DE102017206697A1 - Method for producing a torsion bar with a pinion section and torsion bar with pinion section for the steering of a motor vehicle - Google Patents

Abstract

The invention relates to a method for producing a torsion bar (28) for the steering (10) of a motor vehicle having a main body (46) extending over a length L _G and a pinion section (18) arranged non-rotatably thereon, wherein for the formation of the pinion section (FIG. 18) extending over the circumference of the base body (46) extending over at least part of the length L _{G of} the base body (46) extending radially outwardly outstanding pinion base portion (30) having a length L _B on the torsion bar (28) is arranged, wherein for the arrangement of the pinion base portion (30) first at least one separate sleeve (48) is made in the form of a hollow component, the at least one sleeve (48) then pushed onto the base body (46) and relative to is positioned, and then over a length L _R , which corresponds to at least a portion of the length L _B , on the outer periphery (32) of the sleeve (48) has a toothing (34) is formed, wherein by forming the toothing (34) a rotationally fixed connection between the base body (46) and the sleeve (48) is produced.

Description

The invention relates to a method for producing a torsion bar with a pinion portion for the steering of a motor vehicle. Furthermore, the invention relates to a torsion bar with a pinion portion for the steering of a motor vehicle.

Out DE 10 2015 105 284 A1 a method for producing a torsion bar is known, which serves for chassis stabilization. To form Ankoppelabschnitten on the torsion bar this is so converted at its end, in particular upsets that increase the end portions radially. Subsequently, the end regions are converted into Ankoppelabschnitten, in particular by rolling or machining. On a torsion bar with pinion is not referenced.

Out DE 10 2016 214 163 A1 For example, a method of manufacturing a steering shaft portion having a connecting portion is known. The connecting portion should serve to screw a steering wheel to the steering spindle part. The steering shaft is in the form of a hollow shaft with a smooth inner surface. In the hollow shaft, a cylindrical sleeve is used. To make a connection between the hollow shaft and the sleeve they are transformed together. In particular, a mandrel is to be introduced into the sleeve and applied from the outside a forming pressure on the hollow shaft. By reshaping form-fitting elements form on the sleeve and on the hollow shaft, which serve to produce a force acting in the circumferential direction positive engagement. After the common forming a coupling portion, which serves to connect the steering wheel, introduced into the sleeve. On a special training of a pinion is not taken.

Out DE 10 2006 027 745 A1 For example, there is known a method of manufacturing a rotary valve for power steering systems of motor vehicles having a torsion bar called a torsion bar. The torsion bar of this rotary valve is pressed into a rotary rod bore of a separate pinion and is locally deformed for attachment by means of a deformation element such that the pinion and the torsion bar are caulked together to form a rotationally fixed unit.

The invention has for its object to provide a method for producing a torsion bar with a pinion portion and a torsion bar with a pinion portion available, which allow a cost effective and efficient production of a torsion bar with high functional integration and manufacturing accuracy.

The object is achieved according to the invention with the features of the independent claims. Further practical embodiments and advantages of the invention are described in connection with the dependent claims.

The invention relates to a method for producing a torsion bar with a body extending over a length L _G and a rotationally fixed thereto arranged pinion portion for the steering of a motor vehicle. For the formation of the pinion section, a sprocket base section extending over the circumference of the main body and extending over at least part of the length L _{G of} the main body and projecting outwards in the radial direction with a length L _{B is} arranged on the torsion bar. For the arrangement of the pinion base portion, at least one separate sleeve in the form of a hollow component is first produced. The at least one sleeve is then pushed onto the base body and positioned relative thereto. After positioning is then over a length L _R , which corresponds to at least a portion of the length L _B , formed on the outer circumference of the sleeve, a toothing, wherein the formation of the toothing on the outer circumference of the sleeve takes place such that a rotationally fixed connection between the base body and the sleeve is created. The area with the toothing then forms the pinion section. The pinion portion is used in particular for the functional coupling of the torsion bar with a rack portion of a handlebar of a motor vehicle.

With this method according to the invention, a particularly simple and cost-effective production of a torsion bar with a pinion section can take place, in particular insofar as during the formation of the toothing on the outer circumference of the sleeve at the same time a rotationally fixed connection between the sleeve and the base body is achieved. A machining of the sleeve prior to the preparation of the compound or post-processing after the formation of the toothing is not required. The inventive method requires neither the formation of a toothing on a sleeve using an inside support structure, nor is a formation of knurls or teeth for producing a rotationally fixed connection with the body required. By forming the toothing on the outer circumference of the sleeve in its desired position relative to the main body a particularly dimensional, non-positive, rotationally fixed connection between the sleeve and the base body is made because the outer dimension is exactly predetermined by the outside attacking tool. Any manufacturing tolerances with regard to the inner dimension of the sleeve and / or the outer dimension of the basic body, in particular their diameter, so far do not affect the external geometry of the teeth.

According to a further, alternative method according to the invention, for producing a torsion bar with a base body extending over a length L _G and a pinion section formed thereon for the steering of a motor vehicle for the formation of the pinion section, an over the circumference of the body extending over at least one Part of the length L _{G of} the body extending, radially outwardly outstanding pinion base portion having a length L _{B formed} on the torsion bar. Over a length L _R , which corresponds to at least a part of the length L _B , a toothing is formed on the outer circumference of the pinion-base portion. This inventive method for producing a torsion bar with a one-piece design of the base body and the pinion portion facilitates the production of a torsion bar with pinion portion insofar as can be dispensed with the manufacture and connection of two separate elements.

In both of the methods described above, all suitable methods can be considered as the manufacturing method for the formation of the toothing. In this regard, reference is made in particular to turning, milling and pressing.

Both methods described above have in common that a torsion bar with functionally integrated pinion by a relatively small number of operations and at the same time with high manufacturing accuracy can be easily and inexpensively. In both cases, it can be dispensed with a subsequent connection of an element with trained pinion with a body.

In a practical embodiment of the two methods described above, the pinion base portion and / or the toothing are formed by forming. The production by forming has - especially compared to a production by machining - the advantage that no material broke arises.

During cold forming, there is also the advantage that the material is heated only insignificantly during processing. By forming both a pinion base portion can be formed with a relation to a base enlarged external size. Furthermore, a toothing can be formed by forming on a pinion base section, regardless of whether the formation is to take place on an outer circumference of a pinion base section pushed onto the sleeve or on a pinion base section formed integrally on the main body.

In conjunction with the use of a sleeve as the base pinion section forming can be advantageously used to use the externally applied to the outer circumference of the sleeve forming force at the same time for a non-positive connection between the sleeve and body.

Regardless of which process is performed, cold rolling results in production which requires relatively little energy compared to other manufacturing processes. This results in so far a relatively inexpensive production.

As a forming process, in particular for the formation of the toothing or the formation of a pinion base portion, hot rolling is also considered.

In order to enable processing of the torsion bar which is as simple as possible and has a low potential for error, the maximum diameter of the pinion base section or the maximum external dimension of the pinion base section is spaced from the toothing and / or the maximum diameter of the main body or the maximum outside dimension of the Basic body maximum as large as the smallest diameter of the toothing. By the maximum diameter of the pinion base portion spaced from the toothing areas of a pinion base portion are meant, in which no toothing is to be formed. By appropriate training can be ensured that a tool through which a base body is guided centered acts only on those areas that also have a sufficiently large diameter or a sufficiently large external dimensions. This is particularly advantageous if, in the production of a torsion bar, the base body together with the pinion base section is guided during the production in the axial direction by a tool.

Also advantageous in terms of manufacturing technology is when the toothing is formed during or after the production of the pinion base section. Because in this case, the production of a torsion bar according to the invention can be carried out in a maximum of two processing steps.

If the torsion bar is integrally formed, the toothing during the manufacture of the pinion base portion can take place, ie simultaneously during the production of the body with pinion section. By "while" in this case is meant that the torsion bar is made by using a single tool in one operation is, with the tool both the formation of the pinion base portion and the formation of the toothing can be done in one operation.

The inventive method can alternatively be carried out in two steps, regardless of whether the base body and the pinion base portion are integrally formed or by arranging a sleeve relative to a base body. This can be done in particular by the formation of the pinion base portion (in one-piece design) or arrangement of the pinion base portion (when using a sleeve) takes place in a first step and in a second step, the formation of the toothing is performed.

In a practical embodiment of the method for producing a one-piece torsion bar, the formation of the pinion base section takes place on the main body by forming a rod with a constant diameter. Forming is a particularly cost-effective and compared to machining machining material-saving process. The forming can be realized in particular by means of cold rolling. Alternatively, the production of the base body with the pinion base portion formed thereon can also be effected in a casting process.

When a torsion bar is manufactured integrally according to a method according to the invention, it is particularly advantageous if both the formation of the pinion base portion on the base body and the formation of the toothing by means of forming is carried out. Because in this case can be done by using only one forming tool or by the use of two forming tools of the same type manufacturing.

In a further practical embodiment, the pinion base section is arranged or formed completely overlapping with respect to the base body in the longitudinal direction of the torsion bar. In other words, in this case, the pinion base portion extends exclusively between a first end and a second end of the main body.

This has the advantage, in particular in the case of a production by means of a sleeve which is arranged relative to the base body, that the sleeve is completely supported by the base body, so that there is no need for the sleeve during manufacture on the inside by means of other suitable measures to support. The described, completely overlapping arrangement has advantages in particular in connection with the production of a frictional connection by means of forming, since the base body serves in this case as an abutment during the forming process.

1. a) der Grundkörper und der Ritzel-Basisabschnitt einstückig ausgebildet sind oder
2. b) der Grundkörper und der Ritzel-Basisabschnitt kraftschlüssig drehfest miteinander verbunden sind.

The invention also relates to a torsion bar for the steering of a motor vehicle with a base body and a pinion base portion, on whose outer side a pinion portion is formed with a toothing, wherein

1. a) the base body and the pinion base portion are integrally formed or
2. b) the base body and the pinion base portion are non-rotatably connected to each other non-positively.

In this case, torsion bars having the abovementioned features a) are produced, in particular by a method as described above, in particular by means of forming, such as, for example, Cold rolling.

Also, a torsion bar having the above-mentioned features b) is preferably produced by a method as described above, in which the pinion base portion is formed by a sleeve and the connection between the sleeve and the base body takes place through the formation of the toothing, in particular by means of forming , such as Cold rolling.

The torsion bars according to the invention are intended in particular for use in steering gears, in particular in electromechanical steering gears. The torsion bar is usually installed in such a steering gear in a torque measuring unit functionally coupled with an input shaft and torque sensors. A steering or torque introduced by a driver via the input shaft is transmitted in particular via the torsion bar to a steering rod oriented in the vehicle transverse direction. The toothing of the pinion portion cooperates with a corresponding rack portion of the handlebar. About the torsion of the torsion bar, the need for a steering assist or a steering assist torque is determined to be provided by means of a power steering device. As power steering devices often electric motors are used.

Optionally, as viewed in the longitudinal direction of the torsion bar, a taper can also be formed over part of the length of the torsion bar. Such tapers are formed in practice on torsion bars to achieve a desired set torsional stiffness in a particular length of the torsion bar - especially in a region in which a torque measuring unit and / or another measuring unit for detecting rotational movements of the torsion bar surrounding the torsion bar is.

The invention also relates to steering systems for motor vehicles with a torsion bar as described above and to motor vehicles with such steering.

• 1 einen Teil einer Lenkung eines Kraftfahrzeuges in einer Ansicht von vorne,
• 2 einen Teil der Lenkung aus 1 mit einem erfindungsgemäßen Torsionsstab, einer Drehmomentmesseinheit und einer Eingangswelle in einer Schnittdarstellung,
• 3 einen funktional mit dem in 2 übereinstimmenden Torsionsstab in einer Seitenansicht,
• 4 den Torsionsstab aus 3 in einer Schnittdarstellung,
• 5a und 5b eine schematische Darstellung eines erfindungsgemäßen Verfahrens zur Herstellung eines Torsionsstabes gemäß den 3 und 4 und
• 6a und 6b eine schematische Darstellung eines anderen erfindungsgemäßen Verfahrens zur Herstellung eines Torsionsstabes mit einstückig daran ausgebildetem Ritzel.

Further practical embodiments of the invention are described below in conjunction with the drawings. Show it:

• 1 a part of a steering of a motor vehicle in a view from the front,
• 2 a part of the steering 1 with a torsion bar according to the invention, a torque measuring unit and an input shaft in a sectional view,
• 3 a functional with the in 2 matching torsion bar in a side view,
• 4 the torsion bar off 3 in a sectional view,
• 5a and 5b a schematic representation of a method for producing a torsion bar according to the invention according to the 3 and 4 and
• 6a and 6b a schematic representation of another method according to the invention for producing a torsion bar with integrally formed thereon pinion.

In the 1 and 2 are parts of a steering system 10 a motor vehicle, not shown. Such steering 10 are commonly installed in the front of motor vehicles to steering movements of a steering wheel (not shown) via a rotatably connected to the steering wheel input shaft 16 to transfer to steerable wheels. The transmission of the steering movements takes place from the input shaft 16 over a torsion bar 28 (see. 2 ) on a pinion 18 with a toothing 34 (see. 2 ) and from the pinion 18 via a rack section 20 a handlebar 12 , in the 1 is clearly visible and extends substantially in the transverse direction of the motor vehicle, not shown. The handlebar 12 is at its outside ends each functionally connected to the steerable wheels (not shown) of the motor vehicle (not shown).

As in particular in 2 well recognizable are the torsion bar 28 and the input shaft 16 over part of its length from a torque measuring unit 14 surround. As in 2 is recognizable, the torsion bar in a longitudinal section, which also extends over this part, in this embodiment, an (optional) taper, ie a reduction of the outer diameter.

The handlebar 12 includes in the illustrated embodiment in addition to that with the pinion 18 meshing rack section 20 another spindle section 22 , This spindle section 22 is provided in a known manner, by means of a ball screw 24 if necessary, by an electric auxiliary motor 26 to be driven to provide a steering assist power or a steering assist torque. It is so far in the steering shown 10 to an electromechanical steering 10 ,

As in 2 by a sectional view through the input shaft 16 can be seen, the torsion bar extends 28 through the input shaft 16 , which is designed here as a hollow shaft. The torsion bar 28 is in conjunction with the 2-4 embodiments shown formed in two parts. It comprises a basic body 46 and a pinion base portion 30 , It surrounds the input shaft 16 an upper portion of the body 46 of the torsion bar 28 ,

In a lower section of the torsion bar 28 is the main body 46 from a pinion base section 30 surrounded, which on its outer circumference 32 a gearing 34 for engagement in the rack section 20 the handlebar 12 having. The area with the teeth 34 forms the pinion section 18 , At the lower end of the pinion base section 30 is the sprocket base section 30 by means of a ball bearing 36 rotatably mounted, the ball bearing 36 by means of a suitable fixing element 38 is held in a desired position. The input shaft 16 and the torsion bar 28 are also part of a multi-part housing 40 surrounded as a whole by the reference numeral 40 is provided. In the case 40 include torque sensors 42 arranged.

With the help of torque sensors 42 can a by the introduced steering torque on the torsion bar 28 determined torque and the need for the provision of a steering assist power or a steering assist torque are determined, which from the auxiliary motor 26 are to be provided. As in 1 can be seen, is also between the torque measuring unit 14 and the auxiliary engine 26 a connection line 42 intended.

The 3 and 4 show a first embodiment of a torsion bar 28 in detail. This torsion bar 28 Although not exactly in the 1 and 2 torsion bar shown, but it is functionally the same structure and so far functionally identical. It is so far readily possible, the geometry of the in the 1 and 2 to adjust shown torsion bar. It will be in the following on the already in connection with the 1 and 2 described, functionally identical elements.

The torsion bar 28 includes the main body 46 with the length L _G. Over part of the length L _{G of} the body 46 is the sprocket base section 30 on the body 46 arranged. The sprocket base section 30 extends over a length L _B , which in the present case about 45% of the length L _{G of} the body 46 equivalent. The sprocket base section 30 protrudes from the main body 46 in the radial direction. In the in 4 shown embodiment of the torsion bar 28 is the sprocket base section 30 as a separate sleeve 48 trained and encloses the body 46 over the entire circumference. On the outer circumference 32 of the pinion base section 30 is a gearing 34 educated. The area of gearing 34 forms the pinion section 18 which extends over the length L _R , which corresponds to only a part of the length L _B. In the present case, the length L _R corresponds to approximately 20% of the length L _{G of} the main body 46 and about 40% of the length L _B. The gearing 34 is formed in the embodiment shown as a helical toothing.

The minimum diameter of the toothing 34 is in this case as large as or slightly larger than the maximum diameter of the pinion base portion 30 in the areas that are spaced from the gearing 34 are. The diameter of the main body 46 is also recognizable smaller than the smallest diameter of the toothing 34 , This allows a particularly simple machining with a tool, since the torsion bar 28 in this case can be machined only in the relevant areas by axial passage through a tool, if the tool is designed so that it performs machining only in areas with a sufficiently large external dimension.

At the pinion base section 30 is below the pinion section 18 a connection section 52 designed, in particular for the sliding of the ball bearing 36 , At the upper end of the body 46 is another connection section 54 educated. As in 4 is clearly visible, is on this embodiment of the torsion bar 28 a (also optional) taper is formed, which extends from an area below the connection portion 54 extends at the upper end to the lower end of the torsion bar. In this embodiment, it is necessary for manufacturing reasons that one end of the torsion bar is made so that the sleeve 48 on the torsion bar 28 is deferrable. The lower connection section 52 which is opposite to the torsion bar 28 has larger outer dimension, therefore, in the embodiment shown on the pinion base portion 30 educated.

In conjunction with the 5a and 5b as well as the 6a and 6b The following are two different methods for producing a torsion bar 28 explained.

5a and 5b show schematically the production of a first embodiment of a torsion bar 28 , This will be the main body 46 and the pinion base section 30 initially manufactured as separate elements, wherein the pinion base section 30 as a simple sleeve 48 , is made in the form of a hollow cylindrical element. The inner surface and the outer surface of the sleeve 48 are cylindrical with smooth surfaces and have no pre-introduced profiling or the like.

To assemble the sleeve 48 on the main body 46 pushed and aligned with this. The alignment takes place in such a way that the main body 46 and the pinion base section 30 in the form of the sleeve 46 over the entire length L _{B of} the pinion base section 30 overlap. Such an arrangement is in 5b shown. After positioning is in the outer circumference 32 of the pinion base section 30 by means of a forming tool shown schematically 50 a gearing 34 educated. In the forming tool 50 it is a cold rolling tool. By machining with the forming tool 50 becomes simultaneous with the training of the gearing 46 a non-rotatable connection between the sleeve 48 and the body 46 produced. With the help of the forming tool 50 becomes the gearing 32 only over the portion of the length L _R on the outer circumference 32 of the pinion base section 30 formed, which the pinion portion 18 represents.

In the following, the same reference numerals are used to describe a second embodiment of a method according to the invention for identical or at least functionally identical components as for the description of the first embodiment.

6a and 6b show schematically a method for producing a second embodiment of a torsion bar according to the invention 28 , In this second embodiment, the pinion base portion 30 integral to the body 46 educated. The sprocket base section 30 is produced in this embodiment by forming a rod with a constant diameter. The sprocket base section 30 protrudes in the radial direction relative to the base body 46 out. Also in this second embodiment, the pinion base portion extends 30 over about 50% of the length L _{G of} the body 46 , In an in 6b shown second step, the formation of the teeth takes place 34 at the pinion base portion 30 , Training takes place by means of the forming tool shown schematically 50 , here also by means of a cold rolling tool. The pinion section 18 with the teeth 34 is also about a part of the length of the pinion base portion 30 on the outer circumference 32 educated.

The features of the invention disclosed in the present description, in the drawings and in the claims may be essential both individually and in any desired combinations for the realization of the invention in its various embodiments. The invention may be varied within the scope of the claims and in consideration of the knowledge of the person skilled in the art.

In particular, it is again pointed out at this point that even in the 5a . 5b . 6a and 6b schematically shown torsion bars 28 Can have tapers (not shown), in particular in of the respective pinion portion (not shown) and / or pinion base portion 30 spaced lengths.

LIST OF REFERENCE NUMBERS

10

steering

12

handlebars

14

Torque measuring unit

16

input shaft

18

pinion portion

20

Rack section

22

spindle section

24

Ball Screw

26

auxiliary engine

28

torsion bar

30

Pinion base section

32

outer periphery

34

gearing

36

ball-bearing

38

fixing

40

casing

42

torque sensor

44

connecting line

46

body

48

shell

50

forming tool

52

connecting section

54

connecting section

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely 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.

Cited patent literature

• DE 102015105284 A1 [0002]
• DE 102016214163 A1 [0003]
• DE 102006027745 A1 [0004]

Claims (9)

Method for producing a torsion bar (28) for the steering (10) of a motor vehicle having a base body (46) extending over a length L _G and a pinion section (18) arranged thereon in a rotationally fixed manner, in accordance with which for forming the pinion section (18) extending over the circumference of the base body (46) extending over at least part of the length L _{G of} the base body (46) extending radially outwardly outstanding pinion base portion (30) having a length L _B on the torsion bar (28) is arranged, characterized in that for the arrangement of the pinion base portion (30) first at least one separate sleeve (48) is made in the form of a hollow component, the at least one sleeve (48) then pushed onto the base body (46) and relative to is positioned, and then over a length L _R , which corresponds to at least a portion of the length L _B , on the outer periphery (32) of the sleeve (48) a Verz (34) is formed, wherein by forming the toothing (34) a rotationally fixed connection between the base body (46) and the sleeve (48) is produced. Method for producing a torsion bar (28) for the steering (10) of a motor vehicle having a main body (46) extending over a length L _G and a pinion section (18) formed thereon, according to which a pinion section (18) is formed over the circumference of the base body (46) extending over at least a portion of the length L _{G of} the base body (46) extending, radially outwardly outstanding pinion base portion (30) formed with a length L _B on the base body (46) is formed, over a length L _R , which corresponds to at least a portion of the length L _B , a toothing (34) is formed. Method according to one of the preceding claims, characterized in that the pinion base portion (30) and / or the toothing (34) are formed by forming. Method according to one of the preceding claims, characterized in that the maximum diameter of the pinion base portion (30) spaced from the toothing (34) and / or the maximum diameter of the base body (46) is at most as large as the smallest diameter of the toothing ( 34). Method according to one of the preceding claims, characterized in that the toothing (34) is formed during or after the production of the pinion base portion (30). Method according to one of the preceding Claims 2 to 5 , characterized in that the formation of the pinion base portion (30) on the base body (46) takes place by forming a rod with a constant diameter. Method according to one of the preceding claims, characterized in that the pinion base portion (30) relative to the base body (46) in the longitudinal direction of the torsion bar (28) is arranged or formed completely overlapping. Torsion rod for the steering (10) of a motor vehicle having a base body (46) and a pinion base portion (30), on whose outer side (32) a pinion portion (18) with a toothing (34) is formed, characterized in that the base body (46) and the pinion base portion (30) are integrally formed or b) the base body (46) and the pinion base portion (30) are non-rotatably connected to one another in a force-fitting manner. Torsion bar according to the preceding claim, characterized in that - viewed in the longitudinal direction of the torsion bar - spaced from the pinion base portion a taper is formed.

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