Cold engine testing

• US 5,780,730 A
• Filed: 07/08/1994
• Issued: 07/14/1998
• Est. Priority Date: 02/05/1991
• Status: Expired due to Fees

• Current Assignee: Assembly Technology & Test, Inc. (ATS Corp.)
• Original Assignee: Assembly Technology & Test, Inc. (ATS Corp.)
• Inventors: Scourtes, George, Yush, Elliott, Gagneur, John P.
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US08/271,904
• Time in Patent Office: 1,467 Days
• Field of Search: 73/115, 73/116, 73/117.2, 73/119 R
• US Class Current: 73/114.37
• CPC Class Codes: G01M 15/09 by monitoring pressure in fluid ducts, e.g. in lubrication or cooling parts
• CPC Class Codes: G01M 15/106 using pressure sensors

Abstract

An internal combustion engine is tested by measuring/recording the pressure of the intake gas as the engine is rotated without combustion.

Claims

1. A method of testing a internal combustion engine having an intake, plurality of cylinders and an operating cycle, said method comprising the steps of:

rotating said engine without internal combustion, through said operating cycle at a speed sufficient to cause vacuum variations in the intake related to each cylinder;

measuring pressure waveforms defined as the vacuum variations in the intake with respect to said engine operating cycle;

converting said pressure waveforms to digital data;

comparing characteristics of said digital data with characteristics of digital data for a normal engine; and

indicating as abnormal any engine whose digital data comparison with a normal engine is beyond tolerance limits, wherein said comparing step comprises comparing digital data characteristics of each cylinder with the corresponding digital data characteristics of each cylinder of a normal engine, and said indicating step comprises indicating as abnormal any cylinder whose digital data comparison with a corresponding cylinder of a normal engine is beyond tolerance limits, wherein said characteristic is amplitude of vacuum variations,

wherein excessive intake valve lash is a condition to be determined, said pressure waveform includes a relative maxima and a relative minima for each cylinder, said amplitude of vacuum variations comprises a difference between said relative maxima and said relative minima, and in said comparing step, an amplitude less than the amplitude of a normal engine is an indication of said excessive intake valve lash condition.

2. An apparatus for testing an internal combustion engine having an intake, a plurality of cylinders and an operating cycle, said apparatus comprising:

means for rotating said engine, without internal combustion, through said operating cycle at a speed sufficient to cause vacuum variations in the intake related to each cylinder;

means for measuring pressure waveforms defined as the vacuum variations in the intake with respect to said engine operating cycle;

means, responsive to said measuring means, for converting said pressure waveforms to digital data;

means, responsive to said converting means, for comparing characteristics of said digital data with characteristics of digital data for a normal engine; and

means, responsive to said comparing means, for indicating as abnormal any engine whose digital data comparison with a normal engine is beyond tolerance limits,

wherein said means for comparing comprises a means for comparing digital data characteristics of each cylinder with the corresponding digital data characteristics of each cylinder of a normal engine, and said means for indicating comprises a means for indicating as abnormal any cylinder whose digital data comparison with a corresponding cylinder of a normal engine is beyond tolerance limits,

wherein said characteristics comprise amplitude of vacuum variation for each cylinder,

wherein excessive intake valve lash is a condition to be determined, said pressure waveform includes a relative maxima and a relative minima for each cylinder, said amplitude of vacuum variations comprises a difference between said relative maxima and said relative minima, said means for comparing digital data comprises means for comparing the amplitude of vacuum variations, and said indicating means comprising a means, responsive to said comparing means determining an amplitude of vacuum variation less than the amplitude of vacuum variation of a normal engine, for providing an indication of said excessive intake valve lash condition.