Intake structure of internal combustion engine

Abstract

To effectively supply condensed water to intake air with a simple structure.SOLUTION: An intake air structure of an internal combustion engine includes: a condensed water storage part mounted on an upstream side of a cooling core provided in an EGR cooler or an inter cooler, and storing condensed water generated in the cooling core; and a condensed water transfer pipe connecting an area getting to have a pressure lower than that of the condensed water storing part and the condensed water storage part when an intake valve is opened, in an intake passage. The intake valve is opened, and pressure in the intake passage is decreased and becomes lower than the pressure in the condensed water storing part. Thereby, the condensed water stored in the condensed water storing part is sucked out into the intake passage, and is mixed with the intake air to cool the intake air.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, there have been proposals to process condensed water discharged from an EGR (Exhaust Gas Recirculation) cooler or an intercooler by mixing it with intake air (see, for example, Patent Documents 1 and 2). It has also been proposed to inject water into the intake air to cool it and improve the efficiency of intake of fresh air into the combustion chamber (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-251477 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-4295 [Patent Document 3] Patent Publication No. 2021-011824 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, Patent Document 1 discloses sucking out condensed water using a Venturi tube. Patent Document 2 discloses sucking out condensed water using a glass capillary tube. It is conceivable that the condensed water sucked out by the structures disclosed in Patent Document 1 and Patent Document 2 could be used for intake air cooling. However, the Venturi tube in Patent Document 1 is thought to cause intake resistance. Furthermore, the glass capillary tube in Patent Document 2 is thought to become clogged. If the glass capillary tube becomes clogged, its ability to suck up condensed water is impaired.

[0005] The invention disclosed in this specification aims to effectively supply condensed water to intake air with a simple configuration. [Means for solving the problem]

[0006] The above object is achieved by an intake structure of an internal combustion engine including a condensed water reservoir provided upstream of a cooling core provided in an EGR cooler or an intercooler and configured to store condensed water generated in the cooling core, an area in an intake passage that has a lower pressure than the condensed water reservoir when an intake valve is opened, and a condensed water transfer pipe connecting the condensed water reservoir. [Effects of the Invention]

[0007] The invention disclosed in this specification can effectively supply condensed water to intake air with a simple configuration. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing the general configuration of an internal combustion engine equipped with an intake structure according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the general configuration of an internal combustion engine equipped with an intake structure according to a second embodiment. [Figure 3] Figure 3 is a schematic diagram of the intake structure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] (First embodiment) First, the general configuration of an internal combustion engine 1 will be described with reference to Figures 1 and 3. Figure 1 is a schematic diagram showing the general configuration of an internal combustion engine 1 equipped with an intake structure of a first embodiment. Figure 3 is a schematic diagram of the intake structure equipped in the internal combustion engine 1. Note that, since Figure 3 is also used to explain a second embodiment described later, reference numerals used in the second embodiment are also written in Figure 3.

[0011] The internal combustion engine 1 shown in FIG. 1 has four cylinders 50 arranged in series. The internal combustion engine 1 uses hydrogen as fuel, but may also be a gasoline engine or a diesel engine. Note that a fuel supply system and an ignition system are omitted from FIG. 1. Also, only one cylinder 50 is shown in FIG. 3. The number of cylinders and the method of arranging the cylinders are not limited to this and may be any of various conventionally known modes.

[0012] A combustion chamber 50a provided in each cylinder 50 of the internal combustion engine 1 communicates with an intake passage 3 via an intake manifold 2. The intake manifold 2 includes a branch pipe 2a connected to the intake port of each cylinder 50.

[0013] Referring to Figure 3, a piston 51 is slidably housed in a cylinder 50. A combustion chamber 50a is formed between the piston 51 and a cylinder head disposed above the cylinder block. The internal combustion engine 1 is equipped with an intake valve 52 and an exhaust valve 53 that open and close the combustion chamber 50a. The intake valve 52 and the exhaust valve 53 open and close in accordance with the rotation of an intake camshaft and an exhaust camshaft, both of which are drivingly connected to a crankshaft (not shown). As a result, the intake valve 52 and the exhaust valve 53 are driven to open and close at predetermined timing in response to the reciprocating movement of each piston 51, in synchronization with the rotation of the crankshaft.

[0014] An intercooler 4 is provided in the intake passage 3 to cool the gas flowing through the intake passage 3. Connected upstream of the intercooler 4 is a compressor 6 of a turbocharger 5 that operates using exhaust energy as a driving source.

[0015] A throttle valve 10 is disposed upstream of the compressor 6. The throttle valve 10 adjusts the amount of fresh air flowing into the intake passage 3 by changing the cross-sectional area of the intake passage 3. The opening of the throttle valve 10 is controlled by an ECU (Electronic Control Unit), not shown.

[0016] An air cleaner 8 is provided upstream of the throttle valve 10. An EGR gas inlet 7 is provided in the intake passage 3 upstream of the compressor 6 and downstream of the throttle valve 10, and one end of an EGR passage 15 is connected to it.

[0017] The combustion chamber 50a of the internal combustion engine 1 is connected to an exhaust passage 11 via an exhaust manifold 21. A turbine 12 of the turbocharger 5 is provided in the exhaust passage 11. Downstream of the turbine 12, exhaust purification devices 13 and 14 are provided to remove harmful substances such as particulate matter and NOx from the exhaust.

[0018] An EGR gas outlet 23 is provided in the exhaust passage 11, and one end of the EGR passage 15 is connected to the EGR gas outlet 23. Meanwhile, the other end of the EGR passage 15 is connected to the EGR gas inlet 7 of the intake passage 3 as described above. The EGR passage 15 connects the exhaust passage 11 downstream of the turbine 12 with the intake passage 3 upstream of the compressor 6. Note that in this embodiment, two exhaust purification devices 13, 14 are provided, but a single exhaust purification device may be used.

[0019] An EGR cooler 16 that cools the gas flowing through the EGR passage 15 is provided in the middle of the EGR passage 15, and an EGR valve 17 is disposed downstream of the EGR cooler 16. The EGR valve 17 adjusts the amount of exhaust gas that flows into the intake passage 3 via the EGR passage 15 by changing the flow cross-sectional area of the EGR passage 15. The opening degree of the EGR valve 17 is controlled by the ECU.

[0020] When the EGR valve 17 is controlled in the opening direction, the EGR passage 15 is opened, and part of the relatively low-pressure exhaust gas discharged from the exhaust purification device 13 flows into the EGR passage 15 and is recirculated to the intake passage 3 via the EGR cooler 16. The EGR gas recirculated to the intake passage 3 is pressurized by the compressor 6 together with fresh air and supercharged to the internal combustion engine 1. This allows a large amount of exhaust gas to be recirculated to the internal combustion engine 1.

[0021] In this way, by recirculating the exhaust gas using the EGR device 24 including the EGR passage 15, the EGR cooler 16, and the EGR valve 17, it becomes possible to recirculate a large amount of exhaust gas to the internal combustion engine 1, and it becomes possible to more reliably lower the combustion temperature of the mixture in the combustion chamber of the internal combustion engine 1. This reduces the amount of NOx produced in the combustion process.

[0022] The internal combustion engine 1 includes a condensed water reservoir 60 and a condensed water transfer pipe 61. The condensed water reservoir 60 and the condensed water transfer pipe 61 are included in the intake structure. Referring to FIG. 3, the intercooler 4 includes a cooling core 4a therein. The cooling core 4a cools the gas flowing into the intercooler 4. This causes condensed water to be generated from the gas. The condensed water reservoir 60 is provided at a position into which the condensed water generated in the cooling core 4a flows due to gravity. In this embodiment, the condensed water reservoir 60 is provided below the cooling core 4a. The condensed water reservoir 60 is also provided upstream of the intercooler 4. The cooling core 4a causes pressure loss. Therefore, the pressure upstream of the intercooler 4 is higher than the pressure downstream of the intercooler 4. In FIG. 3, reference symbol HP indicates a region where the pressure is higher due to the pressure loss caused by the cooling core 4a.

[0023] The condensed water transfer pipe 61 includes a branch pipe 62 and a one-way valve 63. The branch pipes 62 branch off from the condensed water transfer pipe main body 61a and are connected to the branch pipes 2a of the intake manifold 2. The pressure in each branch pipe 2a decreases when the intake valve 52 opens and the piston 51 descends. As a result, there is a period of time when the pressure in each branch pipe 2a is lower than the pressure in the condensed water reservoir 60. When the pressure in the branch pipe 2a becomes lower than the pressure in the condensed water reservoir 60, the condensed water stored in the condensed water reservoir 60 is sucked into the branch pipe 2a. The sucked condensed water is supplied into the cylinder together with the intake air. This cools the intake air with the latent heat of vaporization of the condensed water. As a result, the oxygen density increases, and the power output of the internal combustion engine 1 can be improved. In FIG. 3, reference symbol LP indicates a region where the pressure becomes lower than the condensed water reservoir 60 when the intake valve 52 opens.

[0024] In the internal combustion engine 1, pressure fluctuations occur in the region from the throttle valve 10 to the combustion chamber 50a, and it is expected that the pressure there will be lower than that in the condensed water reservoir 60. For this reason, the condensed water transfer pipe 61 may be connected to the region of the intake passage 3 that is included in the region from the throttle valve 10 to the combustion chamber 50a. However, even during the same time period, the pressure in each branch pipe 2a will be different. For this reason, it is thought that pressure changes will be unlikely to occur in the region from the throttle valve 10 to the combustion chamber 50a. In contrast, the pressure in the branch pipe 2a provided in each cylinder 50 is likely to change due to the operation of the piston 51 and the intake valve 52 in each cylinder 50. For this reason, in this embodiment, branch pipes 62 are provided and connected to each branch pipe 2a.

[0025] A one-way valve 63 is provided in each branch pipe 62. The one-way valve 63 allows the transfer of condensed water from the condensed water transfer pipe 61 side to the branch pipe 2a side, but blocks the backflow of condensed water from the branch pipe 2a side to the condensed water transfer pipe 61 side. Depending on the pressure state in the branch pipe 2a, it is possible that the pressure in the branch pipe 2a will be higher than the pressure in the condensed water storage section 60. In this case, if the one-way valve 63 were not provided, it is possible that condensed water would flow back from the branch pipe 2a side to the condensed water storage section 60 side. The one-way valve 63 blocks this backflow of condensed water. The one-way valve 63 is provided in each branch pipe 62 because, as described above, the pressure in each branch pipe 2a will be different even during the same time period.

[0026] Each branch pipe 62 may be connected to the intake port of each cylinder 50 .

[0027] According to this embodiment, condensed water generated in the cooling core 4a is stored in the condensed water storage section 60 by gravity. The condensed water stored in the condensed water storage section 60 is then supplied to the intake air through a condensed water transfer pipe 61 that connects the condensed water storage section 60 to an area in the intake passage 3 that has a lower pressure than the condensed water storage section 60 when the intake valve 52 is opened. In this way, this embodiment can effectively supply condensed water to the intake air with a simple configuration.

[0028] In this embodiment, hydrogen is used as fuel. Therefore, it is expected that the EGR gas contains a large amount of moisture, resulting in the generation of a large amount of condensed water. The intake structure of this embodiment can efficiently supply such a large amount of condensed water to the intake air and cool the intake air using the latent heat of vaporization. As described above, this embodiment can be suitably used in an internal combustion engine 1 that uses hydrogen as fuel. As described above, the internal combustion engine 1 can also be a gasoline engine or a diesel engine. Even in such cases, condensed water can be efficiently supplied to the intake air and the intake air can be cooled.

[0029] In addition, since the present embodiment does not use a Venturi tube, for example, it is possible to suppress the occurrence of pressure loss. Furthermore, since a glass capillary tube is not used, malfunctions due to breakage or clogging of the glass capillary tube do not occur.

[0030] Although the intake structure of this embodiment is applied to an internal combustion engine 1 equipped with an EGR device 24, it can also be applied to an internal combustion engine that does not have an EGR device 24 and only has an intercooler 4.

[0031] (Second embodiment) Next, a second embodiment will be described with reference to FIGS. 2 and 3. FIG. 2 is a schematic diagram showing the general configuration of an internal combustion engine 70 equipped with an intake structure of the second embodiment. Unlike the internal combustion engine 1 of the first embodiment, the internal combustion engine 70 of the second embodiment does not include an intercooler 4 or a turbocharger 5. In other words, the internal combustion engine 70 is a naturally aspirated internal combustion engine. The internal combustion engine 70 has a configuration common to the internal combustion engine 1 of the first embodiment, except for not including the intercooler 4 or the turbocharger 5. Therefore, the same reference numerals are used in the drawings for the common components. In the following description, detailed description of the common components will be omitted. Note that when referring to FIG. 3 for the second embodiment, the intercooler 4 and cooling core 4a in the first embodiment will be taken to refer to the EGR cooler 16 and cooling core 16a.

[0032] Similar to the internal combustion engine 1 of the first embodiment, the internal combustion engine 70 of the second embodiment also includes a condensed water storage section 60 and a condensed water transfer pipe 61. The condensed water transfer pipe 61 also includes a condensed water transfer pipe main body 61a, a branch pipe 62, and a one-way valve 63.

[0033] However, the condensed water reservoir 60 is provided upstream of the EGR cooler 16. Referring to FIG. 3, the EGR cooler 16 includes a cooling core 16a. The cooling core 16a cools the gas flowing into the EGR cooler 16. This causes condensed water to be generated from the gas. The condensed water reservoir 60 is provided at a position into which the condensed water generated in the cooling core 16a flows due to gravity. In this embodiment, the condensed water reservoir 60 is provided below the cooling core 16a. The condensed water reservoir 60 is also provided upstream of the EGR cooler 16. The cooling core 16a causes a pressure loss. Therefore, the pressure upstream of the EGR cooler 16 is higher than the pressure downstream of the EGR cooler 16.

[0034] With this configuration, condensed water can be supplied to the intake air in the same manner as in the first embodiment. Note that, since the first embodiment includes the turbocharger 5, the pressure in the branch pipe 2a is higher than that in the second embodiment. Therefore, in the first embodiment, even if condensed water is to be supplied from the condensed water reservoir 60 provided upstream of the EGR cooler 16 as in the second embodiment, it is not possible to transfer the condensed water appropriately. For this reason, when the turbocharger 5 is provided, it is desirable to adopt the first embodiment.

[0035] The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited to these. Various modifications of these embodiments are within the scope of the present invention, and it is obvious from the above description that various other embodiments are possible within the scope of the present invention. [Explanation of symbols]

[0036] 1...internal combustion engine, 4...intercooler, 5...turbocharger, 16...EGR cooler, 60...condensate reservoir, 61...condensate transfer pipe, 62...branch pipe, 63...one-way valve

Claims

[Claim 1] a condensed water reservoir provided upstream of a cooling core included in the EGR cooler or the intercooler, the condensed water reservoir configured to store condensed water generated in the cooling core; a condensed water transfer pipe connecting a region in the intake passage that has a lower pressure than the condensed water reservoir when the intake valve is opened to the condensed water reservoir; 1. An intake structure for an internal combustion engine, including:

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