US Patent 7454902 Torque converter

A torque converter 1 is a device for transmitting torque by fluid, and includes a front cover 14, an impeller 18, a turbine 19, and a stator 20. The impeller 18, the turbine 19 and the stator 20 constitute a fluid operating chamber 6 having a torus shape. Flattening (L/D1) is less than or equal to 0.18, wherein D1 is an outer diameter of the fluid operating chamber 6 and L is the axial direction length of the fluid operating chamber 6. In the impeller shell 22, a surface 22a on which the impeller blades 23 are fixed has an impeller straight portion 22b showing a straight line in a cross section. In the turbine shell 25, a surface 25a on which the turbine blades 26 are fixed has a turbine straight portion 25b showing a straight line in a cross section.