KR100743210B1 - Method for the injection of fuel - Google Patents

Abstract

Method for injecting fuel (14a) into a combustion chamber having at least two fuel injectors (12a, 12b, 12c) of a cylinder (11) of a reciprocating internal combustion diesel engine in underload operation comprises alternately injecting the fuel so that during at least two successive working cycles no fuel is injected by at least one of the fuel injectors and during at least two following successive working cycles no fuel is injected by the other fuel injector. An Independent claim is also included for a reciprocating internal combustion engine operated by the method. Preferred Features: Each combustion chamber has two, three or four fuel injectors.

Description

Fuel injection method {METHOD FOR THE INJECTION OF FUEL}

1 is a schematic illustration of a two-stroke diesel engine;

2a is a plan view of a combustion chamber with one actual injection nozzle;

2b is a plan view of a combustion chamber having two actual injection nozzles.

The invention relates to a method of injecting fuel into the combustion chamber of a cylinder of a diesel-type reciprocating piston combustion engine during partial load operation according to the preamble of claim 1.

A method of injecting fuel into the combustion chamber of a cylinder of a low speed two-stroke reciprocating piston combustion engine of a diesel structure is known from the specification of EP 0 775 821. Fuel is injected into the combustion chamber using two to four fuel injection nozzles, which are operated continuously over the entire load range. In particular, the fuel quantity determined for one power stroke during partial load operation is injected by only one injection nozzle and in the subsequent power stroke the fuel quantity is injected through the second injection nozzle so that the required amount of fuel during each power stroke is applied to each injection nozzle. Alternately sprayed through.                         

A disadvantage of this injection method is the fact that incomplete combustion occurs in the combustion chamber, especially during partial load operation, so that the exhaust gases of the combustion have a high concentration of severe smoke.

It is an object of the present invention to operate a reciprocating piston combustion engine of a diesel structure of a type which has more desirable operating characteristics.

This object is met by a method having the features of claim 1.

The dependent claims 2 to 9 also relate to more preferred methods.

It is an object of the present invention that fuel is injected alternately in such a way that no fuel is injected in at least one injection nozzle during at least two consecutive duty cycles and then that fuel is not injected by a subsequent injection nozzle during at least two consecutive duty cycles. In particular, with at least two combustion nozzles associated with each combustion chamber, it is in particular fulfilling a method of injecting fuel into the combustion chamber of a cylinder of a reciprocating piston combustion engine of diesel structure type in partial load operation.

This method can generate hot zones in the combustion chamber. In a preferred method the fuel is injected asymmetrically by the same injection nozzle or injection nozzles for a time period of at least 30 minutes, preferably between 10 and 30 minutes, in order to generate a high temperature in long time operation. The advantage of this method is that the number of heat load changes has the beneficial effect of material fatigue and is reduced compared to that described in the specification of EP 0 775 821. Local high temperatures in and around the combustion zone reduce severe soot. Injection of fuel using only one nozzle has the advantage that the fuel is temporarily injected through this nozzle, which results in a stable, renewable injection. Continuous changes between individual nozzles during the injection have the disadvantage of a larger number of heat load changes.

It is known to the person skilled in the art, for example, in the specification of EP 0 775 821 that a nonuniform temperature distribution in the combustion chamber is disadvantageous, for example because high temperature corrosion can occur in the thermal zone. It is also known to those skilled in the art that non-uniform temperature distributions generate large stresses in the cylinder and in the piston and also increase the fatigue of the material. A person skilled in the art will therefore try as a result of his expertise to avoid uneven temperatures wherever possible in the combustion chamber.

However, it has surprisingly been found that the following advantages arise from the opening of only one nozzle, especially during partial load operation:

The combustion takes place in the same place, so that a local heat zone with a higher temperature appears in the combustion zone. This reduces the more complete combustion of the fuel and the severe soot of the combustion exhaust gases.

Because the temperature level is generally low at partial loads, critical hot corrosion does not occur in the piston despite the uneven temperature distribution.

The injection method according to the invention reduces the number of heat load changes, which reduces material fatigue, so that the life of combustion chamber components, such as pistons, cylinder caps and exhaust valves, is comparable to changes in nozzles at each duty cycle. Is increased.

The fuel is preferably injected through one nozzle in each case.

Partial load operation leads to lower overall temperature levels in the combustion chamber and in the combustion chamber components.

Therefore, the higher stress of the combustion chamber components caused by the non-uniform temperature distribution is limited, so that no excessive or critical stresses are generated in the combustion chamber components. In addition, the occurrence of high temperature corrosion by locally higher combustion chamber temperatures is prevented as a result of lower overall temperature levels.

The method according to the invention is particularly suitable for very low partial load operation of less than 15% of the total load, in particular between 1% and 3% of the total load.

The method according to the invention has the important advantage of enabling combustion that is beneficial to the surrounding environment during partial load operation and of avoiding visually unfavorable, gray or black exhaust fumes. This is particularly preferred for marine diesel engines.

The method according to the invention is suitable for fixed and mobile two-stroke and four-stroke diesel engines, in particular four-stroke diesel engines with a cylinder bore diameter of 150 mm or more, or two-stroke diesel engines with a cylinder bore diameter of 300 mm or more, respectively.

For example, three or four injection nozzles are combined with one combustion chamber. The diesel engine can act as a load and operate in the following operating modes:

In full load operation, fuel is fed into the combustion chamber through all three or four injection nozzles.

In the first partial load range, between 25% and 15% of the total load, fuel is injected into the combustion chamber through the two injection nozzles.

In a second partial load range of less than 15% of the total load, fuel is injected into the combustion chamber through only one of the three or four injection nozzles.

Switching into or out of the spray nozzle during switching to one of three designated operating modes advantageously takes place with a switching function with hysteresis. Thus, starting at the first partial load range, switching to the operating mode according to the second partial load range is made at 12.5% partial load of the total load, while starting at the second partial load range, starting at the first partial load range. The switching to the operating mode accordingly takes place at a partial load of 17.5% of the total load, for example the switching can be made between the first partial load range and the second partial load range.

In addition, the transition from one operating mode to another can occur, for example, in the manner in which time control is used, so that after a certain time, for example 20 seconds after exceeding or falling below a set threshold, This is done in a different mode of operation. In addition, the transition from one operating mode to another can occur suddenly, so that switching to another operating mode takes place immediately at large changes in load, for example 5%.

The invention will be explained below with reference to one embodiment.

Duty cycle refers to a method that occurs during operation of a reciprocating piston combustion engine and, among others, includes the action of a valve, fuel injection, combustion and discharge of combustion gases and will be understood below. Typically, in a two-stroke engine, the duty cycle is completed after one revolution, but in a four-stroke engine, the duty cycle is completed after two revolutions.

1 shows a two-stroke diesel engine 1 with a plurality of cylinders 11 and pistons 10 in which the cooperative action, fuel supply and discharge valves 13 are electronically controlled between the crankshafts 2. To show. Fuel is supplied to the injection nozzle 12 via a tube line 6 and an accumulator 5 with a high pressure pump 4. The hydraulic system comprising the pressure pump 7, the tube line 9 and the accumulator 8 make it possible to act to determine the position of the exhaust valve 13. The two-stroke diesel engine 1, which is scavenged in the longitudinal direction, has an exhaust valve 13 arranged in the center of gravity and a plurality of injection nozzles 12 arranged around the cylinder cover. This two-stroke diesel engine 1 of this kind generally has two to four fuel injection nozzles 12.

2a schematically shows a combustion chamber of a cylinder 11 with three injection nozzles 12a, 12b, 12c arranged around at regular intervals. This method shows partial load operation with one active injection nozzle in each case. Therefore, the fuel 14a is injected through the injection nozzle 12a, but the fuel 14a is not injected through the injection nozzles 12b and 12c at the time shown. During at least two consecutive duty cycles, fuel 14a is injected only through injection nozzle 12a, and then during at least two consecutive duty cycles, fuel 14a is injected only through injection nozzle 12b, And then fuel is injected only through the injection nozzle 12c during at least two different continuous duty cycles. In a particularly preferred method, fuel is supplied from one injection nozzle 12a substantially for another two consecutive duty cycles, for example for 10 to 30 minutes. At that time, fuel is supplied only through the injection nozzle 12b and only through the injection nozzle 12c. This method generates a hot combustion zone, which burns with non-uniform temperature and consequently with less soot in the combustion chamber. Fuel may first be injected through the injection nozzle 12a, then through the injection nozzle 12b and then through the injection nozzle 12c. In addition, the order of the spray nozzles may be changed so that the spray nozzles 12c, the spray nozzles 12b, and the spray nozzles 12a may be operated in the order.

2b shows an example of a method of partial load operation with two injection nozzles 12a, 12b operated simultaneously in each case. Similar to the embodiment according to FIG. 2A, fuels 14a and 14b are only injected through injection nozzles 12a and 12b during at least two successive duty cycles, followed by injection nozzles 12b and 12c during at least two successive duty cycles. Only) and then likewise through the injection nozzles 12c and 12a. This method is repeated continuously. As shown in FIG. 2A, it is preferable to inject fuel for 5 to 60 minutes, in particular for 10 to 30 minutes, through the same injection nozzles 12a, 12b before the other pair of injection nozzles 12b, 12c is changed. Particularly preferred.

The two method examples illustrated in FIGS. 2A and 2B provide a fuel 14a, in order to obtain a temporarily non-uniform temperature distribution in the combustion zone having a longer duration and a more stable injection period, combustion chamber, or, respectively, during partial load operation. 14b) can be asymmetrically injected in a two-stroke or four-stroke diesel engine with two to four fuel injection nozzles 12 in each case per cylinder 11 through an opening in only a portion of the current nozzle. Only two examples are shown. At very low partial loads of 1% to 15% of the maximum load, the method illustrated in FIG. 2 with one active injection nozzle 12a, 12b, 12c in each case is particularly preferred. Injection nozzles 12a, 12b and 12c are sized to operate at nominal load. It is preferable at partial low load to supply a relatively small amount of fuel to the combustion chamber through one injection nozzle 12a, 12b, 12c in order to obtain the desired injection type.

The present invention has the following advantages.

(1) reduce the more complete combustion of fuel and the severe soot of combustion exhaust gases.

(2) Since the temperature level is generally low at partial load, critical hot corrosion does not occur in the piston despite the uneven temperature distribution.

(3) The life of combustion chamber components, such as pistons, cylinder caps and exhaust valves, changes in nozzles at each duty cycle because the number of heat load changes is reduced through the injection method according to the present invention, which reduces material fatigue. Increased in comparison with

Claims (10)

In the method of injecting fuel into the combustion chamber of the reciprocating piston combustion engine (1) of the diesel structure type, having at least two injection nozzles (12a, 12b, 12c) coupled to each combustion chamber, Fuels 14a and 14b are alternately injected in such a manner that no fuel is injected into at least one of the injection nozzles 12a, 12b and 12c during at least two consecutive duty cycles; And then fuel 14a, 14b is not injected by the other injection nozzles 12a, 12b, 12c during at least two consecutive duty cycles. A fuel injection method, characterized in that. The method of claim 1, 2 to 4 injection nozzles are coupled to each combustion chamber. The method according to claim 1 or 2, The fuel is injected by the same injection nozzle at least twice consecutively; And then fuel is injected by another injection nozzle at least twice consecutively. The method of claim 1, Fuel is alternately injected each time by one injection nozzle of the injection nozzle; Fuel is injected by the same injection nozzle during at least two consecutive duty cycles. The method of claim 1, And the fuel is continuously injected by the same injection nozzle for at least 3 minutes. The method of claim 4, wherein The fuel is injected by the same injection nozzle for between 5 and 60 minutes. The method of claim 1, Wherein said reciprocating piston combustion engine is operated at a partial load of less than 10% of the total load. The method of claim 1, Said reciprocating piston combustion engine being operated as a four-stroke or two-stroke diesel engine. The method of claim 1, Wherein said fuel is injected during partial load operation by one, two or three injection nozzles. In a reciprocating piston diesel combustion engine comprising at least one cylinder (11) having at least two injection nozzles (12a, 12b, 12c) associated with each combustion chamber, The fuels 14a, 14b are alternately injected in such a manner that no fuel is injected into at least one of the injection nozzles 12a, 12b, 12c during at least two consecutive duty cycles at partial load; And then means for preventing fuel (14a, 14b) from being injected by other injection nozzles (12a, 12b, 12c) during at least two consecutive duty cycles.

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