Fuel cut-off control system in fuel injection internal combustion engine with automatic power transmission

Claim 2

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an accelerator pedal to produce a first signal; a second means for deriving the revolution speed of the engine to produce a second signal having a value indicative of said engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fuel injection system for controlling fuel injection quantity and fuel injection timing; fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal and including means for selectively comparing said second signal value with a first lower and a second higher threshold values, said fuel cut-off signal generator being operable in either one of a first state in which said comparing means is activated to compare said second signal value with said first, lower threshold value to resume operation of said fuel injection system to resume fuel supply to the engine when said second signal value becomes lower than said first threshold value, a second state in which said comparing means is activated to compare said second signal value with said second, higher threshold value to disable said fuel injection system when said second signal value exceeds said second threshold value, and a third state in which said comparing means is activated to compare said second signal value with said first threshold value to disable said fuel injection system when said second signal value exceeds said first threshold value; and means for operating said fuel cut-off signal generator in said third state in response to said third signal.

Claim 3

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an accelerator pedal to produce a first signal; a second means for deriving engine revolution speed to produce a second signal having a value indicative of said engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fuel injection system for injecting fuel into the engine; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with predetermined thresholds, said generator being variable between a first state in which said second signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; and means for setting said fuel cut-off signal generator to said third state in response to said third signal.

Claim 4

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an accelerator pedal to produce a first signal; a second means for deriving engine revolution speed to produce a second signal having a value indicative of said engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fuel injection system for injecting fuel into the engine; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with predetermined thresholds, said generator being variable between a first state in which said second signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; and means for setting said fuel cut-off signal generator to said third state in response to said third signal.

Claim 5

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an accelerator pedal to produce a first signal; a second means for deriving engine revolution speed to produce a second signal having a value indicative of the engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fourth means for detecting the load condition on the engine to produce a fourth signal having a value indicative of the engine load condition; a fuel injection system for injecting fuel at a controlled amount and a controlled timing based on said second and fourth signal values; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with predetermined thresholds, said generator being variable between a first state in which said second signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; and means for setting said fuel cut-off signal generator to said third state in response to said third signal.

Claim 6

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an accelerator pedal to produce a first signal; a second means for deriving engine revolution speed to produce a second signal having a value indicative of the engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fourth means for detecting the load condition on the engine to produce a fourth signal having a value indicative of the engine load condition; a fuel injection system for injecting fuel at a controlled amount and a controlled timing based on said second and fourth signal values; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with predetermined thresholds, said generator being variable between a first state in which said second signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; and means for setting said fuel cut-off signal generator to said third state in response to said third signal.

Claim 7

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an accelerator pedal to produce a first signal; a second means for deriving engine revolution speed to produce a second signal having a value indicative of the engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fourth means for detecting the load condition on the engine to produce a fourth signal having a value indicative of the engine load condition; a fuel injection system for injecting fuel at a controlled amount based on said second and fourth signal values, and in synchronism with the engine revolution; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with thresholds, said generator being variable between a first state in which said second signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; and means for receiving said third signal and responsive thereto for setting said fuel cut-off signal generator to said third state after a predetermined period of time after receiving said third signal.

Claim 8

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an accelerator pedal to produce a first signal; a second means for deriving engine revolution speed to produce a second signal having a value indicative of the engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fourth means for detecting the load condition on the engine to produce a fourth signal having a value indicative of the engine load condition; a fuel injection system for injecting fuel at a controlled amount based on said second and fourth signal values, and in synchronism with the engine revolution; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with thresholds, said generator being variable between a first state in which said second signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; and means for receiving said third signal and responsive thereto for setting said fuel cut-off signal generator to said third state after a predetermined period of time after receiving said third signal.

Claim 9

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an accelerator pedal to produce a first signal; a second means for producing a second signal being an engine speed dependent signal having a value variable depending upon the engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fourth means for detecting a load condition on the engine to produce a fourth signal having a value indicative of the engine load condition; a fuel injection system for injecting fuel at a controlled amount and a controlled timing based on said second and fourth signal values; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with predetermined thresholds, said generator being variable between a first state in which said second signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; means for setting said fuel cut-off signal generator to said third state in response to said third signal; and an automative power transmission including a down-shifting means which shifts the transmission down to a lower gear in response to said third signal.

Claim 10

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an accelerator pedal to produce a first signal; a second means for producing a second signal being an engine speed dependent signal having a value variable depending upon the engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fourth means for detecting a load condition on the engine to produce a fourth signal having a value indicative of the engine load condition; a fuel injection system for injecting fuel at a controlled amount and a controlled timing based on said second and fourth signal values; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with predetermined thresholds, said generator being variable between a first state in which said second signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; means for setting said fuel cut-off signal generator to said third state in response to said third signal; and an automative power transmission including a down-shifting means which shifts the transmission down to a lower gear in response to said third signal.

Claim 11

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an acceleration pedal to produce a first signal; a second means for producing a second signal being an engine speed dependent signal having a value variable depending upon the engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fourth means for detecting a load condition of the engine to produce a fourth signal having a value indicative of the engine load condition; a fuel injection system for injecting fuel at a controlled amount based on said second and fourth signal values and synchronously with the engine revolution; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with predetermined thresholds, said generator being variable between a first state in which said signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; means for receiving said third signal and responsive thereto for setting said fuel cut-off signal generator to said third state after a predetermined period of time after receiving said third signal; and an automatic power transmission including a down-shifting means responsive to said third signal to shift the transmission to a lower gear ratio.

Claim 12

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an acceleration pedal to produce a first signal; a second means for producing a second signal being an engine speed dependent signal having a value variable depending upon the engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fourth means for detecting a load condition of the engine to produce a fourth signal having a value indicative of the engine load condition; a fuel injection system for injecting fuel at a controlled amount based on said second and fourth signal values and synchronously with the engine revolution; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with predetermined thresholds, said generator being variable between a first state in which said signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; means for receiving said third signal and responsive thereto for setting said fuel cut-off signal generator to said third state after a predetermined period of time after receiving said third signal; and an automatic power transmission including a down-shifting means responsive to said third signal to shift the transmission to a lower gear ratio.

Claim 13

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an accelerator pedal to produce a first signal; a second means for producing a second signal being an engine speed dependent signal having a value variable depending upon the engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fourth means for detecting a load condition on the engine to produce a fourth signal having a value indicative of the engine load condition; a fuel injection system for injecting fuel at a controlled amount based on said second and fourth signal values and in synchronism with the engine revolution; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with predetermined thresholds, said generator being variable between a first state in which said second signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; means for receiving said third signal and responsive thereto for setting said fuel cut-off signal generator to said third state after a predetermined period of time after receiving said third signal; an automatic power transmission; and down-shifting means, incorporated in said automatic power transmission, for shifting the transmission to a lower gear ratio in response to said third signal.

Claim 14

A fuel cut-off control system for a fuel injection internal combustion engine comprising: a first means for detecting a released position of an accelerator pedal to produce a first signal; a second means for producing a second signal being an engine speed dependent signal having a value variable depending upon the engine revolution speed; a third means for detecting application of a brake to produce a third signal; a fourth means for detecting a load condition on the engine to produce a fourth signal having a value indicative of the engine load condition; a fuel injection system for injecting fuel at a controlled amount based on said second and fourth signal values and in synchronism with the engine revolution; a fuel cut-off signal generator for producing a fuel cut signal to disable said fuel injection system to cut-off fuel supply to the engine in response to said first signal, said fuel cut-off signal generator including means for comparing said second signal value with predetermined thresholds, said generator being variable between a first state in which said second signal value is compared to a first, lower threshold to resume operation of said fuel injection system when said second signal value becomes equal to or less than said first threshold, a second state in which said second signal value is compared to a second, higher threshold to disable said fuel injection system when said second signal value becomes equal to or greater than said second threshold, and a third state in which said second signal value is compared with said first threshold to disable said fuel injection system when said second signal value exceeds said first threshold value; means for receiving said third signal and responsive thereto for setting said fuel cut-off signal generator to said third state after a predetermined period of time after receiving said third signal; an automatic power transmission; and down-shifting means, incorporated in said automatic power transmission, for shifting the transmission to a lower gear ratio in response to said third signal.

Claim 16

The system as set forth in claim 8, which further comprises a holding circuit for holding said third signal to maintain said third signal even when said third means cease to produce said third signal.

Claim 17

The system as set forth in claim 9, wherein said third signal holding circuit is responsive to the trailing edge of said first signal to cease output of the third signal.

Claim 18

The system as set forth in claim 8, which includes a delay circuit interpositioned between said third means and said fuel cut-off signal generator for providing a delay in the operation of said setting means.

Claim 19

The system as set forth in claim 11, which further comprises an engine coolant temperature sensor for detecting the temperature of an engine coolant to produce an engine coolant temperature signal having a value proportional to said engine coolant temperature, and said first and second thresholds are adjusted to accordance with said engine coolant temperature signal value.

Claim 20

The system as set forth in claim 5, 6 or 7, further comprising a comparator for comparing said second signal value and said first threshold, and disabling the down-shifting operation of said down-shifting means when said second signal value is less than said first threshold.

Claim 21

The system as set forth in claim 5, 6 or 7, wherein said down-shifting means is connected to said means for setting said fuel cut-off signal generator such that said setting means becomes operative in response to said third signal with a given delay time after operation of said down-shifting means.

Claim 22

The system as set forth in claim 13, which further comprises an engine coolant temperature sensor for detecting the temperature of the engine coolant to produce an engine coolant temperature signal having a value proportional to said engine coolant temperature, and said first and second thresholds are adjusted in accordance with said engine coolant temperature signal value.

Claim 23

In a fuel injection control system for detecting control parameters and producing a fuel injection pulse with a duty cycle corresponding to a determined fuel injection amount and outputting said fuel injection pulse in synchronism with the engine revolution, a method for controlling fuel cut-off comprising: detecting whether a throttle valve angular position is smaller than a predetermined open angle and producing a first signal in response thereto; producing an engine speed dependent signal having a value variable depending upon the engine revolution speed; deriving engine revolution speed on the basis of said engine speed dependent signal value and producing a second signal having a value indicative of the engine revolution speed; detecting initial application of a brake and producing a third signal in response thereto; producing first, lower and second, higher reference signals respectively having values representative of first, lower and second, upper thresholds; producing a fuel cut-off signal which cuts off fuel supply in response to said first signal; comparing said second signal value with said first reference signal value in the presence of the fuel cut-off signal and ceasing production of the fuel cut-off signal in order to resume fuel supply when said second signal value becomes less than said first reference signal value; comparing said second signal value with said second reference signal value in the absence of the fuel cut-off signal and producing the fuel cut-off signal when said second signal value exceeds said second reference signal value; and comparing said second signal value with said first reference signal in the absence of the fuel cut-off signal and the presence of the third signal and producing the fuel cut-off signal in response to said third signal when said second signal value exceeds said first reference signal value.

Claim 24

In a fuel injection control system for detecting control parameters and producing a fuel injection pulse with a duty cycle corresponding to a determined fuel injection amount and outputting said fuel injection pulse in synchronism with the engine revolution, a method for controlling fuel cut-off comprising: detecting whether a throttle valve angular position is smaller than a predetermined open angle and producing a first signal in response thereto; producing an engine speed dependent signal having a value variable depending upon the engine revolution speed; deriving engine revolution speed on the basis of said engine speed dependent signal value and producing a second signal having a value indicative of the engine revolution speed; detecting initial application of a brake and producing a third signal in response thereto; producing first, lower and second, higher reference signals respectively having values representative of first, lower and second, upper thresholds; producing a fuel cut-off signal which cuts off fuel supply in response to said first signal; comparing said second signal value with said first reference signal value in the presence of the fuel cut-off signal and ceasing production of the fuel cut-off signal in order to resume fuel supply when said second signal value becomes less than said first reference signal value; comparing said second signal value with said second reference signal value in the absence of the fuel cut-off signal and producing the fuel cut-off signal when said second signal value exceeds said second reference signal value; and comparing said second signal value with said first reference signal in the absence of the fuel cut-off signal and the presence of the third signal and producing the fuel cut-off signal in response to said third signal when said second signal value exceeds said first reference signal value.

Claim 25

In a fuel injection control system for detecting control parameters and producing a fuel injection pulse with a duty cycle corresponding to a determined fuel injection amount and outputting said fuel injection pulse in synchronism with the engine revolution, a method for controlling fuel cut-off comprising: detecting whether a throttle valve angular position is smaller than a predetermined open angle and producing a first signal in response thereto; producing an engine speed dependent signal having a value variable depending upon the engine revolution speed; deriving engine revolution speed on the basis of said engine speed dependent signal value and producing a second signal having a value indicative of the engine revolution speed; detecting initial application of brake to produce a third signal; interrupting said first signal for a given period of time in response to said third signal; producing first, lower and second, higher reference signal respectively having values representative of first, lower and second, upper thresholds; producing a fuel cut-off signal to cut-off fuel supply as long as said first signal is present and said second signal value is above said first reference signal value; comparing said second signal value with said first reference signal value in the presence of said fuel cut-off signal and ceasing production of said fuel cut-off signal when said second signal value becomes less than said first reference signal value; comparing said second signal value with said second reference signal value in the absence of said fuel cut-off signal and producing said fuel cut-off signal when said second signal value exceeds said second reference signal value; and comparing said second signal value with said first reference signal value in the absence of the fuel cut-off signal and the presence of the third signal and producing the fuel cut-off signal in response to said third signal when said second signal value exceeds said first reference signal value.

Claim 26

In a fuel injection control system for detecting control parameters and producing a fuel injection pulse with a duty cycle corresponding to a determined fuel injection amount and outputting said fuel injection pulse in synchronism with the engine revolution, a method for controlling fuel cut-off comprising: detecting whether a throttle valve angular position is smaller than a predetermined open angle and producing a first signal in response thereto; producing an engine speed dependent signal having a value variable depending upon the engine revolution speed; deriving engine revolution speed on the basis of said engine speed dependent signal value and producing a second signal having a value indicative of the engine revolution speed; detecting initial application of brake to produce a third signal; interrupting said first signal for a given period of time in response to said third signal; producing first, lower and second, higher reference signal respectively having values representative of first, lower and second, upper thresholds; producing a fuel cut-off signal to cut-off fuel supply as long as said first signal is present and said second signal value is above said first reference signal value; comparing said second signal value with said first reference signal value in the presence of said fuel cut-off signal and ceasing production of said fuel cut-off signal when said second signal value becomes less than said first reference signal value; comparing said second signal value with said second reference signal value in the absence of said fuel cut-off signal and producing said fuel cut-off signal when said second signal value exceeds said second reference signal value; and comparing said second signal value with said first reference signal value in the absence of the fuel cut-off signal and the presence of the third signal and producing the fuel cut-off signal in response to said third signal when said second signal value exceeds said first reference signal value.

Claim 27

In a fuel injection control system for detecting control parameters and producing a fuel injection pulse with a duty cycle corresponding to a determined fuel injection amount and outputting said fuel injection pulse synchronously with the engine revolution, a method for controlling fuel cut-off comprising: detecting whether a throttle valve angular position is smaller than a predetermined open angle and producing a first signal in response thereto; producing an engine speed dependent signal having a value variable depending upon the engine revolution speed; deriving engine revolution speed on the basis of said engine speed dependent signal value and producing a second signal having a value indicative of the engine revolution speed; detecting initial application of a brake to produce a third signal; producing first, lower and second, higher reference signals respectively having values representative of first, lower and second, upper thresholds; producing a fuel cut-off signal to cut-off fuel supply in response to said first signal; comparing said second signal value with said first reference signal value in the presence of said fuel cut-off signal and ceasing to produce said fuel cut-off signal when said second signal value becomes less than said first reference signal value; comparing said second signal value with said second reference signal value in the absence of said fuel cut-off signal and producing said fuel cut-off signal when said second signal value exceeds said second reference signal value; comparing said second signal value with said first reference signal value in the absence of said fuel cut-off signal and in the presence of said third signal and producing said fuel cut-off signal in response to said third signal when said second signal value exceeds said first reference signal value; and shifting an automatic power transmission to a lower gear ratio in response to said third signal.

Claim 28

In a fuel injection control system for detecting control parameters and producing a fuel injection pulse with a duty cycle corresponding to a determined fuel injection amount and outputting said fuel injection pulse synchronously with the engine revolution, a method for controlling fuel cut-off comprising: detecting whether a throttle valve angular position is smaller than a predetermined open angle and producing a first signal in response thereto; producing an engine speed dependent signal having a value variable depending upon the engine revolution speed; deriving engine revolution speed on the basis of said engine speed dependent signal value and producing a second signal having a value indicative of the engine revolution speed; detecting initial application of a brake to produce a third signal; producing first, lower and second, higher reference signals respectively having values representative of first, lower and second, upper thresholds; producing a fuel cut-off signal to cut-off fuel supply in response to said first signal; comparing said second signal value with said first reference signal value in the presence of said fuel cut-off signal and ceasing to produce said fuel cut-off signal when said second signal value becomes less than said first reference signal value; comparing said second signal value with said second reference signal value in the absence of said fuel cut-off signal and producing said fuel cut-off signal when said second signal value exceeds said second reference signal value; comparing said second signal value with said first reference signal value in the absence of said fuel cut-off signal and in the presence of said third signal and producing said fuel cut-off signal in response to said third signal when said second signal value exceeds said first reference signal value; and shifting an automatic power transmission to a lower gear ratio in response to said third signal.

Claim 29

In a fuel injection control system for detecting control parameters and producing a fuel injection pulse with a duty cycle corresponding to a determined fuel injection amount and outputting said fuel injection pulse in synchronism with the engine revolution, a method for controlling fuel cut-off comprising: detecting whether a throttle valve angular position is smaller than a predetermined open angle and producing a first signal in response thereto; producing an engine speed dependent signal having a value variable depending upon the engine revolution speed; deriving engine revolution speed on the basis of said engine speed dependent signal value and producing a second signal having a value indicative of the engine revolution speed; detecting initial application of a brake and producing a third signal in response thereto; interrupting said first signal for a given period of time in response to said third signal; producing first, lower and second, higher reference signals respectively having values representative of first, lower and second, upper thresholds; producing a fuel cut-off signal to cut-off fuel supply as long as said first signal is present and said second signal value exceeds said first reference signal value; comparing said second signal value with said first reference signal value in the presence of said fuel cut-off state and ceasing production of said fuel cut-off signal when said second signal value becomes less than said first reference signal value; comparing said second signal value with said second reference signal value in the absence of said fuel cut-off signal and producing said fuel cut-off signal when said second signal value exceeds said second reference signal value; comparing said second signal value with said first reference signal value in the absence of the fuel cut-off signal in response to said third signal when said second signal value exceeds said first reference signal value; and shifting an automatic power transmission to a lower gear ratio in response to said third signal.

Claim 30

In a fuel injection control system for detecting control parameters and producing a fuel injection pulse with a duty cycle corresponding to a determined fuel injection amount and outputting said fuel injection pulse in synchronism with the engine revolution, a method for controlling fuel cut-off comprising: detecting whether a throttle valve angular position is smaller than a predetermined open angle and producing a first signal in response thereto; producing an engine speed dependent signal having a value variable depending upon the engine revolution speed; deriving engine revolution speed on the basis of said engine speed dependent signal value and producing a second signal having a value indicative of the engine revolution speed; detecting initial application of a brake and producing a third signal in response thereto; interrupting said first signal for a given period of time in response to said third signal; producing first, lower and second, higher reference signals respectively having values representative of first, lower and second, upper thresholds; producing a fuel cut-off signal to cut-off fuel supply as long as said first signal is present and said second signal value exceeds said first reference signal value; comparing said second signal value with said first reference signal value in the presence of said fuel cut-off state and ceasing production of said fuel cut-off signal when said second signal value becomes less than said first reference signal value; comparing said second signal value with said second reference signal value in the absence of said fuel cut-off signal and producing said fuel cut-off signal when said second signal value exceeds said second reference signal value; comparing said second signal value with said first reference signal value in the absence of the fuel cut-off signal in response to said third signal when said second signal value exceeds said first reference signal value; and shifting an automatic power transmission to a lower gear ratio in response to said third signal.

Claim 32

The method as set forth in claim 16 or 18, which further comprises the step of comparing said second signal value with said first reference signal value to produce an enabling signal for enabling said step of comparing in the presence of said third signal when said second signal value exceeds said first reference signal value.

Claim 33

The method as set forth in claim 17 or 19, which further comprises the step of comparing said second signal value with said first reference signal value to produce an enabling signal for enabling said interruption of said first signal when said second signal value exceeds said first reference signal value.

Claim 34

The method as set forth in claim 21, wherein said step of comparing in the presence of said third signal is performed after a given delay time after production of said third signal.

Claim 35

The method as set forth in claim 22, wherein said interruption of said first signal in response to said third signal is performed after a given delay time after production of said third signal.

Claim 37

A fuel cut-off control method for an internal combustion engine in an automotive vehicle with a fuel injection system which performs fuel injection into the engine and which ceases to perform fuel injection in the presence of a fuel cut-off signal S C , the method comprising the steps of: (a) deriving the revolution speed of the engine; (b) producing a deceleration signal when engine operating conditions are conducive to engine braking; (c) comparing the measured engine speed to a first threshold speed; (d) producing the fuel cut-off signal when the measured engine speed is below the first threshold speed and the deceleration signal is produced; (e) comparing the measured engine speed to a second threshold speed lower than the first threshold speed; (f) preventing production of the deceleration signal, so as to allow the fuel injection system to resume fuel injection, when the measured engine speed is below the second threshold speed; the step of producing the deceleration signal comprising the steps of monitoring the state of engine load and vehicle braking and producing the deceleration signal when the vehicle is in a substantially no engine load state and no vehicle braking state.

Claim 38

A fuel cut-off control method for an internal combustion engine in an automotive vehicle with a fuel injection system which performs fuel injection into the engine and which ceases to perform fuel injection in the presence of a fuel cut-off signal S C , the method comprising the steps of: (a) deriving the revolution speed of the engine; (b) producing a deceleration signal when engine operating conditions are conducive to engine braking; (c) comparing the measured engine speed to a first threshold speed; (d) producing the fuel cut-off signal when the measured engine speed is below the first threshold speed and the deceleration signal is produced; (e) comparing the measured engine speed to a second threshold speed lower than the first threshold speed; (f) preventing production of the deceleration signal, so as to allow the fuel injection system to resume fuel injection, when the measured engine speed is below the second threshold speed; the step of producing the deceleration signal comprising the steps of monitoring the state of engine load and vehicle braking and producing the deceleration signal when the vehicle is in a substantially no engine load state and no vehicle braking state.

Claim 39

The fuel cut-off control method of claim 26, wherein the engine is equipped with an automatic power transmission and further comprising the step of shifting the automatic transmission into the next lower gear when the vehicle operator requests vehicle braking.

Claim 40

The fuel cut-off control method of either of claims 26 or 27, further comprising the steps of measuring engine temperature and adjusting the first and second threshold speeds in accordance with the measured engine temperature.

Claim 41

The fuel cut-off control method of either of claims 26 or 27, further comprising the step of producing the deceleration signal S G within a predetermined period of time after the vehicle operator requests vehicle braking when the vehicle operator requests substantially no engine load.

Claim 42

The fuel cut-off control method of either of claims 26 or 27, wherein after the deceleration signal S G has been initially produced, the deceleration signal S G is continuously produced as long as the vehicle operator requests substantially no engine load.

Claim 43

The fuel cut-off method of either of claims 26 or 27, wherein said step of monitoring engine load requested by the vehicle operator comprises the step of detecting the position of an accelerator pedal of the engine and recognizing that the vehicle operator requests substantially no engine load when the accelerator pedal is in a released position.

Claim 44

The fuel cut-off method of either of claims 26 or 27, wherein said step of monitoring engine load requested by the vehicle operator comprises the step of detecting the position of a throttle valve of the engine and recognizing that the vehicle operator requests substantially no engine load when the throttle valve is substantially closed.

Claim 45

A fuel cut-off control system for an internal combustion engine in an automotive vehicle equipped with automatic power transmission and a fuel injection system, which can be selectably disabled by a fuel cut-off signal, the system comprising: (a) a first sensor producing an engine speed related signal having value variable depending upon engine speed and deriving engine revolution speed on the basis of said engine speed related signal values for outputting an engine speed signal indicative thereof; (b) a brake sensor for monitoring the vehicle brake system and outputting a brake signal when the vehicle brakes are actuated by the vehicle operator; (c) an accelerator pedal switch associated with an accelerator pedal of the vehicle for outputting a coasting signal when the accelerator pedal is in a released position corresponding to substantially no load demand on the engine; (d) a deceleration signal generator responsive to the coasting signal, and said deceleration signal generator being responsive to the brake signal for outputting a deceleration signal irrespective of the coasting signal; (e) a fuel cut-off means responsive to the engine speed signal and the deceleration signal for starting to output the fuel cut-off signal when the engine speed signal level exceeds a first threshold level and the deceleration is present and continuing to output the fuel cut-off signal as long as the deceleration signal is present and the engine speed signal level exceeds a second threshold level representing a lower engine speed than the first threshold level.

Claim 46

A fuel cut-off control system for an internal combustion engine in an automotive vehicle equipped with automatic power transmission and a fuel injection system, which can be selectably disabled by a fuel cut-off signal, the system comprising: (a) a first sensor producing an engine speed related signal having value variable depending upon engine speed and deriving engine revolution speed on the basis of said engine speed related signal values for outputting an engine speed signal indicative thereof; (b) a brake sensor for monitoring the vehicle brake system and outputting a brake signal when the vehicle brakes are actuated by the vehicle operator; (c) an accelerator pedal switch associated with an accelerator pedal of the vehicle for outputting a coasting signal when the accelerator pedal is in a released position corresponding to substantially no load demand on the engine; (d) a deceleration signal generator responsive to the coasting signal, and said deceleration signal generator being responsive to the brake signal for outputting a deceleration signal irrespective of the coasting signal; (e) a fuel cut-off means responsive to the engine speed signal and the deceleration signal for starting to output the fuel cut-off signal when the engine speed signal level exceeds a first threshold level and the deceleration is present and continuing to output the fuel cut-off signal as long as the deceleration signal is present and the engine speed signal level exceeds a second threshold level representing a lower engine speed than the first threshold level.

Claim 47

The system of claim 33, further comprising an engine temperature sensor for outputting a temperature signal S w indicative of engine temperature, and means responsive to the temperature signal for adjusting the first and second threshold levels in accordance with engine temperature as indicated by the temperature signal.

Claim 48

The system of claim 34, further comprising means responsive to the brake signal for shifting the automatic transmission into the next lower gear.

Claim 49

The system of claim 34, further comprising means for delaying the output of the brake signal by a predetermined period of time.

Claim 50

The system of claim 35, further comprising means for delaying the output of the brake signal for a period of time approximating the response time of said shifting means.

Claim 52

The system of claim 38, wherein the deceleration signal generator further comprises an OR gate receiving as inputs the output of said multivibrator and the fuel cut-off signal and the output of which is inputted to said AND gate.