of a hub of a worm wheel of the motor vehicle steering 6 .

1 first shows a motor vehicle 1 , in the present case a passenger car which has an electromechanical motor vehicle steering system shown in the following drawing figures 2nd having. In this respect, the common view shows 2nd and 3rd first an electromechanical motor vehicle steering 2nd According to the state of the art ( DE 10 2017 208 248.8 ). This has a steering shaft 3rd and one in a steering box 4th (see. 3rd ) mounted steering pinion 5 on which the steering shaft 3rd with a rack 6 the motor vehicle steering 2nd couples. In 2nd was for the sake of clarity on the representation of the steering housing 4th waived.

The steering pinion 5 has a toothed section 7 on which with a serration 8th the rack 6 is engaged. In 2nd is also a so-called pressure piece 9 hinted at which the rack 6 against the tooth section 7 the steering pinion 5 presses. At a free end section 10th the steering pinion 5 is a worm wheel 11 attached, which by worm teeth 12 with a helical screw 13 having worm shaft 14 an electric drive device 15 is connected. Said drive device 15 has an electric motor.

In this motor vehicle steering 2nd it is a motor vehicle steering 2nd after a so-called "single-pinion version". Here is the worm wheel 11 directly on the steering pinion 5 the steering shaft 3rd placed. That of the electric drive device 15 Support torque applied is via the same steering pinion 5 into the steering shaft 3rd initiated, as well as the manual steering torque, which is initiated via a steering wheel not shown in the drawing. In the coupling area between the steering shaft 3rd and the steering pinion 5 is a torque measuring device 16 arranged.

The steering pinion 5 is at both ends, namely via a first bearing arranged on the torque measuring device side 17th and a second bearing arranged on the worm wheel side 18th in the steering housing 4th rotatably mounted. The first camp 17th is formed by a needle bearing, whereas the second bearing 18th is formed by a ball bearing.

The second worm wheel side bearing 18th is axially on the steering pinion by means of a securing element 5 secured and fixed. The securing element is through a fastening screw 19th formed which from the end face of the free end portion 10th the steering pinion 5 in an axial threaded hole 20th is screwed in and so the worm wheel 11 against a bearing inner ring 21st of the second bearing arranged on the worm wheel side 18th presses and on the steering pinion 5 specifies.

First embodiment variant of the invention (FIG. 4):

4th shows a first embodiment of a motor vehicle steering system designed according to the invention 2nd , Functionally identical parts are designated with the same reference numerals as in the previous drawing figures, so that reference is also made to the above description of the prior art for their explanation.

This first embodiment variant of the invention differs from the prior art described above in that the securing element is not according to the prior art by said fastening screw 19th , but instead by a camp mother 22 is formed, which on an external thread portion 23 of the end section 10th the steering pinion 5 with tension against one shoulder 24th the steering pinion 5 supporting bearing inner ring 21st of the second bearing arranged on the worm wheel side 18th is screwed. A bearing outer ring 25th of the second camp 18th is supported axially on a shoulder 26 of the steering housing 4th and is by means of an internal thread section 27th the same screwed lock nut 28 axially secured.

To the free end of said end section 10th the steering pinion 5 closes on the external thread section 23 a preferably cylindrical fastening section 29 of the end section 10th for the worm wheel 11 at. The fastening section 29 has a positive locking contour 30th on, for example a recess in the lateral surface of the fastening section 29 form-fitting contour 30th which according to this embodiment by a in the outer surface of the mounting portion 29 introduced toothing is formed. Instead of said toothing, knurling, which is known per se and not shown in the drawing, and or one or more grooves running in the circumferential direction can also be used, for example. In combination with one of the above form-fitting contours 30th or alone, the attachment section 29 of the end section 10th also have a non-circular or polygonal cross section (not shown in the drawing).

The worm wheel 11 has a hub 31 with a cylindrical axial bore 32 on. At least the hub 31 consists of a plastic, preferably a thermoplastic. The hub 31 of the worm wheel 11 is by warm embedding with said mounting section 29 so rigidly connected that the hub 31 of the worm wheel 11 the camp mother 22 contacted. As already explained above, warm embedding is understood to mean a joining measure in which at least the free end section 10th the steering pinion 5 For example, heated inductively to approx. 160 ° C and then the one in the area of the hub 31 with the cylindrical axial bore 32 provided worm wheel 11 on said free end section 10th or its attachment section 29 is pushed axially until the hub 31 on the camp nut 22 axially tight. Through the heated end section 10th the plastic of the hub liquefies 31 at least in the contact area and penetrates into recesses in the form-fitting contour 30th , in the present example as a toothing. After cooling the liquefied plastic to room temperature with the help of, for example, an air shower, it hardens and goes with the fastening section 29 of the end section 10th the steering pinion 5 a positive and material joint connection.

Due to the rigid connection between the steering pinion 5 and worm wheel 11 that acts the camp mother 22 contacting worm wheel 11 or the hub 31 the same advantageous as an axial securing or as a counter element for the bearing nut 22 .

Second embodiment variant of the invention (FIG. 5):

5 shows a second embodiment variant of the invention, wherein functionally identical parts are designated with the same reference numerals as in the previous drawing figures, so that for their explanation reference is also made to the above description of the prior art and to the first embodiment variant of the invention.

In the 5 The second embodiment variant of the invention shown differs from the previously described first embodiment variant in that the worm wheel 11 a hub 31 from a particularly weldable metal, preferably from a steel. Under a hub 31 However, said metal, preferably steel, also becomes a hub 31 understood from a plastic, which has an insert made of said metal, preferably steel, the latter in the assembly of the fastening section 29 of the end section 10th the steering pinion 5 also made of a weldable metal, preferably steel. Said insert is used in the manufacture of the worm wheel 11 including hub 31 after a plastic injection molding process, for example, inserted into the injection mold and subsequently overmolded with plastic (not shown in the drawing).

One with the cylindrical axial bore 32 provided worm wheel 11 is on the free end section 10th or its attachment section 29 , which is designed according to this embodiment as a cylindrical pin, pushed so far with clearance that the hub 31 on the bearing nut screwed with preload 22 axially tight.

A rigid joint between the worm wheel 11 and the mounting section 29 of the end section 10th the steering pinion 5 The worm wheel is made of metal, preferably steel 11 or its metal or steel content (hub 31 made of metal / steel or metal / steel insert) preferably by welding with the fastening section 29 of the free end section 10th connected. How out 5 can be seen further, the joining seam 33 or weld seam advantageous in terms of process technology at the front of the free end section 10th the steering pinion 5 on the same and the hub 31 respectively in the contact area between them. The seam 33 can be ring-shaped or formed by ring sections.

However, the invention is not limited to a cohesive joint connection by welding, but also covers a joint connection by gluing. The seam is also here 33 Technically advantageous on the face of the free end section 10th the steering pinion 5 on the same and the hub 31 respectively in the contact area between the same and can be ring-shaped or formed by ring sections.

Furthermore, it can also be expedient and is accordingly also covered by the invention, the adhesive on the outer surface of the fastening section 29 and / or the corresponding inner lateral surface of the hub 31 to apply. Assign the outer surface of the fastening section 29 and / or the corresponding inner lateral surface of the hub 31 in addition, a form-locking contour, not shown in the drawing, for example knurling forming a depression in the outer or inner lateral surface, said material connection is advantageously supplemented by a form-fitting connection (not shown in the drawing).

Third embodiment variant of the invention (FIGS. 6 and 7):

6 shows a preferred embodiment of a third embodiment of the invention, parts having the same function are designated with the same reference numerals as in the previous drawing figures, so that for their explanation reference is also made to the above description of the prior art and to the first and second embodiments of the invention.

In the 6 shown preferred embodiment of the third embodiment of the invention is based on a worm wheel 11 with a hub 31 from a weldable metal, preferably steel, which now integrally provides the bearing nut provided as a separate component in the embodiment variants described above 22 trains. Under a hub 31 However, a hub made of metal, preferably steel, is also used 31 understood from a plastic, which has an insert made of metal, preferably steel, the latter in the assembly of the end portion 10th the steering pinion 5 made of a weldable metal, preferably steel. Said insert is used in the manufacture of the worm wheel 11 including hub 31 after, for example, a plastic injection molding process, placed in the injection mold and subsequently cast with plastic (not shown in the drawing).

7 shows said hub 31 made of metal, preferably steel in a perspective individual representation. The hub faces on its outer surface 31 Recesses 34 on. The hub 31 is used in the manufacture of the worm wheel 11 after a plastic injection molding process, inserted into the injection mold, not shown in the drawing, and then overmoulded with plastic. The plastic enters said recesses 34 the hub 31 one, so that form and material connection between the hub 31 and the molded and cured plastic is effected.

A free face 35 the hub 31 has a means 36 to the rotary drive by means of a tool, not shown in the drawing. According to this embodiment, said means 35 formed for the rotary drive by blind holes for a key. However, the invention is not limited to this embodiment of the agent 36 to the rotary drive, but captures any other means known per se 36 to the rotary drive. For example, this can also be formed by a polygonal contour, such as a hexagon, for a correspondingly designed wrench (not shown in the drawing).

Again 6 the hub shows 31 Made of metal, preferably steel, the bearing nut 22 forming internal thread section 37 on, in the assembled state of the worm wheel 11 with an external thread section 38 of the free end section 10th the steering pinion 5 made of metal, preferably steel. At the internal thread section 37 the hub 31 a first fit section closes on the bearing side 39 the hub 31 on in the assembled state of the worm wheel 11 the bearing inner ring at the front 21st of the second worm wheel side bearing 18th contacted. The first section of fit 39 the hub 31 corresponds to a second fit section 40 of the free end section 10th the steering pinion 5 . This enables a safe and comfortable mounting of the worm wheel on the steering pinion.

The worm wheel is therefore used during assembly 11 first on the second fit section 39 of the free end section 10th the steering pinion 5 attached and then onto the external thread section 38 of the free end section 10th until the bearing inner ring contacts 21st screwed on, with preload.

A rigid joint between the worm wheel 11 and the end section 10th the steering pinion 5 The hub is subsequently made of metal, preferably steel 31 of the worm wheel 11 preferably by welding with the free end section 10th the steering pinion 5 connected. How out 6 can be seen further, the joining seam 33 or weld seam advantageous in terms of process technology at the front of the free end section 10th the steering pinion 5 on the same and the hub 31 respectively in the contact area between them. The seam 33 can be ring-shaped or formed by ring sections.

However, the invention is not limited to a cohesive joint connection by welding, but also covers a cohesive joint connection by gluing. The seam is also here 33 Technically advantageous on the face of the free end section 10th the steering pinion 5 on the same and the hub 31 respectively in the contact area between the same and can be ring-shaped or formed by ring sections. Alternatively, it can also be provided to apply the adhesive to the outer surface of the free end section 10th the steering pinion 5 and / or the corresponding inner lateral surface of the hub 31 apply (not shown in the drawing).

According to an alternative, not shown in the drawing, to the preferred embodiment of the third embodiment variant of the invention described above, the hub can 31 a first fit section 39 have on which the bearing nut on the bearing side 22 forming internal thread section 37 of the worm wheel 11 connects. In the assembled state of the worm wheel 11 correspond to the first fitting section 39 with a correspondingly arranged second fitting section 40 of the free end section 10th the steering pinion 5 and the internal thread section 37 with a correspondingly arranged external thread section 38 of the free end section 10th the steering pinion 5 . Seen in the axial direction, are therefore the first fitting section 39 and internal thread section 37 as well as the second fit section 40 and male thread section 38 swapped in their order.

As already stated above, the invention is not limited to the two embodiments of the third embodiment variant of the invention described above, but also covers an embodiment in which the design of the fitting sections 39 , 40 is dispensed with and only said thread (internal thread section 37 and male thread section 38 ) are available to the worm wheel 11 with preload against the bearing inner ring 21st of the second bearing arranged on the worm wheel side 18th to screw.

Reference symbol list

1

Motor vehicle

2nd

Motor vehicle steering

3rd

Steering shaft

4th

Steering housing

5

Steering pinion

6

Rack

7

Gear section (steering pinion 5 )

8th

Gearing (rack 6 )

9

Pressure piece

10th

End section (steering pinion 5 )

11

Worm wheel

12

Worm teeth

13

slug

14

Worm shaft

15

Drive device

16

Torque measuring device

17th

first camp

18th

second camp

19th

Mounting screw

20th

Tapped hole

21st

Bearing inner ring

22

Camp mother

23

Male thread section (end section 10th )

24th

Shoulder (steering pinion 5 )

25th

Bearing outer ring

26

Shoulder (steering housing 4th )

27th

Internal thread section (steering housing 4th )

28

Lock nut

29

Fastening section (end section 10th )

30th

Positive locking contour (fastening section 29 )

31

hub

32

Axial bore (hub 31 )

33

Joining seam

34

Recess

35

Face

36

Rotary drive means

37

Internal thread section (hub 31 )

38

Male thread section (end section 10th )

39

first fit section (hub 31 )

40

second fit section (end section 10th )

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102017208248 [0002, 0021]

Claims (10)

Electromechanical motor vehicle steering (2), with a steering shaft (3), with a steering pinion (5) which is mounted in a steering housing (4) and which couples the steering shaft (3) with a toothed rack (6), and with one at a free end section (10 ) of the steering pinion (5) fastened worm wheel (11), the steering pinion (5) being rotatably supported at both ends via a respective bearing (17, 18) in the steering housing (4), and wherein a bearing (18) of said bearings (18) arranged on the worm wheel side 17, 18) is secured and fixed axially on the steering pinion (5) by means of a securing element, characterized in that the securing element is formed by a bearing nut (22) which is attached to an externally threaded portion (23, 37) of the free end portion (10) of the steering pinion (5) is preloaded against the worm wheel-side bearing (18). Motor vehicle steering (2) Claim 1 , characterized in that the bearing nut (22) is axially secured by means of the worm wheel (11) attached to the free end section (10) of the steering pinion (5). Motor vehicle steering (2) Claim 2 , characterized in that the worm wheel (11) is fastened to the free end section (10) of the steering pinion (5) by a form and / or material connection. Motor vehicle steering (2) Claim 3 , characterized in that the worm wheel (11) has a hub (31) made of plastic and the free end section (10) of the steering pinion (5) has a fastening section (29) corresponding to the hub (31), the hub (31) is rigidly connected to said fastening section (29) by hot embedding. Motor vehicle steering (2) Claim 4 , characterized in that the fastening section (29) has a form-fitting contour (30). Motor vehicle steering (2) Claim 3 , characterized in that the worm wheel (11) has a hub (31) made of a metal, which is rigidly connected by welding or gluing to the free end portion (10) of the steering pinion (5) also made of a metal. Motor vehicle steering (2) Claim 1 , characterized in that the bearing nut (22) is formed in one piece by a hub (31) made of a metal of the worm wheel (11) attached to the free end section (10) of the steering pinion (5). Motor vehicle steering (2) Claim 7 , characterized in that the hub (31) of the worm wheel (11) made of metal is additionally rigidly connected by welding or gluing to the free end section (10) of the steering pinion (5) also made of metal. Motor vehicle steering () after Claim 8 , characterized in that - the hub (31) has an internal thread section (37) forming the bearing nut (22), which in the assembled state of the worm wheel (11) has an external thread section (38) of the free end section (10) of the steering pinion (5) corresponds, and that on said bearing side thread section (37) is connected a first fitting section (39) of the hub (31) which, in the assembled state of the worm wheel (11), contacts a bearing inner ring (21) of the worm wheel side bearing (18) on the face side and contacts one corresponds to the second fitting section (40) of the free end section (10) of the steering pinion (5), or that the hub (31) has a first fitting section (38) which, in the assembled state of the worm wheel (11), has a second fitting section (40) of the free end section (10) of the steering pinion (5) corresponds, and that a bearing nut (22) is formed on the bearing side of said first fitting section (38) of the hub (31) Connects to the internal thread section (37) of the hub (31), which in the assembled state of the worm wheel (11) contacts a bearing inner ring (21) of the worm wheel-side bearing (18) and with an external thread section (38) of the free end section (10) of the steering pinion (5 ) corresponds. Motor vehicle (1) with an electromechanical motor vehicle steering system (2) according to one of the preceding claims.

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