CN216077343U

CN216077343U - Heat insulation ring for cylinder sleeve and internal combustion engine

Info

Publication number: CN216077343U
Application number: CN202121983400.0U
Authority: CN
Inventors: 畠山公一; 奥山浩二; 黑政勇气
Original assignee: TPR Co Ltd; TPR Industry Co Ltd
Current assignee: TPR Co Ltd; TPR Industry Co Ltd
Priority date: 2020-08-25
Filing date: 2021-08-23
Publication date: 2022-03-18
Anticipated expiration: 2031-08-23
Also published as: CN114109639A; JPWO2022044986A1; CN114109639B; JP2022141676A; WO2022044986A1; JP7157262B2

Abstract

The utility model provides a heat insulating ring for a cylinder liner and an internal combustion engine using the same, which are not easy to generate damage from a groove part for forming a heat insulating air layer; in the heat insulating ring (10) for a cylinder liner and an internal combustion engine (200) using the heat insulating ring (10), the cross-sectional shape of a groove portion (34) provided on the outer peripheral surface (30) of an annular member (20) constituting the heat insulating ring (10) is: the cross-sectional shape is selected from any one or more of (1) a first cross-sectional shape having a V-shape, (2) a second cross-sectional shape in which the vicinity of a corner portion of the first cross-sectional shape is rounded to form a curve, (3) a third cross-sectional shape formed only by a curved line having a circular arc shape, and (4) a fourth cross-sectional shape having a U-shape.

Description

Heat insulation ring for cylinder sleeve and internal combustion engine

Technical Field

The utility model relates to a heat insulation ring for a cylinder sleeve and an internal combustion engine.

Background

Known are: in order to reduce heat loss of the internal combustion engine, a heat insulating ring is provided on an inner peripheral surface of the cylinder liner in the vicinity of a combustion chamber side end portion (see, for example, patent documents 1 and 2). In the conventional heat insulating rings as exemplified in patent documents 1 and 2, a groove portion having a square cross-sectional shape in a cross-section perpendicular to the circumferential direction is provided on the outer circumferential surface of the heat insulating ring in order to form an air layer for heat insulation.

[ Prior art documents ]

[ patent document ]

Patent document 1: japanese patent, examined Japanese patent publication No. 05-12527

Patent document 2: japanese patent, Japanese laid-open No. 2007-32401

SUMMERY OF THE UTILITY MODEL

(problem to be solved by the utility model)

However, in the conventional heat insulating ring having the groove portion for forming the heat insulating air layer, there is a case where damage is generated from the groove portion by using the heat insulating ring in an internal combustion engine.

The present invention has been made in view of the above circumstances, and an object thereof is to provide: a heat insulating ring for a cylinder liner, which is less likely to cause damage due to a groove portion, and an internal combustion engine using the same.

(means for solving the problems)

The above object is achieved by the following invention. That is to say that the first and second electrodes,

the heat insulating ring for a cylinder liner of the present invention has the following features.

The heat insulating ring for a cylinder liner comprises an annular member, wherein in a cross section of the annular member perpendicular to a circumferential direction, an outer peripheral surface of the annular member comprises a flat portion parallel to an axial direction of the annular member and a groove portion recessed toward an inner peripheral side of the annular member more than the flat portion, and a cross-sectional shape of the groove portion is any one or more cross-sectional shapes selected from the group consisting of the following cross-sectional shapes (1) to (4):

(1) a V-shaped first cross-sectional shape formed by only two straight lines and one corner portion which is an intersection of the two straight lines,

(2) a second cross-sectional shape formed by rounding the vicinity of the corner in the first cross-sectional shape to a curve,

(3) a third cross-sectional shape formed only by a curved line in the shape of a circular arc,

(4) a fourth cross-sectional shape of a U-shape.

In one embodiment of the heat insulating ring for a cylinder liner according to the present invention, it is preferable that: in the first cross-sectional shape and the second cross-sectional shape, an angle formed by two straight lines is 45 degrees to 160 degrees.

In another embodiment of the heat insulating ring for a cylinder liner according to the present invention, it is preferable that: satisfies the following formula (1),

formula (1): 0.85 is more than or equal to Sr/(Dr multiplied by Wr) is more than or equal to 0.5;

in the above equation (1), Sr represents a cross-sectional area (#) of the groove portion in a cross-section perpendicular to the circumferential direction of the annular member²) Dr denotes a maximum groove depth (#) of the groove portion, and Wr denotes a maximum opening width (#) of the groove portion in the axial direction of the annular member.

In another embodiment of the heat insulating ring for a cylinder liner according to the present invention, it is preferable that: satisfies the following equation (2),

equation (2): 0.41 is more than or equal to Dr/Wr;

in the above equation (2), Dr represents the maximum groove depth (mm) of the groove portion, and Wr represents the maximum opening width (mm) of the groove portion in the axial direction of the annular member.

In another embodiment of the heat insulating ring for a cylinder liner according to the present invention, it is preferable that: satisfies the following equation (3),

equation (3): 0.57 is more than or equal to Dr/Tr;

in the above equation (3), Dr represents the maximum groove depth (mmm) of the groove portion, and Tr represents the radial thickness (mmm) of the annular member.

In another embodiment of the heat insulating ring for a cylinder liner according to the present invention, it is preferable that: satisfies the following equation (4),

equation (4): 0.55 is more than or equal to Fr/Hr;

in the above equation (4), Fr represents a length (mm) of the flat portion in the axial direction of the annular member, and Hr represents an axial height (mm) of the annular member.

In another embodiment of the heat insulating ring for a cylinder liner according to the present invention, it is preferable that: the annular member has an inner diameter of 84 mm to 247 mm, a radial thickness Tr of 1.5 mm to 8.0 mm, and an axial height Hr of 5.0 mm to 70.0 mm.

In another embodiment of the heat insulating ring for a cylinder liner according to the present invention, it is preferable that: the heat insulation ring for the cylinder liner is a carbon deposition scraping ring.

The internal combustion engine of the present invention has the following features.

The internal combustion engine is provided with at least: a cylinder liner having a cylindrical member, an inner peripheral surface of the cylindrical member being configured by a first region near one end side and a second region other than near one end side of the cylindrical member in an axial direction, an inner diameter of the first region being larger than an inner diameter of the second region; and a heat insulating ring which has an annular member and is fitted in the first region of the cylinder liner.

In a cross section of the annular member perpendicular to the circumferential direction, the outer circumferential surface of the annular member includes a flat portion parallel to the axial direction of the annular member and a groove portion recessed further toward the inner circumferential side of the annular member than the flat portion.

The cross-sectional shape of the groove is any one or more cross-sectional shapes selected from the group consisting of the following cross-sectional shapes (1) to (4):

(4) a fourth cross-sectional shape of a U-shape.

In one embodiment of the internal combustion engine of the present invention, it is preferable that: the annular member has an inner diameter smaller than an inner diameter of the second region.

In another embodiment of the internal combustion engine of the present invention, it is preferable that: the internal combustion engine is a diesel engine.

(effects of utility model)

According to the present invention, there can be provided: a heat insulating ring for a cylinder liner, which is less likely to cause damage due to a groove portion, and an internal combustion engine using the same.

Drawings

Fig. 1 is a schematic sectional view showing an example of the heat insulating ring for a cylinder liner according to the present embodiment and an example of an internal combustion engine according to the present embodiment.

Fig. 2 is a schematic sectional view showing another example of the heat insulating ring for a cylinder liner according to the present embodiment and another example of the internal combustion engine according to the present embodiment.

Fig. 3 is a schematic sectional view showing still another example of the heat insulating ring for a cylinder liner according to the present embodiment and still another example of the internal combustion engine according to the present embodiment.

Fig. 4 is a schematic sectional view showing still another example of the heat insulating ring for a cylinder liner according to the present embodiment and still another example of the internal combustion engine according to the present embodiment.

Fig. 5 is a diagram showing an example of a result of simulation analysis of a stress distribution and a temperature distribution in a conventional heat insulating ring for a cylinder liner provided with a groove portion having a square cross section.

Fig. 5 (a) is a cross-sectional view showing a cross-sectional shape of an insulating ring used for simulation analysis, fig. 5 (B) is a view showing temperature distributions of the insulating ring and a cylinder liner shown in fig. 5 (a), and fig. 5 (C) is a view showing a stress distribution of the insulating ring shown in fig. 5 (a).

Fig. 6 is a diagram showing an example of the results of simulation analysis of the stress distribution and the temperature distribution in the heat insulating ring for a cylinder liner according to the present embodiment.

Fig. 6 (a) is a cross-sectional view showing a cross-sectional shape of an insulating ring used for simulation analysis, fig. 6 (B) is a view showing temperature distributions of the insulating ring and the cylinder liner shown in fig. 6 (a), and fig. 6 (C) is a view showing a stress distribution of the insulating ring shown in fig. 6 (a).

Fig. 7 is a diagram showing an example of the result of a simulation analysis of the temperature distribution in the heat insulating ring provided with no groove portion.

Fig. 7 (a) is a cross-sectional view showing a cross-sectional shape of an insulating ring used for simulation analysis, and fig. 7 (B) is a view showing temperature distributions of the insulating ring and the cylinder liner shown in fig. 7 (a).

Fig. 8 is an enlarged cross-sectional view showing an example of a groove portion having a first cross-sectional shape.

Fig. 9 is an enlarged cross-sectional view showing an example of a groove portion having a second cross-sectional shape.

Fig. 10 is an enlarged cross-sectional view showing an example of a groove portion having a third cross-sectional shape.

Fig. 10 (a) is a diagram showing a case where the cross-sectional shape of the groove portion is formed in a semicircular arc, and fig. 10 (B) is a diagram showing a case where the cross-sectional shape of the groove portion is formed in an arc that is curved more gently than the semicircular arc.

Fig. 11 is an enlarged cross-sectional view showing an example of a groove portion having a fourth cross-sectional shape.

Fig. 12 is a schematic sectional view showing another example of the heat insulating ring for a cylinder liner according to the present embodiment and another example of the internal combustion engine according to the present embodiment.

(symbol description)

10. 10A, 10B, 10C, 10D, 10E: heat insulation ring

12: heat insulation ring

14: heat insulation ring

20: ring-shaped member

30: peripheral surface

32: flat part

34. 34A, 34B, 34C, 34D: trough part

36: trough part

36B: bottom surface of the groove

36C: corner part

38: notch part (chamfered part)

40A, 40B: straight line

42: corner part

44: curve line

50. 50A, 50B: circular arc

52: straight line

60: inner peripheral surface

102: cylinder liner

120: cylindrical member

130: inner peripheral surface

130A: first region (inner peripheral surface near the side end of combustion chamber)

130B: second region

200. 200A, 200D: internal combustion engine

300: piston

310: top bank

400: carbon deposit

Detailed Description

< Heat insulation Ring for Cylinder liner >

Fig. 1 to 4 are schematic sectional views showing an example of an insulating ring for a cylinder liner (hereinafter, simply referred to as an insulating ring) according to the present embodiment, and are views showing a structure of a cross section of the insulating ring perpendicular to a circumferential direction. Fig. 1 to 4 show a state in which the heat insulating ring is attached to the inner peripheral surface of the cylinder liner in the vicinity of the combustion chamber side end portion. The Y direction shown in fig. 1 to 4 and other drawings is a direction parallel to the axial direction of the heat insulating ring and the cylinder liner, and the X direction perpendicular to the Y direction is a direction parallel to the radial direction of the heat insulating ring and the cylinder liner.

The heat insulating ring 10 shown in fig. 1 to 4 has an annular member 20, and in a cross section (paper surface in the drawing) of the annular member 20 perpendicular to the circumferential direction, an outer circumferential surface 30 of the annular member 20 includes: a flat portion 32 parallel to the axial direction of the annular member 20, and a groove portion 34 recessed toward the inner circumferential side of the annular member 20 more than the flat portion 32.

In the example shown in fig. 1 to 4, the heat insulating ring 10 is attached to the inner peripheral surface 130A (first region) near the combustion chamber side end of the cylinder liner 102. Therefore, the flat portion 32 in the outer peripheral surface 30 is in contact with the inner peripheral surface 130A of the cylinder liner 102. In the example shown in fig. 1 to 4, two groove portions 34 and three flat portions 32 are provided, and one groove portion 34 is located between the two flat portions 32. Further, in the example shown in fig. 1 to 4, notches (chamfered portions) 38 are further provided on both axial end sides of the outer peripheral surface 30. However, the notch (chamfered portion) 38 may be omitted. The groove 34 is preferably provided continuously in the circumferential direction of the heat insulating ring 10, but may be provided discontinuously. In the case where the groove portion 34 is provided continuously in the circumferential direction of the heat insulating ring 10, the groove portion 34 may be provided continuously so as to be parallel to the circumferential direction, or may be provided continuously so that the groove portion 34 intersects the circumferential direction to form a predetermined angle (for example, an angle exceeding 0 degrees and 30 degrees or less).

Here, the groove 34A (34) having a V-shaped cross-sectional shape (first cross-sectional shape) formed by only one corner portion which is an intersection of two straight lines and two straight lines is provided on the outer peripheral surface 30 of the heat insulating ring 10A (10) shown in fig. 1, and the groove 34B (34) having a cross-sectional shape (second cross-sectional shape) which is formed by rounding the vicinity of the corner portion in the first cross-sectional shape into a curved line is provided on the outer peripheral surface 30 of the heat insulating ring 10B (10) shown in fig. 2.

Further, the groove portion 34C (34) is provided on the outer peripheral surface 30 of the heat insulating ring 10C (10) shown in fig. 3, the groove portion 34C (34) has a sectional shape (third sectional shape) formed only by a curved line in an arc shape, and the groove portion 34D (34) is provided on the outer peripheral surface 30 of the heat insulating ring 10D (10) shown in fig. 4, and the groove portion 34D (34) has a U-shaped sectional shape (fourth sectional shape). In the insulating ring 10 shown in fig. 1 to 4, the groove portions 34 are arranged at predetermined intervals (Fr2) in the axial direction of the annular member 20. However, the following configuration is also possible: the plurality of groove portions 34 are arranged in a zigzag shape by minimizing the interval (Fr2) between two axially adjacent groove portions 34.

In the heat insulating ring 10 of the present embodiment, the cross-sectional shape of the groove portion 34 provided in the outer peripheral surface 30 may be any one or more cross-sectional shapes selected from the group consisting of the first cross-sectional shape, the second cross-sectional shape, the third cross-sectional shape, and the fourth cross-sectional shape. For example, when the number of the groove portions 34 provided in the outer peripheral surface 30 is only one, the cross-sectional shape of the groove portions 34 is any one selected from the group consisting of the first cross-sectional shape, the second cross-sectional shape, the third cross-sectional shape, and the fourth cross-sectional shape. In the case where the number of the grooves 34 provided in the outer peripheral surface 30 is two or more, the sectional shape of the grooves 34 may be (a) any one selected from the group consisting of a first sectional shape, a second sectional shape, a third sectional shape, and a fourth sectional shape, as illustrated in fig. 1 to 4, or (b) two or more kinds may be combined.

The groove 34 having any one of the first to fourth cross-sectional shapes is less likely to cause damage to the heat insulating ring than the groove having a square cross-sectional shape provided on the outer peripheral surface of the conventional heat insulating ring as exemplified in patent documents 1 and 2. The reason for this will be explained below.

First, when the internal combustion engine is operated, the in-cylinder pressure acts on the inner peripheral surface of the heat insulating ring. Therefore, a strong force acts on the heat insulating ring from the inner circumferential side to the outer circumferential side of the heat insulating ring. Therefore, if the groove portion is provided on the outer peripheral surface of the heat insulating ring in order to form the air layer for heat insulation, it is difficult to avoid a problem that local stress concentration is likely to occur in the groove portion or the vicinity thereof.

Therefore, the inventors of the present application have studied the stress distribution in the cross section of the heat insulating ring in order to investigate the cause of breakage of the groove portion in the conventional heat insulating ring provided with a groove portion having a square cross section. Fig. 5 is a diagram showing an example of the results of simulation analysis of the stress distribution and the temperature distribution in the conventional heat insulating ring provided with the groove portion having a square cross section.

Fig. 5 (a) is a cross-sectional view showing a cross-sectional shape of an insulating ring used for simulation analysis. Fig. 5 (a) shows a state in which the heat insulating ring 12 is attached to the inner circumferential surface 130A of the cylinder liner 102. Two groove portions 36 having a square cross section are provided on the outer peripheral surface 30 of the heat insulating ring 12 shown in fig. 5 (a) instead of the two groove portions 34 shown in fig. 1 to 4, and the dimensions and shapes of the other portions of the heat insulating ring 12 other than the groove portions 36 are the same as those of the heat insulating ring 10B shown in fig. 6 (a) described later. Fig. 5 (C) is a diagram showing a stress distribution of the heat insulating ring 12 shown in fig. 5 (a), and fig. 5 (B) is a diagram showing a temperature distribution of the heat insulating ring 12 and the cylinder liner 102 shown in fig. 5 (a).

In the heat insulating ring 12 and the cylinder liner 102 shown in fig. 5 (a), the dimensions of the main portions are set as follows. The dimensions and shapes differ only in the dimension and shape of the groove 36 and the groove 34B in fig. 5 (a) and fig. 6 (a) described later, and differ only in the presence or absence of the

grooves

36 and 34B in fig. 5 (a) and fig. 6 (a) and fig. 7 (a) described later.

Radial thickness of the annular member constituting the heat insulating ring 12: 2.3 mm;

axial height of the annular member constituting the heat insulating ring 12: 9.9 mm;

maximum opening width of the groove portion 36 in the annular member axial direction: 3.15 mm;

maximum groove depth of the groove portion 36: 0.5 mm;

the radial thickness of the cylindrical member (the portion thereof corresponding to the first region 130A) constituting the cylinder liner 102: 2.7 mm;

axial length of the cylindrical member constituting the cylinder liner 102 (the portion thereof corresponding to the first region 130A): and 9.9 mm.

The simulation analysis shown in fig. 5 was performed using commercially available strength and thermal analysis software. In the case of performing the simulation analysis, the following conditions were used: the material of the heat insulating ring 12 and the cylinder liner 102 is cast iron (FC250), and the general in-cylinder pressure and combustion heat in the internal combustion engine act from the inner peripheral side of the heat insulating ring 12, and the ambient temperature is room temperature. In fig. 5 (C), the gray scale display shown by white to black indicates the magnitude of the stress, and the stress is larger when white and smaller when black. Note that fig. 5 (B) will be described later. Note that, in fig. 5 (a) and 5 (B), the illustration of the back side of the cross section of the heat insulating ring 12 is omitted.

As clearly confirmed from (C) of fig. 5: in both corner portions 36C and the center portion of the groove bottom surface 36B of the groove 36 having a square cross section, there is an interface (stress concentration portion) formed by a layer having a strong stress action (the white-most portion in the drawing) and a layer having a weak stress action (the black-most portion in the drawing) in direct contact with each other. In such a stress concentration portion, the strengths of the stresses respectively acting on one side and the other side of the interface are extremely different. Thus, it can be inferred that: the stress concentration portion causes breakage of the heat insulating ring 12.

Based on the above knowledge, it can be considered that: in the cross-sectional shape of the groove portion, (a) the number of corner portions 36C causing the stress concentration portion is reduced or the corner portions 36C are eliminated, and (B) the central portion of the groove bottom surface 36B causing the stress concentration portion is formed into an arcuate shape or a V-shape which is convex in the inner circumferential direction, whereby a strong stress locally acting on the central portion of the groove bottom surface 36B is dispersed to the periphery, which is very important. Based on this, the present inventors have devised the heat insulating ring 10 of the present embodiment having the groove portions 34 illustrated in fig. 1 to 4. Here, the number of the corner portions of the groove portion 34A having the first cross-sectional shape is one, and the bottom center portion of the groove portion 34A is formed in a V-shape. In addition, the

groove portions

34B, 34C, and 34D having the second to fourth cross-sectional shapes do not have the corner portion 36C, and the center portion of the groove bottom surface of the

groove portions

34B, 34C, and 34D is formed in an arcuate shape formed by a curved line curved so as to be convex in the inner circumferential direction.

Fig. 6 is a diagram showing an example of the results of simulation analysis of the stress distribution and the temperature distribution in the heat insulating ring according to the present embodiment. Fig. 6 (a) is a cross-sectional view showing a cross-sectional shape of an insulating ring used for simulation analysis, and is substantially the same as the insulating ring 10B shown in fig. 2 except that dimensions of respective portions are set to predetermined values. Fig. 6 (C) is a diagram showing a stress distribution of the heat insulating ring 10B shown in fig. 6 (a), and fig. 6 (B) is a diagram showing a temperature distribution of the heat insulating ring 10B and the cylinder liner 102 shown in fig. 6 (a). The simulation analysis shown in fig. 6 was performed under the same conditions as the simulation analysis shown in fig. 5, except that the groove portion 34B of the heat insulating ring 10B and the groove portion 36 of the heat insulating ring 12 had different cross-sectional shapes. That is, the positions, the number, and the areas of the contact portions (flat portions 32) between the cylinder liner 102 and the heat insulating rings 10B and 12, at which the in-cylinder pressure is transmitted to the cylinder liner 102 side, are the same for the heat insulating ring 10B and the heat insulating ring 12. The maximum opening width and the maximum groove depth of the

groove portions

34B and 36 are also the same. Therefore, it can be considered that: the difference in stress distribution between fig. 5 (C) and fig. 6 (C) is actually caused by the difference in cross-sectional shape between the groove portion 34B of the heat insulating ring 10B and the groove portion 36 of the heat insulating ring 12. Note that fig. 6 (B) will be described later. Note that, in fig. 6 (a) and 6 (B), the illustration of the back side of the cross section of the heat insulating ring 10B is omitted.

In the heat insulating ring 10B shown in fig. 6 (a), the dimensions of the main portion of the heat insulating ring 10B are set as follows. In addition, the size of the main portion of the cylinder liner 102 is set to be the same as (a) in fig. 5. The groove 34B has a cross-sectional shape that is line-symmetrical with respect to a straight line that passes through the center of the bottom surface of the groove 34B and is parallel to the radial direction of the annular member 20.

Radial thickness of the annular member 20 constituting the heat insulating ring 10B: 2.3 mm;

axial height of the annular member 20 constituting the heat insulating ring 10B: 9.9 mm;

maximum opening width of the groove portion 34B in the axial direction of the annular member 20: 3.15 mm;

maximum groove depth of the groove portion 34B: 0.5 mm;

radius of curvature of curve near the center of bottom surface of groove portion 34B: and 1.0 mm.

As is clear from fig. 6 (C), although there is a stress distribution in the heat insulating ring 10B of the present embodiment, a significant stress concentration portion as shown in fig. 5 (C) is not observed. The results demonstrate that: the

grooves

34A, 34B, 34C, and 34D shown in fig. 1 to 4 are less likely to cause breakage due to the grooves than the grooves 36 shown in fig. 5.

Further, since the space (heat insulating air layer) surrounded by the groove portion and the cylinder liner is filled with a gas (air, combustion gas, or a mixture thereof) having extremely low thermal conductivity, the heat insulating air layer greatly contributes to the exertion of the heat insulating property by the heat insulating ring. From this point, it is considered that the larger the volume of the heat insulating air layer is, the more advantageous the improvement of the heat insulating property is. However, the inventors of the present invention studied the relationship between the volume of the heat insulating air layer and the heat insulating property of the heat insulating ring, and found that: simply increasing the volume of the heat insulating air layer may not significantly improve the heat insulating property. The reason for this will be explained below.

Fig. 7 is a diagram showing an example of the result of a simulation analysis of the temperature distribution in the heat insulating ring provided with no groove portion. Fig. 7 (a) shows a state in which the heat insulating ring 14 is attached to the inner circumferential surface 130A of the cylinder liner 102. The heat insulating ring 14 shown in fig. 7 (a) is made of the same material and has the same dimensions and shapes as the heat insulating ring 12 shown in fig. 5 (a) and the heat insulating ring 10B shown in fig. 6 (a), except that no groove is provided in the outer peripheral surface 30. Fig. 7 (B) is a graph showing the temperature distribution of the heat insulating ring 14 and the cylinder liner 102 shown in fig. 7 (a). The simulation analysis shown in fig. 7 was performed under the same conditions as the simulation analysis shown in fig. 5 and 6, except that the heat insulating ring 14 did not have a groove portion. Here, in fig. 5 (B), 6 (B), and 7 (B), the gradations shown by white to black indicate a difference in temperature, and the temperature is higher when white and lower when black.

In the heat insulating ring 14 shown in fig. 7 (a), the dimensions of the main portion of the heat insulating ring 14 are set as follows. In addition, the size of the main portion of the cylinder liner 102 is set to be the same as (a) in fig. 5.

Radial thickness of the annular member 20 constituting the heat insulating ring 14: 2.3 mm;

axial height of the annular member 20 constituting the heat insulating ring 14: and 9.9 mm.

As is clear from fig. 7 (B), in the heat insulating ring 14 having no groove portion, heat is smoothly transferred from the combustion chamber side to the cylinder liner 102 via the heat insulating ring 14. That is, in the heat insulating ring 14 having no groove portion, there is almost no heat insulating effect.

Further, referring to fig. 5 (B) and fig. 6 (B), in the heat insulating rings 10B and 12, the heat insulating rings 10B and 12 themselves are at a higher temperature than the heat insulating ring 14 due to the presence of the grooves 34B and 36 (heat insulating air layer). However, the temperature of the cylinder liner 102 is still lower due to this. Here, it is understood that the heat insulating ring 10B and the heat insulating ring 12 are slightly inferior to the heat insulating ring 12 in the heat insulating property of the heat insulating ring 10B, but the heat insulating property of the heat insulating ring 10B and the heat insulating ring 12 is not significantly different with reference to the heat insulating ring 14.

On the other hand, the groove portion 34B provided in the heat insulating ring 10B and the groove portion 36 provided in the heat insulating ring 12 have the same maximum opening width, the same maximum groove depth, and the same number of groove portions, and the difference therebetween is only in the sectional shape of the groove portion and the sectional area (volume of the heat insulating air layer) based thereon. The cross-sectional area (volume of the heat-insulating air layer) of the groove 34B is about 1/2 of the cross-sectional area (volume of the heat-insulating air layer) of the groove 36. That is, as is apparent from the simulation analysis results shown in fig. 5 (B), 6 (B), and 7 (B), the thermal insulation property may not be improved simply in proportion to the volume of the thermal insulation air layer. In addition, from these results, it is considered that: the heat insulation property actually depends greatly on the maximum opening width of the

grooves

34B and 36, that is, the sectional length of the flat portion 32 serving as a heat transfer path from the heat insulating rings 10B and 12 to the cylinder liner 102 side, as compared with the volume of the heat insulating air layer.

Here, when the groove portion 36 having a square cross section and the

groove portions

34A, 34B, 34C, and 34D having the first to fourth cross-sectional shapes have the same maximum opening width and maximum groove depth, the cross-sectional area (volume of the heat insulating air layer) of the

groove portions

34A, 34B, 34C, and 34D is smaller than that of the groove portion 36, and the material portion (actual thickness portion) constituting the heat insulating ring 10 increases as the cross-sectional area decreases.

From these cases, it can be considered that: the

grooves

34A, 34B, 34C, and 34D having the first to fourth cross-sectional shapes, when the groove 36 having a square cross-section with the same maximum opening width and maximum groove depth as those of the grooves is used as a reference, (a) exhibit a heat insulating effect approximately equal to that of the groove 36, (B) exhibit a strength-improving effect of the heat insulating ring 10 due to a difference in the cross-sectional shape of the groove with respect to the groove 36, and (C) exhibit a strength-improving effect of the heat insulating ring 10 due to an increase in the actual thickness of the groove 36.

Next, a preferred embodiment of the heat insulating ring 10 of the present embodiment will be described.

Fig. 8 is an enlarged cross-sectional view showing an example of the groove portion 34A having the first cross-sectional shape. Fig. 9 is an enlarged sectional view showing an example of the groove portion 34B having the second sectional shape. The groove 34A has a V-shaped cross section formed by only two

straight lines

40A and 40B and one corner 42 which is an intersection of the two

straight lines

40A and 40B, and the groove 34B has a cross section formed by rounding the vicinity of the corner 42 in the cross section of the groove 34A to form a curved line 44.

Here, the angle θ 1 formed by the two

straight lines

40A and 40B is not particularly limited as long as the shape formed by the two

straight lines

40A and 40B is a V shape, but is preferably 45 degrees to 160 degrees, more preferably 90 degrees to 160 degrees, further preferably 120 degrees to 150 degrees, and particularly preferably 135 degrees to 145 degrees. In order to sufficiently ensure the heat insulating property of the

heat insulating rings

10A, 10B when the angle θ 1 is smaller than 45, it is necessary to (a) increase the number of the

groove portions

34A, 34B per unit axial height of the annular member 20 provided on the outer peripheral surface 30, or (B) further increase the maximum groove depth Dr and the maximum opening width Wr of the

groove portions

34A, 34B. However, in the case of the former (a), when the

heat insulating rings

10A and 10B are manufactured, the processing of the

groove portions

34A and 34B becomes more complicated. In the case of the latter (B), the actual thickness portion is greatly reduced, and therefore, the strength of the

heat insulating rings

10A and 10B may be easily reduced. When the angle θ 1 exceeds 160 degrees, the thickness of the heat insulating air layer becomes extremely small relative to the maximum opening width Wr, and therefore, the heat insulating performance of the

heat insulating rings

10A and 10B may be easily reduced.

On the other hand, the angle θ 2A formed by the straight line 40A and the flat portion 32 and the angle θ 2B formed by the straight line 40B and the flat portion 32 are not particularly limited as long as a desired angle θ 1 can be obtained, and it is generally preferable that the angle θ 2A and the angle θ 2B are the same. In the examples shown in fig. 8 and 9, the angle θ 2A and the angle θ 2B are set to be the same. In addition, (i) the angle θ 2A and the angle θ 2B are preferably 90 degrees to 170 degrees, more preferably 100 degrees to 170 degrees, and further preferably 120 degrees to 170 degrees, respectively; (ii) with respect to the sum of the angle θ 2A and the angle θ 2B (θ 2A + θ 2B), 225 degrees to 340 degrees is preferable, and 240 degrees to 320 degrees is more preferable. Further, (iii) with respect to the absolute difference | θ 2A- θ 2B | between the angle θ 2A and the angle θ 2B, 0 degree to 45 degrees is preferable, 0 degree to 30 degrees is more preferable, 0 degree to 15 degrees is further preferable, and 0 degree is most preferable.

In addition, (a) when the angle θ 2A (or the angle θ 2B) is 90 degrees or more and less than 100 degrees, and (B) | θ 2A- θ 2B | exceeds 30 degrees, the asymmetry of the sectional shape of the

groove portions

34A, 34B becomes large, and the straight line 40A (or the straight line 40B) is parallel or substantially parallel to the radial direction. In the

grooves

34A and 34B having such a cross-sectional shape, the processing for forming the

grooves

34A and 34B by cutting or the like may be difficult. Therefore, from the viewpoint of facilitating the processing of the

grooves

34A and 34B, it is more preferable that: even in the range satisfying the above conditions (i) to (iii), the angle θ 2A and the angle θ 2B are appropriately selected out of the ranges satisfying the above conditions (a) and (B). However, if a processing method having excellent workability is available or if other advantages are present, it is needless to say that the

grooves

34A and 34B satisfying the conditions (a) and (B) may be provided as necessary.

The curvature radius of the curve 44 is not particularly limited, but is preferably 0.2 mm to 4.0 mm, more preferably 0.5 mm to 1.5 mm, and particularly preferably 0.8 mm to 1.5 mm.

Fig. 10 is an enlarged cross-sectional view showing an example of the groove portion 34C having the third cross-sectional shape. In fig. 10 (a), among others, shown are: an example of the groove portion 34C when the cross-sectional shape is the semicircular arc 50A (50) (when 2 × the maximum groove depth Dr is equal to the maximum opening width Wr) is shown in fig. 10 (B): the cross-sectional shape of the groove portion 34C is an example of the arc 50B (50) (2 × maximum groove depth Dr < maximum opening width Wr), in which the arc 50B (50) is curved more gently than the semicircular arc 50A.

Fig. 11 is an enlarged cross-sectional view showing an example of the groove portion 34D having a fourth cross-sectional shape (U-shaped cross section). The groove 34D having a U-shaped cross section has a cross-sectional shape: a combination of the arc 50 and two straight lines 52 extending from both ends of the arc 50 in the outer circumferential direction of the heat insulating ring 10D is formed as illustrated in fig. 10.

In the groove portion 34 and the heat insulating ring 10 having the groove portion 34 illustrated in fig. 1 to 4 and 8 to 11, at least one of the following expressions (1) to (4) is preferably satisfied, more preferably, any two expressions are satisfied simultaneously, further preferably, any three expressions are satisfied simultaneously, and particularly preferably, all four expressions are satisfied simultaneously.

Formula (1): 0.85% or more Sr/(Dr × Wr) 0.5 or more

Equation (2): 0.41 ≧ Dr/Wr

Equation (3): 0.57 ≧ Dr/Tr

Equation (4): 055 ≥ Fr/Hr

The numerical parameters in equations (1) to (4) have the following meanings.

Dr: maximum groove depth (#) of the groove portion 34

Wr: the maximum opening width (#) of the groove portion 34 in the axial direction of the ring member 20

Sr: the cross-sectional area ([ mm ]) of the groove 34 in the cross section perpendicular to the circumferential direction of the annular member 20²)

Tr: radial thickness (#) of the ring member 20

Fr: the length (#) of the flat portion 32 in the axial direction of the ring member 20

Hr: axial height (#) of the ring member 20

The length Fr of the flat portion 32 indicates the total length of the lengths Fr1 to Frn of the flat portions 32. For example, in the heat insulating ring 10 shown in fig. 1 to 4, there are: the total of three flat portions 32, that is, the flat portion 32 on the combustion chamber side, the flat portion 32 on the center portion, and the flat portion 32 on the crankcase side in the axial direction of the annular member 20. Therefore, the total value of the lengths Fr1, Fr2, Fr3 of the three flat portions 32 is defined as the length Fr of the flat portion 32.

Here, Sr/(Dr × Wr) shown in expression (1) indicates that the groove portion has a square cross-sectional shape 36 when the value is 1, and indicates that the groove portion has a V-shaped cross-sectional shape 34A when the value is 0.5, and the cross-sectional shape of the groove portion changes from the V-shape (first cross-sectional shape) to a second cross-sectional shape, an arc shape (third cross-sectional shape), a U-shape (fourth cross-sectional shape), and a square shape, which are curved by rounding the corner portions of the V-shape, in this order as the value increases from 0.5 to 1. When the formula (1) is satisfied, the heat insulating ring 10 having improved strength while maintaining heat insulating properties substantially equal to each other can be obtained more easily than the heat insulating ring 12 having the groove portion 36 having a square cross section. In addition, from the viewpoint of further improving the strength, Sr/(Dr × Wr) is more preferably 0.50 to 0.84, still more preferably 0.53 to 0.70, and particularly preferably 0.54 to 0.68.

Dr/Wr shown in equation (2) is a parameter indicating the aspect ratio of the groove 34, and Dr/Tr shown in equation (3) is a parameter indicating the depth ratio of the groove 34 to the insulating ring 10. When the formula (2) is satisfied, the heat insulating ring 10 having improved strength while maintaining heat insulating properties substantially equal to each other can be obtained more easily than the heat insulating ring 12 having the groove portion 36 having a square cross-sectional shape. Then, the same applies to the case where expression (3) is satisfied.

The lower limit of Dr/Wr is not particularly limited, but is preferably 0.10 or more from the practical viewpoint, and the lower limit of Dr/Tr is also not particularly limited, but is preferably 0.15 or more from the practical viewpoint. Further, Dr/Wr is more preferably 0.16 to 0.41, and still more preferably 0.16 to 0.21, from the viewpoint of achieving a more balanced balance between heat insulating properties and strength. Further, Dr/Tr is more preferably 0.22 to 0.57, and still more preferably 0.22 to 0.29, from the viewpoint of achieving a more balanced combination of heat insulation and strength.

Further, Fr/Hr shown in equation (4) represents a ratio of the length Fr of the flat portion 32 with respect to the axial height Hr of the insulating ring 10. Considering that the ratio of the notch portion (chamfered portion) 38 to the axial height Hr is relatively very small, Fr/Hr can also be said to be an inverse function of Σ Wr/Hr (the ratio of the sum of the maximum opening widths Wr to the axial height Hr). When equation (4) is satisfied, the heat insulating ring 10 having improved strength while maintaining heat insulating properties substantially equal to each other can be obtained more easily than the heat insulating ring 12 having the groove portion 36 having a square cross-sectional shape. The lower limit of Fr/Hr is not particularly limited, but is preferably 0.10 or more from the practical viewpoint. Further, when the improvement of the heat insulating property is more desirable than the strength, Fr/Hr is more preferably 0.18 or more and less than 0.37, and when the improvement of the strength is more desirable than the heat insulating property, Fr/Hr is more preferably 0.37 to 0.55.

In the heat insulating ring 10 of the present embodiment, it is also preferable that the following expression (5) is satisfied from the viewpoint of suppressing the decrease in strength of the heat insulating ring 10.

Equation (5): Tr-Dr is more than or equal to 1.0 mm

The material of the annular member 20 constituting the heat insulating ring 10 of the present embodiment is not particularly limited, and examples thereof include: iron, iron alloy (heat-resistant steel such as SUH, stainless steel such as SUS, cast iron (in particular, cast iron of the same material as the cylinder liner 102), and the like), nickel alloy (nichrome and the like).

The outer dimensions of the annular member 20 constituting the heat-insulating ring 10 according to the present embodiment are not particularly limited, but generally, the inner diameter thereof is preferably 84 mm to 247 mm, more preferably 107 mm to 234 mm, and still more preferably 111 mm to 147 mm; the radial thickness Tr is preferably 1.5 mm to 8 mm, and more preferably 1.5 mm to 3.0 mm; the axial height Hr is preferably 5.0 mm to 70.0 mm, and more preferably 6.5 mm to 18.0 mm. The maximum opening width Wr and the maximum groove depth Dr, which are dimensions common to the first to fourth cross-sectional shapes, are not particularly limited, but the maximum opening width Wr is preferably about 1.0 mm to 40 mm, and the maximum groove depth Dr is preferably about 0.2 mm to 4.0 mm, for example.

The number of the groove portions 34 provided on the outer peripheral surface 30 in the cross section perpendicular to the circumferential direction of the annular member 20 is not particularly limited, and any number may be selected as long as there is one or more grooves per the entire height of the annular member 20 in the axial direction. However, the number of the groove portions 34 is more preferably two to five, still more preferably two to three, and particularly preferably two per axial height 10 mm of the annular member 20. When the number of the groove portions 34 is one in the entire height range of the annular member 20 in the axial direction, if the equation (4) is further satisfied, stress tends to concentrate on the two narrow flat portions 32 located on both sides of the one groove portion 34 in the axial direction of the annular member 20. That is, the following operation becomes more difficult: from the viewpoint of ensuring the strength of the heat insulating ring 10, the stress is appropriately dispersed in the axial direction of the annular member 20. In addition, when the number of the groove portions 34 is six or more per the axial height 10 mm of the annular member 20, the width (axial length) of the flat portion 32 located between two adjacent groove portions 34 in the axial direction of the annular member 20 becomes narrow. Therefore, when the groove portion 34 is formed by cutting, the flat portion 32 is easily damaged.

The heat insulating ring 10 of the present embodiment is a member used for the purpose of reducing heat loss of the internal combustion engine, but may be used as a member (carbon scraper ring) for the purpose of scraping off carbon deposits adhering to the top land (top land) of the piston, in addition to the purpose. When the heat insulating ring 10 is also used as a carbon deposit scraping ring, the inner diameter of the annular member 20 constituting the heat insulating ring 10 is set to be slightly smaller than the inner diameter of the cylinder liner 102 to which the heat insulating ring 10 is attached (the inner diameter in a portion on the crankcase side than the portion to which the heat insulating ring 10 is attached). On the other hand, when the heat insulating ring 10 of the present embodiment is not used as a soot scraping ring, the inner diameter of the annular member 20 constituting the heat insulating ring 10 may be set to be substantially equal to or larger than the inner diameter of the cylinder liner 102 to which the heat insulating ring 10 is attached (the inner diameter in a portion on the crankcase side than the portion to which the heat insulating ring 10 is attached).

Further, the surface of the annular member 20 constituting the heat insulating ring 10 of the present embodiment may be subjected to various surface treatments or formed with various coatings as necessary. For example, the surface of the annular member 20 may be formed with a sprayed film by a spraying process, or with a manganese phosphate film by a manganese phosphate film process. Although the method of forming the film depends, the film may be selectively formed on a part of the surface of the annular member 20 (the outer peripheral surface 30, the inner peripheral surface 60, and the like) or may be formed to cover the entire surface of the annular member 20. In addition, since the thermal insulating property of the thermal insulating ring 10 is generally excellent, the thermal insulating film or the manganese phosphate film is preferably formed on at least the outer peripheral surface 30 of the annular member 20, from the viewpoint of improving the thermal insulating property.

The heat insulating ring 10 of the present embodiment can be used for any type of internal combustion engine as long as it is an internal combustion engine provided with a cylinder liner to which the heat insulating ring 10 can be attached. Representative examples of such internal combustion engines include gasoline engines and diesel engines. In addition, when the heat insulating ring 10 of the present embodiment is used in a diesel engine in which soot is easily generated in a combustion chamber, the heat insulating ring 10 of the present embodiment is preferably used also as a soot scraping ring.

< internal combustion engine >

The internal combustion engine of the present embodiment includes at least a cylinder liner and the heat insulating ring 10 of the present embodiment. Fig. 1 to 4 are schematic cross-sectional views showing an example of an internal combustion engine 200A (200) according to the present embodiment. The internal combustion engine 200A shown in fig. 1 to 4 includes at least the cylinder liner 102 and the heat insulating ring 10 of the present embodiment. The cylinder liner 102 includes a cylindrical member 120, and an inner peripheral surface 130 of the cylindrical member 120 includes a first region 130A near one end side (combustion chamber side) in the axial direction of the cylindrical member 120 and a second region 130B other than the vicinity of one end side. In addition, the inner diameter in the first region 130A is set larger than that in the second region 130B. Then, the heat insulating ring 10 is fitted in a portion of the inner peripheral surface 130 of the cylinder liner 102 that is partially recessed toward the outer peripheral side, i.e., the first region 130A of the cylinder liner 102.

Fig. 12 is a schematic sectional view showing another example of the internal combustion engine of the present embodiment, and is a schematic diagram of an example of an internal combustion engine 200 including the heat insulating ring 10 of the present embodiment, which also functions as a soot scraping ring. The internal combustion engine 200D (200) shown in fig. 12 includes at least the cylinder liner 102 similar to that illustrated in fig. 1 to 4 and the heat insulating ring 10E (10) of the present embodiment fitted in the first region 130A of the cylinder liner 102. Here, the insulation ring 10E shown in fig. 12 has the same dimensional shape as the insulation ring 10B shown in fig. 2 except that the inner diameter thereof is smaller than that of the insulation ring 10B shown in fig. 2. In the internal combustion engine 200D shown in fig. 12, the inner diameter of the annular member 20 constituting the heat insulating ring 10E is smaller than the inner diameter in the second region 130B of the cylindrical member 120 constituting the cylinder liner 102. Therefore, the inner circumferential surface 60 of the annular member 20 is configured to: and protrudes further toward the central axis of the cylinder liner 102 than the second region 130B of the cylinder liner 102. Therefore, in the case where the soot 400 is attached to the outer circumferential surface of the top land 310 of the piston 300, the soot 400 is scraped off by the heat insulating ring 10E when the piston 300 moves toward the top dead center within the cylinder liner 102. The inner diameter of the annular member 20 constituting the heat insulating ring 10E is set to be larger than the outer diameter of the top land 310 of the piston 300.

In the internal combustion engine 200A illustrated in fig. 1 to 4, the inner peripheral surface 60 of the annular member 20 and the second region 130B of the cylinder liner 102 constituting the

heat insulating rings

10A, 10B, 10C, and 10D are on the same horizontal plane. That is, the inner diameter of the second region 130B is the same as the inner diameter of the ring member 20. Therefore, in the internal combustion engine 200A, the

heat insulating rings

10A, 10B, 10C, 10D do not have a function as a carbon deposit scraping ring.

The internal combustion engine 200 of the present embodiment may be any type of internal combustion engine, and a typical internal combustion engine is preferably a gasoline engine or a diesel engine.

Further, the inner peripheral surface 130 of the cylindrical member 120 constituting the cylinder liner 102 may be subjected to various surface treatments or formed with various coatings, as necessary. For example, the inner peripheral surface 130 of the cylindrical member 120 may be formed with a sprayed film by a spraying process, or with a manganese phosphate film by a manganese phosphate film process. Although the method of forming the coating is also dependent, the coating may be selectively formed on a part of the inner circumferential surface 130 (the first region 130A, the second region 130B, and the like) of the cylindrical member 120 or may be formed to cover the entire inner circumferential surface 130. In addition, since the thermal insulation property of the thermal spray film or the manganese phosphate film is generally excellent, it is preferable that the thermal spray film or the manganese phosphate film is formed at least on the first region 130A from the viewpoint of improving the thermal insulation property in the vicinity of the portion where the thermal insulation ring 10 is attached.

[ examples ] A method for producing a compound

The present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples.

In the heat insulating rings of examples 1 to 9 and comparative example 1, the following parameters were calculated based on the parameters shown in equations (1) to (4): the tendency of the variation in the temperature of the inner peripheral surface of the heat insulating ring and the maximum displacement amount in the groove radial direction, which was caused by Sr/(DrxWr), Dr/Wr, Dr/Tr, and Fr/Hr, was analyzed by simulation. The results are shown in tables 1 to 3. In all examples and comparative examples, the outer dimensions, the number of grooves, and the material of the heat insulating rings were the same. The dimensions of each portion of the insulating ring shown in the table are all represented by mm. Further, as illustrated in fig. 1 and the like, the two grooves are provided at equal intervals in the axial direction of the heat insulating ring. In addition, the inner peripheral surface temperature is: the larger the value, the more excellent the heat insulation performance of the heat insulating ring, and the maximum displacement amount in the groove radial direction is: the smaller the value, the smaller the stress generated in the heat insulating ring, and the less likely fatigue fracture of the heat insulating ring occurs.

The simulation analyses shown in tables 1 to 3 were performed using commercially available strength and thermal analysis software. In the case of performing the simulation analysis, the following conditions were used: the material of the heat insulating ring and the cylinder liner used in combination therewith was cast iron (FC250), and the general in-cylinder pressure and combustion heat in the internal combustion engine acted from the inner peripheral side of the heat insulating ring, and the ambient temperature was room temperature.

Here, shown in table 1 are: when the maximum opening width Wr and the maximum groove depth Dr of the groove portion were the same, the inner peripheral surface temperature and the maximum groove radial displacement amount based on Sr/(Dr × Wr) were evaluated. When the maximum opening width Wr and the maximum groove depth Dr of the groove portion are the same, it can be said that the cross-sectional shape is defined as a quantitative parameter by changing the value of Sr/(Dr × Wr) to be equivalent to changing the shape of the groove portion. Therefore, it can be said that table 1 is a result of evaluating the temperature of the inner peripheral surface and the maximum displacement amount in the groove radial direction based on the sectional shape of the groove.

Shown in table 2 are: when the sectional shape of the groove portion and the maximum opening width Wr are the same, the result of evaluation based on the inner peripheral surface temperature and the maximum groove radial displacement amount by the maximum groove depth Dr is obtained. Among them, it can be considered that: the influence of the maximum groove depth Dr on the heat insulating property and the mechanical strength is not caused by the absolute value of the maximum groove depth Dr, but is strongly influenced by the relative proportion of the maximum groove depth Dr occupied in the heat insulating ring as a whole. Thus, shown in table 2 are: the results of evaluation were obtained based on the ratio of the maximum groove depth Dr, which is the major axial dimension of the heat insulating ring, to the maximum opening width Wr, which is the major radial dimension of the heat insulating ring, and the radial thickness Tr, which is the major radial dimension of the heat insulating ring, as reference values, i.e., Dr/Wr (aspect ratio of the groove portions), Dr/Tr (depth ratio of the groove portions to the heat insulating ring), and the inner peripheral surface temperature and the maximum amount of radial displacement of the groove portions.

Shown in table 3 are: the results of evaluation of the inner peripheral surface temperature and the maximum groove portion radial displacement amount based on the flat portion length Fr (or the maximum opening width Wr which is an actual inverse function of the flat portion length Fr) were obtained. Among them, it can be considered that: the influence of the flat portion length Fr on the heat insulating property and the mechanical strength is not caused by the absolute value of the flat portion length Fr, but is strongly influenced by the relative proportion of the flat portion length Fr in the entire heat insulating ring. Thus, shown in table 3 are: the results of evaluation were made based on the ratio of the flat portion length Fr, i.e., Fr/Hr, when the axial height Hr, which is the major axial dimension of the heat insulating ring, was taken as a reference value, and the inner peripheral surface temperature and the groove portion radial direction maximum displacement amount were evaluated. Fr/Hr can be said to be an occupation ratio of the flat portion in the axial direction.

[ TABLE 1 ]

[ TABLE 2 ]

[ TABLE 3 ]

Claims

1. A heat insulating ring for a cylinder liner, characterized in that,

the heat insulating ring for the cylinder sleeve is provided with an annular component,

in a cross section of the annular member perpendicular to a circumferential direction, an outer circumferential surface of the annular member includes a flat portion parallel to an axial direction of the annular member and a groove portion recessed more toward an inner circumferential side of the annular member than the flat portion;

(1) a V-shaped first cross-sectional shape formed only by two straight lines and one corner portion which becomes an intersection of the two straight lines,

(2) a second cross-sectional shape in which the vicinity of a corner in the first cross-sectional shape is rounded to form a curve,

(4) a fourth cross-sectional shape of a U-shape.

2. The heat insulating ring for a cylinder liner according to claim 1,

in the first cross-sectional shape and the second cross-sectional shape, an angle formed by the two straight lines is 45 degrees to 160 degrees.

3. The heat insulating ring for a cylinder liner according to claim 1 or 2,

satisfies the following formula (1),

in the above-mentioned formula (1),

sr represents a cross-sectional area ([ mm ]) of the groove in a cross-section perpendicular to a circumferential direction of the annular member²)，

Dr denotes a maximum groove depth (mmm) of the groove portion,

wr denotes a maximum opening width (mmm) of the groove portion in the axial direction of the annular member.

4. The heat insulating ring for a cylinder liner according to claim 1 or 2,

satisfies the following equation (2),

equation (2): 0.41 is more than or equal to Dr/Wr;

in the above-mentioned formula (2),

dr denotes a maximum groove depth (mmm) of the groove portion,

5. The heat insulating ring for a cylinder liner according to claim 1 or 2,

satisfies the following equation (3),

equation (3): 0.57 is more than or equal to Dr/Tr;

in the above-mentioned formula (3),

dr denotes a maximum groove depth (mmm) of the groove portion,

tr represents a radial thickness (mm) of the annular member.

6. The heat insulating ring for a cylinder liner according to claim 1 or 2,

satisfies the following equation (4),

equation (4): 0.55 is more than or equal to Fr/Hr;

in the above-mentioned formula (4),

fr represents a length (mmm) of the flat portion in the axial direction of the annular member,

hr represents an axial height (mm) of the annular member.

7. The heat insulating ring for a cylinder liner according to claim 1 or 2,

the heat insulation ring for the cylinder sleeve is a carbon deposit scraping ring.

8. An internal combustion engine, characterized in that,

the internal combustion engine is provided with at least:

a cylinder liner having a cylindrical member, an inner peripheral surface of the cylindrical member being constituted by a first region near one end side in an axial direction of the cylindrical member and a second region other than near the one end side, an inner diameter in the first region being larger than an inner diameter in the second region, and

a heat insulating ring having an annular member and fitted in the first region of the cylinder liner;

(4) a fourth cross-sectional shape of a U-shape.

9. The internal combustion engine of claim 8,

the annular member has an inner diameter smaller than an inner diameter of the second region.

10. An internal combustion engine according to claim 8 or 9,

the internal combustion engine is a diesel engine.