Fuel control system for actuating injection means for controlling small fuel flows

• US 4,530,332 A
• Filed: 10/26/1983
• Issued: 07/23/1985
• Est. Priority Date: 10/26/1983
• Status: Expired due to Fees

• Current Assignee: Siemens-Bendix Automotive Electronics LP
• Original Assignee: Allied Corp. (Honeywell International Inc.)
• Inventors: Harvey, Bruce J., Pauwels, Michael A., Laurent, Harold J.
• Primary Examiner(s): Dolinar, Andrew M.
• Application Number:
  US06/545,792
• Time in Patent Office: 636 Days
• Field of Search: 123/478, 123/480, 123/481, 123/487
• US Class Current: 123/481
• CPC Class Codes: F02D 2200/0406 Intake manifold pressure
• CPC Class Codes: F02D 2200/0414 Air temperature
• CPC Class Codes: F02D 41/08 for idling F02D41/06, F02D41/16 take precedence
• CPC Class Codes: F02D 41/187 using a hot wire flow sensor
• CPC Class Codes: F02D 41/266 the computer being backed-up or assisted by another circuit, e.g. analogue
• CPC Class Codes: F02D 41/3005 Details not otherwise provided for

Abstract

A fuel control system for actuating injection means for controlling small fuel flows is described in a microprocessor based engine control system. The short time duration fuel pulses are sensed and the control system processes the skipping of the injection pulses in the opposite direction of cylinder ignition or precesses skipping around the engine. In one example, in every three fuel pulses, one is omitted and the remaining two are increased in time duration. This processing of the fuel pulses allows each cylinder to omit receiving fuel only once in four engine cycles for a four cylinder engine. Other counts may be used providing that the count is not a multiple of a factor of the total number of cylinders. The increased time duration of the fuel pulses allows actuation of the injector in its linear region of operation.

Claims

1. A fuel control system for actuating injection means for controlling small fuel flows in a fuel injected engine having a plurality of cylinders comprising;

signal generating means responsive to a fuel demand condition of the engine for generating a demand signal proportional to the amount of fuel demanded by the engine;

fuel pulse generating means responsive to said demand signal for generating fuel pulses for activating the injection means in a predetermined order of cylinder injection during each engine cycle according to the demands of the engine, said fuel pulses having a time width proportional to the amount of fuel to be injected into the engine;

threshold means for generating a threshold signal indicating a small fuel flow demand for the engine;

comparison means responsive to said demand signal and said threshold signal and operative for generating a pulse skipping signal when said demand signal is less than said threshold signal;

counter means for counting said fuel pulses, said counter means operative to count to a predetermined number and reset said counter means to a beginning count value;

means responsive to said beginning count value and said pulse skipping signal for generating a pulse skipping signal; and

injection actuation means responsive to said fuel pulses and the absence of said pulse skipping signal for actuating the injection means and in the presence of said pulse skipping signal to skip actuating the injection means at a different time during each engine cycle in a predetermined order of skipping, opposite to said predetermined order of cylinder injection.

2. The system of claim 1 additionally including multiplying means responding to said pulse skipping signal to increase the time width of each fuel pulse by a predetermined factor.

3. The system of claim 1 wherein the signal generating means is an absolute manifold pressure sensor located in the intake manifold of the engine responding to the pressure therein.

4. A fuel control system for actuating injection means for controlling small fuel flows to each engine cylinder in a fuel injected engine, the system comprising:

pulse generating means responsive to engine fuel demands for generating fuel pulses having a pulse width proportional to an amount of fuel to be injected;

a counter counting said fuel pulses, said counter having a maximum count equal to the total number of engine cylinders;

means for resetting said counter to a beginning count value when said counter equals said maximum count;

a control signal generator responsive to said engine fuel demand for the engine being in a small fuel flow condition to generate a control signal;

a multiplier responsive to said control signal to increase the pulse width of each of the subsequent said fuel pulses by a predetermined factor; and

injection actuating means responsive to said multiplied fuel pulse and the counter not equal to said beginning count value to actuate the injection means in a predetermined order of cylinder injection and the counter equal to said beginning count value to skip actuating the injector means in an order opposite to the order of cylinder injection.

5. A method of fuel control for actuating injection means for controlling small fuel flows in a fuel injected engine having injection means by means of skipping actuation pulses in an order inversely to the order of cylinder injection, the method comprising the steps of:

sensing the fuel demand of the engine;

generating in response to said sensed engine fuel demand, fuel pulses having a pulse width proportional to an amount of fuel;

counting the fuel pulses;

determining when the count equals a predetermined number and resetting the count to a beginning count value;

comparing the value of said sensed engine fuel demand to a first predetermined value;

generating a control signal when the value of said sensed engine fuel demand is less than the first predetermined value indicating a small fuel flow condition for generating a pulse skipping signal;

multiplying the pulse width of each subsequent fuel pulse in response to said control signal by a predetermined factor; and

then

actuating the injection means at a time determined by the next multiplied fuel pulse in response to said control signal and the count not equal to said beginning count value and skipping actuation of the injection means in response to said control signal and the count equal to said beginning count value thereby processing the skipping of actuation times during each engine cycle in an order inversely to the order of cylinder injection during each engine cycle.

6. The method according to claim 5 wherein the step of sensing the fuel demand comprises the steps of:

sensing the manifold pressure in the intake manifold of the engine; and

then

generating a signal representative of value of the manifold pressure.

7. The method according to claim 5 additionally including the steps of:

generating a second predetermined value having a value equal to the value of the first predetermined value plus an incremental value representing an hysteresis value;

comparing the value of said sensed engine fuel demand with the second predetermined value; and

then

resetting the control signal when the value of said sensed engine fuel demand is greater than the second predetermined value.

8. The method according to claim 5 where in the step of multiplying, the factor equals approximately one hundred fifty percent.

9. A method of fuel control for actuating injection means for controlling small fuel flows in a fuel injected engine, the method comprising the steps of;

generating in response to engine fuel demands, fuel pulses having a pulse width proportional to an amount of fuel to be injected;

counting the fuel pulses to a predetermined number of fuel pulses;

resetting the count to a beginning count value when the count equals a predetermined number of fuel pulses;

generating a control signal when the fuel pulse width is less than a predetermined value indicating that the fuel demand for the engine is in a small fuel flow condition;

multiplying the fuel pulse width by a predetermined factor in response to the control signal; and

then

actuating the injection means with the multiplied fuel pulse and the count not equal to said beginning count value in a predetermined order of cylinder injection and skipping actuating the injection means when the count is equal to said beginning count value thereby processing the skipping of multiplied pulses in an order inversely to the order of cylinder injection.

10. A method for controlling small fuel flows to individual cylinders of an internal combustion engine by means of skipping actuation pulses to fuel injection means in an order opposite from the normal order of actuating the fuel injection means, said method comprising the steps of:

generating fuel pulses according to the demands of the internal combustion engine;

actuating the fuel injection means by each fuel pulse in a predetermined order of cylinder injection;

counting each fuel pulse to a predetermined count;

resetting the count to a beginning count value by the predetermined count;

determining when the fuel demand of the internal combustion engine is less than a predetermined value;

multiplying each fuel pulse by a predetermined factor to increase the length of such fuel pulse in response to the fuel demand being less than a predetermined value; and

then

skipping the actuation of the fuel injection means in an order opposite said predetermined order in the presence of the beginning count value and the determination of the fuel demand being less than the predetermined value whereby the total fuel from the multiplied fuel pulses supplied to the internal combustion engine for a complete engine cycle is substantially equal to the total fuel demand of the engine.