Patent ID: 11859369
Assignee: CATERPILLAR INC.
Field: Mechanical elements (Mechanical engineering)
Classification: CPC E  F | IPC E  F

Claim 0:
1. A lockup clutch system, comprising:
one or more clutch discs operational to, when engaged, couple rotational force from an input component to an output component, the one or more clutch discs, the input component, and the output component housed in a hydraulic fluid chamber of a torque converter;
a lockup piston housed in a piston housing of the torque converter, the lockup piston having a first end portion and a second end portion opposite of the first end portion, the lockup piston operational to:
engage with the one or more clutch discs when the lockup piston is biased, and
disengage from the one or more clutch discs when the lockup piston is unbiased;

a mechanical spring housed in the piston housing and coupled to the lockup piston at the second end portion of the lockup piston, the mechanical spring operational to bias the lockup piston to engage with the one or more clutch discs; and
a relief valve coupled to the hydraulic fluid chamber, the relief valve operational to, based on a state of a prime mover:
in an open position, relieve hydraulic pressure from hydraulic fluid in the hydraulic fluid chamber allowing the lockup piston to be biased so as to engage with the one or more clutch discs, and
in a closed position, allow the hydraulic pressure from the hydraulic fluid in the hydraulic fluid chamber to build up allowing the lockup piston to be unbiased so as to disengage from the one or more clutch discs,

wherein the relief valve is operational to be in the open position with the prime mover in an off state and with the prime mover in an on state and at a speed less than a preselected speed.