KR100351580B1 - Fuel quantity control method and control system of engine - Google Patents

Abstract

Determining the required rate of change of fuel per cycle over time in response to changes in engine load requirements, and applying a filter constant to the determined rate of change of fuel required per cycle over time to determine the rate of change of fuel required per cycle of the engine over time. A method of controlling the amount of fuel supplied to an engine that undergoes a change in engine load demand, comprising the step of maintaining the value not to be greater than a predetermined threshold.

Description

Fuel quantity control method and control system of engine

The present invention relates to a method and a control system for controlling the amount of fuel supplied to a fuel molecule internal combustion engine, in particular an internal combustion engine that undergoes a sudden change in torque that may occur in a driving condition of a motor vehicle.

While the vehicle is driving, a sudden increase or decrease in engine speed may occur. This can be effected by the engine's control system as it occurs at the driver's demand or as, for example, during the conversion of an automatic gear. Acceleration or deceleration has the effect of increasing or decreasing the fuel condition of the engine and may result in engine fuel shortages or fuel oversupply during multiple engine cycles. This lack of fuel supply or fuel oversupply can reduce the optimum engine performance.

In addition, the conventional practice of isolating the engine from the support of the vehicle by means of a relatively compliant isolation mount, commonly referred to as the engine mount, particularly if the engine mount is fully compliant to sudden acceleration or deceleration (i.e. acceleration of the vehicle). Or the engine mount does not absorb the shock transmitted at the time of deceleration and responds completely to the shock), and the torque response caused by the shock at the engine mount may result in large movement of the engine with respect to the vehicle chassis. Such large movements and shocks in the engine mount are undesirable in view of the comfort of the driver and passengers, and are stressed to the engine mount, and therefore should be avoided. This phenomenon is commonly referred to as tip-in or tip-out.

The effect of tip-in / tip-out can be more pronounced in automobiles that are supported in common mounts, as is usually the case in engines, gearboxes and final drives in conventional all-wheel drive applications. By mounting the engine / gearbox assembly to a common mount, the torque response the mount receives consists of the torque generated at the gearbox output shaft. When such an engine / gearbox assembly is mounted via a common mount, the torque generated at the gearbox output shaft is three to four times greater than the torque generated at the engine flywheel.

In addition, the effect of tip-in / tip-out can generally occur better in engines that can provide a quick response to changes in driver demand. For example, Applicant's stratified-charge direct-injection two-stroke engines can respond to rapid changes in load demands that may be particularly demanding by the driver. These engines differ from conventional charge engines in that the driver demands control the amount of fuel in the engine rather than the airflow directed to the engine as in the general case. Thus the inertia and other lags associated with the airflow control engine do not necessarily have the same effect on Applicant's engine. Thus, in some cases it is desirable to adapt the damping function to this response, while in other situations the rapid response of the engine provides the driver with sufficient benefit.

Whatever the mode of operation of the engine, the above-mentioned problems are particularly frequent in the low speed range of the engine and, for example, in the operation of a car which suddenly causes a change in engine load demands while driving in the city and in a short time causes a return to low speed operation. Occurs frequently. In particular, in this environment, a failure of the engine's fuel supply can have poor results. In contrast, if a sudden change occurs during high speed operation, the effect seems less harmful as any fuel supply failure is compensated over many cycle periods of engine operation if the high speed operation condition is maintained for a long time.

It is an object of the present invention to provide a method of controlling the fuel supply to an engine in the above-described state in order to solve or substantially reduce the above problem.

In accordance with the above object, the present invention provides a method for determining a required fuel change rate per cycle based on a determined value of fuel required per cycle according to a change in load demand, and The rate of change of fuel per cycle supplied to the engine over time is determined by applying a filter constant to the determined value of fuel required per cycle, depending on the determined rate of change of fuel required per cycle over time. A method of controlling the amount of fuel supplied to an engine that undergoes a change in engine load demands, the method comprising maintaining.

Conveniently, the method can be carried out in a fuel based control system, in which the operator does not directly control the fuel supply to the engine, but merely the operator's request (i.e. the power output from the engine). A request signal is generated, which is then processed by an electronic control unit (ECU) which determines fuel and air flow conditions of the engine. Thus, the operator request signal, which is conveniently determined as a function of the accelerator pedal position, is input to the ECU, which outputs the required fuel (FPC) demand per cycle of the engine and thus controls the fuel supply. The rate of fuel change per cycle over time is measured according to the present invention and then filtered, i.e. multiplied by a filter constant to reduce the rate of fuel change per cycle over time not greater than a predetermined threshold, if greater than the predetermined threshold. It causes engine movements that cause anxiety for the engine operator and adversely affect the engine mounts. The threshold is a time variant and can be determined statistically or take into account mechanical properties such as the life or durability of the engine mount.

Conveniently, the ECU may be configured to change the engine load demand regardless of the driver's action, which may be required during gear ratio changes in the automatic transmission gearbox. In this way, the present invention can also be applied to changes in load demand that occur regardless of the driver.

Conveniently, the necessary filter or damping constants will be stored in a look-up table with preset values for a particular rate of change of fuel per cycle over time under particular engine speeds and load conditions. In this way, the ECU provides the appropriate filter constant depending on the engine operating condition. In addition, a lookup table storing a filter or damping constant or intermediate lookup tables required to generate an input for such a filter constant lookup table is advantageously made depending on the road surface speed of the detected vehicle. The detected road speed of the vehicle itself depends on the engine speed and load, and can be calculated from this engine speed and load with other engine operating parameters if necessary. In addition, it is known to calculate a special transmission gear in which a vehicle is built via the engine speed and the road surface speed of the vehicle. Therefore, in the case of the road speed of the vehicle, the lookup table may be made depending on the transmission gear in which the vehicle is built.

Conveniently, a lookup table that stores the necessary filters or damping constants can be arranged to adapt with respect to time. Thus, if a specially selected filter constant results in an unsatisfactory engine operating state, for example, each time the filter constant is applied to the required fuel demand per engine cycle, the filter constant is appropriately incremented up or down, in advance in the lookup table. Replaced with the stored filter constant value.

Similarly, the determined rate of change of fuel required per cycle over time may be constant (linear time function of fuel supply) or time variance. In the case of time variables, the ECU will calculate a function representing the variation in fuel rate per cycle over time for the engine.

Conveniently, filtering or damping of the rate of change of the fuel supply rate of the engine takes place immediately as required by the operator or ECU. This is particularly advantageous in fuel inertial control systems with less inertia and delay than in conventional charge control systems based on air, as already mentioned. In other words, rapid filtering or damping reactions are necessary in the fuel based control system to facilitate the change in fuel feed rate and / or to achieve the desired effect of changing the value of the fuel change rate supplied per engine cycle not to be greater than a predetermined threshold. Do.

However, with the determined rate of change of fuel required per cycle over time, the degree of fill ring will vary over time taking into account such characteristics as the operation of the engine mount. The movement of the engine will be most severe at the start of the tip-in / tip-out that the engine mount best follows. As the engine progresses further, the tracking of the mount is generally reduced. The degree of filtering will therefore vary with consideration of the following of the mount, and the filter constant can be initially calculated to make the rate of change of fuel supply for the engine smaller when the mount is best following. The recalculation of the filter constant is then generated to increase the rate of change of the fuel supply, and over time as the engine strength increases or decreases, it tends to offset the possibility of unnecessary levels of tip-in / tip-out operation. Faster access to fuel demand per cycle. This recalculation of the filter constant can occur step by step or more gradually.

The method of the present invention may conveniently be carried out in cooperation with the applicant's pending patent applications AU 34862/93 and PCT / AU 94/00360.

In another aspect, the present invention provides a system for implementing the method described above, in particular a control unit with means for determining a change in engine load demand, and a system for changing the engine load demand over time in response to the determined change in engine load demand. Means for determining the required rate of change of fuel per cycle, and a predetermined threshold as well as the value of the filter constant, multiplied by the determined rate of change of fuel required per cycle over time, for the engine over time; It provides a fuel control system for an engine that is subject to a change in engine load requirements, comprising means for determining a filter constant applicable to the determined rate of change of fuel required per cycle of the engine over time to adjust to a filtered value no greater. .

The filter constant determining means may provide an appropriate filter constant according to the sensed engine operating state. For example, the filter constant may be determined in response to the detected engine speed, the detected engine load, the detected road speed of the vehicle, and / or the sensing change of the transmission gear of the vehicle. In this way, the filter constant is a function of the parameters that can affect the operation of the engine and the driveability of the vehicle in which it is mounted, thus providing better compensation for tip-in / tip-out operation of the engine.

Nevertheless, filter constants can be made depending on other sensed engine operating parameters. For example, if the filter constant needs to correct the special air / fuel ratio condition of the engine, an air intake flow and fuel flow sensor may be incorporated into the system as part of the filter constant determination means. It forms part of the electronic control unit that constitutes an important component of the. Appropriately programmed control units and required sensors can be supplied and installed in the vehicle or engine.

The invention will be clearly understood in the following description with reference to the drawings.

1 is a schematic diagram of an engine management system according to a first embodiment of the present invention.

2 is a schematic diagram of an engine management system according to a second embodiment of the present invention.

3 is a schematic diagram of an engine management system according to the prior art.

4 is a schematic diagram of an engine management system incorporated in a fuel based control system according to a third embodiment of the present invention.

In FIG. 1, there is shown schematically a method of operating an engine management system for controlling the fuel supply to an automobile engine according to the method described above. The schematic part in the dashed line constitutes the part of the electronic control unit (ECU) 9 which forms an important component of the engine management system, and ECU-controlled engine management systems are known in the art. The ECU 9 receives a signal indicating the engine speed from the engine speed sensor 10 and a signal indicating the engine load demand from the load demand sensor 11, and the latter signal is usually a potentiometer attached to a driver-operated throttle pedal. Point to the location of. Both input signals are advantageously filtered to remove noise and avoid hunting. In addition, the ECU 9 is arranged to change the engine load demand irrespective of the driver operated throttle pedal, and the load demand sensor 11 may be configured to equally sense a signal not generated by the driver.

The ECU 9 can determine the rate of change of engine speed with respect to time and the rate of change of engine load demand with respect to time from the above-described signals. Also as already mentioned, the ECU 9 can be adapted to receive a signal indicating the vehicle road speed from an appropriate road speed sensor, or if necessary, actually generate such a signal from other sensed or input engine operating parameters. You can. The "gear gear signal" indicates whether the execution of the filtering routine is actually necessary. Along with vehicle road speed, the transmission gear signal can be calculated as a function of engine operating parameters, for example road speed and engine speed. Next, filtering of the rate of change of fuel supply (i.e., dFPC / dt) at low gear and low speed engine conditions, for example, by analytic seems to be even more necessary.

It should be noted that it is desirable to use the road speed as an input variable of the ECU 9 or a variable generated by the ECU 9 so that the operation of the engine management system is less impaired. In other words, is the filtering of the rate of change of the engine's fuel supply dependent on the vehicle's road speed too seriously active due to the fact that it may have the same fuel supply rate for different vehicle speeds depending on which transmission gear the car is equipped with? Or may be insufficient. For example, at low road speeds and engine slow speeds, a sudden increase in engine load demand, which occurs after a sudden decrease in engine load demand, typically results in poor tip-in / tip-out operation. Such situations usually correspond to short accelerations in low gears, such as may be the case when tuning in a parking area, for example. Therefore, it is highly desirable for this situation to sufficiently filter the rate of change of fuel supply to avoid tip-in / tip-out.

In contrast, at high vehicle road speeds and engine low speeds, as experienced when driving at relatively high speeds, a large amount of filtering may be necessary when the tip-in or tip-out motion of the engine is not actually visible to the driver due to other factors such as car inertia. Will not need. Other situations that may arise include situations in which the vehicle is driven and actively matches engine speed. In such a situation, it is desirable to filter the rate of change of the engine's fuel supply so that the engine performance can be compromised by the driver's dissatisfaction.

It is also important to note that a large amount of filtering is usually undesirable during gear shifting and in some situations no filtering is required during gear shifting. For example, during normal gear shift, the driver of the car presses the clutch and "backs off" the fuel supply, so that the engine speed drops until another gear ratio is selected and the clutch remains disconnected while the load demand is applied. do. If a filtering routine is available that changes the rate of change of fuel supply rate for the engine over time, the engine ECU detects this as a possible tip when the driver presses the clutch or stops the accelerator pedal during gear shifting and thus the rate of change of fuel supply. You can filter If this happens, the engine will "hang" speed rather than slow down. In fact, the engine speed increased because the load from the gearbox was removed. This is undesirable because the driver tries to correct such engine response by gear shift action. Any consumption of fuel resulting from such an unnecessary increase in fuel supply is undesirable.

Thus, the filtering routine is suitably made in accordance with the signal from the clutch switch so that the driver occurs with no or reduced filtering during gear shifts. Obviously, if no clutch signal is received, the ECU will handle any other reductions as possible tip-in or tip-out situations and apply filtering accordingly. It should be noted that similar corrections will apply equally even if no clutch signal is received during the start or end of the gear shift.

Referring again to FIG. 1, a fuel per cycle (FPC) request lookup table based on operator demand or engine load demand and engine speed 10 as indicated by pedal potentiometer position 11 or The map 12 generates a signal indicating the required fuel supply rate (FPC _demand ) per cycle of the engine 20. From this FPC request map 12 the ECU 9 can also calculate the rate of change (dFPC / dt) 14 in the fuel demand per cycle of the engine over time. Conveniently, this value is determined by reading two FPC requests over a predetermined period interval if the time interval is the time between recording of two FPC request values. Conveniently, the two FPC request values mentioned will be the request FPC determined as a function of the new pedal position and the previous request FPC.

The signal 13 indicating the required fuel supply rate (FPC _request ) of the engine 20 is input to the second lookup table or map 15 together with the road speed signal 16, from which the base filter constant B (17). ) Is calculated. The road speed signal 16 is calculated by the ECU 9 from the sensed or known engine operating parameters. The actual rate of change of the base filter constant 17 and fuel feed rate (dFPC / dt) 14 is then input into a third lookup table or map 18 which provides the true filter constant value 19 if necessary. The real filter constant value 19 is applied as the original required FPC value 13 to generate a filtered or damped FPC value 13, which can be entered as an operating control parameter for the engine 20. The " true " filter constant value 19 is appropriate for the special value of dFPC / dt, so that the rate of change of fuel supply is required for the new value for the required FPC (i.e., below the predetermined threshold of dFPC / dt To avoid unnecessary tip-in / tip-out motions.

The controlled rate of change of the required FPC will not cause a mistake in the fueling of the engine 20, but in some cases provides a satisfactory fueling for acceptable levels of acceleration or deceleration. To this end, the map 18 that calculates the true filter constant has a predetermined filter constant that has been found to be satisfactory for the particular dFPC / dt required by the operator or operator or ECU 9. This improves the driveability of the motor vehicle as the movement of the engine 20 and also controls any impact caused by the engine mount to an acceptable or more desirable level. Filtering of the request FPC signal 13 takes place immediately and continues until acceleration or deceleration is complete.

In other embodiments, a system may be provided that does not take road speed into consideration, and / or a system that starts only in response to any engine operating conditions established by or programmed by the ECU 9. Such a system is shown in FIG. The operation of this system is briefly described as described with reference to FIG. 1 without correcting the road speed. In such a device a second map 15 is not needed. In this case, the base filter constant 24 is made by the lookup table or map 23 as a function of the rate of change of fuel supply (dFPC / dt) 14 and the fuel demand 13. The base filter constant 24 is then applied to the original fuel demand or demand FPC 13 to generate a filtered or damped FPC value 13 and may be input as an operating control parameter for the engine 20.

Applicant's pending Australian patent application No. 34862/93 describes a method for controlling the amount of air and fuel per cycle supplied to each cylinder from an internal combustion engine. The control system disclosed in this patent application is shown in FIG. Referring to FIG. 3 of the present application similar to the third of the patent application, the FPC request map 12 generates a signal 13 indicating the fuel demand per cycle of the engine 20 during normal operation of the engine 20. do. Signal 13 indicating the fuel demand per cycle of engine 20 is input to an air demand map 23 that determines the air demand 27 per cycle for a particular fuel demand per cycle 13 (in terms of engine speed). do. The air mass sensor 22 then measures the actual air 21 per cycle supplied to the engine 20 at the current positions of the throttle valve 28 and the bypass valve 29. If the air demand 27 per cycle as indicated in the air demand map 23 does not match the actual air 21 per cycle supplied to the engine 20, the air bypass valve 29 makes the necessary corrections. Works to carry out. Normally this operation is achieved via the PID controller 31.

Fuel per cycle 13 and actual air per cycle 21 signals are provided as inputs to the air / fuel ratio comparator 25 where the actual air / fuel ratio based on these inputs is the engine load demand or pedal position and engine speed. It is compared with the inspected air / fuel ratio which is preset based on. The inspected air / fuel ratio is stored in a map and will normally be within a range between the maximum or minimum predetermined limit. The required air / fuel ratio does not exceed the inspected air / fuel ratio and therefore does not exceed, for example, the abundant noncombustion limit of the engine. If the air / fuel ratio is different from the inspected air / fuel ratio more than the allowable amount, as determined by the fuel demand per cycle 13 and the actual air per cycle, the correction module 26 is supplied to the engine 20 It may serve to correct the sugar fuel so that the air / fuel ratio will be within an acceptable deviation from the inspected air / fuel ratio.

Thus, in view of the present invention, if there is a sudden change in pedal position at low road speeds, for example, the rate of change of _inspected fuel per cycle demand (dFPC / dt _inspected ) can be input into the base filter constant map 15 and Since the map provides a bass filter constant 17 appropriate for the particular value of dFPC / dt _inspected, the rate of change of fuel supply (dFPC / dt) 14 is manageable as described above with reference to FIG. Level is reduced. This is shown in FIG. However, the system is preferably configured such that the filtering routine can still be executed, even if the rate of change of fuel per cycle (dFPC / dt) 14 exceeds any threshold even at high road speeds. In this respect, the purpose of the filtering routine is to improve operator comfort and the system is also configured to achieve that goal.

Since the values of the filter constants are adaptable over time, for example, if the selected filter constants 19 and 24 are detected by the combustion chamber pressure transducers, as the misfire of the engine 20 increases, the filter constants 19 Each time, 24 is applied to a particular FPC request value 13, the filter constants 19, 24 are incremented down as needed and replaced with the filter constant values already held in the filter constant maps 18, 23. In this way, the necessary filtering and fueling conditions in the engine 20 are maintained,

Alternatively, filter constants 19 and 24 or filter constant maps 18 and 23 can be adapted to accommodate changes or differences in engine mounts. Thus, for example, as the time progresses, the wear or secular variation of the engine mounts increases, and as a result the need to filter the rate of change of fuel per cycle (dFPC / dt) 14 results in a degradation of such engine mounts. Will change accordingly. The ECU 9 can be programmed with such factors in mind. In addition, the ECU 9 may be configured to be able to employ the filter constant maps 18 and 23 with respect to other engine mounts, such as when replacing an automobile engine mount. To this end, the ECU 9 will receive or generate signals from a properly positioned accelerometer or sensed crankshaft oscillation.

Note that the described method is a system that is applied to filter the change in fuel supply rate required by the ECU 9 regardless of the driver's action. In the field of automatic gearbox engines, the ECU 9 quickly reduces the load requirements and subsequently reapplies the load demands so that there is a smooth transition during the gear changeover, therefore, the method can be used to fuel the engine while returning to a higher load demand. While applied to control the feed rate, no filtering is required to reduce the fuel supply of the engine 20 during gear shift.

Reference is now made to another embodiment where the filter constant is made as a function of time and the degree of filtering is changed in consideration of the variable motion of the engine mount in response to engine motion caused by changes in engine load requirements.

The engine mount typically initially follows the shock or shock applied to the engine mount and then poorly follows as the mount absorbs the force applied by the engine. Thus, the degree of filtering of the rate of change of fuel per cycle over time can be varied to account for this phenomenon. This is accomplished in the following way.

Initially, if a tip-in or tip-out occurs in response to a change in engine load requirements, a first high level of filtering or a decrease in the rate of change of fuel supply is needed to control or limit the initial reaction movement of the engine at the engine mount, The mount in question is a mount that receives the force caused by the engine's motion, whether it responds to tip-in or tip-out.

In this way, the engine does not receive enough moment to cause a force shock that is transmitted to the vehicle via the engine mount. In other words, the next time the mount begins to absorb the forces generated by the movement of the engine, if the mount does not follow well, a greater rate of change in fuel supply to the engine would initially be controlled by the more realistic rhythm of the engine. When allowed. After the initial "compliant" phase was completed, the engine mount absorbed the actual portion of the force generated by the engine motion. Thus, the Filti constant can be recalculated, and the degree of filtering is increased without increasing the rate of change of fuel supply, which causes severe shock or shock to the engine mount, since the mount strength has been increased to a level that does not harm the driver's comfort. Can be reduced.

The change in filtering achieved by the recalculation of the filter constant may be stepwise or gradual and possibly a function of the degree of engine motion generated as determined by reference to time or monitored engine mount strength. Such a change in filtering can be induced to respond better when the filtered rate of change of fuel supply can be better matched to the driver's required rate of change or can actually achieve the final required FPC at the same rate or time. If the required rate of change of fuel supply was supplied without filtering, then the final required FPC would have been achieved.

In one embodiment, an injection timing or possibly a time counter may be used, for example, which may be executed when the operator demand increases suddenly, i.e. from idle to wide throttle at low speeds, which typically results in an unacceptable tip. . The ECU 9 may then provide a filter constant that makes the rate of change of fuel supply lower during the initial injection timing with counter execution. The filter constant can be calculated in response to engine speed, gear and road speed or other parameters as described above so that the initial rate of change in the fuel supply of the engine is kept below the threshold causing excessive engine motion.

Next, if the engine mount is not well tracked, the fuel supply rate can be increased as the likelihood of excessive engine motion is reduced, so that the rate of change of fuel supply will approach the final demand more quickly when the counter increments steadily rise. The filter constant value can be changed to make this possible.

Once the final fuel demand per cycle over time is reached, the counter is set to zero and cannot be used until the next tip in / tip out timing is reached.

The above description of the present invention is not intended to limit the present invention, and those skilled in the art can make other changes within the scope of the present invention.

Claims (35)

In the method of controlling the amount of fuel supplied to an engine that undergoes a change in engine load demand, Determining the value of the required fuel per cycle (FPC _demand ) according to the change in load demand, and the required rate of fuel change per cycle according to the time (dFPC / dt) based on the determined value of the required fuel per cycle (FPC _demand ) And the filter constant applied to the determined value of the required fuel per cycle (FPC _requirement ) per cycle depending on the determined rate of change of fuel required per cycle according to time (dFPC / dt) per cycle supplied to the engine over time. And maintaining a rate of change of fuel not to be greater than a predetermined threshold. The method of claim 1, The filter constant is provided by a look-up table in the control unit, the look-up table having a predetermined value of the filter constant corresponding to a particular rate of change of fuel required per cycle over time under a particular engine operating condition. How to control the amount of fuel you are doing. The method according to claim 1 or 2, The application of the filter constant is a method of controlling the amount of fuel depending on the engine operating state. The method of claim 1, The application of the filter constant depends on at least one parameter selected from the group consisting of engine gear, clutch position, vehicle road speed, engine load and engine speed. The method of claim 1, And the value of the filter constant depends on the engine load or the engine speed or both. The method of claim 1, A method of controlling the amount of fuel carried out in an automobile in which the value of the filter constant depends on the sensed road speed of the automobile. The method of claim 1, And the value of said filter constant depends on the signal generated by the change of engine gear. The method of claim 1, And the filter constant is incremented up or down to generate the necessary filter constant for a given engine operating condition and can be applied over time. The method of claim 1, And the filter constant is corrected for a change in wear of the engine mount. The method of claim 2, The control unit determines the required air / fuel ratio according to the engine operating condition, and according to this determination, the control unit maintains the required air / fuel ratio and simultaneously changes the filter constant to change the filter constant to maintain the rate of change of fuel per cycle below a predetermined threshold. Control method. The method of claim 1, And the change of engine load demand is initiated by an operator of an engine. The method of claim 1, The change in engine load demand is independent of the amount of fuel operated by the operator. The method of claim 11, And wherein the change in engine load demand is determined as a function of the position of the accelerator pedal. The method of claim 1, Wherein the change in engine load demand is determined as a function of engine operating state. The method of claim 1, And the filter constant is applied instantaneously to the determined rate of change of fuel required per cycle over time. The method of claim 1, And the value of the filter constant is changed in accordance with a change in tracking of the mount relative to the engine. The method of claim 16, With the filter constant applied and the engine motion starting at the engine mount, the filter constant is calculated to produce an initial threshold of fuel change rate per cycle of the engine over time, with the engine speed decreasing at the engine mount. As the filter constant is recalculated as it becomes smaller in response to tracking, the next value of the engine's fuel change rate per cycle over time is greater than the initial value, allowing quicker access to the engine's fuel per cycle required by the engine operator. To control the amount of fuel present. The method of claim 1, The fuel change rate required per cycle with time is determined directly from the engine load demand. The method of claim 1, The control method is a method of controlling the amount of fuel carried out in a fuel based control system. The method of claim 1, And the filter constant is diverted over time when the determined rate of change of fuel required per cycle of the engine exceeds a predetermined threshold. The method of claim 1, A method of controlling the amount of fuel in which the determined rate of change of fuel required per cycle with time varies over time. The method of claim 1, The determined rate of change of fuel required per cycle over time is a constant fuel control method. The method of claim 1, The predetermined threshold value is a control method of the amount of fuel varies over time. The method of claim 1, And the engine is a direct injection engine. The method of claim 1, The engine is a control method of the fuel amount of the air-using engine. In a fuel control system for an engine subject to a change in engine load requirements, A control unit having means for determining a change in engine load demand; Means for determining a value of fuel required per cycle (FPC _demand ) in accordance with a change in load demand; Means for determining a rate of change (dPFC / dt) of fuel required per cycle over time based on the determined value of fuel required per cycle (FPC _requirement ); Means for determining a filter constant based on the determined changes in fuel required per cycle over time; Means for adapting the filter constant to the fuel required per cycle (FPC _requirement ) to maintain a rate of change of fuel per cycle supplied to the engine over time not greater than a predetermined threshold. The method of claim 26, And a sensor for determining a value of an engine operating state upon which the filter constant depends such that the filter constant is determined according to the sensed value. The method of claim 26 or 27, The sensor comprises an engine load sensor or an engine speed sensor or both sensors. The method of claim 26, The sensor comprises a road speed sensor. The method of claim 26, The aircraft sensor includes a fuel conversion sensor. The method of claim 26, The sensor includes a means for determining wear of the engine mount. The method of claim 26, A fuel control system comprising an air intake flow sensor and a fuel flow sensor. The method of claim 26, A fuel control system comprising a sensor for sensing the clutch position. The method of claim 26, The engine is a direct injection engine. The method of claim 28, The engine is a fuel control system.