Steering systems for vehicles, especially commercial vehicles

Abstract

The present invention relates to a steering system (10) for a vehicle, particularly a commercial vehicle, comprising at least one first steering gearbox (12) for steering at least one first wheel (16) and at least one first steering mechanism (14) connected to the first steering gearbox (12), at least one second steering gearbox (18) for steering at least one second wheel (22) and at least one second steering mechanism (20) connected to the second steering gearbox (18), and at least one tensioning mechanism (26), which is connected to the first steering gearbox (12) and the second steering gearbox (18), thereby allowing the first steering gearbox (12) and the second steering gearbox (18) to be preloaded in opposite directions relative to each other, particularly when the vehicle is stationary.

Description

Technical Field

[0001] The present invention relates to a steering system for a vehicle, particularly for a commercial vehicle, comprising at least one first steering gearbox for steering at least one first wheel and at least one first steering mechanism connected to the first steering gearbox, at least one second steering gearbox for steering at least one second wheel and at least one second steering mechanism connected to the second steering gearbox, and at least one tensioning mechanism.

[0002] In the future, further increasing functional requirements will be imposed on steering systems for vehicles, particularly for commercial vehicles. This is because the steering system plays a central role in the (partial) automation process of the vehicle.

[0003] In this case, it is particularly important that the steering system functions accurately and reliably, takes into account the increasing functional requirements, and can still be further optimized with respect to the installation space requirements.

[0004] Steering systems for vehicles are already well-known from the prior art.

[0005] For example, the vehicle steering device shown in German Patent Application Publication No. 10114600 (DE112012806263T5) has a steering operating device operable by a driver, particularly a steering handwheel, and each one electric-mechanical actuator for controlling each one of the steerable wheels of a pair of wheels of a steerable axle located on the left and right of the vehicle body, and means for ensuring the control of both wheels of this axle each time by the other actuator that is still functioning normally when a failure or abnormality occurs in one of the two actuators arranged corresponding to the steerable axle.

[0006] Furthermore, the vehicle steering system disclosed in German Patent Application Publication No. 112012806263 includes a steering system configured to rotate the steering wheels in accordance with the operation of the vehicle steering wheel, in which case the steering system includes a first motor and a second motor for steering, having commonly set electrical characteristics, a first current sensor configured to detect a first current value of the current flowing through the first motor, a second current sensor configured to detect a second current value of the current flowing through the second motor, and an abnormality diagnosis unit.

[0007] Conventional steering systems remain complex, consisting of numerous components, making them expensive, requiring a large installation space, and being heavy.

[0008] Therefore, the object of the present invention is to advantageously improve the steering system of the type described at the beginning, in particular, to provide a steering system that is redundantly formed, has a lower weight, can be manufactured at low cost, and executes precise steering commands to the wheels.

[0009] This problem is solved by a steering system having the features described in claim 1, based on the present invention. According to this invention, a steering system for a vehicle, particularly for a commercial vehicle, comprising: at least one first steering gearbox and at least one first steering mechanism connected to the first steering gearbox for steering at least one first wheel; at least one second steering gearbox and at least one second steering mechanism connected to the second steering gearbox for steering at least one second wheel; and at least one tension mechanism, wherein the tension mechanism is connected to the first steering gearbox and the second steering gearbox, thereby allowing preloads to be applied to the first steering gearbox and the second steering gearbox in opposite directions relative to each other, particularly when the vehicle is stopped.

[0010] This invention is based on the fundamental idea that the steering system has two independent steering gearboxes, thereby forming a redundant steering system. Furthermore, the first steering gearbox and the second steering gearbox are connected to each other via a tension mechanism that applies a preload to both steering gearboxes. Applying this preload has the advantage or background of eliminating or adjusting the steering play in both steering gearboxes and, consequently, in the connected first and second steering mechanisms. This allows the steering system to operate more precisely, thereby improving the driving reliability of the steering system and the vehicle or commercial vehicle. In normal driving, the tension mechanism is used only to apply a preload to both steering gearboxes and is not used to transmit steering motion from the first steering gearbox to the second steering gearbox or from the second steering gearbox to the first steering gearbox. In particular, in this case, a preload can be applied to the first steering gearbox and the second steering gearbox in opposite directions relative to each other when stationary. If the first and / or second steering gearbox fails, the tension mechanism, in addition to its function as a play adjustment member, is used as a linkage to transmit the steering action of the still-functioning first or second steering gearbox to the first or second steering mechanism, thereby ensuring continued and reliable steering of both wheels.

[0011] In other respects, it may be assumed that the tension mechanism is rotatably mounted to the first steering mechanism and the second steering mechanism. In this invention, the first and second steering mechanisms are formed as link devices comprising one or more couplings, connecting each tie rod to the first and second steering gearboxes. This allows the tension mechanism to be coupled or connected to the first and second steering mechanisms very easily. Thus, expensive and time-consuming steering components such as racks can be eliminated, thereby enabling the provision of an inexpensive steering system. However, the tension mechanism is the only mechanical coupling or connecting member between the first steering mechanism and the second steering mechanism. This is because, under normal operation, the first and second steering mechanisms are driven independently of each other by the first or second steering gearbox.

[0012] Furthermore, the tension mechanism may be capable of and / or already being preloaded elastically in its installed state. This form of elastic and mechanical preloading provides a structurally very simple and reliable means of applying opposing preloads to both the steering mechanism and the steering gearbox, because there is no need to provide any additional components to ensure the preload is applied. Moreover, this configuration is extremely inexpensive and lightweight. In this case, the tension mechanism may be formed as a tension rod, tension bar, tension spoke, tension pipe, tension beam, or tension vise that is capable of and / or already preloaded elastically.

[0013] Furthermore, it is conceivable that the tension mechanism has at least one length adjustment mechanism and / or telescopic mechanism. This allows for particularly precise adjustment of the preload. This is advantageous in particular because an extremely large preload can create a mechanical load on both the steering mechanism and the steering gearbox, and shorten the lifespan of both the steering mechanism and the steering gearbox. However, an extremely small preload is equally undesirable, as this may negate virtually all of the play-eliminating effect of the steering system. In this respect, precise adjustment of the preload by the tension mechanism is extremely important in the sense of a reliably functioning steering system according to the present invention.

[0014] Furthermore, it is possible that the tension mechanism has at least one elastic spring member. The spring member allows for specific adjustment of important parameters of the tension mechanism, such as preload force, cushioning characteristics, preload distance, preload direction, and preload elasticity, for each steering system. By selecting a suitable elastic spring member, a good compromise between excessive and insufficient preload can be achieved. Elastic spring members are particularly advantageous in combination with length adjustment mechanisms and / or telescopic mechanisms, because this allows for more precise adjustment of the aforementioned parameters.

[0015] Furthermore, it may be assumed that the elastic spring member is formed as an axial spring member. By providing an axial spring member, the above-mentioned parameters can be adjusted very easily. This is because, in one embodiment of the present invention, the tension mechanism may be formed as a rigid bar-shaped, beam-shaped, or rod-shaped member (i.e., the length of the tension mechanism is significantly longer than the height and width). In other words, the tension mechanism exerts its function or effect of applying preload, as described above, substantially in the axial direction in combination with the axial spring member.

[0016] Similarly, it is conceivable that elastic spring members are formed as radial spring members, particularly leaf spring members. Radial spring members allow for the preloading of tension mechanisms to be implemented structurally very simply, with reduced weight and using a very small number of components. For example, leaf spring members are extremely simple, yet extremely reliable and complete mechanical components with clearly defined elastic properties. In short, radial spring members are extremely effective and reliable components for forming tension mechanisms, because in some cases, only one component is needed to construct a radial spring member.

[0017] Furthermore, it is conceivable that the second steering gearbox is structurally smaller than the first steering gearbox in at least one dimension. The second steering gearbox, also known as the "power pack," is not mechanically coupled to the vehicle's steering wheel and steering column, and is therefore controlled only via a control device and / or adjustment device. Thus, the second steering gearbox may omit some components for mechanical coupling to the steering column, thereby being smaller overall than the first steering gearbox. As a result, a particularly lightweight, compact, and efficient steering system is provided, which, despite having two steering gearboxes, is weight-neutral or even lighter than the well-known electric steering systems that are mainly mounted in a single steering gearbox in commercial vehicle manufacturing.

[0018] Furthermore, the second steering gearbox can be structurally formed to be at least 10% smaller, preferably at least 20% smaller, and particularly preferably at least 25% smaller than the first steering gearbox in at least one dimension. This saving of configuration space allows other components in the vehicle to be designed more flexibly and / or larger. This is because the functional density in vehicles, especially commercial vehicles, continues to increase in light of the background of autonomous driving, in which case the required configuration space remains substantially constant. In this respect, the space-saving configuration of the steering system, which is aimed at by reducing the second steering gearbox in this way, is particularly important.

[0019] Additionally, it may be assumed that the first steering gearbox is coupled to at least one first electric motor, and the second steering gearbox is coupled to at least one second electric motor. This coupling is particularly advantageous because, in addition to purely electromechanical steering assist, the first and second electric motors enable steering system assist functions, such as lane keeping assist, (partial) autonomous steering, collision assist, and / or wind compensation assist, via the first and second steering gearboxes. In this case, the two electric motors may be connected (e.g., via a CAN bus, LIN bus, and / or Ethernet) to one of the vehicle or steering system, particularly a central control and / or regulating device, which simultaneously processes signals provided by sensors required by the assist system and controls the two electric motors accordingly. This provides a particularly efficient, fast, and dynamic steering system.

[0020] Furthermore, it is conceivable that the second steering gearbox can only be driven via a second electric motor. Moreover, the second electric motor can be controlled independently of the first electric motor by the steering system's control and / or adjustment device. This is particularly advantageous as it eliminates the need for additional configuration space and additional hydraulic steering assist means, including costly components such as pumps, valves, actuators, and conduits. Furthermore, it simplifies the control or adjustment of the steering system, as only the first and second electric motors need to be controlled, thereby eliminating the need for additional and expensive control or adjustment of the steering hydraulic system.

[0021] Similarly, the first steering gearbox may also have at least one mechanical direct drive unit that can connect the first steering gearbox to at least one steering column and the vehicle's steering wheel. This provides an additional level of safety to the steering system, because even in the worst-case scenario, i.e., if the first and second electric motors fail, the vehicle can still be safely controlled mechanically by the driver via the vehicle's steering wheel through the steering system. In this case, the tension mechanism is additionally used as a linkage that simultaneously transmits the steering action of the first steering gearbox or steering mechanism to the second steering gearbox or second steering mechanism, so that both wheels on a single axle can still be steered as prescribed. The axle may be the front axle of a vehicle or commercial vehicle, but additionally or alternatively, it may also be the rear axle. Thus, the safety of the vehicle is enhanced by the mechanical direct drive unit, and a situation in which the vehicle becomes unsteerable can be avoided.

[0022] Further details and advantages of the present invention will be described in more detail based on one embodiment shown in only the drawings. [Brief explanation of the drawing]

[0023] [Figure 1] In the sole FIGURE 1, there is shown a schematic perspective view of one embodiment of a steering system according to the present invention.

[0024] That is, in FIGURE 1, there is shown a steering system 10 according to the present invention for a vehicle (not shown in FIGURE 1).

[0025] The vehicle is formed as a commercial vehicle.

[0026] The steering system 10 has a first steering gearbox 12 for steering at least one first wheel 16 and a first steering mechanism 14.

[0027] Furthermore, the first steering gearbox 12 is connected to the first steering mechanism 14.

[0028] The first steering mechanism 14 has a first steering rod 14a and a second steering rod 14b, and the first steering rod 14a and the second steering rod 14b are coupled to each other via a swivel joint.

[0029] Furthermore, the second steering rod 14b is connected to a tie rod 14c via another swivel joint, and the tie rod 14c is also mounted on a wheel carrier 14d that attaches to and supports the first wheel 16.

[0030] The first steering rod 14a is also connected non-rotatably relative to the output shaft of the first steering gearbox 12.

[0031] Thus, the rotation of the output shaft of the first steering gearbox 12 is transmitted to the first steering mechanism 14, whereby the tie rod 14c of the first steering mechanism 14 is swiveled, and as a result, the steering operation or rotation of the first wheel 16 is caused.

[0032] Furthermore, the steering system includes a second steering gearbox 18 for steering the second wheel 22 and a second steering mechanism 20.

[0033] In Figure 1, the second steering gearbox 18 is connected to the second steering mechanism 20.

[0034] The second steering mechanism 20 has another first steering rod 20a and another second steering rod 20b, the other first steering rod 20a and the other second steering rod 20b are connected to each other via a swivel joint.

[0035] Furthermore, the second steering rod 20b is connected to another tie rod 20c via another swivel joint, and the other tie rod 20c is also mounted to a wheel carrier 20d that mounts and supports the second wheel 22.

[0036] Another first steering rod 20a is connected to the output shaft of the second steering gearbox 18 in a manner that prevents relative rotation.

[0037] Therefore, the rotation of the output shaft of the second steering gearbox 18 is transmitted to the second steering mechanism 20, causing the tie rod 20c to rotate, and as a result, steering action or rotation of the second wheel 22 is produced.

[0038] The first and second steering gearboxes 12 and 18 are each attached to the vehicle frame support (for example, via a number of screw fasteners), in which case the output shafts of the two steering gearboxes 12 and 18 each extend through the vehicle frame support and are each connected to the first steering rods 14a and 20a in a manner that prevents relative rotation.

[0039] The first and second wheels 16, 22 or the steering system 10 are arranged in this embodiment to correspond to the front axle 24 of the commercial vehicle.

[0040] Alternatively or additionally, the first and second wheels 16, 22 or the steering system 10 may be positioned corresponding to the rear axle of the commercial vehicle.

[0041] Furthermore, the steering system includes a tension mechanism 26 connected to the first steering gearbox 12 and the second steering gearbox 18.

[0042] In Figure 1, the tension mechanism may be formed as a tension rod, tension bar, tension spoke, tension pipe, tension beam, or tension vise that can be elastically preloaded and / or preloaded.

[0043] The aforementioned connection is made such that a preload can be applied to the first steering gearbox 12 and the second steering gearbox 18 relative to each other.

[0044] In particular, it may be assumed that preloads can be applied to the first steering gearbox 12 and the second steering gearbox 18 in opposite directions relative to each other when the vehicle is stopped.

[0045] Therefore, the tension mechanism 26 may be able to be elastically preloaded or may already have a preload applied to it in its installed state.

[0046] Furthermore, the tension mechanism 26 is rotatably attached to the first steering mechanism 14 and the second steering mechanism 20.

[0047] The pivot connection is made in Figure 1 at the rotatable joint between each of the second steering rods 14b, 20b and each of the tie rods 14c, 20c.

[0048] Applying a preload in the opposite direction means that the tension mechanism 26 elastically pushes the first steering mechanism 14 and the second steering mechanism 20 apart at the rotational joint between the second steering rods 14b, 20b and the tie rods 14c, 20c, to the extent that the steering play of the steering system 10 is offset, adjusted, or eliminated.

[0049] In this case, the distance between both tie rods 14c, 20c and both second steering rods 14b, 20b, particularly at the rotational joints, is increased, thereby eliminating steering play.

[0050] Furthermore, in relation to this, it may be assumed that applying a preload in the opposite direction as an alternative means elastically pressing the first steering mechanism 14 and the second steering mechanism 20 together by the tension mechanism 26 at the rotational joint between the second steering rods 14b, 20b and the tie rods 14c, 20c to the extent that the steering play of the steering system 10 is offset, adjusted, or eliminated.

[0051] In this case, the distance between both tie rods 14c, 20c and both second steering rods 14b, 20b, particularly at the rotational joints, is reduced, thereby eliminating steering play.

[0052] The tension mechanism 26 may further have a length adjustment mechanism 26a.

[0053] The length adjustment mechanism 26a may be formed, for example, by two linear guides that are movable axially relative to each other, and the linear guides are mounted relative to each other at desired positions (for example, via one or more screw fastenings).

[0054] Additionally or alternatively, the tension mechanism 26 may have a telescopic mechanism.

[0055] The tension mechanism 26 may further include an elastic spring member (not shown in Figure 1).

[0056] The elastic spring member may be formed as an axial spring member.

[0057] In this case, the axial spring member may be formed as an axial compression spring member or an axial tension spring member.

[0058] In this regard, coil springs, diaphragm springs, disc springs, barbed springs, ring springs, gas compression springs, or oil compression springs can be considered as axial compression spring members.

[0059] Furthermore, in relation to this, all of the other spring members mentioned above, which are particularly suitable for coil tension springs and axial tension springs, can be considered as axial tension spring members.

[0060] The elastic spring member may also be formed as a radial spring member, either additionally or alternatively.

[0061] In this case, leaf spring members or rod spring members are particularly conceivable.

[0062] In Figure 1, the second steering gearbox 18 is structurally smaller than the first steering gearbox 12 in at least one dimension.

[0063] The second steering gearbox 18 is formed to be at least about 10% smaller than the first steering gearbox 12, particularly in one structural dimension.

[0064] Preferably, however, the second steering gearbox 18 is structurally formed to be at least 20% smaller than the first steering gearbox 12 in at least one dimension.

[0065] However, particularly preferably, the second steering gearbox 18 is structurally formed to be at least 25% smaller than the first steering gearbox 12 in at least one dimension.

[0066] This dimension, in Figure 1, is, for example, the length of both steering gearboxes 12 and 18.

[0067] However, it is also possible, either additionally or alternatively, that this dimension is the width or height of both steering gearboxes 12, 18.

[0068] Furthermore, the second steering gearbox 18 may be structurally smaller than the first steering gearbox 12 in two or three dimensions.

[0069] Furthermore, the first steering gearbox 12 is connected to the first electric motor 28.

[0070] The first electric motor 28 is flange-fastened to the first steering gearbox 12 and drives a spindle or ball screw internally, which then transmits its driving torque or steering moment to the first output shaft.

[0071] Since the first output shaft is also connected to the first steering mechanism 14, the rotational motion of the output shaft is converted into steering motion of the first wheel 16.

[0072] The first steering gearbox 12 further includes a mechanical direct drive unit 30 that can connect the first steering gearbox 12 to the steering column 32 and the vehicle steering wheel 34.

[0073] The mechanical direct drive unit 30, like the first electric motor 28, is coupled to the spindle or ball screw in a manner that prevents relative rotation, and drives the spindle or ball screw via the steering column 32 by the manual steering action of the vehicle steering wheel 34 produced by the vehicle driver.

[0074] In Figure 1, the second steering gearbox 18 is also connected to the second electric motor 36.

[0075] A second electric motor 36 is flange-fastened to a second steering gearbox 18 and internally drives another spindle or ball screw, which then transmits a drive torque or steering moment to a second output shaft.

[0076] Since the second output shaft is also connected to the second steering mechanism 20, the rotational motion of the output shaft is converted into steering motion of the second wheel 22.

[0077] Furthermore, as is clear from Figure 1, the second steering gearbox 18 can only be driven via the second electric motor.

[0078] In other words, the second steering gearbox 18 is not mechanically connected to the steering column 32 or the vehicle steering wheel 34, but is driven solely by the second electric motor 36.

[0079] The functions of the steering system 10 are described below.

[0080] Under normal driving conditions, that is, when all components of the steering system are functioning as specified, the vehicle driver controls the steering system 10 via the vehicle's steering wheel 34.

[0081] When the vehicle driver rotates the vehicle's steering wheel 34 to control it, that is, as soon as a relative change in the current rotation angle occurs, this rotation is transmitted mechanically to the first steering gearbox 12 via the steering column 32.

[0082] The first steering gearbox 12 also mechanically transmits this rotation of the steering column 32 to the first steering mechanism 14, and the first steering mechanism 14 also turns or rotates the first wheel 16 according to the specified direction in response to the rotation of the vehicle steering wheel 34.

[0083] On the other hand, the rotation angle sensor continuously detects the rotation angle and direction of the steering column 32 and / or the vehicle steering wheel 34, and transmits these values ​​to the steering system 10 or the control device and / or adjustment device of the commercial vehicle (not shown in Figure 1).

[0084] Furthermore, the torque sensor simultaneously continuously detects the steering moment of the steering column 32 and / or the vehicle steering wheel 34, and transmits these values ​​to the control device and / or adjustment device.

[0085] Next, based on these values ​​relating to the rotation angle, rotation direction, and steering moment of the steering column 32 and / or vehicle steering wheel 34, the first and second electric motors 28 and 36 are controlled simultaneously and independently by a control device and / or adjustment device, with minimal time lag (due to system inertia) from manual mechanical steering operation.

[0086] As a result, both electric motors 28 and 36 can independently control both steering gearboxes 12 and 18 simultaneously or synchronously with respect to manual mechanical control via the vehicle steering wheel 34, thereby producing steering assist.

[0087] A tension mechanism 26 applies a preload to the first and second steering gearboxes 12 and 18 via the first and second steering mechanisms 14 and 20, thereby adjusting the play between the first steering gearbox 12 and the second steering gearbox 18.

[0088] If the first and / or second electric motors 28, 36 fail, a tension mechanism 26 is additionally used as a linkage to transmit the steering action of the first steering mechanism 14 to the second steering mechanism 20 and, conversely, to transmit the steering action of the second steering mechanism 20 to the first steering mechanism 14.

[0089] Even if only one of the electric motors 28,36 is functioning correctly, control can still be guaranteed because the two electric motors 28,36 can be controlled independently of each other. [Explanation of symbols]

[0090] 10 Steering System 12. First steering gearbox 14. First steering mechanism 14a First steering rod 14b Second steering rod 14c tie rod 14d Wheel Carrier 16 The First Wheel 18. Second steering gearbox 20. Second steering mechanism 20a First steering rod 20b Second steering rod 20c tie rod 20d Wheel Carrier 22 The Second Wheel 24 front axle 26 Tension mechanism 26a Length adjustment mechanism 28. First electric motor 30 Mechanical direct drive unit 32 Steering column 34. Vehicle steering wheel 36. Second electric motor

Claims

1. A steering system (10) for vehicles, particularly for commercial vehicles, A first steering gearbox (12) and a first steering mechanism (14) for steering at least one first wheel (16), wherein the first steering gearbox (12) is connected to the first steering mechanism (14), At least one second steering gearbox (18) and at least one second steering mechanism (20) for steering at least one second wheel (22), wherein the second steering gearbox (18) is connected to the second steering mechanism (20), and the first wheel (16) and the second wheel (22) are located on the front axle (24) or rear axle of the vehicle, The first steering gearbox (12) and the second steering gearbox (18) are connected by at least one tension mechanism (26) such that a preload can be applied to them in opposite directions relative to each other when the vehicle is stopped. Equipped with, The tension mechanism (26) has at least one length adjustment mechanism. Steering system (10).

2. The steering system (10) according to claim 1, wherein the tension mechanism (26) is rotatably attached to the first steering mechanism (14) and the second steering mechanism (20).

3. The steering system (10) according to claim 1 or 2, wherein the tension mechanism (26) can be elastically preloaded and / or has a preload applied to it in the mounted state.

4. The steering system (10) according to any one of claims 1 to 3, wherein the tension mechanism (26) has at least one elastic spring member.

5. The steering system (10) according to claim 4, wherein the elastic spring member is formed as an axial spring member.

6. The steering system (10) according to claim 4, wherein the elastic spring member is formed as a radial spring member, particularly as a leaf spring member.

7. The steering system (10) according to any one of claims 1 to 6, wherein the second steering gearbox (18) is structurally smaller than the first steering gearbox (12) in at least one dimension.

8. The steering system (10) according to claim 7, wherein the second steering gearbox (18) is structurally formed to be at least about 10%, preferably at least 20%, and particularly preferably at least 25% smaller than the first steering gearbox (12) in at least one dimension.

9. The steering system (10) according to any one of claims 1 to 8, wherein the first steering gearbox (12) is connected to at least one first electric motor (28), and the second steering gearbox (18) is connected to at least one second electric motor (36).

10. The steering system (10) according to claim 9, wherein the second steering gearbox (18) can only be driven via the second electric motor (36).

11. The steering system (10) according to any one of claims 1 to 10, wherein the first steering gearbox (12) has at least one mechanical direct drive unit (30) that can connect the first steering gearbox (12) to at least one steering column (32) and a vehicle steering wheel (34).

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