JPS6248053B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel conditioning system with an improved ability to handle transient fuel conditioning regimes. More specifically, an engine's fuel control system is capable of controlling engine acceleration, deceleration (negative acceleration), and other temporary fluctuations in the flow of fuel from an engine's main fuel regulator to its combustion chamber, compared to conventional techniques. The present invention relates to a fuel conditioning system for an internal combustion engine that is better able to handle transient conditions that occur during conditions that cause ignition.

In internal combustion engines, the rate at which fuel is supplied to the engine varies during engine operation. Changes in engine load cause the engine's fuel regulator to increase or decrease the percentage of fuel delivered to the engine.
As a result, the engine must change from a first state where engine operation and fuel flow are quite stable to a second state where these conditions are stable again.
Conditions between these safe conditions have a transient nature in which the fuel flow rate changes continuously and creates an undesirable air/fuel ratio. For example, in vaporizer or other centrally located fuel regulators, there is an intake manifold flow path through which the vaporized or atomized fuel must reach the combustion chamber of the engine. At a given engine load, prior art fuel control systems provide accurate air/fuel control during transient engine operating conditions until conditions in the engine intake flow path stabilize.
It was not possible to maintain the fuel ratio. Sudden acceleration increases the rate at which liquid fuel is deposited on the walls of the intake passage (wall wetting), and sudden deceleration decreases the rate of deposition. The reason for this is related to changing vapor pressure. The higher the vapor pressure, the more fuel tends to accumulate on the walls of the intake passage. Vapor pressure is a partial pressure, so it is the air that primarily influences the pressure in the intake flow path. Air pressure in the intake flow path is generally below atmospheric pressure during engine operation unless the normal throttle valve is fully open.

As long as the wall wetting varies, the amount of fuel delivered by the engine's fuel regulator will actually vary during the charge air transport time (air/fuel charge time) applicable to the particular engine speed and load condition at that time. It is not the amount of fuel that reaches the engine's combustion chamber. Under stable engine operating conditions, engine speed and load are the primary factors that determine the transit time of the air/fuel mixture from the fuel conditioner to each combustion chamber of the engine. This is applicable to both central point and multipoint fuel regulators. Center point fuel regulators are a conventional carburetor and a recently developed center point fuel regulator that has two electromagnetic fuel injectors located within the throttle body (air valves) to inject fuel into the incoming air stream. Including both point fuel injectors. A multipoint fuel regulator includes an electromagnetic fuel injector for each engine combustion chamber, with each injector injecting fuel into an associated combustion chamber in the intake flow path immediately upstream of the intake valve. An example is given below.

A search of the prior art did not turn up any patents specifically related to this subject matter. However, the following patents are of interest for general background.

US Pat. No. 3,794,003 to Reddy shows an electronic deceleration control system responsive to engine RPM (revolutions per minute) and intake manifold absolute pressure. This device calculates the first derivative of manifold pressure to immediately indicate a deceleration request regardless of throttle position or minimum manifold pressure. This device reduces or stops the supply of fuel to the engine when the manifold pressure exceeds a predetermined value. Fuel supply is resumed after the manifold pressure returns to or above the second predetermined value. Engine RPM
is also a factor used in this fuel control system.

U.S. Patent No. 3969614 to Moyer et al.
This issue discloses an engine control device using a digital computer that calculates the appropriate setting for one control variable in real time while taking into account the influence of the settings of other control variables in order to always provide stable engine operation. The computer is programmed to iteratively calculate values for the controlled variables from algebraic functions that define a predetermined desired relationship between the first control output variable and the second control output variable.

US Patent No. to Hartford
No. 3,964,443 discloses a digital engine controller that can be used to control a fuel injector in which engine intake manifold pressure, engine RPM, and engine temperature are used as inputs to a computer.

U.S. Pat. No. 4,086,884 to Moon et al. shows a fuel control system for a spark-ignited internal combustion engine in which fuel is supplied by center point fuel injection. This fuel injection pulse width determines the amount of fuel delivered to the engine, and this is calculated by the velocity-density method to determine the mass air flow rate.

The present invention provides an improved fuel conditioning system particularly suitable for use in spark ignition internal combustion engines. However, the principle of improvement is that diesel,
It can also be extended to other engine types such as external combustion and turbines. Each of these other engine types
may require a fuel mixture and the transient control provided by the present invention. Diesel engines involve direct injection of fuel into the combustion chamber or prechamber of the engine (indirect injection diesel), but the amount of fuel remaining on the walls of the combustion chamber or prechamber and changes in such amounts are the result of diesel engine exhaust emissions. and may be of considerable importance in proper control of fuel economy. Continuous combustion engines, on the other hand, do not require as much fuel control as internal combustion engines because combustion is continuous and excess air is always available. However, it is not inconceivable that such an engine might one day require compensation for transient deposits of fuel in the intake flow path to the "external" combustion chamber of such an engine. . Such compensation may be particularly important where the engine's response to changes in fuel flow is significant.

The improved fuel conditioning system of the present invention is designed to take into account changes that occur in the amount of fuel deposited in liquid form in the intake passage of an engine. The air/fuel ratio of the mixture in the intake passage is determined by the initial fuel conditioning proportional to the incoming air and also due to the transfer of fuel into or into the air/fuel mixture introduced from the plane of the intake passage. Varies as a function of net migration. The incoming air is mixed with fuel at some point in the intake flow path before flowing into the engine's combustion chamber. Liquid fuel on the walls of the combustion chamber may be included in the net transfer.

According to the present invention, an improved fuel conditioning system for an engine with an intake flow path takes into account the fuel regulator and the rate of deposition and removal of liquid fuel on or from the surface of the intake flow path of the engine. including its fuel regulator and associated equipment. Liquid fuel on the walls of the intake channel is moved into and removed from the air/fuel mixture flowing through the intake channel into the combustion chamber. This movement and removal occurs at varying rates both locally and also globally within the flow path. This rate variation is a function of engine speed, engine load, engine and intake air and fuel temperatures, and several other less important parameters.

Referring now to the drawings, FIG. 1 shows a basic fuel conditioning system 10 and a transient compensation fuel conditioning system 12. As shown in FIG. The basic fuel conditioning system has an engine 16 that produces certain operating conditions that are sensed via an engine sensing device 14, as indicated by arrow 15.
A sensing device coupled by electrical leads 32, which may take the form of a data bus for transmitting digital information, determines the operating status of the engine by determining the desired regulated ratio of fuel to be delivered to the engine 16 at a particular moment. You can calculate it and use it. This ratio is calculated in the basic fuel regulator 10. The fuel is moved in the direction indicated by arrow 17 in response to an appropriate signal appearing on the electrical or mechanical path represented by arrow 19.
The fuel is supplied to the engine using a fuel regulator 18, as shown in FIG.

The basic fuel conditioning system 10 preferably includes a digital computer of the type used in the fuel conditioning system described in U.S. Pat. No. 3,969,614 commonly issued to Moyer et al. Preferably, the fuel injection pulse width can be calculated to give the ratio. The pulse width may be determined using a computer calculation that determines the amount of fuel to be delivered to the engine for each injection as a function of the mass air flow into the engine's intake flow path at the time of injection. A mass air flow meter or other device may be used to directly determine mass air flow. Instead, the velocity-density type of mass airflow into the engine is done, as is done in the improved fuel conditioning system described in U.S. Pat. No. 4,086,884 commonly issued to Moon et al. An indirect determination may also be made. The device of Moon et al.'s patent is now published in the United States under the names of J. W. Hoard and R. R. Tuttle and entitled "Method for Improved Fuel Control of Internal Combustion Engines" dated November 2, 1979. A further improvement has been made to the method described in patent application no. 317671.

The transient fuel adjustment compensator 12 is intended to correct the basic fuel adjustment ratio calculated by the digital computer. This compensation takes into account the proportion of fuel that is removed from or added to the liquid present at the plane of the engine's intake flow path. This transfer rate may, if desired, include a change in the amount of liquid fuel remaining in the combustion chamber of the engine as a deposit on its walls. When the fuel adjustment ratio (fuel injection pulse width multiplied by the number of injections per unit time and the fuel supply ratio during injection) is calculated by the basic fuel adjustment device 10, the engine The mass air flow rate to must first be determined.
At 33, the desired air/fuel ratio is determined based on the engine operating conditions prevailing at the time the mass air flow rate is determined. Via electrical or computer paths 34 and 35, a digital computer determines the desired mass fuel flow rate to the engine by dividing the mass air flow rate by the desired air/fuel ratio. The results on the electrical or computer path 37 are then used to calculate the fuel flow requirements, i.e., the fuel flow that takes into account the transfer of fuel to and from the amount of liquid fuel remaining on the surface of the engine's intake flow path. be exposed. This fuel flow request appears on electrical or mechanical path 19 and controls the regulation of fuel by fuel regulator 18.

Fuel regulator 18 may be a conventional carburetor or a set of electromagnetic fuel injectors. In the preferred form of the invention, the fuel regulator is a throttle body mounted to the engine's intake manifold. The throttle body has two electromagnetic fuel injectors positioned to inject liquid fuel through the throttle body and into the airflow entering the intake manifold. The injector may be oriented directly above a throttle plate or plate mounted within the throttle body to control mass air flow into the engine.

The fuel flow requirement is determined at point 20 of the system depicted in Figure 1.
It can be determined by This signal is a combination of the desired fuel mass flow rate and a second term represented by (TRISFn) (a constant). This second term compensates for changes in the amount of liquid fuel present in the plane of the engine's intake flow path. The constant in this term is the scale factor. The factor TRISFn is the transfer rate of fuel on the plane of the engine's intake flow path. This factor, along with other quantities used in the discussion below, is defined as follows. That is, TRISF=d(AISF)/dt=transfer rate of intake surface fuel AISF=actual intake surface fuel EISF=equilibrium intake surface fuel ISTC=intake surface time constant The transfer rate is expressed in units of mass per unit time. Actual and equilibrium intake surface fuel are expressed in units of mass and intake surface time constants are expressed in units of time. The intake surface time constant is the measure of the actual time it takes for fuel to leave liquid form and vice versa to become gas or vapor in the intake air mixture moving onto the intake surface toward the combustion chamber of the engine. .

The product of the transfer rate of intake surface fuel and the time constant is the difference between the equilibrium intake surface fuel and the actual intake surface fuel, and can be expressed mathematically as follows: (TRISF) (ISTC) = ISTCd (AISF)/dt = EISF - AISF This is a differential equation. In the constant rate state, d
(AISF)/dt is equal to zero and the actual intake surface fuel
AISF is a balanced inlet surface fuel. however,
Under transient conditions of engine operation, where the equilibrium intake surface fuel EISF varies between two different values corresponding to two different states of approximately stable engine operation, the above differential equation gives the engine's fuel regulator the EISF It may be solved to allow for the amount of fuel entering and exiting the suction flow due to changes in conditions. The fuel flow demand is a fuel flow rate equal to the desired fuel flow rate that is less than the net amount transferred from the intake surface to the intake mixture.

Although the desired fuel flow rate is calculated as described above, the TRISF compensation of the base fuel regulator calculation is preferably done separately by a digital computer that is used to handle both the base fuel regulator and the TRISF calculation. In the transient compensator, EISFn is available as a value that is calculated or found from the computer's tabular storage and is applicable to the particular engine operating condition at the time the fuel adjustment calculation is being made.
The subscript n represents the current EISF, AISF and TRISF values, and the subscript (n-1) represents their value at a previous time, such as the immediately previous computer calculation cycle.

Various types of computer or electronic techniques can be used in solving the differential equations that define TRISF. There are several mathematical methods that approximate solutions using trial and error techniques. This solution can also be obtained by using a table containing TRISF values for various engine operating conditions. A preferred form of the invention uses a combination of these techniques and approximates solutions to equations based on results obtained from previous solutions.
The previous solution, as well as the ongoing solution at a given time, is calculated from the values obtained in the previous solution of the differential equation, as well as by use of a table of values for equilibrium intake surface fuel (EISF).

EISF may be expressed as a function of one or more engine operating parameters, such as engine speed and engine load. In Figure 2, EISF is related to intake manifold absolute pressure, a quantity closely related to engine load.
Other parameters representing intake air or mixture flow rate or representing engine torque may also be used. A group of curves is EISF and RPM is also on the right hand side of each curve.
It is illustrated to show that it is a function of engine speed in numbers. Variables can be swapped if different families of curves are to be used.
Points 93 and 97 on the 1000 RPM curve represent two different engine power output requirements at the same engine speed. In a vehicle application of the engine, this would correspond to changing from driving the vehicle on level ground to driving uphill with the throttle open to maintain engine speed. In such cases, if a throttle valve (commonly used in engines to control airflow and power output) is opened to increase the engine's power output, the engine speed will remain approximately constant. Will. When opening the throttle, intake manifold absolute pressure (MAP)
increases, thereby moving engine operation from point 97 to point 93. The pressures corresponding to these points are shown by lines 99 and 95, respectively. The EISF values at these points are shown by lines 96 and 94, respectively.

Line 98 in FIG. 2 shows the actual intake surface fuel (AISF) that necessarily occurs sometime during equilibrium engine operation at points 97 and 93. The AISF value occurring between the equilibrium points is used to determine the rate of inlet fuel transfer and then, as shown in block 20, to determine the fuel flow requirement. In this way, transient compensation of the fuel adjustment ratio calculated by the basic fuel adjustment system 10 is achieved to take into account liquid fuel moving from the engine intake flow path to its intake mixture and vice versa. .

At balanced engine operation, the intake surface fuel remains unchanged and can therefore be ignored. However, during changes or transient conditions that occur in engine operation, accurate fuel regulation is dependent on the contribution of the inlet air/fuel mixture to the amount of liquid fuel present at the intake flowpath surface or from the intake surface deposits of fuel to the air/fuel mixture. Requires that a deduction be made for the contribution to the mixture. Fuel leaving the intake surface becomes atomized or vapor or gas and mixes with the air and fuel moving along the intake flow path. This intake surface fuel is added to the adjusted amount of fuel determined by the current fuel settings. On the other hand, the gaseous fuel deposited on the intake flow path faces undergoes a change in conditions and is subtracted from the amount of fuel that actually reaches the combustion chamber of the engine.

When fuel is added to the air/fuel mixture, it must be subtracted from the desired amount obtained from the step shown in block 36 of FIG. Therefore, the fuel taken from the walls of the intake channel and added to the incoming mixture is given the opposite mathematical sign compared to the desired fuel flow, so when combined in the summing process, the result is A value representing the fuel flow requirement, i.e., must be adjusted to provide the desired air/fuel ratio taking into account the transient fuel addition provided by the fuel taken from the intake flow path plane and drawn into the combustion chamber of the engine. It is the amount of fuel. Of course, the fuel removed from the air/fuel mixture moving toward the combustion chamber is given the same mathematical sign as the desired fuel flow, so when combined to add to it, the fuel flow demand is reduced to the inlet mixture. This will include special consideration for fuel that is removed from the air and deposited on the intake flow path surfaces.

When the fuel flow demand is the same as the desired fuel flow determined as indicated by block 36,
The fuel supply system does not provide any transient compensation. The air/fuel ratio of the air/fuel mixture drawn into the engine during transient conditions is a combination of the adjusted fuel and the amount of fuel obtained from or added to the fuel previously deposited on the intake flow path surface. This latter amount results from pressure changes within the intake manifold under various conditions of engine operation. If the pressure increases as a result of opening the throttle or reducing engine load, the partial pressure of oxygen and non-flammable gases in the intake mixture increases correspondingly and the partial pressure of fuel vapor decreases. The fuel separated from the air-fuel mixture is deposited as a liquid on the surface of the intake flow path. Conversely, if the fuel partial pressure increases as a result of other partial pressures decreasing, the amount of liquid fuel deposited on the intake flow path surface will decrease, and the fuel removed from that surface will enter the combustion chamber of the engine. guided by. In addition to pressure, there are other factors that affect the amount of liquid fuel on the surface of an engine's intake flow path.

When the air supplied to the engine is cold, the amount of liquid fuel deposited on the intake flow path surface is greater than when the engine is warm. This is because the partial pressure of the engine intake air is greater at lower temperatures than at higher temperatures, and also because fuel condenses more easily at lower temperatures. Also, if the intake air or fuel is cold, the fuel conditioner 18 used may not be effective in thoroughly mixing the air and fuel being drawn into the engine. For these reasons, it has become common to use fuel concentrators and techniques (the common equivalent of chiokes commonly used in spark ignition engines) to compensate for low temperature operation. Unfortunately, the resulting fuel enrichment results in increased engine exhaust hydrocarbon emissions, which necessitates the use of sophisticated choke control systems to reduce hydrocarbons as much and as quickly as possible. Such reduction in hydrocarbon emissions hinders or reduces the performance of the associated engine during the warm-up period.

The temperature of the intake system or its components is significant with respect to the amount of liquid fuel that can be deposited on the intake surface of the engine. The intake flow path of an engine may contain air, a mixture of air and fuel, or a mixture of air, fuel, and exhaust gases. Either of these or the temperature of the engine and its intake conduit may be used to determine the rate at which fuel moves from the intake flow path surface to the intake air mixture or vice versa. The physical nature of the fuel itself is also important and varies both geographically and seasonally.

When it is desired to correct the rate at which fuel is delivered to the engine's combustion chamber for changes in the amount or transfer rate of liquid fuel present in the engine's intake flow path, this is accomplished using the transient fuel regulator 12 of FIG. This can be achieved by the method shown below.

In the transient fuel adjustment compensation device 12 of FIG.
The current transfer rate value TRISFn of the intake surface fuel is determined by the passage 46 leading to the block 20 of the basic fuel conditioning system 10.
appears in This TRISFn value is a number that is repeatedly calculated and updated based on changes in various operating parameters. As shown in block 44, the current transfer rate of engine intake fuel is a function of variables f ₄ that may be interrelated as follows:

TRISFn=EISFn-AISFn/ISTCn(1
) This TRISFn value is used until the EISFn, AISFn and ISTCn values are known in real time, i.e. when the engine is running and the basic and transient compensation fuel regulator 10
and 12 can only be calculated in the computer steps of block 44. EISFn can be determined from the engine motion parameters shown in Figure 2, but in reality,
As _shown in _block 40 _of FIG. temperature T _o ), time (Time _o ) and air/fuel ratio (A/
F _o ) is a function f ₁ of F o ). The physical properties of the fuel may also be considered. A/Fn is, of course, the ratio of air to fuel in the gaseous mixture near the intake flow path surface and varies depending on the position in the intake flow path. EISFn may also be obtained from a computer storage device having stored therein constants defining the slope and EISF axis intercept of a family of curves that may be representative of one or more of the curves shown in FIG. In this case, engine speed RPMn may be used to select an appropriate set of constants, and one value of intake manifold absolute pressure (MAP) may be used to obtain a value for the current equilibrium intake surface fuel EISFn. It's okay to be hurt. Of course, you can replace them with variables if you wish. In any case, the current EISFn is determined from the values of one or more engine operating parameters.

The TRISFn value in equation (1) cannot be determined until the AISFn and ISTCn values are obtained, i.e. the former is subtracted from the EISFn value obtained as mentioned in the previous section and this
The difference between the EISFn and AISFn values is divided by ISTCn, the current intake surface time constant.

AISFn is approximately equal to AISF _(o-1) modified to compensate for changes that may have occurred during the time elapsed since the previous actual intake surface fuel AISF _(o-1) was determined. If AISFn just mentioned the elapsed time △t,
If it is regarded as a function f ₃ of AISF _(o-1) and TRISF _(o-1) , the following formula is obtained.

AISFn=AISF _(o-1) + [TRISF _(o-1) ] [△t] (2) From the above equation (2), basic fuel adjustment is made for fluctuations in the amount of liquid fuel on the engine intake flow path surface. It can be determined, at least to a good approximation, from the previous values of TRISF and AISF used to compensate the device 10.

ISTCn is a time constant that represents the current or immediate rate at which fuel is being transferred from a liquid state on the intake surface to a vapor or gas state in the inhaled mixture, or vice versa. From this point of view, ISTCn can be said to be a function of one or more engine operating parameters that affect this rate of movement. Therefore, as shown in block 42 of FIG.
ISTCn is a function _f2 of intake manifold absolute pressure, engine speed, engine air or intake air mixture temperature, engine intake system temperature, time, A/Fn, and fuel physical properties. The intake surface time constant is not a constant in the sense that it does not change, but rather a variable under certain engine operating conditions.

ISTC is the equilibrium intake surface fuel EISFn and the actual intake surface fuel that exists and should be converted during engine transient operation.
The difference in AISFn is the amount of time required for the portion of fuel that will be moved.
The variations in ISTC are mainly due to variations in the engine intake system temperature and the intake air or gaseous mixture temperature TIn. That is, there may be other engine operating parameters that affect ISTC, such as intake manifold absolute pressure, engine speed, or engine cycle time. Variations in ISTC are analogous to variations in the RC time constant as a result of temperature and other variations that change resistance and capacitance values in an electrical circuit. At normal engine operating temperatures, this ISTC can be considered a constant, but to obtain more accurate fuel regulation ability, it is desirable to use multiple values for ISTC. These values may be chosen for the particular temperature range in which the engine operates, or other engine operating parameters may be selected.
May be chosen to determine the value used as ISTC.

If this ISTC value is selected from a table or calculated from a formula programmed into a digital computer, the ISTC is a variable that takes into account variations in the physical properties of the engine's intake manifold and its contents. Become. This is mathematically similar to the way in which the RC time constant of an electric circuit varies depending on changes in the resistance value R and capacitance value C that determine the time constant. Changes in ISTC that result from variations in the physical properties of an engine's intake system are primarily due to variations in engine operation and intake air temperature. These fluctuations are extremely small after the engine warms up.

After the ISTC is selected, the digital computer calculates the current intake surface fuel conversion rate TRISFn using the above equation (1).
and (2). That is,
EISF _o calculated in block 40, block 42
ISTC _o calculated in , calculated in block 62
AISF _o is input to block 44 via paths 41, 43, and 64, and TRISF _o is calculated. this
TRISFn is applied via paths 45 and 46 to determine fuel flow requirements in the basic fuel conditioning system 10, as shown in block 20.

After the TRISFn value is determined, the value is
7 to update the memory of the previous value. In other words, the latest or most current value TRISFn
is the previous value, as shown by block 50 in FIG.
TRISF _(o-1) and its updated value is applied across path 51 to storage 52. The storage device sends this updated value via path 53 to block 62, which in equation (2) above
It is used as the value of TRISF _(o-1) to calculate what should become the next TRISFn, and the next value is stored in the storage device 5 again.
2 will be updated.

Similarly, AISFn determined using equation (2) above
The value for is calculated iteratively. The clock 60 or pulse generator normally required by digital computer engine controllers to update fuel trim control settings is used to computer determine the time elapsed since the last update of the AISFn calculations. The signal from clock 60 is sent to block 62 via path 61. The current AISFn value is applied to the calculation of the TRISFn value via line 63, and the new AISFn value is also calculated from equation (2) as shown in block 65.
Storage device 6 containing the AISF _(o-1) values used in the calculation of
7 via path 66. Signals from storage device 67 are routed through path 68
The data is then sent to block 62. This process is
Preferably, the calculations of TRISFn are repeated at the same rate as they are made.

As is clear from the above description _and from _FIG . In order for the current TRISF _o value to be calculated in 44, the current actual intake surface fuel amount, i.e.
The AISF _o value must be calculated in block 62 and the calculated value must also be input into block 44. Then, in order to calculate the AISF _o value in block 62, storage devices 67, 52
The previous actual intake surface fuel, ie, AISF _(o-1) value, and the previous equilibrium intake surface fuel transfer rate, ie, TRISF _(o-1) value, must be stored respectively. That is, the TRISF values and
Once the AISF value is stored, the AISF value is repeatedly calculated in block 62, and therefore the TRISF value is repeatedly calculated in block 44. In order for the calculation in block 44 to begin, First, some data of AISF and TRISF values must be stored in storage devices 67 and 52. However, the data initially stored in the storage devices 67, 52 does not necessarily have to be accurate AISF values and TRISF values. That is, once the calculation of the TRISF value is started in block 44, the calculation is repeated every time ΔT elapses, and each time the calculation is repeated, the calculated TRISF value gradually changes from the actual intake air. (i.e. block 4)
This is because the calculation accuracy in 4 is improving). However, it is of course desirable that the data initially stored in the storage devices 52, 67 be accurate values. This is because if the data is accurate, an accurate calculated value can be obtained while the calculation in block 44 is repeated a small number of times.

From the above point of view, the data that is first stored in the storage devices 67 and 52 is actually detected data.
It can be said that AISF value and TRISF value are desirable. However, if that data is not available, the AISF value or TRISF value in an equilibrium state may be used. In other words, as is clear from the above explanation, in the equilibrium state, the AISF value is equal to the EISF value, and
This is because since the TRISF value is equal to zero, the AISF value and TRISF value in the equilibrium state can be easily obtained. However, storage devices 67, 52
The data initially stored in the
It does not matter if it is an AISF value or a TRISF value.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of the basic fuel control system and the transient compensation system used to modify, if necessary, the computer-calculated fuel quantity determined by the basic system. FIG. 2 is a graph of absolute intake manifold pressure of an internal combustion engine versus the amount of liquid fuel present on the intake manifold at equilibrium conditions of engine operation.

Claims (1)

[Claims] 1 A fuel conditioning system for an internal combustion engine that determines a desired fuel flow rate based on a mass air flow rate into the engine and a desired air/fuel ratio, the engine 16 introducing an air/fuel mixture into the combustion chamber of the engine. an intake passageway, the fuel conditioning system comprising an electrically configurable fuel system 18 for controlling the rate at which fuel is adjusted into the intake passageway when the engine is operated at selected conditions; The configuration determines the setting of the fuel system 18 and generates an electric signal 19 therefor without modifying the desired fuel flow rate, except for when the fuel is introduced from the surface of the intake passage. a device 12 for modifying the rate at which fuel is adjusted into the intake passage taking into account the rate at which it moves to the air/fuel mixture or from the introduced air/fuel mixture to the surface of the intake passage; consists of a digital calculator programmed to iteratively calculate a value representing the current transfer rate of fuel across the surface of the intake passage; a device used to modify the fuel adjustment rate by generating a control signal 46 that modifies the desired fuel flow rate to account for the proportion of fuel entering or leaving the mixture; 12 is the current equilibrium intake surface fuel quantity (EISF _o ) as a function of engine operating parameters.
a device 40 for calculating the current intake system time constant (ISTC o ) as a function of engine operating parameters; and a device 42 for calculating _{the current intake system time constant (ISTC o )} as a function of engine operating parameters; A device 62 for calculating the current actual intake surface fuel (AISF _o ) as a first-order differential function of the movement rate (TRISF _o-1 ) of the current equilibrium intake surface fuel quantity (EISF _o ) and the current intake system time constant ( ISTC _o ) and current actual intake surface fuel (AISF _o )
an electrical signal that iteratively calculates the intake surface fuel transfer rate and couples it to the desired fuel flow rate to determine the fuel flow request _; 19
A fuel adjustment device for an internal combustion engine, characterized in that it is configured to generate an electric signal and guide the electric signal to a fuel device 18 to adjust the flow rate of fuel introduced into the engine.