JPH11280530A - Method for uniforming rate of fuel injected to each cylinder in internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out initial injection and after injection to all cylinders with actually same fuel rate by finding out drift from an average value of an energy conversion value of each cylinder, and regulating a period of initial fuel injection in an injector of a cylinder in which the drift is detected, for returning the energy conversion value to an average value. SOLUTION: A distributor piping 7 is connected to a regulation driving part 8 per injector 6 (6 I to 6 IV) arranged on each cylinder of a multiple cylinder engine through a branch pipe. The regulation driving part 8 is provided with a magnetic or piezoelectric actuator, and is driven and controlled by a control device 9 according to a load condition decided by a position of an acceleration pedal 10. At the time of control, crank shaft rotating speed is held in a constant level for a prescribed period, an engine is operated only in a main injection stroke, an operating amplitude showing an energy conversion value of each cylinder is measured, drift from an average value of the energy conversion value of each cylinder is found out, and then, a period of initial fuel injection in the injector 6 in which the drift is detected is regulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls a fuel injection device (fuel injection valve) for each cylinder, and further controls an individual injection device for dispensing a required amount of fuel in accordance with operating conditions of the engine. The present invention relates to a method for driving an internal combustion engine having an electronic engine control device, in particular, a multi-cylinder piston type engine.

[0002]

2. Description of the Related Art The piston type internal combustion engine used is optimized from various viewpoints in order to significantly reduce exhaust gas pollution. In an internal combustion engine that operates with fuel injection, especially an engine that directly injects fuel into a cylinder with a fuel injection valve, a modern electronic engine control device controls the switching time of the fuel injection valve very accurately, so theoretically Can obtain a very short open cycle, that is, a very small fuel injection amount. Very low fuel injection rates are particularly required for diesel engines operating with "initial injection". When operating as such, the first very small amount for each operation cycle fuels, for example, inject 1.5 mm ³ in the cylinder, then immediately and many more while achieving the process of combustion and load handling capabilities of that time It injects fuel to reduce noise and pollutant emissions. In the Otto engine that operates by direct fuel injection, a requirement has been developed to post-inject a small amount of fuel in order to optimize the operating conditions of an exhaust treatment device connected to the Otto engine.

[0003] A fuel injection device is formed substantially of a carrier body having a nozzle with at least one opening. This nozzle opening is opened and closed by a valve shaft movably incorporated in the carrier body. The valve shaft is connected to a controllable actuator. When actuated and energized by the engine controller, the actuator retracts the valve shaft and allows fuel to be delivered by the injector without blocking the nozzle opening. When the actuator stops,
The valve shaft is substantially biased by the return spring and returns to the closed position. In some injector configurations, the valve shaft is closed by the pressure of fuel entering the injector through a fuel line. Theoretically, the fuel injected by the injector is directly proportional to the open period if it is at a constant pressure in the fuel distribution system ("common rail" system).

[0004] As will be apparent from the above description, the injector is a complex structure having a plurality of movable components. This means that mass production needs to take into account tolerances. Thus, if a very small amount of fuel is to be injected, a small difference in the tolerances can cause a significant deviation from the desired amount. Therefore, the theoretically possible accuracy of achievable fuels with electronic engine control is not actually obtained. Thus, in a multi-cylinder piston internal combustion engine, the actual amount of fuel injected into the cylinder deviates considerably from the desired value determined by engine control. Collecting injectors with the same tolerances through expensive testing and selection processes in the manufacturing process would not solve the above-mentioned problem. Because during the driving period, depending on the operating conditions,
This is because, for example, the appearance of the individual injectors of the engine changes due to uneven wear.

[0005] There are various known methods for equalizing the power measured from the individual cylinders of a multi-cylinder engine. In the case of initial injection or post-injection in which the injection process in question is not an initial control value for the measured output, these methods are usually not applicable.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved method for permitting the initial and post-injection of substantially the same amount of fuel to all cylinders of a multi-cylinder piston internal combustion engine depending on operating conditions. Is to provide.

[0007]

According to the present invention, there is provided, in accordance with the present invention, a crankshaft, a separate injector for injecting fuel into each cylinder, and wherein the injector distributes fuel as a function of operating conditions of the internal combustion engine. A method for equalizing the amount of fuel during the initial injection of fuel into each of the cylinders of the internal combustion engine and during the post-injection associated with the initial injection, the method comprising: Therefore, the following processes, (a) operation of maintaining the rotation speed of the crankshaft constant for a predetermined period, operating the engine only in the main injection process, and (i) operation representing the energy conversion value of each cylinder The amplitude is measured, (ii) the deviation of the energy conversion value of each cylinder from the average value is determined, and (iii) the initial fuel injection by the injector of the cylinder in which the deviation is detected in order to return the energy conversion value to the average value. Period (B) the program of the engine control device adopts the changed period of the initial fuel injection, and one of the initial injection and the post-injection as a function of the changed period of the main injection process of the normal engine operating condition. Controlling the injection period.

[0008] Further advantageous embodiments of the invention are described in the dependent claims.

[0009]

This and other objects, which will become apparent as the description proceeds, have been achieved by the present invention. According to the present invention, simply stated, a method for equalizing the amount of fuel injected as an initial injection and / or a post injection into each cylinder of an internal combustion engine comprises the following steps.
That is, during a predetermined test period, the rotation speed of the crankshaft of the engine is kept constant, the operation amount representing the energy conversion amount in each cylinder is measured, and the energy conversion amount from the average value is measured for each cylinder. The program of the electronic engine control device for determining the deviation, changing the period of fuel injection in the injector of the cylinder for which the deviation has been calculated to restore the amount of energy conversion to the average value, and operating the injector is changed. To control the injector as a function of the period modified by normal engine operation for all operating conditions.

As outlined above, the method according to the invention makes it possible, not only at the time of the final supply of the engine, but also to monitor the function of the injector at predetermined intervals and to adjust for any deviations that have occurred during that time. it can. For example, if the performance of the method according to the invention measures a 10% excess of the average value of the fuel, the injection period of each injector is reduced to such an extent that a predetermined average value is again achieved for such an injector. Is done. The shortened opening period of the injector is added in a later variable operation to all opening processes of the injector. Thus, even in this operation, an open period reduced by such a value provides the desired tolerance equalization. The shortening or extension of the opening period is effected by the earlier or later closing of the injector. This is because when it is open, the engine control device determines in advance the highest control value based on the operating conditions.

[0011] The invention is mainly advantageously implemented in diesel engines operating with initial injection and / or after injection. During this injection period, a certain amount of fuel is introduced into the cylinder irrespective of the amount of fuel subsequently introduced into the cylinder, as controlled by the engine controller and / or the cylinder equalization mechanism depending on the power conditions. You.

Even in the case of post-injection, it is necessary to inject the same amount of fuel into each cylinder in order to guarantee that no cylinder deviates from the predetermined amount of fuel and the timing determination condition.

In the method according to the invention, the degree of energy conversion in the various cylinders is a function of the quantity of fuel injected into the individual cylinders, and such energy conversion can be detected directly at the engine in various ways. The fact that it takes advantage of.

According to a first embodiment of the method, the energy conversion is detected by a speed measurement at the crankshaft. Even when the engine is driven at a constant crankshaft speed, the rotational speed fluctuates due to successive working cycles (strokes) of the individual cylinders. If the energy conversion in each cylinder is the same, the fluctuation of the rotation speed is constant. However, more energy is converted, for example, due to the increased amount of fuel injected in one cylinder,
And / or the amount of fuel injected in the other cylinders is reduced, so that if the energy conversion is low, there may be a slight increase, even if both injectors are controlled by the engine control to have the same open cycle. Energy conversion is known from periodic fluctuations in rotational speed by periodic deviations. Depending on the firing order, the deviations detected from the normal speed fluctuations are assigned to a special cylinder. Since the open period of each injector or multiple injectors changes, the duration of the injection becomes shorter when the energy conversion increases so that the same energy conversion in each cylinder is detected again, or vice versa. Can be applied to the engine controller if the energy conversion becomes longer as the energy conversion decreases, so that a signal representative of such a change in the open duration of each injector can be applied, thereby controlling the next engine operation, in particular the operation of the injector. .

According to another advantageous embodiment of the invention, the energy conversion is detected by measuring the torque at the crankshaft. For the same reasons explained above for fluctuations in the speed, fluctuations in the torque at the crack shaft appear. Therefore, if there is a shift in the energy conversion in one or more cylinders, significant torque fluctuations can be confirmed.

In the two embodiments of the method described above, the energy conversion needs to be tied to the crankshaft speed or torque and the firing sequence of the individual cylinders. According to another embodiment of the invention, The energy conversion is detected by measuring the pressure in each cylinder. If all cylinders have the same pressure behavior during the stroke, the same amount of fuel is dispensed to each cylinder.
If a deviation is detected in the pressure course, it is considered that an excessive or insufficient amount of fuel has been supplied.

In the method according to the invention and the above embodiment of the method, it is costly to drive the engine with a constant load during the period of detecting the energy conversion. The idling load or an arbitrarily selected load is sufficient, and it is costly to drive the engine without a change in speed during the short period of detecting a speed change. The time period for modifying the amount of fuel injected is short compared to the change in speed during normal driving (eg, on a road or highway), so the modification can be performed whether the vehicle is stationary or moving. I can do it.

The method according to the invention, as explained above, is intended for use in piston-type internal combustion engines, in particular for diesel engines in which fuel is injected directly into cylinders with an injector. However, it should be understood that this method is applicable to piston internal combustion engines that inject fuel into the gas intake or exhaust ports of each cylinder.
However, in such a case, it is necessary to consider important conditions for injection to the intake or exhaust port. Therefore,
For example, the detection of energy conversion and the modification of the injection period of the injector should be performed on a warm engine, which can substantially prevent erroneous measurements based on the amount of fuel adhering to the intake port walls. It should be understood that the method is applicable to other types of internal combustion engines, such as "Wankel" type engines.

[0019]

FIG. 1 schematically shows a four-stroke four-cylinder engine having cylinders I, II, III and IV. Each cylinder has one intake valve 1 and one exhaust valve 2. Both cylinder valves 1 and 2 are mechanically driven together by a camshaft or individual electromagnetic actuators. The gas intake valve 1 opens and closes a gas exhaust port 4. A camshaft (not shown) for operating the cylinder valves 1 and 2 is normally driven by a crankshaft 5 as a function of the number of revolutions of the camshaft.

Each of the cylinders has an injector (fuel injector) 6 coupled to a fuel supply, which is preferably maintained under pressure by a fuel pump (not shown). It is formed as a common rail system implied by the distributor piping 7. A number of branch pipes extend from this distributor pipe 7 to the individual injectors 6.

Each injector 6 has a controlled adjustment drive 8,
For example, a magnetic or piezoelectric actuator is provided. Since this actuator is operated by the electronic engine control device 9, the injector 6 is open for a period determined by the engine control device 9, for example, according to a desired load condition determined by the position of the accelerator pedal 10. As a result, an amount of fuel determined by the design of the injector 6 is introduced into each cylinder at the appropriate time during the operating stroke.

As is common in modern electronic engine control systems, the engine controller 9 also controls and regulates the operation of the engine, such as engine speed, supplied torque and refrigerant temperature, in an optimal manner. Receive additional data needed for A signal indicating the rotation speed of the crankshaft at that time is applied to the engine control device 9 by the rotation speed signal transmitter 11. The transmitter 11 of the rotational speed signal also outputs a signal indicating the angular position of the crankshaft, that is, the position of the piston of at least one cylinder. As a result, it is possible to control the actuator 8 of the injector 6 in proportion to the accurately timed rotation speed. When the injector 6 is operated by the electrically controlled actuator 8, the opening / closing timing, the opening period, and the opening frequency can be freely controlled within one working stroke. The engine controller 9 is designed for this purpose in such a way that the programmed inputs can be changed in individual cylinders with respect to the data required for the operation of the fuel injector 6. As a result, not only can the predetermined data depending on the operation of controlling the individual injectors 6 be varied, but also the basic settings can be varied.

Assuming that all injectors 6 _I to 6 _IV are identical in structure, tolerance and operating mode, the same amount of fuel is injected into each cylinder at the same opening and closing times. As a result, the same energy conversion takes place in each of the individual cylinders I-IV, provided that a constant rotational speed is maintained at a predetermined load. As a result, the same energy conversion needs to take place in each of the individual cylinders I-IV if a constant speed is maintained at a given load. This inevitably heterogeneity, i.e. that the variation rotational speed of around the average value n _m which is determined at the point the order of the individual cylinders becomes constant within a variation range as shown in FIG. 2 Lead. Slightly when the rotational speed is increased to the average value n _m within this variation range, a predetermined ignition sequence I- III-IV - associated with the cylinder which is ignited at the time seen in II. If the energy conversion is constant, uniform variation is obtained around the average value n _m which is predetermined by the engine control unit 9.

However, as explained above, due to manufacturing tolerances, the individual injectors will release different amounts of fuel to different cylinders within the opening period specified by the engine control, so that The non-uniform energy conversion takes place in the cylinder. This gives a deviation in the variation of the rotational speed of about necessarily mean rotational speed n _m.

For simplicity, the injectors 6 _I, 6 _II and 6
Assuming that _IV is exactly equal to the tolerance tolerance and that only injector 6 _III has a variation that injects more fuel during the same open period compared to the other injectors, the rotational speed as shown in FIG. The deviation of the curve is obtained. The positive increase in the rotational speed associated with cylinder III is greater than that of the other cylinders.
Because, as the amount of fuel increases, the energy conversion also increases, which necessarily gives an increase in the rotational speed during the working stroke of the cylinder III.

If injector 6 _III injects less fuel than the amount injected by the other injectors, it will result in less energy conversion in cylinder III. This means that the increase in the number of revolutions is correspondingly less than in the other cylinders.

If the engine controller 9 sets the operation to a constant rpm n _m and an excessive rpm has been determined for the cylinder III as shown in FIG. An engine control unit equipped with an appropriate program for detecting the shift in the conversion (in this case, detecting the shift in the rotational speed) eliminates the uneven rotational speed of the cylinder III shown in FIG. , The open period of the injector 6 _III is shortened. Since reduction of such open period is stored in the control program of the engine control unit 9, the injector 6 _III at the next operation is necessarily short open period.

The method according to the invention is used with particular advantage for diesel engines operating with ignition jets or initial (pilot) injection. In such an ignition process, a very small amount of fuel is injected into the cylinder to be ignited in each stroke, and then a larger amount of fuel is introduced in accordance with a predetermined load condition. In this case, the duration of the initial injection for each injector is determined as a function of the modified duration of the main injection event seen for each of the injectors. Therefore, as described above, the engine control device 9 can correct the preliminary injection period for each injector 6 as a result of the test operation according to the measurement method according to the present invention.

In an Otto engine operated by direct injection, for example, in order to improve the efficiency of the exhaust gas catalyst by improving the cold air start condition, a large amount of fuel is injected according to the load condition, and then the exhaust gas temperature is increased accordingly. Therefore, a smaller amount of fuel is injected (post-injection). If any of the cylinders have a non-uniformity in the detected energy conversion deviation of the main injection, such a post-injection adjustment is performed as described above.

Instead of, or in addition to, detecting energy conversion due to non-uniformities in the rotational speed of the crankshaft, the energy conversion can be detected by a torque sensor at the crankshaft. The torque curve substantially coincides with the rotational speed curves shown in FIGS.

By providing each cylinder with a pressure sensor 12 for detecting a pressure change in each cylinder chamber, the Energy conversion in each cylinder can be determined very accurately, and the injection period of the injector 6 can be more accurately varied. . The detection of energy conversion by a pressure sensor is particularly effective in a diesel engine operated by ignition jet injection. Because,
This is because the energy conversion of the amount of fuel introduced by the injection jet is determined by the pressure change.

It is understood that various modifications, improvements and alterations are possible in the above description of the present invention, which are considered to have the same meaning and scope as in the appended claims.

[0033]

As described above, according to the method of the present invention for equalizing the amount of fuel injected to each cylinder of the internal combustion engine, all the cylinders of the multi-cylinder piston internal combustion engine are actually operated in accordance with the operating conditions. Initial injection and post-injection of the same amount of fuel can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a four-stroke, four-cylinder engine;

FIG. 2 is a graph showing a rotation speed curve for the same energy conversion in each cylinder;

FIG. 3 shows a rotational speed curve when there is a deviation in the energy conversion in one of the cylinders.

[Explanation of symbols]

First intake valve 2 exhaust valves 3 intake port 4 exhaust ports 5 crankshaft 6 (6 _I to 6 _IV) injector (fuel injection valve) 7 distributor conduit 8 adjusting driver 9 the engine controller 10 an accelerator pedal I, II, III, IV cylinder _nm Average rotation speed

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Dimitri Shamis 48326 Auburn Hills, Michigan, North Squeiler Road, 201 apartment 1505 (72) Inventor Mark Case 48307, Michigan, United States Rothiester , Iron Wood Court, 1161 Apartments 101

Claims (8)

[Claims] 1. A system comprising: a crankshaft; a separate injector for injecting fuel into each cylinder; and an electronic engine controller wherein the injector is for metering fuel as a function of operating conditions of the internal combustion engine. In a method for equalizing the amount of fuel at either the time of initial injection of fuel into each of the cylinders of the internal combustion engine and the time of post-injection accompanying the initial injection, the following steps are performed: On the other hand, the rotation speed of the crankshaft is kept constant, the engine is operated only in the main injection process, (i) the operation amplitude representing the energy conversion value of each cylinder is measured, and (ii) the energy conversion value of each cylinder is measured. Calculating the deviation from the average value, (iii) varying the period of the initial fuel injection in the injector of the cylinder in which the deviation was detected in order to return the energy conversion value to the average value, and (b) the program of the engine control device. But Adopting a modified period of the early fuel injection to control one of the initial injection and post-injection periods as a function of the modified period of the main injection process under normal engine operating conditions. Features method. 2. The method according to claim 1, wherein the value of the operation is the number of revolutions of a crankshaft. 3. The method of claim 1, wherein the value of the operation is a crankshaft torque. 4. The method of claim 1, wherein the value of the operation is a pressure in a cylinder. 5. The method of claim 1, further comprising operating the engine at a constant load and performing step (a). 6. The method of claim 1, further comprising operating the engine at a constant speed and performing step (a). 7. The vehicle is an output device for a vehicle, further operating the engine to keep the vehicle constant.
The method of claim 1, comprising the step of: 8. The method of claim 1, wherein the engine is a vehicle output device, and further comprising the step of propelling the vehicle to a uniform motion with the engine and performing step (a).