Hydrogen engine and combustion control method

Abstract

The application discloses a hydrogen engine and a combustion control method. The hydrogen engine comprises a cylinder cover, an air inlet valve, an air outlet valve, a fuel nozzle and a spark plug arranged on the cylinder cover; a cylinder body connected below the cylinder cover, a piston arranged in the cylinder body, the periphery of the piston being sealed and matched with the inner peripheral wall of the cylinder body and being arranged in the cylinder body in a vertical and slidable mode; the inner surface of the cylinder cover is concave upward to form a first spherical surface, the top surface of the piston is concave downward to form a second spherical surface, and a combustion chamber is formed between the cylinder cover and the piston. The application can reduce the knocking tendency and improve the combustion efficiency.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of internal combustion engines, and particularly relates to a hydrogen engine and a combustion control method. BACKGROUND

[0002] In a vehicle engine or a large-bore natural gas engine, lean combustion is a recognized effective means to improve engine thermal efficiency and reduce emissions, and within a certain dilution range, the thermal efficiency of the engine gradually increases.

[0003] A hydrogen engine using hydrogen as fuel can expand the lean combustion limit, accelerate combustion, and improve flame stability. However, current hydrogen engines are mostly directly modified from gasoline or diesel engines, and using hydrogen as fuel can easily cause knocking, large heat loss, and low combustion efficiency. SUMMARY

[0004] The purpose of the present disclosure is to provide a hydrogen engine and a combustion control method that can reduce the tendency of knocking and improve combustion efficiency.

[0005] The first aspect of the present application discloses a hydrogen engine, comprising: a cylinder head, the cylinder head is provided with an intake valve, an exhaust valve, a fuel nozzle and a spark plug; a cylinder body connected below the cylinder head, a piston is arranged in the cylinder body, the peripheral side of the piston is sealingly fitted with the inner peripheral wall of the cylinder body, and the piston is vertically slidably arranged in the cylinder body; the inner surface of the cylinder head is concave upward to form a first spherical surface, the top surface of the piston is concave downward to form a second spherical surface, and a combustion chamber is formed between the cylinder head and the piston.

[0006] In an exemplary embodiment of the present disclosure, the radius corresponding to the second spherical surface is 1.2 to 1.5 times the radius corresponding to the first spherical surface.

[0007] In an exemplary embodiment of the present disclosure, the arc corresponding to the second spherical surface is 120 to 150 degrees.

[0008] In an exemplary embodiment of the present disclosure, the spark plug includes a spark plug body mounted on the cylinder head, and a plurality of electrodes arranged on the spark plug body, the plurality of electrodes are distributed along the circumference of the spark plug body, one end of the electrode away from the spark plug body extends into the combustion chamber, and can form a discharge channel with the inner surface of the cylinder head when the electrode discharges.

[0009] In an exemplary embodiment of the present disclosure, the plurality of electrodes are uniformly distributed around the central axis of the combustion chamber, so that the plurality of electrodes away from the one end of the spark plug body and the shortest distance of the inner surface of the cylinder head are equal.

[0010] In an exemplary embodiment of the present disclosure, the electrode comprises, in the direction from top to bottom, a vertical segment, a bent segment and a horizontal segment connected in sequence, the vertical segment extends vertically and is connected with the spark plug body, the bent segment extends in the direction gradually away from the axis of the combustion chamber in the direction from top to bottom, and the horizontal segment extends horizontally.

[0011] In an exemplary embodiment of the present disclosure, the shortest distance between the end of the electrode away from the spark plug body and the inner surface of the cylinder head is 0.4mm-0.9mm.

[0012] In an exemplary embodiment of the present disclosure, the number of the electrodes is 4-6.

[0013] In an exemplary embodiment of the present disclosure, the surface of the combustion chamber is coated with a platinum coating.

[0014] The second aspect of the present application discloses a combustion control method applied to the hydrogen engine, comprising:

[0015] The intake valve controls the air supply amount in the combustion chamber, and the fuel nozzle controls the fuel supply amount in the combustion chamber, so that the excess air coefficient in the combustion chamber is greater than 3, and the spark plug ignites at the crank angle of the piston between 10° and -3°.

[0016] The present application has the following beneficial effects:

[0017] In the present application, the combustion chamber structure is optimized to be arranged, the inner surface of the cylinder head is concave upward to form a first spherical surface, and the top surface of the piston is concave downward to form a second spherical surface, so that the overall combustion chamber is spherical, the combustion chamber volume is larger under the same surface area, the surface-volume ratio of the combustion chamber is smaller, thereby the heat loss and wall quenching effect can be reduced, the combustion efficiency can be improved, the flame propagation distance can be shortened, and the probability of knock can be reduced. By using the combustion control method of the present application, the combustion temperature can be reduced, and the emission of nitrogen oxides can be reduced.

[0018] Other characteristics and advantages of the present application will become apparent from the following detailed description, or will be learned by practice of the present application.

[0019] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the present disclosure and, together with the description, further serve to explain the principles of the present disclosure. It is to be understood that the drawings are only schematic, and that they do not purport to be to scale with respect to one another. The embodiments presented herein are by way of example only, and various changes might be made by persons skilled in the art without departing from the scope of the disclosure.

[0021] Figure 1 A cross-sectional view of a hydrogen engine according to the present embodiment.

[0022] BRIEF DESCRIPTION OF DRAWINGS

[0023] 1: Cylinder head; 11: Intake valve; 12: Exhaust valve; 13: Fuel nozzle; 14: Spark plug; 141: Spark plug body; 142: Electrode; 15: Intake port; 16: Exhaust port; 17: First spherical surface; 2: Cylinder block; 21: Piston; 22: Second spherical surface; 3: Combustion chamber. DETAILED DESCRIPTION

[0024] Example implementations will now be described with reference to the drawings; however, example implementations can be implemented in many different forms and should not be construed as limited to the examples set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example implementations to those skilled in the art.

[0025] Moreover, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the

[0026] The application will be further described with reference to the drawings and specific examples. It is to be expressly understood that the description of various embodiments of the application set out herein is intended as a description of various modes by which the application can be practiced. In this regard, no individual element or

[0027] Example 1

[0028] Because of the existence of the lean limit of fuel, with the increase of dilution rate, the ignition difficulty increases, the combustion instability increases, and the cycle variation of the engine increases. The engine using hydrogen as fuel can expand the lean limit to accelerate combustion and improve flame stability. However, the current hydrogen engine is mostly directly modified from gasoline engine or diesel engine, and using hydrogen as fuel is easy to cause knocking, large heat loss and low combustion efficiency. The embodiment is to solve the above problems.

[0029] Referring to Figure 1 A hydrogen engine, comprising a cylinder head 1 and a cylinder body 2. The cylinder body 2 is connected below the cylinder head 1, and the two are combined to form the shell of the engine. The cylinder head 1 and the cylinder body 2 can be integrally cast or separately cast and then assembled. It can be understood that the cylinder head 1 and the cylinder body 2 both have an inner cavity.

[0030] Among them, the cylinder head 1 is provided with an intake valve 11, an exhaust valve 12, a fuel nozzle 13 and a spark plug 14, and the cylinder body 2 is provided with a piston 21. The peripheral side of the piston 21 is sealingly attached to the inner peripheral wall of the cylinder body 2, and is vertically slidably arranged in the cylinder body 2. The bottom of the piston 21 is connected to the crankshaft, and the cylinder head 1 and the piston 21 form a combustion chamber 3. Specifically, the cylinder head 1 is provided with an intake passage 15 and an exhaust passage 16 which communicate with the combustion chamber 3. The intake valve 11 and the exhaust valve 12 are respectively arranged at one end of the intake passage 15 and the exhaust passage 16 which communicate with the combustion chamber 3. The intake valve 11 opens or closes the intake passage 15, and the exhaust valve 12 opens or closes the exhaust passage 16 to control the amount of air entering the combustion chamber 3. The injection end of the fuel nozzle 13 communicates with the combustion chamber 3 for injecting fuel, which is hydrogen in this embodiment. The spark plug 14 is responsible for ignition.

[0031] When the engine is working, the movement process of the intake valve 11, the exhaust valve 12, the fuel nozzle 13, the spark plug 14 and the piston 21 will not be described here, and can refer to the existing engine.

[0032] In this embodiment, the inner surface of the cylinder head 1 is concave upward to form a first spherical surface 17, and the top surface of the piston 21 is concave downward to form a second spherical surface 22, so that when the piston 21 moves to the top dead center, the combustion chamber 3 is spherical as a whole. Under the same surface area, the volume of the combustion chamber 3 is larger, and the surface-volume ratio of the combustion chamber 3 is smaller, so that the heat loss and the wall quenching effect can be reduced, the combustion efficiency can be improved, the flame propagation distance can be shortened, and the probability of knocking can be reduced.

[0033] Further, the radius corresponding to the second spherical surface 22 is 1.2 to 1.5 times the radius corresponding to the first spherical surface 17, so that the depth of the combustion chamber 3 corresponding to the second spherical surface 22 in the vertical direction is shallower than the depth of the combustion chamber 3 corresponding to the first spherical surface 17 in the vertical direction, the volume of the part of the combustion chamber corresponding to the cylinder head 1 is larger, and more fuel is located in the part of the combustion chamber corresponding to the cylinder head 1 at the time of ignition, so that the spark plug 14 is more likely to ignite successfully. It can be understood that in the embodiment, the centers of the first spherical surface 17 and the second spherical surface 22 are on the same central axis, and the radius corresponding to the second spherical surface 22 can be one of 1.2 times, 1.35 times, 1.5 times, etc. of the radius corresponding to the first spherical surface 17, and the specific multiple is subject to actual design. At the same time, the arc corresponding to the second spherical surface 22 is 120 degrees to 150 degrees, which can be one of 120 degrees, 135 degrees, 150 degrees, etc., and the arc corresponding to the first spherical surface 17 is 180 degrees.

[0034] For example, the spark plug 14 includes a spark plug body 141 mounted on the cylinder head 1 and a plurality of electrodes 142 provided on the spark plug body 141, which are distributed along the circumference of the spark plug body 141. One end of the electrode 142 away from the spark plug body 141 extends into the combustion chamber 3 and acts as a side electrode, the cylinder head 1 contacts the spark plug body 141 and acts as a center electrode, and the electrode 142 can form a discharge channel with the inner surface of the cylinder head 1 when discharging, and a “breakdown” phenomenon occurs at this time. At this time, the gas forms a luminous body, i.e. “spark”, thereby igniting the mixture in the combustion chamber 3. The plurality of ignition points can increase the ignition points, accelerate combustion, further reduce the tendency of knocking, and make the mixture in the combustion chamber 3 more stable, thereby improving the combustion stability. At the same time, the lean burn limit can be expanded, the combustion temperature can be reduced, the fuel combustion thermal efficiency can be improved, and the emission of nitrogen oxides can be reduced. The number of electrodes 142 can be 4 to 6, and in the embodiment, the number of electrodes 142 is 4.

[0035] Further, the plurality of electrodes 142 are uniformly distributed around the central axis of the combustion chamber 3, so that the shortest distance between one end of the electrode 142 away from the spark plug body 141 and the inner surface of the cylinder head 1 is equal, thereby enabling the plurality of electrodes 142 to discharge at the same time to increase the ignition success rate, reduce the tendency of knocking, and improve the combustion stability. The shortest distance between one end of the electrode 142 away from the spark plug body 141 and the inner surface of the cylinder head 1 is 0.4 mm to 0.9 mm, which can ensure that the electrode 142 can ignite successfully when discharging.

[0036] Further, the electrode 142 comprises a vertical segment, a bending segment and a horizontal segment connected in sequence from top to bottom, the vertical segment extends along the vertical direction and is connected with the spark plug body 141, the bending segment extends along the direction gradually away from the axis of the combustion chamber 3 from top to bottom, and the horizontal segment extends horizontally, so that the distance between the end of the horizontal segment and the inner surface of the cylinder head 1 is shortened, the flame propagation distance is shortened, and the ignition success is more favorable. Of course, in other embodiments, the electrode 142 can also only comprise a vertical segment and a horizontal segment connected, so that the whole is L-shaped.

[0037] For example, the surface of the combustion chamber 3 is coated with a platinum coating, which can improve the corrosion resistance of the surface of the combustion chamber 3, prolong the service life of the engine, and reduce performance degradation. When metal platinum encounters hydrogen, hydrogen ions are produced, further accelerating combustion, improving combustion efficiency, reducing knock tendency, and improving fuel thermal efficiency. At the same time, hydrogen in the slit will also be oxidized to hydrogen ions when it encounters platinum. During engine operation, it can be oxidized and combusted to improve fuel utilization. For engine oil entering the combustion chamber 3 during engine operation, a catalytic reaction will occur after encountering platinum to produce carbon dioxide, which can reduce the problem of pre-ignition and solid suspended particle emissions caused by engine oil.

[0038] It can be understood that in the embodiment, the first spherical surface 17 and the second spherical surface 22 are both coated with a platinum coating. Since the intake valve 11 and the exhaust valve 12 are arranged at the end of the intake port 15 and the exhaust port 16 communicating with the combustion chamber, when the intake valve 11 and the exhaust valve 12 close the intake port 15 and the exhaust port 16, the outer surface of the intake valve 11 and the exhaust valve 12 is in contact with the inner surface of the cylinder head 1 to form the first spherical surface 17, so the outer surface of the intake valve 11 and the exhaust valve 12 is also coated with a platinum coating.

[0039] Embodiment Two

[0040] The embodiment provides a combustion control method applied to the hydrogen engine, which comprises: controlling the air supply amount in the combustion chamber 3 by the intake valve 11, and controlling the fuel supply amount in the combustion chamber 3 by the fuel nozzle 13, so that the excess air ratio in the combustion chamber 3 is greater than 3, and the spark plug 14 ignites at the crank angle of the piston 21 between 10° and -3°.

[0041] Since the structure of the combustion chamber 3 of the hydrogen engine is improved, the combustion efficiency is more easily improved, and the ignition success is more easily achieved, so that the combustion in the combustion chamber 3 can be operated in the mode that the excess air ratio is greater than 3, and the combustion temperature in the combustion chamber 3 of the engine during operation is lower than 1400K, the generated emissions after ignition are only a small amount of carbon dioxide, and no nitrogen oxides are generated, so that the ultra-lean combustion is achieved.

[0042] In addition, the terms "first", "second", etc. are used only for the purpose of description, and should not be understood as indicating or implying relative importance or implying a number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0043] In the present application, unless otherwise explicitly specified and limited, the terms "assembly", "connection" and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] In the description of the present application, the description referring to the terms "some embodiments", "exemplarily" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are contained in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples, without contradiction.

[0045] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application. Therefore, any changes or modifications made in accordance with the claims and description of the present application shall be within the scope of the present application.

Claims

1. A hydrogen engine, characterized in that, include: Cylinder head, wherein an intake valve, an exhaust valve, a fuel injector and a spark plug are provided on the cylinder head; A cylinder block is connected to the cylinder head below. A piston is disposed in the cylinder block. The periphery of the piston is sealed and fitted to the inner peripheral wall of the cylinder block and is slidably disposed in the cylinder block in a vertical direction. The inner surface of the cylinder head is recessed upward to form a first spherical surface, and the top surface of the piston is recessed downward to form a second spherical surface. A combustion chamber is formed between the cylinder head and the piston. The spark plug includes a spark plug body mounted on the cylinder head and a plurality of electrodes disposed on the spark plug body. The plurality of electrodes are distributed circumferentially along the spark plug body. One end of the electrode away from the spark plug body extends into the combustion chamber and can form a discharge channel with the inner surface of the cylinder head when the electrode discharges.

2. The hydrogen engine according to claim 1, characterized in that, The radius corresponding to the second sphere is 1.2 to 1.5 times the radius corresponding to the first sphere.

3. The hydrogen engine according to claim 1 or 2, characterized in that, The arc corresponding to the second sphere is 120 degrees to 150 degrees.

4. The hydrogen engine according to claim 1, characterized in that, The plurality of electrodes are evenly distributed around the central axis of the combustion chamber, such that the shortest distance between the end of the plurality of electrodes away from the spark plug body and the inner surface of the cylinder head is equal.

5. The hydrogen engine according to claim 4, characterized in that, The electrode comprises a vertical segment, a bent segment, and a horizontal segment connected in sequence from top to bottom. The vertical segment extends vertically and is connected to the spark plug body. The bent segment extends from top to bottom in a direction gradually away from the central axis of the combustion chamber. The horizontal segment extends horizontally.

6. The hydrogen engine according to claim 4 or 5, characterized in that, The shortest distance between the end of the electrode facing away from the spark plug body and the inner surface of the cylinder head is 0.4mm to 0.9mm.

7. The hydrogen engine according to claim 4, characterized in that, The number of electrodes is 4 to 6.

8. The hydrogen engine according to claim 1, characterized in that, The surface of the combustion chamber is coated with a platinum coating.

9. A combustion control method, characterized in that, Applied to the hydrogen engine as described in any one of claims 1 to 8, comprising: The intake valve controls the amount of air supplied to the combustion chamber, and the fuel injector controls the amount of fuel supplied to the combustion chamber, so that the excess air coefficient in the combustion chamber is greater than 3, and the spark plug ignites the piston when the crankshaft angle is between 10° and -3°.

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