Steering device for a vehicle and method for operating a steering device for a vehicle

Abstract

The invention relates to a steering device (100) for a vehicle, comprising - a steering wheel (110), - a steering column (115) and - a steering linkage which is mechanically coupled to the steering column (115) by means of a steering gear (140). According to the invention, it is provided that - a first steered wheel (151) of a vehicle axle is mechanically coupled to a first wheel pivoting unit (150), wherein the first wheel pivoting unit (150) comprises the steering linkage and the steering gear (140), - a second steered wheel (161) of the same vehicle axle is mechanically coupled to a second wheel pivoting unit (160), wherein the second wheel pivoting unit (160) is designed as an actuator (162) mechanically decoupled from the steering linkage, - a detection device (120) is provided which is designed to detect steering inputs made by means of actuating the steering wheel (110), and - a control unit (130) which is designed to control the second wheel swivel unit (160) depending on the detected steering input. Furthermore, the invention relates to a method for operating the steering device (100).

Description

[0001] The invention relates to a steering device for a vehicle according to the preamble of claim 1 and a method for operating a steering device for a vehicle.

[0002] EP 3 458 336 B1 discloses a steer-by-wire steering system for motor vehicles with - two steered vehicle wheels with independent wheel steering, having - each an electronically controlled steering actuator assigned to a steered vehicle wheel, wherein the steering actuator has an actuator with an output shaft which, depending on a driver's steering request, causes a rotation of the vehicle wheel about a pivot axis by means of a rotation, - a feedback actuator designed to transmit a restoring torque to a steering wheel, and - a control unit that controls the feedback actuator and the steering actuators to generate drive power, and - a switchable clutch, which is designed in such a way that it - is normally open and separates the individual wheel steering systems from each other and - in a special case is closed and connects the individual wheel steering systems in such a way that a drive power can be transferred from one individual wheel steering system to the other individual wheel steering system to rotate a vehicle wheel, wherein the controllable clutch is connected to an actuator of a steering actuator via a flexible shaft.

[0003] Furthermore, vehicles are known with a steering column that transmits a driver's steering input via a steering wheel, through a steering gear, to a steering linkage, and from the steering linkage simultaneously to both wheels of an axle to be steered, so that they turn in accordance with the steering input. Steering-assist actuators are also known, which provide auxiliary energy for steering the wheels.

[0004] The invention is based on the objective of providing a novel steering device for a vehicle and a novel method for operating a steering device for a vehicle.

[0005] The problem is solved according to the invention by a steering device which has the features of claim 1 and a method which has the features of claim 7.

[0006] Advantageous embodiments of the invention are the subject of the dependent claims.

[0007] A steering device for a vehicle has - a steering wheel, - a steering column and - a steering linkage which is mechanically coupled to the steering column by means of a steering gear.

[0008] According to the invention, it is provided that - a first steered wheel of a vehicle axle is mechanically coupled to a first wheel swivel unit, wherein the first wheel swivel unit comprises the steering linkage and the steering gear, - a second steered wheel of the same vehicle axle is mechanically coupled to a second wheel swivel unit, wherein the second wheel swivel unit is designed as an actuator mechanically decoupled from the steering linkage, - a detection device is present which is designed to detect a steering input made by means of actuating the steering wheel, and - a control unit which is designed to control the second wheel swivel unit depending on the detected steering input.

[0009] The steering system combines a mechanical steering system with an electronically controlled steering system, a so-called steer-by-wire system, to create a hybrid steering architecture. This allows the steering system to combine the advantages of a mechanical coupling of a wheel to the steering wheel, thus providing a mechanical fallback, with the flexible adaptation of the steering kinematics to the current state of the vehicle and / or the driving situation of a steer-by-wire system.

[0010] A mechanical fallback level means that if a vehicle's electronics fail, especially components of an electronically controlled steering system component, the vehicle can still be maneuvered using the mechanically coupled steering system component, thereby increasing driving safety.

[0011] Pure steer-by-wire systems require safety measures to ensure continued driving safety in the event of a vehicle electronics failure. Since this is achieved in the proposed steering system through a mechanical fallback mechanism, the complexity and cost of the steering system are reduced.

[0012] Furthermore, the lack of mechanical coupling between the wheel swivel units results in a space advantage in the drive train, especially on a steered axle of the vehicle.

[0013] Furthermore, an existing mechanical architecture of the steering column can be adopted, thus reducing the design effort required to implement the steering device and enabling further cost reductions.

[0014] Furthermore, the steering system can be adapted for both left-hand drive and right-hand drive vehicles with minimal design effort.

[0015] In one possible embodiment of the steering device, the actuator is designed to pivot the second steered wheel using electrical and / or hydraulic and / or pneumatic energy. The availability of different energy sources for the actuator allows for a high degree of design flexibility.

[0016] In another possible embodiment of the steering device, the steering gear is designed as a planetary gear set. Besides its compact design, the planetary gear set offers the possibility of variably adjusting the steering ratio by selecting the operating mode, for example, various two-shaft or three-shaft operation. If the mechanical fallback system engages, the planetary gear set provides a higher steering ratio, thus ensuring the vehicle remains steerable and increasing driving safety.

[0017] In another possible embodiment of the steering device, the control unit is designed to actuate a power steering actuator, which then supplies the steering gear with auxiliary energy. This power steering assistance allows for easier steering and thus improved vehicle maneuverability.

[0018] In another possible embodiment of the steering device, the control unit is designed to variably control or regulate both the steering ratio and the steering kinematics. Two control chains or loops result in a very wide range of application possibilities for the system, allowing the non-mechanically coupled wheel to possess all degrees of freedom defined by the control or regulation system. Thus, the steering kinematics, in its current configuration, can be adapted to the respective driving conditions. This results in freely adjustable steering kinematics, for example, an Ackermann or anti-Ackermann characteristic, and a freely selectable steering ratio between the steering wheel and the steered wheel. This leads to a high degree of adaptability to different requirements and / or driving situations.An Ackermann characteristic generally refers to a situation where the inside wheel turns more sharply than the outside wheel in a turn, creating a common center point of the curve. This is intended to reduce tire wear and / or improve cornering stability. An anti-Ackermann characteristic generally refers to a situation where, for example, at high speeds, the outside wheel turns more sharply than the inside wheel to stabilize cornering and / or reduce understeer. Furthermore, a tie rod can be positioned asymmetrically between the wheels of the steered axle, as steering errors can be compensated for by the steering system.

[0019] In another possible embodiment of the steering device, the detection device is designed to determine a steering wheel angle and / or a steering torque and / or a vehicle speed and / or a yaw rate and / or a lateral acceleration. Such a multitude of input variables for controlling the system provides a particularly broad database and thus enables a highly targeted adaptation to a prevailing driving situation by incorporating various factors.

[0020] In the method for operating the aforementioned steering device, it is provided according to the invention that - the steering input is determined by means of the detection device, - depending on the determined steering input - the first wheel swivel unit is controlled by means of the steering gear in such a way that the first steered wheel is swivelled in and - the second wheel swivel unit is controlled by the control unit in such a way that the second steered wheel is swivelled in.

[0021] The method and its embodiments mentioned below lead to the same advantages in an analogous manner as the steering device and its embodiments.

[0022] In one possible embodiment of the method, it is provided that a value determined by the detection device is - a steering wheel angle and / or - a steering torque and / or - a driving speed and / or - a yaw rate and / or - a lateral acceleration is provided as an input variable for controlling or regulating the steering ratio of the first steered wheel.

[0023] In another possible embodiment of the method, it is provided that the control or regulation of the steering ratio serves as the output variable. - outputs a first wheel steering angle for the first steered wheel to the first wheel swivel unit, - outputs a control variable for auxiliary energy to be supplied to the steering gear to a power steering actuator, - transmits a value for the current state of the vehicle as an input variable to a control or regulation system for steering kinematics and - transmits a value for a second wheel steering angle of the second steered wheel as an input variable to the control or regulation of the steering kinematics.

[0024] In another possible embodiment of the method, it is provided that the control or regulation of the steering kinematics outputs the second wheel steering angle to the second wheel swivel unit.

[0025] Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

[0026] This shows: Fig. 1 schematically a possible embodiment of a steering device, Fig. 2 schematically a possible embodiment of a steering gear and Fig. 3 schematically possible embodiments of two functional blocks of a control or regulation system.

[0027] Corresponding parts are marked with the same reference symbols in all figures.

[0028] Fig. Figure 1 schematically shows a possible embodiment of a steering device 100.

[0029] The steering device 100 comprises a steering wheel 110, a steering column 115, a detection device 120, a control unit 130, a first wheel swivel unit 150, a second wheel swivel unit 160, a first wheel 151 and a second wheel 161.

[0030] The steering device 100 is, for example, designed and configured for steering wheels 151, 161 arranged on a front axle of a vehicle.

[0031] The steering wheel 110 is mechanically coupled to the steering column 115.

[0032] In this embodiment, the detection device 120 is arranged on the steering column 115. The detection device 120 is designed to detect steering inputs made by actuating the steering wheel 110. Furthermore, the detection device 120 is designed to detect a steering wheel angle and / or a steering torque and / or a vehicle speed and / or a yaw rate and / or a lateral acceleration.

[0033] The control unit 130 is data-connected to the detection device 120 and the wheel swivel units 150 and 160. The control unit 130 is configured to control the second wheel swivel unit 160 depending on the detected steering input. Furthermore, the control unit 130 is configured to control a power steering actuator (not shown in detail) so that it can perform a function in Fig. 2. The steering gear 140, shown in more detail, is supplied with auxiliary power. Such a system is also commonly known as power steering. Furthermore, the control unit 130 is designed to variably control or regulate the steering ratio and the steering kinematics.

[0034] The first wheel pivoting unit 150 is mechanically coupled to the first wheel 151 by means of a coupling element 170. The first wheel pivoting unit 150 is designed to pivot the first wheel 151 in response to the steering input. The first wheel pivoting unit 150 includes the steering gear 140 and a steering linkage (not shown in detail). The steering gear 140 is mechanically coupled to the steering column 115 and the steering linkage. In this embodiment, the steering gear 140 is designed as a planetary gear set. In another embodiment (not shown in detail), the steering gear 140 can be non-variable, resulting in a fixed steering ratio.

[0035] The second wheel swivel unit 160 is mechanically coupled to the second wheel 161 by means of a coupling element 170. The second wheel swivel unit 160 is configured to swivel the second wheel 161 depending on the steering input. The second wheel swivel unit 160 is configured as an actuator 162 that is mechanically decoupled from the steering linkage 153. The actuator 162 is configured to swivel the second wheel 161 by means of electrical and / or hydraulic and / or pneumatic energy.

[0036] When a driver (not shown) operates the steering wheel 110, the steering wheel angle is transmitted to the steering gear 140 via the steering column 115. Simultaneously, the detection device 120 determines the steering wheel angle, the steering torque, the current vehicle speed, the yaw rate, and the lateral acceleration and transmits these values ​​to the control unit 130.

[0037] Data transmitted by the acquisition device 120 are used by the control unit 130 as input variables 211 for a [function / process / etc.] in [a specific program / process / etc.]. Fig. 3. Function block 210, shown in more detail, is used for a steering ratio control or regulation system.

[0038] The function block 210 determines as output variables 212 an actual state of the vehicle, a wheel steering angle for the first wheel 151 and a wheel steering angle for the second wheel 161 that depends on the wheel steering angle of the first wheel 151, as well as a value of the auxiliary energy relevant for the steering gear 140, in particular a steering assist.

[0039] The steering ratio on the steering gear 140 can be adjusted by means of the wheel steering angle for the first wheel 151.

[0040] Additionally, auxiliary energy can be transferred to the steering gear 140 by means of the power steering actuator, so that steering input at the steering wheel 110 is supported.

[0041] The current state and the wheel steering angle for the second wheel 161 are used as input variables 221 for a [function / process] in [a specific context]. Fig. 3. Function block 220, shown in more detail, provides a control or regulation of the steering kinematics.

[0042] This function block 220 determines the steering angle for the second wheel 161 as a function of the desired steering kinematics as output variable 222. For example, an Ackermann characteristic of the steering kinematics can be achieved in this way. Here, the inner wheel 151, 161 is turned more sharply than the outer wheel 161, 151, so that a common center point of the curve is created, in order to, for example, reduce tire wear and / or enable more stable cornering.

[0043] Similarly, at high speeds, an anti-Ackermann characteristic can be achieved, in which the outer wheel turns more sharply to stabilize cornering and / or reduce understeer.

[0044] The wheel steering angle for the second wheel 161, determined by function block 220, is transmitted to the second wheel swivel unit 160. The second wheel swivel unit 160 then swivels the second wheel 161.

[0045] Fig. Figure 2 schematically shows a possible embodiment of a steering gear 140.

[0046] The steering gear 140 has a steering spindle 141, a ring gear 142, planet gears 143 and a steering output 144.

[0047] The steering spindle 141 is mechanically coupled to the steering column 115 and the ring gear 142. The steering spindle 141 transmits the steering wheel angle and the steering torque to the ring gear 142.

[0048] The ring gear 142 transmits the steering wheel angle and the steering torque via the planet gears 143 to a sun gear (not shown), which is mechanically coupled to the steering output 144. The steering torque changes depending on the set steering ratio.

[0049] The steering output 144 transmits the steering torque and the steering wheel angle to the steering linkage, thereby turning the first wheel 151.

[0050] Fig. Figure 3 schematically shows a possible embodiment of two functional blocks 210, 220 of a control or regulation system.

[0051] Data transmitted by the detection device 120 is supplied by the control unit 130 as input variables 211 to the function block 210. The input variables 211 include, for example, the steering wheel angle, the steering torque, the current vehicle speed, the yaw rate, and / or the lateral acceleration.

[0052] As already explained, the function block 210 determines from the input variables 211 as output variables 212 an actual state of the vehicle, a wheel steering angle for the first wheel 151 and a wheel steering angle for the second wheel 161 that depends on the wheel steering angle of the first wheel 151 as well as a value of the auxiliary energy relevant for the steering gear 140.

[0053] The output variables 212 relating to the wheel steering angle for the first wheel 151 and the auxiliary energy are supplied to the first wheel swivel unit 150 and the power steering actuator in order to adjust the steering ratio on the steering gear 140 and the auxiliary energy to be transmitted to the steering gear 140.

[0054] The output variables 212 relating to the current state and the wheel steering angle for the second wheel 161 are provided as input variables 221 to the function block 220, which uses these input variables 221 to determine the wheel steering angle for the second wheel 161 as a function of the desired steering kinematics as output variable 222 and transmits it to the second wheel swivel unit 160. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 3 458 336 B1

[0002]

Claims

[1] Steering device (100) for a vehicle, comprising - a steering wheel (110), - a steering column (115) and - a steering linkage which is mechanically coupled to the steering column (115) by means of a steering gear (140), characterized by , that - a first steered wheel (151) of a vehicle axle is mechanically coupled to a first wheel pivoting unit (150), wherein the first wheel pivoting unit (150) comprises the steering linkage and the steering gear (140), - a second steered wheel (161) of the same vehicle axle is mechanically coupled to a second wheel pivoting unit (160), wherein the second wheel pivoting unit (160) is designed as an actuator (162) mechanically decoupled from the steering linkage, - a detection device (120) is provided which is designed to detect a steering input made by means of actuating the steering wheel (110), and - a control unit (130) which is designed to control the second wheel swivel unit (160) depending on the detected steering input. [2] Steering device (100) according to claim 1, characterized by , that the actuator (162) is designed to pivot the second steered wheel (161) by means of electrical and / or hydraulic and / or pneumatic energy. [3] Steering device (100) according to claim 1 or 2, characterized by , that the steering gear (140) is designed as a planetary gear. [4] Steering device (100) according to any one of the preceding claims, characterized by , that the control unit (130) is designed to control a power steering actuator, so that the latter supplies the steering gear (140) with auxiliary energy. [5] Steering device (100) according to any one of the preceding claims, characterized by, that the control unit (130) is designed to control or regulate a steering ratio and a steering kinematics variably. [6] Steering device (100) according to any one of the preceding claims, characterized by , that the detection device (120) is configured to determine a steering wheel angle and / or a steering torque and / or a driving speed and / or a yaw rate and / or a lateral acceleration. [7] Method for operating a steering device (100) according to one of the preceding claims, wherein - the steering input is determined by means of the detection device (120), - depending on the determined steering input - the first wheel swivel unit (150) is controlled by means of the steering gear (140) in such a way that the first steered wheel (151) is swivelled in and - the second wheel swivel unit (160) is controlled by means of the control unit (130) in such a way that the second steered wheel (161) is swivelled in. [8] Method according to claim 7, characterized by , that a value determined by the detection device (120) - a steering wheel angle and / or - a steering torque and / or - a driving speed and / or - a yaw rate and / or - a lateral acceleration is provided as an input variable (211) for controlling or regulating a steering ratio of the first steered wheel (151). [9] Method according to claim 8, characterized by , that the control or regulation of the steering ratio as an output variable (212) - outputs a first wheel steering angle for the first steered wheel (151) to the first wheel swivel unit (150), - outputs a control variable for auxiliary energy to be supplied to the steering gear (140) to a power steering actuator, - transmits a value for the current state of the vehicle as an input variable to a control or regulation system for steering kinematics and - transmits a value for a second wheel steering angle of the second steered wheel (161) as an input variable (221) to the control or regulation of the steering kinematics. [10] Method according to claim 9, characterized by , that the steering kinematics control or regulation outputs the second wheel steering angle to the second wheel swivel unit (160).

Images