Methanol engine

Abstract

The invention relates to a methanol engine. The methanol engine comprises a cylinder body assembly and a cylinder cover assembly, the cylinder body assembly and the cylinder cover assembly are used for forming a combustion chamber, and the compression ratio of the combustion chamber ranges from 13 to 16; the cylinder body assembly comprises a piston, and the piston is provided with a tumble concave face facing the cylinder cover assembly. The cylinder cover assembly comprises a cylinder cover and two exhaust valves, the cylinder cover is provided with an air inlet channel with the flow coefficient larger than or equal to 0.3, and the air inlet channel comprises an outer air inlet channel and two air inlet fork channels communicated between the outer air inlet channel and the combustion chamber. The exhaust valves are used for reflecting air inlet flow of the corresponding air inlet forked channels to the tumble concave faces, so that the tumble ratio of the methanol engine is larger than or equal to 2.4. The methanol engine can achieve high heat efficiency.

Description

Technical Field

[0001] This application relates to the technical field of engines, and particularly to methanol engines. Background Art

[0002] In order to reduce the dependence on petroleum, people have searched for some alternative energy sources to petroleum.

[0003] For example, methanol is a good fuel. The carbon dioxide produced by methanol combustion is less than that of gasoline and diesel, which can greatly reduce pollutant emissions. The price of methanol is usually lower than that of gasoline and diesel. Using methanol as a fuel can reduce the vehicle operation cost. The construction of methanol energy has been vigorously developed.

[0004] However, the research on methanol combustion needs to be strengthened. Due to the different characteristics of methanol from traditional fuels, there are some deficiencies in directly using methanol as a fuel in traditional engines.

[0005] For example, traditional heavy-duty engines are diesel engines. The intake port design of diesel engines usually focuses on high flow rate and low resistance. When applying methanol, due to problems such as high volatility and low calorific value of methanol compared with diesel, if methanol is directly burned in a diesel engine, it will cause premature evaporation of methanol in the intake port, resulting in an overly lean or unevenly distributed air-fuel mixture, affecting the combustion efficiency. In addition, if the combustion is incomplete, due to the relative increase in incomplete combustion and heat loss inside the engine at low speeds, it will be difficult for the engine to reach a high level of thermal efficiency, the combustion economy of methanol will become poor, the vehicle's cruising range will be seriously affected, and at the same time, the economic burden on users will increase. Summary of the Invention

[0006] Based on this, it is necessary to provide a methanol engine for at least one of the above problems.

[0007] This application provides a methanol engine, which includes: a cylinder block assembly and a cylinder head assembly. The cylinder block assembly and the cylinder head assembly are used to form a combustion chamber, and the compression ratio of the combustion chamber ranges from 13 to 16. The cylinder block assembly includes a piston, and the piston has a tumble concave surface facing the cylinder head assembly. The cylinder head assembly includes a cylinder head and two exhaust valves. The cylinder head has an intake port with a flow coefficient greater than or equal to 0.3. The intake port includes an outer intake port and two intake forks respectively communicating between the outer intake port and the combustion chamber. The exhaust valves are used to reflect the intake air flow of the corresponding intake forks to the tumble concave surface, so that the tumble ratio of the methanol engine is greater than or equal to 2.4.

[0008] Through the combustion chamber structure design, it is possible to enable the methanol mixture to quickly enter the combustion chamber through the intake passage at low engine speeds. The air flow blows onto the exhaust valve and is then reflected onto the tumble concave surface of the piston. The intake air flow is in a tumble state, which can accelerate the rapid mixing of methanol droplets and gas, thereby forming a uniform methanol mixture gas with a high turbulence intensity. A high intake air volume can increase the total heat of methanol combustion. The compression ratio of the methanol engine is relatively large, which is conducive to the full combustion of methanol under high temperature and high pressure conditions. Methanol can undergo chemical reactions more thoroughly, release more energy, and also improve the ratio of the methanol engine to convert chemical energy into mechanical energy, thus enhancing the thermal efficiency. In addition, the flame propagation speed in the methanol engine is higher. In an environment with a high compression ratio, the mixture gas in the combustion chamber is in a high temperature and high pressure state, which is conducive to the propagation of the flame. The flame can propagate through the mixture gas at a faster speed, making the combustion process more stable and rapid, reducing fluctuations and abnormal conditions during the combustion process, such as reducing the occurrence probability of knocking, etc., and ensuring the stable operation of the methanol engine. Additionally, by improving the thermal efficiency, the fuel economy of the methanol engine is enhanced, and the user's operating cost is reduced.

[0009] In some embodiments, the outer intake passage has a saddle-shaped surface at the bifurcation of the two intake forks; the cylinder head also has two exhaust forks, and the exhaust forks and the intake forks are arranged radially opposite to each other along the piston; wherein, the cylinder head assembly further includes two intake valves corresponding to the two intake forks one by one.

[0010] With such a setting, it is beneficial to reduce the flow resistance of the gas and help the air flow to be evenly distributed to the two intake forks; the two air flows can quickly enter the combustion chamber.

[0011] In some embodiments, the first inclination angle of the axis of the intake valve relative to the radial direction is smaller than the second inclination angle of the axis of the exhaust valve relative to the radial direction. The range of the first inclination angle α3 is from 63° to 67°, and the range of the second inclination angle α7 is from 68° to 72°.

[0012] With such a setting, it helps to configure the combustion chamber structure and also helps to ensure the compression ratio.

[0013] In some embodiments, the cylinder head has a mounting surface for mounting to the cylinder block; based on the axial section defined by the axis of the intake valve and the radial direction of the piston, the intake manifold has an intake manifold port, a first flow line, and a second flow line. The first flow line is located between the second flow line and the mounting surface. The first flow line includes an air flow guiding section extending to the intake manifold port and a first arc section extending from the air flow guiding section. The second flow line includes a second arc section extending to the intake manifold port. The radius R10 of the first arc section ranges from 13 mm to 18 mm, the length L5 of the air flow guiding section ranges from 3 mm to 6 mm, the radius R11 of the second arc section ranges from 47 mm to 52 mm, the opening size W3 of the intake manifold port ranges from 29 mm to 33 mm; along the axial direction of the piston, the distance h4 between the intake manifold port and the mounting surface ranges from 15 mm to 19 mm.

[0014] With such a setting, it helps to determine the flow direction, velocity, flow coefficient, and tumble ratio of the air-fuel mixture.

[0015] In some embodiments, the first inclination angle α3 is 65°, and the second inclination angle α7 is 70°; the air flow guiding section is parallel to the mounting surface; the radius R10 of the first arc section is 15 mm, the length L5 of the air flow guiding section is 4 mm, the radius R11 of the second arc section is 50 mm, the opening size W3 of the intake manifold port is 31 mm; the distance h4 between the intake manifold port and the mounting surface is 17 mm.

[0016] With such a setting, it is beneficial to optimize the methanol engine.

[0017] In some embodiments, based on the axial section, the first flow line further includes a first guiding section extending to the outer intake passage, and the second flow line further includes a second guiding section extending to the outer intake passage; the length L3 of the first guiding section ranges from 33 mm to 36 mm, the angle α4 between the first guiding section and the axis of the intake valve ranges from 33° to 36°, the length L4 of the second guiding section ranges from 43 mm to 47 mm, the angle α2 between the second guiding section and the axis of the intake valve ranges from 38° to 42°; the opening size h3 of the outer port of the intake manifold ranges from 37 mm to 41 mm.

[0018] With such a setting, it helps to determine the flow rate of the air-fuel mixture, that is, the magnitude of the flow coefficient.

[0019] In some embodiments, based on the axial section, the opening size h1 of the outer port of the outer intake passage ranges from 53 mm to 58 mm; based on the longitudinal section perpendicular to the axial section, the distance W2 between the two intake manifolds ranges from 28 mm to 32 mm. The saddle-shaped surface includes a middle section intercept line facing away from the intake manifold and a transition line segment connecting the middle section intercept line and the intake manifold. The radius R7 of the middle section intercept line ranges from 4 mm to 6 mm, and the radius of the transition line segment ranges from 11 mm to 13 mm.

[0020] Such a setting is helpful to ensure the air intake volume and air intake uniformity.

[0021] In some embodiments, the cylinder head has a bell mouth, the intake fork is connected to the combustion chamber through the bell mouth, and the intake valve can separate the combustion chamber from the bell mouth; the cylinder head has a combustion chamber for constituting a combustion chamber, the combustion chamber includes a first side corresponding to the intake valve, a second side corresponding to the exhaust valve, and two guide flow surfaces connected between the first side and the second side, the portion of the first side connected to the mounting surface is an arc side concave in the cylinder head, the portion of the second side connected to the mounting surface is a beveled side inclined away from the exhaust valve, the radial width dimension W4 of the combustion chamber is in the range of 92 mm to 96 mm, the guide flow surface is convex toward the combustion chamber, and the radius of the guide flow surface is in the range of 95 mm to 100 mm.

[0022] Such an arrangement, by configuring the combustion chamber, helps to control the flow direction of the airflow, reduce resistance, and then help to achieve the best running trajectory of the gas.

[0023] In some embodiments, the piston has an end face facing the combustion chamber, the tumble concave surface is an inner spherical surface recessed in the end face, the depth h5 of the inner spherical surface relative to the end face ranges from 6 mm to 9 mm, and the radius R21 of the inner spherical surface ranges from 170 mm to 175 mm.

[0024] With such a configuration, the inner spherical surface helps the gas to form a rapid arc flow, which is beneficial to controlling the tumble ratio, accelerating the rapid mixing of methanol droplets and gas, and helping to increase the turbulence intensity.

[0025] In some embodiments, the maximum flow coefficient of the intake port is in a range of 0.4 to 0.5, and the maximum tumble ratio of the methanol engine is in a range of 3 to 3.3.

[0026] Such an arrangement, combined with the cyclic motion of the piston, helps to improve thermal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of a methanol engine according to one or more embodiments; Figure 2 is a schematic structural diagram of an intake passage and a combustion chamber of a cylinder head according to one or more embodiments; Figure 3 is a schematic structural diagram of an intake passage of a methanol engine according to one or more embodiments; Figure 4 is a schematic structural diagram of a cylinder head according to one or more embodiments; Figure 5 is a schematic design diagram of an air intake duct according to one or more embodiments; Figure 6Schematic cross-sectional view at the corresponding exhaust valve of a cylinder head assembly according to one or more embodiments; Figure 7 Schematic structural view of a cylinder head assembly according to one or more embodiments; Figure 8 Schematic cross-sectional view at the corresponding spark plug of a cylinder head assembly according to one or more embodiments; Figure 9 Schematic structural view of a piston according to one or more embodiments; Figure 10 Schematic structural view of a piston according to one or more embodiments; Figure 11 Schematic curve graph of the flow coefficient of the embodiment of the present application and the comparative example; Figure 12 Schematic curve graph of the tumble ratio of the embodiment of the present application and the comparative example.

[0028] Explanation of reference numerals: 1, cylinder block; 11, cylinder block main body; 12, cylinder liner; 101, cylinder bore; 2, cylinder head; 2001, mounting surface; 2002, air flow guiding section; 2003, first arc section; 2004, second arc section; 2005, first guiding section; 2006, second guiding section; 2007, middle section intercept line; 2008, transition line segment; 21, intake passage; 211, outer intake passage; 2111, saddle-shaped surface; 212, intake fork passage; 2120, intake fork port; 2121, first streamline; 2122, second streamline; 22, exhaust passage; 221, exhaust fork passage; 23, bell mouth; 24, combustion chamber; 241, first side; 242, second side; 243, guiding flow surface; 3, piston; 301, end face; 302, tumble concave surface; 303, ring surface; 4, intake valve; 5, exhaust valve; 501, exhaust valve bottom surface; 1000, methanol engine; 1001, combustion chamber; 1100, cylinder block assembly; 1200, cylinder head assembly; 1210, spark plug; 1220, spacer sleeve; 1230, intake seat ring; 1240, exhaust seat ring; 1250, intake duct; 1260, exhaust duct; 1300, pin; 1400, cylinder head gasket. Detailed implementation manners

[0029] To make the above objects, features, and advantages of the present application more apparent and understandable, the following provides a detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0030] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "perpendicular", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present application.

[0031] In the present application, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over", and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "below", "beneath", and "underneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0032] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. Exemplarily, the first intake valve may also be referred to as the second intake valve, and the second intake valve may also be referred to as the first intake valve. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0033] In this application, unless otherwise clearly specified or limited, terms such as "connected" and "coupled" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a flexible connection or a rigid connection in at least one direction; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, or there may be an intermediate medium while being directly connected, and it may also be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. Terms such as "installed", "set", and "fixed" can be understood in a broad sense as connection. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] Reference Figure 1 , Figure 1 shows a methanol engine in an embodiment of the present application. In an exemplary embodiment, the methanol engine 1000 includes a cylinder head assembly 1200 and a cylinder block assembly 1100. For convenience of description, a spatial rectangular coordinate system XYZ can be established. The X-axis direction can be the front-rear direction, the Y-axis direction can be the left-right direction, and the Z-axis direction can be the up-down direction. The cylinder head assembly 1200 can be disposed above the cylinder block assembly 1100. The cylinder head assembly 1200 and the cylinder block assembly 1100 are used to form a combustion chamber 1001.

[0035] In an exemplary embodiment, the methanol engine 1000 includes a cylinder block 1, a piston 3, a cylinder head 2, an intake valve 4, and an exhaust valve 5. The piston 3 is disposed in the cylinder block 1 and can all be used to constitute the cylinder block assembly 1100; the intake valve 4 and the exhaust valve 5 are both disposed in the cylinder head 2 and can all be used to constitute the cylinder head assembly 1200.

[0036] The cylinder head 2 is disposed on the cylinder block 1, and the cylinder head 2 and the cylinder block 1 are used to form a combustion chamber 1001. Specifically, the cylinder head 2 may have a combustion chamber 24, and the cylinder block 1 may have a cylinder bore 101. Exemplarily, the methanol engine 1000 may further include a cylinder head gasket 1400. The cylinder head gasket 1400 is disposed between the cylinder block 1 and the cylinder head 2, and the inner hole of the cylinder head gasket 1400 can also be used to constitute the combustion chamber 1001.

[0037] The cylinder head 2 has an intake passage 21 and an exhaust passage 22 communicating with the combustion chamber 1001. Reference Figure 2 shows a schematic structural diagram of the intake passage 21 and the combustion chamber 24. The flow coefficient of the intake passage 21 is configured to be greater than or equal to 0.3. This flow coefficient can be an average flow coefficient. Exemplarily, it can be 0.35 or 0.4. A high intake air volume can increase the total heat of methanol combustion and improve the power output of the methanol engine 1000. A high intake air volume is a simple, direct, and effective way to improve the thermal efficiency of the methanol engine, especially suitable for heavy-duty engines with low speed and high torque.

[0038] The intake valve 4 is provided on the cylinder head 2. Figure 1 When the intake valve 4 is opened, the intake passage 21 is communicated with the combustion chamber 1001. The intake valve 4 is used to separably open and close the intake passage 21 and the combustion chamber 1001.

[0039] The exhaust valve 5 is provided on the cylinder head 2. Figure 1 When the exhaust valve 5 is closed, the exhaust passage 22 is hermetically separated from the combustion chamber 1001. The exhaust valve 5 is used to separably open and close the exhaust passage 22 and the combustion chamber 1001. The exhaust valve 5 and the intake valve 4 can be controlled according to, for example, the requirements of the four-stroke operation.

[0040] Reference Figure 1 , when the intake valve 4 is opened, the methanol mixture introduced into the intake passage 21 enters the combustion chamber 24, and then can flow to the exhaust valve 5. The exhaust valve 5 is used to reflect the intake air flow in the intake passage 21 to the concave surface at the top of the piston 3. Reference Figure 9 , one end of the piston 3 facing the combustion chamber 1001 and also facing the cylinder head assembly 1200 has a tumble concave surface 302. The structural layout of the components of the methanol engine 1000 enables the tumble ratio of the methanol engine 1000 to be greater than or equal to 2.4. By configuring the flow coefficient of the intake passage 21 and by configuring the structural design layout of the parts for defining the combustion chamber 1001, the methanol mixture can quickly enter the combustion chamber 1001 through the intake passage 21 at low engine speeds. The air flow blows to the exhaust valve 5 and is then reflected to the piston 3 to achieve a tumble state substantially perpendicular to the Z-axis direction, which can accelerate the rapid mixing of methanol droplets and gas, thereby forming a uniform methanol mixture gas with a high turbulence intensity.

[0041] The cylinder block 1 may include a cylinder block main body 11 and a cylinder liner 12 fixed to the cylinder block main body 11. The cylinder liner 12 is wear-resistant, temperature-resistant, and pressure-resistant. The piston 3 is slidably connected to the cylinder liner 12 along the Z-axis direction. The methanol engine 1000 may further include a pin 1300 and a transmission mechanism (not shown). The pin 1300 is arranged along the X-axis direction, and the piston 3 is rotatably connected to the pin 1300 to output power to the transmission mechanism.

[0042] The piston 3 is arranged in the cylinder block 1. The piston 3 can slide along the Z-axis direction to change the volume of the combustion chamber 1001, for example Figure 1The position of the middle piston 3 is relatively high, and the volume of the combustion chamber 1001 is relatively small. By configuring the structure of the combustion chamber 1001 and the stroke of the piston 3, the compression ratio of the methanol engine 1000 can be achieved in the range of 13 to 16, such as 14 or 15. The relatively large compression ratio of the methanol engine 1000 is conducive to the full combustion of methanol under high temperature and high pressure conditions. Methanol can undergo chemical reactions more thoroughly, releasing more energy. It also improves the ratio of the methanol engine 1000 to convert chemical energy into mechanical energy, enhancing the thermal efficiency. In addition, the flame propagation speed in the methanol engine 1000 is higher. In an environment with a high compression ratio, the mixture in the combustion chamber 1001 is in a high temperature and high pressure state, which is conducive to the propagation of the flame. And the flame can propagate through the mixture at a faster speed, making the combustion process more stable and rapid, reducing fluctuations and abnormal conditions during the combustion process, such as reducing the occurrence probability of knocking, etc., and ensuring the stable operation of the methanol engine 1000. By improving the thermal efficiency, the fuel economy of the methanol engine 1000 is enhanced, and the user's usage cost is reduced.

[0043] When the methanol engine 1000 is working, the intake valve 4 is opened, the exhaust valve 5 is closed, and the piston 3 moves from the top dead center to the bottom dead center. The volume of the combustion chamber 1001 above the piston 3 increases, generating a vacuum, and the pressure in the combustion chamber 1001 drops below the intake pressure. Under the action of the vacuum suction, the methanol-air mixture enters from the intake passage 21.

[0044] Combined with Figure 2 As shown, the intake passage 21 may include an outer intake passage 211 and two intake branch passages 212 respectively communicating between the outer intake passage 211 and the combustion chamber 24 of the combustion chamber 1001.

[0045] Refer to Figure 2 and Figure 3 As shown, the outer intake passage 211 can project and cover the two intake branch passages 212, and the cross-sectional area of the outer intake passage 211 is larger. The intake branch passages 212 can extend along the YZ plane, and the two intake branch passages 212 can be arranged along the X-axis direction.

[0046] The shape of the outer port of the outer intake passage 211 can be approximately a rounded rectangle, and the range of the width W1 of the outer port along the X-axis direction can be between 95 mm and 100 mm; Figure 3 As shown, the size ranges of the four rounded corners can meet: 9 mm ≤ R1 ≤ 11 mm, 9 mm ≤ R2 ≤ 11 mm, 7 mm ≤ R3 ≤ 9 mm, 7 mm ≤ R4 ≤ 9 mm. The shape of the outer port of the outer intake passage 211 can be approximately a pillow shape, and the range of the opening size h2 of the middle position along the YZ plane can be between 38 mm and 53 mm.

[0047] Refer to Figure 4 And combined with Figure 2As shown, the external intake passage 211 has a saddle-shaped surface 2111 at the bifurcation of the two intake fork passages 212. The two ends of the saddle-shaped surface 2111 protrude outward in the Z-axis direction, and the middle part is recessed inward; as Figure 4 shown, the two ends of the saddle-shaped surface extend inward in the X-axis direction, and the middle part protrudes outward.

[0048] Figure 4 The cross-section shown can be roughly along the extension direction of the intake fork passage 212 and can be parallel to the X-axis direction. This cross-section can be called a longitudinal section. The saddle-shaped surface 2111 can include a middle section line 2007 facing away from the intake fork passage 212 and transition line segments 2008 connecting the middle section line 2007 and the intake fork passage 212, specifically including a first transition line segment and a second transition line segment. The radius R7 of the middle section line 2007 ranges from 4 mm to 6 mm. The radius of the transition line segment ranges from 11 mm to 13 mm. For example, the radius R5 of the first transition line segment and the radius R6 of the second transition line segment can each range from 11 mm to 13 mm. Each arc segment of the saddle-shaped surface 2111 can be a circular arc, which can reduce the flow resistance of the mixed gas and achieve uniform distribution of the two intake fork passages 212.

[0049] The saddle-shaped surface 2111 can have a symmetric shape, and the two intake fork passages 212 can also be symmetrically arranged. Exemplarily, the distance W2 between the two intake fork passages 212 ranges from 28 mm to 32 mm. The two opposite sides of the two intake fork passages 212 can be basically smoothly connected to the two sides of the external intake passage 211.

[0050] The methanol engine 1000 can include two intake valves 4, which are arranged in the two intake fork passages 212 in a one-to-one correspondence. The methanol engine 1000 can also include two intake ducts 1250. The intake valves 4 can be slidably arranged on the cylinder head 2 through the intake ducts 1250.

[0051] Refer to Figure 5 and in combination with Figure 2 shown, the intake valve 4 can have an axis Q. The cylinder head 2 has a mounting surface 2001 for mounting to the cylinder block 1, and this mounting surface 2001 can be parallel to the XY plane. In combination with Figure 1 shown, based on the axial section defined by the axis Q of the intake valve 4 and the modified radial direction parallel to the Y-axis of the piston 3, that is, the axial section parallel to the YZ plane, the opening dimension h1 of the outer port of the external intake passage 211 ranges from 53 mm to 58 mm, and the external intake passage 211 can ensure the intake air volume; with the structural design of the saddle-shaped surface 2111, it is beneficial to ensure the intake air uniformity.

[0052] Refer to Figure 2, the intake manifold 212 has an intake manifold opening 2120, a first streamline 2121 and a second streamline 2122. The first streamline 2121 is located between the second streamline 2122 and the mounting surface 2001. The first streamline 2121 includes an air flow guiding section 2002 extending to the intake manifold opening 2120 and a first arc section 2003 extending from the air flow guiding section 2002; the second streamline 2122 includes a second arc section 2004 extending to the intake manifold opening 2120. Combining Figure 5 As shown, the radius R10 of the first arc section 2003 ranges from 13 mm to 18 mm, the length L5 of the air flow guiding section 2002 ranges from 3 mm to 6 mm, the radius R11 of the second arc section 2004 ranges from 47 mm to 52 mm, and the opening size W3 of the intake manifold opening 2120 ranges from 29 mm to 33 mm; along the axial direction of the piston 3, the distance h4 between the intake manifold opening 2120 and the mounting surface 2001 ranges from 15 mm to 19 mm. Both the first arc section 2003 and the second arc section 2004 can be concave arcs and can be circular arcs. The air flow guiding section 2002 can be a straight section, and the intake manifold 212 forms a necking structure at the inner end portion, which helps to determine the flow direction, velocity, flow coefficient and tumble ratio of the mixed gas.

[0053] Based on the axial section, the first streamline 2121 further includes a first guiding section 2005, which can extend from the first arc section 2003 to the outer intake passage 211. The second streamline 2122 further includes a second guiding section 2006. An intake valve 4 can be passed between the second guiding section 2006 and the second arc section 2004, and the second guiding section 2006 can extend to the outer intake passage 211. The two air flows of the two intake manifolds 212 can quickly enter the combustion chamber 1001.

[0054] The length L4 of the first guiding section 2005 ranges from 43 mm to 47 mm, and the angle α4 between the first guiding section 2005 and the axis Q of the intake valve 4 ranges from 42° to 46°. The length L3 of the second guiding section 2006 ranges from 33 mm to 36 mm, and the angle α2 between the second guiding section 2006 and the axis Q of the intake valve 4 ranges from 38° to 42°. The opening size h3 of the outer port of the intake manifold 212 ranges from 37 mm to 41 mm. The structural setting of the intake manifold 212 helps to determine the flow rate of the mixed gas, that is, the magnitude of the flow coefficient.

[0055] Based on the axial section, the inner wall of the outer air intake passage 211 can be smoothly connected to the first streamline 2121. The range of the fillet radius R9 at the circular arc connection can be from 72 mm to 77 mm, and the range of the length L1 of the first straight line segment of the outer air intake passage 211 extending from the outer port to this circular arc connection can be from 45 mm to 50 mm. The outer air intake passage 211 can also be smoothly connected to the second streamline 2122. The range of the fillet radius R8 at this circular arc connection can be from 45 mm to 50 mm, and the range of the length L2 of the second straight line segment of the outer air intake passage 211 extending from the outer port to this circular arc connection can be from 42 mm to 47 mm. The included angle α1 between the upper and lower straight line segments of the outer air intake passage 211 can be in the range of 17° to 21°. The outer air intake passage 211 is relatively well - matched with the two air intake forks 212 and can effectively convey air.

[0056] Combined Figure 6 As shown, in the embodiment corresponding to the two air intake forks 212, the exhaust passage 22 can include two exhaust forks 221, and the two exhaust forks 221 can converge into the outer exhaust passage. The exhaust forks 221 and the air intake forks 212 are arranged radially opposite to each other along the direction parallel to the Y - axis of the piston 3. Subsequently, the methanol engine 1000 includes two intake valves 4 corresponding to the two air intake forks 212 one by one and two exhaust valves 5 corresponding to the two exhaust forks 221 one by one.

[0057] The methanol engine 1000 can also include an intake seat ring 1230 and an exhaust seat ring 1240, which are respectively arranged at the positions of the corresponding air intake forks 212 and exhaust forks 221 of the cylinder head 2 for sealing cooperation with the intake valve 4 and the exhaust valve 5. The methanol engine 1000 can also include an exhaust duct 1260 arranged on the cylinder head 2. The exhaust valve 5 can be slidably arranged in the exhaust duct 1260 and thus can also have an axis. The axis Q of the intake valve 4 and the axis of the exhaust valve 5 are inclined away from each other in the YZ plane. Exemplarily, the first inclination angle α3 of the axis Q of the intake valve 4 relative to the Y - axis direction is less than the second inclination angle α7 of the axis of the exhaust valve 5 relative to the Y - axis direction, which helps to configure the structure of the combustion chamber 1001, helps to configure the structure of the combustion cavity 24, and affects the structure of the air intake passage 21. The air flow can flow out of the air intake passage 21 better and be reflected by the exhaust valve 5 towards the piston 3.

[0058] Exemplarily, the range of the first inclination angle α3 is from 63° to 67°, and the range of the second inclination angle α7 is from 68° to 72°. Such a setting also helps to ensure the compression ratio and the volume of the combustion cavity 24 will not be too large.

[0059] The first inclination angle α3 can be 65°, and the second inclination angle α7 can be 70°. The air flow guiding section 2002 can be parallel to the installation surface 2001, which helps to restrict the flow direction of the air flow; the radius R10 of the first arc section 2003 is 15 mm, the length L5 of the air flow guiding section 2002 is 4 mm, the radius R11 of the second arc section 2004 is 50 mm, the opening size W3 of the air intake fork 2120 is 31 mm; the distance h4 between the air intake fork 2120 and the installation surface 2001 is 17 mm. The structure of the methanol engine 1000 is optimized.

[0060] As Figure 2 shown, the cylinder head 2 can have a flared opening 23. The air intake fork 212 communicates with the combustion chamber 1001 through the flared opening 23, and the intake valve 4 can separate the combustion chamber 1001 from the flared opening 23. Referring Figure 5 to, the range of the flare angle α5 of the flared opening 23 can be between 88° and 92°, which is beneficial to ensure the smooth and rapid outflow of the air flow at the air intake fork 2120.

[0061] Referring Figure 6 to, Figure 7 and Figure 2 referring to, the cylinder head 2 has a combustion chamber 24 for forming the combustion chamber 1001. The combustion chamber 24 includes a first side 241 corresponding to the intake valve 4, a second side 242 corresponding to the exhaust valve 5, and two guiding flow surfaces 243 connected between the first side 241 and the second side 242. Exemplarily, the part of the first side 241 connecting to the installation surface 2001 is a circular arc side concave into the cylinder head 2, and the range of the fillet R13 of this circular arc side in the axial section is between 4 mm and 6 mm. The part of the second side 242 connecting to the installation surface 2001 is an inclined hypotenuse inclined away from the exhaust valve 5, and the range of the inclination angle α6 of this hypotenuse is between 33° and 37°.

[0062] Referring Figure 7 to, the width dimension W4 of the combustion chamber 24 in the Y-axis direction ranges from 92 mm to 96 mm, the guiding flow surfaces 243 protrude into the combustion chamber 24, and the ranges of the radii R16 and R17 of the two guiding flow surfaces 243 can each be between 95 mm and 100 mm. By providing the two guiding flow surfaces 243, it helps to control the flow direction of the air flow, reduce the resistance, and then is beneficial to achieve the optimal operation trajectory of the gas.

[0063] The sides of the combustion chamber 24 can be transitioned by circular arcs. Exemplarily, Figure 7 as shown, the fillets of the four circular arcs satisfy: 21 mm ≤ R14 ≤ 24 mm, 21 mm ≤ R15 ≤ 24 mm, 16 mm ≤ R18 ≤ 19 mm, 16 mm ≤ R19 ≤ 19 mm. The two fillets at the exhaust valve 5 are smaller than the two fillets at the intake valve 4.

[0064] Referring Figure 7 to andFigure 6 The combustion chamber 24 may further include a dome between the intake valve 4 and the exhaust valve 5. In the axial section, the range of the radian R12 of the dome may be between 9 mm and 13 mm.

[0065] In the air flow discharged from the intake valve 4, a part of it is controlled to flow towards the bottom surface 501 of the exhaust valve 5 of the exhaust valve, and another part can flow downward towards the piston 3. The air flow flowing towards the exhaust valve 5 is reflected by the bottom surface 501 of the exhaust valve towards the piston 3. The high-speed mixed gas forms a tumbling gas in the combustion chamber 1001, which can accelerate the uniform mixing of air and methanol. The bottom surface 501 of the exhaust valve may be perpendicular to the axis of the exhaust valve 5.

[0066] Reference Figure 8 The methanol engine 1000 may further include a spark plug 1210 and a spacer 1220. The spark plug 1210 may be arranged on the cylinder head 2 through the spacer 1220. The spark plug 1210 may be located at the top center position of the combustion chamber 24. The spark plug 1210 is used for ignition, and the flame can spread rapidly in the combustion chamber 1001.

[0067] Reference Figure 9 and Figure 10 The piston 3 may have an end face 301 facing the combustion chamber 1001. The tumbling concave surface is an inner spherical surface recessed in the end face 301. The range of the depth h5 of the tumbling concave surface 302 relative to the end face 301 is between 6 mm and 9 mm. The range of the radius R21 of the inner spherical surface is between 170 mm and 175 mm. The inner spherical surface helps the gas to form a rapid circular flow, is beneficial to controlling the tumble ratio, can accelerate the rapid mixing of methanol droplets and gas, and is beneficial to enhancing the turbulence intensity.

[0068] In some other embodiments, the tumbling concave surface 302 of the piston 3 is an arc surface parallel to the X-axis direction. And the inner spherical surface can achieve a higher compression ratio.

[0069] The piston 3 may further have an annular surface 303 connecting the end face 301 and the tumbling concave surface 302. In the axial section, the cross-section line of the annular surface 303 may be a convex arc, and the range of the radius R20 of the convex arc may be between 18 mm and 22 mm. The range of the inner diameter D1 of the end face 301 of the piston 3 may be between 104 mm and 108 mm, and the range of the outer diameter D2 of the tumbling concave surface 302 may be between 93 mm and 98 mm.

[0070] When the piston 3 is in different motion processes, the state of the air flow may change. The range of the maximum flow coefficient of the intake passage 21 may be between 0.4 and 0.5, and the range of the maximum tumble ratio of the methanol engine 1000 may be between 3 and 3.3. Cooperating with the cyclic motion of the piston 3 helps to improve the thermal efficiency.

[0071] Reference Figure 11 and Figure 12, in a comparative example, methanol is burned using a traditional diesel engine, which has a swirl intake port and adopts a flat-top combustion chamber design with a relatively large swirl.

[0072] In the embodiments of the present application, to solve the problems that the volatility of methanol is much higher than that of diesel, which is prone to premature evaporation in the intake port, resulting in an overly lean or unevenly distributed air-fuel mixture, incomplete combustion, and low combustion efficiency, a comprehensive innovative optimization design is carried out on the combustion system, cylinder head combustion chamber structure, and intake and exhaust ports, improving the tumble ratio, flow coefficient, enhancing the in-cylinder flow turbulence intensity, promoting the rapid and uniform mixing of methanol and air, achieving full combustion, and improving combustion efficiency; optimizing the compression ratio according to the characteristics of methanol to avoid knocking; through bench thermodynamic development, the thermal efficiency is greatly improved.

[0073] Exemplarily, the methanol engine 1000 includes a cylinder block 1, a piston 3, a cylinder head 2, an intake valve 4, and an exhaust valve 5. The methanol engine 1000 satisfies: h1 = 55 mm; h2 = 40.5 mm; h3 = 39 mm; h4 = 17 mm; h5 = 7.5 mm; W1 = 98 mm; W2 = 30 mm; W3 = 31 mm; W4 = 94 mm; L1 = 48 mm; L2 = 44 mm; L3 = 34.5 mm; L4 = 45 mm; L5 = 4 mm; α1 = 19°; α2 = 40; α3 = 65°; α4 = 44°; α5 = 90°; α6 = 35°; α7 = 70°; R1 = 10 mm; R2 = 10 mm; R3 = 8 mm; R4 = 8 mm; R5 = 12 mm; R6 = 12 mm; R7 = 5 mm; R8 = 48 mm; R9 = 74 mm; R10 = 15 mm; R11 = 50 mm; R12 = 11 mm; R13 = 5 mm; R14 = 22.5 mm; R15 = 22.5 mm; R16 = 97.5 mm; R17 = 97.5 mm; R18 = 17.5 mm; R19 = 17.5 mm; R20 = 20 mm; R21 = 172 mm; D1 = 106 mm; D2 = 95 mm.

[0074] The compression ratio of the methanol engine 1000 in this embodiment can be controlled to 14.5. The methanol engine 1000 has a relatively high average flow coefficient, greater than 0.35, a maximum flow coefficient close to 0.5, and a minimum flow coefficient of 0.2; the average tumble ratio is greater than 2.4, the maximum tumble ratio is close to 3.3, and the minimum tumble ratio is also greater than 1. The performance of the methanol engine 1000 is superior to that of the comparative example, and the lean combustion thermal efficiency reaches 50.2%.

[0075] The technical features of the above-disclosed embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0076] The embodiments disclosed above merely represent several implementation manners of the present application. Their descriptions are relatively specific and detailed, but they should not be construed as limitations on the patent protection scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the patent protection scope required by the present application. Therefore, the patent protection scope of the present application shall be subject to the appended claims.

Claims

1. Methanol engine, characterized in that: It comprises a cylinder block assembly and a cylinder head assembly, wherein the cylinder block assembly and the cylinder head assembly are used to form a combustion chamber, and the compression ratio of the combustion chamber is in the range of 13 to 16; The cylinder assembly includes a piston having a tumble concave surface facing the cylinder head assembly; The cylinder head assembly includes a cylinder head and two exhaust valves. The cylinder head has an intake duct with a flow coefficient greater than or equal to 0.

3. The intake duct includes an external intake duct and two intake fork ducts respectively connected between the external intake duct and the combustion chamber. The exhaust valve is used to reflect the intake air flow of the corresponding intake fork duct to the tumble concave surface, so that the tumble ratio of the methanol engine is greater than or equal to 2.

4.

2. The methanol engine according to claim 1, characterized in that: The outer air intake passage has a saddle-shaped surface at the bifurcation of the two air intake forks; The cylinder head also has two exhaust fork channels, and the exhaust fork channels and the intake fork channels are arranged opposite to each other along the radial direction of the piston; Wherein, the cylinder head assembly also includes two intake valves corresponding to the two intake forks.

3. The methanol engine according to claim 2, characterized in that: The first inclination angle of the axis of the intake valve relative to the radial direction is smaller than the second inclination angle of the axis of the exhaust valve relative to the radial direction. The first inclination angle α3 ranges from 63° to 67°, and the second inclination angle α7 ranges from 68° to 72°.

4. The methanol engine according to claim 3, characterized in that: The cylinder head has a mounting surface for mounting to the cylinder body; Based on the axis of the intake valve and the radially defined axial section of the piston, the intake fork has an intake fork opening, a first streamline and a second streamline, the first streamline is located between the second streamline and the mounting surface, the first streamline includes an airflow guide section extending to the intake fork opening and a first arc section extending from the airflow guide section, the second streamline includes a second arc section extending to the intake fork opening, The radius R10 of the first arc segment is in the range of 13 mm to 18 mm, the length L5 of the airflow guide segment is in the range of 3 mm to 6 mm, the radius R11 of the second arc segment is in the range of 47 mm to 52 mm, and the opening size W3 of the intake fork opening is in the range of 29 mm to 33 mm; Along the axial direction of the piston, the distance h4 between the intake fork opening and the mounting surface ranges from 15 mm to 19 mm.

5. The methanol engine according to claim 4, characterized in that: The first inclination angle α3 is 65°, the second inclination angle α7 is 70°; the airflow guide section is parallel to the mounting surface; the radius R10 of the first arc section is 15 mm, the length L5 of the airflow guide section is 4 mm, the radius R11 of the second arc section is 50 mm, and the opening size W3 of the air intake fork opening is 31 mm; the distance h4 between the air intake fork opening and the mounting surface is 17 mm.

6. The methanol engine according to claim 4, characterized in that: Based on the axial section, the first streamline also includes a first guide segment extending to the external air intake duct, and the second streamline also includes a second guide segment extending to the external air intake duct; the length L3 of the first guide segment ranges from 33mm to 36mm, the angle α4 between the first guide segment and the axis of the intake valve ranges from 42° to 46°, the length L4 of the second guide segment ranges from 43mm to 47mm, the angle α2 between the second guide segment and the axis of the intake valve ranges from 38° to 42°; the opening size h3 of the external port of the intake fork duct ranges from 37mm to 41mm.

7. The methanol engine according to claim 4, characterized in that: Based on the axial section, the opening size h1 of the outer port of the outer air inlet duct ranges from 53 mm to 58 mm; Based on the longitudinal section perpendicular to the axial section, the distance W2 between the two intake forks ranges from 28mm to 32mm, the saddle-shaped surface includes a middle section facing away from the intake fork and a transition line segment connected between the middle section and the intake fork, the radius R7 of the middle section ranges from 4mm to 6mm, and the radius of the transition line segment ranges from 11mm to 13mm.

8. The methanol engine according to claim 4, characterized in that: The cylinder head has a bell mouth, the intake fork passage is connected to the combustion chamber through the bell mouth, and the intake valve can separate the combustion chamber and the bell mouth; The cylinder head has a combustion chamber for constituting the combustion chamber, the combustion chamber includes a first side corresponding to the intake valve, a second side corresponding to the exhaust valve, and two guide flow surfaces connected between the first side and the second side, the portion of the first side connected to the mounting surface is a circular arc side concave in the cylinder head, the portion of the second side connected to the mounting surface is a beveled side inclined away from the exhaust valve, the width dimension W4 of the combustion chamber along the radial direction ranges from 92 mm to 96 mm, the guide flow surface is convex toward the combustion chamber, and the radius of the guide flow surface ranges from 95 mm to 100 mm.

9. The methanol engine according to claim 1, characterized in that: The piston has an end face facing the combustion chamber, the tumble concave surface is an inner spherical surface recessed in the end face, a depth h5 of the inner spherical surface relative to the end face ranges from 6 mm to 9 mm, and a radius R21 of the inner spherical surface ranges from 170 mm to 175 mm.

10. The methanol engine according to any one of claims 1 to 9, characterized in that: The maximum flow coefficient of the intake duct ranges from 0.4 to 0.5, and the maximum tumble ratio of the methanol engine ranges from 3 to 3.3.

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