DE10306857A1 - Internal combustion engine fuel system operating method, by triggering reaction if amount of lubricant entering fuel exceeds predetermined amount - Google Patents

Abstract

Fuel is fed by a fuel pump (20) which is lubricated by a lubricant other than fuel. If the amount of lubricant entering the fuel exceeds a predetermined amount, a reaction is triggered. The viscosity of the lubricant may be determined in order to determine the amount of fuel that has entered it. The same lubricant may be used to lubricate the fuel pump and the internal combustion engine. Independent claims are included for (1) a computer program; (2) an electrical storage medium; (3) a control unit; (4) and an internal combustion engine.

Description

State of technology

The invention relates to a method for operating an internal combustion engine in which fuel from a Fuel pump promoted which is lubricated at least in regions by a lubricant which is not fuel.

The invention further relates to a Computer program, an electrical storage medium and a control and / or control device. The present invention also relates to an internal combustion engine.

A process of the aforementioned Art is known from the market. For example, it is known the fuel first by means of an electric feed pump on a pre-pressure and then in a high pressure fuel pump to compress a very high pressure. The fuel then continues into a fuel rail, and from there to injectors that inject the fuel directly into the combustion chambers assigned to them. The high pressure fuel pump is in this known method of a camshaft of the internal combustion engine driven (basically but is also a drive over a crankshaft, a balance shaft, etc., possible). The drive shaft of the High pressure fuel pump and the corresponding bearings are at the Lubricant circuit of the internal combustion engine connected. The Sealing between the fuel conveying area and the lubricant leading The drive area takes place in the known high-pressure fuel pump with suitable sealing rings or sealing sleeves.

From the DE 44 23 241 A1 it is known that when an internal combustion engine is cold started, fuel can get into the engine oil, which evaporates again from the engine oil when the internal combustion engine is operating with increasing temperature. The evaporated fuel is supplied to the combustion system via the crankcase ventilation, which leads to mixture enrichment.

The present invention has the Task to develop a method of the type mentioned at the beginning that the corresponding internal combustion engine operated even more reliably can be.

This task is done in a process of the type mentioned in that when a fuel entry the lubricant reaches or exceeds a certain volume, triggered a reaction becomes.

With a computer program, the Task solved by that it's performing of such a method and programmed on a storage medium is saved.

With an electrical storage medium accomplished the task that a computer program of the above type is stored on it.

In a control and / or regulating device for an internal combustion engine the task is solved by that it is programmed to be used in the above procedure.

In an internal combustion engine accomplished the task that it has a control and / or regulating device of the above type.

Advantages of invention

According to the invention it was recognized that the seal leading between the fuel Förderbereich and the leading lubricant Basically, the drive range of the fuel pump is rarely perfect So there may always be some leakage from the bottom a comparatively high pressure fuel in the under comes with a comparatively low pressure lubricant. About that in addition, such a seal is a comparative one highly stressed component, which can fail completely in extreme cases. In the latter In this case, there is a massive entry of fuel into the lubricant. However, by adding fuel to the lubricant reduces the lubricating properties of the lubricant.

If the fuel pump has a has its own lubricant system, elevated only the bearing friction of the fuel pump. In contrast, the fuel pump is connected to the lubricant system of the internal combustion engine connected, increase the bearing friction of the corresponding bearing of the internal combustion engine. This reduces the life of the fuel pump and possibly also the internal combustion engine, and in extreme cases can even become one sudden failure the fuel pump or the internal combustion engine.

All this is done with the method according to the invention avoided: by monitoring the amount of fuel input into the lubricant and that Trigger an appropriate response when reaching a certain extent or exceeded can in time for an increasing fuel input in the lubricant, i.e. an inadmissible thinning of the lubricant by the Fuel to be responded to. A dilution of the lubricant in an extent that causes permanent damage to the fuel pump and / or the internal combustion engine, can thus be avoided. As a result, the service life of the internal combustion engine and its operational reliability elevated.

Advantageous further developments of Invention are in subclaims specified.

In a first particularly preferred Further development of the method according to the invention it is proposed that to determine the amount of fuel input a viscosity of the lubricant is determined. The viscosity of the lubricant it is a parameter, which by the mixing of the lubricant is directly influenced by the fuel, because the viscosity of Fuel differs significantly from that of more common Lubricant. The viscosity of the lubricant is over it an essential parameter for the lubricating properties of the lubricant.

If the viscosity is monitored, the advantages according to the invention therefore particularly reliable be achieved.

If for the lubrication of the fuel pump and the internal combustion engine uses the same lubricant, it is additional or alternatively advantageous if for determining the amount of fuel input a deviation of an air ratio lambda from a target value is determined becomes. This is based on the knowledge that the fuel pump fuel entering the lubricant when the internal combustion engine is operating evaporates with increasing temperature. The evaporated fuel is usually about a Crankcase ventilation of the Combustion supplied. hereby the mixture is enriched, which changes the air ratio lambda.

The air ratio lambda is used in conventional internal combustion engines recorded anyway, so that in this variant of the method according to the invention, if appropriate a fuel entry can be recognized without additional Installations are required. If necessary, a course monitors the air ratio lambda to the influence of the evaporation from the lubricant Fuel on the Lambda air ratio from others the Lambda air ratio differentiate influencing variables to be able to.

It is also proposed that the Determining the amount of fuel input the temperature of the Lubricant and / or a component temperature of the fuel pump and / or the internal combustion engine is determined. That is again based on the knowledge that by diluting the lubricant by the fuel's lubricity is reduced, which is the friction in the area of the bearing surfaces Fuel pump and / or the internal combustion engine increased. hereby increases also the temperature at the corresponding points. Appropriate Temperature sensors are common Internal combustion engines are present anyway, so that the advantages according to the invention are also present here additional Installations can be achieved. It should also be noted that if necessary a surveillance the influence of the fuel input of the course of the corresponding temperature in the lubricant to the temperature of others the appropriate Differences influencing temperature differ can be.

It is particularly advantageous if a flow path, which of an installation area of a piston seal of the fuel pump leads to a low pressure area, blocked in a direction from the low pressure area to the installation area of the piston seal becomes. This ensures that the failure of the Piston seal of the fuel pump the fuel is not completely unobstructed can flow into the lubricant from the low pressure area. This also increases the reliability when operating the internal combustion engine.

In response to an illegal fuel entry can send information, in particular a warning signal, to the user the internal combustion engine are output, and / or the fuel pressure can be automatically lowered, and / or the internal combustion engine be turned off automatically. The first reaction can be, for example an acoustic or visual signal, which the user prompts the internal combustion engine only in a low power range operate and immediately to go to a workshop. The decrease in fuel pressure is reduced the pressure difference between the fuel and the lubricant and thus also the further entry of the fuel into the lubricant, which is particularly important if the seal between the fuel is faulty leading and the leading lubricant Area offers advantages.

An automatic shutdown of the internal combustion engine is the ultimate way to do costly and fatal damage to keep away from the internal combustion engine. If necessary, the three measures also run in stages, that is it will initially issued a warning signal, then, if the Fuel entry into the lubricant, the fuel pressure automatically lowered, and if the fuel input increases again the internal combustion engine is automatically switched off in the lubricant or a start impossible made.

The following are particularly preferred exemplary embodiments of the present invention with reference to the accompanying Drawing explained in detail.

The drawing shows:

1 a schematic representation of an internal combustion engine with a fuel system and a fuel pump;

2 a schematic section through the fuel pump of 1 ;

3 a flowchart of a method for operating the internal combustion engine of 1 ; and

4 a view similar 2 an alternative embodiment of a fuel pump.

description of the embodiments

In 1 an internal combustion engine bears the overall reference number 10 , It drives a motor vehicle, which in 1 but is not shown. The internal combustion engine 10 includes a fuel system 12 ,

To the fuel system 12 belongs to a fuel tank 14 , from which an electric fuel pump 16 compresses the fuel to a pre-pressure of approximately 4 bar and to an inlet 18 a high pressure fuel pump 20 promotes. This compresses the fuel to a very high pressure level (approximately 100 bar) and delivers it from an outlet 22 to a fuel rail 24 , From there, the fuel goes through fuel injectors 26 in these directly assigned combustion chambers 28 (For reasons of clarity, the injectors and combustion chambers are not all provided with reference symbols).

How out 2 can be seen, it is the high-pressure fuel pump 20 a 1-cylinder radial piston pump. It is lubricated by a lubricant, which is the high-pressure fuel pump 20 through channels 30 fed and via channels 32 is dissipated from this. The canals 30 and 32 are at an in 1 lubricant system shown only symbolically 34 the internal combustion engine 10 connected. This can include, for example, a lubricant pump, a lubricant filter, and so on.

The viscosity of the lubricant is checked by a viscosity sensor 36 detected. The temperature of a cylinder head, which in 1 is not shown, is from a temperature sensor 38 detected. The combustion exhaust gases are through an exhaust pipe 40 derived in which a catalyst 42 is arranged. An air number lambda in the exhaust gas is generated by a lambda sensor 44 detected.

The viscosity sensor 36 , the temperature sensor 38 and the lambda sensor 44 deliver signals to a control and regulating device 46 which, among other things, the fuel injectors 26 controls.

The high pressure fuel pump 20 includes a housing 48 ( 2 ) in which a piston 50 is slidably axially movable. Between the case 48 and the piston 50 is a funding room 52 available, which has a check valve 54 with the inlet 18 , and via a check valve 56 with the outlet 22 connected is. The piston 50 is from a cam 58 a drive shaft 60 in a reciprocating motion. The drive shaft 60 with the cam 58 is in a drive room 62 inside the case 48 arranged. It is stored opposite this via bearings, not shown.

The drive room 62 is with lubricant 64 filled which the drive room 62 over the channel 30 fed and from this by means of the channel 32 is dissipated. The fuel-carrying delivery room 52 is against the lubricant 64 leading drive room 62 through a piston seal 66 sealed. Immediately before the piston seal 66 , to the funding room 52 is an annular relief space 68 available through a relief channel 70 with the inlet 18 connected is. Through the relief room 68 and the relief channel 70 is in operation of the high pressure fuel pump 20 prevents it from sticking to the piston seal 66 builds up a large pressure differential which the piston seal 66 stressed and their lifespan reduced excessively.

A method for operating the internal combustion engine 10 will now refer to 3 explained. The method is a computer program on a memory 71 of the control unit 46 stored.

After a starting block 72 are in one block 74 the signals from the viscosity sensor 36 detected. In one block 76 the detected signals are compared with a first limit value. If in the block 76 it is found that in the block 74 recorded viscosity is below the first limit (the lubricant has become thinner), is in the block 78 an acoustic and an optical warning signal to the user of the internal combustion engine 10 output. This can be, for example, a warning lamp on the dashboard of the motor vehicle, as well as a synthetic speech output. In one block 80 also the fuel pressure at the outlet 22 and in the funding room 52 reduced to a pressure of approximately 40 bar. This is possible, for example, by means of a quantity control valve (not shown) or another pressure setting device.

In response to the warning signals in the block 78 can the user of the internal combustion engine 10 turn them off, for example. This will be in the block 82 queried. Will the internal combustion engine 10 against it despite the warning signals in the block 78 continues to operate, is in the block 84 checked whether the viscosity value drops further and reaches a second limit value. The answer is in the block 84 "yes" is in the block 86 the operation of the internal combustion engine 10 automatically set.

Regardless of whether the internal combustion engine 10 was turned off by the user (block 82 ) or was switched off automatically (block 86 ), is in the block 88 a system analysis is carried out, and an entry is made in a fault memory, which can be read out, for example, by a diagnostic device, and which a person carries out maintenance of the internal combustion engine 10 the impermissible drop in viscosity and the possible cause of a defective piston seal 66 points. The process ends in a block 90 ,

In an embodiment not shown game instead of the signals from the viscosity sensor 36 the signals from the temperature sensor 38 and / or the lambda sensor 44 evaluated. It is also possible that the signals from the viscosity sensor 36 with the help of the signals from the temperature sensor 38 and / or the lambda sensor 44 be subjected to a plausibility check.

At the in 1 illustrated internal combustion engine 10 becomes the drive room 62 the high pressure pump 20 from the lubricant system 34 the internal combustion engine 10 supplied with lubricant. However, the method described above is also possible in an internal combustion engine with a high-pressure fuel pump, the drive chamber of which is part of a closed system with a so-called "disposable lubricant filling", or the drive chamber is supplied by its own lubricant supply. It is also noted that the reduction in fuel pressure 80 Advantageously so far that a combustion process with direct fuel injection is just barely possible. Under certain circumstances, this can lower the fuel pressure to that of the electric fuel pump 16 available pressure level. The first limit, which is in the block 76 is checked, is preferably selected so that when this first limit value is reached, the motor vehicle into which the internal combustion engine 10 installed, can still be driven into a workshop easily and without the risk of consequential damage.

In the above embodiment, a high pressure fuel pump 20 with a single radial to the drive shaft 60 arranged pistons 50 shown. The described method can, however, be used just as well in multi-piston pumps or pumps of another type. In principle, the use of the method described is suitable for pumps which deliver media whose viscosity differs from the lubricant used. However, the method described is particularly advantageous in the case of so-called “plug-in pumps”: these are high-pressure fuel pumps which are inserted into an opening in a crankcase, a control housing or a cylinder head of an internal combustion engine and from a separate cam of a crankshaft, camshaft , Balance shaft, etc. are driven.

In 4 is an alternative design of a high pressure fuel pump 20 shown. Such elements and areas, which have equivalent functions to elements and areas of the 2 high pressure fuel pump shown 20 have the same reference numerals. They are not explained in detail again.

In contrast to that in 2 high pressure fuel pump shown 20 is with the in 4 high pressure fuel pump shown 20 in the relief channel 70 between the relief space 68 and the inlet 18 a check valve 92 present, which is the flow path from the inlet 18 to the relief room 68 blocks, but allows a flow in the opposite direction. This prevents the piston seal from failing completely 66 the fuel freely from the inlet 18 over the relief room 68 in the drive room 62 arrives and in this way large amounts of fuel with the in the drive room 62 existing lubricant 64 mix.

Claims (11)

Method of operating a fuel system ( 12 ), preferably an internal combustion engine ( 10 ) using fuel from a fuel pump ( 20 ) which is supported at least in some areas by a lubricant ( 64 ) is lubricated, which is not fuel, characterized in that when a fuel entry into the lubricant ( 64 ) reaches or exceeds a certain extent ( 76 . 84 ), a reaction is triggered ( 78 . 80 . 86 ). A method according to claim 1, characterized in that a viscosity of the lubricant (to determine the extent of the fuel input 64 ) is determined ( 74 ). Method according to one of claims 1 or 2, characterized in that for the lubrication of the fuel pump ( 20 ) and the internal combustion engine ( 10 ) the same lubricant ( 64 ) is used, and that a deviation of an air ratio lambda from a target value is determined to determine the extent of the fuel input. Method according to one of the preceding claims, characterized in that the temperature of the lubricant and / or a component temperature of the fuel pump and / or the internal combustion engine ( 10 ) is determined. Method according to one of the preceding claims, characterized in that a flow path ( 70 ), which of an installation area ( 68 ) a piston seal ( 66 ) the fuel pump ( 20 ) to a low pressure area ( 18 ) leads in a direction from the low pressure area ( 18 ) to the installation area ( 68 ) the piston seal ( 66 ) is blocked ( 92 ). Method according to one of the preceding claims, characterized in that the reaction comprises that information, in particular a warning signal, is output to the user of the internal combustion engine ( 78 ), and / or that a fuel pressure is automatically reduced ( 80 ), and / or that the internal combustion engine automatically is turned off ( 86 ). Computer program, characterized in that it is programmed to carry out the method according to one of the preceding claims and on a storage medium ( 71 ) is saved. Electrical storage medium ( 71 ) for a control unit ( 46 ) an internal combustion engine ( 10 ), characterized in that a computer program according to claim 7 is stored on it. Control and / or regulating device ( 46 ) for an internal combustion engine ( 10 ), characterized in that it is programmed for use in a method according to one of claims 1 to 6. Internal combustion engine ( 10 ), in particular for a motor vehicle, with a control and / or regulating device ( 46 ), which is programmed for use in a method according to one of claims 1 to 6. Internal combustion engine ( 10 ) according to claim 10, characterized in that in a flow path ( 70 ), which of an installation area ( 68 ) a piston seal ( 66 ) the fuel pump ( 20 ) to a low pressure area ( 18 ) leads, one towards the low pressure area ( 18 ) to the installation area ( 68 ) the piston seal ( 66 ) acting flow barrier ( 92 ) is available.