Method of detecting abnormality in internal combustion engine

Abstract

To provide a method of detecting an abnormality in an internal combustion engine, which can determine the presence or absence of the occurrence of the abnormality before a serious abnormality occurs.SOLUTION: An internal combustion engine 10 includes: n temperature detection means 22 arranged in a cylinder liner 12; and a piston ring 16 having m outer peripheral grooves. The n temperature detection means 22 are arranged so that center angles θ indicating arrangement angles become respective approximate values. When the piston ring 16 is arranged so that one outer peripheral groove 16a is positioned corresponding to one temperature detection means 22A in the m outer peripheral grooves, the piston ring is arranged so that temperature detection means 22B corresponding to other outer peripheral groove 16b exists. The normality or abnormality of an operation state is determined by the number of the temperature detection means 22 in which a temperature change detected during an operation of the internal combustion engine 10 is generated.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an abnormality detection in an internal combustion engine, and more particularly to a method suitable for detecting an abnormality between a piston ring and a cylinder liner inside an internal combustion engine. [Background technology]

[0002] Abnormalities in piston rings and cylinder liners not only reduce power output, but can also cause problems such as scuffing that require extensive repairs. For this reason, inspections have traditionally been conducted by stopping the engine and visually checking the condition of the piston rings and the lower surface of the cylinder liner, or by inserting a camera into the cylinder to visually check the upper surface of the cylinder liner.

[0003] However, when carrying out such an inspection method, it is necessary to stop the engine, and it is not possible to know if an abnormality occurs during navigation. For this reason, a method has been proposed in which the drain oil from the cylinder liner during operation is analyzed and the occurrence of scuffing is detected from the iron concentration. Although this method does not require stopping the engine, it takes time to collect a drain oil sample, and there is a possibility that by the time an abnormality is detected, it may be necessary to replace the cylinder liner, etc.

[0004] Therefore, as a means for realizing early detection of anomalies such as scuffing, techniques such as those disclosed in Patent Document 1 and Patent Document 2 have been proposed. Specifically, the technique disclosed in Patent Document 1 detects an abnormal waveform contained in a vibration signal during operation and detects the occurrence of scuffing based on this abnormal waveform. In addition, the technique disclosed in Patent Document 2 detects the gas temperature using a temperature detector provided near the scavenging port in the scavenging chamber and detects anomalies such as scuffing based on a change in the gas temperature.

[0005] It is true that the techniques disclosed in Patent Documents 1 and 2 are believed to enable early detection of an abnormality. However, in reality, no matter which technique is used, the detection itself occurs after the abnormality has occurred.

[0006] In response to this situation, a technology such as that disclosed in Patent Document 3 has been proposed. The technology disclosed in Patent Document 3 involves arranging a temperature sensor on the cylinder liner wall located at the top dead center of the piston, and detecting temperature fluctuations due to friction to detect the condition before scuffing occurs. With this technology, it is possible to detect abnormalities such as scuffing before they occur, making it possible to take measures.

[0007] In reality, however, it is difficult to distinguish between local temperature increases in the cylinder liner caused by load fluctuations or the blow-through of combustion gases, making it difficult to determine whether there is an abnormality. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 55-29054 [Patent Document 2] JP 2010-7672 A [Patent Document 3] JP 2011-169327 A Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, an object of the present invention is to provide an abnormality detection method for an internal combustion engine that can determine whether or not an abnormality has occurred before a serious abnormality such as scuffing occurs, based on temperature changes that occur during steady-state operation. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the present invention provides an internal combustion engine abnormality detection method, comprising: an internal combustion engine having a piston, n (n is a positive number equal to or greater than 3) temperature detection means arranged on a cylinder liner in which the piston slides; and a piston ring having m (m is nk (k is a positive number equal to or greater than 1) and m is a positive number equal to or greater than 2) outer circumferential grooves arranged on the piston; the n temperature detection means are arranged such that central angles θ, which indicate the arrangement angles between adjacent temperature detection means and are based on the center of the cylinder liner, are approximate to each other; the m outer circumferential grooves are arranged such that when the piston ring is arranged so that one outer circumferential groove corresponds to one temperature detection means, each of the other outer circumferential grooves has a corresponding temperature detection means; the internal combustion engine is judged to be normal when temperature changes detected by the temperature detection means occur almost simultaneously in m of the temperature detection means during operation of the internal combustion engine; and is judged to be abnormal when temperature changes detected by the temperature detection means occur in a number other than m of the temperature detection means.

[0011] In the method for detecting an abnormality in an internal combustion engine having the above-mentioned features, the rotation direction of the piston ring can also be detected based on the order in which the temperature change occurs in the temperature detection means.

[0012] Furthermore, in the method for detecting an abnormality in an internal combustion engine having the above-mentioned characteristics, the rotational speed of the piston ring can be calculated based on the central angle θ and the timing of detection of the temperature change by the temperature detection means, and the presence or absence of sticking of the piston ring can be determined by comparing the rotational speed of the piston ring under normal conditions that has been checked in advance with the rotational speed of the piston ring calculated based on the detection timing of the temperature change. With such characteristics, it is possible to detect an abnormality before a serious abnormality due to sticking of the piston occurs. Effect of the Invention

[0013] According to the method for detecting an abnormality in an internal combustion engine having the characteristics described above, it is possible to easily and reliably detect temperature changes that occur before a serious abnormality occurs, and to determine whether or not an abnormality has occurred before a serious abnormality such as scuffing occurs. [Brief description of the drawings]

[0014] [Figure 1] 1 is a diagram showing an example of an internal combustion engine in which a method for detecting an abnormality in an internal combustion engine according to the present invention can be implemented; [Diagram 2] FIG. 2 is a plan view showing an example of a piston ring that is applied to the internal combustion engine shown in FIG. [Diagram 3] 2 is a diagram showing an example of a planar arrangement of temperature detecting means in the internal combustion engine shown in FIG. 1. [Figure 4] 4 is a graph showing the timing of temperature changes detected by three temperature detection means during normal operation and the rotation state of a piston ring. [Diagram 5] 4 is an example of a graph showing the timing of temperature changes detected by three temperature detection means during abnormal operation and the rotation state of a piston ring. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the method for detecting an abnormality in an internal combustion engine according to the present invention will be described in detail with reference to the drawings. Note that the embodiment shown below is merely a part of a preferred embodiment for carrying out the present invention, and even if a part of the configuration or method is changed, it can be considered as a part of the present invention as long as the effect is achieved.

[0016] [composition] First, referring to Fig. 1, an example of an internal combustion engine (part of the internal combustion engine is shown) to which the method for detecting an abnormality in an internal combustion engine according to the present invention can be applied will be described. An internal combustion engine 10 to which the present invention can be applied is basically composed of a cylinder liner 12, a piston 14, piston rings 16, 18, 20, and a temperature detection means 22. The cylinder liner 12 is an element that slides the piston 14, which will be described in detail later, and that constitutes a combustion chamber. The piston 14 is an element that slides along the inner wall of the cylinder liner 12 by the action of a rod 14a and compresses the gas in the combustion chamber. The piston rings 16, 18, 20 are rings that are arranged on the outer surface of the piston 14, and are elements that fill the gap between the piston 14 and the cylinder liner 12 to increase airtightness and also play a role as sliding members.

[0017] The cylinder liner 12 according to this embodiment is provided with a temperature detection means 22. The temperature detection means 22 is arranged so as to be able to pinpoint the surface temperature of the cylinder liner 12 at the corresponding installation position. Specifically, as shown in Fig. 1, the temperature detection means 22 is arranged so that when the piston 14 reaches the top dead center, a portion slightly below the piston ring 20 (if multiple piston rings are provided, below the lowest piston ring) becomes the detection surface. In addition, n temperature detection means 22 (n is a positive number of 3 or more) are arranged at the same height.

[0018] The arrangement interval of the n temperature detection means 22 (n=3 in the example shown in FIG. 3: temperature detection means 22A to 22C) is determined by the central angle θ with the center of the cylinder liner 12 as the base point. Specifically, the central angle θ indicating the arrangement angle between adjacent temperature detection means 22 is determined to be an approximate value. Here, approximation is intended to include a range of error based on the value obtained by dividing 360 degrees by n. This is because even when the temperature detection means 22 are attached with a reference value as a target, deviations may occur. Here, the range of error differs depending on the diameter of the cylinder liner 12.

[0019] As shown in Fig. 1, a plurality of piston rings 16, 18, 20 according to this embodiment (three in the example shown in Fig. 1) are provided along the thickness direction of the piston 14. Each of the piston rings 16, 18, 20 has a joint 21 (see Fig. 2) in a part thereof, and is configured so that the piston rings 16, 18, 20 can be expanded when fitted into a groove (not shown) provided in the piston 14.

[0020] Furthermore, the piston ring 16 disposed at the tip of the piston 14 is provided with outer circumferential grooves 16a, 16b in addition to the abutment 21. The outer circumferential grooves 16a, 16b are grooves provided in the thickness direction of the piston ring 16, and in the example according to the embodiment, are provided obliquely so as to have an inclination angle with respect to the thickness direction.

[0021] A plurality of the outer circumferential grooves 16a and 16b (two in the example shown in FIG. 2) are provided on the circumference of the piston ring 16. Here, when the number of the outer circumferential grooves is m, m may be any number that satisfies m=nk. Here, n is the number of the temperature detection means 22, and k is a positive number equal to or greater than 1. Moreover, m is a positive number equal to or greater than 2. Moreover, the m outer circumferential grooves are arranged so that when the piston ring 16 is arranged so that one outer circumferential groove (e.g., the outer circumferential groove 16a) corresponds to one temperature detection means (e.g., the temperature detection means 22A), the other outer circumferential grooves (e.g., the outer circumferential groove 16b) also have corresponding temperature detection means (e.g., the temperature detection means 22B). The outer circumferential grooves 16a and 16b play a role in releasing a part of the combustion gas generated in the combustion chamber during gas compression to the lower side of the piston ring 16, thereby reducing the load on the piston ring 16.

[0022] [Example] In the internal combustion engine 10 configured as described above, the piston rings 16, 18, 20 generally rotate in the circumferential direction due to the operation of the piston 14 accompanied by combustion. The rotational speed of the piston rings 16, 18, 20 depends on the rotational speed of the crankshaft (not shown) in the internal combustion engine 10, but is generally one rotation per several tens of minutes. For this reason, assuming that the piston ring 16 rotates at a constant speed, the abutment 21 and outer peripheral grooves 16a, 16b of the piston ring 16 will repeatedly slide along the cylinder liner at the same position (angle) for a certain period of time.

[0023] The outer circumferential grooves 16a, 16b provided in the piston ring 16 serve to allow a portion of the combustion gas generated in the combustion chamber to escape to the space between the piston ring 16 and the piston ring 18. The inner wall of the cylinder liner 12 located opposite the outer circumferential grooves 16a, 16b constitutes a portion of the passage through which the high-temperature combustion gas passes, and therefore tends to become hotter than other portions.

[0024] In this embodiment, the temperature detection means 22 detects a temperature change caused by the presence of the outer circumferential grooves 16a, 16b, thereby determining whether or not an abnormality (minor abnormality) that may lead to the occurrence of scuffing or the like has occurred.

[0025] For example, as shown in Figures 2 and 3, when the piston ring 16 has two outer circumferential grooves (outer circumferential grooves 16a, 16b), the cylinder liner 12 has three temperature detection means (temperature detection means 22A, 22B, 22C), and the central angle (arrangement angle) θ≈120 degrees, if the internal combustion engine 10 is operated normally and no abnormality occurs in the cylinder liner 12 or the piston ring 16, the temperature detection means 22 (22A, 22B, 22C) will show a detection pattern as shown in Figure 4. In Figures 4 and 5, the rotation state of the piston ring 16 (positions of the outer circumferential grooves 16a, 16b) is shown in the upper part of the temperature detection graph.

[0026] When the piston ring 16 rotates as the internal combustion engine 10 operates, the peripheral grooves 16a, 16b move closer to the temperature detection means 22 (22A, 22B, 22C), and as described above, the wall temperature of the cylinder liner 12 located opposite the peripheral grooves 16a, 16b also rises. Therefore, the temperature detected by the temperature detection means 22 to which the peripheral grooves 16a, 16b are approaching gradually rises. The temperature detected by the temperature detection means 22 reaches a peak when the positions of the temperature detection means 22 and the peripheral grooves 16a, 16b coincide, and then gradually drops as the positional relationship between the two shifts.

[0027] As described above, the arrangement angle (central angle θ) of the outer circumferential grooves 16a, 16b provided in the piston ring 16 coincides with the arrangement angle (central angle θ) of the temperature detection means 22A, 22B, 22C provided in the cylinder liner 12. Therefore, in this embodiment, when the internal combustion engine 10 is normal, a temperature change is detected at the same time by two temperature detection means (any combination of 22A and 22B, 22B and 22C, or 22C and 22A).

[0028] For example, in the example shown in FIG. 4, at time ta, the temperature detection means 22A and the temperature detection means 22C detect a temperature change. At this time, the outer circumferential groove 16a is located at the position of the temperature detection means 22A, and the outer circumferential groove 16b is located at the position of the temperature detection means 22C. In this operating state, when the piston ring 16 rotates in the direction of the arrow A, at time tb, the temperature change is detected by the temperature detection means 22A and the temperature detection means 22B. At this time, the outer circumferential groove 16b is located at the position of the temperature detection means 22A, and the outer circumferential groove 16a is located at the position of the temperature detection means 22B. Similarly, when the operation of the internal combustion engine 10 continues, the piston ring 16 rotates (in the direction of the arrow A), and the outer circumferential groove 16a approaches the position of the temperature detection means 22C (at time tc), the outer circumferential groove 16b approaches the position of the temperature detection means 22B. As a result, the temperature change is detected by the temperature detection means 22B and the temperature detection means 22C. Furthermore, at time td, the outer circumferential groove 16a returns to the position of the temperature detection means 22A, the piston ring 16 completes one rotation, and the temperature change is detected by the temperature detection means 22A and the temperature detection means 22C, just as at time ta.

[0029] In this way, when the number of outer circumferential grooves provided on the piston ring 16 (in this embodiment, two, circumferential grooves 16a and 16b) matches the number and timing of the temperature detection means 22 that detects temperature changes, it can be determined that the piston ring 16 is rotating normally and that no abnormality has occurred in either the piston ring 16 itself or the cylinder liner 12 (= normal).

[0030] In contrast, when the temperature change detection rule changes, such as when a single temperature detection means 22B detects a temperature change (time ta1) or when a temperature change is detected by more temperature detection means 22 (22A, 22B, 22C) than the number of outer circumferential grooves 16a, 16b (time tc) as shown in Fig. 5, it is suspected that a combustion gas blow-through or the like is occurring due to a factor other than the outer circumferential grooves 16a, 16b. For this reason, it can be determined that an abnormality has occurred in the movement of the piston ring 16 or in the piston ring 16 itself in the internal combustion engine 10, and that continued operation may progress to a serious abnormality such as scuffing.

[0031] [effect] In this way, according to the internal combustion engine abnormality detection method of the present invention, it is possible to easily and reliably detect temperature changes that may occur before a serious abnormality occurs, and to determine whether or not an abnormality exists before a serious abnormality such as scuffing occurs.

[0032] [Application example] Moreover, according to the above-mentioned method for detecting an abnormality in an internal combustion engine, the rotation direction of the piston ring 16 can be known from the order in which the temperature detection means 22A, 22B, and 22C detect the outer circumferential grooves 16a and 16b. Furthermore, it is also possible to calculate the rotation speed (angular velocity) of the piston ring 16 based on the arrangement angle (central angle θ) of the outer circumferential grooves 16a and 16b and the detection timing (elapsed time) by the temperature detection means 22A, 22B, and 22C. Then, by investigating in advance the rotation speed of the piston ring 16 during normal operation, it is also possible to detect the presence or absence of sticking of the piston ring 16 based on the change in the rotation speed of the piston ring 16 obtained by comparing the two. [Explanation of symbols]

[0033] 10... internal combustion engine, 12... cylinder liner, 14... piston, 14a... rod, 16, 18, 20... piston rings, 16a, 16b... outer peripheral groove, 21... joint, 22 (22A, 22B, 22C)... temperature detection means.

Claims

1. An internal combustion engine having a piston, n temperature detection means (n ​​is a positive number of 3 or more) arranged on a cylinder liner in which the piston slides, and m piston rings (m is n-k (k is a positive number of 1 or more) and m is a positive number of 2 or more) having outer circumferential grooves arranged on the piston, The n temperature detection means are arranged such that the central angles θ, which indicate the arrangement angles between the adjacent temperature detection means and are based on the center of the cylinder liner, are approximate to each other; the m number of the peripheral grooves are arranged such that when the piston ring is arranged such that one peripheral groove corresponds to one temperature detection means, each of the other peripheral grooves also has a corresponding temperature detection means; a temperature detection means for detecting an abnormality in an internal combustion engine, the temperature detection means being determined to be normal when temperature changes detected by the temperature detection means during operation of the internal combustion engine occur substantially simultaneously in m number of the temperature detection means, and the temperature detection means being determined to be abnormal when temperature changes detected by the temperature detection means occur in a number other than m number of the temperature detection means.

2. 2. The method for detecting an abnormality in an internal combustion engine according to claim 1, wherein the rotation direction of the piston ring is detected based on an order of the temperature detection means in which the temperature change occurs.

3. calculating a rotational speed of the piston ring based on the central angle θ and a detection timing of the temperature change by the temperature detection means; 2. The method for detecting an abnormality in an internal combustion engine according to claim 1, further comprising the step of comparing a rotational speed of the piston ring under normal conditions, which has been checked in advance, with the rotational speed of the piston ring calculated based on the detection timing of the temperature change, to determine whether the piston ring is stuck.

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