Torque transmitting devices such as clutches or brakes are used throughout the automotive industry. For example, vehicle transmissions employ multiple clutches to engage and disengage the gearsets of the transmission to provide forward and reverse gear ratios.
Generally, a clutch includes a friction plate and a reaction plate. The friction plate has a layer of friction material attached to the surface that opposes the reaction plate. Conventional friction materials are (a) cellulose/Kevlar/resin based materials; (b) sintered and/or metallic friction materials; and (c) woven carbon fiber friction materials.
Attempts have been made to use woven carbon fiber as a friction material for shifting/launch clutches. Carbon fiber material is typically more durable and has higher thermal conductivity as well as permeability in comparison with cellulose-based material, which favorably affect the friction characteristics of the clutch. The carbon fiber woven friction material is attached to the core steel plate by polymer-based adhesive. The adhesive has low thermal conductivity.
U.S. Pat. No. 6,360,864 ('864) issued Mar. 26, 2002 to Ford Global Technologies Inc, of Dearborn, Mich. attempts to decrease the instant temperature of the lubrication fluid in the clutch. The '864 patent increasing the area of contact between the fluid and steel reaction plates by providing either internal channels open for the fluid to flow through the reaction plate or having reaction plate split into two halves with a spacer between in an attempt to decrease the instant lubrication fluid temperature.
While the device of the '864 patent and other prior art devices work for their intended purpose improvements are still needed. For example, it would be desirable to provide a device that reduces the temperature of the lubricating fluid and addresses clutch overloading.