Internal combustion engine

Abstract

To provide an internal combustion engine which inhibits temperature change of a fluid flowing in a predetermined passage as much as possible to suppress influence of the temperature change on the internal combustion engine while avoiding work needing a long time and high costs such as heat insulation coating.SOLUTION: An internal combustion engine 10 includes: a first passage 16 formed in an internal combustion engine body 12; a second passage 19 which is located adjacent to the first passage 16 with a first wall part 21 disposed therebetween; and a third passage 20 which is located adjacent to the first passage 16 with a second wall part 22 disposed therebetween and communicates with the second passage 19. A flow speed of a fluid flowing in the third passage 20 is larger than a flow speed of the fluid flowing in the second passage 19. A thickness dimension t1 of the first wall part 21 is larger than a thickness dimension t2 of the second wall part 22.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an internal combustion engine. [Background technology]

[0002] For example, an internal combustion engine such as a diesel engine is provided with an intake gas flow path for supplying outside air taken in through an intake port to the combustion chamber of each cylinder. A turbocharger compressor is provided downstream of the intake port of this intake gas flow path, and an intercooler is provided downstream of the compressor. The turbocharger turbine, which is coaxially connected to the compressor, receives the flow of exhaust gas and rotates to operate the compressor. As a result, the taken-in air is compressed, and the compressed air is cooled by the intercooler before being supplied to the combustion chamber (see, for example, Patent Document 1).

[0003] In addition, this type of internal combustion engine is generally provided with a structure for cooling the cylinder block and cylinder head that house the cylinders. Specifically, a cooling water passage for circulating cooling water is formed in the vicinity of a portion of the cylinder block that constitutes the engine body and that defines the combustion chamber together with the cylinder head, and by circulating the cooling water through this cooling water passage, it is possible to cool the portion of the cylinder block that is subject to particularly high thermal load, such as the portion that defines the combustion chamber (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-234733 A [Patent Document 2] JP 2019-163739 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the cooling water passage that cools the cylinders and the intake gas passage that supplies the cylinders with gas conditioned to a predetermined temperature are arranged in a limited space, they are often arranged very close to each other. Therefore, even if gas conditioned to a predetermined temperature flows through the intake gas passage, the temperature of the gas flowing through the intake gas passage may differ between the upstream and downstream sides of the intake gas passage due to the influence of the temperature of the cooling water in the adjacent cooling water passage. The difference in temperature of the gas supplied to each cylinder may affect the performance of the internal combustion engine.

[0006] In order to minimize the effects of the cooling water flowing through the cooling water passage, attempts have been made to apply an insulating coating to the inner surface of the intake gas flow passage; however, there is a problem in that it takes a great deal of time and cost to apply the insulating coating to the inner surface of the intake gas flow passage, which has a complex structure, without any leaks.

[0007] The above-mentioned problem is not limited to the intake gas flow path of an internal combustion engine, but can occur in any case in which flow paths through which fluids with different temperatures flow are adjacent to each other to the extent that heat transfer is possible.

[0008] In view of the above circumstances, the technical problem to be solved in this specification is to suppress temperature changes of a fluid flowing through a specified flow path as much as possible, while avoiding time-consuming and costly work such as insulating coating, and to suppress the effects of the temperature changes on an internal combustion engine. [Means for solving the problem]

[0009] The above-mentioned problems are solved by an internal combustion engine according to the present invention, which is characterized in that the internal combustion engine includes a first flow passage formed inside an internal combustion engine body, a second flow passage adjacent to the first flow passage across a first wall portion, and a third flow passage adjacent to the first flow passage across the second wall portion and communicating with the second flow passage, the flow velocity of fluid flowing through the third flow passage being greater than the flow velocity of fluid flowing through the second flow passage, and the thickness dimension of the first wall portion being greater than the thickness dimension of the second wall portion.

[0010] In this way, in the internal combustion engine according to the present invention, the thickness dimension of the first wall portion separating the first flow path from the second flow path is made larger than the thickness dimension of the second wall portion separating the first flow path from the third flow path, so that the heat transfer action between the first flow path and the second flow path that occurs along the first wall portion can be reduced. Meanwhile, since the flow velocity of the fluid flowing through the third flow path is greater than the flow velocity of the fluid flowing through the second flow path, the temperature influence from the adjacent first flow path through the second wall portion is relatively small. As described above, according to the present invention, it is possible to suppress the temperature change of the fluid flowing through the second flow path as much as possible and suppress the influence of the temperature change on the internal combustion engine while avoiding a long-term and expensive work such as heat insulating coating.

[0011] In the internal combustion engine according to the present invention, the first flow passage and the second flow passage may extend side by side, and a plurality of third flow passages may branch off from the second flow passage in a direction intersecting with the first flow passage.

[0012] By arranging the first flow passage and the second flow passage so that they extend side by side in this manner, it is possible to ensure the required volume for each flow passage while making the internal combustion engine body compact. By branching the third flow passage in a direction intersecting with the second flow passage, it is possible to ensure the required volume for each flow passage while arranging multiple third flow passages in a limited space. Of course, because the first wall portion between the first flow passage and the second flow passage is relatively large, it is possible to suppress unnecessary heat transfer as much as possible even when the first flow passage and the second flow passage are arranged adjacent to each other over a long distance.

[0013] In addition, in the internal combustion engine of the present invention, the first flow path is a cooling water passage through which cooling water flows, and the second flow path and the third flow path are intake gas flow paths through which intake gas as a fluid flows toward the combustion chamber, and the intake gas may be adjusted to a predetermined temperature lower than that of the cooling water upstream of a portion of the intake gas flow path that contacts the first wall portion.

[0014] By applying the configuration according to the present invention to the cooling water passage and the intake gas passage arranged adjacent to each other, it is possible to minimize the temperature change of the intake gas (intake air) flowing through the intake gas passage. Therefore, the intake gas, whose temperature has been adjusted to a suitable temperature for supply to the combustion chamber, can be supplied to the combustion chamber while maintaining the adjusted temperature as much as possible, which enables the internal combustion engine to produce a stable output. Effect of the Invention

[0015] As described above, according to the internal combustion engine of the present invention, it is possible to suppress temperature changes of the fluid flowing through a specified flow path as much as possible while avoiding time-consuming and costly work such as insulating coating, and to suppress the effects of the temperature changes on the internal combustion engine. [Brief description of the drawings]

[0016] [Figure 1] 1 is a perspective view of an internal combustion engine according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view taken along line AA of the internal combustion engine shown in FIG. [Diagram 3] 2 is a cross-sectional view of the internal combustion engine shown in FIG. 1 taken along line B-B. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the internal combustion engine will be described by taking, as an example, a diesel engine used to supply torque to a generator motor of a ship or to rotate a propeller shaft of a ship.

[0018] Fig. 1 shows a perspective view of an internal combustion engine 10 according to one embodiment of the present invention. As shown in Fig. 1, this internal combustion engine 10 is for extracting power by combustion in a plurality of cylinders (cylinders 11), and includes an internal combustion engine body 12, a combustion chamber 13 of each cylinder 11, an intake gas passage 14 for supplying intake gas to the combustion chamber 13, an exhaust gas passage 15 for discharging exhaust gas from the combustion chamber 13, and a cooling water passage 16. Here, the cooling water passage 16 corresponds to a first passage according to the present invention.

[0019] In this embodiment, the internal combustion engine body 12 is made up of a cylinder block 17 that integrally has a plurality of cylinders 11, and a cylinder head 18 that, together with the cylinder block 17, defines each combustion chamber 13.

[0020] The intake gas passage 14 is mainly for compressing gas (usually air) taken in through an intake port (not shown) and sending it to the combustion chamber 13 of each cylinder 11, and has a main intake passage 19 with an intake port at its upstream end, and a plurality of auxiliary intake passages 20 branching from the main intake passage 19 and connected to the combustion chamber 13 of each cylinder 11. Here, the main intake passage 19 corresponds to the second passage according to the present invention, and the auxiliary intake passage 20 corresponds to the third passage according to the present invention. In this embodiment, the main intake passage 19 extends linearly along the front-rear direction (x direction in FIG. 1) of the internal combustion engine 10. A compressor (not shown) of a supercharger is disposed upstream of the main intake passage 19 (lower left side in FIG. 1). An intercooler (not shown) is disposed downstream of the compressor in the main intake passage 19 and upstream of the region where the auxiliary intake passage 20 branches off. With this configuration, air taken in from the intake port is compressed by the compressor and supplied to the combustion chamber 13 through the main intake passage 19 and the auxiliary intake passage 20. In addition, the high-temperature air is cooled by the intercooler disposed downstream of the compressor, and compressed air adjusted to a predetermined temperature (for example, 40 to 45°C) can be supplied to the combustion chamber 13.

[0021] In this embodiment, each auxiliary intake passage 20 branches out in a direction intersecting (orthogonal in FIG. 1) the main intake passage 19. More specifically, the auxiliary intake passage 20 extends from the main intake passage 19 to one side in the vertical direction (here, the combustion chamber 13 side in the z direction), and then curves toward the center in the width direction (y direction) of the internal combustion engine 10 to connect to the combustion chamber 13 (see FIG. 2).

[0022] The main intake passage 19 configured as described above is formed integrally inside the cylinder block 17. In addition, a portion of the auxiliary intake passage 20 on the main intake passage 19 side is formed integrally inside the cylinder block 17 together with the main intake passage 19, and the remaining portion of the auxiliary intake passage 20 on the combustion chamber 13 side is formed integrally with the cylinder head 18.

[0023] The cross-sectional area S1 of the main intake passage 19 is larger than the cross-sectional area S2 of the auxiliary intake passage 20. Therefore, when a predetermined gas (the above-mentioned compressed air) is sent from the upstream side of the main intake passage 19, the flow velocity v2 of the gas (compressed air) flowing through the auxiliary intake passage 20 is larger than the flow velocity v1 of the gas (compressed air) flowing through the main intake passage 19 located upstream of each auxiliary intake passage 20.

[0024] The cooling water passage 16 allows cooling water to flow inside the internal combustion engine body 12, and in this embodiment, the cooling water passage 16 is integrally formed inside a cylinder block 17 that constitutes the internal combustion engine body 12. In this case, cooling water cooled to a predetermined temperature (for example, about 80° C.) is sent into the cooling water passage 16 by a pump (not shown), thereby allowing the cooling water to flow through the cooling water passage 16 and cooling the combustion chamber 13. In FIG. 1, the cooling water passage 16 extends linearly along the front-rear direction (x direction) of the internal combustion engine 10, and is arranged so that the cooling water passage 16 passes near each cylinder 11. In this case, a main intake passage 19 of the intake gas flow passage 14 is provided below the cooling water passage 16, and the cooling water passage 16 and the main intake passage 19 extend in parallel. The cooling water passage 16 and the main intake passage 19 are adjacent to each other in the vertical direction across a first wall portion 21 that extends in the horizontal direction (x direction and y direction) (see FIG. 3).

[0025] Next, the relationship between the cooling water passages 16 and the auxiliary air intake passages 20 will be described. Each auxiliary air intake passage 20 extends in a direction intersecting (orthogonal in FIG. 1) the cooling water passages 16, and the cooling water passages 16 and the auxiliary air intake passages 20 are adjacent to each other in the width direction (y direction) of the internal combustion engine 10, separated by a second wall portion 22 extending in the up-down direction (z direction) (see FIG. 2).

[0026] Here, when the thickness dimension of the first wall portion 21 is t1 and the thickness dimension of the second wall portion 22 is t2, the thickness dimension t1 of the first wall portion 21 and the thickness dimension t2 of the second wall portion 22 are set to t1>t2. Specifically, the thickness dimensions t1 and t2 of the walls 21 and 22 are set so that t1>1.25×t2, and preferably, the thickness dimensions t1 and t2 of the walls 21 and 22 are set so that t1>1.5×t2. This is because, when t1≦1.25×t2, it is difficult to sufficiently reduce the heat transfer between the cooling water passage 16 and the main intake passage 19. On the other hand, from the viewpoint of reducing the above-mentioned heat transfer and avoiding a situation in which the dimensions of the internal combustion engine body become larger than necessary, it is preferable to set the thickness dimensions t1 and t2 of the walls 21 and 22 so that t1≦3.0×t2.

[0027] In this embodiment, the outer end of the first wall portion 21 and the lower end of the second wall portion 22 are continuous. In the region of the main air intake passage 19 where the auxiliary air intake passage 20 branches off, the thickness dimension t1 of the first wall portion 21 decreases toward the outside and smoothly continues to the second wall portion 22 when it becomes equal to the thickness dimension t2 of the second wall portion 22 (see FIG. 2). On the other hand, in the region of the main air intake passage 19 excluding the branching portion of the auxiliary air intake passage 20, the thickness dimension t1 of the first wall portion 21 is constant in the width direction (see FIG. 3). Of course, the configuration of the first wall portion 21 and the second wall portion 22 shown in FIG. 2 is merely an example. For example, although not shown, the first wall portion 21 may be structured to be continuous to the second wall portion 22 with the thickness dimension t1 constant.

[0028] 1 shows only the cooling water passage 16 which is particularly related to the present invention, and does not deny the existence of other cooling water passages. In other words, cooling water passages of any shape other than those shown in the figure can be provided in the internal combustion engine body 12.

[0029] As described above, in the internal combustion engine 10 according to this embodiment, the thickness dimension t1 of the first wall portion 21 separating the cooling water passage 16 and the main intake passage 19 is made larger than the thickness dimension t2 of the second wall portion 22 separating the cooling water passage 16 and the auxiliary intake passage 20, so that the heat transfer action between the cooling water passage 16 and the main intake passage 19 that occurs along the first wall portion 21 can be reduced. On the other hand, since the flow velocity v2 of the gas (compressed air) flowing through the auxiliary intake passage 20 is larger than the flow velocity v1 of the gas flowing through the main intake passage 19, the influence of the temperature from the adjacent cooling water passage 16 through the second wall portion 22 is relatively small. As described above, according to the internal combustion engine 10 according to this embodiment, it is possible to suppress the temperature change of the gas flowing through the main intake passage 19 as much as possible and suppress the influence of the temperature change on the internal combustion engine 10 while avoiding a long-term and expensive work such as heat insulating painting.

[0030] When the intake gas passage 14 of the internal combustion engine 10 is configured as in this embodiment, the flow rate of gas differs between the upstream side and downstream side of the main intake passage 19 (the flow rate decreases toward the downstream side). Therefore, the downstream side is more susceptible to the influence of heat transfer from the cooling water passage 16. Taking these points into consideration, it is preferable to set the size of the thickness dimension t1 of the first wall portion 21 separating the cooling water passage 16 and the main intake passage 19.

[0031] Although one embodiment of the present invention has been described above, the internal combustion engine according to the present invention can have configurations other than those described above without departing from the spirit of the invention.

[0032] For example, in the above embodiment, the cooling water passage 16, the main intake passage 19, and the first wall portion 21 are all formed integrally inside the cylinder block 17, but of course this is not limited to this. As long as they are formed inside the internal combustion engine body 12 so as to be adjacent to each other with the first wall portion 21 in between, the structure and arrangement of the cooling water passage 16 and the main intake passage 19 are arbitrary.

[0033] In the above embodiment, the first wall portion 21 and the second wall portion 22 are both flat, but other shapes are possible. For example, although not shown, the cooling water passage 16 and the main intake passage 19 may both have a circular cross section, and the first wall portion 21 may be curved in an arc. Similarly, the second wall portion 22 may have any shape.

[0034] In addition, in the above embodiment, the thickness dimension t1 of the first wall portion 21 is constant in the front-rear direction (x direction) of the internal combustion engine 10, but it may of course be changed. For example, although not shown in the drawings, in consideration of the fact that the flow rate of compressed air decreases toward the downstream side of the main intake passage 19, the thickness dimension t1 of the first wall portion 21 may be increased toward the downstream side of the main intake passage 19.

[0035] In the above description, the first flow path is the cooling water path 16 and the second flow path is the main intake path 19 (intake gas flow path 14), but the present invention can be applied to other combinations of flow paths. That is, the fluid flowing through the first flow path is not limited to cooling water. Similarly, the fluid flowing through the second and third flow paths is not limited to compressed air. In the above description, the first flow path and the second flow path (and the third flow path) are illustrated as different types of fluids, but the present invention can be applied to a combination of the first and second flow paths through which the same type of fluid flows. In short, the present invention can be applied to any combination of flow paths as long as the flow paths through which fluids with different temperatures flow are adjacent to each other with a wall between them. [Explanation of symbols]

[0036] 10 Internal combustion engine 11 Cylinders 12 Internal combustion engine body 13 Combustion chamber 14 Intake gas flow path 15 Exhaust gas flow path 16 Cooling Channel 17 Cylinder block 18 Cylinder head 19 Main intake tract 20 Auxiliary intake passage 21 First wall 22 Second wall t1, t2 thickness dimensions

Claims

1. A first flow passage formed inside an internal combustion engine body; A second flow path adjacent to the first flow path across a first wall portion; a third flow passage adjacent to the first flow passage across a second wall portion and communicating with the second flow passage; Equipped with A flow velocity of the fluid flowing through the third flow path is greater than a flow velocity of the fluid flowing through the second flow path; and The first wall portion has a thickness dimension greater than a thickness dimension of the second wall portion.

2. The first flow path and the second flow path extend side by side; and The internal combustion engine according to claim 1 , wherein a plurality of the third flow passages branch off from the second flow passage in a direction intersecting with the first flow passage.

3. The first flow path is a cooling water channel through which cooling water flows, The second flow path and the third flow path are intake gas flow paths through which intake gas as the fluid flows toward a combustion chamber, 3. The internal combustion engine according to claim 1, wherein the intake gas is adjusted to a predetermined temperature lower than that of the cooling water upstream of a portion of the intake gas flow passage that contacts the first wall portion.

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