Gap position measuring device

Abstract

The invention relates to a gap position measuring device. A gap position measuring device for an internal combustion engine, the internal combustion engine comprising at least one cylinder having a cylinder liner wall and a reciprocating piston having at least one first piston ring, the first piston ring having a piston ring gap. The gap position measuring device comprises a first set of sensors having three temperature sensors, the first set of sensors being adapted to be arranged on or in the cylinder liner wall, being spaced apart circumferentially in a first axial plane. Furthermore, the gap position measuring device comprises a signal analysis unit, the signal analysis unit being configured to receive temperature data from the first set of sensors and being further adapted to determine an 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 piston ring clearance position measuring device for a reciprocating internal combustion engine, a reciprocating internal combustion engine having such clearance position measuring device, a method for measuring the clearance position of piston rings in an internal combustion engine, and a computer program.

[0002] This invention preferably relates to a reciprocating internal combustion engine, such as a large marine or ship engine or a stationary engine, whose cylinder has 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-fueled engine, a dual-fuel or multi-fuel engine. Combustion of liquid and / or gaseous fuels in such an engine, as well as auto-ignition or forced ignition, are possible. Background Technology

[0003] The internal combustion engine can be a longitudinally scavenging two-stroke engine.

[0004] The term "internal combustion engine" also refers to a large engine that can operate not only in the Diesel cycle, characterized by auto-ignition of fuel, but also in the Otto cycle, characterized by forced ignition of fuel, or a combination of both. Furthermore, the term "internal combustion engine" specifically includes dual-fuel engines and large engines in which auto-ignition of one fuel is used for forced ignition of another.

[0005] The engine speed is preferably below 800 RPM (especially for four-stroke engines), and more preferably below 200 RPM (especially for two-stroke engines), which is a hallmark of low-speed engines.

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

[0007] Other possible fuels that can be added upon request include: LBG (liquefied biogas), biofuels (such as oil made from algae or seaweed), ammonia, hydrogen, and synthetic fuels derived from CO2 (such as synthetic fuels made from energy converted to gas or liquid).

[0008] Large ships (especially those used for transporting cargo) are typically powered by internal combustion engines (particularly diesel and / or gas-fueled engines, primarily two-stroke crosshead engines).

[0009] The piston of a reciprocating piston internal combustion engine (especially a dual-fuel or Otto cycle type reciprocating piston internal combustion engine) is provided with piston rings that form a piston ring assembly. The piston rings are placed in grooves in the piston and are used to seal and isolate the combustion chamber from the outside.

[0010] Piston rings can have ring bodies with gaps between their ends, or ring bodies with two overlapping ends forming a piston ring lock. However, in the region of the piston ring lock, the piston rings are not completely closed, and the pressure in the cylinder may force hot gases through the piston ring lock. Therefore, even if there is no actual gap between the ends of the ring bodies, the piston ring lock is referred to as a piston ring gap.

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

[0012] The clearance position of the top compression ring has been shown to affect hydrocarbon emissions, and misalignment of the ring clearance is believed to lead to increased fuel consumption. In diesel engines, the absence of piston ring rotation can cause localized wear and carbon deposits, while excessive rotation can lead to high wear on the ring sides.

[0013] US6155109 discloses a system for measuring end gap rotation, comprising multiple inductive detectors extending through the wall of a cylinder and circumferentially spaced in an axial plane intersected by each ring during piston reciprocating motion. The end gap position is associated with a detector having a significant change in sensed induced current.

[0014] KR20010066041 discloses a piston ring gap position measuring device, which includes: multiple temperature sensors mounted in a ring shape at multiple locations in a cylinder block to surround a piston connected to the piston rings, for sensing ambient temperature to detect the gap position; a signal analyzer for analyzing the temperature values ​​sensed and received in real time by the individual temperature sensors; and a computer for detecting the piston ring gap position based on information input from the signal analyzer, according to the maximum and minimum temperature values ​​sensed by one of the temperature sensors. The gap position measuring device requires multiple temperature sensors to accurately determine the gap position. Summary of the Invention

[0015] The present invention is based on the objective of providing a clearance position measuring device, an internal combustion engine having such a clearance position measuring device, a method for measuring clearance position, and a computer program that avoids the disadvantages of known technologies, and in particular provides a safe, reliable, and effective measurement of piston ring clearance.

[0016] A clearance position measuring device for an internal combustion engine, the internal combustion engine comprising: at least one cylinder having a cylinder liner wall; a reciprocating piston having at least one piston ring, the clearance position measuring device comprising at least a first set of sensors, the first set of sensors comprising at least one temperature sensor, preferably fewer than five temperature sensors, preferably two, three or four temperature sensors, more preferably three temperature sensors.

[0017] Preferably, the cylinder has an inner diameter of at least 200 mm.

[0018] Temperature sensors are arranged in the cylinder liner wall and spaced circumferentially. Preferably, all sensors in the first group are arranged in the first axial plane.

[0019] The gap position measuring device includes a signal analysis unit configured to receive temperature data from a temperature sensor.

[0020] The signal analysis unit can be configured to receive temperature data from only the first set of sensors and / or only one to four sensors, which are preferably arranged in an axial plane.

[0021] Each temperature sensor is connected to the signal analysis unit via a cable or wirelessly.

[0022] The signal analysis unit is configured to determine the angular position of the piston ring clearance relative to the cylinder based on the received temperature data.

[0023] The signal analysis unit can also be configured to determine the angular position of the piston ring gap by fitting a fitted curve to the temperature data and by determining the angular position of the maximum value of the fitted curve.

[0024] The signal analysis unit can be configured simply to fit a fitted curve to temperature data from a set of sensors having one, two, three, or four temperature sensors (preferably three temperature sensors).

[0025] The signal analysis unit can be adapted to process temperature data provided by temperature sensors. Preferably, each sensor can measure a curve of change over time during one or more piston strokes.

[0026] The signal analysis unit can be adapted to determine the average value over the measurement time interval for further processing, such as for fitting. The time interval can have a duration from 0.5 seconds to 20 seconds (preferably 1 second to 10 seconds).

[0027] The signal analysis unit is also adapted to determine the angular position of the piston ring clearance (especially the uppermost piston ring) relative to the cylinder by determining the circumferential position of the maximum value of the fitted curve.

[0028] The angular position of the piston ring gap can be determined using only a few temperature sensors. Fitting data to a set of sensors consisting of only one to four sensors may have slightly lower accuracy than fitting data to data from more sensors, but this accuracy has proven to be high enough, especially when measurements are taken over a longer period of time.

[0029] Clearance position measuring devices can be easily retrofitted into existing internal combustion engines at a relatively low cost.

[0030] Furthermore, for engines that already include more than four temperature sensors in the cylinder, the clearance position measuring device according to the invention can be equipped with a corresponding signal analysis unit that uses only one to four temperature sensors, for example, when some temperature sensors are removed due to damage or dirt.

[0031] The sensor can be fixed in a suitable position using high-temperature epoxy resin or other devices to prevent micro-movements caused by engine vibration.

[0032] The sensor can be spring-loaded and secured with a bayonet plug. The sensor can be a PT1000 temperature sensor or a thermocouple.

[0033] Preferably, the fitted curve has multiple free parameters corresponding to the number of temperature sensors providing the data.

[0034] Preferably, the fitted curve corresponds to the expected temperature distribution along the circumference of the cylinder during the measurement interval, which has a significant maximum value.

[0035] When using the so-called particle filter or sequential Monte Carlo method, fitting curves with more free parameters can also be used for fitting. The so-called particle filter or sequential Monte Carlo method finds an approximate solution to the filtering problem of nonlinear state-space systems.

[0036] The fitting curve of the gap position measuring device can have the following form: .

[0037] An alternative fitting function can be used as a fitting curve, which is continuous and has a value at 0. and 360 The single maximum value between.

[0038] The maximum value of the fitted curve can provide the angular position of the piston ring gap, since it can be assumed that the piston ring gap is located at the position of maximum temperature.

[0039] Under normal circumstances, the width of the piston ring gap will not change.

[0040] However, if there is such significant wear that the gap width will widen and the piston rings will leak, this method may provide a less precise solution. However, regardless of the ring gap width, the maximum temperature distribution will always be in the same location. It may only affect the amplitude, and this effect also depends on other parameters such as the engine's actual load point and fuel type.

[0041] Piston ring leaks will be detected by other monitoring methods, as leaks of large amounts of exhaust gas into the underside of the piston are typically detected by specialized sensors. In this situation, the crew will realize that clearance monitoring may be compromised.

[0042] The signal analysis unit can be adapted to: receive temperature data that changes over time; and determine the speed of rotation of the piston ring gap based on the angular position of the maximum value of the fitted curve that changes over time.

[0043] In this document, "varying over time" refers to data from temperature sensors provided from multiple (preferably consecutive) measurement intervals. For example, measurements can be taken during each expansion stroke, and the circumferential position of the temperature maximum value during multiple expansion strokes can be considered, where each measurement time corresponds to the duration of the expansion stroke. The speed of the rotational movement of the piston ring clearance corresponds to the piston ring rotation speed.

[0044] The signal analysis unit can be adapted to compare the rotational speed of the piston ring clearance with a predetermined speed limit. If an excessively high piston ring rotational speed is detected, the signal analysis unit can be adapted to trigger a signal and / or maintenance action. During maintenance, it may be necessary to replace the piston rings.

[0045] The signal analysis unit is adapted to receive temperature data that changes over time and to determine the cylinder liner thermal map based on the angular position of the maximum value of the fitted curve that changes over time.

[0046] In particular, the cylinder liner heat map corresponds to the probability that the gap location depends on the circumferential corner portion or corner region.

[0047] A cylinder liner heat map can be represented by a histogram, in which the number of times the maximum value of the fitted curve appears in each corner of the circumference is counted, that is, the number of times the maximum value changes over time in each corner.

[0048] Histograms can be normalized, for example, by dividing by the number of events measured.

[0049] Therefore, compared to other circumferential portions, the circumferential portion with a relatively high maximum occurrence frequency is more likely to be where the piston ring gap is located.

[0050] Typically, after a period of time, this higher probability corresponds to higher wear of the cylinder liner in this circumferential area, which can be confirmed, for example, when the cylinder liner is inspected optically.

[0051] A cylinder liner thermal map may include more than one maximum value, which corresponds to more than one area with higher wear. Various factors can cause higher wear. For example, manufacturing problems with the cylinder liner may cause the internal shape of the cylinder liner to be more elliptical than circular in some areas. Additionally or alternatively, lubrication may vary in different areas of the cylinder liner.

[0052] The signal analysis unit can be adapted to trigger signals and / or maintenance actions based on cylinder liner heat maps.

[0053] Specifically, the signal analysis unit may be adapted to: compare the cylinder liner heat map with a target heat map and / or with a target range; and if the difference between the cylinder liner heat map and the target heat map exceeds a predetermined acceptable value, trigger a signal and / or maintenance action.

[0054] The target heatmap can correspond to an ideal heatmap, such as a uniform distribution of probability for all corner portions of a circle or a histogram with the same number of maximum occurrences.

[0055] The difference between the cylinder liner heat map and the target heat map can be determined by comparing the maximum value of the cylinder liner heat map with the average value of the target heat map.

[0056] The maximum value of the cylinder liner heat map should not exceed a certain limit, such as a predetermined acceptable value, to prevent extensive wear.

[0057] If the maximum value approaches the limit, it can trigger a signal and / or maintenance action.

[0058] A predetermined acceptable value can be selected so that the limit is not reached, thus ensuring low wear of the cylinder liner.

[0059] Maintenance actions can be triggered based on information about the location of the maximum temperature.

[0060] For example, lubrication can be altered by increasing the amount of fuel throughout the cylinder or locally at individual injectors.

[0061] In this cylinder, especially relative to other cylinders, the amount of fuel injected can be reduced until the cylinder completely stops working.

[0062] It can trigger an instruction to perform a check.

[0063] The signal analysis unit can be adapted to predict when piston rings or cylinder water jackets must be replaced based on changes in cylinder liner heat maps over time.

[0064] The clearance position measuring device may include a monitor adapted to display the position of the piston ring clearance, rotational speed, and / or cylinder liner thermal image.

[0065] The monitor can also be adapted to display signals or warnings to trigger maintenance actions when necessary.

[0066] The clearance position measuring device may include at least another set of sensors, the at least another set of sensors having at least one temperature sensor, the at least another set of sensors being arranged in the cylinder liner wall of the cylinder and circumferentially spaced apart in a corresponding other axial plane.

[0067] Preferably, the other set of sensors also includes one to four temperature sensors in the corresponding other axial plane, more preferably three temperature sensors.

[0068] The first axial plane and the other axial plane may be spaced apart corresponding to the axial distance between the first piston ring and the other 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 other piston ring.

[0069] The signal analysis unit can be adapted to evaluate the temperature data of the sensor group independently, so that the risk of excessive wear of the ring or cylinder liner can be associated with the corresponding piston ring.

[0070] The signal analysis unit can be adapted to receive temperature data from the temperature sensor continuously or periodically, for example, once after a certain number of strokes for each stroke, or once at a certain time interval (e.g., once per hour).

[0071] The signal analysis unit can be adapted to process the received data continuously or periodically, preferably on the same time basis as the received data.

[0072] The signal analysis unit can be adapted to use a particle filter (sequential Monte Carlo method).

[0073] When using a particle filter or sequential Monte Carlo method, a mathematical model can describe the profile of the temperature distribution caused by, for example, the first and second piston rings. This profile can correspond to the fitted curve described above.

[0074] For example, when using only one set of sensors, the fitted curve may correspond to a fitted function with more parameters than the data provided by the measurement points. Therefore, these equations may be uncertain.

[0075] According to the particle filter method, random values ​​are selected for the free parameters, and through Monte Carlo simulation, it can be determined which combination of values ​​best fits the measured values.

[0076] In the first step, there can be several different combinations of fitting.

[0077] After the next measurement, when the loop may have moved, the next computational iteration is performed. For this iteration, the solution from the closest measurement in the first simulation is used as the starting point, and the random parameters of these solutions vary only slightly in a random manner.

[0078] Of these solutions, only the best one can be used for the next step.

[0079] After several iterations, only a few configurations are usually left that look very similar.

[0080] The location of the piston ring gap can be determined by averaging the values ​​from all remaining configurations.

[0081] As a result, the solution is very close to the actual position of the piston ring gap.

[0082] By using Monte Carlo simulation, only two sensors are needed, which are preferably positioned at the top dead center of the top ring.

[0083] With three sensors at the top dead center of each ring, fitting the three-parameter curves shown above is possible without Monte Carlo simulation.

[0084] The object of the present invention is also achieved by an internal combustion engine comprising: at least one cylinder; a reciprocating piston having at least one piston ring; and a clearance position measuring device as described above.

[0085] The object of the present invention is also achieved by a method for operating an internal combustion engine, preferably an internal combustion engine as described above, the internal combustion engine having a cylinder and a reciprocating piston having at least one piston ring, the method comprising the following steps.

[0086] Temperature data are received at one, two, three, or four (preferably three) measuring points on or within the cylinder liner wall, the measuring points being circumferentially spaced in an axial plane, the temperature data preferably being provided by corresponding temperature sensors.

[0087] The fitted curve is fitted onto the temperature data, and the angular position of the piston ring clearance relative to the cylinder is determined by identifying the angular position of the maximum value of the fitted curve.

[0088] The method may include another step: receiving temperature data that changes over time and determining the cylinder liner thermal map based on the angular position of the maximum value of the fitted curve over time.

[0089] Specifically, the cylinder liner heatmap corresponds to the probability that the gap location depends on the circumferential corner portion. The cylinder liner heatmap can be represented by a histogram that counts the number of times the maximum value of the fitted curve occurs at each corner portion around the circumference.

[0090] The method may include an additional step: triggering signals and / or maintenance actions based on cylinder liner thermal images.

[0091] The object of the present invention is also achieved by a computer program comprising program code that, when executed on a computer of an internal combustion engine as described above, performs the steps of the method as described above.

[0092] The object of the present invention is also achieved by a computer program product that can be directly loaded into the internal memory of a digital computer. The computer program product includes a software code portion that, when the program is run on the digital computer of the internal combustion engine as described above, executes the method steps described above. Attached Figure Description

[0093] Other advantageous aspects of the invention will be explained below with reference to exemplary embodiments and accompanying drawings.

[0094] In the accompanying drawings, the following is illustrated: Figure 1 A schematic diagram of an internal combustion engine is shown in the side view. The internal combustion engine has a cylinder with a piston and piston rings. Figure 2 A schematic diagram of the gap position measuring device is shown in a cross-sectional view of the first axial plane; Figure 3 A schematic diagram showing temperature data and fitted curves is provided. Figure 4 A first example of a cylinder liner heat map is shown; Figure 5 A second example of a cylinder liner heat map is shown.

[0095] Figure Labels

[0096] Internal combustion engine (1)

[0097] Cylinder (2)

[0098] Cylinder liner wall (3)

[0099] Piston (4)

[0100] Piston rings (5)

[0101] Piston ring gap 6

[0102] Gap position measuring device (10)

[0103] Temperature sensors (11A, 11B, 11C)

[0104] First axial plane (12)

[0105] Signal Analysis Unit (13)

[0106] Monitor (14)

[0107] Data (15A, 15B, 15C)

[0108] Fitted curve (16)

[0109] Corner position (17)

[0110] Maximum value (18)

[0111] Cylinder liner thermal images (19a; 19b)

[0112] Number of occurrences (20)

[0113] Corner section (21)

[0114] Temperature sensor (22)

[0115] Second axial plane (23)

[0116] Axial distance (24)

[0117] Two piston rings (5, 25)

[0118] Gap (6, 26)

[0119] Target heatmap (27)

[0120] Difference (28)

[0121] Corner region (29)

[0122] The pre-determined acceptable value (30) Detailed Implementation

[0123] Figure 1 A schematic diagram of an internal combustion engine 1 is shown. The internal combustion engine 1 has a cylinder 2, the cylinder 2 has a piston 4, and the piston 4 has piston rings 5.

[0124] Piston 4 reciprocates within the cylinder. Two piston rings 5 ​​and 25 are shown in the figure. Piston 4 may have only one piston ring 5, or it may have two or more piston rings.

[0125] A first set of sensors, comprising three temperature sensors 11A, 11B, and 11C, is arranged in the cylinder liner wall 3 of the cylinder 2 in the first axial plane 12.

[0126] Another set of sensors with temperature sensor 22 can be arranged in the cylinder liner wall 3 of cylinder 2, and the temperature sensor 22 can also be circumferentially spaced in a corresponding additional axial plane 23. The additional axial plane 23 is preferably a distance from the first axial plane 12 corresponding to the axial distance 24 between the first piston ring 5 and the other piston ring 25.

[0127] In the longitudinal scavenging cylinder 2, temperature sensors 11A, 11B, and 11C (see...) Figure 2 ) and 22 can be arranged above the scavenging port (not shown in the figure).

[0128] For example, when piston 4 is at top dead center (TDC), sensors 11A, 11B, and 11C can be positioned at the vertical center of the first piston ring 5. In this position, piston 4 is as close as possible to the location where the maximum "leakage" of exhaust gas through the ring gap 6 occurs, resulting in the highest temperature change. Alternatively, sensors 11A, 11B, and 11C can be vertically arranged above the TDC position of the first piston ring 5, i.e., closer to the combustion chamber. This position also provides reasonable results in this method.

[0129] Figure 2 First axial plane 12 (see Figure 1 A schematic diagram of the clearance position measuring device 10 is shown in the cross-sectional view of the cylinder 2. The clearance position measuring device 10 has three temperature sensors 11A, 11B, and 11C, which are arranged in the cylinder liner wall 3 of the cylinder 2 and circumferentially spaced apart from each other in the first axial plane 12.

[0130] Three temperature sensors 11A, 11B, and 11C are arranged at equidistant angular positions A, B, and C.

[0131] The gap position measuring device 10 includes a signal analysis unit 13, which is adapted to receive data 15A, 15B, 15C from temperature sensors 11A, 11B, 11C (see...). Figure 3 ).

[0132] Signal analysis unit 13 may also be adapted to receive signals arranged in one or more additional axial planes 23 (see Figure 1 The data from the temperature sensor 22, another set of sensors in the group.

[0133] The signal analysis unit 13 is adapted to provide data for displaying the angular position of the piston ring clearance on the monitor 14. The monitor 14 can also display warning signals or trigger maintenance actions.

[0134] Figure 3 A schematic diagram of temperature data 15A, 15B, 15C and fitted curve 16 is shown.

[0135] Typically, temperature data 15A, 15B, and 15C are measured when the piston ring 6 passes through the axial plane 12 during the piston stroke.

[0136] In this example, the fitted curve 16 has the following form: .

[0137] Signal analysis unit 13 is adapted to fit the fitted curve 16 to the signal generated by sensors 11A, 11B and 11C (see...). Figure 2 The data measured at angular positions A, B, and C are 15A, 15B, and 15C.

[0138] The circumferential position of the maximum value 18 of the fitted curve 16 is determined, which corresponds to the angular position 17 of the piston ring gap 6 relative to the cylinder circumference.

[0139] Signal analysis unit 13 can be adapted to determine the first piston ring 5 and at least one additional piston ring 25 (see [link]). Figure 1 The piston ring clearance is 6, and the angular position is 26.

[0140] Figure 4 A first example of cylinder liner thermal image 19a is shown. Fitted curve 16 (see...) Figure 3 The circumferential position of the maximum value of 18 is represented by lines at the corresponding angles on the circle diagram. Areas with more lines have a higher risk of heat input to the cylinder liner and a higher risk of wear.

[0141] Figure 5 A second example of cylinder liner heat map 19b is shown.

[0142] Fitted curve 16 (see) Figure 3 The maximum value of 18, which occurs 20 times, corresponds to the probability that the piston ring gap position is in a certain corner portion 21.

[0143] The y-axis corresponds to the occurrence count of 20, and the x-axis corresponds to the angle portion of 21.

[0144] It appears 20 times in corner region 29. m The difference 28 between the target heatmap 27 and the target heatmap 28 may exceed the predetermined acceptable value 30. Within this angular range, cylinder liner wear is more likely to occur. Therefore, signal analysis unit 13 (see...) Figure 2 It can provide warning signals.

[0145] Remark

[0146] Any embodiment described with respect to the apparatus should similarly relate to the method. Synergistic effects can arise from different combinations of embodiments, although they may not be described in detail.

[0147] While presently preferred embodiments of the invention have been shown and described, it should be clearly understood that the invention is not limited thereto, but may be practiced and implemented in various other ways within the scope of the appended claims.

Claims

1. A clearance position measuring device (10) for an internal combustion engine (1), the internal combustion engine (1) comprising: At least one cylinder (2), the at least one cylinder (2) having a cylinder liner wall (3); a reciprocating piston (4), the piston (4) having at least one first piston ring (5), the at least one first piston ring (5) having a piston ring gap (6), wherein the gap position measuring device (10) includes: - A first set of sensors, the first set of sensors having at least one temperature sensor (11A, 11B, 11C), preferably three temperature sensors, the first set of sensors being adapted to be arranged on or in the cylinder liner wall (3), preferably circumferentially spaced apart in a first axial plane (12); and - Signal analysis unit (13), which is configured to receive temperature data (15A, 15B, 15C) from the first set of sensors (11A, 11B, 11C) and is also 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 group of sensors includes fewer than five temperature sensors.

3. The gap position measuring device according to claim 1 or 2, wherein, The signal analysis unit (13) is configured to determine the angular position (17) of the piston ring gap (6) by fitting a fitted curve (16) to the temperature data (15A, 15B, 15C) and by determining the angular position of the maximum value (18) of the fitted curve (16). Advantageously, the fitted curve (16) has the following form: 。 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) that varies over time; and to determine the speed of rotation of the piston ring gap (6) based on the angular position of the maximum value (18) of the fitted curve (16) that varies over time.

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

6. The gap position measuring device according to claim 5, wherein, The signal analysis unit (13) is configured to issue signals and / or trigger maintenance actions based on the cylinder liner heat map, and Specifically, the signal analysis unit (13) is configured to: compare the cylinder liner heat map (19a; 19b) with the target heat map (27); and if the difference (28) between the cylinder liner heat map (19a; 19b) and the target heat map (27) is greater than a predetermined threshold, then trigger the signal and / or trigger the maintenance action.

7. The clearance position measuring device according to any one of the preceding claims, the clearance position measuring device further comprising a monitor (14) configured to display the angular position (17) of the piston ring clearance (6), the speed of the rotational movement of the piston ring clearance (6) and / or the cylinder liner heat map (19a; 19b).

8. The gap position measuring device according to any one of the preceding claims, wherein, The gap position measuring device (10) includes at least another set of sensors having at least one temperature sensor (22), preferably three temperature sensors (22), the at least another set of sensors being adapted to be arranged in the cylinder liner wall (3) and circumferentially spaced apart in another axial plane (23), wherein the first axial plane (12) and the other axial plane (23) are preferably arranged at an axial distance corresponding to the axial distance (24) between the first piston ring (5) and the other piston ring (25), and wherein 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 other piston ring based on temperature data (15A, 15B, 15C) from the first set of sensors and based on temperature data from the other set of sensors.

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

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

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

12. A method for operating an internal combustion engine (1), wherein the internal combustion engine (1) is preferably the internal combustion engine (1) according to claim 11, the method comprising the following steps: Temperature data (15A, 15B, 15C) are received from at least one measuring point (A, B, C) in a first group, preferably fewer than five measuring points, preferably three measuring points, located on or within the cylinder liner wall (3) of the cylinder (2), wherein the measuring points are preferably circumferentially spaced in a first axial plane (12, 23); and - The angular position (17) of the piston ring gap (6) relative to the cylinder (2) is determined based on the temperature data.

13. The method of claim 12, wherein in order to determine the angular position (17) of the piston ring clearance (6), the method includes at least one additional step, the at least one additional step being selected from the group consisting of the following steps: - Fit the fitted curve (16) to the temperature data (15A, 15B, 15C) and determine the angular position of the maximum value (18) of the fitted curve (16); and - Use the sequential Monte Carlo method.

14. The method according to any one of claims 12 to 13, wherein the method comprises the additional step of: - Receive the temperature data (15A, 15B, 15C) over time and determine the cylinder liner thermal map (19a; 19b) of the angular position (17) of the piston ring clearance (6); and - Preferably, signals and / or maintenance actions are issued based on the cylinder liner thermal diagrams (19a; 19b).

15. A computer program comprising instructions that, when executed by a computer of an internal combustion engine (1) according to claim 11, cause the computer to perform the method according to any one of claims 12 to 14.

Images