US 7,223,202 B2 · Hydraulic circuit for torsional damper assembly of an electrically variable transmission

Abstract

The present invention relates to a torsional damper for an electrically variable transmission. The torsional damper is equipped with a hydraulically actuable lock-out clutch to selectively directly couple the engine to the input shaft of the transmission. The electric motors provided with the electrically variable transmission can serve to effectively cancel out engine compression pulses when the springs of the torsional damper are locked out. During higher speeds the centrifugal loading placed on oil in the torsional damper increases, which may cause the lock-out clutch to inappropriately engage. The present invention hydraulically balances the hydraulic actuator (or piston) driving the lock-out clutch to appropriately regulate lock-out clutch engagement.

Claims18

Dependent claims

An electrically variable transmission with at least one electric motor and a rotatable torsional damper assembly, the torsional damper assembly comprising:

a torsional spring operable to eliminate or reduce compression pulses and torsionals;
a clutch assembly having a hydraulically operable piston for selectively locking out said torsional spring;
at least one electric motor operable to cancel out the compression pulses when the torsional spring is locked out;
and
a hydraulic fluid applicable to opposing sides of said piston to sufficiently hydraulically balance said piston so as to prevent the clutch assembly from locking out said torsional spring at least partially in response to the rotational speed of said damper, thereby enabling said torsional spring to eliminate the torsionals.

2 more elements

A powertrain having an engine generating compression pulses and torsionals;

and an electrically variable transmission with at least one electric motor having a hydraulically actuable torsional damper assembly, comprising:
an engine side cover secured to the engine;
a damper flange commonly securable to said engine side cover and a damper hub;
wherein said damper hub is securable to an input shaft in said electrically variable transmission;
and wherein said damper flange has a damper spring enabling the torsional damper assembly to absorb such engine torsionals and compression pulses;
a transmission side cover secured to the engine side cover and configured to at least partially enclose said damper flange;
wherein said transmission side cover and said engine side cover further define a vessel enclosing said damper flange and said damper spring;
wherein said damper flange and said transmission side cover encloses selectively energizeable clutch plates for locking out said damper springs;
and
at least one electric motor in the electrically variable transmission to selectively cancel the engine compression pulses.

7 more elements

Dependencies are inferred from the claim text.

Hydraulic circuit for torsional damper assembly of an electrically variable transmission

Life of this patent

Hydraulic circuit for torsional damper assembly of an electrically variable transmission

Life of this patent

Abstract

Claims18