Gap position measuring device

Abstract

To provide a gap position measuring device for internal combustion engines. [Solution] A gap position measuring device for an internal combustion engine comprises at least one cylinder having a liner wall and a reciprocating piston having at least one first piston ring having a piston ring gap. The gap position measuring device comprises a first set of sensors having three temperature sensors adapted to be positioned on or within the liner wall, spaced circumferentially apart in a first axial plane. Furthermore, the gap position measuring device comprises a signal analysis unit, which is further adapted to receive temperature data from the first set of sensors and determine the angular position of the piston ring gap relative to the cylinder based on the received temperature data.

Description

TECHNICAL FIELD

[0001] The present invention relates to a gap position measuring device for piston rings of a reciprocating internal combustion engine, a reciprocating internal combustion engine having such a gap position measuring device, a method for measuring the gap position of a piston ring of an internal combustion engine, and a computer program.

[0002] The present invention preferably relates to a reciprocating internal combustion engine, such as a large marine or ship engine, or a stationary engine, having a cylinder with an inner diameter of at least 200 mm. The engine is preferably a two-stroke engine or a two-stroke crosshead engine. The engine can be a diesel engine or a gas engine, and can be a dual-fuel engine or a multi-fuel engine. Combustion of liquid and / or gaseous fuel is possible within such an engine, and self-ignition or forced ignition is also possible.

BACKGROUND ART

[0003] The internal combustion engine may be a uniflow scavenged two-stroke engine.

[0004] The term internal combustion engine also refers not only to diesel cycles characterized by self-ignition of fuel, but also to Otto cycles characterized by positive ignition of fuel, or large engines that can operate with a mixture of the two. Furthermore, the term internal combustion engine particularly includes dual-fuel engines and large engines where self-ignition of one fuel is used for positive ignition of another fuel.

[0005] The engine speed is preferably 800 RPM or less, particularly for four-stroke engines, more preferably 200 RPM or less, particularly for two-stroke engines, which indicates the specified value for low-speed engines.

[0006] The fuel can be diesel oil or marine diesel oil or heavy oil or emulsion or slurry or methanol or ethanol, as well as gases such as liquefied natural gas (LNG), liquefied petroleum gas (LPG) and the like.

[0007] Further possible fuels that may be added upon request include LBG (liquefied biogas), biofuels (e.g., oils made from algae or seaweed), ammonia, hydrogen, and synthetic fuels from CO2 (e.g., produced by power-to-gas or power-to-liquid).

[0008] Large vessels, especially those used for transporting goods, are typically powered by internal combustion engines, particularly diesel and / or gas engines, often two-stroke cross-head engines.

[0009] In reciprocating piston internal combustion engines, particularly those of the dual-fuel or Otto cycle type, the piston is provided with piston rings that form a piston ring package. These piston rings seat in grooves within the piston and serve to seal the combustion chamber from the outside.

[0010] A piston ring may have a ring body with a gap between its ends, or a ring body with two overlapping ends that form a piston ring lock. However, within the region of the piston ring lock, the ring is not completely closed, and the pressure in the cylinder can force hot gases through to the piston ring lock. Therefore, even if there is no actual gap between the ends of the ring body, the piston ring lock is also referred to as the piston ring gap.

[0011] The position of the piston ring gap, the rotational motion of the piston rings, and consequently the position of the piston ring gap over time are important parameters for engine operation and durability.

[0012] The gap position of the upper compression ring has been shown to affect hydrocarbon exhaust substances, and ring gap alignment is thought to lead to increased oil consumption. Without rotational motion of the piston rings in a diesel engine, localized wear and carbon deposition can occur, while excessive rotational motion can contribute to severe wear on the ring sides.

[0013] U.S. Patent No. 6,155,109 discloses a system for measuring gap rotation, comprising a plurality of inductive detectors extending through the wall of a cylinder and spaced circumferentially within an axial plane intersected by each ring during piston reciprocation. The end gap position is associated with the detectors having large fluctuations in the sensed induced current.

[0014] Korean Patent No. 20010066041 discloses a gap position measuring device for piston rings, which includes a plurality of temperature sensors mounted in a ring shape at multiple positions within a cylinder block surrounding a piston coupled to a piston ring to sense the ambient temperature for detecting the gap position; a signal analyzer for analyzing the temperature values ​​sensed by each temperature sensor and received in real time; and a computer for detecting the gap position of the piston ring according to the highest and lowest temperature values ​​sensed by one of the temperature sensors from the information input from the signal analyzer. The gap position measuring device requires a plurality of temperature sensors to accurately determine the gap position. [Prior art documents] [Patent Documents]

[0015] [Patent Document 1] U.S. Patent No. 6155109 [Patent Document 2] Korean Patent No. 20010066041 [Overview of the project] [Problems that the invention aims to solve]

[0016] The present invention is based on the object of providing a gap position measuring device, an internal combustion engine having such a gap position measuring device, a method for measuring a gap position, and a computer program, which avoid known disadvantages and in particular provide safe, reliable and effective measurement of the piston ring gap. [MEANS FOR SOLVING THE PROBLEM]

[0017] This object is achieved by the features of the independent claims.

[0018] A gap position measuring device for an internal combustion engine comprising at least one cylinder having a liner wall and a reciprocating piston having at least one piston ring comprises at least a first set of sensors comprising at least one, preferably less than five temperature sensors, preferably 2, 3 or 4 temperature sensors, more preferably 3 temperature sensors.

[0019] The cylinder preferably has an inner diameter of at least 200 mm.

[0020] The temperature sensors are arranged in the liner wall and spaced apart in the circumferential direction. Preferably, all sensors of the first set of sensors are arranged in a first axial plane.

[0021] The gap positioning device comprises a signal analysis unit configured to receive temperature data of the temperature sensors.

[0022] The signal analysis unit may be configured to receive temperature data from only the first set of sensors, which are preferably arranged in one axial plane, and / or from only 1 to 4 sensors.

[0023] Each of the temperature sensors is connected to the signal analysis unit by a connecting line or wirelessly.

[0024] The signal analysis unit is configured to determine the angular position of the piston ring gap relative to the cylinder based on the received temperature data.

[0025] The signal analysis unit may be further configured to determine the angular position of the piston ring gap by fitting a fitting curve to the temperature data and determining the angular position of the maximum value of the fitting curve.

[0026] The signal analysis unit may only be configured to fit a fitting curve to the temperature data of one set of sensors having 1, 2, 3, or 4 temperature sensors, preferably 3 temperature sensors.

[0027] The signal analysis unit may be adapted to process the temperature data provided by the temperature sensors. Each sensor may preferably measure a time-dependent curve during one or more piston strokes.

[0028] The signal analysis unit may be adapted to determine an average value during a measurement time interval for further processing, for example for fitting. The time interval may have a duration of 0.5 seconds to 20 seconds, preferably a duration of 1 second to 10 seconds.

[0029] The signal analysis unit is further adapted to determine the angular position of the piston ring gap, in particular of the uppermost piston ring, relative to the cylinder by determining the circumferential position of the maximum value of the fitting curve.

[0030] The angular position of the piston ring gap can be determined with only a small number of temperature sensors. Fitting to the data of a set of sensors comprising only 1 to 4 sensors may be slightly less accurate than fitting to data from a greater number of sensors, but it has been found that the accuracy is sufficiently high, especially when the measurement is performed over a longer period of time.

[0031] Because gap position measurement devices are inexpensive, they can be easily added to existing combustion engines.

[0032] Furthermore, in the case of an engine already equipped with five or more temperature sensors in the cylinder, the gap position measuring device according to the present invention can be set up using only one to four temperature sensors, along with their respective signal analysis units, for example, when some of the temperature sensors are removed due to damage or contamination.

[0033] The sensor may be fixed in place by high-temperature epoxy or other means to prevent minute movements caused by engine vibrations.

[0034] The sensor may be mounted by spring suspension or secured with a bayonet plug. The sensor may be a PT1000 temperature sensor or a thermocouple.

[0035] Preferably, the fitting curve has a number of free parameters corresponding to the number of temperature sensors providing data.

[0036] Preferably, the fitting curve corresponds to the expected temperature profile along the circumference of the cylinder during the measurement interval and has one significant maximum value.

[0037] When using so-called particle filters or successive Monte Carlo methods to find approximate solutions for filtering problems of nonlinear state-space systems, fitting curves with more free parameters can also be used for fitting.

[0038] The fitting curve of the gap position measuring device may have the following forms.

number

[0039] An alternative fitting function may be used as a fitting curve that is continuous and has a single maximum value between 0° and 360°.

[0040] The maximum value of the fitting curve can provide the angular position of the piston ring gap, as it can be assumed that the piston ring gap is at the position of the maximum temperature.

[0041] Under normal conditions, the width of the piston ring gap does not change.

[0042] Nevertheless, if the gap width widens and there is significant wear causing leakage from the piston rings, this method may offer an inaccurate solution. However, regardless of the ring gap width, the maximum value of the temperature distribution is always at the same location. Only the amplitude may be affected, which also depends on other parameters such as the actual load point and the engine's fuel type.

[0043] Since a large amount of exhaust gas leaking into the underside of the piston is usually detected by a special sensor, leaks from the piston rings are caught by other monitoring solutions. In this case, the crew is aware that gap monitoring may be affected.

[0044] The signal analysis unit may be adapted to receive temperature data over time and determine the speed of rotational motion of the piston ring gap based on the angular position of the maximum value of the fitting curve over time.

[0045] In this context, “chronological” means that the temperature sensor data is provided from multiple, preferably consecutive, measurement intervals. Measurements may be taken, for example, during each expansion stroke, the circumferential position of the maximum temperature may be considered over several expansion strokes, and each measurement time corresponds to the time of the expansion stroke. The rotational speed of the piston ring gap corresponds to the piston ring rotational speed.

[0046] The signal analysis unit may be adapted to compare the rotational speed of the piston ring gap with a predetermined speed limit. If an excessive piston ring rotational speed is detected, the signal analysis unit may be adapted to trigger a signal action and / or inspection action. During the inspection action, it may be necessary to replace the piston rings.

[0047] The signal analysis unit may be adapted to receive temperature data over time and to determine a liner heatmap based on the angular position of the maximum value of the fitting curve over time.

[0048] The liner heatmap specifically corresponds to the probability of gap locations depending on the circumferential angle section or angular region.

[0049] The liner heatmap may also be represented by a histogram, which counts the frequency of occurrence of the maximum value of the fitting curve for each angle section around the circumference, i.e., the number of maximum values ​​over time for each angle section.

[0050] The histogram may be normalized, for example, by dividing it by the number of measurement events.

[0051] Therefore, circumferential sections that have a relatively large number of maximum occurrences compared to other circumferential sections have a higher probability of the piston ring gap being located within that section.

[0052] Typically, this higher probability after some time corresponds to more severe wear of the liner in this circumferential region, which can be confirmed when the liner is inspected, for example, optically.

[0053] The liner heatmap may include two or more maximum values ​​corresponding to two or more areas with more severe wear. Various reasons can cause more severe wear. For example, manufacturing issues with the liner may cause the inner shape of the liner to be more elliptical than circular in some areas. Additionally or alternatively, lubrication may differ in different areas of the liner.

[0054] The signal analysis unit may be adapted to trigger signal and / or inspection actions in response to the liner heatmap.

[0055] In particular, the signal analysis unit may be configured to compare the liner heatmap with a target heatmap and / or a target range, and to trigger a signal action and / or inspection action if the difference between the liner heatmap and the target heatmap exceeds a predetermined tolerance.

[0056] The target heatmap may correspond to an ideal heatmap, such as a uniform distribution of probabilities, or a histogram with the same number of maximum occurrences for all angular sections on the circumference.

[0057] The difference between the liner heatmap and the target heatmap may be determined, for example, by the maximum value of the liner heatmap compared to the average value of the target heatmap. The maximum value of the liner heatmap must not exceed certain limits, such as a predetermined tolerance, in order to prevent widespread wear.

[0058] If the maximum value approaches the limit, a signal operation and / or inspection operation may be triggered.

[0059] The specified tolerances may be chosen so as not to reach the limit in order to ensure low wear of the liner.

[0060] The inspection operation can be triggered based on information about the location of the maximum temperature.

[0061] For example, lubrication can be modified by increasing its amount across the entire cylinder or locally in individual injectors.

[0062] The amount of fuel injected in this cylinder can be reduced, especially compared to other cylinders, until the cylinder is completely shut down.

[0063] An order to conduct an inspection may be issued.

[0064] The signal analysis unit may be adapted to predict when the piston rings or cylinder jacket need to be replaced based on changes in the liner heatmap over time.

[0065] The gap position measuring device may include a monitor adapted to display the piston ring gap position, rotational speed, and / or liner heat map.

[0066] The monitor may also be adapted to display a signal or warning to trigger an inspection operation when necessary.

[0067] The gap position measuring device may further comprise at least one additional set of sensors, each having at least one temperature sensor, positioned within the liner wall of the cylinder and spaced circumferentially within their respective further axial planes.

[0068] Preferably, a further set of sensors also comprises one to four temperature sensors, more preferably three temperature sensors, within each further axial plane.

[0069] The first axial plane and the further axial planes may be spaced apart corresponding to the axial distance between the first piston ring and the further piston ring, and the signal analysis unit may be adapted to determine the angular position of the gap between the first piston ring and at least the further piston ring.

[0070] The signal analysis unit may be adapted to individually evaluate the temperature data of the sensor set, thereby allowing the risk of excessive wear of the ring or liner to be associated with each piston ring.

[0071] The signal analysis unit may be adapted to receive temperature data from the temperature sensor continuously or periodically, for example, after each stroke, once after a certain number of strokes, or once at specific time intervals such as once every hour.

[0072] The signal analysis unit may be adapted to process the received data continuously or periodically, preferably on the same time basis as the data is received.

[0073] The signal analysis unit may be adapted to use a particle filter (sequential Monte Carlo method).

[0074] When using a particle filter or a successive Monte Carlo method, the mathematical model may describe, for example, the temperature distribution profiles attributable to the first and second piston rings. These profiles may correspond to the fitting curves described above.

[0075] For example, when using only one set of sensors, the fitting curve may correspond to a fitting function with more parameters than the data provided by the measurement points. Therefore, the formula may be undetermined.

[0076] A particle filter method may be used to select random values ​​for the free parameter values, and Monte Carlo simulation may be used to determine which combination of values ​​best fits the measured values.

[0077] In the first step, there may be several different combinations to fit.

[0078] If the ring can move after the next measurement, the next iteration of the calculation is performed. In this iteration, the solution from the first simulation that was closest to the measured value is used as the starting point, and the random parameters of these solutions are changed only slightly and randomly.

[0079] From these solutions, only the optimal solution can be used for the next step.

[0080] After several iterations, usually only a few configurations remain that may look very similar.

[0081] The average value from all remaining components may be obtained to determine the position of the piston ring gap.

[0082] This solution has been found to be very close to the actual position of the piston ring gap at that time.

[0083] By using Monte Carlo simulation, only two sensors are required, and these sensors are preferably positioned on the top dead center position of the upper ring.

[0084] If there are three sensors at the top dead center position of each ring, the fitting curve for the three parameters shown above can be obtained without Monte Carlo simulation.

[0085] The object of the present invention is also achieved by an internal combustion engine comprising at least one cylinder and a reciprocating piston having at least one piston ring, and equipped with a gap position measuring device as described above.

[0086] The object of the present invention is also achieved by a method for operating an internal combustion engine, preferably as described above, which includes a cylinder and a reciprocating piston having at least one piston ring, and the method comprises the following steps:

[0087] Temperature data from one, two, three, or four measurement points, preferably three, on or within the liner wall of the cylinder, spaced circumferentially in the axial plane, is preferably provided and received by each temperature sensor.

[0088] The fitting curve is fitted to the temperature data, and the angular position of the piston ring gap relative to the cylinder is determined by determining the angular position of the maximum value of the fitting curve.

[0089] The method may include a further step of receiving temperature data over time and determining a liner heatmap based on the angular position of the maximum value of the fitting curve over time.

[0090] The liner heatmap specifically corresponds to the probability of gap locations depending on the circumferential angle section. The liner heatmap may also be represented by a histogram that counts the frequency of occurrence of the maximum value of the fitting curve for each angle section around the circumference.

[0091] The method may include further steps that trigger signaling and / or inspection actions in response to the liner heatmap.

[0092] The object of the present invention is also achieved by a computer program which includes program code for performing the steps of the method described above when the program is executed on a computer of an internal combustion engine as described above.

[0093] The object of the present invention is also achieved by a computer program product which is directly loadable into the internal memory of a digital computer, and includes a software code portion that performs the method steps described above when the program is running on the digital computer of an internal combustion engine as described above.

[0094] Further advantageous aspects of the present invention are described below with reference to exemplary embodiments and figures. The figures schematically illustrate the following: [Brief explanation of the drawing]

[0095] [Figure 1] This is a schematic side view of an internal combustion engine having a cylinder with a piston having piston rings. [Figure 2] This is a schematic cross-sectional view of the gap position measuring device in the first axial plane. [Figure 3] This is a schematic diagram of the temperature data and fitting curve. [Figure 4] This figure shows the first example of a liner heatmap. [Figure 5] This figure shows a second example of a liner heatmap. [Modes for carrying out the invention]

[0096] Figure 1 shows a schematic diagram of an internal combustion engine 1 having a cylinder 2 having a piston 4 with piston rings 5.

[0097] The piston 4 reciprocates within the cylinder. In this figure, two piston rings 5, 25 are shown. The piston 4 may have only one piston ring 5, or it may have two or more piston rings.

[0098] A first set of sensors, having three temperature sensors 11A, 11B, and 11C, is positioned within the liner wall 3 of the cylinder 2 in a first axial plane 12.

[0099] A further set of sensors having a temperature sensor 22 may be arranged within the liner wall 3 of the cylinder 2, and these temperature sensors 22 may also be spaced circumferentially within their respective further axial planes 23. The further axial planes 23 are preferably spaced away from the first axial plane 12, corresponding to the axial distance 24 between the first piston ring 5 and the further piston ring 25.

[0100] In the longitudinal scavenging cylinder 2, temperature sensors 11A, 11B, 11C (see Figure 2) and 22 may be positioned above the scavenging port (not shown in the figure).

[0101] For example, sensors 11A, 11B, and 11C may be positioned vertically at the center of the first piston ring 5 when the piston 4 is at top dead center (TDC). At this position, the piston 4 is as close as possible to the position where the greatest "blow-out" of exhaust gas from the ring gap 6 occurs, and therefore the largest temperature change occurs. Alternatively, sensors 11A, 11B, and 11C may be positioned vertically above the first ring 4 at its TDC position, i.e., closer to the internal combustion chamber. This position also provides reasonable results in the present invention. Figure 2 shows a schematic cross-sectional view of the gap position measuring device 10 in the first axial plane 12 (Figure 1). The gap position measuring device 10 has three temperature sensors 11A, 11B, and 11C, which are positioned within the liner wall 3 of the cylinder 2 and spaced circumferentially apart from each other in the first axial plane 12.

[0102] The three temperature sensors 11A, 11B, and 11C are positioned at equally separated angular positions A, B, and C.

[0103] The gap positioning device 10 includes a signal analysis unit 13 adapted to receive data 15A, 15B, 15C (see Figure 3) from temperature sensors 11A, 11B, 11C.

[0104] The signal analysis unit 13 may also be adapted to receive data from temperature sensors 22 of an additional sensor set located in one or more additional axial planes 23 (see Figure 1).

[0105] The signal analysis unit 13 may be adapted to provide data for displaying the angular position of the piston ring gap on the monitor 14. The monitor 14 may also display a warning signal or trigger an inspection action.

[0106] Figure 3 shows a schematic diagram of the temperature data 15A, 15B, 15C and the fitting curve 16.

[0107] Typically, temperature data 15A, 15B, and 15C are measured during the piston stroke as the piston ring 6 passes through the axial plane 12. In this example, the fitting curve 16 has the following form.

number

[0108] The signal analysis unit 13 is adapted to fit the fitting curve 16 to the data 15A, 15B, and 15C measured at angular positions A, B, and C by sensors 11A, 11B, and 11C (see Figure 2).

[0109] The circumferential position of the maximum value 18 of the fitting curve 16, which corresponds to the angular position 17 of the piston ring gap 6 with respect to the cylinder circumference, is determined.

[0110] The signal analysis unit 13 may be adapted to determine the angular position of the piston ring gaps 6, 26 of the first piston ring 5 and at least one further piston ring 25 (see Figure 1).

[0111] Figure 4 shows a first example of a liner heatmap 19a. The circumferential position of the maximum value 18 of the fitting curve 16 (see Figure 3) is represented by lines at each angle in the circle diagram. Areas with more lines have a higher risk of heat input to the liner and a higher risk of wear.

[0112] Figure 5 shows a second example of the liner heatmap 19b.

[0113] The occurrence of the maximum value 18 of the fitting curve 16 (see Figure 3), corresponding to the probability of the piston ring gap position within a specific angle section 21, is shown.

[0114] The y-axis corresponds to the number of occurrences (20), and the x-axis corresponds to the angle section (21).

[0115] In the angle region 29, the number of occurrences was 20. m The difference 28 between the target heatmap 27 and the current heatmap 27 may exceed a predetermined tolerance value 30. In this angular region, the likelihood of liner wear is higher. Therefore, the signal analysis unit 13 (see Figure 2) may provide a warning signal.

[0116] Note Any embodiment described for a device is equally relevant to this method. Synergistic effects may arise from different combinations of embodiments, which may not be described in detail.

[0117] While currently preferred embodiments of the present invention have been shown and described, it should be clearly understood that the present invention is not limited thereto and can be embodied and implemented in various other ways within the scope of the following claims. [Explanation of Symbols]

[0118] 1. Internal combustion engine 2. One cylinder 3 Liner Wall 4 pistons 5 Piston Rings 6. Piston ring gap 10 Gap position measuring device 11A, 11B, 11C temperature sensors 12 First axial plane 13 Signal Analysis Unit 14 monitors 15A, 15B, 15C Data 16. Fitting Curve 17 Angular position 18 Maximum value 19a, 19b Liner Heatmap 20 occurrences 21 Circumferential angle 22 Temperature Sensor 23 Second axial plane 24 Axial distance 5.25 Two piston rings 6.26 Gap 27. Target Heatmap 28 difference 29 Angular area 30 Prescribed tolerance

Claims

1. A gap position measuring device (10) for an internal combustion engine (1) comprising at least one cylinder (2) having a liner wall (3) and a reciprocating piston (4) having at least one first piston ring (5) having a piston ring gap (6), wherein the gap position measuring device (10) is A first set of sensors comprising at least one temperature sensor (11A, 11B, 11C), preferably adapted to be positioned on or within the liner wall (3), and preferably three temperature sensors spaced circumferentially in a first axial plane (12), A gap position measuring device (10) comprising a signal analysis unit (13) configured to receive temperature data (15A, 15B, 15C) from the first set of sensors (11A, 11B, 11C), and further adapted to determine the angular position (17) of the piston ring gap (6) relative to the cylinder based on the received temperature data.

2. The gap position measuring device according to claim 1, wherein the first set of sensors comprises fewer than five temperature sensors.

3. The signal analysis unit (13) is configured to fit a fitting curve (16) to the temperature data (15A, 15B, 15C) and determine the angular position (17) of the piston ring gap (6) by determining the angular position (18) of the maximum value of the fitting curve (16). Advantageously, the fitting curve (16) takes the following form. [Math 1] A gap position measuring device according to claim 1 or 2, having the following features.

4. The gap position measuring device according to claim 3, wherein the signal analysis unit (13) is configured to receive the temperature data (15A, 15B, 15C) over time and to determine the speed of rotational motion of the piston ring gap (6) based on the angular position (17) of the maximum value (18) of the fitting curve (16) over time.

5. The gap position measuring device according to claim 3 or 4, wherein the signal analysis unit (13) is configured to receive the temperature data (15A, 15B, 15C) over time and to determine the liner heat map (19a, 19b) of the angular position (17) of the piston ring gap (6).

6. The signal analysis unit (13) is configured to emit a signal and / or trigger an inspection operation based on the liner heat map. In particular, the gap position measuring device according to claim 5, wherein the signal analysis unit (13) is configured to compare the liner heatmaps (19a, 19b) with a target heatmap (22) and to trigger the signal and / or the inspection operation when the difference (28) between the liner heatmaps (19a, 19b) and the target heatmap (27) is greater than a predetermined threshold.

7. A gap position measuring device according to any one of claims 1 to 6, further comprising a monitor (14) configured to display the angular position (17) of the piston ring gap (6), the speed of the rotational motion of the piston ring gap (6), and / or the liner heatmap (19a, 19b).

8. The gap position measuring device (10) comprises at least one temperature sensor (22), preferably a further set of sensors having three temperature sensors (22) arranged within the liner wall (3) and adapted to be spaced apart circumferentially in a further axial plane (23), wherein the first axial plane (12) and the further axial plane (23) are preferably arranged at an axial distance corresponding to the axial distance (24) between the first piston ring (5) and the further piston ring (25), and the signal analysis unit (13) is configured to determine the angular position of the piston ring gap (6, 26) of the first piston ring and the further piston ring based on the temperature data (15A, 15B, 15C) from the first set of sensors and the temperature data from the further set of sensors, according to any one of claims 1 to 7.

9. The gap position measuring device according to any one of claims 1 to 8, wherein the signal analysis unit (13) is configured to continuously receive the temperature data (15A, 15B, 15C) at predetermined periodic time intervals, irregular time intervals, or as requested.

10. The gap position measuring device according to any one of claims 1 to 9, wherein the signal analysis unit (13) is configured to use a successive Monte Carlo method.

11. An internal combustion engine (1) comprising at least one cylinder (2) having a liner wall (3), a reciprocating piston (4) having at least one piston ring (5, 25), and a gap position measuring device (10) according to any one of claims 1 to 10.

12. Preferably, a method for operating an internal combustion engine (1) as described in claim 11, wherein the method is A step of receiving temperature data (15A, 15B, 15C) from a first set of at least one measurement point (A, B, C), preferably fewer than five measurement points, preferably three measurement points, located on or within the liner wall (3) of a cylinder (2), wherein the measurement points are preferably spaced apart circumferentially in a first axial plane (12, 23). A method comprising the step of determining the angular position (18) of the piston ring gap (6) relative to the cylinder (3) based on the temperature data.

13. In order to determine the angular position (18) of the piston ring gap (6), The steps include: fitting a fitting curve (16) to the temperature data (15A, 15B, 15C), determining the angular position (17) of the maximum value (18) of the fitting curve (16); and Steps using the sequential Monte Carlo method The method according to claim 12, further comprising at least one further step from the group consisting of

14. The steps include receiving the temperature data (15A, 15B, 15C) over time and determining the liner heatmap (19a, 19b) of the angular position (17) of the piston ring gap (6), and Preferably, the step of emitting a signal and / or triggering an inspection operation based on the liner heat map (19a, 19b). The method according to claim 12 or 13, further comprising the steps of the method.

15. A computer program comprising, when the program is executed by the computer of the internal combustion engine (1) described in claim 11, an instruction causing the computer to perform the method described in any one of claims 12 to 15.

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