Overhead valve guide air inlet type two-stroke engine

Abstract

The utility model provides an overhead valve guide air inlet type two-stroke engine which solves the problems that waste gas cannot be fully swept away due to the fact that a four-stroke working mode of a traditional overhead valve type engine is improved into a two-stroke working mode, and combustion efficiency and emission performance are poor. According to the technical scheme, the overhead valve guide air inlet type two-stroke engine comprises an engine body set and an air distribution mechanism provided with an overhead valve, an air guide pipe moving along with an air inlet valve rod through a support sleeve is arranged on the air inlet valve rod of the air distribution mechanism, the air guide pipe is close to the head of the air inlet valve, and a front end air outlet is reserved between the front end of the air guide pipe and the head of the air inlet valve. The rear port of the gas-guide tube communicates with the gas inlet channel; an air inlet cam of the air distribution mechanism is provided with an air inlet cam protruding part which pushes the front end of an air guide pipe of an air inlet valve to stretch into an inner cavity of the air cylinder body. By guiding and scavenging the inlet air, the engine can go deep into the cylinder body to purge the combusted waste gas, open the exhaust valve to work and fully sweep the waste gas, so that the scavenging efficiency is greatly improved, and the combustion efficiency and the emission performance are improved.

Description

Technical Field

[0001] This utility model relates to the field of internal combustion engine technology, and in particular to a top-mounted valve-guided intake 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] 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

[0003] The purpose of this invention is to provide a top-mounted valve-guided intake two-stroke engine that solves the problem that traditional top-mounted valve engines cannot fully remove exhaust gas when converted from a four-stroke to a two-stroke operation, resulting in poor combustion efficiency and emission performance. By guiding the intake air to scavenge the exhaust gas, it improves combustion efficiency and emission performance.

[0004] The technical solution adopted by this utility model is as follows: the overhead valve guided intake two-stroke engine includes an engine block assembly, a valve train mechanism with an overhead valve, and a crankshaft connecting rod mechanism that drives the intake cam and exhaust cam to rotate in a two-stroke operation. The key technical points are: the intake valve stem of the valve train mechanism has an air guide pipe that moves with the intake valve stem via a bracket, the air guide pipe is close to the intake valve head, and a front outlet is left between the front end of the air guide pipe and the intake valve head, and the rear end of the air guide pipe is connected to the intake passage; the intake cam of the valve train mechanism is provided with an intake cam protrusion that pushes the front end of the air guide pipe of the intake valve into the cylinder body cavity.

[0005] The air guide tube and the straight section of the air intake near the air inlet of the air intake channel are fitted with a clearance.

[0006] The support for the air guide tube is a connecting rod or connecting rib plate set between the inner wall of the air guide tube and the valve stem in the middle of the air guide tube.

[0007] The support for the air duct includes a front support and a rear support respectively disposed at both ends of the air duct. The front support is a connecting rod or connecting rib between the air outlet at the front end of the air duct and the valve stem or intake valve head; the rear support is a connecting rod or connecting rib between the rear end of the air duct and the valve stem.

[0008] The air outlet at the front end of the air duct is set as an angled port facing away from the exhaust valve.

[0009] The air duct wall is provided with multiple air outlets.

[0010] The advantages and beneficial effects of this utility model are as follows: Because this overhead valve guided intake two-stroke engine uses an overhead valve valve train and a crankshaft connecting rod mechanism operating in a two-stroke manner, it forms an independent lubrication system and completes one power stroke per crankshaft rotation. Furthermore, it employs an air guide pipe that moves with the intake valve stem and is fixedly mounted on the intake valve stem of the valve train. An outlet is left between the front end of the air guide pipe and the intake valve head. An intake cam protrusion is also provided on the intake cam of the valve train to push the intake valve head into the cylinder cavity. The intake cam's operation controls the air guide pipe's extension into the cylinder cavity, forming a guide area. Therefore, fresh air entering the cylinder can be guided into this guide area via the air guide pipe, achieving deep scavenging of the exhaust gas after combustion within the cylinder. This opens the exhaust valve, thoroughly scavenging the exhaust gas and greatly improving scavenging efficiency. This avoids the problem of traditional intake valves only scavenging exhaust gas at the valve opening, resulting in low scavenging efficiency. This improves combustion efficiency and emission performance. Combined with the two-stroke operating mode, it significantly enhances engine efficiency. Attached Figure Description

[0011] The present invention will be further described below with reference to the accompanying drawings.

[0012] Figure 1 This is a structural schematic diagram of an embodiment of the present utility model;

[0013] Figure 2 This is a schematic diagram of the first intake valve structure according to an embodiment of the present utility model;

[0014] Figure 3 yes Figure 2 A schematic diagram of the longitudinal sectional view of the structure;

[0015] Figure 4 This is a schematic diagram of a second intake valve structure according to an embodiment of the present invention;

[0016] Figure 5 This is a schematic diagram of a third intake valve structure according to an embodiment of the present invention;

[0017] Figure 6 This is a schematic diagram of the fourth intake valve structure according to an embodiment of the present utility model;

[0018] Figure 7 This is a schematic diagram of the fifth intake valve structure according to an embodiment of the present utility model;

[0019] Figure 8 This is a structural schematic diagram of the second working state of an embodiment of this utility model;

[0020] Figure 9 This is a structural schematic diagram of the third working state of an embodiment of this utility model;

[0021] Figure 10 This is a structural schematic diagram of the fourth working state of an embodiment of this utility model;

[0022] Figure 11 This is a structural schematic diagram of the fifth working state of an embodiment of this utility model;

[0023] Figure 12 This is a schematic diagram of the fifth intake valve working state structure according to an embodiment of this utility model;

[0024] Figure 13 This is a schematic diagram of the gas distribution phase of this utility model.

[0025] The numbers in the diagram are explained as follows: 1. Cylinder head, 2. Intake passage, 3. Intake valve, 4. Cylinder block, 5. Piston, 6. Crankshaft, 7. Crankcase, 8. Intake valve cam, 9. Intake valve spring, 10. Exhaust valve cam, 11. Exhaust valve spring, 12. Exhaust valve, 13. Exhaust port, 14. Fuel injector, 15. Air guide area, 21. Straight section intake port, 31. Valve stem, 32. Air guide pipe, 33. Intake valve head, 34. Front exhaust port, 35. Rear port, 36. Bracket, 37. Exhaust port, 81. Protrusion. Detailed Implementation

[0026] according to Figure 1-13 This utility model will be described in detail, and its implementation will be illustrated by examples. Figure 1As shown, a two-stroke engine with overhead valve guided intake 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 overhead 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 has a straight intake port 21 connecting the intake passage 2 and the intake port. The intake valve head 33 can block and open the intake port. 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. The improvements are as follows: Figures 1 to 3 As shown, the intake valve stem 31 of the valve train is fixedly fitted with an air guide tube 32 via a bracket 36 at its front. The air guide tube is movably positioned within the straight section of the intake port 21 that connects the intake channel 2 and the intake inlet. The air guide tube can move with the intake valve stem. A clearance fit can be formed between the inner wall of the straight section of the intake port 21 and the air guide tube 32, which can reduce the loss of fresh air through the gap between them and reduce or prevent contact between them, thus reducing the frictional resistance generated between the valve and the air guide tube due to the up-and-down movement of the valve. Figure 2 and Figure 3 As shown, the intake valve stem 31 of the intake valve has a disc-shaped intake valve head 33 at its front end. A certain distance is left between the front end of the air guide pipe and the intake valve head to form a front outlet 34. The rear end 35 of the air guide pipe is connected to the intake channel 2, so that the inner cavity of the air guide pipe forms a passage connecting the intake channel and the intake port. The intake cam 8 of the valve train is provided with an intake cam protrusion 81 that pushes the front end of the air guide pipe 32 of the intake valve into the inner cavity of the cylinder block 4. The intake cam 8 of this valve train has a larger cam protrusion than conventional intake cams. 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. This allows the intake valve head to extend into the air guide area 15 between the upper part of the cylinder cavity and the center position or near the bottom dead center of the piston. The length of the intake cam protrusion and the depth of the intake valve head extending into the cylinder cavity can be matched by the air guide tube. Therefore, fresh air entering the cylinder can be guided into the air guide area through the air guide tube to achieve the purpose of deep scavenging of exhaust gas into the cylinder cavity. This is different from the traditional intake valve operation method of engines, which only makes the valve head disengage from the valve door to form an open state. The engine's intake passage is connected to the exhaust pipe of an external turbocharger or supercharger system (i.e., a Roots blower), or it can be connected to the exhaust pipes of both the turbocharger and supercharger systems. The purpose is to allow pressurized fresh air to enter the engine's combustion chamber through the intake valve's duct.

[0027] As a further improvement, such as Figure 3As shown, the support 36 of the air guide tube 32 can be a connecting rod or connecting rib between the inner wall of the air guide tube and the valve stem 31 in the middle of the air guide tube, so that the air guide tube is stably connected to the valve stem. The connecting rib can be in the shape of a longitudinal thin sheet, which can reduce air resistance. The air guide tube and the support can be connected and fixed by welding to the intake valve stem or by an integral structure.

[0028] As a further improvement, such as Figure 3 and Figure 4 As shown, the support 36 of the air duct 32 can be constructed by including a front support and a rear support respectively disposed at both ends of the air duct. The front support is a connecting rod or connecting rib near the air duct port 34 at the front end of the air duct and the valve stem 31, and the rear support is a connecting rod or connecting rib near the rear end 35 of the air duct and the valve stem 31. This structure can securely connect the air duct to the intake valve and reduce obstruction of the air duct's internal passage. Figure 5 As shown, the front bracket can also use a connecting rod or connecting rib plate near the front air inlet of the air duct and the valve head to increase stability. The connecting rib plate can be in the shape of a longitudinal thin sheet to reduce air resistance.

[0029] As a further improvement, such as Figure 6 As shown, the front air inlet 34 of the air guide pipe 32 can be configured as an angled port facing away from the exhaust valve. The outlet at the lower part of the air guide pipe is inclined to the direction of the intake valve head, so that when the fresh gas is ejected from the front air guide port, it is directed towards the inner wall of the cylinder body away from the exhaust valve. This allows most of the gas entering the cylinder body to be sprayed towards the cylinder wall and the top of the piston. The gas rebounds from the inner wall of the cylinder body and the top of the piston to clean up the combusted exhaust gas, thus better removing the combusted exhaust gas from the cylinder body and increasing the efficiency of exhaust gas cleaning. To prevent the air guide pipe of the intake valve from changing the direction of air blowing due to rotation, the valve guide rod of the intake valve can be made into an ellipse, or an anti-rotation locating pin can be made on the valve guide rod and the air guide pipe of the valve, or the intake guide rod hole in the cylinder head can be used to limit and prevent rotation.

[0030] As a further improvement, such as Figure 7 As shown, multiple air outlets 37 can be provided on the wall of the air guide pipe 32, so that gas can be continuously injected and exhaust gas can be swept out as the air guide pipe extends into the cylinder body from the air inlet.

[0031] Working methods and principles: such as Figure 1 , Figures 8 to 13As shown, the power stroke, exhaust, intake, and compression processes of a two-stroke diesel engine with valves are sequentially displayed, along with the operating states 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, while in this engine, the intake and exhaust valves each open and close once per crankshaft revolution.

[0032] The work process includes the following steps: Figure 1 In 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 spring position; 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 to move downward from the top dead center, and intake valve cam 8, exhaust valve cam 10 and crankshaft 6 rotate clockwise.

[0033] like Figure 8 As shown, the exhaust valve cam 10 is set to push the exhaust valve spring 11 to open the exhaust valve 12 before the piston 5 moves to the bottom dead center, releasing the pressure in the combustion chamber. At this time, the intake valve remains closed, so that the exhaust gas after combustion can be discharged from the exhaust port 13.

[0034] like Figure 9 As shown, before the piston 5 continues to move to the bottom dead center, the intake valve cam 8 rotates to the open intake valve state. At this time, the intake valve has just opened and begins to send fresh air into the cylinder to carry out the intake process.

[0035] like Figure 10 As shown, the process of intake and exhaust occurs simultaneously. The piston 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 cylinder cavity, so that the intake valve reaches the maximum opening depth. This allows the intake duct to extend into the cylinder, and the fresh air entering the cylinder can be guided into the air guide area 15 through the air guide to achieve the purpose of sweeping exhaust gas deep into the cylinder. The pressurized fresh air is sent to the bottom of the cylinder and the combusted exhaust gas is discharged from the cylinder. 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.

[0036] like Figure 11As shown, this illustrates the compression process of the engine piston. After scavenging, exhaust valve 12 closes prematurely, and the intake valve 3 guide gradually retracts, 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 start of the compression stroke. 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.

[0037] like Figure 1 As shown, once the engine reaches its initial operating position, the air-fuel mixture is ignited, pushing the piston to perform work. With the piston near top dead center, 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.

[0038] like Figure 12 The diagram shown is a schematic of the fifth intake valve working state structure according to an embodiment of this utility model. The intake valve 3 uses the front end of the air guide pipe 32 with an angled air guide port 34. The front end of the air guide pipe extends into the air guide area between the upper part of the cylinder body cavity and near the bottom dead center of the piston for scavenging. The closer the front end of the air guide pipe is to the bottom dead center of the piston, the better the scavenging effect. The optimal position is to extend the front end of the air guide pipe into the air guide area between the bottom dead center of the piston and the center of the cylinder body cavity (making the air guide pipe close to the top of the piston). The air guide pipe wall is provided with multiple air outlets 37, so that when some fresh gas is ejected from the front end of the air guide port, it is directed towards the cylinder body wall away from the exhaust valve. The gas rebounds from the cylinder body wall to scavenge the exhaust gas, increasing the efficiency of exhaust gas scavenging.

[0039] Figure 13 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.

[0040] This invention enables the engine crankshaft to perform work once per revolution.

[0041] In summary, the purpose of this utility model has been achieved.

Claims

1. A two-stroke engine with overhead valve guided intake, comprising an engine block assembly, a valve train with overhead valves, and a crankshaft connecting rod mechanism that drives the intake cam and exhaust cam to rotate, characterized in that: The intake valve stem of the valve train has an air guide tube that moves with the intake valve stem via a bracket. The air guide tube is close to the intake valve head, and there is a front air guide port between the front end of the air guide tube and the intake valve head. The rear end of the air guide tube is connected to the intake passage. The intake cam of the valve train is provided with an intake cam protrusion that pushes the front end of the air guide tube of the intake valve into the cylinder body cavity.

2. The overhead valve guided intake two-stroke engine according to claim 1, characterized in that: The air guide tube and the straight section of the air intake near the air inlet of the air intake channel are fitted with a clearance.

3. The overhead valve guided intake two-stroke engine according to claim 1 or 2, characterized in that: The support for the air guide tube is a connecting rod or connecting rib plate set between the inner wall of the air guide tube and the valve stem in the middle of the air guide tube.

4. The overhead valve guided intake two-stroke engine according to claim 1, characterized in that: The support for the air duct includes a front support and a rear support respectively disposed at both ends of the air duct. The front support is a connecting rod or connecting rib between the air outlet at the front end of the air duct and the valve stem or intake valve head, and the rear support is a connecting rod or connecting rib between the rear end of the air duct and the valve stem.

5. The overhead valve guided intake two-stroke engine according to claim 1, characterized in that: The front end of the air duct is set as an angled port facing away from the exhaust valve.

6. The overhead valve guided intake two-stroke engine according to claim 1, characterized in that: The air duct wall is provided with multiple air outlets.

7. The overhead valve guided intake two-stroke engine according to claim 3, characterized in that: The air outlet at the front end of the air guide pipe is set as an oblique port facing away from the exhaust valve, and the wall of the air guide pipe is provided with multiple air outlet holes.

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