steering gear

Abstract

Steering gear (1) for a motor vehicle comprising a steering spindle (3) arranged in a rotationally fixed and linearly displaceable manner, which is supported at a first bearing point (4) and a second bearing point (5) spaced apart along the longitudinal extent of the steering spindle (3), wherein the steering spindle (3) engages with a rotatable transmission element such that a rotation of the transmission element causes a linear displacement of the steering spindle (3), wherein a first roller (6) is rotatably mounted against the linearly displaceable steering spindle (3), and a second roller (7) opposite the first roller (6) is rotatably mounted against the linearly displaceable steering spindle (3), wherein a first raceway (10) is formed on the steering spindle (3), on which the first roller (6) rolls during operation of the steering gear (1), and a second raceway (11) is formed on the steering spindle (3), on which during operation of the steering gear (1) rolls the second roller (7),wherein the first roller (6) and the second roller (7) are subjected to force such that the first roller (6) and the second roller (7) bear against the steering spindle (3) without play during operation of the steering gear (1), characterized in that the first roller (6) has a first axis of rotation (8) which is oriented perpendicular to the longitudinal extent of the steering spindle (3) and the second roller (7) has a second axis of rotation (9) which is oriented perpendicular to the longitudinal extent of the steering spindle (3), wherein the second raceway (11) of the steering spindle (3) has a first radially inwardly directed raceway section (16) which deviates from a circular segment shape and the second raceway (11) of the steering spindle (3) has a second radially inwardly directed raceway section (17) which deviates from a circular segment shape, wherein the first roller (6) is designed as a cylindrical roller, wherein the second roller (7) is designed in two parts,with a first roller half (12) and a second roller half (13) arranged coaxially to the first roller half (12), wherein the first roller half (12) has a first running surface (14) which rolls on the second raceway (11) of the steering spindle (3) during operation of the steering spindle (3), and the second roller half (13) has a second running surface (15) which rolls on the second raceway (11) of the steering spindle (3) during operation of the steering spindle (3), wherein the first roller half (12) and the second roller half (13) are rotatable relative to each other, wherein the first roller half (12) is rotatably mounted via a first angular contact ball bearing (19) and the second roller half (13) is rotatably mounted via a second angular contact ball bearing (20), and the first angular contact ball bearing (19) and the second angular contact ball bearing (20) are arranged in an O-configuration,wherein the pressure lines (21) of the rolling contacts of the first roller (6) with the first raceway (10) of the steering spindle (3) intersect with a pressure cone (22) of the first angular contact ball bearing (19) and the second angular contact ball bearing (20).

Description

[0001] The present invention relates to a steering gear for a motor vehicle comprising a steering spindle arranged in a rotationally fixed and linearly displaceable manner, which is mounted at a first bearing point and a second bearing point spaced apart in the longitudinal extent of the steering spindle, wherein the steering spindle engages with a rotatable gear element such that a rotation of the gear element causes a linear displacement of the steering spindle.

[0002] The present invention relates to a steering gear for vehicles, in particular to an improved steering gear that makes the transmission of steering forces more efficient and safer. A steering gear is an essential component of the steering system in vehicles. It converts the rotary motion of the steering wheel into a linear motion that then controls the wheels. In a steer-by-wire system, there is no mechanical connection between the steering wheel and the steering gear, since the steering commands are transmitted from the steering wheel to a road wheel actuator via an electrical signal path. The steering gear is then driven by a correspondingly controlled electric actuator.

[0003] DE 10 2019 208 451 A1 discloses a steering gear for a motor vehicle, comprising a steering rod with a threaded spindle and a spindle nut that can be driven about a spindle axis. This spindle nut interacts with the threaded spindle to displace the steering rod relative to a housing along the spindle axis. The invention provides that the steering rod has a running surface parallel to the spindle axis and that a roller unit rotatable about a roller axis relative to the housing has a rotationally symmetrical cylindrical surface that rolls on the running surface and forms a positive connection with it in the tangential direction with respect to the spindle axis.

[0004] DE 103 14 358 A1 discloses a rack and pinion steering system for a motor vehicle, comprising a steering housing in which a rack is mounted for longitudinal displacement. The rack meshes with a pinion and is axially preloaded by a pressure piece located on the opposite side from the engagement side with the pinion. The pressure piece has a rotatable guide roller adapted to the contour of the rack, against which the rack bears. The guide roller is held on both sides by rolling bearings that absorb radial and axial forces. The outer rings of these bearings have a spherical outer contour and are received in inversely spherical receiving bores in the pressure piece.

[0005] DE 10 2005 062 034 A1 discloses a rack and pinion steering gear in combination with an electrically operated steering system. It comprises a rack shaft and a gear shaft that engages with the rack shaft, as well as a roller rack guide. The line of action of a load acting on the rack, determined by a separating force and a lateral force, is held on the inside of a needle bearing that supports a roller. This arrangement stabilizes the rotation of the roller by optimally transmitting the resulting forces to the rack guide.

[0006] DE 103 44 726 A1 discloses a rack and pinion steering system for a motor vehicle, comprising a rack that meshes with a pinion and is guided in its longitudinal direction so as to be displaceable back and forth in a longitudinal guide of a guide body. The invention includes an anti-rotation device between the rack and the guide body, comprising two longitudinal guide elements arranged on the rack and two counter-guide elements arranged on the guide body. These elements bear against each other in both circumferential directions and overlap each other, wherein at least one of the longitudinal guide elements or counter-guide elements is adjustable in the direction of the associated counter-guide element or longitudinal guide element and can be rigidly fixed in the respective adjusted position in order to improve the stability of the rack and pinion steering system.

[0007] In conventional steering gears, the steering rod is actuated by a gearbox, which often exerts an additional torque on the spindle. This torque, in turn, must be supported against the gearbox housing, which presents various challenges depending on the steering gear design. One such challenge is that the tie rods are usually at an angle to the steering rod axis, which can lead to steering rod deflection, especially when steering forces and road surface impacts are applied.

[0008] When using such steering gears in steer-by-wire systems, a key challenge lies in ensuring high force feedback quality for the driver. Traditional systems suffer from significant friction losses and high steering rod push-through forces caused by the sliding bearing or the losses of the gearbox itself. These factors impair the transmission of crucial information from the road surface to the driver, as it is lost in the frictional offset.

[0009] Conventional sliding bearings based on plain bearings tend to generate increased push-through forces due to their inherent friction properties. These forces increase further with increasing steering forces, negatively impacting efficiency and feedback.

[0010] The object of the invention is therefore to avoid or at least reduce these problems and to provide an improved steering gear for motor vehicles.

[0011] This problem is solved by a steering gear for a motor vehicle comprising a steering spindle arranged in a rotationally fixed and linearly displaceable manner, which is supported at a first bearing point and a second bearing point spaced apart along the longitudinal extent of the steering spindle, wherein the steering spindle engages with a rotatable gear element such that a rotation of the gear element causes a linear displacement of the steering spindle, wherein a first roller is rotatably mounted against the linearly displaceable steering spindle, and a second roller opposite the first roller is rotatably mounted against the linearly displaceable steering spindle, wherein a first raceway is formed on the steering spindle on which the first roller rolls during operation of the steering gear, and / or a second raceway is formed on the steering spindle on which the second roller rolls during operation of the steering gear.wherein the first roller and / or the second roller are subjected to such force that the first roller and / or the second roller rest against the steering spindle without play during operation of the steering gear.

[0012] This results in a purely rolling steering spindle bearing consisting of at least two independently rotatable rollers, which together support the steering spindle with respect to all radially acting forces and against rotation, but allow axially displaceable freedom with the lowest possible friction losses.

[0013] The two rollers thus enable the torques applied by the steering spindle to be absorbed. Furthermore, the steering gear, with at least one force-bearing roller, compensates for backlash, contributing to quiet operation as unwanted rattling or clattering noises are prevented by the preload.

[0014] The steering gear according to the invention thus provides a sliding bearing for the steering spindle, which is specifically designed to minimize sliding forces. By significantly reducing frictional forces, the steering gear according to the invention offers an optimized solution that improves both the quality of the force feedback, and thus the interaction between vehicle and driver, and increases the efficiency of the overall system.

[0015] It is preferred that at least two rollers roll on at least three raceway sections extending axially along the steering spindle, wherein one of the rollers consists of a first and second roller half and at least one of the roller halves is arranged to be displaceable along its axis of rotation and is pre-tensioned by a spring element pressing against the steering rod.

[0016] For the purposes of this application, the steering spindle may also be referred to as the steering rod.

[0017] According to the invention, the first roller has a first axis of rotation oriented perpendicular to the longitudinal extent of the steering spindle and / or the second roller has a second axis of rotation oriented perpendicular to the longitudinal extent of the steering spindle, which has proven to be particularly advantageous with regard to reducing the resistance moment against a linear offset of the steering spindle as well as with regard to providing the highest possible moment support.

[0018] According to a further preferred embodiment of the invention, the first roller and / or the second roller may also be spring-loaded, particularly in the axial direction. A spring force application allows for precise and cost-effective force application to preload a roller relative to the steering spindle. A spring element, as used in connection with this invention, is a mechanical component that stores and releases energy in the form of elastic deformation. It is designed such that it undergoes a specific deformation when a force is applied and returns to its original shape after the force is removed. A spring element can be selected from the group consisting of coil springs, leaf springs, disc springs, Belleville springs, torsion springs, and / or rubber springs.

[0019] According to a further preferred embodiment of the invention, the spring element can also be configured as a disc spring, which is designed as a frustoconical, conical disc spring. Disc springs can be used individually or in columns consisting of several springs arranged one above the other in connection with this invention. The arrangement of the disc springs can be parallel (in the same direction) or series (in opposite directions) in order to achieve different spring characteristics and load characteristics and to precisely adapt the spring stiffness and load limits to the specific requirements of the steering gear.

[0020] The raceways for the rollers on the steering spindle preferably have a flat contact surface extending along the length of the steering spindle. In other words, the raceways do not have threads, although threads may be present in the axially adjacent sections of the steering spindle. Advantageously, at least one of the raceways is formed by a radially inwardly directed material removal from the circular cross-sectional shape of the steering spindle, thus enabling the transmission of torques between this raceway and a corresponding roller.

[0021] According to the invention, it is also provided that the second raceway of the steering spindle has a first raceway section that deviates from a circular segment shape and is directed radially inwards, and / or that the second raceway of the steering spindle has a second raceway section that deviates from a circular segment shape and is directed radially inwards.

[0022] The advantageous effect of this design lies in the fact that the second raceway, with one or both raceway sections, enables the absorption and transmission of torque between the corresponding roller or roller half. This allows torque to be transmitted from the steering spindle to one or more rollers at widely distributed points, which can contribute to a more compact steering gear design due to improved load distribution.

[0023] According to the invention, the first roller is further designed as a cylindrical roller. Because the cylindrical roller forms a linear contact with the corresponding raceway of the steering spindle, torque transmission between the steering spindle and the cylindrical roller is also enabled.

[0024] In a preferred embodiment of the invention, a roller may also be formed in multiple parts. Preferably, a roller is formed in two parts, with a first roller half and a second roller half, and it is further preferred that both roller halves are guided axially displaceable relative to each other. According to the invention, the second roller is also formed in two parts, with a first roller half and a second roller half arranged coaxially to the first roller half. The first roller half has a first running surface that rolls on the second raceway of the steering spindle during operation, and the second roller half has a second running surface that rolls on the second raceway of the steering spindle during operation. The running surfaces of the roller halves with the steering spindle can be either convex, concave, or conical, corresponding to the respective raceway of the steering spindle.It is particularly preferred that, regardless of the shape of the raceways and running surfaces, a convex contact is formed between a running surface and a raceway so that drilling friction in the rolling contact can be reduced. For example, the rolling radius of a convexly shaped roller half is smaller than the concave radius in the corresponding raceway of the steering spindle – and vice versa. Furthermore, it is advantageous that the components rolling with the steering spindle, in particular the rollers and the spindle itself, are hardened, at least in the contact areas.

[0025] Preferably, both roller halves are supported relative to each other by a common axis, i.e., positioned coaxially. The first roller half and the second roller half can preferably be arranged on a common shaft and / or bolt.

[0026] According to the invention, the first roller half and the second roller half are also rotatable relative to each other. Due to the axial displacement, the contact points of the roller halves with the steering spindle are generally not static. Since the steering spindle can execute small tilt angles under torque, the contact areas can migrate, for example, due to crowning, which leads to different instantaneous rolling diameters with respect to the roller axis, and the two roller halves can then rotate at different angular velocities.

[0027] In a further preferred embodiment of the invention, it can also be provided that the first roller half and / or the second roller half are subjected to spring force in the axial direction towards the steering spindle by a spring element. This can particularly ensure that the steering spindle is always in contact with the rollers or roller halves at its at least three rolling track areas within the limits of the preload force, thus providing a smooth-running, backlash-free bearing of the steering spindle.

[0028] It may also be advantageous to further develop the invention in such a way that the first roller half is rotatably mounted on a first angular contact ball bearing and / or the second roller half is rotatably mounted on a second angular contact ball bearing.

[0029] An angular contact ball bearing is a rolling bearing specifically designed to accommodate both radial and axial loads. It is characterized by the angular arrangement of the balls relative to the bearing raceways, which allows the angular contact ball bearing to accommodate loads acting at an angle to the bearing axis.

[0030] An outer ring of an angular contact ball bearing is preferably provided by a rolling pressure plate of the steering gear. The outer ring or the rolling pressure plate is arranged on the side of the angular contact ball bearing facing away from the steering spindle.

[0031] The inner ring of an angular contact ball bearing is preferably formed by a roller half. The inner ring or roller half is arranged on the side of the angular contact ball bearing facing the steering spindle.

[0032] Rolling elements are arranged between the inner and outer rings of the angular contact ball bearing. Rolling friction typically occurs primarily between these three main components—inner ring, outer ring, and rolling elements—within the angular contact ball bearing. Since the rolling elements in the inner and outer rings preferentially roll on hardened steel surfaces with optimized lubrication, the rolling friction is low.

[0033] The term angular contact ball bearing, as used in this application, does not preclude the possibility that roller-shaped rolling elements may be used in an angular contact ball bearing instead of bearing balls. Depending on the bearing design, the rolling elements can therefore be in the shape of a ball or a roller. They roll on the raceways of the angular contact ball bearing and their function is to transmit a force acting on the bearing from the outer ring to the inner ring and vice versa. Roller-shaped rolling elements are also referred to as roller bearings, and spherical rolling elements as bearing balls.

[0034] Roller-shaped rolling elements can be selected, for example, from the group of symmetrical oscillating rollers, asymmetrical oscillating rollers, cylindrical rollers, needle rollers and / or conical rollers.

[0035] Rolling elements can be guided and spaced apart within a cage or by spacers. It is also possible, in principle, to design a cageless angular contact ball bearing, which is also known as a full complement angular contact ball bearing. In full complement angular contact ball bearings, adjacent rolling elements can make contact.

[0036] Within the angular contact ball bearing, the rolling elements can roll, particularly on the inner ring raceway of the inner ring. For this purpose, the surface of the inner ring raceway can advantageously be designed to be wear-resistant, for example, through a suitable surface treatment process and / or by applying an additional layer of material. The inner ring raceway can be flat or profiled. A profiled design of the inner ring raceway can, for example, serve to guide the rolling elements on the inner ring raceway. A flat design of the inner ring raceway, on the other hand, can, for example, allow a certain degree of axial displacement of the rolling elements on the inner ring raceway.

[0037] The rolling elements can roll within the angular contact ball bearing, particularly on the outer ring raceway. For this purpose, the surface of the outer ring raceway can advantageously be designed to be correspondingly wear-resistant, for example, by means of a suitable surface treatment process and / or by applying a suitable additional material layer.

[0038] The outer ring raceway can be flat or profiled. A profiled outer ring raceway can, for example, guide the rolling elements on the outer ring raceway. A flat outer ring raceway, on the other hand, can, for example, allow a certain degree of axial displacement of the rolling elements on the outer ring raceway.

[0039] An angular contact ball bearing can have a cage, which guides the rolling elements. The cage is designed to space the rolling element balls and / or rollers apart, thus minimizing friction and heat generation. Furthermore, the cage maintains a fixed distance between the rolling element balls and / or rollers during rolling, ensuring even load distribution. The cage can be made of a single piece or multiple pieces.

[0040] The first angular contact ball bearing and the second angular contact ball bearing are arranged in an O-configuration.

[0041] According to the invention, the pressure lines of the rolling contacts of the first roller with the first raceway of the steering spindle intersect with the pressure cone of the first angular contact ball bearing and the second angular contact ball bearing. This minimizes the resulting tilting moment acting on one roller half. Since the two roller halves are displaceable relative to each other on a common shaft, these reduced tilting moments counteract potential increases in friction (for example, due to tilting effects) and ensure smooth axial movement of the steering spindle even under load.

[0042] Finally, the invention can also be advantageously implemented such that the spring element is designed as a compression spring which is supported on one side by an axially displaceable first rolling pressure plate of the first angular contact ball bearing and on the other side by an axially displaceable adjusting screw, so that the spring preload of the spring element exerted on the first roller half can be adjusted via the adjusting screw. The spring element acting axially on one roller half, for example a disc spring, can thus, together with the aforementioned pressure angles, effectively compensate for any play in the bearing point between the steering spindle and the rollers.

[0043] The adjusting screw can also provide an end stop in the event of high lateral spindle forces or moments, where the preload force of the spring element is exceeded and the corresponding roller half, including the bearing and pressure plate, deflects axially, compressing the spring element. The end stop can be located either between the adjusting screw and the pressure plate, or between the adjusting screw and a flattened disc spring, which then rests against the pressure plate like a washer.

[0044] The invention will now be explained in more detail with reference to figures, without limiting the general concept of the invention.

[0045] It shows: Fig. 1 a steering gear in a longitudinal section view, Fig. 2 a first embodiment of a steering gear in a cross-sectional view, Fig. 3 a second embodiment of a steering gear in a cross-sectional view, Fig. 4 a third embodiment of a steering gear in a cross-sectional view, Fig. 5 a fourth embodiment of a steering gear in a cross-sectional view, Fig. 6 a fifth embodiment of a steering gear in a cross-sectional view.

[0046] The Fig. Figure 1 shows a steering gear 1 for a motor vehicle comprising a steering spindle 3 that is fixed in rotation and linearly displaceable, and which is supported at a first bearing point 4 and a second bearing point 5 spaced apart along the longitudinal extent of the steering spindle 3, wherein the steering spindle 3 engages with a rotatable gear element such that a rotation of the gear element causes a linear displacement of the steering spindle 3. A first roller 6 is rotatably mounted on the linearly displaceable steering spindle 3, and a second roller 7, opposite the first roller 6, is rotatably mounted on the linearly displaceable steering spindle 3.

[0047] A first raceway 10 is formed on the steering spindle 3, on which the first roller 6 rolls during operation of the steering gear 1. Furthermore, a second raceway 11 is formed on the steering spindle 3, on which the second roller 7 rolls during operation of the steering gear 1. The second roller 7 is subjected to such force that the first roller 6 and the second roller 7 bear against the steering spindle 3 without play during operation of the steering gear 1.

[0048] This will be shown using the cross-sectional views of different embodiments of the steering gear 1 in the Fig. 2-5 are now explained in more detail below.

[0049] The Fig. Figure 2 shows a first embodiment of a steering gear 1, in which the first roller 6 has a first axis of rotation 8 oriented perpendicular to the longitudinal extent of the steering spindle 3, and the second roller 7 has a second axis of rotation 9 oriented perpendicular to the longitudinal extent of the steering spindle 3. The two axes of rotation 8 and 9 are thus parallel to each other.

[0050] In the illustrated embodiment, the first roller 6 is designed as a cylindrical roller and rolls on the first raceway 10 of the steering spindle 3, which has a straight, linear contour in cross-section oriented parallel to the first axis of rotation 8. This results in linear rolling contact between the first roller 6 and the steering spindle 3, which in particular also enables the transmission of torques between the steering spindle 3 and the first roller 6. This design of the first raceway 10 is also referred to as a spindle flat.

[0051] The first roller 6 is preferably integrally provided with two axially outwardly extending bolt-like bearing sections, which define a shaft 33 of the first roller 6 and via which the first roller 6 is connected to the needle bearings 31, 32 and rotatably mounted relative to the gearbox housing 26. For mounting and / or maintenance of the steering gear 1, a housing cover 34 is provided in the gearbox housing 26 in the area of ​​the first roller 6.

[0052] The second raceway 11 of the steering spindle 3 has a first raceway section 16 that deviates from a circular segment shape and is directed radially inwards, as well as a second raceway section 17 that deviates from a circular segment shape and is directed radially inwards. Thus, the steering spindle 3 has a total of three circumferentially distributed contact points with the rollers 6, 7.

[0053] In the Fig. Figure 2 further shows that the second roller 7 is designed in two parts, with a first roller half 12 and a second roller half 13 arranged coaxially to the first roller half 12, which is designed to be axially displaceable. The first roller half 12 has a first running surface 14 which rolls on the second raceway 11 of the steering spindle 3 during operation, and the second roller half 13 has a second running surface 15 which rolls on the second raceway 11 of the steering spindle 3 during operation. Here, the first roller half 12 and the second roller half 13 are arranged on a common shaft 25, wherein the second roller half 13 is guided to be displaceable on the shaft 25 and preferably also rotatable relative to the shaft 25.

[0054] The second roller half 13 is spring-loaded and thus pre-tensioned by a spring element 18 in the direction directed axially towards the steering spindle 3. The spring element 18 is designed as a disc spring. The spring element 18 is supported on one side by an axially displaceable first rolling pressure washer 23 of the first angular contact ball bearing 19 and on the other side by an axially displaceable adjusting screw 24, so that the spring preload of the spring element 18 exerted on the first roller half 12 can be adjusted via the adjusting screw 24. A small air gap between the adjusting screw 24 and the rolling pressure washer 23 can be set via the adjusting screw 24, so that the second roller half 13 can "breathe" axially to accommodate the tolerance variations associated with the travel path.Larger steering spindle forces acting laterally to the right can exceed the preload force of the spring element 18 during operation of the steering gear 1; therefore, the adjusting screw 24 can also serve as an axial travel limiter. The adjusting screw 24 is sealed against the gearbox housing 26 by the seal 27.

[0055] The first roller half 12 is rotatably mounted via a first angular contact ball bearing 19, and the second roller half 13 is rotatably mounted via a second angular contact ball bearing 20. The roller halves 12 and 13 each form an inner ring of the respective angular contact ball bearing 19 and 20, respectively, and the rolling thrust washers 23 and 30 each form an outer ring. The inner rings each have an inner raceway for the rolling elements 28 and 29, and the outer rings each have an outer raceway for the rolling elements 28 and 29.

[0056] The rolling pressure disc 30 is fixedly embedded in the gearbox housing 26, while the rolling pressure disc 23 is guided in the gearbox housing 26 in such a way as to be axially displaceable relative to the gearbox housing 26.

[0057] In the embodiment of the Fig. 2 are the first angular contact ball bearing 19 and the second angular contact ball bearing designed in O-configuration.

[0058] The roller halves 12, 13 of the first roller 7 are designed in a disc-shaped manner in their contact rolling area with the steering spindle 3, with their rolling area in convex contact with the corresponding raceway sections 16, 17 of the steering spindle 3. The raceway sections 16, 17 can be concave (as shown), convex, or conical. The contact area of ​​the roller halves 12, 13 of the second roller 7 with the steering spindle 3 can thus be at a defined pressure angle, similar to an angular contact ball bearing. This allows the second roller 7 to also absorb lateral forces from the steering spindle 3.

[0059] The convex contact surfaces between the raceway sections 16, 17 and the roller halves 12, 13, in combination with the outer contact area of ​​the first cylindrical roller 6, result in a more favorable increase in the lever arm for torque support due to the contact angle. This allows for a reduction in contact pressure on the first roller or the first raceway 10 when torque is applied, which can contribute to minimizing the diameter of the first cylindrical roller 6. Alternatively, the degree of spindle flattening can also be reduced, resulting in a larger spindle cross-section.

[0060] In the Fig. Figure 3 shows an embodiment of a steering gear 1, which is essentially based on the design of the one described in the Fig. This corresponds to the previously known steering gear 1, in which, however, the angular contact ball bearings 19, 20 are arranged in an X-configuration, which can be advantageous due to the ball contact pressures occurring in the angular contact ball bearings 19, 20. It is clearly visible that the pressure lines 21 of the rolling contacts of the first roller 6 with the first raceway 10 of the steering spindle 3 intersect with the pressure cone 22 of the first angular contact ball bearing 19 and the second angular contact ball bearing 20. The perpendicular to the rolling contact of each roller half 12, 13 thus describes a pressure line 21, similar to that of an angular contact ball bearing. It is advantageous if each roller half 12, 13 is designed and / or positioned such that the pressure line 21 of the spindle contact ideally penetrates the area of ​​the pressure cone 22 of the associated angular contact ball bearing 19, 20. This minimizes the tilting moment resulting on the roller halves 12, 13.Since the two roller halves 12,13 are movable relative to each other and rotatable relative to each other on the common shaft 25, reduced tilting moments counteract possible increases in friction (tilting effects) and ensure smooth axial displacement and relative rotation even under load.

[0061] In the embodiments of the Fig. 4-5 is the area of ​​the second raceway 11 with its two raceway sections 16, as a cylindrical section-shaped area of ​​the steering spindle 3 without threads, which facilitates a particularly cost-effective manufacturing of the steering gear 1.

[0062] In these embodiments, the roller halves 12, 13 have a concave crown to ensure good contact with the cylindrical raceway sections 16, 17 of the steering spindle 3. Of course, the roller halves 12, 13 can also be conical, which is particularly simple in design but results in somewhat higher contact pressures. In this design, the X-arrangement of the angular contact ball bearings 19, 20 is particularly advantageous, as it enables a compact design. Analogous to the spindle flattening on the first roller 6, spindle flattening can also be incorporated in the contact areas with the two roller halves 12, 13 for conical roller halves 12, 13. Here, too, a slight crowning is preferably incorporated either on the steering spindle 3 and / or on the conical roller halves 12, 13.

[0063] It is understood that in these embodiments the Fig. 4-5 The moment support is realized solely by the upper cylindrical first roller 6. Since edge supports in the contact area of ​​the spindle edges (transition from the flat to the cylindrical surface) with the first roller 6 must be avoided, either the first roller 6 or the first raceway 10 is crowned in these areas.

[0064] As with the ones already from the Fig. In two or three known embodiments, the first and second roller halves 12, 13 of the first roller 7 are guided on a common shaft 25, with at least one of the roller halves 12, 13 (here the second roller half 13) being mounted axially displaceably and rotatably relative to the first roller half 12. Alternatively, two identical roller halves 12, 13 are also conceivable, which are guided on a common, floatingly mounted shaft 25 as a common axis. Naturally, an additional sliding bearing sleeve can be provided between the shaft 25 and one roller half 12, 13, but this is not shown in the figures.

[0065] The Fig. 5 showed a further development of the Fig. 4. A previously known embodiment of a steering gear 1. Here too, the rolling pressure plate 23 is axially displaceable within the gear housing 26 via the adjusting screw 24. The outer surface of the rolling pressure plate 23 can – as in the embodiments of the Fig. 2-4 is provided to be slightly convex to prevent the rolling pressure plate 23 from tilting against the gearbox housing 26. The same applies analogously to the rolling pressure plate 30. Preferably, the rolling pressure plates 23 and 30 are made of the same part. Alternatively, as is now shown in the Fig. As shown in Figure 5, the rolling pressure disc 23 is designed with slightly more radial play and is thus guided with play in the gearbox housing 26. In the area of ​​the axial offset of the rolling pressure disc 23, a seal 35 designed as an O-ring is embedded in the gearbox housing 26, which creates a centering effect between the rolling pressure disc 23 and the gearbox housing 26.

[0066] It is understood that all components of the steering gear 1 can be arranged in the gearbox housing 26 and that the steering spindle 3 extends longitudinally out of the gearbox housing 26 on both sides. This allows the components arranged inside the gearbox housing 26 to be well protected from external mechanical and / or chemical influences.

[0067] Due to their axial displacement, the contact points of the roller halves 12, 13 with the steering spindle 3 are generally not static. Since the steering spindle 3 can execute small tilting angles under torque, the contact areas can migrate if crowning is present, leading to different instantaneous rolling diameters relative to the roller axis and allowing the two roller halves 12, 13 to rotate at different angular velocities. This is in the Fig. 6 is shown and is explained in more detail below.

[0068] The Fig. Figure 6 illustrates different rolling radii (contact point to the axis of rotation) using conical roller halves 12 and 13. This is caused by an increased support torque on the steering spindle 3, which pushes the second roller half 13 to the right against the end stop of the adjusting screw 24. The rolling pressure disc 23 is therefore shown in the blocked or end-stop state with the disc spring (spring element 18) flattened. It is clearly visible that in such an operating state, the rolling radius R of the first roller half 12 is larger than the rolling radius r of the second roller half 13 with the spindle 3, which leads to different rotational speeds of the roller halves 12 and 13. Because the second roller half 13 is also rotatably mounted on the shaft 25, the first and second roller halves 12 and 13 can consequently be rotated relative to each other.

[0069] The Fig.Figure 6 also shows a further development of the adjusting screw 24, which has a central through-hole. The set axial travel on the right roller pressure plate 23 can be measured and adjusted through this hole by simultaneously applying a torque (or a radial force directed downwards towards the roller halves 12, 13) to the steering spindle 3. The through-hole is then sealed watertight by inserting a rubber plug.

[0070] The invention is not limited to the embodiments illustrated in the figures. The foregoing description is therefore not to be considered limiting, but rather explanatory. The following claims are to be understood as meaning that a named feature is present in at least one embodiment of the invention. This does not preclude the presence of further features. Insofar as the claims and the foregoing description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing any hierarchy. Reference symbol list 1 Steering gear 3 Steering spindle 4 storage locations 5 storage location 6 rolls 7 roll 8 axis of rotation 9 axis of rotation 10 Career 11 Career 12 roll halves 13 roll half 14 Running surface 15 tread surface 16 career section 17 career stage 18 spring element 19 angular contact ball bearings 20 angular contact ball bearings 21 printing lines 22 pressure cones 23 Rolling pressure disc 24 Adjusting screw 25 wave 26 Gearbox housings 27 Seal 28 rolling elements 29 rolling elements 30 rolling pressure disc 31 needle bearings 32 needle bearings 33 wave 34 Housing covers 35 Seal

Claims

[1] Steering gear (1) for a motor vehicle comprising a steering spindle (3) arranged in a rotationally fixed and linearly displaceable manner, which is supported at a first bearing point (4) and a second bearing point (5) spaced apart in the longitudinal extent of the steering spindle (3), wherein the steering spindle (3) engages with a rotatable transmission element such that a rotation of the transmission element causes a linear displacement of the steering spindle (3), wherein a first roller (6) is rotatably mounted against the linearly displaceable steering spindle (3), and a second roller (7) opposite the first roller (6) is rotatably mounted against the linearly displaceable steering spindle (3), wherein a first raceway (10) is formed on the steering spindle (3), on which the first roller (6) rolls during operation of the steering gear (1), and a second raceway (11) is formed on the steering spindle (3). which rolls the second roller (7) during the operation of the steering gear (1),wherein the first roller (6) and the second roller (7) are subjected to force such that the first roller (6) and the second roller (7) bear against the steering spindle (3) without play during operation of the steering gear (1), characterized by, that the first roller (6) has a first axis of rotation (8) oriented perpendicular to the longitudinal extent of the steering spindle (3) and the second roller (7) has a second axis of rotation (9) oriented perpendicular to the longitudinal extent of the steering spindle (3), wherein the second raceway (11) of the steering spindle (3) has a first radially inwardly directed raceway section (16) deviating from a circular segment shape and the second raceway (11) of the steering spindle (3) has a second radially inwardly directed raceway section (17) deviating from a circular segment shape, wherein the first roller (6) is designed as a cylindrical roller, wherein the second roller (7) is designed in two parts, with a first roller half (12) and a second roller half (13) arranged coaxially to the first roller half (12), wherein the first roller half (12) has a first running surface (14),which rolls on the second raceway (11) of the steering spindle (3) during operation, and the second roller half (13) has a second running surface (15) which rolls on the second raceway (11) of the steering spindle (3) during operation, wherein the first roller half (12) and the second roller half (13) are rotatable relative to each other, wherein the first roller half (12) is rotatably mounted via a first angular contact ball bearing (19) and the second roller half (13) is rotatably mounted via a second angular contact ball bearing (20), and the first angular contact ball bearing (19) and the second angular contact ball bearing (20) are arranged in an O-configuration, wherein the pressure lines (21) of the rolling contacts of the first roller (6) with the first raceway (10) of the steering spindle (3) are aligned with a pressure cone (22) of the first angular contact ball bearing (19) and the second angular contact ball bearing (20) cut. [2] Steering gear (1) according to claim 1, characterized by, that the first roller (6) and / or the second roller (7), in particular in the axial direction, are / is subjected to spring force. [3] Steering gear (1) according to claim 2, characterized by , that a spring element (18) is designed as a compression spring which is supported on one side by an axially displaceable first rolling pressure disk (23) of the first angular contact ball bearing (19) and on the other side by an axially displaceable adjusting screw (24), so that the spring preload of the spring element (18) exerted on the first roller half (12) is adjustable via the adjusting screw (24).

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