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EP-4740004-A1 - MEASURING CLAMP FOR MEASURING THE CONDUCTIVITY PROPERTIES OF VEHICLE TIRES, AND CORRESPONDING METHOD

EP4740004A1EP 4740004 A1EP4740004 A1EP 4740004A1EP-4740004-A1

Abstract

The invention relates to a measuring clamp (10) for measuring the conductivity properties of vehicle tires, comprising: i) a main part (12), ii) a first clamp element (14) which is connected to the main part (12), said first clamp element (14) comprising an electrically conductive first contacting element (16), iii) a second clamp element (18) which is connected to the main part (12) and is arranged at a distance to the first clamp element (14), said second clamp element (18) comprising an electrically conductive second contacting element (20), and iv) a measuring unit (22) which is connected to the first contacting element (16) and the second contacting element (20) for measuring the connectivity properties, wherein the first contacting element (16) is arranged on the first clamp element (14) face facing in the direction of the second clamp element (18), and the second contacting element (20) is arranged on the second clamp element (18) face facing in the direction of the first clamp element (14). The measuring clamp (10) is designed such that the distance between the first clamp element (14) and the second clamp element (18) can be modified in a reversible and nondestructive manner, and the first contacting element (16) comprises a plurality of electrically conductive first conductor elements which extend from the surface of the first clamp element (14).

Inventors

  • KASTENS, SVEN
  • KUNZE, CHRISTIAN
  • Gandyra, Stefan

Assignees

  • Continental Reifen Deutschland GmbH

Dates

Publication Date
20260513
Application Date
20240619

Claims (10)

  1. 1. Measuring clamp (10) for measuring the conductivity properties of vehicle tires, comprising: i) a base body (12), ii) a first clamp element (14) connected to the base body (12), the first clamp element (14) comprising an electrically conductive first contacting element (16), iii) a second clamp element (18) connected to the base body (12) and spaced apart from the first clamp element (14), the second clamp element (18) comprising an electrically conductive second contacting element (20), iv) a measuring unit (22) connected to the first contacting element (16) and the second contacting element (20) for measuring the conductivity properties, the first contacting element (16) being arranged on the side of the first clamp element (14) pointing in the direction of the second clamp element (18), the second contacting element (20) being arranged on the side facing in the direction of the first clamp element (14) facing side of the second clamp element (18), wherein the measuring clamp (10) is designed so that the distance between the first clamp element (14) and the second clamp element (18) can be changed reversibly and non-destructively, wherein the first contacting element (16) comprises a plurality of electrically conductive first conducting elements extending from the surface of the first clamp element (14).
  2. 2. Measuring clamp (10) according to claim 1, wherein the base body (12) comprises a handle (24).
  3. 3. Measuring clamp (10) according to one of claims 1 or 2, wherein the first clamp element (14) is connected in a fixed position to the base body (12), wherein the second clamp element (18) is arranged on the base body (12) so as to be reversibly and non-destructively movable.
  4. 4. Measuring clamp (10) according to one of claims 1 to 3, wherein the first contacting element (16) comprises 10 or more electrically conductive first conducting elements.
  5. 5. Measuring clamp (10) according to one of claims 1 to 4, wherein the first conducting elements consist at least partially of an electrically conductive material which is selected from the group consisting of metals and carbon fiber reinforced plastic.
  6. 6. Measuring clamp (10) according to one of claims 1 to 5, wherein the first contacting element (16) is a brush, wherein the first conducting elements are electrically conductive bristles.
  7. 7. Measuring clamp (10) according to one of claims 1 to 6, wherein the second contacting element (20) is a brush, wherein the second conducting elements are electrically conductive bristles.
  8. 8. Measuring clamp (10) according to one of claims 1 to 7, wherein the measuring clamp (10) additionally comprises: v) a pretensioning mechanism (26) arranged between the first clamp element (14) and the second clamp element (18).
  9. 9. Measuring clamp (10) according to one of claims 1 to 8, wherein the measuring unit (22) is a resistance measuring device.
  10. 10. Method for determining the conductivity properties of vehicle tires with a measuring clamp (10) according to one of claims 1 to 9, comprising the method steps: a) producing or providing a vehicle tire, comprising two tire beads and a tread located on the outside in the radial direction, b) contacting one of the tire beads with the second contacting element (20), c) contacting the tread with the first conducting elements of the first contacting element (16), d) measuring the conductivity properties of the vehicle tire between the first contacting element (16) and the second contacting element (20) with the measuring unit (22).

Description

CLAMP FOR MEASURING THE CONDUCTIVITY PROPERTIES OF VEHICLE TIRES AND ASSOCIATED METHOD Description The invention relates to a measuring clamp for measuring the conductivity properties of vehicle tires and a corresponding method for determining the conductivity properties of vehicle tires using such a measuring clamp. An essential component of modern pneumatic vehicle tires, which in many cases is largely responsible for the performance characteristics of these products, is the tread. Nowadays, treads usually consist of several different components, in particular different rubber materials, which can be obtained by vulcanization from vulcanizable rubber compounds. In cross-sectional view, most treads, especially in the car and truck sector, comprise one or more rubber materials that are intended to come into contact with the road surface during later use and whose properties are optimized for this purpose. This layer, which acts as a kind of top layer, is made from a vulcanizable rubber mixture, sometimes referred to as a "cap mixture", which often contains large amounts of non-electrically conductive fillers, such as precipitated silicon dioxide. There is usually a base underneath the rubber material intended for contact with the road. In the majority of cases, this base serves primarily to create sufficient adhesion between the top layer intended for contact with the road and the other parts of the pneumatic vehicle tire, so that a high bond strength between the tread and the other components of the vehicle tyre can be ensured. The person skilled in the art is aware that for the majority of applications, a tread must, for technical and/or regulatory reasons, have a certain electrical conductivity as a whole, which can prevent undesirable static charging. In many cases, however, the rubber material of the cover layer does not have sufficient electrical conductivity to ensure this. Therefore, in the prior art, the electrical conductivity of the entire tread is usually achieved by the base mixture of the underlying base, which has an increased electrical conductivity, in particular as a result of a high carbon black content. For this purpose, for example, a strand of material from the base is guided to the top of the tread, which thereby creates an electrically conductive connection between the surface of the tread and the base. The electrically conductive base mixture is usually formed to the surface of the tread by a pre-template in the extruder. The corresponding structure is also referred to as a "carbon center beam" (CCB). Information on the technological background is disclosed, for example, in DE 4445758 B4, DE 69717958 T2, EP 1792720 A2, NL 2006420 C2 and US 2018170123 A1. Due to the high safety and regulatory relevance of sufficient conductivity of vehicle tires, checking for the presence of the desired conductivity is an important part of the quality testing of vehicle tires. As a standard, the conductivity of vehicle tires is usually determined on a special test bench, for example according to the Guideline 110 of the German Rubber Industry Association (WdK). For this, the vehicle tire is mounted on a steel rim, on which it must remain for 8 hours before the measurement is carried out. The vehicle tire is then pressed against a steel plate with a defined force and conductivity measurements are carried out automatically at three different circumferential points (offset 120°). This test is very time-consuming for each vehicle tire and requires a lot of equipment. Accordingly, only a few tires can be measured in succession on a regular basis, particularly because larger batches would require a corresponding number of rims. This means that only individual tires from a batch can be measured at any one time, unless a lot of time is to be spent checking an entire batch. Further information on the technological background is disclosed, for example, in WO 2020109995 A1 , CN 207703756 U, EP 3894847 A1 , US 8211258 B2 and CN 1390698 A. In view of the high time and cost involved, the established standard procedure makes it impossible in practice, from an efficiency point of view, to carry out the desirable complete inspection of an entire batch of tires. For this reason, tire manufacturing often uses an unofficial test that can be used to more quickly estimate the conductivity properties of pneumatic vehicle tires. An insulation measuring device is used for this, which is equipped with a crocodile clip and an electrode tip. In use, the crocodile clip is usually clamped into the tire bead and the tip is used to make contact with the conductive area of the tread, ie the CCB. This test delivers conductivity values much more quickly, which are at least qualitatively comparable to the values of the official test. The challenge when using such a handheld device is that it is often difficult to make correct and reproducible contact with the vehicle tires. In particular, it is challenging to reliably hit the CCB wi