DE102022117594A1 - Steering gear unit - Google Patents

Abstract

The invention relates to a steering gear unit (1) for a motor vehicle, having a shaft arrangement (2) which has an axially extending pinion shaft (3) which leads distally to a gear housing (10) and at least one which is connected in a rotationally fixed manner to the pinion shaft (3). Extension element (4) extending partially proximal to the pinion shaft (3), and with a sleeve element (11) which is connected to the gear housing (10) and surrounds the pinion shaft (3) with a tube section (11.1) at a radial distance, so that between one A tangentially circumferential first gap (6) is formed between the proximal tube end (11.2) of the tube section (11.1) and the pinion shaft (3). In order to protect a steering gear more effectively from moisture, the invention provides that a protective element (8) is connected to the shaft arrangement (2) proximally of the tube section (11.1) and has a tangentially circumferential sleeve section (8.3) which is positioned with respect to the axial direction (A) extends distally beyond the pipe end (11.2) and partially surrounds the pipe section (11.1) on the radial outside, the protective element (8) being spaced from the sleeve element (11) by a second gap (7).

Description

The invention relates to a steering gear unit with the features of the preamble of claim 1.

Rack and pinion steering is normally used in steering gears of motor vehicles, especially cars. A pinion shaft, which is rotated by the steering wheel, interacts with a rack, which in turn acts on the tie rods. The pinion shaft is normally mechanically coupled to a steering wheel and connected to its steering shaft in a torque-transmitting manner, for example via a cardan joint. However, a mechanical decoupling is also conceivable, so that the pinion shaft is moved via an actuator in accordance with a steer-by-wire and has no mechanical connection to the steering wheel. In the case of a power steering system, one or more torque sensors are provided which detect a torque applied by the steering wheel, which can then be amplified by an actuator. In any case, the pinion shaft runs into a steering gear housing, in which the rack is also arranged. Near the housing, the pinion shaft is often surrounded by a type of plastic sleeve or tube, which is intended to prevent dirt and moisture from entering the housing. However, it has been shown that despite this protection, damage caused by moisture occurs. This particularly applies to the failure of torque sensors in the area of the pinion shaft.

The DE 38 01 846 C2 discloses a motor-driven power steering device having a steering force transmission mechanism for transmitting a manually applied steering force applied to a steering wheel to a steerable vehicle wheel. The steering force transmission mechanism has a pinion shaft which cooperates with a rack. The pinion shaft is guided into a gear housing in which the rack is accommodated. A sealing part is inserted between the gearbox housing and the pinion shaft. The sealing part and an upper end of the gearbox housing are covered by a dust protection cap placed over the pinion shaft.

The DE 10 2018 107 863 A1 shows a sealing arrangement for an input shaft of a steering gear, with a first element and a second element. The first element defines a first central passage and the second element defines a second central passage, both extending along a central axis and through which an input shaft of a steering gear extends. The second element is attached to the input shaft and is rotatable with the input shaft about the central axis with respect to the first element. An external seal is arranged between the first element and the second element. An inner seal is supported by and movable with the second element.

In view of the state of the art shown, the moisture protection of a steering gear still offers room for improvement.

The invention is based on the object of protecting a steering gear more effectively from moisture.

According to the invention, the object is achieved by a steering gear unit with the features of claim 1, the subclaims relating to an advantageous embodiment of the invention.

It should be noted that the features and measures listed individually in the following description can be combined with one another in any technically sensible manner and show further refinements of the invention. The description additionally characterizes and specifies the invention, particularly in connection with the figures.

The invention shows a steering gear unit for a motor vehicle. The motor vehicle can be, for example, a car or a truck. The steering gear unit is assigned to a steering gear, although not all components of the steering gear unit actually have to be gear parts.

The steering gear unit has a shaft arrangement which has an axially extending pinion shaft leading distally to a gear housing and an extension element which is non-rotatably connected to the pinion shaft and extends at least partially proximal to the pinion shaft. The axial direction is defined by the direction of travel of the pinion shaft and normally corresponds to an axis of symmetry of the pinion shaft. The pinion shaft leads to a gear housing, which is arranged distally. That is, the end of the pinion shaft that is arranged towards the gearbox housing is the distal end, while the opposite end is the proximal end. As a rule, the distal end is a lower end and the proximal end is an upper end. Normally the pinion shaft leads into the gearbox housing and is rotatably mounted on it. In the gearbox housing, the pinion shaft can interact via a pinion with a rack, which is slidably mounted within the gearbox housing. When assembled, the pinion shaft can be indirectly connected to a steering wheel. In addition to the pinion shaft, the shaft arrangement has an extension element, which is also called a shaft extension, pinion shaft ver Lengthening or lengthening of the pinion shaft can be referred to. This is connected to the pinion shaft in a rotationally fixed manner. It extends at least partially proximal to the pinion shaft, ie it forms an extension of the pinion shaft in the proximal direction. The extension element can in particular be designed at least partially symmetrical to the axial direction. Although the extension member extends partially proximal to the pinion shaft, it may overlap with the pinion shaft in the axial direction.

The steering gear unit also has a sleeve element which is connected to the gear housing and surrounds the pinion shaft with a tube section at a radial distance, so that a tangentially circumferential first gap is formed between a proximal tube end of the tube section and the pinion shaft. The function of the sleeve element is to prevent dirt and moisture from penetrating between the gearbox housing and the pinion shaft. For this purpose, it is connected to the gearbox housing, whereby the connection can be at least splash-proof. Furthermore, a tube section of the sleeve element surrounds the pinion shaft, i.e. the tube section extends in a tangential direction around the pinion shaft. There is a radial distance between the pipe section and the pinion shaft. Typically, the tube section is cylindrical with a circular cross section and extends parallel to the axial direction. In this case, its inner radius is chosen to be larger than an outer radius (or more generally, a radial outer dimension) of the pinion shaft. In any case, the radial spacing ensures that no friction occurs between the pinion shaft and the pipe section. However, this also results in a tangentially circumferential first gap being formed between a proximally arranged tube end (usually the upper tube end) and the pinion shaft. The first gap can also be described as ring-shaped. It could be a potential weak point in terms of protection against dirt and moisture.

Therefore, it is provided according to the invention that a protective element is connected to the shaft arrangement proximally of the pipe section and has a tangentially circumferential sleeve section which extends distally beyond the pipe end with respect to the axial direction and partially surrounds the pipe section radially on the outside, the protective element being protected by a second Space is spaced from the cuff element. The protective element is connected to the shaft arrangement, for example to the pinion shaft and/or to the extension element, and could also be viewed as part of the shaft arrangement. It is normally connected in a rotationally fixed manner so that it rotates synchronously with the shaft arrangement. The protective element is also normally fixed axially with respect to the shaft arrangement. In particular, it can be fixed relative to the shaft arrangement both in the tangential direction and in the axial direction. In contrast to the pinion shaft and the extension element, which have to transmit considerable mechanical forces and are therefore usually made of a stable material such as steel, the protective element can be made in a weight-optimized manner from a lighter, although less stable, material such as plastic. The connection is provided proximal to the pipe section and therefore also proximal to the pipe end. The sleeve section is essential for the function of the protective element. This is designed to be tangentially circumferential. It extends distally beyond the end of the tube with respect to the axial direction. I.e. it is arranged partially proximally and partially distally of the pipe end with respect to the axial direction, whereby it partially surrounds the pipe section on the radial outside. The sleeve section therefore shields a part of the pipe section near the pipe end from the outside and it also forms a shield in the transition region between the pipe section and the part of the pinion shaft that is not surrounded by the pipe section. There is therefore an overlap in the axial direction between the external sleeve section extending in the distal direction and the internal tube section extending in the proximal direction.

The protective element is spaced from the cuff element by a second gap. The protective element is thus held without contact with the cuff element. The two elements are separated by the second space, which also applies in particular to the sleeve section and the tube section. During operation, the protective element can rotate together with the shaft assembly without causing friction on the pipe section. The second gap is tangentially circumferential and can in particular be annular.

The function of the protective element is to shield the first gap from the outside as much as possible. However, this does not create a liquid-tight connection in the true sense, but rather the protective element and the sleeve element act together in the manner of a labyrinth seal. This has proven to be sufficient and the fact that the protective element has no contact with the tubular element eliminates solid friction, which could otherwise lead to wear and a loss of sealing effect. In general, there are friction losses between the protective element and the cuff element avoided. The same applies to any noticeable noises that may occur upon contact. In addition, the absence of an elastomeric sealing element between the tubular element and the sleeve element saves material and simplifies the assembly of the steering gear unit. The protective element can be made inexpensively from plastic and can have a low mass so that it does not influence the driver's steering feel. The normally given fixation in the axial and/or tangential direction of the protective element relative to the shaft arrangement prevents the protective element from slipping and possibly coming into contact with the sleeve element or other fixed parts.

Although embodiments are conceivable in which the protective element consists of several separately manufactured parts, it is preferred that the protective element is formed in one piece. In particular, the protective element can be produced by primary molding, for example by injection molding. If necessary, the original forming can also be supplemented by other processes, such as machining.

According to one embodiment, the protective element has a connecting section which rests on the shaft arrangement and a collar section which extends radially outwards from this and to which the sleeve section is at least indirectly connected. The connecting section can preferably be designed to be tangentially circumferential and to rest circumferentially on the shaft arrangement. In particular, it can form a liquid-tight or at least splash-proof seal with the shaft arrangement. For example, the connecting section can be cylindrical or cylindrical. Normally, the radial outer dimension of the connecting section does not change or changes only insignificantly along the axial direction. In contrast, the collar section extends radially outwards. It can, for example, run perpendicular to the axial direction in the manner of an annular disk, but it could also have the shape of a cone shell, which widens radially along the axial direction. The sleeve section can connect directly to the collar section. Because the collar section extends radially outwards, the necessary radial distance is obtained, which is necessary in order to arrange the sleeve section radially on the outside of the pipe section. Alternatively, the sleeve section can also be connected indirectly to the collar section, i.e. via at least one additional intermediate section.

The protective element advantageously forms a positive connection with the shaft arrangement in the tangential direction. The tangential positive connection is preferably complete - i.e. free of play - so that this ensures that the protective element cannot be rotated relative to the shaft arrangement. The positive connection can be provided directly with the pinion shaft and/or the extension element, but it could also be provided with a further element of the shaft arrangement, which in turn is connected to the pinion shaft and/or the extension element. In addition, the positive connection could be provided indirectly via another element that cannot be clearly assigned to the shaft arrangement. Alternatively or in particular in addition to a tangential positive connection, a frictional connection and/or material connection can be provided, which prevents or at least makes it more difficult for the protective element to be displaced relative to the shaft arrangement in the tangential direction.

Furthermore, it is preferred that the protective element forms a positive connection with the shaft arrangement in the axial direction. This in turn is preferably complete and therefore free of play. In this case too, the positive connection can be provided directly with the pinion shaft and/or the extension element, with another element of the shaft arrangement, or it could be provided indirectly via a further element that cannot be assigned to the shaft arrangement. Alternatively or in particular in addition to an axial positive connection, a frictional connection and/or a material connection can be provided, which prevents or at least makes it more difficult for the protective element to move relative to the shaft arrangement in the axial direction. In particular, both tangential and axial positive connection is advantageously provided, through which the protective element is fixed relative to the shaft arrangement.

According to one embodiment, the shaft arrangement has a bolt element which extends at an angle to the axial direction, through which the extension element is connected to the pinion shaft in a rotationally secure manner, the protective element having a holding section which engages in a form-fitting manner with the bolt element. The bolt element can in particular run at right angles to the axial direction. Typically it forms a positive connection with both the extension element and the pinion shaft. Normally the bolt element has a shaft and a head connected to it at the end. The shaft is usually provided with an external thread, so that the bolt element can also be referred to as a screw element or screw, although the term “bolt element” also includes threadless embodiments. The pinion shaft can have a recess, groove or groove in which the bolt element is partially arranged. Furthermore, the extension element can have two through openings through which the bolt element is passed. One of the through openings can have an internal thread that is screwed to the external thread of the bolt element. In the embodiment described here, the protective element has a holding section, which can also be referred to as a retaining section. This engages positively with the bolt element, ie it forms a positive fit with the bolt element. The positive connection can be provided in particular in the axial direction, so that an axial position of the protective element relative to the bolt element and thus relative to the shaft arrangement is secured. Alternatively or additionally, a tangential positive connection can be provided.

An advantageous embodiment provides that the holding section surrounds the bolt element in an arc and forms an axial positive connection with it. In this case, the holding section can be designed like a hook. It approaches the bolt element axially from one side, e.g. the distal side, is guided around it, e.g. radially on the outside, and engages behind the bolt element on the axially other side, e.g. the proximal side. In this way, an axial positive connection is achieved, which can in particular be formed axially on both sides. Furthermore, the holding section can form a radial positive connection with the bolt element.

The extension element often surrounds the pinion shaft in sections, although it is also possible for it to additionally clamp it in a force-fitting manner. In order to realize this, the extension element can have an expansion slot, which makes it possible to pull together a section of the extension element, for example by a thread-bearing bolt element, in order to produce the required clamping effect. One embodiment provides that the extension element has an axial expansion slot in which the holding section is at least partially arranged. Accordingly, the holding section is at least partially dimensioned so that it can be arranged in the expansion slot. This creates a positive connection between the holding section and the extension element, which in turn creates a rotation-proof connection between the protective element and the shaft arrangement. During assembly, the protective element can first be pushed onto the pinion shaft before the extension element is mounted in such a way that it receives the holding section in its expansion slot. In many cases, the extension element must be arranged in a specific orientation with respect to the pinion shaft, which must then be taken into account when positioning the protective element.

Particularly in the case of a holding section designed to save material, a secure connection of the same to other areas of the protective element can be important. According to one embodiment, the holding section is connected radially on the inside to the connecting section and distally to the collar section. There is therefore a double and to a certain extent redundant connection of the holding section to the rest of the protective element, namely on the one hand with the connecting section and on the other hand with the collar section. Not only can the holding section be stabilized in this way, but the three sections can mutually stabilize each other. The holding section can in particular be at least partially rib-like or wall-like, for example in order to engage in an expansion slot of the extension element as described above.

When assembled, the protective element is designed to run all the way around in a tangential direction. If the protective element is manufactured in one piece, it is possible, on the one hand, to produce it closed in a ring-like manner, for example by primary molding. Another possibility is that the protective element has two sections connected by a film hinge, which rest against each other in a contact area that is continuous in the axial direction. The two sections can also be made in one piece by primary molding, with the film hinge also being made in one piece with this. The film hinge forms a pivot axis about which the two sections, which can, for example, form mutually symmetrical halves of the protective element, can be pivoted against each other and folded together. When folded, the two sections then enclose parts of the pipe section and the shaft arrangement. In the contact area, which passes through in the axial direction, but normally does not run parallel to the axial direction, the sections lie against one another.

One embodiment provides that the connecting section is connected to the extension element and the collar section is adjoined by a capsule section which, radially on the outside, surrounds a connection area in which the pinion shaft is connected to the extension element and to which the sleeve section adjoins. That is, in this case, the protective element extends with respect to the axial direction partly at the level of the extension element to which the connecting portion is connected and partly at the level of the pinion shaft. The connection area in which the pinion shaft and extension Rung element are connected, can in particular have the above-mentioned expansion slot and / or the bolt element. This area normally has a larger radial dimension compared to the proximal and distal areas of the shaft arrangement. Accordingly, the capsule section that surrounds the connection area can also represent the section of the protective element with the greatest radial extent.

The capsule section adjoins the collar section, although depending on the embodiment, a clear demarcation between the capsule section and the collar section may not be possible. The sleeve section adjoins the capsule section distally. This can be tapered radially compared to the capsule section. Whether this is the case depends, among other things, on the radial extent of the connection area compared to that of the pipe section. In order to establish a rotation-proof connection with the shaft arrangement in this embodiment, there are different options. For example, the connecting section can be connected to the extension element in a rotationally fixed manner. Alternatively or additionally, the capsule section can also engage, for example, in a form-fitting manner with the connection area. For example, the capsule section can have at least one bulge in which one end of the bolt element is received in a form-fitting manner. In the embodiment described here, the protective element can normally only be mounted after the extension element has been connected to the pinion shaft. This in turn normally makes it impossible to slide the protective element onto the extension element in the axial direction. This applies in particular when both the connecting section and the sleeve section are radially tapered relative to the capsule section. This embodiment can be combined, for example, with the above-mentioned embodiment, in which the protective element has two sections.

• 1 eine erste Schnittdarstellung einer erfindungsgemäßen Lenkgetriebeeinheit gemäß einer ersten Ausführungsform;
• 2 eine zweite Schnittdarstellung der Lenkgetriebeeinheit aus 1;
• 3 eine perspektivische Darstellung der Lenkgetriebeeinheit aus 1;
• 4 eine perspektivische Darstellung eines Schutzelements der Lenkgetriebeeinheit aus 1;
• 5 eine perspektivische Darstellung einer erfindungsgemäßen Lenkgetriebeeinheit gemäß einer zweiten Ausführungsform; sowie
• 6 eine perspektivische Darstellung eines Schutzelements der Lenkgetriebeeinheit aus 5.

Further advantageous details and effects of the invention are explained in more detail below using different exemplary embodiments shown in the figures. It shows

• 1 a first sectional view of a steering gear unit according to the invention according to a first embodiment;
• 2 a second sectional view of the steering gear unit 1 ;
• 3 a perspective view of the steering gear unit 1 ;
• 4 a perspective view of a protective element of the steering gear unit 1 ;
• 5 a perspective view of a steering gear unit according to the invention according to a second embodiment; as well as
• 6 a perspective view of a protective element of the steering gear unit 5 .

In the different figures, the same parts are always provided with the same reference numbers, which is why they are usually only described once.

1 - 3 show a first embodiment of a steering gear unit 1 according to the invention for a car, which is part of a steering gear. The steering gear unit 1 comprises a shaft arrangement 2 with a pinion shaft 3 and an extension element 4. The shaft arrangement runs along an axial direction A, to which the pinion shaft 3 is predominantly rotationally symmetrical. Towards a distal side D, the pinion shaft 3 runs into a gear housing 10, which is only partially shown here. In the transmission housing, the pinion shaft 3 interacts via a pinion with a rack (both not shown). As can be seen from the synopsis of 1 and 3 can be seen, the pinion shaft 3 is connected to the extension element 4 in a connection area 9, being inserted into a connecting section 4.1 of the latter. The extension element 4 extends relative to the pinion shaft 3 to a proximal side P. A bolt element 5, which is designed here as a screw, runs perpendicular to the axial direction A through the extension element 4 and is screwed to it. The bolt element 5 partially engages in a one-sided groove 3.1 of the pinion shaft 3 and thus forms a positive connection with the pinion shaft 3, both in the axial direction A and in the tangential direction. In addition, the extension element 4 has an axial expansion slot 4.2, so that the connecting section 4.1 is contracted and clamps the pinion shaft 3 when the bolt element 5 is tightened.

A sleeve element 11 is connected to the gear housing 10, the connection being at least splash-proof. The sleeve element 11 extends with a tube section 11.1 proximal to a tube end 11.2. The pipe section 11.1 surrounds the pinion shaft 3 at a radial distance, so that a first gap 6 is formed between the pinion shaft 3 and the pipe end 11.2. In order to prevent dirt and moisture from entering the first gap 6, the steering gear unit 1 has a protective element 8, which is in 4 shown in isolation. It is connected to the pinion shaft 3 proximally of the pipe section 11.1, with an approximately cylindrical connecting section 8.1 on the pinion wave 3 is present. Distally, there is a collar section 8.2 which extends radially outwards. This is in turn adjoined by a sleeve section 8.3, which extends distally beyond the pipe end 11.2 and partially surrounds the pipe section 11.1 on the outside. A second gap 7 is formed between the cuff element 11 and the protective element 8 so that they are kept contact-free. This means there is no friction and no wear. However, the protective element 8 together with the pipe section 11.1 forms a labyrinth seal, which provides effective protection against penetrating moisture.

There is a frictional connection between the connecting section 8.1 and the pinion shaft 3, which prevents any displacement of the protective element 8 relative to the pinion shaft 3. In order to achieve improved protection via a positive connection, the protective element 8 has a holding section 8.4, which is designed like a rib overall and which is connected radially on the inside to the connecting section 8.1 and distally to the collar section 8.2. It engages in a form-fitting manner with the bolt element 5, whereby it encompasses the bolt element 5 in an arc. In this way it forms an axial positive connection with the bolt element 5. The slim, rib-like shape of the holding section 8.4 also allows it to be partially arranged in the expansion slot 4.2, so that there is also a tangential positive connection with the extension element 4 and thus with the shaft arrangement 2 as a whole.

When assembling the gear unit 1, the sleeve element 11 with the pipe section 11.1 is first pushed over the pinion shaft 3 and connected to the gear housing 10, so that the in 2 shown condition results. The protective element 8 is then pushed onto the pinion shaft 3 from the proximal side P, with the holding section 8.4 being aligned tangentially on the groove 3.1. The extension element with the connecting section 4.1 is then pushed over the pinion shaft 3, with the holding section 8.4 being received in the expansion slot 4.2. Finally, the bolt element 5 is screwed in.

5 and 6 show a second embodiment of a steering gear unit 1 according to the invention, which is largely identical to the first embodiment and only differs with regard to the protective element 8. In this case, the protective element 8 is connected to the extension element 4 proximal to the connection area 9. The connecting section 8.1 lies accordingly on the outside of the extension element 4. The collar section 8.2 merges into a capsule section 8.5, which encloses the connection area 9. The capsule section 8.5 has bulges 8.6 in which the ends of the bolt element 5 can be received. This creates a tangential and axial positive connection between the protective element 8 and the shaft arrangement 2. The sleeve section 8.3 adjoins the capsule section 8.5. Like the connecting section 8.1, this has a smaller radial extent than the capsule section 8.5. Due to the radial expansion of the extension element 4 in the connection area 9, when assembling the steering gear unit 1, it is not possible to place the protective element 8 and the extension element 4 axially one after the other, as in the first embodiment. This problem is solved in that the protective element 8 consists of two sections 8.7, 8.8, which are connected by a film hinge 8.9. After the extension element 4 has been pushed onto the pinion shaft 3 and secured by means of the bolt element 5, the protective element is attached by pivoting the sections 8.7, 8.8 against each other about the film hinge 8.9 and folding them together until they are in a contact area 8.10 that is continuous in the axial direction A issue. The two sections 8.7, 8.8 can be connected to one another by a clamp connection, by gluing or in another way.

List of reference symbols:

1

Steering gear unit

2

Wave arrangement

3

Pinion shaft

3.1

Nut

4

Extension element

4.1

connection section

4.2

expansion slot

5

Bolt element

6

first gap

7

second gap

8th

Protective element

8.1

connection section

8.2

collar section

8.3

sleeve section

8.4

holding section

8.5

Capsule section

8.6

Bulging

8.7, 8.8

section

8.9

film hinge

8.10

Contact area

9

Connection area

10

Gearbox housing

11

Cuff element

11.1

pipe section

11.2

pipe end

A

axial direction

D

distal side

P

proximal side

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was 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 3801846 C2 [0003]
• DE 102018107863 A1 [0004]

Claims (10)

Steering gear unit (1) for a motor vehicle, with a shaft arrangement (2) which has an axially extending pinion shaft (3) leading distally to a gear housing (10) and a non-rotatably connected to the pinion shaft (3) and located at least partially proximal to the pinion shaft (3) extending extension element (4), as well as with a sleeve element (11), which is connected to the gear housing (10) and surrounds the pinion shaft (3) at a radial distance with a tube section (11.1), so that between a proximal tube end (11.2 ) of the pipe section (11.1) and the pinion shaft (3) a tangentially circumferential first gap (6) is formed, characterized in that a protective element (8) is connected to the shaft arrangement (2) proximally of the pipe section (11.1) and has a tangentially circumferential space formed sleeve section (8.3), which extends distally beyond the pipe end (11.2) with respect to the axial direction (A) and partially surrounds the pipe section (11.1) on the radial outside, the protective element (8) passing through a second gap (7). Cuff element (11) is spaced apart. Steering gear unit Claim 1 , characterized in that the protective element (8) has a connecting section (8.1) which rests on the shaft arrangement (2) and a collar section (8.2) which extends radially outwards from this and to which the sleeve section (8.3) is at least indirectly connected. Steering gear unit according to one of the preceding claims, characterized in that the protective element (8) forms a positive connection with the shaft arrangement (2) in the tangential direction. Steering gear unit according to one of the preceding claims, characterized in that the protective element (8) forms a positive connection with the shaft arrangement (2) in the axial direction (A). Steering gear unit according to one of the preceding claims, characterized in that the shaft arrangement (2) has a bolt element (5) which extends at an angle to the axial direction (A), through which the extension element (4) is connected to the pinion shaft (3) in a rotation-proof manner, wherein the protective element (8) has a holding section (8.4) which engages in a form-fitting manner with the bolt element (5). Steering gear unit according to one of the preceding claims, characterized in that the holding section (8.4) surrounds the bolt element (5) in an arc and forms an axial positive connection with it. Steering gear unit according to one of the preceding claims, characterized in that the extension element (4) has an axial expansion slot (4.2) in which the holding section (8.4) is at least partially arranged. Steering gear unit according to one of the preceding claims, characterized in that the holding section (8.4) is connected radially on the inside to the connecting section (8.1) and distally to the collar section (8.2). Steering gear unit according to one of the preceding claims, characterized in that the protective element (8) has two sections (8.7, 8.8) connected by a film hinge (8.9) which rest against one another in a contact area (8.10) that is continuous in the axial direction (A). Steering gear unit according to one of the preceding claims, characterized in that the connecting section (8.1) is connected to the extension element (4) and the collar section (8.2) is followed by a capsule section (8.5) which surrounds a connection area (9) on the radial outside, in to which the pinion shaft (3) is connected to the extension element (4), and to which the sleeve section (8.3) is connected.

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