US4126037A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compression test using battery voltage waveform during cranking
Assignee: RCA Corp
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Filing: 1977-11-17
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Granted: 1978-11-21
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Expires: 1997-11-17
Abstract
Abstract The compression in the cylinders of an internal combustion engine is tested by analyzing the battery voltage waveform when the engine is cranked by the starter motor with ignition or fuel inhibited. The detected voltage waveform is amplified in a manner to emphasize the a-c component having cycles between positive voltage peaks, each cycle having a negative voltage peak due to a compression stroke. A missing negative voltage peak indicates a very low compression in one cylinder. The voltage cycles are integrated and the integrals are compared to detect compression imbalance. The base level of each integration is made equal to the level of an adjacent positive voltage peak.
Inventors
- 👤 Richard E. Hanson
- 👤 Ronald E. Tetrev
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:34
CPC Classifications
G; G01; G01L; G01L23/00; G01L23/08; G01L23/085
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
100 words
Compression testing apparatus for testing an internal combustion engine, comprising means for detecting the battery voltage waveform when the engine is cranked with the ignition or fuel inhibited, said voltage waveform having cycles between positive voltage peaks, amplifier means for amplifying the detected voltage waveform relative to a reference voltage, means to adjust said reference voltage to a value approximating the direct-current component of said voltage waveform, and means to increase the gain of said amplifier, whereby to increase the amplification of the alternating-current component of said voltage waveform, and means to compare the cycles of said amplified voltage waveform.
Claim 2
Dependent Claim
100 words
Compression testing apparatus for testing an internal combustion engine, comprising means for detecting the battery voltage waveform when the engine is cranked with the ignition or fuel inhibited, said voltage waveform having cycles between positive voltage peaks, amplifier means for amplifying the detected voltage waveform relative to a reference voltage, means to adjust said reference voltage to a value approximating the direct-current component of said voltage waveform, and means to increase the gain of said amplifier, whereby to increase the amplification of the alternating-current component of said voltage waveform, and means to compare the cycles of said amplified voltage waveform.
Claim 3
Dependent Claim
132 words
Apparatus to detect unsatisfactory compression in individual cylinders of an internal combustion engine having compression strokes, comprising means for detecting the battery voltage waveform when the engine is cranked with the ignition or fuel inhibited, said voltage waveform having cycles between positive voltage peaks, each cycle having a negative voltage peak due to compression strokes in at least one of the cylinders of the engine, means for generating cycle period signals representing the time periods between successive positive voltage peaks of said waveforms, and means for comparing each said cycle period signal with the preceding cycle period signal and producing a FAIL signal if the present signal is more than twice that of the preceding signal, whereby a FAIL signal is generated as the result of very low compression in one cylinder.
Claim 4
Dependent Claim
132 words
Apparatus to detect unsatisfactory compression in individual cylinders of an internal combustion engine having compression strokes, comprising means for detecting the battery voltage waveform when the engine is cranked with the ignition or fuel inhibited, said voltage waveform having cycles between positive voltage peaks, each cycle having a negative voltage peak due to compression strokes in at least one of the cylinders of the engine, means for generating cycle period signals representing the time periods between successive positive voltage peaks of said waveforms, and means for comparing each said cycle period signal with the preceding cycle period signal and producing a FAIL signal if the present signal is more than twice that of the preceding signal, whereby a FAIL signal is generated as the result of very low compression in one cylinder.
Claim 5
Dependent Claim
31 words
Apparatus according to claim 2 wherein said means for comparing cycle period signals also produces a FAIL signal if the present signal is less than one-half that of the preceding signal.
Claim 6
Dependent Claim
58 words
Apparatus according to claim 2, and in addition, integrator means for integrating the area of each negative-going waveform cycle to produce corresponding integration signals, and means for subtracting the amplitude of the smallest integration signal from the amplitude of the largest integration signal and producing a difference signal which is a measure of compression imbalance in the engine.
Claim 7
Dependent Claim
24 words
Apparatus according to claim 4, and in addition, means for setting the base level of an adjacent positive voltage peak of the voltage waveform.
Claim 8
Dependent Claim
28 words
Apparatus according to claim 4 wherein the base level of the integrator means is set at the level of the highest of the two adjacent positive voltage peaks.
Claim 9
Dependent Claim
54 words
Apparatus according to claim 2 wherein said means for detecting the starter motor voltage waveform includes means for amplifying the detected voltage waveform relative to a reference voltage, means to adjust said reference voltage to a value approximating the direct-current component of said voltage waveform, and means to increase the gain of said amplifier.
Claim 10
Independent Claim
94 words
The method of performing a compression test of an internal combustion engine, comprising the steps of detecting the battery voltage waveform when the engine is cranked with the ignition or fuel inhibited, said voltage waveform having cycles between positive voltage peaks, amplifying the detected voltage waveform relative to a reference voltage, adjusting said reference voltage to a value approximating the direct-current component of said voltage waveform, increasing the gain of said amplifier, whereby to increase the amplification of the alternating-current component of said voltage waveform, and comparing the cycles of said amplified voltage waveform.
Claim 11
Independent Claim
94 words
The method of performing a compression test of an internal combustion engine, comprising the steps of detecting the battery voltage waveform when the engine is cranked with the ignition or fuel inhibited, said voltage waveform having cycles between positive voltage peaks, amplifying the detected voltage waveform relative to a reference voltage, adjusting said reference voltage to a value approximating the direct-current component of said voltage waveform, increasing the gain of said amplifier, whereby to increase the amplification of the alternating-current component of said voltage waveform, and comparing the cycles of said amplified voltage waveform.
Claim 12
Independent Claim
114 words
The method of detecting unsatisfactory compression in individual cylinders of an internal combustion engine having compression strokes, comprising the steps of detecting the battery voltage waveform when the engine is cranked with the ignition or fuel inhibited, said voltage waveform having cycles between positive voltage peaks, each cycle having a negative voltage peak due to compression strokes in at least one of the cylinders of the engine, generating cycle period signals representing the time periods between successive positive voltage peaks of said waveform, and comparing each said cycle period signal with the preceding cycle period signal and producing a FAIL signal if the present signal is more than twice, that of the preceding signal.
Claim 13
Independent Claim
114 words
The method of detecting unsatisfactory compression in individual cylinders of an internal combustion engine having compression strokes, comprising the steps of detecting the battery voltage waveform when the engine is cranked with the ignition or fuel inhibited, said voltage waveform having cycles between positive voltage peaks, each cycle having a negative voltage peak due to compression strokes in at least one of the cylinders of the engine, generating cycle period signals representing the time periods between successive positive voltage peaks of said waveform, and comparing each said cycle period signal with the preceding cycle period signal and producing a FAIL signal if the present signal is more than twice, that of the preceding signal.
Claim 14
Dependent Claim
28 words
The method according to claim 9 and the additional step of producing a FAIL signal if the present signal is less than one-half that of the preceding signal.
Claim 15
Dependent Claim
57 words
The method according to claim 9 and in addition the steps of integrating the area of each negative-going waveform cycle to produce corresponding integration signals, and subtracting the amplitude of the smallest integration signal from the amplitude of the largest integration signal and producing a difference signal which is a measure of compression imbalance in the engine.
Claim 16
Dependent Claim
32 words
The method according to claim 11, and in addition the step of setting the base level of said integration at the level of an adjacent positive voltage peak of the voltage waveform.
Claim 17
Dependent Claim
32 words
The method according to claim 11, and in addition the step of setting the base level of said integration at the level of the highest of the two adjacent positive voltage peaks.
Claim 18
Dependent Claim
51 words
The method according to claim 9 wherein said step of detecting the battery voltage waveform includes the steps of amplifying the detected voltage waveform relative to a reference voltage, adjusting said reference voltage to a value approximating the direct-current component of said voltage waveform, and increasing the gain of said amplifier.
Claim 19
Independent Claim
158 words
A method of testing the compression of the cylinders of an internal combustion engine of the type in which pairs of cylinders are operated in synchronism and which is started by a battery comprising the steps of: producing a waveform representing the battery voltage when the engine is cranked but when the fuel is not permitted to ignite and with the waveform compensated to remove the effect of decreasing battery voltage during successive compression cycles, said waveform including successive peaks during each period, each such peak representing a different pair of cylinders; integrating the area under each peak of said waveform for N successive periods, where N is an integer greater than 1; selecting from the integrals for each pair of cylinders, the integral of greatest value for each pair of cylinders; and comparing the selected integral of greatest value with the selected integral of lowest value to obtain a measure of the compression balance of the engine.
Claim 20
Independent Claim
158 words
A method of testing the compression of the cylinders of an internal combustion engine of the type in which pairs of cylinders are operated in synchronism and which is started by a battery comprising the steps of: producing a waveform representing the battery voltage when the engine is cranked but when the fuel is not permitted to ignite and with the waveform compensated to remove the effect of decreasing battery voltage during successive compression cycles, said waveform including successive peaks during each period, each such peak representing a different pair of cylinders; integrating the area under each peak of said waveform for N successive periods, where N is an integer greater than 1; selecting from the integrals for each pair of cylinders, the integral of greatest value for each pair of cylinders; and comparing the selected integral of greatest value with the selected integral of lowest value to obtain a measure of the compression balance of the engine.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-11-20 | 1982-05-22 | 1982-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-11-20 | 1986-05-22 | 1986-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-11-20 | 1990-05-22 | 1990-11-21 | $7700.00 | Window Closed / Lapsed |