Drive belts including foamed undercord layers and methods of manufacturing the same

Patent metadata

Field	Value
Publication number	US-12320405-B2
Application number	US-202118270025-A
Country	US
Kind code	B2
Filing date	Dec 28, 2021
Priority date	Dec 28, 2020
Publication date	Jun 3, 2025
Grant date	Jun 3, 2025

Abstract

A drive belt includes an undercord layer having a first region proximate a backing layer surface of the undercord layer and a second region proximate the exterior surface of the undercord layer, the first region being foamed and the second region either being foamed to a lesser extent than the first region or not being foamed. The drive belt further includes a cover layer formed over the exterior surface of the undercord layer. Alternatively, the drive belt may be foamed throughout the undercord layer thickness, with a cover layer formed on the exterior surface of the undercord layer. The manufacturing process for making the foamed undercord layer can include incorporating a first quantity of foaming agent in a first sheet of undercord layer material and either a second quantity of foaming agent in a second sheet of undercord layer material, the second quantity being less than the first quantity, or including no foaming agent in the second sheet. The first sheet and second sheet are disposed in a mold, to which heat and pressure is applied to cure the sheets and foam the first sheet and the second sheet when the second sheet includes foaming agent. The mold includes an exterior portion that forms ridges in the exterior surface of the undercord layer and a cover layer disposed on the exterior surface of the undercord layer. The drive belt incorporating the undercord layer having a foamed first region may exhibit reduced bending stiffness and improved energy efficiency.

First claim

We claim:

1. A drive belt comprising: a foamed undercord layer having a thickness extending from a backing layer surface to an exterior surface opposite the backing layer surface, wherein the foamed undercord layer is foamed throughout the entire thickness of the foamed undercord layer; a plurality of void spaces located throughout the thickness of the foamed undercord layer, the plurality of voids being present throughout the thickness of the foamed undercord layer as a result of the foamed undercord layer being foamed; a plurality of cords fully embedded within the foamed undercord layer; and a cover layer formed over and abutting the exterior surface of the foamed undercord layer.

2. The drive belt of claim 1 , wherein the exterior surface of the foamed undercord layer is in the shape of a plurality of ridges and the cover layer conforms to the plurality of ridges.

3. The drive belt of claim 2 , wherein the plurality of ridges are aligned in parallel to the axis of rotation of the drive belt.

4. The drive belt of claim 2 , wherein the plurality of ridges are aligned perpendicular to the axis of rotation of the drive belt.

5. The drive belt of claim 1 , wherein the material of the foamed undercord layer directly abuts the plurality of void spaces.

6. The drive belt of claim 1 , further comprising: a backing layer, the backing layer abutting the backing layer surface of the foamed undercord; the plurality of cords being aligned perpendicular to the axis of rotation of the drive belt.

7. The drive belt of claim 1 , wherein the foamed undercord layer comprises an elastomer.

8. The drive belt of claim 1 , wherein the specific gravity of the foamed undercord layer is in the range of from 0.6 to 1.1 g/cm3.

9. The drive belt of claim 8 , wherein the specific gravity of the foamed undercord layer is in the range of from 0.8 to 1.0 g/cm3.

10. The drive belt of claim 1 , wherein the drive belt is a molded drive belt.

11. The drive belt of claim 1 , wherein the specific gravity of the foamed undercord layer is reduced by 10 to 40% as compared to an unfoamed undercord layer, and the bending stiffness of the drive belt decreases as the reduction in specific gravity of the foamed undercord layer is increased.

12. A method of manufacturing a drive belt, comprising: preparing a sheet of uncrosslinked undercord material, the sheet of uncrosslinked undercord material comprising an elastomer and a foaming agent; disposing the sheet of uncrosslinked undercord material in an interior portion of a mold in at least two layers; placing cord material in the mold between said at least two layers so that the cord will be fully embedded within the undercord material in the final belt; applying a cover layer on top of the sheet of uncrosslinked undercord material; closing the mold cavity by disposing an exterior portion of the mold on the interior portion, wherein the exterior portion of the mold includes a profile to form a plurality of ridges in the cover layer and sheet of uncrosslinked undercord material; applying heat and pressure to the mold to thereby cure and foam the sheet of uncrosslinked undercord material and form a sleeve of drive belt material, the foaming resulting in the creation of a plurality of void spaces throughout the thickness of the sleeve of belt material; removing the sleeve of belt material from the mold; and cutting the sleeve of belt material into individual belts.

13. The method of claim 12 , wherein the foaming agent has a decomposition temperature in the range of from 125 deg. C. and 175 deg. C.

14. The method of claim 12 , wherein the sheet of uncrosslinked undercord material comprises foaming agent at an amount of about 5.0 phr.

15. The method of claim 12 , wherein the profile of the exterior portion of the mold forms a plurality of ridges in the cover layer and sheet of uncrosslinked undercord material that are aligned perpendicular to the axis of rotation of the individual belts.

16. The method of claim 12 , wherein the profile of the exterior portion of the mold forms a plurality of ridges in the cover layer and sheet of uncrosslinked undercord material that are aligned parallel to the axis of rotation of the individual belts.

17. A drive belt comprising: a foamed undercord layer having a thickness extending from a backing layer surface to an exterior surface opposite the backing layer surface, wherein the foamed undercord layer is foamed throughout the entire thickness of the foamed undercord layer; a plurality of void spaces located throughout the thickness of the foamed undercord layer, the plurality of voids being present throughout the thickness of the foamed undercord layer as a result of the foamed undercord layer being foamed; a plurality of cords embedded within the foamed undercord layer; and a cover layer formed over and abutting the exterior surface of the foamed undercord layer; wherein the foamed undercord layer includes a first region extending from the backing layer surface to a boundary located intermediate the backing layer surface and the exterior surface, and a second region extending from the boundary to the exterior surface; wherein the first region is foamed to thereby include a plurality of void spaces located throughout the first region; and wherein the second region is either not foamed or foamed to a lesser degree than the first region.

18. The drive belt of claim 17 , wherein the second region is foamed to a lesser degree than the first region.

Assignees

• Gates Corp

Inventors

• Cheong Tae Hee
• Ochoa Charles F
• Gerring Douglas G
• Spring Kyle

Classifications

• F16G5/20

  with a contact surface of special shape, e.g. toothed · CPC title

• F16G5/06

  with reinforcement bonded by the rubber · CPC title

• F16G1/28

  with a contact surface of special shape, e.g. toothed · CPC title

• B32B2413/00

  Belts · CPC title

• B32B2250/24

  All layers being polymeric · CPC title