Electromechanical vehicle steering device and method for producing same

Abstract

The invention relates to an electromechanical vehicle steering device (1), comprising a housing (2), an electric motor (3) having an axis of rotation (A), a tappet (4) having a longitudinal axis (B), which tappet (4) is arranged in the housing (2) so as to be axially displaceable in the direction of the longitudinal axis (B) and the longitudinal axis (B) extends parallel to the axis of rotation (A) of the electric motor (3), a gearwheel (5) by means of which the electric motor (3) is drivingly coupled to the tappet (4), the gear (5) is mounted in the housing (2) in order to convert a rotational movement of the motor (3) into a linear movement of the push rod (4), the gear (5) comprising a toothed belt drive (51) and a ball screw drive (55), a ball screw nut (56) of the ball screw drive (55) meshing with the push rod (4), and the push rod (4) being mounted in the housing (2), the ball screw nut (56) being mounted on the housing (2) by means of an adjustable bearing (57), the toothed belt (54) of the toothed belt drive (51) can be tensioned by an adjustable bearing (57). The push rod (4) is also mounted in the housing (2) by means of a guide bushing (70). The position of the guide bushing (70) is radially adjustable relative to the tappet (4) in the housing (2). The invention further relates to a method for producing such a vehicle steering device.

Description

[0001] The present invention relates to an electromechanical vehicle steering system, comprising a housing, a motor having a rotational axis, and a push rod having a longitudinal axis. The push rod is arranged in the housing and can move axially in the direction of the longitudinal axis and the longitudinal axis extends parallel to the rotational axis of the motor. The motor is drivenly connected to the push rod through the transmission so as to convert the rotational motion of the motor into linear motion of the push rod. The transmission comprises a toothed belt transmission and a ball screw transmission. The ball screw nut of the ball screw transmission is engaged with the push rod. The push rod is installed in the housing. The ball screw nut is installed on the housing through an adjustable bearing. The toothed belt of the toothed belt transmission can be tensioned through the adjustable bearing.

[0002] The invention also relates to a method for producing such an electromechanical vehicle steering system.

[0003] A universal electromechanical vehicle steering system is known from DE 10 2008 050 248 A1. In this case, a toothed belt drive is coupled to the output shaft of the electric motor via a first, smaller toothed pulley and, via another, larger toothed pulley, to the ball screw nut of a ball screw drive, which is operatively engaged with the steering system's push rod. To adjust the belt preload, after placing the toothed belt on the steering gear pulley, the rack is tilted relative to the steering gear housing while simultaneously loosening the ball screw bearings until the predetermined belt preload, measured during the adjustment process, is reached. The ball screw bearings are then fixed in their original positions on the steering gear housing. This eliminates the need for additional tensioning and adjustment mechanisms on the toothed belt drive. The belt preload can be adjusted automatically. However, tension may be generated by tilting the toothed belt to tension it.

[0004] DE 10 2009 037 873 B4, a modification of DE 10 2008 050 248 A1, proposes first measuring the toothed belt while applying a predetermined belt preload. Based on the measurement results, the center distance between the first toothed belt pulley and the bearing unit for the next toothed belt pulley is adjusted by adjusting the position of the bearing unit so that the predetermined belt preload is achieved on the subsequently installed toothed belt. The next toothed belt pulley is then mounted on the bearing unit. Only then is the measured toothed belt installed on the toothed belt pulley. This allows for high adjustment accuracy of the toothed belt preload, as any tolerances in the toothed belt are compensated for at the end of the process chain.

[0005] Since the toothed belt drive is adapted to the specifically assembled toothed belt during the assembly process, there is no need for complex preliminary measuring and sorting of the toothed belts and toothed belt drives for individual allocation.

[0006] Another advantage of the solution in DE 10 2009 037 873 B4 is that the bearing unit can be secured to the toothed belt drive, particularly the toothed pulley, in a concealed manner. Once the toothed belt assigned to the toothed belt drive has been measured, the bearing unit can be adjusted and secured, and the toothed pulley assembled, before or on the bearing unit, before the toothed belt is installed. This increases design freedom. Furthermore, the bearing unit and associated pulley can be accommodated very compactly, for example, in a vehicle steering housing. Because the toothed belt is measured with a predetermined belt preload applied, its expansion behavior is taken into account during assembly, which means that the dispersion of the belt preload is kept extremely low. This is crucial for a uniform steering feel in mass production. However, in the solution proposed in DE 10 2009 037 873 B4, the toothed belt must be installed in a preloaded state, which is only possible with spur-toothed belts, whose running characteristics are less favorable than those of helical-toothed belts.

[0007] Another method for ensuring the lowest possible distribution of the toothed belt preload is known from DE 10 2006 036 215 B4. It describes a method for assembling a steering gear with a toothed belt drive without a tensioning device. The method is based on two toothed belt pulleys with a fixed, non-adjustable center distance, which are coupled to each other via a pre-tensioned toothed belt. The center distance of the toothed belt pulleys is fixed. DE 10 2006 036 215 B4 proposes measuring the actual wheelbase of the toothed belt pulleys for each steering gear within a tolerance range for the wheelbase. A number of toothed belt grades are provided, each grade being categorized by different lengths and / or widths. All toothed belts belonging to a grade, combined with the tolerance range for the wheelbase of the toothed belt in the assembled state, result in a toothed belt tension within a predetermined tolerance range. A toothed belt is then selected from the corresponding belt grade based on the measured actual wheelbase and then assembled. However, this process is quite complex due to the large number of different belts required and the selection process required during assembly.

[0008] Another electromechanical vehicle steering device is known from DE 10 2010 034 698 A1. Its assembly is as follows: First, the toothed belt pulleys of a toothed belt drive are assembled, with at least one toothed pulley being off-axis relative to the transmission component. The toothed belt is then loosely placed on the toothed belt pulleys. Then, at least one toothed belt pulley is moved from its off-axis position to a tensioning position to tension the toothed belt. Finally, the initially off-axis toothed belt pulley is secured in a clamped position. This process enables the installation of a toothed belt with a toothed profile that, due to its geometry, cannot be pushed axially onto the gears in the toothed belt drive, which is only slightly off-axis or not off-axis. At the same time, a defined belt tension can be ensured. To tension the toothed belt, a toothed belt pulley, specifically one mounted on a ball screw nut, is rotated relative to the ball screw nut. An eccentric mechanism between the peripheral portion of the ball screw nut and the toothed belt pulleys enables the aforementioned off-axis placement of the toothed belt and subsequent tensioning through relative rotation. However, the manufacture of such an eccentric mechanism is complicated.

[0009] A similar design with an eccentric mechanism is known from DE 103 104 92 A1, but the eccentric mechanism is arranged in a different position than in DE 10 201 0 034 698 A1. According to DE 103 104 92 A1, the motor and / or the push rod are mounted via an eccentric, allowing the center distance between the output shaft and the push rod to be varied. In one embodiment variant, the push rod is housed in a ball screw nut, which in turn is supported on an eccentric ring via rolling bearings. The eccentric ring is in turn mounted in the steering gear housing. By rotating the eccentric ring, the toothed belt of the toothed belt drive can be tensioned.

[0010] The above-mentioned prior art shows the complexity of producing an electromechanical vehicle steering device with a toothed belt drive with respect to ensuring a uniform steering feel in series production.

[0011] The object of the present invention is to provide an alternative which is simple in terms of production technology and which is suitable for continuing to ensure a uniform steering feel in series production with little effort.

[0012] This object is achieved by an electromechanical vehicle steering system having the features of patent claim 1. The vehicle steering device according to the invention is characterized in particular in that the push rod is also mounted in the housing via a guide bushing and the position of the guide bushing is radially adjustable relative to the push rod in the housing.

[0013] Adjustable guide bushings in the housing can be used to compensate for tensions in the gearbox, particularly in the area of ​​the ball screw, which can occur due to manufacturing tolerances while maintaining a constant belt preload.

[0014] However, electromechanical vehicle steering systems remain simple in structure and assembly.

[0015] Since the toothed belt can be placed in a non-prestressed state during assembly, both straight and helical toothed belts can be used.

[0016] The solution according to the invention is particularly suitable for steer-by-wire systems, in which no teeth are required on the push rod for engagement with the steering pinion.

[0017] The position of the push rod in the gear can thus be adjusted independently of one another at two locations: on the one hand, by adjusting the position of the ball screw nut, and on the other hand, by adjusting the position of the additional guide bushing. This allows for particularly great flexibility in compensating for any manufacturing tolerances. Since these can be accommodated to a greater extent than before, the solution according to the invention also reduces manufacturing costs.

[0018] In contrast to electromechanical vehicle steering systems in which the toothed belt pulley is tensioned by adjusting the position of the electric motor, in the solution according to the invention the electric motor can be arranged non-adjustably on or in the housing, which eliminates the need for corresponding sealing points.

[0019] In contrast to electromechanical vehicle steering systems with a fixed center distance between motor and actuator, there is no need to measure the required belt length and sort out toothed belts of suitable length.

[0020] Specific embodiments of the invention are the subject matter of further patent claims.

[0021] For example, the guide bushing can have a sliding bearing, wherein a section of the push rod is axially guided and fixed to prevent rotation around its longitudinal axis. In this case, the guide bushing also assumes the function of preventing the push rod from rotating.

[0022] According to another specific embodiment, the housing housing comprises a portion having a motor receiving space for the motor, which is mounted on the housing or integrally formed therewith, and the motor comprises an output shaft, on which the first toothed pulley of the toothed belt drive is arranged in a rotationally fixed manner. The motor is preferably inserted axially into the motor receiving space from the side opposite the first toothed pulley. This further simplifies assembly.

[0023] According to another specific embodiment, the output shaft of the motor is rotatably mounted in the housing via a rolling bearing, the outer ring of which rests on a shoulder on the inner wall of the housing. This provides, on the one hand, excellent support for the tension of the toothed belt and, on the other hand, excellent access to the toothed belt drive for mounting the toothed belt pulleys.

[0024] According to another specific embodiment of the invention, the adjustable bearing comprises a rolling bearing and a bearing clamping device, wherein the outer ring of the rolling bearing is radially movable in the housing relative to the longitudinal axis of the push rod and is fixed to the housing by the bearing clamping device. The bearing clamping device is clamped to the housing radially outside the second toothed belt pulley, which is arranged in a rotationally fixed manner on the ball screw nut. This makes it very easy to adjust the position of the ball screw nut when tensioning the toothed belt pulley. The production of an eccentric surface is thus eliminated.

[0025] According to another specific embodiment of the invention, the housing integrally forms a section with a gear receiving space. The outer wall of this gear receiving space extends radially around the toothed belt drive and is closed at the end by a drive cover having a through-hole for the push rod. This makes the components of the toothed belt drive easily accessible during assembly. At the same time, the housing structure remains simple.

[0026] The above object is further achieved by a method for producing an electromechanical vehicle steering device of the type having an axially parallel arrangement of a push rod and an electric motor according to claim 7. The method is characterized by the following steps, namely:

[0027] -Attach the motor to the actuator's housing,

[0028] - inserting a ball screw nut with rolling bearing into the gear receiving space of the housing, the ball screw nut being designed to support the push rod,

[0029] - Pre-fix the rolling bearing on the housing,

[0030] - Arrange a toothed pulley on the output shaft of the motor and the ball screw nut,

[0031] - Place the toothed belt loosely on the installed toothed belt pulley,

[0032] - tensioning the toothed belt by radially displacing the rolling bearing of the ball screw nut and securing the rolling bearing with the toothed belt tensioned, and

[0033] - providing a guide bushing for guiding the push rod, radially positioning the guide bushing in the housing according to the position of the rolling bearing of the ball screw nut, and fixing the guide bushing to the housing.

[0034] If necessary, the steps can be performed in the order specified here, but this is not binding. This process can be carried out manually and, if desired, automatically or partially automatically with minimal effort. In particular, the toothed belt tension can be adjusted with high precision despite relatively coarse tolerances, thus avoiding tension in the ball screw.

[0035] According to a special embodiment of the method, the push rod can be moved in parallel with the ball screw nut and the guide bushing in the housing radially to the longitudinal axis of the push rod. This makes it possible to prevent the push rod from tilting in the ball screw nut particularly well.

[0036] According to another particular embodiment of the method, the motor and the ball screw nut are inserted into the housing from opposite sides and in opposite directions.

[0037] According to another specific embodiment, the motor is inserted into the motor receiving space together with the first toothed belt pulley preassembled on the output shaft, which is guided through the bearing point for the output shaft on the housing. By forming such a sub-unit, assembly can be further simplified. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The following explains in more detail the manner in which the present invention is implemented using the exemplary embodiments shown in the accompanying drawings. The accompanying drawings show:

[0039] Figure 1 is a longitudinal sectional view of a possible exemplary embodiment of an electromechanical vehicle steering system according to the invention.

[0040] Figure 1 The exemplary embodiment in FIG. 1 shows an electromechanical vehicle steering device 1 , which in the present case is designed as a steer-by-wire device, for example for a passenger car or a light commercial vehicle.

[0041] The electromechanical vehicle steering system 1 comprises a housing 2, an electric motor 3 having an axis of rotation A, a push rod 4 having a longitudinal axis B, and a transmission 5, via which the electric motor 3 is drive-coupled to the push rod 4 so as to convert the rotational movement of the electric motor 3 into a linear movement of the push rod 4 in the direction of its longitudinal axis B.

[0042] The push rod 4 is in turn coupled to a wheel carrier (not shown) via a push rod joint 6 , such that a linear movement of the push rod 4 along its longitudinal axis B results in a steering rotation of the associated wheel.

[0043] For this purpose, the push rod 4 is arranged in the housing 2 such that it can be moved axially in the direction of the longitudinal axis B. The longitudinal axis B of the push rod 4 extends parallel to the rotation axis A of the electric motor 3 .

[0044] The motor 3 can be connected to the part of the housing 2 that accommodates the push rod 4 via a flange. The motor 3 can also be arranged in a motor receiving space 21 of the housing 2, which is formed by an integral section 22 of the housing 2.

[0045] In an embodiment variant, the components of the motor 3 are provided as a power pack 31 which is mounted directly in the motor receiving space 21 of the section 22 . In this case, the motor housing is formed by an integral wall section of the housing 2 of the push rod 4 .

[0046] However, as already mentioned, the section 22 with the motor receiving space 21 can be provided as a separate component and fixedly mounted on another housing 2 that accommodates the tappet 4 .

[0047] In all cases, the position of the motor 3 relative to the housing 2 of the push rod 4 is fixed and cannot be adjusted. Therefore, the position of the axis of rotation A of the motor 3 is fixed. In the ideal case of a one-piece construction of the section 22 and the housing 2 of the push rod 4, the sealing points that would otherwise be required are eliminated.

[0048] The transmission 5 comprises a toothed belt drive 51 and a ball screw drive 55 , which in the present case are connected in series for transmission purposes.

[0049] The toothed belt drive 51 comprises a first toothed belt pulley 52 and a second toothed belt pulley 53, which are coupled in a rotationally fixed manner to the output shaft 32 of the motor 3, and a toothed belt 54 placed on these toothed belt pulleys 52 and 53. The toothed belt 54 can have straight or helical teeth.

[0050] The ball screw 55 has a ball screw nut 56 , which engages with a corresponding threaded section 41 of the push rod 4 via balls 56 a and supports the push rod 4 in the housing 2 .

[0051] For this purpose, a ball screw nut 56 is rotatably mounted in the housing 2 while being fixed against axial displacement.

[0052] In the exemplary embodiment shown, an adjustable bearing 57 is provided for this purpose, which can be designed as a rolling bearing, for example. An inner ring 58 of the adjustable bearing 57 is fixed to the ball screw nut 56 , while an outer ring 59 of the adjustable bearing is fixed to the housing 2 .

[0053] In order to fix the adjustable bearing 57 , a bearing clamping device 60 can be provided, by which the outer ring 59 of the adjustable bearing 57 is fixed axially and radially relative to the housing 2 .

[0054] It should be noted in this context that the adjustable bearing 57 can be moved radially relative to the longitudinal axis B of the push rod 4 before it is fixed to the housing 2 , in order to enable the toothed belt 54 to be placed and tensioned.

[0055] The bearing clamping device 60 can be formed, for example, by a retaining disk or a retaining ring, which is axially clamped on the housing 2 by means of screws 61 or the like, including the adjustable bearing 57 .

[0056] The clamping of the bearing clamping device 60 to the housing 2 can preferably be carried out radially outside the second toothed belt pulley 53, which is arranged in a rotationally fixed manner on the ball screw nut 56. Depending on the design of the bearing clamping device 60, the clamping can also take place within the circumference of the second toothed belt pulley 53, for example by providing corresponding through-holes in the latter, which enable access to suitable clamping means, such as screws 61.

[0057] As a variation of this, other fastening mechanisms can also be provided to fix the outer ring 59 of the adjustable bearing 57. In particular, the outer ring 59 of the adjustable bearing 57 can be screwed directly to the housing 2. For this purpose, a corresponding flange can optionally be formed on the outer circumference of the outer ring 59.

[0058] However, since the manufacture and processing of rolling element steel is generally complicated, fastening using the bearing clamping device 60 would be preferred.

[0059] As previously mentioned, the push rod 4 is mounted on the housing 2 via a ball screw nut 56 and an adjustable bearing 57. The toothed belt 54 of the toothed belt drive 51 is tensioned by radially displacing the adjustable bearing 57 relative to the housing 2 when the longitudinal axis B of the push rod 4 is displaced relative to the housing 2 and relative to the rotation axis A of the motor 3, thereby ultimately also fixing the push rod 4 in this position.

[0060] To avoid tension in the ball screw 55, the push rod 4 is also mounted in the housing 2 via a guide bushing 70. In other words, in addition to the first support point L1 on the ball screw 55, a separate second support point L2 for the push rod 4 is provided via the guide bushing 70 in the housing 2.

[0061] In the present case, the position of the guide bushing 70 is radially adjustable relative to the push rod 4 in the housing 2. When the toothed belt 54 is tensioned, the position of the push rod 4 in the region of the guide bushing 70 can be radially adjusted, for example to prevent the push rod 4 from tilting in the ball screw 55. In series production, this has a positive effect on the uniform steering feel of many vehicle steering systems.

[0062] The guide bushing 70 can in particular have a sliding bearing, in which the tappet 4 is axially guided via the section 42 and is additionally secured against rotation about its longitudinal axis B.

[0063] For simple assembly of the electromechanical vehicle steering system, the motor 3 can be provided with an output shaft 32 on which the first toothed pulley 52 of the toothed belt drive 51 is arranged in a rotationally fixed manner. The motor 3 is preferably inserted axially into the motor receiving space 21 from the side opposite the first toothed pulley 52 .

[0064] In addition, the output shaft 32 of the motor 3 can be rotatably mounted in the housing 2 via a rolling bearing 33 , wherein the outer ring 34 of the rolling bearing 33 is supported on the inner wall shoulder 23 of the housing 2 .

[0065] The rolling bearing 33 of the drive shaft 32 is arranged axially between the electric motor 3 and the first toothed pulley 51 .

[0066] The motor receiving space 21 can be delimited by the rolling bearing 33 of the drive shaft 32 relative to a section 24 having a gear receiving space 25, which is preferably formed integrally with the housing 2. The gear 5 having the toothed belt drive 51 and the ball screw drive 55 can be arranged in this gear receiving space 25.

[0067] Preferably, the outer wall of the segment 25 extends radially around the toothed belt drive 51. The gear receiving space 25 is preferably open at the end over the entire area of ​​the toothed belt drive 51, thereby making it very easy to assemble the components of the toothed belt drive 51. After assembly, the gear receiving space 25 can be closed at the end by a gear cover 26, which has a through-hole for the push rod 4.

[0068] In the same manner, a motor cover 27 may be provided on the motor accommodation space 21 , which is installed after the motor 3 or the corresponding power pack 31 is installed.

[0069] An electromechanical vehicle steering system of the type having an axially parallel arrangement of push rod 4 and electric motor 3 as described above can be produced in the manner explained in more detail below.

[0070] Manufacturing first involves mounting the motor 3 to the housing 2 of the push rod 4. Specifically, this involves inserting the motor 3 or a corresponding power pack 31 into the motor receiving space 21 of the housing 2. If the motor receiving space 21 is provided by a separate housing component, this separate housing component is first mounted to the housing 2 of the push rod 4. Mounting the motor 3 can also involve firmly flange-connecting the motor 3 to the housing 2 of the push rod 4. The position of the rotation axis A of the motor 3 relative to the housing 2 is thus fixed and can therefore no longer be changed.

[0071] Furthermore, production includes inserting a ball screw nut 56 with an adjustable bearing 57 , in particular a rolling bearing, into the gear receiving space 25 of the housing 2 . As described above, the ball screw nut 56 is designed to support the push rod 4 .

[0072] The push rod 4 can be installed together with the ball screw nut 56 at the same time. However, the push rod 4 can also be installed only after the ball screw nut 56 is installed.

[0073] The adjustable bearing 57 or the rolling bearing is then pre-fixed to the housing 2 , for example, by means of mounting screws 61 .

[0074] Furthermore, toothed pulleys 52 and 53 are arranged on the output shaft 32 of the electric motor 3 and on a ball screw nut 56 .

[0075] Specifically, the second toothed pulley 53 may be mounted on the ball screw nut 56 after the adjustable bearing 57 is pre-fixed.

[0076] The first toothed pulley 52 may be provided when the motor 3 is mounted on the housing 2 , but may also be subsequently mounted on the output shaft 32 that has been mounted on the housing 2 .

[0077] If the motor 3 is inserted into the motor receiving space 21 together with the first toothed belt pulley 52 pre-mounted on the output shaft 32 , the first toothed belt pulley 52 can pass through the bearing point for the output shaft 32 on the housing 2 .

[0078] The toothed belt 54 is placed in a loose, untensioned state on the mounted toothed belt pulleys 52 and 53. The pre-fixation of the adjustable bearing 57 is adjusted accordingly.

[0079] After the toothed belt 54 is placed, the toothed belt is tensioned by radially moving the adjustable bearing 57 of the ball screw nut 56 until the desired toothed belt tension is achieved. Here, the position of the longitudinal axis B of the push rod 4 is moved relative to the housing 2, i.e., in the radial direction of the longitudinal axis B.

[0080] Then, when the toothed belt 54 is tensioned, the adjustable bearing 57 is fixed while maintaining the set toothed belt tension.

[0081] According to the present invention, a guide bushing 70 is also provided on the housing 2 as a second bearing point L2 for guiding the push rod 4. When the toothed belt 54 is tensioned, the guide bushing 70 can be radially positioned in the housing 2 according to the position of the adjustable bearing 57 of the ball screw nut 56 to avoid tension, and the guide bushing 70 can be fixed to the housing 2.

[0082] When the toothed belt 54 is tightened, the push rod 4 can be displaced radially and substantially parallel to the longitudinal axis B of the push rod 4 in the housing 2 by means of the ball screw nut 56 and the guide bushing 70, as shown in the figure. Figure 1 The double arrows at the bearing points L1 and L2 in FIG. This displacement occurs transversely or radially to the longitudinal axis B of the push rod 4 .

[0083] The motor 3 and the ball screw nut 56 can be inserted into the housing 2 from opposite sides in opposite directions. The corresponding insertion openings of the housing 2, which is preferably made in one piece, are finally closed by covers 26 and 27. A bellows can be used to seal between the housing 2 and the tie rod joint 6.

[0084] The present invention has been explained in more detail above using exemplary embodiments and further modifications. In particular, the individual technical features explained above in the context of further individual features can be implemented independently of these individual features and in combination with further individual features, even if this is not explicitly described, as long as this is technically possible. Therefore, the present invention is obviously not limited to the described exemplary embodiments and specifically mentioned modifications, but includes all configurations defined by the patent claims.

[0085] List of Reference Numerals

[0086] 1Electromechanical vehicle steering system

[0087] 2 shell

[0088] 3 motors

[0089] 4 putters

[0090] 5. Transmission

[0091] 6 push rod joint

[0092] 21 Motor accommodation space

[0093] 22 Section of the housing 2

[0094] 23 inner wall shoulder

[0095] 24 Section of the housing 2

[0096] 25 Transmission space

[0097] 26 Transmission cover

[0098] 27 Motor cover

[0099] 31 power group

[0100] 32 output shaft

[0101] 33 rolling bearings

[0102] 34 Outer Ring

[0103] 41 thread segments

[0104] Section 42

[0105] 51 toothed belt drive

[0106] 52 first toothed pulley

[0107] 53 Second toothed pulley

[0108] 54 tooth belt

[0109] 55 ball screw

[0110] 56 ball screw nut

[0111] 56a ball

[0112] 57 Adjustable bearing

[0113] 58 Inner Ring

[0114] 59 Outer Ring Road

[0115] 60 bearing clamping device

[0116] 61 bolts

[0117] 70 guide bushing

[0118] A. Rotation axis of motor 3

[0119] B longitudinal axis of push rod 4

[0120] L1 first support part

[0121] L2 second support part

Claims

1. An electromechanical vehicle steering system (1), comprising Housing (2), an electric motor (3) having an axis of rotation (A), A push rod (4) having a longitudinal axis (B), wherein The push rod (4) is arranged in the housing (2) so as to be axially movable in the direction of the longitudinal axis (B), and the longitudinal axis (B) extends parallel to the rotation axis (A) of the motor (3). a transmission (5) by which the motor (3) is drivingly coupled to the push rod (4) so ​​as to convert the rotary motion of the motor (3) into a linear motion of the push rod (4), Wherein, the transmission device (5) includes a toothed belt transmission device (51) and a ball screw transmission device (55). wherein the ball screw nut (56) of the ball screw transmission (55) engages with the push rod (4) and supports the push rod (4) in the housing (2), wherein the ball screw nut (56) is mounted on the housing (2) via an adjustable bearing (57), and The toothed belt (54) of the toothed belt drive (51) can be tensioned via an adjustable bearing (57). It is characterized in that The push rod (4) is also supported in the housing (2) via a guide bushing (70), and the position of the guide bushing (70) is adjustable in the housing (2) in a radial direction relative to the push rod (4).

2. The electromechanical vehicle steering device (1) according to claim 1, characterized in that The guide bushing (70) has a plain bearing in which the push rod (4) is axially guided via a section (42) and secured against rotation about its longitudinal axis (B).

3. The electromechanical vehicle steering device (1) according to claim 1 or 2, characterized in that A section (22) having a motor receiving space (21) for the motor (3) is fixed to or integrally formed on the housing (2), the motor (3) having an output shaft (32), a first toothed belt pulley (52) of the toothed belt drive (51) being rotationally fixedly arranged on the output shaft, and the motor (3) being axially pushed into the motor receiving space (21) from a side opposite to the first toothed belt pulley (52).

4. The electromechanical vehicle steering device (1) according to claim 3, characterized in that The output shaft (32) of the motor (3) is rotatably mounted in the housing (2) via a rolling bearing (33), and the outer ring rolling bearing (34) is supported on the inner wall shoulder (23) of the housing (2).

5. The electromechanical vehicle steering device (1) according to any one of claims 1 to 4, characterized in that The adjustable bearing (57) comprises a rolling bearing and a bearing clamping device (60), the outer ring (59) of the rolling bearing being movable radially in the housing (2) relative to the longitudinal axis (B) of the push rod (4) and being fixed to the housing (2) by means of the bearing clamping device (60), wherein the clamping of the bearing clamping device (60) to the housing (2) is preferably performed radially outside a second toothed belt pulley (53) of the toothed belt drive (51) which is arranged in a rotationally fixed manner on the ball screw nut (56).

6. An electromechanical vehicle steering device (1) according to any one of claims 1 to 5, characterized in that The housing (2) integrally forms a section (24) having a transmission receiving space (25), the outer wall of which extends radially around the toothed belt drive (51), and the transmission receiving space (25) is closed at the end by a transmission cover (26), which has a through-opening for the push rod (4).

7. A method for producing an electromechanical vehicle steering device (1) of the type having an axially parallel arrangement of a push rod (4) and an electric motor (3), characterized in that: - Mount the motor (3) on the housing (2) of the push rod (4), - introducing a ball screw nut (56) with a rolling bearing into the transmission receiving space (25) of the housing (2), wherein the ball screw nut (56) is designed to support the push rod (4), - Pre-fix the rolling bearing on the housing (2), - arranging the toothed pulleys (52, 53) of the toothed belt drive (51) on the output shaft (32) of the motor (3) and on the ball screw nut (56), - place the toothed belt (54) of the toothed belt drive (51) loosely on the installed toothed pulleys (52, 53), - tensioning the toothed belt (54) by radially displacing the rolling bearing of the ball screw nut (56) and fixing the rolling bearing when the toothed belt (54) is tensioned, - providing a guide bushing (70) for guiding the push rod (4), and radially positioning the guide bushing (70) in the housing (2) according to the position of the rolling bearing of the ball screw nut (56), and fixing the guide bushing (70) to the housing (2).

8. The method according to claim 7, characterized in that The push rod (4) is movable in the housing (2) with the ball screw nut (56) and the guide bushing (70) radially parallel to the longitudinal axis (B) of the push rod (4).

9. The method according to claim 7 or 8, characterized in that The motor (3) and the ball screw nut (56) are pushed into the housing (2) from opposite sides and in opposite directions.

10. The method according to any one of claims 7 to 9, characterized in that The motor (3) is inserted into the motor receiving space (21) together with a first toothed belt pulley (52) pre-assembled on an output shaft (32), wherein the first toothed belt pulley (52) passes through a bearing point on the housing (2) for the output shaft (32).

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