Four-cylinder engine

Abstract

The invention discloses a four-cylinder engine, and relates to the technical field of engines. When the four-cylinder engine is started, the flywheel is driven to rotate, then the eccentric shaft and the eccentric wheel are driven to rotate, the eccentric wheel drives the large end of the synchronous connecting rod to do circular motion, the small end of the synchronous connecting rod drives the first connecting rod to do reciprocating rectilinear motion, and the first connecting rod drives the second connecting rod to do reciprocating rectilinear motion in the opposite direction through mutual driving gears; meanwhile, a first driving chain wheel and a second driving chain wheel which are fixed on the eccentric shaft respectively drive a first cam shaft and a second cam shaft to synchronously rotate through a first synchronous chain and a second synchronous chain, so that air intake, compression, work and exhaust of each air cylinder are completed, and synchronous work and accurate control of piston motion and an air distribution mechanism are realized. Linear thrust generated by fuel combustion always acts on the tangent point of the outer gear ring through the first connecting rod and the second connecting rod, the maximum rotating torque, namely torque, is generated through conversion in the whole working stroke, energy is output outwards, and energy loss in the operation process of the four-cylinder engine is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and in particular to a four-cylinder engine. Background Technology

[0002] In existing conventional engines, the linear thrust of the piston generated by fuel combustion and expansion is converted into the rotational torque (i.e., torque) of the crankshaft through the connecting rod and crankshaft, which is then output as energy. Through theoretical calculations and simulation tests, the torque transmission coefficient curve in this conversion process is parabolic (torque transmission coefficient: the ratio of the torque value generated by the conventional engine after conversion through the connecting rod and crankshaft to the torque value FR generated by the ideal structure conversion under the same piston position conditions, where F is the linear thrust of the piston, which is a variable as the piston moves downward, and R is the crankshaft rotation radius). The torque transmission coefficient is determined by the crankshaft structure parameters of the conventional engine and is a theoretical value; the actual crankshaft transmission loss is also related to the cylinder pressure curve when the engine is working. For example, the maximum in-cylinder pressure of a traditional engine usually occurs around 20 degrees of crankshaft rotation. However, the engine we tested only produced a torque of 0.4372FR after crankshaft conversion when the crankshaft rotation angle was 20 degrees. The torque transmission coefficient was optimal when the crankshaft rotation angle was between 60 and 100 degrees, but the in-cylinder pressure was already very low at this time. Therefore, the energy loss during transmission and conversion was relatively large throughout the power stroke, making it difficult to improve the thermal efficiency of a traditional engine.

[0003] A free piston engine is a new type of power unit that combines an internal combustion engine with a linear generator (or hydraulic pump, etc.). Its piston movement is not restricted by the crankshaft and directly outputs electrical or hydraulic energy through linear motion. However, when a cylinder in a free piston engine malfunctions or stops working, the compression or intake / exhaust strokes of other cylinders cannot be completed, causing the engine to stop working.

[0004] Therefore, how to reduce energy loss during engine operation while extending the engine's continuous operating time has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a four-cylinder engine that reduces energy loss during operation while extending the continuous working time of the four-cylinder engine.

[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides a four-cylinder engine, the four-cylinder engine comprising an eccentric shaft, an output assembly, and a valve train: The eccentric shaft is fitted with a flywheel and an eccentric wheel that are fixedly connected to the eccentric shaft. A synchronous connecting rod, a first connecting rod, and a second connecting rod are arranged in parallel from front to back behind the eccentric wheel. The eccentric wheel is rotatably connected to the large end of the synchronous connecting rod through a connecting shaft. The small end of the synchronous connecting rod is rotatably connected to the first connecting rod through a connecting pin. The first connecting rod meshes with the second connecting rod through mutually driving gears. The eccentric shaft is connected to a drive device, which drives the eccentric shaft to rotate during startup. The rotation axis of the eccentric shaft, the rotation axis of the eccentric wheel, and the center line of the eccentric shaft are coaxial. The eccentric shaft and the eccentric wheel are fixedly connected. The connecting shaft is fixedly connected to the eccentric wheel. The large end of the synchronous connecting rod is rotatably connected to the connecting shaft. The axial center line of the connecting shaft is eccentrically located to the axial center line of the eccentric wheel. When the drive device drives the eccentric shaft to rotate, the connecting shaft performs a circular motion around the axial center line of the eccentric shaft. The two ends of the first connecting rod are respectively connected by piston pins to a first piston slidably disposed in a first cylinder and a second piston slidably disposed in a second cylinder. The two ends of the second connecting rod are respectively connected by piston pins to a third piston slidably disposed in a third cylinder and a fourth piston slidably disposed in a fourth cylinder. The first cylinder and the second cylinder are arranged opposite to each other, arranged from front to back, and the third cylinder and the fourth cylinder are arranged opposite to each other. The rotation axis of the mutually driving gears is perpendicular to the movement direction of the first connecting rod. The first cylinder includes the first cylinder, the first connecting rod, and the first piston; the second cylinder includes the second cylinder, the first connecting rod, and the second piston; the third cylinder includes the third cylinder, the second connecting rod, and the third piston; and the fourth cylinder includes the fourth cylinder, the second connecting rod, and the fourth piston. The output component includes a main output shaft and a secondary output shaft, both of which are drivenly connected to the first connecting rod and the second connecting rod. Both the main output shaft and the secondary output shaft are used to output energy to the outside. The valve train is connected to the eccentric shaft drive. The valve train is used to control the opening and closing of the intake and exhaust passages of each cylinder provided on the first cylinder head and the second cylinder head, respectively. The valve train is matched with the first connecting rod and the second connecting rod so that when the four-cylinder engine is in operation, the four-cylinder engine alternately performs intake, compression, power, and exhaust according to the first cylinder, the second cylinder, the fourth cylinder, and the third cylinder; or, the four-cylinder engine alternately performs intake, compression, power, and exhaust according to the working sequence of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder.

[0007] The present invention achieves the following technical advantages over the prior art: The four-cylinder engine of the present invention includes an eccentric shaft, an output assembly, and a valve train. A flywheel and an eccentric wheel are fixedly connected to the eccentric shaft. A synchronizing link, a first link, and a second link are arranged in parallel from front to back behind the eccentric wheel. The eccentric wheel is rotatably connected to the large end of the synchronizing link via a connecting shaft, and the small end of the synchronizing link is rotatably connected to the first link via a connecting pin. As the eccentric shaft and eccentric wheel rotate, the connecting shaft and the large end of the synchronizing link perform circular motion, and then the small end of the synchronizing link performs reciprocating linear motion with the first link. The first link drives the second link to perform reciprocating linear motion in opposite directions via mutually driving gears. The eccentric shaft rotates linearly, synchronizing its operation with the first and second connecting rods and the first to fourth pistons. Simultaneously, as the eccentric shaft rotates, it drives the first and second drive sprockets, which in turn drive the first and second camshafts via the first and second synchronization chains and the driven sprockets of the first and second camshafts, thus synchronizing the operation of the first and second camshafts with the eccentric shaft. This synchronization of the eccentric shaft with the camshafts, and with the first and second connecting rods and the first to fourth pistons, achieves the necessary conditions for the normal operation of a four-cylinder, four-stroke engine.

[0008] Taking the first cylinder as an example, the advantages of this invention are briefly introduced: When the first cylinder is working, the linear thrust of the piston generated by fuel combustion is always applied to the tangent point of the outer gear ring of the first one-way clutch throughout the entire working stroke via the rack on the connecting rod. At this time, the first connecting rod moves to the right, the first one-way clutch engages, and drives the main output shaft to rotate. After conversion, the output shaft obtains the maximum rotational torque (i.e., torque) and outputs energy to the outside. Compared with the traditional engine connecting rod crankshaft mechanism conversion transmission, the transmission loss is greatly reduced. Furthermore, when the first cylinder is in its power stroke, the second cylinder is in its compression stroke, the fourth cylinder is in its intake stroke, and the third cylinder is in its exhaust stroke. The first and second cylinders share a first connecting rod, and the energy required for the compression stroke of the second cylinder is directly transferred from the first piston to the second piston through the first connecting rod, achieving near-lossless transmission. The energy required for the intake stroke of the fourth cylinder and the exhaust stroke of the third cylinder is transferred from the first connecting rod to the second connecting rod through the meshing of mutually driving gears. This direct transmission, achieved through the rigidity of the mechanical structures such as the first and second connecting rods and the first and fourth pistons, results in high transmission efficiency. Compared to existing engines, this invention avoids crankshaft transmission losses and improves energy transmission efficiency. For example, the mutually driving gears and the gears on the meshing surfaces of the first and second connecting rods and the mutually driving gears in this invention all use high-precision gear teeth, which reduces transmission losses. The average transmission efficiency of these energy transfers is as high as approximately 97%. In summary, the energy required for the operation of the four-cylinder engine in this invention is transmitted efficiently, and the transmission losses are significantly reduced compared to the crankshaft transmission of traditional engines.

[0009] Furthermore, in this invention, the eccentric wheel is connected to the first connecting rod via a synchronous connecting rod. The rotational speeds of the eccentric wheel, eccentric shaft, and flywheel are matched with the operating frequency of the four-cylinder engine. This allows the flywheel to be driven by the eccentric shaft, and energy is stored within the flywheel. The energy stored in the flywheel enables the first and second connecting rod piston assemblies to smoothly pass through their top and bottom dead centers. If a cylinder occasionally malfunctions or stops working, the energy stored in the flywheel will sustain the entire system's operation. Once the cylinder recovers, the entire system resumes normal operation. Obviously, this extends the continuous operating time of the four-cylinder engine. Moreover, since the eccentric wheel, eccentric shaft, and flywheel perform circular motion, the stored energy experiences almost no loss other than conventional mechanical losses.

[0010] In summary, the four-cylinder engine in this invention not only reduces energy transmission loss during operation, but also has a longer continuous working time. The fact that the structural verification prototype can shut down normally after working continuously for a maximum of 7 hours is the best proof of this. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of a four-cylinder engine. Figure 2 for Figure 1 Sectional view at AA; Figure 3 Rear view of a four-cylinder engine; Figure 4 for Figure 3 Top view of section BB in the middle; Figure 5 A schematic diagram of the main output shaft and the auxiliary output shaft; Figure 6 A schematic diagram of the structure of the first positioning roller and the second positioning roller; The components are as follows: 1. Secondary output shaft; 2. First mounting base; 3. Fourth one-way clutch assembly; 4. Chassis; 5. Second connecting rod; 6. First connecting rod; 7. Fourth cylinder; 8. Fourth piston; 9. Connecting pin; 10. Second piston; 11. Valve; 12. Intake passage; 13. Second camshaft; 14. Cam; 15. Second cylinder head; 16. Exhaust passage; 17. Synchronizing connecting rod; 18. Second camshaft driven sprocket; 19. Second synchronizing chain; 20. Eccentric wheel; 21. Connecting shaft; 22. Bearing bracket; 23. Bearing; 24. Flywheel; 25. Eccentric shaft; 26. Second driving sprocket; 27. First driving sprocket; 28. First synchronizing chain; 29. ​​Second one-way clutch assembly; 30. First positioning roller; 31. 31. Mutually driven gears; 32. Second positioning roller; 33. First piston; 34. Third piston; 35. First camshaft driven sprocket; 36. First camshaft; 37. First cylinder; 38. First cylinder head; 39. Third cylinder; 40. Main output shaft; 41. Second mounting base; 42. Third one-way clutch; 43. External gear ring; 44. First one-way clutch; 45. Second positioning rod; 46. First positioning rod; 47. Fourth one-way clutch; 48. Second one-way clutch; 49. First transmission gear; 50. Second transmission gear; 51. Transition gear; 52. First positioning plate; 53. Second positioning plate; 54. Mutually driven shaft; 55. Inner ring; 56. One-way locking element; 57. Outer ring; 58. Second cylinder. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0015] like Figures 1-6As shown, this invention discloses a four-cylinder engine, which includes an eccentric shaft 25, an output assembly, and a valve train. A flywheel 24 and an eccentric wheel 20 are fixedly connected to the eccentric shaft 25. A synchronous connecting rod 17, a first connecting rod 6, and a second connecting rod 5 are arranged in parallel from front to back behind the eccentric wheel 20. The eccentric wheel 20 is rotatably connected to the large end of the synchronous connecting rod 17 via a connecting shaft 21. The small end of the synchronous connecting rod 17 is rotatably connected to the first connecting rod 6 via a connecting pin 9. The first connecting rod 6 is connected by mutually driving gears. Wheel 31 meshes with the second connecting rod 5. The eccentric shaft 25 is connected to a drive device, which rotates the eccentric shaft 25 upon startup. The rotation axis of the eccentric shaft 25, the rotation axis of the eccentric wheel 20, and the center line of the eccentric shaft 25 are coaxial. The eccentric shaft 25 and the eccentric wheel 20 are fixedly connected. The connecting shaft 21 is fixedly connected to the eccentric wheel 20. The large end of the synchronous connecting rod 17 is rotatably connected to the connecting shaft 21. The axial center line of the connecting shaft 21 is eccentrically positioned relative to the axial center line of the eccentric shaft 25. When the drive device rotates the eccentric shaft 25... When the spindle 25 rotates, the connecting shaft 21 makes a circular motion around the axial center line of the eccentric shaft 25; the two ends of the first connecting rod 6 are respectively connected by piston pins to the first piston 33 slidably disposed in the first cylinder 37 and the second piston 10 slidably disposed in the second cylinder 58; the two ends of the second connecting rod 5 are respectively connected by piston pins to the third piston 34 slidably disposed in the third cylinder 39 and the fourth piston 8 slidably disposed in the fourth cylinder 7; the first cylinder 37 and the second cylinder 58 are arranged opposite to each other, and the first cylinder 37 and the third cylinder 39 are respectively connected by piston pins. The second cylinder 58 and the fourth cylinder 7 are arranged from front to back, and the third cylinder 39 and the fourth cylinder 7 are arranged opposite each other; the rotation axis of the mutual driving gear 31 is perpendicular to the movement direction of the first connecting rod 6; the first cylinder includes the first cylinder 37, the first connecting rod 6 and the first piston 33; the second cylinder includes the second cylinder 58, the first connecting rod 6 and the second piston 10; the third cylinder includes the third cylinder 39, the second connecting rod 5 and the third piston 34; the fourth cylinder includes the fourth cylinder 7, the second connecting rod 5 and the fourth piston 8; The output assembly includes a main output shaft 40 and an auxiliary output shaft 1, both of which are connected to the first connecting rod 6 and the second connecting rod 5. Both the main output shaft 40 and the auxiliary output shaft 1 are used to output energy externally. The main output shaft 40 is used to output energy externally, and the energy of the auxiliary output shaft 1 can be transmitted to the main output shaft 40 through the bridge gears 51 that mesh with the main output shaft 40 and the auxiliary output shaft 1 respectively, and then the main output shaft 40 outputs energy externally. The rear end of the auxiliary output shaft 1 can be used to connect to engine accessories to provide energy to the engine accessories. Moreover, the main output shaft 40 and the auxiliary output shaft 1 can be interchanged according to actual usage requirements. That is, the energy of the main output shaft 40 can be transmitted to the auxiliary output shaft 1 through the bridge gears 51 that mesh with the main output shaft 40 and the auxiliary output shaft 1 respectively, and then the auxiliary output shaft 1 outputs energy externally.

[0016] The valve train is connected to the eccentric shaft 25 for transmission. The valve train is used to control the opening and closing of the intake and exhaust passages of each cylinder located on the first cylinder head 38 and the second cylinder head 15 respectively. The valve train is matched with the first connecting rod 6 and the second connecting rod 5 so that when the four-cylinder engine is in operation, the four-cylinder engine alternately performs intake, compression, power, and exhaust according to the first cylinder, the second cylinder, the fourth cylinder, and the third cylinder; or, the four-cylinder engine alternately performs intake, compression, power, and exhaust according to the working order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder.

[0017] Based on the above structure, the four-cylinder engine of this invention includes an eccentric shaft 25, an output assembly, and a valve train. The eccentric shaft 25 is fitted with a flywheel 24 and an eccentric wheel 20 fixedly connected to it. Behind the eccentric wheel 20, a synchronizing link 17, a first link 6, and a second link 5 are arranged in parallel from front to back. The eccentric wheel 20 is rotatably connected to the large end of the synchronizing link 17, and the synchronizing link 17 is rotatably connected to the first link 6. As the eccentric shaft 25 and the eccentric wheel 20 rotate, the large end of the synchronizing link 17 performs a circular motion, and then the small end of the synchronizing link 17 performs a reciprocating linear motion with the first link 6. The first link 6 drives the second link 5 to perform a reciprocating linear motion in opposite directions through a mutual driving gear 31, thus achieving synchronized operation of the eccentric shaft 25, the first link 6, the second link 5, and the first piston 33 to the fourth piston 8. This synchronizing assembly is also applicable to two-stroke engines. Simultaneously, as the eccentric shaft 25 rotates, it drives the first and second drive sprockets to rotate. Through the first and second synchronization chains 19 and the driven sprockets of the first and second camshafts, it drives the first and second camshafts to rotate, achieving synchronous operation of the first and second camshafts 13 and the eccentric shaft 25. The eccentric shaft 25 is synchronized with the camshafts, and also synchronized with the first connecting rod 6, the second connecting rod 5, and the first piston 33 to the fourth piston 8. This achieves synchronous operation of the first connecting rod 6, the second connecting rod 5, the first piston 33 to the fourth piston 8, the eccentric shaft 25, and the valve train. At the same time, the four-cylinder engine control system will precisely control the ignition timing, injection timing, and injection duration based on the speed and position sensor signals on the eccentric shaft 25, the position sensor signals on the first camshaft 36 and the second camshaft 13, and signals from other sensors on the engine (the control system is existing technology, and its specific structure will not be described in detail). Thus, all systems and mechanisms of the engine achieve synchronous operation and precise control.

[0018] Taking the first cylinder's power stroke as an example, when the first cylinder is in operation, the linear thrust of the first piston 33 generated by fuel combustion acts on the tangent point of the outer gear ring 43 of the first one-way clutch 44 throughout the entire power stroke via the rack on the first connecting rod 6. At this time, the first connecting rod 6 moves to the right, the first one-way clutch 44 engages, and drives the main output shaft 40 to rotate. After conversion, the main output shaft 40 obtains the maximum rotational torque (i.e., torque) and outputs energy to the outside. Compared with the traditional engine connecting rod crankshaft mechanism conversion transmission, the transmission loss is greatly reduced. Furthermore, when the first cylinder is in its power stroke, the second cylinder is in its compression stroke, the fourth cylinder is in its intake stroke, and the third cylinder is in its exhaust stroke. The first and second cylinders share the first connecting rod 6. The energy required for the compression stroke of the second cylinder is directly transferred from the first piston 33 to the second piston 10 through the first connecting rod 6. This rigid structure allows for direct, near-lossless energy transfer. The energy required for the intake stroke of the fourth cylinder and the exhaust stroke of the third cylinder is transferred from the first connecting rod 6 to the second connecting rod 5 through the meshing of the mutual driving gear 31. This rigid, direct transmission through the mechanical structures of the first and second connecting rods 5, the first piston 33, and the fourth piston 8 avoids crankshaft transmission losses and improves energy transmission efficiency compared to existing conventional engines. For example, in this invention, the mutual driving gears, as well as the gears on the meshing surfaces of the first connecting rod 6, the second connecting rod 5, and the mutual driving gear 31, all use high-precision gear teeth, which reduces transmission losses. The energy transfer efficiency of the four-cylinder engine itself can reach approximately 97%. Thus, it can be seen that the energy required for the operation of the four-cylinder engine in this invention is efficiently transmitted, and the transmission losses are significantly reduced compared to the crankshaft transmission of conventional engines.

[0019] Furthermore, in this invention, the eccentric wheel 20 is connected to the first connecting rod 6 via the synchronous connecting rod 17. The rotational speeds of the eccentric wheel 20, the eccentric shaft 25, and the flywheel 24 are matched with the operating frequency of the four-cylinder engine. Thus, the flywheel 24 is driven by the eccentric shaft 25, and energy is stored in the flywheel 24. The energy stored in the flywheel 24 can power the first connecting rod piston assembly (which includes the first connecting rod 6, and structures such as the first piston 33 and the second piston 10 located at both ends of the first connecting rod 6 that can move with the first connecting rod 6) and the second connecting rod piston assembly (which includes the second connecting rod 5, and structures such as the third piston 34 and the fourth piston 8 located at both ends of the second connecting rod 5 that can move with the second connecting rod 4). The system smoothly passes through top and bottom dead centers. If a cylinder occasionally malfunctions or stops working, the energy stored in the flywheel 24 will keep the entire system running. Once the cylinder recovers, the entire system continues to operate normally. Obviously, this extends the continuous working time of the four-cylinder engine. Moreover, the eccentric wheel 20, eccentric shaft 25, flywheel 24, etc., move in a circular motion, and the stored energy suffers almost no loss other than conventional mechanical losses. The supplemented energy is transmitted through the synchronizing rod 17 and eccentric wheel, etc., and there are still some transmission losses. As can be seen from the above description, most of the energy in this structure is transmitted through a highly efficient transmission structure. The energy transmitted here accounts for a very small proportion of the total energy, so the loss here is limited.

[0020] In summary, the four-cylinder engine in this invention not only reduces energy loss during operation but also has a longer continuous working time.

[0021] Specifically, the driving device can be a rotary motor or other rotary drive device that can drive the eccentric shaft 25 to rotate.

[0022] like Figures 1-6As shown, the large end of the synchronizing link 17 is connected to the eccentric wheel 20 via the connecting shaft 21. The connecting shaft 21 is rotatably connected to the large end of the synchronizing link 17, and the connecting shaft 21 is fixedly connected to the eccentric wheel 20 (i.e., an interference fit). The small end of the synchronizing link 17 is rotatably connected to the first link 6 via the connecting pin 9. For example, the small end of the synchronizing link 17 and the connecting pin 9 are in a transition fit (i.e., a rotatable connection), and the connecting pin 9 is fixedly connected to the first link 6. When the eccentric shaft 25 rotates, the connecting shaft 21 and the large end of the synchronizing link 17 move in a circular motion around the center line of the eccentric wheel 20. The small end of the synchronizing link 17 is rotatably connected to the connecting pin 9, and the connecting pin 9 is interference-fitted to the first link 6. When the four-cylinder engine is running, the drive unit drives the eccentric shaft 25 and the eccentric wheel 20 to rotate. The large end of the synchronizing link 17 moves in a circular motion with the connecting shaft 21, and the small end of the synchronizing link 17 drives the first link 6 to reciprocate linearly via the connecting pin 9. Alternatively, the synchronous connecting rod 17, the first connecting rod 6, and the eccentric wheel 20 can be connected in other ways to achieve the following: "the rotation of the eccentric wheel 20 drives the synchronous connecting rod 17 to rotate, which in turn drives the first connecting rod 6 to perform reciprocating linear motion in the direction from the first cylinder 37 toward the second cylinder 58".

[0023] like Figures 1-6As shown, a housing 4 is provided outside the mutual drive gear 31. The two ends of the main output shaft 40 and the auxiliary output shaft 1 pass through the housing 4 and are rotatably connected to the first mounting seat 2 on the housing 4. The mutual drive gear 31 controls the upper and lower dead points of the second connecting rod 5, and enables the first connecting rod 6 and the second connecting rod to perform reciprocating linear motion in opposite directions. In the operation of the four-cylinder engine in this invention, the energy generated by the work of one of the cylinders from the first to the fourth cylinder is transferred to the other cylinders through the mutual drive gear 31, thereby satisfying the energy required for intake, compression, and exhaust of each cylinder. The first connecting rod 6 and the second connecting rod 5 are both rods with racks on three sides. The racks on the first connecting rod 6 and the second connecting rod 5 can be integrally machined on the rod; or, the rod and the rack can be machined separately, and the rack can be fixed on the three sides of the rod with fasteners such as screws. The two ends of the first connecting rod 6 are fixedly connected to the first piston 33 and the second piston 10 respectively by piston pins, and the two ends of the second connecting rod 5 are fixedly connected to the third piston 34 and the fourth piston 8 respectively by piston pins. The axial center lines of the corresponding piston pins used to fix the first piston 33, the second piston 10, the third piston 34, and the fourth piston 8 are aligned with the radial center lines of the first piston 33, the second piston 10, the third piston 34, and the fourth piston 8. The piston pins have a symmetrical structure and no eccentricity. The first piston 33 and the second piston 10 are respectively fitted onto the outer ends of the first connecting rod 6, and are transition-fitted with the first piston 33 and the second piston 10 (i.e., 0-to-0 fit). At the same time, the third piston 34 and the fourth piston 8 are respectively fitted onto the outer ends of the second connecting rod 5, and are transition-fitted with the third piston 34 and the fourth piston 8 (i.e., 0-to-0 fit). Thus, the first connecting rod 6 is basically positioned by the first piston 33 and the second piston 10, and the second connecting rod 5 is basically positioned by the third piston 34 and the fourth piston 8. Alternatively, other methods can be used to connect the corresponding connecting rods and the corresponding pistons.

[0024] A cross gear 51 meshes between the main output shaft 40 and the auxiliary output shaft 1. The end of the main output shaft 40 or the auxiliary output shaft 1 is used to connect to the load equipment. This allows the four-cylinder engine in this invention to concentrate the energy of the main output shaft 40 and the auxiliary output shaft 1 and output it outward in a unified manner. Alternatively, in a specific working scenario, the cross gear 51 can be omitted, and the main output shaft 40 and the auxiliary output shaft 1 can output energy to the load equipment and other structures respectively. The main output shaft 40 and the auxiliary output shaft 1 rotate in the same direction.

[0025] like Figures 1-6As shown, the four-cylinder engine also includes a positioning assembly, which includes a first positioning roller 30 located in front of and abutting against the first connecting rod 6, and a second positioning roller 32 located behind and abutting against the second connecting rod 5. The first positioning roller 30 and the second positioning roller 32 define the positions of the first connecting rod 6 and the second connecting rod 5, maintaining the engagement of the first connecting rod 6 with the second connecting rod 5 via the mutual drive gear 31. This prevents connecting rod deformation and positional movement during energy transmission, ensures that the piston on the second connecting rod 5 can reach the designed top dead center and bottom dead center, and guarantees the meshing clearance between the mutual drive gear 31 and the racks on the first and second connecting rods 6 and 5. Figures 1-6 As shown, a first positioning rod 46 passes through the first positioning roller 30, and a second positioning rod 45 passes through the second positioning roller 32. The first positioning rod 46 and the second positioning rod 45 are arranged parallel to each other, and their ends are respectively connected to opposite sides of the first positioning plate 52 and the second positioning plate 53. As needed, both the first positioning rod 46 and the second positioning rod 45 can be fixedly connected to the first positioning plate 52 and the second positioning plate 53. Figures 1-6 As shown, a mutual drive shaft 54 ​​is also installed inside the mutual drive gear 31 (the mutual drive gear 31 and the mutual drive shaft 54 ​​are connected by bearings), and the two ends of the mutual drive shaft 54 ​​are fixedly connected to the first positioning plate 52 and the second positioning plate 53 respectively.

[0026] like Figures 1-6As shown, the first cylinder 37 and the third cylinder 39 are installed in the first cylinder block, and the second cylinder 58 and the fourth cylinder 7 are installed in the second cylinder block. The valve train includes a first cylinder head 38 located on the left side of the first cylinder block and a second cylinder head 15 located on the right side of the second cylinder block. The first cylinder head 38 has an intake passage 12 and an exhaust passage 16 communicating with the first cylinder 37, and an intake passage 12 and an exhaust passage 16 communicating with the third cylinder 39. A first camshaft 36 is rotatably mounted inside the first cylinder head 38. The first camshaft 36 has several cams 14 corresponding to the intake passages 12 and the exhaust passages 16. A first camshaft driven sprocket 35 is fixedly mounted on the first camshaft 36. The first camshaft driven sprocket 35 is connected to a first drive sprocket 27 fixedly mounted on an eccentric shaft 25 via a first synchronous chain 28. The second cylinder head 15 has an intake passage communicating with the second cylinder 58. The cylinder head 15 includes a second camshaft 13 rotatably mounted inside the second cylinder head 15. The second camshaft 13 has several cams 14 corresponding to the intake and exhaust passages 12 and 16. A second camshaft driven sprocket 18 is fixedly mounted on the second camshaft 13. The second camshaft driven sprocket 18 is connected to a second drive sprocket 26 fixedly mounted on an eccentric shaft 25 via a second synchronous chain 19. Both the intake and exhaust passages 12 and 16 have valves 11 for controlling the opening and closing of the passages (the valves 11 in the intake passage 12 can be called intake valves, and the valves 11 in the exhaust passage 16 can be called exhaust valves). The cams 14 on the first and second camshafts 36 intermittently abut against the tappets at the corresponding intake and exhaust passages 12 and 16 to control the opening and closing of the corresponding valves 11.

[0027] The gear ratio between the driven sprocket 35 and the first drive sprocket 27 of the first camshaft is 2:1, and the gear ratio between the driven sprocket 18 and the second drive sprocket 26 of the second camshaft is 2:1. This causes the eccentric shaft 25 to rotate two revolutions, and the first camshaft 36 and the second camshaft 13 to rotate one revolution, thus enabling the four-stroke engine to operate normally.

[0028] In this invention, the ends of the main output shaft 40 and the auxiliary output shaft 1, i.e., the energy output ends, can be respectively connected to the load device for transmission, thereby outputting the energy generated by the corresponding cylinder; or, as... Figures 1-6 As shown, a first transmission gear 49 is fixedly sleeved on the main output shaft 40, and a second transmission gear 50 is fixedly sleeved on the auxiliary output shaft 1. The first transmission gear 49 meshes with the second transmission gear 50 through a bridge gear 51. This allows the four-cylinder engine in this invention to concentrate the energy received from the corresponding cylinders on the main output shaft 40 and the auxiliary output shaft 1 and output it uniformly. Figures 1-6As shown, the two ends of the main output shaft 40 and the auxiliary output shaft 1 are rotatably connected to 2 and the second mounting base 41, respectively, and a transmission rod passing through the bridge gear 51 is rotatably connected to the second mounting base 41.

[0029] like Figures 1-6 As shown, a first one-way clutch assembly and a third one-way clutch assembly are fixedly connected to the main output shaft 40. A second one-way clutch assembly 29 and a fourth one-way clutch assembly 3 are fixedly connected to the auxiliary output shaft 1. The first one-way clutch assembly and the second one-way clutch assembly 29 are engaged with the first connecting rod 6, and the third one-way clutch assembly and the fourth one-way clutch assembly 3 are engaged with the second connecting rod 5. Specifically, when the first link 6 moves to the right and the second link 5 moves to the left, the first one-way clutch assembly engages with the main output shaft 40, and the fourth one-way clutch assembly 3 engages with the auxiliary output shaft 1; when the first link 6 moves to the left and the second link 5 moves to the right, the third one-way clutch assembly engages with the main output shaft 40, and the second one-way clutch assembly 29 engages with the auxiliary output shaft 1.

[0030] When the first cylinder is in operation (the first cylinder includes the first cylinder barrel 37, the first connecting rod 6, and the first piston 33, etc.), the linear thrust of the piston generated by the combustion of the first cylinder pushes the first connecting rod 6 to move to the right. The gear teeth on the first connecting rod 6 drive the external gear ring 43 on the first one-way clutch 44 to rotate. The first one-way clutch assembly engages with the main output shaft 40, and the first one-way clutch assembly drives the main output shaft 40 to rotate. Throughout the entire working stroke of the first cylinder, the linear thrust on the first piston 33 always acts on the tangent point of the external gear ring 43 of the first one-way clutch through the first connecting rod 6. After conversion, the main output shaft 40 obtains the maximum rotational torque (i.e., torque) and outputs energy to the outside. The second one-way clutch assembly 29 separates from the auxiliary output shaft 1, the third one-way clutch assembly separates from the main output shaft 40, and drives the second connecting rod 5 to move to the left through the mutual driving gear 31. The fourth one-way clutch assembly 3 engages with the auxiliary output shaft 1, driving the auxiliary output shaft 1 to rotate.

[0031] Similarly, when the second cylinder is working (the second cylinder includes the second cylinder barrel 58, the first connecting rod 6, and the second piston 10, etc.), the linear thrust on the second piston 10 pushes the first connecting rod 6 to move to the left, the second one-way clutch assembly 29 engages with the auxiliary output shaft 1 and drives the auxiliary output shaft 1 to rotate, the first one-way clutch assembly disengages from the main output shaft 40, the fourth one-way clutch assembly 3 disengages from the auxiliary output shaft 1, and under the drive of the mutual driving gear 31, the second connecting rod 5 moves to the right, the third one-way clutch assembly engages with the main output shaft 40 and drives the main output shaft 40 to rotate.

[0032] When the fourth cylinder is in operation (the third cylinder includes the fourth cylinder 7, the second connecting rod 5, and the fourth piston 8, etc.), the linear thrust on the fourth piston 8 pushes the second connecting rod 5 to move to the left. The fourth one-way clutch assembly 3 engages with the auxiliary output shaft 1 and drives the auxiliary output shaft 1 to rotate. The second one-way clutch assembly 29 disengages from the auxiliary output shaft 1, and the third one-way clutch assembly disengages from the main output shaft 40. Under the action of the mutual driving gear 31, the first connecting rod 6 moves to the right, and the first one-way clutch assembly engages with the main output shaft 40 and drives the main output shaft 40 to rotate.

[0033] When the third cylinder is in operation (the third cylinder includes the third cylinder 39, the second connecting rod 5, the third piston 34, etc.), the second connecting rod 5 moves to the right, the third one-way clutch assembly engages with the main output shaft 40, driving the main output shaft 40 to rotate, the first one-way clutch assembly disengages from the main output shaft 40, and the fourth one-way clutch assembly 3 disengages from the auxiliary output shaft 1. Under the action of the mutual driving gear 31, the second one-way clutch assembly 29 engages with the auxiliary output shaft 1 and drives the auxiliary output shaft 1 to rotate.

[0034] In short, when the first link 6 or the second link 5 moves to the right, the first one-way clutch assembly and the third one-way clutch assembly engage with the main output shaft 40, and the second one-way clutch assembly 29 and the fourth one-way clutch assembly 3 disengage from the auxiliary output shaft 1; when the first link 6 or the second link 5 moves to the left, the first one-way clutch assembly and the third one-way clutch assembly disengage from the main output shaft 40, and the second one-way clutch assembly 29 and the fourth one-way clutch assembly 3 engage with the auxiliary output shaft 1.

[0035] In summary, when each cylinder performs a power stroke, two one-way clutch assemblies work together to output energy to the main output shaft 40 and the auxiliary output shaft 1. Therefore, this is more suitable for high-power, large-displacement engines. For low-power engines, that is, when the engine displacement and power requirements are small, only the first one-way clutch assembly can be set on the main output shaft 40, and only the second one-way clutch assembly 29 can be set on the auxiliary output shaft 1. The energy generated by the cylinders without one-way clutch assemblies can be transmitted to the first connecting rod 6 or the second connecting rod 5 through the mutual driving gear 31, and then transmitted to the main output shaft 40 or the auxiliary output shaft 1 by the first one-way clutch assembly or the second one-way clutch assembly 29, so as to output energy to the outside.

[0036] A balance shaft drive sprocket is fixedly sleeved on the eccentric shaft 25. A balance shaft mechanism is provided inside the housing 4. A balance shaft is provided on the balance shaft mechanism. A balance shaft driven sprocket is fixedly sleeved on the balance shaft. The balance shaft driven sprocket is connected to the balance shaft drive sprocket on the eccentric shaft 25 through a chain to prevent the eccentric shaft from vibrating at high speed.

[0037] The first one-way clutch assembly includes a first one-way clutch 44 and an outer gear ring 43 arranged sequentially from the inside out (the outer ring of the first one-way clutch 44 is interference-fitted with the inner hole of the outer gear ring 43, and the inner hole of the first one-way clutch 44 is interference-fitted with the main output shaft 40). The second one-way clutch assembly 29 includes a second one-way clutch 48 and an outer gear ring 43 arranged sequentially from the inside out (the outer ring of the second one-way clutch 48 is interference-fitted with the inner hole of the outer gear ring 43, and the inner hole of the second one-way clutch 48 is interference-fitted with the auxiliary output shaft 1). The third one-way clutch assembly includes a third one-way clutch 42 and an outer gear ring 43 arranged sequentially from the inside to the outside (the outer ring of the third one-way clutch 42 is interference-fitted with the inner hole of the outer gear ring 43, and the inner ring of the third one-way clutch 42 is interference-fitted with the main output shaft 40); the fourth one-way clutch assembly 3 includes a fourth one-way clutch 47 and an outer gear ring 43 arranged sequentially from the inside to the outside (the outer ring of the fourth one-way clutch 47 is interference-fitted with the inner hole of the outer gear ring 43, and the inner hole of the fourth one-way clutch 47 is interference-fitted with the auxiliary output shaft 1).

[0038] The first through fourth one-way clutches have the same structural composition. Taking the first one-way clutch assembly as an example, the structure is illustrated below: Figures 1-6 As shown, the first one-way clutch assembly includes a one-way clutch and an outer gear ring 43 arranged sequentially from the inside out. The one-way clutch includes an inner ring 55, a one-way locking element 56, and an outer ring 57 arranged sequentially from the inside out. The inner ring 55 is interference-fitted with the main output shaft 40, and the outer ring 57 is interference-fitted with the outer gear ring 43. When the first connecting rod 6 moves to the right, the inner ring 55 is connected to the outer ring 57 through the one-way locking element 56. When the first connecting rod 6 moves to the left, the inner ring 55 disengages from the outer ring 57. The engagement of the corresponding one-way clutch with the corresponding output shaft means that the inner ring 55 and the outer ring 57 of the one-way clutch are engaged, and vice versa. The one-way clutch can be a wedge type, roller type, ratchet type, electromagnetic one-way clutch, or any other clutch that can achieve the function of one-way engagement, depending on the actual situation.

[0039] In a traditional engine, the linear thrust of the piston generated by fuel combustion and expansion is converted into rotational torque (i.e., torque) through the connecting rod and crankshaft, thus outputting energy. Theoretical calculations and simulation measurements show that the torque transmission coefficient curve in this conversion process is parabolic (torque transmission coefficient: the ratio of the torque value generated by the traditional engine after conversion via connecting rod and crankshaft to the torque value FR generated by the ideal structure under the same piston position conditions, where F is the linear thrust of the piston, which is a variable as the piston moves downwards, and R is the crankshaft rotation radius). The torque transmission coefficient is determined by the transmission... The crankshaft structure parameters of a conventional engine are theoretical values, while the actual crankshaft transmission loss is also related to the cylinder pressure curve during engine power stroke. For example, the maximum cylinder pressure of a conventional engine generally occurs around a crankshaft angle of 20 degrees. However, the torque generated by the crankshaft after conversion at a crankshaft angle of 20 degrees in our test engine is only 0.4372FR. The torque transmission coefficient is optimal between crankshaft angles of 60 and 100 degrees, but the cylinder pressure is already very low at this time. Therefore, the energy loss during transmission and conversion is relatively large throughout the power stroke, making it difficult to improve the thermal efficiency of conventional engines. In this invention, the linear thrust of the piston generated by the combustion and expansion of fuel in each cylinder acts on the tangent point of the external gear ring of the one-way clutch throughout the entire power stroke via the first connecting rod 6 and the second connecting rod 5. The torque obtained by the output shaft after passing through the one-way clutch is always FR (F is the linear thrust acting on the piston, and R is the radius of the pitch circle of the external gear ring), which is an ideal structure, thus significantly improving the thermal efficiency of a four-cylinder engine.

[0040] Furthermore, the eccentric shaft 25 is fitted with a bearing 23 and a bearing bracket 22 from the inside out. The invention also provides a first medium channel on the main output shaft 40, communicating with the one-way clutches in the first and third one-way clutch assemblies, respectively. The auxiliary output shaft 1 provides second medium channels, communicating with the one-way clutches in the second and fourth one-way clutch assemblies 29 and 3, respectively. Both the first and second medium channels are used to inject media with lubricating, cleaning, and cooling functions, such as lubricating oil or other media possessing these functions simultaneously, to reduce mechanical wear of the one-way clutches and extend their service life. If an electromagnetic one-way clutch is used, the aforementioned medium channels are used to house the power supply circuit and control circuit.

[0041] The four-cylinder engine also includes an electronic control system and various sensors. Speed ​​sensors and angle sensors are installed on the eccentric shaft 25, the first camshaft 36, and the second camshaft 13. The control system will accurately control the ignition timing, injection timing, and injection duration of each cylinder based on the speed and position sensor signals of the eccentric shaft 25, the position sensor signals on the first camshaft 36 and the second camshaft 13, and the signals and feedback signals from other engine sensors.

[0042] Furthermore, while ensuring exhaust emissions meet standards, combustion efficiency is maximized without controlling combustion speed, as energy transfer efficiency remains close to 100% throughout the entire power stroke. In addition, knocking in traditional engines is caused by a non-linear relationship between piston speed and crankshaft angular velocity. However, in this invention, the piston speeds are linearly related through the meshing of racks on the first connecting rod 6 and the second connecting rod 5 with the gears on the corresponding one-way clutch outer gear rings on the main output shaft 40 and the auxiliary output shaft 1. Therefore, knocking is less likely to occur, a fact verified in the structural verification prototype tests.

[0043] Compared to traditional engines: This invention solves three major problems: crankshaft transmission loss, energy loss during compression and intake / exhaust strokes, and engine knock. It also boasts broad fuel adaptability, allowing for the use of more fuels, particularly renewable and low-carbon environmentally friendly fuels. Compared to free-piston engines: This invention: 1. Employs a highly reliable purely mechanical structure, solving the uncontrollable problem of free-piston engines; 2. Achieves energy storage through mechanisms such as the flywheel 24, addressing the limitation of free-piston engines to prolonged operation; 3. Utilizes the characteristics and orderly control of various mechanical structures to achieve smooth operation and extended working time for a four-cylinder engine; 4. While current free-piston engines convert the chemical energy of fuel into mechanical energy, which is then directly converted into electrical energy output via a linear generator, this invention uses a mechanical one-way clutch to directly output mechanical energy, resulting in higher output efficiency and suitability for more operating scenarios. Of course, the energy output system in this invention can also use a linear generator to directly output electrical energy (linear generators and related structures are existing technologies, and their specific structures will not be described in detail).

[0044] This invention discloses multiple technical solutions, but does not provide any contrary technical teachings. Any content not covered in this invention is applicable to existing technologies.

[0045] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A four-cylinder engine, characterized in that, The four-cylinder engine includes an eccentric shaft, output assembly, and valve train: The eccentric shaft is fitted with a flywheel and an eccentric wheel that are fixedly connected to the eccentric shaft. A synchronous connecting rod, a first connecting rod, and a second connecting rod are arranged in parallel from front to back behind the eccentric wheel. The eccentric wheel is rotatably connected to the large end of the synchronous connecting rod through a connecting shaft. The small end of the synchronous connecting rod is rotatably connected to the first connecting rod through a connecting pin. The first connecting rod meshes with the second connecting rod through mutually driving gears. The eccentric shaft is connected to a drive device, which drives the eccentric shaft to rotate during startup. The rotation axis of the eccentric shaft, the rotation axis of the eccentric wheel, and the center line of the eccentric shaft are coaxial. The eccentric shaft and the eccentric wheel are fixedly connected. The connecting shaft is fixedly connected to the eccentric wheel. The large end of the synchronous connecting rod is rotatably connected to the connecting shaft. The axial center line of the connecting shaft is eccentrically located to the axial center line of the eccentric wheel. When the drive device drives the eccentric shaft to rotate, the connecting shaft performs a circular motion around the axial center line of the eccentric shaft. The two ends of the first connecting rod are respectively connected by piston pins to a first piston slidably disposed in a first cylinder and a second piston slidably disposed in a second cylinder. The two ends of the second connecting rod are respectively connected by piston pins to a third piston slidably disposed in a third cylinder and a fourth piston slidably disposed in a fourth cylinder. The first cylinder and the second cylinder are arranged opposite to each other, arranged from front to back, and the third cylinder and the fourth cylinder are arranged opposite to each other. The rotation axis of the mutually driving gears is perpendicular to the movement direction of the first connecting rod. The first cylinder includes the first cylinder, the first connecting rod, and the first piston; the second cylinder includes the second cylinder, the first connecting rod, and the second piston; the third cylinder includes the third cylinder, the second connecting rod, and the third piston; and the fourth cylinder includes the fourth cylinder, the second connecting rod, and the fourth piston. The output component includes a main output shaft and a secondary output shaft, both of which are drivenly connected to the first connecting rod and the second connecting rod. Both the main output shaft and the secondary output shaft are used to output energy to the outside. The valve train is connected to the eccentric shaft drive. The valve train is used to control the opening and closing of the intake and exhaust passages of each cylinder provided on the first cylinder head and the second cylinder head, respectively. The valve train is matched with the first connecting rod and the second connecting rod so that when the four-cylinder engine is in operation, the four-cylinder engine alternately performs intake, compression, power, and exhaust according to the first cylinder, the second cylinder, the fourth cylinder, and the third cylinder; or, the four-cylinder engine alternately performs intake, compression, power, and exhaust according to the working sequence of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder.

2. The four-cylinder engine according to claim 1, characterized in that, The main output shaft meshes with the auxiliary output shaft via a bridge gear, and the main output shaft has an energy output end for transmission connection with the load device.

3. The four-cylinder engine according to claim 1, characterized in that, A first one-way clutch assembly fixedly connected to the main output shaft is sleeved on the main output shaft, and a second one-way clutch assembly fixedly connected to the auxiliary output shaft is sleeved on the auxiliary output shaft. The first one-way clutch assembly and the second one-way clutch assembly are engaged with the first connecting rod. Specifically, when the first connecting rod moves to the right and the second connecting rod moves to the left, the first one-way clutch assembly engages with the main output shaft; when the first connecting rod moves to the left and the second connecting rod moves to the right, the second one-way clutch assembly engages with the auxiliary output shaft.

4. The four-cylinder engine according to claim 3, characterized in that, The main output shaft is also fitted with a third one-way clutch assembly that is fixedly connected to the main output shaft, and the auxiliary output shaft is also fitted with a fourth one-way clutch assembly that is fixedly connected to the auxiliary output shaft. Both the third one-way clutch assembly and the fourth one-way clutch assembly are engaged with the second connecting rod. Specifically, when the first connecting rod moves to the right and the second connecting rod moves to the left, the fourth one-way clutch assembly engages with the auxiliary output shaft; when the first connecting rod moves to the left and the second connecting rod moves to the right, the third one-way clutch assembly engages with the main output shaft.

5. The four-cylinder engine according to claim 3 or 4, characterized in that, The first one-way clutch assembly includes a one-way clutch and an outer gear ring arranged sequentially from the inside to the outside. The one-way clutch includes an inner ring, a one-way locking member, and an outer ring arranged sequentially from the inside to the outside. The inner ring is interference-fitted with the main output shaft, and the outer ring is interference-fitted with the inner hole of the outer gear ring. When the first connecting rod moves to the right, the inner ring is connected to the outer ring through the one-way locking member. When the first connecting rod moves to the left, the inner ring disengages from the outer ring.

6. The four-cylinder engine according to claim 4, characterized in that, The main output shaft is provided with a first medium channel that communicates with the first one-way clutch assembly and the third one-way clutch assembly respectively, and the auxiliary output shaft is provided with a second medium channel that communicates with the second one-way clutch assembly and the fourth one-way clutch assembly respectively. The first medium channel and the second medium channel are used to inject a medium with lubrication, cooling and cleaning functions. The four-cylinder engine also includes a positioning assembly, which includes a first positioning roller located in front of the first connecting rod and abutting against the first connecting rod, and a second positioning roller located behind the second connecting rod and abutting against the second connecting rod.

7. The four-cylinder engine according to claim 1, characterized in that, The first cylinder and the third cylinder are installed in the first cylinder body, and the second cylinder and the fourth cylinder are installed in the second cylinder body; The valve train includes a first cylinder head located on the left side of the first cylinder block and a second cylinder head located on the right side of the second cylinder block. The first cylinder head has corresponding intake and exhaust passages that communicate with the first cylinder and the third cylinder, respectively. A first camshaft is rotatably mounted inside the first cylinder head. The first camshaft has a plurality of cams for controlling the opening and closing of the intake and exhaust valves on the first and third cylinders. A first camshaft driven sprocket is fixedly mounted on the first camshaft. The first camshaft driven sprocket is connected to a first drive sprocket fixedly mounted on the eccentric shaft via a first synchronous chain. The second cylinder head is provided with corresponding intake passages and exhaust passages that communicate with the second cylinder and the fourth cylinder, respectively. A second camshaft is rotatably mounted inside the second cylinder head. The second camshaft is provided with a plurality of cams for controlling the opening and closing of the intake valves and exhaust valves on the second cylinder and the fourth cylinder. A second camshaft driven sprocket is fixedly mounted on the second camshaft. The second camshaft driven sprocket is connected to a second drive sprocket fixedly mounted on the eccentric shaft via a second synchronous chain. The intake passage and the exhaust passage are each provided with valves for opening and closing the intake passage or the exhaust passage; the first camshaft and the second camshaft are each provided with cams for controlling the opening and closing of the valves.

8. The four-cylinder engine according to claim 7, characterized in that, The tooth ratio of the first camshaft driven sprocket to the first driving sprocket is 2:1, and the tooth ratio of the second camshaft driven sprocket to the second driving sprocket is 2:1; the four-cylinder engine is a four-stroke four-cylinder engine.

9. The four-cylinder engine according to claim 1, characterized in that, The eccentric shaft is fixedly connected to the eccentric wheel, the connecting shaft is fixedly connected to the eccentric wheel, the large end of the synchronizing rod is rotatably connected to the connecting shaft, the small end of the synchronizing rod is transitionally fitted to the connecting pin, and the connecting pin is fixedly connected to the first connecting rod. The above synchronization structure is suitable for the synchronous operation and precise control of a four-stroke engine or a two-stroke engine.

10. The four-cylinder engine according to claim 1, characterized in that, The first connecting rod is connected to the first piston and the second piston at both ends by piston pins, and the second connecting rod is connected to the third piston and the fourth piston at both ends by piston pins. The axial center lines of the corresponding piston pins are respectively aligned with the radial center lines of the first piston, the second piston, the third piston, and the fourth piston, meaning the piston pins are symmetrically arranged. The first piston and the second piston are respectively sleeved on the outer sides of both ends of the first connecting rod and are transition-fitted with the first connecting rod. The third piston and the fourth piston are respectively sleeved on the outer sides of both ends of the second connecting rod and are transition-fitted with the second connecting rod.

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