Motor vehicle steering system, assembly tool and assembly method for a motor vehicle steering system

Abstract

A motor vehicle steering system is disclosed. The system includes a steering spindle consisting of spindle members which are non-rotatably connected to one another. One end of a spindle member has a spline shaft profile and is introduced into a sleeve-like intermediate piece which is arranged on the other spindle member and, on the inner periphery, has a negative-shaped spline shaft profile with respect to the spline shaft profile such that the spindle member is plug-connected to the intermediate piece. In order for the spindle members to be able to be connected to each other with minimal effort even in the event of visual inaccessibility, a circumferential guide contour pointing toward the intermediate piece is formed on the spindle member. The guide contour is upstream of the spline shaft profile toward the intermediate piece and is perforated by grooves of the spline shaft profile to form convex guide segments.

Claims

1. A motor vehicle steering system, comprising: a steering spindle including a first spindle member and a second spindle member, wherein the first spindle member is non-rotatably connected to the second spindle member, wherein an end of the first spindle member has a spline shaft profile disposed in an axial direction on an outer periphery of the first spindle member, wherein the spline shaft profile is disposed in a sleeve intermediate piece which is disposed on the second spindle member; and a plug having a circumferential guide contour; wherein the spline shaft profile has a plurality of teeth and a plurality of grooves; wherein the plurality of grooves of the spline shaft profile extend axially through the circumferential guide contour; wherein an insertion extension extends coaxially at least from the circumferential guide contour in a direction facing the sleeve intermediate piece and wherein the insertion extension is disposed in the sleeve intermediate piece; wherein the insertion extension is hollow, wherein an engager is disposed on an inner shell surface of the insertion extension, and wherein the engager is a circumferential engaging rib.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 a perspective view of a spindle member assigned to a steering column having an attached plastic plug,

(2) FIG. 2 a perspective view of the connection of the spindle member from FIG. 1 assigned to the steering column having a steering coupling,

(3) FIG. 3 a longitudinal section of the plastic plug from FIG. 1, and

(4) FIG. 4 a perspective view of the spindle member from FIG. 1 assigned to the steering column having an assembly tool coupled thereto.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) The stump depicted in FIG. 1 of a spindle member 1 assigned to a steering column shows the end 11 which is connected in an assembled motor vehicle steering system to the steering coupling 2 (FIG. 2) by means of a sleeve-like intermediate piece 21 supported by this. The spindle member 1 has a spline shaft profile 12 on its end 11, with the same tooth spacing and tooth depths and tooth widths, which leads to the spindle member 1 being relatively easy to produce. The spline shaft profile 12 consists of teeth 5 and grooves 6, which each have a conical shape in the vertical direction (this means the thickness direction) and taper towards the end 11 of the spindle member 1. The intermediate piece 21 also has a spline shaft profile on the inner side which is formed to be negative-shaped with respect to the spline shaft profile 12 of the spindle member 1. The spline shaft profile of the intermediate piece is also designed in the vertical direction conically with the same taper angle, wherein, however, the cone opens towards the spindle member 1. As a result, a wedge clamping force is used during assembly of the two spindle members 1 and 2 which achieves particularly good hold of the two members 1 and 2 with respect to each other. This becomes even more important since a compression spring based clamping device is integrated in the intermediate piece 21 which takes effect in the end position of the plug connection and pulls the two members towards each other, whereby the wedge clamping force is very large. In addition, the teeth 5 and the grooves 6 can be formed conically in the width direction, wherein the grooves 6 open towards the end 11 of the steering spindle and the teeth 5 are tapered. The spline shaft profile of the intermediate piece 21 is correspondingly formed to be negative-shaped, such that, when plugging together the two members 1 and 2, a wedge clamping force which acts transversely to the plug-in direction is achieved in this respect too.

(6) A plastic plug 3 can be seen at the end side upstream of the spline shaft profile 12 of the spindle member 1 in the direction of the intermediate piece 21, the plastic plug having a guide contour 13 next to an insertion extension 14 (also see FIG. 3). The insertion extension 14 is provided with a small but effective chamfer 15 on its end side front surface, which should help during assembly to improve centering of the plastic plug 3 and therefore of the spindle member 1 in an assigned receiver, here the intermediate piece 21 of the steering coupling 2. The grooves 6 of the spline shaft profile 12 extend axially through the guide contour 13, which is formed on the bottom side of an annular collar 8 facing away from the steering spindle member 1, or they break through axially to form guide segments 10. The annular collar 8 thereby forms the contact surface between the plastic plug 3 and the spindle member 1 with its upper side 9 and closes largely flush with the spline shaft profile 12. If you were to look at the processing of the guide contour 13, then you would see an undulating curve path which delimits the guide contour 13 on the side facing away from the contact surface. In the case of the delimited curve path, the bulged or indented sections themselves can be symmetrical, wherein the longitudinal axes of the grooves 6 of the spline shaft profile 12 run through the vertices of the indented sections and either the longitudinal axis of a groove 6 of a tooth 5 of the spline shaft profile 12 runs through the vertices of the bulged or indented sections. The guide contour 13 is formed to facilitate assembly of the steering spindle member 1, which usually takes place in a tight, i.e. visually and tactilely barely accessible region. According to the operating principle of the cam disc and probe pin, it makes it possible for the installer to detect the correct angular position in a tactile manner.

(7) In an embodiment which is not depicted figuratively, the insertion extension 14 and the guide contour 13 can principally also be integral components of the steering spindle member 1, which, however, would be associated with higher costs for processing of the steering spindle member 1, which is mostly produced from metal. A plastic part according to the invention is particularly advantageous at this point, since it can be produced with complex shapes in a cost-effective manner, for example by injection molding.

(8) For the assembly of the steering spindle member 1, which is mostly telescopic as part of a telescopic steering column, with the steering coupling 2, the steering spindle end 11 of the spindle member 1 is introduced very closely on the region of the steering coupling 2, which is intended for receiving the steering spindle member 1, in particular on the intermediate piece 21. Such a position shortly before the insertion of the steering spindle member 1 into the intermediate piece 21 is depicted in FIG. 2.

(9) In FIG. 2 it is clear to see how the insertion extension 14 of the spindle member 1 assigned to the steering column or of the plastic plug 3 partially protrudes into the steering coupling 2. Furthermore, the intermediate piece 21 is depicted as a part of the steering coupling 2 which is held moveably on the steering coupling 2. The teeth of the spline shall profile are formed in the interior of the substantially cylindrical intermediate piece 2 the teeth being brought into engagement in a joined position with grooves 6 of the spline shaft profile 12 of the spindle member 1. Protrusions 24 protruding radially inwards, which are formed as tongues 24, are arranged on a front side 23 of the intermediate piece 21 facing the spindle member 1. Furthermore, the tongues 24 are also bent upwards to a certain extent, i.e. in the direction of the spindle member 1, which is also easy to implement in terms of production since the intermediate piece 21 can be produced at least partially, for example, by means of deep drawing and stamping a sheet metal. If the spindle member 1 is now to be coupled operatively to the steering coupling 2 as intended, then the spindle member 1 is introduced even more closely on the intermediate piece 21 of the steering coupling 2, until the collar 8 having the guide contour 13 rests on the tongues 24. If the relative angular position of the two coupling partners is already suitable, then the spline shaft profiles matched geometrically with respect to each other are able to simply slide into each other.

(10) In the event of the individual teeth/grooves 5,6 of the spline shaft profile 12 and therefore also of the spline shaft profile of the intermediate piece 21 differing in terms of width, spacing and depth, it is possible to couple the spindle member 1 in accordance with the poka-yoke principle only in exactly one angular position to a steering coupling by means of this asymmetrical spline shaft profile 12. This is advantageous during installation of the spindle member 1 or the steering coupling 2 in a motor vehicle shell, since installation is only possible in one single angular position of the steering coupling 2 and spindle member 1, to which the steering wheel is coupled, which leads to a straight-line positioning of the steering wheel.

(11) The guide contour 13 helps the installer to find this angular position exactly. For this purpose, the installer rotates the steering spindle member 1 slowly in any peripheral direction, wherein the undulated, gently curved regions of the guide contour 13, so the guide segments 10, slide on the tongues 24. Since the widths of the grooves 6 of the spline shaft profile 12 and the widths of the tongues 24 are also different, the tongues 24 cannot accidentally lock into an incorrect groove. Like a cam disc, the guide contour 13 slides on the tongues 24. The installer then continues to rotate it until the predetermined assembly position is reached. In this case, the tongue 24 is located in the region of the assigned indentation (as depicted) and is guided from the flanks of the guide contour 13 in such a way that the tongue 24 continues to rotate virtually automatically in the event of further slight axial pressure being applied in the direction of the vertex of the indentation and then the spline shaft profile 12 can finally be brought into engagement. As a rule, the spindle member 1 is a hollow shaft member or it is at least hollow on the end 11 facing the intermediate piece 21 in order to be able to receive the plastic plug 3 according to the invention, for example by gluing, pressing, expanding.

(12) The poka-yoke principle is similarly fulfilled in a preferred alternative embodiment when the spline shaft profile 12 is symmetrical. However, this requires special precautions. A straight groove 7 running consistently axially is also introduced for this purpose in the outer side in one of the teeth 5 of the steering spindle member 1, the groove containing a section 7a in the annular collar 8. This groove 7 interacts with an additional tongue 25 arranged on the front side 23 of the intermediate piece 21. The groove 7 and the tongue 25 thereby have a width which is different from the grooves 6 and the tongues 24 and/or are arranged asymmetrically with respect to the grooves 6 and 24 in the peripheral direction of the spindle members 1 and 2. Here, the spline shaft profile 12 of the spindle member can only engage with the intermediate piece 21 and thus with the steering coupling 2 when the groove 7 and the tongue 25 lie opposite each other, wherein the tongue 25 slides into the groove 7 during plugging together of the spindle members 1 and 2. In order to find this single possible inserted position, the installer proceeds in the same way as in the aforementioned alternative exemplary embodiment.

(13) In FIG. 3, the plastic plug 3 is finally seen in a longitudinal section. This has a connection extension 31 which can be introduced into the steering spindle member end (which is hollow) as intended. For better fixing of the connection extension 31 in the spindle member 1, the outer diameter thereof can be designed to be slightly larger than the inner diameter of the corresponding bore of the steering spindle member 1. Or alternatively, which is not depicted in the figure, a suitable expanding means, for example an expanding rivet, can be present in the interior. The plastic plug 3 can further contribute to improving the acoustic decoupling of the engine compartment, since otherwise, all types of sounds can enter the passenger compartment through the hollow steering spindle member 1. On the other end, the plastic plug 3 has an insertion extension 14 which plunges, for example, into an intermediate piece 21 (see FIG. 2) during assembly of the spindle member 1 having the steering coupling 2. Here, the insertion extension 14 is hollow and has a chamfer 15 on its end which should facilitate insertion for the installer and improve centering at the same time. Three engaging ribs 32 are arranged on the inner shell surface, with which an assembly tool 4 (FIG. 4) can be brought into engagement for the convenient and low-effort shifting of the plastic plug 3 or the spindle member 1 coupled to the plastic plug 3. Depending on the force to be applied, there can of course also be more or fewer engaging ribs 32 present or, which is not shown in the figure, completely different engaging means which seem suitable to the person skilled in the art. Furthermore, it is also possible, but not shown figuratively, that a sealing is present on an (outer) shell surface of the connection extension 31 which is to prevent moisture and dirt from being able to enter the spindle member 1 and causing corrosion there.

(14) The guide contour 13 is an integral component of the plastic plug 3 and forms a type of double collar sleeve together with the connection extension 31 and the insertion extension 14. Furthermore, the guide contour 13 has an undercut 16 on its front side facing the insertion extension 14 which should improve the guide of the guide contour 13 on the tongues 24 shown in FIG. 2. The ends of the tongues 24 shown there lie in a region of the undercut 16 on the guide contour 13, whereby there is virtually only line contact between the two parts. In addition, radial guiding and centering of the spindle member 1 on the spindle member 2 is also thereby improved. In this context, handling rotational movement is also supported since slipping is avoided as a result of radial stability.

(15) The above-mentioned coupling of the assembly tool 4 to the insertion extension is depicted in FIG. 4. The assembly tool 4 according to the invention has a handle 42 for this purpose which is connected to an engaging end 41 by means of a shaft 43. The shaft 43 can consist of a fibre-reinforced plastic. It can be rigid or it can be a flexible wire or a cable or an elastic core. It is also possible that the shaft 43 has a shape which is adapted to the installation situation in the motor vehicle, the shape being suitable, for example, to enable the use of the assembly tool 4 during assembly from below without obstructions due to other units in the engine compartment. The assembly tool 4 has corresponding engaging means on the engagement end 41 which are to be supported in the engaging means 32 of the insertion extension 14 (see FIG. 3). The engaging means of the assembly tool 4 can, however, also be a simple inflatable balloon or an elastic bellows. By means of the assembly tool 4 shown, the installer can pull out a telescopic steering spindle, assembled in the motor vehicle shell in the collapsed condition, in a convenient manner to its length corresponding to the assembly condition without having to expose himself/herself to the risk of finger injuries.