DE102013213708A1 - Worm gear for a power steering device of a motor vehicle with clearance compensation - Google Patents

Abstract

The invention relates to a worm gear for a power steering device of a motor vehicle with clearance compensation, the invention has the object to provide a worm gear available that is easy to manufacture and assemble and allows low-noise clearance compensation. A worm gear (10) according to the invention comprises a housing (82) for receiving a worm shaft (18) and a worm gear (14) engaged with the worm shaft (18), the worm shaft (18) being movably mounted in the radial direction. In this case, at least one torsion element (40) on the one hand with respect to the worm shaft (18) and on the other hand set against a housing-fixed component and designed such that the torsion element (40) in its installed position in the housing (82) is claimed in such a torsion that the worm shaft ( 18) is biased in the direction of the worm wheel (14).

Description

The invention relates to a worm gear for a power steering device of a motor vehicle with clearance compensation. In particular, the invention relates to worm gear for steering column-based electric power steering devices (so-called Column type Electric Power Steering Systems, also abbreviated CEPS) and power steering devices with such worm gears.

The required by a arranged in the steering column pinion torques are known to be high and the required speeds low. An electric servomotor arranged in the region of the steering column is therefore usually combined with a transmission mechanism for reducing the rotational speed and for increasing the torque. Due to the high reduction ratio, worm gears with worm shaft and worm wheel are usually used for this purpose. The worm shaft is then often stored coaxially with the shaft of an electric servomotor and rotatably connected to this shaft. The worm shaft can also be designed in one piece with a shaft driven by an electric motor.

The worm gear meshing with the worm is usually rotatably coupled to the steering column of the vehicle to assist the rotary drive of the steering column or the steering pinion. A known disadvantage of the worm gear described is the play between the tooth flanks of the worm shaft and the worm wheel. This game causes the tooth flanks of the worm shaft and the worm wheel, in particular when changing direction, which are associated with a change of the tooth flank side, are not temporarily engaged with each other. The new contacting of the tooth flanks leads to an unwanted noise, which is also referred to as "deflection clinker". Such noises usually occur while driving, in particular when changing direction and correction of direction (tracking). A disadvantage of the described game is further that it is perceived by the driver when driving and the steering is felt in this case as indirect.

Out DE 102 17 123 A1 It is known to reduce the play in a power steering apparatus with worm gear by a spring which applies a restoring force to a floating bearing which guides the worm shaft. The worm and the worm wheel are thus to be kept in contact with each other under different driving conditions. A disadvantage of this design is that there is a metallic contact between the outer ring of the bearing and the spring, which can also generate noise.

In the DE 10 2008 009 107 B4 It is proposed to arrange an elastic damping ring around an outer ring of a guide bearing of the worm shaft and to combine with a specially bent leaf spring to eliminate the play in the worm gear.

Out EP 1 731 404 A1 is a power steering device with worm shaft and worm wheel are known, which are accommodated in a housing. The apparatus comprises a specially designed biasing member having a main portion and a pair of movement limiting portions for biasing the worm shaft in the direction of the worm wheel. The biasing member is disposed in a recess of a support hole formed in the housing.

The solutions described are partly associated with new noise problems, in part require the production of costly, special components and / or are sometimes associated with complex assembly work.

The invention has for its object to provide a worm gear available that is easy to manufacture and assemble and allows low-noise clearance compensation.

The object is achieved according to the invention with the features of claim 1.

A worm gear according to the invention for a power steering device comprises a housing for receiving a worm shaft and a worm gear meshing with the worm shaft, wherein the worm shaft is movably mounted in the radial direction. The worm gear further comprises at least one torsion element which is fixed on the one hand relative to the worm shaft and on the other hand with respect to a housing-fixed component and designed such that the torsion element is claimed in its installed position in the housing to torsion, that the worm shaft is biased in the direction of the worm wheel. A determination of the torsion element with respect to the worm shaft is understood as meaning both securing the torsion element to the worm shaft itself and fastening the torsion element to a component fixedly connected to the worm shaft, in particular a bearing arranged on the worm shaft. The torsion of the torsion element can be generated either by the fact that the torsion element is fixed relative to a housing-fixed component and with respect to the worm shaft and then twisted by relative movement of the worm shaft to the housing-fixed component. Such a relative movement can be generated, for example, that the holes in the Housing for the worm shaft and the worm wheel are arranged relative to each other so that the worm shaft (slightly) is radially deflected due to the position of the worm wheel after final assembly. For this purpose, for example, the center distance of the holes for the worm shaft and the worm wheel can be deliberately reduced.

Alternatively or in addition to the above and described possibility to achieve a torsion of the torsion element in its installed position, the housing-fixed component on which the torsion element is fixed, be designed and arranged so that during the determination of the torsion element (for example, a screw) twisted must be or is inevitably twisted.

For a worm gear according to the invention suitable torsion elements are not only geometrically simple in construction and inexpensive to produce, but can also be easily installed. An inventive worm gear with such a torsion element has the further advantage that a permanent bias is generated due to a torsional movement, wherein the torsional motion is substantially silent. As will be clarified below by means of practical embodiments, one or more torsion elements can also be integrated in a simple manner into a worm gear according to the invention such that noise generation due to relative movements between the torsion element and the adjacent components is virtually eliminated.

An inventive worm gear with the features described above can be realized on worm gears, in which the motor shaft of an electric motor and coaxial with the motor shaft arranged worm shaft are formed in two parts and rotatably connected to each other via a spline. It can also be trained on worm gears, in which the motor shaft is formed integrally with the worm shaft. Details will be discussed in detail in connection with the drawings.

In a practical embodiment of the worm gear according to the invention, the torsion element is fixed relative to the worm shaft on a bearing and / or on the housing side on a bearing plate or the housing itself. The determination of the torsion element relative to the worm shaft on a bearing is particularly suitable for package reasons and installation reasons. In this case, known from the prior art screw shafts can be kept unchanged, so that only the bearing and / or the bearing plate or the housing must be changed for the reconstruction of a known worm gear. Already existing assemblies, in particular a consisting of worm shaft and bearings assembly or a pre-assembled assembly of other elements can be maintained as well as the assembly procedures, because the torsion of a worm gear according to the invention is added only in a relatively late assembly step.

In a further practical embodiment, the bearing and / or the bearing plate and / or the housing have a shoulder and / or a groove for receiving the torsion element. On a paragraph, a torsion element can be pushed in the axial direction on a bearing and then has a one-sided axial stop. The formation of a groove has the advantage that a matched to the geometry of the groove torsion element can be fixed axially in both directions. In the latter case, however, it must be structurally ensured that the torsion element (as simply as possible and without damage to the torsion element) can be introduced into the groove. This can be done, for example, by designing bearings in two parts.

Alternatively, the torsion element may be formed so that it is elastically expandable for mounting on the bearing.

In another practical embodiment, the torsion element comprises an annular body with at least one radially outwardly projecting torsion arm. The torsion element preferably comprises two torsion arms arranged on opposite sides or a plurality of torsion arms, which are particularly preferably distributed uniformly over the circumference. In particular, torsion arms are arranged so that they are twisted in the radial direction when the worm shaft is moved as intended and thus exert a restoring torque on the worm shaft.

The torsion can be fixed on the housing side, for example, by inserting into corresponding recesses of the housing or a bearing plate rotation.

In a particularly preferred embodiment, each Torsionsarm joins at least one Anschraubfläche for screwing with and / or an annular body for fixing to a housing-fixed component, in particular for screwing or fixing to a bearing plate or the housing. If this Anschraubfläche is annular in order to clamped by a screw head to be, has the Anschraubfläche for screwing an ideal shape. The attachment surface can also be referred to as "attachment eye" in this case.

To make a torsion body elastically expandable and yet reliable, the annular body may have two open ends. In particular, the annular body may be formed in the manner of a locking ring with two open ends and an intermediate franking. Under a clearing in this context, an interruption of the annular structure understood that can be increased by pushing apart the open ends, in particular so far that the torsion over another element, in particular a bearing, out and introduced into a groove formed in this element can be. Under an annular body are understood in this context, such elements which consist only of a circular ring segment. Thus, in particular, two annular ring-like annular bodies with open ends can connect to the outside of the torsion arms.

In order to facilitate the pressing apart of the open ends, it is advantageous if an annular body formed on the torsion element in the region of the open ends has at least one recess or a flattening for the attack of a spreading tool or an upsetting tool. In this case, the torsion element can be held in the region of recesses in the assembly by inserting a - in particular pincers - spreading tool and simultaneously expanded and positioned with this spreading tool and positioned. A torsion element with flats can be compressed during assembly by clamping using a compression tool and thus compressed, in particular in order to move it in the axial direction along a worm shaft in a groove formed in the housing or bearing plate can.

In a further practical embodiment of the worm gear according to the invention, the torsion element on the annular body in the region of the torsion arms radially inwardly projecting projections and / or recesses. The formation of such projections and / or recesses causes an advantageous stress distribution in the torsion element during a spreading and / or compression and ensures a high fatigue strength during (torsional) operation. To further improve the stress distribution and the fatigue strength further radial, inwardly projecting projections may be formed on the torsion. These are preferably distributed uniformly over the circumference. The radially inwardly projecting projections abut with their inner sides after insertion of the torsion element in a groove of a bearing on the outer peripheral surface of the groove.

The torsion element can also be fixed only indirectly with respect to the worm shaft and / or with respect to a component fixed to the housing by being fixed in relation to a separate assembly aid and by fixing the assembly aid of the worm shaft and / or with respect to the component fixed to the housing. Such an indirect fixing may have mounting advantages, in particular because the assembly aid is structurally adaptable to the mounting conditions. Thus, for example, another material can be used for the assembly aid and / or dimensional adjustments can be made in order to adapt the torsion element to already existing geometries of other components.

In a particularly practical embodiment, the assembly aid is designed in the manner of a securing ring with two open ends. In this case, the assembly tool can be designed to be particularly elastic, for example, due to its geometry and because of the material used.

The determination of the torsion of the mounting tool can be particularly simple and inexpensive, if at the mounting tool at least one clamping element for fixing the torsion ( 40 ) is provided. As such clamping elements come in particular axially excellent clamping arms with U-shaped profile into consideration.

The determination of the torsion element relative to the worm shaft and / or with respect to a housing-fixed component can be simplified with respect to the assembly process, if on the one hand on the housing-fixed component (in particular housing or end shield) and on the other hand on the torsion element or on the mounting tool corresponding chamfers are formed cause an expansion or compression of the torsion element or the mounting tool during axial assembly movement. In this case, a purely axial movement can be carried out for mounting the torsion element in order to introduce the torsion element, for example, into a groove arranged in a housing-fixed component, since any necessary compression or expansion by the chamfer is effected.

In a further practical embodiment of the worm gear according to the invention, the torsion element is arranged on the outside on a first bearing of the worm shaft and Furthermore, a second bearing for supporting the worm shaft is provided, wherein the second bearing, in particular by the outside arrangement of a (possibly elastic) bearing bush and / or at least one radially outwardly outstanding elastic ring, is designed to be movable in the radial direction. By arranging a plurality of elastic rings with different elasticities and / or by the arrangement of a plurality of elastic rings that protrude different degrees radially outward relative to the outer ring of the bearing, a progression of the spring characteristic for the second bearing can be adjusted.

If the worm shaft is non-rotatably connected via a spline and is coaxially connected to a motor shaft of an electric motor, it is advantageous if the end of the motor shaft in the wedge gear is crowned in the area of the spline, in particular so that the worm shaft is "unrolled" around the end. and thus can be pivoted. The spherical design of the motor shaft is preferably tuned in this case to the radial mobility of the worm shaft. Preferably, by the spherical structure, a pivot angle of less than 5 °, preferably less than 2 ° and more preferably less than 1 °, favors. This is preferably realized in that the respective outermost tangent to the spherical structure has at least the aforementioned angle with respect to the axis of rotation of the worm shaft.

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

1 A first embodiment of a worm gear according to the invention without housing in a perspective view,

2 this in 1 shown worm gear without housing in a view according to the arrow II in 1 .

3 that in the 1 and 2 shown, worm gear according to the invention without a housing in a sectional view according to the designated III in level 1 .

4 an exploded view of the elements of the in 1 - 3 shown, worm gear without housing, according to the invention,

5 the torsion of the in the 1 - 4 shown, worm gear according to the invention in an enlarged view,

6 the in 3 marked with IV area of the in the 1 - 4 shown, worm gear according to the invention in an enlarged view,

7 a preassembled module for in the 1 - 4 shown worm gear according to the invention,

8th an alternative embodiment of a torsion element for a worm gear according to the invention,

9 a further alternative embodiment of a torsion element for a worm gear according to the invention,

10 a further alternative embodiment of a torsion element for a worm gear according to the invention,

11 A second embodiment of a worm gear according to the invention without housing in a sectional view,

12 this in 11 shown worm gear without housing in a partially disassembled state,

13 a further alternative embodiment of a torsion element for a worm gear according to the invention,

14 a further alternative embodiment of a torsion element for a worm gear according to the invention,

15 a further alternative embodiment of a torsion element for a worm gear according to the invention,

16 this in 14 shown torsion element in the mounted state in a housing in an axial sectional view,

17 this in 14 shown torsion element in the mounted state in a housing in a radial sectional view

18 a detailed view of the in 15 shown torsion element in the assembled state in a housing,

19 a further alternative embodiment of a torsion element for a worm gear according to the invention for use with a mounting aid,

20 an assembly aid for use with the in 19 shown torsion element in a perspective front view,

21 this in 20 assembly aids shown in a rear perspective view,

22 a worm shaft with a bearing in the 20 and 21 shown assembly aids and in 19 shown torsion element in a perspective view

23 in the 22 shown worm shaft in a half-sectional view,

24 in the 22 shown worm shaft together with a worm wheel and a housing in a sectional view

25 an enlarged view of the marked XXV area in 24 ,

The 1 to 4 show a first embodiment of a worm gear according to the invention 10 for a power steering device in the area of a steering column 12 is arranged. The steering column 12 is non-rotatable with a worm wheel 14 connected and about a steering column axis 16 rotatably mounted. By a driver of a motor vehicle can use the steering wheel torques directly into the steering column 12 be initiated.

The worm wheel 14 is about the worm gear 10 engaged with a worm shaft 18 , The worm shaft 18 is about a first camp 20 and a second camp 22 around the worm shaft axis 24 rotatably mounted. The first camp 20 is formed in the embodiment shown as a fixed bearing. The second camp 22 is designed as a movable bearing in the embodiment shown.

As in particular in 3 recognizable, is the second camp 22 also part of an assembly assembly group 30 (ZSB floating bearing), which next to the second bearing 22 a bearing bush 26 , a centrally located first elastic ring 28 as well as two right and left of the elastic ring 28 arranged elastic rings 30a . 30b having smaller outer diameter and lesser thickness. The bearing bush 26 itself is formed in the embodiment shown from a relatively rigid material, in particular steel or a hard plastic.

The worm shaft 18 and the worm wheel 14 with steering column 12 are stored in a common housing, not shown. The worm shaft 18 is via a spline 32 (compare in particular 3 and 6 ) rotatably with a motor shaft 34 an electric motor 36 connected. With the help of the electric motor 36 can over the motor shaft 34 and the worm shaft 18 a steering assist torque in the worm wheel 14 and thus in the steering column 12 be initiated.

As in particular in the 2 to 4 is recognizable, is in the outer ring of the first bearing 20 on the outer peripheral surface a groove 38 educated. This groove 38 serves to accommodate a torsion element 40 , this in 5 is shown in detail. The torsion element 40 includes a first radially outwardly projecting torsion arm 42a and a second radially outwardly projecting torsion arm 42b , To the torsion arms 42a . 42b close to the outside a first mounting surface 44a and a second attachment surface 44b on, which are annular. The torsion arms 42a . 42b are over an annular body 46 connected to each other, which is designed in the manner of a securing ring. Accordingly, the annular body 46 , which also as the main body of the torsion element 40 can be designated, a first open end 48a and a second open end 48b with an intermediate franking 50 on. In the area of the open ends 48a . 48b are recesses 52a . 52b formed for the engagement of a spreading tool, not shown.

To the torsion element 40 in the on the outer ring of the first camp 20 trained groove 38 to be able to bring a non-illustrated pliers-like spreading tool in the recesses 52a . 52b introduced to the annular body 46 to hold and elastically expand so that the franking 50 and the diameter of the annular element 46 increase. The torsion element 40 can then - in its widened state - passed over the outer bearing ring and into the groove 38 be used. The groove 38 and the torsion element 40 are coordinated in their dimensions so that the torsion element 40 from the outer ring of the first bearing 20 is recorded essentially free of play.

As in particular in 4 is recognizable and in connection with 7 will be described in more detail, is the torsion element 40 with its screw-on surfaces 44a . 44b opposite a bearing plate 54 of the electric motor 36 established.

6 shows the area of the spline 32 between the motor shaft 34 and the worm wheel 14 , As you can see, this is the end of the motor shaft 34 in the field of splines 32 crowned, that is, it points in the area of the dashed line 56 an area with maximum diameter D _max , the diameter of the dashed line 56 is formed decreasing in both axial directions. Towards the worm shaft 18 the diameter decreases down to the value D ₁ , in the opposite direction the diameter decreases up to the value D ₂ . Due to the spherical shape, the worm shaft 18 opposite the motor shaft 34 by an angle Į YHUVFKZHnkt, which in 6 symbolically (ie not to scale) is entered. The swivel angle Į LVW in the embodiment shown is at most 5 °, preferably at most 2 ° and particularly preferably at most 1 °.

The operation of a worm gear according to the invention 10 is described below in particular with reference to 2 and 3 explained. In a worm gear according to the invention 10 is the torsion element 40 on the one hand over the annular body 46 opposite the first camp 20 and on the other hand on the mounting surfaces 44a . 44b opposite the end shield 54 established.

The center distance A between the steering column axis 16 and the worm shaft axis 24 (see 2 ) is in the illustrated worm gear 10 chosen so that the torsion arms 42a . 42b of the torsion element 40 in its normal position (see dashed line 58 in the 3 and 6 ) and thereby a bias between the worm shaft 18 and the worm wheel 14 produce. To a radial mobility of the second bearing 22 This bearing is in a bearing bush 26 arranged on the outside radially outwardly excellent, elastic rings 28 . 30a . 30b are arranged (see. 2 - 4 ). In the normal position (see dashed line 58 ) is the bushing 26 only with the elastic ring 28 on the housing, not shown. The further the worm shaft 18 from the normal position (dashed line 58 ), the further the elastic ring becomes 28 compressed, in addition to the elastic rings 30a . 30b come into contact with the housing. Once the elastic rings 30a . 30b additionally come into contact with the housing, the force required for a further axial movement of the bearing bush 26 elevated. The maximum deflection of the worm shaft 18 is reached when the elastic rings 28 . 30a . 30b so far compressed that the bushing 26 with the housing (not shown) comes directly and completely to the plant.

7 shows a preassembled assembly assembly with electric motor 36 and worm shaft 18 (ZSB engine worm shaft). In this figure, it is particularly easy to see that the mounting surfaces via screws 60a . 60b at screw domes 62a . 62b are fixed, which on the end plate 54 are formed.

The assembly of a worm gear according to the invention 10 can be carried out in particular as follows:
First, the torsion element 40 on the first camp 20 assembled. Subsequently, the worm shaft 18 in the first camp 20 assembled.

The second camp 22 can on the worm shaft 18 be mounted or in an assembly group ZSB floating bearing together with the bearing bush 26 and the elastic rings 28 . 30a . 30b to be assembled.

In the 7 assembly shown ZSB motor worm shaft includes in particular the worm shaft 18 , the first camp 20 , the torsion element 40 and the engine 36 with bearing plate 54 , The torsion element 40 comes with two screws 60a . 60b to the end shield 54 screwed. The assembly described above can be pretested and has the advantage that the worm shaft 18 with very high accuracy with respect to the motor shaft 34 can be positioned.

Subsequently, the above-mentioned assembly assembly ZSB floating bearing is pre-assembled. For the assembly ZSB floating bearing a housing bore is provided in the housing, to which a suitable game can arise.

When the assembly group ZSB engine together with the attached worm shaft 18 and the assembly group ZSB floating bearings are preassembled in the housing, the steering column 12 (if necessary as assembly group ZSB output shaft).

As already described, by a targeted reduction of the axial distance A between the worm shaft axis 24 and the steering column axis 16 the worm shaft 18 Due to the axial positions during assembly, they are deflected so that the torsion element 40 , as described, is twisted and the worm shaft 18 in the direction of the worm wheel 14 biases. The worm gear according to the invention 10 is designed so that the resulting during assembly bias between worm shaft 18 and worm wheel 14 is maintained at each operating point.

The floating bearing 22 can its position together with the bearing bush 26 due to the resilience of the elastic rings 28 . 30a . 30b vary in the axial direction as described.

It is possible, an eccentric (not shown) in an assembly group ZSB output shaft bearing, ie the part of the steering column 12 , to arrange to vary the center distance A stepless. By such eccentric can the degree of bias of the worm gear according to the invention 10 varies with the help of the torsion and thus adjusted.

An inventive worm gear 10 makes it possible to dispense with the production of eccentric geometries on the worm shaft bearing. The assembly group ZSB motor worm shaft can be mounted and pre-tested. The direct screwing of the assembly group ZSB worm shaft to the electric motor 36 causes between the worm shaft 18 and the motor shaft 34 only a minimal misalignment occurs.

The 8th to 10 . 13 to 19 and 22 to 25 show further embodiments of a torsion element 40 , The 11 and 12 . 16 to 18 and 22 to 25 show further embodiments and details of a worm gear according to the invention 10 , For identical or at least functionally identical elements of the alternative embodiments, the same reference numerals as in FIGS 1 to 7 used.

The in the 8th to 10 shown torsion elements 40 also have an annular body 46 on and are designed in the manner of a retaining ring. In the 8th shown embodiment of the torsion element 40 is different from the one in 5 illustrated embodiment essentially in that on the annular element 46 radially inwardly projecting projections 64 are formed. These projections 64 improve the stress distribution, in particular during the use of a spreading tool and during operation (fatigue strength) of a worm gear according to the invention 10 , Furthermore, at the in 8th shown embodiment additional mounting surfaces 44c . 44d provided so that on each torsion arm 42a . 42b two mounting surfaces each 44a . 44c ; 44b . 44d are connected. As a result, the housing-side fixing of the torsion element 40 be improved.

In the 9 and 10 are other embodiments of torsion elements 40 with annular body 46 shown. These essentially have geometric variations in the area of the screw-on surfaces 44a . 44b . 44c . 44d on.

In the 11 and 12 is a second embodiment of a worm gear according to the invention 10 shown. Unless explained in detail below, the structure essentially corresponds to that in the 1 to 4 shown first embodiment of a worm gear according to the invention 10 , The main difference of the second embodiment of the worm gear according to the invention 10 is that the worm shaft 18 integral with the motor shaft 34 is trained. The torsion element 40 is in this embodiment about screws 60a . 60b set against the housing, not shown.

In the 11 and 12 are also the rotor 66 and the stator 68 of the electric motor 36 shown. As in the 11 and 12 is recognizable, is the rotor 66 stored on the fly, ie the bearings 20 . 22 the motor shaft 34 Both are on the same side of the rotor 66 , The first camp 20 is in the second embodiment of the worm gear according to the invention 10 also designed as a fixed bearing.

In the in the 11 and 12 illustrated second embodiment of a worm gear according to the invention 10 with one-piece "motor worm shaft" 18 . 34 It is advantageous that the rotor 66 is stored flying. Because this makes it possible, the worm shaft 18 first completely with the first camp 20 and the second camp 22 to assemble and the first bearing 20 also with the help of the torsion element 40 relative to the housing (not shown) to fix. Further elements or assembly groups (ZSB) can then be easily retrofitted, which were either embedded warm in the housing (not shown) or preferably with the housing (not shown) were screwed.

The in the 13 to 15 shown torsion elements 40 also have an annular body 46 on and are like a circlip with recesses 52a . 52b and an intermediate franking 50 educated. To the annular body 46 close in the radial direction outward two torsion arms 42a . 42b on, which are arranged opposite to each other. To the torsion arms 42a . 42b close in turn in the radial direction outward two further annular body 70 . 72 on, each only in about a semi-circular ring segment, each with two open ends 74a . 74b correspond.

The in the 13 and 14 shown embodiments have at the open ends 74a . 74b the annular body 70 . 72 recesses 76a . 76b for the engagement of a spreading tool, not shown.

This in 14 shown torsion element 40 shows in comparison to the in 13 shown torsion element 40 in addition to the annular body 70 . 72 above and below the torsion arms 42a . 42b V-shaped recesses 76 on. This facilitates upsetting of the annular body 70 . 72 to be able to lead this through a smaller diameter area.

This is 15 shown torsion element 40 shows in comparison to the in 13 shown torsion element 40 at the open ends 74a . 74b in addition flattenings 78 on, which increase the support surface for a top or bottom flat compression tool and thus facilitate the use of such a compression tool.

The 16 and 17 show the example of in 14 shown torsion element 40 How this can be arranged in the installed state in a worm gear according to the invention. The annular body 46 is in one in the outer ring of a warehouse 20 trained groove 38 established. The annular body 70 . 72 are set in a groove, which in one the bearing 20 surrounding housing 82 is trained.

As in 17 is recognizable, are in the housing 82 in the field of torsion arms 42a . 42b (in 17 is only the torsion arm 42b recognizable) V-shaped recesses 84 formed, which are designed such that one with the help of a in the recesses 74a . 74b engaging compression tool compressed torsion element 40 in the axial direction in the housing 82 is insertable without the annular body 70 . 72 in the field of torsion arms 42a . 42b must be compressed in the radial direction.

In the case 82 is also a chamfer 86 formed during axial assembly movement of the torsion element 40 and impinge the torsion element 40 that causes the annular body 70 . 72 , which with the chamfer 86 come into contact, be compressed in the radial direction. The further movement of the torsion element 40 in the axial direction and the subsequent insertion of the torsion element 40 in the groove 80 is thus supported. As in 18 shown, the annular body can 70 . 72 also - in addition to or independently of the chamfer 86 - with the help of a like in 18 and a functionally designed assembly tool 88 be biased before or thus the annular body 70 . 72 then on the chamfer 86 to meet. In this case, a particularly high holding force can be generated. This in 18 shown assembly tool 88 is only needed for assembly and then removed again.

The 19 to 25 refer to a further embodiment of a worm gear according to the invention 10 , this in 24 with worm shaft 18 , Worm wheel 14 and housing 82 is shown. In this embodiment, the torsion element 40 indirectly via a separate assembly aid 90 in the case 82 established.

19 first shows the torsion element 40 , which are essentially those in 15 shown embodiment (without flattening) corresponds. In the annular bodies 46 . 70 . 72 are areas 92 formed corresponding recesses, which cooperate with the in the 20 and 21 shown assembly aids 90 are provided. The mounting tool 90 is as an annular body in the manner of a locking ring with open ends 94a . 94b and recesses 96a . 96b in the area of the open ends 94a . 94b educated. Evenly distributed over the circumference are on the mounting tool 90 four clamping elements 98 molded, which allow in a simple way, the annular body 70 . 72 opposite the assembly tool 90 to fix and thus fix (cf. 22 and 23 ).

As in particular in 25 is to recognize, is on the assembly tool 90 at a projection 102 a chamfer 100 arranged, whose surface parallel to that in the housing 82 trained bevel 86 is formed and in this respect corresponds with this. The assembly of a "unit" from the in 19 shown torsion element 40 with the in the 20 and 21 shown assembly aids in the housing can be done in a simple manner by simply inserting in the axial direction. Meets the chamfer 100 of assembly tool 90 on the chamfer 86 of the housing and becomes the unit of assembly tool 90 and torsion element 40 moved in the axial direction, the annular element by sliding of the chamfers 86 . 100 upset each other in the radial direction until it reaches the projection 102 pass and in the axial direction up to that in the housing 82 trained groove 80 can be performed. Once the mounting tool 90 - as in the 24 and 25 recognizable - in the groove 80 of the housing 82 is locked, the assembly process is completed. Advantageous to the assembly of the unit from assembly aids 90 and torsion element 40 is that the annular body 70 . 72 of the torsion element 40 do not need to be widened or compressed during assembly.

Generally, the interpretation of, in particular by the torsion element 40 generated bias, in the trade-off between a game reduction and easy steering even in case of failure of the power steering device is.

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 is not limited to the described embodiments. It can be varied within the scope of the claims and taking into account the knowledge of the person skilled in the art.

LIST OF REFERENCE NUMBERS

10

 worm gear

12

 steering column

14

 worm

16

 steering column axis

18

 worm shaft

20

 first camp (fixed camp)

22

 second bearing (floating bearing)

24

 Worm shaft axis

26

 bearing bush

28

 elastic ring

30a, 30b

 elastic ring

32

 splines

34

 motor shaft

36

 electric motor

38

 groove

40

 torsion

42a, 42b

 torsion arm

44a, 44b

 bolting

44c, 44d

 bolting

46

 annular body

48a, 48b

 open end

50

 franking

52a, 52b

 recess

54

 end shield

56

 dashed line

58

 dashed line

60a, 60b

 screw

62a, 62b

 screw bosses

64

 head Start

66

 rotor

68

 stator

70

 annular body

72

 annular body

74a, 74b

 open end

76

 recess

78

 flattening

80

 groove

82

 casing

84

 recess

86

 chamfer

88

 assembly tool

90

 installation equipment

92

 Area with corresponding recesses

94a, 94b

 open end

96a, 96b

 recess

98

 clamping element

100

 chamfer

102

 head Start

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 10217123 A1 [0004]
• DE 102008009107 B4 [0005]
• EP 1731404 A1 [0006]

Claims (14)

Worm gear for a power steering device comprising a housing for receiving a worm shaft ( 18 ) and one with the worm shaft ( 18 ) engaged worm wheel ( 14 ), whereby the worm shaft ( 18 ) is movably mounted in the radial direction, characterized in that at least one torsion element ( 40 ) on the one hand with respect to the worm shaft ( 18 ) and on the other hand fixed relative to a housing-fixed component and designed such that the torsion element ( 40 ) in its installed position in the housing ( 82 ) is subjected to torsion such that the worm shaft ( 18 ) in the direction of the worm wheel ( 14 ) is biased. Worm gear according to the preceding claim, characterized in that the torsion element ( 40 ) opposite the worm shaft ( 18 ) at a warehouse ( 20 ) and / or that the torsion element ( 40 ) on the housing side on a bearing plate ( 54 ) or the housing ( 82 ) is itself set. Worm gear according to the preceding claim, characterized in that the bearing ( 20 ) and / or the bearing plate ( 54 ) and / or the housing ( 82 ) has a shoulder and / or a groove ( 38 ; 80 ) for receiving the torsion element ( 40 ) exhibit. Worm gear according to one or more of the preceding claims, characterized in that the torsion element ( 40 ) an annular body ( 46 ) with at least one radially outstanding torsion arm ( 42a . 42b ). Worm gear according to the preceding claim, characterized in that each torsion arm ( 42a . 42b ) at least one mounting surface ( 44a . 44b ; 44c . 44d ) for screwing with and / or an annular body ( 70 ; 72 ) for fixing to a housing-fixed component connects. Worm gear according to one or more of the preceding claims, characterized in that the annular body ( 46 ; 70 ; 72 ) two open ends ( 48a . 48b ) having. Worm gear according to the preceding claim, characterized in that the annular body ( 46 ; 70 ; 72 ) in the region of the open ends ( 48a . 48b ; 74a . 74b ) Recesses ( 52a . 52b ; 76a . 76b ) and / or flats ( 78 ) are designed for the attack of a spreading tool or upsetting tool. Worm gear according to one or more of the preceding claims, characterized in that the torsion element ( 40 ) on the annular body ( 46 . 70 . 72 ) in the region of the torsion arms ( 42a . 42b ) radially inwardly projecting projections ( 64 ) and / or recesses ( 76 ) having. Worm gear according to one or more of the preceding claims, characterized in that the torsion element ( 40 ) compared to a separate assembly aid ( 90 ) and the mounting aid ( 90 ) opposite the worm shaft ( 18 ) or fixed to a housing-fixed component. Worm gear according to the preceding claim, characterized in that the assembly aid ( 90 ) in the manner of a locking ring with two open ends ( 94a . 94b ) is trained. Worm gear according to one of the two preceding claims, characterized in that on the assembly aid ( 90 ) at least one clamping element ( 98 ) for fixing the torsion element ( 40 ) is provided. Worm gear according to one or more of the preceding claims, characterized in that on the one hand on the housing ( 82 ) or end shield and on the other hand on the torsion element ( 40 ) or the assembly aid ( 90 ) corresponding chamfers ( 86 . 100 ) are formed, which in axial assembly movement of the torsion ( 40 ) or the assembly aid ( 90 ) an expansion or compression of the torsion element ( 40 ) or the assembly aid ( 90 ) cause. Worm gear according to one or more of the preceding claims, characterized in that the torsion element ( 40 ) on the outside at a first bearing ( 20 ) of the worm shaft ( 18 ) and also a second bearing ( 22 ) for supporting the worm shaft ( 18 ), the second bearing ( 22 ) is arranged to be movable in the radial direction. Worm gear according to one or more of the preceding claims, characterized in that the worm shaft ( 18 ) via a spline ( 32 ) rotatably and coaxially with a motor shaft ( 34 ), the end of the motor shaft ( 34 ) in the region of the spline ( 32 ) is formed spherical.

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