V-ribbed belt and method for producing same

Abstract

A v-ribbed belt manufactured in a molding or grinding process has in different areas of the structure thereof different elastomer materials. In upper rib segments oriented toward the belt pulley there is an elastomer material that is not electrically conductive. The lower rib segments are made of an electrically conductive elastomer material. The height ratio a/(a+b) of the height (a) of the lower rib segments to the overall height (a+b) of the rib, as measured at the material boundary located at the rib flank, is at least 6 percent, or the absolute height of the lower rib segments is at least 0.12 mm.

Claims

1. A V-ribbed belt, comprising: a plurality of ribs configured for engagement of a multi-grooved belt pulley at rib flanks on opposite sides of each rib, wherein each rib of the plurality of ribs has an upper rib segment formed from a non-conductive elastomer material and a lower rib segment formed from a conductive elastomer material, wherein a material boundary between the non-conductive elastomer and the conductive elastomer in each rib extends to the rib flanks, wherein the lower rib segments of the plurality of ribs have a height dimension measured from a bottom of a valley between each two adjacent ribs of the plurality of ribs to the material boundary between the lower rib segment and the upper rib segment at the rib flanks of the two adjacent ribs is at least 0.12mm, and wherein each rib has a tip and wherein a height ratio of the height dimension of the lower rib segments to a second height dimension measured from the valley between the two adjacent ribs to a plane connecting tips of the two adjacent ribs is at least 6% wherein elastomer material in the non-conductive elastomer material and the conductive elastomer material is the same, and filler in the non-conductive elastomer material and the conductive elastomer material is different, wherein the filler in the conductive elastomer material includes carbon black, and wherein the filler in the non-conductive elastomer material includes silica.

2. The V-ribbed belt as claimed in claim 1, further comprising an adjacent zone which surrounds and extends below the valleys and extends over an entire width of the V-ribbed belt and which is formed from the conductive elastomer material of the lower rib segments.

3. The V-ribbed belt as claimed in claim 1, wherein the material boundary between the upper rib segment and the lower rib segment is curved toward the tip between the rib flanks on opposite sides of the rib.

4. The V-ribbed belt as claimed in claim 1, wherein the material boundary between the upper rib segment and the lower rib segment is flat between the rib flanks on opposite sides of the rib.

5. A method for producing a V-ribbed belt as claimed in claim 1, wherein either the V-ribbed belt is produced in a molding method using a vulcanization mold, and a layer used for shaping the upper rib segments is formed from the non-conductive elastomer which is less viscous than the conductive elastomer used for the lower rib segments; or the V-ribbed belt is produced in a grinding method wherein elastomer material for the upper rib segments and lower rib segments are applied over one another in layers, and the ribs are formed by grinding.

6. The method claimed in claim 5 wherein the V-ribbed belt is produced in the grinding method.

7. The method of claim 5 wherein the V-ribbed belt is produced in the molding method.

8. The V-ribbed belt as claimed in claim 1 wherein the elastomer material is selected from the group comprising of rubbers and polyurethanes.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a three-rib ribbed belt in a schematic cross-sectional illustration, produced using an embossing method,

(2) FIG. 2 is a five-rib ribbed belt in a schematic cross-sectional illustration, produced using a grinding method.

(3) FIG. 1 shows a V-ribbed belt, designated as a whole by 10, having the belt height h and the rib spacing s, which has three ribs 1, and, below it, part of an associated multi-groove belt pulley 4 having the individual grooves 5 in a schematic illustration. The belt has multiple tension carriers 2, which are arranged close to the back 3 of the rib. When the ribs 1 of the ribbed belt 10 engage in the grooves 5 of the belt pulley 4, the two interact and the flanks 6 of the ribs 1 come into contact with the flanks 7 of the grooves 5. Each rib 1 of the ribbed belt has an upper rib segment 8, which comprises the rib tips 18, and a lower rib segment 9, which extends as far as the height of the rib valleys 19 at the foot of the rib. In the present exemplary embodiment, the lower rib segments 9, together with an adjacent zone 11 which surrounds the rib valleys 19, form a continuous area extending over the entire width of the belt, which consists entirely of the conductive elastomer material of the lower rib segments 9. The V-ribbed belt according to FIG. 1 is an embossed ribbed belt, in which the material boundary 12 between the conductive elastomer of the lower rib segments 9 and the non-conductive elastomer of the upper rib segments 8 is curved slightly in the direction of the rib tips 18. The height a of the lower rib segments 9 is determined by the height between the rib valley and the material boundary 12 at the rib flank 6. The height of the upper rib segments 8 is determined by the difference in height between the material boundary 12 at the rib flank 6 and the height of the rib tip 18. As a result of the special embossing method of the invention, the material boundary 12 is curved only slightly, so that the conductive material of the lower rib segments is exposed over an adequate area of the rib flank 6.

(4) By contrast, FIG. 2 shows a corresponding but five-rib ribbed belt 10 having a flat material boundary 12, which has been produced using a grinding method.

(5) The optimal height ratios a/(a+b) for this test configuration were determined experimentally. The test results are reproduced below. A minimal absolute value of at least 0.12 mm for the height of the lower rib segments a always resulted in an adequate conductivity/voltage derivative.

(6) Conductivity Test

(7) Ribbed belts with the PK profile, the belt bodies of which consisted of an EPDM, were investigated. The conductive rib mixture A contained highly conductive carbon black in a weight proportion between 10 and 25 per cent by weight and further smaller proportions of less-conductive carbon blacks. The non-conductive rib mixture B contained no carbon black, instead fillers based on silicic acid.

(8) Test Arrangement

(9) For the test arrangement, two belt pulleys (PK profile, external diameter equal to 50.00 mm) were mounted with a spacing of 10 cm from each other (mean spacing) on a non-electrically conductive plate such that a V-ribbed belt laid in the two belt pulleys was pressed into the belt pulleys by a pulling mass of 10 kg. For this purpose, the belt was fixed at one end and weighted at its other end with a weight of 10 kg. The contact between the two outer ribs of the belt and the associated profile of the belt pulley was insulated in order to ensure that, for this investigation, the contact between belt pulley and belt was produced only in the inner rib area. The conductivity from belt pulley to belt pulley was measured at a voltage of 500 V.

(10) The test results are shown in table 1:

(11) TABLE-US-00001 TABLE 1 Test results, exemplary profile PK Overall structure Conductivity height/belt Sample in % height (mm) a/(a + b) 1 100 5.090 0.084 2 100 5.070 0.122 3 100 5.040 0.100 4 100 5.060 0.117 5 100 5.040 0.122 6 100 5.020 0.071 7 100 5.040 0.122 8 100 5.060 0.060 Average 0.10 Conductivity is established approximately with an [a/(a + b)] ratio of 0.06 to 0.13. The minimum height a for the serviceable examples was from 0.12 mm.

LIST OF DESIGNATIONS

(12) 1 Rib 2 Tension carrier 3 Back of the belt 4 Belt pulley 5 Belt pulley groove 6 Rib flank 7 Groove flank 8 Upper rib segment 9 Lower rib segment 10 V-ribbed belt 11 Zone 12 Material boundary 18 Rib tip 19 Rib valley a Height of the lower rib segment b Height of the upper rib segment a+b Overall rib height h Belt height s Rib spacing