Patent ID: 7686715
Filing Date: 2010-03-30
Classification: F16H

Abstract:
1. A variator for a belt continuously variable transmission (CVT), the variator comprising: a driven hybrid clamping mechanism (HCM) and a driving HCM coupled via a v-belt; each HCM comprising: a pulley having adjustable belt-engagement surfaces to allow for a variable effective diameter of the belt when about the pulley; a clamping spring disposed to bias the belt-engagement surfaces closer together to exert a clamping force on the belt; a first hydraulic drive disposed to assist the clamping force of the clamping spring, the first hydraulic drive including a moveable portion, a moveable housing portion, a first stationary housing portion and a second stationary housing portion; and a second hydraulic drive disposed to oppose the clamping force of the clamping spring, the second hydraulic drive including the moveable housing portion, the first stationary housing portion and a third stationary housing portion; wherein the driven pulley exerts a total clamping force at the belt in response to the clamping spring, the first hydraulic drive, the second hydraulic drive, or any one of the foregoing, of the driven HCM; wherein the driving HCM further comprises a third hydraulic drive disposed to assist the clamping force of the driving HCM clamping spring, and the driving HCM second hydraulic drive is disposed between the first and the third hydraulic drives of the driving HCM; wherein the clamping spring of the driving HCM includes a first clamping spring disposed at the first hydraulic drive, and a second clamping spring disposed at the third hydraulic drive; wherein the driving pulley exerts a total clamping force at the belt in response to the first clamping spring, the second clamping spring, the first hydraulic drive, the second hydraulic drive, the third hydraulic drive, or any combination of the foregoing, of the driving HCM; and wherein the driven HCM first hydraulic drive provides equal to or greater than about 50% of the total clamping force at the belt at the driven pulley, and the driving HCM first hydraulic drive provides equal to or greater than about 50% of the total clamping force at the belt at the driving pulley.