Power steering arrangement with suitable and adjustable compensation of roadside shock pulses for the steering gear and method for adjusting the power steering arrangement - Patents.com

Abstract

The invention relates to a power steering arrangement for electromechanical power steering of a motor vehicle (10), in particular a commercial vehicle, which has a steering gear (1) adapted to transmit a rotational movement (III) introduced by a steering generator, in particular by a steering wheel (15), via an input side (2) of the steering gear (1), in particular via an input shaft (3) of the steering gear (1), to an output side (4) of the steering gear (1), the power steering arrangement adapted to convert a movement (I) derived from the output side (4) of the steering gear (1) into a rotational movement (V) of at least one wheel (17; 19) of the motor vehicle (10) about a steering axis (18). According to the proposal, an adjustable absorption unit (23) is provided for at least partially absorbing road shocks taken in via the wheels (17; 19) of the motor vehicle (10) and furthermore a separate preload unit (24) is provided. The separate preload unit (24) is configured to cooperate with the adjustable absorption unit (23) such that a predetermined preload force is applied to the adjustable absorption unit (23).The invention further relates to a method of adjusting a power steering group for electromechanical power steering of a motor vehicle (10).

Description

[Technical field]

[0001] The invention relates to a power steering arrangement for electromechanical power steering of a motor vehicle in the manner specified in the preamble of claim 1. The invention further relates to a method for adjusting a power steering arrangement for electromechanical power steering of a motor vehicle in the manner specified in the preamble of claim 9.

[0002] Power steering components are known from a large amount of the prior art. In this case, the power steering components include several components that are sensitive to mechanical loads, in particular in connection with the steering gear integrated in the power steering components, i.e. the steering gear further comprises a spindle, a ball circulation nut with balls or a ball chain, as well as a tooth pair, for example in the form of an outer toothing of the ball circulation nut, which engages with the sector toothing of the sector shaft. These components are particularly sensitive to suddenly applied mechanical forces or loads.

[0003] The cause of such a sudden load is, for example, a road shock pulse, i.e., a bump in the road can lead to a shock in the vehicle, which can lead to an undesirable sudden movement of the power steering group, for example. In the prior art, only the shock damper system of the wheel suspension is usually used to compensate for the road shock. However, such a system can be improved in order to better compensate or absorb the loads or stresses introduced into the sensitive components of the steering gear.

[0004] In the following, these problems will be explained by way of example in the case of a commercial vehicle, without it being understood that this is not limiting. Commercial vehicles usually have a power steering assembly with a recirculating ball steering mechanism. For this purpose, the power steering assembly has a steering gear, which is designed to transfer a rotational movement introduced by a steering generator, i.e. for example by a steering wheel, from an input side of the steering gear to an output side of the steering gear. In this case, the input side can be formed, for example, by an input shaft, and the output side can be formed, for example, by an output shaft in the form of a sector shaft. In this case, for example, the input shaft is formed as a spindle inside the steering gear, and the rotational movement of the spindle generates a translational movement of a recirculating ball nut surrounding the spindle section, so that the introduced rotational movement of the input shaft can be converted in a defined way, which translational movement can also be called the recirculating ball nut or the axial movement of the piston. The recirculating ball nut is further usually provided with an outer toothing. In this case, the ball recirculating nut, by means of its outer toothing which meshes with the sector toothing of the sector shaft, can serve to convert the translational movement of the ball recirculating nut into a rotational movement of the sector shaft or output shaft and thus to be delivered to the output side of the steering gear. This output side is usually followed by a pitman arm, to which a thrust rod is pivotally connected. The thrust rod of the power steering assembly finally receives the rotational movement delivered from the output side of the steering gear and performs a translational thrust rod movement, also called an axial movement, in a defined manner during the steering process itself. This translational thrust rod movement then results in a defined rotational movement of at least one wheel of the motor vehicle about the steering axis.

[0005] In such a power steering system, a road shock pulse can cause sudden movements of many of the components of the power steering system, which in turn lead to undesirable loads or stresses being introduced into the steering gear. Up until now, such forces or loads and stresses in the prior art power steering system itself are usually primarily compensated for by the hydraulic pressure of the power steering system.

[0006] In the prior art, moreover, a great deal of effort is usually required to design such a power steering component for each specific application. Therefore, in order to precisely define the switching points of the steering gear or the damping elements, which may be provided for the power steering component, very precise and complex design and manufacturing methods are often required. This basically leads to the problem that indirect steering behavior can occur if the individual components installed are not correctly designed or manufactured. In order to avoid such undesirable effects, such as indirect steering behavior, a time-consuming and cost-intensive individual design of the steering gear for the power steering component must be carried out, which is adapted to the application. Corresponding methods for adjusting the power steering component are therefore very complex in the prior art.

[0007] In this context, the object of the present invention is to improve the power steering system of the type mentioned at the beginning, so that the steering gear is better protected from road-side shock pulses. Furthermore, it is desirable to reduce the effort required for design and production, and to avoid indirect steering behavior in the simplest possible way. Therefore, the object of the present invention is also to provide a method for adjusting a power steering system for electromechanical power steering of a motor vehicle, which can reduce the effort required for effectively avoiding indirect steering behavior.

[0008] This problem is solved by a power steering arrangement having the features set forth in the characterizing part of claim 1. Furthermore, this problem is solved by a method having the features set forth in the characterizing part of claim 9. Particularly advantageous further configurations of the invention are disclosed in the dependent claims.

[0009] The basic idea is to design the power steering assembly in such a way that an individual adjustable absorption unit is provided in a defined manner within the power steering assembly in order to adequately protect the steering gear from the loads or stresses caused by roadside shock pulses. For this purpose, the adjustable absorption unit adequately compensates for such movements and the resulting loads by converting kinetic energy into potential energy in the adjustable absorption unit. Forces or loads on the steering gear are reduced, which would not be substantially damped or damped or would only be damped or compensated by the hydraulic pressure of the power steering if the adjustable absorption unit were not provided. The adjustable absorption unit is adapted for this purpose to convert kinetic energy into potential energy and serves to adequately damp or absorb vibrations in a spring-like manner. The adjustable absorption unit is preferably designed elastically for this purpose. The adjustable absorption unit is advantageously designed in such a way that it allows at least small relative movements of the surrounding components of the power steering assembly adjacent to the adjustable absorption unit.

[0010] It is important to note that the above-mentioned disadvantages of the prior art can be avoided by the fact that the present invention additionally provides a separate preload unit which can be used to adjust the adjustable absorption unit. The separate preload unit can thus adjust the adjustable absorption unit to a preload force that is individually adapted to the respective application, by simply compressing the adjustable absorption unit to the desired extent. This allows the adjustable absorption unit to be adjusted simply and precisely in such a way that indirect steering behaviors can be effectively avoided. This also significantly reduces the effort in the manufacturing process of the power steering component and in particular the costs involved in the design of the power steering component. Thus, highly precise and complex design and manufacturing methods are no longer necessary in order to precisely define the switching points of the adjustable absorption unit. This allows indirect steering behaviors to be effectively avoided by simply preloading the adjustable absorption unit to the desired extent by means of the separate preload unit, even if the components are not precisely designed or manufactured.

[0011] A power steering arrangement according to the proposal for electromechanical power steering of a motor vehicle, which may in particular be a power steering arrangement for electromechanical power steering of a commercial vehicle, comprises a steering gear. The steering gear is configured to transfer a rotational movement introduced by a steering generator from an input side of the steering gear to an output side of the steering gear. The steering generator may in particular be a steering wheel. The introduced rotational movement may in particular be introduced via an input shaft of the steering gear. According to the proposal, the power steering arrangement is configured to convert the movement introduced from the output side of the steering gear into a rotational movement of at least one wheel of the motor vehicle about a steering axis.

[0012] The power steering group according to the proposal is characterized in that an adjustable absorption unit is provided for at least partially absorbing road shocks taken in through the wheels of the motor vehicle, and furthermore according to the proposal a separate preload unit is provided, which is arranged to cooperate with the adjustable absorption unit in such a way that a preload force is applied to the adjustable absorption unit.

[0013] The proposed method for adjusting a power steering arrangement for electromechanical power steering of a motor vehicle is in particular a method for adjusting a power steering arrangement according to the proposal as described above or below, for example a power steering arrangement according to one of claims 1 to 8.

[0014] The proposed method is characterized in that an adjustable absorption unit for at least partially absorbing road shocks captured via the wheels of the vehicle is integrated into the steering movement translation path of the entire power steering assembly, and furthermore, according to the proposed method, a separate preload unit is provided, which compresses the adjustable absorption unit and thereby finally adjusts the predefined preload force applied to the adjustable absorption unit.

[0015] Basically, the adjustable absorbent unit can be at least partially compressed (e.g. at least one elastic element or a group of elastic elements, if the adjustable absorbent unit is formed from several elastic elements arranged differently) to any desired predefined degree. In this case, any is of course understood to mean a degree within certain boundaries, i.e. within a region adapted to the construction space. In particular, for example, a compensation disk or several compensation disks of a predefined thickness can be provided, which compress the adjustable absorbent unit by exactly that thickness. Usually, for this, the adjustable absorbent unit is simply compressed axially by a separate preloading unit, since the available construction space left for the adjustable absorbent unit is reduced by arranging the compensation disks. Alternatively, a preloading nut or other constructional component with a thread that engages with a corresponding thread can also be provided as a separate preloading unit. In this case, the degree of compression of the adjustable absorbent unit can advantageously be adjusted individually by screwing a threaded component into the corresponding thread to the desired degree, thereby compressing the adjustable absorbent unit to that degree.

[0016] Basically, the adjustable absorption unit according to the proposal is in particular integrated into a power steering assembly and is a component part thereof, for which purpose it can be integrated, for example, in the steering movement conversion path of the entire assembly, i.e. between the input side of the steering gear and, for example, the thrust rod which effects the steering, seen from the steering generator, i.e., for example the steering wheel, towards the wheels to be steered.

[0017] As a result, the sudden movements in the proposed power steering system are advantageously compensated for by the adjustable absorption unit and the resulting loads are at least partially absorbed, so that shock pulses from the road surface or the forces resulting therefrom can be adequately spring-damped or compensated for when they are transmitted via the wheel, for example to the thrust rod and possibly also to other components of the power steering system, for example connected to the thrust rod provided, or via the steering gear housing, so that no longer only the hydraulic pressure of the power steering system serves for such compensation of road-side shock pulses, so that the steering gear of the proposed power steering system, and in particular the sensitive components arranged inside the steering gear, are well protected against road-side shock pulses.

[0018] Basically, the input side of the steering gear can be formed by an input shaft, which can in particular be formed as a spindle. The output side of the steering gear can also be formed by an output shaft, preferably a sector shaft. The movements derived from the output side of the steering gear can be transferred directly or indirectly from the output side, for example via a sector shaft, further, for example to a thrust rod. The output shaft can then be rigidly connected, for example to a pitman arm, in particular immovably or rotationally immovable. In this case, the pitman arm can receive the rotational movement of the output shaft and can likewise perform a rotational movement. In this case, for example, a ball joint can be provided at the end of the pitman arm opposite the output shaft, which connects the pitman arm to the thrust rod. The ball joint thus transfers the movements derived from the output side of the steering gear in the form of a rotational movement of the output shaft and thus of the pitman arm to the thrust rod, resulting in a translational thrust rod movement.

[0019] Thus, in such an embodiment with a thrust rod, the thrust rod is provided to receive a movement derived from the output side of the steering gear and to perform a translational thrust rod movement, in which case the thrust rod is arranged such that the translational thrust rod movement causes a rotational movement of at least one wheel of the motor vehicle about the steering axis.

[0020] The adjustable absorption unit can be arranged so that it is basically integrated in the steering gear, preferably between the input side and the output side of the steering gear. The adjustable absorption unit can basically be formed as an elastic element, for example as an elastomer or spring package, or several elastic elements can be provided as the adjustable absorption unit. Basically, the relative movement of adjacent components can be made possible by the elastic element of the adjustable absorption unit, so that the kinetic energy is absorbed by the adjustable absorption unit, thereby resulting in the desired compensation effect. Basically, it can be preferably envisaged that the adjustable absorption unit is formed from at least one elastic element, in particular at least one disc spring and / or at least one coil spring and / or at least one elastomer.

[0021] In principle, it may be provided that the steering gear has an input shaft configured as a spindle and a ball circulation nut for converting the rotational movement of the input shaft into a translational movement, the tooth section being arranged to surround the ball circulation nut from the outside. In this case, it may be provided that the adjustable absorption unit is arranged in such a way that the translational movement of the ball circulation nut is transmitted to the tooth section via the adjustable absorption unit or vice versa. As a result, roadside shock pulses can be effectively compensated in a particularly advantageous manner in the steering gear itself.

[0022] Alternatively or additionally, it can also be provided that the steering gear has an input shaft configured as a spindle and a ball bearing nut for converting the rotational movement of the input shaft into a translational movement, and the adjustable absorption unit is at least partially configured as an elastic axial spindle bearing of the input shaft, so that road shock pulses can be effectively compensated on the input side of the steering gear in a particularly advantageous manner.

[0023] In addition, the adjustable absorption unit, which is preferably formed as an elastic axial spindle bearing of the input shaft, is formed by at least one elastic element, in particular at least one disk spring, which is arranged adjacent to the bearing assembly of the input shaft for rotatably supporting the input shaft in the housing, in such a way that the bearing assembly of the input shaft is accommodated in the housing axially elastically via the at least one elastic element. Axially elastic is to be understood in particular as axially with respect to the input shaft. Surprisingly, it was recognized that the present invention allows the economy of the entire power steering group to be further improved, despite the increased constructional effort in the form of a supplementary bearing assembly of the input shaft, since the sensitive components of the steering gear are advantageously protected against road-side shock pulses and thus the service life is improved.

[0024] Basically, and preferably, it can be assumed that the input shaft formed as a spindle is formed in multiple parts by at least one spindle section facing the ball recirculating nut and the input section, which are connected to one another in a non-rotatable manner, but axially elastically, via an adjustable damping unit formed as an elastic axial spindle bearing of the input shaft, preferably in the form of at least one elastic element, particularly preferably in the form of a ring spring. Surprisingly, it was recognized that the service life of the entire power steering assembly can be further increased by the invention, despite the increased constructional effort in the form of a split input shaft, in particular the associated weakening of the input shaft and thus of the entire power steering assembly, since the sensitive components of the steering gear are advantageously better protected against road-side shock pulses.

[0025] A preferred embodiment of the power steering assembly is characterized in that the separate preload unit comprises at least one first compensation disk. This allows the preload force for the adjustable absorption unit to be individually configured in a particularly simple manner. The power steering assembly can be individually adapted to the application without the need for a complex design of the individual components, in particular the elastic elements of the adjustable absorption unit. Furthermore, inaccuracies in the manufacture of the power steering assembly can be effectively compensated for. Preferably, the first compensation disk forms a direct contact surface as abutment surface for the adjustable absorption unit or for some of its elastic elements.

[0026] Additionally, it may be provided that the separate preload unit further comprises at least one second compensation disk. In particular, the second compensation disk may have a second thickness that is different from the first thickness of the first compensation disk. This allows a particularly simple adaptation to the specific use case for the power steering assembly. It can be adapted individually to the use case of the power steering assembly without the need for a complex design of the individual components, in particular the elastic elements of the adjustable absorption unit. Furthermore, inaccuracies in the manufacture of the power steering assembly can also be effectively compensated. Preferably, the first compensation disk and the second compensation disk are arranged directly against each other.

[0027] According to another embodiment of the power steering assembly, it is provided that the separate preload unit has a preload nut. This allows the preload force for the adjustable absorption unit to be individually determined in a particularly simple manner. It can be individually adapted to the application of the power steering assembly without the need for a complex design of the individual components, in particular the elastic elements of the adjustable absorption unit. Furthermore, imprecisions in the manufacture of the power steering assembly can be effectively compensated for. Preferably, the preload nut can be simply screwed further into the corresponding mating thread in order to increase the preload force. Furthermore, the preload nut preferably has an end face which forms a direct contact surface as an abutment surface for the adjustable absorption unit or for some of its elastic elements.

[0028] According to a further embodiment of the power steering group, it is envisaged that the separate preload unit is arranged to cooperate with the adjustable absorption unit, preferably in a substantially stepless manner, such that a preload force is adjustable via two components which are engaged with each other via a screw thread and a corresponding screw thread. In this case, substantially stepless does not mean that it can take on an arbitrarily high or low value, i.e. that the components can be rotated relative to each other in any width, but that it can only be rotated relative to each other by a certain range. Furthermore, when the components are rotated relative to each other, small jumps may occur in the resulting preload force. In that respect, the concept of stepless should not be understood as absolute. An individual adaptation of the preload force is thus easily possible.

[0029] According to a further embodiment of the power steering assembly, it is provided that the separate preload unit and the adjustable absorption unit are at least partially movable axially relative to one another in the assembled state, thereby ensuring effective compensation of road shocks.

[0030] According to a further embodiment of the power steering group, it is provided that the separate preload unit is fixed in the assembled state against circumferential rotation, in particular via a fixing pin engaging in a groove, thereby ensuring the reliability of the uniform compensation action of the adjustable absorption unit, and effectively preventing undesired changes in the preload force.

[0031] According to a further embodiment of the power steering assembly, it is provided that the separate preload unit has end faces which form contact surfaces for directly abutting the adjustable absorption unit in order to apply a preload force to the adjustable absorption unit, thereby ensuring an effective and uniform transfer of the preload force of the preload unit to the adjustable absorption unit.

[0032] A preferred embodiment of the method for adjusting a power steering assembly is characterized in that at least one first compensation disk is provided adjacent to the adjustable absorption unit as a separate preloading unit in order to preload the adjustable absorption unit by a suitable compression. This allows the preload force acting on the adjustable absorption unit to be individually configured in a particularly simple manner. It can be individually adapted to the application of the power steering assembly without the need for a complex design of the individual components, in particular the elastic elements of the adjustable absorption unit. Furthermore, inaccuracies in the manufacture of the power steering assembly can also be effectively compensated. The method is therefore effective and simple. Preferably, the first compensation disk forms a direct contact surface as abutment surface for the adjustable absorption unit or for some of its elastic elements.

[0033] It may furthermore be provided that a second compensation disk is additionally provided adjacent to the adjustable absorption unit for preloading the adjustable absorption unit by appropriate compression. In this case, the second compensation disk preferably has a second thickness different from the first thickness of the first compensation disk. This allows a particularly simple adaptation to the application for the power steering assembly. It can be individually adapted to the application for the power steering assembly without the need for a complex design of the individual components, in particular the elastic elements of the adjustable absorption unit. Furthermore, inaccuracies in the manufacture of the power steering assembly can also be effectively compensated. Preferably, the first compensation disk and the second compensation disk are arranged directly against each other.

[0034] According to a further embodiment of the method, it is provided that a preload nut is provided adjacent to the adjustable absorption unit as a separate preload unit in order to preload the adjustable absorption unit by a suitable compression. This allows the preload force for the adjustable absorption unit to be individually configurable in a particularly simple manner. It can be individually adapted to the application of the power steering assembly without the need for a complex design of the individual components, in particular the elastic elements of the adjustable absorption unit. Furthermore, inaccuracies in the manufacture of the power steering assembly can be effectively compensated for. Preferably, the preload nut can be simply screwed further into the corresponding mating thread in order to increase the preload force. Furthermore, the preload nut preferably has an end face which forms a direct contact surface as an abutment surface for the adjustable absorption unit or for some of its elastic elements.

[0035] According to a further embodiment of the method, it is envisaged to adjust the pre-defined pre-load force by rotating the first component with the screw thread and the second component of the separate pre-load unit, which engages with the first component and has a corresponding screw thread, relative to each other. Thus, preferably, the pre-load force is substantially steplessly adjustable. In this case, substantially steplessly does not mean that it can assume an arbitrarily high or low value, i.e. that the components can be rotated relative to each other in any width, but that it can only be rotated relative to each other by a certain range. Furthermore, when the components are rotated relative to each other, small jumps in the resulting pre-load force may occur. In that respect, the concept of steplessness should not be understood as absolute. Thereby, an individual adaptation of the pre-load force is easily possible. The further the two components are rotated relative to each other, the higher the degree of compression of the adjustable absorbent unit, i.e. the higher the pre-load force acting on the adjustable absorbent unit.

[0036] According to another embodiment of the method, it is envisaged that the separate preload unit is finally fixed against circumferential rotation.

[0037] Additionally, it may preferably be provided that this fixing is effected by providing fixing pins which engage in a circumferentially positive manner in the grooves.

[0038] This ensures effective compensation of roadside shocks, and ensures a uniform compensating action of the adjustable absorption unit, since undesired changes in the preload force are effectively prevented.

[0039] The features and resulting advantages of the proposed power steering arrangements described above and below are applicable, where technically significant, to the proposed method, and vice versa.

[0040] Further features and advantages of the invention will become apparent from the claims and the following description of embodiments of the invention which should not be understood as limiting, which are explained in more detail below also with reference to the drawings, in which: [Brief description of the drawings]

[0041] [Figure 1] FIG. 2 is a schematic diagram of a steering gear. [Diagram 2] FIG. 2 is a schematic diagram of a motor vehicle equipped with the steering gear of FIG. 1. [Figure 3a] FIG. 2 is a schematic diagram partially showing a cross-sectional view of a steering gear of the power steering assembly according to the present invention. [Figure 3b] FIG. 3a is a cross-sectional view taken along line AA of FIG. 3a. [Figure 4] FIG. 1 shows a separate preload unit formed as a compensation disk. [Diagram 5] FIG. 3A shows a partial cross-sectional view of the steering gear of the proposed power steering assembly, essentially along the line BB in FIG. 3A. [Figure 6] FIG. 3A shows a partial cross-sectional view of a steering gear of another power steering arrangement according to the present proposal, essentially along the line BB in FIG. 3a). [Figure 7a] FIG. 2 is a perspective view showing an input shaft of the power steering component group according to the present proposal in an assembled state. [Figure 7b] FIG. 7b is a front view in the direction B of FIG. 7a. [Figure 7c] FIG. 7b) is a cross-sectional view taken along line AA of FIG. [Figure 8] FIG. 7a) shows the input shaft of the proposed power steering arrangement according to FIG. 7a) in a disassembled state with all its individual components.

[0042] A power steering group for electromechanical power steering of a motor vehicle is shown diagrammatically in Figure 1. The power steering group has a steering gear 1. Steering movements performed by the driver of the motor vehicle by means of a steering generator, for example a steering wheel (not shown in Figure 1), are converted via the steering gear 1. For this purpose, via an input side 2 of the steering gear 1, in the concrete illustrated case a rotational movement introduced via an input shaft 3 is transmitted to an output side 4 of the steering gear 1.

[0043] At the output side 4 of the steering gear 1, a movement is further derived, which in the illustrated case is a rotational movement of an output shaft 6 of the steering gear 1, which is formed as a sector shaft 5. This movement derived at the output side 4, which in the illustrated case is a rotational movement indicated by two curved double arrows I, is finally received by a thrust rod 7 of the power steering group in this non-limiting illustrated example, which thereby performs a translational thrust rod movement. The translational thrust rod movement of the thrust rod 7 is a linear movement indicated by a double arrow II in FIG. 1, which finally results in a rotation of at least one wheel of the motor vehicle about the steering axis (not shown in FIG. 1), as a result of which the motor vehicle performs the desired cornering.

[0044] In order to convert the rotational movement (double arrow I) delivered to the output side 4 into the desired translational thrust rod movement (double arrow II) of the thrust rod 7, the illustrated power steering assembly comprises a pitman arm 8 and a joint in the form of a ball joint 9 connecting the pitman arm 8 to the thrust rod 7.

[0045] For the following description of the general steering process, reference is made to both Figures 1 and 2, where Figure 2 shows a schematic view from below of a motor vehicle 10 equipped with a power steering assembly having the steering gear 1 shown in Figure 1.

[0046] For motor vehicles 10 in the form of commercial vehicles, a recirculating ball steering gear is usually used as a so-called recirculating ball steering mechanism (KUL for short). The kinematics of such an assembly are particularly suitable for commercial vehicles, since commercial vehicles primarily have a front axle in the form of a rigid axle. If the trailing arm and the thrust rod of the front axle are of approximately equal length and are arranged approximately parallel to one another, they form a parallelogram. As a result, no or only very little spring movement of the front axle plays any role. If the steering gear 1 is mounted fixedly on the frame, length compensation in the steering column can be achieved, for example, by corresponding relative movements between the frame and the driver's cab of the motor vehicle 10. Since commercial vehicles are an application example for which the proposed power steering arrangement is particularly suitable, the invention will be explained below with the example of a recirculating ball steering mechanism.

[0047] The steering gear 1 comprises an input shaft 3, which is formed in a certain section as a spindle 11, and a ball recirculating nut 13, which is arranged in the region of the spindle 11 and has an outer toothing 12. Sector teeth 14 engage with the outer toothing 12. The sector teeth 14 and the outer toothing 12 are arranged in mesh with one another. The sector teeth 14 is furthermore connected rotationally immovably, i.e. fixedly, to an output shaft 6, which is therefore formed as a sector shaft 5. A pitman arm 8 is furthermore connected rotationally immovably or fixedly, to the output shaft 6, which is furthermore, as already mentioned above, movably connected to the thrust rod 7 via a ball joint 9.

[0048] In the steering gear 1, the rotation of a steering generator, in particular a steering wheel 15 (FIG. 2), is transmitted via a steering column and an input shaft 3 to a spindle 11. The input shaft 3 can, for example, be part of a steering column. The spindle 11 is also called a ball screw or, in some cases, a worm. This rotational movement of the input shaft 3, indicated in FIG. 1 by the arrow III showing a circular movement, is converted by the ball circulation nut 13 into a linear movement of the ball circulation nut 13 and thus also of the outer toothing 12 of the ball circulation nut 13. This linear movement of the ball circulation nut 13 and of the outer toothing 12 is indicated in FIG. 1 by the double-headed arrow IV.

[0049] The linear movement indicated by the double arrow IV is then converted via the tooth pair of the outer teeth 12 and the sector teeth 14 into a rotational movement of the output shaft 6 indicated by the curved double arrow I, which is led to the output side 4 of the steering gear 1 as already explained. The linear movement (double arrow IV) is thus also converted finally into a rotational movement (double arrow I) of the pitman arm 8. At the end of the pitman arm 8, the thrust rod 7 is again moved mainly linearly. As can be seen from FIG. 2, the wheel 17 to be steered is finally swiveled about the steering axis 18 by the thrust rod 7 via the steering lever 16 attached to the wheel carrier. Such a rotational movement of the wheel 17 is indicated in FIG. 2 by the curved double arrow V. In this case, another wheel 19 opposite the wheel 17 can be steered together via a steering arm 20 and a rigid tie rod 21.

[0050] With reference to FIG. 1, it can be seen that the rotational movement (double arrow I) derived from the output side 4 is transmitted to the thrust rod 7 via the ball joint 9, whereby the thrust rod 7 performs a translational thrust rod movement (double arrow II), as a result of which the steering movement of the wheel 17 or the wheels 17, 19 is performed in a predetermined manner.

[0051] Figure 2 further shows the frame 22 of the motor vehicle 10 in the form of two side members arranged parallel to one another. The steering gear 1 can be attached to the frame 22 of the motor vehicle 10 by means of fastening devices not shown in Figures 1 and 2, for example by means of the side members of the frame 22 and the casing of the steering gear 1 being connected to one another via fastening screws. The direction of travel of the motor vehicle 10 is indicated in Figure 2 by the arrow VI.

[0052] The steering gear 1 preferably has a hydraulic power assist. For this purpose, the ball recirculating nut 13 is sealed against the casing of the steering gear 1. The ball recirculating nut 13 can therefore function as a so-called hydraulic piston, or simply as a piston. Correspondingly, the ball recirculating steering mechanism has two opposing faces of the piston and separate oil chambers for the hydraulic steering assist. This allows a pressure difference to be created between the two sides of the ball recirculating nut 13 via the steering torque applied by the driver to the input shaft 3, for example by means of a rotary slide valve. This pressure difference allows the movement of the ball recirculating nut 13 to be assisted.

[0053] The described power steering group has several components sensitive to mechanical loads, in particular in the steering gear 1, in order to achieve the desired steering movements. These components must be protected, inter alia, against sudden movements, which may result, for example, from vibrations and ultimately from undesirable forces being introduced into the steering gear 1 via the wheels 17, 19. Such forces or loads or stresses in the system may arise, for example, when road irregularities lead to shocks being introduced via the wheels 17, 19. In this respect, it is particularly desired to damp or compensate such road-side shock pulses towards the steering gear 1 and thus prevent damage to the components of the steering gear 1. In particular, such harmful shocks may be transmitted in the illustrated embodiment to the wheels 17, 19, then via the thrust rod 7 and further to the steering gear 1, which may cause damage to the sensitive components of the steering gear 1.

[0054] In this case, measures are advantageously taken according to the invention. For this purpose, it is essential, first of all, that an adjustable absorption unit 23 is provided for absorbing the road shocks taken in via the wheels 17, 19 of the motor vehicle 10.

[0055] The adjustable absorption unit 23 can in this case be provided at various points or nodes of the power steering assembly, as can be seen, for example, in the exemplary embodiment shown in Figures 3 to 8. The adjustable absorption unit 23 is in this case preferably formed by at least one energy absorbing element and is adapted to convert kinetic energy at least partially into potential energy.

[0056] For this purpose, the adjustable absorption unit 23 is preferably integrated in the power steering assembly in such a way that the components of the power steering assembly adjacent to the adjustable absorption unit 23 can perform at least minimal mutual movements. For this purpose, the adjustable absorption unit 23 is preferably designed elastically or has a higher flexibility than the directly adjacent components. In this way, sudden movements of the components in the power steering assembly can be appropriately absorbed by the adjustable absorption unit 23 and spring-like damped or compensated by this absorption unit. The appropriately permitted relative movements of the components in the form of the adjustable absorption unit 23 serve for an appropriate energy conversion and thus compensation of the kinetic energy. In this way, the risk of damage to components in the steering gear 1 that are sensitive to mechanical loads is significantly reduced.

[0057] The adjustability of the adjustable absorption unit 23 is ensured in this case by a separate preload unit 24, which cooperates with the adjustable absorption unit 23, so that a preload force is applied to the adjustable absorption unit 23. In particular, the separate preload unit 24 serves to contract or compress the adjustable absorption unit 23 to a certain extent, so that the adjustable absorption unit 23 has a substantially smaller thickness dimension in the force flow direction of the forces to be compensated, which are introduced by roadside impacts, in the presence of the separate preload unit 24 compared to the state in which the separate preload unit 24 is not present or is not installed. This allows a suitable return force to be generated in the adjustable absorption unit 23.

[0058] The adjustable absorption unit 23 for absorbing or compensating for road shocks taken in via the wheels 17 of the motor vehicle 10 can be provided at various points in the power steering assembly. However, as is evident from the following exemplary embodiments in figures 3, 5, 6, 7 and 8, the adjustable absorption unit 23 can be particularly effectively integrated into the steering gear 1 or into its connection to the input shaft 3. Particularly preferably, in this case, the adjustable absorption unit 23 is integrated into the structure of the ball circulation nut 13 or into the interaction of the ball circulation nut with the input shaft 3 (see figures 3, 5), or into a series of supports of the input shaft 3 (see figure 6), or into the structure of the input shaft 3 itself (see figures 7, 8).

[0059] In Fig. 3a) the steering gear 1 is shown in a partially schematic manner, Fig. 3b) shows the section AA of Fig. 3a), Fig. 3a serves as a schematic overview (with different alternative reference signs in brackets), Fig. 5 as well as Fig. 6 basically show the section BB of Fig. 3a).

[0060] Figure 3b) partially shows a steering gear 1 of a corresponding power steering assembly according to the proposal, similar to the exemplary embodiment shown in Figure 5. In both exemplary embodiments, the steering gear 1 in each case has an input shaft 3 configured as a spindle 11, furthermore a ball-circulating nut 13 and also a rack 55 for converting the rotational movement (arrow III) of the input shaft 3 into a translational movement (double arrow IV).

[0061] To further transmit this translational movement (double arrow IV), the rack 55 has an outer toothed section 56, which provides the outer toothing 12. The toothed section 56 or the outer toothing 12 then engages with the sector shaft 5, which at least partially forms the output side 4 of the steering gear 1, and the translational movement (double arrow IV) further results in the desired rotational movement of the sector shaft 5 (see double arrow I in FIG. 1). Furthermore, the rack 55 forms a separate component with respect to the ball recirculating nut 13 located on the inside.

[0062] To compensate for road shocks, the adjustable absorption unit 23 of the power steering assembly according to FIGS. 3b) and 5 is arranged in such a way that the translational movement of the ball circulation nut 13 (double arrow IV) is transmitted via the adjustable absorption unit 23 to the toothed section 56 and vice versa, i.e. the translational movement of the toothed section 56 is also transmitted via the adjustable absorption unit 23 to the ball circulation nut 13. In this case, the adjustable absorption unit 23 is formed from at least one elastic element, i.e. in the embodiment according to FIG. 5 from two disc springs 57 or in the embodiment according to FIG. 3b) from two elastomers 58. In principle, a combination of elastomers, disc springs or coil springs is also possible.

[0063] The adjustable absorption unit 23 finally forms the joint between each ball recirculating nut 13 and a toothed section 56 which assumes the function of the outer toothing 12 for the toothed pair with the sector shaft 6 .

[0064] In the direction corresponding to the translational movement of the ball recirculation nut 13 (double arrow IV), the two components, i.e. the ball recirculation nut 13 and the rack 55 with the toothed section 56, are essentially designed to be movable relative to one another. In the rotational direction, i.e. the direction corresponding essentially to the rotational movement of the input shaft 3 (arrow III), the two components, i.e. the ball recirculation nut 13 and the rack 55 with the toothed section 56, are fixed against rotation relative to one another, i.e. the ball recirculation nut 13 cannot rotate in its seat in the rack 55. For this purpose, for example, a locking key can be provided for fixing. In FIG. 5, balls 60 of the ball recirculation steering mechanism are additionally shown, whereas in FIG. 3b) these are not explicitly shown.

[0065] Each adjustable absorption unit 23, which consists of at least one elastic element, in the illustrated embodiment allows a relative movement of the components adjacent to the adjustable absorption unit 23. This relative movement is possible in the axial direction. In this case, each adjustable absorption unit 23 is elastically compressed. In this way, the adjustable absorption unit 23 converts kinetic energy into potential energy in a defined manner in the event of excessively strong or sudden movements, for example in the event of a sudden rotation of the output shaft 6, which may be caused, for example, by a road impact. In this way, loads occurring inside the steering gear 1, which are caused by road impacts, can be advantageously compensated.

[0066] In both exemplary embodiments shown in Figures 3b) and 5, the ball nut 13 is received in a central hole with a flat surface 61 of the rack 55 and is fixed on the side opposite to the flat surface 61 by a cover 62. For this purpose, the cover 62 rests with its head-side annular support surface against the end face of the rack 55 which is located opposite the flat surface 61 of the central hole.

[0067] The covers 62 are each firmly connected to the rack 55, preferably via an end of the rack 55 facing away from the flat surface 61. Furthermore, the cover 62 according to the embodiment of FIG.

[0068] In the embodiment according to Fig. 3b), the elastomer 58 shown on the left bears with its left outer end face against the inner part of the head-side annular resting surface of the cover 62. And in the embodiment according to Fig. 5, the disc spring 57 shown on the right bears with its right outer face against the inner end face of the lead-in section 59 of the cover 62.

[0069] In the following, the compensation effect of the roadside sudden movements by the adjustable damping unit 23 in both exemplary embodiments shown in Figures 3b) and 5 will be explained. In particular, the situation of sudden movements of the output shaft 6 is concerned, which may lead to corresponding sudden linear movements of the rack 55, which engages with the output shaft 6 via the tooth pair (see references 12, 14, 56), in both directions indicated by the double arrow IV.

[0070] Basically, in both the embodiments of Fig. 3b) and Fig. 5, a sudden pivoting of the sector shaft 5 to the left and thus a sudden linear movement of the rack 55 is firstly compensated by the elastomer 58 shown on the right in the embodiment shown in Fig. 3b) and firstly by the disc spring 57 shown on the right in the embodiment shown in Fig. 5. The same applies analogously to a sudden linear movement of the respective ball recirculating nut 13 to the right, which leads to a compression of the right elastomer 58 or the right disc spring 57.

[0071] The opposite applies for the opposite direction of movement: in the event of a sudden movement of the respective ball-recirculating nut 13 to the left, the left elastomer 58 or the left disc spring 57 is compressed, in each case so that the desired compensation is achieved accordingly. The same applies for a sudden displacement of the output shaft 6, and thus of the sector toothing 14, to the right: a sudden linear movement of the respective rack 55 to the right causes the left elastomer 58 or the left disc spring 57 to be compressed, in each case so that the desired compensation is achieved accordingly.

[0072] In detail, the appropriate compensation of the sudden movements according to the embodiment of FIG. 3b) is performed as follows: a sudden movement of the rack 55 to the left, triggered for example by a sudden pivoting of the sector axis 5 to the left, firstly leads to a compression of the right-hand elastomer 58, which is accommodated in the central receiving part 25 of the rack 55, on the bottom of which is arranged firstly a compensation disk (described in more detail below) of the preload unit 24, against which the right-hand elastomer 58 also rests adjacently. In any case, the rack 55 transmits the sudden movement to the left via the bottom of the central receiving part 25 and the preload unit 24 to the right-hand elastomer 58 and then via the adjacent ring element 63 to the ball circulation nut 13.

[0073] The compensation of a sudden movement of the rack 55 to the left as described above also works in the opposite direction in terms of the force flow, i.e. when the cause of the sudden movement is not a displacement of the output shaft 6 and thus the sector toothing 14 to the left as described above, but rather a sudden movement of the ball circulation nut 13 to the right, since in this case the ball circulation nut 13 moving suddenly to the right will first compress the right-side elastomer 58 by the movement transmission via the ring element 63, which will then further compensate and transmit this movement in the desired way to the preload unit 24 or finally to the rack 55 and finally to the sector toothing 14 and the output shaft 6.

[0074] Also, in the case of a sudden movement of the rack 55 in the opposite direction, i.e. to the right (e.g. caused by a sudden displacement of the sector shaft 5 to the right), first the cover 62 shown on the left edge in Fig. 3b is moved to the right, since it is rigidly connected to the rack 55. This first causes the adjacent left elastomer 58 to be compressed, and then this movement is further transmitted to the ball recirculating nut 13 via the ring element 63.

[0075] The compensation described also works in the opposite direction in terms of the force flow, i.e. if the starting point is not a sudden movement of the rack 55 to the right, but a sudden movement of the ball circulation nut 13 to the left, since in this case the movement of the ball circulation nut 13 to the left first causes the adjacent left elastomer 58 to be compressed by the ring element 63, thus obtaining the desired compensation, before the forces and movements are further transmitted to the cover 62 and thus to the rack 55 and the output shaft 6.

[0076] 5 is carried out as follows: if, for example, the rack 55 is suddenly moved linearly to the left due to a sudden displacement of the sector axis 5 to the left, firstly the right-hand disc spring 57 is compressed. This occurs in that together with the rack 55 the cover 62, which is firmly connected to it, together with its lead-in section 59, is likewise moved to the left. This in turn firstly causes the right-hand disc spring 57 to be compressed, which in turn causes the desired compensation of the road side shock to be achieved, before finally transmitting this movement further to the ball circulation nut 13, which is connected to the left side of the right-hand disc spring 57.

[0077] The compensation of a sudden movement of the rack 55 to the left as described here also works in the opposite direction in terms of the force flow, i.e. when the cause of the sudden movement is not a displacement of the output shaft 6 and thus the sector toothing 14 to the left as described above, but rather a sudden movement of the ball circulation nut 13 to the right, since in this case the ball circulation nut 13 moving suddenly to the right first compresses the right-side disc spring 57, which then further compensates and transmits this movement to the cover 62, which transmits it to the rack 55 and finally to the sector toothing 14.

[0078] 5 to the right, first the left-hand disc spring 57 in the area of ​​the flat surface 61 is compressed, and then a corresponding load is transmitted further to the recirculating ball nut 13. Similarly, a sudden, jerk movement of the recirculating ball nut 13 to the left first causes the left-hand disc spring 57 to be compressed, and then finally a force and thus a movement is transmitted further to the rack 55 via the flat surface 61, which finally causes a displacement of the sector toothing 14 to the left and thus of the output shaft 6.

[0079] A particular advantage of the proposed power steering group is that a separate preload unit 24 is provided which cooperates with the adjustable absorption unit 23. The desired and defined preload force is applied to the adjustable absorption unit 23 from the separate preload unit 24.

[0080] In the illustrated embodiment according to Fig. 3b) and Fig. 5, in particular a first compensation disk 26 in each case is used as a separate preload unit 24. Fig. 4 essentially shows such a first compensation disk 26, which in this case has a first thickness d1. Furthermore, a further second compensation disk 27 is shown, which has a different, in this case smaller, thickness d2. The compensation disks 26, 27 each have a central opening 28 through which, in the assembled state, the ball recirculating nut 13 as well as the input shaft 3 (see Fig. 3b) or only the input shaft 3 (see Fig. 5) can extend.

[0081] Basically, in particular in order to appropriately adjust the desired preload force to be applied to the adjustable absorption unit 23, it is also possible, as shown purely by way of example in Fig. 3b) and Fig. 5, to provide as separate preload unit 24 not only a first compensation disk 26 but also several compensation disks 26, 27.

[0082] In particular, the separate preload units 24 in the described embodiment each have an end face 29 which serves as a contact surface with the respective first compensation disk 25, i.e. with the respective adjustable absorption unit 23, for the very adjustment, i.e. preloading, of the absorption unit 23. The first compensation disk 25 and the respective adjustable absorption unit 23 are arranged in abutment against one another via the contact surfaces.

[0083] Specifically, in FIG. 3b), the first compensation disk 26 is accommodated in the central accommodation 25 of the rack 55. Next to the central accommodation 25 on the side opposite the bottom face, the right elastomer 58 of the adjustable absorption unit 23 is arranged. The right elastomer 58 contacts via its right end face outer surface with the end face 29 (see FIG. 4) of the first compensation disk 26 of the separate preload unit 24.

[0084] In this way, the separate preload unit 24 with the first compensation disk 26 serves for a compression of the adjustable absorbent unit 23, or in particular of the right-hand elastomer 58, compared to the case in which the first compensation disk 26 is not provided, i.e. a preload force is applied to the adjustable absorbent unit 23, which in turn results in a return force in said adjustable absorbent unit 23.

[0085] In other words, the proposed method for adjusting a power steering group for electromechanical power steering of a motor vehicle 10 advantageously enables the power steering group, which may in particular be the power steering group described above, to be adjusted by first incorporating an adjustable absorption unit 23 for at least partially absorbing road shocks absorbed via the wheels 17 or 19 of the motor vehicle 10 into the steering movement conversion path of the entire power steering group.

[0086] According to the proposal, then, a separate preloading unit 24 is provided. In this case, as in the example of figures 3, 5 and 6, at least one first compensation disk 26 may be provided adjacent to the adjustable absorption unit 23 for preloading by appropriate compression of the adjustable absorption unit 23 as a separate preloading unit 24. Furthermore, it is also conceivable to provide a second compensation disk 27 adjacent to the adjustable absorption unit 23 for preloading by appropriate compression of the adjustable absorption unit 23 (see figure 4). In this case, the second compensation disk 27 may advantageously have a second thickness d2 different from the first thickness d1 of the first compensation disk 26.

[0087] With such a separate preload unit 24, essentially according to the proposed method, an individual desired and predetermined preload force is finally adjusted to the adjustable absorption unit 23, by the separate preload unit 24 compressing the adjustable absorption unit 23. In this case, the adjustable absorption unit 23 is compressed to a predetermined extent, which is selected via the thickness of the selected compensation disks 26, 27, for example via the first thickness d1 of the first compensation disk 26 (see FIG. 4), as is the case, for example, in the exemplary embodiment of FIGS. 3, 5 and 6. The degree of compression and thus the preload force can also be adjusted, for example, by the method step of screwing in the preload nut 30, which ensures an almost infinitely infinite adjustability (see FIGS. 7 and 8 and the corresponding description).

[0088] Figures 6, 7 and 8 show a further embodiment of an adjustable absorption unit 23 of the proposed power steering group. In the illustrated embodiment, the steering gear 1 has an input shaft 3 configured as a spindle 11 and a ball recirculating nut 13 for converting a rotational movement (arrow III) of the input shaft 3 into a translational movement (double arrow IV). In this case, the adjustable absorption unit 23 is at least partially configured as an elastic axial spindle bearing of the input shaft 3.

[0089] In the embodiment of Fig. 6, the adjustable absorption unit 23 of the input shaft 3, which is configured as an elastic axial spindle bearing, is formed by two elastic elements, in particular a disk spring 67 and a disk spring 68. In this case, the disk springs 67 and 68 are arranged in a casing 70 adjacent to the bearing assembly of the input shaft 3, in particular a double row angular contact ball bearing 69, for rotatably supporting the input shaft 3, in such a way that the bearing assembly of the input shaft 3 is accommodated in the casing 70 axially elastically via the disk springs. A separate preload unit 24 with a first compensation disk 26 is arranged between the left disk spring 67 and the angular contact ball bearing 69.

[0090] The illustrated adjustable absorption unit 23 in the form of two disc springs 67, 68 allows for an appropriate compensation of road shocks which may be introduced, for example, via the sector shaft 6 with the sector toothing 14. Together with the input shaft 3 (arrow III) therefore rotates a sleeve which surrounds the input shaft 3 as well as an inner race of an angular contact ball bearing 69. The outer race of the angular contact ball bearing 69 is also arranged in a casing 70 of the steering gear 1 so as to be non-rotatable but axially displaceable.

[0091] The adjustable absorption unit 23 in the form of disc springs 67, 68 furthermore bears on both sides, namely on the left side by the disc spring 67 and on the right side by the disc spring 68, against the outer race of the angular contact ball bearing 69. However, in this case the left-hand disc spring 67 does not bear directly against the outer race of the angular contact ball bearing 69, but only indirectly. Therefore, between the disc spring 67 and the outer race of the angular contact ball bearing 69 a first compensation disk 26 is furthermore arranged.

[0092] According to the proposal, in the event of a shock on the spindle side, the disk spring 67 shown on the left side is compressed in the case of a sudden movement of the input shaft 3 to the left, and the disk spring 68 shown on the right side in the case of a sudden movement of the input shaft 3 to the right, so that an axially damped movement occurs. The inner diameter of the disk springs 67, 68 is larger than the diameter of the sleeve or the input shaft 3. The illustrated adjustable absorption unit 23 thus again appropriately tolerates small relative movements of adjacent components of the power steering group, which in turn appropriately converts kinetic energy into potential energy and thus also serves to compensate for the shock on the road side. The separate preloading unit 24 with the first compensation disk 26 in this case also provides an appropriate preloading of the disk spring 67 shown here on the left side.

[0093] In the exemplary embodiment of Figures 7 and 8, the input shaft 3 configured as a spindle 11 is made in several parts by at least one spindle section 71 facing the ball recirculating nut 13 and an input section 72. In Figure 7a) the input shaft 3 is shown in a perspective view in the assembled state, and in Figure 7b) the corresponding input shaft 3 is shown in a front view in the direction of the arrow B in Figure 7a). In Figure 7c) the input shaft 3 is shown in this case in a longitudinal section corresponding to the section AA in Figure 7b). Figure 8 furthermore shows the same input shaft 3, but in an unassembled state, i.e. exploded into the individual components for the purposes of illustration.

[0094] The spindle section 71 and the input section 72 of the input shaft 3 are connected to one another in a manner that prevents them from rotating relative to one another. However, the spindle section 71 and the input section 72 are also connected to one another axially elastically via the adjustable absorption unit 23, which is formed as an elastic axial spindle bearing of the input shaft 3. In this case, the elastic axial spindle bearing is formed by elastic elements, i.e. in this case, on the one hand, by the package of ring springs 73 shown on the left and, on the other hand, by the package of ring springs 91 on the right.

[0095] For this purpose, the ring spring 73 shown on the left is arranged between the spindle section 71 and the input section 72. In particular, the ring spring 73 shown on the left is accommodated in a central receiving section 74 of the spindle section 71 with its end 75 facing the input section 72. On its side opposite the bottom of the receiving section 74, the ring spring 73 abuts against an end face 76 of a connecting thrust rod 77. This connecting thrust rod 77 is also accommodated to a large extent in the receiving section 74 of the spindle section 71, but its end 78 facing the input section 72 of the input shaft 3 protrudes from the receiving section 74 and thus from the end 75 of the spindle section 71.

[0096] The spindle section 71 of the input shaft 3 is connected to the input section 72 in a rotationally fixed manner by means of the connecting thrust rod 77. For this purpose, the connecting thrust rod 77 is accommodated in the receiving section 74 of the spindle section 71 and in the receiving section 79 of the input section 72, respectively, as explained, and is connected to the respective components in a rotationally fixed manner with respect to one another. For this purpose, on the one hand, a spindle-side connecting pin 80 is provided, which in the assembled state extends through both an elongated hole 81 in the spindle section 71 and a spindle-side through-hole 82 in the connecting thrust rod 77 (the through-hole 82 is shown only in FIG. 8 for the sake of clarity). For this purpose, the elongated hole 81 is also configured as a through-hole. For this purpose, the elongated hole 81 and the spindle-side through-hole 82 are aligned with one another in the assembled state. The elongated hole 81 has a greater axial extension in relation to the axis of the input shaft 3 than the spindle-side through-hole 82.

[0097] The connecting thrust rod 77 furthermore has an input-side through-hole 83 (the through-hole 83 is only shown in FIG. 8 for the sake of clarity) on the side facing the input section 72. Furthermore, the input section 72 of the input shaft 3 also has a through-hole 84, which in the assembled state is made to coincide with the input-side through-hole 83. The input-side connecting pin 85 also extends through both the through-hole 84 and the input-side through-hole 83 in the assembled state, so that the input section 72 and the connecting thrust rod 77 are connected to each other in a non-rotatable manner relative to one another. Furthermore, both the through-hole 84 and the input-side through-hole 83 have essentially the same diameter, and the input-side connecting pin 85 also connects the two components to one another in a form-locking manner when viewed in the axial direction, so that the input section 72 and the connecting thrust rod 77 are also connected to one another in an axially immovable manner.

[0098] With the above-mentioned arrangement, the input section 72 and the spindle section 71 are connected to each other by the spindle-side connecting pin 80, the input-side connecting pin 85 and the connecting thrust rod 77 in such a way that they cannot rotate relative to each other. Between the opposing ends of the two components, i.e. between the end 75 of the spindle section 71 facing the input section 72 and the end 86 of the input section 72 facing the spindle section 71, there is a sufficient movement clearance for a small relative axial movement between the spindle section 71 and the input section 72. The fact that the spindle-side connecting pin 80 is received with an axial clearance in the elongated bore 81 of the spindle section 71 also allows the connecting thrust rod 77 to move axially relative to the spindle section 71.

[0099] These small axial relative movements are utilized in a defined manner so that roadside shock pulses can be damped or compensated for. For this purpose, an adjustable absorption unit 23 in the form of a ring spring 73 shown on the left, which is placed against the end face 76 of the connecting thrust rod 77 and arranged in the receiving part 74 of the spindle section 71, and in the form of a package of ring springs 91 on the right, serves as the final function. The relative movements absorbed by the adjustable absorption unit 23 convert kinetic energy into potential energy in a defined manner, so that the roadside shocks are compensated for.

[0100] Furthermore, according to the proposal, a preload nut 30 is provided as a separate preload unit 24. The preload nut 30 partially surrounds the connecting thrust rod 77 from the outside. The ring spring 91 of the package of ring springs 91 shown on the right side is arranged next to the preload nut 30, viewed in the axial direction. In particular, the ring spring 91 shown on the right side is also arranged to surround the connecting thrust rod 77. In this case, the ring spring 91 is arranged on the left side, i.e. in the direction towards the spindle section 71, against the axial thrust rod abutment 31. The ring spring 91 is also arranged on the right side, i.e. in the direction towards the input section 72, against the axial end face 32 of the preload nut 30. This axial end face 32 of the preload nut 30 thus forms the contact surface between the ring spring 91 of the adjustable absorption unit 23 and the separate preload unit 24.

[0101] The parts of the separate preload unit 24 are, in the embodiment shown in Figs. 7 and 8, two mutually engaging threads: on the one hand, the preload nut 30 has a thread 33 on its outer circumferential surface (for the sake of clarity, only indicated by an arrow in Fig. 8); on the other hand, the spindle section 71 of the input shaft 3, which is formed partly hollow inside, also has a corresponding thread 34 which fits into the thread 33. This results in mutual engagement between the preload nut 30 as a first component and the spindle section 71 of the input shaft 3 as a second component. The separate preload unit 24 is thus arranged to cooperate with the adjustable absorption unit 23 such that a predefined preload force is adjustable via both components in the form of the preload nut 30 and the spindle section 71, which are brought into mutual engagement via the thread 33 and the corresponding thread 34. In this case, both components are essentially steplessly adjustable in this embodiment. This allows the axial position of the preload nut 30 to be arbitrarily changed, at least within a predetermined range, relative to the spindle section 71 of the input shaft 3 .

[0102] Depending on how far the preload nut 30 is recessed into the receiving portion 74 of the spindle section 71 (indicated by the dashed arrow in FIG. 8) and ultimately how far it is threaded into the corresponding thread 33, the right package of the ring spring 91 will be compressed to a greater or lesser extent.

[0103] In order to secure the preload nut 30 against re-rotation of the thread 33 on the corresponding thread 34, an anti-rotation means can be provided, as shown in this exemplary embodiment. For this purpose, in the exemplary embodiment shown in Figures 7 and 8, the preload nut has a groove 35. It is also possible to provide a number of grooves at different points on the circumference of the preload nut 30. For the purpose of the anti-rotation means, a fastening pin 36 is provided which, in the assembled state, engages both in the groove 35 of the preload nut 30 and in a peripheral hole 37 of the spindle section 71 of the input shaft 3 (see both Figures 7c and 8). Via the positive-locking reception of the fastening pin 36 in the hole 37 and also via the positive-locking reception of the fastening pin 36 in the groove 35, as viewed in the circumferential direction, the preload nut 30 is fixed against rotation, i.e. is connected to the spindle section 71 of the input shaft 3 in a substantially non-rotatable or rotationally immobile manner.

[0104] Viewed in the axial direction, the preload nut 30 is arranged around the inner connecting thrust rod 77 such that the preload nut 30 is axially slidable relative to the connecting thrust rod 77, i.e. the preload nut 30 can change its axial position relative to the connecting thrust rod 77. Thus, despite the fact that the position of the preload nut 30 is fixed axially and circumferentially relative to the spindle section 71, as already explained in detail, at least a small axial relative movement of the spindle section 71 of the input shaft 3 is possible relative to the connecting thrust rod 77 and thus relative to the input section 72 of the input shaft 3. The axial movement play is also obtained by the fact that the groove 35 is formed as an elongated hole in which the fixing pin 36 can reciprocate to a certain extent along the axial direction.

[0105] The preload nut 30 abuts with its axial end face 32 against the axial abutment face 38 of the ring spring 91, compressing the ring spring and thus applying a desired predetermined preload force to the adjustable absorption unit 23 by compression of the ring spring 91.

[0106] In other words, according to the proposed method for adjusting a power steering group, which is partially shown in Figures 7 and 8, it is assumed that as a separate preload unit 24, a preload nut 30 is provided adjacent to the adjustable absorption unit 23, specifically in the right-hand package of the ring spring 91, in particular adjacent to the axial abutment surface 38 of this ring spring 91, in order to preload the adjustable absorption unit 23 by a suitable compression. In this case, a first component of the separate preload unit 24 in the form of the preload nut 30, which has a thread 33, and a second component in the form of the spindle section 71 of the input shaft 3, which engages with the first component and has a corresponding thread 34, are rotated relative to one another to adjust a preload force that is set. In this case, the distance by which the thread 33 is screwed into the corresponding thread 34 determines the degree of compression of the ring spring 91 and thus the adjusted preload force.

[0107] With the illustrated power steering assembly, road shocks are advantageously compensated for as follows: the input section 72 of the input shaft 3 is supported axially and radially at its position. Shocks acting on the spindle 11 are damped or compensated for by the package of the ring spring 73 or 91. If, for example, the spindle 11 is moved towards the right in the direction of the input section 72, first the left package of the ring spring 73 is compressed, after which this movement is finally transmitted further to the connecting thrust rod 77 and thus to the input section 72 of the input shaft 3.

[0108] For example, a shock resulting in a sudden movement of the input section 72 of the input shaft 3 to the left, i.e. towards the spindle section 71, or to the right, i.e. away from the spindle section 71, is compensated as follows: a movement of the input section 72 to the left also moves the connecting thrust rod 77 towards the left, which in turn firstly compresses the left-hand package of the ring spring 73, which is then further transmitted to the spindle section 71. Conversely, i.e. when the input section 72 is moved towards the right, also the connecting thrust rod 77 moves towards the right, which in turn firstly compresses the right-hand package of the ring spring 91 via the axial thrust rod abutment 31. This movement is then further transmitted via the axial end face 32 of the preload nut 30 right to the preload nut 30 and thus also to the spindle section 71, which is rigidly connected to the preload nut 30.

[0109] Finally, there is also an externally arranged protective sleeve 87, which also has a spindle-side through-hole 88 and an input-side through-hole 89. The spindle-side through-hole 88 corresponds to the spindle-side through-hole 82 of the connecting thrust rod 77 as well as to the elongated hole 81 of the spindle section 71. Furthermore, the spindle-side connecting pin 80 also extends through the spindle-side through-hole 88 of the protective sleeve 87. The input-side through-hole 89 also corresponds to the input-side through-hole 83 of the connecting thrust rod 77 as well as to the through-hole 84 in the input section 72. Furthermore, the input-side connecting pin 85 also extends through the spindle-side through-hole 89 of the protective sleeve 87.

[0110] The protective sleeve therefore externally surrounds in particular the connecting thrust rod 77 and also the axial free space between the spindle section 71 and the input section 72. Furthermore, the protective sleeve also provides an external guide for both components of the input shaft 3 which are formed separately from one another, namely the spindle section 71 and the input section 72. [Explanation of symbols]

[0111] 1 Steering gear 2 (Steering gear 1) input side 3 Input shaft 4 (Steering gear 1) output side 5 Sector Axis 6 Output shaft 7 Thrust Rod 8 Pitman Arm 9 Ball Joint 10. Automobiles 11 Spindle 12 (of ball recirculating nut 13) outer tooth row 13 Ball Circulation Nut 14 Sector tooth row (sector axis 5) 15 Steering Wheel 16 Steering lever 17,19 (Car 10) Wheels 18 Steering shaft 20 Steering arm 21 Tie rod 22 (Car 10) Frame 23 Adjustable Absorption Unit 24 Preload Unit 25 (Rack 55) central storage area 26 First Compensation Disk 27 Second Compensation Disk 28 Aperture 29 (of preload unit 24) end face 30 Preload Nut 31 Axial thrust rod abutment 32 (end face of preload nut 30) 33 Threads 34 Corresponding thread 35 Groove 36 Fixing pin 37 (of spindle section 71) peripheral hole 38 (of ring spring 91) axial contact surface 55 racks 56 Dentition 57 Disc spring 58 Elastomer 59 (of cover 61) axially extending lead-in section 60 Ball 61 (flat surface of central hole in rack 55) 62 Cover 63 Ring Element 67,68 Disc spring 69 (two-row) angular contact ball bearing 70 (Steering gear) casing 71 (input shaft 3) spindle segment 72 (Input axis 3) Input section 73 Ring Spring 74 (spindle section 71) receiving portion 75 (facing the input section 72) end of the spindle section 71 End face of 76 (connecting thrust rod 77) 77 Connecting thrust rod 78 (facing the input section 72) the end of the connecting thrust rod 77 79 (Input section 72) Receptacle 80 Spindle side connection pin 81 (spindle section 71) slot 82 (connection thrust rod 77) through hole on the spindle side 83 (connecting thrust rod 77) input side through hole 84 (input section 72) through hole 85 Input side connection pin 86 (facing the spindle section 71) end of the input section 72 87 Protective sleeve 88 (Protective sleeve) through hole on spindle side 89 (Protective sleeve) input side through hole 91 Ring spring

Claims

1. A power steering arrangement for electromechanical power steering of a motor vehicle (10), comprising: a steering gear (1) configured to transmit a rotational motion (III) introduced by a steering generator from an input side (2) of the steering gear (1) to an output side (4) of the steering gear (1), the power steering group is configured to convert a movement (I) derived from the output side (4) of the steering gear (1) into a rotational movement (V) of at least one wheel (17; 19) of the vehicle (10) about a steering axis (18), In the power steering configuration group, an adjustable absorption unit (23) is provided for at least partially absorbing road side shocks taken up through the wheels (17; 19) of the vehicle (10), and a separate preload unit (24) is provided, the separate preload unit (24) being arranged to cooperate with the adjustable absorption unit (23) such that a preload force is applied to the adjustable absorption unit (23), 10. A power steering assembly, comprising: a first compensation disc (26) and a second compensation disc (28) disposed in said first compensation disc (28).

2. 2. The power steering group of claim 1, wherein the separate preload unit (24) further comprises at least one second compensation disc (27).

3. 3. The power steering group of claim 1 or 2, wherein said separate preload unit (24) includes a preload nut (30).

4. 4. A power steering group according to claim 1, wherein the separate preload unit (24) is adapted to cooperate with the adjustable absorption unit (23) in such a way that a preload force is adjustable via two components which are brought into engagement with one another via a screw thread (33) and a corresponding screw thread (34).

5. 5. A power steering assembly according to claim 1, wherein the separate preload unit (24) and the adjustable absorption unit (23) are at least partially slidable relative to one another in the axial direction in the assembled state.

6. 6. Power steering group according to claim 1, characterized in that the separate preload unit (24) is fixed against circumferential rotation in the assembled state.

7. 7. A power steering assembly according to claim 1, wherein the separate preload unit (24) has an end face (29; 32) which forms a contact surface for directly abutting the adjustable absorption unit (23) in order to apply the predetermined preload force to the adjustable absorption unit (23).

8. A method for adjusting a power steering group for electromechanical power steering of a motor vehicle (10), comprising: an adjustable absorption unit (23) for at least partially absorbing road shocks taken up via the wheels (17; 19) of the vehicle (10) is integrated in the path of translation of the steering movement of the entire power steering assembly, Further providing a separate preload unit (24); Finally, the separate preload unit (24) compresses the adjustable absorbent unit (23) thereby adjusting the predetermined preload force applied to the adjustable absorbent unit (23); 2. The method according to claim 1, wherein as said separate preload unit (24), at least one first compensation disk (26) is provided adjacent to said adjustable absorption unit (23) for preloading by suitable compression of said adjustable absorption unit (23).

9. 9. The method of claim 8, further comprising providing a second compensation disk (27) adjacent said adjustable absorption unit (23) for preloading said adjustable absorption unit (23) by suitable compression.

10. 10. The method according to claim 8 or 9, wherein as the separate preload unit (24), a preload nut (30) is provided adjacent to the adjustable absorption unit (23) for preloading by appropriate compression of the adjustable absorption unit (23).

11. 11. The method according to claim 8, further comprising adjusting the predetermined preload force by rotating a first component of the separate preload unit (24) having a screw thread (33) relative to a second component engaging the first component and having a corresponding screw thread (34).

12. Method according to any one of claims 8 to 11, characterized in that the separate preload unit (24) is finally fixed against circumferential rotation.

13. 13. The method according to claim 12, wherein the fixing is performed by providing a fixing pin (36) which engages in a circumferentially positive manner in the groove (35).

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