DE102009028111A1 - Method for determining unwanted combustion of engine oil in internal combustion engine, involves determining unwanted combustion of engine oil on basis of determined operating condition of throttle pedal - Google Patents

Abstract

The method involves determining unwanted combustion of engine oil on the basis of determined operating condition of a throttle pedal attached to the internal combustion engine (100). The unwanted combustion of engine oil is determined on the basis of determined existence of a force-fit between the internal combustion engine and a gear assigned to the internal combustion engine and on the remote basis of determined oxygen content of the exhaust gas (120) of the internal combustion engine. An independent claim is also included for a device for determining unwanted combustion of engine oil in an internal combustion engine, particularly in a diesel combustion engine.

Description

The The present invention relates to a method for determining a unwanted combustion of engine oil in one Internal combustion engine, in particular a diesel internal combustion engine, and a corresponding device, in particular for establishing a protection function for damage prevention.

State of the art

The Regeneration of Diesel Particulate Filters (DPF) in the exhaust gas flow of Diesel internal combustion engines are made by burning the stored Particle. For this purpose, the exhaust gas temperature is raised to a value in which the burning begins. To the required temperatures from 600 to 650 ° C, will be a variety of Measures taken. Especially when present lower Engine loads and engine speeds are in addition to injection-side measures, such as the late shift of the main injection (MI), the discontinuation of a post-injection burning in the engine (Pol2) or settling in a diesel oxidation catalyst (DOC) burning Post-injection (Pol1), in addition extensive interventions in the air system of the internal combustion engine, for example via a throttle, required.

Especially at the mentioned low loads can by these regeneration measures due to the high post-injection quantities and the low cylinder pressures an increased oil dilution result.

Under oil dilution be in the context of this application the entrainment of fuels in the lubricating oil of an internal combustion engine and the failure the subsequent fuel evaporation in the oil understood, whereby the oil is constantly diluted further becomes. Oil thinning can, as well as an overfill with engine oil, to an increased or excessive oil level to lead.

By the excessive oil level, for example, over the crankcase breather oil into the combustion chamber get there and burn uncontrollably. This can cause engine damage due to overspeed or increased component load, for example, by overtemperatures lead.

From the DE 199 06 892 C2 and cited therein documents are known in which in order to control a diesel internal combustion engine with at least one adjusting element for influencing the internal combustion engine supplied amount of fresh air in certain operating conditions in which no moment is desired, positioning elements are brought into a position in which the Internal combustion engine supplied fresh air amount assumes a minimum value. Such methods may, for example, act on a throttle valve or an exhaust gas recirculation device.

Usually become invalid injections and invalid Burns detected by various methods. Problematic however, in these methods is inadmissible burns to safely recognize at various operating points, in particular with regard to occurring and to be considered tolerances. Furthermore, such methods require considerable additional effort on sensors, signal processing and / or in the context of the application. It is desirable, a simple and reliable Method for detecting undesired engine oil combustion specify.

Disclosure of the invention

outgoing from the illustrated prior art proposes the present Invention A method for determining an undesirable Combustion of engine oil in an internal combustion engine, in particular a diesel internal combustion engine, having the features of the claim 1 and an associated device with the features of Patent claim 10 before. Advantageous embodiments are the subject the dependent claims and the following description.

Advantages of the invention

By leave the proposed method according to the invention For example, four states or parameter constellations, hereinafter referred to as A to D, determine, by means of which, respectively an excessive, and therefore undesirable, Combustion of engine oil is determined. These four states are explained below.

In a first state A is a positive connection between an internal combustion engine and a to ordered transmission. This corresponds to a coupled state. In state A, furthermore, an accelerator pedal (accelerator pedal) assigned to the internal combustion engine is not operated (alpha = 0). Since no injection takes place in this case, as a rule, ie during normal engine operation, an oxygen content in the exhaust gas of the internal combustion engine of about 21% is to be expected. This oxygen content corresponds to that of the fresh air supplied to the engine. In this case, a lambda probe commonly used for measuring the oxygen content of the exhaust gas will provide a measured value of 32, which lies at the end of the lambda sensor characteristic curve. If a significant deviation of the oxygen content is measured in this state, ie the oxygen content of the exhaust gas is below the stated value of approximately 21%, this indicates an uncontrolled combustion of engine oil.

In a next state B is also traction between the internal combustion engine and the transmission (coupled Status). However, in contrast to the aforementioned condition A the accelerator pedal now operated (alpha ≠ 0), creating an injection to a certain extent. The oxygen content of the exhaust gas will therefore be below the oxygen content of the fresh air of 21%. By comparing the current lambda value with one derived from a lambda probe value map, expected Oxygen content, a deviation value can be detected. Lies a deviation between lambda setpoint and lambda actual value before and this deviation is above predetermined tolerances, which due to drifts in the air flow sensor readings and the Injectors may need to be considered It can be assumed that an uncontrolled combustion of engine oil (so-called "enrichment" of Mixture in the combustion chamber of the internal combustion engine).

In a further state C is no adhesion between the Internal combustion engine and the transmission (disengaged state). Becomes the accelerator pedal is not operated in this state (alpha = 0), is located the engine is idling.

Increases now the speed of the engine to a value that is significantly above the usual idle speed is or even over the regulation speed defined on the basis of safety measures, may also be due to uncontrolled combustion of engine oil be assumed.

In a fourth state D is also no adhesion (disengaged Condition), but the accelerator pedal is operated (Alpha ≠ 0). This indicates that the driver is irrelevant from here Reasons the speed increased without engaged gear. In this case, the security function usually takes effect Drehzahlabregelung. If the Abregeldrehzahl is exceeded despite Drehzahlabregelung, can be assumed that in addition to the through the operation of the accelerator pedal caused fuel injection engine oil is burned.

The previously explained states A to D are summarized in the following table. traction accelerator exhaust gas oxygen rotation speed A Yes No <Fresh air any B Yes Yes <Setpoint any C No No any > Idle speed D No Yes any > Abregeldrehzahl

Becomes one of the states A to D detected, is expediently to close a throttle and / or the exhaust gas recirculation valve (EGR valve) to open to a the oil burning to block supporting oxygen supply and thereby to stop an uncontrolled combustion. Upon detection of States B, C or D is conveniently at the same time to stop the fuel injection.

Further Advantages and embodiments of the invention will become apparent from the Description and attached drawing.

It It is understood that the above and the following yet to be explained features not only in each case specified combination, but also in other combinations or can be used in isolation, without the scope of the present To leave invention.

The Invention is based on embodiments in the drawing schematically and will be described below with reference to the drawing described in detail.

Brief description of the drawings

1 shows a schematic representation of an internal combustion engine, in which the inventive method can be realized.

2 shows courses of injection quantities and speeds at an excessive oil combustion in an internal combustion engine.

3 shows a schematic representation of a running in a control device according to a particularly preferred embodiment method.

embodiments the invention

In 1 is an internal combustion engine 100 represented, in which the inventive method can be realized. In internal combustion engine 100 In particular, the air / exhaust system is shown in detail. The internal combustion engine 100 has an injection or fuel system 109 , which is shown in the figure but for the sake of simplicity only schematically.

The internal combustion engine 100 gets fresh air 110 fed. exhaust 120 is discharged accordingly. The fresh air is supplied via a fresh air line 111 , The exhaust gas is exhausted via an exhaust pipe 121 , The fresh air 110 first goes through an air mass sensor 101 , for example as a hot-film air mass meter (HFM) 101 can be trained. Furthermore, in a corresponding internal combustion engine 100 a compressor 108 be provided. About a throttle 102 the fresh air supply is regulated. The fresh air now passes through a fresh air manifold 131 to the individual cylinders 132 of the engine block 130 , About a fuel system 109 Fuel is burned together with the fresh air supplied.

Via an exhaust manifold 133 will exhaust from the engine block 130 led away. Further, an exhaust gas recirculation system 103 provided by means of which at least a portion of the exhaust gas 120 can be re-supplied to the engine. As a result, a reduction of the oxygen partial pressure in the cylinder can be effected. Corresponding exhaust gas recirculation systems 103 are known from the prior art.

After passing through the compressor 108 is via a temperature sensor 106 for example, a temperature of the exhaust gas 120 certainly. The exhaust 120 is, for example, by an oxidation catalyst (DOC) 104 directed, in which the exhaust gas is cleaned of undesirable combustion products. Before the DOC is a lambda probe 107 intended. The DOC is a particle filter 105 downstream. Downstream of the particulate filter 105 leaves the exhaust 120 the exhaust system.

The present invention makes it possible in a corresponding internal combustion engine 100 by driving a throttle valve 102 and an exhaust gas recirculation system 103 a combustion in the engine block 130 then prevent when an undesirable oil burning is detected. It should be understood that the internal combustion engine 100 even without a part of the components mentioned, in particular without air mass sensor 101 , Compressor 108 , Oxidation catalyst 104 , Particle filter 105 and / or temperature sensor 106 can be realized. Further, other methods and apparatus for measuring exhaust gas oxygen content may also be used.

2 shows measured values in case of excessive oil combustion without suitable protective measures. The measured value curves are in total with 200 designated. In the application of the 2 is on the abscissa 201 applied a time in seconds. On a first ordinate 202 An engine speed is plotted in revolutions per minute. On a second ordinate 203 a total injection amount is plotted in milligrams per stroke.

The measured value course 212 corresponds to the course of the engine speed and thus the first ordinate 202 , The measured value course 213 corresponds to an injection quantity and thus the second ordinate 203 ,

In 2 a first injection occurs in the period of 410 to 423 seconds. A second injection takes place in the period of 424 to 437 seconds. After 437 seconds and up to 480 seconds no injection follows. The ignition was also turned off at 437 seconds. Thus, in the latter period, the engine speed should reach zero because no fuel is available to provide a moment more. Like in the 2 However, this is not the case. The engine speed comes only in the range of 473 to 476 seconds to a standstill. The increase in engine speed is at an increase due to excessive oil combustion in the engine. For the reasons mentioned above, this can damage the motor, z. B. by overspeed (here almost 6000 rpm at a rated speed of 4200 U / min), result.

With in other words, an attempt to turn off the engine at 437 seconds by turning off the ignition and no fuel more is provided. Due to the oil burning suggests but this fails and the engine goes through uncontrolled.

3 shows a schematic representation of a flowchart that corresponds to the method according to the invention. The flowchart is a total of 300 designated. In the with 310 designated blocks that can also run in parallel or individually, the previously explained states A to D are detected. Because of at least one in one of 310 detected blocks detected state A to D is to start from massive oil combustion in the engine.

The corresponding values are transmitted via lines 311 to 314 to a logical unit 320 , which may be implemented as part of an engine control unit (SG) passed. A corresponding functionality can also be implemented in the SG software, which advantageously requires no additional hardware in the control unit. The logical unit 320 is realized as an OR circuit. Located on at least one of the lines 311 to 314 the value of one and can therefore be assumed to be excessive oil combustion in the internal combustion engine, controls the logical unit 320 via lines 321 and 322 the switches 330 and 340 at.

The desk 330 is assigned to a throttle valve. About the in 3 illustrated switching state 334 of the switch 330 is a normal application value 331 on and over a line 333 a certain, beyond the application value 331 defined throttle position. Receives the switch 330 now via line 321 an instruction to make a transition becomes one over line 332 provided instruction for closing a throttle valve via line 333 passed on to the throttle.

Similarly, receives a switch for an exhaust gas recirculation valve 340 usually via a wire 341 an application value for an exhaust gas recirculation valve, the switch position 344 manual 343 and thus passed to the exhaust gas recirculation valve. Receives switch 340 a signal via line 332 , is over line 342 an instruction to the exhaust gas recirculation control passed.

In summary, upon the determination of at least one of the states A to D, the throttle valve is closed and, at the same time, the exhaust gas recirculation valve is opened. In the 3 are shown switch positions that correspond to a normal engine operation in which none of the states A to D was detected.

As mentions all the functionality in the engine control unit (MSG) without additional hardware. In the MSG All required signals are processed and included Recognition of one of the four states mentioned will become a regulator moved in the air system to predetermined positions (opening the throttle and exhaust recirculation valves).

As already explained above, but in 3 for reasons of clarity not shown, may also be provided by the logical unit 320 to cause an interruption of the fuel supply.

It is understood that in the illustrated figures only exemplary Embodiments of the invention are shown. Besides Any other embodiment is conceivable without the frame to leave this invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19906892 C2 [0006]

Claims (11)

Method for determining undesired combustion of engine oil in an internal combustion engine ( 100 ), in particular a diesel internal combustion engine, characterized in that the determining ( 310 On the basis of a determined operating state of the accelerator pedal associated with the internal combustion engine, a determined existence of a frictional connection between the internal combustion engine and a transmission associated with the internal combustion engine and also on the basis of a determined oxygen content of the exhaust gas of the internal combustion engine and / or performed on the basis of a determined speed of the internal combustion engine. Method according to claim 1, in which an undesired combustion of engine oil is determined ( 310 , A, B), when a frictional connection between the internal combustion engine and the engine is determined and the oxygen content of the exhaust gas falls below a predetermined value. Method according to Claim 2, in which undesired combustion of engine oil is determined ( 310 , A), when the oxygen content falls below a threshold value with respect to the air supplied to the internal combustion engine when the accelerator pedal is not operated. Method according to Claim 2, in which undesired combustion of engine oil is determined ( 310 , B), when the oxygen content falls below a threshold value with respect to a Lambdasollwertekennfelds a lambda probe when operating the accelerator pedal. Method according to claim 1, in which an undesired combustion of engine oil is determined ( 310 , C, D), when no frictional connection between the internal combustion engine and the engine is detected and the speed exceeds a predetermined value. Method according to Claim 5, in which undesired combustion of engine oil is determined ( 310 , C), when in non-operation of the accelerator pedal, the speed exceeds a threshold relative to an idle speed of the internal combustion engine. Method according to Claim 5, in which undesired combustion of engine oil is determined ( 310 , D), when the speed exceeds a threshold value with respect to a Abregeldrehzahl the internal combustion engine when operating the accelerator pedal. Method according to one of the preceding claims, in which one of the internal combustion engine ( 100 ) associated throttle valve ( 102 ) and / or an exhaust gas recirculation valve associated with the internal combustion engine ( 103 ) is opened if an undesirable combustion of engine oil is determined. Method according to one of the preceding claims, in which a fuel supply to the internal combustion engine ( 100 ) is inhibited if an undesirable combustion of engine oil is determined. Device for carrying out a method according to one of the preceding claims with an engine control unit, Means for determining an operating condition of the internal combustion engine associated accelerator pedal, means for determining a presence a frictional connection between the internal combustion engine and one of Internal combustion engine associated transmission and further means for Determining an oxygen content of the exhaust gas of the internal combustion engine and / or means for determining a rotational speed of the internal combustion engine. Apparatus according to claim 9, wherein the means for determining an operating state of the internal combustion engine associated accelerator pedal, the means for detecting a presence a frictional connection between the internal combustion engine and one of Internal combustion engine associated transmission and the means for determining an oxygen content of the exhaust gas of the internal combustion engine and / or the means for determining a speed of the internal combustion engine as Part of the engine control unit are formed.

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