US 5,665,023 A · Failsafe control apparatus for belt-type continuously variable transmission

Abstract

A control apparatus for a belt-type continuously variable transmission that has a drive pulley, a driven pulley, a V-belt trained around the drive and driven pulleys, a drive cylinder for varying the pulley width of the drive pulley, and a driven cylinder for varying the pulley width the said driven pulley. A pressure regulator valve produces pulley control pressures supplied to the drive and driven cylinders and a shift valve distributes the pulley control pressures to the drive and driven cylinders for varying the widths of the drive and driven pulleys for speed ratio control. An electric shift control normally controls the shift valve by electric power supplied to solenoid valves but the electric shift control causes the pressures in both the drive cylinder and said driven cylinder to be equal when the electric power is lost.

Claims21

Dependent claims

A control apparatus for a belt-type continuously variable transmission having a drive pulley, a driven pulley, a V-belt trained around said drive and driven pulleys, a drive cylinder for varying a pulley width of said drive pulley, and a driven cylinder for varying a pulley width of said driven pulley, comprising:

pressure regulator valve means for producing pulley control pressures to be supplied to said drive and driven cylinders;
a shift valve for distributing said pulley control pressure to said drive and driven cylinders to regulate drive and driven cylinder pressures in said drive and driven cylinders for a speed ratio control;
electric shift control means for operationally controlling said shift valve by means of an electric power;
and
means for allowing said electric shift control means to move said shift valve to a first position at which a common pressure is supplied to both said drive cylinder and said driven cylinder when said electric power is lost.

2 more elements

means for producing and supplying separate pulley control pressures to said drive cylinder and said driven cylinder;
said means being operationally controlled by an electric power control;
and
said means including means for causing said pulley control pressures in both said drive cylinder and said driven cylinder to be equal when said electric power control is lost.

1 more element

Dependencies are inferred from the claim text.

Failsafe control apparatus for belt-type continuously variable transmission

Life of this patent

Failsafe control apparatus for belt-type continuously variable transmission

Life of this patent

Abstract

Claims21