Engine test and display apparatus

• US 4,125,894 A
• Filed: 05/18/1977
• Issued: 11/14/1978
• Est. Priority Date: 12/16/1975
• Status: Expired due to Term

• Current Assignee: Snap-On Tools Company LLC (Snap-On Incorporated)
• Original Assignee: Sun Electric Corp (Snap-On Incorporated)
• Inventors: Kreft, Keith A., Karlin, Richard A., Trussell, Gerald C., Comiskey, Gary F., Caruth, James R., Arnston, Robert W., Shepardson, Robert C., Perna, Frank, Damm, Arthur, Sienaski, Dennis C., D'Souza, Alfred C., Van Ermen, Gary L., Borgens, Frederick R., Jankowski, Thomas M., Leung, Yam C., Cashel, Aloysius T.
• Primary Examiner(s): Morrison, Malcolm A.
• Assistant Examiner(s): Krass, Errol A.
• Application Number:
  US05/798,181
• Time in Patent Office: 545 Days
• Field of Search: 364/424, 364/425, 364/442, 364/551, 73/112, 73/116, 73/117.2, 73/117.3, 73/118, 123/32 EA, 340/146.2, 324/15, 324/16 R, 324/16 S
• US Class Current: 701/123
• CPC Class Codes: F02B 2075/025 two
• 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: F02P 17/08 using a cathode-ray oscilloscope F02P17/06 takes precedence
• CPC Class Codes: G01D 1/12 giving a maximum or minimum of a value
• CPC Class Codes: G01M 15/042 by monitoring a single specific parameter not covered by groups G01M15/06 - G01M15/12
• CPC Class Codes: G01M 15/044 by monitoring power, e.g. by operating the engine with one of the ignitions interrupted; by using acceleration tests
• CPC Class Codes: G01M 15/05 by combined monitoring of two or more different engine parameters
• CPC Class Codes: G01M 15/102 by monitoring exhaust gases
• CPC Class Codes: G01P 21/02 of speedometers
• CPC Class Codes: G06F 11/0763 by bit configuration check, e.g. of formats or tags
• CPC Class Codes: G10D 1/12 Zithers, e.g. autoharps

Abstract

The disclosure describes an improved automated engine diagnosing device employing a digital data processor computer and a cathode ray tube display monitor which displays engine parameter (i.e., condition) values in alphabetic, numeric, and graphical form. Some data is accumulated from the engine by means of direct digital measurements, whereas other data is obtained from the engine by an analog-to-digital converter. The data is then processed by the computer and displayed on the cathode ray tube display monitor.

Claims

1. Improved apparatus for measuring the dwell of an ignition system of an internal combustion engine having a predetermined number of cylinders and fuel ignitors, said ignition system comprising a switch periodically opened and closed in synchronism with the rotation of the engine in order to create time-spaced ignition pulses for firing the ignitors, the switch being closed for a dwell time period and being open for a firing time period in order to create such ignition pulse, said apparatus comprising:

clock means for producing clock pulses at a predetermined rate;

first counter means for counting the clock pulses;

second counter means for counting the clock pulses;

first gate means for transmitting clock pulses to the first counter means in response to a first one of the ignition pulses and for preventing the transmission of clock pulses to the first counter means in response to a second one of the ignition pulses;

second gate means for transmitting clock pulses to the second counter means only during the duration of one or more dwell time periods which occur between the first ignition pulse and the second ignition pulse;

processor means for producing a digital dwell signal having a value proportional to the count of the second counter means divided by the count of the first counter means; and

display means for displaying a swell number having a value proportional to the value of the dwell signal.

2. Apparatus, as claimed in claim 1, and further comprising means for electrically coupling the first gate means to a single one of the ignitors, whereby the first one and second one of the ignition pulses are successive ignition pulses transmitted to said single one of the ignitors.

3. Apparatus, as claimed in claim 2, wherein the second gate means comprises means for transmitting clock pulses to the second counter means during only a single dwell time period which occurs between the first and second ignition pulses and wherein the apparatus further comprises means for selecting the dwell time period during which the clock pulses are transmitted to the second counter means, whereby the dwell number associated with a preselected ignitor is displayed on the display means.

4. Apparatus, as claimed in claim 2, wherein the second gate means comprises means for transmitting clock pulses to the second counter means during each dwell time period occurring between the first ignition pulse and the second ignition pulse, whereby the dwell number displayed on the display means represents the averge dwell time of the ignition system.

5. Apparatus, as claimed in claim 4, wherein the processor means further comprises means for dividing the count of the second counter means by the predetermined number of chambers.

6. Apparatus, as claimed in claim 1, wherein the processor means comprises a digital computer.

7. Apparatus, as claimed in claim 1, wherein the display means comprises:

a character generator; and

a cathode ray tube monitor.

8. Improved apparatus for measuring the timing of a chamber of an internal combustion engine having a predetermined number of chambers and including an ignition system having fuel ignitors, said ignition system comprising a switch periodically opened and closed in synchronism with the rotation of the engine in order to create time-spaced ignition pulses for firing the ignitors, the time duration between successive closures of the switch defining a chamber timing period, said apparatus comprising:

clock means for producing clock pulses at a predetermined rate;

first counter means for counting the clock pulses;

second counter means for counting the clock pulses;

first gate means for transmitting clock pulses to the first counter means in response to a first one of the ignition pulses and for preventing the transmission of clock pulses to the first counter means in response to a second one of the ignition pulses;

second gate means for transmitting clock pulses to the second counter means only during one or more selected chamber timing periods which occur between the first ignition pulse and the second ignition pulse;

means for modifying the one or more selected chamber timing periods during which clock pulses are transmitted to the second counter means;

processor means for producing a digital chamber timing signal having a value proportional to the count of the second counter means divided by the count of the first counter means; and

display means for displaying a chamber timing number having a value proportional to the value of the chamber timing signal, whereby the chamber timing number displayed on the display means is associated with one or more preselected chambers and ignitors.

9. Apparatus, as claimed in claim 8, and further comprising means for electrically coupling the first gate means to a single one of the ignitors, whereby the first one and second one of the ignition pulses are successive ignition pulses transmitted to said single one of the ignitors.

10. Apparatus, as claimed in claim 9, wherein the processor means comprises means for individually selecting each of the chamber timing periods within an engine cycle and for summing the individual resulting counts of the second counter means, whereby the chamber timing number displayed on the display means represents the average chamber timing of the ignition system.

11. Apparatus, as claimed in claim 10, wherein the processor means comprises means for dividing the summed individual counts of the second counter means by the predetermined number of chambers.

12. Apparatus, as claimed in claim 8, wherein the processor means comprises a digital computer.

13. Apparatus, as claimed in claim 8, wherein the display means comprises:

a character generator; and

a cathode ray tube monitor.

14. Apparatus for analyzing an internal combustion engine comprising:

means coupled to the engine for generating a digital measurement signal corresponding to a predetermined engine condition;

display means having a face for displaying at a first location on the face a first character group of alphabetic letters indicative of the unit in which the predetermined engine condition is measured and for displaying at a second location on the face a first number indicative of the value of the engine condition being measured;

memory means for storing a first character code signal corresponding to the first character group, a first display address signal corresponding to the first location, and a second display address signal corresponding to the second location;

display controller means for enabling the display means to display the first character group at the first location in response to the first character code signal and the first display address signal and for enabling the display means to display the first number at the second location in response to the second display address signal and a first digital display signal corresponding to the value of said engine condition in the units indicated by the first character group; and

processor means for altering the value of the digital measurement signal to produce the first digital display signal, transmitting the first digital display signal and second display address signal to the display controller means and for transmitting the first character code signal and first display address signal to the display controller means, at least said first digital display signal being produced and transmitted to the display controller means in less than 8 seconds from the time the engine condition occurs, whereby the units and value of the engine condition are displayed in digital form on the face of the display means in real time, so that an operator of the apparatus can determine the value of the engine condition as the engine is operating.

15. Apparatus, as claimed in claim 14, wherein the means coupled to the engine for generating comprises:

analog measuring means for generating an analog measuring signal corresponding to the engine condition being measured; and

converter means for converting the analog measuring signal to the digital measurement signal.

16. Apparatus, as claimed in claim 14, wherein the memory means comprises a digital read-only memory for storing an application control program.

17. Apparatus, as claimed in claim 14, wherein the processor means comprises:

an arithmetic unit;

a control unit;

means for transmitting data from the memory means to the display controller means; and

means for enabling the temporary storage of the first digital display signal before transmitting the first digital display signal to the display controller means.

18. Apparatus, as claimed in claim 14, wherein the display controller means comprises a buffer memory for storing the first character code signal while the first character group is displayed on the face of the display means.

19. Apparatus, as claimed in claim 14, wherein the display means comprises a cathode ray tube.

20. Apparatus, as claimed in claim 19, wherein the cathode ray tube comprises an electron gun for scanning the face with a predetermined number of scan lines at a predetermined rate, and wherein the display controller means comprises:

clock means for generating clock pulses at a predetermined rate;

row counter means for counting clock pulses so that each scan is divided into a predetermined number of rows; and

line counter means for counting the scans so that the face of the cathode ray tube means is divided into a predetermined number of lines for displaying characters.

21. Apparatus, as claimed in claim 14, and further comprising panel switch means for selecting the type of engine condition to be displayed, wherein the processor means comprises means for periodically interrogating the panel switch means independent of the selection state of the panel switch means, whereby a change in the type of engine condition selected on the panel switch means results in a substantially instantaneous change of the unit and value displayed on the display means.

22. Apparatus, as claimed in claim 21, wherein the processor means comprises executive means for interrogating the panel switch means before the first digital display signal and second display address signal are transmitted to the display controller means.

23. Apparatus, as claimed in claim 14, wherein the processor means comprises means for transmitting the first character code signal and the first display address signal in parallel form to the display controller means, whereby the display of engine parameters in real time is facilitated.

24. Apparatus, as claimed in claim 23, wherein the first character code signal and the first display address signal are transmitted to the display controller means in a single word.

25. Apparatus, as claimed in claim 14, wherein the memory means comprises means for storing an instruction signal corresponding to an alphabetic instruction to be displayed on the display means, wherein the processor means comprises means for transmitting the instruction signal to the display controller means, and wherein the display controller means comprises means for displaying the alphabetic instruction simultaneously with the first character group and the first number on the display means.

26. Apparatus for analyzing an internal combustion engine comprising:

means coupled to the engine for generating a digital measurement signal corresponding to a predetermined engine condition;

display means having a face for displaying at a first location on the face a first character group of alphabetic letters indicative of the unit in which the predetermined engine condition is measured, for displaying at a second location on the face a first number indicative of the value of the engine condition being measured at a first point in time, and for displaying at a third location on the face a second number indicative of the value of the engine condition being measured at a second point in time;

memory means for storing a first character code signal corresponding to the first character group, a first display address signal corresponding to the first location, a second display address signal corresponding to the second location, and a third display address signal corresponding to the third location;

display controller means for enabling the display means to display the first character group at the first location in response to the first character code signal and the first display address signal, for enabling the display means to display the first number at the second location in response to the second display address signal and a first digital display signal corresponding to the value of said engine condition in the units indicated by the first character group at the first point in time, and for enabling the display means to display the second number at the third location in response to the third display address signal and a second digital display signal corresponding to the value of said engine condition in the units indicated by the first character group at the second point in time;

processor means for transmitting the first character code signal and first display address signal to the display controller means, operative in a first mode at the first point in time for altering the value of the digital measurement signal to produce the first digital display signal and for transmitting the first digital display signal and second display address signal to the display controller means, and operative in a second mode at the second point in time for altering the value of the digital measurement signal to produce the second digital display signal and for transmitting the second digital display signal and third display address signal to the display controller means; and

selection means for operating the processor means in the first mode whereby the first number is displayed on the face of the display means so that the value of the engine condition at the first point in time can be observed, and for operating the processor means in the second mode whereby the second number is displayed on the face of the display means so that the value of the engine condition at the second point in time can be observed.

27. Apparatus, as claimed in claim 26, wherein the selection means comprises a transmitter located remotely from the processor means for selectively determining the operating mode of the processor means.

28. Apparatus, as claimed in claim 26, wherein the means coupled to the engine for generating comprises:

analog measuring means for generating an analog measuring signal corresponding to the engine condition being measured; and

converter means for converting the analog measuring signal to the digital measurement signal.

29. Apparatus, as claimed in claim 26, wherein the memory means comprises a digital memory.

30. Apparatus, as claimed in claim 26, wherein the processor means comprises:

an arithmetic unit;

a control unit;

means for transmitting data from the memory means to the display controller means; and

means for enabling the temporary storage of the first digital display signal before transmitting the first digital display signal to the display controller means.

31. Apparatus, as claimed in claim 26, wherein the display controller means comprises a buffer memory for storing the first character code signal while the first character group is displayed on the face of the display means.

32. Apparatus, as claimed in claim 26, wherein the display means comprises a cathode ray tube.

33. Apparatus, as claimed in claim 31, wherein the cathode ray tube comprises an electron gun for scanning the face with a predetermined number of scan lines at a predetermined rate, and wherein the display controller means comprises:

clock means for generating clock pulses at a predetermined rate;

row counter means for counting clock pulses so that each scan is divided into a predetermined number of rows; and

line counter means for counting the scans so that the face of the cathode ray tube is divided into a predetermined number of lines for displaying characters.

34. Apparatus, as claimed in claim 26, wherein the memory means comprises means for storing an instruction signal corresponding to an alphabetic instruction to be displayed on the display means, wherein the processor means comprises means for transmitting the instruction signal to the display controller means, and wherein the display controller means comprises means for displaying the alphabetic instruction simultaneously with the first character group, the first number and the second number on the display means.

35. Apparatus for automatically analyzing an internal combustion engine during a first operating state and a second operating state comprising:

means coupled to the engine for generating first and second digital measurement signals corresponding to first and second engine conditions, respectively, which are useful for analyzing the first operating state and for generating third and fourth digital measurement signals corresponding to third and fourth engine conditions, respectively, which are useful for analyzing the second operating state;

display means having a face for displaying simultaneously during a first time period first and second numbers corresponding to the first and second digital measurement signals, respectively, a first character group of alphabetical letters indicative of the units of the first number and a second character group of alphabetical letters indicative of the units of the second number, and for displaying simultaneously during a second time period, third and fourth numbers corresponding to the third and fourth digital measurement signals, respectively, a third character group of alphabetical letters indicative of the units of the third number and a fourth character group of alphabetical letters indicative of the units of the fourth number;

memory means for storing first character code signals corresponding to the first character group, second character code signals corresponding to the second character group, third character code signals corresponding to the third character group and fourth character code signals corresponding to the fourth character code group;

display controller means for enabling the display means to display the first character code group in response to the first character code signals, to display the second character code group in response to the second character code signals, to display the third character code group in response to the third character code signals, to display the fourth chacter code group in response to the fourth character code signals, to display the first number in response to a first digital display signal corresponding to the value of the first engine condition in the units indicated by the first character code group, to display the second number in response to a second digital display signal corresponding to the value of the second engine condition in the units indicated by the second character group, to display the third number in response to a third digital display signal corresponding to the value of the third engine condition in the units indicated by the third character group, and to display the fourth number in response to a fourth digital display signal corresponding to the value of the fourth engine condition in the units indicated by the fourth character group;

processor means for operating in a first mode during the first time period to alter the digital measurement signals to produce the first and second digital display signals, respectively, and to transmit the first and second digital display signals and the first and second character code signals to the display controller means so that the first and second numbers and the first and second character groups are displayed, and for operating in a second mode during the second time period to alter the value of the third and fourth digital measurement signals to produce the third and fourth digital display signals, respectively, and to transmit the third and fourth digital display signals and the third and fourth character control signals to the display controller means so that the third and fourth numbers and the third and fourth character groups are displayed; and

selection means for enabling the processor means to operate in the first mode so that the first operating state of the engine can be analyzed by observing the first and second numbers on the face of the display means and for enabling the processor means to operate in the second mode so that the second operating state of the engine can be analyzed by observing the third and fourth numbers on the face of the display means.

36. Apparatus, as claimed in claim 35, wherein the means coupled to the engine for generating comprises:

analog measuring means for generating an analog measuring signal corresponding to the engine condition being measured; and

converter means for converting the analog measuring signal to the digital measurement signal.

37. Apparatus, as claimed in claim 35, wherein the memory means comprises a digital memory.

38. Apparatus, as claimed in claim 35, wherein the processor means comprises:

an arithmetic unit;

a control unit;

means for transmitting data from the memory means to the display controller means; and

means for enabling the temporary storage of the first digital display signal before transmitting the first digital display signal to the display controller means.

39. Apparatus, as claimed in claim 35, wherein the display controller means comprises a buffer memory for storing the first character code signal while the first character group is displayed on the face of the display means.

40. Apparatus, as claimed in claim 35, wherein the display means comprises a cathode ray tube.

41. Apparatus, as claimed in claim 40, wherein the cathode ray tube comprises an electron gun for scanning the face with a predetermined number of scan lines at a predetermined rate, and wherein the display controller means comprises:

clock means for generating clock pulses at a predetermined rate;

row counter means for counting clock pulses so that each scan is divided into a predetermined number of rows; and

line counter means for counting the scans so that the face of the cathode ray tube means is divided into a predetermined number of lines for displaying characters.

42. Apparatus, as claimed in claim 35, wherein the memory means comprises means for storing character signals corresponding to a first alphabetic instruction and a second alphabetic instruction to be displayed on the display means, wherein the processor means comprise means for transmitting the character signals to the display controller means, and wherein the display controller means comprises means for displaying the first alphabetic instruction during the first time period and for displaying the second alphabetic instruction during the second time period.

43. Apparatus, as claimed in claim 35, wherein the processor means enables the storage of the first digital measurement signal in the memory means during the first time period, and uses the first and third digital measurement signals during the second time period in order to calculate a fifth digital display signal for display on the display means.

44. Apparatus, as claimed in claim 35, wherein the selection means comprises a transmitter located remotely from the processor means.

45. Apparatus for displaying a first engine condition associated with a first chamber of an internal combustion engine and for separately displaying a second engine condition associated with a second chamber of the internal combustion engine, said apparatus comprising:

means coupled to the engine for generating a first digital measurement signal corresponding to the first engine condition and for generating a second digital measurement signal corresponding to the second engine condition;

display means having a face for displaying at a first location on the face a first character group indicative of the unit in which the first and second engine conditions are measured, for displaying at a second location on the face a first number indicative of the value of the first engine condition and for displaying at a third location on the face a second number indicative of the value of the second engine condition;

memory means for storing first character code signals corresponding to the first character group, a first display address signal corresponding to the first location, a second display address signal corresponding to the second location and a third display address signal corresponding to the third location;

display controller means for enabling the display means to display the first character group at the first location in response to the first character code signals and the first display address signal, for enabling the display means to display the first number at the second location in response to the second display address signal and a first digital display signal corresponding to the value of said first engine condition in the units indicated by the first character group, for enabling the first display means to display the second number at the third location in response to the third display address signal and a second digital display signal corresponding to the value of said second engine condition in the units indicated by the first character group; and

processor means for transmitting the first character code signals and first display address signal to the display controller means so that the first character group is displayed, for altering the value of the first and second digital measurement signals to produce the first and second digital display signals and transmitting the first and second digital display signals together with the second and third display address signals to the display controller means, whereby the first number and second number are simultaneously displayed on the face of the display means so that the value of the first and second engine conditions can be observed.

46. Apparatus, as claimed in claim 45, wherein the means coupled to the engine for generating comprises:

analog measuring means for generating an analog measuring signal corresponding to the engine condition being measured; and

converter means for converting the analog measuring signal to the digital measurement signal.

47. Apparatus, as claimed in claim 45, wherein the memory means comprises a digital read-only memory for storing an application control program.

48. Apparatus, as claimed in claim 45, wherein the processor means comprises:

an arithmetic unit;

a control unit;

means for transmitting data from the memory means to the display controller means; and

means for enabling the temporary storage of the first digital display signal before transmitting the first digital display signal to the display controller means.

49. Apparatus, as claimed in claim 45, wherein the display controller means comprises a buffer memory for storing the first character code signals while the first character group is displayed on the face of the display means.

50. Apparatus, as claimed in claim 45, wherein the display means comprises a cathode ray tube.

51. Apparatus, as claimed in claim 50, wherein the cathode ray tube comprises an electron gun for scanning the face with a predetermined number of scan lines at a predetermined rate, and wherein the display controller means comprises:

clock means for generating clock pulses at a predetermined rate;

row counter means for counting clock pulses so that each scan is divided into a predetermined number of rows; and

line counter means for counting the scans so that the face of the cathode ray tube means is divided into a predetermined number of lines for displaying characters.

52. Apparatus, as claimed in claim 45, wherein the internal combustion engine comprises a first ignitor located adjacent the first chamber, a second ignitor located adjacent the second chamber, a switch periodically opened and closed in synchronism with the engine to create a first firing signal for activating the first ignitor and for creating a second firing signal for activating the second ignitor and wherein the means coupled to the engine further comprises:

chamber selection means for producing a first chamber selection pulse during the creation of the first firing signal and for producing a second chamber selection pulse during the creation of the second firing signal; and

means for producing the first digital measurement signal in response to the first chamber selection pulse and for producing the second digital measurement signal in response to the second chamber selection pulse.

53. Apparatus, as claimed in claim 52, wherein the chamber selection means comprises:

register means for receiving from the processor means a first selection code corresponding to the first chamber or a second selection code corresponding to the second chamber;

first counter means for counting the signals produced by the opening and closing of the switch and for producing a first counting state during the creation of the first firing signal and for producing a second counting state during the creation of the second firing signal; and

comparator means for generating the first chamber selection pulse when the first selection code corresponds to a first counting state and for generating the second chamber selection pulse when the second chamber selection code corresponds to the second counting state.

54. Apparatus, as claimed in claim 45, and further comprising panel switch means for selecting the type of engine condition to be displayed, wherein the processor means comprises means for periodically interrogating the panel switch means independent of the selection state of the panel switch means, whereby a change in the type of engine condition selected on the panel switch means results in a substantially instantaneous change of the unit and values displayed on the display means.

55. Apparatus, as claimed in claim 54, wherein the processor means comprises executive means for interrogating the panel switch means before the first and second digital display signals and the first, second and third display address signals are transmitted to the display controller means.

56. Apparatus, as claimed in claim 45, wherein the processor means comprises means for transmitting the first character code signal and the first display address signal in parallel form to the display controller means, whereby the display of engine parameters in real time is facilitated.

57. Apparatus, as claimed in claim 56, wherein the first character code signal and the first display address signal are transmitted to the display controller means in a single word.

58. Apparatus, as claimed in claim 45, wherein the first character group comprises alphabetic letters.

59. Apparatus for determining and displaying the value of a predetermined parameter of an internal combustion engine having a plurality of chambers fitted with ignitors operated by a series of time-spaced firing signals, said apparatus comprising:

means coupled to the engine for generating a digital measurement signal proportional to the value of the predetermined parameter;

display means having a face for displaying at a first location a scale of numbers indicative of the predetermined parameter and for displaying a variable graphic image adjacent the scale;

memory means for storing first character code signals corresponding to the scale of numbers and first number display address signals corresponding to the first location;

display controller means for enabling the display means to display the scale of numbers at the first location in response to the first character code signals and the first number display address signals, and for producing a graphic image at a position adjacent the scale of numbers determined by the value of a digital display signal, so that the predetermined parameter is visually represented; and

processor means for transmitting the first character code signals and first number display address signals to the display controller means so that the scale of numbers is displayed and for converting the digital measurement signal into a digital display signal and transmitting the digital signal to the display controller means so that the graphic image is displayed on the display means.

60. Apparatus, as claimed in claim 59, wherein the means coupled to the engine comprises:

clock means for producing clock pulses at a predetermined rate;

counter means for counting the clock pulses; and

gate means for transmitting the clock pulses to the counter means in response to a first one of the firing signals and for preventing clock pulses from being transmitted to the counter means in response to a second one of the firing pulses in order to form the digital measurement signal in the counter means.

61. Apparatus, as claimed in claim 60, wherein the processor means comprises means for computing the digital display signal from the digital measurement signal by inverting the digital measurement signal.

62. Apparatus, as claimed in claim 60, wherein the gate means is responsive only to the firing pulse transmitted to a single one of the ignitors.

63. Apparatus, as claimed in claim 62, wherein the first firing signal occurs at the beginning of one engine cycle and the second firing signal occurs at the beginning of the next subsequent engine cycle.

64. Apparatus, as claimed in claim 59, wherein the processor means comprises means for dividing a constant by the number of pulses counted by the counter means.

65. Apparatus, as claimed in claim 59, wherein the means coupled to the engine comprises means for generating a digital measurement signal proportional to the speed of the engine, whereby the speed of the engine is visually represented.

66. Apparatus, as claimed in claim 59, wherein the display means comprises a cathode ray tube.

67. Apparatus, as claimed in claim 66, wherein the cathode ray tube comprises:

an electron gun for striking the face of the tube with an electron beam in response to the graphic signal; and

scanning means for scanning the beam across the face in a series of parallel lines, each line being scanned during a predetermined time period.

68. Apparatus, as claimed in claim 67, wherein the display controller means comprises:

first latch means for storing a row number signal corresponding to the row on the face at which the graphic image is to be produced;

first counter means for counting the number of rows scanned by the scanning means, and for producing a first start signal in the row indicated by the row number signal;

second counter means for counting the number of lines scanned by the scanning means within the row indicated by the row number and for producing a second start signal in a predetermined line;

means for receiving clock pulses at a predetermined rate;

second latch means for storing the digital display signal;

third counter means for generating a stop signal after the receipt of a predetermined number of clock pulses proportional to the value of the digital display signal;

means for resetting the third counter means at the beginning of each scan line; and

means responsive to the first and second counter means for generating the graphic signal in response to the first and second start signals and terminating the graphic signal in response to the stop signal, whereby the cathode ray tube generates a visible line having a length proportional to the value of the predetermined parameter.

69. Apparatus, as claimed in claim 68, wherein the memory means comprises means for storing the row number signal.

70. Apparatus for measuring and displaying a parameter useful for diagnosing an internal combustion engine comprising:

transducer means for generating a digital calibration signal corresponding to the ambient value of the parameter adjacent the engine during a first time period and for generating a digital measurement signal corresponding to the value of the parameter produced by the engine as well as the ambient value of the parameter during a second time period;

display means including a face for displaying a digital measurement number indicative of the value of the parameter produced only by the engine;

memory means for storing the digital calibration signal;

processor means for combining the digital calibration signal and the digital measurement signal to produce a digital calculated signal having a value which eliminates the effect of the ambient value of the parameter on the digital measurement signal; and

display controller means for enabling the display means to display the digital measurement number in response to the digital calculated signal.

71. Apparatus, as claimed in claim 70, wherein the transducer means comprises:

analog measuring means for generating an analog measuring signal corresponding to the parameter being measured; and

converter means for converting the analog measuring signal to a digital signal.

72. Apparatus, as claimed in claim 70, wherein the parameter is amperes.

73. Apparatus, as claimed in claim 70, wherein the memory means comprises a digital read-only memory for storing an application control program.

74. Apparatus, as claimed in claim 70, wherein the processor means comprises:

an arithmetic unit;

a control unit; and

means for transmitting data among the processor means, memory means, transducer means and display controller means.

75. Apparatus, as claimed in claim 74, wherein the arithmetic unit comprises means for subtracting the digital calibration signal from the digital measurement signal.

76. Apparatus, as claimed in claim 70, wherein the display means comprises a cathode ray tube.

77. Apparatus, as claimed in claim 76, wherein the display controller means comprises a character generator.

78. Apparatus, as claimed in claim 70, and further comprising panel switch means for selecting the engine parameter to be displayed, wherein the processor means comprises means for periodically interrogating the panel switch means independent of the selection state of the panel switch means, whereby a change in the engine parameter selected on the panel switch means results in a substantially instantaneous change of the measurement number displayed on the display means.

79. Apparatus, as claimed in claim 78, wherein the processor means comprises executive means for interrogating the panel switch means before the digital calculated signal is transmitted to the display controller means.

80. Apparatus for measuring and displaying a parameter useful for diagnosing an internal combustion engine comprising:

transducer means coupled to the engine for generating a digital measurement signal corresponding to the value of the parameter produced by the engine;

display means including a face for displaying a digital measurement number indicative of the value of the parameter produced by the engine if the digital measurement number is within a predetermined range of values and for displaying a symbol if the digital measurement signal is outside the predetermined range of values;

memory means for storing range signals indicative of the range of values of the digital measurement number acceptable for display on the display means;

processor means for comparing the digital measurement signal with the range signals, for producing the error signal if the value of the digital measurement signal is outside the predetermined range of values indicated by the range signals, and for producing a digital display signal corresponding to the value of the digital measurement signal is within the predetermined range of values indicated by the range signals; and

display controller means for enabling the display means to display the digital measurement number in response to the digital display signal and for enabling the display means to display the symbol in response to the error signal.

81. Apparatus, as claimed in claim 80, wherein the transducer means comprises:

analog measuring means for generating an analog measuring signal corresponding to the parameter being measured; and

converter means for converting the analog measuring signal to the digital measurement signal.

82. Apparatus, as claimed in claim 81, wherein the parameter is current.

83. Apparatus, as claimed in claim 81, wherein the parameter is resistance.

84. Apparatus, as claimed in claim 80, wherein the memory means comprises a digital read-only memory for storing an application control program.

85. Apparatus, as claimed in claim 80, wherein the processor means comprises:

an arithmetic unit;

a control unit; and

means for transmitting data among the processor means, memory means, transducer means and display controller means.

86. Apparatus, as claimed in claim 80, wherein the display means comprises a cathode ray tube.

87. Apparatus, as claimed in claim 86, wherein the display controller means comprises a character generator.

88. Apparatus, as claimed in claim 80, and further comprising panel switch means for selecting the engine parameter to be displayed, wherein the processor means comprises means for periodically interrogating the panel switch means independent of the selection state of the panel switch means, whereby a change in the engine parameter selected on the panel switch means results in a substantially instantaneous change of the digital measurement number displayed on the display means.

89. Apparatus, as claimed in claim 88, wherein the processor means comprises executive means for interrogating the panel switch means before the digital display signal is transmitted to the display controller means.

90. Apparatus for automatically determining the relative power produced by at least the first and second chambers of an internal combustion engine, the first and second chambers being fitted with first and second ignitors fired by time-spaced firing signals generated by the engine, said apparatus comprising:

disabling means for preventing a firing signal from being transmitted to the first ignitor in response to a first disable signal and for preventing a firing signal from being transmitted to the second ignitor in response to a second disable signal;

speed detection means for generating a digital base speed signal having a value proportional to the base speed of the engine when the first or second ignitors are enabled to receive firing signals, for generating a first digital disabled speed signal proportional to the first disabled speed of the engine when the first ignitor is prevented from receiving firing signals and for generating a second digital disabled speed signal having a value proportional to the second disabled speed of the engine when the second ignitor is prevented from receiving firing signals;

memory means for storing the digital base speed signal in response to a store signal;

display means for displaying a first speed change number indicating the difference between the speed of the engine when both first and second ignitors are enabled and when the first ignitor is prevented from receiving firing signals and for displaying a second speed change number indicating the difference between the speed of the engine when both first and second ignitors are enabled and when the second ignitor is prevented from receiving firing signals;

display controller means for enabling the display means to display the first speed change number in response to a first speed change signal and for enabling the display means to display the second speed change number in response to a second speed change signal; and

processor means for enabling the production of the first disabled speed signal at a first point in time and for calculating the first speed change number in response to the digital base speed signal and the first disabled speed signal, whereby the first speed change number is displayed, and

for enabling the production of the second disabled speed signal at a second point in time and for calculating the second speed change number in response to the digital base speed signal and the second disabled speed signal, whereby the second speed change number is displayed.

91. Apparatus, as claimed in claim 90, wherein the processor means comprises means for sampling the digital base speed signal over a first predetermined number of engine revolutions and for averaging the values of the sampled digital base speed signals, whereby the average base speed of the engine over the first predetermined number of engine revolutions is used to calculate the first and second speed change numbers.

92. Apparatus, as claimed in claim 91, wherein the processor means further comprises:

means for sampling the first digital disabled speed signal over a second predetermined number of engine revolutions and for averaging the values of the sampled first digital disabled speed signals, whereby the average first disabled speed of the engine over the second predetermined number of engine revolutions is used to calculate the first speed change number; and

means for sampling the second digital disabled speed signal over a third predetermined number of engine revolutions and for averaging the values of the sampled second digital disabled speed signals, whereby the average second disabled speed of the engine over the third predetermined number of engine revolutions is used to calculate the second speed change number.

93. Apparatus, as claimed in claim 92, wherein the speed detection means comprises:

clock means for producing clock pulses at a predetermined rate;

a counter means for counting clock pulses; and

gate means for transmitting clock pulses to the counter means in response to a first one of the firing pulses and for inhibiting clock pulses from being transmitted to the counter means in response to a second one of the firing pulses.

94. Apparatus, as claimed in claim 92, wherein the processor means comprises an arithmetic unit and a control unit.

95. Apparatus, as claimed in claim 90, wherein the memory means comprises a digital, read-write memory.

96. Apparatus, as claimed in claim 90, wherein the display means comprises a cathode ray tube.

97. Apparatus, as claimed in claim 90, wherein the digital base speed signal has a value proportional to the average base speed of the engine when the first and second ignitors are enabled to receive firing signals.

98. Apparatus for measuring and displaying a parameter of an internal combustion engine which is capable of varying over a first and second range of values, said apparatus comprising:

analog measuring means operable with a first degree of sensitivity for generating a first analog measuring signal having a first value proportional to the parameter and operable with a second degree of sensitivity for generating a second analog measuring signal having a value proportional to the parameter times a scale factor;

converter means for converting the first analog measuring signal to a first digital measurement signal and for converting the second analog measuring signal to a second digital measurement signal;

display means having a face for displaying at a first location on the face a first character group indicative of the units in which the parameter is measured and for displaying at a second location on the face a first number indicative of the value of the parameter in the first range and a second number indicative of the value of the parameter in the second range;

display controller means for enabling the display means to display the first number at the second location in response to a first digital display signal and to display the second number at the second location in response to a second digital display signal;

memory means for storing a scale factor signal corresponding to the scale factor; and

processor means for operating the analog measuring means with the first degree of sensitivity when the parameter is within the first range of values so that the first digital measurement signal is produced and for converting the first digital measurement signal into the first conversion signal to form the first digital display signal whereby the first number is displayed, and for operating the analog measuring means with the second degree of sensitivity when the parameter is within the second range of values so that the second digital measurement signal is produced and for combining the second digital measurement signal with the scale factor signal to form the second digital display signal whereby the second number is displayed.

99. Apparatus, as claimed in claim 98, wherein the memory means comprises means for storing a range digital signal having a value between the first range of values and the second range of values, and wherein the processor means comprises means for comparing the range digital signal with the first digital measurement signal to determine whether the parameter lies within the first or second range of values.

100. Apparatus, as claimed in claim 99, wherein:

the analog measuring means and converter means comprise an amplifier including means for adjusting the gain of the amplifier to a first level in response to a first adjustment signal and capable of adjusting the gain of the amplifier to a second level in response to a second adjustment signal; and

the processor means comprises means for generating the first adjustment signal when the parameter is within the first range of values and for generating the second adjustment signal when the parameter is within the second range of values.

101. Apparatus, as claimed in claim 100, wherein the memory means further comprises a digital memory.

102. Apparatus, as claimed in claim 101, wherein the display means comprises a cathode ray tube.

103. Apparatus, as claimed in claim 102, wherein the processor means comprises an arithmetic unit for multiplying the value of second digital measurement signal times the value of the scale factor signal to form the second digital display signal.

104. Apparatus for measuring and displaying the maximum value of a parameter of an internal combustion engine which varies in value comprising in combination:

means for generating during a predetermined time period a series of time-spaced digital measurement signals having values corresponding to the values of the parameter as it varies;

memory means for storing at any one instant in time the measurement signal having the largest value of all the measurement signals generated during the predetermined time period;

processor means for repetitively comparing the value of the stored measurement signal with the value of a subsequently-generated measurement signal and for storing the subsequently-generated measurement signal in place of the stored measurement signal in the memory means if the value of the subsequently-generated measurement signal is greater than the value of the stored measurement signal; and

display means for displaying a number corresponding to the value of the measurement signal remaining in the memory means at the end of the predetermined time period, whereby the maximum value of the parameter occurring during the predetermined time period is displayed.

105. Apparatus, as claimed in claim 104, wherein the parameter is current.

106. Apparatus, as claimed in claim 104, wherein the processor means comprises a digital computer.

107. Apparatus, as claimed in claim 104, wherein the display means comprises:

a character generator; and

a cathode ray tube monitor.

108. Apparatus, as claimed in claim 104, wherein the engine comprises an ignition system including a high voltage secondary coil for generating secondary ignition signals and wherein the parameter comprises the secondary ignition signal voltage.

109. Apparatus, as claimed in claim 108, wherein the means for generating comprises:

means for generating a threshold signal in response to the rising of the secondary ignition signal voltage above a predetermined threshold level;

means for generating a cross-over signal in response to a decrease in said secondary ignition signal voltage after said voltage has attained the maximum value;

a storage capacitor; and

gate means responsive to the threshold and cross-over signals for enabling the storage capacitor to charge to a storage voltage proportional to the secondary ignition signal voltage, for generating a sample signal indicating that the storage voltage is available for sampling and for thereafter discharging the storage capacitor.

110. Apparatus, as claimed in claim 104, wherein the predetermined time period is no greater than the time required for one revolution of said engine.

111. Apparatus for measuring and displaying the minimum value of a parameter of an internal combustion engine which varies in value comprising in combination:

means for generating during a predetermined time period a series of time-spaced digital measurement signals having values corresponding to the values of the parameter as it varies;

memory means for storing at any one instant in time the measurement signal having the smallest value of all the measurement signals generated during the predetermined time period;

processor means for repetitively comparing the value of the stored measurement signal with the value of one or more subsequently-generated measurement signals and for storing the subsequently-generated measurement signal in place of the stored measurement signal in the memory means if the value of the subsequently-generated measurement signal is less than the value of the stored measurement signal; and

display means for displaying a number corresponding to the value of the measurement signal remaining in the memory means at the end of the predetermined time period, whereby the minimum value of the parameter occurring during the predetermined time period is displayed.

112. Apparatus, as claimed in claim 111, wherein the processor means comprises a digital computer.

113. Apparatus, as claimed in claim 111, wherein the engine comprises an ignition system including a high voltage secondary coil for generating secondary ignition signals and wherein the parameter comprises the secondary ignition signal voltage.

114. Apparatus, as claimed in claim 111, wherein the means for generating comprises:

means for generating a threshold signal in response to the rising of the secondary ignition signal voltage above a predetermined threshold level;

means for generating a cross-over signal in response to a decrease in said secondary ignition signal voltage after said voltage has attained the maximum value;

a storage capacitor; and

gate means responsive to the threshold and cross-over signals for enabling the storage capacitor to charge to a storage voltage proportional to the secondary ignition signal voltage, for generating a sample signal indicating that the storage voltage is available for sampling and for thereafter discharging the storage capacitor.

115. Apparatus, as claimed in claim 111, wherein the predetermined time period is no greater than the time required for one revolution of said engine.

116. Apparatus for determining the timing of an internal combustion engine having a plurality of chambers fitted with ignitors which are operated by a series of time-spaced firing pulses and having a timing mark which passes a timing location when the engine is located at a predetermined number of degrees prior to a top dead center position, said apparatus comprising:

a register for storing the predetermined number of degrees;

manually operable means for entering the predetermined number of degrees into the register;

generator means for generating a timing pulse when the timing mark passes the timing location;

clock means for producing clock pulses at a predetermined rate;

a counter means for counting clock pulses;

gate means for transmitting clock pulses to the counter means between the occurrence of a first and second one of the firing pulses to obtain a first count proportional to the time period between the first and second ignition pulses, and for transmitting clock pulses to the counter means between the occurrence of one of the firing pulses and the timing pulse to obtain a second count proportional to the time period between the last said firing pulse and the timing pulse;

processor means for generating a timing number proportional to the second count divided by the first count plus the predetermined number of degrees; and

display means for displaying a timing display number proportional to the timing number in digital form.

117. Apparatus, as claimed in claim 116, wherein the gate means is responsive only to the firing pulses transmitted to a single one of the ignitors.

118. Apparatus, as claimed in claim 116, wherein the first firing pulse occurs at the beginning of one engine cycle and the second firing pulse occurs at the beginning of the next subsequent engine cycle.

119. Apparatus, as claimed in claim 116, wherein the processor means comprises means for multiplying a constant times the quotient of the second count divided by the first count.

120. Apparatus, as claimed in claim 116, wherein the display means comprises:

a character generator; and

a cathode ray tube monitor.

121. Apparatus, as claimed in claim 116, wherein the manually-operable means comprises a keyboard capable of generating digital data.

122. Apparatus, as claimed in claim 116, wherein the processor means comprises means for determining whether the timing number exceeds a predetermined number of degrees, whereby the timing display number is displayed as degrees advance or as degrees retard.

124. Apparatus, as claimed in claim 122, wherein the processor means comprises:

an arithmetic unit;

a control unit; and

means for transmitting data among the processor means, memory means, transducer means and display controller means.

125. Apparatus, as claimed in claim 124, wherein the display means comprises a cathode ray tube.

126. Apparatus, as claimed in claim 124, wherein the transducer means comprises:

analog measuring means for generating an analog measuring signal corresponding to the parameter being measured; and

converter means for converting the analog measuring signal to the digital measurement signal.

127. Apparatus, as claimed in claim 124, wherein the parameter is the concentration of an exhaust emission from the engine.

128. Apparatus, as claimed in claim 124, wherein the memory means comprises a digital read-only memory for storing the first and second linearization constants.

123. Apparatus for measuring and displaying a parameter useful for diagnosing an internal combustion engine comprising:

transducer means for generating a digital measurement signal corresponding to the value of the parameter produced by the engine;

display means including a face for displaying a digital measurement number indicative of the value of the parameter;

memory means for storing first and second linearization constants;

processor means for multiplying the value of the digital measurement signal times the value of the first linearization constant to produce a first partial result signal, for multiplying a power of the value of the digital measurement signal times the value of the second linearization constant to produce a second partial result signal, and for summing the values of the first and second partial result signals in order to produce a digital calculated signal, whereby the value of the digital measurement signal is linearized; and

display controller means for enabling the display means to display the digital measurement number in response to the digital calculated signal.