Power steering assembly with targeted and adjustable compensation of road-side shock impulses to the steering gear, as well as a method for setting up a power steering assembly.

Description

[0001] The present invention relates to a power steering assembly for an electromechanical power steering system of motor vehicles according to the preamble of claim 1. Furthermore, the invention relates to a method for setting up a power steering assembly for an electromechanical power steering system of motor vehicles according to the preamble of claim 9.

[0002] Power steering assemblies are known in a wide variety from the prior art. These assemblies, particularly the steering gear integrated within them, comprise several components sensitive to mechanical stress. For example, the steering gear typically includes a spindle and a ball screw nut with balls or a ball chain, as well as gear pairings, such as external teeth on the ball screw nut engaging with segmented teeth on a segmented shaft. These components are especially sensitive to sudden, applied mechanical forces or loads.

[0003] One source of such sudden loads is, for example, road-related impacts. Uneven road surfaces, for instance, can cause shocks in the vehicle, which can lead to unwanted sudden movements in a power steering assembly. In current technology, the shock absorber system of the wheel suspension is typically the only component responsible for compensating for road-related impacts. However, such a system could be improved to more effectively compensate for or absorb loads or stresses introduced into sensitive components of a steering gear.

[0004] This problem is illustrated below using the example of a commercial vehicle, although this is not to be understood as limiting the scope of the present invention. Commercial vehicles regularly have power steering assemblies with a recirculating ball steering system. For this purpose, the power steering assembly includes a steering gear which is configured to transmit a rotary motion initiated by a steering sensor, such as a steering wheel, via an input side of the steering gear to an output side of the steering gear. The input side can be formed, for example, by an input shaft and the output side by an output shaft, for example, in the form of a segmented shaft.Within the steering gear, the applied rotary motion of the input shaft can be converted as intended by means of a spindle-shaped input shaft. This spindle motion causes a translational movement of a ball screw nut surrounding the spindle section. This translational movement can also be described as the axial movement of the ball screw nut or the piston. The ball screw nut is typically equipped with external teeth. These external teeth mesh with the segmented teeth of the segmented shaft, converting the translational movement of the ball screw nut into a rotary movement of the segmented shaft, or output shaft, which is then transmitted at the output side of the steering gear. A steering column lever is typically connected to this output side, and a pushrod is articulated to this lever.The pushrod of the power steering assembly ultimately receives the rotary motion originating from the output side of the steering gear and, as intended, performs a translational pushrod movement – ​​also known as axial movement – ​​during a steering maneuver. This translational pushrod movement causes a intended rotary movement of at least one wheel of the vehicle around a steering axis.

[0005] In power steering assemblies constructed in this way, road-side impact impulses can lead to sudden movements in many of the aforementioned components of the power steering assembly, which in turn result in undesirable loads or stresses introduced into the interior of the steering gear. To date, such forces, loads, and stresses in state-of-the-art power steering assemblies are generally compensated primarily by the hydraulics of the power steering assemblies themselves.

[0006] Furthermore, the prior art often requires significant effort for the design of such power steering assemblies for each specific application. Highly precise and complex design and manufacturing processes are frequently necessary to correctly define the switching point of any damping elements used in a steering gear or power steering assembly. This leads to the problem that if the individual components are not correctly designed or manufactured, steering response can become less direct. To avoid such negative effects, such as indirect steering, a time-consuming and costly, application-specific design of the steering gears for the power steering assemblies is required. For these reasons, the corresponding methods for setting up a power steering assembly are very complex in the prior art.

[0007] Specifically, a steering device is known from the prior art in US patent 1,350,285 A, comprising a T-lever and cooperating springs, for reducing accidents when the front wheels collide with stones or obstacles on the road. Furthermore, a steering device is known from CH patent 344,316 A, comprising a shock- and noise-damping mechanism between the steering linkage and the steering gear. DE 20 60 017 A1 describes a vehicle steering system with compression springs axially integrated between the steering worm and the housing to dampen shocks transmitted from the road surface and prevent them from being transferred to the steering wheel.

[0008] Against this background, the invention aims to further develop a power steering assembly of the type mentioned above in such a way that the steering gear is better protected against road-related impacts. Furthermore, the effort required for design and manufacturing should be reduced, and indirect steering behavior should be avoided in the simplest possible way. The invention therefore also aims to provide a method for setting up a power steering assembly for an electromechanical power steering system in motor vehicles that requires less effort to effectively avoid indirect steering behavior.

[0009] This problem is solved by a power steering assembly having the features of the characterizing part of claim 1. The problem is further solved by a method having the features of the characterizing part of claim 9. Further, particularly advantageous embodiments of the invention are disclosed in the dependent claims.

[0010] The fundamental principle is to design the power steering assembly in such a way that it incorporates a dedicated, adjustable absorption unit specifically designed to protect the steering gear from loads and stresses resulting from road-related impacts. This adjustable absorption unit compensates for these movements and the resulting loads by converting kinetic energy into potential energy. This reduces forces and loads within the steering gear that, without the adjustable absorption unit, would be essentially undamped or not attenuated at all, or would only be dampened or compensated for by the power steering system's hydraulics.The adjustable absorption unit is designed to convert kinetic energy into potential energy and ensures that vibrations are selectively dampened or absorbed. Preferably, the adjustable absorption unit is elastically designed for this purpose. The adjustable absorption unit is advantageously configured to allow at least small relative movements of the adjacent components of the power steering assembly.

[0011] Furthermore, a key aspect of the invention is the realization that the disadvantages described in the prior art can be avoided by providing an additional separate preload unit, which can be used to adjust the adjustable absorption unit. This allows a preload force in the adjustable absorption unit to be individually adapted to the respective application by simply compressing the adjustable absorption unit by a desired amount using the separate preload unit. This enables the adjustable absorption unit to be precisely adjusted to effectively prevent indirect steering behavior. This also significantly reduces the effort involved in the manufacturing processes and, in particular, the design of power steering assemblies.This eliminates the need for highly precise and complex design and manufacturing processes to correctly define the switching point of the adjustable absorption unit. As a result, even if components are not correctly designed or manufactured, indirect steering behavior can be effectively avoided, since the separate preload unit simply preloads the adjustable absorption unit by the desired amount.

[0012] The proposed power steering assembly for an electromechanical power steering system of motor vehicles, which may in particular be a power steering assembly for an electromechanical power steering system of commercial vehicles, comprises a steering gear. This steering gear is configured to transmit a rotary motion initiated by a steering sensor via an input side of the steering gear to an output side of the steering gear. The steering sensor may in particular be a steering wheel. The initiated rotary motion may be initiated via an input shaft of the steering gear. According to the proposal, the power steering assembly is configured to convert a motion originating from the output side of the steering gear into a rotary motion of at least one wheel of the motor vehicle about a steering axis.

[0013] The proposed power steering assembly is characterized by the inclusion of an adjustable absorption unit for at least partial absorption of road-related shocks transmitted via the vehicle's wheel. Furthermore, the proposal includes a separate preload unit, which is configured to interact with the adjustable absorption unit in such a way that a predetermined preload force is exerted on the adjustable absorption unit.

[0014] The proposed method for setting up a power steering assembly for an electromechanical power steering system of motor vehicles is a method for setting up a proposed power steering assembly as described above or below, specifically a power steering assembly according to one of claims 1 to 8.

[0015] The proposed method is characterized in that an adjustable absorption unit for at least partial absorption of road-related shocks transmitted via the vehicle's wheel is integrated into the conversion circuit of the steering movement of the entire power steering assembly. Furthermore, a separate preload unit is provided, and finally, a predetermined preload force is set, which is exerted on the adjustable absorption unit by the separate preload unit compressing the adjustable absorption unit.

[0016] In principle, the adjustable absorption unit can be compressed, at least partially (for example, at least one elastic element or a group of elastic elements if the adjustable absorption unit is formed by several differently arranged elastic elements), by any desired predetermined amount. "Any amount" naturally refers to a dimension within certain limits, i.e., within a range adapted to the available installation space. Specifically, for example, either one or more compensating washers of a specific thickness can be provided, which compress the adjustable absorption unit by that thickness.Typically, the adjustable absorption unit is simply compressed axially by the separate preloading unit, since the installation space available for the adjustable absorption unit is reduced by the use of a compensating washer. Alternatively, preload nuts can be used as a separate preloading unit, or other components with a thread engaging a mating thread can be used. In this case, the degree of compression of the adjustable absorption unit can be advantageously adjusted by screwing the threaded component into the mating thread by a desired amount, thus compressing the adjustable absorption unit by that amount.

[0017] In principle, the proposed adjustable absorption unit is integrated into the power steering assembly and is a component thereof. For example, the absorption unit can be integrated into the conversion chain of the steering movement within the entire assembly, i.e., from the steering sensor (e.g., the steering wheel) towards the wheel being steered, between the input side of the steering gear and the pushrod responsible for steering.

[0018] As a result, sudden movements in the proposed power steering assembly are advantageously compensated for by the adjustable absorption unit, and the resulting loads are at least partially absorbed. In this way, the shock impulses, or the resulting forces, transmitted from the road, either via the wheel to, for example, a pushrod and possibly to other components of the power steering assembly connected to the pushrod, or via the steering gear housing, can be selectively dampened or compensated.This means that the hydraulics of the power steering assembly are no longer solely responsible for compensating for road-side shock impulses, thus better protecting the steering gear of the proposed power steering assembly, and in particular the sensitive components located within the steering gear, from road-side shock impulses.

[0019] The input side of the steering gear is generally formed by an input shaft, which is at least partially designed as a spindle. The output side of the steering gear can, in turn, typically be formed by an output shaft, preferably a segmented shaft. The movement originating from the output side of the steering gear can be transmitted directly or indirectly from the output side, for example via the segmented shaft, to, for instance, a pushrod. The output shaft can be rigidly connected, in particular rotationally fixed, to a steering column lever. The steering column lever can then receive a rotary movement of the output shaft and also execute a rotary movement. Furthermore, a ball joint can be provided, for example, at the end of the steering column lever facing away from the output shaft, connecting the steering column lever to the pushrod.The ball joint can therefore ensure that the movement originating from the output side of the steering gear, in the form of the rotary movement of the output shaft and thus the rotary movement of the steering column lever, is transferred to the pushrod to carry out a translational pushrod movement.

[0020] In such an embodiment with a push rod, the push rod is therefore provided to receive the movement originating from the output side of the steering gear and to carry out a translational push rod movement, wherein the push rod is arranged in such a way that the translational push rod movement causes the rotational movement of at least one wheel of the motor vehicle about the steering axis.

[0021] The adjustable absorption unit can advantageously be integrated into the steering gear and preferably positioned between the input and output sides. The adjustable absorption unit can be designed as an elastic element, such as an elastomer or spring assembly, or it can consist of multiple elastic elements. Relative movements of adjacent components can be permitted by the elastic element(s) of the adjustable absorption unit, allowing kinetic energy to be absorbed and thus achieving the desired compensation effect.In principle, it is preferably provided that the adjustable absorption unit is formed from at least one elastic element, in particular from at least one disc spring and / or from at least one coil spring and / or from at least one elastomer.

[0022] According to one proposed alternative of the invention, the steering gear advantageously comprises an input shaft designed as a spindle and a ball screw nut for converting the rotary motion of the input shaft into a translational motion, with a toothed section surrounding the ball screw nut on the outside. The adjustable absorption unit is arranged such that the translational motion of the ball screw nut is transmitted to the toothed section via the adjustable absorption unit and vice versa. In this way, road-side shock impulses can be particularly advantageously compensated effectively within the steering gear itself.

[0023] It is also advantageously proposed that the steering gear has an input shaft designed as a spindle and a ball screw nut for converting the rotary motion of the input shaft into a translational motion. According to two further alternatives of the invention, the adjustable absorption unit is at least partially formed as an axial elastic spindle bearing for the input shaft. In this way, road-side shock impulses can be particularly advantageously compensated effectively on the input side of the steering gear.

[0024] According to one of these two further alternatives of the invention, it is advantageously provided that the adjustable absorption unit, formed as an axial elastic spindle bearing of the input shaft, is formed by at least one elastic element, in particular by at least one disc spring, wherein the at least one elastic element is arranged adjacent to a bearing arrangement of the input shaft for rotatable mounting of the input shaft in a housing such that the bearing arrangement of the input shaft is received axially elastically in the housing via the at least one elastic element. The at least one elastic element is arranged adjacent to an outer ring of the bearing arrangement of the input shaft in the housing. "Axially elastic" is to be understood in particular as referring axially to the input shaft.The present invention has surprisingly demonstrated that, despite the additional design effort required to supplement the bearing arrangement of the input shaft, the overall efficiency of the power steering assembly can still be increased. This is because sensitive components of the steering gear are advantageously protected from road-related impacts, thus increasing its service life.

[0025] According to the further two alternatives of the invention, it is advantageously provided that the input shaft designed as a spindle is formed in multiple parts by at least one spindle section facing the ball screw nut and an input section, and that the spindle section and the input section are rotationally fixed but axially elastically connected to each other via the adjustable absorption unit formed as an axial elastic spindle bearing of the input shaft, preferably in the form of at least one elastic element, particularly preferably in the form of ring springs.The present invention has surprisingly demonstrated that, despite the additional design effort involved in dividing the input shaft and, more importantly, the resulting weakening of the input shaft and thus the entire power steering assembly, the service life of the entire assembly can still be increased. This is because sensitive components of the steering gear are advantageously protected from road-related impacts.

[0026] A preferred embodiment of the power steering assembly is characterized in that the separate preload unit comprises at least one first compensating washer. This allows the preload force on the adjustable absorption unit to be individually configured in a particularly simple manner. Individual adaptability to the specific application of the power steering assembly is possible without requiring complex design of the individual components, especially the elastic elements of the adjustable absorption unit. Furthermore, inaccuracies in the manufacturing of the power steering assembly can be effectively compensated. Preferably, the first compensating washer forms a direct contact surface as a bearing surface with the adjustable absorption unit or some of its elastic elements.

[0027] Additionally, it is preferably provided that the separate preload unit further comprises at least one second compensating washer. In particular, the second compensating washer can have a second thickness that differs from the first compensating washer's thickness. This allows for particularly easy adjustments to the specific application of the power steering assembly. Individual adaptability to the application of the power steering assembly is possible without having to undertake a complex design of the individual components, especially the elastic elements of the adjustable absorption unit. Inaccuracies in the manufacturing of the power steering assembly can also be effectively compensated. Preferably, the first compensating washer and the second compensating washer are arranged directly adjacent to each other.

[0028] According to a further embodiment of the power steering assembly, the separate preload unit includes a preload nut. This allows for particularly simple individual adjustment of the preload force on the adjustable absorption unit. Individual adaptation to the specific application of the power steering assembly is possible without the need for complex design of the individual components, especially the elastic elements of the adjustable absorption unit. Furthermore, inaccuracies in the manufacturing of the power steering assembly can be effectively compensated for. Preferably, the preload nut can simply be screwed further into the corresponding mating thread to increase the preload force. Even more preferably, the preload nut has an end face that forms a direct contact surface with the adjustable absorption unit or some of its elastic elements.

[0029] According to a further embodiment of the power steering assembly, the separate preload unit is configured to interact with the adjustable absorption unit in such a way that the predetermined preload force can be adjusted, preferably essentially steplessly, by means of two components that engage with each other via threads and mating threads. "Essentially stepless" means that arbitrarily high or low values ​​cannot be assumed; that is, the components cannot be rotated relative to each other arbitrarily far, but rather can be rotated within a certain range. Furthermore, small jumps in the resulting preload force can occur when the components are rotated relative to each other. Therefore, the term "stepless" should not be understood as absolute. This allows for simple individual adjustment of the preload force.

[0030] According to another embodiment of the power steering assembly, the separate preload unit and the adjustable absorption unit are designed to be at least partially displaceable axially relative to each other when assembled. This ensures effective compensation of road shocks.

[0031] According to a further embodiment of the power steering assembly, the separate preload unit is secured against circumferential rotation in the assembled state, in particular by a locking bolt engaging in a groove. This ensures a uniform compensation effect of the adjustable absorption unit. Unwanted adjustment of the preload force is effectively prevented.

[0032] According to a further embodiment of the power steering assembly, the separate preload unit has an end face which forms a contact surface for direct contact with the adjustable absorption unit in order to exert the predetermined preload force on it. This ensures effective and uniform transmission of the preload force from the preload unit to the adjustable absorption unit.

[0033] A preferred embodiment of the method for setting up the power steering assembly is characterized in that at least one first compensating washer is provided as a separate preload unit adjacent to the adjustable absorption unit, where the preload is applied by targeted compression of the adjustable absorption unit. This allows the preload force acting on the adjustable absorption unit to be individually configured in a particularly simple manner. Individual adaptation to the specific application of the power steering assembly is possible without the need for complex design of the individual components, especially the elastic elements of the adjustable absorption unit. Furthermore, inaccuracies in the manufacturing of the power steering assembly can be effectively compensated for. The method is therefore efficient and simple.Preferably, the first compensating disc forms a direct contact surface as a bearing surface to the adjustable absorption unit or some elastic elements thereof.

[0034] Preferably, a second compensating washer is provided adjacent to the adjustable absorption unit, adjacent to the preload achieved by targeted compression of the adjustable absorption unit. This second compensating washer preferably has a thickness that differs from the thickness of the first compensating washer. This allows for particularly easy adjustments to the specific application of the power steering assembly. Individual adaptability to the application of the power steering assembly is possible without requiring complex design of the individual components, especially the elastic elements of the adjustable absorption unit. Furthermore, inaccuracies in the manufacturing of the power steering assembly can be effectively compensated. Preferably, the first and second compensating washer are arranged directly adjacent to each other.

[0035] According to a further embodiment of the method, a preload nut is provided as a separate preloading unit adjacent to the adjustable absorption unit, where the preload is applied by targeted compression of the adjustable absorption unit. This allows the preload force on the adjustable absorption unit to be individually adjusted in a particularly simple manner. Individual adaptation to the specific application of the power steering assembly is possible without the need for complex design of the individual components, especially the elastic elements of the adjustable absorption unit. Furthermore, inaccuracies in the manufacturing of the power steering assembly can be effectively compensated for. Preferably, the preload nut can simply be screwed further into the corresponding mating thread to increase the preload force.Furthermore, preferably the preload nut has an end face that forms a direct contact surface as a bearing surface to the adjustable absorption unit or some elastic elements thereof.

[0036] According to a further embodiment of the method, the predetermined preload force is set by rotating a threaded first component of the separate preload unit and a mating threaded second component relative to each other. Preferably, the preload force can thus be adjusted essentially steplessly. "Essentially stepless" means that arbitrarily high or low values ​​cannot be assumed; that is, the components cannot be rotated arbitrarily far relative to each other, but rather can be rotated within a certain range. Furthermore, small jumps in the resulting preload force can occur when the components are rotated relative to each other. Therefore, the term "stepless" should not be understood as absolute. This allows for simple individual adjustment of the preload force.The more the components are twisted against each other, the higher the degree of compression of the adjustable absorption unit, i.e., the higher the preload force acting on it.

[0037] According to a further embodiment of the method, it is provided that the separate preload unit is finally secured against rotation in the circumferential direction.

[0038] Additionally, it may preferably be provided that the securing is effected by providing a locking bolt that engages positively in a groove in the circumferential direction.

[0039] Effective compensation of road-side impacts is thus ensured. The safety of a consistent compensation effect from the adjustable absorption unit is guaranteed, as unwanted adjustments to the preload force are effectively prevented.

[0040] The features and resulting advantages described above and below relating to the proposed power steering assembly are, where technically feasible, transferable to the proposed method, and vice versa.

[0041] Further features and advantages of the invention will become apparent from the claims and the following description of exemplary embodiments of the invention, which are not to be understood as limiting and are explained in more detail below with reference to the drawing. This drawing shows: Fig. 1 a schematic representation of a steering gear, Fig. 2 a schematic representation of a motor vehicle with a steering gear made of Fig. 1 , Fig. 3 partially shows a steering gear of a proposed power steering assembly in a sectional view, in Fig. 3 a) in a schematic view, as well as in Fig. 3 b) in a section view AA from Fig. 3 a), Fig. 4 separate preload units designed as compensating discs, Fig. 5 partially a steering gear of another proposed power steering assembly in a sectional view, basically according to section line BB from Fig. 3 a) , Fig. 6 partially shows a steering gear of a proposed power steering assembly in a sectional view, basically according to section line BB. Fig. 3 a) , Fig. 7 an input shaft of a proposed power steering assembly in Fig. 7 a) in a perspective view in an assembled state, in Fig. 7 b) in a front view from direction B Fig. 7 a) , as well as in Fig. 7 c) in a sectional view according to section AA in Fig. 7 b) , and Fig. 8 the input shaft of the proposed power steering assembly made of Fig. 7 a) in a view of all individual parts in an unassembled state.

[0042] In Fig. 1A power steering assembly for an electromechanical power steering system in motor vehicles is shown schematically. The power steering assembly includes a steering gear 1. A steering input from a steering sensor, such as a steering wheel (in the steering gear 1), is transmitted via the steering gear 1. Fig. 1 (not shown), the steering movement performed by the driver of the motor vehicle is converted. For this purpose, a rotary movement initiated via an input side 2 of the steering gear 1, in the specific case shown 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 again transmitted, in this specific case a rotary movement of an output shaft 6 of the steering gear 1 designed as a segmented shaft 5. This movement transmitted at the output side 4, which in this case is the rotary movement indicated by two curved double arrows I, is ultimately received in this non-limiting embodiment by a pushrod 7 of the power steering assembly. The pushrod 7 thus performs a translational pushrod movement. The translational pushrod movement of the pushrod 7 is a linear movement, which in Fig. 1 characterized by a double arrow II, and ultimately results in at least one wheel of the motor vehicle rotating around a steering axis (in Fig. 1 (not shown), so that as a result the motor vehicle performs the desired curve.

[0044] To convert the rotary motion (double arrows I) emitted at the output side 4 into the desired translational pushrod motion (double arrow II) of the pushrod 7, the illustrated servo steering assembly has a steering column lever 8 and a joint in the form of a ball joint 9 connecting the steering column lever 8 to the pushrod 7.

[0045] The following description of a typical steering maneuver refers to both Fig. 1 as well as on Fig. 2 , which shows a schematic representation of a motor vehicle 10 from below with a power steering assembly with the steering gear 1 made of Fig. 1 shows, referenced.

[0046] For motor vehicles 10 in the form of commercial vehicles, recirculating ball steering gears, also known as recirculating ball steering systems (abbreviated: KUL), are generally used. The kinematics of such an arrangement are particularly advantageous for commercial vehicles, as these usually have a rigid front axle. If the trailing arms of the front axle and the pushrod are approximately the same length and arranged essentially parallel to each other, they form a parallelogram. As a result, suspension movements of the front axle have little or no effect. If the steering gear 1 is mounted rigidly to the frame, length compensation in the steering column can be achieved, for example, by a corresponding relative movement between the frame of the motor vehicle 10 and a driver's cab. Since commercial vehicles are an application for which the proposed power steering assembly is particularly suitable, the invention is explained below using the example of a recirculating ball steering system.

[0047] The steering gear 1 comprises an input shaft 3, which is partially designed as a spindle 11, and a ball screw nut 13, which has external teeth 12 and is arranged in the area of ​​the spindle 11. A segment toothing 14 engages with the external teeth 12. The segment toothing 14 and the external teeth 12 are arranged in a meshing configuration. The segment toothing 14 is also rotationally fixed, i.e., rotationally fixed, to the output shaft 6, which is therefore designed as a segment shaft 5. The steering arm 8 is in turn rotationally fixed, i.e., rotationally fixed, to the output shaft 6, and the steering arm 8 is, as previously described, movably connected to the push rod 7 via the ball joint 9.

[0048] In the steering gear 1, the rotation of a steering sensor, specifically a steering wheel 15 ( Fig. 2), via the steering column and the input shaft 3 to the spindle 11. The input shaft 3 can, for example, be part of the steering column. The spindle 11 is also called a ball screw or, if applicable, a worm gear. This rotary motion of the input shaft 3, which in Fig. 1 The movement indicated by an arrow III, which suggests a circular motion, is converted into a linear motion of the ball screw nut 13 and thus also of the external teeth 12 of the ball screw nut 13 by means of the ball screw nut 13. This linear motion of the ball screw nut 13 and the external teeth 12 is in Fig. 1 marked by a double arrow IV.

[0049] The linear movement indicated by double arrow IV is then converted, via the gear pairing of the external gear 12 and the segment gear 14, into the rotary movement of the output shaft 6, indicated by the curved double arrows I, which is already described and originates at the output side 4 of the steering gear 1. Thus, the linear movement (double arrow IV) is ultimately also converted into the rotary movement of the steering column lever 8 (double arrows I). At the end of the steering column lever 8, the pushrod 7 is again moved predominantly linearly. As shown in Figure 1, the pushrod 7... Fig. 2 As can be seen, the wheel 17 to be steered is ultimately pivoted around the steering axis 18 by means of a steering lever 16 attached to the wheel carrier. This rotational movement of the wheel 17 is in Fig. 2 indicated by a curved double arrow V. A further wheel 19 opposite wheel 17 can be steered via a track lever 20 and a rigid tie rod 21.

[0050] With reference to Fig. 1 It is evident that the rotary movement (double arrows I) originating from the output side 4 is transmitted via the ball joint 9 to the push rod 7 in such a way that the push rod 7 performs the translational push rod movement (double arrow II) for the intended execution of the steering movement of the wheel 17 or the wheels 17, 19.

[0051] In Fig. 2 Furthermore, a frame 22 of the motor vehicle 10 is shown in the form of two longitudinal beams arranged parallel to each other. The steering gear 1 can be engaged by means of a [missing information] in the Figs. 1 and 2 The mounting arrangement (not shown) on the frame 22 of the motor vehicle 10 is such that, for example, the longitudinal members of the frame 22 and the housing of the steering gear 1 are connected to each other via fastening screws. A direction of travel of the motor vehicle 10 is indicated in Fig. 2 marked with an arrow VI.

[0052] The steering gear 1 preferably features hydraulic power assistance. For this purpose, the recirculating ball nut 13 is sealed against a housing of the steering gear 1. The recirculating ball nut 13 can thus function as a so-called hydraulic piston, or simply piston. The recirculating ball steering system accordingly has two separate oil chambers on opposite sides of the piston for hydraulic power assistance. The steering torque applied by the driver at the input shaft 3 can then be used, for example by means of a rotary valve, to create a differential pressure between the two sides of the recirculating ball nut 13. This differential pressure assists the movement of the recirculating ball nut 13.

[0053] The described power steering assembly incorporates several components, particularly in the steering gear 1, that are sensitive to mechanical stress in order to achieve the desired steering movement. It is essential to protect these components, especially against sudden movements, which can result, for example, from vibrations and ultimately unwanted forces being transmitted via the wheels 17 and 19 into the steering gear 1. Such forces, loads, or stresses within the system can occur when, for instance, uneven road surfaces cause impacts transmitted via the wheels 17 and 19. Therefore, it is particularly desirable to dampen or compensate for such road-related impact impulses to the steering gear 1 and thus prevent damage to its components.In particular, such harmful shocks can be transmitted in the illustrated embodiment via the wheels 17, 19 and then the push rod 7 further to the steering gear 1, which could cause damage to sensitive components of the steering gear 1.

[0054] The present invention advantageously provides a remedy in this regard. Essentially, an adjustable absorption unit 23 is provided for absorbing road-related shocks transmitted via the wheel 17, 19 of the motor vehicle 10.

[0055] The adjustable absorption unit 23 can be provided at a wide variety of locations or nodes of the power steering assembly, as exemplified in the illustrated embodiments of the Figs. 3 to 8The adjustable absorption unit 23 is preferably formed by at least one energy-absorbing element and is configured for at least partial conversion of kinetic into potential energy.

[0056] The adjustable absorption unit 23 is preferably integrated into the power steering assembly in such a way that components of the power steering assembly adjacent to the adjustable absorption unit 23 can perform at least minimal movements relative to each other. For this purpose, the adjustable absorption unit 23 is preferably elastically designed or exhibits increased compliance compared to the adjacent components, particularly those immediately adjacent. In this way, sudden movements of components in the power steering assembly can be selectively absorbed by the adjustable absorption unit 23 and cushioned or compensated by it. The relative movements specifically permitted in the component in the form of the adjustable absorption unit 23 ensure a targeted energy conversion and thus a compensation of the kinetic energy. In this way, the risk of damage to components in the steering gear 1 that are sensitive to mechanical stress is significantly reduced.

[0057] The adjustability of the adjustable absorption unit 23 is ensured by a separate preload unit 24. This separate preload unit 24 interacts with the adjustable absorption unit 23, thereby exerting a predetermined preload force on the adjustable absorption unit 23. In particular, the separate preload unit 24 serves to compress the adjustable absorption unit 23 to a certain extent. As a result, the adjustable absorption unit 23 has a reduced thickness, especially in the direction of force flow of the forces to be compensated by the road-side impacts, when the separate preload unit 24 is present, compared to the state when no separate preload unit 24 is present or installed. This deliberately generates a restoring force in the adjustable absorption unit 23.

[0058] The adjustable absorption unit 23 for absorbing or compensating road-related shocks transmitted via the wheel 17 of the motor vehicle 10 can be provided at various points in the power steering assembly. As shown in the following exemplary embodiments of the Fig. 3 , 5 , 6 , 7 , 8 As will become clear, the adjustable absorption unit 23 can be integrated particularly effectively into the steering gear 1 or its connection to the input shaft 3. The adjustable absorption unit 23 is particularly preferably integrated into the structure of the ball screw nut 13 or its interaction with the input shaft 3 (see Figure 1). Fig. 3 , 5 ), or in the course of the storage of the input shaft 3 (see Fig. 6 ) or in the structure of the input wave 3 itself (cf. Fig. 7 , 8 ) provided.

[0059] In Fig. 3 a) The steering gear 1 is shown partially schematically. Fig. 3 b)shows the section view AA from Fig. 3 a). Fig. 3 a) It serves as a kind of schematic overview (with different alternative reference symbols in brackets), because also Fig. 5 as well as Fig. 6 They basically show the section view BB from Fig. 3 a) .

[0060] Fig. 3 b) shows, as does the embodiment according to Fig. 5 , the steering gear 1 of the corresponding proposed power steering assemblies partially. In both embodiments, the steering gear 1 has an input shaft 3 designed as a spindle 11, as well as a ball screw nut 13 and a rack 55 for converting the rotary motion of the input shaft 3 (arrow III) into a translational motion (double arrow IV).

[0061] To transmit this translational movement (double arrow IV), the rack 55 has a toothed section 56 on its outer side, which provides the external teeth 12. The toothed section 56, or the external teeth 12, then engages with the segment shaft 5, which at least partially forms the output side 4 of the steering gear 1, and its translational movement (double arrow IV) in turn causes the desired rotational movement of the segment shaft 5 (cf. double arrows I in Fig. 1 ). Furthermore, the rack 55 forms a separate component from the internal ball screw nut 13.

[0062] To compensate for road-side shocks, the adjustable absorption unit 23 is located in the Fig. 3 b) and 5The illustrated power steering assemblies are arranged such that the translational movement of the recirculating ball nut 13 (double arrow IV) is transmitted via the adjustable absorption unit 23 to the toothed section 56, and vice versa; that is, a translational movement of the toothed section 56 is also transmitted via the adjustable absorption unit 23 to the recirculating ball nut 13. The adjustable absorption unit 23 consists of at least one elastic element, specifically in the embodiment shown. Fig. 5 from two disc springs 57, or in the version variant according to Fig. 3 b) formed from two elastomers 58. Combinations of elastomers, disc springs or coil springs are also possible in principle.

[0063] The adjustable absorption unit 23 ultimately forms a connection point between the respective ball screw nut 13 and the toothed section 56, which takes over the function of the external toothing 12 for the tooth pairing with the segment shaft 6.

[0064] In the direction corresponding to the translational movement of the ball screw nut 13 (double arrow IV), the two components, ball screw nut 13 and rack 55 with toothed section 56, are fundamentally movable relative to each other. In the direction of rotation, i.e., fundamentally corresponding to the rotational movement of the input shaft 3 (arrow III), the two components, ball screw nut 13 and rack 55 with toothed section 56, are secured against rotation relative to each other. The ball screw nut 13 therefore cannot rotate within its receptacle in the rack 55. Keys, for example, can be provided for this purpose. Fig. 5Additionally, the balls 60 of the ball recirculation steering are shown, while in Fig. 3b ) the explicit description of this was omitted.

[0065] The adjustable absorption unit 23, formed from at least one elastic element, allows relative movements of the components adjacent to the adjustable absorption unit 23 in the illustrated embodiments. These relative movements are possible in the axial direction. The adjustable absorption unit 23 undergoes elastic compression in each case. In this way, the adjustable absorption unit 23 converts kinetic energy into potential energy as intended in the event of excessively strong or sudden movements, for example, in the case of sudden rotation of the output shaft 6, such as those caused by road impacts. This allows the loads prevailing inside the steering gear 1 and caused by road impacts to be advantageously compensated.

[0066] The ball screw nut 13 is in the two illustrated embodiments of the Fig. 3 b) and5 The rack 55 is received in a central bore having a flat surface 61 and secured on the opposite side of the flat surface 61 by a cover 62. The cover 62 abuts with its circumferential bearing surface at its head against the end face of the rack 55, which end face of the flat surface 61 is located opposite the central bore.

[0067] The covers 62 are each firmly connected to the rack 55, preferably via the end faces of the rack 55 facing away from the planar surfaces 61. Furthermore, according to the exemplary embodiment, the cover 62 has Fig. 5 an axially extending import section 59 which projects into the central bore of the rack 55.

[0068] In the embodiment according to Fig. 3 b)The elastomer 58 shown on the left rests with its left, outer end face against an inner part of the head-side, circumferential bearing surface of the cover 62. In the embodiment according to Fig. 5 In turn, the disc spring 57 shown on the right rests with its right, outer surface against an inner end face of the import section 59 of the cover 62.

[0069] The compensation effect of the sudden movements caused by the road surface by the adjustable absorption units 23 of the two described embodiments is described below. Fig. 3 b) and 5described. Specifically, this mainly concerns situations where sudden movements of the output shaft 6 occur, which can lead to jerky linear movements of the rack 55, which engages with the output shaft 6 via the gear pairing (see reference numerals 12, 14, 56), in the two directions indicated by the double arrow IV.

[0070] In principle, the situation is the same in both exemplary embodiments of the Fig. 3 b) and 5 as follows: Sudden rotation of the segment shaft 5 and thus sudden linear movements of the rack 55 to the left are described in the Fig. 3b ) in the embodiment shown, initially compensated by the elastomer 58 shown on the right, and in the embodiment shown in Fig. 5In the illustrated embodiment, the movement is initially compensated by the disc spring 57 shown on the right. The same applies analogously to sudden linear movements of the respective ball screws 13 to the right, which leads to a compression of the right elastomer 58 or the right disc spring 57.

[0071] Conversely, for the opposite directions of movement: During sudden movements of the respective ball screw nut 13 to the left, the left elastomer 58 or the left disc spring 57 is compressed, thereby achieving the desired compensation. Similarly, for a sudden deflection of the output shaft 6 and thus of the segmented toothing 14 to the right: The sudden linear movements of the respective racks 55 to the right compress the left elastomer 58 or the left disc spring 57, thereby achieving the desired compensation.

[0072] Specifically, the targeted compensation of jerky movements proceeds according to the exemplary embodiment of the Fig. 3 b) The process proceeds as follows: If, for example, the rack 55 moves abruptly to the left, perhaps provoked by a sudden pivoting of the segment shaft 5 to the left, this causes the right elastomer 58 to be compressed first. This right elastomer 58 is held in a central receptacle 25 of the rack 55, with a compensating washer of a preload unit 24 (described in more detail later) being arranged at the base of this central receptacle 25, against which the right elastomer 58 rests. In any case, the abrupt movement to the left is transmitted from the rack 55, via the base of the central receptacle 25 and the preload unit 24, to the right elastomer 58 and then, via an adjacent ring element 63, to the ball screw nut 13.

[0073] The compensation described here for the sudden movement of the rack 55 in the left direction functions analogously in the opposite direction with respect to the force flow, i.e., when the cause of the jerky movement is not, as previously described, the deflection of the output shaft 6 and thus the segmented toothing 14 to the left, but rather a jerky movement of the ball screw nut 13 to the right. In this case, the ball screw nut 13, moving abruptly to the right, compresses the right elastomer 58 via the ring element 63, before the elastomer 58, in turn, compensates the movement as desired and transmits it to the preload unit 24, and ultimately to the rack 55, and finally to the segmented toothing 14 and the output shaft 6.

[0074] Conversely, in the opposite direction, i.e., in the case of a sudden movement of the rack 55 to the right (for example, caused by the abrupt deflection of the segment shaft 5 to the right), the one on the left edge is initially moved. Fig. 3 b) The illustrated cover 62 moves to the right, as it is firmly connected to the rack 55. This initially compresses the adjacent left elastomer 58 before the movement is transmitted via the ring element 63 to the ball screw nut 13.

[0075] This described compensation also works in the reverse direction with respect to the force flow, i.e., when the starting point is not a sudden movement of the rack 55 to the right, but a jerky movement of the ball screw nut 13 to the left. In this case, the movement of the ball screw nut 13 to the left first compresses the adjacent left elastomer 58 by means of the ring element 63, thereby achieving the desired compensation, before the forces and the movement are transmitted to the cover 62 and thus to the rack 55 and the output shaft 6.

[0076] According to an exemplary embodiment of the Fig. 5The targeted compensation of sudden movements proceeds as follows: If, for example, the rack 55 moves abruptly and linearly to the left, such as due to a sudden deflection of the segment shaft 5 to the left, the right disc spring 57 is compressed first. This occurs because the cover 62, which is rigidly connected to the rack 55, along with its insertion section 59, is also moved to the left. This, in turn, compresses the right disc spring 57, resulting in the desired compensation of the road-side shock, before the movement is finally transmitted to the ball screw nut 13, which is located to the left of the right disc spring 57.

[0077] The compensation described here for the sudden movement of the rack 55 in the left direction functions analogously in the opposite direction with respect to the force flow, i.e., when the cause of the jerky movement is not, as previously described, the deflection of the output shaft 6 and thus of the segmented toothing 14 to the left, but rather a jerky movement of the ball screw nut 13 to the right. In this case, the ball screw nut 13, moving abruptly to the right, first compresses the right-hand Belleville spring 57, before the spring in turn transmits the compensated movement to the cover 62, which then transmits the movement to the rack 55 and finally to the segmented toothing 14.

[0078] Conversely, if the rack 55 is according to Fig. 5When a sudden movement to the right occurs, the left Belleville spring 57, located in the area of ​​the planar surface 61, is compressed first, before the corresponding loads are transmitted to the ball screw nut 13. Similarly, a sudden, jerky movement of the ball screw nut 13 to the left causes the left Belleville spring 57 to be compressed first, before the forces and thus the movement are transmitted via the planar surface 61 to the rack 55, ultimately causing the segmented toothing 14 and thus the output shaft 6 to deflect to the left.

[0079] A particular advantage of the proposed power steering assembly is that a separate preload unit 24 is provided, which interacts with the adjustable absorption unit 23. A desired, predetermined preload force is exerted by this separate preload unit 24 on the adjustable absorption unit 23.

[0080] In the illustrated embodiments according to Fig. 3 b) and Fig. 5 Specifically, a first compensating washer 26 is used as a separate preload unit 24. Fig. 4 A first compensating washer 26 is shown, having a first thickness d1. Furthermore, a second compensating washer 27 with a different, here smaller, thickness d2 is shown. Each of the compensating washer 26, 27 has central openings 28 through which, in the assembled state, the ball screw nut 13 and the input shaft 3 (see figure) can be accessed. Fig. 3 b) ), or merely input wave 3 (see Fig. 5 ) can extend.

[0081] In principle, several shims 26, 27 and not only those, as in Fig. 3 b) and Fig. 5The first compensating disc 26 shown is provided as a separate preload unit 24, in particular to specifically adjust the desired preload forces acting on the adjustable absorption units 23.

[0082] Specifically, the separate preload units 24, in the described embodiments the respective first compensating washers 25, each have an end face 29 which serves as a contact surface with the adjustable absorption unit 23 for the adjustment, i.e., preload, of the absorption unit 23. The first compensating washers 25 and the respective adjustable absorption unit 23 are arranged in a contact surface against each other.

[0083] Specifically, in Fig. 3 b)The first compensating washer 26 is received in the central receptacle 25 of the rack 55. Adjoining the side facing away from the base of the central receptacle 25 is the right elastomer 58 of the adjustable absorption unit 23. The right elastomer 58 is in contact with the end face 29 of the first compensating washer 26 of the separate preload unit 24 via its right end face (see figure). Fig. 4 ) in contact.

[0084] The separate preload unit 24 with the first compensating washer 26 thus compresses the adjustable absorption unit 23, or more precisely, the right elastomer 58, compared to when the first compensating washer 26 is not present. A predetermined preload force is therefore exerted on the adjustable absorption unit 23, which in turn generates a restoring force in this adjustable absorption unit 23.

[0085] A power steering assembly can therefore be advantageously set up using the proposed method for setting up a power steering assembly for an electro-mechanical power steering system of motor vehicles 10, in particular a power steering assembly as described above, by first integrating the adjustable absorption unit 23 into the conversion train of the steering movement of the entire power steering assembly for at least partial absorption of road-side shocks received via the wheel 17 or 19 of the motor vehicle 10.

[0086] Then, as proposed, a separate preloading unit 24 is provided. This separate preloading unit 24 can be, as in the embodiments of the Fig. 3 , 5 and 6, at least one first compensating washer 26 is provided adjacent to the adjustable absorption unit 23, adjacent to the preload, by targeted compression of the adjustable absorption unit 23. Furthermore, it is also conceivable to provide a second compensating washer 27 adjacent to the adjustable absorption unit 23, adjacent to the preload, by targeted compression of the adjustable absorption unit 23 (cf. Fig. 4 Advantageously, the second compensating disc 27 can have a second thickness d2 that differs from a first thickness d1 of the first compensating disc 26.

[0087] Using such separate preload units 24, a desired, predetermined preload force is set according to the proposed method and exerted on the adjustable absorption unit 23 by the separate preload unit 24 compressing the adjustable absorption unit 23. The adjustable absorption unit 23 is compressed to a certain predetermined extent. This extent can be, for example, as in the embodiments of the Fig. 3 , 5 and 6 the thickness of the selected compensating washers 26, 27 can be chosen, for example, the first thickness d1 of the first compensating washer 26 (cf. Fig. 4 The degree of compression, and thus also the preload force, can also be adjusted via the process step of screwing in, for example, a preload nut 30, thereby ensuring essentially stepless adjustability (see Fig. 7 and 8and the corresponding description).

[0088] In the Fig. 6 , 7 and 8 Further embodiments of an adjustable absorption unit 23 of the proposed power steering assembly are shown. In the illustrated embodiments, the steering gear 1 has an input shaft 3 designed as a spindle 11 and a ball screw nut 13 for converting the rotary motion of the input shaft 3 (arrow III) into a translational motion (double arrow IV). The adjustable absorption unit 23 is at least partially formed as an axial elastic spindle bearing of the input shaft 3.

[0089] In the exemplary embodiment according to Fig. 6The adjustable absorption unit 23, formed as an axial elastic spindle bearing of the input shaft 3, is formed by two elastic elements, specifically the disc spring 67 and the disc spring 68. The disc springs 67 and 68 are arranged adjacent to a bearing arrangement of the input shaft 3 for rotatable mounting of the input shaft 3, specifically to the double-row angular contact ball bearing 69, in a housing 70 such that the bearing arrangement of the input shaft 3 is axially elastically supported in the housing 70 by the disc springs. The separate preload unit 24 with a first compensating washer 26 is arranged between the left disc spring 67 and the angular contact ball bearing 69.

[0090] With the aid of the adjustable absorption unit 23 shown, in the form of the two disc springs 67, 68, road-side shocks, which can be introduced, for example, via the segment shaft 6 with the segment toothing 14, can be specifically compensated. Thus, a sleeve surrounding the input shaft 3 and the inner ring of the angular contact ball bearing 69 rotate with the input shaft 3 (arrow III). The outer ring of the angular contact ball bearing 69, in turn, is arranged in the housing 70 of the steering gear so as to be rotationally fixed but axially displaceable.

[0091] The adjustable absorption unit 23, in the form of the disc springs 67 and 68, rests against the outer ring of the angular contact ball bearing 69 on both sides, i.e., the disc spring 67 on the left and the disc spring 68 on the right. However, the left disc spring 67 does not rest directly against the outer ring of the angular contact ball bearing 69, but only indirectly. The first compensating washer 26 is positioned between the disc spring 67 and the outer ring of the angular contact ball bearing 69.

[0092] As proposed, axial damped movement occurs in the event of spindle-side impacts, since the disc spring 67 shown on the left is compressed during a sudden movement of the input shaft 3 to the left, and the disc spring 68 shown on the right is compressed during a sudden movement of the input shaft 3 to the right. The inner diameter of the disc springs 67 and 68 is larger than the diameter of the sleeve and the input shaft 3, respectively. The adjustable absorption unit 23 shown thus allows small relative movements of the adjacent components of the power steering assembly, which in turn lead to a targeted conversion of kinetic into potential energy and thus also compensate for road-side impacts. The separate preload unit 24 with the first compensating washer 26 provides targeted preload for the disc spring 67 shown here on the left.

[0093] In the exemplary embodiment according to the Fig. 7and 8 The input shaft 3, designed as a spindle 11, is formed in multiple parts by at least one spindle section 71 facing the ball screw nut 13 and an input section 72. Fig. 7 a) The input shaft 3 is shown in a perspective view in its assembled state, while Fig. 7 b) the corresponding input wave 3 in a front view according to arrow B Fig. 7 a) shows. In Fig. 7 c) The input wave 3 is then in a longitudinal section corresponding to section AA. Fig. 7 b) depicted. Fig. 8 The same input wave 3 is shown again, but in an unassembled state, i.e., disassembled into individual components for illustration purposes.

[0094] The spindle section 71 and the input section 72 of the input shaft 3 are rotationally rigidly connected to each other. However, the spindle section 71 and the input section 72 are also axially elastically connected to each other via the adjustable absorption unit 23, which forms the axial elastic spindle bearing of the input shaft 3. The axial elastic spindle bearing is formed by elastic elements, namely, in this case, by a cluster of ring springs 73 shown on the left, and by the cluster of ring springs 91 shown on the right.

[0095] The ring springs 73 shown on the left are arranged between the spindle section 71 and the input section 72. Specifically, the ring springs 73 shown on the left are received in a central receptacle 74 at the end 75 of the spindle section 71 facing the input section 72. On the side facing away from the base of the receptacle 74, the ring springs 73 rest against an end face 76 of a connecting push rod 77. This connecting push rod 77 is also largely received in the receptacle 74 of the spindle section 71; however, the end 78 of the connecting push rod 77 facing the input section 72 of the input shaft 3 protrudes from the receptacle 74 and thus from the end 75 of the spindle section 71.

[0096] The connecting push rod 77 ensures a torsionally rigid connection between the spindle section 71 and the input section 72 of the input shaft 3. As described, the connecting push rod 77 is inserted into the receptacle 74 of the spindle section 71 and a receptacle 79 of the input section 72, and is rotationally fixed to the respective components. For this purpose, a spindle-side connecting pin 80 is provided, which, in the assembled state, extends through both a slot 81 in the spindle section 71 and a spindle-side through-bore 82 in the connecting push rod 77 (for clarity, the through-bore 82 is shown only in the Fig. 8(marked). The elongated hole 81 is also designed as a through-hole. The elongated hole 81 and the spindle-side through-hole 82 are aligned with each other in the assembled state. The elongated hole 81 has a greater axial extent, relative to the axis of the input shaft 3, than the spindle-side through-hole 82.

[0097] On the side facing the inlet section 72, the connecting push rod 77 again has an inlet-side through-bore 83 (the through-bore 83 is shown only in the for clarity of the Fig. 8(marked). Furthermore, the inlet section 72 of the inlet shaft 3 also has a through-bore 84, which, in the assembled state, is aligned with the inlet-side through-bore 83. An inlet-side connecting pin 85, in turn, extends through both the through-bore 84 and the inlet-side through-bore 83 in the assembled state, so that the inlet section 72 and the connecting push rod 77 are rotationally fixed to one another. Moreover, the inlet section 72 and the connecting push rod 77 are also axially fixed to one another, since both the through-bore 84 and the inlet-side through-bore 83 have essentially the same diameter, and the inlet-side connecting pin 85 also positively locks the two components together in the axial direction.

[0098] In the described arrangement, the inlet section 72 and the spindle section 71 are rotationally fixed to one another by means of the components spindle-side connecting pin 80, inlet-side connecting pin 85, and connecting push rod 77. Sufficient clearance for minor axial relative movements between spindle section 71 and inlet section 72 is provided between the two opposing ends of the two components, i.e., between the end 75 of the spindle section 71 facing the inlet section 72 and the end 86 of the inlet section 72 facing the spindle section 71. The fact that the spindle-side connecting pin 80 is received with axial clearance in the elongated hole 81 of the spindle section 71 also allows the connecting push rod 77 to move axially relative to the spindle section 71.

[0099] Such small axial relative movements are used to dampen or compensate for road-side impact impulses. This is achieved by the adjustable absorption unit 23, in the form of the ring springs 73 shown on the left, which are arranged in the receptacle 74 of the spindle section 71, bearing against the end face 76 of the connecting push rod 77, and in the form of the right-hand assembly of ring springs 91. The relative movements absorbed by the adjustable absorption unit 23 convert kinetic energy into potential energy, thus compensating for road-side impacts.

[0100] Furthermore, the preload nut 30 is proposed as a separate preload unit 24. The preload nut 30 partially surrounds the connecting push rod 77 on its outer side. The ring springs 91 of the assembly of ring springs 91 shown on the right are arranged adjacent to the preload nut 30 in the axial direction. Specifically, the ring springs 91 shown on the right are also arranged surrounding the connecting push rod 77. The ring springs 91 are arranged on the left side, i.e., in the direction towards the spindle section 71, against an axial push rod contact 31. On the right side, i.e., in the direction towards the inlet section 72, the ring springs 91 are arranged against an 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 springs 91 of the adjustable absorption unit 23 and the separate preload unit 24.

[0101] Part of the separate pre-tensioning unit 24 are located in the Fig. 7 and 8 In the illustrated embodiment, there are two interlocking threads. Firstly, the preload nut 30 has a thread 33 on its outer cylindrical surface (for clarity, only shown in the figure). Fig. 8(indicated by an arrow). Furthermore, the partially hollow spindle section 71 of the input shaft 3 has a mating thread 34 that matches the thread 33. In this way, the preload nut 30, as the first component, and the spindle section 71 of the input shaft 3, as the second component, engage with each other. The separate preload unit 24 is thus configured to interact with the adjustable absorption unit 23 in such a way that the predetermined preload force can be adjusted by means of the two components—the preload nut 30 and the spindle section 71—engaging with each other via the thread 33 and the mating thread 34. In this case, the two components are essentially infinitely adjustable. This allows the preload nut 30 to change its axial position relative to the spindle section 71 of the input shaft 3 as desired, at least within a certain range.

[0102] Depending on how far the preload nut 30 is inserted into the receptacle 74 of the spindle section 71 (in Fig. 8 (indicated by the dashed arrow) and is finally turned into the counter thread 33, the right package of ring springs 91 is compressed to a greater or lesser extent.

[0103] To prevent the preload nut 30 from rotating again in the mating thread 34, an anti-rotation device can be provided, as shown here. For this purpose, the following is shown in Fig. 7 and 8In the illustrated embodiment, the preload nut has a groove 35. Several grooves can also be provided at different locations on the cylindrical surface of the preload nut 30. To prevent rotation, a locking bolt 36 is provided in the assembled state, which engages both in the groove 35 of the preload nut 30 and in the bore 37 on the cylindrical surface of the spindle section 71 of the input shaft 3 (see overview of Fig. 7 c) and 8 ). The preload nut 30 is secured against rotation, i.e., essentially rotationally fixed, to the spindle section 71 of the input shaft 3 by means of the positive locking of the locking bolt 36 in the bore 37 and likewise the positive locking of the locking bolt 36 in the groove 35 in the circumferential direction.

[0104] Viewed in the axial direction, the preload nut 30 is arranged around the internal connecting push rod 77 in such a way that the preload nut 30 is axially displaceable relative to the connecting push rod 77. The preload nut 30 can therefore change its position in the axial direction relative to the connecting push rod 77. Thus, despite the preload nut 30 being secured in the axial and circumferential directions relative to the spindle section 71, at least small axial relative movements of the spindle section 71 of the input shaft 3 relative to the connecting push rod 77, and consequently relative to the input section 72 of the input shaft 3, are possible, as previously described in detail. The axial range of motion is also provided by the fact that the groove 35 is designed as an elongated hole in which the locking bolt 36 can move axially back and forth to a certain extent.

[0105] The preload nut 30 rests with its axial end face 32 on an axial contact surface 38 of the ring springs 91, presses them together and thus exerts the desired predetermined preload force on the adjustable absorption unit 23 through the compression of the ring springs 91.

[0106] According to the proposed procedure for setting up the in the Fig. 7 and 8The partially illustrated power steering assembly is designed as follows: a preload nut 30, acting as a separate preload unit 24, is attached to the adjustable absorption unit 23, specifically to the right-hand assembly of ring springs 91 and, in particular, to the axial contact surface 38 of these ring springs 91, adjacent to the preload area, by targeted compression of the adjustable absorption unit 23. The predetermined preload force is set by rotating the first component of the separate preload unit 24, in the form of the preload nut 30, which has the thread 33, and the second component, in the form of the spindle section 71 of the input shaft 3, which engages with the first component and has the mating thread 34, relative to each other. The extent to which the thread 33 is turned into the mating thread 34 determines the degree of compression of the ring springs 91 and thus the set preload force.

[0107] The illustrated power steering assembly advantageously compensates for road-related shocks as follows: The input section 72 of the input shaft 3 is axially and radially supported in its position. Shocks acting on the spindle 11 are dampened or compensated by the sets of ring springs 73 and 91, respectively. For example, if the spindle 11 moves to the right towards the input section 72, the left set of ring springs 73 is compressed first, before this movement is finally transmitted to the connecting rod 77 and thus to the input section 72 of the input shaft 3.

[0108] Shocks, which result, for example, in sudden movements of the input section 72 of the input shaft 3 either to the left, i.e., towards the spindle section 71, or to the right, i.e., away from the spindle section 71, are compensated as follows: When the input section 72 moves to the left, the connecting push rod 77 also moves to the left, which in turn initially compresses the left pack of ring springs 73 before the movement is transmitted to the spindle section 71. Conversely, when the input section 72 moves to the right, the connecting push rod 77 also moves to the right, which, via the axial push rod contact 31, initially compresses the right pack of ring springs 91. The movement is then transmitted via the axial end face 32 of the preload nut 30 to the preload nut 30 itself and thus also to the spindle section 71, which is rigidly connected to the preload nut 30.

[0109] Finally, an externally arranged protective sleeve 87 is provided, which also has a spindle-side through-bore 88 and an inlet-side through-bore 89. The spindle-side through-bore 88 is aligned with the spindle-side through-bore 82 of the connecting push rod 77 and the elongated hole 81 in the spindle section 71. Furthermore, the spindle-side connecting pin 80 also extends through the spindle-side through-bore 88 of the protective sleeve 87. The inlet-side through-bore 89, in turn, is aligned with the inlet-side through-bore 83 of the connecting push rod 77 and the through-bore 84 in the inlet section 72. Furthermore, the inlet-side connecting pin 85 also extends through the spindle-side through-bore 89 of the protective sleeve 87.

[0110] The protective sleeve thus surrounds, in particular, the connecting push rod 77 on the outside, as well as the axial clearance between spindle section 71 and input section 72. Furthermore, the protective sleeve provides external guidance for the two separately designed components of the input shaft 3, namely the spindle section 71 and the input section 72. Reference symbol list: 1 steering gear 29 Front surface (of the preloading- 2 Entrance side (of the steering gear- heit 24) bes 1) 30 Preload nut 3 Input wave 31 axial pushrod system 4 Output side (of the steering gear 1) 32 Front surface (of the preload nut 30) 5 Segmented shaft 33 thread 6 Output wave 34 Counter thread 7 Push rod 35 Nut 8 Steering column lever 36 locking bolt 9 ball joint 37 Bore on the outer surface (of spindle section 71) 10 motor vehicle 11 spindle 38 axial contact surface (of the ring springs 91) 12 External teeth (of the ball screw nut 13) 55 rack and pinion 13 ball screw nut 56 gear section 14 Segmented gearing (of the segmented shaft 5) 57 Disc springs 58 Elastomer 15 steering wheel 59 axially extending inlet section (of the cover 61) 16 Steering lever 17, 19 Wheels (of the motor vehicle 10) 60 balls 61 Planar surface (of the central bore in the rack 55) 18 steering axle 20 Track lever 62 Lid 21 tie rod 63 Ring element 22 Frame (of the motor vehicle 10) 67, 68 8 disc springs 69 Angular contact ball bearings (double row) 23 adjustable absorption unit 70 Housing (of the steering gear) 24 Preload unit 71 Spindle section (of the input shaft 3) 25 central mount (of the rack 55) 72 Entrance section (of entrance wave 3) 26 first shim 27 second shim 73 Ring springs 28 opening 74 Recording (of the spindle section 71) 83 through-hole on the inlet side (of the connecting push rod 77) 75 End of spindle section 71 (facing the inlet section 72) 84 Through bore (of the inlet section 72) 76 End face (of the connecting push rod 77) 85 input-side connecting pin 77 Connecting push rod 86 End of the inlet section 72 (facing the spindle section 71) 78 End of the connecting push rod 77 (facing the entrance section 72) 87 Protective sleeve 79 Recording (of entrance section 72) 88 Spindle-side through-hole (of the protective sleeve) 80 spindle-side connecting pin 89 Inlet-side through-hole (of the protective sleeve) 81 Slotted hole (of spindle section 71) 91 Ring springs 82 Spindle-side through-hole (of the connecting push rod 77)

Claims

1. Power steering assembly for electromechanical power steering of motor vehicles (10), in particular commercial vehicles, having a steering gear (1), wherein the steering gear (1) is configured to transmit a rotational movement (III) introduced by a steering device, in particular by a steering wheel (15), through an input side (2) of the steering gear (1) in the form of an input shaft (3) of the steering gear (1), to an output side (4) of the steering gear (1), wherein the input shaft (3) is formed at least in sections as a spindle (11), wherein the steering gear (1) comprises a ball screw nut (13) for converting the rotational movement (III) of the input shaft (3) into a translational movement (IV), and wherein the power steering assembly 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 motor vehicle (10) about a steering axle (18), characterized in that an adjustable absorption unit (23) is provided for at least partial absorption of road-induced shocks received through the wheel (17; 19) of the motor vehicle (10), wherein a separate preload unit (24) is provided, which separate preload unit (24) is configured to interact with the adjustable absorption unit (23) such that a predetermined preload force is applied to the adjustable absorption unit (23), wherein at least one of the following features is fulfilled: (i) the steering gear (1) further comprises a rack (55) for converting the rotational movement (III) of the input shaft (3) into the translational movement (IV), wherein the rack (55) has, on an outer side, a toothing section (56) that surrounds the ball screw nut (13) on the outside and is a separate component from the ball screw nut (13), wherein the ball screw nut (13) and the rack (55) are configured to be movable relative to one another in a direction corresponding to the translational movement (IV) of the ball screw nut (13), wherein the adjustable absorption unit (23) is arranged between the components configured to be movable relative to one another, in the form of the ball screw nut (13) and the rack (55), and is integrated into the structure of the ball screw nut (13), such that the translational movement (IV) of the ball screw nut (13) is transmitted via the adjustable absorption unit (23) to the toothing section (56) and vice versa; or (ii) the adjustable absorption unit (23) is formed as an axial elastic spindle bearing of the input shaft (3) and by at least one elastic element (67; 68), wherein the at least one elastic element (67; 68) is arranged adjacent to an outer ring of a bearing arrangement (69) of the input shaft (3) for rotatable bearing of the input shaft (3) in a housing (70), such that the bearing arrangement (69) of the input shaft (3) is received axially elastically in the housing (70) via the at least one elastic element (67; 68); or (iii) the adjustable absorption unit (23) is formed as an axial elastic spindle bearing of the input shaft, wherein the input shaft (3) is formed in multiple parts by at least one spindle section (71) facing the ball screw nut (13) and an input section (72), and wherein the spindle section (71) and the input section (72) are connected to one another so as to be rotationally fixed but axially elastic via the adjustable absorption unit (23).

2. Power steering assembly according to claim 1, characterized in that the separate preload unit (24) comprises at least one first compensation washer (26).

3. Power steering assembly according to claim 2, characterized in that the separate preload unit (24) further comprises at least one second compensation washer (27), in particular of a second thickness (d2), which preferably differs from a first thickness (d1) of the first compensation washer (26).

4. Power steering assembly according to any one of claims 1 to 3, characterized in that the separate preload unit (24) comprises a preload nut (30).

5. Power steering assembly according to any one of claims 1 to 4, characterized in that the separate preload unit (24) is configured to interact with the adjustable absorption unit (23) such that the predetermined preload force is adjustable, preferably substantially continuously, via two components engaging with one another via a thread (33) and a counter-thread (34).

6. Power steering assembly according to any one of claims 1 to 5, characterized in that the separate preload unit (24) and the adjustable absorption unit (23) are, in an assembled state, at least partially movable relative to one another in an axial direction.

7. Power steering assembly according to any one of claims 1 to 6, characterized in that the separate preload unit (24) is secured, in the assembled state, against rotation in a circumferential direction, in particular via a securing pin (36) engaging with a groove (35).

8. Power steering assembly according to any one of claims 1 to 7, characterized in that the separate preload unit (24) has an end face (29; 32), which end face (29; 32) forms a contact surface for directly bearing against the adjustable absorption unit (23) so as to apply the predetermined preload force to the adjustable absorption unit (23).

9. Method for configuring a power steering assembly for electromechanical power steering of motor vehicles (10) according to any one of claims 1 to 8, characterized in that the adjustable absorption unit (23) for at least partial absorption of road-induced shocks received through the wheel (17; 19) of the motor vehicle (10) is integrated into the conversion path of the steering movement of the entire power steering assembly, in that furthermore the separate preload unit (24) is provided, and in that finally a predetermined preload force is set, which predetermined preload force is applied to the adjustable absorption unit (23) in that the separate preload unit (24) compresses the adjustable absorption unit (23).

10. Method according to claim 9, characterized in that, as the separate preload unit (24), at least one first compensation washer (26) is provided adjacent to the adjustable absorption unit (23) for preloading by targeted compression of the adjustable absorption unit (23).

11. Method according to claim 10, characterized in that furthermore a second compensation washer (27) is provided adjacent to the adjustable absorption unit (23) for preloading by targeted compression of the adjustable absorption unit (23), wherein, preferably, the second compensation washer (27) has a second thickness (d2) that differs from a first thickness (d1) of the first compensation washer (26).

12. Method according to any one of claims 9 to 11, characterized in that, as the separate preload unit (24), a preload nut (30) is provided adjacent to the adjustable absorption unit (23) for preloading by targeted compression of the adjustable absorption unit (23).

13. Method according to any one of claims 9 to 12, characterized in that the predetermined preload force is set by rotating, with respect to one another, a first component of the separate preload unit (24) having a thread (33) and a second component engaging with the first component and having a counter-thread (34).

14. Method according to any one of claims 9 to 13, characterized in that the separate preload unit (24) is finally secured to prevent rotation in a circumferential direction.

15. Method according to claim 14, characterized in that securing is achieved by providing a securing pin (36) that engages in a form-fitting manner with a groove (35) in the circumferential direction.