Steering system

Abstract

To provide a steering system. [Solution] The present invention relates to a steering system comprising an electric motor and a steering gear device, wherein the steering gear device comprises a first steering gear input shaft connectable to a steering shaft, a second steering gear input shaft technically connected to the electric motor, and a steering gear output shaft, and the torque path from the first steering gear input shaft to the steering gear output shaft comprises at least two gear stages technically connected in series. The steering system is characterized in that one of the gear stages is configured as a helical gear mechanism, the helical gear mechanism comprises a first helical gear, and the first helical gear meshes with a second helical gear.

Description

Technical Field

[0001] The present invention relates to a steering system including an electric motor and a steering gear device, wherein the steering gear device includes a first steering gear input shaft connectable to a steering shaft, a second steering gear input shaft operatively connected to the electric motor in terms of drive technology, and a steering gear output shaft, wherein a torque path from the first steering gear input shaft to the steering gear output shaft comprises at least two gear stages connected in series in terms of drive technology.

Background Art

[0002] A power steering system is known from German Utility Model No. 202014101670U1 specification. The power steering system includes a steering wheel shaft, on which a first worm screw and a worm wheel are coaxially arranged. The power steering system further includes an auxiliary power shaft, on which a second worm screw meshing with the worm wheel is coaxially arranged. The power steering system further includes a segment shaft having a gear segment meshing with the first worm screw.

[0003] A steering gear for an electromechanical steering system for vehicles is known from German Patent Application Publication No. 102019127965A1 specification. The steering gear includes an input shaft connectable to or connected to the steering column of the steering system, a segment shaft connectable to or connected to the pitman arm of the steering system, an angle gear, a servo gear, and an electric motor for driving the servo gear. The angle gear is designed as a bevel gear mechanism. The input shaft and electric motor are connected to a servo gear. The servo gear is connected to the angle gear. The angle gear is connected to a segment shaft. The angle gear is configured to transmit torque from the servo gear to the segment shaft via two transmission paths.

[0004] German Patent Application No. 10234596B3 describes a non-trajectory-constrained power steering system for automobiles, configured as a ball-recirculating steering system. To enhance the variability of the ball-circulating steering system, a servo motor, configured as an electric motor, is positioned at the steering gear input to reduce the manual force required for steering.

[0005] From German Patent Application Publication No. 102015217045A1, a commercial vehicle steering system including a steering gear for transmitting manual torque applied to the steering wheel to a pitman arm is known. The steering gear is equipped with an electric motor to supply auxiliary torque for steering assistance, and steering assistance is provided entirely electrically over the entire range of steering motion. The steering gear further comprises an input shaft and an output shaft, whose axes of rotation are in a torsional position relative to each other. The steering gear further comprises a first gear unit connecting the input shaft to the output shaft and a second gear unit to which an electric motor is connected on the input side. The second gear unit is connected to the output shaft on the output side, and the gear stages of the reduction gear unit are arranged coaxially with the output shaft. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] German Utility Model Specification No. 202014101670U1 [Patent Document 2] German Patent Application Publication No. 102019127965A1 Specification [Patent Document 3] German Patent Application No. 10234596B3 Specification [Patent Document 4] German Patent Application Publication No. 102015217045A1 Specification [Overview of the project] [Problems that the invention aims to solve]

[0007] The objective of the present invention is to provide the above-described type of steering system that has a compact design and, at the same time, excellent adaptability to installation conditions in commercial vehicles. [Means for solving the problem]

[0008] This objective is achieved by a steering system characterized in that one of the gear stages is configured as a helical gear mechanism, the helical gear mechanism comprises a first helical gear, and the first helical gear meshes with a second helical gear.

[0009] In embodiments of the present invention, the reduction ratio from the first steering gear input shaft to the steering gear output shaft, which is connected to the steering control unit of a commercial vehicle in a manner that prevents relative rotation and without further gear changes or reductions, is advantageously in the range of 1:22 to 1:26, preferably 1:24, so that the ratio of the steering angle of the steering wheel to the steering action of the wheels matches the steering feel that a typical driver is accustomed to. At the same time, with respect to the motor connection, since the torque required by the steering gear output shaft is very high (e.g., 8000 Nm), it is necessary to consider that a very high reduction ratio, for example in the range of 1:900 to 1:1500, particularly 1:1000, must be achieved in the torque path from the motor to the steering gear output shaft in order to avoid the use of an excessively large motor. Within this scope, the gear stage that comprises the steering gear output shaft or is directly connected to the steering gear output shaft should advantageously have the largest possible reduction ratio. Since the gear stage that comprises the steering gear output shaft or is directly connected to the steering gear output shaft is also located in the torque path from the first steering gear input shaft to the steering gear output shaft, special boundary conditions arise in this torque path regarding the reduction ratio of the gear stage (alone or together with at least one further gear stage) that is connected upstream in terms of drive technology from the gear stage that comprises the steering gear output shaft or is directly connected to the steering gear output shaft. It has been shown that by configuring the gear stage as a helical gear mechanism, the required reduction ratio of this gear stage can be achieved with a very compact design, and at the same time, an arrangement of the first steering gear input shaft relative to the steering gear output shaft that is advantageous with respect to the installation situation and installation space utilization in commercial vehicles can be realized.

[0010] A helical gear mechanism can be understood as a gear comprising two helical gears that mesh directly with each other, in which the rotational axes of the gears are in mutually skew positions. In particular, the rotational axis of one of the gears can lie in one plane, and the rotational axis of the other gear is parallel to the surface normal of that plane. Advantageously, it can be contemplated that L<Dπsinβ holds for both helical gears, where L is the axial length of the gear, D is the root circle diameter of the oblique tooth trace, π is the circular constant, and β is the helix angle.

[0011] In an advantageous embodiment, the rotational axis of the first helical gear lies in a plane that forms an angle in the range of 70 to 110 degrees, in particular 90 degrees, with respect to the rotational axis of the second helical gear. This embodiment particularly advantageously contributes to positioning the first steering gear input shaft and the steering gear output shaft relative to each other in an optimum orientation, achieving particularly excellent adaptability to the installation situation in commercial vehicles and efficient utilization of installation space.

[0012] As already mentioned, the other gear stages may, advantageously, be directly connected to the steering gear output shaft or may be provided with the steering gear output shaft.

[0013] In a particularly advantageous embodiment, the steering system comprises a further gear stage connected downstream of the drive gear stage, configured as a helical gear mechanism. Here, the further gear stage can have a gear ratio towards the high-speed side in the range of 3:1 to 10:1 to achieve the aforementioned reduction ratio of 1:22 to 1:26, preferably 1:24, in the torque path from the first steering gear input shaft to the steering gear output shaft, advantageously in a compact and space-saving overall manner, and the helical gear mechanism has a reduction ratio in the range of 1:1.5 to 1:5.

[0014] Preferably, the other gear stages are connected downstream of further gear stages in terms of drive technology.

[0015] In particularly compact and robust embodiments, one of the helical gears in the helical gear mechanism functions as an intermediate gear, which is a component of a gear stage and also a component of a further gear stage. For this purpose, the intermediate gear may have an additional set of teeth in addition to its oblique teeth.

[0016] Embodiments in which the intermediate gear is configured as an internal gear, and the internal gear has an additional set of teeth, which is an internal set of teeth, are particularly advantageous. The internal set of teeth can be configured as a straight set of teeth or as an oblique set of teeth. Such an embodiment makes it possible to achieve the above-described advantageous gear ratio particularly well with a very compact design. In such an embodiment, to achieve the above-mentioned reduction ratio of 1:22 to 1:26, preferably 1:24, in the torque path from the first steering gear input shaft to the steering gear output shaft in an overall compact and space-saving manner, the further gear stage can have a speed-increasing gear ratio in the range from 5:1 to 10:1, in particular 7.2:1, and the helical gear mechanism has a reduction ratio in the range from 1:2.5 to 1:5, in particular 1:3.7.

[0017] As an alternative to an internal toothing, the intermediate gear can be provided with an external toothing that meshes with the toothing of the eccentric shaft gear, in particular in addition to an external toothing that is part of another gear stage. In such an embodiment, to achieve the above-mentioned reduction ratio of 1:22 to 1:26, preferably 1:24, in the torque path from the first steering gear input shaft to the steering gear output shaft in an overall compact and space-saving manner, the further gear stage can have a speed-increasing gear ratio in the range from 3:1 to 7:1, in particular 4.9:1, and the helical gear mechanism has a reduction ratio in the range from 1:1.5 to 1:4.5, in particular 1:2.6.

[0018] The intermediate gear can advantageously have helical toothing on its outer circumference. Such an embodiment allows the intermediate gear to perform its dual function very easily in a simple manner. Furthermore, this embodiment can be constructed in a particularly compact manner.

[0019] In a particularly advantageous embodiment, the other of the gear stages is formed by a cycloidal gear mechanism, the cycloidal gear mechanism having at least one externally toothed cycloidal disk, the cycloidal disk engaging with roller pins arranged along the circumference, the movement of the cycloidal disk being generated by a plurality of rotationally driven eccentric shafts, the eccentric shafts being arranged offset from the center and each supported so as to be capable of rotating about their own axis.

[0020] The cycloidal gear mechanism can advantageously have a reduction ratio in the range of 1:30 to 1:80, particularly in the range of 1:30 to 1:50, especially 1:40.

[0021] In particular, it is advantageously contemplated that each eccentric shaft comprises an eccentric shaft gear which is a component of a further gear stage. Furthermore, each eccentric shaft gear can be provided with a toothing, in particular an external toothing, which meshes with a further toothing of an intermediate gear. In this way, the further gear stage forms an upstream stage connected immediately upstream of the cycloidal gear mechanism, and the eccentric shaft gear and the intermediate gear are components of this upstream stage.

[0022] In a particularly advantageous embodiment, each eccentric shaft comprises a further eccentric shaft gear. The further eccentric shaft gear can advantageously be a component of a second upstream stage of the cycloidal gear mechanism. In particular, it can be advantageously contemplated that the second upstream stage and the cycloidal gear mechanism together form an RV mechanism.

[0023] The RV mechanism means a gear system including a cycloidal gear mechanism and an upstream stage. The cycloidal gear mechanism includes at least one cycloidal disk comprising cycloidal external toothing, and the cycloidal external toothing meshes with roller pins arranged along a circumference. The movement of the cycloidal disk is generated by a plurality of eccentric shafts, which are each arranged offset from the center and are each supported so as to be rotatable about their own axis. Each eccentric shaft carries a gear having external toothing, and the gear meshes with a centrally arranged drive gear. The gear of the eccentric shaft and the drive gear are components of the upstream stage. That is, the drive gear transmits rotational motion to the gear of the eccentric shaft, whereby the eccentric shaft drives the cycloidal disk to perform oscillating motion, and at that time, the cycloidal disk rolls in the circumferential direction along the circumference of the roller pins.

[0024] In particular, the motor may be advantageously connected directly or indirectly to the cycloidal gear mechanism via a second upstream stage. This upstream stage may advantageously have a reduction ratio in the range of 1:2.5 to 1:5.

[0025] In particularly compact and robust embodiments, the eccentric shaft gears of each eccentric shaft and any further eccentric shaft gears are located on different sides of at least one cycloidal disk. However, it is also entirely possible that the eccentric shaft gears of each eccentric shaft and any further eccentric shaft gears are located on the same side of at least one cycloidal disk.

[0026] In a compact, robust, and reliable embodiment, each further eccentric shaft gear meshes with a centrally located and rotatably supported drive gear. The drive gear and the further eccentric shaft gear may form, or may be at least a component of, a second upstream stage connected immediately upstream of the cycloidal gear mechanism.

[0027] The other gear stages mentioned above can also be formed by a harmonic drive mechanism. Such an embodiment is particularly advantageous because it allows for the realization of a high reduction ratio, for example, 1:240, while eliminating the backlash of the harmonic drive mechanism.

[0028] In an advantageous embodiment of the steering system, an electric motor is connected to a second steering gear input via a power transmission gear system. This allows the motor's rotational speed and torque to be adapted to the requirements of the steering system.

[0029] Embodiments in which the power transmission gear system is configured as a traction means transmission mechanism, or which include a traction means transmission mechanism, are particularly advantageous. For example, traction means transmission mechanisms such as toothed belt or chain transmission mechanisms enable low-noise and low-vibration power transmission. Furthermore, the traction means transmission mechanism enables the positioning of the electric motor relative to the steering gear system, which is particularly advantageous for utilizing available installation space within the vehicle.

[0030] Alternatively, the power transmission gear system may be configured as a spur gear mechanism or may be equipped with a spur gear mechanism. To achieve a favorable gear ratio in a compact design, the spur gear mechanism may advantageously be equipped with three spur gears.

[0031] In another advantageous embodiment, the power transmission gear system is designed as a harmonic drive mechanism, or is intended to incorporate a harmonic drive mechanism. The harmonic drive mechanism also allows for a very compact design and, due to its backlash-free power transmission, provides particularly high steering precision.

[0032] In particular, the steering system can be configured such that, for example, by the special embodiment of the power transmission gear system described above, the motor is offset axially from the second gear stage, and is positioned particularly parallel to the axis and / or parallel to the steering gear output shaft. This arrangement allows for a space-saving design and enables flexible integration of the motor into the vehicle's installation space.

[0033] Alternatively, the steering system can be designed so that the motor is coaxially positioned with the second gear stage. This design ensures direct and low-loss power transmission, thereby improving the system's efficiency. Furthermore, it results in a more compact unit, particularly in the radial direction, which allows for easier assembly and maintenance.

[0034] Preferably, the steering gear device comprises a steering gear device housing, which encloses at least a cycloidal gear mechanism. Particularly advantageous, the steering gear device housing may also be intended to enclose at least a gear stage, in particular all gear stages, and / or at least one of further steering system components. For example, the steering gear device housing may also advantageously enclose a power transmission gear device.

[0035] Preferably, the steering gear device housing comprises a plurality of fixing elements for fixing the steering gear device housing to a higher structure, particularly the vehicle body. The fixing elements of the steering gear device housing can be configured, for example, as through holes or as fixing screw holes for fixing screws.

[0036] In a particularly advantageous embodiment, the steering gear device housing is configured such that it is possible to manufacture a steering system that is mirror-symmetric with respect to a vertical mirror surface, with respect to the arrangement and orientation of at least the first and second steering gear input shafts, the steering gear output shaft, and the fixing elements. Such a steering system offers the possibility of easily realizing a mirror-symmetric steering system using identical parts, which facilitates adaptation to various vehicle types, particularly for left-hand drive and right-hand drive cars, without requiring complex new configurations. This enables efficient production and reduces both development and manufacturing costs.

[0037] Generally, the steering system components of a steering system are configured such that a steering system mirror-symmetric to the steering system described above can be manufactured with respect to the arrangement and orientation of at least the first and second steering gear input shafts, the steering gear output shaft, and the fixing elements, particularly with respect to a vertical mirror surface. A particular advantage of this embodiment is the ability to use identical parts. All steering system components are configured to be used mirror-symmetrically, eliminating the need for different components for left-hand drive and right-hand drive vehicles. This reduces the number of variations, resulting in significant reductions in both production and logistics costs. Furthermore, the use of identical parts allows for economies of scale in manufacturing, further reducing production costs. Assembly is also simplified, as the same assembly groups can be used regardless of the installation direction. At the same time, serviceability is improved as there is no need to store various components for spare parts supply.

[0038] Alternatively, in embodiments including a worm, spindle, and helical gear as components of a gear stage configured, for example, as a worm gear mechanism, spindle gear mechanism, or helical gear mechanism, when the worm, spindle, and helical gear are replaced, respectively, by the same worm, spindle, and helical gear having opposite helical directions, the steering system components can be configured to enable the manufacture of a steering system that is mirror-symmetric with respect to a vertical mirror plane, particularly with respect to the arrangement and orientation of at least the first and second steering gear input shafts, steering gear output shafts, and fixed elements. Such embodiments also have the advantage of using substantially identical parts.

[0039] In a particularly advantageous embodiment, the steering gear device housing includes at least one input shaft bearing housing for a steering gear input shaft bearing, particularly in an opening in the housing wall. A steering gear input shaft bearing can be positioned in the input shaft bearing housing for rotatable support of the steering gear input shaft. This enables stable support of the steering gear input shaft. The steering gear input shaft bearing can be advantageously configured as a rolling bearing, particularly as a ball bearing, as a roller bearing, or as an angular contact roller bearing.

[0040] An embodiment in which the steering gear device housing includes an additional input shaft bearing housing in addition to the input shaft bearing housing, and the additional input shaft bearing housing is arranged in mirror symmetry with respect to the horizontal mirror surface with respect to the first input shaft bearing housing, is particularly advantageous. A steering gear input shaft bearing can be positioned in the input shaft bearing housing to support the steering gear input shaft. This symmetrical design facilitates production and enables cost-effective implementation of left-hand drive and right-hand drive variants with respect to the rotational support of the steering gear input shaft.

[0041] Particularly advantageously, depending on whether the steering system is manufactured for a right-hand drive or left-hand drive vehicle, the steering gear input shaft bearing may be inserted into an input shaft bearing housing, or into a further input shaft bearing housing. Preferably, when the steering gear input shaft bearing is inserted into an input shaft bearing housing, the further input shaft bearing housing is closed off with a cover. Conversely, when the steering gear input shaft bearing is inserted into a further input shaft bearing housing, the input shaft bearing housing is preferably closed with a cover. The cover is preferably configured to be removable without damage, for example, for maintenance purposes.

[0042] Alternatively, and advantageously, to ensure that the steering gear input shaft is reliably rotatably supported, the steering gear input shaft bearing may also be inserted into both the input shaft bearing housing and a further input shaft bearing housing. Depending on whether the steering system is manufactured for a right-hand drive or left-hand drive vehicle, the steering gear input shaft protrudes from the steering gear device housing through an opening in the input shaft bearing housing, or an opening in a further input shaft bearing housing. In this case, the other opening in the input shaft bearing housing is preferably closed with a cover.

[0043] The steering gear device housing can, advantageously, be equipped with an output shaft bearing housing for the steering gear output shaft bearing, thereby enabling precise rotational support of the steering gear output shaft. The steering gear output shaft bearing can be positioned within the output shaft bearing housing.

[0044] An embodiment in which the steering gear device housing includes an additional output shaft bearing housing in addition to the output shaft bearing housing, and the additional output shaft bearing housing is arranged in a mirror-symmetrical manner with respect to the mirror surface with respect to the first output shaft bearing housing, is particularly advantageous. A steering gear output shaft bearing can be positioned in the output shaft bearing housing to support the steering gear output shaft. This symmetrical design facilitates production and enables cost-effective implementation of left-hand drive and right-hand drive variants with respect to the rotational support of the steering gear output shaft.

[0045] Particularly advantageously, depending on whether the steering system is manufactured for a right-hand drive or left-hand drive vehicle, the steering gear output shaft bearing may be inserted into an output shaft bearing housing, or into a further output shaft bearing housing. Preferably, when the steering gear output shaft bearing is inserted into an output shaft bearing housing, the further output shaft bearing housing is closed off with a cover. Conversely, when the steering gear output shaft bearing is inserted into a further output shaft bearing housing, the output shaft bearing housing is preferably closed with a cover. The cover is preferably configured to be removable without damage, for example, for maintenance purposes.

[0046] According to the present invention, a method for manufacturing multiple steering systems is provided, in which the steering system components are provided first, which is particularly advantageous. The steering system components include, in particular, a plurality of identical electric motors, a plurality of steering gear units, and a plurality of steering gear unit housings. Each steering gear unit includes a first steering gear input shaft connectable to a steering shaft, a second steering gear input shaft that is technically connected to or connectable to an electric motor, and a steering gear output shaft, respectively. Each steering gear device housing is provided with fixing elements for fixing the steering gear device housing to a higher structure, particularly the vehicle body, and the steering gear device housing is configured to enable the manufacture of a steering system and a steering system that is mirror-symmetric with respect to a vertical mirror surface, with respect to the arrangement and orientation of at least the first and second steering gear input shafts, the steering gear output shaft, and the fixing elements. Preferably, the steering gear device housing is configured to enable the manufacture of both a steering system for a right-hand drive vehicle and a steering system for a left-hand drive vehicle.

[0047] Embodiments in which steering systems for left-hand drive and right-hand drive vehicles are assembled from completely identical steering system components are particularly advantageous. This leads to a significant reduction in the number of parts and, consequently, cost savings in production and logistics. Furthermore, the standardization of components simplifies warehouse management and reduces the complexity of assembly.

[0048] In a further advantageous embodiment, the steering systems for left-hand drive and right-hand drive vehicles may consist of the same components, except that a worm, spindle, or helical gear having a counter-helical orientation is used. [Effects of the Invention]

[0049] As already mentioned above, advantageously, depending on whether the steering system is manufactured for a right-hand drive or left-hand drive vehicle, the steering gear input shaft bearing may be inserted into an input shaft bearing housing or into a further input shaft bearing housing (arranged mirror-image to the input shaft bearing housing) with respect to the rotational support of the steering gear input shaft.

[0050] Similarly, as already mentioned above, advantageously, depending on whether the steering system is manufactured for a right-hand drive vehicle or a left-hand drive vehicle, the steering gear output shaft bearing may be inserted into an output shaft bearing housing or into a further output shaft bearing housing (arranged mirror-image to the output shaft bearing housing) with respect to the rotational support of the steering gear output shaft.

[0051] Embodiments in which the distance from the plane perpendicular to the steering gear output shaft on which the rotation axis of the first steering gear input shaft is located to the plane on which the outer portion of the steering gear device housing directly surrounding the output shaft bearing housing is located is particularly advantageous, in which case the distance is in the range of 70 mm to 90 mm, or particularly 80 mm. These dimensions achieve a good balance between compactness, structural stability, and efficient use of installation space.

[0052] The steering system can be advantageously designed so that the axes of rotation of the first steering gear input shaft and the steering gear output shaft are torsion relative to each other. This arrangement allows for particularly good use of installation space and integration into the vehicle. In particular, the axes of rotation of the first steering gear input shaft and the steering gear output shaft are further arranged in planes perpendicular to each other, which allows for particularly good use of installation space and integration into a vehicle. Embodiments in which the axes of rotation of the first steering gear input shaft and the steering gear output shaft are located at a distance of 80 mm to 100 mm, particularly 90 mm, are especially advantageous.

[0053] A steering system comprising a steering shaft operably connected to a steering control unit is particularly advantageous, wherein the steering shaft is preferably directly connected to or integrally manufactured with a first steering gear input shaft.

[0054] Furthermore, the steering system according to the present invention or a vehicle equipped with the steering according to the present invention, particularly commercial vehicles, especially trucks or buses, are particularly advantageous.

[0055] The scope of the present invention is schematically shown in the figures as an example, and will be described below with reference to the figures. Here, even in different exemplary embodiments, the same or identical elements are usually denoted by the same reference numerals. [Brief explanation of the drawing]

[0056] [Figure 1] This is a cross-sectional view of an exemplary embodiment of the steering system according to the present invention. [Figure 2] This is a further cross-sectional view of an exemplary embodiment of the steering system according to the present invention. [Figure 3] This is a side view of an exemplary embodiment of the steering system according to the present invention. [Figure 4] This is a perspective view of an exemplary embodiment of the steering system according to the present invention. [Figure 5] A perspective front view of an exemplary embodiment of a steering system according to the present invention, and a further perspective front view of a steering system that is mirror-symmetric to the above steering system with respect to a vertical mirror surface in particular. [Figure 6] A perspective rear view of an exemplary embodiment of a steering system according to the present invention, and a further perspective rear view of a steering system that is mirror-symmetric to the above steering system with respect to a vertical mirror surface in particular. [Figure 7]A side view of an exemplary embodiment of a steering system according to the present invention, and a further side view of a steering system that is mirror-symmetric with respect to the above steering system with respect to a vertical mirror surface in particular. [Figure 8] This is a schematic detail diagram of the helical gear mechanism and RV mechanism of an exemplary embodiment of the steering system according to the present invention. [Figure 9] This is a schematic detail diagram of an exemplary embodiment of a combination of a helical gear mechanism and an RV mechanism for a steering system according to the present invention. [Modes for carrying out the invention]

[0057] Figure 1 shows a cross-sectional view of an exemplary embodiment of the steering system 1 according to the present invention.

[0058] The steering system 1 consists of steering system components. The steering system components include an electric motor 2, a steering gear device 3 which includes a first steering gear input shaft 4 connectable to a steering shaft (not shown), a second steering gear input shaft 5 driven by the electric motor 2, and a steering gear output shaft 6. The steering system components also include a steering gear housing 7, which comprises a plurality of fixing elements 8 for fixing the steering gear housing 7 to a higher structure, particularly the vehicle body. The fixing elements 8 of the steering gear housing 7 can be configured, for example, as through holes or screw holes 9 for fixing screws.

[0059] The steering gear device housing 7 is configured to enable the manufacture of a steering system 11 that is mirror-symmetric to the steering system 1 with respect to the arrangement and orientation of at least the first steering gear input shaft 4 and the second steering gear input shaft 5, the steering gear output shaft 6, and the fixing element 8, particularly with respect to the vertical mirror surface 10, which is shown in Figures 5 to 7 and will be described in more detail below. Specifically, in this exemplary embodiment, the steering system components are configured such that a steering system 11 can be manufactured that is mirror-symmetric with respect to the steering system 1 with respect to the mirror surface 10, with respect to the arrangement and orientation of the first steering gear input shaft 4 and the second steering gear input shaft 5, the steering gear output shaft 6, and the fixed element 8, when the helical gears 17 and 18 of the helical gear mechanism 19 enclosed by the steering gear device housing 7 are replaced by identical helical gears having opposite helical directions.

[0060] Motor 2 is connected to the second steering gear input shaft 5 via a power transmission gear unit 12. The power transmission gear unit 12 is configured as a spur gear mechanism and includes a first spur gear 13, which is directly connected to the power output shaft 14 of the motor 2 in a manner that prevents relative rotation. The power transmission gear unit 12 further includes a rotatably supported second spur gear 15, the teeth of which mesh with the teeth of the first spur gear 13. The power transmission gear unit 12 further includes a third spur gear 16, which is directly connected to the second steering gear input shaft 5 in a manner that prevents relative rotation.

[0061] The torque path from the first steering gear input shaft 4 to the steering gear output shaft 6 comprises multiple gear stages that are technically connected in series. One gear stage is configured as a helical gear mechanism 19, and other gear stages connected downstream of the gear stage configured as the helical gear mechanism 19 are configured as an RV mechanism 20.

[0062] The RV mechanism 20 comprises a cycloidal gear mechanism 21 and an upstream stage 22. The cycloidal gear mechanism 21 is technically connected downstream of the motor 2 via a power transmission gear unit 12 and an upstream stage 22. The cycloidal gear mechanism 21 includes two cycloidal discs 23 and 24, each having a cycloidal external gear row, which meshes with roller pins 25 arranged along the circumference. The movement of the cycloidal discs 23 and 24 is generated by a plurality of eccentric shafts 26, each centered off-center and supported by rolling bearings 27 to rotate relative to the cycloidal discs 23 and 24.

[0063] Each eccentric shaft 26 comprises an eccentric shaft gear 28 and a further eccentric shaft gear 29. The eccentric shaft gear 28 and the further eccentric shaft gear 29 of each eccentric shaft 26 are positioned on opposite sides of the two cycloidal discs 27.

[0064] The further eccentric shaft gear 29 is part of the upstream stage 22. The centrally located second steering gear input shaft 5 has an external gear row 30 that meshes with the external gear row of the further eccentric shaft gear 29. To that extent, the second steering gear input shaft 5 functions as the drive gear 57 of the upstream stage 22, transmitting its rotational motion to the further eccentric shaft gear 29. As a result, the eccentric shaft 26 drives the cycloidal disc 27 to oscillate, causing the cycloidal disc 27 to roll circumferentially along the circumference of the roller pin 25. In addition to its own rotation, the eccentric shaft 26 rotates together with the cycloidal disc 27 around the rotational axis 31 of the RV mechanism. Each eccentric shaft 26 is connected to the steering gear output shaft 6 via further rolling bearings 32, and the rotational motion of the cycloidal disc 27 around the rotational axis 31 is transmitted to the steering gear output shaft 6 via the eccentric shaft 26.

[0065] Furthermore, each eccentric shaft 26 is technically connected to the first steering gear input shaft 4 via a helical gear mechanism 19. The helical gear mechanism 19 comprises a first helical gear 17, which is coaxially positioned with the steering gear input shaft 4 and indirectly connected to the steering gear input shaft 4 in a manner that prevents relative rotation. The helical gear mechanism 19 further comprises a second helical gear 18, whose oblique external teeth mesh with the oblique external teeth of the first helical gear 17. The axes of rotation of the helical gears 17 and 18 are positioned in a twisted position relative to each other, and the second helical gear 18 rotates around the rotational axis 31 of the cycloidal gear mechanism 20.

[0066] The second helical gear 18 is ring-shaped and has an oblique external tooth row on its outer circumference, which meshes with the oblique external tooth row of the first helical gear 17. The second helical gear 18 has an internal tooth row 54 along its inner circumference, which meshes with the external tooth row 55 of a further eccentric shaft gear 29. The second helical gear 18 is rotatably supported on the steering gear output shaft 6 by a plurality of rolling bearings 33.

[0067] To that extent, the torque path from the first steering gear input shaft 4 to the steering gear output shaft 6 comprises several gear stages that are technically connected in series. As already mentioned, one of these gear stages is formed by a helical gear mechanism 19. Another gear stage of these is formed by the meshing of a second helical gear 18, preferably a linear internal tooth row 54, with the external tooth row 55 of an eccentric shaft gear 28. The other gear stage of these is formed by a cycloidal gear mechanism 21. The helical gear 18 forms an intermediate gear 56, which is a component of two gear stages that are technically connected in series.

[0068] The steering gear device housing 7 includes an output shaft bearing housing 34, and a steering gear output shaft bearing 35 and a seal 53 are arranged in the output shaft bearing housing 34 to rotatably support the steering gear output shaft 6.

[0069] The distance 36 from the plane 37 perpendicular to the steering gear output shaft 6, where the rotation axis of the first steering gear input shaft 4 is located, to the plane 38 where the outer portion of the steering gear device housing 7 that directly surrounds the output shaft bearing housing 34 is located, is in the range of 70 mm to 90 mm, and preferably 80 mm.

[0070] The axes of rotation of the first steering gear input shaft 4 and the steering gear output shaft 6 are positioned in planes perpendicular to each other, and these planes have a distance of 80 mm to 100 mm, especially 90 mm, from each other 39.

[0071] Figure 2 shows a further cross-sectional view of an exemplary embodiment of the steering system 1 according to the present invention.

[0072] As can be seen in Figure 2, the steering gear input shaft 4 has an input portion 40 configured as a solid shaft, a central portion 41 configured as a solid shaft, and a hollow shaft portion 42, the hollow shaft portion 42 forming a first helical gear 17 in part. The central portion 41 is directly connected at one end to the input portion 40 in a way that prevents relative rotation, and at the other end to the hollow shaft portion 42 in a way that prevents relative rotation, and the hollow shaft portion 42 surrounds the central portion 41 and a part of the input portion 40.

[0073] The steering system 1 includes a first rotation angle sensor 43, which detects the rotational position and rotational speed of the input portion 40 of the first steering gear input shaft 4, as well as the steering speed. The steering system 1 further includes a second rotation angle sensor 44, which detects the rotational position of the portion of the hollow shaft portion 42 of the first steering gear input shaft 4 that surrounds the input portion 40. The first rotation angle sensor 43 comprises a first rotary encoder sensor 60 and a first coding element 61, the first coding element 61 interacting non-contact with the first rotary encoder sensor 60, for example, in the form of a graduated disk, a toothed ring, or a magnetic wheel. The second rotation angle sensor 44 comprises a second rotary encoder sensor 62 and a second coding element 63, the second coding element 63 interacting non-contact with the second rotary encoder sensor 62, for example in the form of a graduated disk, a toothed ring, or a magnetic wheel. The first rotary encoder sensor 60 and the second rotary encoder sensor 62 can, advantageously, be arranged together on the same support and / or within the same sensor housing. In the figure, the first rotary encoder sensor 60 and the second rotary encoder sensor 62 are shown together only schematically as a hatched closed polygon.

[0074] The measurement signals from the first rotary encoder sensor 60 and the second rotary encoder sensor 62 are transmitted to a control device (not shown), which controls the motor 2 taking the measurement signals into consideration. Here, the control device can infer the current torque applied to the first steering gear input shaft 4 by the steering control unit (not shown) from the difference between the rotation angle of the first rotary encoder sensor 60 and the rotation angle of the second rotary encoder sensor 62. This is possible because the input portion 40 where the first coding element 61 is located and the end of the hollow shaft portion 42 where the second coding element 63 is located, which is directly connected to the central portion 41, both belong to the first steering gear input shaft 4, but are technically located before and after the first helical gear 17 of the helical gear mechanism 19. Therefore, when torque is applied, they rotate relative to each other, particularly due to the twisting of the relatively thin central portion 41, and the greater the torque applied to the first steering gear input shaft 4 by the steering control unit (not shown), the greater the difference in rotational angle.

[0075] To that extent, it may be advantageous to configure the control device to control the motor 2 in accordance with the difference in rotation angle between at least the first rotary encoder sensor 60 and the second rotary encoder sensor 62.

[0076] The steering gear device housing 7 comprises an input shaft bearing housing 45 and a further input shaft bearing housing 46, the further input shaft bearing housing 46 being arranged in mirror symmetry with respect to the horizontal mirror plane of the first input shaft bearing housing. A steering gear input shaft bearing module 47 is arranged in the input shaft bearing housing 45, and the steering gear input shaft bearing module 47 includes a first rolling bearing 58 and a second rolling bearing 59. The input portion 40 is rotatably supported by the first rolling bearing 58. The end of the hollow shaft portion 42 surrounding the input portion 40 is rotatably supported by the second rolling bearing 59.

[0077] Further input shaft bearing housings 46 house additional steering gear input shaft bearing modules 48, each equipped with rolling bearings 64. The ends of the hollow shaft portions 42, which are directly connected to the central portion 41, are rotatably supported by the rolling bearings 64.

[0078] The steering gear input shaft bearing module 47 and the further steering gear input shaft bearing module 48 play a particular role in reliably supporting the first steering gear input shaft 4 in a rotatable manner, and the first rotary encoder sensor 60 and the second rotary encoder sensor 62 are spatially integrated within the steering gear input shaft bearing module 47. The steering gear input shaft 4 protrudes outward through the opening of the input shaft bearing housing 45.

[0079] In contrast, if, for example, a mirror-symmetric steering system 11 for a right-hand drive vehicle is manufactured instead of a steering system 1 which may be configured for a left-hand drive vehicle, the steering gear housing 7 can be used such that the steering gear input shaft 4 protrudes out of the steering gear housing 7 through the opening of a further input shaft bearing housing 46, as shown in Figures 5 to 7.

[0080] Figure 3 shows the steering system 1 in a side view, and Figure 4 shows the steering system 1 in a perspective view. As can be seen from both figures, there are a total of five fixing elements 8, and the fixing elements 8 can be configured as screw holes.

[0081] There are two upper fixing elements 49, two lower fixing elements 50, and one central fixing element 51. The fixing elements 8 are arranged symmetrically to one another with respect to the plane 52 on which the rotation axis 31 and the central fixing element 51 are located.

[0082] As shown in Figures 5 to 7, the steering gear device housing 7 is configured to enable the manufacture of a steering system 11 that is mirror-symmetric to the steering system 1 with respect to the arrangement and orientation of the first steering gear input shaft 4, the second steering gear input shaft 5, the steering gear output shaft 6, and the fixing element 8, particularly with respect to the vertical mirror surface 10. In steering system 1, two upper fixing elements 49 are positioned at the top, whereas in the mirror-symmetric steering system 11, the two upper fixing elements 49 are positioned at the bottom. In steering system 1, two lower fixing elements 50 are positioned at the bottom, whereas in the mirror-symmetric steering system 11, the two lower fixing elements 49 are positioned at the top.

[0083] In steering system 1, the steering gear input shaft 4 protrudes outward through the opening of the input shaft bearing housing 45, whereas in the mirror-symmetric steering system 11, the steering gear input shaft 4 protrudes outward through the opening of an additional input shaft bearing housing 46.

[0084] Figure 8 shows schematic detail views of the helical gear mechanism 19 and RV mechanism 20 of an exemplary embodiment of the steering system according to the present invention, where the oblique tooth arrangements of the first helical gear 17 and the second helical gear 18 are not shown for clarity.

[0085] Figure 9 shows a schematic detail of an exemplary embodiment of a combination of a helical gear mechanism 19 and an RV mechanism 20 for a steering system according to the present invention.

[0086] Unlike the combination of the helical gear mechanism 19 and the RV mechanism 20 shown in Figure 8, the eccentric shaft gear 28 of each eccentric shaft and the further eccentric shaft gear are located on the same side of the two cycloidal discs 27. [Explanation of Symbols]

[0087] 1. Steering System 2 motors 3. Steering gear system 4. First steering gear input shaft 5. Second steering gear input shaft 6. Steering gear output shaft 7. Steering gear device housing 8 fixed elements 9 screw holes 10 Mirror surface 11. Mirror-symmetry steering system 12 Power transmission gear system 13 First spur gear 14 Power output shaft 15. Second spur gear 16. Third spur gear 17. First helical gear 18. Second helical gear 19. Helical gear mechanism 20 RV Mechanism 21 Cycloidal gear mechanism 22 Upstream stage 23 Cycloidal discs 24 Cycloidal Discs 25 Roller pins 26 Eccentric shaft 27 Rolling bearings 28 Eccentric shaft gear 29 Further eccentric shaft gears 30 External dentition 31 Rotational center axis 32 Further rolling bearings 33 Rolling bearings 34 Output shaft bearing housing 35 Steering gear output shaft bearing 36 distance 37 plane 38 plane 39 distance 40 Input section 41 Central part 42 Hollow shaft section 43. First rotation angle sensor 44. Second rotation angle sensor 45 Input shaft bearing housing 46 Further input shaft bearing housing 47 Steering gear input shaft bearing 48 Further steering gear input shaft bearings 49 Upper fixed element 50 Lower fixed element 51 Central fixed element 52 plane 53 Seals 54 Inner teeth 55 External dentition 56 Intermediate gear 57 Drive gear 58 First rolling bearing 59 Second rolling bearing 60 First rotary encoder sensor 61 Second rotary encoder sensor 62 First coding element 63 Second coding element 64 Rolling bearings

Claims

1. a. Electric motor and, b. Steering gear device and A steering system comprising, the steering gear device, i. A steering gear input shaft connectable to the steering shaft, a second steering gear input shaft that is technically connected to the electric motor, and a steering gear output shaft, ii. The torque path from the first steering gear input shaft to the steering gear output shaft comprises at least two drive-technically series-connected gear stages. In the steering system, One of the gear stages is configured as a helical gear mechanism. The helical gear mechanism comprises a first helical gear, A steering system characterized in that the first helical gear meshes with a second helical gear.

2. The steering system according to claim 1, characterized in that the axis of rotation of the first helical gear lies in a plane having an angle of 70 to 110 degrees, particularly 90 degrees, with respect to the axis of rotation of the second helical gear.

3. The steering system according to claim 1 or 2, characterized in that the other gears among the gears are directly connected to the steering gear output shaft, or the system includes the steering gear output shaft.

4. The steering system further includes additional gear stages, The steering system according to any one of claims 1 to 3, characterized in that the further gear stage is connected downstream of the gear stage, which is configured as a helical gear mechanism in terms of drive technology.

5. The steering system according to claim 4, characterized in that the other gears among the gears are connected downstream of the further gears in terms of drive technology.

6. One of the helical gears of the helical gear mechanism functions as an intermediate gear. The steering system according to claim 4 or 5, characterized in that the intermediate gear is a component of the gear stage and also a component of the further gear stage.

7. The steering system according to claim 6, characterized in that the intermediate gear has a further set of teeth in addition to its diagonal set of teeth.

8. The aforementioned intermediate gear is configured as an internal gear, The steering system according to claim 7, characterized in that the internal gear comprises, in particular, a linear internal gear as a further tooth arrangement.

9. The steering system according to claim 7 or 8, characterized in that the intermediate gear has an oblique row of teeth on its outer circumference.

10. The other gear stages among the aforementioned gear stages are formed by a cycloidal gear mechanism, The cycloidal gear mechanism comprises at least one cycloidal disc with external teeth, The cycloidal disk engages with roller pins arranged along its circumference, The motion of the cycloidal disk is generated by a plurality of eccentric shafts that are driven to rotate, The steering system according to any one of claims 1 to 9, characterized in that the eccentric shafts are arranged with their centers offset and each is supported so as to be able to rotate.

11. Each eccentric shaft has an eccentric shaft gear, The steering system according to claim 10, characterized in that the eccentric shaft gear is a component of the further gear stage.

12. Each eccentric shaft gear has a toothed row, particularly an external toothed row, The steering system according to claim 11 and any one of claims 6 to 10, characterized in that the gear row meshes with the further gear row of the intermediate gear.

13. The steering system according to any one of claims 10 to 12, characterized in that each eccentric shaft comprises a further eccentric shaft gear.

14. The steering system according to claim 13, characterized in that the eccentric shaft gear and the further eccentric shaft gear of each eccentric shaft are arranged on different sides of the at least one cycloidal disc.

15. The steering system according to claim 13 or 14, characterized in that each further eccentric shaft gear meshes with a drive gear that is centrally located and rotatably supported.

16. The steering system according to any one of claims 1 to 9, characterized in that the other gear stages among the gear stages are formed by a harmonic drive gear mechanism.

17. The steering system according to any one of claims 1 to 16, characterized in that the electric motor is connected to a second steering gear input via a power transmission gear device.

18. The steering system according to claim 17, characterized in that the power transmission gear device is configured as a traction means transmission mechanism, or comprises a traction means transmission mechanism.

19. The steering system according to claim 18, characterized in that the power transmission gear device is configured as a spur gear mechanism or comprises a spur gear mechanism.

20. The steering system according to claim 18, characterized in that the power transmission gear device is configured as a harmonic drive gear mechanism or comprises a harmonic drive gear mechanism.

21. The steering system according to any one of claims 1 to 20, characterized in that the motor is axially offset with respect to the steering gear output shaft and / or the other gear stages, and is arranged particularly parallel to the axis.

22. The steering system according to any one of claims 1 to 21, characterized in that the motor is arranged coaxially with the steering gear output shaft and / or the other gear stages.

23. The steering gear device comprises a steering gear device housing, The steering system according to any one of claims 1 to 22, characterized in that the steering gear device housing surrounds at least the gear stages, in particular all of the gear stages, and / or the power transmission gear device, which are technically connected in series.

24. The steering system according to claim 23, characterized in that the steering gear device housing comprises a structure above the steering gear device housing, particularly a fixing element for fixing it to the vehicle body.

25. The steering system according to claim 23 or 24, characterized in that the steering gear device housing is configured such that a steering system can be manufactured that is mirror-symmetric with respect to the steering system with respect to at least the arrangement and orientation of the first and second steering gear input shafts, the steering gear output shaft, and the fixed elements, particularly with respect to a vertical mirror surface.

26. a. The steering system components of the steering system are configured such that it is possible to manufacture a steering system that is mirror-symmetric with respect to the steering system with respect to at least the arrangement and orientation of the first and second steering gear input shafts, the steering gear output shaft, and the fixing elements, particularly with respect to a vertical mirror surface, or b. The steering system according to any one of claims 1 to 25, characterized in that when each helical gear is replaced by an identical helical gear having opposite helical directions, the steering system components of the steering system are configured such that a steering system can be manufactured that is mirror-symmetric with the steering system with respect to at least the arrangement and orientation of the first and second steering gear input shafts, the steering gear output shaft, and the fixed elements, particularly with respect to a perpendicular mirror surface.

27. The steering system according to any one of claims 22 to 26, characterized in that the steering gear device housing is provided with at least one input shaft bearing housing for a steering gear input shaft bearing, particularly in an opening in the housing wall.

28. The steering system according to claim 27, characterized in that the steering gear input shaft bearing is arranged in the input shaft bearing housing.

29. The steering gear device housing is provided with at least one additional input shaft bearing housing for a steering gear input shaft bearing, particularly in a further opening in the housing wall. The steering system according to claim 27 or 28, characterized in that the further input shaft bearing housing is configured and arranged in mirror symmetry with respect to the mirror surface, particularly with respect to the horizontal mirror surface, with respect to the input shaft bearing housing.

30. The steering system according to claim 29, characterized in that a steering gear input shaft bearing is arranged in the further housing.

31. The steering system according to any one of claims 22 to 30, characterized in that the steering gear device housing is provided with at least one output shaft bearing housing for a steering gear output shaft bearing, particularly in an opening in the housing wall.

32. The steering system according to claim 31, characterized in that a steering gear output shaft bearing is arranged in the output shaft bearing housing.

33. The steering system according to claim 31 or 32, characterized in that the distance from a plane perpendicular to the steering gear output shaft on which the rotation axis of the first steering gear input shaft is located to a plane on which the outer portion of the steering gear device housing that directly surrounds the output shaft bearing housing is located is in the range of 70 mm to 90 mm, and particularly 80 mm.

34. The steering gear device housing is further provided with at least one additional output shaft bearing housing for a steering gear output shaft bearing in a further opening in the housing wall, The steering system according to any one of claims 22 to 33, characterized in that the further output shaft bearing housing is configured and arranged in mirror symmetric with respect to the mirror surface, particularly with respect to the horizontal mirror surface, with respect to the output shaft bearing housing.

35. The steering system according to claim 34, characterized in that a steering gear output shaft bearing is arranged in the further output shaft bearing housing.

36. The steering system according to claim 34 or 35, characterized in that the distance from a plane perpendicular to the steering gear output shaft on which the rotation axis of the first steering gear input shaft is located to a plane on which the outer portion of the steering gear device housing that directly surrounds the further output shaft bearing housing is located is in the range of 70 mm to 90 mm, and particularly 80 mm.

37. The steering system according to any one of claims 1 to 36, characterized in that the rotation axes of the first steering gear input shaft and the steering gear output shaft are in a torsional position relative to each other.

38. The steering system according to any one of claims 1 to 37, characterized in that the rotation axes of the steering gear input shaft and the steering gear output shaft are arranged in a plane perpendicular to each other.

39. The steering system according to any one of claims 1 to 38, characterized in that the rotation axes of the first steering gear input shaft and the steering gear output shaft are within the range of 80 mm to 100 mm, particularly 90 mm.

40. A steering system according to any one of claims 1 to 39, A steering system comprising a steering shaft that is operationally connected to the steering control unit and linked to a first steering gear input shaft.

41. A vehicle, particularly a commercial vehicle, especially a truck or bus, comprising a steering system according to any one of claims 1 to 39, or a steering system according to claim 40.

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