PARTIAL PREFILL OF CLUTCH FOR COAST DOWNSHIFT CONDITIONS IN A VEHICLE

摘要

A vehicle transmission includes a plurality of oncoming clutches that are hydraulically-actuated. A controller is operatively connected to the plurality of oncoming clutches. An algorithm stored on and executable by the controller causes the controller to determine if at least one predefined coast condition is met and identify the plurality of oncoming clutches configured to be engageable during a downshift event from an initial gear ratio to respective other gear ratios. The initial gear ratio is greater than each of the respective other gear ratios. The algorithm causes the controller to generate a first pressure command to at least partially pressurize a first one of the oncoming clutches to a first staging pressure (PS1) if the at least one predefined coast condition is met prior to the downshift event. The first staging pressure (PS1) is defined as a first return spring pressure (PR1) minus a first variable correction factor (CF1).

主权项

1. A transmission comprising:
a plurality of oncoming clutches, each of the plurality of oncoming clutches being hydraulically-actuated; a controller operatively connected to the plurality of oncoming clutches; an algorithm stored on and executable by the controller to cause the controller to:
determine if at least one predefined coast condition is met;identify the plurality of oncoming clutches configured to be engageable during a downshift event from an initial gear ratio to respective other gear ratios, the initial gear ratio being greater than each of the respective other gear ratios; andat least partially prefill a first one of the plurality of oncoming clutches by generating a first pressure command to at least partially pressurize the first one of the plurality of oncoming clutches to a first staging pressure (PS1) if the at least one predefined coast condition is met prior to the downshift event; and wherein the first staging pressure (PS1) is defined as a first return spring pressure (PR1) minus a first variable correction factor (CF1).