# US 4,391,251 A · Electronic controller for controlling the air/fuel ratio of the mixture supplied to an internal combustion engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,391,251 A - Document ID: US4391251A - Status: Granted - Kind: A - Application number: 06/197,604 - Filed: 1980-10-16 - Granted: 1983-07-05 - Earliest claimed: 1979-10-19 - Assignees: Groupement d'Interet Economique de Recherche et de Developpement PSA - Inventors: Pierre Planteline; Roger Machetel - Web page: https://patentgrep.com/patent/US4391251A ## CPC - F02D 41/26: using computer, e.g. microprocessor - F02D 41/1482: {Integrator, i.e. variable slope} - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) ## Abstract A digital electronic controller for an engine equipped with an oxygen detor located along the exhaust path of the gases and a carburettor equipped with electrovalves for regulating the fuel flow rate. This controller comprises digital circuits for closed loop and open loop regulation including a digital memory in which the carburettor regulation value is permanently stored, a logic circuit for controlling the operating modes and a plurality of amplifiers for controlling the electrovalves of the carburettor. This controller makes it possible to reduce the pollution level of motor vehicles. ## Claims ### Claim 1 A digital electronic controller for regulating the air/fuel ratio of the mixture supplied to the cylinders of an internal combustion engine, having an EGO sensor situated on the exhaust path of the burned gases, at least one fuel supply device, such as a carburetor, whose fuel flow rate can be modified by an electrovalve controlled on the basis of an opening/closing cycle and a plurality of sensors for measuring operating conditions of this engine, said electronic controller comprising: a clock signal generator providing synchronous signals and a clock signal at the electrovalve cycle frequency; a closed loop digital circuit of the proportional integral type with variable gain, said closed loop being connected between said EGO sensor and said electrovalve and including a digital integrator having a gain control input receiving a digital signal representative of the rotation speed of the motor, a digital time duration modulator having a control input connected to the EGO sensor, and a multiplexer for opening said closed loop, said multiplexer having a command input connected to a logic circuit sensitive to operating conditions of said motor and at least a second input receiving a command signal sensitive to a motor physical parameter such as the temperature or the rotation speed of the motor. ### Claim 2 (depends on 1) The controller according to claim 1, wherein said digital integrator comprise a programmable counter of the up/down type, whose clock input is connected to a binary rate multiplier programmed by a digital signal representing the speed of revolution of the engine, said binary rate multiplier having a clock input connected to the said clock signal generator and data input connected respectively to the output of an A/D convertor which receives an analog signal representative of the speed of revolution of the engine. ### Claim 3 (depends on 2) The controller according to claim 2, wherein said programmable counter has an overflow output connected to a first input of a logic gate whose second input is connected to said binary rate multiplier and whose output is connected to the clock input of the said counter. ### Claim 4 (depends on 3) The controller according to claim 3, wherein the counting direction input of said programmable counter is connected to a counting direction selection circuit including means for forcing the counting direction. ### Claim 5 (depends on 1) The controller according to claim 1, wherein said time duration modulator comprises two linked programmable counters, each of the counters being loop connected with the first counter of said two counters having data inputs connected respectively to outputs of the digital integrator and the second counter of said two counters having data inputs connected respectively to a digital voltage source, and wherein the outputs of said two counters are connected to a multiplexer controlled by the output signal of said EGO sensor. ### Claim 6 (depends on 1) The controller according to claim 1, wherein the output signal of said digital integrator is stored in a digital memory circuit comprising, loop connected, a programmable counter of the up/down type and a digital comparator, said comparator having first data inputs connected respectively to outputs of said programmable counter whose data inputs are connected to a digital voltage source and the loading input receives an initialization command signal. ### Claim 7 (depends on 6) The controller according to claim 6, further comprising a second time duration modulator connected between said digital memory circuit and the second input of said multiplexer, said second time duration modulator comprising a programmable counter, loop connected, whose data inputs are connected respectively to outputs of said digital memory circuit, the loading input is connected to the clock signal at the frequency of the cycle of said electrovalve and the clock input is connected to a binary rate multiplier whose data inputs receive a digital signal representative of the temperature of the engine and the clock input is connected to said clock signal generator. ### Claim 8 (depends on 1, 2, 3, 4, 5, 6, 7) The controller according to any one of claims 1 to 7 further comprising a time duration comparator which is connected between the output of the first time duration modulator and the output of the second time duration modulator for providing an output signal to the counting direction forcing means. ### Claim 9 (depends on 1, 2, 3, 4, 5, 6, 7) The controller according to any one of claims 1 to 7, wherein each of said circuits are constructed in accordance with C-MOS technology and wherein the clock signals are interrupted when the engine is not operating. ### Claim 10 (depends on 1, 2, 3, 4, 5, 6, 7) An internal combustion engine, comprising a digital electronic controller according to any one of the claims 1 to 7.