Speed ​​control system for a motor vehicle

Abstract

A speed control system (16) for regulating a set driving speed of a motor vehicle is provided, comprising a lever (18) for setting the driving speed and a resistance device (20) acting on the lever (18) to provide a resistance force, wherein the resistance force depends on a magnetic force of an electromagnet (26) of the resistance device (20) that can be switched in several stages. The electromagnet (26), which can be switched in several stages, can signal various information to the speed control system (16) via the haptically perceptible resistance force, corresponding to the switched stage of the electromagnet (26), thus enabling simple and cost-effective control of a motor vehicle's driving speed while maintaining a high level of driving safety.

Description

[0001] The invention relates to a speed control system by which the driving speed of a motor vehicle can be regulated. The invention further relates to a motor vehicle with such a speed control system and to a method by which the driving speed of a motor vehicle with such a speed control system can be regulated.

[0002] From DE 10 2013 010 452 A1 a speed control system for a motor vehicle is known in which a lever intended for setting a target speed can be subjected to an increased restoring force if the target speed that would otherwise be set would be above a detected prescribed maximum speed.

[0003] There is a constant need to be able to regulate the speed of a motor vehicle simply and cost-effectively while maintaining a high level of driving safety.

[0004] The object of the invention is to demonstrate measures that enable simple and cost-effective control of the driving speed of a motor vehicle while maintaining a high level of driving safety.

[0005] The problem is solved according to the invention by a speed control system with the features of claim 1, a motor vehicle with the features of claim 9, and a method with the features of claim 10. Preferred embodiments of the invention are specified in the dependent claims and the following description, each of which can individually or in combination represent an aspect of the invention, the scope of protection being determined by the claims.

[0006] One aspect of the invention relates to a speed control system for regulating a set driving speed of a motor vehicle, comprising a lever for setting the driving speed and a resistance device acting on the lever to provide a resistance force, wherein the resistance force depends on a magnetic force of an electromagnet of the resistance device that can be switched in several stages.

[0007] This allows the cruise control lever to be pivoted against the provided resistance force, thus changing the set speed by a defined increment. This resistance force can be generated by the electromagnet, which may need to be amplified. Since the electromagnet can be switched in multiple stages, a corresponding number of different resistance forces can be provided, particularly to transmit specific information about the resistance applied to the lever as feedback to the driver. For example, the level of resistance can indicate the size of the increment by which the currently set speed would be changed.This approach takes advantage of the fact that switching the electromagnet to a different stage, which provides a different magnetic force and thus a different resistance, is usually accomplished using an electronic switching element. This element can simultaneously switch another setting in the cruise control system, such as the increment by which the set speed is to be adjusted. The same trigger signal that changes a setting in the cruise control system can be used to switch the electromagnet to a different stage. This allows the changed setting in the cruise control system to be signaled to the driver as haptic feedback via a change in resistance.This provides the driver with haptic feedback on the cruise control setting when the lever is operated, thus preventing excessively high or low speeds and the associated potentially unnecessarily dangerous driving situations. The multi-stage switchable electromagnet allows the cruise control system to signal different information corresponding to its activated stage via haptically perceptible resistance, enabling simple and cost-effective speed control of a vehicle while maintaining a high level of driving safety.

[0008] The cruise control system can be configured to regulate the power and / or torque of a drive unit, particularly an electric and / or internal combustion engine, so that the vehicle maintains the set speed. The cruise control system can constitute a driver assistance system that allows the vehicle's speed to be set without using an accelerator pedal or similar device. Specifically, in Eco mode, the cruise control system can operate the drive unit at a particularly energy-efficient operating point for the set speed. Additionally or alternatively, in Sport mode, the cruise control system can operate the drive unit at a particularly high-performance operating point for the set speed, enabling especially rapid and powerful acceleration.

[0009] The lever of the cruise control system, also known as speed control, can be located on the steering wheel, similar to a turn signal lever. By pivoting the lever, the set speed can be decreased or increased, the cruise control system can be activated or deactivated, and / or the increment by which the set speed can be changed can be adjusted. The lever can be pivoted circumferentially relative to the steering column, rotated longitudinally along the lever and / or radially along the steering column, and / or pivoted about a tangent to the steering column. The lever's movement is relative to a neutral position, to which it automatically returns when no external force is applied by the driver.The relative position and / or orientation of the lever to the zero position can be detected, for example, using displacement and / or angle sensors. In particular, moving the lever in one direction can increase the set driving speed, and moving it in the opposite direction can decrease the set speed. The lever can be pre-tensioned, especially by means of at least one spring acting on the lever, so that it automatically returns to the zero position when the driver does not apply any external force to move it from the zero position.

[0010] The resistance device can provide the resistance force acting on the lever with the aid of the switchable electromagnet. It is specifically designed that the resistance force scales with the magnetic force provided by the electromagnet. It is generally possible for the resistance force to be identical to the magnetic force of the electromagnet, but with a force amplification between the magnetic force generated by the electromagnet and the resistance force of the resistance device acting on the lever. This force amplification can be provided by a linear, particularly proportional, or even a non-linear force transmission. The magnitude of the resistance force depends on the magnitude of the magnetic force of the electromagnet.The resistance device may include a switching element which, in response to a detected position and / or location of the lever, makes a change in the speed control system, in particular changes the amount of the set driving speed, and at the same time switches the electromagnet to a different stage which is associated with a different resistance force.

[0011] The electromagnet can be part of the resistance device. The electromagnet can be switched in several stages and thus be designed as a multi-stage electromagnet. Preferably, the stages are provided in discrete steps, so that a magnetic force or resistance force distinguishable from the other stages is perceptible at the lever at each stage of the electromagnet. However, it is also possible that at least in a partial area, a continuous change in the magnetic force or resistance force between two different stage values ​​is provided. The electromagnet can, in particular, surround a section of the lever. The ferromagnetic material of the lever, for example, can act as the core of the electromagnet and interact with it. The magnetic field of the electromagnet can thus easily act directly or indirectly on the lever to provide the resistance force.

[0012] In particular, the magnetic force acts on an electrorheological fluid to effect a force transmission from the magnetic force to the resistance force. An electrorheological fluid is a fluid that changes its viscosity in an electric and / or a magnetic field. The stronger the magnetic field exerted on the electrorheological fluid by the electromagnet, the greater the viscosity of the electrorheological fluid can be. The electrorheological fluid can stiffen in an increasing magnetic field. The electrorheological fluid can act on the lever, especially when a portion of the lever passes through a volume occupied by the electrorheological fluid.If the viscosity of the electrorheological fluid stiffens due to a stage of the electromagnet with a high magnetic force and a high magnetic field strength, a correspondingly high resistance force against a relative movement of the lever results, which is easily perceptible to the driver.

[0013] Preferably, in a final stage, the electromagnet exerts a magnetic force that essentially stiffens the electrorheological fluid in order to block the lever at least in one direction and / or to hold it firmly in place. The viscosity of the electrorheological fluid can be increased by the magnetic field of the electromagnet, in particular to such an extent that the electrorheological fluid behaves almost like a solid under the expected external forces and thereby blocks the lever.

[0014] Preferably, the blocking occurs in only one direction, allowing the lever to automatically return to the zero position. For example, touching the lever and / or applying a force to it in the direction to be blocked can be detected, leading to the electromagnet switching to a stage, particularly the final stage, where a correspondingly high resistance force is provided. If no force is detected on the lever in the direction to be blocked, the electromagnet can be switched to a stage where no or only a very low resistance force is provided, allowing the lever to automatically return to the zero position.

[0015] Specifically, the electromagnet is designed to provide low resistance in a low setting and a medium resistance higher than in a low setting. In the low setting, the speed can be adjusted by a small increment, and in the medium setting by a large increment higher than in the low setting. This allows the rider to change the set speed by the small increment, for example, 1 km / h, with a light touch of the lever, while a stronger press of the lever, overcoming even the medium resistance, changes the set speed by the large increment, for example, 10 km / h.

[0016] Preferably, the lower setting is selectable within a first angular range encompassing the lever's neutral position, while the intermediate setting is selectable only within a second angular range of the lever that is pivoted outside the first. With only a small pivoting movement of the lever relative to the neutral position, only a small resistance force and a small incremental change in the set travel speed are provided. If the lever is pivoted so far that it leaves the first angular range and enters the second angular range, which is significantly further from the neutral position, a high resistance force and a large incremental change in the set travel speed can be provided.

[0017] Particularly preferred is a maximum travel speed and / or a minimum travel speed for the set travel speed, wherein an adjustment of the set travel speed by one increment to a travel speed above the maximum travel speed and / or below a minimum travel speed is blocked by the resistance force of the electromagnet switched in a final stage. Exceeding the maximum travel speed and / or falling below the minimum travel speed can be avoided by ensuring that the switching position of the electromagnet provides a resistance force sufficient to prevent movement of the lever into an angular position that would cause the travel speed to be exceeded.This makes it possible, for example, to maintain maximum and / or minimum speeds intended for driving safety even if the driver accidentally intends to exceed these limits. If, in a specific driving situation, the intended maximum and / or minimum speed is to be deliberately exceeded, for example when driving on a track designated for racing, it may be necessary to deactivate the cruise control system beforehand.

[0018] In particular, a traffic sign recognition system is provided for the detection of traffic signs, whereby the maximum and / or minimum speed is derived from the at least one detected traffic sign. This simplifies compliance with legally prescribed speed limits regarding maximum and / or minimum speeds. It also helps maintain a high level of driving safety in areas where, for example, the danger posed by excessive speed is not immediately apparent.

[0019] It is particularly preferred that, if the currently set speed is higher than the intended maximum speed, the set speed is automatically reduced to the intended maximum speed. Additionally or alternatively, it can be provided that, if the currently set speed is lower than the intended minimum speed, the set speed is automatically increased to the intended maximum speed. Preferably, the resistance force is varied essentially continuously within an upper range of distances and a corresponding angular range for pivoting the lever, extending up to the maximum speed, and / or within a lower range of distances and a corresponding angular range for pivoting the lever, extending up to the minimum speed.The resistance force acting on the lever can increase continuously until a certain limit is reached, so that further movement of the lever can be blocked once this limit is reached, without surprising the driver. The respective interval range can be large enough for the driver to intuitively feel when the limit is reached. In particular, the respective interval range is small enough to allow for further, abruptly changing levels of resistance.

[0020] Another aspect concerns a motor vehicle with a cruise control system, which, as described above, can be designed and further developed to regulate a set driving speed. The multi-stage switchable electromagnet allows the cruise control system to receive various signals corresponding to the switched stage of the electromagnet via the haptically perceptible resistance force, thus enabling simple and cost-effective speed control of a motor vehicle while maintaining a high level of driving safety.

[0021] Another aspect concerns a method for regulating the speed of a motor vehicle using a cruise control system, which can be designed and further developed as described above, in which the magnetic force of the electromagnet prevents the vehicle's speed from being set above a predetermined maximum speed and / or below a predetermined minimum speed by blocking the lever. The multi-stage switchable electromagnet allows the cruise control system to receive various signals corresponding to the activated stage of the electromagnet via the haptically perceptible resistance force, thus enabling simple and cost-effective speed control of a motor vehicle while maintaining a high level of driving safety.

[0022] The invention is now explained by way of example with reference to the accompanying drawings and preferred embodiments, wherein the features shown below can represent an aspect of the invention, either individually or in combination, and the scope of protection is defined by the claims. The drawings show: Fig. 1: A schematic top view of a steering column module with a cruise control system and Fig. 2: a schematic diagram of a part of the speed control system made of Fig. 1.

[0023] The in Fig. The steering column module 10 shown in Figure 1 can encompass a steering column of a motor vehicle connected to a steering wheel. The steering column module 10 can include a turn signal lever 12 for activating a turn signal and a wiper lever 14 for activating a windshield wiper. The steering column module 10 can also include at least part of a cruise control system 16, which has a lever 18 for setting a speed to be maintained automatically.

[0024] As in Fig.As outlined in Figure 2, the speed control system 16 can include a resistance device 20, which has a housing 22 through which the lever 18 can pass. The housing 22 can contain an electrorheological fluid 24, which can be stiffened by means of an electromagnet 26 to impose a resistance force on the lever that depends on the magnitude of the magnetic force of the electromagnet 26. The electromagnet can be switched in several stages by means of a switching element 28, wherein, in particular, a different magnetic field generated by the electromagnet and a corresponding resistance force are provided at each switched stage. For this purpose, the switching element 28 can be actuated by a release signal 30, which, for example, corresponds to a relative position of the lever to a zero position.In particular, the trigger signal 30 and / or the switching element 28 can simultaneously make a corresponding setting in the speed control system 16, for example by changing the set driving speed stored in a memory 32 by a certain increment. 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] DE 10 2013 010 452 A1

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