Operating unit for a motor vehicle steer-by-wire system

Abstract

The invention relates to an operating unit for a motor vehicle steer-by-wire system, which can be connected to a steering device, such that a steering action of the steering device is converted into a signal representing the steering action and is transmitted to a wheel actuator for the execution of the steering action by means of the wheels of the motor vehicle, wherein the operating unit has a telescopic slide mechanism comprising a telescopic carrier and a telescopic slide which is translatable relative to the telescopic carrier, wherein a steering shaft is rotatably mounted in and / or on the telescopic slide, and a rotary angle limiter is arranged in the telescopic slide, and an electrically energizable force feedback actuator with an electrically energizable motor and an electrically energizable brake is arranged in the telescopic slide, and a first linear bearing is arranged between the telescopic slide and the telescopic carrier, and at least one second linear bearing is arranged at a distance in the telescopic direction, wherein the structure consisting of the telescopic slide, the brake, the motor and the rotary angle limiter has a total mass of more than 2 kg, preferably more than 3 kg.

Description

Technical Field

[0001] This invention relates to an operating unit for a vehicle steer-by-wire system. The operating unit is connectable to a control device, such that the steering action of the control device is converted into a signal representing the steering action and transmitted to a wheel actuator to execute the steering action through the wheels of the vehicle. The operating unit has a telescopic sliding mechanism, including a telescopic support member and a telescopic slider translatably disposed relative to the telescopic support member. A steering shaft is rotatably mounted in and / or on the telescopic slider. An angle limiter and a power-feedback actuator with an energized motor and an energized brake are disposed in the telescopic slider. A first linear bearing and at least one second linear bearing spaced apart along the telescopic direction are disposed between the telescopic slider and the telescopic support member. Background Technology

[0002] In today's automotive industry, the continuous development of new technologies is crucial for improving vehicle performance, safety, and driving comfort. Steering technology is one area that has received significant attention, especially "steer-by-wire" systems, which replace the mechanical steering column with an electrical signal system, offering numerous advantages over traditional steering systems. These systems enable flexible design, lighter vehicle weight, and superior driving dynamics. Steer-by-wire systems in motor vehicles eliminate the mechanical connection between the steering wheel and the wheels, transmitting the driver's steering inputs through electronic control units and actuators. The core advantage of this technology lies in its ability to dynamically adjust steering characteristics, thereby optimizing driving stability and handling under different speeds and road conditions. Furthermore, the absence of a mechanical connection provides more space for innovative vehicle design and expanded safety features. Manufacturers can therefore place the steering wheel anywhere within the vehicle, and even develop entirely new concepts of vehicles without traditional steering wheels. These systems not only enhance comfort and the driving experience but also facilitate the integration of autonomous driving functions. Improvements in feedback mechanisms and control algorithms ensure that the driver always has control of the vehicle, while laying the foundation for the future development of automated driving. Therefore, steer-by-wire systems represent a significant development in vehicle steering technology, with the potential to fundamentally change the way vehicles are designed and operated.

[0003] Despite significant advancements in steer-by-wire systems, known operating units still suffer from a number of drawbacks, particularly regarding acoustic emission and structural acoustics. A major problem is that the mechanical and electrical components within the operating unit, such as force feedback actuators, brakes, or bearings, generate vibrations and noise during operation. This noise is not only audible inside the vehicle but can also be transmitted to adjacent vehicle components via structural acoustics. These acoustic and vibrational disturbances are often perceived as uncomfortable and annoying by occupants, severely impacting the perceived quality of the vehicle.

[0004] Structure-transmitted acoustic emissions are particularly critical, as they can be transmitted to the vehicle chassis and occupants via mechanical connections. These emissions are caused, for example, by vibrations from electric motors, brakes, or other moving parts. Another drawback is that existing structure-transmitted acoustic suppression methods typically rely on heavy and bulky individual damping elements, which increases the installation space and significantly adds to the weight of the operating unit. This negatively impacts integration into modern vehicles, which demand compact and low-noise systems.

[0005] Overall, there is an urgent need for improved steer-by-wire operating units in the existing technology to minimize acoustic and vibration defects without compromising functionality, compactness, and reliability. Summary of the Invention

[0006] The objective of this invention is to avoid or at least reduce the problems known in the prior art and to provide an acoustically optimized operating unit for a vehicle steer-by-wire system.

[0007] This invention achieves the above-mentioned task through an operating unit for a motor vehicle steer-by-wire system. The operating unit can be connected to a control device, such that the steering action of the control device is converted into a signal representing the steering action and transmitted to the wheel actuators to execute the steering action through the wheels of the motor vehicle. The operating unit has a telescopic sliding mechanism, including a telescopic support member and a telescopic slider translatably disposed relative to the telescopic support member. A steering shaft is rotatably mounted within and / or on the telescopic slider. An angle limiter and a power-feedback actuator with an energized motor and an energized brake are disposed within the telescopic slider. A first linear bearing and at least one second linear bearing spaced apart along the telescopic direction are disposed between the telescopic slider and the telescopic support member. The total sound absorption mass of the structure consisting of the telescopic slider, brake, motor, and angle limiter is greater than 2 kg, preferably greater than 3 kg.

[0008] By achieving the desired total structural acoustic absorption mass of the operating unit within a specified parameter range, mechanical vibrations can be effectively suppressed and acoustic emissions further reduced. Heavier components, such as brakes, can absorb the energy of structurally transmitted sound waves more efficiently, thereby reducing, for example, the transmission of vibrations caused by the electric motor to the steering wheel. This measure not only helps reduce noise interference within the vehicle but also results in a smoother and more comfortable driving experience.

[0009] First, the various components or parts of the steer-by-wire system will be described, followed by examples of particularly preferred embodiments.

[0010] steer-by-wire system In this patent application, a steer-by-wire system refers to a steering system for a motor vehicle that eliminates the mechanical connection between the operating unit and the steering mechanism used to adjust the wheels. Instead, it transmits steering actions and commands electronically, thereby achieving precise and flexible control of the vehicle. Steer-by-wire systems offer significant advantages over traditional steering systems in terms of weight savings, design freedom, and driving comfort. In particular, eliminating the steering column and mechanical components reduces vehicle weight and complexity, while allowing for more flexible interior space layout.

[0011] The functions of a steer-by-wire system include, for example, converting steering wheel movements into electronic signals and sending them to a control unit. This control unit analyzes the input and controls the steering actuators of one or more wheels to bring the wheels to the desired steering angle. This enhances adaptability to different driving situations and facilitates the integration of additional functions such as lane-keeping assist or autonomous driving.

[0012] motor vehicles In this patent application, a motor vehicle refers to a motorized land vehicle used for transporting people or goods, particularly suitable for roads. It includes all types of vehicles powered by an engine, including but not limited to automobiles, trucks, buses, and motorcycles. Motor vehicles may employ different drive systems, such as internal combustion engines, electric motors, or hybrid power systems.

[0013] Front axle steering In this application, front axle steering refers to a component of a motor vehicle used to control the direction of the front wheels in order to steer the vehicle according to the requirements of the driver and / or control program.

[0014] Operation unit In this patent application, the operating unit refers to a device for controlling the direction of a motor vehicle by a user, particularly for a steer-by-wire system. This operating unit converts the driver's steering actions into electronic signals to adjust the actual steering action of the vehicle's wheels. The core task of the operating unit is to provide the driver with a steering feel as close as possible to that of a mechanical steering system, achieving intuitive and safe vehicle control. To this end, the operating unit can provide variable resistance torque on the steering shaft, thereby generating tactile feedback, and can be adjusted according to driving conditions.

[0015] Force feedback actuator In this invention, a force feedback actuator is a device designed to transmit tactile and / or force feedback to the driver by applying force to a control mechanism in contact with the driver. This feedback simulates the feel of force transmission in conventional mechanical or hydraulic steering. The force feedback actuator generates force via electronic control commands to reflect the current driving state and road conditions, thereby providing the driver with a realistic steering feel. The force feedback actuator can employ various elements or components, such as electric motors, brakes, solenoid coils, or other suitable devices, to generate the desired force.

[0016] Force feedback actuators can operate actively (e.g., electrically) or passively (e.g., through generators). In active mode, the actuator is driven by an external energy source, such as an electric motor, to apply force to the control device to generate tactile feedback. This means the actuator is controlled to provide perceptible feedback to the user, such as simulating real forces in a vehicle's steering input. In passive mode, the actuator operates as a generator, converting and utilizing or dissipating the kinetic energy generated by the control device or other user interactions. In this mode, external drive is not necessarily required; instead, the mechanical energy input from the control device is used to generate resistance or damping. This mode is particularly useful for improving efficiency and energy saving because it utilizes regenerative forces and provides additional realistic tactile feedback. By flexibly switching between active and passive modes, force feedback actuators can efficiently meet different tactile feedback needs and can dynamically switch according to requirements, load conditions, or applications.

[0017] Preferably, the force feedback actuator includes an electric motor, particularly a gearless electric motor.

[0018] In addition, the force feedback actuator may include a brake.

[0019] Particularly preferably, the force feedback actuator includes an electric motor and a brake, especially preferably an energized brake.

[0020] electric motor In this patent application, the electric motor is a motor device used in the force feedback actuator of the operating unit to apply torque to the steering shaft in a targeted manner to transmit tactile feedback to the driver regarding driving conditions or specific steering resistance. The electric motor can be actively controlled to generate specific resistance or auxiliary torque based on driving parameters, road conditions, or driver assistance systems, thereby achieving controlled steering feel.

[0021] The electric motor consists of a stator and a rotor assembly. The rotor is preferably connected to the steering shaft directly or via gears, thereby transmitting torque to the steering shaft through targeted current control. The electric motor can be designed as a radial flux motor or an axial flux motor.

[0022] The electric motor can operate with or without gears. Gear connections allow for adjustment of torque and speed to suit the specific needs of the operating unit. Preferably, planetary or harmonic gears are used to achieve efficient and low-backlash precision torque transmission. Gear connections are particularly suitable for applications requiring a high-speed, small motor to convert torque into a suitable force feedback system. Alternatively, the electric motor can operate gearless when direct torque transmission to the steering shaft is required.

[0023] brake In this patent application, a brake is a device within an operating unit for purposefully applying controlled power to the steering shaft to influence, limit, or dampen its movement. The brake can be used in particular to provide specific resistance to the rotational movement of the steering shaft to create a realistic steering feel for the driver or to achieve safety-critical limitations on steering actions.

[0024] The brake can preferably be an electromagnetic or electromechanical structure, allowing its braking force to be actively adjusted by a control unit. In a preferred embodiment, the brake includes an energized braking component that applies a frictional, magnetic, or fluid-based braking force to a component connected to the steering shaft. The braking force can be dynamically adjusted according to different operating parameters, such as vehicle speed, steering angle, or driving conditions.

[0025] Particularly preferably, the brake can be a magnetorheological brake.

[0026] The brake can also be a mechanical friction brake, wherein brake pads press against a braking surface connected to the steering shaft, thereby achieving a torque-related steering shaft delay. In another preferred embodiment, the brake can also be an eddy current brake, which generates a magnetic field through induction to brake a conductive disc, achieving a wear-free and virtually noiseless braking effect. Alternatively, the brake can also be an electromechanical clamping device, which uses electrically or magnetically driven clamping elements to specifically suppress or completely prevent rotation of the steering shaft.

[0027] Preferably, gears (such as planetary gears) can also serve as brakes in the sense of this patent application. Due to their internal friction, gears can brake the steering shaft, suppressing or slowing rotational motion. In particular, by specifically adjusting the gear ratio and friction characteristics, a certain amount of basic friction can be provided without additional active braking components or assistance. Such gears can be integrated into the entire system to dampen steering actions or provide specific drag characteristics to simulate traditional mechanical steering.

[0028] Preferably, the brake is integrated within the telescopic slider to achieve a compact structure and optimized mass distribution. The brake can be positioned between the angle limiter and the electric motor, thus working synergistically throughout the steering resistance and feedback system. The brake can be designed to continuously provide modulated power or to actively engage under specific operating conditions, such as to limit the maximum steering angle or generate specific tactile feedback. In a particularly preferred embodiment, the brake can be coupled to the electric motor, with both working together to achieve fine-tuning of the steering feel.

[0029] Magnetorheological braking device In this patent application, a magnetorheological braking device is a device that utilizes a magnetorheological medium to generate a variable and controllable torque between a rotor and a stator. The magnetorheological medium is preferably a liquid or gaseous carrier fluid dispersed with magnetizable particles. When a magnetic field is applied, these particles align along the magnetic field lines, causing an increase in the medium's viscosity and a significant increase in its shear strength. By adjusting the magnetic field strength, precise control of the braking force can be achieved. The magnetorheological braking device is preferably designed with a rotatable shaft passing through a rotor, the rotor being coaxially arranged on the shaft. The rotor is preferably made of a thin plate and is housed within a housing along with the stator, the housing forming a space for accommodating the magnetorheological medium. The stator is equipped with magnetic coils that generate a magnetic field when energized, affecting the magnetorheological medium within the accommodating space. By controlling the magnetic field, a variable braking force is generated between the rotor and the stator; when the magnetic field is activated, the shear strength of the medium increases. Preferably, the magnetorheological braking device is equipped with seals to prevent leakage of the medium from the braking housing and to protect the internal components of the brake from contamination.

[0030] Multiple magnetorheological braking devices can also be advantageously employed to achieve a higher total braking torque. This configuration also allows braking force to be distributed to multiple axes or components of the operating unit, improving the system's flexibility and adaptability. By using multiple braking devices simultaneously, the braking effect can be controlled more precisely because each unit can be controlled independently. This is particularly advantageous in complex systems or applications requiring different braking torques from different parts. Furthermore, the redundancy of multiple braking devices improves operational safety; even if one unit fails, the others can still function normally.

[0031] Dividing the brake into multiple independent braking units also reduces the inductance of each braking segment. Lower inductance means a shorter coil response time, allowing current changes to occur more quickly, thus optimizing the brake's dynamic response. A faster dynamic response means the brake can react more quickly to changing operating conditions, which is particularly advantageous in applications with rapidly changing load demands.

[0032] It is also conceivable that a magnetorheological brake has two spatially separated excitation coils. This configuration allows for more targeted and flexible control of the magnetic field, generating different magnetic field strengths in different regions of the magnetorheological medium. The spatial separation of the excitation coils can generate independent magnetic fields that act on specific particle concentrations or movements within the medium. This benefits by allowing for individual adjustment of the braking force according to the needs of different operating conditions. Furthermore, this arrangement allows for more uniform heat distribution, improving the thermal stability of the braking device. Redundancy is also achieved through the second excitation coil, ensuring that even if one set of excitation coils fails, the other set remains functional.

[0033] The excitation coils can preferably be connected in parallel. The parallel use of coils within a magnetorheological braking device offers significant advantages in terms of dynamic response and compensation capability. By connecting inductors in parallel, the total magnetic field capacity increases, the system response time accelerates, and the magnetorheological medium responds to magnetic field changes more quickly. This improves the brake's dynamic response, allowing for more precise and direct adjustment of braking force to adapt to changing operating conditions. Another advantage of parallel connection is enhanced system compensation capability. If one coil in the parallel connection fails or malfunctions, the remaining coils can still effectively generate the required magnetic field, thereby improving the reliability and fault tolerance of the braking device.

[0034] Brake rotor In this patent application, the brake rotor of the magnetorheological brake is a rotating element directly connected to the rotor shaft, serving as the active braking component in the system. The brake rotor interacts directly with the magnetorheological medium, which is located between it and the brake stator. The function of the brake rotor is to convert the change in viscosity of the magnetorheological medium into the required braking force through its rotation in the magnetic field. This allows for adjustment and control of the braking torque acting on the shaft, achieving precise adjustment of the braking effect of the entire steering system. Preferably, the brake rotor can be manufactured as a thin-plate brake rotor.

[0035] Braking stator In this patent application, the brake stator is a component fixedly mounted relative to the brake housing in a magnetorheological brake. As the stationary part of the brake, it is preferably made into a cylindrical sleeve. The brake stator houses the brake rotor and, together with the brake housing, forms a magnetorheological medium space, in which the medium resides. Preferably, the brake stator is designed to have an inner circumferential surface, allowing the rotor to move along a specific working gap formed therein. The function of the brake stator is to absorb the braking torque transmitted by the brake rotor through the medium, thereby ensuring reliable force transmission of the steering system.

[0036] The braking stator of the magnetorheological braking device is preferably a multi-piece structure, including a coil support, a closed ring, and an outer tube. These components are preferably made of sheet material through a forming process. Preferably, these components are interconnected by a forming connection method, thereby forming a large-area, compact contact between the stator components. This reduces the magnetic reluctance within the assembly, thus significantly improving magnetic circuit efficiency. The reduction in magnetic reluctance helps to achieve higher braking torque without increasing the coil current, improving the energy efficiency of the braking device, and enabling a more compact and lower-cost electrical component design.

[0037] magnetic field generator In this patent application, the magnetic field generator is a device within the magnetorheological brake that generates or influences the electromagnetic field, used to specifically adjust the flow characteristics of the magnetorheological medium. The generated magnetic field penetrates the medium space formed by the brake rotor and brake stator, altering the rheological properties of the medium, thereby increasing its shear viscosity and establishing a corresponding braking torque. Preferably, the magnetic field generator can be made as an energized electromagnet, with the coil wound on a ferromagnetic core, and the magnetic field lines are specifically guided to the working area through appropriate shaping. Its advantage is that the braking torque can be steplessly adjusted according to the applied current, achieving precise and rapid adaptation to different driving conditions in the steer-by-wire system. Preferably, the magnetic field generator is integrated into the brake housing or brake stator area to achieve a short magnetic flux path and efficient coupling with the medium. Alternatively, a permanent magnetic field source can be used as a replacement or supplement to the electromagnet to provide a basic magnetic field or to achieve fault protection.

[0038] To produce a braking effect, the magnetic field generator can be designed to be controllable, enabling it to generate a magnetic field with a predetermined field strength and / or a predetermined magnetic flux when controlled. Specifically, the magnetic field generator can be configured to adjust the field strength and / or magnetic flux between zero and a predetermined maximum value. In this way, the resulting initial braking effect can also be controlled or adjusted. For this purpose, the magnetic field generator can be made as a coil, whose magnetic field depends on the current flowing through the coil windings. By adjusting the current intensity, the field strength and / or magnetic flux can be adjusted between zero and a predetermined maximum value, thereby regulating the braking effect. The magnetic field generator is preferably housed within the braking stator of the magnetorheological brake.

[0039] magnetorheological media In this patent application, the magnetorheological medium is a substance whose rheological properties, particularly viscosity and flowability, change according to an applied magnetic field. It comprises, for example, a liquid or gaseous carrier fluid in which magnetizable particles are dispersed. These particles are preferably spherical or near-spherical, possess magnetic permeability, and are responsive to the magnetic field. The carrier fluid is preferably oil or other suitable liquid medium, or a gas such as air, ensuring uniform suspension and easy movement of the particles in the absence of a magnetic field. In this invention, the magnetorheological medium is used to achieve adjustable mechanical energy transfer. When a magnetic field is applied, the magnetizable particles align along the magnetic field lines, forming a chain-like structure. This structure significantly increases the flow resistance of the medium, allowing for targeted adjustment of torque transmission between the rotor and stator. The intensity of this torque transmission can be adjusted by the intensity of the applied magnetic field, thereby achieving precise and dynamic adjustment of braking characteristics.

[0040] The preferred particle concentration in the carrier fluid is 20 to 50 volume percent. A concentration of approximately 30 to 40 volume percent is particularly advantageous because it achieves an optimal balance between maximizing the magnetorheological effect and minimizing viscosity in the absence of a magnetic field. This concentration facilitates precise tuning of rheological properties while ensuring good pumpability and operability of the medium within the system.

[0041] magnetorheological particles In this patent application, magnetorheological particles refer to magnetizable or magnetically responsive particles suspended in a carrier fluid that can be selectively altered by a magnetic field to change the fluid's flow characteristics. Preferably, these particles are made of iron or iron alloys, possessing high magnetic permeability, and can rapidly form chain-like structures when a magnetic field is applied, thereby increasing the viscosity or flow resistance of the magnetorheological medium. These particles enable rapid and controllable enhancement of the shear force between the rotor and stator, which is beneficial for adjusting the braking effect. Their ability to rapidly and reversibly adjust their arrangement in a magnetic field allows for precise and dynamic adjustment of braking characteristics with almost no delay.

[0042] The particles are preferably coated to reduce agglomeration and sedimentation, thus maintaining a uniform distribution in the carrier medium even during long-term operation. The carrier liquid is preferably made of materials with high thermal stability and low aging properties to ensure the performance of the medium under different thermal and mechanical conditions. The magnetizable particles in the magnetorheological medium are preferably made of ferromagnetic or superparamagnetic materials. Suitable materials include iron, nickel, cobalt and their alloys or ferrite compounds such as iron oxide (Fe3O4). These materials have high magnetic permeability and saturation magnetization, enabling efficient response to applied magnetic fields.

[0043] The particle size is preferably between 0.1 micrometers and 10 micrometers, with 1 micrometer to 5 micrometers being particularly desirable. This particle size distribution ensures stable suspension of the particles in the carrier liquid, reduces sedimentation, and ensures that the particles can form structures quickly and efficiently when a magnetic field is applied.

[0044] Brake housing In this patent application, the brake housing of the magnetorheological brake is a component of the external covering structure of the brake, enclosing and forming a accommodating space for the magnetorheological medium (magnetorheological medium space). The main function of the brake housing is to safely enclose the magnetorheological medium and enable the interaction of the medium between the brake rotor and the brake stator. Because the brake housing forms a "frame structure," it not only protects the internal components from external influences but also serves as a basis for the proper alignment of all internal parts.

[0045] The brake housing can be made of a variety of materials, with metal alloys, plastics or composite materials being preferred.

[0046] Brake housings can be either one-piece or multi-piece structures. One-piece housings offer high structural integrity and reduce potential weak points caused by connections. Multi-piece housings, on the other hand, support a more modular structure, facilitating maintenance and replacement of individual components.

[0047] In principle, it is also conceivable that the stator may be at least partially or entirely used as a brake housing or a part thereof.

[0048] Steering shaft In this patent application, the steering shaft is a mechanical component in the operating unit used for a steer-by-wire system, serving as a rotational shaft for transmitting torque and / or rotational motion. The steering shaft is designed to rotate about a specific axis and is mechanically connected to the operating unit's control mechanism (such as a steering wheel or joystick). Its primary function is to transmit the rotational motion generated by the control mechanism to subsequent mechanical or electronic components within the operating unit.

[0049] Steering shafts can be single-piece or multi-piece structures. Single-piece structures offer high structural integrity and extremely high torque transmission accuracy because there are no additional connection points. Multi-piece steering shafts facilitate modular design, with different sections specifically designed for different needs. Multi-piece structures can also integrate joints or couplings to achieve flexible connections between sections and compensate for tolerances. This structure also facilitates maintenance or replacement of individual sections and better adapts to complex installation space requirements.

[0050] Preferably, the steering shaft is installed in a steering angle limiter, which mechanically restricts the rotational movement of the steering shaft.

[0051] The brake rotor is preferably fixedly connected to the steering shaft.

[0052] Telescopic sliding mechanism In this patent application, the telescopic sliding mechanism is a mechanical unit comprising a telescopic support member and at least one telescopic slider that is capable of translational movement relative to it. The telescopic sliding mechanism enables controlled linear movement between these two components, with the telescopic slider guided within a defined range along the telescopic direction. Guiding is preferably achieved via at least two linear bearings, ensuring both precise motion guidance and the mechanical stability of the entire system.

[0053] Multiple functional units of the operating unit can be integrated inside the telescopic slider. Preferably, this includes a force feedback actuator with a motor and a magnetorheological brake, as well as an angle limiter. This compact integration achieves a space-saving structure for the operating unit.

[0054] The telescopic sliding mechanism is also designed to ensure reliable thermal isolation between its components, especially through the selection of materials with specific thermal conductivity and the optimization of the arrangement of heat-generating parts.

[0055] linear bearings In this patent application, the linear bearing is a mechanical device that enables precise, low-friction guidance and movement of a telescopic slider relative to a telescopic support member along a linear axis.

[0056] Linear bearings can be either linear rolling bearings or linear sliding bearings. Linear rolling bearings use rotating or spherical elements, such as balls or rollers, arranged between guide members and bearing components. These rolling elements roll between contact surfaces, thus minimizing friction. These bearings typically include rolling element guides, cages for positioning the rolling elements, and seals to prevent contamination. Linear sliding bearings, on the other hand, have no rolling elements; the contact surfaces of the bearing components slide directly on the guide members, and they are commonly made of low-friction materials such as polytetrafluoroethylene (PTFE) or coated metals. Due to direct sliding, sliding bearings dissipate heat more easily, and their mechanical structure is simpler than that of linear rolling bearings.

[0057] Preferably, linear bearings also contribute to the thermal isolation of the system through their thermal conductivity characteristics, thus meeting the requirements of the overall system.

[0058] Telescopic slider In this patent application, the telescopic slider is a component of the telescopic sliding mechanism, capable of translational movement relative to the telescopic support member. The telescopic slider is particularly used to achieve linear movement of the operating device within the operating unit.

[0059] The telescopic slider is preferably made of a material with a thermal conductivity of 30 to 50 W / m*K to ensure controlled heat dissipation and minimize thermal stress. The outer peripheral surface of the telescopic slider is designed to have a large area to facilitate heat dissipation and convection, thereby further reducing the thermal load on the unit.

[0060] The core components of the force feedback system are preferably arranged inside the telescopic slider. These include, in particular, an energized electric motor located at the end furthest from the operating device, and a magnetorheological brake for precise control of the return torque. This arrangement achieves a compact, space-saving structure and optimizes the location of the heat source, preventing overheating of the operating unit.

[0061] The telescopic slider is preferably a tubular structure, and more preferably has a polygonal cross-section. The polygonal cross-section effectively prevents the slider from rotating about its longitudinal axis, further improving guiding stability and positioning accuracy.

[0062] Expansion load-bearing components In this patent application, the telescopic carrier is a component of the operating unit, providing a basis for guiding the telescopic slider. As a fixed element relative to the vehicle, the telescopic carrier guides the telescopic slider in translational direction along its defined axis. Therefore, it constitutes the mechanical interface between the movable slider and the rest of the steering system.

[0063] The telescopic carrier may also be provided with mounting points or connection interfaces for additional components (such as sensors or actuators) that are essential for the operation of the steering system. Furthermore, the telescopic carrier can be connected to the steering column adjustment device, particularly to enable tilt adjustment of the operating unit relative to the driver.

[0064] Corner limit switch In this patent application, the angle limiter is a device used to mechanically or functionally limit the maximum rotation angle of the steering shaft within an operating unit. The angle limiter ensures that the steering angle of the operating device does not exceed a predetermined limit to prevent damage to mechanical or electronic components, while ensuring precise control of steering actions.

[0065] The function of the angle limiter is particularly that when the preset maximum angle is reached, it physically prevents the rotation of the steering shaft or generates an increasing reaction force.

[0066] Preferred Implementation According to a preferred embodiment of the present invention, the structural sound transmission contact area between the telescopic slider and the telescopic bearing, specifically the first linear bearing or the second linear bearing, can be set to be less than 5 cm² for each linear bearing. 2 And the total length of the two linear bearings is less than 30cm. 2 The advantage of this operating unit lies in its ability to significantly reduce disruptive vibrations and noise by controlling the structural sound-transmitting contact area of ​​the linear bearing within a specified range, thereby significantly improving the acoustic comfort inside the vehicle. In particular, this measure reduces structural sound transmitted to the steering unit from the electric motor and / or brakes. This is of great significance for improving the overall perceived quality of the vehicle and meeting the modern vehicle requirements for comfort and noise reduction.

[0067] According to a further preferred improvement of the invention, the average surface roughness Rz of the telescopic slider in its contact area with the first linear bearing and / or the second linear bearing is less than 63µm. Reducing the average roughness of the contact area of ​​the telescopic slider ensures quiet and uniform sliding or rolling motion in the linear bearings, while also reducing wear on the bearing components. It is necessary to reduce the acoustic excitation generated by these linear bearings because adjustment or retraction speeds far exceeding 30mm / s often occur in steer-by-wire systems, at which point the excitation increases.

[0068] According to another particularly preferred embodiment of the invention, a surrounding gap of 2-5 mm can be formed between the telescopic slider and the telescopic support member (except at the contact point with the linear bearing). This surrounding gap with a specific height helps reduce sound transmission between components, suppressing structural sound transmission in the telescopic integrated assembly, such as motor hum, brake noise, bearing running noise, or end-impact excitation, by acting as a barrier to structural sound transmission.

[0069] Furthermore, the invention can be further improved by having the electric motor operate via pulse width modulation at a frequency greater than 10 kHz. Using high-frequency pulse width modulation to drive the electric motor can reduce typical low-frequency noises such as howling or humming, achieving almost silent operation of the electric motor and improving the vehicle's acoustic comfort.

[0070] In another preferred embodiment, the motor and / or brake are mounted on the inner circumferential surface of the telescopic slider via an interference fit. This interference fit allows for an extremely stable and low-vibration connection within the telescopic slider. This not only reduces noise but also facilitates low-cost manufacturing and assembly without the need for additional connectors.

[0071] The invention can be further improved such that the average interference pressure between the motor and the inner circumferential surface of the telescopic slider and / or between the brake and the inner circumferential surface of the telescopic slider is 0.5-2.0 MPa. This specific interference pressure between the motor and / or brake and the inner circumferential surface of the telescopic slider not only achieves a stable mechanical connection but also specifically dampens structural sound transmission. The circumferentially segmented interference pressure zone provides a wide and variable pressure distribution because the segmented structure creates many edge regions. Although the mechanical strength of this structure may initially seem unsatisfactory in the low-pressure zone, it brings significant acoustic advantages. In the low-pressure zone, minute force vibrations (i.e., sound waves) can dissipate energy through the interference fit gaps or fretting between the telescopic slider and the motor and / or brake. These micro-frictions, accompanied by variable frictional forces (due to pressure changes), achieve effective "sound energy dissipation." In particular, the interference pressure zones between the motor and the telescopic slider, and between the brake and the telescopic slider, preferably locally and variablely withstand approximately 1 MPa, without a full circumferential interference fit. The combination of variable pressure and micro-motion achieves targeted damping because acoustic energy is dissipated through these micro-frictions. Overall, this significantly reduces interference noise and greatly improves the acoustic comfort of the operating unit.

[0072] According to a further preferred embodiment of the invention, the interference pressure is non-uniformly distributed and less than 0.5 MPa over at least 50% of the contact area. Preferably, the interference pressure between the motor and / or brake and the inner circumferential surface of the telescopic slider is non-uniformly distributed, thus forming a pressure variation zone. This varying pressure causes fretting in the low-pressure zone. These fretting generate micro-friction, accompanied by varying frictional forces, thereby contributing to acoustic energy dissipation. Especially in the "gap" between the motor and the telescopic slider, and between the brake and the telescopic slider, there is preferably no full-circumferential interference pressure, but rather a variable pressure value averaging 0.5-2.0 MPa. The locally lower pressure zone provides the possibility for energy loss from "micro-force vibrations," i.e., structural sound transmission. This special pressure design not only contributes to the acoustic optimization of the operating unit but also improves the noise reduction effect of the entire system.

[0073] Finally, the present invention may preferably design the first linear bearing and / or the second linear bearing as linear rolling bearings. Using linear rolling bearings as linear bearings improves the accuracy and smoothness of the telescopic slider movement. Rolling bearings have lower friction than sliding bearings, reducing wear and energy consumption. Acoustically, these linear rolling bearings or combinations of rolling / sliding bearings are particularly advantageous because rolling bearings have a smaller contact area (lower sound transmission). In hybrid rolling / sliding bearings, the sliding surface, like the aforementioned interference fit gap, dissipates sound energy through micro-movements at the contact point.

[0074] Preferably, the maximum moving speed of the telescopic slider during extension and retraction is 10-60 mm / s. This speed range achieves a balance between responsiveness and telescopic motion accuracy, which is particularly important in steer-by-wire systems. A maximum speed of 10 mm / s to 60 mm / s allows for rapid movement, suitable for situations requiring quick reset or positioning, such as when entering or leaving the vehicle. This speed range ensures that electrically adjustable actuators are not subjected to prolonged high loads, thus extending the lifespan of mechanical and electrical components. Furthermore, a defined maximum speed range improves interaction with automated or safety-critical functions, such as automatic steering wheel reset to zero. Speed ​​control enables harmonious and predictable movement, avoiding unexpected or sudden reactions. This is particularly important for system acceptance and driver trust in steer-by-wire technology.

[0075] Furthermore, the length x of the telescopic slider is preferably 200-350 mm. This length achieves an optimal balance between a compact structure and providing the necessary space for integrating all critical components, such as the steering shaft, magnetorheological brake, motor, and guide elements. This ensures that the telescopic slider can accommodate all necessary functional units without unnecessarily increasing the overall size of the operating unit. This is particularly advantageous in vehicles with limited cockpit space. Additionally, this length range facilitates more precise guidance of the telescopic slider relative to the telescopic carrier. Sufficient length allows for stable mounting of the slider in the guide, improving mechanical strength and operational safety. This minimizes undesirable movement, vibration, or tilting of the telescopic slider, ensuring precise force transmission and enhancing driving safety and handling. Moreover, this length increases the flexibility of the operating unit design. For example, the motor and brake can be strategically positioned to achieve optimal load distribution within the operating unit. This contributes to a balanced weight distribution, positively impacting the system's dynamic characteristics, such as inertial behavior and steering mechanism response.

[0076] Furthermore, the length of the telescopic carrier is preferably 110-350 mm. The main advantage of this dimension is improved mechanical stability. This length ensures reliable guidance of the telescopic slider even under high forces during operation. This minimizes vibration, torsion, or unwanted backlash in the system, improving steering input accuracy. Additionally, this length range allows the operating unit to adapt to different vehicle designs and space conditions. Flexible adjustment of the telescopic carrier length allows the operating unit to be integrated into both compact and spacious cockpits without fundamental design changes. This improves adaptability and reduces development and manufacturing costs when integrating across different vehicle models. Another advantage is improved kinematics of the telescopic movement. The specified telescopic carrier length allows for precise guidance of the telescopic slider within a sufficiently large adjustment range. This helps optimize driver ergonomics, as the position of the control device better adapts to the driver's individual needs and preferences. A wider adjustment range also facilitates adapting the operating unit to drivers of different heights or seating positions.

[0077] According to a preferred improvement of the invention, the telescopic slider preferably has a wall thickness of 1.5-3.0 mm along its length, achieving an optimal balance between stability, weight, and manufacturing cost, thus combining functional and economic advantages. From a technical perspective, this wall thickness ensures that the telescopic slider can safely withstand the forces and torques generated during the operation of the operating unit without deformation or structural weakness. This is particularly important because the telescopic slider needs to accommodate and guide the steering shaft and force feedback components. The slider weight obtained with the specified wall thickness also benefits system dynamics, as the slider can be moved with less energy. The 1.5-3.0 mm wall thickness also facilitates manufacturing, allowing for non-cutting processes such as deep drawing or bending, eliminating the need for complex machining.

[0078] Furthermore, the telescopic slider preferably has a length of 2700-5200 mm. 2 The cross-sectional area of ​​the slider ensures mechanical stability and provides acoustic advantages by increasing the slider's vibration eigenmode frequency. The slider is sufficiently robust to reliably withstand and transmit forces and torques generated during operation, particularly by the force feedback system. Simultaneously, slider deformation or bending is minimized, enabling precise and uniform force transmission, which is especially important in dynamic steering maneuvers. The slider's mass is also sufficiently high to absorb vibrations. Furthermore, this cross-sectional area results in low inertia, enabling rapid and precise slider movement. The mass is also high enough to dampen vibrations. This cross-section also provides sufficient space for integrating necessary force feedback components such as motors, magnetorheological brakes, angle limiters, and steering shafts.

[0079] In addition, the telescopic slider preferably has a diameter of 400-500 cm. 4The sectional moment of inertia within this range provides sufficient stiffness to avoid or reduce deformation under dynamic loads such as rapid steering or sudden load changes. Furthermore, the optimized sectional moment of inertia minimizes vibration and resonance effects in the system. The combination of stiffness and low deformation achieved within this range enables more precise translation of the telescopic slider along the telescopic support. This is particularly important when using linear bearings, as they are more sensitive to slider deformation due to the constant guiding force.

[0080] Preferably, the steering shaft is fixedly integrated in the telescopic slider's extension direction. By fixing the steering shaft to the telescopic slider, the movement of the steering shaft is ensured to be completely synchronized with the movement of the slider. By coupling the steering shaft to the telescopic slider, the load generated during steering actions is specifically distributed to the slider. Integrating the steering shaft into the telescopic slider also means that no additional guide elements or mounting points are needed outside the slider, which is particularly advantageous in vehicles with limited cabin space. Another advantage is improved vibration and noise damping.

[0081] Furthermore, particularly preferably, the brake, force feedback actuator, and angle limiter are arranged in the following order within the telescopic slider: starting from the far end near the control device, the angle limiter, brake, and force feedback actuator are arranged sequentially, facing away from the control device. Placing the angle limiter directly near the control device allows for precise mechanical restriction of the steering shaft directly connected to the control device, effectively limiting the maximum rotational movement of the control device without introducing mechanical backlash or delay from intermediate components. This direct arrangement provides precise restriction and enhances the driver's feedback. The brake and force feedback actuator are relatively heavy components; by placing them away from the angle limiter and closer to the far end, the center of gravity of the moving parts within the telescopic slider is optimized.

[0082] This arrangement also optimizes heat distribution within the telescopic slider. Because the force feedback actuator, as the primary heat source, is positioned at the far end, direct heat transfer to the corner limiter, brake, and steering wheel is minimized, ensuring the functionality of these components under high thermal loads. Simultaneously, the brake, located between the corner limiter and the actuator, acts as a heat absorber, further enhancing thermal isolation.

[0083] In another preferred improvement, the steering shaft preferably passes at least partially, and especially completely, through the brake, force feedback actuator, and corner stop. The main advantage of this arrangement is that it allows for a compact, space-saving structure for the operating unit. Furthermore, the axial passage of the steering shaft ensures precise alignment of all mechanical and electromagnetic components. This axial alignment reduces potential misalignment or mechanical backlash caused by independent arrangements or more complex coupling mechanisms. The accuracy of force transmission from the force feedback actuator to the steering shaft is thus optimized, improving steering precision and driver feedback. Another advantage is the reduction of required bearing points or additional connecting elements, which would be necessary if the steering shaft did not pass through these components. This not only reduces the weight of the operating unit but also lowers assembly complexity. Fewer bearing points also mean lower wear and higher reliability, as potential sources of failure such as bearing failure or misalignment are minimized. Finally, this structure also offers the advantage of minimized vibration and noise. Because the steering shaft passes directly and continuously through the brake, force feedback actuator, and corner stop, mechanical resonance and vibration are distributed more evenly.

[0084] Preferably, the telescopic slider is translatably mounted relative to the telescopic carrier via a first bearing (especially a linear bearing) and a second bearing (especially a linear bearing) spaced apart from it in the telescopic direction.

[0085] In this context, it is particularly preferable that the distance between the first and second linear bearings in the telescopic bearing direction is at least 80 mm. This reduces the risk of tilting motion that may occur when the slider is subjected to lateral forces or uneven loads. This ensures that the operating unit always maintains precise alignment, which is especially important during dynamic motion or under high system loads. A bearing distance of at least 80 mm also ensures that the load is distributed more evenly between the two bearings, reducing wear and load on individual bearing components. A bearing distance of at least 80 mm also dampens vibrations and oscillations generated during operation. Attached Figure Description

[0086] The invention will be further described below with reference to the accompanying drawings, but this is not intended to limit the general concept of the invention.

[0087] Figure 1 : A schematic diagram of a motor vehicle equipped with a steer-by-wire system.

[0088] Figure 2 : Perspective view of the operating unit.

[0089] Figure 3 : A perspective axial section view of the operating unit. Detailed Implementation

[0090] Figure 1The image shows a steer-by-wire system 1 for motor vehicle 2, equipped with a control device 45. The steer-by-wire system 1 includes an operating unit 4 located within the passenger compartment 141. This operating unit receives steering commands from a user or control device, such as part of an automatic or semi-automatic driving system of motor vehicle 2, and transmits them via electrical or optical signals to the wheel actuators 6 of the front axle steering 3. The latter translates the corresponding steering commands into steering actions of the vehicle's front wheels 7a and 7b. Of course, steering commands can also be achieved through rear axle steering or single-wheel steering.

[0091] The operating unit 4, located within the passenger compartment 141, acquires the driver's steering input via the control device 45 or receives corresponding signals from the vehicle's own control devices. After sensors acquire steering angle, torque, or other parameters, the signals are transmitted to the control electronics unit, which then transmits steering commands to the wheel actuators 6. The wheel actuators 6 convert electrical or optical control signals into mechanical steering actions, preferably through linkages or direct drive to the front axle wheels 7a, 7b, thereby achieving the desired steering angle. Preferably, the wheel actuators 6 may also be equipped with other sensors to return feedback on road conditions, forces, or individual wheel steering angles to the control electronics unit. This enables adaptive control strategies, such as stabilizing the vehicle in critical driving situations or initiating steering actions solely through the control device during autonomous driving. By eliminating the direct mechanical connection between the control device 45 and the steering mechanism, costs and space are saved, and the impact of vibrations or disturbances within the vehicle is reduced.

[0092] Figure 2 A perspective view of the operating unit 4 is shown. The operating unit 4 includes a telescopic sliding mechanism 46, which includes a tubular telescopic support member 138 and a telescopic slider 137 that can translate within it. Figure 2 The telescopic slider 137 is shown in the extended state of the telescopic sliding mechanism 46.

[0093] By translating the telescopic slider 137 within the tubular telescopic support 138, the axial position of the control device 45 relative to the driver can be precisely adjusted, thereby achieving optimal ergonomic distance. Figure 2 In the illustrated embodiment, the telescopic slider 137 is mounted with low friction within the inner guide rail of the telescopic carrier 138. The integration of the telescopic carrier 138 with the steering column adjustment device 42 also allows for adjustment of the tilt angle of the entire operating unit 4, enabling the driver to obtain a personalized seating and operating position. The steering shaft 43 is substantially coaxial with the telescopic slider 137 and the telescopic carrier 138, and extends from the telescopic slider 137 at the end near the control device. The control device 45 can be connected to this protruding shaft section, and the rotational motion of the control device 45 can be transmitted to the steer-by-wire system or collected within the system via the steering shaft 43.

[0094] Figure 3The internal structure of the telescopic slider 137 is shown. It can be seen that a force feedback actuator 41, a motor 109, and a brake 107 implemented as a magnetorheological brake 108 are arranged inside the telescopic slider 137. Furthermore, an angle limiter 44 is also arranged inside the telescopic slider 137. Figure 3 Clearly, the telescopic slider 137 is designed to compactly accommodate all the key functional components of the steer-by-wire system while providing axial adjustment functionality.

[0095] The steering shaft 43 passes through the angle limiter 44, the force feedback actuator 41, the electric motor 109, and the brake 107, and is connected to these components respectively. Torque can be applied to the steering shaft 43 via the electric motor 109 and the brake 107. The torque generated or applied by the electric motor 109 is transmitted to the steering shaft 43, giving the driver an active steering feel and targeted feedback through the steering wheel. A magnetorheological brake 108 is integrated into this force flow, achieving adjustable damping or braking torque by selectively changing the viscosity of its magnetorheological medium. This allows for stepless adjustment of the braking effect, achieving precise control over steering feel and self-centering force.

[0096] The angle limiter 44 provides a defined mechanical termination point in each rotational direction of the steering shaft 43. The angle limiter 44 detects the position of the steering shaft 43 and mechanically ensures that a defined termination torque is reached in both rotational directions, thereby preventing over-rotation or system damage. Since the steering shaft 43 passes through not only the angle limiter 44 but also the motor 109 and brake 107, it ensures coaxial alignment of all components, achieving high-precision, short-response-time force and torque management.

[0097] pass Figure 2-3 It can be clearly seen that the operating unit 4 has a telescopic sliding mechanism 46, including a telescopic support member 138 and a telescopic slider 137 that can translate relative to the telescopic support member 138.

[0098] The steering shaft 43 is rotatably mounted within the telescopic slider 137. Inside the telescopic slider 137 is arranged an angle limiter 44 and a power-feedback actuator 41 with an energized motor 102 and an energized brake 107. The arrangement order of the brake 107, the power feedback actuator 41, and the angle limiter 44 within the telescopic slider 137 is as follows: starting from the end closest to the operating device, the angle limiter 44, the brake 107, and the motor 102 are arranged sequentially, towards the end furthest from the operating device. The total sound absorption mass of the structure consisting of the telescopic slider 137, the brake 107, the motor 102, and the angle limiter 44 is greater than 2 kg, preferably greater than 3 kg.

[0099] The brake 107 is a magnetorheological brake 108, which is arranged in front of the motor 102 when viewed from the direction of the operating device 45.

[0100] A first linear bearing 136a and a second linear bearing 136b spaced apart along the telescopic direction are provided between the telescopic slider 137 and the telescopic support member 138. The structural sound transmission contact area of ​​the first linear bearing 136a or the second linear bearing 136b between the telescopic slider 137 and the telescopic support member 138 is less than 5 cm² for each linear bearing 136a and 136b, respectively. 2 Furthermore, the total length of the two linear bearings 136a and 136b is less than 30cm. 2 The telescopic slider 137 has an average surface roughness Rz of less than 63µm in the contact area with the first linear bearing 136a and the second linear bearing 136b.

[0101] Figure 2-3 It is also shown that a circumferential gap is formed between the telescopic slider 137 and the telescopic support member 138, with a gap height of 2-5mm.

[0102] Figure 2-3 It can also be seen that the motor 102 and the brake 107 are mounted on the inner circumferential surface of the telescopic slider 137 by an interference fit. The average interference pressure between the motor 102 and the inner circumferential surface of the telescopic slider 137, and between the brake 107 and the inner circumferential surface of the telescopic slider 137, is 0.5-2.0 MPa. The interference pressure is non-uniformly distributed and is less than 0.5 MPa over at least 50% of the contact area.

[0103] Figure 3 It is also shown that the steering shaft 43 is guided relative to the telescopic slider 137 via a first steering shaft bearing 133a and a second steering shaft bearing 133b. The steering shaft 43 at least partially, preferably completely, passes through the brake 107, the motor 102, and the angle limiter 44. The steering shaft 43 is fixedly integrated in the telescopic direction of the telescopic slider 137. List of reference numerals 1 - Steer-by-wire system 2 - Motor vehicles 4 - Operation Unit 6 - Wheel actuator 7 - Wheels 41 - Force Feedback Actuator 43 - Steering Axle 44 - Corner limit switch 45 - Control Device 46 - Telescopic sliding mechanism 102 - Electric Motor 107 - Brake 108 - Magnetorheological brake 133a - First Steering Shaft Bearing 133b - Second Steering Shaft Bearing 136a - First Linear Bearing 136b - Second linear bearing 137 - Telescopic slider 138 - Telescopic load-bearing component.

Claims

1. An operating unit (4) for a steer-by-wire system (1) of a motor vehicle (2), which can be connected to a control device (45) such that the steering action of the control device (45) is converted into a signal representing the steering action and transmitted to the wheel actuator (6) to execute the steering action through the wheels (7) of the motor vehicle (2), wherein, The operating unit (4) has a telescopic sliding mechanism (46) including a telescopic support member (138) and a telescopic slider (137) that is translatably disposed relative to the telescopic support member (138). A steering shaft (43) is rotatably mounted in and / or on the telescopic slider (137). An angle limiter (44) and a power-operable feedback actuator (41) with a power-operable motor (102) and a power-operable brake (107) are provided in the telescopic slider (137). A first linear bearing (136a) and at least one second linear bearing (136b) spaced apart along the telescopic direction are provided between the telescopic slider (137) and the telescopic support member (138). Its features are, The structure consisting of a telescopic slider (137), a brake (107), a motor (102), and a corner limiter (44) has a total sound absorption mass greater than 2 kg, preferably greater than 3 kg.

2. The operating unit (4) according to claim 1, characterized in that, Between the telescopic slider (137) and the telescopic bearing (138), the structural sound transmission contact area of ​​the first linear bearing (136a) or the second linear bearing (136b) is less than 5 cm² of each linear bearing (136a, 136b). 2 Furthermore, the total length of the two linear bearings (136a, 136b) is less than 30cm. 2 .

3. The operating unit (4) according to claim 1 or 2, characterized in that, The telescopic slider (137) has an average surface roughness Rz of less than 63µm in the area where it contacts the first linear bearing (136a) and / or the second linear bearing (136b).

4. The operating unit (4) according to any of the preceding claims, characterized in that, A surrounding sound insulation gap is provided between the telescopic slider (137) and the telescopic bearing (138), and the gap height is 2-5 mm except at the linear bearing.

5. The operating unit (4) according to any of the preceding claims, characterized in that, The electric motor (102) is driven by pulse width modulation at a frequency greater than 10 kHz.

6. The operating unit (4) according to any of the preceding claims, characterized in that, The electric motor (102) and / or the brake (107) are mounted on the inner circumferential surface of the telescopic slider (137) by an interference fit.

7. The operating unit (4) according to any of the preceding claims, characterized in that, The average interference pressure between the motor (102) and the inner circumferential surface of the telescopic slider (137) and / or between the brake (107) and the inner circumferential surface of the telescopic slider (137) is 0.5-2.0 MPa.

8. The operating unit (4) according to any one of claims 6-7, characterized in that, The interference pressure is non-uniformly distributed and is less than 0.5 MPa over at least 50% of the contact area.

9. The operating unit (4) according to any of the preceding claims, characterized in that, The first linear bearing (136a) and / or the second linear bearing (136b) are linear rolling bearings.

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