JP2004251281A - Method for adding additive to fuel for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a method for reducing formation of deposit in an injecting hole in an injecting valve by mixing additive into fuel for re-eliminating deposit. <P>SOLUTION: Formation of deposit is determined based on at least one variable of engine control. In a first loop 1, if a threshold of a first variable of engine control is exceeded or not is continuously inspected. In a first method step 3.1 for the first loop 1, the first variable of engine control is observed. For each value of the first variable of engine control, if it is over or under the threshold of the first variable is inspected in a first response 4.1. In a case where the value of the first variable of the engine control is over the threshold value for the first variable of engine control, the first response 4.1 is taken as a start point to go through a first arrow 5.1 to reach an OR logic coupling part or a logical addition coupling part (boolesche Order-Verknuepfung) 8, and then to go through an arrow 9 to reach a second method step 10 where mixing of additive is executed. Mixing of additive to fuel is automatically executed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The invention relates to the addition of additives to fuels for internal combustion engines in order to avoid and remove deposits on parts of the internal combustion engine of the vehicle, in particular on injection valves that inject fuel into the cylinders of the internal combustion engine via injection holes. A method for adding.

  When directly injecting fuel, deposits are often formed in the "injection holes" of the injector. This deposit forms on the side of the injection hole facing the combustion chamber of the internal combustion engine at high temperatures and consists mainly of carbides. The formation of this deposit is also called coking. Since the coking reduces the cross section of the injection hole, the volumetric flow that can flow through the injection hole of the injection valve per unit time is also reduced. Injecting the same volume flow requires a longer time for injectors with deposits than for injectors without deposits. In addition, fuel spray is negatively affected by deposits, for example, the jet shape, jet angle, or droplet size may change. This has a direct effect on the formation of the air-fuel mixture. Therefore, the deposits formed in the injection holes of the injection valve increase the emission and increase the consumption of the internal combustion engine. On the contrary, it can lead to a “misfire”.

For example, from EP 0 414 963, "additives" are already known as fuel additives, which avoid and remove deposits on parts of the internal combustion engine, for example on injection valves. The disadvantage is that this additive had previously had to be manually filled into the fuel tank at predetermined time intervals. At this time, although the deposit is not present in the internal combustion engine, the additive is unnecessarily mixed in, or the number of additives is too small, and the deposit is generated in the internal combustion engine. In some cases, it may no longer be completely removed by the additive. Deposits have a negative effect on the functioning of the internal combustion engine.
European Patent No. 0414963 German Offenlegungsschrift 4 117 440

  It is therefore an object of the present invention to improve a method of reducing the formation of deposits at the injection holes of an injection valve by incorporating additives into the fuel in order to remove the deposits again.

  In order to solve this problem, the method according to the invention determines the deposit formation from at least one variable of the engine control.

  The advantage of the method according to the invention over the prior art is that the formation of deposits is recognized from the variables of the engine control, so that an improvement can easily be obtained in that additives can be incorporated as required. Is what you can do. In this way, the injection holes are released from the deposits, so that the formation of the air-fuel mixture is not impaired.

  Advantageous modifications and improvements of the method according to claim 1 are possible with the measures described in claim 2 and subsequent claims.

  It is particularly advantageous if the additive is automatically incorporated into the fuel if one variable of the engine control is above a predetermined threshold. Exceeding this predetermined threshold value is an indication of the formation of deposits at the injection holes.

  It is furthermore advantageous if the additive is automatically mixed into the fuel if at least two variables of the engine control each exceed one predetermined threshold value. This is because the recognition of deposits formed in the injection holes is made more certain by exceeding at least one other predetermined threshold.

  It is also advantageous if a correction value for adapting the fuel mass desired to be injected into the cylinder is used as a variable of the engine control. This is because this change in the correction value indicates the formation of deposits in the injection holes.

  It is furthermore advantageous if the injection time of the fuel into the cylinders of the internal combustion engine is used as a variable of the engine control. This is because the change in the injection time also indicates the formation of deposits in the injection holes.

  It is particularly advantageous if additives are mixed into the fuel tank from the auxiliary tank.

  It is particularly advantageous to mix the additives automatically into the fuel tank or into the fuel line upstream or downstream of the fuel pump. This is because this is a particularly advantageous embodiment for blending additives into the fuel.

  It is also advantageous to signal the formation of deposits in the internal combustion engine by means of a control lamp provided on the vehicle. In this way, the driver of the vehicle takes care to mix the additive with the fuel.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a flow chart of a method according to the invention according to a first embodiment, in which a signal of the operating conditions of the internal combustion engine is received in order to generate a signal for controlling the start of the internal combustion engine, It is used in internal combustion engines that have an electronic control unit for processing for engine control.

  In a first loop 1, it is checked continuously whether a threshold value of a first variable of the engine control is exceeded. In a first method step 3.1 of a first loop 1, a first variable of the engine control is observed. Each value of the first variable of the engine control is subsequently checked in a first response 4.1 as to whether it is above or below a threshold of the first variable. If the value of the first variable of the engine control exceeds the threshold value of the first variable of the engine control, starting from the first response 4.1, via the first arrow 5.1, an OR logical connection or logic is provided. A bleedsche Oder-Verknupfung 8 is reached and from there via arrows 9 a second method step 10 in which the incorporation of additives is carried out. At that time, the mixing of the additive into the fuel is automatically performed.

  The additive can for example be led from the auxiliary tank to the fuel tank via a supply line. However, it is also possible for the additive to be introduced into the fuel line via the supply line, for example upstream or downstream of the fuel pump, whereby the additive mixes with the fuel there and together with the fuel in the direction of the internal combustion engine. At the injection valve. The additive mixed with the fuel comes into contact with the injection hole of the injection valve when injecting the fuel into the combustion chamber, and thus the deposits formed thereon can be removed. The additive subsequently burns with the fuel in the combustion chamber.

  If the value of the first variable of the engine control is less than the threshold value of the first variable of the engine control, no mixing takes place and the first response 4.1 is used as a starting point and the third response is taken via the third arrow 11.1. The method returns to step 3.1. The first loop 1 is executed, for example, continuously.

  In a second loop 2 it is checked continuously if a second variable threshold of the engine control is exceeded. In a first method step 3.2 of a second loop 2, a second variable of the engine control is observed. Each value of the second variable of the engine control is subsequently checked in a first response 4.2 as to whether it is above or below a threshold of the second variable. If the value of the second variable of the engine control exceeds the threshold value of the second variable of the engine control, the OR logic connection 8 via the first arrow 5.2 starting from the first response 4.2 From there, via arrow 9 to a second method step 10 in which the incorporation of the additive takes place. If the value of the second variable of the engine control is below the threshold of the second variable of the engine control, no mixing takes place and the first response 4.2 is used as a starting point and the first response via the third arrow 11.2. Return to method step 3.2. This second loop 2 is also executed, for example, continuously.

  As soon as one of the threshold of the first variable of the engine control and the threshold of the second variable of the engine control is exceeded, the mixing of the additive into the fuel takes place according to the OR logic connection 8. Is

  In the pre-control of the engine control, the fuel mass to be injected is calculated in consideration of many factors. The engine control calculates an injection time for opening the injection valve, which is necessary for injecting the calculated fuel mass into the combustion chamber under pressure from the fuel mass to be injected.

  In many operating conditions a stoichiometric air-fuel ratio is required in the combustion chamber. The stoichiometric air-fuel ratio applies when the air mass required for complete combustion of the injected fuel mass is exactly present in the combustion chamber. "Lambda-Wert" represents the ratio of the actual air mass in the combustion chamber to the air mass required for stoichiometric combustion. If the lambda value is equal to 1, stoichiometric combustion occurs. If the lambda value is greater than one, fuel starvation has occurred and the air-fuel mixture is considered to be too lean. If the lambda value is less than 1, oxygen deficiency has occurred and the air-fuel mixture is considered to be too rich.

  In the lambda closed loop control, when the lambda sensor confirms a required air-fuel ratio, for example, a deviation or deviation from a stoichiometric air-fuel ratio, the fuel mass calculated by the previous control and corrected by the injection valve is corrected. However, the correction of the deviation from the required air-fuel ratio can only be carried out with a delay. In order for there to be as little deviation from the required air-fuel ratio as possible, or for the difference between the injected fuel mass and the required fuel mass for the required air-fuel ratio to be as small as possible The pre-control must calculate the fuel mass to be injected as accurately as possible. Therefore, the fuel mass to be injected, which is calculated by the pre-control, is continuously calculated anew and is newly adapted to the respective operating conditions. In this way, the lambda closed-loop control is relieved and there is less need for post-adjustment. The fuel mass to be injected, which is calculated by means of the pre-control, is additionally corrected in "Gemisculation" with at least one correction factor. In this case, the mixture adaptation takes place only in a predetermined operating mode of the internal combustion engine, so-called "homogeneous operation". The at least one correction coefficient is, for example, multiplied by the fuel mass to be injected, calculated by the previous control, but may be added to the fuel mass to be injected, calculated by the previous control.

  A method for adjusting the air / fuel mixture is known, for example, from DE-A 41 17 440, the content of which is clearly part of the disclosure of the present application.

  In the mixture adaptation, at least one correction factor is adapted in order to achieve the required air-fuel ratio again in the combustion chamber, since the injected fuel mass is reduced when deposits form in the injection holes of the injection valve. It must be. Due to the temporal change of this correction factor, the formation of deposits can thus be recognized.

  Apart from coking or carbon deposition, there are other factors that change at least one correction factor for the mixture adaptation. However, because these other factors have, for the most part, a much smaller effect on at least one correction value than coking, coking is definitely distinguished from the other factors. Can be

  At least one correction value of the mixture adaptation is used in a first loop 1, for example, as a first variable of the engine control.

  Since the mixture adaptation is not active in "stratified operation" of the internal combustion engine, the correction value for mixture adaptation is equal to 0 in stratified operation, so that the first loop cannot cause additive entrainment in stratified operation. . A corresponding threshold value is assigned to the correction value of the mixture adaptation. As soon as the correction value exceeds the threshold value, it must be understood that deposits have formed in the injection holes. The threshold is determined experimentally.

  The injection time can also be used to recognize the deposit. For example, the injection times of all cylinders are examined and an average value, i.e. the average injection time, is determined from these values of the injection times. Since the mass of fuel to be injected, and therefore the injection time, depends on the power required by the internal combustion engine via the gas pedal, the quotient derived from the required power and the injection time, i.e. only the exponent, is a variable of the engine control. Can serve as. The power required via the gas pedal is also called the driver desired torque.

  An index obtained from the driver desired torque and the injection time is used in the second loop 2 as a second variable of the engine control, for example.

  A corresponding threshold value is assigned to an index obtained from the driver desired torque and the injection time. As soon as this index is above its corresponding threshold value, it must be understood that deposits have formed in the injection holes.

  The amount of fuel injected is reduced by deposits formed in the injection holes. As a result, the air-fuel ratio in the combustion chamber of the internal combustion engine changes, and the lambda value increases. The lambda sensor measures the increase in the residual oxygen content of the exhaust gas, since less fuel is burned, and therefore excess oxygen intended for combustion with the fuel. Lambda closed-loop control addresses the rising residual oxygen content of the exhaust gas with an extended injection time to maintain the required air-fuel ratio.

  Instead of automatically mixing the additives into the fuel, it is also possible to signal the formation of deposits, which is determined from at least one variable of the engine control, using a control lamp provided on the vehicle. In this way, the driver of the vehicle indicates that the next time fuel is refilled into the fuel tank, the additive should be mixed with the fuel in order to remove the deposits formed in the injection holes of the injector. You will care.

  The method according to the invention can be used, for example, in gasoline or diesel engines.

  Known additives are, for example, additives from Chevron Oronite (model no. OGA72002) or the additive Optimax from Shell.

  In the method shown in FIG. 2, parts which remain the same or work the same as in the method shown in FIG. 1 have been given the same reference numerals.

  FIG. 2 shows a flow chart of the method according to the invention according to a second embodiment. The method shown in FIG. 2 is different from the method shown in FIG. 1 in that an AND logical connection unit or a logical product logical unit (pooles Un-Verknueffung) 12 is used instead of the OR logical connection unit 8.

  For example, based on the first loop 1, even if the only variable of the engine control indicates deposits, no additive incorporation has yet taken place. For example, based on the second loop 2, it is only after confirming that sediment is present because another variable of engine control also exceeds a predetermined threshold, the additive is added to the fuel in response to the AND logic connection. Mixed. In this way, the likelihood of unnecessary mixing of engine controls based on variables containing errors is reduced.

FIG. 4 is a diagram illustrating a flowchart according to the first embodiment.

FIG. 7 is a diagram illustrating a flowchart according to a second embodiment.

Explanation of reference numerals

1 First Loop 2 Second Loop 3.1, 3.2 First Method Step 4.1, 4.2 First Response 5.1, 5.2 Arrow 8 OR Logical Combiner 9 Arrow 10 Method step 2 11.1, 11.2 Arrow 12 AND logical connection

Claims (9)

  For adding additives to the fuel for the internal combustion engine, in order to avoid and remove deposits on parts of the internal combustion engine of the vehicle, in particular on injection valves that inject fuel into the cylinders of the internal combustion engine via injection holes. A method for adding an additive to a fuel for an internal combustion engine, the method comprising determining deposit formation from at least one variable of engine control.   The method of claim 1, wherein an additive is added to the fuel when one of the engine control variables exceeds a predetermined threshold.   2. The method according to claim 1, wherein the additive is added to the fuel if at least two variables of the engine control each exceed a threshold value.   4. The method as claimed in claim 2, wherein a correction value for adapting the fuel mass desired to be injected into the cylinder is determined as a first variable of the engine control.   4. The method as claimed in claim 2, wherein the time of injection of fuel into the cylinder of the internal combustion engine is determined as a second variable of the engine control.   6. The method according to claim 5, wherein an average injection time is determined as the injection time, which is an average over all cylinders of the internal combustion engine.   4. The method according to claim 2, wherein the additive is added from an auxiliary tank.   4. The method according to claim 2, wherein the additive is mixed in the fuel tank or in the fuel line upstream or downstream of the fuel pump.   The method according to claim 1, wherein the formation of deposits in the internal combustion engine is notified using a control lamp provided on the vehicle.

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