Steering system

Abstract

The invention relates to a steering system comprising an electric motor and a steering gear device having a first steering gear input shaft couplable to a steering shaft, a second steering gear input shaft drivably coupled to the electric motor by a transmission device, and a steering gear output shaft. The steering system is characterized in that it comprises either i) a cycloidal gear mechanism and a strain wave gear mechanism; or ii) two strain wave gear mechanisms.

Description

Technical Field

[0001] The present invention relates to a steering system comprising an electric motor and a steering device, the steering device comprising a first steering input shaft coupled to a steering shaft, a second steering input shaft drivably coupled to the electric motor via a transmission device, and a steering output shaft. Background Technology

[0002] DE202014101670U1 discloses a power steering system. This power steering system has a steering wheel shaft on which a first worm and a worm wheel are coaxially arranged. The power steering system also has a power assist shaft on which a second worm is coaxially arranged, meshing with the worm wheel. The power steering system further has a segmented shaft with a gear segment that meshes with the first worm.

[0003] DE102019127965A1 discloses a steering gear for an electromechanical steering system in a vehicle. The steering gear includes an input shaft coupled to or to a steering column of the steering system, a segmented shaft coupled to or to a steering arm of the steering system, an angle gear mechanism, a servo gear mechanism, and an electric motor for driving the servo gear mechanism. The angle gear mechanism is configured as a bevel gear mechanism. The input shaft and the electric motor are connected to the servo gear mechanism. The servo gear mechanism is connected to the angle gear mechanism. The angle gear mechanism is connected to the segmented shaft. The angle gear mechanism is configured to transmit torque from the servo gear mechanism to the segmented shaft via two transmission paths.

[0004] DE10234596B3 discloses a power steering system for non-rail vehicles, which is configured as a recirculating ball steering system. To improve the variability of the recirculating ball steering system, a servo motor is arranged at the steering input end. This servo motor is configured as an electric motor to reduce the steering effort.

[0005] DE102015217045A1 discloses a commercial vehicle steering system comprising a steering gear for transmitting manual torque applied to a steering wheel to a steering arm. The steering gear has an electric motor for providing auxiliary torque for assisted steering, wherein the steering assistance is provided entirely electrically throughout the entire operating range of the steering system. The steering gear also has an input shaft and an output shaft, whose rotation axes are intersected. The steering gear further has a first gear assembly coupling the input shaft and the output shaft, and a second gear assembly with the electric motor connected to the input side of the second gear assembly. The second gear assembly is coupled to the output side of the output shaft, and the reduction gear stage of the second gear assembly is arranged coaxially with the output shaft. Summary of the Invention

[0006] The problem the invention aims to solve

[0007] The purpose of this invention is to provide a steering system of the type described above, which can provide particularly high steering accuracy and load capacity.

[0008] The object of the present invention is to provide a steering system of the type described above, which can provide particularly high steering accuracy and load capacity.

[0009] Solution for solving the problem

[0010] This objective can be achieved by a steering system characterized by comprising:

[0011] i. A cycloidal gear mechanism and a strain wave gear mechanism, or

[0012] ii. Two strain wave gear mechanisms.

[0013] In the steering gear and transmission devices of the steering system according to the invention, the combination of a strain wave gear mechanism with a cycloidal gear mechanism or another strain wave gear mechanism has many synergistic advantages in terms of accuracy, efficiency, load capacity and durability.

[0014] According to the present invention, it has been recognized that a reduction ratio between 1:22 and 1:26, preferably 1:24, is advantageous from a first steering input shaft connected to the steering handle of a commercial vehicle in a non-rotatable manner and with neither excessive nor insufficient deceleration, to the steering output shaft. This ratio between the steering angle on the steering wheel and the steering motion at the wheels conforms to what the driver is typically accustomed to. Meanwhile, regarding the coupling of the motor, it should be noted that since a very large torque, such as 8,000 Nm, is required on the steering output shaft, a very large reduction ratio, such as between 1:900 and 1:1,500, particularly 1:1,000, must be achieved on the torque path from the motor to the steering output shaft to avoid using an excessively large motor.

[0015] In this sense, a gear stage having a steering output shaft or directly coupled to it must advantageously have the largest possible reduction ratio. Since a gear stage having a steering output shaft or directly coupled to it is also on the torque path from the first steering input shaft to the steering output shaft, certain special boundary conditions arise for the reduction ratio of that gear stage (alone or together with at least one other gear stage) that is drivably upstream of the gear stage on this torque path.

[0016] The combination of cycloidal gear mechanisms and strain wave gear mechanisms, or the use of two strain wave gear mechanisms, can achieve these high reduction ratios in a compact manner, which is highly advantageous for applications in commercial vehicles. The steering system according to the invention enables a compact design while still achieving the aforementioned high reduction ratios. Other types of transmissions, such as planetary gear transmissions or spur gear transmissions, require multi-stage or large-scale designs to achieve such high reduction ratios, while the various combinations of strain wave gear mechanisms and cycloidal gear mechanisms according to the invention can be integrated into the steering system in a space-saving manner. This is particularly advantageous for commercial vehicles, as the installation space for the steering system is limited, and the compact design does not impose unnecessary restrictions on the vehicle structure. The combination of cycloidal gear mechanisms and strain wave gear mechanisms, or the application of two strain wave gear mechanisms in the steering system according to the invention, features high torque, small size, high precision, and low mechanical loss.

[0017] In an advantageous embodiment, both the steering gear assembly and the transmission assembly, whether or not they include a further gearbox, each comprise a cycloidal gear mechanism or a strain wave gear mechanism. A particular advantage of this embodiment is that the aforementioned high reduction ratio can be achieved in a compact manner, both in the torque path from the motor to the steering gear output shaft and in the torque path from the first steering gear output shaft to the steering gear output shaft.

[0018] The steering system can be advantageously configured such that the torque path from the first steering input shaft to the steering output shaft has at least two drivably connected gear stages. This allows for the reduction ratio to be achieved in a compact structure, and enables the positioning and arrangement of the first steering input shaft relative to the steering output shaft, which is advantageous for implementation in commercial vehicles, as will be described in detail below.

[0019] In a particularly advantageous embodiment, the first gear stage is configured as a bevel gear mechanism, a worm gear mechanism, a spindle gear mechanism, a crossed helical gear mechanism or a strain wave gear mechanism, and the second gear stage, which is drivably disposed downstream of said first gear stage, is configured as a strain wave gear mechanism or a cycloidal gear mechanism. The combination of different gear technologies allows the respective advantages to be optimally utilized. For example, bevel gear mechanisms, worm gear mechanisms and crossed helical gear mechanisms can advantageously achieve an angular change in torque transmission, which facilitates integration into different vehicle structures. The use of a crossed helical gear mechanism is particularly advantageous, because it can achieve the reduction ratio required for the first gear stage with a very compact design, and at the same time, can achieve the arrangement of the first steering gear input shaft relative to the steering gear output shaft, which arrangement is advantageous in terms of installation conditions and utilization of installation space for commercial vehicles. In an advantageous embodiment, the rotation axis of the first helical gear of said crossed helical gear mechanism lies in a plane that forms an angle between 70 degrees and 110 degrees, in particular 90 degrees, with the rotation axis of the second helical gear of said crossed helical gear mechanism. In a particularly advantageous manner, this embodiment enables the first steering gear input shaft and the steering gear output shaft to be positioned with an optimal alignment relative to each other, so as to achieve particularly good adaptation to installation conditions in commercial vehicles and effectively utilize installation space. The combination of the above options for the first gear stage with the strain wave gear mechanism or cycloidal gear mechanism drivably disposed downstream thereof ensures that the final torque transmission exhibits a high reduction ratio and extremely small backlash.

[0020] A crossed helical gear mechanism is understood as a gear mechanism having two helical gears, which are in direct meshing engagement with each other and whose rotation axes are staggered relative to each other. In particular, the rotation axis of one of the gears may lie in a plane whose surface normal is parallel to the rotation axis of the other gear. It can be advantageously provided that the following applies to both helical gears: L<Dπsinβ, where L is the axial length of the gear, D is the root diameter of the helical tooth portion, π is the mathematical constant, and β is the helix angle.

[0021] Preferably, said steering gear device housing has a fixing element for fixing said steering gear housing to an upper structure, in particular to a vehicle body. For example, said fixing element of said steering gear device housing can be configured as an opening or a threaded hole for a fixing screw.

[0022] With this housing, a steering system that is mirror-symmetrical to said steering system with respect to a mirror surface, in particular a vertical mirror surface, can be manufactured at least in terms of the arrangement and orientation of said first and second steering gear input shafts, said steering gear output shaft and said fixing element.

[0023] In a particularly advantageous embodiment, the steering gear housing is configured such that a steering system can be manufactured that is mirror-symmetrical to the steering system with respect to a mirror surface, particularly a vertical mirror surface, at least in terms of the arrangement and orientation of the first and second steering input shafts, the steering output shaft, and the fixed elements. This type of steering system makes it easy to achieve a mirror-symmetrical steering system using the same parts, thereby simplifying adaptation to different vehicle variants, particularly left-hand drive and right-hand drive vehicles, without requiring costly redesigns. This results in higher production efficiency, reducing both development and manufacturing costs.

[0024] In general, the steering system components can be advantageously configured such that a steering system can be manufactured that is mirror-symmetrical to the steering system with respect to a mirror surface, particularly a vertical mirror surface, at least in terms of the arrangement and orientation of the first and second steering input shafts, the steering output shaft, and the fixed elements. A particular advantage of this embodiment is the use of identical parts. Since all steering system components are designed to be used in a mirror-symmetrical manner, left-hand drive and right-hand drive vehicles do not need to use different components. This reduces the number of variations, thereby significantly reducing production and logistical costs. Using identical parts also allows for economies of scale in production, further reducing manufacturing costs. Assembly is also simplified because the same components can be used regardless of the installation direction. Simultaneously, product maintainability is improved because the variety of spare parts required for inventory is reduced.

[0025] Optionally, in an embodiment including worm gears, spindles, and / or helical gears, for example including components as gear stages configured as worm gear mechanisms, spindle gear mechanisms, or crossed-axis helical gear mechanisms, the steering system components can be configured such that when all worm gears, spindles, and helical gears are replaced by identical components having opposite helical directions, a steering system can be manufactured that is mirror-symmetrical to the steering system at least in terms of the arrangement and orientation of the first and second steering input shafts, the steering output shaft, and the fixed elements, relative to a mirror surface, particularly a vertical mirror surface. This embodiment also provides the significant advantage of using identical parts.

[0026] Whether it is necessary to replace the worm, spindle, and helical gear with the same gears having opposite helical directions depends on the steering system's layout and the rest of the integration scheme, and how the remaining steering elements are configured in right-hand drive and left-hand drive vehicles.

[0027] A particularly advantageous embodiment specifies that the steering gear housing, particularly at the opening in its housing wall, has at least one input shaft bearing housing for a steering input shaft bearing. A steering input shaft bearing can be arranged in the input shaft bearing housing to rotatably mount the steering input shaft. This allows for stable mounting of the steering input shaft. The steering input shaft bearing can advantageously be configured as a rolling bearing, particularly a ball bearing, or a roller bearing, or an angular contact roller bearing.

[0028] In a particularly advantageous embodiment, in addition to the input shaft bearing housing, the steering gear housing also has another input shaft bearing housing, which is arranged symmetrically with respect to a horizontal mirror surface to the first input shaft bearing housing. A steering input shaft bearing for supporting the steering input shaft can be arranged in this input shaft bearing housing. This symmetrical design facilitates production and enables cost-effective implementation of left-hand drive and right-hand drive vehicle variants regarding the slewing bearing of the steering input shaft.

[0029] In particular, it can be advantageously specified that, depending on whether the steering system is manufactured for a right-hand drive vehicle or a left-hand drive vehicle, the steering input shaft bearing is embedded in the input shaft bearing housing or in the additional input shaft bearing housing. Preferably, when the steering input shaft bearing is embedded in the input shaft bearing housing, the additional input shaft bearing housing is sealed with a cover. Conversely, when the steering input shaft bearing is embedded in the additional input shaft bearing housing, the input shaft bearing housing is preferably sealed with a cover. The cover is preferably configured to be removable without damage for, for example, maintenance.

[0030] Optionally, and potentially advantageously, a steering input shaft bearing is provided in both the input shaft bearing housing and the additional input shaft bearing housing to securely support the rotation of the first steering input shaft. Then, depending on whether the steering system is intended for a right-hand drive vehicle or a left-hand drive vehicle, the steering input shaft extends from the steering unit housing through the opening in either the input shaft bearing housing or the opening in the other input shaft bearing housing. The opening in the other input shaft bearing housing is preferably closed with a cover.

[0031] The steering gear housing may advantageously include an output shaft bearing housing for the steering gear output shaft bearing, thereby achieving precise rotational support for the steering gear output shaft. A steering gear output shaft bearing may be arranged within the output shaft bearing housing.

[0032] In a particularly advantageous embodiment, in addition to the output shaft bearing housing, the steering gear housing also has another output shaft bearing housing, which is arranged symmetrically with respect to a mirror surface to the first output shaft bearing housing. A steering output shaft bearing for supporting the steering output shaft can be arranged in the output shaft bearing housing. This symmetrical design facilitates production and enables cost-effective implementation of left-hand drive and right-hand drive vehicle variants regarding the slewing bearing of the steering output shaft.

[0033] In particular, it can be advantageously specified that, depending on whether the steering system is to be manufactured for a right-hand drive vehicle or a left-hand drive vehicle, the steering output shaft bearing is embedded in the output shaft bearing housing or in the additional output shaft bearing housing. Preferably, when the steering output shaft bearing is embedded in the output shaft bearing housing, the additional output shaft bearing housing is sealed with a cover. Conversely, when the steering output shaft bearing is embedded in the additional output shaft bearing housing, the output shaft bearing housing is preferably sealed with a cover. The cover is preferably configured to be removable without damage for, for example, maintenance.

[0034] A method for manufacturing multiple steering systems offers significant advantages, wherein the method first provides steering system components. These components include, in particular, multiple identical electric motors, multiple steering gear units, and multiple steering gear unit housings. Each steering gear unit includes a first steering input shaft coupled to a steering axis, a second steering input shaft with or coupled to the electric motor for drivable coupling, and a steering output shaft. Each steering gear unit housing has fixing elements for securing the housing to a higher-level structure, particularly to a vehicle body, wherein the housings are configured such that a mirror-symmetric steering system can be produced, at least in terms of the arrangement and alignment of the first and second steering input shafts, the steering output shaft, and the fixing elements. Preferably, the steering gear housings are configured to be usable for producing steering systems for both right-hand drive and left-hand drive vehicles.

[0035] In a particularly advantageous embodiment, the steering systems for left-hand drive vehicles and right-hand drive vehicles are assembled entirely from the same steering system components. This significantly reduces the variety of parts, thus achieving cost savings in production and logistics. Component standardization also simplifies warehousing and reduces the complexity of assembly.

[0036] In another advantageous embodiment, the steering system for left-hand drive vehicles and for right-hand drive vehicles may also consist of components that are identical except for using worms, spindles, or helical gears with opposite helical directions.

[0037] As described above, it can be advantageously specified that, depending on whether the steering system is manufactured for a right-hand drive vehicle or a left-hand drive vehicle, the steering input shaft bearing for rotating the steering input shaft is embedded in an input shaft bearing housing, or in another input shaft bearing housing arranged in a mirror-symmetric manner with the input shaft bearing housing.

[0038] As described above, it can be advantageously specified that, depending on whether the steering system is manufactured for a right-hand drive vehicle or a left-hand drive vehicle, the steering output shaft bearing for rotating the steering output shaft is embedded in an output shaft bearing housing, or in another output shaft bearing housing arranged in a mirror-symmetric manner with the output shaft bearing housing.

[0039] In a particularly advantageous embodiment, the transmission device, especially one connected in series with a strain wave gear mechanism or a cycloidal gear mechanism, has a traction drive mechanism. The traction drive mechanism, such as a timing belt or sprocket type, enables low-noise, low-vibration power transmission. Furthermore, the traction drive mechanism allows the electric motor to be positioned relative to the steering gear in a manner particularly advantageous for utilizing available installation space in the vehicle.

[0040] Alternatively, the transmission device may be configured as a spur gear mechanism, or the transmission device may have one spur gear mechanism. To achieve an advantageous gear ratio in a compact design, the spur gear mechanism may advantageously have three spur gears.

[0041] Optionally, the transmission device, particularly the transmission device connected in series with a strain wave gear mechanism or a cycloidal gear mechanism, may include a spur gear mechanism. To achieve an advantageous transmission ratio in a compact design, the spur gear mechanism may advantageously include three spur gears.

[0042] Overall, it may be advantageous for the transmission device to include a strain wave gear mechanism.

[0043] In an advantageous embodiment, the steering unit has two drivably connected strain wave gear mechanisms in series. This arrangement achieves a combination of exceptionally high reduction ratios and extremely high precision, ensuring accurate and backlash-free steering. An embodiment where the two strain wave gear mechanisms are nested within each other is particularly advantageous. This compact design saves installation space and reduces the overall weight of the steering unit, which is especially beneficial in commercial vehicle applications. In this configuration, the output end of the inner strain wave gear mechanism, such as its flexible or rigid wheel, can be connected to the wave generator of the outer strain wave gear mechanism in a non-rotatable manner, or manufactured as an integral part thereof, for driving it. The output end of the outer strain wave gear mechanism can be connected to the steering output shaft in a non-rotatable manner, or manufactured as an integral part thereof.

[0044] In particular, the steering system can, for example, be configured, through the aforementioned advantageous embodiments of the transmission device, in such a way that the motor is offset from, and particularly offset parallel to, the second gear stage and / or the steering gear output shaft. This arrangement achieves a space-saving design and allows for flexible integration of the motor into the vehicle's mounting space.

[0045] Alternatively, in one embodiment, the steering system can be designed such that the motor is arranged coaxially with the second gear stage and / or with the steering gear output shaft. This embodiment ensures direct and low-loss power transmission, thereby improving system efficiency. This design also makes the unit structure compact, especially radially compact, facilitating installation and maintenance.

[0046] The steering gear housing can advantageously employ a multi-component design. This multi-component implementation simplifies assembly. Furthermore, the multi-component implementation of the steering gear housing facilitates maintenance because the enclosed steering system components are more easily accessible.

[0047] In a particularly advantageous embodiment, the steering gear housing at least encloses the drivably connected gear stages. This protects the steering system components of the gear stages from external influences such as dust, moisture, or mechanical loads, thereby contributing to improved service life and reliability of the steering system.

[0048] Furthermore, the steering gear housing can enclose the transmission device. This ensures optimal protection against contamination and mechanical impacts.

[0049] In a particularly advantageous embodiment, the distance between the plane perpendicular to the steering output shaft and containing the axis of rotation of the first steering input shaft, and the plane containing the portion of the steering unit housing directly surrounding the output shaft bearing housing, is between 70 mm and 90 mm, or equal to 80 mm. These dimensions effectively balance compactness, structural stability, and utilization of available installation space.

[0050] The steering system can advantageously be configured such that the rotation axes of the first steering input shaft and the steering output shaft are intersected. This arrangement allows for particularly efficient use of installation space and enables integration within the vehicle. In particular, the rotation axes of the first steering input shaft and the steering output shaft can also be arranged in mutually perpendicular planes, further maximizing installation space utilization and enabling vehicle integration. In a particularly advantageous embodiment, there is an 80 mm to 100 mm, especially 90 mm, interval between the rotation axes of the first steering input shaft and the steering output shaft.

[0051] A particularly advantageous steering arrangement includes a steering system according to the invention and a steering shaft operatively connected to a steering handle, wherein the steering shaft is coupled to the first steering input shaft, preferably directly coupled, or integrally manufactured with the first steering input shaft.

[0052] A particularly advantageous vehicle, especially a commercial vehicle, particularly a truck or bus, incorporates a steering system according to the invention or a steering arrangement according to the invention. Attached Figure Description

[0053] In the accompanying drawings, the subject matter of the invention is illustrated by way of example, and the following description will refer to the figures, wherein the same or functionally identical elements are generally given the same reference numerals even in different embodiments.

[0054] The diagram is as follows:

[0055] Figure 1 This is a schematic diagram of a first embodiment of the steering system according to the present invention;

[0056] Figure 2 This is a schematic diagram of a second embodiment of the steering system according to the present invention;

[0057] Figure 3 This is a schematic diagram of a third embodiment of the steering system according to the present invention;

[0058] Figure 4This is a schematic diagram of a fourth embodiment of the steering system according to the present invention;

[0059] Figure 5 A front perspective view of a fifth embodiment of a steering system according to the present invention is shown, as well as another front perspective view of a steering system that is mirror-symmetrical to the above-described steering system with respect to a mirror, particularly a vertical mirror.

[0060] Figure 6 It is a rear-view perspective view of a fifth embodiment of the steering system according to the present invention, and another rear-view perspective view of a steering system that is mirror-symmetrical to the above-described steering system with respect to a mirror, particularly a vertical mirror.

[0061] Figure 7 This is a side view of a fifth embodiment of the steering system according to the present invention, and another side view of a steering system that is mirror-symmetrical to the above-described steering system with respect to a mirror, particularly a vertical mirror.

[0062] Figure 8 This is a cross-sectional view of a sixth embodiment of the steering system according to the present invention;

[0063] Figure 9 This is another cross-sectional view of a sixth embodiment of the steering system according to the present invention;

[0064] Figure 10 This is a side view of a sixth embodiment of the steering system according to the present invention;

[0065] Figure 11 It is a front perspective view of a sixth embodiment of the steering system according to the present invention, and another front perspective view of a steering system that is mirror-symmetrical to the above-described steering system with respect to a mirror, particularly a vertical mirror.

[0066] Figure 12 A rear perspective view of a sixth embodiment of a steering system according to the present invention is shown, as well as another rear perspective view of a steering system that is mirror-symmetrical to the above-described steering system with respect to a mirror, particularly a vertical mirror.

[0067] Figure 13 A side view of a sixth embodiment of a steering system according to the invention is shown, as well as another side view of a steering system that is mirror-symmetrical to the above-described steering system with respect to a mirror, particularly a vertical mirror. Detailed Implementation

[0068] Figure 1 A schematic diagram of a first embodiment of the steering system 1 according to the present invention is shown.

[0069] The steering system 1 includes an electric motor 2 and a steering gear assembly 3. The steering gear assembly 3 has a first steering gear input shaft 4 that can be coupled to a steering shaft, a second steering gear input shaft 5 that is drivably coupled to the electric motor 2 via a transmission device 7, and a steering gear output shaft 6. The steering system 1 includes a cycloidal gear mechanism 8 and a strain wave gear mechanism 9, wherein the transmission device 7 includes the strain wave gear mechanism 9, and the steering gear assembly 3 includes the cycloidal gear mechanism 8.

[0070] Figure 2 A schematic diagram of a second embodiment of the steering system 1 according to the present invention is shown.

[0071] Steering system 1 includes an electric motor 2 and a steering gear assembly 3. Steering gear assembly 3 has a first steering input shaft 4 coupled to a steering shaft and a second steering input shaft 5 drivably coupled to the electric motor 2 via a transmission device 7, and a steering output shaft 6. Steering system 1 includes a cycloidal gear mechanism 8 and a strain wave gear mechanism 9, wherein the steering gear assembly 3 includes the strain wave gear mechanism 9 and the cycloidal gear mechanism 8, which are located on the torque path from the first steering input shaft 4 to the steering output shaft 6. The cycloidal gear mechanism 8 is drivably connected to the strain wave gear mechanism 9 downstream of it.

[0072] Figure 3 A schematic diagram of a third embodiment of the steering system 1 according to the present invention is shown.

[0073] Steering system 1 includes an electric motor 2 and a steering gear assembly 3. Steering gear assembly 3 has a first steering input shaft 4 coupled to a steering axle, a second steering input shaft 5 drivably coupled to the electric motor 2 via a transmission device 7, and a steering output shaft 6. Steering system 1 includes a cycloidal gear mechanism 8 and a strain wave gear mechanism 9, wherein the steering gear assembly 3 includes the strain wave gear mechanism 9 and the cycloidal gear mechanism 8, which are located on the torque path from the second steering input shaft 5 to the steering output shaft 6. The cycloidal gear mechanism 8 is drivably connected to the strain wave gear mechanism 9 downstream of it.

[0074] Figure 4 A schematic diagram of a fourth embodiment of the steering system 1 according to the present invention is shown.

[0075] The steering system 1 includes an electric motor 2 and a steering gear assembly 3. The steering gear assembly 3 has a first steering gear input shaft 4 that can be coupled to a steering shaft, a second steering gear input shaft 5 that is drivably coupled to the electric motor 2 via a transmission device 7, and a steering gear output shaft 6. The steering system 1 includes two strain wave gear mechanisms 9 and 10, namely, one strain wave gear mechanism 9 and another strain wave gear mechanism 10. The two strain wave gear mechanisms 9 and 10 are drivably connected in series and arranged to nest with each other. Here, the output end of the first strain wave gear mechanism 9, such as the flexible or rigid wheel of the first strain wave gear mechanism 9, can be connected to the wave generator of the second strain wave gear mechanism 10 in a non-rotatable manner, or it can be integrally manufactured with the second strain wave gear mechanism 10 for driving it. The output end of the second strain wave gear mechanism 10 can be connected to the steering gear output shaft 6 in a non-rotatable manner, or it can be integrally manufactured with the steering gear output shaft 6.

[0076] Figures 5 to 7 A fifth embodiment of the steering system 1 according to the invention is shown, and in another front perspective view, a steering system 12 is shown, which is mirror-symmetrical to the steering system 1 about a mirror 11, particularly a perpendicular mirror. The steering system 1 has an electric motor 2 and a steering gear device 3, the steering gear device 3 having a first steering gear input shaft 4 coupled to a steering shaft and a second steering gear input shaft 5 drivably coupled to the electric motor 2 via a transmission device 7. Figures 5 to 7 (Not visible in the image), and a steering output shaft 6. The motor 2 is coupled to the second steering input shaft 5 via a transmission device 12.

[0077] Steering system 1 includes ( Figures 5 to 7 (Not shown in the image) One cycloidal gear mechanism 8 and one strain wave gear mechanism 9 or two strain wave gear mechanisms 9 and 10.

[0078] The steering system 1 comprises steering system components, including at least an electric motor 2, a steering gear assembly 3, a first steering gear input shaft 4, a second steering gear input shaft 5, and a steering gear output shaft 6. The steering system components also include a steering gear assembly housing 13, which has several fixing elements 14 for securing the steering gear assembly housing 13 to a higher-level structure, particularly the vehicle body. For example, the fixing elements 14 of the steering gear assembly housing 13 can be configured as open holes or threaded holes for fixing screws.

[0079] like Figures 5 to 7As shown, the steering gear housing 13 is configured such that a steering system 12 can be manufactured from the housing, which is mirror-symmetrical to the steering system 1 with respect to the mirror 11, particularly the vertical mirror, at least in terms of the arrangement and orientation of the first steering input shaft 4, the second steering input shaft 5, the steering output shaft 6, and the fixed element 14.

[0080] The distance 15 between the plane 16, which is perpendicular to the rotation axis of the steering output shaft 6 and the first steering input shaft 4, and the plane 17, which is the outer portion of the steering device housing 7 that directly surrounds the output shaft bearing seat 18, is between 70 mm and 90 mm, preferably 80 mm.

[0081] The rotation axes of the first steering input shaft 4 and the steering output shaft 6 are arranged on mutually perpendicular planes 20 and 21, and the distance 19 between the two axes is between 80 mm and 100 mm, preferably 90 mm.

[0082] The steering gear housing 13 has one input shaft bearing seat 22 and another input shaft bearing seat 23, which is arranged mirror-symmetrically with respect to a horizontal mirror surface to the first input shaft bearing seat. The steering gear input shaft bearing is arranged in the input shaft bearing seat 22. The other steering gear input shaft bearing is arranged in the other input shaft bearing seat 23 to securely support the first steering gear input shaft 4 in a rotatable manner. The steering gear input shaft 4 extends outward through an opening in the input shaft bearing seat 22.

[0083] On the other hand, if it is necessary to manufacture a mirror-symmetric steering system 11 for right-hand drive vehicles, rather than, for example, a steering system 1 for left-hand drive vehicles, the steering gear housing 13 can be used in such a way that the steering input shaft 4 extends outward from the steering gear housing 13 through an opening in another input shaft bearing seat 23.

[0084] Figure 8 A cross-sectional view of a sixth embodiment of the steering system 1 according to the present invention is shown.

[0085] The steering system 1 comprises steering system components, including an electric motor 2 and a steering gear assembly 3. The steering gear assembly 3 has a steering shaft (not shown), a steering input shaft 5 drivably coupled to the electric motor 2, and a steering output shaft 6. The steering system components also include a steering gear assembly housing 7, which has several fixing elements 14 for securing the steering gear assembly housing 7 to a higher-level structure, particularly the vehicle body. For example, the fixing elements 14 of the steering gear assembly housing 7 can be configured as open holes or threaded holes 24 for fixing screws.

[0086] The steering gear housing 7 is configured such that a steering system 12 can be manufactured from it. This steering system 12, at least in terms of the arrangement and alignment of the first steering input shaft 4, the second steering input shaft 5, the steering output shaft 6, and the fixing element 14, has mirror symmetry with respect to the mirror 11, particularly the vertical mirror, as shown below. Figures 11 to 13 As shown, it will be described in detail below. Specifically, in this embodiment, the steering system components are designed in such a way that they can be used to produce a steering system 12 that is mirror-symmetrical about the mirror surface 11 with respect to the arrangement and alignment of the first steering input shaft 4, the second steering input shaft 5, the steering output shaft 6, and the fixing element 14.

[0087] In the torque path from motor 2 to steering gear output shaft 6, steering gear unit 3 has a strain wave gear mechanism 9 and another strain wave gear mechanism 10, which are drivably connected in series.

[0088] Motor 2 is coupled to the second steering gear input shaft 5 via transmission device 25. Transmission device 25 is configured as a traction drive device, which includes a traction mechanism 26, a first traction means carrier 27, and a second traction means carrier 28. The first traction means carrier 27 is directly connected to the output shaft 29 of motor 2 in a non-rotatable manner. The second traction means carrier 28 is connected to the second steering gear input shaft 5 in a non-rotatable manner.

[0089] The second steering input shaft 5 is a hollow shaft with an elliptical portion 30. This elliptical portion functions as a deformable part of the wave generator 34 of the strain wave gear mechanism 9, and is mounted in a rotatable state via a radial flexible rolling bearing 31. The elliptical portion 30 presses the end of the can-shaped flexible wheel 32, which has external teeth, into an elliptical shape, and engages it with the internal teeth of the rigid wheel 33 in two meshing positions. Together with the radial flexible rolling bearing 31, the elliptical portion 30 constitutes the wave generator 34 of the strain wave gear mechanism 9.

[0090] The outer circumference of the rigid wheel 33 of the strain wave gear mechanism 9 is elliptical, thus it can simultaneously serve as a variant of another wave generator in another strain wave gear mechanism 10. It is mounted in a rotatable state via another radial flexible rolling bearing 35. The rigid wheel 33 presses the end of another can-shaped flexible wheel 36 with external teeth into an elliptical shape, and engages it with the internal teeth of another rigid wheel 37 in at least two meshing positions. The other rigid wheel 37 is arranged in a non-rotatable manner relative to the steering gear housing. The other can-shaped flexible wheel 36 functions as the output end of another strain wave gear mechanism 10, and is connected to the steering gear output shaft 6 in a non-rotatable manner.

[0091] The torque path from the first steering input shaft 4 to the steering output shaft 6 has several drivably connected gear stages. The first gear stage is configured as a bevel gear mechanism 38 with a crown gear 39 and a pinion 40. The crown gear 39 is connected to the steering input shaft 4 in a non-rotatable manner. The pinion 40 is connected in a non-rotatable manner to a bell-shaped external spur gear 42 via a shaft 41 that is mounted in a rotatable state. The teeth of the spur gear 42 are in mesh with the teeth of another spur gear 43 that is mounted in a rotatable state. The spur gear 42 and the other spur gear 43 constitute another stage in the gear stage. The other spur gear 43 is connected in a non-rotatable manner to a rigid wheel 33.

[0092] The steering gear housing 7 has an output shaft bearing seat 44 in which a steering gear output shaft bearing 45 and a seal 46 are arranged, wherein the steering gear output shaft bearing 45 is used to rotatably support the steering gear output shaft 6.

[0093] Figure 9 Another cross-sectional view of a sixth embodiment of the steering system 1 according to the present invention is shown.

[0094] Figure 9 As shown, the steering input shaft 4 comprises an input portion 47 designed as a solid shaft, an intermediate portion 48 designed as a solid shaft, and a hollow shaft portion 49. The intermediate portion 48 is directly connected at one end to the input portion 47 in a non-rotatable manner, and at the other end to the hollow shaft portion 49 in a non-rotatable manner, wherein the hollow shaft portion 49 surrounds the intermediate portion 48.

[0095] The steering system 1 has a first rotation angle sensor 50 for detecting the rotational position and speed of the input portion 47 of the first steering gear input shaft 4. The steering system 1 also has a second rotation angle sensor 51 for detecting the rotational position of the hollow shaft portion 49 of the first steering gear input shaft 4. The first rotation angle sensor 50 has a first rotation angle sensor element 52 and a first encoding element 53, which interacts non-contactly with the first rotation angle sensor element 52, for example, in the form of a grooved disc, a gear ring, or a magnetic wheel. The second rotation angle sensor 51 has a second rotation angle sensor element 54 and a second encoding element 55, which interacts non-contactly with the second rotation angle sensor element 54, for example, in the form of a coil, a gear ring, or a magnetic wheel. The first and second rotation angle sensor elements 50 and 51 can advantageously be arranged together on the same carrier and / or in the same sensor housing. In the figure, the first rotation angle sensor element 50 and the second rotation angle sensor element 51 are schematically represented by a closed polygon with a diagonal line.

[0096] The detection signals from the first rotation angle sensor element 50 and the second rotation angle sensor element 51 are transmitted to a control device (not shown), which takes the detection signals into account to control the motor 2. In this case, the control device can infer the torque currently applied to the first steering gear input shaft 4 via the steering handle (not shown) based on the corresponding difference between the rotation angle of the first rotation angle sensor element 52 and the rotation angle of the second rotation angle sensor element 54. This is feasible because the input portion 47, where the first encoding element 53 is arranged, and the hollow shaft portion 42, where the second encoding element 55 is arranged, both belong to the first steering gear input shaft 4, but are drivably located in front of and behind the bevel gear mechanism 38, respectively. Therefore, when torque is applied due to torsion, especially the torsion of the relatively thin intermediate portion 48, they will rotate relative to each other, and the greater the torque applied to the first steering gear input shaft 4 via the steering handle (not shown), the greater the difference in rotation angle.

[0097] It may be advantageous for the control device to control the motor 2 based at least on the rotation angle difference between the first rotation angle sensor element 52 and the second rotation angle sensor element 54.

[0098] The steering gear housing 7 has one input shaft bearing seat 56 and another input shaft bearing seat 57, wherein the other input shaft bearing seat 57 is arranged mirror-symmetrically with respect to a horizontal mirror surface to the input shaft bearing seat 56. The steering gear input shaft bearing module 58 is arranged in the input shaft bearing seat 56, which has a rolling bearing 59. The input section 40 is mounted in a rotatable state via the rolling bearing 59.

[0099] Another steering input shaft bearing module 60 is arranged in another input shaft bearing housing 57, which has two rolling bearings 59 for supporting the steering input shaft 4.

[0100] Steering input shaft bearing module 58 and another steering input shaft bearing module 60 are specifically designed to rotatably support the first steering input shaft 4. The steering input shaft 4 extends outward through an opening in the input shaft bearing housing 56.

[0101] On the other hand, if it is necessary to manufacture a mirror-symmetric steering system 12 for right-hand drive vehicles, rather than, for example, a steering system 1 configured for left-hand drive vehicles, then the steering gear housing 7 can be as follows: Figures 11 to 13 As shown, the steering input shaft 4 extends outward from the steering unit housing 7 through the opening of another input shaft bearing seat 57.

[0102] Figure 10 A side view of the steering system 1 is shown. It can be seen that there are a total of five fixing elements 14, which can be configured as threaded holes.

[0103] There are two upper fixing elements 61, two lower fixing elements 62, and one intermediate fixing element 63. The fixing elements 14 are arranged symmetrically about plane 64, which is the plane containing the rotation axis of the steering gear output shaft 6 and the intermediate fixing element 63.

[0104] like Figures 11 to 13 As shown, the steering gear housing 7 is constructed in such a way that a steering system 12 can be manufactured from this housing. This steering system 12 is mirror-symmetrical to the steering system 1 in terms of the arrangement and orientation of the first steering input shaft 4, the second steering input shaft 5, the steering output shaft 6, and the fixing elements 8, with respect to the mirror 11, particularly a vertical mirror. In the steering system 1, two upper fixing elements 61 are arranged at the top, while in the mirror-symmetrical steering system 12, two upper fixing elements 61 are arranged at the bottom. In the steering system 1, two lower fixing elements 62 are arranged at the bottom, while in the mirror-symmetrical steering system 12, two lower fixing elements 62 are arranged at the top.

[0105] In steering system 1, the steering input shaft 4 extends outward through the opening of the input shaft bearing housing 56, while in mirror-symmetric steering system 12, the steering input shaft 4 extends outward through the opening of another input shaft bearing housing 57.

[0106] Explanation of reference numerals in the attached figures:

[0107] 1. Steering system

[0108] 2. Motor

[0109] 3. Steering Gear

[0110] 4. First steering gear input shaft

[0111] 5. Second steering gear input shaft

[0112] 6. Steering gear output shaft

[0113] 7. Steering gear housing

[0114] 8. Cycloidal gear mechanism

[0115] 9. Strain-wave gear mechanism

[0116] 10. Another strain wave gear mechanism

[0117] 11. Mirror

[0118] 12. Mirror-symmetric steering system

[0119] 13. Steering gear housing

[0120] 14. Fixing components

[0121] 15. Distance

[0122] 16. Plane

[0123] 17. Plane

[0124] 18. Output shaft bearing housing

[0125] 19. Distance

[0126] 20. Plane

[0127] 21. Plane

[0128] 22. Input shaft bearing housing

[0129] 23. Another input shaft bearing housing

[0130] 24. Threaded hole

[0131] 25. Transmission device

[0132] 26. Traction mechanism

[0133] 27. First traction mechanism bearing component

[0134] 28. Second traction mechanism bearing component

[0135] 29. Output shaft

[0136] 30. Oval section

[0137] 31. Radial flexible rolling bearing

[0138] 32. Flexible wheel

[0139] 33. Rigid wheel

[0140] 34. Wave Generator

[0141] 35. Another radial flexible rolling bearing

[0142] 36. Another flexible wheel

[0143] 37. Another rigid wheel

[0144] 38. Bevel gear mechanism

[0145] 39. Crown Gear

[0146] 40. Small gear

[0147] 41. Shaft

[0148] 42. Spur gear

[0149] 43. Another spur gear

[0150] 44. Output shaft bearing housing

[0151] 45. Steering gear output shaft bearing

[0152] 46. ​​Sealing components

[0153] 47. Input Section

[0154] 48. Middle section

[0155] 49. Hollow Shaft Section

[0156] 50. First rotation angle sensor

[0157] 51. Second rotation angle sensor

[0158] 52. First rotation angle sensor element

[0159] 53. First coding element

[0160] 54. Second rotation angle sensor element

[0161] 55. Second coding element

[0162] 56. Input shaft bearing housing

[0163] 57. Another input shaft bearing housing

[0164] 58. Steering gear input shaft bearing module

[0165] 59. Rolling bearings

[0166] 60. Another steering gear input shaft bearing module

[0167] 61. Upper fixing element

[0168] 62. Lower fixing element

[0169] 63. Intermediate fixing element

[0170] 64. Plane

Claims

1. A steering system, comprising: a. Electric motor; and b. A steering mechanism comprising a first steering input shaft coupled to a steering shaft, a second steering input shaft drivably coupled to the electric motor via a transmission device, and a steering output shaft. Its features are: c. The steering system includes: i. Cycloidal gear mechanisms and strain wave gear mechanisms, or ii. Two strain wave gear mechanisms.

2. The steering system according to claim 1, characterized in that, The steering device and the transmission device each include a cycloidal gear mechanism or a strain wave gear mechanism.

3. The steering system according to claim 1 or 2, characterized in that, The torque path from the first steering input shaft to the steering output shaft has at least two drivably connected gear stages in series.

4. The steering system according to claim 3, characterized in that, The first gear stage is configured as a bevel gear mechanism, a worm gear mechanism, a spindle gear mechanism, an interleaved shaft helical gear mechanism, or a strain wave gear mechanism, and the second gear stage, which is drivably connected downstream of the first gear stage, is configured as a strain wave gear mechanism or a cycloidal gear mechanism.

5. The steering system according to claim 3 or 4, characterized in that, The steering gear housing has fixing elements for securing the steering gear housing to a higher-level structure, particularly the vehicle body.

6. The steering system according to claim 5, characterized in that, The steering gear housing is configured such that a steering system can be manufactured that is mirror-symmetrical to the steering system, at least in terms of the arrangement and orientation of the first steering input shaft, the second steering input shaft, the steering output shaft, and the fixed elements, with respect to the mirror surface, particularly the vertical mirror surface.

7. The steering system according to any one of claims 1 to 6, characterized in that, a. The steering system components are configured in such a way that a steering system can be manufactured that is mirror-symmetrical to the steering system with respect to the mirror surface, particularly the vertical mirror surface, at least in terms of the arrangement and orientation of the first steering input shaft, the second steering input shaft, the steering output shaft, and the fixed element; or, b. The steering system components are configured such that, when all the worms, spindles, and helical gears are replaced by the same worms, spindles, and helical gears having opposite helical directions, a steering system can be manufactured that is mirror-symmetrical to the steering system at least in terms of the arrangement and orientation of the first steering input shaft, the second steering input shaft, the steering output shaft, and the fixed elements, with respect to the mirror surface, particularly with respect to the vertical mirror surface.

8. The steering system according to any one of claims 1 to 7, characterized in that, a. The transmission device has a traction transmission mechanism; or b. The transmission device has a spur gear mechanism; or c. The transmission device has the strain wave gear mechanism or one of the two strain wave gear mechanisms; or d. The steering mechanism has two drivably connected strain wave gear mechanisms in series; or e. The steering device has two drivable strain wave gear mechanisms connected in series, wherein the strain wave gear mechanisms are nested together.

9. The steering system according to any one of claims 3 to 8, characterized in that, a. The motor is offset from the second gear stage and / or the steering gear output shaft, particularly offset parallel to its axis; or b. The motor is arranged coaxially with the second gear stage and / or the steering gear output shaft.

10. The steering system according to any one of claims 1 to 9, characterized in that, The steering system has at least one of the following characteristics a to c: a. The steering gear housing adopts a multi-component design; b. The steering gear housing at least encloses the drivably connected gear stages; c. The steering gear housing encloses the transmission device.

11. The steering system according to any one of claims 1 to 10, characterized in that, a. The steering gear housing, particularly at an opening in its housing wall, includes at least one input shaft bearing housing for a steering input shaft bearing; or... b. The steering gear housing, particularly at an opening in its housing wall, includes at least one input shaft bearing housing for a steering gear input shaft bearing, wherein the steering gear housing, particularly at another opening in its housing wall, includes at least one other input shaft bearing housing for a steering gear input shaft bearing, the other input shaft bearing housing being constructed and arranged in a mirror-symmetrical manner with respect to a mirror surface, particularly with respect to a horizontal mirror surface, to the input shaft bearing housing.

12. The steering system according to any one of claims 1 to 11, characterized in that, a. The steering gear housing, particularly at an opening in its housing wall, has at least one output shaft bearing housing for a steering gear output shaft bearing; or... b. The steering gear housing, particularly at the opening in its housing wall, has at least one output shaft bearing seat for a steering gear output shaft bearing, wherein the distance between the plane perpendicular to the axis of rotation of the steering gear output shaft and the first steering gear input shaft, and the plane containing the portion of the steering gear housing directly surrounding the output shaft bearing seat, is between 70 mm and 90 mm, particularly equal to 80 mm.

13. The steering system according to any one of claims 1 to 12, characterized in that, The steering system has at least one of the following characteristics a to c: a. The rotation axis of the first steering gear input shaft and the rotation axis of the steering gear output shaft intersect each other; b. The rotation axis of the first steering gear input shaft and the rotation axis of the steering gear output shaft are arranged in mutually perpendicular planes; c. The rotation axis of the first steering input shaft and the rotation axis of the steering output shaft are spaced between each other by 80 mm and 100 mm, particularly by a distance equal to 90 mm.

14. A steering arrangement having a steering system according to any one of claims 1 to 13, and having a steering shaft operatively connected to a steering handle and coupled to the first steering input shaft.

15. A vehicle, particularly a commercial vehicle, especially a truck or bus, having a steering system according to any one of claims 1 to 13 or a steering system according to claim 14.

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