Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
  • F02D41/26—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor
  • F02D41/28—Interface circuits
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/02—Input parameters for engine control the parameters being related to the engine
  • F02D2200/04—Engine intake system parameters
  • F02D2200/0404—Throttle position

Definitions

• This invention relates to electronic fuel-injection circuitry for internal-combustion engines and is more particularly concerned with generation of suitable throttle-responsive fuel- flow control signals used in such circuitry.
• the present invention is therefore directed to improvements in an electronic fuel-injection control circuit for an internal-combustion engine, wherein throttle setting and tachometer output are necessary ingredients in the generation of an electrical control signal for pulse-width modulation of a square-wave generator of fuel-injector excitation pulses, the improvement wherein a first signal reflecting throttle setting is developed by a differential-pressure transducer which is connected to track the instantaneous hydraulic pressure drop across the throttle, and is therefore related to the instantaneous manifold vacuum flow condition of the engine, and a second signal reflecting tachometer output is modulated by said first signal to develop the electrical control signal for such pulses-width modulation.
• the invention has a number of advantages including the ability to produce an output signal reflecting throttle position without use of a potentiometer or any other mechanical means to track throttle position.
• the invention accomplishes this result with means affording inherently greater life, and superior performance and reliability, in racing use of such engines. Since the invention has no mechanical tie to the throttle, there is none of the hysteresis or mechanical wear that are characteristic of conventional throttle-position sensors.
• the invention comprises a tachometer circuit which is modulated by the signal, from a differential-pressure transducer, connected to track the instantaneous hydraulic pressure drop across the engine throttle.
• the tachometer output controls the duty cycle of a pulse generator which, in turn, drives an output transistor; a reference potential is applied across the load resistor and emitter of this output transistor, and the output signal is obtained as a d-c control signal, upon filtering the signal from the collector of the output transducer.
• the transfer function of the device yields maximum output when there is little or no intake vacuum, e.g., at sustained high speed, and minimum output is obtained from minimum speed and maximum vacuum.
• Fig. 1 is an electrical block diagram, schematically indicating components of circuitry of the invention, in the context of other components of fuel-injection control circuitry, applicable to a variety of different fuel-injection engines; and Fig. 2 is a more explicit circuit diagram to show detail of the presently preferred component combination of the invention.
• Fig. 1 The diagram of Fig. 1 is similiar to Fig. 6 of U.S. Patent No. 4,349,000, in order to show context for Fig. 2 circuitry of the invention, the same being shown in Fig. 1 as signal-processing circuitry 10, operative upon tachometer voltage E T and being modulated by the output signal of a differential-pressure transducer 11 connected for response to the instantaneous drop in pressure across the engine throttle 12.
• This pressure drop will be understood to be a function of the negative- pressure or vacuum condition at the intake manifold of the engine; specifically, at full throttle and maximum speed, the pressure drop to zero or near zero, and the pressure drop is greatest at minimum throttle (and therefore at minimum engine speed).
• the modulated-signal output of the signal-processing circuitry 10 is supplied as a d-c analog voltage for multiplication at 13 with a voltage E M , and the product of this multiplication is a fuel-control voltage
• the circuit of Fig. 1 is shown in application to the development of fuel-injection voltage pulses for operation of a two-cycle V-6 engine described in detail in U.S. Patent No . 4 , 349 , 000 , and said circuit operates on various input parameters, in the form of analog voltages which reflect air-mass flow for the current engine speed, a correction being made for volumetric efficiency of the particular engine, to arrive at a modulating-voltage output E MOD in a line 15 to each of two like square-wave pulses generators 16-17.
• the square-wave output at 18 will be of predetermined duration, and the square-wave out- put at 19 will be of duration identical to that in line 18, it being understood that the predetermined duration is always a function of instantaneous engine-operating conditions.
• a first electrical sensor 20 of manifold absolute pressure is a source of first voltage E MAP which is linearly related to such pressure
• a nd a second electrical sensor 21 of manifold absolute temperature may be a thermistor which provides a voltage linearly related to such temperature, through a resistor network 22.
• the voltage E MAP is divided by the network 22 to produce an output voltage E M , which is a linear function of instantaneous air-mass or density at inlet of air to the engine.
• a first amplifier A provides the output voltage E M which is one of the inputs to multiplier 13.
• the voltage product E MF, of multiplier 13 reflects instantaneous air-mass flow for the instantaneous effective throttle (12) setting and engine speed, and a second amplifier A 2 provides a corresponding output voltage E MF for application to one of the voltage-multiplier inputs of a modulator 25, which is the source of E MOD . .
• the other voltage- multiplier input of modulator 25 receives an input voltage E E which is a function of engine speed (tachometer 26) and volumetric efficiency (network 27).
• VDD voltage regulator
• This alternator voltage enters the signal-processing circuitry at a filter R 1 -C 1 , so that the alternator output frequency in the voltage across an amplifier- input resistor R 2 can be clean, i.e., free of high- frequency (rf) noise.
• High-gain amplification via a transistor Q 1 converts the sinusoidal output of the alternator to a square-wave voltage (at alternator frequency) across a resistor R 3 .
• a capacitor C 2 differentiates the square-wave voltage, producing a series of sharply defined positive pulses; after diode clipping at D 2 , only the negative voltage pulses remain across a resistor R 4 , for recycle-triggering of an integrated circuit IC 1 ,which may be of the type-555 variety, connected for operation as a monostable multi- vibrator. Circuit constants are suitably selected so that such triggering results from cut-off of each rising multivibrator voltage at about the 2 ⁇ 3 VDD point.
• a differential-pressure transducer 30 may include a strain-gage bridge 31, for developing an electrical response to the instantaneous pressure drop across the throttle 12 of Fig. 1. As shown, this electrical response is processed by operational amplifiers 32-33 and associated resistors R 16 , R 17 (as trimmed at R 27 ) amd R 18 , to deliver a multivibrator- modulating voltage in the range from zero or near-zero, to six volts; this modulating voltage appears at the connection 34 between resistors R 7 -R 8 and is determinative of the level at which each recycled multivibrator-voltage rise commences.
• the multivibrator output appears across a resistor R 5 as a succession of square-wave voltage pulses at tachometer frequency and with a duty cycle which is an inverse function of the voltage derived from the pressure drop across throttle 12.
• Filter action via elements R 6 -C 4 smooths this pulsing voltage to a d-c voltage at the positive (+) input of an operational amplifier 35, connected as a buffer, for isolation of its d-c voltage output across a resistor R 9 .
• the smoothed and buffered quotient voltage which appears across resistor R 9 contains all the effective "throttle-positioning" data needed for replacement of the mechanically tracking throttle potentiometer 11 of Fig. 1 of U.S. Patent No. 4,349,000, the only remaining problem being that of effectively multiplying the voltage E M by this quotient voltage to achieve the voltage E MF needed by the control unit 25.
• the effective multiplication is achieved by connecting the voltage E M across a switching transistor Q 2 and its load resistor R 1 4 , and by using the quotient voltage value to control the duty cycle of switch Q 2 ; the resulting time-modulated output is smoothed by filter means R 13 -C 6 to yield the d-c output voltage E MF needed by the control unit.
• a second integrated circuit IC 2 which may also be the same type 555 as IC 1 , is connected with associated circuitry as a sawtooth generator 35, operating at a frequency of about 1000 Hz and supplying its sawtooth-voltage output to the positive (+) input of an operational amplifier 36.
• the latter is connected as a comparator, with quotient voltage applied to the negative (-) input.
• the sawtooth voltage thus recurrently scans the current level of quotient voltage to determine the on/off duty cycle of the switching transistor Q 2 .
• the quotient voltage at R 9 is applied via a coupling resistor R 10 to the connection point 37 of resistors R 11 -R 12 which divide the power-supply voltage VDD.
• R 1 10K ohms
• R 14 2K ohms
• R 2 10K ohms
• R15 100K ohms
• R 3 6.8K ohms
• R 16 100K ohms
• R 4 20K ohms
• R 17 619 ohms
• R 5 6.8K ohms
• R 18 866 ohms
• R 6 100K ohms
• R 7 332K ohms
• R 19 1K ohms
• R 8 634K ohms
• 20 33K ohms
• R 9 1K ohms
• R 21 300K ohms
• R 10 71.5K ohms
• R 22 100K ohms
• R 11 100K ohms
• R 23 10K ohms
• R 12 150K ohms
• R 24 100K ohms
• R 13 10K ohms
• R 27 500 ohms
• the four operational amplifiers (32, 33, 35, 56) are suggested by legend to be individual quarter segments of a single integrated circuit component IC 2 , variously connected as above described.
• Priority Country US Before the expiration of the time limit for amending claims and to be republished in the event of the receipt amendments.
• the device comprises a tachometer circuit which is mod lated by the signal from a differential-pressure transducer, connected to track the instantaneous hydraulic pressure dr across the engine throttle.
• the tachometer output controls the duty cycle of a pulse generator which , in turn, drives an o put transistor; a reference potential is applied across the load resistor and emitter of this output transistor, and the outp signal is obtained as a d-c control signal, upon filtering the signal from the collector of the output transducer.
• the transf function of the device yields maximum output when there is little or no intake vacuum, e.g., at sustained high speed, a minimum output is obtained from minimum speed and maximum vacuum.

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• Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)
• Fuel-Injection Apparatus (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (7)

Family Cites Families (4)

• 1987
  • 1987-11-24 AT AT88900903T patent/ATE58206T1/de not_active IP Right Cessation
  • 1987-11-24 DE DE8888900903T patent/DE3766112D1/de not_active Expired - Fee Related
  • 1987-11-24 BR BR8707900A patent/BR8707900A/pt unknown
  • 1987-11-24 JP JP88501064A patent/JPH02501399A/ja active Pending
  • 1987-11-24 EP EP88900903A patent/EP0334894B1/de not_active Expired - Lifetime
  • 1987-11-24 WO PCT/US1987/003121 patent/WO1988004361A2/en not_active Ceased
  • 1987-11-30 CA CA000553166A patent/CA1286752C/en not_active Expired - Fee Related

Non-Patent Citations (1)

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