JPH0361012B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a fuel control system for internal combustion engines, and in particular to provide maximum fuel economy for marine internal combustion engines under all engine operating conditions. The present invention relates to a self-adjusting fuel control system.

[Prior Art] Maximum fuel economy (minimum fuel efficiency) is now the primary objective of internal combustion engine designers in view of the recent rise in gasoline prices.

A common practice in the design and calibration of fuel supply systems in internal combustion engines is to predetermine the fuel supply as a function of the engine operating conditions measured for the engine in operation. In carbureted engines, the main measurement function is generally the ventilator pressure, the fuel delivery rate being determined firstly by this pressure (or the drop in air pressure), and secondly by the rpm, manifold pressure. It is determined by measuring various engine functions such as vacuum, air flow, throttle position, etc.

Fuel control systems of the type described above rely heavily on empirical knowledge of how the engine operates under all possible conditions of load and environment. Although such devices are relatively complex and expensive, they only obtain optimal performance in terms of fuel economy under a limited range of operating conditions.

Accordingly, it is an object of the present invention to provide a self-adjusting fuel control system that does not require economic knowledge of engine performance.

The self-regulating fuel control system itself is already known and described in the publication “Princes of Optimalizing Control Systems”.
End the Application to the Internal Combustion Engine,” American Society of Mechanical Engineers, 1951 (“Principles of Optimalizing
Control Systems and the Application to the
Internal Combustion Engine”, American
Society of Mechanical Engineers, 1951.) Draper and Li. However, the Draper and Lee system is designed to provide maximum power (maximum rpm) at all throttle positions and does not provide maximum fuel economy. Maximum fuel economy is near misfire due to lack of fuel and not at maximum rpm.

Accordingly, another object of the invention is to provide maximum fuel economy for all throttle positions on an internal combustion engine.

A self-adjusting fuel control system that provides maximum fuel economy is disclosed in U.S. Application No. 2, filed September 25, 1981
No. 305900, H. E. Riodan (HE
“Programmable Fuel Economy Optimizer for an Internal Combustion Engine” by Riordan)
(“Programmable Fuel Economy Optimizer
For an Internal Combustion Engine" and assigned to the same assignee as the present invention.

PROBLEM TO BE SOLVED BY THE INVENTION The Riodan fuel economy optimization system provides maximum fuel economy by determining the ratio of speed changes to changes in fuel delivery and reduces engine starvation under deceleration. Sense the breaking point. This method is not suitable for all types of two-stroke engines, although it has many advantages in that it does not require economic knowledge for the fuel control system.

Yet another object of the present invention is to provide a self-adjusting fuel control system that is effective on all engine types.

Another object of the present invention is to provide a self-adjusting fuel control system that provides an accurate range of fuel mixture variations.

Another object of the present invention is to provide a self-adjusting fuel control system with high temperature stability.

SUMMARY OF THE INVENTION A fuel control system according to the present invention provides maximum fuel economy over a wide range of engine throttle conditions for marine internal combustion engines. storage means for storing a fuel control signal; means for reducing the magnitude of the stored fuel control signal in response to the operating rpm of the internal combustion engine reaching a steady state; and the moment of the stored fuel control signal. fuel control means for controlling the amount of fuel delivered to the internal combustion engine so as to reduce the fuel/air ratio of the internal combustion engine when the stored fuel control signal decreases; a steady state rpm signal representative of said steady state operating rpm of the internal combustion engine and decreasing current operating of the internal combustion engine;
a first comparing means for comparing the current operating rpm signal representing the rpm; and in response to the first comparing means, the current operating rpm signal;
means for increasing the magnitude of the stored fuel control signal in the storage means when the rpm signal falls below the steady state rpm signal by a predetermined value.

Further, a method of increasing fuel efficiency according to the present invention is a method for increasing fuel efficiency in operation of a marine internal combustion engine for a given one of a plurality of engine throttle settings, which includes: increasing the engine rpm from the steady state value by increasing the rpm signal value corresponding to the steady state value; monitoring a decrease in the operating rpm of the internal combustion engine with respect to the value of an rpm signal, and determining that the operating rpm of the internal combustion engine is equal to the stored r.
and enriching the fuel in the air/fuel ratio by a predetermined value when the value of the pm signal decreases by a predetermined value.

[Operation] According to the present invention, the internal combustion engine has a fuel supply amount vs. r.
Operating at or near a preselected point on the pm curve, this preselected operating point provides maximum fuel economy during engine operation.

A feature of the present invention maintains engine operation at or near a predetermined operation by sampling fuel mixture ratio and engine rpm during or near steady state operating conditions.

Yet another feature of the invention is to dilute the fuel mixture ratio after reaching steady state conditions and to
Decrease the rpm to a first predetermined value.

Still other features of the invention increase the fuel mixture ratio to a second predetermined value when engine rpm decreases to a first predetermined value. The second predetermined value is less than an intentional departure from steady state conditions, thereby causing engine RP
m. is increased again to the new steady state condition.

[Example] Next, an example of the present invention will be described with reference to the attached drawings.

For a given engine running with a load connected, the fuel delivery versus rpm curve is:
It is known that for any given throttle position, the lean side of the curve exhibits a relatively constant shape. The fuel control system of the present invention takes advantage of this phenomenon and constantly maintains the fuel supply rate close to this shortage limit while avoiding misfires. Since maximum fuel economy occurs near this starvation point, the present invention is capable of achieving maximum fuel economy under all engine operating conditions.

FIG. 1 shows typical fuel delivery versus rpm curves for several engine throttle opening settings. Points a , b and c on the top curve correspond to fuel shortage,
It shows near maximum fuel economy and maximum power. If you go to the right along each curve, there will be excess fuel and power loss will occur. The fuel control system of the present invention locates the fuel supply vs. rpm curve slightly to the right of point b , where the slope of the curve is always positive but the offset from the depletion limit point and misfire is sufficient to provide smooth running. It acts to operate the internal combustion engine in the range of . The operating range just to the right of point b in the present invention provides maximum fuel economy, is compatible with all engine types, and has high stability over a wide temperature range.

FIG. 2 shows the fuel control system of the present invention. This device detects the initial steady state engine rpm
sample and reduce the amount of fuel supplied until the engine rpm drops to a predetermined amount, e.g.
%, sample the engine rpm again, and repeat the process to give optimal fuel economy. The essential feature of circuit operation is that the circuit senses the under-point of engine operation under finite rpm loss.
m. Sampling and fuel supply amount sampling.

Referring to FIG. 2, engine rpm information in the form of a tachometer signal is applied to terminal 100. The tachometer signal is a DC level signal, where a high level DC signal indicates high rpm, and a low level DC signal indicates low rpm. The tachometer signal is applied to comparators 107 and 112, sample and hold circuit 104, and to terminal 148.

A fuel control signal (E'fc) used to provide fuel mixture ratio information to the internal combustion engine is connected to terminal 1.
42 to the engine. This signal is a modified version of the input fuel control signal Efc applied to the circuit of FIG. 2 through terminal 141.
The input fuel control signal is a DC level signal generated by a resistive network (not shown). The dc level of the input fuel control signal is modified by the output signal of operational amplifier 136 in a manner described below. dc
The level-changed fuel control output signal is applied to a pulse generation circuit (not shown) that controls a fuel supply control device (not shown), such as a fuel injector or carburetor having an electrical control means. Signal E′fc
Decreasing the dc level of the signal E′fc results in adding a leaner fuel mixture to the internal combustion engine and reducing the dc level of the signal E′fc.
It is understood that increasing the level results in adding a rich combustion mixture to the internal combustion engine.

The circuit shown in Figure 2 is designed to maintain engine rpm for a given time for any throttle setting.
It is designed to provide conditions for accelerating to.
Once this "steady state" engine rpm level is reached, the circuit samples the engine rpm and fuel mix ratio to provide maximum fuel economy. When we first consider the acceleration phase, we assume that the internal combustion engine in question is at steady r.p.m. for a particular throttle setting.
Assume that it is accelerated to pm. During acceleration, a high level dc tachometer signal is applied to capacitor 108.
is applied to the "+" terminal of comparator 112 via . Resistance 109, 110
Because of the bias network consisting of An output signal is output. This high level signal charges capacitor 135 through diode 134 during acceleration.

The dc tachometer signal is also applied to the "-" input of comparator 107. The switch 104 is similar to the switches 125, 126 and 143 as well.
A CMOS sample and hold switch,
It is open (off) when the voltage at the c (control) input is less than about 3 volts, and open (on) when the c input is greater than 6 volts. Switch 1 during acceleration
04 is on and applies the tachometer signal to the "+" input of the comparator 107. The magnitude of the tachometer signal at the “-” input of the comparator 107 is determined by the resistances 102 and 10.
3 and 105 is greater than the magnitude of the tachometer signal at the "+" input of comparator 107. Therefore, the dc output signal level of comparator 107 is low during acceleration. The low signal level output of comparator 107 turns off switch 126, which in turn outputs a high level voltage (VDD).
is applied to the c terminal of switch 143, this switch is turned on, and the output signal from comparator 136 is applied to the "+" terminal of comparator 145 and capacitor 144, so that this capacitor increases E′fc. It will be charged like this.

Because of the bias network consisting of resistors 137 and 139, the output of operational amplifier 136 follows the voltage level at the "+" input terminal of this amplifier and is slightly greater than the voltage (Ec) appearing at capacitor 135. However, the output of amplifier 136 is limited in value to the voltage appearing at terminal 141, ie, the voltage level of input fuel control signal Efc.
During acceleration, the voltage across capacitor 135 (Ec) is
It increases until it exceeds Efc, and at this time, comparator 1
The output of the comparator 145 becomes low when the voltage magnitude (Ed) at the "+" terminal of the comparator 145 exceeds the voltage magnitude (Ec) at the "-" terminal of the comparator 145. The low output of amplifier 145 turns off transistor 124 and forces the c terminal of sample and hold circuit 104 to a high voltage level.

As acceleration progresses, capacitor 106 begins to charge with the high level output signal of sample and hold circuit 104. The charge stored in capacitor 106 represents engine rpm as a sample of tachometer signal E'T.

Acceleration results in a steady state rpm level, defined as the engine speed at which the dc level of the tachometer signal remains constant for a period of approximately 10 seconds. When steady state rpm is reached, the tachometer signal applied to the "-" terminal of comparator 112 exceeds the magnitude of the tachometer signal applied to the "+" terminal of comparator 112 through capacitor 108. When this happens, comparator 1
The output of 12 turns to the lower side, and the capacitor 135
begins to discharge through transistor 120, resistor 121 and the output of amplifier 107, which is now at a low level.

When the capacitor 135 continues to discharge, the charge (Ed) appearing on the capacitor 144 is transferred to the capacitor 13.
A point is reached where the charge (Ec) appearing at 5 is exceeded.
When this occurs, the output of comparator 145 goes high, turning on transistor 124 and placing sample and hold switch 104 in the hold mode. At this point, capacitor 106 is charged to a value representing a new level of steady state rpm of the engine, which value is applied to sample and hold circuit 104.
is held while in hold mode.

Now, once the engine reaches steady state rpm,
The fuel mixture ratio is decreased until the engine rpm drops to a predetermined amount. During decreasing circuit operation, capacitor 135 continues to discharge as described above, and the output of amplifier 136 (E′fc)
The value is decreased in accordance with the decrease in charge appearing at 35. This decreasing signal is applied to terminal 142 and
From there it is applied to the fuel control system (not shown) to reduce the fuel mixture ratio applied to the internal combustion engine. When the fuel mixture ratio decreases continuously,
Engine rpm begins to drop.

As previously discussed, when steady state rpm is reached, sample and hold circuit 104 enters a hold mode and the charge appearing on capacitor 106 continues to represent the steady state rpm. This voltage value (Ed) is applied to the “+” input of comparator 107. When engine rpm decreases, comparator 10
The magnitude of the tachometer signal applied to 7 "-" units also decreases until it reaches the voltage value stored in capacitor 106 (Eb). The amount of reduction in engine rpm required to reach this point can be easily predetermined by appropriately selecting the values of resistors 101, 102, 103, and 154.
A typical reduction in engine rpm in one embodiment of the invention is 50 rpm.

When the engine rpm drops to a predetermined amount, the output of comparator 107 goes high and begins to increase the engine fuel mixture ratio. This high value output signal is applied to the sample and hold circuit 126, which acts as an inverter, and applies a low level signal to the control terminal of the sample and hold circuit 143.
Put this circuit into hold mode. When this occurs, the previous value of signal E'fc is transferred to capacitor 144.
(Ed). This represents the value at which the internal combustion engine decelerates after reaching the steady state rpm mentioned above.

The high level output of comparator 107 is also applied to transistor 119 and transistor 124. The application of a high level signal to transistor 119 causes capacitor 135 to begin charging through transistor 119 . When the voltage (Ec) appearing on capacitor 135 increases, the output of amplifier 136 increases correspondingly. This increasing signal is applied to terminal 142 and from there to the fuel control system (not shown), which begins increasing the fuel mixture ratio applied to the internal combustion engine. As the fuel mixture ratio increases, engine rpm begins to increase. Applying a high level output signal from comparator 107 to transistor 124 turns off the transistor, which returns sample and hold circuit 104 to sample mode, and capacitor 106 samples increasing engine rpm in the manner previously described. Begin to.

The fuel mixture ratio continues to increase and the engine rpm,
The charge appearing on capacitor 135 (Ec) continues to increase until it exceeds the charge (Ed) stored before appearing on capacitor 144. The amount by which the fuel mixture ratio is increased is determined by the gain of amplifier 136, and is preferably 3%. When the mix ratio increases by 3%, the output of comparator 145 goes low and enters the next decreasing cycle in the manner described above.

Referring now to Figures 3A-3F, the fuel control circuit of the present invention has been detailed above and is shown over a series of discrete time periods (1-5). Period 1 is the internal combustion period for a particular throttle setting.
This is the initial acceleration period during which the steady state rpm increases. During this period, the voltage (Ec) appearing on capacitor 135 rises to VDD (FIG. 3D) and then decreases in level.

Steady state rpm is achieved in period 2, when the voltage Ec begins to decrease in the manner described above, reducing the fuel mixture ratio applied to the internal combustion engine. Voltage
When Ec decreases below the level of the voltage appearing on capacitor 144 (voltage Ed, Figure 3D), the output of amplifier 145 goes high (Figure 3E) and switch 104 goes into hold mode (Figure 3C). The reduction in engine fuel mixture ratio continues until the engine rpm drops to a predetermined amount (Figure 3D).

This drop in engine rpm is shown in FIG. 3A as voltage Ea (the "-" input of comparator 107) drops below voltage Eb (the "+" input of comparator 107).

Period 2 transitions to period 3 when the engine rpm drops to a predetermined amount. At this time, 1
04 goes into sample mode (Figure 3C), 14
3 goes into hold mode (Figure 3F), the output of comparator 107 goes high (Figure 3B), Ec starts to increase (Figure 3D), the fuel mixture ratio increases, and the engine rpm increases. .

Engine rpm continues to increase until voltage Ec reaches the value of voltage Ed at the boundary between periods 3 and 4 (Figure 3D). At this time, the output of comparator 107 goes low (Figure 3B), 104 goes into hold mode (Figure 3C), the output of comparator 145 goes low (Figure 3E), and voltage Ec begins to decrease ( 3rd D
), thereby entering another reduction cycle as described above.

Period 5 repeats the operations of Period 3, and this process of selected speed sampling and continuous rate sampling continues as long as the engine maintains the same throttle setting.

The circuit of Figure 2 is designed for maximum fuel economy for any given throttle setting over a wide range of operating rpm; is not intended to control. In particular, at idle, the tachometer signal applied to terminal 148 causes the output of comparator 112 to be low so as to stop the automatic circuit operation described. Similarly, at very large throttle openings (greater than 50%), element 125 opens, closing comparator 107 and inhibiting the reduction cycle described above. The remaining elements shown in Figure 2 not referenced in the foregoing discussion are standard bias and voltage divider networks, the functions of which will be clearly understood by those skilled in the art. Therefore, I will not explain it in detail.

Although specific embodiments of the invention have been described, it will be understood that various modifications may be made without departing from the spirit of the invention.

Advantages of the Invention As is clear from the foregoing description, the present invention provides maximum fuel economy for any throttle setting over a wide range of operating rpm.

[Brief explanation of drawings]

Figure 1 shows a typical fuel supply versus rpm curve for an internal combustion engine, and Figure 2 shows a variation of the curve in Figure 1.
3 is a schematic illustration of the circuit of the present invention for maintaining the engine operating at or near the preselected point shown above, and FIG. 3 shows various waveforms appearing during operation of the circuit of FIG. shows. 100...Tachometer signal input terminal, 101,
102, 103... Resistor, 104... Sample and hold circuit, 105... Resistor, 106... Capacitor, 107... Comparator, 108... Capacitor, 109, 110, 111... Resistor, 112
... Comparator, 113 ... Resistor, 114, 115 ...
...Diode, 116,117,118...Resistor, 119,120...Transistor, 121,
122...Resistor, 124...Transistor, 12
5,126...sample and hold switch,
127...Diode, 129...Resistor, 13
0,131...Diode, 132,133...
Resistor, 134...Diode, 135...Capacitor, 136...Operation amplifier, 137, 138,
139, 140...Resistor, 141...Fuel control signal input terminal, 142...Fuel control signal input terminal,
143...Sample and hold switch, 14
4... Capacitor, 145... Comparator, 146...
...Diode, 147...Resistor, 148...Terminal, 149,150...Resistor, 151...Capacitor, 152,153,154...Resistor.

Claims (1)

[Scope of Claims] 1. A fuel control system that provides maximum fuel economy over a wide range of engine throttle conditions for a marine internal combustion engine, comprising: storage means for storing a fuel control signal of a magnitude related to the operating rpm of the internal combustion engine; means for decreasing the magnitude of the stored fuel control signal in response to the operating rpm of the internal combustion engine reaching a steady state; and in response to the instantaneous decreasing magnitude of the stored fuel control signal; fuel control means for controlling fuel delivery to the internal combustion engine to reduce the fuel/air ratio of the internal combustion engine when the stored fuel control signal decreases; and representing the steady state operating rpm of the internal combustion engine. Steady state rpm signal and decreasing current operation of an internal combustion engine
a first comparing means for comparing the current operating rpm signal representing the rpm; and in response to the first comparing means, the current operating rpm signal;
means for increasing the magnitude of the stored fuel control signal of the storage means when the rpm signal falls below the steady state rpm signal by a predetermined value. 2. A first sample for sampling the current operating rpm signal while the operating rpm of the internal combustion engine is increasing and holding the value of the current operating rpm signal while the stored fuel control signal is decreasing. and the first claim including the holding means.
Fuel control device as described in section. 3. Claim comprising second comparison means for comparing the decreasing magnitude of the stored fuel control signal to a value of the fuel control signal corresponding to fuel consumption at the steady state operating rpm of the internal combustion engine. 1. The fuel control device according to item 1. 4. The fuel control device according to claim 3, further comprising second sample and hold means for sampling the fuel control signal and holding the value of the fuel control signal. 5 The current operating rpm signal is the steady state rpm signal.
2. The fuel control system of claim 1, wherein said predetermined value below the m. signal corresponds to a decrease of about 50 rpm. 6. The fuel control system of claim 1, wherein said increase in said magnitude of said stored fuel control signal corresponds to an increase of about 3%. 7. A method of increasing fuel efficiency in the operation of a marine internal combustion engine for a given one of a plurality of engine throttle settings, comprising: increasing the operating rpm of the internal combustion engine to a steady state value; storing a value of an rpm signal corresponding to a value of the rpm signal; leans the air/fuel ratio of the internal combustion engine to reduce engine rpm from the steady state; and determining the operation of the internal combustion engine with respect to the stored rpm signal value. Monitoring the decrease in rpm, the operating rpm of the internal combustion engine is the stored r.
A method for increasing fuel efficiency comprising the step of enriching the air/fuel ratio by a predetermined value when the value of the pm signal decreases by a predetermined value. 8. The predetermined value at which the operating rpm of the internal combustion engine falls below the value of the stored rpm signal before execution of the fuel enrichment step corresponds to a decrease of about 50 rpm. A method for increasing fuel efficiency according to scope item 7. 9. The method of claim 7, wherein the predetermined amount by which the air/fuel ratio is enriched corresponds to about 3%. 10. The method of claim 7, further comprising the step of repeating the step of diluting the fuel after performing the step of enriching the fuel.