JP7752159B2 - Method for detecting abnormalities in an internal combustion engine - Google Patents

Description

The present invention relates to detecting abnormalities in internal combustion engines, and in particular to a method suitable for detecting abnormalities between piston rings and cylinder liners inside an internal combustion engine.

Abnormalities in piston rings and cylinder liners not only result in reduced power output, but can also lead to problems such as scuffing, which requires extensive repairs. For this reason, inspections have traditionally been carried out 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 and visually inspecting the upper surface of the cylinder liner.

However, when carrying out this type of inspection method, the engine must be stopped, meaning that if an abnormality occurs while the vessel is underway, it is not possible to detect it. For this reason, a method has been proposed in which the drain oil from the cylinder liner is analyzed while the vessel is in operation, and the occurrence of scuffing is detected from the iron concentration. While this method does not require the engine to be stopped, it takes time to collect a drain oil sample, and so it is possible that by the time an abnormality is detected, the cylinder liner or other part may already need to be replaced.

As a result, technologies such as those disclosed in Patent Documents 1 and 2 have been proposed as means of quickly detecting abnormalities such as scuffing. Specifically, the technology disclosed in Patent Document 1 detects abnormal waveforms contained in vibration signals during operation and detects the occurrence of scuffing based on these abnormal waveforms. Furthermore, the technology disclosed in Patent Document 2 detects gas temperature using a temperature detector installed near the scavenging port in the scavenging chamber and detects abnormalities such as scuffing based on changes in gas temperature.

It is true that the technologies disclosed in Patent Documents 1 and 2 are thought to enable early detection of abnormalities. However, regardless of which technology is adopted, the reality is that detection itself occurs after the abnormality has already occurred.

In response to this situation, technology such as that disclosed in Patent Document 3 has been proposed. The technology disclosed in Patent Document 3 involves placing a temperature sensor on the cylinder liner wall located at the top dead center of the piston and detecting temperature fluctuations due to friction, thereby detecting the condition before scuffing occurs. This type of technology makes it possible to detect abnormalities such as scuffing before they occur, allowing countermeasures to be taken.

However, in reality, it is difficult to distinguish between local temperature increases in the cylinder liner due to load fluctuations or combustion gas blow-through, making it difficult to determine whether an abnormality has occurred.

Japanese Unexamined Patent Publication No. 55-29054 JP 2010-7672 A JP 2011-169327 A

The present invention therefore aims to provide an abnormality detection method for an internal combustion engine that can determine whether or not a serious abnormality, such as scuffing, has occurred before it occurs, based on temperature changes that occur during steady-state operation.

To achieve the above-mentioned objective, 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 of 3 or greater) temperature detection means disposed on a cylinder liner in which the piston slides; and a piston ring having m (m is n-k (k is a positive number of 1 or greater) and m is a positive number of 2 or greater) peripheral grooves disposed on the piston; the n temperature detection means are arranged so that the central angle θ, which indicates the angle between adjacent temperature detection means and is based on the center of the cylinder liner, is similar; the m peripheral grooves are arranged so that when the piston ring is arranged so that one peripheral groove corresponds to one temperature detection means, each of the other peripheral grooves also has a corresponding temperature detection means; the internal combustion engine is determined to be normal if temperature changes detected by the temperature detection means during operation of the internal combustion engine occur substantially simultaneously in all m temperature detection means; and is determined to be abnormal if temperature changes detected by the temperature detection means occur in a number other than m.

Furthermore, in the internal combustion engine abnormality detection method having the above-described characteristics, the rotation direction of the piston ring can also be detected based on the order in which the temperature detection means cause the temperature change.

Furthermore, in the internal combustion engine abnormality detection method having the above-described 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, which has been checked in advance, with the rotational speed of the piston ring calculated based on the timing of detection of the temperature change. With these characteristics, it is possible to detect abnormalities before a serious abnormality due to piston sticking occurs.

The internal combustion engine abnormality detection method having the above-described characteristics makes it 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.

1 is a diagram showing an example of an internal combustion engine to which an abnormality detection method for an internal combustion engine of the present invention can be applied; FIG. 2 is a plan view showing an example of a piston ring that is applied to the internal combustion engine shown in FIG. 1 . 2 is a diagram showing an example of a planar arrangement of temperature detecting means in the internal combustion engine shown in FIG. 1 ; FIG. 4 is a graph showing the timing of temperature changes detected by three temperature detection means during normal operation and the rotation state of the piston rings. 10 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.

Embodiments of the internal combustion engine abnormality detection method of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below are merely some of the preferred forms for implementing the present invention, and even if some of the configuration or method is changed, they can be considered part of the present invention as long as the effects are achieved.

[composition]
First, referring to FIG. 1 , an example of an internal combustion engine (part of the internal combustion engine) to which the internal combustion engine abnormality detection method according to the present invention can be applied will be described. The 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, and 20, and a temperature detection means 22. The cylinder liner 12 is a component that allows the piston 14, which will be described in detail later, to slide and that constitutes a combustion chamber. The piston 14 slides along the inner wall of the cylinder liner 12 due to the action of a rod 14a, compressing gas within the combustion chamber. The piston rings 16, 18, and 20 are rings disposed on the outer surface of the piston 14. They fill the gap between the piston 14 and the cylinder liner 12 to increase airtightness and also serve as sliding members.

The cylinder liner 12 according to this embodiment is equipped with a temperature detection means 22. The temperature detection means 22 is positioned so that it can pinpoint the surface temperature of the cylinder liner 12 at the corresponding installation position. Specifically, as shown in FIG. 1, when the piston 14 reaches top dead center, the detection surface is located slightly below the piston ring 20 (if multiple piston rings are provided, below the lowest piston ring). Furthermore, n temperature detection means 22 (n is a positive number greater than or equal to 3) are arranged at the same height.

The spacing between n temperature detection means 22 (n = 3 in the example shown in Figure 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, which indicates the spacing angle between adjacent temperature detection means 22, is determined to be an approximate value. Here, "approximate" is intended to include a range of error based on the value obtained by dividing 360 degrees by n. This is because even when installing temperature detection means 22 with a target reference value, deviations can occur. The range of error differs depending on the diameter of the cylinder liner 12.

Furthermore, as shown in FIG. 1, multiple piston rings 16, 18, and 20 (three in the example shown in FIG. 1) according to this embodiment are provided along the thickness direction of the piston 14. Each piston ring 16, 18, and 20 has a gap 21 (see FIG. 2) in a portion thereof, which allows the piston rings 16, 18, and 20 to expand when fitted into a groove (not shown) provided in the piston 14.

The piston ring 16, which is placed at the tip of the piston 14, has peripheral grooves 16a and 16b in addition to the abutment 21. The peripheral grooves 16a and 16b are grooves that are provided in the thickness direction of the piston ring 16, and in the example embodiment, they are provided at an angle to the thickness direction.

Piston ring 16 is provided with multiple circumferential grooves 16a and 16b (two in the example shown in Figure 2). Here, if the number of circumferential grooves is m, m may be any number that satisfies the equation m = n - k. Here, n is the number of temperature detection means 22, and k is a positive number greater than or equal to 1. Furthermore, m is a positive number greater than or equal to 2. Furthermore, when piston ring 16 is positioned so that one circumferential groove (e.g., circumferential groove 16a) corresponds to one temperature detection means (e.g., temperature detection means 22A), the other circumferential grooves (e.g., circumferential groove 16b) also have corresponding temperature detection means (e.g., temperature detection means 22B). Circumferential grooves 16a and 16b allow a portion of the combustion gas generated in the combustion chamber during gas compression to escape below piston ring 16, thereby reducing the load on piston ring 16.

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

The outer circumferential grooves 16a and 16b on the piston ring 16 allow some of the combustion gas generated in the combustion chamber to escape into 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 and 16b, forms part of the passage through which the high-temperature combustion gas passes, and therefore tends to be hotter than other areas.

In this embodiment, the temperature detection means 22 detects temperature changes associated with the presence of the peripheral grooves 16a and 16b, thereby determining whether or not an abnormality (minor abnormality) that could lead to the occurrence of scuffing or the like has occurred.

For example, as shown in Figures 2 and 3, if the piston ring 16 has two circumferential grooves (circumferential grooves 16a and 16b), the cylinder liner 12 has three temperature detection means (temperature detection means 22A, 22B, and 22C), and the central angle (arrangement angle) θ is approximately 120 degrees, and the internal combustion engine 10 is operating normally and no abnormalities have occurred in the cylinder liner 12 or piston ring 16, the temperature detection means 22 (22A, 22B, and 22C) will exhibit the detection pattern shown in Figure 4. In Figures 4 and 5, the rotational state of the piston ring 16 (position of the circumferential grooves 16a and 16b) is schematically shown in the upper part of the temperature detection graph.

When the piston rings 16 rotate as the internal combustion engine 10 operates, the peripheral grooves 16a, 16b move closer to the temperature detection means 22 (22A, 22B, 22C). As described above, this causes the wall temperature of the cylinder liner 12, located opposite the peripheral grooves 16a, 16b, to rise. 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 peaks when the positions of the temperature detection means 22 and the peripheral grooves 16a, 16b are aligned, and then gradually drops as the positional relationship between the two shifts.

As described above, the arrangement angle (central angle θ) of the outer circumferential grooves 16a, 16b provided on the piston ring 16 matches the arrangement angle (central angle θ) of the temperature detection means 22A, 22B, 22C provided on the cylinder liner 12. Therefore, in this embodiment, when the internal combustion engine 10 is normal, a temperature change will be detected simultaneously by the two temperature detection means (any combination of 22A and 22B, 22B and 22C, or 22C and 22A).

For example, in the example shown in Figure 4, at time ta, temperature changes are detected by temperature detection means 22A and temperature detection means 22C. At this time, assume that circumferential groove 16a is located at the position of temperature detection means 22A, and circumferential groove 16b is located at the position of temperature detection means 22C. Under these operating conditions, when piston ring 16 rotates in the direction of arrow A, temperature changes are detected by temperature detection means 22A and temperature detection means 22B at time tb. At this time, circumferential groove 16b is located at the position of temperature detection means 22A, and circumferential groove 16a is located at the position of temperature detection means 22B. Similarly, as internal combustion engine 10 continues to operate, piston ring 16 rotates (in the direction of arrow A), and circumferential groove 16a approaches the position of temperature detection means 22C (time tc), circumferential groove 16b approaches temperature detection means 22B. As a result, temperature changes are detected by temperature detection means 22B and 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 temperature detection means 22C, just as at time ta.

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

In contrast, when the temperature change detection rules change, as shown in Figure 5, such as when a single temperature detection means 22B detects a temperature change (time ta1) or when more temperature detection means 22 (22A, 22B, 22C) than the number of peripheral grooves 16a, 16b detect a temperature change (time tc), it is suspected that a combustion gas blow-by or other problem is occurring due to a factor other than the peripheral grooves 16a, 16b. Therefore, 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 could lead to a serious abnormality such as scuffing.

[effect]
In this way, the internal combustion engine abnormality detection method according to the present invention makes it 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.

[Application example]
Furthermore, according to the above-described method for detecting an abnormality in an internal combustion engine, the rotational direction of the piston ring 16 can be determined from the order in which the temperature detecting means 22A, 22B, and 22C detect the outer circumferential grooves 16a and 16b. Furthermore, it is also possible to calculate the rotational 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 detecting means 22A, 22B, and 22C. By previously determining the rotational speed of the piston ring 16 during normal operation, it is possible to detect whether the piston ring 16 is stuck or not based on the change in the rotational speed of the piston ring 16 obtained by comparing the two values.

10...Internal combustion engine, 12...Cylinder liner, 14...Piston, 14a...Rod, 16, 18, 20...Piston rings, 16a, 16b...Peripheral groove, 21...Abutment, 22 (22A, 22B, 22C)...Temperature detection means.

Claims (3)

An internal combustion engine having a piston, n (n is a positive number of 3 or more) temperature detecting means arranged in a cylinder liner in which the piston slides, and m (m is n-k (k is a positive number of 1 or more) and m is a positive number of 2 or more) piston rings each having an outer circumferential groove arranged on the piston,
The n temperature detection means are arranged so that the 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 number of the circumferential grooves are arranged such that when the piston ring is arranged so that one circumferential groove corresponds to one temperature detecting means, each of the other circumferential grooves also has a corresponding temperature detecting means;
a temperature detecting means for detecting an abnormality in an internal combustion engine, the temperature detecting means detecting temperature changes during operation of the internal combustion engine being determined to be normal if the temperature changes occur substantially simultaneously in m number of the temperature detecting means, and the temperature detecting means detecting temperature changes occurring in a number other than m number of the temperature detecting means being determined to be abnormal. The method for detecting an abnormality in an internal combustion engine described in claim 1, characterized in that the rotation direction of the piston ring is detected based on the order in which the temperature detection means cause the temperature change. calculating a rotational speed of the piston ring based on the central angle θ and the 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, wherein the rotational speed of the piston ring calculated based on the detection timing of the temperature change is compared with the rotational speed of the piston ring under normal conditions that has been checked in advance to determine whether the piston ring is stuck.