A valvetrain for a top-mounted ported scavenged two-stroke engine
By incorporating a scavenging switch mechanism and intake cam control in an overhead valve two-stroke engine, efficient scavenging is achieved, solving the problem of poor scavenging performance in traditional two-stroke engines, improving combustion efficiency and emission performance, and reducing fuel consumption and cost.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- FUSHUN BAOMING TECHNOLOGY CO LTD
- Filing Date
- 2025-06-23
- Publication Date
- 2026-08-04
AI Technical Summary
Traditional two-stroke engines have poor scavenging performance, resulting in low combustion efficiency and poor emissions performance. Four-stroke engines suffer from stroke loss and mechanical wear, leading to fuel waste and increased costs.
The engine adopts a top-mounted valve type scavenging two-stroke engine. By setting a guide valve switch mechanism at the intersection of the intake manifold and the intake valve mounting hole, the guide valve tube moves back and forth with the intake valve rod to pass through the intake bend, forming a guide valve channel. The position of the guide valve outlet is controlled to achieve the closing and opening of the intake valve head. Combined with the intake cam, the intake valve head is pushed into the combustion chamber to scaveng.
It improves scavenging efficiency, enhances combustion efficiency and emission performance, reduces fuel consumption and mechanical wear, and reduces engine size and manufacturing costs.
Smart Images
Figure CN224592222U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of internal combustion engine technology, and in particular to a top-valve type high-efficiency scavenging two-stroke engine, which is suitable for power equipment such as automobiles, ships, and generator sets that require high power density, low fuel consumption and low emissions. Background Technology
[0002] Internal combustion engines have a history of over 150 years since their invention. Based on their working cycle, they are mainly divided into two-stroke engines and four-stroke engines. Traditional two-stroke engines use a side-mounted valve intake and exhaust system with mixed lubrication. One revolution of the crankshaft completes one power stroke, while the piston completes the four processes of intake, compression, power, and exhaust through two strokes. The exhaust gases are propelled out by a fresh air-fuel mixture. However, due to limitations in its structure, valve train, and scavenging process, there is a significant amount of residual exhaust gas, and unburned oil is expelled with the exhaust. This results in low combustion efficiency, poor emissions performance, severe exhaust pollution, and high fuel consumption. Four-stroke engines typically employ overhead valves, with intake and exhaust valves located in the cylinder block and cylinder head. The crankshaft completes one power stroke in two rotations, and the piston completes the four processes of intake, compression, power, and exhaust through four strokes. While this solves the exhaust emission problem through separate lubrication, its operating method has significant drawbacks. The engine crankshaft needs to rotate twice to complete one power stroke, resulting in substantial stroke losses and unnecessary mechanical wear, as well as additional energy and time consumption, leading to fuel waste and mechanical damage. Furthermore, the long power stroke cycle results in a large engine size and increased manufacturing costs. Therefore, there is an urgent need to develop new engine structures and valve designs to solve these technical problems.
[0003] Patent document CN107420195B discloses a two-stroke engine based on a four-stroke engine structure. It includes a crankshaft and connecting rod mechanism, a lubrication system, a cooling system, a starting system, a fuel supply system, a valve train, and an ignition system. The improved structure features a longitudinally positioned intake manifold and a longitudinally positioned streamlined intake valve head. The valve seat ring within the intake manifold has a narrow throat, and the intake valve head seals the area below the valve seat ring. During operation, the transmission ratio between the crankshaft and the intake and exhaust camshafts is 1:1. Each reciprocating motion of the piston within the cylinder drives the crankshaft and connecting rod mechanism to rotate one revolution, which in turn drives the intake and exhaust valves to open once each via the camshaft transmission mechanism, forming a two-stroke working cycle. When the intake valve opens, the exhaust valve also opens. Fresh gas enters the cylinder combustion chamber through the gap between the narrow throat of the intake manifold and the intake valve head. The streamlined surface of the intake valve head guides the airflow to complete the scavenging process, increasing the effect of ejecting exhaust gases after combustion in the cylinder. The intake valve remains within the intake manifold at all times. Compared to traditional disc-shaped valve heads, it enhances the airflow guidance effect. However, its intake valve head is still located at the intake manifold opening. Moreover, due to the narrow throat of the intake manifold, it greatly hinders the entry of fresh gas, reduces the gas flow, and severely limits the guiding gas function. In particular, it cannot reach into the piston cylinder and deeper areas to guide gas to scavenge exhaust gases, resulting in poor exhaust gas scavenging effect. Therefore, it cannot further improve combustion efficiency and emission performance. Utility Model Content
[0004] The purpose of this invention is to provide a top-mounted valve type scavenging two-stroke engine, which solves the problem that it is difficult to scavenge exhaust gas when converting a traditional top-mounted valve engine from a four-stroke to a two-stroke working mode, resulting in poor combustion efficiency and emission performance. After entering the engine combustion chamber through the intake valve and setting a position, it connects to the intake manifold for scavenging and exhausting exhaust gas, thereby improving combustion efficiency and emission performance.
[0005] The technical solution adopted by this utility model is as follows: the overhead valve type scavenging two-stroke engine includes a block assembly, an overhead valve type valve train, and a crankshaft connecting rod mechanism that drives the intake cam and exhaust cam to rotate in a two-stroke operation. A valve rod with an intake valve head is provided in the intake valve mounting hole of the valve train. The key technical point is that an air guide switch mechanism is provided in the intake bend at the intersection of the intake passage and the intake valve mounting hole.
[0006] The air intake switch mechanism is as follows: an air intake pipe is fixedly installed on the intake valve stem, and an air intake outlet is provided between the air intake pipe and the intake valve head; the air intake pipe passes through the intake bend and closes the intake passage by reciprocating with the intake valve stem; the air intake pipe enters the engine combustion chamber and connects the intake passage by reciprocating with the intake valve stem.
[0007] The intake cam of the valve train is provided with an intake cam protrusion that pushes the front end of the intake valve guide tube into the engine combustion chamber.
[0008] The inner wall of the air intake bend is provided with an arc-shaped air guide groove around the circumference of the air guide pipe.
[0009] The intake bend is provided with a thickened inlet, and an air guide sleeve is fixedly installed in the intake valve mounting hole. The air guide sleeve is sleeved on the rear of the air guide pipe. The air guide pipe moves back and forth with the intake valve rod to engage the air guide sleeve and close the intake passage; the air guide pipe moves back and forth with the intake valve rod to disengage from the air guide sleeve and open the intake passage.
[0010] The air guide sleeve is fitted over the air guide tube.
[0011] The air guide sleeve is nested inside the air guide tube.
[0012] The air guide tube is fixed to the intake valve stem by a connecting rod or connecting rib plate as a support.
[0013] An air guide plate for guiding scavenging air is provided between the air guide pipe and the intake valve head.
[0014] The air guide plate is an elliptical thin plate that is obliquely fixed to the intake valve stem. The sloping surface of the elliptical thin plate and the front end of the air guide pipe form an air outlet.
[0015] The air guide plate is a sloping front end plate of the air guide pipe, and an air guide outlet is provided on the side wall of the air guide pipe near the valve head of the front end plate.
[0016] The air guide plate is a flared thin plate fixed to the intake valve stem, and the outer slope of the flared thin plate forms an air outlet with the front end of the air guide pipe.
[0017] The advantages and beneficial effects of this utility model are as follows: Because this overhead valve type scavenging two-stroke engine uses an overhead valve valve train and a two-stroke crankshaft connecting rod mechanism, it forms an independent lubrication system and completes one power stroke per crankshaft rotation. An air guide switch mechanism is installed in the intake bend. This mechanism uses an air guide pipe fixed to the intake valve stem, with an air guide outlet between the air guide pipe and the intake valve head. This allows the inner cavity of the air guide pipe to form a connected air guide channel with the air guide outlet, and controls the position of the air guide outlet. The air guide pipe wall penetrates and inserts into the intake bend to close it, and moves with the intake valve stem into the engine combustion chamber to connect the intake bend. This forms a valve that closes and opens the intake passage as the intake valve moves up and down, ensuring that the intake passage remains closed even when the intake valve head leaves the intake passage outlet, and only connects to the intake passage when the rear end of the air guide pipe leaves the closed intake bend. The system uses a scavenging method where compressed air is injected from the air outlet extending into the engine combustion chamber for scavenging. The combustion chamber then pushes the exhaust gas out. The intake cam of the valve train also features a cam protrusion that pushes the intake valve head into the combustion chamber. This cam movement controls the intake valve guide pipe's extension into the combustion chamber's guide area, creating a targeted scavenging effect. This allows fresh air entering the combustion chamber to be directed into the guide area, effectively scavenging the exhaust gas deep within the cylinder block's combustion chamber. This opens the exhaust valve, quickly and efficiently removing exhaust gas, saving intake air volume, and significantly improving scavenging efficiency. This avoids the problem of traditional intake valves only scavenging at the valve opening, resulting in low scavenging efficiency. This improves combustion efficiency and emissions performance. Combined with the two-stroke engine's operating mode, it greatly enhances engine efficiency. Attached Figure Description
[0018] The present invention will be further described below with reference to the accompanying drawings.
[0019] Figure 1 This is a structural schematic diagram of Embodiment 1 of the present utility model;
[0020] Figure 2 This is a schematic diagram of the gas distribution mechanism structure of Embodiment 1 of this utility model;
[0021] Figure 3 yes Figure 2 Sectional view along axis AA;
[0022] Figure 4 This is a schematic diagram of the gas distribution mechanism structure of Embodiment 2 of this utility model;
[0023] Figure 5 yes Figure 4 BB-direction sectional view;
[0024] Figure 6 yes Figure 5 CC-direction sectional view;
[0025] Figure 7 This is a schematic diagram of the gas distribution mechanism structure of Embodiment 3 of this utility model;
[0026] Figure 8 This is a schematic diagram of the gas distribution mechanism structure of Embodiment 4 of this utility model;
[0027] Figure 9 This is a schematic diagram of the first intake valve structure according to an embodiment of the present utility model;
[0028] Figure 10 This is a schematic diagram of a second intake valve structure according to an embodiment of the present invention;
[0029] Figure 11 This is a schematic diagram of a third intake valve structure according to an embodiment of the present invention;
[0030] Figure 12 This is a schematic diagram of the fourth intake valve structure according to an embodiment of the present utility model;
[0031] Figure 13 This is a structural schematic diagram of the second working state of Embodiment 1 of this utility model;
[0032] Figure 14 This is a structural schematic diagram of the third working state of Embodiment 1 of this utility model;
[0033] Figure 15 This is a structural schematic diagram of the fourth working state of Embodiment 1 of this utility model;
[0034] Figure 16 This is a structural schematic diagram of the fifth working state of Embodiment 1 of this utility model;
[0035] Figure 17 This is a structural schematic diagram of the working state of Embodiment 3 of this utility model;
[0036] Figure 18 This is a structural schematic diagram of the fourth working state of Embodiment 3 of this utility model;
[0037] Figure 19 This is a structural schematic diagram of the fourth embodiment of this utility model in its working state one;
[0038] Figure 20 This is a structural schematic diagram of the fourth working state of this utility model;
[0039] Figure 21 This is a schematic diagram of the gas distribution phase of this utility model.
[0040] The numbers in the diagram are explained as follows: 1. Cylinder head, 2. Intake manifold, 3. Intake valve, 4. Engine combustion chamber, 5. Piston, 6. Crankshaft, 7. Crankcase, 8. Intake valve cam, 81. Protrusion, 9. Intake valve spring, 10. Intake valve mounting hole, 11. Exhaust valve cam, 12. Exhaust valve, 13. Exhaust port, 14. Fuel injector, 15. Air guide area, 16. Valve guide, 17. Intake bend, 18. Fresh air, 19. Arc-shaped air guide groove, 20. Thickened inlet, 21. Air guide sleeve, 22. Exhaust gas, 31. Intake valve stem, 32. Air guide pipe, 32-1. Rear end of air guide pipe, 33. Intake valve head, 34. Air guide outlet, 35. Bracket, 36. Elliptical thin plate, 37. Sloping front end plate, 38. Trumpet-shaped thin plate. Detailed Implementation
[0041] according to Figure 1-21 The present invention will be described in detail below, as shown in Embodiment 1. Figures 1 to 3 As shown, a top-mounted valve type scavenging two-stroke engine includes an engine block assembly, a crankshaft and connecting rod mechanism, a valve train, a fuel supply system, and a lubrication system. The engine block assembly includes a cylinder block 4, a cylinder head 1, and a crankcase 7. The valve train uses top-mounted valves. An intake valve 3, driven by an intake valve cam 8 and an intake valve spring 9, is located on the cylinder head 1. The intake valve stem 31 of the intake valve 3 is located within an intake valve mounting hole 10, and the rear part of the intake valve stem 31 is located within a valve guide 16 above the intake valve mounting hole. The intake valve head 33 is used to close and open the intake passage at the front end of the intake valve stem 31. The crankshaft 6 of the crankshaft and connecting rod mechanism drives the camshaft to rotate synchronously with the crankshaft via a timing gear, chain, or timing belt, operating in a two-stroke mode.
[0042] The improvement lies in the following: At the intersection of the intake manifold 17 and the intake valve mounting hole 10, an intake bend 17 is connected to the thickened section of the valve mounting hole 10, and a guide valve mechanism is installed. The guide valve mechanism uses a guide pipe 32 fixed to the front of the intake valve stem 31 via a bracket. A certain distance is left between the front end of the guide pipe 32 and the intake valve head 33, forming a guide outlet 34. The guide pipe 32 penetrates the intake bend 17 and can reciprocate along the length of the intake valve stem 31 into the engine combustion chamber 4. The guide pipe reciprocates through the intake bend to close the intake manifold, and reciprocates into the engine combustion chamber to open the intake manifold. The rear end 32-1 of the guide pipe connects to the intake bend 17, and the inner cavity of the guide pipe is connected to the intake bend to form a passage, thus creating a guide valve mechanism capable of closing and opening the intake manifold. Figure 9 As shown, the air duct 32 is fixed to the intake valve stem 31 via a connecting rod or connecting rib as a bracket 35. The bracket 35 can be set between the rear end and the front end of the air duct. This embodiment uses... Figure 12The fourth type of intake valve structure. The air guide pipe 32 is inserted into the intake bend 17 and forms a clearance fit with the intake bend, which can reduce the loss of fresh air from the gap between them, and reduce or prevent contact between them, thus reducing the frictional resistance generated between the valve and the air guide pipe due to the up and down movement.
[0043] like Figure 2 As shown, the intake cam 8 of the valve train is equipped with an intake cam protrusion 81 that pushes the front end of the intake valve guide tube 32 into the engine combustion chamber 4. The intake cam 8 of this valve train is larger than a conventional intake cam protrusion; the diameter of the intake cam 8 and the length of the intake valve stem are both greater than those of the exhaust cam 10. The intake valve spring 9 is thicker than the exhaust valve spring 11, resulting in a longer stroke to push the intake valve stem and head. Figure 15 As shown, the intake valve head 33 can be pushed into the air guide area 15 between the upper part and the center position of the engine combustion chamber or near the bottom dead center position of the piston. The intake valve cam 8 pushes the intake valve head into the engine combustion chamber by matching the length of the intake cam protrusion with the depth of the intake valve head into the engine combustion chamber. Therefore, the fresh air 18 entering the engine combustion chamber can be guided and blown into the air guide area 15 by the air guide tube, achieving the purpose of deep scavenging of exhaust gas into the cylinder. This is different from the traditional engine intake valve operation method, which only makes the valve head disengage from the valve door to form an open state. The engine intake passage is connected to the exhaust pipe of the external turbocharger system or supercharger system (i.e., Roots blower), and can also be connected to the exhaust pipes of both the turbocharger system and the supercharger system at the same time. The purpose is to allow pressurized fresh air to enter the engine combustion chamber through the intake valve air guide tube.
[0044] like Figures 4 to 6 As shown, this is the gas distribution mechanism of Embodiment 2 of the present invention. The gas distribution mechanism is improved based on Embodiment 1. An arc-shaped air guide groove 19 is provided around the air guide pipe 32 on the inner wall of the intake bend 17. Since the air guide pipe 32 is inserted through the wall of the closed intake, the radial pressure of fresh air on the side wall of the air guide pipe 32 facing the intake is relatively large. In order to avoid the air guide pipe being displaced or deformed due to long-term pressure on one side, an arc-shaped air guide groove 19 is provided around the air guide pipe on the inner wall of the intake bend corresponding to the fresh air entry point. This allows fresh air to surround the air guide pipe, which can balance the gas pressure and keep the air guide pipe stable in use.
[0045] As a further improvement, such as Figure 7 and Figure 8As shown, a thickening inlet 20 can be provided in the intake bend 17, and an air guide sleeve 21 is fixedly installed in the intake valve mounting hole 10. The air guide sleeve is sleeved on the air guide pipe 32. The air guide sleeve is either an outer sleeve or nested in the rear of the air guide pipe 32. The air guide pipe 32 moves back and forth with the intake valve rod to engage the air guide sleeve 21 to close the intake passage. The air guide pipe 32 moves back and forth with the intake valve rod to disengage from the air guide sleeve, so that the rear end of the air guide pipe 32 connects to the intake bend, and thus connects to the intake passage.
[0046] like Figure 7 As shown, the air distribution mechanism in Embodiment 3 can employ a thickened inlet 20 in the intake bend, with the inner diameter of the air guide sleeve 21 inside the intake valve mounting hole 10 being larger than that of the air guide pipe 32. This sleeve is fitted over the air guide pipe, closing the air guide pipe 32 to the intake passage 2. The air guide pipe 32 reciprocates with the intake valve stem, engaging the air guide sleeve 21 to close the intake passage. Conversely, the air guide pipe 32 reciprocates with the intake valve stem, disengaging from the air guide sleeve, allowing its rear end to connect to the intake bend and thus the intake passage. Alternatively, the arc-shaped air guide groove 19, as in Embodiment 2, can be used to balance gas pressure and ensure stable operation of the air guide pipe.
[0047] like Figure 8 As shown, the gas distribution mechanism in Embodiment 4 can employ a thickened inlet 20 in the intake bend, with an air guide sleeve 21 having an inner diameter smaller than the air guide tube 32 within the intake valve mounting hole 10. This sleeve is nested inside the air guide tube, closing the air guide tube 32 to the intake passage 2. The air guide tube 32 reciprocates with the intake valve stem, engaging the air guide sleeve 21 to close the intake passage. Conversely, the air guide tube 32 reciprocates with the intake valve stem, disengaging from the air guide sleeve, allowing its rear end to connect to the intake bend and thus the intake passage. The support 35 within the air guide tube 32 is positioned from the middle to the lower part. When the intake bend is closed, the air guide sleeve is inserted into the air guide tube from the rear without interfering with the support. Alternatively, the arc-shaped air guide groove 19 as in Embodiment 2 can be used to balance gas pressure and ensure stable operation of the air guide tube.
[0048] The intake valve used in this invention can have various structures. Figure 9 This is the first type of intake valve in Embodiment 1 of this utility model. An air guide pipe 32 is fixed to the front of the intake valve stem 31, with a certain distance between the front end of the air guide pipe and the intake valve head, forming an air guide outlet 34. The air guide pipe is fixed to the intake valve stem by a bracket 35, so that the air guide pipe is stably connected to the valve stem. The bracket adopts a connecting rod or a connecting rib. The connecting rib can be in the shape of a longitudinal thin sheet, which can reduce air resistance. The air guide pipe 32 and the bracket 35 can be welded to the intake valve stem 31 or be integrally connected and fixed.
[0049] As a further improvement, a guide plate for guiding scavenging air is provided between the front end of the air guide pipe 32 and the intake valve head 33.
[0050] like Figure 10 As shown, this is the second type of intake valve according to an embodiment of the present invention. It is an improvement on the first type of intake valve. The air guide plate provided between the front end of the air guide pipe 32 and the intake valve head 33 is an elliptical thin plate 36 that is obliquely fixed to the intake valve stem. The slope surface of the elliptical thin plate and the front end of the air guide pipe form an air guide outlet 34. The structure is simple and easy to guide gas for scavenging.
[0051] like Figure 11 The image shows a third type of intake valve according to an embodiment of the present invention. It is an improvement on the first type of intake valve. The air guide plate is a sloped front end plate 37 of the air guide pipe. An air guide outlet 34 is provided on the side wall of the air guide pipe near the valve head of the front end plate. It adopts an integral structure with the air guide pipe, which is easy to assemble and manufacture. The structure is simple and easy to guide gas for scavenging.
[0052] The second and third types of intake valves allow the air guide plate to face away from the engine combustion chamber wall, causing most of the gas entering the combustion chamber to be sprayed towards the combustion chamber wall and the top of the piston. This utilizes the rebound of gas from the combustion chamber wall and piston top to scavenge the burned exhaust gases, improving exhaust gas removal efficiency. To prevent the intake valve guide tube from changing the direction of airflow due to rotation, the intake valve guide rod can be made elliptical, or a locating pin can be added to the valve guide rod and the valve guide tube to prevent rotation, or the intake guide rod hole in the cylinder head can be used to limit rotation.
[0053] like Figure 12 As shown, this is the fourth type of intake valve in the embodiment of the present invention, which is an improvement on the first type of intake valve. The air guide plate is a flared thin plate 38 fixed to the intake valve stem. The outer slope of the flared thin plate and the front end of the air guide pipe form an air guide outlet 34, which facilitates the guidance of gas to the surroundings in the engine combustion chamber. The structure is simple and easy to guide gas for scavenging.
[0054] Working methods and principles: such as Figure 1 , Figures 13 to 16 As shown, the power stroke, exhaust, intake, and compression processes of the two-stroke diesel engine using the fourth type of intake valve in Embodiment 1 are sequentially illustrated, along with its operating status at each stage. This utility model engine is a two-stroke engine, and its valve train differs from that of traditional engines. In a traditional four-stroke engine, the intake and exhaust valves open and close only once every two crankshaft revolutions. In contrast, the valve train of this engine opens and closes once for each of the intake and exhaust valves per crankshaft revolution.
[0055] The work process includes the following steps: Figure 1In the initial working state, that is, at the beginning of the power stroke, both intake valve 3 and exhaust valve 12 are closed, piston 5 is close to the top dead center position, and the protrusions of intake valve cam 8 and exhaust valve cam 10 rotate away from the valve springs. Then, the crankshaft drives the camshaft to rotate counterclockwise synchronously through the timing gear, chain, or timing belt. During the cycle, this process is also the power stroke, pushing the piston down from the top dead center, and intake valve cam 8, exhaust valve cam 11, and crankshaft 6 rotate counterclockwise. At this time, intake valve head 33 closes the intake manifold outlet, and air duct 32 closes the intake bend.
[0056] like Figure 13 As shown, the exhaust valve cam 11 is set to push the exhaust valve spring to open the exhaust valve 12 before the piston 5 moves to the bottom dead center, releasing the pressure in the engine combustion chamber. At this time, the intake valve remains closed, and the air guide pipe 32 still closes the intake bend; this allows the exhaust gas 22 after combustion to be discharged from the exhaust port 13.
[0057] like Figure 14 As shown, during the process of the intake valve moving towards the engine combustion chamber, the piston 5 continues to move to the point before the bottom dead center. The intake valve cam 8 rotates to the open intake valve state. At this time, the intake valve head 33 disengages from the intake bend outlet. The intake valve has just opened, and the air guide pipe 32 still passes through the closed intake bend. The intake passage 2 is not connected to avoid wasting compressed intake air volume.
[0058] like Figure 15 As shown, the process of intake and exhaust occurs simultaneously. The piston 5 continues to move to the bottom dead center and then gradually moves upward after passing the bottom dead center. During this process, the intake valve cam 8 pushes the intake valve head 33 into the engine combustion chamber. The air guide pipe 32 gradually passes through the intake bend, making the intake bend fully open and connecting the intake passage. The intake valve reaches its maximum opening depth, allowing the intake duct to extend into the engine combustion chamber. The fresh air 18 entering the engine combustion chamber can be guided and blown into the air guide area 15 through the air guide pipe, achieving the purpose of sweeping exhaust gas deep into the engine combustion chamber. The pressurized fresh air is sent to the bottom of the engine combustion chamber, and the burned exhaust gas is discharged outside the engine combustion chamber. After reaching the maximum depth, it retracts upward, so that the movement of the intake valve head does not interfere with or collide with the movement of the piston.
[0059] like Figure 16As shown, this illustrates the compression process of the engine piston. After scavenging, the exhaust valve 12 closes prematurely, the intake valve 3's guide pipe gradually retracts, and the guide pipe 32 moves through and closes the intake bend inlet, thus closing the intake valve. Alternatively, the exhaust and intake valves can be closed simultaneously. This position coincides with the end of the piston's fresh air exchange, the closing position of both the intake and exhaust valves, and the beginning of the compression stroke. The piston 7 then continues to move upwards to continue the air compression process. The piston continues to move upwards until it reaches top dead center, completing the compression stroke.
[0060] like Figure 1 As shown, after completing the compression stroke, the engine reaches its initial working position. Then, the air-fuel mixture is ignited, pushing the piston to perform work. The piston is near top dead center, and the fuel injector 14 operates, injecting atomized diesel fuel into the combustion chamber. Alternatively, gasoline or other combustible gases can be injected into the engine cylinder after the intake and exhaust valves are closed. Adding a spark plug transforms it into a gasoline engine. Alternatively, the engine can burn natural gas or liquefied petroleum gas (LPG). After completing one working cycle, the engine enters the next power stroke.
[0061] In Example 3, based on Example 1, a thickened inlet 17 is provided in the intake bend. The inner diameter of the guide sleeve 21 in the intake valve mounting hole of the valve train is larger than that of the guide pipe 32, and it is sleeved outside the guide pipe. The guide pipe moves with the intake valve stem, causing the guide pipe 32 and the guide sleeve 21 to fit together and separate, thus closing and opening the intake passage. The working process is similar to Example 1, as follows... Figure 17 As shown, this is the initial working state of Embodiment 2. Both the intake valve 3 and exhaust valve 12 are closed, and the piston 5 is near top dead center. At this time, the intake valve head 33 closes the intake passage, and the air guide sleeve 21 is fitted onto the rear of the air guide pipe 32, simultaneously blocking the intake bend. The air guide pipe closes the intake bend inlet. Figure 18 The diagram shown is a structural schematic of the fourth working state of Embodiment 3 of this utility model, which is a process in which intake and exhaust occur simultaneously. The piston continues to move to the bottom dead center, and the air guide pipe 32 gradually passes through the intake bend and disengages from the air guide sleeve 21, so that the intake bend is fully opened, the intake passage is connected, and the intake valve reaches the maximum opening depth, allowing the air guide pipe to extend into the engine combustion chamber. The air guide pipe 32 can be used to guide the fresh air 18 entering the engine combustion chamber into the air guide area 15, so as to achieve the purpose of sweeping exhaust gas deep into the engine combustion chamber. The use of a bend to set a thickened inlet can increase the intake volume in the connected state, and at the same time, it avoids wasting compressed intake volume when the air guide pipe has not reached the set position of the engine combustion chamber.
[0062] Example 4, based on Example 1, involves setting a thickened inlet 17 in the intake bend. The inner diameter of the guide sleeve 21 in the intake valve mounting hole of the valve train is smaller than that of the guide pipe 32, and it is nested inside the guide pipe. The guide pipe moves with the intake valve stem, causing the guide pipe 32 and the guide sleeve 21 to fit together and separate, thus closing and opening the intake passage. The working process is similar to Example 1, as follows... Figure 19 As shown, this is the initial working state of Embodiment 2. Both the intake valve 3 and exhaust valve 12 are closed, and the piston 5 is near top dead center. At this time, the intake valve head closes the intake outlet, the guide sleeve 21 is fitted onto the rear of the guide pipe 32, simultaneously blocking the intake bend, and the guide pipe closes the intake bend inlet. Figure 20 The diagram shown is a structural schematic of the fourth working state of the present invention, which is a process in which intake and exhaust occur simultaneously. The piston continues to move to the bottom dead center, and the air guide pipe gradually passes through the intake bend and disengages from the air guide sleeve, so that the intake bend inlet is fully opened, the intake passage is connected, the intake valve reaches the maximum opening depth, and the intake duct extends into the engine combustion chamber. The fresh air 18 entering the engine combustion chamber can be guided and blown into the air guide area 15 by the air guide pipe, so as to achieve the purpose of sweeping exhaust gas deep into the engine combustion chamber. The bend is designed with a thickened inlet, which can increase the intake volume in the connected state, and at the same time avoids wasting compressed intake volume when the air guide pipe has not reached the set position of the engine combustion chamber.
[0063] Figure 21 The diagram shows the valve timing of this invention. The crankshaft, intake camshaft, and exhaust camshaft rotate counter-clockwise along the coordinate axis. 'a' represents the angular range of the exhaust camshaft from opening to closing, 'b' represents the angular range of the intake camshaft from opening to closing, 'c' represents the angular range of the piston crankshaft's power stroke, and 'd' represents the angular range of the piston crankshaft's compression stroke. The intake valve can open at a position of 28 to 35 degrees before the piston reaches bottom dead center, and the exhaust valve can open at a position of 30 to 60 degrees before the intake valve opens. The intake and exhaust valves can close simultaneously or with a delay. The angle range of the protrusions on the intake and exhaust valve cams can be adjusted, reducing the engine's intake and exhaust strokes.
[0064] This invention connects the intake manifold when the air guide pipe enters the engine combustion chamber at a set position, avoiding wasted compressed air intake. Compressed air is then ejected from the air guide outlet extending into the combustion chamber for efficient scavenging, and the exhaust gas is pushed out by the combustion chamber. This ensures the engine crankshaft performs work once per revolution. Therefore, manufacturing costs are reduced, engine power is increased, and the engine achieves power output comparable to large-displacement, multi-cylinder engines with a smaller displacement and number of cylinders. It also reduces fuel consumption and maintenance costs. The design reduces engine size and weight, lowering production and maintenance costs, while also reducing the size of the engine support frame. Because independent intake and exhaust strokes are eliminated, fuel efficiency is improved. Engine stroke losses are significantly reduced, minimizing fuel consumption and mechanical wear caused by intake and compression strokes, resulting in higher thermal efficiency and greater energy savings and environmental friendliness. This invention is particularly suitable for automotive engines with long pistons.
[0065] In summary, the purpose of this utility model has been achieved.
Claims
1. A two-stroke engine with overhead valve type scavenging, comprising an engine block assembly, an overhead valve type valve train, and a two-stroke crankshaft connecting rod mechanism that drives the intake cam and exhaust cam to rotate, wherein a valve stem with an intake valve head is provided in the intake valve mounting hole of the valve train, characterized in that: An air guide switch mechanism is installed at the air intake bend where the air intake duct meets the air intake valve mounting hole; The air intake switch mechanism is as follows: an air intake pipe is fixedly installed on the intake valve stem, and an air intake outlet is provided between the air intake pipe and the intake valve head; the air intake pipe passes through the intake bend and closes the intake passage by reciprocating with the intake valve stem; the air intake pipe enters the engine combustion chamber and connects the intake passage by reciprocating with the intake valve stem. The intake cam of the valve train is provided with an intake cam protrusion that pushes the front end of the intake valve guide tube into the engine combustion chamber.
2. The overhead valve type scavenging two-stroke engine according to claim 1, characterized in that: The inner wall of the air intake bend is provided with an arc-shaped air guide groove around the circumference of the air guide pipe.
3. The overhead valve type scavenging two-stroke engine according to claim 1 or 2, characterized in that: The intake bend is provided with a thickened inlet, and an air guide sleeve is fixedly installed in the intake valve mounting hole. The air guide sleeve is sleeved on the rear of the air guide pipe. The air guide pipe moves back and forth with the intake valve rod to engage the air guide sleeve and close the intake passage; the air guide pipe moves back and forth with the intake valve rod to disengage from the air guide sleeve and open the intake passage.
4. The overhead valve type scavenging two-stroke engine according to claim 3, characterized in that: The air guide sleeve is fitted over the air guide tube.
5. The overhead valve type scavenging two-stroke engine according to claim 3, characterized in that: The air guide sleeve is nested inside the air guide tube.
6. The overhead valve type scavenging two-stroke engine according to claim 1 or 2, characterized in that: The air duct is fixed to the intake valve stem by a connecting rod or connecting rib plate as a support.
7. The overhead valve type scavenging two-stroke engine according to claim 1 or 2, characterized in that: An air guide plate is installed between the front end of the air guide pipe and the head of the intake valve to guide the scavenging air.
8. The overhead valve type scavenging two-stroke engine according to claim 7, characterized in that: The air guide plate is an elliptical thin plate that is obliquely fixed to the intake valve stem. The sloping surface of the elliptical thin plate and the front end of the air guide pipe form an air outlet.
9. The overhead valve type scavenging two-stroke engine according to claim 7, characterized in that: The air guide plate is a sloping front end plate of the air guide pipe, and an air guide outlet is provided on the side wall of the air guide pipe near the valve head of the front end plate.
10. The overhead valve type scavenging two-stroke engine according to claim 7, characterized in that: The air guide plate is a flared thin plate fixed to the intake valve stem, and the outer slope of the flared thin plate forms an air outlet with the front end of the air guide pipe.