Method for determining the specific fuel consumption of an internal combustion engine and apparatus therefor

• US 5,006,994 A
• Filed: 04/19/1989
• Issued: 04/09/1991
• Est. Priority Date: 04/19/1988
• Status: Expired due to Fees

• Current Assignee: Wennstrom System AB
• Original Assignee: Ase Europe AB
• Inventors: Andersson, Kjell, Eriksson, Lennart
• Primary Examiner(s): Chin, Gary
• Application Number:
  US07/340,227
• Time in Patent Office: 720 Days
• Field of Search: 364/442, 73/113, 73/114
• US Class Current: 701/123
• CPC Class Codes: G01F 9/003 by measuring the weight

Abstract

The invention relates to a method and an apparatus for determining the specific fuel consumption of an internal combustion engine by measuring the change in weight of a pot containing fuel for consumption by the engine during a specific, selectable time. The apparatus for performing this method includes a data acquisition system equipped with a number of measuring points. Sensors at the measuring points feed, through the data acquisition system, signals representing the change in weight of the fuel pot, the speed of the engine and the torque of the engine into a computer. The computer is programmed for measuring at constant speed and constant torque, within selectable tolerances, and for measurement during a specific, selectable period of time. The method of the invention permits the use of statistical methods to assure reliable and accurate measurement results with the shortest possible measurement period, while providing high flexibility in interfacing with an operator or central computer system.

Claims

1. An apparatus for making a measurement of the specific fuel consumption of an internal combustion engine, the apparatus comprising:

a fuel pot connected to the internal combustion engine via fuel line means equipped with a valve;

a load cell having strain gauge sensor means on which said fuel pot is supported for measuring a change in weight of the pot during a preset, selectable time, resulting from the consumption of fuel by the engine during said time;

pulse transducer sensor means connected to the engine shaft for detecting the speed of the engine and providing a mean pulse rate indicative of said speed;

dynamometer sensor means connected to the engine shaft for measuring the engine torque and providing an analog input signal indicative of said torque;

a data acquisition system including signal conversion units for converting said analog input signal to frequency;

said data acquisition system further including a measuring unit for measuring said mean pulse rate for a selectable number of pulses;

a computer system for recording the data fed to the computer system through said data acquisition system from corresponding ones of said sensor means at each measuring point during the measuring period, for subsequent processing and evaluation of said measurement;

a counter means included in said computer system for accumulating the total number of revolution pulses indicative of engine speed during a preset selectable measuring period; and

,

means included in said computer system for disqualifying said measurement and starting a new measurement of the specific fuel consumption when said means pulse rate or said engine torque exceeds predetermined limits thereof.

2. A method for performing a measurement of a specific fuel consumption of an internal combustion engine, the method comprising the steps of:

obtaining respective signals from a plurality of sensors indicative of engine speed, engine torque and a change in weight of a pot containing fuel to be consumed by the engine;

passing said signals through a conditioning system and then to a computer;

continuously recording and storing in the computer, during a measuring period, the change in weight of the fuel pot and a number of revolutions of an engine shaft;

programming the computer for performing said measurement of the specific fuel consumption at constant engine speed and engine torque, within selectable, preset limits of tolerance of said engine speed and engine torque during said measuring period, which can be varied in small increments of 0.5 second to achieve maximum accuracy;

terminating said measurement and starting a new measurement of the specific fuel consumption when the engine speed or torque exceeds the preset limits during the measurement period;

calculating a linear fuel consumption curve as a function of time with said computer by a least-squares method utilizing said change in weight, as well as calculating a mean torque and a mean speed, after the measurement period and provided the engine speed and torque are constant within the preset limits;

disqualifying said measurement and starting a new measurement of the specific fuel consumption when said mean speed or said mean torque exceeds said limits of said tolerance, or if any stored tabulated value from said curve is greater than a predetermined value; and

,

calculating with the computer the fuel consumption per piston stroke based on the fuel consumption curve, the measuring period, the number of revolutions of the engine shaft during the measuring period and the number of cylinders, whereby a statistical certainty of the measurement of the specific fuel consumption can be specified.