Cylinders, internal combustion engines, and vehicles
The cylinder's inner wall surface pattern aligns piston rings to minimize gas leakage, improving durability and efficiency in internal combustion engines.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- ISUZU MOTORS LTD
- Filing Date
- 2024-12-02
- Publication Date
- 2026-06-12
AI Technical Summary
Internal combustion engines experience gas leakage to the crankshaft side, affecting durability, environmental performance, and output efficiency.
The cylinder features an inner wall surface with a surface pattern that rotates piston rings in the circumferential direction, aligning gaps between piston rings to minimize gas leakage.
Suppresses gas leakage, enhances durability, improves environmental performance, and increases output efficiency by aligning piston ring gaps.
Smart Images
Figure 2026095911000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a cylinder, an internal combustion engine, and a vehicle.
Background Art
[0002] Internal combustion engines mounted on vehicles and the like include pistons. A plurality of piston rings are arranged on the piston body of the piston. Each of the plurality of piston rings is formed in a C shape having a joint gap (see Patent Document 1). The gas flowing from the combustion chamber to the crankshaft side passes through each joint gap of the piston rings.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In this type of internal combustion engine, from the viewpoints of the durability, environmental performance, and output efficiency of the internal combustion engine, it is required to suppress gas leakage to the crankshaft side in the internal space of the cylinder.
[0005] The present disclosure has been made in view of the above problems, and an object thereof is to suppress gas leakage to the crankshaft side in the internal space of the cylinder.
Means for Solving the Problems
[0006] The cylinder according to the embodiment includes an inner wall surface. The inner wall surface covers the internal space in which the piston is arranged. The inner wall surface has a surface pattern. The surface pattern rotates the piston ring in the circumferential direction of the piston by contact with the piston ring of the piston that moves in the vertical direction of the cylinder.
Effects of the Invention
[0007] According to this disclosure, gas leakage toward the crankshaft side can be suppressed in the internal space of the cylinder. [Brief explanation of the drawing]
[0008] [Figure 1] Figure 1 is a schematic diagram showing an example of the configuration of a vehicle according to this embodiment. [Figure 2] Figure 2 is a schematic diagram showing an example of the configuration of an internal combustion engine according to this embodiment. [Figure 3] Figure 3 is a schematic cross-sectional view showing an example of the configuration of the outer circumferential surface and its vicinity of the piston according to the embodiment. [Figure 4] Figure 4 is a schematic diagram showing the configuration of the inner wall surface of the cylinder according to the embodiment. [Figure 5] Figure 5 shows a cross-section of a portion of the inner wall surface when it is cut by a plane perpendicular to the height direction of the cylinder. [Figure 6] Figure 6 shows a state in which the gaps between the top ring, second ring, and oil ring are not misaligned in the circumferential direction relative to each other, or are only slightly misaligned. [Figure 7] Figure 7 shows an example of a state in which one or more gaps of the top ring, second ring, and oil ring are located circumferentially apart from the gaps of the other piston rings. [Figure 8] Figure 8 is a schematic diagram showing the configuration of the inner wall surface of the cylinder according to Modification Example 1. [Figure 9] Figure 9 is a schematic diagram showing the configuration of the inner wall surface of the cylinder according to the modified example 2. [Modes for carrying out the invention]
[0009] Figure 1 is a schematic diagram showing an example of the configuration of a vehicle 100 according to an embodiment. As shown in Figure 1, the vehicle 100 comprises an internal combustion engine 1, a transmission 110, and at least one wheel 40. When the internal combustion engine 1 is driven, the driving force is transmitted to at least one wheel 40 via the transmission 110.
[0010] Figure 2 is a schematic diagram showing an example of the configuration of an internal combustion engine 1 according to an embodiment. Figure 3 is a schematic cross-sectional view showing an example of the configuration of the outer circumferential surface and its vicinity of the piston 3 according to the embodiment. As shown in Figures 2 and 3, the internal combustion engine 1 comprises an intake valve (not shown), a cylinder 2, a piston 3, a piston pin 4, a combustion chamber 6, a crank arm (not shown), and a crankshaft (not shown). The internal combustion engine 1 according to the embodiment is, for example, a four-stroke engine that constitutes one cycle consisting of four processes: intake, compression, expansion, and exhaust. The internal combustion engine 1 according to the embodiment is, for example, a diesel engine. The piston 3 comprises a piston body 5 and a plurality of piston rings. The plurality of piston rings according to the embodiment include a top ring 7, a second ring 8, and an oil ring 9. Note that in Figure 2, for the sake of explanation, the top ring 7, the second ring 8, and the oil ring 9 are omitted from the illustration.
[0011] Cylinder 2 extends along the central axis A1 and is formed in a cylindrical or other tubular shape. Cylinder 2 has an inner wall surface 11. Inside cylinder 2, an internal space is formed that is covered by the inner wall surface 11. Hereafter, the direction around the central axis A1 of cylinder 2 will be referred to as the circumferential direction.
[0012] The piston 3 is positioned in the internal space and connected to the crank arm via a piston pin 4 or the like, which extends in a direction perpendicular or nearly perpendicular to the central axis A1 of the cylinder 2. The crank arm is rotatably mounted on the crankshaft. The piston 3 reciprocates in the internal space along the central axis A1 of the cylinder 2, in parallel with the rotation of the crank arm with the crankshaft as the axis of rotation. The axial direction of the cylinder 2 is aligned with the direction of movement of the piston 3.
[0013] In piston 3, for example, the following are formed in order from the intake valve side: piston crown 12, top land 13, top ring groove 14, second land 15, second ring groove 17, third land 18, oil ring groove 19, and piston skirt 21. The piston crown 12 is the end face on the intake valve side of piston 3 and faces the intake valve side. The piston skirt 21 forms the end face on the crankshaft side of piston 3, and the end face on the crankshaft side formed by the piston skirt 21 faces the crankshaft side.
[0014] In this embodiment, a piston 3 used in a diesel engine, one of the internal combustion engines 1, is described as an example, but the invention is not limited to this. The piston 3 may be used not only in a diesel engine, but also in other internal combustion engines 1, such as a gasoline engine.
[0015] In Figure 2, the direction along the central axis A1 of the cylinder 2 is defined as the Y-axis direction, the direction perpendicular to the Y-axis direction and in which the piston pin 4 extends is defined as the Z-axis direction, and the direction perpendicular to both the Y-axis and Z-axis directions is defined as the X-axis direction. In the X-axis direction, one side is defined as the positive direction of the X-axis, and the other side as the negative direction of the X-axis. In the Y-axis direction, the intake valve side is defined as the positive direction of the Y-axis, and the crankshaft side is defined as the negative direction of the Y-axis. Furthermore, in Figures 2 and 3, the far side of the plane of the paper is defined as the positive direction of the Z-axis, and the near side is defined as the negative direction of the Z-axis.
[0016] Next, the configuration of the inner wall surface 11 of the cylinder 2 will be described. FIG. 4 is a schematic diagram showing the configuration of the inner wall surface 11 of the cylinder 2 according to the embodiment. The inner wall surface 11 extends along the axial direction and the circumferential direction of the cylinder 2. In FIG. 4, the cylinder 2 is developed, and a state in which a part of the inner wall surface 11 is viewed from the inner space side covered by the inner wall surface 11 of the cylinder 2 is shown. In FIG. 4, the arrow r represents the direction along the circumferential direction of the cylinder 2. Also, the vertical direction in FIG. 4 extends along the axial direction of the cylinder 2.
[0017] As shown in FIG. 4, the inner wall surface 11 includes a surface pattern 30. The surface pattern 30 rotates the piston ring in the circumferential direction of the piston 3 when the piston ring moving in the vertical direction of the cylinder 2 comes into contact. The surface pattern 30 may be formed over the entire inner wall surface 11, or may be formed only at the portion of the inner wall surface 11 that comes into contact with the piston ring during the reciprocating motion of the piston 3.
[0018] In one example, the surface pattern 30 includes first grooves 31 that are inclined with respect to the vertical direction of the cylinder 2. The surface pattern 30 may include only one first groove 31, or may include a plurality of first grooves 31.
[0019] Also, in one example, the surface pattern 30 includes second grooves 32 that are inclined in the opposite direction to the inclination of the first grooves 31 with respect to the vertical direction of the cylinder 2. The surface pattern 30 may include only one second groove 32, or may include a plurality of second grooves 32. The first grooves 31 and the second grooves 32 are formed, for example, in a spiral shape. In this case, the first grooves 31 are formed in a spiral shape in the opposite direction to the second grooves 32.
[0020] The first grooves 31 may intersect the second grooves 32. In this case, the surface pattern 30 is formed in a cross-hatch shape.
[0021] The first groove 31 applies a first rotational force to the piston ring moving vertically in the cylinder 2, directed toward one side in the circumferential direction of the piston 3. The second groove 32 applies a second rotational force, which is of a different magnitude to the first rotational force, to the piston ring moving vertically in the cylinder 2, directed toward the opposite side of the first rotational force.
[0022] Figure 5 shows a cross-section of the inner wall surface 11 when a portion of it is cut by a plane P perpendicular to the height direction of the cylinder 2. Plane P is represented by the dashed line in Figure 4, and plane P is a plane that passes through a portion of the inner wall surface 11. In Figure 5, d1 represents the depth of the first groove 31, and d2 represents the depth of the second groove 32. In one example, as shown in Figure 5, the depth d1 of the first groove 31 is different from the depth d2 of the second groove 32. Specifically, the depth d1 of the first groove 31 is deeper than the depth d2 of the second groove 32. As a result, the first rotational force is greater than the second rotational force.
[0023] In the following description of the embodiments, it is assumed that the ratio of the area of the first groove 31 to the total area of the inner wall surface 11 is the same as the ratio of the area of the second groove 32 to the total area of the inner wall surface 11. In this case, if the widthwise dimensions of the first groove and the second groove are the same, the number of first grooves per unit area will be the same as the number of second grooves per unit area. Furthermore, it is assumed that the angle (inclination angle) between the first groove 31 and the inner wall surface 11 in the vertical direction is the same as the angle (inclination angle) between the second groove 32 and the inner wall surface 11 in the vertical direction.
[0024] Next, the multiple piston rings will be described. The top ring 7 is positioned in the top ring groove 14. The second ring 8 is positioned in the second ring groove 17. The oil ring 9 is positioned in the oil ring groove 19. Each of the top ring 7, second ring 8, and oil ring 9 has two ends, and is formed by extending in a C-shape from one end to the other. A gap is formed between the two ends. Hereafter, the gap formed in the top ring 7 will be referred to as S1, the gap formed in the second ring 8 as S2, and the gap formed in the oil ring 9 as S3.
[0025] Each piston ring rotates circumferentially around the piston 3 by contacting the surface pattern 30 as it moves vertically within the cylinder 2. Specifically, each piston ring receives the resultant force of the first and second rotational forces by contacting the first groove 31 and the second groove 32 as it moves vertically within the cylinder 2. As a result, each piston ring rotates circumferentially around the piston 3. In a configuration where the depth d1 of the first groove 31 is deeper than the depth d2 of the second groove 32, the first rotational force is greater than the second rotational force, so the direction of the resultant force received by each of the multiple piston rings is the direction in which the first rotational force acts.
[0026] Each of the multiple piston rings has a different configuration and function. Furthermore, each of the multiple piston rings is positioned differently on the piston body 5. Therefore, the contact state between each of the multiple piston rings and the inner wall surface 11 is different from the contact state between the other piston rings and the inner wall surface 11. Because the contact states are different, the force acting on each of the multiple piston rings is different from the force acting on the other piston rings, and each of the multiple piston rings rotates at a different rotational speed relative to the other piston rings.
[0027] Next, we will explain the gas that passes through the gap between the piston joints as part of the blow-by gas. The gas mainly flows from the combustion chamber 6, through the region between the piston crown 12 and the inner wall 11, the space between the top land 13 and the inner wall 11, the joint gap S1, the space between the second land 15 and the inner wall 11, the joint gap S2, the space between the third land 18 and the inner wall 11, and the region between the piston skirt 21 and the inner wall 11, in that order, towards the crankshaft side. The longer the path from the region between the piston crown 12 and the inner wall 11 to the region between the piston skirt 21 and the inner wall 11 (hereinafter simply referred to as the gas path), the greater the gas pressure loss. When the pressure loss is large, it becomes more difficult for the gas to flow from the combustion chamber 6 towards the crankshaft side.
[0028] Figure 6 shows a state where the gaps S1 to S3 of the top ring 7, second ring 8, and oil ring 9 are not misaligned with each other in the circumferential direction of the piston 3, or are only slightly misaligned. In other words, Figure 6 shows a state where the gaps S1 to S3 of the top ring 7, second ring 8, and oil ring 9 are aligned in the circumferential direction of the cylinder 2. Figure 6 shows an enlarged view of the second land 15, third land 18, and their surrounding configuration. In Figure 6, G1 represents the gas path when the gaps S1 to S3 of the top ring 7, second ring 8, and oil ring 9 are not misaligned with each other in the circumferential direction, or are only slightly misaligned. In the state shown in Figure 6, the distance along the circumferential direction between gap S1 and gap S2, and the distance along the circumferential direction between gap S2 and gap S3 are 0. In other words, in the state shown in Figure 6, the length of the gas path is minimized.
[0029] On the other hand, Figure 7 shows a state in which one or more gaps S1 to S3 of the top ring 7, second ring 8, and oil ring 9 are located circumferentially apart from the gaps S1 to S3 of the other piston rings. In other words, Figure 7 shows an example of a state in which the gaps S1 to S3 of the top ring 7, second ring 8, and oil ring 9 are not located together in the circumferential direction of the cylinder 2. In Figure 7, G2 represents the gas path when the gaps S1 to S3 of the top ring 7, second ring 8, and oil ring 9 are located circumferentially apart from the gaps S1 to S3 of the other piston rings. In the example shown in Figure 7, the gaps S1 and S3 of the top ring 7 and oil ring 9 are located at the same position in the circumferential direction. On the other hand, the gap S2 of the second ring 8 is located circumferentially apart from the gaps S1 and S3 of the top ring 7 and oil ring 9.
[0030] When comparing the length of the gas path in the state shown in Figure 6 and the state shown in Figure 7, as shown by G1 in Figure 6 and G2 in Figure 7, the length of the gas path in the state shown in Figure 7 is longer than the length of the gas path in the state shown in Figure 6. The longer the gas path, the greater the gas pressure loss. Also, in G2 in Figure 7, there is one or more bends in the gas flow path between the joint gap S1 and the joint gap S3 (four bends in Figure 7). Therefore, in the state shown in Figure 7, pressure loss occurs due to the bends in the gas flow path. Due to these reasons, the pressure loss is greater in the state shown in Figure 7 than in the state shown in Figure 6. And when the pressure loss is greater, it becomes more difficult for the gas to flow, so the gas flows less easily in the state shown in Figure 7 than in the state shown in Figure 6.
[0031] According to the embodiment, the inner wall surface 11 is provided with a surface pattern 30. The piston rings of the piston 3, which moves vertically in the cylinder 2, come into contact with the surface pattern 30, causing the piston rings to rotate in the circumferential direction of the piston 3. Since each of the multiple piston rings rotates at a different rotational speed than the other piston rings, the gaps between the multiple piston rings are not misaligned with each other in the circumferential direction of the piston 3, or are only slightly misaligned. As a result, one or more gaps S1 to S3 are positioned circumferentially apart from the gaps between the other piston rings. This increases the length of the gas path, making it more difficult for gas to flow from the combustion chamber 6 to the crankshaft side in the internal space of the cylinder 2, thereby suppressing gas leakage. Furthermore, suppressing gas leakage improves the durability of components such as a compressor (not shown) provided in the internal combustion engine 1. In addition, the ratio of the energy output by the internal combustion engine 1 to the energy of gas combustion can be increased. Moreover, the environmental performance of the internal combustion engine 1 is improved.
[0032] (Variation 1) In the surface pattern 30 formed on the inner wall surface 11 according to the embodiment, the angle between the first groove 31 and the inner wall surface 11 in the vertical direction was equal to the angle between the second groove 32 and the inner wall surface 11 in the vertical direction, but the embodiment is not limited to this. The angle between the first groove 31 and the inner wall surface 11 in the vertical direction may be different from the angle between the second groove 32 and the inner wall surface 11 in the vertical direction. Figure 8 is a schematic diagram showing the configuration of the inner wall surface 11 of the cylinder 2 according to Modification 1. In Figure 8, θ1 represents the angle between the first groove 31 and the inner wall surface 11 in the vertical direction, and θ2 represents the angle between the second groove 32 and the inner wall surface 11 in the vertical direction. As shown in Figure 8, in one example, the angle θ1 between the first groove 31 and the inner wall surface 11 in the vertical direction is larger than the angle θ2 between the second groove 32 and the inner wall surface 11 in the vertical direction. The larger the angle between the groove and the inner wall surface 11 in the vertical direction, the greater the rotational force acting on the piston ring moving in the vertical direction of the cylinder 2, in one circumferential direction on the piston 3. For this reason, even in the configuration according to Modification 1, the first rotational force is greater than the second rotational force. Therefore, since each of the multiple piston rings can be rotated, gas leakage toward the crankshaft side can be suppressed within the internal space of the cylinder 2.
[0033] (Modification 2) In the surface pattern 30 formed on the inner wall surface 11 according to the embodiment, the area ratio of the first groove 31 to the entire inner wall surface 11 and the area ratio of the second groove 32 to the entire inner wall surface 11 were the same, but this is not limited to this configuration. The area ratio of the first groove 31 to the entire inner wall surface 11 may be different from the area ratio of the second groove 32 to the entire inner wall surface 11. For example, if the widthwise dimensions of the first groove and the second groove are the same, a configuration in which the area ratio of the first groove 31 is different from the area ratio of the second groove 32 can be realized by making the number of first grooves per unit area different from the number of second grooves per unit area. Figure 9 is a schematic diagram showing the configuration of the inner wall surface 11 of the cylinder 2 according to Modification 2. In Figure 9, a part of the inner wall surface 11 is shown. As shown in Figure 9, in one example, the number of first grooves 31 formed in a part of the inner wall surface 11 is greater than the number of second grooves 32 formed in the same part of the inner wall surface 11. The larger the area ratio of the grooves to the inner wall surface 11, the greater the rotational force acting on the piston rings moving vertically in the cylinder 2 toward one side in the circumferential direction of the piston 3. For this reason, even in the configuration according to Modification 2, the first rotational force is greater than the second rotational force. Therefore, since each of the multiple piston rings can be rotated, gas leakage toward the crankshaft side can be suppressed in the internal space of the cylinder 2.
[0034] (Variation 3) Furthermore, each of the multiple piston rings may have a surface pattern (not shown) formed on its outer circumference. When each piston ring is in contact with the surface pattern 30 of the cylinder 2 and is subjected to a rotational force in one direction in the circumferential direction of the piston 3, the presence of the surface pattern 30 of the piston ring further increases the rotational force in the direction from which it is being subjected to the rotational force. Therefore, each of the multiple piston rings can be rotated more, and gas leakage toward the crankshaft side can be further suppressed in the internal space of the cylinder 2.
[0035] The surface pattern 30 can be configured in any way that causes the piston ring to rotate in the circumferential direction of the piston 3 when it comes into contact with the piston ring moving vertically in the cylinder 2. For example, embodiments 1 to 3 may be selected or combined as appropriate.
[0036] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways during implementation without departing from its essence. Furthermore, each embodiment may be combined as appropriate, and in that case, the combined effects can be obtained. Moreover, the above embodiments include various inventions, and various inventions can be extracted by selecting combinations from the multiple constituent elements disclosed. For example, if the problem can be solved and effects obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, then the configuration with these deleted constituent elements can be extracted as an invention. [Explanation of Symbols]
[0037] 1...Internal combustion engine, 2...Cylinder, 3...Piston, 4...Piston pin, 5...Piston body, 6...Combustion chamber, 7...Top ring, 8...Second ring, 9...Oil ring, 11...Inner wall surface, 12...Piston crown surface, 13...Top land, 14...Top ring groove, 15...Second land, 17...Second ring groove, 18...Third land, 19...Oil ring groove, 21...Piston skirt, 30...Surface pattern, 31...First groove, 32...Second groove, 40...Wheel, 100...Vehicle, 110...Transmission, A1...Center axis, P...Plane, r...Arrow, S1~S3...Joint gap.
Claims
1. It has an inner wall surface that covers the internal space in which the piston is arranged, The inner wall surface has a surface pattern that causes the piston ring of the piston, which moves vertically, to rotate in the circumferential direction of the piston when it comes into contact with it. Cylinder.
2. The cylinder according to claim 1, wherein the surface pattern includes a first groove that is inclined with respect to the vertical direction.
3. The cylinder according to claim 2, wherein the surface pattern includes a second groove that is inclined in the direction opposite to the inclination of the first groove with respect to the vertical direction.
4. The cylinder according to claim 3, wherein the first groove intersects with the second groove.
5. The first groove applies a first rotational force to the piston ring, which moves in the vertical direction, to one side in the circumferential direction. The second groove applies a second rotational force, which is of a different magnitude from the first rotational force, to the piston ring that moves in the vertical direction, in the opposite direction to the first rotational force. The cylinder according to claim 3.
6. The cylinder according to claim 3, wherein the first groove and the second groove differ in one or more of the following: depth, area ratio, and inclination angle.
7. A cylinder according to any one of claims 1 to 6, The piston equipped with the piston ring, An internal combustion engine equipped with [a specific feature].
8. A vehicle equipped with an internal combustion engine as described in claim 7.