Hydrogen engine

Abstract

To provide a hydrogen engine that can suppress abnormal combustion of hydrogen gas. [Solution] The hydrogen engine includes a combustion chamber for burning a mixture of air and hydrogen gas, an injector for directly injecting the hydrogen gas into the combustion chamber, an insertion hole communicating with the combustion chamber into which the injector is inserted, and a spacer member mainly composed of copper, which is placed in the gap between the inner wall of the insertion hole on the combustion chamber side and the tip of the injector in the direction of hydrogen gas injection.

Description

Technical Field

[0001] The present invention relates to a hydrogen engine.

Background Art

[0002] Regarding hydrogen engines, for example, Patent Document 1 describes a liquid hydrogen system for supplying hydrogen to a hydrogen engine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A direct injection (DI) injector directly injects hydrogen gas into the combustion chamber of a hydrogen engine. The DI injector is inserted into an insertion hole provided in the cylinder head of the hydrogen engine. A space called a sack or the like is provided between the tip of the DI injector where hydrogen gas is injected and the inner wall on the combustion chamber side of the insertion hole to suppress wear of the needle of the DI injector.

[0005] However, the hydrogen gas injected from the tip of the DI injector may enter the sack due to the tumble flow in the combustion chamber, and after the combustion of the air-fuel mixture in the combustion chamber, it may remain in the sack in a high-temperature state without being exhausted unburned. In this case, when new hydrogen gas is injected, the hydrogen gas in the sack may ignite and cause abnormal combustion such as pre-ignition.

[0006] Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a hydrogen engine capable of suppressing abnormal combustion of hydrogen gas.

Means for Solving the Problems

[0007] The hydrogen engine of the present invention comprises a combustion chamber for burning a mixture of air and hydrogen gas, an injector for directly injecting the hydrogen gas into the combustion chamber, an insertion hole communicating with the combustion chamber into which the injector is inserted, and a spacer member mainly composed of copper, which is disposed in the gap between the inner wall of the insertion hole on the combustion chamber side and the tip of the injector in the direction of hydrogen gas injection.

[0008] In the hydrogen engine described above, the spacer member may be fixed to the inner wall by adhesive bonding.

[0009] In the hydrogen engine described above, the spacer member may have holes through which the hydrogen gas injected from the injector into the combustion chamber passes. [Effects of the Invention]

[0010] According to the present invention, abnormal combustion of hydrogen gas can be suppressed in a hydrogen engine. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic partial cross-sectional view showing an example of a hydrogen engine. [Figure 2] Figure 2 is a schematic plan view showing the bottom surface of the cylinder head. [Figure 3] Figure 3 is a partial cross-sectional view of the cylinder head along line AA in Figure 2. [Figure 4] Figure 4 shows an example of a spacer member in plan view and side view. [Modes for carrying out the invention]

[0012] Figure 1 is a schematic partial cross-sectional view showing an example of a hydrogen engine 1. The hydrogen engine 1 comprises a cylinder block 2, a cylinder head 3, a piston 4, a connecting rod 5, and a direct injection injector (hereinafter referred to as injector) 8. The hydrogen engine 1 is installed as a power source in vehicles such as hydrogen-powered cars. Figures 1 to 3 show the mutually orthogonal X, Y, and Z directions.

[0013] The cylinder head 3 is joined to the cylinder block 2 at an interface P along the XY plane. Inside the cylinder block 2, a cylinder 6 is provided, oriented in the Z direction. The cylinder head 3 is positioned to close one open end of the cylinder 6. The cylinder block 2 and cylinder head 3 are made of metal such as aluminum alloy or cast iron.

[0014] The piston 4 reciprocates within the cylinder 6 in the Z direction. The piston 4 is connected to the connecting rod 5 via a piston pin. The connecting rod 5 is connected to the crankshaft (not shown) via a crank pin. The connecting rod 5 acts to convert the reciprocating motion of the piston 4 into rotational motion of the crankshaft. In addition, the walls of the cylinder 6 in the cylinder block 2, the cylinder head 3, and the top surface of the piston 4 define a combustion chamber 7 where a mixture of air and hydrogen gas burns.

[0015] The cylinder head 3 is provided with an intake port 11 for intake and an exhaust port 12 for exhaust, adjacent to each other in the X direction. The intake port 11 faces the combustion chamber 7 and communicates with the combustion chamber 7 through an intake opening 13 formed in the cylinder head 3. The exhaust port 12 faces the combustion chamber 7 and communicates with the combustion chamber 7 through an exhaust opening 14 formed in the cylinder head 3. The cylinder head 3 is also provided with an intake valve 21 for opening and closing the intake opening 13, an exhaust valve 31 for opening and closing the exhaust opening 14, a spark plug 41 for igniting the air-fuel mixture in the combustion chamber 7, and an injector 8 for directly injecting hydrogen gas into the combustion chamber 7.

[0016] Figure 2 is a schematic plan view showing the bottom surface of the cylinder head 3. The combustion chamber 7 is provided with two sets of intake openings 13 and exhaust openings 14. The two intake openings 13 are arranged side by side in the Y direction, and the two exhaust openings 14 are also arranged side by side in the Y direction. The spark plug 41 is positioned along the Z direction and is located substantially in the center of the two intake openings 13 and the two exhaust openings 14. The injector 8 is inserted into an insertion hole 45 in the cylinder head 3 and injects hydrogen gas into the combustion chamber 7 through an injection hole 62 that opens into the combustion chamber 7. The injector 8 is positioned such that its axis L is along the X direction and passes through the midpoint between the two intake openings 13 and the midpoint between the two exhaust openings 14 in the Y direction.

[0017] Figure 3 is a partial cross-sectional view of the cylinder head 3 along line AA in Figure 2. The injector 8 is inserted into an insertion hole 45 in the cylinder head 3. The insertion hole 45 extends toward approximately the center of the combustion chamber 7 and is formed according to the shape of the injector 8. The insertion hole 45 communicates with the combustion chamber 7 through an injection hole 62.

[0018] The injector 8 has a roughly cylindrical main body 80, an extension 81 extending from the main body 80, and a tip 810 provided at the tip of the extension 81. The extension 81 has a smaller diameter than the main body 80 and is roughly cylindrical with a constriction in the middle, and a roughly band-shaped sealing member 82 is wrapped around the constricted portion. The sealing member 82 is made of, for example, Teflon (registered trademark) and seals the gap between it and the inner wall of the insertion hole 45. This maintains the airtightness of the combustion chamber 7. However, if the airtightness of the combustion chamber 7 is maintained, it is not necessarily required to provide the sealing member 82.

[0019] The tip portion 810 has a tapered annular shape facing the injection direction of hydrogen gas, and in the insertion hole 45, it faces the inner wall 450 on the combustion chamber 7 side adjacent to the edge of the opening of the injection hole 62. A gap 61, called a sac or the like, is formed between the tip portion 810 and the inner wall 450. Inside the tip portion 810 and the extension portion 81, a delivery hole 811 through which hydrogen gas is delivered is provided along the axis L direction. The hydrogen gas enters the gap 61 from the delivery hole 811 and is injected into the combustion chamber 7 through the injection hole 62 as indicated by the arrow D. Note that the direction in which the injection hole 62 extends is inclined by a predetermined angle with respect to the axis L of the injector 8 so that the hydrogen gas is injected in an appropriate direction inside the combustion chamber 7.

[0020] The tip portion 810 of the injector 8 is separated from the combustion chamber 7 by the gap 61 between it and the inner wall 450 of the insertion hole 45. Thereby, compared with the case where the gap 61 does not exist, the temperature rise of the needle (not shown) etc. of the injector 8 is suppressed.

[0021] As indicated by the reference sign E, the insertion hole 45 has a stepped portion 451 formed so as to abut on the front end side surface of the main body portion 80. When the main body portion 80 and the stepped portion 451 abut, the injector 8 is positioned with respect to the insertion hole 45.

[0022] A spacer member 9 mainly composed of copper is provided in the gap 61 between the inner wall 450 of the insertion hole 45 and the tip portion 810. In FIG. 3, the spacer member 9 is shown as a cross section along the X-Z plane. The spacer member 9 promotes the combustion of the hydrogen gas and air (oxygen) that have entered the gap 61 due to the tumble flow F generated in the combustion chamber 7. At this time, the copper of the material of the spacer member 9 acts as a catalyst for the combustion reaction of the hydrogen gas and oxygen. Note that the spacer member 9 may be formed only of copper, or may be an alloy of copper and other metals.

[0023] Figure 4 shows an example of a spacer member 9 in plan view and side view. The spacer member 9 has a substantially annular shape in which the diameter decreases in the direction of hydrogen gas injection. A central hole 90 is provided in the center of the spacer member 9 in plan view. The spacer member 9 is positioned so that the position of the central hole 90 coincides with the position of the injection hole 62, so that hydrogen gas is injected from the injector 8 through the central hole 90 into the combustion chamber 7, as shown by arrow D in Figure 3. Note that the central hole 90 is just one example of a hole. The spacer member 9 may also have other shapes that do not have a central hole 90.

[0024] The lower surface 91 of the spacer member 9 faces the opening of the injection hole 62 and is inclined from the outer edge toward the central hole 90 so as to be convex toward the combustion chamber 7. The upper surface 92 of the spacer member 9 faces the tip 810 of the injector 8 and is inclined from the outer edge toward the central hole 90 so as to be concave toward the tip 810. As a result, the hydrogen gas injected from the injector 8 is delivered to the combustion chamber 7 more smoothly than if the upper surface 92 and lower surface 91 were substantially flat. However, the upper surface 92 and lower surface 91 may be substantially flat.

[0025] The spacer member 9 is fixed by being bonded to the inner wall 450 of the insertion hole 45 with an adhesive. This suppresses displacement of the spacer member 9 due to vibrations of the hydrogen engine 1. The spacer member 9 is not limited to being fixed by adhesive; for example, it may be fixed by fitting into a groove formed in the insertion hole 45. However, in this case, the shape of the spacer member 9 and the insertion hole 45 becomes more complex, and the assembly of the spacer member 9 becomes more difficult. Alternatively, the spacer member 9 could be fixed by bringing the tip 810 of the injector 8 into contact with a part of the upper surface 92 of the spacer member 9 and sandwiching it between the inner wall 450. However, in this case, vibrations of the hydrogen engine 1 are transmitted to the injector 8, which is undesirable.

[0026] The copper material of the spacer member 9 acts as a catalyst for the combustion of hydrogen gas and air (oxygen) in the gap 61. This promotes the oxidation reaction of the high-temperature hydrogen gas in the gap 61, generating moisture. Therefore, compared to the case where the spacer member 9 is not present, the amount of hydrogen gas in the gap 61 is reduced after combustion in the combustion chamber 7.

[0027] The embodiments described above are preferred examples of the present invention. However, the invention is not limited thereto, and various modifications are possible without departing from the spirit of the invention. [Explanation of Symbols]

[0028] 1 Hydrogen engine, 7 Combustion chamber, 8 Direct injection injector (injector), 9 Spacer member, 45 Insertion hole, 61 Gap, 82 Seal member, 810 Tip

Claims

1. A combustion chamber for burning a mixture of air and hydrogen gas, An injector that directly injects the hydrogen gas into the combustion chamber, An insertion hole that communicates with the combustion chamber and into which the injector is inserted, A spacer member, mainly composed of copper, is positioned in the gap between the inner wall of the insertion hole on the combustion chamber side and the tip of the injector in the direction of hydrogen gas injection. Hydrogen engine.

2. The spacer member is fixed to the inner wall by adhesive. The hydrogen engine according to claim 1.

3. The spacer member has a hole through which the hydrogen gas injected from the injector into the combustion chamber passes. A hydrogen engine according to claim 1 or 2.

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