Method and system for controlling fuel to be supplied from fuel pump to engine

Claim 3

A method of controlling fuel to be supplied from a motor-driven fuel pump to a fuel injection valve for an engine as set forth in claim 1, which further comprises the steps of: (a) detecting the battery voltage; (b) calculating a fuel injection time period correction in accordance with the detected battery voltage; and (c) correcting the basic time period during which the fuel injection valve is kept open by adding the fuel injection time period correction to the basic time period.

Claim 5

A method of controlling fuel to be supplied from a motor-driven fuel pump to a fuel injection valve for an engine as set forth in claim 1, which further comprises a step of returning some fuel to a fuel tank when the pressure of fuel generated by the fuel pump rises beyond a predetermined value.

Claim 6

A method of controlling fuel to be supplied from a motor-driven fuel pump to a fuel injection valve for an engine as set forth in claim 4, which further comprises the steps of : (a) detecting the amount of fuel returned to the fuel tank; (b) calculating a motor-drive correction signal in accordance with the detected amount of fuel returned to the fuel tank; and - (c) modifying the basic motor-drive duty cycle signal by which to drive the fuel pump motor in response to the correction signal to the basic motor-drive duty cycle signal.

Claim 8

A method of controlling fuel to be supplied from a motor-driven fuel pump to a fuel injection valve for an engine as set forth in claim 6, further including the step of smoothing the duty cycle signal to provide an analog signal for driving the fuel pump motor.

Claim 9

A controller for controlling fuel to be supplied from a motor-driven fuel pump to a fuel injection valve for an engine, comprising: (a) a plurality of sensors for detecting engine operating conditions and generating signals corresponding thereto; (b) an input unit to which the signals from said sensors are inputted and providing output signals corresponding thereto; (c) a microcomputer connected to said input unit for receiving said output signal, said microcomputer calculating a basic fuel injection time period during which said fuel injection valve is kept open to inject fuel into the engine and 'a basic motor-drive duty cycle for driving the fuel pump motor to supply fuel from the fuel pump to the fuel injection valve in accordance with the output signals from said input unit; (d) an injector drive unit connected to said microcomputer and said fuel injection valve for outputting a pulse signal to the fuel injection valve, said pulse signal having a pulse width corresponding to the basic fuel injection time period calculated by said microcomputer; and (e) a pump drive unit connected to said microcomputer and said fuel pump motor for outputting a pulse signal with a duty cycle corresponding to the basic motor-drive duty cycle calculated by said microcomputer to the fuel pump motor.

Claim 10

A controller for controlling fuel to be supplied from a motor-driven fuel pump to a fuel injection valve for an engine, comprising: (a) a plurality of sensors for detecting engine operating conditions and generating signals corresponding thereto; (b) an input unit to which the signals from said sensors are inputted and providing output signals corresponding thereto; (c) a microcomputer connected to said input unit for receiving said output signal, said microcomputer calculating a basic fuel injection time period during which said fuel injection valve is kept open to inject fuel into the engine and 'a basic motor-drive duty cycle for driving the fuel pump motor to supply fuel from the fuel pump to the fuel injection valve in accordance with the output signals from said input unit; (d) an injector drive unit connected to said microcomputer and said fuel injection valve for outputting a pulse signal to the fuel injection valve, said pulse signal having a pulse width corresponding to the basic fuel injection time period calculated by said microcomputer; and (e) a pump drive unit connected to said microcomputer and said fuel pump motor for outputting a pulse signal with a duty cycle corresponding to the basic motor-drive duty cycle calculated by said microcomputer to the fuel pump motor.

Claim 11

A controller for controlling fuel to be supplied from a motor-driven fuel pump to a fuel injection valve for an engine as set forth in claim 8, which further comprises a pressure sensor for detecting the fuel pressure in a supply duct disposed between the fuel pump and the fuel injection valve and for generating a pressure signal corresponding thereto and wherein said microcomputer is operative in response to said pressure signal for correcting the calculated basic duty cycle for driving the fuel pump motor.

Claim 12

A controller for controlling fuel to be supplied from a motor-driven fuel pump to a fuel injection valve for an engine as set forth in claim 8, which further comprises a pressure regulator for returning some fuel from the fuel pump to a fuel tank when the fuel pressure in a fuel supply duct disposed between the fuel pump and the fuel injection valve rises beyond a predetermined value.

Claim 13

A controller for controlling fuel to be supplied from a motor-driven fuel pump to a fuel injection valve for an engine as set forth in claim 8, further comprising a smoothing circuit, connected between said pump drive unit and said fuel pump motor for averaging the duty cycle pulse signal from the pump drive unit to produce an analog signal for driving said fuel pump motor, the voltage level of which corresponds to the duty cycle of the received pulse -signal.

Claim 14

The controller of claim 8, wherein said microcomputer generates clock signals and said injector drive unit comprises: (1) a counter for counting the number of clock signals inputted thereto; (2) a register connected to said microcomputer for digitally storing the basic fuel injection time period for which the fuel injection valve is kept open as calculated by said microcomputer; (3) a comparator connected to said counter and register for comparing the counted number of clock signals of said counter with the stored basic time fuel injection period in said register and for outputting a reset signal when the counted number of clock signals reaches the basic time period; (4) a flip flop connected to said microcomputer for receiving a set signal representative of the engine operating condition and connected to said comparator for receiving said reset signal, said flip-flop outputting a signal to the fuel injection valve, the output signal of said flip-flop being set to a first level upon receipt of said set signal and being reset to a second level upon receipt of said reset signal; and (5) an AND gate connected to receive said clock signals and said flip-flop for outputting the clock signals to said counter only while the output of said flip-flop is at said first level.

Claim 15

The controller of claim 8, wherein said microcomputer generates clock pulses and said pump drive unit comprises: (1) a first counter for counting said clock pulses inputted thereto; (2) a first register connected to said microcomputer for storing a first data calculated by said microcomputer, said first data representative of the period of said pulse signal form the pump drive unit; (3) a first comparator for comparing the number of clock pulses counted by said first . counter with the first data stored in said first register and for outputting a set signal when the counted number is equal to the first data stored in said first register; (4) a second counter for counting the clock pulses inputted thereto; (5) a second register connected to said microcomputer for storing the basic motor-drive duty cycle calculated by said microcomputer; (6) a second comparator connected to said second counter and second register for comparing . the number of clock pulses of said second counter with the basic motor-drive duty cycle stored in said second register and for outputting a reset signal when the counted number of clock pulses reaches the basic motor-drive duty cycle stored in said second register; (7) a flip flop for outputting said pulse signal of said pump drive unit to be applied to the motor of the fuel pump, the output of .said flip flop being set to a first level when said first comparator outputs the set signal thereto and being reset to a second level when said second comparator outputs the reset signal thereto; and (8) an AND circuit for outputting the clock pulses to said second counter only while the output of said flip flop is at said first level.

Claim 16

A controller for controlling fuel to be supplied from a motor-driven fuel pump to a fuel injection valve for an engine as set forth in claim 10, which further comprises a flow-rate sensor for detecting the amount of fuel to be returned from said pressure regulator to the fuel tank, the output of said flow-rate sensor being applied to said pulse input unit for further correcting the duty cycle of the signal to be applied to the motor to drive the fuel pump, said flow-rate sensor being disposed between said pressure regulator and the fuel tank.

Claim 17

A controller for controlling fuel to be supplied from a motor-driven fuel pump to a fuel injection valve for an engine as set forth in claim 8, wherein said microcomputer generates clock pulses and the sensor generates a digital speed signal at.predetermined rotation angles of the engine crankshaft and wherein said imput unit comprises: (a) a first counter connected for counting the digital speed signals inputted thereto; (b) a second counter generating a transfer-clear output signal to said first counter to determine a predetermined pulse count time interval for said first counter, a said second counter counting a predetermined number of clock pulses corresponding to said time interval, and (c) a register connected to said first counter and said microcomputer, said register storing the counted number of speed signals from said first counter and outputting same to said microcomputer, whereby the first counter supplies to the register the number of pulses received within the time interval specified by the second counter and whereby a speed signal is provided to the microcomputer.