GB2597953A - Method and leakage detection unit of an internal combustion engine for localizing leakage of at least one gaseous medium at the engine - Google Patents

Abstract

The present invention relates to a method for localizing leakage of at least one gaseous medium at an internal combustion engine (10), comprising a step of emitting at least one electromagnetic radiation beam (two shown 26a,26b, with different wavelengths) through at least one analysis section (28) disposed at or in the vicinity of an outer surface of the engine (10); a step of measuring a radiation characteristic of the radiation beam (26) after passing through the analysis section (28); and a step of determining a leakage of the gaseous medium into the analysis section (28) in dependence on the measured radiation characteristic.

Description

Description

Method and leakage detection unit of an internal combustion engine for localizing leakage of at least one gaseous medium at the engine

Technical Field

[0001] The present invention relates to a method for localizing leakage of at least one gaseous medium at an internal combustion engine. Further, the present invention relates to a leakage detection unit of an internal combustion engine and a test bench for an internal combustion engine which are configured for localizing leakage of at least one gaseous medium at the engine.

Technological Background

[0002] During operation and manufacturing, internal combustion engines may be affected by leakage. The effects of leakage frequently become only apparent at higher engine load due to higher pressure and high temperature conditions prevailing in the engine which lead to material extensions and thus to extensions of leaks. Particularly, an air fuel supply system and exhaust system of the engine may be affected by leakage as high pressure and high temperature gases and fluids flow therethrough.

[0003] In the technical field of internal combustion engines, a widely used method for detecting and localizing leaks or leakage at the engine is to spray a soap solution onto the engine to cover its outer surface with a thin soap film. The presence of a leak or leakage is then confirmed by bubbles formed in the soap film. For doing so, it is required that technical personnel approaches the engine during its operation in order to apply the soap solution and to inspect the surface covered by the soap film. However, since parts of the engine are only accessible with difficulties for the personnel, this approach may be time and cost consuming in order to ensure a proper leakage inspection.

[0004] Furthermore, for determining whether an engine as such is affected by leakage, the use of gas sensors is known which detect the presence of leakage gases in the environment surrounding the engine. For example, such gas sensors may be installed in an exhaust system of an engine test cell. This approach may be used to detect the presence of a leakage gas, but may not qualify for localizing a leak or leakage at the engine.

100051 According to another known approach, the use of camera systems is known which are suitable to visualize leakage or discharge of specific gases, e.g. on false color images. However, the installation of such camera systems are usually cost-intensive.

Summary of the invention

[0006] Starting from the prior art, it is an objective to provide an improved method for localizing leakage of a gaseous medium at an internal combustion engine In addition, it is an objective to provide a leakage detection unit of an internal combustion engine and a test bench for an internal combustion engine for carrying out such a method.

[0007] These objectives are solved by means of a method, a leakage detection unit of an internal combustion engine and a test bench for an internal combustion engine with the features of the independent claims. Preferred embodiments are set forth in the present specification, the Figures as well as the dependent claims [0008] Accordingly, a method for localizing leakage of at least one gaseous medium at an internal combustion engine is provided. The method comprises a step of emitting at least one electromagnetic radiation beam through at least one analysis section disposed at or in the vicinity of an outer surface of the engine; a step of measuring a radiation characteristic of the radiation beam after passing through the analysis section; and a step of determining a leakage of the gaseous medium into the analysis section in dependence on the measured radiation characteristic.

[0009] Furthermore, a leakage detection unit of an internal combustion engine is provided for localizing leakage of at least one gaseous medium at the engine. The leakage detection unit comprises a radiation unit configured for emitting at least one electromagnetic radiation beam through at least one analysis section disposed at or in the vicinity of an outer surface of the engine, a sensor unit configured for receiving the radiation beam after passing through the analysis section and for measuring a radiation characteristic of the received radiation beam, and a control unit configured for determining a leakage of the gaseous medium into the analysis section in dependence on the measured radiation characteristic.

100101 The proposed leakage detection unit may particularly be used for carrying out the method as described above. Accordingly, technical features which are described in connection with the proposed method in the present disclosure may also relate and be applied to the proposed leakage detection unit, and vice versa.

100111 Furthermore, a test bench for an internal combustion engine is provided having a leakage detection unit for localizing leakage of at least one gaseous medium at the engine The leakage detection unit of the test bench comprises a radiation unit configured for emitting at least one electromagnetic radiation beam through at least one analysis section disposed at or in the vicinity of an outer surface of the engine, a sensor unit configured for receiving the radiation beam after passing through the analysis section and for measuring a radiation characteristic of the received radiation beam, and a control unit configured for determining a leakage of the gaseous medium into the analysis section in dependence on the measured radiation characteristic.

100121 The test bench is equipped with a leakage detection unit which may particularly be used for carrying out the method as described above and which may correspond to the above described leakage detection unit of an internal combustion engine in terms of its structural and functional configuration. Accordingly, technical features which are described in connection with the proposed method and the proposed leakage detection unit of an internal combustion engine in the present disclosure may also relate and be applied to the proposed test bench, and vice versa.

Brief description of the drawings

[0013] The present disclosure will be more readily appreciated by reference to the following detailed description when being considered in connection with the accompanying drawings in which: [0014] Figure 1 schematically shows a top view of an internal combustion engine comprising a leakage detection unit for localizing leakage of gaseous media at the engine; [0015] Figure 2 shows a flow diagram illustrating a method performed by the leakage detection unit depicted in Fig. 1 for localizing leakage of at least one gaseous medium at an internal combustion engine; [0016] Figure 3 schematically shows a top view of an internal combustion engine comprising a leakage detection unit according to a further embodiment, [0017] Figure 4 schematically shows a top view of an internal combustion engine comprising a leakage detection unit according to a further embodiment; [0018] Figure 5 schematically shows a top view of an internal combustion engine comprising a leakage detection unit according to a further embodiment; [0019] Figure 6 schematically shows a top view of an internal combustion engine comprising a leakage detection unit according to a further embodiment, and [0020] Figure 7 schematically shows a test bench for an internal combustion engine comprising a leakage detection unit for localizing leakage of gaseous media at the engine.

Detailed description of preferred embodiments

[0021] In the following, the invention will be explained in more detail with reference to the accompanying Figures. In the Figures, like elements are denoted by identical reference numerals and repeated description thereof may be omitted in order to avoid redundancies.

[0022] Fig. 1 schematically shows an internal combustion engine 10, also referred to as the "engine" in the following, provided in the form of a reciprocating engine, in particular a stationary gas engine which is powered with an air fuel mixture of intake air and a gaseous fuel, specifically natural gas. The engine 10 comprises a plurality of cylinders (not shown), e.g. eight or twelve or sixteen cylinders, which are received in an engine block 12. In the configuration of the engine 10 described hereinafter, the cylinders are arranged according to a V-configuration, but are not limited to this structural arrangement. For example, the cylinders may also be arranged according to an in-line configuration or any other known cylinder configuration. Each cylinder is provided with a combustion chamber delimited by a piston accommodated in the cylinder. The pistons are configured for reciprocating and axial movement within the cylinders and are coupled to a crank shaft of the engine such that the reciprocating movement of the pistons is transferred into a rotating movement of the crank shaft. During operation of the engine 10, the air fuel mixture is supplied to and ignited in each cylinder so as to produce high-temperature and high-pressure gases which apply forces to and thus axially move the associated pistons, thereby rotating the crank shaft. In this way, chemical energy, at first, is transformed into mechanical energy.

[0023] For supplying intake air and the fuel medium into the combustion chambers, the engine 10 is equipped with an air fuel supply system 14, also referred to as the "supply system" in the following which is connected to the engine block 12. In the context of the present disclosure, the term "supply system" may refer to any part of the engine 10 through which fresh intake air and/or the fuel medium and/or any other medium to be supplied into the engine block 12, in particular the combustion chambers or cylinders, are/is guided.

[0024] Specifically, the supply system 14 may be provided such that fresh air from outside the engine 10 and the fuel medium are separately supplied into and thus mixed within the combustion chambers. For example, in such a configuration, fresh air may be supplied into the combustion chambers via respective intake passages which are connected to the combustion chambers via intake air valves, wherein the fuel medium may be injected into the combustion chambers by means of fuel pumps. According to another configuration, fresh air may be mixed with the fuel medium to generate the air fuel mixture before entering the combustion chambers.

[0025] For expelling combustion gases from the combustion chambers, i.e. after combustion of the air fuel mixture took place, the engine 10 further comprises an exhaust system 16 which is connected to the engine block 12. In the context of the present disclosure, the term "exhaust system" may refer to any part of the engine through which exhaust gases, in particular gases resulting from the combustion of the air fuel mixture, are guided. Specifically, for controlling the expelling of combustion gases, exhaust gas valves may be provided which variedly expel exhaust gases from the combustion chambers into exhaust passages. The exhaust system 16 may be equipped with an exhaust gas recirculation system which is configured to recirculate a portion of the engine's exhaust gas back into the cylinders, e.g. by guiding the exhaust gas into supply passages, e.g. intake air passages, of the supply system 14.

[0026] The basic structure and function of such an internal combustion engine 10 and its components are well known to a person skilled in the art and are thus not further specified. Rather, characteristics of a leakage detection unit 18 of the engine 10 interlinked with the present invention are addressed in the following. The skilled person will understand that, although not further specified in the present disclosure, the internal combustion engine 10 may be equipped with further components, such as a particulate filter, etc. [0027] The leakage detection unit 18 of the engine 10 is configured for detecting and localizing leakage of different gaseous media at the engine 10.

[0028] In the context of the present disclosure, the term "leakage" refers to an unintended discharge of a gaseous medium from the engine 10, in particular a part thereof, into its surrounding environment. In general, leakage may be caused by any unintended breakthrough or opening, also referred to as a leak or crack, provided in an outer surface or shell of the engine 10 which delimit an inside of the engine 10 from its surrounding or ambient environment. Typically, such unintended openings may result from material fatigue, material defects or assembly errors. During operation, these unintended openings may allow gaseous medium to flow from the inside of the engine 10 into its surrounding. In other words, during operation of the engine 10, the gaseous medium is guided from the inside of the engine 10 into its surrounding through the unintended opening. Specifically, the discharge of the gaseous medium may be effected by a pressure difference prevailing across the unintended opening, i.e. a pressure difference occurring between the pressure prevailing in the inside of the engine 10 and the ambient pressure prevailing in its surrounding.

100291 Further, the term "gaseous medium" refers to a medium, matter or substance which, in a considered condition, is in the gaseous state. For example, in particular in view of the described embodiments, the term "gaseous medium" may refer to at least one of a gaseous fuel medium, such as gaseous alkane, in particular methane, and a gaseous exhaust medium, such as gaseous oxocarbon, in particular carbon dioxide and/or carbon monoxide, but is not limited thereto.

100301 In the shown configuration, the leakage detection unit 18 comprises two detection sets, particularly a first detection set 20a and a second detection set 20b, each of which is intended and configured to detect at least one specific gaseous medium.

100311 More specifically, the first detection set 20a is provided to detect a leakage of a gaseous fuel medium, such as gaseous alkane, in particular methane. Accordingly, as can be gathered from Fig. 1, the first detection set 20a is implemented to monitor the supply system 14, i.e. to detect leakage of the gaseous fuel medium in the area of the supply system 14. According to a further configuration, the first detection set 20a may not be limited to monitor the supply system 14, but rather may be configured to monitor any portion of the engine 10 in which gaseous fuel medium flows. Thus, alternatively or additionally first detection set 20a may be configured to monitor the engine block 12, specifically a cylinder head thereof For example, the first detection set 20a may be configured to monitor a space between two cylinder lines of the V-configuration of the engine block 12.

100321 Further, the second detection set 20b is provided to detect a leakage of a gaseous exhaust medium, such as gaseous oxocarbon, in particular carbon dioxide and/or carbon monoxide. Accordingly, as can be gathered from Fig. 1, the second detection set 20b is implemented to monitor the exhaust system 16 of the engine 10, i.e. to detect leakage of the gaseous exhaust medium in the area of the exhaust system 16. According to a further configuration, the second detection set 20b may not be limited to monitor the exhaust system 16, but rather may be configured to further monitor any portion of the engine 10 in which gaseous exhaust medium may flow, such as the engine block 12. Thus, additionally or alternatively, the second detection set 20b may not be limited to monitor the exhaust system 16 may be configured to monitor an exhaust gas recirculation system in case the engine 12 is provided with such. Further, the second detection set 20b may be configured to monitor a space between cylinder lines of the V-configuration of the engine block 12.

[0033] In the shown configuration, each detection set 20a,b is built up from corresponding components or type of components, the structural and functional configuration of which may differ among the different detection sets. Thus, for avoiding a repeated description, like elements are indicated by identical reference numerals, while the character "a" identifies those elements associated to the first detection set 20a and the character -b" identifies those elements associated to the second detection set 20b.

[0034] In the following, the detection set 20 is generically specified, the description of which applies to both the first detection set 20a and the second detection set 20b, respectively.

[0035] Each detection set 20 comprises a radiation unit 22 having at least one radiation source 24 configured for emitting at least one electromagnetic radiation beam 26. The radiation beam 26 emitted by the radiation unit 22 is guided through at least one analysis section 28 disposed at or in the vicinity of an outer surface of the engine 10. For doing so, the radiation unit 22 may comprise at least one deflection element, in particular an optical deflection element, such as a mirror.

[0036] In the context of the present disclosure, the term "analysis section" refers to a section or space through which the radiation beam 26 is guided. More specifically, the analysis section 28 is disposed outside from an interior of the engine through which operating fluids and gases are guided. Further, the analysis section 28 is disposed adjacent to or in the region or vicinity of the outer surface or shell of the engine 10 which delimit an inside of the engine 10 from its surrounding or ambient environment. In general, any distance between the analysis section 28 and the outer surface or shell of the engine 10 may be set which allows for reasonably detecting leakage. For example, a distance, in particular a minimal distance, between the analysis section 28 and the outer surface or shell of the engine 10 may be in the range between 0 cm to 30 cm, in particular between 0 cm to 5 cm or 10 cm. In the shown configuration, a plurality of analysis sections 28a is disposed at or in the vicinity of the supply system 14 and a plurality of analysis sections 28b is disposed at or in the vicinity of the exhaust system 16.

[0037] The at least one radiation source 24 is provided in the form of a laser, specifically a diode laser. In this way, the radiation source 24 is configured to generate a radiation beam 26 in the form of a laser beam which may have a narrow spectrum and may be relatively focused, thereby allowing for an accurate analysis and detection of leakage phenomena at the engine 10.

[0038] The detection set 20 further comprises a sensor unit 30 having at least one sensor element 32 which is intended and configured for receiving the at least one radiation beam 26 after passing through the analysis section 28 For doing so, the sensor unit 30 may comprise at least one deflection element, in particular an optical deflection element, such as a mirror, for guiding the radiation beam 26 towards the sensor element 32. Specifically, the at least one sensor element 32 is configured for measuring a radiation characteristic of the received radiation beam 26. For doing so, the sensor element 32 is provided in the form of an optical detector, in particular an electro-optical detector, which is configured to measure the intensity of the received radiation beam 26. According to one configuration, the sensor element 32 may be configured to measure the intensity of an incoming radiation beam 26 at different frequencies within a frequency range. In other words, the sensor element 32 may be provided in the form of an optical spectrum analyzer. Specifically, the optical spectrum analyzer may be configured to use reflective or reflective techniques to separate out different wavelength ranges of light, the intensity of which is then measured by an electro-optical detector. In this way, spectral intensity of the light, i.e. a frequency-dependent intensity of the light, may be determined.

[0039] The radiation unit 22 and the sensor unit 30 are communicatively connected to a control unit 34 of the leakage detection unit 18 as can be gathered by dashed lines in Fig. 1. This communicative connection may be implemented as a wired connection or wirelessly. By such a configuration, an exchange of information, in particular of control signals and measurement data, is enabled between the control unit 34, the radiation unit 22 and the sensor unit 30. Specifically, the control unit 34 is configured to transmit control signals to the radiation unit 22 and the sensor unit 30 so as to control operation thereof. Further, the sensor unit 30 is configured to transmit measurement data to the control unit 34 being indicative of the measured radiation characteristic.

[0040] The control unit 34 is configured for determining a leakage of the specific gaseous medium in one of the at least one analysis section 28 in dependence on the radiation characteristic measured by the sensor unit 30. In other words, based on the measurement data received by the sensor unit 30, the control unit 34 is configured to determine and localized a leakage of the gaseous medium at the engine 10. Specifically, the control unit 34 is of an electronic control unit type and is configured to read out measurement data from the sensor unit 30, i.e. the measured radiation characteristic, and to process and interpret the thus obtained measurement data in order to determine and localized leakage of gaseous media at the engine 10 100411 The control unit 34 may be a part of an engine control unit of the engine 10, which may also be referred to as "engine control module' and which may be configured to control and monitor operation of the engine 10. Alternatively, the control unit 34 may be provided separately, in particular functionally and/or physically separately from the engine control unit. In the shown configuration, the different detection sets 20 are connected to and communicate with the same control unit 34. In this way, a modular design of the leakage detection unit 18 may be provided allowing that an arbitrary number of interchangeable different detection sets may be connected to the same control unit 34. According to an alternative configuration, each detection set 20 may be provided with its own control unit 34, thereby constituting a leakage detection unit 18, respectively. Accordingly, the engine 10 may be provided with more than one leakage detection unit IS, which may be provided functionally and/or physically separated from one another.

100421 In the following, the method and principles underlying the proposed leakage detection unit 18 of the engine 10 are described which allow for effectively and efficiently detecting and localizing leakage at the engine 10.

[0043] In the context of the proposed solution, it has been found to make use of matter-specific absorption characteristic of atoms and molecules for detecting and localizing leakage at an engine. In general, the suggested approach is based on the physical effect that each substance has its unique radiation absorption spectrum defined by its structure and composition. That is, upon radiating a sample with light, the sample absorbs a part of the light having a wavelength that corresponds to an absorption wavelength that is unique or specific to the sample's molecules and atoms. This effect is also used in known absorption spectroscopy approaches.

[0044] For illustrating how this effect is applied for detecting and localizing leakage at the engine 10, a method carried out by the proposed leakage detection unit 18 of the engine 10 is described in the following under reference to Fig. 2 illustrating a corresponding flow diagram of the method.

[0045] In a first step Si, at least one analysis section 28 is defined which is disposed and associated to a region and location of the engine 10 to be monitored for leakage. In other words, during operation of the leakage detection unit 18, the at least one analysis section 28 is monitored in order to detect whether leakage of a monitored gaseous medium occurs in one of the analysis sections 28 or not. When the presence of the gaseous medium in one analysis section 28 is detected, the presence of a leakage of the gaseous medium in this analysis section 28 is determined. By identifying those analysis sections 28 in which the gas is present and thus the leakage occurs, the leakage of the gaseous medium is localized since each one of the analysis sections 28 is directly associated to a region or location at the engine 10.

100461 For properly monitoring an area of the engine 10, preferably, more than one analysis sections 28 are defined, in particular per detection set 20 For doing so, the analysis sections 28 may be provided to form a dense mesh for properly covering the area of the engine 10 to be monitored. Specifically, a plurality of analysis sections 28 may be defined such that a distance, in particular a minimal distance, between adjacent analysis sections lies within a range of 1 cm to 20 cm, in particular between 5 cm to 10 cm. The different analysis sections 28 may extend parallel to one another. That is, a direction along which the radiation beam 26 protrudes through its associated analysis section 28 may extend in parallel among adjacent analysis sections 28. An example of such a parallel arrangement of analysis sections 28 of a detection set 20 is provided by the configuration of the leakage detection unit 18 depicted in Fig. 1. For illustrative purposes, each one of the detection set 20 depicted in Fig. 1 comprises three parallel analysis sections 28, wherein a distance between adjacent analysis sections 28 is within a range between 5 cm to 10 cm. However, it is apparent to a skilled person that the depicted detection set 20 may comprise any suitable number of analysis sections 28 which may be arranged in an arbitrary arrangement relative to one another so as to allow for a proper leakage monitoring and localization. To that end, the leakage detection unit 18 may comprise a plurality of analysis sections 28 which extend inclined relative to one another. Specifically, such analysis sections 28 may cross each other, i.e. may partially overlap, or may be spaced apart from one another, thereby forming a mesh, i.e. a dense mesh, of analysis sections 28 which allows for accurately monitoring and localizing leakages. Such an arrangement of analysis sections 28 is implemented in the configuration depicted in Fig. 3.

10047] In Fig. 3, the component denoted by reference "36" refers to an arbitrary area of the engine 10 to be monitored by the leakage detection unit 18, i.e. the detection set 20. The area 36 of the engine 10 may refer to any part or subsystem of the engine 10, such as the engine block 12, the supply system 14 and the exhaust system 16. Alternatively, the area 36 may be constituted by more than one part or subsystem of the engine 10, i.e. by more than one of the engine block 12, the supply system 14 and the exhaust system 16.

100481 Step S1 of defining the different analysis sections 28 may be performed upon installing the detection set 20, i.e. the radiation unit 22 and the sensor unit 30, according to a desired arrangement at the engine 10. By doing so, also the beam path of the at least one radiation beam 26 to be emitted by the radiation source 24 of the radiation unit 22 and to be received by the sensor element 32 of the sensor unit 30 is set since the analysis section 28 refers to a section through which the radiation beam 26 is guided.

10049] After defining the different analysis sections 28, the method proceeds to step S2 in which at least one radiation beam 26 is emitted through at least one associated analysis section 28. This step is performed by the radiation unit 22, i.e. its radiation sources 24. In case a plurality of different radiation beams 26 are emitted, this step may be performed such that at least a part of the radiation beams is simultaneously emitted, i.e. at the same time, or subsequently, i.e one after the other.

100501 Further, the at least one radiation beam 26 is generated such that it has a radiation wavelength which corresponds, in particular substantially corresponds, to an absorption wavelength of the gaseous medium the leakage or presence of which within the at least one analysis section 28 is to be determined. In this way, the radiation beam 26 is adapted to the gaseous medium to be detected, thereby ensuring that an intended absorption occurs when the radiation beam 26 is guided through the gaseous medium to be detected.

100511 For providing a detection set 20 with a certain degree of configurability and flexibility, the at least one radiation source 24 of the radiation unit 22 may be provided in the form of a tunable diode laser configured for selectively emitting radiation beams 26 of an adjustable wavelength range, in particular narrow wavelength range. In this way, the detection set 20 may be suitable to detect different gaseous media by selectively adapting the wavelength of the radiation beam 26 to an absorption wavelength of a gaseous medium to be detected 100521 In the configuration depicted in Fig. 1, the radiation unit 22 is configured to emit or radiate a plurality of radiation beams 26, each of which is associated to a different radiation path and to a different analysis section 28. In other words, step S2 is performed such that a plurality of analysis sections 28 is radiated, wherein each one of the analysis sections 28 is radiated by an associated radiation beam 26 which differs among the plurality of analysis sections 28.

100531 For doing so, the radiation unit 22 comprises a plurality of radiation sources 24, each of which is associated to one analysis section 28 as shown in the configuration depicted in Figs. 1 and 3. Accordingly, the sensor unit 30 comprises a corresponding number of sensor elements 32, each of which is associated to one analysis section 28. In other words, in the configuration depicted in Fig. 1, a one-to-one relation is provided between the analysis section 28 on the one hand and the radiation sources 24 and sensor element 32 on the other, respectively.

100541 In a next step 53, after the at least one radiation beam 26 is guided through its associated analysis section 28, the radiation characteristic of the radiation beam 26 is measured, i.e. after passing through the analysis section 28. This step is performed by the sensor unit 30, i.e. its sensor elements 32. Specifically, the sensor unit 30 is provided such that the measured radiation characteristic is indicative of an absorption the radiation beam 26 is subjected to upon being guided through the analysis section 28. This absorption is effected due to an intersection with the gaseous medium to be detected. More specifically, the measured radiation characteristic is indicative of an intensity of the radiation beam 26 at a frequency or in a frequency range which substantially corresponds to the absorption frequency or frequency range of the gaseous medium the presence of which within the analysis section 28 is to be determined.

100551 Further, the sensor unit 30 is configured to measure for each analysis section 28 the radiation characteristic which is transmitted to the control unit 34. Specifically, the sensor unit 30 may transmit the radiation characteristic in a data format or in the way which allows the control unit 34 to associate the thus received measured radiation characteristics to its corresponding analysis section 28. In this way, upon receiving the measured data from the sensor unit 30, the control unit 34 is enabled and configured to associate the measured radiation characteristic to its corresponding analysis section 28 so as to enable to detect and localize the occurrence of a leakage of the gaseous medium at the engine 10.

100561 In a next step S4, a leakage of the gaseous medium into the at least one analysis section 28 is determined in dependence on the measured at least one radiation characteristic. This step is performed by means of the control unit 34 which receives the measured radiation characteristics from the sensor unit 30. Specifically, the control unit 34 is configured to determine for each analysis section 28 whether the associated measured radiation characteristic indicates that the associated radiation beam 26 has met or hit the gaseous medium to be detected when being guided through the associated analysis section 28. For doing so, the control unit 34 analyzes the measured radiation characteristic, i.e. the measured intensity, of the radiation beam 26. That is, when the measured radiation characteristic indicates that the intensity of the radiation beam 26 is subjected to a drop, the control unit 34 determines that the analysis section 28 associated to the analyzed radiation characteristic is subjected to a leakage of the gaseous medium. In other words, for determining a leakage of the gaseous medium, the control unit 34 compares the measured radiation characteristic with a threshold. Specifically, when the control unit 34 detects that the measured radiation characteristic has reached the threshold, it detects that the intensity of the radiation beam 26 has been substantially attenuated upon irradiating through the associated analysis section 28, thereby determining the presence of the gaseous medium to be measured within the analysis section 28 [0057] For further localizing the appearance of the leakage, the control unit 34 may be configured to analyze the measured radiation characteristics associated to different analysis sections 28, in particular to adjacent and/or crossing analysis sections 28 In this way, the control unit 34 may be configured to narrow down the location or potential location of the leakage. For example, if the measured radiation characteristics associated to two analysis sections 28 which intersect each other or are provided next to each other indicate the occurrence of a leakage, respectively, the control unit 34 may localize leakage in an area or spot at which the two analysis sections 28 intersect or in an area which lies between the two analysis sections 28.

[0058] As set forth above, the leakage detection unit 18 of the engine 10 is provided with the first detection set 20a which is configured to detect a first type of gaseous medium, i.e. the gaseous fuel medium, and with the second detection set 20b which is configured to detect a second type of gaseous medium, i.e. the gaseous exhaust medium. For doing so, the first detection set 20a is provided to emit first radiation beams 26a having a first wavelength which are emitted through first analysis sections 28a and the second detection set 20b is provided to emit second radiation beams 26b having a second wavelength which are emitted through second analysis sections 28b. The first analysis sections 28a are provided at or in the vicinity of the supply system 14, wherein the second analysis sections 28a are provided at or in the vicinity of the exhaust system 16. In other words, the first analysis sections 28a are provided spaced apart from the second analysis sections 28b.

100591 The first wavelength of the first radiation beams 26a is adapted to correspond to or substantially correspond to the absorption wavelength of the gaseous fuel medium, in particular methane, to be detected by the first detection set 20a. The second wavelength of the second radiation beams 26b differs from the first wavelength and is adapted to correspond or substantially correspond to the absorption wavelength of the gaseous exhaust medium, in particular carbon dioxide and/or carbon monoxide, to be detected by the second detection set 20b. By such an arrangement, the different detection sets 20 may be used to selectively and effectively detect different types of gaseous medium.

100601 Fig. 4 shows another configuration of the leakage detection unit 18 in which, compared to the embodiments depicted in Fig. I and 3, the number of radiation sources 24 is lower compared to the number of analysis sections 28. Specifically, in the shown configuration, the leakage detection unit 18 manages to perform the method of detecting and localizing leakage by means of one single radiation source 24. That is, the leakage detection unit 20 enables for generating the plurality of radiation beams 26 to be guided through different analysis sections 28 by the use of one single radiation source 24 per detection set 20. For doing so, the radiation unit 22 further comprises a beam manipulation unit 38 through which the radiation beam 26 generated by the single radiation source 24 is guided before being directed into the respective analysis sections 28. Specifically, in the shown configuration, the beam manipulation unit 38 is provided in the form of an optical beam splitter and deflector. As such, the manipulation unit 38 is configured to, by means of its optical splitter, split the receiving radiation beam from the radiation source 24 into a number of separate and individual radiation beams 26, each of which is associated to one analysis section 28. Then, each one of the spitted radiation beams 26 is deflected towards its associated analysis section 28.

100611 Fig. 5 shows another configuration of the leakage detection unit 18 in which, compared to the embodiment depicted in Fig. 4, the number of sensor elements 32 is lower compared to the number of analysis sections 28.

Specifically, in the shown configuration, the leakage detection unit 18 manages to perform the method of detecting and localizing leakage by means of one single sensor element 32. For doing so, the leakage detection unit 18 is operated such that the sensor unit 30, in particular its sensor element 32, receives different radiation beams 26 separately at successive time sequences, wherein the different radiation beams differ from one another by the analysis section 28 they are guided through. For doing so, the radiation unit 22, in particular its beam manipulation unit 38 may comprise an optical splitter and a shutter element which time-sequentially and selectively blocks emission of the splitted, individual radiation beams 26, respectively. Alternatively, the beam manipulation unit 38 may comprise an adjustable optical deflector which guides the radiation beam 26 successively through the different analysis sections 28.

[0062] After being guided through the analysis sections 28, the radiation beams 26 are guided into a deflection unit 40 of the sensor unit 30 which deflects each one of the radiation beams 26 towards the single sensor element 32. Alternatively or additionally, the deflection unit 40 may comprise a shutter element and or an adjustable optical deflector for selectively guiding the incoming radiation beams 26 successively towards the single sensor unit 32.

[0063] In the configuration depicted in Fig. 5, for allowing proper analysis of the measured radiation characteristics, the control unit 34 is configured to associate each one of the successive time sequences, during which individual analysis sections 28 are separately radiated by the radiation beam 26, to one analysis section 28. By doing so, the control unit 34 knows which one of the plurality of analysis sections 28 is irradiated by the radiation beam 26 at which time sequence. During each time sequence, the sensor unit 30 measures the radiation characteristic of the incoming radiation beam 26. Then, the control unit 34 determines for each time sequence the occurrence of a leakage of the gaseous medium within the associated analysis section 28 in dependence on the measured radiation characteristic during this time sequence. This approach may also be referred to as a time-division multiplexing approach since the sensor unit 30 receives independent signals at a single sensor element 32, wherein the different signals are associated to different time sequences in an alternating time pattern. In this way, different signals can be transmitted on a common signal path.

100641 Fig. 6 shows another configuration of the leakage detection unit 18 which is configured to change a radiation path of the radiation beam so as to adapt or displace the analysis section 28, in particular relative to the engine 10. In this way, the leakage detection unit 18 enables to irradiate a plurality of different analysis sections 28. For doing so, the leakage detection unit 18 is provided with a radiation unit 22 which is configured for displacing the radiation source 24 relative to the engine 10 as indicated by arrow A in Fig 6 Further, the leakage detection unit 18 is provided with a sensor unit 30 which is configured for displacing the sensor element 32 in accordance to the movement of the radiation source 24 of the radiation unit 22 as indicated by arrow A in Fig. 6. In this way, it may be ensured that, even though the radiation path of the radiation beam 26 is displaced, the radiation beam 26 is received and measured by the sensor unit 30. Alternatively or additionally, the radiation unit 22 may be provided with a deflecting unit for changing, displacing or adapting the radiation path of the radiation beam 26. By such a configuration, the radiation path and thus the analysis section 28 associated thereto may be successively changed so as to detect leakage of the gaseous medium at different locations at the engine 10, thereby enabling to accurately localize a leakage.

100651 According to a further development, for attenuating or filtering disturbing signals in the signal measured by the sensor unit 30, the leakage detection unit 18 may be equipped with a lock-in amplifier. Such disturbing signals may originate from light emissions present in the surrounding of the engine 10. Specifically, for implementing such a lock-in amplifier, the radiation unit 22 of the previously described configurations of the leakage detection unit 18 may be configured to modulate the at least one radiation beam 26 generated by the at least one radiation source 24 in terms of frequency and phase based on a reference signal having a predetermined frequency and phase. For doing so, the radiation unit 22 may guide the radiation beam 26 through, e.g., a shutter element, in particular a chopper wheel, which is configured to modulate the radiation beam 26 in dependence on the reference signal. The chopper wheel is provided with openings through which the radiation beam can be guided and rotated in dependence on the reference signal, thereby modulating the radiation beam in terms of frequency and phase. The thus generated radiation beam 26 is guided through the at least one analysis section 28 before it is received and processed by the sensor unit 30. Specifically, the sensor unit 30 is configured to process the received radiation beam 26 as a function of the reference signal which is used to modulate the radiation beam 26 By processing the received radiation beam based on the reference signal, a narrow-band filtering may be performed which allows for effectively attenuate disturbing signals from the engine's surrounding, for example by ambient light. In this way, a processed radiation beam signal is generated based on which the radiation characteristic of the radiation beam is determined.

[0066] Fig. 7 shows a test bench 42 for an internal combustion engine 10. For example, such a test bench 42 may be used during manufacturing of engines 10. As such, the test bench 42 is configured to perform test procedures at different engines 10 which can be interchangeable received therein.

100671 The test bench is equipped with a leakage detection unit 18 as described above. Thus, the leakage detection unit 18 forms a part of the test bench 42 compared to the previously described configurations in which it is a part of the internal combustion engine 10.

[0068] It will be obvious for a person skilled in the art that these embodiments and items only depict examples of a plurality of possibilities.

Hence, the embodiments shown here should not be understood to form a limitation of these features and configurations. Any possible combination and configuration of the described features can be chosen according to the scope of the invention. This is particularly the case with respect to the following optional features which may be combined with some or all embodiments, items and/or features mentioned before in any technically feasible combination.

[0069] As set forth above, a method for localizing leakage of at least one gaseous medium at an internal combustion engine is provided.

[0070] Compared to known approaches, the proposed method enables to automatically identify, i.e. without excessive manual work, a location at the engine, i.e. an analysis section, at which a leakage occurs. In this way, a method for localizing leakage of at least one gaseous medium is provided which can be performed time and cost efficiently.

[0071] The proposed method may be employed for localizing leakage at any suitable internal combustion engines, such as reciprocating engines, in particular stationary gas engines, specifically large stationary gas engines. For example, such internal combustion engines may be utilized or be installed in vehicles, such as vessels, or power plants, i.e. as main or auxiliary engines.

[0072] According to one configuration, the method may be provided such that the at least one gaseous medium is at least one of a gaseous alkane, in particular methane, and a gaseous oxocarbon, in particular carbon dioxide and carbon monoxide.

[0073] The at least one analysis section may be disposed at or in the vicinity of at least one of an air fuel supply system, an exhaust system and a cylinder head portion of the engine.

[0074] Specifically, the radiation beam may have a radiation wavelength which substantially corresponds to an absorption wavelength of the gaseous medium the leakage or presence of which within the analysis section is to be determined. To this end, the step of measuring a radiation characteristic of the radiation beam after passing through the analysis section may be performed such that the radiation characteristic may be indicative of an absorption the radiation beam is subjected to due to an interaction with the gaseous medium upon being guided through the analysis section. Specifically, according to one configuration, the radiation characteristic may be indicative of an intensity of the radiation beam at a frequency or in a frequency range which substantially corresponds to an absorption frequency or absorption frequency range of the gaseous medium the presence of which within the analysis section is to be determined.

100751 In a further development, the step of emitting the at least one electromagnetic radiation beam is performed by means of at least one or by means of one diode laser, in particular a tunable diode laser. By virtue of the tunable diode laser, the leakage detection unit may be adapted for detecting different gaseous media in a cost and time efficient manner. Alternatively or additionally, the step of emitting at least one radiation beam may be performed such that a plurality of analysis sections is radiated. Optionally, each one of the analysis sections may be radiated by an associated radiation beam which differs among the plurality of analysis sections. In other words, by doing so, a one-to-one relation between analysis sections and radiation beams, respectively, may be provided. Alternatively or additionally, a distance, in particular a minimal distance, between adjacent analysis sections, in particular adjacent parallel analysis sections, may be within a range of 1 cm to 20 cm, in particular between 5 cm to 10 cm.

[0076] In a further development, the step of emitting at least one electromagnetic radiation beam may be performed such that at least one first radiation beam having a first wavelength is emitted through at least one first analysis section and at least one second radiation beam having a second wavelength is emitted through at least one second analysis section. Additionally, the first and the second wavelength may differ from one another. Optionally, the first and the second analysis section may be spaced apart from one another.

[0077] The first analysis section may be arranged at or in the vicinity of an air filet supply system of the engine. Optionally, the first wavelength may correspond to an absorption wavelength of methane. Alternatively or additionally, the second analysis section may be arranged at or in the vicinity of an exhaust system of the engine. Optionally, the second wavelength may correspond to an absorption wavelength of at least one of carbon dioxide and carbon monoxide.

[0078] In a further development, the step of emitting at least one electromagnetic radiation beam may be performed such that a sensor unit receives different radiation beams separately at successive time sequences. In the context of the present disclosure, a radiation beam is characterized by its radiation path. Thus, radiation beams are described as different in the present disclosure if at least a part of their radiation path differs from one another. Additionally, the different radiation beams may differ from one another by the analysis section they are guided through. Further, the method may comprise a step of associating each one of the successive time sequences to at least one analysis section; and/or a step of measuring, during each time sequence, a radiation characteristic of the radiation beam received by the sensor unit; and/or a step of determining for each time sequence the occurrence of a leakage of the gaseous medium within the associated analysis section in dependence on the measured radiation characteristic.

[0079] Alternatively or additionally, the method may comprise a step of changing radiation path of the radiation beam so as to displace the analysis section relative to the engine. Specifically, for doing so, the radiation path may be translationally or rotationally displaced. More specifically, this may be performed by deflecting the radiation beam by means of at least one deflecting unit or by displacing a radiation source emitting the radiation beam.

[0080] According to a further development, the method may further comprise a step of modulating the radiation beam in terms of frequency and phase based on a reference signal; and/or a step of receiving the radiation beam after passing through the analysis section; and/or a step of processing the received radiation beam as a function of the reference signal to generate a processed radiation beam signal; and/or a step of determining the radiation characteristic of the processed radiation beam signal.

10081] Furthermore, a leakage detection unit of an internal combustion engine and a test bench being equipped with such a leakage detection unit are provided as set forth above.

Industrial applicability

10082] With reference to the Figures and their accompanying description, a method for detecting leakage of the gaseous medium at an internal combustion engine is suggested. Further, a leakage detection unit of an internal combustion engine and a test bench being equipped with a leakage detection unit for carrying out the method are proposed. The method and the leakage detection unit as mentioned above are applicable in internal combustion engines, for example provided as a stationary gas engine. The suggested method may replace conventional leakage detection methods. Accordingly, the suggested leakage detection unit may replace conventional leakage detection devices and may serve as a replacement or retrofit part.

List of reference numerals internal combustion engine 12 engine block 14 air fuel supply system 16 exhaust system 18 leakage detection unit detection set 22 radiation unit 24 radiation source 26 radiation beam 28 analysis section sensor unit 32 sensor element 34 control unit 36 area to be monitored 38 beam manipulation unit deflection unit 42 test bench

Claims (15)

1. Claims What is claimed is: A method for localizing leakage of at least one gaseous medium at an internal combustion engine (10), comprising: - a step (S2) of emitting at least one electromagnetic radiation beam (26) through at least one analysis section (28) disposed at or in the vicinity of an outer surface of the engine (10); - a step (S3) of measuring a radiation characteristic of the radiation beam (26) after passing through the analysis section (28); and - a step (S4) of determining a leakage of the gaseous medium into the analysis section (28) in dependence on the measured radiation characteristic.
2. 2. Method according to claim 1, wherein the at least one gaseous medium the leakage of which is to be determined is at least one of a gaseous alkane, in particular methane, and a gaseous oxocarbon, in particular carbon dioxide and carbon monoxide.
3. 3. Method according to claim 1 or 2, wherein the at least one analysis section (28) is disposed at or in the vicinity of at least one of an air fuel supply system (14), an exhaust system (16) and a cylinder head portion of the engine (10).
4. 4. Method according to any one of claims 1 to 3, wherein the radiation beam (26) has a radiation wavelength which substantially corresponds to an absorption wavelength of the gaseous medium the leakage of which within the analysis section (28) is to be determined.
5. 5. Method according to any one of claims Ito 4, wherein the radiation characteristic is indicative of an absorption the radiation beam (26) is subjected to due to an interaction with the gaseous medium upon being guided through the analysis section (28).
6. 6. Method according to any one of claims Ito 5, wherein the radiation characteristic is indicative of an intensity of the radiation beam (26) at a frequency or in a frequency range which substantially corresponds to an absorption frequency or frequency range of the gaseous medium the presence of which within the analysis section (28) is to be determined.
7. 7 Method according to any one of claims Ito 6, wherein the step (S2) of emitting the at least one electromagnetic radiation beam (26) is performed by means of a diode laser or a tunable diode laser.
8. 8. Method according to any one of claims 1 to 7, in which the step (S2) of emitting the at least one radiation beam (26) is performed such that a plurality of analysis sections (28) is radiated, wherein a distance between adjacent analysis sections (28) lies within a range of 1 cm to 20 cm, in particular between 5 cm to 10 cm, and wherein each one of the analysis sections (28) is radiated by an associated radiation beam (26) which differs among the plurality of analysis sections (28).
9. 9 Method according to any one of claims Ito 8, wherein the step (S2) of emitting at least one electromagnetic radiation beam (26) is performed such that at least one first radiation beam (26a) having a first wavelength is emitted through at least one first analysis section (28a) and at least one second radiation beam (26b) having a second wavelength is emitted through at least one second analysis section (28b), wherein the first and the second wavelength differ from one another, and wherein the first and the second analysis section (28a, 28b) are spaced apart from one another.
10. 10. Method according to claim 9, wherein the first analysis section (28a) is arranged at or in the vicinity of an air fuel supply system (14) of the engine (10) and the first wavelength corresponds to an absorption wavelength of methane, and wherein the second analysis section (28b) is arranged at or in the vicinity of an exhaust system (16) of the engine (10) and the second wavelength corresponds to an absorption wavelength of at least one of carbon dioxide and carbon monoxide.
11. 11 Method according to any one of claims 1 to 10, in which the step (S2) of emitting at least one electromagnetic radiation beam (26) is performed such that a sensor unit (30) receives different radiation beams (26) separately at successive time sequences, wherein the different radiation beams (26) differ from one another by the analysis section (28) they are guided through, and wherein the method further comprises the steps of - associating each one of the successive time sequences to at least one analysis section (28); - measuring, during each time sequence, a radiation characteristic of the radiation beam (26) received by the sensor unit (30); and - determining for each time sequence the occurrence of a leakage of the gaseous medium within the associated analysis section (28) in dependence on the measured radiation characteristic
12. 12. Method according to any one of claims Ito 11, further comprising a step of changing a radiation path of the radiation beam (26) so as to displace the analysis section (28) relative to the engine (10).
13. 13. Method according to any one of claims Ito 12, further comprising the steps of: - modulating the radiation beam (26) in terms of frequency and phase based on a reference signal; - receiving the radiation beam (26) after passing through the analysis section (28); - processing the received radiation beam (26) as a function of the reference signal to generate a processed radiation beam signal; and - determining the radiation characteristic of the processed radiation beam signal.
14. 14. Leakage detection unit (18) of an internal combustion engine (10) for localizing leakage of at least one gaseous medium at the engine (10) which comprises: - a radiation unit (22) configured for emitting at least one electromagnetic radiation beam (26) through at least one analysis section (28) disposed at or in the vicinity of an outer surface of the engine (10), - a sensor unit (30) configured for receiving the radiation beam (26) after passing through the analysis section (28) and for measuring a radiation characteristic of the received radiation beam (26), and - a control unit (34) configured for determining a leakage of the gaseous medium into the analysis section (28) in dependence on the measured radiation characteristic.
15. 15. Test bench (42) for an internal combustion engine (10) having a leakage detection unit (18) for localizing leakage of at least one gaseous medium at the engine (10) which comprises: - a radiation unit (22) configured for emitting at least one electromagnetic radiation beam (26) through at least one analysis section (28) disposed at or in the vicinity of an outer surface of the engine (10), - a sensor unit (30) configured for receiving the radiation beam (26) after passing through the analysis section (28) and for measuring a radiation characteristic of the received radiation beam (26), and - a control unit (34) configured for determining a leakage of the gaseous medium into the analysis section (28) in dependence on the measured radiation characteristic.