Horizontal double-cylinder engine of motorcycle

Abstract

The horizontal type double-cylinder engine comprises an engine body, two air cylinders, two pistons, a crank connecting rod mechanism and an air distribution mechanism, each air cylinder is provided with a plurality of sets of air inlet mechanisms and air outlet mechanisms in a matched mode, and the air distribution mechanism comprises an air inlet cam shaft, an air outlet cam shaft, an air inlet timing chain wheel and an air outlet timing chain wheel; the crank connecting rod mechanism comprises a left crank, a right crank and a crank pin, two piston connecting rods are arranged in the middle of the crank pin in a sleeved mode, a timing driving chain wheel is connected to the left crank in a sleeved mode, and the timing driving chain wheel, the air inlet timing chain wheel and the exhaust timing chain wheel are located on the same side and connected through a timing chain. A CVT driving belt wheel is connected to the right crank in a sleeved mode, the CVT driving belt wheel is in transmission connection with a CVT driven belt wheel on one side of the CVT driving belt wheel through a belt, the CVT driven belt wheel is fixedly connected to a main transmission shaft in a sleeved mode, an input gear is connected to the main transmission shaft in a sleeved mode, and an output gear in transmission connection with the input gear is arranged on one side of the input gear.

Description

Technical Field

[0001] The utility model relates to the field of motorcycle engines, in particular to a horizontal twin-cylinder motorcycle engine. Background Art

[0002] A motorcycle engine is one of its core components, responsible for providing the power to keep the vehicle running. Currently, motorcycle engines are primarily categorized as single-cylinder and multi-cylinder. Multi-cylinder engines, compared to single-cylinder engines, are more complex in structure, offer greater power output, and deliver smoother power. Multi-cylinder engines include, but are not limited to, two-cylinder, three-cylinder, and four-cylinder engines. These engines increase power output and smoothness by increasing the number of cylinders. Common multi-cylinder engine arrangements include parallel (inline), V-type, horizontally opposed, and W-type. Parallel engines, such as inline-twin or inline-four (I4), have their cylinders arranged vertically on a single plane.

[0003] Existing in-line twin-cylinder engines are mostly vertical, occupying a large space in the vertical direction and having a relatively complex overall structure. Simultaneously, existing twin-cylinder engines have a sprocket placed in the middle, which results in large vibrations during operation. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a horizontal twin-cylinder motorcycle engine to solve the problems of the existing motorcycle twin-cylinder engines having a complex structure and large vibration during operation.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A motorcycle horizontal twin-cylinder engine comprises an engine body, two cylinders, two pistons, a fuel injection device, an ignition device, a crank-connecting rod mechanism and a valve mechanism, wherein each cylinder is equipped with a plurality of intake mechanisms and exhaust mechanisms, wherein the valve mechanism comprises an intake camshaft and an exhaust camshaft, and an intake timing sprocket and an exhaust timing sprocket are respectively sleeved on the end positions on the same side of the intake camshaft and the exhaust camshaft; the crank-connecting rod mechanism comprises a left crank, a right crank and a crank pin installed between the left crank and the right crank, two piston connecting rods are sleeved on the middle part of the sleeve crank pin, a timing driving sprocket is sleeved on the left crank, and the timing driving sprocket is sleeved on the intake timing sprocket and the exhaust timing sprocket. The exhaust timing sprockets are located on the same side and are connected by a timing chain. The right crank is sequentially sleeved with a balance shaft driving gear and a CVT driving pulley from the inside to the outside. A CVT driven pulley is provided on one side of the CVT driving pulley. The CVT driving pulley and the CVT driven pulley are connected by a belt drive. The CVT driven pulley is sleeved and fixed on a main drive shaft. An input gear is sleeved and fixed on the main drive shaft. An output gear is provided on the side of the input gear and is transmission-connected to the input gear. A balance shaft is provided on one side of the right crank, parallel to it. The balance shaft is sleeved with a balance shaft driven gear that meshes with the balance shaft driving gear. In this way, the valve train, intake mechanism, and exhaust mechanism are all located at the front end of the engine, and the crank-connecting rod structure is located at the rear end of the engine body. The transmission mechanism is distributed horizontally as a whole, forming a horizontal two-cylinder engine. Compared with a vertical two-cylinder engine, this arrangement has a smaller longitudinal assembly height. At the same time, the right crank is used to drive the CVT driving pulley to rotate, making the overall layout compact. The intake timing sprocket and exhaust timing sprocket are located at the end positions of the intake camshaft and exhaust camshaft respectively, which changes the installation position of the traditional two-cylinder engine timing driven sprocket. The end position is close to the assembly end of the shaft, which is relatively less vibrating. When the crank-connecting rod mechanism rotates after the piston is ignited, it drives the CVT driving pulley, CVT driven pulley and main drive shaft mounted thereon, and finally outputs the power to the output gear through the input gear to achieve power output. When the right crank rotates, the balance shaft driving gear will drive the meshing balance shaft driven gear to rotate, which in turn causes the balance shaft to rotate. After the balance shaft rotates, it can reduce the vibration of the engine.

[0007] Furthermore, the engine body includes a cylinder head cover, a cylinder head, a cylinder block, a crankcase, a left cover, a right cover, and a CVT cover. The cylinder head cover, cylinder head, and cylinder block are connected in a front-to-back manner. The crankcase includes a left crankcase and a right crankcase. The outer side of the left crankcase is sealed to the left cover, and the right crankcase is sealed to the right cover. The CVT cover is connected to the outer side of the right cover and together they form the CVT case. Multiple cooling fins are provided on the outer end surfaces of the cylinder head cover, cylinder head, and cylinder block. This separates the crankcase and CVT case in the engine body. The CVT case generates more heat than the crankcase. Separating the two prevents hot air from the CVT case from flowing into the crankcase, which could affect the service life of the transmission components within the crankcase. The cylinder head cover, cylinder head, and cylinder block are connected to the combustion chamber. The circumferential arrangement of multiple cooling fins on the outer end surfaces of these components allows heat generated by these components to be removed through air cooling.

[0008] Furthermore, an air inlet and outlet duct connected to the CVT case are provided on the upper side of the right cover. The inlet duct is located near the CVT driving pulley, and the outlet duct is located near the CVT driven pulley. An air inlet chamber connected to the inlet duct is provided on the CVT cover, and an air outlet is provided on the side of the air inlet chamber facing the right cover, corresponding to the blades of the CVT driving pulley. This arrangement simplifies mold making and effectively reduces mold making costs. The upward-facing exhaust duct prevents stones from being thrown into the CVT case. After the motorcycle engine starts, the CVT driving pulley rotates, causing the blades on the driving pulley to rotate as well, creating negative pressure outside the chassis. This draws cold air from outside the chassis through the air inlet duct into the air inlet chamber, where it then flows through the exhaust port to the driving pulley, cooling the driving pulley. Simultaneously, the air, driven by the driving pulley blades, flows to the driven pulley, where it passes through the driven pulley and is then guided clockwise along its sidewall to the air outlet duct, where the hot air is discharged. Because the air outlet faces forward, when the hot air is discharged from the exhaust duct, the external cold air directly blows it in the opposite direction of riding, preventing it from flowing to the front, instantly removing the hot air flow. The inlet chamber, after drawing in the external cold air, creates a vortex within the inlet chamber, increasing the air flow rate.

[0009] Furthermore, a barrier rib is provided on the side of the right cover facing the CVT cover. The upper end of the barrier rib is connected to the upper wall of the right cover, and the lower end extends toward the axis of the CVT driven pulley. The barrier rib is arranged at an angle, and its inclination is aligned with the air outlet duct. This barrier rib can form a certain barrier to the air on the side of the driven pulley, preventing some of the hot air from being discharged from the air outlet duct from entering the driving pulley through the space above the driven pulley and affecting the efficiency of hot air discharge.

[0010] Furthermore, it also includes an oil lubrication system, which includes an oil collecting chamber located at the bottom of the crankcase body and a coarse filter, an oil pump, an external oil cooler, a fine filter and a main oil circuit connected in sequence, one end of the coarse filter is immersed in the lubricating oil in the oil collecting chamber, the oil pump is assembled in the crankcase body, and the oil cooler is placed on the motorcycle frame outside the crankcase body, and is provided with an oil inlet pipeline and an oil outlet pipeline; the fine filter and the coarse filter are both located on the lower end surface of the crankcase body, the coarse filter and the oil inlet pipe of the oil pump are connected through a first oil guide channel located in the crankcase body, the oil outlet of the first oil guide channel is connected to the oil inlet pipeline of the oil cooler, and the oil outlet pipeline of the oil cooler is connected to the fine filter through a second oil guide channel located on the crankcase body; the inner end of the fine filter is placed in the crankcase body, and the end is connected to the main oil channel in the crankcase body. In this way, based on the provision of heat sinks and air inlet and outlet ducts for air cooling, the oil lubrication system can achieve oil cooling for the crankshaft, crankcase, cylinder block, and cylinder head. The lubricating oil in the oil collection chamber will produce impurities after long-term circulation. Furthermore, after lubricating various components and returning to the oil collection chamber, the lubricating oil's temperature will rise, affecting subsequent lubrication and cooling. The high-temperature lubricating oil in the oil collection chamber undergoes preliminary filtration through a coarse filter before being pumped by an oil pump to an oil cooler outside the crankcase. After cooling in the oil cooler, it is directed from the oil cooler's oil outlet line to a second oil guide channel in the crankcase. Finally, it enters a fine filter for further fine filtering. Finally, the cooled and filtered lubricating oil is delivered through the main oil passage in the crankcase to various oil circuits, lubricating the various transmission components within the crankcase. The coarse and fine filters are mounted on the lower end surface of the crankcase, on the same side, making installation and removal convenient, eliminating the need to stand on either side for installation or removal. The oil cooler is arranged outside the crankcase body and on the motorcycle frame, does not occupy the space of the engine, and can effectively reduce the volume of the engine.

[0011] Furthermore, the coarse filter is installed at a lower height than the fine filter. The oil lubrication system also includes a main drive shaft lubrication oil passage, a crankshaft lubrication oil passage, a case oil outlet passage, two piston lubrication oil passages, and a cylinder block cooling oil passage and a cylinder head cooling oil passage, all connected to the main oil passage. Thus, placing the coarse filter in a lower installation position shortens the path between the oil collection chamber and the coarse filter. After cooling and fine filtering the lubricating oil, the cooled oil can be pumped through the main oil passage to the main drive shaft, crankshaft, crankcase, pistons, cylinder block, and cylinder head, providing cooling and lubrication for various high-temperature engine components.

[0012] Furthermore, the crankcase is formed by connecting a left crankcase and a right crankcase; two piston oil jets are provided in the crankcase, facing the back of the piston; a left lubricating oil passage and a right lubricating oil passage are provided on the interface between the left crankcase and the right crankcase and the cylinder body, respectively; one end of the right lubricating oil passage is connected to the oil outlet passage of the case; the two piston lubricating oil passages are provided in the left crankcase and the right crankcase, respectively, and are connected to the left and right lubricating oil passages on the corresponding sides; a matching oil passage for connecting the left and right lubricating oil passages is provided on the case interface of the cylinder body, and the left and right sides of the matching oil passage correspond to the left and right lubricating oil passages, respectively. In this way, when the oil pump pumps lubricating oil from the crankcase to the cylinder body, the lubricating oil passes through the case outlet passage of the crankcase, enters the right lubricating oil passage, the matching oil passage, and the left lubricating oil passage in sequence, and is then directed to the piston oil jets on the corresponding sides through the left and right lubricating oil passages. In the aforementioned oil circuit, a mating oil channel directs lubricating oil from the right lubricating oil channel to the left lubricating oil channel. This compact structure prevents leakage from the gap between the left and right crankcases after the oil channel passes through the joint. The piston oil nozzle is positioned facing the back of the piston, allowing the sprayed lubricating oil to reach the back of the piston directly. As the temperature at the back of the piston is the highest, this arrangement effectively ensures piston lubrication and cooling.

[0013] Furthermore, a first oil channel and a second oil channel are respectively provided along the axial direction of the left crank and crankpin. The first and second oil channels are connected by an oblique oil guide channel. The crankpin is also provided with oil injection holes corresponding to the two piston and connecting rods. The first oil channel, the oblique oil guide channel, and the second oil channel form the crankshaft lubrication oil channel. This oblique oil guide channel directs lubricating oil from the first channel into the second oil channel. One end of the oblique oil guide channel is located at the end of the left crank, and the other end is located on the crankpin. The left crank and crankpin are connected by an interference fit at the end of the left crank, allowing for synchronous rotation. During operation, the channels remain synchronized and connected. The oil injection holes correspond to the two piston and connecting rod end assembly points, respectively, providing lubrication and cooling for the piston and connecting rod end assembly points. The second oil channel provided in the crankpin not only cools and lubricates the piston and connecting rod end assembly points through the oil injection holes but also cools the crankpin, effectively ensuring a long crankpin life.

[0014] Furthermore, the intake mechanism and exhaust mechanism are installed in the cylinder head, and include valves, valve springs, valve spring upper seats and valve spring lower seats, the valve spring lower seats are fixedly connected to the engine body, the lower end of the valve spring is connected to the valve spring lower seat, the valve is arranged through the valve spring, and the upper end of the valve spring is clamped with the upper end of the valve by a locking clip; the intake camshaft and the exhaust camshaft are arranged at the front end of the intake mechanism and the exhaust mechanism, and four cams are provided on the intake camshaft and the exhaust camshaft, and the four cams are divided into two groups, and the two groups of cams form an angle of 180 degrees relative to the axis of the intake camshaft; a rocker arm shaft is provided between the intake camshaft and the intake mechanism and between the exhaust camshaft and the exhaust mechanism, and four rocker arms are provided on each rocker arm shaft, each rocker arm is in contact with the corresponding valve top, and the four cams on the intake camshaft and the exhaust camshaft correspond to the rocker arms one by one, and when the intake camshaft and the exhaust camshaft rotate, one group of cams is pressed against the corresponding rocker arm, squeezing the intake mechanism or the exhaust mechanism to realize intake or exhaust. In this way, the intake mechanism and the exhaust mechanism realize intake and exhaust by pressing down the top of the valve through the rocker arm on the rocker arm shaft, and the overall structure is compact.

[0015] Furthermore, the intake and exhaust camshafts are provided with camshaft cooling oil passages along their axial direction, connecting to the cylinder head cooling oil passages. The intake and exhaust camshafts are also provided with multiple radial oil injection holes corresponding to their journals. This allows lubricating oil to enter the cylinder head and be directed into the intake and exhaust camshafts, cooling them. The radial oil injection holes then provide cooling and lubrication for each camshaft.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The horizontal double-bar engine is used in motorcycles. The overall structure is compact. The oil cooler for cooling the high-temperature oil in the lubrication system is located on the frame outside the engine, further saving engine space.

[0018] 2. The timing sprocket drive mechanism is located at one end of the shaft, has a compact structure, and can effectively reduce vibration.

[0019] 3. The engine is cooled by combining air cooling and oil cooling, which saves more space than the traditional air cooling combined with water cooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the three-dimensional structure of a horizontal twin-cylinder motorcycle engine in an embodiment;

[0021] Figure 2 Schematic diagram of the cross-sectional structure of a horizontal twin-cylinder engine in the embodiment;

[0022] Figure 3 Schematic diagram of the assembly structure of the intake and exhaust mechanism, the valve mechanism and the crankshaft connecting rod mechanism in the embodiment;

[0023] Figure 4 Schematic diagram of the cross-sectional structure of the CVT transmission mechanism in the embodiment;

[0024] Figure 5 Schematic diagram of the assembly structure of the input gear and the output gear in the embodiment;

[0025] Figure 6 Schematic diagram of the disassembled structure of the CVT case in the embodiment;

[0026] Figure 7 Schematic diagram of the connection structure between the crankcase and the external oil cooler in the embodiment;

[0027] Figure 8 Schematic diagram of the distribution structure of the oil lubrication system after extraction in the embodiment;

[0028] Figure 9 Schematic diagram of the distribution structure of the lubricating oil circuits of the crankcase and cylinder head in the embodiment;

[0029] Figure 10 Schematic diagram of the cross-sectional structure of the intake camshaft in the embodiment. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the utility model for protection, but merely represents selected embodiments of the present invention. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following figures. Therefore, once an item is defined in one figure, it does not require further definition or explanation in subsequent figures. In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or relationships, are based on the positions or relationships shown in the figures, or the positions or relationships in which the inventive product is typically placed when in use. These terms are intended solely for ease of description and simplification of the present invention and do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance. Furthermore, terms such as "horizontal" and "vertical" do not imply that a component must be absolutely horizontal or overhanging, but rather may be slightly tilted. For example, "horizontal" simply refers to a direction that is more horizontal than "vertical," and does not imply that the structure must be completely horizontal, but rather may be slightly tilted. It should also be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0032] like Figure 1-Figure 5As shown, the horizontal twin-cylinder motorcycle engine provided in this embodiment includes a body 1, two cylinders, two pistons 6, a fuel injection device, an ignition device, a crank-connecting rod mechanism 7 and a valve mechanism 2. Each cylinder is equipped with two intake mechanisms 3 and two exhaust mechanisms 4 (in specific implementation, three or four sets can be provided). The valve mechanism 2 includes an intake camshaft 21 and an exhaust camshaft 23. The intake camshaft 21 and the exhaust camshaft 23 are respectively provided at the same side end positions. There is an intake timing sprocket 22 and an exhaust timing sprocket 24; the crank-connecting rod mechanism 7 includes a left crank 71, a right crank 73 and a crank pin 72 installed between the left crank 71 and the right crank 73, two piston connecting rods 61 are sleeved on the middle part of the crank pin 72, and a timing driving sprocket 74 is sleeved on the left crank 71. The timing driving sprocket 74 is located on the same side as the intake timing sprocket 22 and the exhaust timing sprocket 24, and is connected by a timing chain 25 (in the timing chain A guide plate and a tensioning plate are respectively provided on the left and right sides of the timing chain for tensioning and guiding the timing chain). A balance shaft driving gear 75 and a CVT driving pulley 81 are sequentially sleeved on the right crank 73 from the inside to the outside; a CVT driven pulley 82 is provided on one side of the CVT driving pulley 81. The CVT driving pulley 81 and the CVT driven pulley 82 are connected by a belt 83. The CVT driven pulley 82 is sleeved and fixed on a main transmission shaft 84. An input gear 85 is sleeved and fixed on the main transmission shaft 84. An output gear 88 connected to the input gear 85 is provided on one side of the input gear 85 (the CVT driving pulley 81, the CVT driven pulley 82, the belt and the main transmission shaft 84 together constitute the CVT transmission mechanism 8); a balance shaft 77 parallel to it is provided on one side of the right crank 73. A balance shaft driven gear 76 meshing with the balance shaft driving gear 75 is sleeved on the balance shaft 77. The valve train 2, intake mechanism 3, and exhaust mechanism 4 are all located at the front end of the engine (i.e., toward the front of the motorcycle). The crankshaft-connecting rod mechanism is located at the rear end of the engine body 1. The transmission mechanism is arranged horizontally, forming a horizontal twin-cylinder engine. Compared to a vertical twin-cylinder engine, this arrangement reduces the longitudinal assembly height. Furthermore, the right crank 73 is used to drive the CVT drive pulley 81, resulting in a compact overall layout. The intake timing sprocket 22 and exhaust timing sprocket 24 are located at the ends of the intake camshaft 21 and exhaust camshaft 23, respectively, unlike the traditional mounting position of the timing driven sprocket in a twin-cylinder engine. These locations are closer to the assembly end of the shaft, resulting in relatively low vibration. When the crankshaft-connecting rod mechanism 7 rotates after the piston 6 is ignited, it drives the CVT drive pulley 81, CVT driven pulley 82, and main drive shaft 84, which are then transmitted to the output gear via the input gear 85, achieving power output.When the right crank 73 rotates, the balance shaft driving gear 75 drives the balance shaft driven gear 76 meshing with it to rotate, thereby causing the balance shaft 77 to rotate. After the balance shaft 77 rotates, it can reduce the vibration of the engine.

[0033] like Figure 5 As shown, the input gear 85 and the output gear 88 are connected by an intermediate gear set. Specifically, the intermediate gear set includes a first helical tooth 86 and a second helical tooth 87. The first helical tooth 86 and the second helical tooth 87 are both sleeved on an intermediate shaft. The first helical tooth 86 is engaged with the input gear 85, and the second helical tooth 87 is engaged with the output gear 88. The input gear, the first helical tooth, the second helical tooth and the output gear are all helical gears.

[0034] Specifically, the engine body 1 in this embodiment includes a cylinder head cover 11, a cylinder head 12, a cylinder block 13, a crankcase, a left cover 16, a right cover 17, and a CVT cover 18. The cylinder head cover 11, cylinder head 12, and cylinder block 13 are connected in a front-to-back manner. The crankcase includes a left crankcase 14 and a right crankcase 15. The left crankcase 14 is sealed to the left cover 16 on the outside, and the right crankcase 15 is sealed to the right cover 17 on the inside. The CVT cover 18 is connected to the outside of the right cover 17 and together they form the CVT case. Multiple cooling fins are provided on the outer end surfaces of the cylinder head cover 11, cylinder head 12, and cylinder block 13. This separates the crankcase and CVT case in the engine body 1. Since the CVT case generates more heat than the crankcase, separating the two prevents hot air from the CVT case from flowing into the crankcase, which could affect the service life of the transmission components within the crankcase. The cylinder head cover 11, the cylinder head 12 and the cylinder body 13 are connected to the combustion chamber. After a plurality of cooling fins are arranged circumferentially on the outer end surfaces of the above components, the heat generated by the above components can be taken away by air cooling.

[0035] like Figure 6As shown, an air inlet duct 171 and an air outlet duct 172 are provided on the upper side of the right cover 17, communicating with the CVT case. The air inlet duct 171 is located near the CVT driving pulley 81, and the air outlet duct 172 is located near the CVT driven pulley 82. An air inlet chamber 181 is provided on the CVT cover 18, communicating with the air inlet duct 171. An air outlet 182 is provided on the side of the air inlet chamber 181 facing the right cover 17, corresponding to the blades of the CVT driving pulley 81. Thus, with the air inlet duct 171 and the air outlet duct 172 located on the upper side of the right cover 17, mold opening is simplified, effectively reducing mold opening costs. The upward-facing exhaust duct prevents stones from being thrown into the CVT case. After the motorcycle engine is started, the CVT driving pulley 81 rotates, causing the blades on the driving pulley to rotate as well, creating negative pressure outside the box. This draws cold air from outside the box through the air inlet duct 171 into the air inlet chamber 181, where it then flows through the exhaust port to the driving pulley, cooling the driving pulley. Simultaneously, under the action of the driving pulley blades, the air flows to the driven pulley, passes through the driven pulley, and is then guided clockwise along its sidewall to the air outlet duct 172, where the hot air is discharged. Because the air outlet is positioned forward, when the hot air is discharged from the exhaust duct, the external cold air will directly blow the hot air in the opposite direction of riding, preventing it from flowing to the front, instantly carrying away the hot air. The air inlet chamber 181, after drawing in the external cold air, allows the cold air to form a vortex within the air inlet chamber 181, increasing the air flow rate.

[0036] Furthermore, a barrier rib 173 is provided on the side of the right cover 17 facing the CVT cover 18. The upper end of the barrier rib 173 is connected to the upper wall of the right cover 17, and the lower end extends toward the axis of the CVT driven pulley 82. The barrier rib 173 is arranged at an angle, and its inclination is consistent with the direction of the air outlet 172. In this way, the barrier rib 173 can form a certain barrier to the air on the side of the driven pulley, preventing some of the hot air from being discharged from the air outlet 172 from entering the driving pulley through the space above the driven pulley and affecting the efficiency of hot air discharge.

[0037] like Figure 7 、 Figure 8As shown, it also includes an oil lubrication system 9, which includes an oil collecting chamber 91 provided at the bottom of the crankcase body and a coarse filter 92, an oil pump 93, an external oil cooler 94, a fine filter 95 and a main oil line 96 connected in sequence. One end of the coarse filter 92 is immersed in the lubricating oil in the oil collecting chamber 91, the oil pump 93 is assembled in the crankcase body, and the oil cooler is placed on the motorcycle frame outside the crankcase body and is provided with an oil inlet pipeline and an oil outlet pipeline; the fine filter 95 is connected to the main oil line 96 in sequence. Both the filter 95 and the coarse filter 92 are located on the lower end surface of the crankcase. The coarse filter 92 is connected to the oil inlet pipe of the oil pump 93 via a first oil guide channel located within the crankcase. The oil outlet of the first oil guide channel is connected to the oil inlet line of the oil cooler, while the oil outlet line of the oil cooler is connected to the fine filter 95 via a second oil guide channel located within the crankcase. The inner end of the fine filter 95 is located within the crankcase, and its end is connected to the main oil passage 96 within the crankcase. In this way, by providing heat sinks and air inlet and outlet ducts 171 and 172 for air cooling and heat dissipation, the oil lubrication system 9 is able to achieve oil cooling for the crankshaft, crankcase, cylinder block, and cylinder head. The lubricating oil in the oil collection chamber 91, after long-term circulation, will produce some impurities. Furthermore, after lubricating various components and returning to the oil collection chamber 91, the temperature of the lubricating oil will rise, affecting subsequent lubrication and cooling. After preliminary filtration through coarse filter 92, the high-temperature lubricating oil in the oil collection chamber is pumped to the oil cooler outside the crankcase body via oil pump 93. After cooling in the oil cooler, the oil is then directed from the oil cooler's oil outlet line to the crankcase body's second oil guide channel. Finally, it enters fine filter 95, undergoes further fine filtration, and is finally delivered to the various oil circuits through main oil passages 96 on the crankcase body to lubricate the various transmission components within the crankcase body. The coarse filter 92 and fine filter 95 are mounted on the lower end surface of the crankcase body, located on the same side, making installation and removal relatively easy, eliminating the need to stand on either side for installation or removal. The oil cooler is located outside the crankcase body, on the motorcycle frame, eliminating engine space and effectively reducing the engine's size.

[0038] Furthermore, the coarse filter is installed at a lower height than the fine filter 95. The oil lubrication system 9 also includes a main drive shaft lubrication oil passage 97, a crankshaft lubrication oil passage 98, a case oil outlet passage, two piston lubrication oil passages 99, and a cylinder block cooling oil passage 99a and a cylinder head cooling oil passage 99b, all connected to the main oil passage 96. Thus, placing the coarse filter in a lower installation position shortens the path between the oil collection chamber and the coarse filter. After cooling and fine filtering, the cooled lubricating oil is pumped through the main oil passage 96 to the main drive shaft, crankshaft, crankcase, pistons 6, and the cylinder block and cylinder head, providing cooling and lubrication for various high-temperature components within the engine.

[0039] like Figure 9As shown, the crankcase body is connected by a left crankcase 14 and a right crankcase 15; two piston oil nozzles 994 are arranged towards the back of the piston 6 in the crankcase body, and a left lubricating oil channel 991 and a right lubricating oil channel 992 are respectively provided on the docking surfaces of the left crankcase 14 and the right crankcase 15 with the cylinder body. One end of the right lubricating oil channel 992 is connected with the oil outlet channel of the case, and the two piston lubricating oil channels 99 are respectively provided in the left crankcase 14 and the right crankcase 15, and are connected with the left lubricating oil channel 991 and the right lubricating oil channel 992 on the corresponding sides; a matching oil channel 993 for connecting the left lubricating oil channel 991 and the right lubricating oil channel 992 is provided on the case docking surface of the cylinder body, and the left and right sides of the matching oil channel 993 correspond to the left lubricating oil channel 991 and the right lubricating oil channel 992 respectively. Thus, when the oil pump 93 pumps lubricating oil from the crankcase toward the cylinder, the oil passes through the crankcase's oil outlet passage and then enters the right lubricating oil passage 992, the mating oil passage 993, and the left lubricating oil passage 991. From there, it is directed through the left and right lubricating oil passages 991 and 992 to the corresponding piston oil nozzles 994. In this oil circuit, the lubricating oil from the right lubricating oil passage 992 is directed to the left lubricating oil passage 991 via the mating oil passage 993. This compact structure prevents leakage from the joint between the left and right crankcases 14 and 15 after the oil passages pass through them. The piston oil nozzles 994 are positioned facing the back of the piston 6, allowing the sprayed lubricating oil to directly reach the back of the piston 6. Since the temperature at the back of the piston 6 is highest, this arrangement effectively ensures lubrication and cooling of the piston 6.

[0040] Furthermore, a first oil passage 711 and a second oil passage 721 are respectively provided along the axial direction of the left crank 71 and crankpin 72. The first oil passage 711 and the second oil passage 721 are connected by an oblique oil guide passage. The crankpin 72 is also provided with oil injection holes corresponding to the two piston connecting rods 61. The first oil passage 711, the oblique oil guide passage, and the second oil passage 721 form the crankshaft lubricating oil passage 98. An end oil seal is provided at one end of the second oil passage 721 near the crankpin 72. Thus, the oblique oil guide passage can guide lubricating oil from the first passage into the second oil passage 721. One end of the oblique oil guide passage is provided at the end of the left crank 71, and the other end is provided at the crankpin 72. The left crank 71 and the crankpin 72 are connected by an interference fit at the end of the left crank 71, allowing for synchronous rotation. Therefore, during operation, the passages remain synchronized and connected. The oil injection holes are located at the two connecting rod 61 assembly points, providing lubrication and cooling for the small ends of the connecting rods 61. The second oil passage 721 within the crankpin 72 not only lubricates the assembly ends of the connecting rods 61 through the oil injection holes but also cools the crankpin 72, effectively ensuring a longer service life for the crankpin 72.

[0041] like Figure 3As shown, the intake mechanism 3 and the exhaust mechanism 4 are installed in the cylinder head 12, including valves, valve springs, valve spring upper seats and valve spring lower seats. The valve spring lower seat is fixedly connected to the engine body 1, the lower end of the valve spring is connected to the valve spring lower seat, the valve is arranged through the valve spring, and the upper end of the valve spring is clamped with the upper end of the valve; the intake camshaft 21 and the exhaust camshaft 23 are arranged at the front end of the intake mechanism 3 and the exhaust mechanism 4, and four cams are provided on the intake camshaft 21 and the exhaust camshaft 23. The four cams are divided into two groups, and the two groups of cams are opposite to each other. The intake camshaft 21 forms a 180-degree angle with the axis of the intake camshaft 21. A rocker shaft 5 is provided between the intake camshaft 21 and the intake mechanism 3, and between the exhaust camshaft 23 and the exhaust mechanism 4. Each rocker shaft 5 is equipped with four rocker arms 51, each of which contacts the top of a corresponding valve. The four cams on the intake camshaft 21 and the exhaust camshaft 23 correspond to the rocker arms one by one. When the intake camshaft and the exhaust camshaft 23 rotate, one set of cams contacts the corresponding rocker arm, squeezing the intake mechanism 3 or the exhaust mechanism 4 to achieve intake or exhaust. In this way, the intake mechanism 3 and the exhaust mechanism 4 achieve intake and exhaust through the rocker arms on the rocker shaft 5 pressing down on the valve tops, resulting in a compact overall structure.

[0042] like Figure 10 As shown, a camshaft cooling oil passage 211 is provided along the axial direction of the intake camshaft 21 and the exhaust camshaft 23, communicating with the cylinder head cooling oil passage 99b. Multiple radial oil injection holes 212 corresponding to the journals of the intake and exhaust camshafts 21 and 23 are also provided. Thus, after entering the cylinder head, the lubricating oil is introduced into the intake and exhaust camshafts 21 and 23, cooling them. The radial oil injection holes lubricate and cool each camshaft.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Ordinary technicians in this field should understand that those modifications or equivalent replacements of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A motorcycle horizontal twin-cylinder engine, comprising an engine block, two cylinders, two pistons, a fuel injection device, an ignition device, a crank-connecting rod mechanism, and a valve train, wherein each cylinder is equipped with multiple intake and exhaust mechanisms, the valve train comprising an intake camshaft and an exhaust camshaft, an intake timing sprocket and an exhaust timing sprocket being respectively sleeved on the same side end positions of the intake camshaft and the exhaust camshaft, characterized in that: The crank-connecting rod mechanism is located at the rear end of the valve mechanism, and includes a left crank, a right crank and a crank pin. Two piston connecting rods are sleeved on the middle part of the crank pin. A timing driving sprocket is sleeved on the left crank. The timing driving sprocket is located on the same side as the intake timing sprocket and the exhaust timing sprocket, and is connected by a timing chain. A balance shaft driving gear and a CVT driving pulley are sleeved on the right crank from the inside to the outside; a CVT driven pulley is provided on one side of the CVT driving pulley, and the CVT driving pulley and the CVT driven pulley are connected by a belt drive, and the CVT driven pulley is sleeved and fixed on a main drive shaft, and an input gear is sleeved and fixed on the main drive shaft, and an output gear connected to the input gear is provided on one side of the input gear; a balance shaft parallel to it is provided on one side of the right crank, and a balance shaft driven gear meshing with the balance shaft driving gear is sleeved on the balance shaft.

2. The motorcycle horizontal twin-cylinder engine according to claim 1, characterized in that: The engine body includes a cylinder head cover, a cylinder head, a cylinder body, a crankcase, a left cover, a right cover and a CVT cover. The cylinder head cover, the cylinder head and the cylinder body are connected front to back in sequence. The crankcase includes a left crankcase and a right crankcase. The outer side of the left crankcase is sealed with the left cover, and the right crankcase is sealed with the right cover. The CVT cover is connected to the outer side of the right cover and together with it forms a CVT case body; a plurality of heat sinks are provided on the outer end surfaces of the cylinder head cover, the cylinder head and the cylinder body.

3. The motorcycle horizontal twin-cylinder engine according to claim 2, characterized in that: An air inlet duct and an air outlet duct connected to the CVT case are provided on the upper side of the right cover, the air inlet duct is arranged close to the side of the CVT driving pulley, and the air outlet duct is arranged close to the side of the CVT driven pulley; an air inlet chamber connected to the air inlet duct is provided on the CVT cover, and an air exhaust port corresponding to the blades of the CVT driving pulley is provided on the side of the air inlet chamber facing the right cover.

4. The motorcycle horizontal twin-cylinder engine according to claim 3, characterized in that: A blocking rib is provided on the side of the right cover facing the CVT cover, the upper end of the blocking rib is connected to the upper wall of the right cover, and the lower end extends toward the CVT driven pulley shaft; the blocking rib is arranged obliquely, and the inclination direction is consistent with the air outlet duct.

5. The motorcycle horizontal twin-cylinder engine according to claim 1, 2, 3 or 4, characterized in that: It also includes an oil lubrication system, which includes an oil collecting chamber located at the bottom of the crankcase body and a coarse filter, an oil pump, an external oil cooler, a fine filter and a main oil circuit connected in sequence, one end of the coarse filter being immersed in the lubricating oil in the oil collecting chamber, the oil pump being assembled in the crankcase body, and the oil cooler being placed on a motorcycle frame outside the crankcase body, and being provided with an oil inlet pipe and an oil outlet pipe; the fine filter and the coarse filter are both located on the lower end surface of the crankcase body, the coarse filter is connected to the oil inlet pipe of the oil pump through a first oil guide channel located in the crankcase body, the oil outlet of the first oil guide channel is connected to the oil inlet pipe of the oil cooler, and the oil outlet pipe of the oil cooler is connected to the fine filter through a second oil guide channel located on the crankcase body; the inner end of the fine filter is placed in the crankcase body, and the end is connected to the main oil channel in the crankcase body.

6. The motorcycle horizontal twin-cylinder engine according to claim 5, characterized in that: The installation height of the coarse filter is lower than that of the fine filter. The oil lubrication system also includes a main transmission shaft lubricating oil channel, a crankshaft lubricating oil channel, a box oil outlet channel, two piston lubricating oil channels, a cylinder cooling oil channel and a cylinder head cooling oil channel connected to the main oil channel.

7. The motorcycle horizontal twin-cylinder engine according to claim 6, characterized in that: The crankcase body is formed by connecting a left crankcase and a right crankcase; two piston oil nozzles arranged towards the back of the piston are provided in the crankcase body, and a left lubricating oil channel and a right lubricating oil channel are respectively provided on the docking surfaces of the left crankcase and the right crankcase with the cylinder body, and one end of the right lubricating oil channel is connected with the oil outlet channel of the case body. The two piston lubricating oil channels are respectively provided in the left crankcase and the right crankcase, and are connected with the left lubricating oil channel and the right lubricating oil channel on the corresponding sides; a matching oil channel for connecting the left lubricating oil channel and the right lubricating oil channel is provided on the case docking surface of the cylinder body, and the left and right sides of the matching oil channel correspond to the left lubricating oil channel and the right lubricating oil channel respectively.

8. The motorcycle horizontal twin-cylinder engine according to claim 6, characterized in that: A first oil passage and a second oil passage are respectively provided in the left crank and crank pin along their axial directions. The first oil passage and the second oil passage are connected by an oblique oil guide passage. Oil injection holes corresponding to the two piston connecting rods are also provided on the crank pin. The first oil passage, the oblique oil guide passage and the second oil passage form the crankshaft lubricating oil passage.

9. The motorcycle horizontal twin-cylinder engine according to claim 1 or 2 or 3 or 4 or 6 or 7 or 8, characterized in that: The intake mechanism and the exhaust mechanism are installed in the cylinder head, and include valves, valve springs, an upper seat of the valve spring and a lower seat of the valve spring. The lower seat of the valve spring is fixedly connected to the engine body, the lower end of the valve spring is connected to the lower seat of the valve spring, the valve is arranged through the valve spring, and the upper end of the valve spring is clamped with the upper end of the valve; the intake camshaft and the exhaust camshaft are arranged at the front end of the intake mechanism and the exhaust mechanism, and four cams are respectively provided on the intake camshaft and the exhaust camshaft, and the four cams are divided into two groups, and the two groups of cams form an angle of 180 degrees relative to the axis of the intake camshaft; a rocker arm shaft is provided between the intake camshaft and the intake mechanism and between the exhaust camshaft and the exhaust mechanism, and four rocker arms are provided on each rocker arm shaft, each rocker arm is in contact with the corresponding valve top, and the four cams on the intake camshaft and the exhaust camshaft correspond to the rocker arms one by one. When the intake camshaft and the exhaust camshaft rotate, one group of cams is pressed against the corresponding rocker arm, squeezing the intake mechanism or the exhaust mechanism to realize intake or exhaust.

10. The motorcycle horizontal twin-cylinder engine according to claim 9, characterized in that: A camshaft cooling oil passage connected to the cylinder head cooling oil passage is provided in the intake camshaft and the exhaust camshaft along their axial direction. A plurality of radial oil spray holes corresponding to their journals are also provided on the intake camshaft and the exhaust camshaft.

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