Method and apparatus for testing internal combustion engines
First Claim
1. A method for testing relative compressions of cylinders of an internal combustion engine comprising the steps of:
- suppressing ignition of an internal combustion engine;
deriving a representation of current draw through a starter motor as said motor is used to turn over said engine with said ignition suppressed; and
eliminating distortions of compression relationships of cylinders of said engine represented by said representation of said current draw by compensating for a current/speed characteristic of said motor.
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Accused Products
Abstract
In a method and apparatus for the evaluation of a starter motor current or of a magnitude proportional to it for determining the relative compressions of the cylinders of an internal combustion engine, in order to eliminate the distortion of the compression relationships between the individual cylinders, account is taken of the current/speed characteristic of the starter motor. Using a direct current series motor as the starter, from the starter current there is derived a magnitude N proportional to the actual speed according to the relationship N =1/i+k*i where i is the motor current. The correction factor K serves to take account of the departure of the characteristic from a hyperbolic curve.
34 Citations
15 Claims
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1. A method for testing relative compressions of cylinders of an internal combustion engine comprising the steps of:
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suppressing ignition of an internal combustion engine; deriving a representation of current draw through a starter motor as said motor is used to turn over said engine with said ignition suppressed; and eliminating distortions of compression relationships of cylinders of said engine represented by said representation of said current draw by compensating for a current/speed characteristic of said motor. - View Dependent Claims (2, 3)
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4. An apparatus for testing relative compressions of cylinders of an internal combustion engine comprising:
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means for deriving a signal representative of a current draw through a starter motor used to turn over an internal combustion engine with said engine'"'"'s ignition being suppressed; means for interrupting said ignition to thereby suppress ignition of said engine; means for evaluating said signal coupled to said means deriving said signal; means for compensating for a current/speed characteristic of said motor; means for deriving a signal representative of relative compressions of cylinders of said engine; and means for identifying compression representations for each cylinder of said engine and matching said compression representations to respective cylinders. - View Dependent Claims (5, 6, 7, 8, 9)
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10. An apparatus for testing relative compressions of cylinders of an internal combustion engine comprising:
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means for deriving a signal representative of a current draw through a starter motor used to turn over an internal combustion engine with said engine'"'"'s ignition being suppressed; means for evaluating said signal coupled to said means deriving said signal; means for compensating for a current/speed characteristic of said motor; means for deriving a signal representative of relative compressions of cylinders of said engine; and means for identifying compression representations for each cylinder of said engine and matching said compression representations to respective cylinders. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification