Steering system for a motor vehicle and method for producing a steering system

Abstract

The present invention relates to a steering system (1) for a motor vehicle, comprising a sliding guide having guide parts (2, 5, 831, 9) which have sliding surfaces (61, 91) that are in sliding contact with one another. In order to enable a functionally improved, environmentally friendly sliding guide, the invention proposes that at least one of the guide parts (5, 9) comprises a ceramic material in the region of the sliding surface (61, 91).

Description

[0001] thyssenkrupp Presta AG 1 250020P10WO / 25016-EPS thyssenkrupp AG

[0002] Steering system for a motor vehicle

[0003] and methods for manufacturing a steering system

[0004] State of the art

[0005] The invention relates to a steering system for a motor vehicle, comprising a sliding guide with guide elements having sliding surfaces that slid in contact with one another. A method for manufacturing a steering system is also part of the invention.

[0006] A motor vehicle's steering system comprises mechanical functional components that are adjustable relative to one another along a defined path of movement. These functional components can include, for example, adjustable elements of a steering column, or an actuator rod that can be moved within the housing of a steering gear or steering actuator, or similar components.

[0007] The relative movement of the functional parts is determined by a sliding guide formed between two guide parts connected to the functional parts. The two guide parts have sliding surfaces that are in sliding contact with each other and are adjustable relative to each other, for example along an axis.

[0008] In applications within a motor vehicle's steering system, high quality standards are demanded of the sliding guide, both in terms of manufacturing, functional and operational characteristics, and environmental compatibility. The relative adjustment of the guide components should be smooth and low-friction, while simultaneously requiring tight bearing tolerances to ensure high rigidity and prevent noise generation due to vibrations. These properties should be maintained throughout the entire service life with minimal maintenance and should not be affected by wear or aging, even under adverse operating conditions. Furthermore, manufacturing, operation, and disposal should be efficient and environmentally friendly, particularly with regard to the materials used.

[0009] In the prior art, it is, for example, from EP 3257721 B1 or the

[0010] EP 2 990300 B1 known, in a sliding guide between the sleeves of a steering column thyssenkrupp Presta AG 2 250020P10WO / 25016-EPS thyssenkrupp AG

[0011] The use of a polymer sliding element is preferred, with the use of a fully fluorinated polymer such as polytetrafluoroethylene (PTFE) being the preferred option in practice due to its favorable sliding properties. This reduces friction. However, a disadvantage is that the polymer element settles over time, which can lead to increased bearing clearance, noise, and reduced stiffness. Compensating for these adverse effects requires considerable effort. Furthermore, the use of these technically well-suited fully fluorinated polymers is disadvantageous with regard to environmental compatibility.

[0012] Another example is provided by DE 102021 212403 A1, which describes a sliding guide between a linearly displaceable actuator rod and a pressure piece that is fixed relative to it, with a polymer sliding surface.

[0013] In view of the problems explained above, it is an object of the present invention to enable a functionally improved, environmentally friendly sliding guide.

[0014] Description of the invention

[0015] This problem is solved according to the invention by the steering system with the features of claim 1 and the method according to claim 9. Advantageous further developments are set out in the dependent claims.

[0016] In a steering system for a motor vehicle, comprising a sliding guide with guide parts having sliding surfaces that glide in contact with each other, it is provided according to the invention that at least one of the guide parts has a ceramic material in the area of ​​the sliding surface.

[0017] The invention relates to a steering system, for example a steering column, a steering gear, a steering actuator, or another functional group of the steering system of a motor vehicle, which has two guide elements that are movable relative to each other. The guide elements contact each other with sliding surfaces which are adjustable in one direction of their surface area relative to each other.

[0018] Preferably, the sliding surfaces can be flat and extend in a sliding plane.

[0019] A special design is a linear sliding bearing, in which sliding displacement in one direction of movement along a linear slide track is possible. The linear slide track thyssenkrupp Presta AG 3 250020P10WO / 25016-EPS thyssenkrupp AG

[0020] It can preferably be designed in a linear adjustment direction, for example in the axial direction of axially adjustable sleeves of a steering column, or in the axial direction of an actuator rod of a steering actuator or steering gear. Alternatively, the sliding track can be curved or bent.

[0021] The ceramic material, hereinafter also referred to as ceramic, is formed from a non-metallic, inorganic sintering material. This is supplied as a fine-grained powder, from which a raw part, the so-called green body, is first formed. This is then sintered by heat treatment. Through the sintering process, the material particles are bonded together to form a solid sintered body made of the ceramic material.

[0022] The guide element can be made entirely of ceramic material, or sectionally in the area of ​​a sliding surface that slidably contacts the other guide element. Accordingly, a sliding pair is formed according to the invention in which at least one of the two sliding surfaces comprises a ceramic material.

[0023] The ceramic material exhibits advantageously low friction in various possible friction pairings. It possesses high wear resistance, hardness, and dimensional stability. This is an advantage over the use of plastic materials such as PTFE or similar substances, which exhibit lower dimensional stability and adverse settling behavior, potentially leading to increased bearing play and undesirable noise generation during operation. These adverse effects can be virtually eliminated by the invention.

[0024] Another advantage is that, compared to conventional plastic and / or metal friction pairings, the ceramic material allows for smaller differences between static and kinetic friction, thus almost completely eliminating stick-slip effects. This is particularly important in automotive steering systems for achieving precise steering characteristics and a pleasant feel.

[0025] According to the invention, different friction pairings can be realized in which one friction partner is formed by the ceramic material. The other friction partner can, for example, comprise a metallic material or the like, whereby the specific material properties of the ceramic enable favorable sliding behavior and long-term stable operating characteristics. thyssenkrupp Presta AG 4 250020P10WO / 25016-EPS thyssenkrupp AG

[0026] The ceramic material also exhibits improved environmental compatibility, both in its production, operation and disposal, especially compared to the previously preferred fluorinated polymer materials.

[0027] It is possible, but not necessary, for both guide elements to be made of a ceramic material. It is possible for at least the sliding surfaces of both guide elements to be designed according to the invention, thereby creating a ceramic-on-ceramic sliding pair. This pair is highly resilient and virtually wear-free. Furthermore, considering the operating conditions, it may be possible to operate such a sliding bearing dry, i.e., without additional lubricant, thereby reducing manufacturing and operating costs while maintaining high operational reliability. This allows for further optimization of manufacturing, operation, and environmental compatibility.

[0028] An advantageous design can be achieved by incorporating a sliding element made of ceramic material into the guide element. This sliding element has a sliding surface that contacts the other guide element and can therefore also be referred to as a contact element. The sliding element can initially be manufactured separately from the ceramic material, and one or more sliding elements can be fixed to a guide element. It is possible to use identically designed sliding elements on different guide element designs, or vice versa. This allows for flexible adaptation with minimal design effort.

[0029] Alternatively, the guide element can be formed integrally with the sliding element. In this case, the guide element can be made entirely of ceramic material.

[0030] It is advantageous that the sliding element is designed as an injection-molded part. The injection-molded part is produced using an injection molding process (e.g., ceramic injection molding, CIM) from a thermoplastic or thermoset polymer filled with ceramic particles. The polymer (acting as a binder) is then removed from this green part, for example, by thermal, chemical, or solvent-based treatment, and the ceramic particles are sintered at high temperatures to form a sintered body. In this way, customized, and especially complex, shapes that cannot be produced with conventional press-sintering processes, or only with great difficulty, can be realized efficiently and with high precision. thyssenkrupp Presta AG 5 250020P10WO / 25016-EPS thyssenkrupp AG

[0031] The guide element may have a base body made of a non-ceramic material. This base body can be adapted to the function of the guide element in the steering system of a motor vehicle and may, for example, have specific mechanical interfaces such as coupling, connecting, actuating, or drive elements, or the like. One or more sliding elements may be connected to the base body, for example, by positive-locking and / or material-locking connections. Preferably, fixed, permanent connections are used.

[0032] The material of the base body can be optimized according to specific requirements. For example, it can be made of a metallic material, such as steel or aluminum, or of a plastic material, a composite material, or the like. For instance, fiber-reinforced plastic can be used to provide a lightweight, dimensionally stable, and highly durable guide component.

[0033] An advantageous embodiment may provide that the base body comprises an injection-molded part, in particular a plastic injection-molded part made of a thermoplastic or thermoset polymer. The injection molding process further offers the advantageous possibility of permanently bonding one or more ceramic sliding elements to the base body by overmolding or overmolding. This allows for the efficient production of a dimensionally accurate guide element and a secure connection with the sliding element.

[0034] It is advantageous that the injection-molded part is made from a fiber-reinforced polymer. This allows for the efficient production of a highly durable component.

[0035] Alternatively, the base body may be a casting, e.g. a metal die-cast part, for example made of aluminum, zinc or other alloys.

[0036] Alternatively, the base body can consist of a sheet metal part, e.g., a stamped and / or bent part. This sheet metal part can have a spring effect, so that the sliding element(s) connected to the base body are spring-loaded and pressed against the second guide part of the sliding pair, which is contacted by the sliding element. This can advantageously compensate for tolerances, wear, or superimposed transverse movements.

[0037] It is still possible that the base body has been machined.

[0038] A further advantageous embodiment may provide that the at least one sliding element has an undercut element which is positively locked to the base body.

[0039] is connected. Especially when one or more ceramic sliding elements are connected to a base body by overmolding or overmolding in an injection molding process, a particularly secure and inseparable connection can be achieved with an undercut element.

[0040] Further development may provide that the guide element incorporates a lubricant reservoir. The lubricant reservoir is designed to hold a supply of lubricant, for example, grease or a solid lubricant such as molybdenum disulfide or the like, which can be dispensed between the sliding contact surfaces. The lubricating film supplied from the lubricant reservoir between the guide elements is relatively thin, allowing the reservoir's capacity to be precisely determined to ensure long-lasting lubrication of the sliding guide, preferably sufficient for its entire service life. This enables smooth and low-wear adjustment of the sliding guide.

[0041] A lubricant reservoir can have a lubricant receptacle which can be incorporated into at least one guide part as a depression or concave molding, for example in the form of a lubricant pocket or trough, in such a way that it is open towards the sliding surface.

[0042] During operation, the lubricant reservoir is filled with a lubricant. This lubricant can be formulated so that, under typical operating conditions, a sufficient, but not excessive, quantity of lubricant flows from the reservoir into the contact area between the guide elements. Preferably, the lubricant can be added during the assembly of the sliding guide, thus enabling maintenance-free operation.

[0043] The lubricant reservoir can be molded into the ceramic material, for example into a sliding element, or into a base body.

[0044] One advantageous application is that the sliding guide is formed between an actuator rod and the housing of a steering actuator. The actuator rod can have a rack and / or a threaded spindle, which is mounted in a housing so as to be linearly displaceable in the longitudinal direction, and which is connected to one or more steerable wheels. In a manual steering system, the steering actuator has a steering gear in which the actuator rod can be moved manually via a gear drive, if necessary thyssenkrupp Presta AG 7 250020P10WO / 25016-EPS thyssenkrupp AG

[0045] with an additional motor-assisted force. In a steer-by-wire steering system, the steering actuator has only a motorized linear drive, for example, a spindle or gear drive. In any case, the actuator rod forms a guide element that is slidably guided by another guide element connected to the housing, which, for example, includes a pressure piece inserted into the housing. The pressure piece has a sliding surface that slidably contacts a corresponding sliding surface of the actuator rod. The sliding surface of the actuator rod forms a longitudinally linear guide track. The use of the virtually wear-free ceramic material according to the invention enables a simplified design and ensures optimal operation throughout its entire service life.

[0046] The actuator rod can be made of steel, a composite material, or other materials, for example.

[0047] Another possible application is that the sliding guide is arranged between adjustable sleeves of a steering column. A longitudinally adjustable steering column, as described, for example, in the aforementioned EP 3257721 B1, has at least two sleeves or sleeve tubes that are axially adjustable along a longitudinal axis, for example, an inner sleeve telescopically mounted in an outer sleeve, which constitute the guide elements. In this application, it is advantageous that the ceramic material enables a largely complete elimination of disruptive stick-slip effects without compromising high stiffness and the smoothest possible adjustability of the sleeve assembly. A further advantage is that the use of additional lubricant can be reduced or completely avoided.

[0048] The invention further comprises a method for manufacturing a steering system comprising a sliding guide with two guide parts having sliding surfaces that slid in contact with each other, wherein, according to the invention, a sliding element made of ceramic material is formed on at least one of the guide parts. The method allows all features expressly or implicitly disclosed above in connection with the steering column according to the invention to be realized.

[0049] For the manufacture of the sliding guide, two guide parts are provided, which have corresponding sliding surfaces that can be brought into sliding contact with each other. According to the invention, at least one of the guide parts is designed, at least partially, at least in the area of ​​the sliding surface, as a sliding element made of a ceramic material. It can be - as described above-thyssenkrupp Presta AG 8 250020P10WO / 25016-EPS thyssenkrupp AG

[0050] ben - a one-piece sliding element can be implemented, or one or more sliding elements can be attached to a base body.

[0051] It is advantageous for the sliding element to be manufactured using an injection molding process. This could, for example, be CIM (ceramic injection molding).

[0052] It is preferably possible to produce an injection-molded part from a thermoplastic or thermoset polymer filled with ceramic particles using an injection molding process. Subsequent thermal treatment sinters the ceramic particles into a solid sintered body, from which the sliding element is then formed. In the first step, an injection-molded part is produced from a thermoplastic or thermoset polymer material containing a relatively high proportion of ceramic powder. In this part, the ceramic particles are embedded in the polymer matrix (the binder). This filled injection-molded part forms the green part for a subsequent sintering process. In a preceding debinding process, the binder is removed from the green part by thermal, chemical, or solvent-based means.The injection-molded part is then heated to a sintering temperature at which the ceramic particles are bonded together to form a continuous, solid sintered body. At this temperature, any remaining polymer is burned out and thus removed from the sintered body. The advantage of this process is that complex shapes can be produced efficiently and with high precision using injection molding, and the sintered body exhibits significant advantages of the ceramic material, such as favorable sliding properties and high and lasting dimensional stability.

[0053] It is possible that the sliding element forms a guide part. This can therefore be designed as a one-piece sintered molded part made of ceramic material. Accordingly, it encompasses the sliding surface.

[0054] Alternatively, a base body can be produced and connected to the sliding element. The guide element is formed from the base body and one or more sliding elements attached to it. It can be advantageous for the base body to be made of a non-ceramic material. For specific details and advantages, please refer to the preceding description of the steering system.

[0055] The material of the base body can be optimized with regard to specific requirements. thyssenkrupp Presta AG 9 250020P10WO / 25016-EPS thyssenkrupp AG

[0056] It can be a metallic material, such as steel, or a plastic material, a composite material, or the like. For example, a fiber-reinforced plastic can be used to provide a lightweight and highly durable guide component.

[0057] An advantageous further development can provide for the base body to be manufactured as an injection-molded part, preferably using plastic injection molding from a thermoplastic or thermoset polymer. The injection molding process also offers the advantageous possibility of permanently bonding one or more ceramic sliding elements to the base body by overmolding or overmolding. This allows for the efficient creation of a highly resilient connection.

[0058] It is advantageous that the base body is made of a fiber-reinforced plastic. This allows for the efficient production of a highly durable component.

[0059] Alternatively, the base body may be a casting, such as a metal die-cast part, produced using a metal die-casting process, for example from aluminum, zinc, or other alloys. It is also possible for the base body to be produced by machining.

[0060] Alternatively, the base body can consist of a sheet metal part, e.g., a stamped and / or bent part. This sheet metal part can have a spring effect, so that the sliding element(s) connected to the base body are spring-loaded and pressed against the second guide part of the sliding pair, which is contacted by the sliding element. This can advantageously compensate for tolerances, wear, or superimposed transverse movements.

[0061] It is possible that at least one sliding element is injection-molded onto the base body. In this process, a ceramic sliding element is permanently bonded to the base body using a plastic injection molding process. thyssenkrupp Presta AG 10 250020P10WQ / 25016-EPS thyssenkrupp AG

[0062] Description of the drawings

[0063] Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. Specifically, they show:

[0064] Fig. 1 shows a motor vehicle steering system in a schematic perspective view,

[0065] Fig. 2 shows a steering gear according to the invention in a freestanding perspective view,

[0066] Fig. 3 shows the steering gear according to Fig. 2 in a partially separated view,

[0067] Fig. 4 shows a cross-section through the steering gear perpendicular to the rack,

[0068] Fig. 5 shows the pressure piece of the steering gear according to Fig. 2 in a perspective view,

[0069] Fig. 6 shows a longitudinal section through the pressure piece according to Fig. 5,

[0070] Fig. 7 shows a sliding element of the pressure piece according to the invention as shown in Figs. 5 and 6 in a freestanding perspective view,

[0071] Fig. 8 shows a schematic perspective view of a steering column according to the invention.

[0072] Fig. 9 shows a partial longitudinal section through the steering column according to Fig. 8,

[0073] Fig. 10 shows a guide element (sliding element) of the steering column according to the invention.

[0074] Figures 8 and 9 are isolated in a perspective view.

[0075] Embodiments of the invention

[0076] In the various figures, identical parts are always identified with the same reference symbols and are therefore generally only named or mentioned once. thyssenkrupp Presta AG 11 250020P10WO / 25016-EPS thyssenkrupp AG

[0077] Fig. 1 schematically shows a motor vehicle steering system 1 designed as an electromechanical power steering system, which has a steering column 10. A steering shaft 11 is rotatably mounted in this column, into which a manual steering torque (steering torque) can be applied as a steering command via a steering wheel 102.

[0078] The steering torque is transmitted from the steering shaft 11 to a steering pinion 104, which is rotatably mounted in a steering gear 3 about an axis L1 and engages with a toothed section 106 of a rack 2. As a result, rotation of the steering shaft 11 causes the rack 2 in the steering gear 3 to move longitudinally, i.e., along its longitudinal axis Z, as indicated by the double arrow, depending on the direction of rotation. The resulting movement of the connected tie rods 108 transmits the specified steering angle to the steerable wheels 110 of the vehicle.

[0079] The axis L1 is perpendicular (skew) to the longitudinal axis Z.

[0080] An electric power assist can be provided in the form of a power assist 112 coupled to the steering shaft 1, a power assist 114 coupled to the steering pinion 104, and / or a power assist 116 coupled to the rack 2. The respective power assist 112, 114, or 116 couples an auxiliary torque into the steering shaft 11 and / or the steering pinion 104 and / or an auxiliary force directed in the direction of the longitudinal axis Z into the rack 2, thereby assisting the driver with steering. The three different power assists 112, 114, and 116 shown in Figure 1 illustrate possible positions for their arrangement.

[0081] Typically, only one of the positions shown is equipped with a power assist device 112, 114, or 116. The auxiliary torque or force to be applied to assist the driver by means of the respective power assist device 112, 114, or 116 is determined taking into account a steering torque applied by the driver, as measured by a torque sensor 118. Alternatively, or in combination with the application of the auxiliary torque, the power assist device 112, 114, or 116 can introduce an additional steering angle into the steering system, which is added to the steering angle applied by the driver via the steering wheel 102.

[0082] A torque sensor 118, which is known in principle and which, for example, has an electrical sensor arrangement, can be used to measure the rotation of the steering shaft 11, thyssenkrupp Presta AG 12 250020P10WO / 25016-EPS thyssenkrupp AG

[0083] and / or a steering torque applied by the driver via the steering wheel 102 can be measured. Similarly, an auxiliary torque can be generated by one of the power assistance systems 112, 114, or 116.

[0084] Fig. 2 shows the steering gear 3 in its assembled state in a freestanding perspective view. Fig. 4 shows a cross-section AA perpendicular to the longitudinal axis Z of the rack 2.

[0085] The steering gear 3 has a housing 31, which may, for example, have a base made of metal, such as aluminum or magnesium casting. The rack 2 is mounted in the housing 31 so as to be longitudinally displaceable along its longitudinal axis Z, and the steering shaft 11 with the steering pinion 104 is mounted to be rotatable about the axis L1. The steering pinion 104 is in mesh with the teeth 106 of the rack 2, as can be seen in Fig. 4.

[0086] The rack 2 forms an actuator rod that is linearly displaceable in the housing 31 according to the invention. It can be made of steel, at least in sections.

[0087] A preload device 4 has an adjusting screw 41 which is screwed into a corresponding internal thread in a bore 32, which extends in the direction of a preload axis V, which designates the preload direction. The preload axis V is identical to the screw axis of the adjusting screw 41.

[0088] The bore 32 extends in the area of ​​the rack 2 transversely to the longitudinal axis Z and to the axis L1. Preferably, the preload axis V can intersect the longitudinal axis Z, as in the embodiment shown in Fig. 4.

[0089] In the bore 32 a pressure piece 5 is mounted so as to be displaceable in the direction of the preload axis V, and rests on the rack 2 on a side facing away from the toothing 106 with respect to the longitudinal axis Z, the rack being guided sliding on the pressure piece 5 in its longitudinal direction.

[0090] A spring 43 can optionally be arranged axially with respect to the preload axis V between the adjusting screw 41 and the pressure piece 5 according to the invention.

[0091] When the adjusting screw 41 is screwed into the bore 32, the pressure piece 5 is axially loaded against the rack 2 in the direction of the preload axis V. The toothing 106 derthyssenkrupp Presta AG 13 250020P10WQ / 25016-EPS thyssenkrupp AG

[0092] Rack 2 is held in meshing with the steering pinion 104, as indicated by the arrow in Fig. 4. A sliding guide designed according to the invention is formed between rack 2 and the pressure piece 5.

[0093] In Fig. 3, the adjusting screw 41, the pressure piece 5 and the spring 43 are shown schematically separated in the direction of the preload axis V.

[0094] The adjusting screw 41 can be designed as a plastic injection molded part made of a thermoplastic polymer.

[0095] The pressure piece 5 is shown separately in a perspective view in Fig. 5, and in a longitudinal section along the prestressing axis V in Fig. 6.

[0096] The pressure piece 5 forms a guide element designed according to the invention. In the example, it has a base body 51 which is mounted in the housing 31 so as to be linearly displaceable in the direction of the preload axis V. This allows it to be displaced transversely to the rack 2 perpendicularly to the axis Z, as indicated by the arrow in Figures 5 and 6.

[0097] The basic body 51 can be designed as a plastic injection molded part made of a thermoplastic polymer.

[0098] A sliding element 6 according to the invention, made of a ceramic material, is attached to the base body 51, preferably by a firm, material- and form-fitting connection.

[0099] The sliding element 6 has a sliding surface 61 on its outer side, facing away from the base body. This sliding surface is shaped like a hollow cylinder and segment and is adapted to the rear side of the rack 2, facing away from the toothing 106. As a result, the rack 2 is linearly slidably mounted on the sliding surface 61 of the sliding element 6 in the direction of its longitudinal axis Z, which is shown in Fig. 6.

[0100] In the area of ​​the pressure piece 5, a sliding pair is formed between the material of the rack 2 and the ceramic of the sliding element 6, for example, a metal-ceramic sliding pair. Alternatively, it is possible that the rack 2 has a composite material, a ceramic material, a hard coating, or the like in the area of ​​the sliding bearing. It is quite possible to use a fiber composite material with high-strength and / or hard reinforcing fibers. This is due to the fact that the ceramic thyssenkrupp Presta AG 14 250020P10WO / 25016-EPS thyssenkrupp AG

[0101] Since the material can easily be designed with a relatively higher hardness, potentially detrimental abrasion of the sliding surface 61 can be practically ruled out. The sliding element 6 is shown separately in a perspective view in Fig. 7. According to the invention, it is manufactured as a one-piece part using the injection molding process according to the invention. As can be clearly seen, it can thereby have a complex shape that would not be possible, or only with great difficulty, to produce using conventional ceramic manufacturing processes, for example, with a pressed green part.

[0102] For example, recesses 62 can be formed in the area of ​​the sliding surface 61 to serve as lubricant reservoirs.

[0103] It is advantageous that the sliding element 6 has integrally molded interlocking elements 63. These can be permanently embedded in the plastic material of the base body 51 by injection molding, as can be seen in Figures 5 and 6. The interlocking elements 63 can partially (or all) have one (or more) undercutting elements 64, which further reinforce the interlocking, permanent connection with the base body 51.

[0104] Figures 8, 9 and 10 show a second application of a sliding guide according to the invention.

[0105] Fig. 8 shows a steering column 10 according to the invention, as it may be used, for example, in a steering system 1 according to Fig. 1, in a schematic perspective view from the top right obliquely to the rear end, with reference to the direction of travel of a vehicle not shown.

[0106] The steering column 10 comprises a support unit 82, which has fastening means 821 in the form of mounting holes for attachment to a vehicle body (not shown). The outer shell 84 of a sleeve unit, also referred to as a guide box or box-type rocker arm, is held by the support unit 82 and houses an actuating unit 83.

[0107] The actuating unit 83 has an inner casing 831 (casing tube) in which a steering spindle 832 is rotatably mounted about a longitudinal axis L2, which extends axially in the longitudinal direction, i.e., in the direction of the longitudinal axis L2. At the rear end, a mounting section 833 is formed on the steering spindle 832, to which a steering wheel (not shown) can be attached. thyssenkrupp Presta AG 15 250020P10WQ / 25016-EPS thyssenkrupp AG

[0108] The inner shell 831 is telescopically displaceable in the outer shell 84 of the shell unit in the direction of the longitudinal axis L2 to enable longitudinal adjustment of the steering wheel connected to the steering spindle 832 in the longitudinal direction forwards and backwards, as indicated by the double arrow parallel to the longitudinal axis L2.

[0109] The outer shell 84 is pivotally mounted in a pivot bearing 822 on the support unit 82 about a horizontal pivot axis lying transversely to the longitudinal axis L2. At the rear, it is connected to the support unit 82 via an actuating lever 841. By rotating the actuating lever 841 by means of an adjusting drive 86, the outer shell 84 can be pivoted relative to the support unit 82 about the pivot axis, which is horizontal in the installed state. This allows for the vertical adjustment H of a steering wheel attached to the mounting section 833, as indicated by the double arrow.

[0110] An adjusting drive 85 for longitudinal adjustment of the actuating unit 83 relative to the outer shell 84 in the direction of the longitudinal axis L2 has a spindle drive with a spindle nut 851 into which a threaded spindle 852 extending along its spindle axis engages, i.e., its external thread is screwed into the corresponding internal thread of the spindle nut 851. The spindle axis runs essentially parallel to the longitudinal axis L2.

[0111] The spindle nut 851 is rotatably mounted about the spindle axis in a drive housing of a drive unit, which is fixedly connected to the outer shell 84. In the direction of the spindle axis, the spindle nut 851 is axially supported on the outer shell 84 via the drive unit.

[0112] The threaded spindle 852 is connected to the inner shell 831 of the actuating unit 83 via a connecting element, the ball joint, formed at its rear end, and is fixed in the direction of the longitudinal axis L2 and fixed with respect to rotation about the spindle axis. A so-called plunge spindle drive is realized by means of the rotatable spindle nut 851 and the threaded spindle 852, which is fixed with respect to rotation.

[0113] The transmission element extends from the actuating unit 83 through a slot in the outer casing 84. To adjust the steering column 10 longitudinally, the transmission element can be moved freely along the slot in the longitudinal direction. thyssenkrupp Presta AG 16 250020P10WO / 25016-EPS thyssenkrupp AG

[0114] The adjusting drive 85 has a drive unit with an electric actuator motor, by which the spindle nut 851 can be rotated relative to the stationary threaded spindle 852 relative to the drive housing. Depending on the direction of rotation of the actuator motor, this allows the threaded spindle 852 to be displaced translationally relative to the spindle nut 851 in the direction of the spindle axis, so that the inner shell 831 of the adjusting device 83, connected to the threaded spindle 852, is adjusted relative to the outer shell 84, connected to the spindle nut 851, in the direction of the longitudinal axis L2.

[0115] Fig. 9 shows a longitudinal section through the steering column 10 along the longitudinal axis L2, with the actuating unit 83 omitted. Its inner casing 831 is telescopically adjustable in an axial passage 843 of the outer casing 84 in the longitudinal direction, as indicated by the double arrow.

[0116] A guide element 9 according to the invention is attached to the inside of the passage 843, which is shown separately in a perspective view in Fig. 10. Preferably, several guide elements 9 can be distributed around the circumference, so that the inner shell 831 is slidably mounted on its outer surface exclusively in sliding contact with the guide elements 9.

[0117] The guide element 9 shown at the bottom in Fig. 9 can have a pressure spring element from which a radially inward, i.e. upward, pressing force can be exerted on the inner shell 831. This allows it to absorb the weight of the inner shell 831 and press it against the other guide elements 9 arranged above in sliding contact.

[0118] The guide element 9 has a tubular segment-shaped basic form, which in the example shown is designed as a hollow cylindrical profile segment. It has two longitudinally spaced sliding surfaces 91 (see Fig. 9) which are adapted to the outer surfaces of the inner shell 831 and bear against them in a planar sliding contact such that the latter is guided in a longitudinally adjustable sliding manner.

[0119] According to the invention, the guide element 9 is made of, or comprises, a ceramic material in the area of ​​the sliding surfaces 91. This allows a ceramic-metal sliding pair to be formed with the material of the inner sleeve 831, for example, steel. Alternatively, other materials can be used for the inner sleeve, for example, other metals, composite materials, or the like. thyssenkrupp Presta AG 17 250020P10WQ / 25016-EPS thyssenkrupp AG

[0120] Each sliding element 92 can have a sliding surface 91, which may be made of a ceramic material. The sliding elements 92 can be attached to a base body 93. This base body can, for example, be a plastic injection-molded part, preferably a one-piece part.

[0121] The sliding elements 92 can preferably be manufactured by injection molding according to the inventive method. To create a permanent, form-fit and material-fit connection, the base body 93 can be injection-molded onto the sliding elements 92.

[0122] Alternatively, it is possible that one or more sliding elements 92 together with the base body 93 are made of ceramic material, for example in one piece.

[0123] Fastening elements 94 project radially outwards from the outer surface of the base body 93. These elements may include, for example, spring-loaded detent elements and can engage or snap into corresponding detent receptacles, such as continuous detent openings in the outer shell 84, in a form-fitting manner. The fastening elements 94 are preferably formed integrally with the base body 93 by injection molding.

[0124] The fastening elements 94 can be arranged longitudinally between the sliding elements 92, as can be seen in Fig. 10.

[0125] The contact surfaces 91 can optionally be provided with molded recesses 95, which can serve as lubricant reservoirs and, as schematically indicated in the example, can have cross-shaped grooves. thyssenkrupp Presta AG 18 250020P10WQ / 25016-EPS

[0126] thyssenkrupp AG Reference List

[0127] 1 Steering system

[0128] 10 Steering column

[0129] 11 Steering shaft

[0130] 102 Steering wheel

[0131] 104 Steering sprocket

[0132] 106 gearing

[0133] 108 tie rod

[0134] 110 wheel

[0135] 112 Auxiliary power support 114 Auxiliary power support 116 Auxiliary power support 118 Torque sensor

[0136] 2 Rack and pinion

[0137] 3 Steering gear

[0138] 31 cases

[0139] 32 bore

[0140] 4 Pre-tensioning device

[0141] 41 Adjusting screw

[0142] 43 spring

[0143] 5 printing pieces

[0144] 51 Basic body

[0145] 6 sliding element

[0146] 61 Sliding surface

[0147] 62 depressions

[0148] 63 Positive locking elements 64 Undercut element 82 Support unit

[0149] 821 Fasteners

[0150] 822 Swivel bearing

[0151] 83 Actuator

[0152] 831 Inner jacket

[0153] 832 Steering spindle

[0154] 833 Fastening section 84 Outer casing

[0155] 841 Actuating lever

[0156] 85 Adjustment drive

[0157] 851 Spindle nut Thyssenkrupp Presta AG 19 250020P10WQ / 25016-EPS

[0158] thyssenkrupp AG

[0159] 852 Threaded spindle

[0160] 86 Adjustment drive

[0161] 9 Guide element

[0162] 91 Sliding surface

[0163] 92 sliding element

[0164] 93 Basic body

[0165] 94 Fastening element

[0166] 95 In-depth study

[0167] H Altitude

[0168] L1 axle (steering pinion)

[0169] L2 Longitudinal axis (steering spindle)

[0170] Z Longitudinal axis (of the rack 2)

[0171] V Preload axis (screw axis of adjusting screw 41)

Claims

thyssenkrupp Presta AG 1 250020P10WQ / 25016-EPS thyssenkrupp AG PATENT CLAIMS 1. Steering system (1) for a motor vehicle, comprising a sliding guide with guide parts (2, 5, 831, 9) having sliding contact surfaces (61, 91) that slid together, characterized by that at least one of the guide parts (5, 9) has a ceramic material in the area of ​​the sliding surface (61, 91).

2. Steering system according to claim 1, characterized in that the guide part (5, 9) has a sliding element (6, 92) formed from the ceramic material.

3. Steering system according to claim 2, characterized in that the sliding element (6, 92) is designed as an injection-molded part.

4. Steering system according to one of the preceding claims, characterized in that the guide part (5, 9) has a base body (51, 93) made of a non-ceramic material.

5. Steering system according to claim 4, characterized in that the base body (51, 93) has an injection-molded part connected to the sliding element (6, 92).

6. Steering system according to claim 5, characterized in that the at least one sliding element (6, 92) has an undercutting element (64) which is positively connected to the base body (51, 93).

7. Steering system according to one of the preceding claims, characterized in that the guide part (5, 9) has a lubricant reservoir (62, 95).

8. Steering system according to one of the preceding claims, characterized in that the sliding guide is formed between an actuator rod (2) and a housing (31) of a steering actuator (3).

9. Steering system according to one of the preceding claims, characterized in that the sliding guide between adjustable sleeves (84, 831) of a steering column (10) thyssenkrupp Presta AG 2 250020P10WO / 25016-EPS thyssenkrupp AG is arranged.

10. Method for manufacturing a steering system comprising a sliding guide with two guide parts (2, 5, 831, 9) having sliding contact surfaces (61, 91) according to one of the preceding claims, characterized by that at least on one of the guide parts (5, 9) a sliding element (6, 92) made of ceramic material is formed.

11. Method according to claim 10, characterized in that the sliding element (6, 92) is manufactured in an injection molding process.

12. Method according to claim 11, characterized in that an injection-molded part is provided from a thermoplastic or thermosetting polymer filled with ceramic particles in an injection molding process, in which the ceramic particles are sintered to form a solid sintered body by subsequent thermal treatment and from which the sliding element (6, 92) is then formed.

13. Method according to one of the preceding claims 10 to 12, characterized in that a base body (51 , 93) is produced which is connected to the sliding element (6, 92).

14. Method according to claim 13, characterized in that the base body (51, 93) is manufactured as a plastic injection molded part.

15. Method according to claim 14, characterized in that at least one sliding element (6, 92) is injection-molded onto the base body (51, 93).

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