Digital engine analyzer

• US 4,812,768 A
• Filed: 10/09/1987
• Issued: 03/14/1989
• Est. Priority Date: 08/23/1985
• Status: Expired due to Term

• Current Assignee: Snap-On Incorporated
• Original Assignee: Snap-On Tools Company LLC (Snap-On Incorporated)
• Inventors: Quinn, Robert O.
• Primary Examiner(s): Strecker, Gerard R.
• Assistant Examiner(s): Solis, Jose M.
• Application Number:
  US07/089,241
• Time in Patent Office: 522 Days
• Field of Search: 324/379, 324/384, 324/392, 73/117 X, 346/110 R, 364/431, 364/431.12, 340/798, 340/789
• US Class Current: 324/379
• CPC Class Codes: F02B 2075/027 four
• CPC Class Codes: F02P 17/00 Testing of ignition installations, e.g. in combination with adjusting testing fuel injection apparatus F02M65/00; testing ignition installations in general F23Q23/00; Testing of ignition timing in compression-ignition engines
• CPC Class Codes: G01R 13/345 for displaying sampled signals by using digital processors by intermediate A.D. and D.A. convertors (control circuits for CRT indicators)
• CPC Class Codes: G09G 1/162 for displaying digital inputs as analog magnitudes, e.g. curves, bar graphs, coordinate axes, singly or in combination with alpha-numeric characters cathode-ray oscilloscopes for displaying analog inputs, singly or in combination with alpha-numeric characters G01R13/20; television receiver circuitry for displaying supplementary, e.g. alpha-numeric, information H04N5/445

Abstract

A microprocessor controlled digital engine analyzer receives analog input signals from an engine being analyzed, engine parameter data entered via a keyboard, and function data, selecting one of several operating modes for the analyzer and which information is to be displayed, entered via the keyboard, and displays on a CRT screen the selected information such as cylinder firing order, RPM, Dwell, KV and DC volts, alphanumerically, information such as primary and secondary ignition and voltage, alternator and fuel injector information through the use of continuous waveform patterns, and additional information pertaining to Dwell, KV and Cylinder Shorting through the use of bar graphs. The waveform pattern data derived from the analog input signals is stored in a dual bank waveform memory and read out for display on the CRT screen under hardware control, and address data representing alphanumeric data and screen formats for the various operating modes to be displayed is stored in a dual bank display memory for application to a character generator, a bank switching arrangement being used for both the waveform memory and the display memory to enable the banks of each memory to be alternately written to and read from. A main microprocessor receives and processes analog input signals, other than the waveform pattern signals, and a display microprocessor receives numerical data from the main microprocessor and causes display of the numerical data on the CRT screen.

Claims

1. An engine analyzer for analyzing an internal combustion engine that produces engine signals, comprising a cathode ray tube for displaying a waveform corresponding to a selected engine signal which is continuously updated as and when the corresponding selected engine signal changes, means for selecting an RPM setpoint operating mode for the engine analyzer, means for selecting the magnitude of the RPM setpoint, means for determining the time between ignition signals and converting such time into engine speed in RPM, means for storing the engine speed in RPM thus calculated, and means for freezing the waveform displayed on said cathode ray tube to be that corresponding to the selected engine signal which was being produced when the engine speed reaches or exceeds the RPM setpoint.

2. The engine analyzer of claim 1, further comprising means for determining whether the engine speed in RPM is equal to or greater than the RPM setpoint.

3. The engine analyzer of claim 1, further comprising means for displaying an indication of the magnitude of the selected RPM setpoint on the screen of the cathode ray tube.

4. The engine analyzer according to claim 1, further comprising means for displaying the engine speed in RPM on the screen of the cathode ray tube.

5. An engine analyzer for analyzing an internal combustion engine that produces engine signals, comprising a cathode ray tube for displaying a waveform corresponding to a selected engine signal which is continuously updated as and when the corresponding electrical signal changes, a keyboard having a key thereon for selecting an RPM setpoint and additional keys for selecting the magnitude of the RPM setpoint microprocessor means coupled to said keyboard and adapted to process the activation of said keys said microprocessor operating under stored program for (a) determining the time between ignition signals and converting such time into engine speed in RPM, (b) storing the engine speed in RPM thus calculated, (c) determining whether the engine speed in RPM is equal to or greater than the RPM setpoint, and (d) if so, freezing the waveform on said cathode ray tube to be that corresponding to the electrical signals when the engine speed was at or about the RPM setpoint irrespective of subsequent changes in the electrical signals.

6. The engine analyzer of claim 5, wherein said microprocessor is further operated under stored program for (e) determining whether an RPM setpoint had previously been programmed into said microprocessor means via said keyboard and, if so, (f) removing such previous setpoint from said microprocessor means.