internal combustion engine

Abstract

To inhibit water injected from a water injection valve from mixing with an oil on an inner wall surface of a cylinder to generate an emulsion.SOLUTION: An internal combustion engine 11 includes a combustion chamber 31 and a water injection valve 35. The combustion chamber 31 is formed surrounded by a cylinder 13 extending along an axis L1, a cylinder head 21 disposed at one side of the cylinder 13 in a direction along the axis L1, and a piston 16 which is disposed in the cylinder 13 in a manner that enables reciprocation. The cylinder head 21 has an intake port 22 which forms a part of an intake passage and extends to an inner wall surface 14a of the cylinder 13, inclining relative to the axis L1. A water trap wall 26 extending to the piston 16 side is provided in at least a part of a portion, located around an opening 22a of the combustion chamber 31 of the intake port 22 and at the downstream of the intake port 22, of a portion of the cylinder head 21 which faces the combustion chamber 31.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine including a combustion chamber and a water injection valve that injects water into an intake passage connected to the combustion chamber. [Background technology]

[0002] An internal combustion engine in which water is injected into an intake passage from a water injection valve and the intake air is cooled by the heat of vaporization of the injected water is described, for example, in Patent Document 1. With this internal combustion engine, abnormal combustion such as knocking and pre-ignition can be suppressed by lowering the temperature of the intake air. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-95899 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the injected water adheres to and mixes with the lubricating oil adhering to the inner wall surface of the cylinder, an emulsion is formed, which can cause a deterioration in the sliding characteristics of the piston. [Means for solving the problem]

[0005] An internal combustion engine that solves the above problem comprises a combustion chamber and a water injection valve that injects water into an intake passage connected to the combustion chamber, the combustion chamber being formed by a cylinder extending along an axis, a cylinder head arranged on one side of the cylinder in a direction along the axis, and a piston arranged to be able to reciprocate in the cylinder, the cylinder head forming part of the intake passage and having an intake port that extends toward the inner wall surface of the cylinder at an angle to the axis and opens into the combustion chamber, and a water trap wall extending toward the piston is provided in at least a part of the portion of the cylinder head facing the combustion chamber, around the opening of the intake port in the combustion chamber and downstream of the intake port.

[0006] According to the above configuration, when water is injected into the intake passage from the water injection valve, the spray of injected water flows through the intake port and enters the combustion chamber from the opening at the downstream end of the intake port. In the combustion chamber, the spray of water flows in the direction of the extension of the intake port, i.e., in a direction inclined relative to the axis of the cylinder. In the combustion chamber, the inner wall surface of the cylinder is located on the extension of the intake port.

[0007] However, a water trap wall is provided in a location on the cylinder head that satisfies the above conditions. The water trap wall extends from the above location on the cylinder head toward the piston. The water trap wall is located on an extension of the intake port in the combustion chamber, between the opening of the intake port and the inner wall surface of the cylinder.

[0008] As a result, at least a portion of the main flow of water that flows into the combustion chamber from the intake port opening collides with the water trap wall and is blocked. As a result, the amount of water that flows in the direction of the intake port and adheres to the inner wall surface of the cylinder is less than if the water trap wall were not provided. This reduces the amount of water that mixes with the lubricating oil that is supplied during operation of the internal combustion engine and adheres to the inner wall surface of the cylinder, thereby reducing the amount of emulsion that is generated. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a partial cross-sectional view showing a combustion chamber and its surrounding area of ​​an internal combustion engine according to an embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view of part A in FIG. [Figure 3] FIG. 2 is a partial perspective view showing the positional relationship between an intake port, an exhaust port, and a water trap wall in the cylinder head of the embodiment. [Figure 4] FIG. 2 is a partial bottom view showing the positional relationship between an intake port, an exhaust port, and a water trap wall in the cylinder head of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment in which the internal combustion engine is embodied as a multi-cylinder internal combustion engine mounted on a vehicle will be described with reference to the drawings. <Basic configuration of internal combustion engine 11> As shown in FIG. 1, a portion of an internal combustion engine 11 is formed by a cylinder block 12. The cylinder block 12 has a plurality of cylindrical cylinders 13, each extending vertically along an axis L1. The plurality of cylinders 13 are arranged in a row perpendicular to the plane of the drawing. Each cylinder 13 is formed by a cylinder liner 14 fitted into the cylinder block 12. A piston 16, shown by a two-dot chain line, is arranged in the cylinder liner 14 so as to be able to reciprocate and slide. Each piston 16 is connected to a crankshaft (not shown), which is the output shaft of the internal combustion engine 11, via a connecting rod (not shown). The reciprocating motion of each piston 16 is converted into rotational motion by the connecting rod and then transmitted to the crankshaft.

[0011] A cylinder head 21 is disposed on one side of the cylinder 13 in the direction along the axis L1 (the upper side in FIG. 1) via a gasket 18. The cylinder head 21 is fastened to the cylinder block 12 by head bolts (not shown).

[0012] The space surrounded by the top surface of each piston 16, the inner wall surface 14a of each cylinder 13 (cylinder liner 14), and the lower surface 21a of the cylinder head 21 constitutes a combustion chamber 31 for burning a mixture of fuel and air. The portion of the lower surface 21a facing the combustion chamber 31 is recessed upward.

[0013] The cylinder head 21 is provided with intake ports 22 that form part of the intake passage and that introduce air into each combustion chamber 31. The intake ports 22 connected to each combustion chamber 31 extend toward the inner wall surface 14a of the cylinder liner 14 while being inclined with respect to the axis L1. The intake ports 22 connected to each combustion chamber 31 have openings 22a that open in recessed portions of the lower surface 21a of the cylinder head 21.

[0014] The cylinder head 21 is also provided with exhaust ports 24 that form part of the exhaust passage and that guide the combustion gas generated in each combustion chamber 31. The exhaust ports 24 connected to each combustion chamber 31 are inclined with respect to the axis L1 on the opposite side to the intake ports 22. Each exhaust port 24 has an opening 24a that opens in a recessed portion of the lower surface 21a.

[0015] As shown in FIGS. 3 and 4, in this embodiment, two intake ports 22 and two exhaust ports 24 are provided for each combustion chamber 31. The openings 22a of the intake ports 22 are aligned and open in a recessed portion of the lower surface 21a. The openings 24a of the exhaust ports 24 are aligned and open in a recessed portion of the lower surface 21a in the same direction as the alignment direction of the openings 22a. The openings 22a and the openings 24a are adjacent to each other and close to each other in a direction perpendicular to the alignment direction. As shown in FIG. 1, each opening 24a is located downstream of the corresponding opening 22a in the air flow direction at the intake port 22.

[0016] In addition to the multiple intake ports 22, the intake passage also includes a surge tank and an intake manifold (both not shown) located upstream of the intake ports 22. The intake manifold distributes and supplies air to each combustion chamber 31, and is branched into the same number of branches as the combustion chambers 31. Two passages are formed inside each branch, separated from each other. Each passage is connected to the intake port 22 described above.

[0017] The air outside the internal combustion engine 11 passes through each section of the intake passage as intake air in sequence. At this time, the intake air that flows into the surge tank is distributed to the branching sections of the intake manifold and led to each intake port 22.

[0018] The intake manifold is fitted with a fuel injection valve (not shown) that supplies fuel to each combustion chamber 31 by injecting fuel such as gasoline toward each intake port 22 (port injection).

[0019] In addition, the cylinder head 21 is provided with intake valves 23 that open and close each intake port 22, and exhaust valves 25 that open and close each exhaust port 24. Note that Figures 3 and 4 show the cylinder head 21 in a state before these intake valves 23 and exhaust valves 25 are installed. Furthermore, the cylinder head 21 is provided with a valve operating mechanism (not shown) that drives the intake valves 23 and exhaust valves 25 in Figures 1 and 2.

[0020] Then, the mixture consisting of fuel injected (port injected) from the fuel injection valve and intake air drawn in through the intake passage as described above flows into the combustion chamber 31 through the opening 22a when the intake valve 23 is opened.

[0021] The fuel injection valves may be attached to the cylinder head 21. In this case, each fuel injection valve directly injects fuel (in-cylinder injection) into the corresponding combustion chamber 31. The injected fuel mixes with intake air that flows into the combustion chamber 31 through the intake passage to form an air-fuel mixture.

[0022] Furthermore, the internal combustion engine 11 may be equipped with both a port-injection fuel injection valve and an in-cylinder injection fuel injection valve. As shown by the two-dot chain lines in Figures 3 and 4, spark plugs 32 are attached to the cylinder head 21 corresponding to each combustion chamber 31. The air-fuel mixture is ignited and burned by the spark plugs 32. The air-fuel mixture throughout the combustion chambers 31 is burned by the spread of a small flame generated by spark ignition (flame propagation). The high-temperature, high-pressure combustion gases generated by this combustion reciprocate the piston 16 shown in Figure 1, causing the crankshaft to rotate and providing driving force (output torque) for the internal combustion engine 11.

[0023] In addition to the exhaust port 24, the exhaust passage also includes an exhaust manifold, a catalytic converter (neither of which are shown), and the like, which are arranged downstream of the exhaust port 24. The exhaust manifold has the same number of branch portions as the number of combustion chambers 31. The multiple branch portions join at the downstream end of the exhaust manifold.

[0024] The combustion gas generated in each combustion chamber 31 passes through each part of the exhaust passage in order and is discharged to the outside of the internal combustion engine 11 as exhaust gas. <Water injection valve 35> As shown in FIG. 1, a water injector 35 that injects water W1 is disposed in the intake passage. The water injector 35 cools the intake air by the heat of vaporization of the injected water W1. The water injector 35 may be disposed, for example, upstream of the surge tank in the intake passage. The water injector 35 may also be attached to the surge tank. Furthermore, the water injector 35 may be attached both upstream of the surge tank in the intake passage and in the surge tank.

[0025] Meanwhile, a pump and a water tank (both not shown) in which water is stored are arranged outside the internal combustion engine 11. The water injection valve 35 is connected to the pump via piping (not shown). The pump draws up water from the water tank and supplies the water at a predetermined pressure to the water injection valve 35 via the piping.

[0026] The operation of the water injection valve 35 is controlled in accordance with the operating state of the internal combustion engine 11. <Water Trap Wall 26> 1 and 2, a water trap wall 26 is provided in the recessed portion of the underside 21a of the cylinder head 21. A water trap wall 26 is provided for each opening 22a of the intake port 22. In this embodiment, in which two intake ports 22 are provided for each combustion chamber 31, as shown in FIGS. 3 and 4, one water trap wall 26 is provided for each intake port 22, that is, two water trap walls 26 are provided for each combustion chamber 31.

[0027] Each water trap wall 26 is preferably formed in a position and shape that satisfies the following conditions: Condition: When the maximum amount of water is injected from the water injection valve 35 and the intake valve 23 is fully open, the main flow of water injected from the water injection valve 35 is in a position and shape that obstructs it the most.

[0028] To satisfy the above conditions, each water trap wall 26 is formed around the opening 22a of the intake port 22, at least in a portion downstream of the intake port 22. In this embodiment, each water trap wall 26 is provided between the opening 22a of the intake port 22 and the opening 24a adjacent to the intake port 22 on the downstream side.

[0029] Each water trap wall 26 is provided in the middle portion between the opening 22a and the opening 24a downstream of the intake port 22 in the arrangement direction of the opening 22a of the intake port 22 and the opening 24a downstream of the intake port 22. In the circumferential direction of each opening 22a, each water trap wall 26 is provided in the region including the point where the distance between the opening 22a of the intake port 22 and the opening 24a downstream of the intake port 22 is the narrowest.

[0030] To satisfy the above conditions, each water trap wall 26 has a plate-like shape. Each water trap wall 26 is formed in a shape that corresponds to the shape of the opening 22a, that is, a gently curved shape that bulges toward the opening 24a downstream of the intake port 22.

[0031] 1 and 2, each water trap wall 26 extends from the recessed portion of the lower surface 21a of the cylinder head 21 toward the piston 16. Each water trap wall 26 may be formed integrally with the cylinder head 21, or may be formed as a separate member from the cylinder head 21.

[0032] The lower end of each water trap wall 26, which is the end on the piston 16 side, is located in a position that does not interfere with the intake valve 23 when the intake valve 23 reciprocates to open and close the intake port 22. In addition, the lower end of each water trap wall 26 is located in a position that does not interfere with the exhaust valve 25 when the exhaust valve 25 reciprocates to open and close the exhaust port 24.

[0033] Next, the operation of this embodiment configured as above will be described. As shown in Figures 1 and 2, when water W1 is injected from the water injection valve 35 into the intake passage depending on the operating state of the internal combustion engine 11, the injected water spray flows through each intake port 22 and enters the combustion chamber 31 through the opening 22a.

[0034] When the water W1 injected from the water injection valve 35 vaporizes, the heat of vaporization removes heat from the intake air. The decrease in the temperature of the intake air suppresses abnormal combustion such as knocking and pre-ignition. Here, knocking is a phenomenon in which an unburned mixture (unburned gas) at the end of each combustion chamber 31 self-ignites before the arrival of a flame caused by spark ignition. Pre-ignition is a phenomenon in which an unburned mixture self-ignites in the combustion chamber 31 before spark ignition by the spark plug 32.

[0035] In each combustion chamber 31, the water spray flows in the direction of the intake port 22, i.e., in a direction inclined with respect to the axis L1 of the cylinder 13, as indicated by solid arrow B in Figures 1 and 2. In each combustion chamber 31, the inner wall surface 14a of the cylinder liner 14 is located on an extension of the intake port 22. Therefore, if no measures are taken to block the flow of the water spray, the water spray will flow in the direction indicated by dashed-dotted arrow C in Figures 1 and 2 and adhere to the inner wall surface 14a of the cylinder liner 14. The water is supplied as the internal combustion engine 11 operates and mixes with the lubricating oil adhering to the inner wall surface 14a of the cylinder liner 14. This creates an emulsion of water and oil.

[0036] In this regard, in this embodiment, a water trap wall 26 is provided at each recessed portion of the underside 21a of the cylinder head 21. Each water trap wall 26 extends from the recessed portion of the underside 21a of the cylinder head 21 toward the piston 16. This water trap wall 26 is located on an extension of the intake port 22 in the combustion chamber 31, between the opening 22a of the intake port 22 and the inner wall surface 14a of the cylinder liner 14.

[0037] Therefore, at least a part of the main stream of water that flows into the combustion chamber 31 from the opening 22a collides with the water trap wall 26 and is blocked from flowing. The amount of water that flows across the water trap wall 26 to the opposite side from the intake port 22 is less than when the water trap wall 26 is not provided.

[0038] The water spray whose flow is obstructed by the water trap wall 26 is captured by the water trap wall 26. The captured water W2 either drips onto the piston 16 and evaporates, or evaporates on the surface of the water trap wall 26.

[0039] According to the present embodiment described above in detail, the following effects can be obtained. (1) In this embodiment, a water trap wall 26 extending toward the piston 16 is provided on a portion of the lower surface 21a of the cylinder head 21 around each opening 22a, downstream of the intake port 22.

[0040] Therefore, the flow of water spray that flows into the combustion chamber 31 is blocked by the water trap wall 26, reducing the amount of water that adheres to the inner wall surface 14a of the cylinder liner 14. This reduces the amount of water that is supplied as the internal combustion engine 11 operates and mixes with the lubricating oil that adheres to the inner wall surface 14a. This reduces the amount of water-oil emulsion that is generated, and suppresses deterioration of the sliding characteristics of the piston 16 that would otherwise be caused by the emulsion.

[0041] (2) In this embodiment, each water trap wall 26 is provided around the opening 22a and close to the opening 22a. Therefore, the flow of water can be blocked by the water trap wall 26 immediately after it leaves the opening 22a. This effectively prevents water from adhering to the inner wall surface 14a, compared to when each water trap wall 26 is provided farther from the opening 22a.

[0042] (3) In this embodiment, each water trap wall 26 has a shape corresponding to the shape of the opening 22a of the intake port 22, and is formed in a curved shape that bulges toward the opening 24a of the exhaust port 24. Therefore, despite its small size, it is possible to efficiently capture water spray and efficiently reduce the amount of water adhering to the inner wall surface 14a of the cylinder liner 14.

[0043] (4) In this embodiment, each water trap wall 26 is formed in a plate shape. The thickness of the water trap wall 26 in the direction of arrangement between the opening 22a of the intake port 22 and the opening 24a downstream of the intake port 22 is small. Therefore, the water trap wall 26 is less likely to interfere with the operation of the intake valve 23 and the exhaust valve 25.

[0044] (5) When each water trap wall 26 is formed integrally with the cylinder head 21, the water trap wall 26 can be formed at the same time as manufacturing the cylinder head 21. This makes it easier to manufacture each water trap wall 26 than when each water trap wall 26 is formed from a separate member from the cylinder head 21.

[0045] The above embodiment can also be implemented as a modified example in which it is modified as follows: The above embodiment and the following modified example can be implemented in combination with each other within a range where no technical contradiction occurs.

[0046] <Water Trap Wall 26> Each water trap wall 26 may be formed in a flat shape extending in the circumferential direction of the opening 22a instead of being curved.

[0047] Each water trap wall 26 may be provided at multiple locations around each opening 22 a, provided that the locations are downstream of the intake port 22 . Each water trap wall 26 may be provided around the opening 22a and downstream of the intake port 22, over a wider area in the circumferential direction of the opening 22a than in the above embodiment.

[0048] The water trap wall 26 may be provided parallel to the axis L1 of the cylinder 13, or may be provided at an angle relative to the axis L1. In the latter case, the water trap wall 26 may be inclined relative to the axis L1 so that, for example, it approaches the opening 22a (moves away from the opening 24a) as it approaches the piston 16.

[0049] <Applicable internal combustion engines> The present invention is also applicable to internal combustion engines that use hydrogen as fuel. The present invention can also be applied to an internal combustion engine of a type in which the number of openings 22a, 24a facing the combustion chamber 31 is different from that of the above embodiment.

[0050] The present invention is also applicable to an internal combustion engine in which the cylinder 13 is configured without using the cylinder liner 14. [Explanation of symbols]

[0051] 11...Internal combustion engine 13...Cylinder 14a...Inner wall surface 16...Piston 21...Cylinder head 22...Intake port 22a...Opening 26...Water trap wall 31...Combustion chamber 35...Water injection valve L1…Axis line W1…Water

Claims

1. a combustion chamber; and a water injection valve that injects water into an intake passage connected to the combustion chamber, the combustion chamber is surrounded by a cylinder extending along an axis, a cylinder head disposed on one side of the cylinder in a direction along the axis, and a piston disposed in the cylinder so as to be capable of reciprocating; an internal combustion engine, wherein the cylinder head forms a part of the intake passage, extends toward an inner wall surface of the cylinder in a state inclined with respect to the axis, and has an intake port opening at the combustion chamber, a water trap wall extending toward the piston is provided around an opening of the intake port in the combustion chamber in a portion of the cylinder head facing the combustion chamber, At least a portion of the water trap wall is located within a range extending from the wall surface of the intake port in a direction toward the combustion chamber in which the intake port extends. Internal combustion engine.

2. The water trap wall is plate-shaped.

2. The internal combustion engine according to claim 1.

3. The water trap wall is inclined with respect to the axis so as to approach the opening toward the piston side.

3. The internal combustion engine according to claim 2.

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