System for determining the state variables of a vehicle tire

Abstract

The invention relates to a system for determining state variables of a vehicle tire (2) equipped with a TPMS tire pressure monitoring system (22), wherein the system comprises at least one housing (1) that can be driven over by the vehicle tire (2) with at least one radar sensor (12) integrated into the housing (1) for measuring the tread depth of the vehicle tire (2) and an evaluation unit (3) for evaluating the tread depth measured by the radar sensor (12), wherein the at least one radar sensor (12) is also configured to measure the contact area (23) of the vehicle tire (2) and the measured contact area (23) can be transmitted to the evaluation unit (3) and the evaluation unit (3) is connected to a receiver (4) by means of which measured values ​​of the TPMS tire pressure monitoring system (22) of the vehicle tire (2) can be read out and transmitted to the evaluation unit (3).

Description

[0001] The invention relates to a system for determining state variables of a vehicle tire equipped with a TPMS tire pressure monitoring system, wherein the system comprises at least one housing over which the vehicle tire can roll, with at least one radar sensor integrated into the housing for measuring a tread depth of the vehicle tire, and an evaluation device for evaluating the tread depth measured by the radar sensor.

[0002] Such systems with at least one housing over which the vehicle tire can roll are known as drive-over systems (DOS), for which reference is made to US 2017 / 0350781 A1 and US 2008 / 0256815 A1 for examples. They are used to automatically check and monitor the tread depth of the vehicle tire using a corresponding sensor when the vehicle tire rolls over the housing.

[0003] EP 1 952 092 B1 also discloses detecting tread depth using a radar sensor integrated into the housing. Radar sensors emit electromagnetic waves or radio waves that are reflected by most objects, which can then be detected by the radar sensor. The tread depth can then be calculated from the travel times of the emitted waves in an associated evaluation device.

[0004] Particularly in fleet management systems and in the context of vehicle maintenance of a large number of vehicles, it is desirable to monitor and test not only the tread depth but also other condition variables of a vehicle tire in the simple and fast test procedure typical for DOS systems by simply rolling over the housing containing the sensor.

[0005] The object of the invention is therefore to expand the existing DOS systems with regard to the range of state variables that can be determined during rollover.

[0006] To achieve the stated object, the invention proposes the design of a system of the type mentioned at the outset with the features specified in claim 1.

[0007] Advantageous embodiments and further developments of the invention are the subject of the dependent claims.

[0008] The proposed invention provides that the radar sensor intended for measuring tread depth is used not only to measure the tread depth but also to measure the contact patch of the vehicle tire and transmit the measured contact patch to the evaluation device. Furthermore, the evaluation device is connected to a receiving device, by means of which measured values ​​from the TPMS tire pressure monitoring system of the vehicle tire can be read out and also transmitted to the evaluation device.

[0009] The contact patch of a vehicle tire is the area with which the vehicle tire rests on the ground at every moment of its rotation, which is often also referred to as tire contact area.

[0010] According to the invention, it was found that by measuring the contact area and incorporating the associated measured values ​​from the TPMS tire pressure monitoring system of the respective vehicle tire, not only can the tread depth of the respective vehicle tire be determined in a conventional manner, but moreover, the load acting on the respective vehicle tire can also be determined quickly and easily while the system according to the invention is rolling over it. Since the contact area resulting from a specific applied load depends to a large extent on the tire pressure prevailing in the respective vehicle tire being measured, the invention provides that at least measured values ​​of the tire pressure, preferably also the measured value of the temperature of the vehicle tire, can be read out from the TPMS tire pressure monitoring system by means of the receiving device and transmitted to the evaluation device.

[0011] According to a further proposal of the invention, the system can also include a device for identifying the vehicle tire, which is also coupled to the evaluation device. In this way, the tire format, tire type, and other data, such as manufacturer, etc., can be read from corresponding RFID tags provided in the vehicle tire and transmitted to the evaluation device for appropriate consideration.

[0012] According to a further proposal of the invention, the system comprises several, in particular two housings over which vehicle tires can roll, with at least one radar sensor integrated into the housing, each at a distance corresponding to the track width of a vehicle carrying the vehicle tires, which distance can also be adjustable if necessary. It is thus possible, while the system rolls over, to measure the vehicle tires on the vehicle axle by axle using the radar sensors integrated into the respective housings and in the manner according to the invention. The measured values ​​can then be compared in the evaluation device so that, in addition to the individual wheel load of the vehicle tires, the axle load, axle load distribution, possible overload and / or uneven load distribution on a vehicle can be determined.

[0013] It is understood that all of the aforementioned determinable state variables can be measured, displayed, archived and / or, if necessary, used to generate warnings when predetermined limit values ​​are exceeded or undershot within the framework of the system according to the invention.

[0014] According to a further proposal of the invention, at least the surfaces of the housing and / or the radar sensor of the system according to the invention over which the vehicle tire rolls are designed to be heated, in order to eliminate potential sources of error, particularly during outdoor installations, caused by weather influences, particularly snow and ice during the cold season. According to the invention, the surfaces over which the vehicle tire rolls over the system according to the invention are heated at correspondingly cold temperatures so that no snow or a layer of ice can form on them, or such a layer is melted.

[0015] A further positive effect of such heating is that the temperature range in which the radar sensors used to measure the tread depth and contact area can be used can be kept smaller, which can improve the measurement result.

[0016] Within the scope of the invention, it has proven sufficient if the surface of the system according to the invention over which the vehicle tire can roll can be heated, for example, using appropriate electrical heating elements, to temperatures of approximately 5-7 °C. Either the radar sensor itself or parts of it or the housing can be heated. If the housing has a ramp, this can also be heated to facilitate the crossing.

[0017] Furthermore, according to a further proposal of the invention, it can also be provided that the surfaces of the housing over which the vehicle tire can roll are arranged inclined relative to the horizontal so that rain as well as water which is created when snow and ice melt can run off or be drained away more easily.

[0018] According to a further proposal of the invention, in order to extend the service life of the radar sensors used and to save energy, the system can comprise at least one proximity sensor by means of which an impending or currently occurring rolling over of the at least one housing can be detected in order to switch on the otherwise switched off system in this case and, for example, to switch it off again after a predetermined period of time has elapsed.

[0019] According to the invention, the proximity sensors used can, for example, be a pressure sensor that responds to the load on the housing when the vehicle tire rolls over it, or at least one corresponding mechanical switch is provided that is capable of detecting the vehicle tire rolling over the housing. Furthermore, the proximity sensor can additionally or alternatively also be formed by an electromagnetic sensor, for example, a sensor capable of identifying and reading RFID tags attached to the vehicle and / or the vehicle tire.

[0020] If, according to a further proposal of the invention, the system also comprises a corresponding database containing vehicle-specific information associated with the RFID tags, which can be transmitted to the evaluation device, more precise situational information can be transmitted to the evaluation device, for example, information about the direction of travel of the vehicle tire rolling over the system, information about the type of vehicle tire, or even about the type of vehicle to which the vehicle tire is attached. For example, this can also be used to detect whether a tractor unit is being driven by a trailer, so that the evaluation device can also determine which vehicle tire or which vehicle axle is currently rolling over the system according to the invention.

[0021] Further embodiments and details of the invention are explained below using a schematic embodiment in the drawing. They show: Fig. 1 a schematic perspective view of a system according to the invention; Fig. 2 the supervision of the system in accordance with Fig. 1; Fig. 3 the schematic side view of the system; Fig. 4 a measurement result of the system according to the invention.

[0022] The figures show a system for determining state variables of a vehicle tire 2, which is designed as a conventional pneumatic tire and mounted on a vehicle rim (not shown here). In a conventional manner, the vehicle tire 2 has a sensor of a TPMS tire pressure monitoring system 22 in the region of the valve or at a suitable location, for example, in the region of the inner surface.

[0023] In order to determine different state variables of the vehicle tire, for example the tread depth, the system has a housing 1 over which the vehicle tire 2 can roll, with at least one radar sensor 12 integrated into the housing 1.

[0024] To facilitate rolling over the housing 1, corresponding ramps 10, 11 are provided in front of and behind the housing 1 in the direction of travel, although it would also be possible for the housing 1 to be recessed into the ground, which would make the ramps 10, 11 unnecessary.

[0025] In addition to the radar sensor 12 integrated into the housing 1, a receiving device 4 is also provided, by means of which measured values ​​of the TPMS tire pressure monitoring system 22 can be read out via the radio connections used by such TPMS tire pressure monitoring systems 22 while the housing 1 is rolled over and transmitted to an evaluation device 3, which also receives the measured values ​​of the radar sensor 12.

[0026] In addition, a receiver for reading RFID tags can also be provided in a manner not shown in detail, which can be arranged on the vehicle and / or the vehicle tires 2 and can transmit further information about the type, type and format of the vehicle tire and the vehicle to the evaluation device 3.

[0027] As can be seen in particular from the illustration in accordance with Fig. 3, the vehicle tire 2 mounted on a vehicle not shown here rolls over the housing 1 in an exemplary direction of travel F by first driving up the ramp 10, rolling over the housing 1 and then being guided back to the ground U via the ramp 11. Corresponding proximity sensors, which can be installed, for example, in the ramps 10, 11, register the approaching vehicle tire 2 and switch on the evaluation device 3, the receiving device 4 and the radar sensor 12.

[0028] At the moment the vehicle tire 2 rolls over the housing 1, it passes the radar sensor 12 arranged in the housing and aligned with the circumferential tread of the vehicle tire 2.

[0029] In addition to simply determining the tread depth during rolling over, the radar sensor 12 of the system is also designed and suitable for measuring the contact area 23 of the vehicle tire 2, with which it is in contact with the ground, and for transmitting the measured contact area 23 to the evaluation device 3.

[0030] The resulting contact patch 23 for a given vehicle tire 2 depends on the load acting on the vehicle tire 2 as well as its inflation pressure, and to a lesser extent on its temperature. As the load increases, the contact patch 23 of the vehicle tire 2 becomes larger, provided the inflation pressure remains constant.

[0031] The Fig.Figure 4 shows an example result of the measurements of the radar sensor 12 after rolling over the housing 1. Information about the depth of the profile grooves 21 as well as the length L and width B of the contact surface 23 is available. These measured values ​​are transmitted to the evaluation device 3

[0032] In addition, the evaluation device 3 can access the measured values ​​of the tire pressure and the temperature received by the receiving device 4 from the TPMS tire pressure monitoring system 22 installed on the vehicle tire 2.

[0033] From these measured values ​​transmitted to the evaluation device 3, the latter can then determine, in addition to the state variable of the tread depth, the wheel load of the vehicle tire and any possible overload of the vehicle tire.

[0034] If, what is not shown in the figures, the system comprises several, in particular two housings that can be rolled over by vehicle tires 2 and have at least one radar sensor 12 integrated into the housing 1, which are each arranged at a distance from one another corresponding to the track width of the vehicle carrying the vehicle tires 2, the respective axle load and / or load distribution of a vehicle can also be determined by comparison and, if corresponding limit values ​​are exceeded, can also be displayed with corresponding warnings.

[0035] The system explained above is switched on as needed by means of sensors not shown in detail only when a vehicle tire rolls over the housing 1, for example with the pressure sensors integrated in the ramps 10, 11, which act as a proximity sensor to register the approaching vehicle tire 2 and temporarily switch on the power supply of the system.

[0036] A high degree of independence from weather influences is also achieved by the fact that the surfaces of the housing 1 and the radar sensor 12, as well as the two ramps 10, 11, over which the vehicle tire 2 rolls, can be heated by means of electrical heating elements (not shown here) to counteract the accumulation of snow and ice or to melt them. Furthermore, all surfaces of the housing 1 over which the vehicle tire 2 rolls can also have a certain inclination relative to the horizontal, so that rainwater can be more easily drained or channeled away. List of reference symbols 1 housing 2 vehicle tires 3 Evaluation device 4 Receiving device 10 Ramp 11 Ramp 12 radar sensor 21 tread grooves 22 TPMS tire pressure monitoring system 23 Contact area F Direction of travel B Width of the contact area L Length of the contact area Underground QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] US 2017 / 0350781 A1

[0002] US 2008 / 0256815 A1

[0002] EP 1 952 092 B1

[0003]

Claims

[1] System for determining state variables of a vehicle tire (2) which is equipped with a TPMS tire pressure monitoring system (22), wherein the system comprises at least one housing (1) over which the vehicle tire (2) can roll, with at least one radar sensor (12) integrated into the housing (1) for measuring a tread depth of the vehicle tire (2) and an evaluation device (3) for evaluating the tread depth measured by the radar sensor (12), characterized by that the at least one radar sensor (12) is also designed to measure the contact area (23) of the vehicle tire (2) and the measured contact area (23) can be transmitted to the evaluation device (3) and the evaluation device (3) is connected to a receiving device (4) by means of which measured values ​​of the TPMS tire pressure monitoring system (22) of the vehicle tire (2) can be read out and transmitted to the evaluation device (3). [2] System according to claim 1, characterized bythat measured values ​​of the tire pressure and the temperature of the vehicle tire (2) can be read out from the TPMS tire pressure monitoring system (22) by means of the receiving device (4). [3] System according to claim 1 or 2, characterized by that the system comprises a device for identifying the vehicle tire (2) which is coupled to the evaluation device (3). [4] System according to one of claims 1 to 3, characterized by that the system comprises two housings (1) which can be rolled over by vehicle tires (2) and which have at least one radar sensor (12) integrated into the housing (1), which are each arranged at a distance from one another corresponding to the track width of a vehicle carrying the vehicle tires. [5] System according to one of claims 1 to 4, characterized by that the wheel load of the vehicle tire (2) and / or the axle load, overload and / or uneven load distribution of a vehicle can be determined by means of the evaluation device (3). [6] System according to one of claims 1 to 5, characterized by that at least the surfaces of the housing (1) and / or the radar sensor (12) that can be rolled over by the vehicle tire (2) are heatable. [7] System according to one of claims 1 to 6, characterized by that at least the surfaces of the housing (1) over which the vehicle tire (2) can roll are arranged inclined relative to the horizontal. [8] System according to one of claims 1 to 7, characterized by that the system comprises at least one proximity sensor, by means of which a rolling over of the at least one housing (1) can be detected and the system can be activated. [9] System according to claim 8, characterized by that the proximity sensor is formed by a pressure sensor, a switch and / or an electromagnetic sensor. [10] System according to one of claims 8 or 9, characterized by that the proximity sensor includes a receiver for reading RFID tags. [11] System according to claim 10, characterized by that the system comprises a database containing vehicle-specific information associated with the RFID tags, which can be transmitted to the evaluation device (3).

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