Fuel limiter for a uniflow-scavenged, two-stroke cycle, opposed-piston engine

Patent metadata

Field	Value
Publication number	US-9957901-B2
Application number	US-201615062868-A
Country	US
Kind code	B2
Filing date	Mar 7, 2016
Priority date	Jan 15, 2016
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

Control of fuel flow in a uniflow-scavenged, two-stroke cycle, opposed-piston engine includes limiting an amount of torque or fuel in response to a torque demand, based upon a comparison and a selection of fuel delivery options derived from a global airflow parameter and/or a trapped airflow parameter.

First claim

The invention claimed is:

1. A method for controlling operations of a uniflow-scavenged, two-stroke cycle, opposed-piston engine with a fuel source during demands for increased torque, comprising:
receiving a torque demand for a desired torque level of the engine;
determining a minimum value of a global air to fuel ratio (AFR) of the engine based on an engine speed and the desired torque level;
determining a measured value of global mass airflow based on air flow conditions of the engine;
determining a first maximum fuel quantity limit based on the minimum value of global AFR and the measured value of global mass airflow;
determining a minimum value of a trapped AFR of the engine based on the engine speed and the desired torque level;
determining a measured value of trapped mass airflow based on air flow conditions of the engine;
determining a second maximum fuel quantity limit based on the minimum value of trapped AFR and the measured value of trapped mass airflow; and,
limiting a quantity of fuel provided to the engine by:
selecting the minimum of the first maximum fuel quantity limit, the second fuel quantity limit, and a desired fuel quantity derived from the torque demand, followed by providing a limited fuel command to the fuel source according to the selection; or,
selecting the minimum of a torque based on the first maximum fuel quantity limit, a torque based on the second fuel quantity limit, and a desired torque derived from the torque demand, followed by providing a limited torque command to the fuel source according to the selection.

2. A method for limiting emissions of smoke by a uniflow-scavenged, two-stroke cycle, opposed-piston engine with a fuel source during demands for increased torque, comprising:
receiving a torque demand for a desired torque level of the engine;
determining a minimum value of a global smoke-limited air to fuel ratio (AFR) of the engine based on an engine speed and the desired torque level;
determining a measured value of global mass airflow based on air flow conditions of the engine;
determining a first maximum fuel quantity limit based on the minimum value of global smoke-limited AFR and the measured value of global mass airflow;
determining a minimum value of a trapped smoke-limited AFR of the engine based on the engine speed and the desired torque level;
determining a measured value of trapped mass airflow based on air flow conditions of the engine;
determining a second maximum fuel quantity limit based on the minimum value of trapped smoke-limited AFR and the measured value of trapped mass airflow; and,
limiting a quantity of fuel provided to the engine according to one of:
selecting the minimum of the first maximum fuel quantity limit, the second fuel quantity limit, and a desired fuel quantity derived from the torque demand, followed by providing a limited fuel command to the fuel source according to the selection; and
selecting the minimum of a torque based on the first maximum fuel quantity limit, a torque based on the second fuel quantity limit, and a desired torque derived from the torque demand, followed by providing a limited torque command to the fuel source according to the selection.

Assignees

• Achates Power Inc

Inventors

• Nagar Nishit
• Sharma Arunandan

Classifications

• F02D1/06 Primary

  by means dependent on pressure of engine working fluid (F02D1/08 takes precedence) · CPC title

• F02B25/08

  Engines with oppositely-moving reciprocating working pistons · CPC title

• F02M63/0225

  Fuel-injection apparatus having a common rail feeding several injectors (F02M63/0003 takes precedence); Means for varying pressure in common rails; Pumps feeding common rails · CPC title

• F02B2075/025

  two · CPC title

• F02B75/02

  Engines characterised by their cycles, e.g. six-stroke · CPC title