WO2022044986A1 - Heat-shielding ring for cylinder liner, and internal combustion engine - Google Patents

Abstract

Provided are a heat-shielding ring for a cylinder liner that is less likely to be damaged due to a groove for forming an insulation air layer, and an internal combustion engine that uses said heat-shielding ring. The present invention is a heat-shielding ring 10 for a cylinder liner and an internal combustion engine 200 that uses the heat-shielding ring 10. In the heat-shielding ring 10 for a cylinder liner, the cross-sectional shape of a groove 34 provided in an outer peripheral surface 30 of a ring-form member 20 constituting the heat-shielding ring 10 is any one or more shapes selected from the group comprising (1) a first cross-sectional shape in the form of a letter V, (2) a second cross-sectional shape in which the vicinities of the corners of the first cross-sectional shape are rounded into a curve, (3) a third cross-sectional shape formed from only an arcuate curve, and (4) a fourth cross-sectional shape in the form of a letter U.

Description

Heat shield ring for cylinder liner and internal combustion engine

The present invention relates to a heat shield ring for a cylinder liner and an internal combustion engine.

For the purpose of reducing heat loss of an internal combustion engine, a technique of providing a heat shield ring on the inner peripheral surface near the end of the cylinder liner on the combustion chamber side is known (for example, Patent Documents 1, 2, etc.). As exemplified in Patent Documents 1 and 2, in the conventional heat shield ring, in order to form an air layer for heat insulation, a groove having a rectangular cross section in a cross section orthogonal to the circumferential direction is formed on the outer peripheral surface of the heat shield ring. Is provided.

Jitsufuku No. 05-12527 Japanese Unexamined Patent Publication No. 2007-32401

However, in the conventional heat shield ring having a groove for forming a heat insulating air layer, damage due to the groove may occur due to use in an internal combustion engine.

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

The above object is achieved by the following invention. That is,
The heat shield ring for a cylinder liner of the present invention has a ring-shaped member, and in a cross section orthogonal to the circumferential direction of the ring-shaped member, the outer peripheral surface of the ring-shaped member is a flat portion parallel to the axial direction of the ring-shaped member. And a groove portion recessed on the inner peripheral side of the ring-shaped member from the flat portion, and the cross-sectional shape of the groove portion is formed only from (1) two straight lines and one corner portion which is an intersection of the two straight lines. The V-shaped first cross-sectional shape to be formed, (2) the second cross-sectional shape in which the vicinity of the corners in the first cross-sectional shape is rounded to form a curved line, and (3) the third formed only from the arc-shaped curve. It is characterized in that it is at least one selected from the group consisting of the cross-sectional shape of (4) U-shaped fourth cross-sectional shape.

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

Another embodiment of the heat shield ring for a cylinder liner of the present invention preferably satisfies the following formula (1).
-Equation (1) 0.85 ≧ Sr / (Dr × Wr) ≧ 0.5
[In the formula (1), Sr means the cross-sectional area (mm ² ) of the groove portion in the cross section orthogonal to the circumferential direction of the ring-shaped member, Dr means the maximum groove depth (mm) of the groove portion, and Wr means the ring. It means the maximum opening width (mm) of the groove portion in the axial direction of the shaped member. ]

Another embodiment of the heat shield ring for a cylinder liner of the present invention preferably satisfies the following formula (2).
・ Equation (2) 0.41 ≧ Dr / Wr
[In the formula (2), Dr means the maximum groove depth (mm) of the groove portion, and Wr means the maximum opening width (mm) of the groove portion in the axial direction of the ring-shaped member. ]

Another embodiment of the heat shield ring for a cylinder liner of the present invention preferably satisfies the following formula (3).
・ Equation (3) 0.57 ≧ Dr / Tr
[In the formula (3), Dr means the maximum groove depth (mm) of the groove portion, and Tr means the radial thickness (mm) of the ring-shaped member. ]

Another embodiment of the heat shield ring for a cylinder liner of the present invention preferably satisfies the following formula (4).
・ Equation (4) 0.55 ≧ Fr / Hr
[In the formula (4), Fr means the length (mm) of the flat portion in the axial direction of the ring-shaped member, and Hr means the axial height (mm) of the ring-shaped member. ]

In another embodiment of the heat shield ring for a cylinder liner of the present invention, the inner diameter of the ring-shaped member is 84 mm to 247 mm, the radial thickness Tr is 1.5 mm to 8.0 mm, and the axial height Hr is 5. It is preferably 0.0 mm to 70.0 mm.

Another embodiment of the heat shield ring for the cylinder liner of the present invention is preferably carbon scraper ring.

The internal combustion engine of the present invention has a cylindrical member, and the inner peripheral surface of the cylindrical member is composed of a first region near one end side in the axial direction of the cylindrical member and a second region other than near one end side. A cylinder liner having an inner diameter in the first region larger than the inner diameter in the second region and a heat shield ring having a ring-shaped member and fitted in the first region of the cylinder liner are provided at least. In the cross section orthogonal to the circumferential direction of the ring-shaped member, the outer peripheral surface of the ring-shaped member has a flat portion parallel to the axial direction of the ring-shaped member and a groove portion recessed on the inner peripheral side of the ring-shaped member from the flat portion. The cross-sectional shape of the groove is a V-shaped first cross-sectional shape formed only from (1) two straight lines and one corner that is the intersection of the two straight lines, (2) first. A second cross-sectional shape in which the vicinity of the corners of the cross-sectional shape is rounded to form a curved line, (3) a third cross-sectional shape formed only from an arcuate curve, and (4) a U-shaped fourth cross-sectional shape. It is characterized in that it is at least one kind selected from the group consisting of.

In one embodiment of the internal combustion engine of the present invention, it is preferable that the inner diameter of the ring-shaped member is smaller than the inner diameter of the second region.

Another embodiment of the internal combustion engine of the present invention is preferably a diesel engine.

According to the present invention, it is possible to provide a heat shield ring for a cylinder liner, which is less likely to be damaged due to a groove, and an internal combustion engine using the same.

It is a schematic sectional drawing which shows an example of the heat shield ring for a cylinder liner of this embodiment, and an example of an internal combustion engine of this embodiment. It is a schematic sectional drawing which shows the other example of the heat shield ring for a cylinder liner of this embodiment, and another example of the internal combustion engine of this embodiment. It is a schematic sectional drawing which shows the other example of the heat shield ring for a cylinder liner of this embodiment, and another example of the internal combustion engine of this embodiment. It is a schematic sectional drawing which shows the other example of the heat shield ring for a cylinder liner of this embodiment, and another example of the internal combustion engine of this embodiment. It is a figure which shows an example of the analysis result which simulated the stress distribution and the temperature distribution in the heat shield ring for a cylinder liner provided with the groove part of the conventional rectangular cross section. Here, FIG. 5 (A) is a cross-sectional view showing the cross-sectional shape of the heat shield ring used for the simulation analysis, and FIG. 5 (B) is the temperature of the heat shield ring and the cylinder liner shown in FIG. 5 (A). It is a figure which shows the distribution, and FIG. 5C is a figure which shows the stress distribution of the heat shield ring shown in FIG. 5A. It is a figure which shows an example of the analysis result which simulated the stress distribution and the temperature distribution in the heat shield ring for a cylinder liner of this embodiment. Here, FIG. 6A is a cross-sectional view showing the cross-sectional shape of the heat shield ring used for the simulation analysis, and FIG. 6B is the temperature of the heat shield ring and the cylinder liner shown in FIG. 6A. It is a figure which shows the distribution, and FIG. 6C is a figure which shows the stress distribution of the heat shield ring shown in FIG. 6A. It is a figure which shows an example of the analysis result which simulated the temperature distribution in the heat shield ring which does not provide a groove part. Here, FIG. 7A is a cross-sectional view showing the cross-sectional shape of the heat shield ring used for the simulation analysis, and FIG. 7B is the temperature of the heat shield ring and the cylinder liner shown in FIG. 7A. It is a figure which shows the distribution. It is an enlarged cross-sectional view which shows an example of the groove part which has the first cross-sectional shape. It is an enlarged cross-sectional view which shows an example of the groove part which has the 2nd cross-sectional shape. It is an enlarged cross-sectional view which shows an example of the groove part which has a 3rd cross-sectional shape. Here, FIG. 10A is a diagram showing a case where the cross-sectional shape of the groove portion is a semicircular arc, and FIG. 10B is a diagram in which the cross-sectional shape of the groove portion is looser than the semicircular arc. It is a figure which shows the case of a curved arc. It is an enlarged cross-sectional view which shows an example of the groove part which has the 4th cross-sectional shape. It is a schematic sectional drawing which shows the other example of the heat shield ring for a cylinder liner of this embodiment, and another example of the internal combustion engine of this embodiment.

<Heat shield ring for cylinder liner>
1 to 4 are schematic cross-sectional views showing an example of a heat shield ring for a cylinder liner (hereinafter, abbreviated as “heat shield ring”) of the present embodiment, and have a cross-sectional structure orthogonal to the circumferential direction of the heat shield ring. It is a figure which shows about. 1 to 4 show a state in which the heat shield ring is mounted on the inner peripheral surface near the end of the cylinder liner on the combustion chamber side. Further, the Y direction shown in FIGS. 1 to 4 and other drawings means a direction parallel to the axial direction of the heat shield ring and the cylinder liner, and the X direction orthogonal to the Y direction is the heat shield ring and the cylinder liner. It means the direction parallel to the radial direction.

The heat shield ring 10 shown in FIGS. 1 to 4 has a ring-shaped member 20, and the outer peripheral surface 30 of the ring-shaped member 20 has a cross section (paper surface in the drawing) orthogonal to the circumferential direction of the ring-shaped member 20. It includes a flat portion 32 that is parallel to the axial direction of the ring-shaped member 20, and a groove portion 34 that is recessed on the inner peripheral side of the ring-shaped member 20 with respect to the flat portion 32.

In the examples shown in FIGS. 1 to 4, the heat shield ring 10 is mounted on the inner peripheral surface 130A (first region) near the end of the cylinder liner 102 on the combustion chamber side. Therefore, of the outer peripheral surface 30, the flat portion 32 is in contact with the inner peripheral surface 130A of the cylinder liner 102. Further, in the examples shown in FIGS. 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 examples shown in FIGS. 1 to 4, the outer peripheral surface 30 is also provided with notches (chamfered portions) 38 on both end sides in the axial direction. However, the notch portion (chamfered portion) 38 may be omitted. The groove portion 34 is preferably provided continuously with respect to the circumferential direction of the heat shield ring 10, but may be provided discontinuously. Further, when the groove portion 34 is continuously provided in the circumferential direction of the heat shield ring 10, the groove portion 34 may be continuously provided so as to be parallel to the circumferential direction, and the groove portions 34 intersect with each other in the circumferential direction. Therefore, it may be continuously provided so as to form a constant angle (for example, an angle exceeding 0 degrees and 30 degrees or less).

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

Further, the outer peripheral surface 30 of the heat shield ring 10C (10) shown in FIG. 3 is provided with a groove portion 34C (34) having a cross-sectional shape (third cross-sectional shape) formed only by an arcuate curve. , The outer peripheral surface 30 of the heat shield ring 10D (10) shown in FIG. 4 is provided with a groove portion 34D (34) having a U-shaped cross-sectional shape (fourth cross-sectional shape). In the heat shield ring 10 shown in FIGS. 1 to 4, the groove portions 34 are arranged at regular intervals (Fr2) with respect to the axial direction of the ring-shaped member 20. However, the distance (Fr2) between the two groove portions 34 adjacent to each other in the axial direction may be made as small as possible, and a large number of groove portions 34 may be provided in a saw blade shape.

In the heat shield ring 10 of the present embodiment, the cross-sectional shape of the groove portion 34 provided on the outer peripheral surface 30 is based on the above-mentioned first cross-sectional shape, second cross-sectional shape, third cross-sectional shape, and fourth cross-sectional shape. Any one or more selected from the group may be used. For example, if the number of the groove portions 34 provided on the outer peripheral surface 30 is only one, the cross-sectional shapes of the groove portions 34 are the first cross-sectional shape, the second cross-sectional shape, the third cross-sectional shape, and the fourth cross-sectional shape. It is any one selected from the group consisting of. Further, when the number of the groove portions 34 provided on the outer peripheral surface 30 is two or more, the cross-sectional shape of the groove portions 34 is the first as illustrated in FIGS. 1 to 4 (a). It may be only one kind selected from the group consisting of the cross-sectional shape, the second cross-sectional shape, the third cross-sectional shape and the fourth cross-sectional shape, and (b) a combination of two or more kinds. There may be.

The groove portion 34 having any of the cross-sectional shapes selected from the first to fourth cross-sectional shapes is the groove portion having a rectangular cross-sectional shape provided on the outer peripheral surface of the conventional heat shield ring exemplified in Patent Documents 1 and 2. In comparison, the heat shield ring is less likely to be damaged. The reason will be explained below.

First, when the internal combustion engine is operating, the intracranial pressure acts on the inner peripheral surface of the heat shield ring. Therefore, a strong force acts on the heat shield ring from the inner peripheral side to the outer peripheral side of the heat shield ring. Therefore, if a groove is provided on the outer peripheral surface of the heat shield ring to form a heat insulating air layer, it is unavoidable that local stress concentration is likely to occur in or near the groove.

Therefore, the present inventors examined the stress distribution in the cross section of the heat shield ring in order to investigate the cause of the tendency of damage caused by the groove in the conventional heat shield ring provided with the groove portion having a rectangular cross section. FIG. 5 is a diagram showing an example of an analysis result simulating a stress distribution and a temperature distribution in a conventional heat shield ring provided with a groove having a rectangular cross section.

Here, FIG. 5A is a cross-sectional view showing the cross-sectional shape of the heat shield ring used in the simulation analysis. FIG. 5A shows a state in which the heat shield ring 12 is mounted on the inner peripheral surface 130A of the cylinder liner 102. The outer peripheral surface 30 of the heat shield ring 12 shown in FIG. 5A is provided with two groove portions 36 having a rectangular cross section instead of the two groove portions 34 shown in FIGS. 1 to 4, and other than the groove portions 36. The dimensions and shape of each part of the heat shield ring 12 are the same as those of the heat shield ring 10B shown in FIG. 6A, which will be described later. 5 (C) is a diagram showing the stress distribution of the heat shield ring 12 shown in FIG. 5 (A), and FIG. 5 (B) is a diagram showing the heat shield ring 12 and the cylinder liner shown in FIG. 5 (A). It is a figure which shows the temperature distribution of 102.

In the heat shield ring 12 and the cylinder liner 102 shown in FIG. 5A, the dimensions of the main part are set as follows. Regarding the dimensional shape, only the dimensional shape of the groove portion 36 and the groove portion 34B is different between FIG. 5 (A) and FIG. 6 (A) described later, and it is different from FIG. 5 (A) and FIG. 6 (A) described later. , Only the presence or absence of the groove portions 36 and 34B is different from FIG. 7A described later.
-Diametric thickness of the ring-shaped member constituting the heat shield ring 12: 2.3 mm
Axial height of the ring-shaped member constituting the heat shield ring 12: 9.9 mm
-Maximum opening width of the groove 36 in the axial direction of the ring-shaped member: 3.15 mm
-Maximum groove depth of groove 36: 0.5 mm
-The radial thickness of the cylindrical member (however, the portion corresponding to the first region 130A) constituting the cylinder liner 102 is 2.7 mm.
-The axial length of the cylindrical member (however, the portion corresponding to the first region 130A) constituting the cylinder liner 102 is 9.9 mm.

The simulation analysis shown in FIG. 5 was carried out using commercially available strength and thermal analysis software. In the simulation analysis, the material of the heat shield ring 12 and the cylinder liner 102 is assumed to be 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 shield ring 12. Moreover, the ambient temperature was carried out under the condition assuming room temperature. Here, in FIG. 5C, the gradation display shown in white to black means the magnitude of stress, the whiter the stress, the larger the stress, and the blacker the stress, the smaller the stress. The explanation of FIG. 5B will be described later. Further, in FIGS. 5 (A) and 5 (B), the description of the back side of the heat shield ring 12 is omitted.

As is clear from FIG. 5 (C), in the central portion of the two corner portions 36C and the groove portion bottom surface 36B of the groove portion 36 having a rectangular cross section, a layer (whitest portion in the figure) on which extremely strong stress acts and a weak portion are weak. It was confirmed that there is an interface (stress concentration part) formed by direct contact with the stressed layer (blackest part in the figure). In such a stress concentration portion, the strength of the stress acting on one side and the other side of the interface is extremely different. Therefore, it is presumed that the stress concentration portion causes the heat shield ring 12 to break.

Based on the above findings, in the cross-sectional shape of the groove, (a) the number of corners 36C that cause the stress concentration part is reduced or eliminated, and (b) the bottom surface of the groove that causes the stress concentration part is generated. It is important to disperse the strong stress that acts locally on the central part of the groove bottom surface 36B by forming the central part of the 36B in an arch shape or a V shape that is convex in the inner peripheral direction. Conceivable. Therefore, the present inventors have found the heat shield ring 10 of the present embodiment having the groove portion 34 exemplified in FIGS. 1 to 4. Here, the groove portion 34A having the first cross-sectional shape has one corner portion, and the central portion of the bottom surface of the groove portion 34A is V-shaped. Further, the groove portions 34B, 34C, 34D having the second to fourth cross-sectional shapes do not have the corner portions 36C, and the central portion of the groove portion bottom surface of the groove portions 34B, 34C, 34D is convex in the inner peripheral direction. It has an arch shape composed of curved curves.

FIG. 6 is a diagram showing an example of analysis results simulating the stress distribution and the temperature distribution in the heat shield ring of the present embodiment. Here, FIG. 6A is a cross-sectional view showing the cross-sectional shape of the heat shield ring used in the simulation analysis, and is substantially the same as the heat shield ring 10B shown in FIG. 2 except that the dimensions of each part are set to predetermined values. It is the same sectional view. 6 (C) is a diagram showing the stress distribution of the heat shield ring 10B shown in FIG. 6 (A), and FIG. 6 (B) is a diagram showing the heat shield ring 10B and the cylinder liner shown in FIG. 6 (A). It is a figure which shows the temperature distribution of 102. The simulation analysis shown in FIG. 6 was carried out under the same conditions as the simulation analysis shown in FIG. 5, except that the cross-sectional shapes of the groove portion 34B of the heat shield ring 10B and the groove portion 36 of the heat shield ring 12 were different. That is, the positions, numbers, and areas of the contact portions (flat portions 32) between the cylinder liner 102 and the heat shield rings 10B and 12 at which the cylinder internal pressure is transmitted to the cylinder liner 102 side are the heat shield ring 10B and the heat shield ring 12. Is the same as. Further, the maximum opening width and the maximum groove depth of the groove portion 34B and the groove portion 36 are also the same. Therefore, it is considered that the difference in stress distribution between FIGS. 5 (C) and 6 (C) is substantially due to the difference in cross-sectional shape between the groove portion 34B of the heat shield ring 10B and the groove portion 36 of the heat shield ring 12. Be done. The explanation of FIG. 6B will be described later. Further, in FIGS. 6A and 6B, the description on the back side of the heat shield ring 10B is omitted.

In the heat shield ring 10B shown in FIG. 6A, the dimensions of the main part of the heat shield ring 10B are set as follows. Further, the dimensions of the main part of the cylinder liner 102 were set to be the same as those in FIG. 5 (A). The cross-sectional shape of the groove portion 34B is line-symmetric with respect to a straight line that passes through the central portion of the bottom surface of the groove portion 34B and is parallel to the radial direction of the ring-shaped member 20.
The radial thickness of the ring-shaped member 20 constituting the heat shield ring 10B: 2.3 mm.
Axial height of the ring-shaped member 20 constituting the heat shield ring 10B: 9.9 mm
-Maximum opening width of the groove 34B in the axial direction of the ring-shaped member 20: 3.15 mm
-Maximum groove depth of groove 34B: 0.5 mm
-Radius of curvature of the curve near the center of the bottom surface of the groove 34B: 1.0 mm

As is clear from FIG. 6 (C), although the stress distribution exists also in the heat shield ring 10B of the present embodiment, the remarkable stress concentration portion as shown in FIG. 5 (C) was not confirmed. This result confirms that the groove portions 34A, 34B, 34C, and 34D shown in FIGS. 1 to 4 are less likely to be damaged due to the groove portion than the groove portion 36 shown in FIG.

Since the space (insulated air layer) surrounded by the groove and the cylinder liner is filled with a gas having extremely low thermal conductivity (air, combustion gas or a mixed gas thereof), the insulated air layer is formed by a heat shield ring. It greatly contributes to the exertion of heat insulation. Based on this point, it is considered that a larger volume of the adiabatic air layer is more advantageous for improving the adiabatic property. However, when the present inventors examined the relationship between the volume of the heat insulating air layer and the heat insulating property of the heat shield ring, there are cases where the heat insulating property is not significantly improved even if the volume of the heat insulating air layer is simply increased. It turned out that there was. The reason will be explained below.

FIG. 7 is a diagram showing an example of analysis results simulating the temperature distribution in a heat shield ring having no groove. FIG. 7A shows a state in which the heat shield ring 14 is mounted on the inner peripheral surface 130A of the cylinder liner 102. The heat shield ring 14 shown in FIG. 7 (A) has the heat shield ring 12 and FIG. 6 (A) shown in FIG. 5 (A) in terms of material and dimensional shape, except that the outer peripheral surface 30 is not provided with a groove. It is the same member as the heat shield ring 10B shown in 1. Further, FIG. 7B is a diagram showing the temperature distribution of the heat shield ring 14 and the cylinder liner 102 shown in FIG. 7A. The simulation analysis shown in FIG. 7 was performed under the same conditions as the simulation analysis shown in FIGS. 5 and 6 except that the heat shield ring 14 does not have a groove. Here, in FIGS. 5 (B), 6 (B), and 7 (B), the gradation display shown by white to black means the difference in temperature, and the whiter the temperature, the higher the temperature, and the blacker the temperature, the lower the temperature. Means that.

In the heat shield ring 14 shown in FIG. 7A, the dimensions of the main part of the heat shield ring 14 are set as follows. Further, the dimensions of the main part of the cylinder liner 102 were set to be the same as those in FIG. 5 (A).
The radial thickness of the ring-shaped member 20 constituting the heat shield ring 14: 2.3 mm.
Axial height of the ring-shaped member 20 constituting the heat shield ring 14: 9.9 mm

As is clear from FIG. 7B, in the heat shield ring 14 having no groove, heat is smoothly transferred from the combustion chamber side to the cylinder liner 102 via the heat shield ring 14. That is, the heat shield ring 14 having no groove has almost no heat insulating effect.

Further, referring to FIGS. 5 (B) and 6 (B), in the heat shield rings 10B and 12, the heat shield rings 10B and 12 themselves are heat shielded due to the presence of the groove portions 34B and 36 (insulated air layer). The temperature is higher than that of the ring 14. However, due to this, the temperature on the cylinder liner 102 side becomes lower. Here, comparing the heat shield ring 10B and the heat shield ring 12, the heat shield ring 10B is slightly inferior in heat insulating property to the heat shield ring 12, but when the heat shield ring 14 is used as a reference, the heat shield ring is used as a reference. It can be seen that there is no significant difference in the heat insulating properties between the 10B and the heat shield ring 12.

On the other hand, the groove portion 34B provided in the heat shield ring 10B and the groove portion 36 provided in the heat shield ring 12 are the same in the maximum opening width, the maximum groove depth and the number of groove portions, and the difference between the two is that of the groove portion. Only the cross-sectional shape and the resulting cross-sectional area (volume of the adiabatic air layer). The cross-sectional area of the groove portion 34B (volume of the adiabatic air layer) is about ½ of the cross-sectional area of the groove portion 36 (volume of the adiabatic air layer). That is, from the simulation analysis results shown in FIGS. 5 (B), 6 (B), and 7 (B), it may not always be possible to say that the heat insulating property is simply improved in proportion to the volume of the insulated air layer. It turns out. Further, from these results, the heat insulating property is the maximum opening width of the grooves 34B and 36 rather than the volume of the heat insulating air layer, in other words, the heat conduction path from the heat shield rings 10B and 12 to the cylinder liner 102 side. It is considered that the cross-sectional length of the flat portion 32 is substantially dependent on the cross-sectional length.

Here, when the groove portion 36 having a rectangular cross-sectional shape 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 groove portion is more than the groove portion 36. The cross-sectional area (volume of the adiabatic air layer) of 34A, 34B, 34C, and 34D is smaller, and the material portion (actual meat portion) constituting the heat shield ring 10 increases as the cross-sectional area becomes smaller. become.

From these facts, the groove portions 34A, 34B, 34C, and 34D having the first to fourth cross-sectional shapes are based on the groove portion 36 having the same maximum opening width and maximum groove depth and having a rectangular cross-sectional shape. (A) While exhibiting a heat insulating effect almost the same as that of the groove portion 36, in addition to the effect of (b) improving the strength of the heat shield ring 10 due to the difference in the cross-sectional shape of the groove portion with respect to the groove portion 36, (c). It is considered that the heat shield ring 10 also has an effect of improving the strength of the heat shield ring 10 by increasing the actual meat portion with respect to the groove portion 36.

Next, a more preferable form of the heat shield 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, and FIG. 9 is an enlarged cross-sectional view showing an example of the groove portion 34B having the second cross-sectional shape. The cross-sectional shape of the groove portion 34A is a V-shaped cross-sectional shape formed only by two straight lines 40A and 40B and one corner portion 42 which is an intersection of these two straight lines 40A and 40B. It is a cross-sectional shape in which the vicinity of the corner portion 42 in the cross-sectional shape of the groove portion 34A is rounded to form a curved line 44.

Here, the angle θ1 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 V-shaped, but is preferably 45 degrees to 160 degrees, preferably 90 degrees. It is more preferably about 160 degrees, further preferably 120 degrees to 150 degrees, and particularly preferably 135 degrees to 145 degrees. In order to sufficiently secure the heat insulating properties of the heat shield rings 10A and 10B when the angle θ1 is less than 45 degrees, (a) the groove portions 34A and 34B provided on the outer peripheral surface 30 per the unit axial height of the ring-shaped member 20. It is necessary to increase the number or (b) increase the maximum groove depth Dr and the maximum opening width Wr of the groove portions 34A and 34B. However, in the case of (a) the former, the processing of the groove portions 34A and 34B becomes more complicated when the heat shield rings 10A and 10B are manufactured. Further, in the latter case (b), since the actual meat portion is significantly reduced, the strength of the heat shield rings 10A and 10B may be easily reduced. Further, when the angle θ1 exceeds 160 degrees, the thickness of the heat insulating air layer becomes extremely thin relative to the maximum opening width Wr, so that the heat insulating properties of the heat shield rings 10A and 10B may easily deteriorate. be.

On the other hand, the angle θ2A formed by the straight line 40A and the flat portion 32 and the angle θ2B formed by the straight line 40B and the flat portion 32 are not particularly limited as long as the desired angle θ1 can be obtained, but are usually set to the angle θ2A and the angle θ2B. Is preferably the same. In the examples shown in FIGS. 8 and 9, the angle θ2A and the angle θ2B are set to be the same. Further, (i) the angle θ2A and the angle θ2B are preferably 90 degrees to 170 degrees, more preferably 100 degrees to 170 degrees, still more preferably 120 degrees to 170 degrees, respectively. ii) The sum of the angles θ2A and the angle θ2B (θ2A + θ2B) is preferably 225 degrees to 340 degrees, more preferably 240 degrees to 320 degrees. Further, (iii) the absolute difference between the angle θ2A and the angle θ2B | θ2A-θ2B | is preferably 0 to 45 degrees, more preferably 0 to 30 degrees, further preferably 0 to 15 degrees, and 0 degrees. Most preferred.

When (a) the angle θ2A (or the angle θ2B) is 90 degrees or more and less than 100 degrees, and (b) | θ2A−θ2B | exceeds 30 degrees, the asymmetry of the cross-sectional shapes of the groove portions 34A and 34B becomes In addition to being larger, the straight line 40A (or straight line 40B) will be parallel or substantially parallel to the radial direction. In the groove portions 34A and 34B having such a cross-sectional shape, it may be difficult to process the groove portions 34A and 34B by cutting or the like. Therefore, from the viewpoint of facilitating the processing of the groove portions 34A and 34B, even within the range satisfying the above conditions (i) to (iii), other than the range satisfying the above conditions (a) and (b). , It is more preferable to appropriately select the angle θ2A and the angle θ2B. However, if necessary, such as when a processing means having excellent workability can be used or when there are other merits, the groove portions 34A and 34B satisfying the conditions (a) and (b) may be provided.

The radius of curvature 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 a groove portion 34C having a third cross-sectional shape. Here, FIG. 10A is an example showing a case where the cross-sectional shape of the groove portion 34C is a semicircular arc 50A (50) (2 × maximum groove depth Dr = maximum opening width Wr). FIG. 10B shows a case where the cross-sectional shape of the groove portion 34C is an arc 50B (50) curved more loosely than the semicircular arc 50A (2 × maximum groove depth Dr <maximum opening width Wr). Case) is an example shown.

FIG. 11 is an enlarged cross-sectional view showing an example of a groove portion 34D having a fourth cross-sectional shape (U-shaped cross section). The groove portion 34D having a U-shaped cross section has a cross-sectional shape obtained by combining an arc 50 as illustrated in FIG. 10 and two straight lines 52 extending from both ends of the arc 50 toward the outer peripheral side of the heat shield ring 10D. ..

In the heat shield ring 10 having the groove portion 34 and the groove portion 34 exemplified in FIGS. 1 to 4 and FIGS. 8 to 11, it is preferable that at least one of the following formulas (1) to (4) is satisfied, and any two of them are satisfied. It is more preferable to fill one at the same time, further preferably to fill any three at the same time, and particularly preferably to fill all four at the same time.

-Equation (1) 0.85 ≧ Sr / (Dr × Wr) ≧ 0.5
・ Equation (2) 0.41 ≧ Dr / Wr
・ Equation (3) 0.57 ≧ Dr / Tr
・ Equation (4) 0.55 ≧ Fr / Hr

Here, the meaning of each numerical parameter in the equations (1) to (4) is as follows.
Dr: Maximum groove depth (mm) of the groove 34
Wr: Maximum opening width (mm) of the groove 34 in the axial direction of the ring-shaped member 20.
Sr: Cross-sectional area (mm ² ) of the groove 34 in a cross section orthogonal to the circumferential direction of the ring-shaped member 20.
Tr: Radial thickness (mm) of the ring-shaped member 20
Fr: Length (mm) of the flat portion 32 in the axial direction of the ring-shaped member 20
Hr: Axial height (mm) of the ring-shaped member 20

The length Fr of the flat portion 32 means the total length of the lengths Fr1 to Frn of the individual flat portions 32. For example, in the heat shield ring 10 shown in FIGS. 1 to 4, the flat portion 32 located on the combustion chamber side in the axial direction of the ring-shaped member 20, the flat portion 32 located in the central portion, and the flat portion 32 located on the crank chamber side are located. There are a total of three flat portions 32, which are flat portions 32. Therefore, the total value of the lengths Fr1, Fr2, and Fr3 of these three flat portions 32 is defined as the length Fr of the flat portion 32.

Here, for Sr / (Dr × Wr) shown in the equation (1), when the value is 1, it means that the cross-sectional shape is a rectangular groove portion 36, and when the value is 0.5, it means that the cross-sectional shape is a rectangular groove portion 36. , Means that the cross-sectional shape is a V-shaped groove 34A, and as the value increases from 0.5 to 1, the cross-sectional shape of the groove changes from V-shaped (first cross-sectional shape) to V-shaped. It sequentially changes into a second cross-sectional shape in which the corners of the shape are rounded into a curved line, an arc shape (third cross-sectional shape), a U-shape (fourth cross-sectional shape), and a square shape. When the formula (1) is satisfied, it is more possible to obtain the heat shield ring 10 having improved strength while maintaining substantially the same heat insulating property as the heat shield ring 12 having the groove portion 36 having a rectangular cross section. It will be easy. From the viewpoint of further improving the strength, Sr / (Dr × Wr) is more preferably 0.50 to 0.84, further preferably 0.53 to 0.70, and 0.54 to 0.68. Especially preferable.

Further, Dr / Wr shown in the formula (2) is a parameter meaning the aspect ratio of the groove portion 34, and Dr / Tr shown in the formula (3) means the depth ratio of the groove portion 34 to the heat shield ring 10. It is a parameter. When the formula (2) is satisfied, it is more possible to obtain the heat shield ring 10 having improved strength while maintaining substantially the same heat insulating property as the heat shield ring 12 having the groove portion 36 having a rectangular cross section. It will be easy. The same applies to the case where the equation (3) is satisfied.
The lower limit of Dr / Wr is not particularly limited, but is preferably 0.10 or more in practical use, and the lower limit of Dr / Tr is not particularly limited, but is preferably 0.15 or more in practical use. The Dr / Wr is more preferably 0.16 to 0.41 and even more preferably 0.16 to 0.21 from the viewpoint of achieving both heat insulating properties and strength in a well-balanced manner. Further, regarding Dr / Tr, 0.22 to 0.57 is more preferable, and 0.22 to 0.29 is further preferable, from the viewpoint of achieving both heat insulating properties and strength in a well-balanced manner.

Further, Fr / Hr shown in the equation (4) means the ratio of the length Fr of the flat portion 32 to the axial height Hr of the heat shield ring 10. Considering that the ratio of the cutout portion (chamfered portion) 38 to the axial height Hr is relatively very small, Fr / Hr is ΣWr / Hr (maximum opening width Wr with respect to the axial height Hr). It can also be said to be the inverse function of the sum ratio). When the formula (4) is satisfied, it is possible to obtain a heat shield ring 10 having substantially the same degree of heat insulation as that of the heat shield ring 12 having a groove portion 36 having a rectangular cross-sectional shape, but with greatly improved strength. It will be easier. The lower limit of Fr / Hr is not particularly limited, but practically, it is preferably 0.10 or more. Further, Fr / Hr is more preferably 0.18 or more and less than 0.37 when it is desired to further improve the heat insulating property rather than the strength, and 0.37 to 0. It is more preferably 55.

Further, in the heat shield ring 10 of the present embodiment, it is also preferable to satisfy the following formula (5) from the viewpoint of suppressing the decrease in the strength of the heat shield ring 10.
-Equation (5) Tr-Dr ≧ 1.0 mm

The material of the ring-shaped member 20 constituting the heat shield ring 10 of the present embodiment is not particularly limited, and is, for example, iron, iron alloy (heat resistant steel such as SUH, stainless steel such as SUS, cast iron (particularly with cylinder liner 102). (Cast iron of the same material), etc.), nickel alloy (Inconel, etc.) can be mentioned. It was

Further, the external dimensions of the ring-shaped member 20 constituting the heat shield ring 10 of the present embodiment are not particularly limited, but in general, the inner diameter is preferably 84 mm to 247 mm, more preferably 107 mm to 234 mm. It is preferable that the thickness is 111 mm to 147 mm, the radial thickness Tr is preferably 1.5 mm to 8 mm, the radial thickness Tr is more preferably 1.5 mm to 3.0 mm, and the axial height Hr is 5. It is preferably 0 mm to 70.0 mm, 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 for example, the maximum opening width Wr is about 1.0 mm to 40 mm. The maximum groove depth Dr is preferably about 0.2 mm to 4.0 mm.

The number of groove portions 34 provided on the outer peripheral surface 30 in the cross section orthogonal to the circumferential direction of the ring-shaped member 20 is not particularly limited, and any number can be selected as long as it is one or more per the entire axial height of the ring-shaped member 20. .. However, the number of groove portions 34 is more preferably 2 to 5 per 10 mm in axial height of the ring-shaped member 20, further preferably 2 to 3, and particularly preferably 2. When the number of the groove portions 34 is one per the entire axial height of the ring-shaped member 20 and the equation (4) is to be further satisfied, both sides of the one groove portion 34 in the axial direction of the ring-shaped member 20. Stress tends to concentrate on the two narrow flat portions 32 located in. That is, from the viewpoint of ensuring the strength of the heat shield ring 10, it tends to be difficult to appropriately disperse the stress in the axial direction of the ring-shaped member 20. Further, when the number of the groove portions 34 is 6 or more per 10 mm of the axial height of the ring-shaped member 20, the width (axis) of the flat portion 32 located between the two adjacent groove portions 34 in the axial direction of the ring-shaped member 20. Directional length) becomes narrower. Therefore, when the groove portion 34 is formed by cutting, the flat portion 32 is likely to be damaged.

The heat shield ring 10 of the present embodiment is a member used for the purpose of reducing the heat loss of the internal combustion engine, but in addition to this purpose, the purpose is to scrape off the carbon adhering to the top land of the piston. It may also be used as a member (carbon scraper ring). When the heat shield ring 10 is also used as a carbon scraper ring, the inner diameter of the ring-shaped member 20 constituting the heat shield ring 10 is the inner diameter of the cylinder liner 102 to which the heat shield ring 10 is mounted (the portion where the heat shield ring 10 is mounted). It is set slightly smaller than the inner diameter of the part on the crank chamber side). On the other hand, when the heat shield ring 10 of the present embodiment is not used as a carbon scraper ring, the inner diameter of the ring-shaped member 20 constituting the heat shield ring 10 is the inner diameter of the cylinder liner 102 to which the heat shield ring 10 is mounted (shielding). The inner diameter at the portion on the crank chamber side of the portion where the heat ring 10 is mounted) may be substantially equal to or larger than this.

Further, the surface of the ring-shaped member 20 constituting the heat shield ring 10 of the present embodiment may be subjected to various surface treatments or various film formations may be formed, if necessary. For example, a thermal spraying film formed by a thermal spraying treatment, a manganese phosphate film formed by a parfoss treatment, or the like can be formed on the surface of the ring-shaped member 20. These films may be selectively formed on a part of the surface of the ring-shaped member 20 (outer peripheral surface 30, inner peripheral surface 60, etc.) or the entire surface of the ring-shaped member 20 may be formed, although it depends on the method of forming the film. It can be formed to cover. Since the thermal spraying film and the manganese phosphate film are generally excellent in heat insulating properties, they are formed on at least the outer peripheral surface 30 of the ring-shaped member 20 from the viewpoint of improving the heat insulating properties of the heat shield ring 10. preferable.

The heat shield ring 10 of the present embodiment can be used in any type of internal combustion engine as long as it is an internal combustion engine provided with a cylinder liner to which the heat shield ring 10 can be mounted. Typical examples of such an internal combustion engine include a gasoline engine and a diesel engine. When the heat shield ring 10 of the present embodiment is used in a diesel engine in which carbon is likely to be generated in the combustion chamber, it is preferable that the heat shield ring 10 of the present embodiment is also used as carbon scraper ring.

<Internal combustion engine>
The internal combustion engine of the present embodiment includes at least a cylinder liner and a heat shield ring 10 of the present embodiment. 1 to 4 are schematic cross-sectional views showing an example of the internal combustion engine 200A (200) of the present embodiment. The internal combustion engine 200A shown in FIGS. 1 to 4 includes at least a cylinder liner 102 and a heat shield ring 10 of the present embodiment. The cylinder liner 102 has a cylindrical member 120, and the inner peripheral surface 130 of the cylindrical member 120 has a first region 130A near one end side (combustion chamber side) in the axial direction of the cylindrical member 120 and a vicinity of one end side. It is composed of a second region 130B other than the above. Further, the inner diameter in the first region 130A is set to be larger than the inner diameter in the second region 130B. The heat shield ring 10 is fitted in a portion where the inner peripheral surface 130 of the cylinder liner 102 is partially recessed toward the outer peripheral side, that is, in the first region 130A of the cylinder liner 102.

FIG. 12 is a schematic cross-sectional view showing another example of the internal combustion engine of the present embodiment, and is a diagram showing an example of the internal combustion engine 200 provided with the heat shield ring 10 of the present embodiment that also functions as carbon scraper ring. .. The internal combustion engine 200D (200) shown in FIG. 12 has a cylinder liner 102 similar to that illustrated in FIGS. 1 to 4, and a heat shield ring of the present embodiment fitted in the first region 130A of the cylinder liner 102. It has at least 10E (10). Here, the heat shield ring 10E shown in FIG. 12 is a member having the same dimensions and shape as the heat shield ring 10B shown in FIG. 2, except that the inner diameter thereof is smaller than the inner diameter of the heat shield ring 10B shown in FIG. be. In the internal combustion engine 200D shown in FIG. 12, the inner diameter of the ring-shaped member 20 constituting the heat shield ring 10E is smaller than the inner diameter of the cylindrical member 120 constituting the cylinder liner 102 in the second region 130B. Therefore, the inner peripheral surface 60 of the ring-shaped member 20 is positioned so as to protrude from the central axis side of the cylinder liner 102 with respect to the second region 130B of the cylinder liner 102. Therefore, when the carbon 400 adheres to the outer peripheral surface of the top land 310 of the piston 300, the carbon 400 is scraped off by the heat shield ring 10E as the piston 300 moves toward the top dead center in the cylinder liner 102. Will be done. The inner diameter of the ring-shaped member 20 constituting the heat shield 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 FIGS. 1 to 4, the inner peripheral surface 60 of the ring-shaped member 20 constituting the heat shield rings 10A, 10B, 10C, and 10D and the second region 130B of the cylinder liner 102 are surfaces. It is one. That is, the inner diameter of the second region 130B and the inner diameter of the ring-shaped member 20 are the same. Therefore, in the internal combustion engine 200A, the heat shield rings 10A, 10B, 10C, and 10D do not have a function as carbon scraper ring. It was

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

The inner peripheral surface 130 of the cylindrical member 120 constituting the cylinder liner 102 may be subjected to various surface treatments or various film formations may be formed, if necessary. For example, a thermal spraying film formed by a thermal spraying treatment, a manganese phosphate film formed by a parfoss treatment, or the like can be formed on the inner peripheral surface 130 of the cylindrical member 120. These coatings may be selectively formed on a part of the inner peripheral surface 130 of the cylindrical member 120 (first region 130A, second region 130B, etc.) or the inner peripheral surface 130, depending on the method of forming the coating. It can be formed so as to cover the whole. Since the thermal spraying film and the manganese phosphate film are generally excellent in heat insulating properties, they are formed in at least the first region 130A from the viewpoint of improving the heat insulating properties in the vicinity of the portion where the heat shield ring 10 is attached. Is preferable.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples shown below.

Regarding the heat shield rings of Examples 1 to 9 and Comparative Example 1, the parameters shown in the formulas (1) to (4): Sr / (Dr × Wr), Dr / Wr, Dr / Tr, and Fr / Hr are shielded. A simulation analysis was performed on the fluctuation tendency of the inner peripheral surface temperature of the heat ring and the maximum displacement in the radial direction of the groove. The results are shown in Tables 1 to 3. In each of the examples and comparative examples, the external dimensions of the heat shield ring, the number of grooves, and the material are all the same. In addition, the unit of dimensions of each part of the heat shield ring shown in the table is mm. Further, the two grooves are provided at equal intervals with respect to the axial direction of the heat shield ring as illustrated in FIG. The larger the value of the inner peripheral surface temperature, the better the heat insulating property of the heat shield ring, and the smaller the value, the better the heat insulating property of the heat shield ring. This is an evaluation item that means that the generated stress is small and fatigue fracture of the heat shield ring is unlikely to occur.

The simulation analysis shown in Tables 1 to 3 was carried out using commercially available strength and thermal analysis software. In the simulation analysis, the material of the heat shield ring and the cylinder liner used in combination with it is assumed to be cast iron (FC250), and the general in-cylinder pressure and combustion heat in the internal combustion engine are applied from the inner peripheral side of the heat shield ring. It worked and the ambient temperature was assumed to be room temperature.

Here, Table 1 shows the results of evaluating the inner peripheral surface temperature and the maximum displacement in the groove radial direction with respect to Sr / (Dr × Wr) when the maximum opening width Wr and the maximum groove depth Dr of the groove are the same. Shows. When the maximum opening width Wr and the maximum groove depth Dr of the groove portion are the same, changing the value of Sr / (Dr × Wr) is also synonymous with changing the shape of the groove portion, and the cross-sectional shape is quantitatively changed. It can be said that it is defined as a parameter. Therefore, it can be said that Table 1 is the result of evaluating the inner peripheral surface temperature and the maximum displacement amount in the radial direction of the groove portion with respect to the cross-sectional shape of the groove portion.

Table 2 shows the results of evaluating the inner peripheral surface temperature and the maximum displacement in the radial direction of the groove with respect to the maximum groove depth Dr when the cross-sectional shape of the groove and the maximum opening width Wr are the same. However, the influence of the maximum groove depth Dr on the heat insulating property and the mechanical strength is strongly influenced not by the absolute value of the maximum groove depth Dr but by the relative ratio of the maximum groove depth Dr to the entire heat shield ring. it is conceivable that. Therefore, in Table 2, the maximum groove depth when the maximum opening width Wr, which is the main axial dimension of the heat shield ring, and the radial thickness Tr, which is the main radial dimension of the heat shield ring, are used as reference values. The results of evaluating the ratio of Dr, that is, the inner peripheral surface temperature and the maximum displacement in the groove radial direction with respect to Dr / Wr (aspect ratio of the groove) and Dr / Tr (depth ratio of the groove to the heat shield ring) are shown. ..

Table 3 shows the results of evaluating the inner peripheral surface temperature and the maximum displacement in the groove radial direction with respect to the flat portion length Fr (or the maximum opening width Wr which can be said to be a substantially inverse function of the flat portion length Fr). However, it is considered that the influence of the flat portion length Fr on the heat insulating property and the mechanical strength is not strongly influenced by the absolute value of the flat portion length Fr but by the relative ratio of the flat portion length Fr to the entire heat shield ring. .. Therefore, in Table 3, the ratio of the flat portion length Fr when the axial height Hr, which is the main axial dimension of the heat shield ring, is used as a reference value, that is, the inner peripheral surface temperature and the groove portion diameter with respect to Fr / Hr. The result of evaluating the maximum displacement in the direction is shown. Fr / Hr can be said to be the occupancy ratio of the flat portion in the axial direction.

10, 10A, 10B, 10C, 10D, 10E: Heat shield ring 12: Heat shield ring 14: Heat shield ring 20: Ring-shaped member 30: Outer peripheral surface 32: Flat portion 34, 34A, 34B, 34C, 34D: Groove portion 36 : Groove 36B: Groove bottom surface 36C: Corner 38: Notch (chamfer)
40A, 40B: Straight line 42: Corner 44: Curve 50, 50A, 50B: Arc 52: Straight line 60: Inner peripheral surface 102: Cylinder liner 120: Cylindrical member 130: Inner peripheral surface 130A: First region (combustion chamber side) Inner peripheral surface near the end of
130B: Second region 200, 200A, 200D: Internal combustion engine 300: Piston 310: Topland 400: Carbon

Claims (10)

1. Has a ring-shaped member,
   In a cross section orthogonal to the circumferential direction of the ring-shaped member, the outer peripheral surface of the ring-shaped member has a flat portion parallel to the axial direction of the ring-shaped member and an inner peripheral side of the ring-shaped member with respect to the flat portion. Including the groove that is dented in
   The cross-sectional shape of the groove is
   (1) A V-shaped first cross-sectional shape formed only from two straight lines and one corner portion that is an intersection of the two straight lines.
   (2) A second cross-sectional shape in which the vicinity of the corners in the first cross-sectional shape is rounded to form a curved line.
   (3) A third cross-sectional shape formed only from an arcuate curve, and
   (4) U-shaped fourth cross-sectional shape,
   A heat shield ring for a cylinder liner, characterized in that it is one or more selected from the group consisting of.
2. The heat shield ring for a cylinder liner according to claim 1, wherein the angle formed by the two straight lines in the first cross-sectional shape and the second cross-sectional shape is 45 degrees to 160 degrees.
3. The heat shield ring for a cylinder liner according to claim 1 or 2, wherein the following formula (1) is satisfied.
   -Equation (1) 0.85 ≧ Sr / (Dr × Wr) ≧ 0.5
   [In the formula (1), Sr means the cross-sectional area (mm ² ) of the groove portion in the cross section orthogonal to the circumferential direction of the ring-shaped member, and Dr means the maximum groove depth (mm) of the groove portion. , Wr means the maximum opening width (mm) of the groove portion in the axial direction of the ring-shaped member. ]
4. The heat shield ring for a cylinder liner according to any one of claims 1 to 3, wherein the heat shield ring for a cylinder liner is characterized by satisfying the following formula (2).
   ・ Equation (2) 0.41 ≧ Dr / Wr
   [In the formula (2), Dr means the maximum groove depth (mm) of the groove portion, and Wr means the maximum opening width (mm) of the groove portion in the axial direction of the ring-shaped member. ]
5. The heat shield ring for a cylinder liner according to any one of claims 1 to 4, wherein the heat shield ring for a cylinder liner is characterized by satisfying the following formula (3).
   ・ Equation (3) 0.57 ≧ Dr / Tr
   [In the formula (3), Dr means the maximum groove depth (mm) of the groove portion, and Tr means the radial thickness (mm) of the ring-shaped member. ]
6. The heat shield ring for a cylinder liner according to any one of claims 1 to 5, which satisfies the following formula (4).
   ・ Equation (4) 0.55 ≧ Fr / Hr
   [In the formula (4), Fr means the length (mm) of the flat portion in the axial direction of the ring-shaped member, and Hr means the axial height (mm) of the ring-shaped member. ]
7. The heat shield ring for a cylinder liner according to any one of claims 1 to 6, which is a carbon scraper ring.
8. It has a cylindrical member, and the inner peripheral surface of the cylindrical member is composed of a first region in the vicinity of one end side in the axial direction of the cylindrical member and a second region other than the vicinity of the one end side. A cylinder liner having an inner diameter in one region larger than the inner diameter in the second region.
   A heat shield ring having a ring-shaped member and fitted to the first region of the cylinder liner is provided at least.
   In a cross section orthogonal to the circumferential direction of the ring-shaped member, the outer peripheral surface of the ring-shaped member has a flat portion parallel to the axial direction of the ring-shaped member and an inner peripheral side of the ring-shaped member with respect to the flat portion. Including the groove that is dented in
   The cross-sectional shape of the groove is
   (1) A V-shaped first cross-sectional shape formed only from two straight lines and one corner portion that is an intersection of the two straight lines.
   (2) A second cross-sectional shape in which the vicinity of the corners in the first cross-sectional shape is rounded to form a curved line.
   (3) A third cross-sectional shape formed only from an arcuate curve, and
   (4) U-shaped fourth cross-sectional shape,
   An internal combustion engine characterized by being one or more selected from the group consisting of.
9. The internal combustion engine according to claim 8, wherein the inner diameter of the ring-shaped member is smaller than the inner diameter of the second region.
10. The internal combustion engine according to claim 8 or 9, which is a diesel engine.

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