System and method for mode selection in a variable displacement engine

• US 5,970,943 A
• Filed: 03/07/1995
• Issued: 10/26/1999
• Est. Priority Date: 03/07/1995
• Status: Expired due to Fees

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Robichaux, Jerry D., Hieb, Bradley J.
• Primary Examiner(s): Kamen, Noah P.
• Application Number:
  US08/400,066
• Time in Patent Office: 1,694 Days
• Field of Search: 123/198 F
• US Class Current: 123/198.00F
• CPC Class Codes: F02D 13/06 Cutting-out cylinders
• CPC Class Codes: F02D 17/02 Cutting-out cutting-out engines in multiple engine arrangements F02D25/04
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A system and method for selecting the operating mode of a variable displacement engine includes a controller with a stored engine map, an engine speed sensor, and an inferred desired fractional manifold vacuum which would be required for the engine to operate on a fractional number of cylinders, given the driver'"'"'s current torque requirements, a specific emissions calibration, and environmental conditions, deriving this inferred desired fractional manifold vacuum from stored information and assorted engine sensor input. The system compares its inferred desired fractional manifold vacuum and current engine speed to one or more stored maps of inferred desired fractional manifold vacuum versus engine speed in order to decide which operating mode should be selected.

Claims

1. A method of determining a number of cylinders to operate in a variable displacement engine having a desired torque and a specific emissions calibration, comprising the steps of:

sensing a present engine speed of the variable displacement engine;

inferring a desired fractional manifold vacuum required to accommodate the desired torque and the specific emissions calibration for the variable displacement engine operating on a fractional number of cylinders;

detecting whether the variable displacement engine is operating on a fractional number of cylinders;

selecting a limit function according to the results of said detecting step, the limit function utilizing the present engine speed and the inferred desired fractional manifold vacuum;

determining an adjustment to the limit function and adjusting the limit function by said adjustment while operating the variable displacement engine;

evaluating the limit function at the present engine speed and the inferred desired fractional manifold vacuum to generate a limit function result; and

generating an operating mode signal to the variable displacement engine according to the limit function result.