US3559063A - Rpm counter for internal combustion engines - Google Patents

Rpm counter for internal combustion engines Download PDF

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Publication number
US3559063A
US3559063A US777567A US3559063DA US3559063A US 3559063 A US3559063 A US 3559063A US 777567 A US777567 A US 777567A US 3559063D A US3559063D A US 3559063DA US 3559063 A US3559063 A US 3559063A
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United States
Prior art keywords
diode
transistor
pole
resistance
internal combustion
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Expired - Lifetime
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US777567A
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English (en)
Inventor
Remo Galletti
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D Olivetti & C Spa
Olivetti & C SpA D
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Olivetti & C SpA D
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
    • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
    • G01P3/4802—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage by using electronic circuits in general
    • G01P3/4807—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage by using electronic circuits in general by using circuits for the detection of the pulses delivered by the ignition system of an internal combustion engine

Definitions

  • An RPM counter for internal combustion engines which measures the interruption frequency of an external breaker switch including a meter, a power supply, a transistor and a compensating unit for changes in battery voltage which includes a capacitor, a Zener diode and a diode, with interposed resistances in the circuit.
  • the present invention relates to an analogic pulse counter device, particularly for use as a speed indicator for internal combustion engines or speedometer for motor cars.
  • the present invention provides an analogic pulse counter device, particularly for the aforesaid applications, which is extremely simple, practical and thus economical, particularly by employing one transistor only.
  • the analogic pulse counter device according to the invention essentially comprises a measuring instrument connected between the collector and emitter of a transistor, the base of which is connected through a suitable component network to a terminal of a switch or breaker, so that the current, as indicated by the instrument, is proportional to interruption frequency, circuitry being provided for rendering the instrument indication, within determined limits, independent of supply voltage.
  • FIG. 1 is an electric diagram for an analogic pulse counter device according to the invention.
  • FIG. 2 shows a modified embodiment contemplating the use of two transistors.
  • FIG. 1 there is schematically shown at S a switch or breaker of any desired type, generally at the outside of the actual device and forming part of the system, the interruption frequency of which is to be measured.
  • S may be the usual breaker of the ignition system for an internal combustion engine, the revolutions of which are to be measured.
  • S has a terminal connected to the positive pole Va through a reactance, the other termi nal being grounded.
  • the base of a transistor T1 is connected in series, through a capacitor C2, a diode D1 and a resistor R1, to that terminal of breaker switch S which is connected to the positive pole.
  • R1 and D1 are grounded through a capacitor C1
  • D1 and C2 are grounded through a diode D2 (preferably a Zener diode) and a resistor R2 series connected.
  • Point A is also connected to the positive pole (+Va) through a resistor R3.
  • Base of transistor T1 (indicated by B) is series connected to +Va through a resistor R4 and a rheostat R5.
  • the collector of transistor T1 is connected to +Va through a resistor R6 and to a milliammeter I1 through a diode D3, the other terminal of milliammeter 11 being grounded.
  • the emitter of transistor T1 is grounded.
  • Set R1-C1 filters any oscillations or disturbances in the inlet circuit; diode D1 cuts off when the input goes positive and allows capacitor C2 to charge at the voltage as determined by Zener D2 (temporarily omitting to consider R2, the function of which will be described in the following.
  • D 1 When 51 closes, D 1 is rendered conducting and voltage of point D lowers to the same extent as A, cutting off T1.
  • Capacitor C2 discharges through R4 and R5 to bring T1 back to a conducting state.
  • Rheostat R5 permits the calibration of the current flowing through I1, adjusting the cutoff time for T1 and thus compensating for the tolerances of the various components.
  • T1 is cut off, a current limited to R6 flows through 11. With T1 saturated, diode D3 prevents a current from flowing through I 1 due to saturation voltage of T1.
  • supply voltage +Va is not stabilized (for example, Va may be a motor car battery voltage).
  • Va may be a motor car battery voltage.
  • provision is made so that the reading of 11 is independent of +Va.
  • +Va voltage there could be provided, for example, a Zener diode, but this would involve a power dissipation.
  • the indication of I1 is made independent of Va by a suitable compensation or equalizing system. Should the voltage sweep of points A and B, and hence base of T1, be constant and independent of Va, it could be readily verified that the average current of I1 for a given pulse frequency would be proportional to Va.
  • I1 may be a milliammeter having an in- 3 ternal resistance of 160 and 12 ma. at full scale value; Rx is a thermistance which can be series added to I1 Where thermal compensation of the instrument is desired.
  • FIG. 2 shows a possible modified embodiment of the invention.
  • diode D1 is substantially replaced by a transistor T2, the emitter of which is grounded by an equalizing resistor R1.
  • R7 As input resistance, there is instead provided a resistor R7 the value of which can be very high.
  • a pulse counter for measuring the interruption frequency of the breaker switch of the ignition system of the engine whose speed is being measured (S-Sl), a supply battery having a positive first pole (+Va) and a grounded second pole;
  • a first resistor (R6), a first diode (D3), and a meter (11) being serially connected, in the order of recitation, between said first and second poles;
  • T1 having a base, an emitter connected to the second pole, and a collector;
  • said collector being connected to the circuit point between said first resistance and said first diode
  • said compensating unit including a third resistance (R3) and a Zener diode (D2);
  • said third resistor (R3) by one of its terminals being directly connected to said first pole, and connected by its other terminal through the Zener diode (D2) to said second pole;
  • the other electrode of said first capacitor being connected to the terminal of the third resistance (R3) which is adjacent the Zener diode (D2) and also connected to one electrode of second diode (D1), the other electrode of said second diode being connected to one terminal of the fourth resistance (R1), the other terminal of said fourth resistance being connected to one terminal of said breaker switch.
  • a filtering capacitor (C1) interposed in series between said other electrode of said second diode and said second pole.
  • a pulse counter for measuring the interruption frequency of the breaker switch the ignition system of 4 the engine whose speed is being measured (S-Sl), a supply battery having a positive first pole (+Va) and a grounded second pole;
  • a first resistor (R6), a first diode (D3), and a meter (I1) being serially connected, in the order of recitation, between said first and second poles;
  • T1 having a base, an emitter connected to the second pole, and a collector;
  • said collector being connected to a circuit point between said first resistance and said first diode
  • a first capacitor (C2) having one electrode connected to said transistor 'base;
  • said compensating unit including a third resistance (R3) and a Zener diode (D2);
  • T2 a second transistor
  • the other electrode of said first capacitor (C2) being connected to that terminal of the third resistance (R3) which is adjacent the fourth resistance (R1) and also connected to the emitter of said second transistor;
  • the collector of said second transistor being connected to said first pole, and the base of said second transistor being connected to one electrode of said Zener diode, the other electrode of said Zener diode being connected to said second pole;
  • a filtering capacitor (C1) with one electrode connected to the electrode of the Zener diode (D2) adjacent the base of the second transistor (T2), the other electrode of said filtering capacitor being connected to said second pole.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Current Or Voltage (AREA)
US777567A 1967-11-24 1968-11-21 Rpm counter for internal combustion engines Expired - Lifetime US3559063A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT2309067 1967-11-24

Publications (1)

Publication Number Publication Date
US3559063A true US3559063A (en) 1971-01-26

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ID=11203666

Family Applications (1)

Application Number Title Priority Date Filing Date
US777567A Expired - Lifetime US3559063A (en) 1967-11-24 1968-11-21 Rpm counter for internal combustion engines

Country Status (8)

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US (1) US3559063A (de)
AT (1) AT300425B (de)
BE (1) BE724226A (de)
CH (1) CH487466A (de)
DE (1) DE1810576A1 (de)
FR (1) FR1592465A (de)
NL (1) NL6816685A (de)
SE (1) SE340904B (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3719888A (en) * 1971-05-26 1973-03-06 Pentron Industries Predetermined speed detector for digital tachometer
US4095178A (en) * 1976-10-21 1978-06-13 Sun Electric Corporation Tachometer circuit

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3719888A (en) * 1971-05-26 1973-03-06 Pentron Industries Predetermined speed detector for digital tachometer
US4095178A (en) * 1976-10-21 1978-06-13 Sun Electric Corporation Tachometer circuit

Also Published As

Publication number Publication date
SE340904B (de) 1971-12-06
FR1592465A (de) 1970-05-11
NL6816685A (de) 1969-05-28
AT300425B (de) 1972-07-25
CH487466A (it) 1970-03-15
DE1810576A1 (de) 1969-12-04
BE724226A (de) 1969-05-02

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