JP7157262B2 - Heat shield rings for cylinder liners and internal combustion engines - Google Patents

Description

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

Japanese Utility Model Publication No. 05-12527 Japanese Patent Application Laid-Open No. 2007-32401

However, a conventional heat shield ring having grooves for forming an insulating air layer may be damaged due to the grooves when used in an internal combustion engine.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat shield ring for a cylinder liner which is less likely to be damaged due to grooves, and an internal combustion engine using the same.

The above objects are achieved by the present invention described below. i.e.
The heat shield ring for a cylinder liner of the present invention has a ring-shaped member, and in a cross section perpendicular 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 toward the inner peripheral side of the ring-shaped member from the flat portion, and the cross-sectional shape of the groove portion is (1) formed only from two straight lines and one corner portion that is the intersection of the two straight lines. (2) a second cross-sectional shape in which the vicinity of the corner of the first cross-sectional shape is rounded to form a curve; (3) a third cross-sectional shape formed only from an arc-shaped curve and (4) a U-shaped fourth cross-sectional shape.

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

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

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

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

Another embodiment of the heat shield ring for cylinder liner of the present invention preferably satisfies the following formula (4).
・Formula (4) 0.55≧Fr/Hr
[In 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 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 mm. .0 mm to 70.0 mm.

Another embodiment of the heat shield ring for cylinder liner of the present invention is preferably a 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 in the axial direction of the cylindrical member and a second region other than near the one end. and at least a cylinder liner having a larger inner diameter in the first region than the inner diameter in the second region, and a heat shield ring having a ring-shaped member and fitted to the first region of the cylinder liner, 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, a groove portion recessed toward the inner peripheral side of the ring-shaped member from the flat portion, and 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 that is the intersection of the two straight lines, (2) the 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 arc-shaped curves, and (4) a fourth U-shaped cross-sectional shape It is characterized by being at least one 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.

Advantageous Effects of Invention According to the present invention, it is possible to provide a cylinder liner heat shield ring that is less likely to be damaged due to grooves, and an internal combustion engine using the same.

1 is a schematic cross-sectional view showing an example of a heat shield ring for a cylinder liner of the present embodiment and an example of an internal combustion engine of the present embodiment; FIG. FIG. 4 is a schematic cross-sectional view showing another example of the heat shield ring for cylinder liner of the present embodiment and another example of the internal combustion engine of the present embodiment; FIG. 4 is a schematic cross-sectional view showing another example of the heat shield ring for cylinder liner of the present embodiment and another example of the internal combustion engine of the present embodiment; FIG. 4 is a schematic cross-sectional view showing another example of the heat shield ring for cylinder liner of the present embodiment and another example of the internal combustion engine of the present embodiment; FIG. 5 is a diagram showing an example of analysis results obtained by simulating stress distribution and temperature distribution in a conventional heat shield ring for a cylinder liner provided with grooves having a rectangular cross section. Here, FIG. 5A is a cross-sectional view showing the cross-sectional shape of the heat insulating ring used in the simulation analysis, and FIG. 5(C) is a diagram showing the stress distribution of the heat shield ring shown in FIG. 5(A). FIG. FIG. 4 is a diagram showing an example of analysis results obtained by simulating stress distribution and temperature distribution in the heat shield ring for cylinder liner of the present embodiment. Here, FIG. 6A is a cross-sectional view showing the cross-sectional shape of the heat insulating ring used in the simulation analysis, and FIG. 6(C) is a diagram showing the stress distribution of the heat shield ring shown in FIG. 6(A). FIG. FIG. 10 is a diagram showing an example of analysis results obtained by simulating temperature distribution in a heat shield ring having no groove. Here, FIG. 7A is a cross-sectional view showing the cross-sectional shape of the heat insulating ring used in the simulation analysis, and FIG. FIG. 4 is a diagram showing distribution; 4 is an enlarged cross-sectional view showing an example of a groove having a first cross-sectional shape; FIG. FIG. 10 is an enlarged cross-sectional view showing an example of a groove portion having a second cross-sectional shape; FIG. 11 is an enlarged cross-sectional view showing an example of a groove having a third cross-sectional shape; Here, FIG. 10A is a diagram showing a case where the cross-sectional shape of the groove is a semicircular arc, and FIG. It is a figure which shows the case where it is a curved circular arc. FIG. 11 is an enlarged cross-sectional view showing an example of a groove having a fourth cross-sectional shape; FIG. 4 is a schematic cross-sectional view showing another example of the heat shield ring for cylinder liner of the present embodiment and another example of the internal combustion engine of the present 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") according to the present embodiment, and the structure of the cross section orthogonal to the circumferential direction of the heat shield ring. It is a figure showing about. 1 to 4 show the state in which the heat shield ring is attached to the inner peripheral surface of the cylinder liner in the vicinity of the end on the combustion chamber side. In addition, the Y direction shown in FIGS. 1 to 4 and other drawings means the 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 the direction of the heat insulating 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 in a cross section (paper surface in the drawing) perpendicular to the circumferential direction of the ring-shaped member 20, the outer peripheral surface 30 of the ring-shaped member 20 is It includes a flat portion 32 parallel to the axial direction of the ring-shaped member 20 and a groove portion 34 recessed toward the inner peripheral side of the ring-shaped member 20 from the flat portion 32 .

In the example shown in FIGS. 1 to 4, the heat shield ring 10 is attached to the inner peripheral surface 130A (first region) near the end of the cylinder liner 102 on the combustion chamber side. Therefore, the flat portion 32 of the outer peripheral surface 30 is in contact with the inner peripheral surface 130A of the cylinder liner 102 . 1 to 4, two groove portions 34 and three flat portions 32 are provided, and one groove portion 34 is positioned between the two flat portions 32. As shown in FIG. Furthermore, in the example shown in FIGS. 1 to 4, the outer peripheral surface 30 is provided with notch portions (chamfered portions) 38 on both axial end sides. However, the notch portion (chamfered portion) 38 can be omitted. The grooves 34 are preferably provided continuously in the circumferential direction of the heat shield ring 10, but may be provided discontinuously. Further, when the grooves 34 are provided continuously in the circumferential direction of the heat shield ring 10, the grooves 34 may be provided continuously so as to be parallel to the circumferential direction, or the grooves 34 may intersect the circumferential direction. It may be continuously provided so as to form a constant angle (for example, an angle of more than 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 ( 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. 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 arcuate curves. A groove portion 34D (34) having a U-shaped cross-sectional shape (fourth cross-sectional shape) is provided in the outer peripheral surface 30 of the heat shield ring 10D (10) shown in FIG. In the heat shield ring 10 shown in FIGS. 1 to 4, the grooves 34 are arranged at regular intervals (Fr2) with respect to the axial direction of the ring-shaped member 20. As shown in FIG. However, the interval (Fr2) between two grooves 34 adjacent to each other in the axial direction may be minimized and a large number of grooves 34 may be provided in a sawtooth shape.

In the heat insulating ring 10 of the present embodiment, the cross-sectional shape of the groove portion 34 provided on the outer peripheral surface 30 is different from the above-described 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 consisting of may be used. For example, if only one groove portion 34 is provided on the outer peripheral surface 30, the cross-sectional shape of the groove portion 34 is the first cross-sectional shape, the second cross-sectional shape, the third cross-sectional shape and the fourth cross-sectional shape. Any one selected from the group consisting of In addition, if the number of grooves 34 provided on the outer peripheral surface 30 is two or more, the cross-sectional shape of the grooves 34 is (a) as illustrated in FIGS. may be any one selected from the group consisting of a cross-sectional shape, a second cross-sectional shape, a third cross-sectional shape and a fourth cross-sectional shape; There may be.

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

First, during the operation of the internal combustion engine, cylinder internal 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 an insulating air layer, it is unavoidable that local stress concentration tends to occur in the groove and its vicinity.

Therefore, the present inventors studied the stress distribution in the cross section of the heat shield ring in order to investigate the cause of susceptibility to breakage due to the groove in the conventional heat shield ring provided with a groove having a rectangular cross section. FIG. 5 is a diagram showing an example of analysis results obtained by simulating stress distribution and 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 attached to the inner peripheral surface 130A of the cylinder liner 102. FIG. The outer peripheral surface 30 of the heat shield ring 12 shown in FIG. 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 insulating ring 12 shown in FIG. 5(A), and FIG. 102 is a diagram showing the temperature distribution of 102. FIG.

In the heat shield ring 12 and the cylinder liner 102 shown in FIG. 5(A), the dimensions of the main parts are set as follows. 5(A) and FIG. 6(A), which will be described later, differ only in the dimensions and shapes of the groove portion 36 and the groove portion 34B. 7A, which will be described later, is different only in the presence or absence of grooves 36 and 34B.
・Radial 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 that constitutes the cylinder liner 102 (however, the portion corresponding to the first region 130A) is 2.7 mm.
・The axial length of the cylindrical member that constitutes the cylinder liner 102 (however, the portion corresponding to the first region 130A) is 9.9 mm

The simulation analysis shown in FIG. 5 was performed 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 cylinder pressure and combustion heat in an internal combustion engine act from the inner peripheral side of the heat shield ring 12, In addition, the ambient temperature was carried out under conditions assuming room temperature. Here, in FIG. 5(C), the gradation display indicated by white to black means the magnitude of the stress, the whiter the higher the stress, and the darker the lower the stress. An explanation of FIG. 5B will be given later. 5(A) and 5(B), illustration of the back side of the cross section of the heat shield ring 12 is omitted.

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

Based on the above knowledge, in the cross-sectional shape of the groove, (a) the number of corners 36C that cause stress concentration is reduced or eliminated, and (b) the groove bottom that causes stress concentration It is important to form the central portion of 36B in an arch shape or a V-shape that protrudes in the inner peripheral direction, thereby dispersing the strong stress acting locally on the central portion of the groove bottom surface 36B. Conceivable. Accordingly, the inventors found the heat shield ring 10 of the present embodiment having the grooves 34 illustrated in FIGS. 1 to 4. FIG. 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. In addition, the grooves 34B, 34C, and 34D having the second to fourth cross-sectional shapes do not have corners 36C, and the central portions of the groove bottom surfaces of the grooves 34B, 34C, and 34D are convex in the inner circumferential direction. It has an arch shape composed of curved curves.

FIG. 6 is a diagram showing an example of analysis results obtained by simulating stress distribution and 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 the heat shield ring 10B shown in FIG. FIG. 4 is a cross-sectional view of the same; 6(C) is a diagram showing the stress distribution of the heat insulating ring 10B shown in FIG. 6(A), and FIG. 6(B) shows the stress distribution of the heat insulating ring 10B shown in FIG. 102 is a diagram showing the temperature distribution of 102. FIG. The simulation analysis shown in FIG. 6 was performed under the same conditions as those of the simulation analysis shown in FIG. That is, the position, number, and area of the contact portions (flat portions 32) between the cylinder liner 102 and the heat shield rings 10B and 12, where the cylinder pressure is transmitted to the cylinder liner 102, are 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, the difference in stress distribution between FIG. 5(C) and FIG. 6(C) is considered to be substantially due to 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. be done. An explanation of FIG. 6B will be given later. In addition, in FIGS. 6A and 6B, illustration of the back side of the cross section of the heat shield ring 10B is omitted.

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

As is clear from FIG. 6(C), the heat shield ring 10B of the present embodiment also has a stress distribution, but no significant stress concentration portion as shown in FIG. 5(C) was confirmed. This result confirms that the grooves 34A, 34B, 34C, and 34D shown in FIGS. 1 to 4 are less likely to be damaged due to the grooves than the groove 36 shown in FIG.

The space (insulating air layer) surrounded by the groove and the cylinder liner is filled with a gas with extremely low thermal conductivity (air, combustion gas, or mixed gas). It greatly contributes to the performance of heat insulation. Based on this point, it is considered that a larger volume of the insulating air layer is more advantageous for improving the heat insulating property. However, when the present inventors examined the relationship between the volume of the insulating air layer and the heat insulating properties of the heat shield ring, there were cases where simply increasing the volume of the insulating air layer did not greatly improve the heat insulating properties. It turns out there is something. The reason will be explained below.

FIG. 7 is a diagram showing an example of an analysis result of simulating temperature distribution in a heat shield ring having no groove. FIG. 7A shows a state in which the heat shield ring 14 is attached to the inner peripheral surface 130A of the cylinder liner 102. FIG. The heat insulating ring 14 shown in FIG. 7(A) is similar in material and dimensions to the heat insulating ring 12 shown in FIG. 5(A) and the heat insulating ring 12 shown in FIG. It is the same member as the heat shield ring 10B shown in FIG. 7(B) is a diagram showing the temperature distribution of the heat shield 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 FIGS. 5 and 6, except that the heat shield ring 14 did not have grooves. Here, in FIGS. 5(B), 6(B) and 7(B), the gradation display indicated by white to black means the difference in temperature, the whiter the higher the temperature and the blacker the lower the temperature. means that

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

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

Further, referring to FIGS. 5B and 6B, the heat shield rings 10B and 12 have grooves 34B and 36 (insulating air layers), so that the heat shield rings 10B and 12 themselves are heat shielded. It has a higher temperature than the ring 14 . However, this causes the temperature on the cylinder liner 102 side to be lower. Here, when the heat insulating ring 10B and the heat insulating ring 12 are compared, although the heat insulating ring 10B is slightly inferior to the heat insulating ring 12 in heat insulating properties, when the heat insulating ring 14 is used as a reference, the heat insulating ring It can be seen that there is no significant difference in heat insulation between 10B and the heat shield ring 12 .

On the other hand, the grooves 34B provided in the heat shield ring 10B and the grooves 36 provided in the heat shield ring 12 have the same maximum opening width, maximum groove depth, and number of grooves, and the difference between the two is the number of grooves. It is only the cross-sectional shape and the resulting cross-sectional area (volume of the insulating air layer). The cross-sectional area of the groove portion 34B (the volume of the heat-insulating air layer) is approximately half the cross-sectional area of the groove portion 36 (the volume of the heat-insulating air layer). That is, from the simulation analysis results shown in FIGS. 5(B), 6(B), and 7(B), it may not necessarily be said that the heat insulation is simply proportional to the volume of the heat insulating air layer. It turns out. Also, 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 path of heat conduction from the heat shield rings 10B and 12 to the cylinder liner 102 side. It is believed that this substantially depends on the cross-sectional length of the flat portion 32 .

Here, when the groove portion 36 having a rectangular 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 groove portion is larger than the groove portion 36. 34A, 34B, 34C, and 34D have a smaller cross-sectional area (capacity of the heat-insulating air layer), and the smaller cross-sectional area increases the material portion (actual thickness portion) that constitutes the heat insulating ring 10. become.

From these facts, when the grooves 34A, 34B, 34C, and 34D having the first to fourth cross-sectional shapes are based on the rectangular cross-sectional groove 36 having the same maximum opening width and maximum groove depth, (a) While exhibiting approximately the same heat insulation effect as the groove 36, (b) the strength improvement effect of the heat shield ring 10 derived from the difference in the cross-sectional shape of the groove with respect to the groove 36, (c) It is considered that the increase in the actual thickness of the grooves 36 also has the effect of improving the strength of the heat insulating ring 10 .

Next, a more suitable form of the heat insulating ring 10 of this 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 from two straight lines 40A and 40B and one corner portion 42 that is the intersection of these two straight lines 40A and 40B. The cross-sectional shape of the groove portion 34A is a curved line 44 formed by rounding the vicinity of the corners 42 in the cross-sectional shape of the groove portion 34A.

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

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

If (a) the angle θ2A (or the angle θ2B) is 90 degrees or more and less than 100 degrees and (b) |θ2A−θ2B| Moreover, the straight line 40A (or the straight line 40B) is parallel or substantially parallel to the radial direction. The grooves 34A and 34B having such cross-sectional shapes may be difficult to process when forming the grooves 34A and 34B by cutting or the like. Therefore, from the viewpoint of facilitating the processing of the grooves 34A and 34B, even within the range satisfying the above conditions (i) to (iii), outside the range satisfying the above conditions (a) and (b), , the angle θ2A and the angle θ2B are appropriately selected. However, the grooves 34A and 34B satisfying the conditions (a) and (b) may of course be provided if necessary, such as when a processing means with excellent workability is available or when there are other merits.

The radius of curvature of 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 gently than the semicircular arc 50A (2×maximum groove depth Dr<maximum opening width Wr case).

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. .

In the heat shield ring 10 having the grooves 34 and the grooves 34 illustrated in FIGS. It is more preferable to satisfy all three at the same time, it is even more preferable to satisfy any three at the same time, and it is particularly preferable to satisfy all four at the same time.

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

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

The length Fr of the flat portion 32 means the total length of the lengths Fr1 to Frn of the individual flat portions 32. As shown in FIG. 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. There are a total of three flats 32 of flats 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. FIG.

Here, for Sr/(Dr×Wr) shown in the formula (1), when the value is 1, it means that the groove 36 has a rectangular cross-sectional shape, and when the value is 0.5, , means that the cross-sectional shape of the groove portion 34A is V-shaped, and as the value increases from 0.5 to 1, the cross-sectional shape of the groove portion changes from V-shaped (first cross-sectional shape) to V-shaped. A second cross-sectional shape with rounded corners, an arc shape (third cross-sectional shape), a U-shape (fourth cross-sectional shape), and a rectangular shape are sequentially changed. When formula (1) is satisfied, it is more desirable to obtain a heat insulating ring 10 having improved strength while maintaining approximately the same degree of heat insulation as compared to the heat insulating ring 12 having the groove portion 36 with a rectangular cross-sectional shape. easier. 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 0.54 to 0.68. Especially preferred.

Further, Dr/Wr shown in formula (2) is a parameter meaning the aspect ratio of the groove 34, and Dr/Tr shown in formula (3) means the depth ratio of the groove 34 to the heat shield ring 10. is a parameter. When formula (2) is satisfied, it is more desirable to obtain a heat insulating ring 10 having improved strength while maintaining approximately the same degree of heat insulation as compared to the heat insulating ring 12 having the groove portion 36 with a rectangular cross-sectional shape. easier. The same applies to the case where the formula (3) is satisfied.
Although the lower limit of Dr/Wr is not particularly limited, it is preferably 0.10 or more for practical use. Note that Dr/Wr is more preferably 0.16 to 0.41, and even more preferably 0.16 to 0.21, from the viewpoint of balancing heat insulation and strength. Also, Dr/Tr is more preferably 0.22 to 0.57, and even more preferably 0.22 to 0.29, from the viewpoint of balancing heat insulation and strength.

Furthermore, Fr/Hr shown in 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 (the maximum opening width Wr to the axial height Hr It can also be said to be an inverse function of the ratio of the sum of When the formula (4) is satisfied, it is possible to obtain the heat insulating ring 10 having substantially the same degree of heat insulation as the heat insulating ring 12 having the groove portion 36 with a rectangular cross section and having a significantly improved strength. easier. Although the lower limit of Fr/Hr is not particularly limited, it is preferably 0.10 or more in practice. Further, Fr/Hr is more preferably 0.18 or more and less than 0.37 when it is desired to improve heat insulation rather than strength, and 0.37 to 0.37 when it is desired to improve strength more than heat insulation. 55 is more preferred.

Moreover, the heat shield ring 10 of the present embodiment preferably satisfies the following formula (5) from the viewpoint of suppressing a decrease in the strength of the heat shield ring 10 .
・Formula (5) Tr−Dr≧1.0 mm

The material of the ring-shaped member 20 that constitutes the heat shield ring 10 of the present embodiment is not particularly limited. cast iron of the same material), etc.), and nickel alloys (Inconel, etc.).

In addition, the outer dimensions of the ring-shaped member 20 constituting the heat shield ring 10 of the present embodiment are not particularly limited, but generally the inner diameter is preferably 84 mm to 247 mm, more preferably 107 mm to 234 mm. It is preferably 111 mm to 147 mm, preferably has a radial thickness Tr of 1.5 mm to 8 mm, more preferably 1.5 mm to 3.0 mm, and has an axial height Hr of 5.0 mm. It is preferably 0 mm to 70.0 mm, more preferably 6.5 mm to 18.0 mm. Further, 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. and the maximum groove depth Dr is preferably about 0.2 mm to 4.0 mm.

The number of grooves 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 of grooves 34 can be selected as long as it is one or more for the entire height of the ring-shaped member 20 in the axial direction. . However, the number of grooves 34 is more preferably 2 to 5, more preferably 2 to 3, and particularly preferably 2 per 10 mm of the axial height of the ring-shaped member 20 . In the case where the number of grooves 34 is one for the entire axial height of the ring-shaped member 20, if the expression (4) is to be satisfied, both sides of one groove 34 in the axial direction of the ring-shaped member 20 Stress tends to concentrate on the two narrow flat portions 32 located at . That is, from the viewpoint of ensuring the strength of the heat shield ring 10, it is likely to be difficult to appropriately disperse the stress in the axial direction of the ring-shaped member 20. Further, when the number of groove portions 34 is 6 or more per 10 mm of the axial height of the ring-shaped member 20, the width of the flat portion 32 (axis direction length) becomes narrower. Therefore, the flat portion 32 is likely to be damaged when the groove portion 34 is formed by cutting.

The heat shield ring 10 of the present embodiment is a member used for the purpose of reducing heat loss in an internal combustion engine. It may also be used as a member (carbon scraper ring). When the heat insulating ring 10 is also used as a carbon scraper ring, the inner diameter of the ring-shaped member 20 constituting the heat insulating ring 10 is equal to the inner diameter of the cylinder liner 102 to which the heat insulating ring 10 is attached (the portion where the heat insulating ring 10 is attached). is set to be slightly smaller than the inner diameter of the portion 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 attached (shield The inside diameter at the portion closer to the crank chamber than the portion where the heat ring 10 is attached) may be substantially equal to or larger than this.

Moreover, 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 may be coated with various films as necessary. For example, a sprayed film formed by thermal spraying, a manganese phosphate film formed by Parphos processing, or the like can be formed on the surface of the ring-shaped member 20 . Depending on the method of forming the coating, these coatings may be selectively formed on a portion of the surface of the ring-shaped member 20 (the outer peripheral surface 30, the inner peripheral surface 60, etc.) or the entire surface of the ring-shaped member 20. It can be formed to cover. In addition, since the thermal spray film and the manganese phosphate film are generally excellent in heat insulation, they are formed at least on the outer peripheral surface 30 of the ring-shaped member 20 from the viewpoint of improving the heat insulation of the heat shield ring 10. preferable.

The heat shield ring 10 of this embodiment can be used in any type of internal combustion engine as long as it has a cylinder liner to which the heat shield ring 10 can be attached. Typical examples of such internal combustion engines include gasoline engines and diesel engines. When using the heat insulating ring 10 of the present embodiment in a diesel engine in which carbon is likely to be generated in the combustion chamber, the heat insulating ring 10 of the present embodiment is preferably used also as a carbon scraper ring.

<Internal combustion engine>
The internal combustion engine of this embodiment includes at least a cylinder liner and the heat shield ring 10 of this embodiment. 1 to 4 are schematic cross-sectional views showing an example of an internal combustion engine 200A (200) of this embodiment. An internal combustion engine 200A shown in FIGS. 1 to 4 includes at least a cylinder liner 102 and the 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 is divided into a first region 130A near one end side (combustion chamber side) of the cylindrical member 120 in the axial direction and a first region 130A near the one end side in the axial direction of the cylindrical member 120. and a second region 130B other than the Also, the inner diameter of the first region 130A is set to be larger than the inner diameter of 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, 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 this embodiment, showing an example of an internal combustion engine 200 provided with the heat shield ring 10 of this embodiment that also functions as a carbon scraper ring. . The internal combustion engine 200D (200) shown in FIG. 12 includes a cylinder liner 102 similar to that illustrated in FIGS. 10E(10). Here, the heat insulating ring 10E shown in FIG. 12 is a member having the same dimensions and shape as the heat insulating ring 10B shown in FIG. 2 except that its inner diameter is smaller than the inner diameter of the heat insulating 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 forming the heat shield ring 10E is smaller than the inner diameter of the cylindrical member 120 forming the cylinder liner 102 at the second region 130B. Therefore, the inner peripheral surface 60 of the ring-shaped member 20 is positioned so as to protrude from the second region 130</b>B of the cylinder liner 102 toward the central axis 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 insulating ring 10E when the piston 300 moves toward the top dead center in the cylinder liner 102. be done. The inner diameter of the ring-shaped member 20 that constitutes 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 planes. constitutes 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 function as carbon scraper rings.

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

Various surface treatments may be applied to the inner peripheral surface 130 of the cylindrical member 120 constituting the cylinder liner 102, or various coatings may be formed thereon, if necessary. For example, a sprayed film formed by thermal spraying, a manganese phosphate film formed by Parphos processing, or the like can be formed on the inner peripheral surface 130 of the cylindrical member 120 . Depending on the method of forming the coating, these coatings may be selectively formed on a portion of the inner peripheral surface 130 of the cylindrical member 120 (first region 130A, second region 130B, etc.), or may be formed on the inner peripheral surface 130. It can be formed to cover the whole. In addition, since the thermal sprayed film and the manganese phosphate film are generally excellent in heat insulation, they are formed at least in the first region 130A from the viewpoint of improving the heat insulation in the vicinity of the portion where the heat shield ring 10 is attached. is preferred.

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

For the heat shield rings of Examples 1 to 9 and Comparative Example 1, parameters shown in formulas (1) to (4): Sr/(Dr×Wr), Dr/Wr, Dr/Tr, Fr/Hr. A simulation analysis was carried out on the fluctuation trends of the inner surface temperature of the heat ring and the maximum radial displacement of the groove. The results are shown in Tables 1-3. It should be noted that the external dimensions, the number of grooves and the material of the heat shield ring are all the same in any of the examples and the comparative examples. In addition, the units of the dimensions of each part of the heat shield ring shown in the table are all mm. Furthermore, the two grooves were provided at equal intervals in the axial direction of the heat insulating ring as illustrated in FIG. 1 and the like. The inner peripheral surface temperature is an evaluation item that means that the larger the value, the better the heat insulating properties of the heat insulating ring. This is an evaluation item that means that the generated stress is small and the heat shield ring is unlikely to be fatigue-broken.

The simulation analyzes shown in Tables 1 to 3 were performed 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 was assumed to be cast iron (FC250), and the general in-cylinder pressure and combustion heat in an internal combustion engine were generated from the inner circumference of the heat shield ring. , and the ambient temperature was carried out under conditions assuming room temperature.

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

Table 2 shows the evaluation results of the inner peripheral surface temperature and the maximum radial displacement amount 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 effect of the maximum groove depth Dr on heat insulation and mechanical strength is strongly influenced by the relative proportion of the maximum groove depth Dr in the entire heat shield ring, not by the absolute value of the maximum groove depth Dr. 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 inner peripheral surface temperature and the maximum radial displacement amount of the groove with respect to the ratio of the depth Dr, that is, Dr/Wr (aspect ratio of the groove) and Dr/Tr (depth ratio of the groove with respect to the heat shield ring) are shown. .

Table 3 shows the evaluation results of the inner peripheral surface temperature and the maximum groove radial displacement 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, the influence of the flat portion length Fr on the heat insulating properties and mechanical strength is considered to be strongly influenced by the relative proportion of the flat portion length Fr in the entire heat shield ring, not by the absolute value of the flat portion length Fr. . 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 diameter with respect to Fr/Hr The results of evaluating the maximum directional displacement amount are 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 portions 34, 34A, 34B, 34C, 34D: groove portion 36 : Groove portion 36B : Groove bottom surface 36C : Corner portion 38 : Notch portion (chamfered portion)
40A, 40B: straight line 42: corner 44: curved line 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 (8)

having 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 includes a flat portion parallel to the axial direction of the ring-shaped member and an inner peripheral side of the ring-shaped member from the flat portion. a groove recessed 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 that is the intersection of the two straight lines,
(2) a second cross-sectional shape in which the vicinity of the corners of the first cross-sectional shape is rounded to form a curved line;
(3) a third cross-sectional shape formed only from arc-shaped curves; and
(4) U-shaped fourth cross-sectional shape,
Any one or more selected from the group consisting of
In the first cross-sectional shape and the second cross-sectional shape, the angle formed by the two straight lines is 45 degrees to 160 degrees,
A heat shield ring for a cylinder liner, characterized by satisfying the following formula.
・Formula (1) 0.85≧Sr/(Dr×Wr)≧0.5
・Formula (3′) 0.29≧Dr/Tr≧0.22
[In the above formula, Sr means the cross-sectional area (mm ² ) of the groove in the cross section perpendicular to the circumferential direction of the ring-shaped member, Dr means the maximum groove depth (mm) of the groove, and Wr means Tr means the maximum opening width (mm) of the groove in the axial direction of the ring-shaped member, and Tr means the radial thickness (mm) of the ring-shaped member. ] 1. The cross-sectional shape of the groove is at least one selected from the group consisting of ( 1 ) the first cross-sectional shape and (2) the second cross-sectional shape. Heat shield ring for cylinder liner described in . 3. The heat shield ring for a cylinder liner according to claim 1 , wherein the following formula (2) is satisfied.
・Formula (2) 0.41≧Dr/Wr
[In the formula (2), Dr means the maximum groove depth (mm) of the groove, and Wr means the maximum opening width (mm) of the groove in the axial direction of the ring-shaped member. ] The heat shield ring for a cylinder liner according to any one of claims 1 to 3 , wherein the following formula (4) is satisfied.
・Formula (4) 0.55≧Fr/Hr
[In the above 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. ] The heat shield ring for a cylinder liner according to any one of claims 1 to 4 , which is a carbon scraper ring. a cylindrical member, the inner peripheral surface of the cylindrical member being 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 in which the inner diameter in one region is larger than the inner diameter in the second region;
6. An internal combustion engine comprising at least a cylinder liner heat shield ring according to any one of claims 1 to 5 fitted in said first region of said cylinder liner. 7. The internal combustion engine according to claim 6 , wherein the inner diameter of said ring-shaped member is smaller than the inner diameter of said second region. 8. Internal combustion engine according to claim 6 or 7 , characterized in that it is a diesel engine.

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