Control system for internal combustion engine

Claim 2

A control system for an internal combustion engine comprising: counting means for accumulating a count value in synchronism with a rotation of the engine from a time when the engine starts, wherein said counting means accumulates said count value only when the engine speed exceeds a predetermined value; displaying means set when the accumulated value of said counting means reaches a predetermined value; electrically controlled valve means provided in at least one of an air and fuel supplying system to control the air/fuel ratio of a fuel-air mixture being supplied to the engine; a sensor provided in an exhaust system of the engine to generate an output signal proportional to an oxygen concentration in the exhaust gas of the engine; and control units for supplying to said electrically controlled valve means a control output signal in response to the output signal from said sensor after said display means is set, and a control output signal independent of the output signal from said sensor before said display means is set.

Claim 3

A control system for internal combustion engine according to claim 1, further comprising failure examining means for examining a failure of said sensor on the basis of whether the output signal of said sensor reaches a predetermined value or not when said displaying means is set.

Claim 4

A control system for internal combustion engine according to claim 1, wherein said counting means accumulates said count valve in synchronism with an ignition signal to the engine.

Claim 5

A control system for internal combustion engine according to claim 1, further comprising reset means for resetting the accumulated value of said counting means to zero when the engine speed is lowered from a predetermined value.

Claim 6

A control system for controlling an air/fuel ratio of a fuel-air mixture to an internal combustion engine, the control system comprising: means for producing output signals indicative of an operating condition of the engine including an output signal in synchronism with a rotation of the engine and an output signal representing a temperature of a coolant of the engine; a sensor means provided in an exhaust system of the engine for generating an output signal in accordance with an oxygen concentration in exhaust gas from the engine; electrically controlled valve means for controlling the air/fuel ratio of the air-fuel mixture supplied to the engine; control means for supplying to said electrically controlled valve means control output signals, said control means being adapted to count the output signals in synchronism with the rotation of the engine from a time when the engine starts and when the engine speed exceeds a predetermined value and to supply control output signals to said electrically controlled valve means independent of the output signal of the sensor means before a counted value of the output signal in synchronism with the rotation of the engine counted during a time period in which the engine speed exceeds the predetermined value satisfies a present value and to supply control output signals in response to the output signal of said sensor means after said counted value satisfies said preset value.

Claim 7

A control system for controlling an air/fuel ratio of a fuel-air mixture to an internal combustion engine, the control system comprising: means for producing output signals indicative of an operating condition of the engine including an output signal in synchronism with a rotation of the engine and an output signal representing a temperature of a coolant of the engine; a sensor means provided in an exhaust system of the engine for generating an output signal in accordance with an oxygen concentration in exhaust gas from the engine; electrically controlled valve means for controlling the air/fuel ratio of the air-fuel mixture supplied to the engine; control means for supplying to said electrically controlled valve means control output signals, said control means being adapted to count the output signals in synchronism with the rotation of the engine from a time when the engine starts and when the engine speed exceeds a predetermined value and to supply control output signals to said electrically controlled valve means independent of the output signal of the sensor means before a counted value of the output signal in synchronism with the rotation of the engine counted during a time period in which the engine speed exceeds the predetermined value satisfies a present value and to supply control output signals in response to the output signal of said sensor means after said counted value satisfies said preset value.

Claim 8

A control system according to claim 5, wherein said control means sets the counted value of the signal in synchronism with the rotation of the engine at zero if the counted valve does not reach the preset value during the time period in which the engine speed is above the predetermined value.

Claim 9

A control system according to claim 5, wherein said means for producing the output signal in synchronism with the rotation of the engine includes a reference crank angle sensor means for producing a reference output signal, and the reference output signal is counted as the output signal in synchronism with the rotation of the engine.

Claim 10

A control system according to claim 5, wherein said means for producing the signal in synchronism with the rotation of the engine includes a crank angle position sensor means for producing an angle position output signal, said control means is adapted to calculate the the engine speed upon receipt of the angle position output signal.

Claim 11

A control system according to claim 5, wherein said control means is adapted to examine a failure of said sensor means on a basis of whether the output signal of said sensor means reaches a predetermined value in amplitude after the counted value of the output signal in synchronism with the rotation of the engine reaches the preset value.

Claim 12

A control system according to claim 9, further comprising means for indicating a failure of said sensor means examined by said control means.

Claim 13

A control system according to claim 5, wherein said control means is adapted to examine a failure of said means for producing the coolant temperature signal on the basis of whether the coolant temperature output signal reaches a preset value after the counted value of the output signal in synchronism with the rotation of the engine reaches a preset value.

Claim 14

A control system according to claim 11, further comprising means for indicating a failure of said means for producing a coolant temperature output signal examined by said control means.

Claim 15

A control system according to claim 5, wherein said control means includes a central processing unit, a read only memory, and a random access memory.