Steering system for a commercial vehicle, commercial vehicle having a steering system, and method for operating a steering system

Abstract

Steering system for a commercial vehicle, commercial vehicle having a steering system, and method of operating a steering system The steering system (100) for a commercial vehicle (CV) includes a wheel interface (105), an electro-hydraulic steering gear (110), and a steering control interface (115). The wheel interface (105) is an interface to a steering linkage with at least one wheel (120) of the utility vehicle (CV), and the wheel interface (105) is connected or connectable to the steering linkage and / or the wheel (120). The electro-hydraulic steering gear (110) is configured to transmit hydraulic power to the wheel interface (105) for steering the wheel (120). The steering control interface (115) is an interface to a steering control device of the commercial vehicle (CV), and the steering control interface (115) is electrically or electronically connected or connectable to the steering control device to adjust the actuation force for the hydraulic power transmission using the electro-hydraulic steering gear (110).

Description

[Technical Field]

[0001] The present invention relates to a steering system for a commercial vehicle, to a commercial vehicle having a steering system, and to a method for operating a steering system.

[0002] Today, two main technologies are used for power transmission in power steering systems: electromechanical and electrohydraulic. WO 2022175120 discloses an electrohydraulic power steering system for a vehicle, comprising a hydraulic pump, a drive unit, a first working line, a second working line, and a heat transfer unit.

[0003] With this in mind, the object of the present approach is to provide an improved steering system for a commercial vehicle, an improved commercial vehicle having a steering system, and an improved method for operating a steering system.

[0004] This problem is solved by a steering system for a commercial vehicle, a commercial vehicle with a steering system and a method for operating a steering system with the features of the independent claims.

[0005] An advantage achievable with the presented approach is that an electrohydraulic steering system is created for commercial vehicles that does not require a mechanical coupling of the steering control to the steering wheels.

[0006] The steering system for a commercial vehicle includes a wheel interface, an electro-hydraulic steering gear, and a steering control interface. The wheel interface is an interface to a steering linkage with at least one wheel of the utility vehicle, and the wheel interface is connected or connectable to the steering linkage and / or the wheel. The electro-hydraulic steering gear is configured to provide hydraulic power transmission to the wheel interface for steering the wheel. The steering control interface is an interface to a steering control device of the utility vehicle, and the steering control interface is electrically or electronically connected or connectable to the steering control device to adjust the actuation force for the hydraulic power transmission using the electro-hydraulic steering gear.

[0007] The utility vehicle may be configured as a large utility vehicle, for example, a utility vehicle weighing more than 3.5 tons or more than 7.5 tons, for example, up to 38 tons. The wheel interface may be mechanically connected or connectable to the steering linkage and / or the wheels. The steering control interface may include, for example, a steering wheel operable by a driver of a commercial vehicle. The steering control interface may be connected or connectable to a steering control device in a signal-transmitting manner and / or non-mechanically, for example, without a mechanical steering column. For example, in the case of signal transmission, the steering control interface may be connected to the steering control device only via a signal-transmitting line or wirelessly.

[0008] The steering system can be configured as a steer-by-wire system. In such a steer-by-wire system, the mechanical connection between the steering wheel of the steering control device and the steered wheels is eliminated. In other words, there is no mechanical steering column. Sensors monitor the steering movement and the input is transmitted electrically or electronically to the steering gear. Advantageously, therefore, the mechanical steering column can be completely omitted.

[0009] According to one embodiment, the steering gear may include a hydraulic piston designed to exert an actuation force for power transmission. For example, the hydraulic piston may be designed to exert an actuation force for power transmission from a pressure difference across the hydraulic piston. Such a piston is suitable for performing hydraulic power transmission.

[0010] The steering gear may further include a hydraulic pump configured to act on the hydraulic piston to operate the hydraulic piston. For example, the hydraulic pump may be configured to act on two sides of the hydraulic piston to move the hydraulic piston by creating a pressure differential on both sides of the hydraulic piston to operate the hydraulic piston. Such a hydraulic pump is adapted to apply a hydraulic force to the hydraulic piston to cause the hydraulic force to be transmitted.

[0011] According to one embodiment, it is further advantageous if the steering gear comprises an electric motor adapted to drive directly or indirectly a hydraulic pump, such electric motor being able to ensure the operation of the hydraulic pump.

[0012] The hydraulic pump may be configured as, for example, a positive displacement pump, which may be any positive displacement pump, for example, including, for example, an external and internal gearing and / or a scroll pump and / or a gear pump with a rotating screw.

[0013] According to one embodiment, the steering gear may include a pitman arm connected between the hydraulic piston and the wheel interface. The pitman arm, sometimes referred to as a "gearbox with a pitman arm," may be configured to provide a mechanical connection to the steering linkage and / or the wheels.

[0014] The steering system may further include a steering control device electrically or electronically connected or connectable to the steering control interface, the steering control device configured to output steering commands to the steering control interface for adjusting actuation force for the hydraulic power transmission. The steering control device may further include a steering wheel operable by a vehicle driver to generate steering commands.

[0015] It is further advantageous if the steering gear according to an embodiment comprises a control unit which electronically connects the steering control device and the steering gear, by means of which control of the steering commands issued by the steering control device to the steering gear can be implemented.

[0016] The steering system may further comprise a power supply adapted to supply power to the steering gear, the steering control device and / or the control unit, such a power supply may ensure operation of the steering gear, the steering control device and / or the control unit.

[0017] According to one embodiment, the steering gear may include a recirculating ball system configured to generate a force against the hydraulic piston. For example, the recirculating ball system may be configured and shaped to generate an additional force against the hydraulic piston. To this end, the recirculating ball system may include, for example, a recirculating ball screw mechanism with a worm gear. In an exemplary embodiment, the recirculating ball system may include a screw located in a block having a threaded connection. The block may further be connected to a gear that moves a pitman arm. A spindle may be rotatable in a fixed position to move the block, which may then transmit its movement to the wheels via the pitman arm. A ball bearing may be located within the block that rotates and returns through the gearbox. This rolling connection reduces friction and backlash in the steering gear.

[0018] The steering system may further include an electric motor configured to directly or indirectly drive the spindle of the recirculating ball system. The electric motor may be an electric motor for operating a hydraulic pump or an additional electric motor. Such an electric motor may ensure the movement of the spindle.

[0019] The commercial vehicle has a steering system in one of the variants described above. Thanks to the electro-hydraulic steering system, such a commercial vehicle is designed to implement a hydraulic power transmission to the steering wheels, advantageously without a mechanical connection of the steering control device to the steering wheels.

[0020] A method for operating a steering system in one of the variations described above includes receiving and actuating steps, wherein the receiving step electrically or electronically receives a steering command via a steering control interface, the steering command configured to set an actuation force for the hydraulic transmission, and the actuating step actuates the electro-hydraulic steering gear using the steering command to transmit hydraulic power to at least the wheel interfaces to the wheels to steer the wheels.

[0021] The method may be implemented, for example, in software or hardware or in a mixed form of software and hardware, for example in a control unit.

[0022] The techniques presented herein further create apparatuses configured to perform, control, or realize the steps of the method variations presented herein in the corresponding apparatus, and this embodiment variation of the techniques in the form of an apparatus may quickly and efficiently solve the problem underlying the techniques.

[0023] For this purpose, the device may have at least one computing unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface to a sensor or actuator for reading a sensor signal from the sensor or outputting a data or control signal to the actuator, and / or at least one communication interface for reading or outputting data embedded in a communication protocol. The computing unit may be, for example, a signal processor, a microcontroller, etc., and the memory unit may be a flash memory or a magnetic memory unit. The communication interface may be configured to read or output data wirelessly and / or wired, and a communication interface capable of reading or outputting wired data may, for example, read or output such data electrically or optically from or to a corresponding data transmission line.

[0024] In this context, a device can be understood as an electrical device that processes a sensor signal and outputs a control signal and / or a data signal as a function thereof. The device can have an interface that can be designed in terms of hardware and / or software. In the case of a hardware-based design, the interface can be, for example, part of a so-called system ASIC that includes various functions of the device. However, the interface can also be a specific integrated circuit or at least partially composed of separate components. In a software-based design, the interface can be, for example, a software module that resides on a microcontroller together with other software modules.

[0025] Advantageously, there is also a computer program product or computer program comprising a program code which may be stored on a machine-readable carrier or storage medium, such as a semiconductor memory, a hard disk memory or an optical memory, and which program code is used in particular to perform, realize and / or control the steps of the method according to any of the embodiments described above, when the program product or program is run on a computer or device.

[0026] Embodiments of the techniques presented herein are explained in more detail in the following description with reference to the drawings. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a schematic diagram of a commercial vehicle having a steering system according to an example embodiment. [Figure 2] FIG. 1 is a schematic diagram of a steering system, according to an example embodiment. [Figure 3] FIG. 1 is a schematic side view of a recirculating ball system for a steering system, according to an example embodiment. [Figure 4] FIG. 1 is a flow diagram of a method for operating a steering system according to an example embodiment.

[0028] In the following description of preferred embodiments of the present approach, the same or similar reference numerals are used for elements that appear in the various figures and have similar effect, and repeated descriptions of these elements will be omitted.

[0029] FIG. 1 shows a schematic diagram of a commercial vehicle CV having a steering system 100 according to an example embodiment.

[0030] By way of example only, the steering system 100 according to this example embodiment is housed on or in a commercial vehicle CV, which here is formed, by way of example, as a heavy commercial vehicle, for example having a weight of more than 3.5 tonnes or more than 7.5 tonnes, for example up to 38 tonnes.

[0031] The steering system 100 includes a wheel interface 105, an electro-hydraulic steering gear 110, and a steering control interface 115. The wheel interface 105 interfaces a steering linkage with at least one wheel 120 of the commercial vehicle, and the wheel interface 105 is connected or connectable to the steering linkage and / or the wheel 120. The electro-hydraulic steering gear 110 is configured to provide hydraulic power transmission to the wheel interface 105 for steering the wheel 120. The steering control interface 115 is an interface to a steering control device of the commercial vehicle, and the steering control interface 115 is electrically or electronically connected or connectable to the steering control device to adjust the actuation force for the hydraulic power transmission using the electro-hydraulic steering gear 110.

[0032] According to this embodiment, the wheel interface 105 is mechanically connected or connectable to the steering linkage and / or the wheels 120. According to this example embodiment, the steering control device (see FIG. 2) comprises a steering wheel that can be operated by the driver of the commercial vehicle CV. According to this example embodiment, the steering control interface 115 is connected or connectable to the steering control device in a signal-transmitting manner and / or non-mechanically, for example without a mechanical steering column. In the case of signal transmission, the steering control interface 115 is connected to the steering control device only via a signal-transmitting line or wirelessly, according to one example embodiment.

[0033] According to this example embodiment, the steering system 100 is formed as a steer-by-wire system. In a steer-by-wire system, the mechanical connection between the steering wheel of the steering control device and the steered wheels 120 is removed. In other words, there is no mechanical steering column. A sensor, according to an example embodiment, monitors the steering movement of the steering wheel of the steering control device, and the input / steering command is, according to this example embodiment, electrically or electronically transmitted to the steering gear 110 via a steering control interface 115 (see also FIG. 2 ).

[0034] According to this example embodiment, the steering gear 110 includes a hydraulic piston 125 configured to exert an actuation force for power transmission. For example, according to this example embodiment, the hydraulic piston 125 is configured to exert an actuation force for power transmission from a pressure difference on two sides of the hydraulic piston 125. According to this example embodiment, the steering gear 110 further includes a hydraulic pump 130 configured to act on the hydraulic piston 125 to operate the hydraulic piston 125. Here, for example, the hydraulic pump 130 is configured to act on the two sides of the hydraulic piston 125 to move the hydraulic piston 125 by generating a pressure difference on both sides of the hydraulic piston 125 to operate the hydraulic piston 125. For example, the hydraulic pump 130 is configured as a positive displacement pump. The positive displacement pump may be any positive displacement pump and, according to one embodiment, may include, for example, an external and internal transmission and / or a scroll pump and / or a gear pump having a rotary screw. According to this example embodiment, the steering gear 110 further comprises an electric motor 135 configured to directly or indirectly drive the hydraulic pump 130 .

[0035] According to this embodiment, the steering gear 110 further comprises a pitman arm 140 connected between the hydraulic piston 125 and the wheel interface 105. According to one embodiment, the steering linkage lever 140 is configured to provide a mechanical connection to the steering linkage and / or the wheel 120.

[0036] In summary, in the electro-hydraulic steering system 100 disclosed herein, power transmission in the steering gear 110 between the electric actuator / motor 135 and the steering wheels 120 is via a hydraulic transmission, among other possible mechanisms. In the steering system 100 according to this example embodiment, the electric motor 135 drives the hydraulic pump 130, which, according to this example embodiment, acts on two sides of the hydraulic piston 125 by creating a pressure difference. This system in the steering gear 110 converts an electric signal into a hydraulic signal, which is then converted into a mechanical signal through the hydraulic piston 125. In other words, according to this embodiment, FIG. 1 shows that the electric motor 135 drives the hydraulic pump 130, which, according to this example embodiment, acts on two sides of the hydraulic piston 125 by creating a pressure difference. According to different example embodiments, the hydraulic pump 130 is formed as an external and internal gear pump, i.e., a worm pump and / or a rotary pump, and is driven by the electric motor 135.

[0037] 2 shows a schematic diagram of a steering system 100 according to an example embodiment, which may be the steering system 100 described based on FIG. 1, with the difference that the steering system 100 according to this example embodiment comprises a steering control device 200, a control unit 205, a power supply 210, and / or a steering linkage 215 with the wheels 120.

[0038] The steering control device 200 is electrically or electronically connected or connectable to the steering control interface 115, and the steering control device 200 is configured to output a steering command to the steering control interface 115 to adjust the actuation force for the hydraulic power transmission. According to this embodiment, the steering command is transmitted to the steering control interface 115 via a control line 220. According to this example embodiment, the steering gear 110 further includes a control unit 205 that electrically or electronically connects the steering control device 200 and the steering gear 110. According to this example embodiment, the control unit 205 is connected to the steering control device 200 via a control line 220 and to the steering control interface 115 via another control line 220. The power supply 210 is configured to supply power to the steering gear 110, the steering control device 200, and / or the control unit 205. According to this embodiment, the power supply 210 is connected to each of the steering gear 110, the steering control device 200, and the control unit 205 via a plurality of power lines 225.

[0039] The steering system 100 disclosed herein may also be referred to as a "steer-by-wire system with hydrostatic transmission for road vehicles."

[0040] Currently, two main technologies are used for power transmission in power steering systems: electromechanical and electrohydraulic. Electrohydraulic is considered the better option. Especially in commercial vehicles, where the actuation forces are quite high, a more advantageous configuration can be achieved with a hydrostatic transmission.

[0041] The most commonly used mechanism in commercial vehicle steering systems today is a ball screw, and the linkage used to rotate the wheels 120 is different from the linkage used in the rack and pinion systems commonly used in passenger cars.

[0042] In known steering systems, there is a mechanical linkage between the steering wheels and the steering wheel within the vehicle that implements the driver's steering intent. However, as technology advances, in the context of the approach presented herein, this mechanical link will be eliminated to provide greater functionality and flexibility.

[0043] With the advent of autonomous capabilities, vehicles are increasingly taking over critical driving functions from the driver. These vehicle systems require higher levels of safety and therefore multiple redundancies. Fail-safe systems that incorporate these redundancies facilitate steer-by-wire systems.

[0044] For example, unlike known steering systems that use rack and pinion steering gear and / or have electro-hydraulic systems with mechanical connections, the steering system 100 presented herein features an electro-hydraulic steering gear 110 without a mechanical connection.

[0045] The steering gear 110 is applicable to heavy vehicles without a mechanical connection to the driver and includes hydraulic power transmission elements.

[0046] Therefore, in a steer-by-wire system implemented according to this embodiment, the mechanical connection between the steering wheel of the steering control device 200 and the steered wheels 120 is eliminated. In other words, the mechanical steering column is removed. According to one embodiment, sensors monitor the steering movement and inputs / steering commands are transmitted electronically to the steering gear 110. According to one embodiment, an electronically generated steering feel is fed back to the driver.

[0047] In summary, the steering system 100 presented herein in the form of a steer-by-wire system includes, among other possible types, at least one hydrostatic transmission between an electric motor 135, sometimes called a "servo motor," and the steering wheels 120 (see FIG. 3). According to an example embodiment, the steering system 100 comprises the following components: - Steering control device 200 in the form of a steering control subsystem with optional force feedback - according to one example embodiment, a control system operated by the driver. According to one example embodiment, sensors are used to monitor steering movements. The force feedback, according to one example embodiment, conveys steering feel to the driver, a control unit 205 in the form of a control unit - the control unit 205 controls the entire steering system 100 and transmits signals between the steering control unit 200 and the steering gear 110; -Power 210, a steering gear 110 including a hydrostatic transmission; Optionally, according to one embodiment, a recirculating ball system with a recirculating ball steering gear is possible (see FIG. 3). The steering system 100, sometimes referred to as a "steering system", generates an actuation force on the steering wheels 120 based on a steering input, and / or - A "steering wheel" subsystem including a steering linkage 215 with the steering wheel 120.

[0048] Overall, there is only an electronic connection between the steering subsystem and the steering wheel 120 subsystem, and no mechanical connection.

[0049] FIG. 2 shows the main components of a steering system 100 in the form of a steer-by-wire system, highlighting the lack of a direct mechanical connection between the steering control device 200 subsystem and the steered wheels 120 subsystem.

[0050] 3 shows a schematic side view of a recirculating ball system 300 of steering system 100, according to an example embodiment, which may be an example embodiment of steering system 100 described with reference to FIG.

[0051] According to this example embodiment, the steering gear 110 includes a recirculating ball system 300 configured to generate a force against a hydraulic piston. According to this embodiment, the recirculating ball system 300 is configured and configured to generate an additional force against the hydraulic piston. To this end, according to this embodiment, the recirculating ball system 300 includes a recirculating ball screw mechanism, for example, with a worm gear. In the exemplary embodiment shown herein, the recirculating ball system 300 includes a screw 301 located in a block 302 having a threaded connection. According to this example embodiment, the block 302 is further connected to a gear 303 that moves a pitman arm 304. According to this example embodiment, the spindle 301 is rotatable in a fixed position, moving the block 302, which in turn is transmitted to the wheels of the utility vehicle via the pitman arm 304. According to one embodiment, the block 302 includes ball bearings that return through a gearbox as it rotates. This rolling connection reduces friction and backlash in the steering gear.

[0052] In other words, according to this example embodiment, the recirculating ball system 300 acts on the wheels 120 in addition to hydraulic pressure. In heavy vehicles, as opposed to passenger cars where a rack and pinion is used, such a recirculating ball system 300, sometimes referred to as a "recirculating ball steering system" or "recirculating ball steering gear," is applicable.

[0053] According to one embodiment, the steering system further comprises an electric motor configured to directly or indirectly drive the spindle 301, sometimes referred to as the "recirculating ball screw," of the recirculating ball steering system 300. According to one embodiment, the electric motor is the same electric motor for driving the hydraulic pump, or according to another embodiment, an additional electric motor.

[0054] 4 shows a flow diagram of a method 400 according to an example embodiment for operating a steering system, which may be the steering system 100 described with reference to FIGS.

[0055] The method 400 includes a receiving step 405 and an actuating step 410. In the receiving step 405, a steering command is received electrically or electronically via a steering control interface, the steering command configured to set an actuation force for a hydraulic transmission. In the actuating step 410, the steering command is used to actuate an electro-hydraulic steering gear to transmit hydraulic power to at least the wheel interfaces to the wheels to steer the wheels.

[0056] Method steps presented herein may be repeated and performed in a different order than described.

[0057] Where an embodiment includes an "and / or" connection between a first feature and a second feature, this should be read to mean that the embodiment includes both the first feature and the second feature in some embodiments, and either only the first feature or only the second feature in other embodiments. [Explanation of symbols]

[0058] commercial vehicle 100 Steering System 105 Wheel Interface 110 Electro-hydraulic steering gear 115 Steering Control Interface 120 wheels 125 hydraulic piston 130 Hydraulic pump 135 Electric Motor 140 Steering column lever 200 Steering Control Unit 205 Control Unit 210 Power Supply Unit 215 Steering linkage 220 Control Line 225 Power Line 300 Recirculating Ball System 301 Spindle 302 Block 303 Gears 304 Pitman Arm How to operate the 400 steering system 405 Receiving Step 410 Driving Steps

Claims

1. A steering system (100) for a commercial vehicle (CV), the steering system (100) comprising: a wheel interface (105) to a steering linkage (215) with at least one wheel (120) of said commercial vehicle (CV), said wheel interface (105) being connected or connectable to said steering linkage (215) and / or said wheel (120); - at least one electrohydraulic steering gear (110) configured to provide hydraulic power transmission to said wheel interfaces (105) for steering said wheels (120); a steering control interface (115) to a steering control device (200) of the utility vehicle, the steering control interface (115) being electrically or electronically connected or connectable to the steering control device (200) for adjusting the actuation force for the hydraulic power transmission using the at least one electro-hydraulic steering gear (110); A steering system (100) comprising:

2. The steering system (100) according to claim 1, characterized in that the steering system (100) is formed as a steer-by-wire system.

3. 3. The steering system (100) according to claim 1 or 2, characterized in that the at least one steering gear (110) comprises a hydraulic piston (125) adapted to exert the actuation force for the power transmission.

4. 4. The steering system (100) according to claim 3, characterized in that the at least one steering gear (110) comprises a hydraulic pump (130) adapted to act on the hydraulic piston (125) to move the hydraulic piston (125).

5. 5. The steering system (100) according to claim 4, characterized in that the at least one steering gear (110) comprises an electric motor (135) adapted to directly or indirectly drive the hydraulic pump (130).

6. Steering system (100) according to claim 4 or 5, characterized in that the hydraulic pump (130) is formed as a positive displacement pump.

7. 7. The steering system (100) according to claim 1, wherein the steering control device (200) is electrically or electronically connected or connectable to the steering control interface (115), and the steering control device (200) is adapted to output a steering command to the steering control interface (115) for adjusting the actuation force for the hydraulic power transmission.

8. 8. The steering system (100) according to claim 7, characterized by a control unit (205) electronically interconnecting said steering control device (200) and said at least one steering gear (110).

9. 9. The steering system (100) according to claim 7 or 8, characterized by a power supply device (210) adapted to supply power to the at least one steering gear (110), the steering control device (200), and / or the control unit (205).

10. 10. The steering system (100) according to any one of claims 3 to 9, characterized in that the at least one steering gear (110) comprises a recirculating ball system (300) configured to generate a force against the hydraulic piston (125).

11. A commercial vehicle (CV) comprising a steering system (100) according to any one of claims 1 to 10.

12. A method (400) for operating a steering system (100) according to any one of claims 1 to 10, said method (400) comprising: - receiving (405) a steering command electrically or electronically via said steering control interface (115), said steering command being configured to adjust the actuation force for said hydraulic power transmission; - driving (410) said at least one electrohydraulic steering gear (110) using said steering command to transmit said hydraulic power to said wheel interface (105) to at least one wheel (120) for steering said wheel (120); The method (400) includes:

13. Apparatus adapted to perform and / or control the steps of the method (400) according to claim 12 in each unit.

14. A computer program configured to perform and / or control the method (400) according to claim 12.

15. A machine-readable storage medium having the computer program of claim 14 stored thereon.

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